Operation of a vaporizer of a domestic appliance

Abstract

In a method for operating a vaporizer of a domestic appliance, the vaporizer is filled at least to a predetermined filling level. The vaporizer can be emptied using an emptying arrangement. A time measurement is started, when a filling level falls below the predetermined filling level. A heating system of the vaporizer is switched on, when the filling level falls below the predetermined filling level. The time measurement is stopped, when the heating system has overheated, and a delivery output is calculated during emptying of the vaporizer, from a duration for emptying that is determined by the time measurement.

Claims

1. A method for operating a vaporizer of a domestic appliance, said method comprising the steps of: (i) filling the vaporizer at least to a predetermined filling level; (ii) emptying the vaporizer using an emptying arrangement which includes a pump; (iii) starting a time measurement when a filling level falls below the predetermined filling level; (iv) switching on a heating system of the vaporizer when the filling level falls below the predetermined filling level; (v) stopping the time measurement when the heating system has overheated; and (vi) calculating a delivery output of the pump during emptying of the vaporizer, from a duration for emptying that is determined by the time measurement, thereby to avoid the pump from running dry.

2. The method of claim 1, wherein the step (i) comprises filling the vaporizer beyond the predetermined filling level.

3. The method of claim 1, wherein the step (iv) comprises switching on the heating system directly when the level falls below the predetermined filling level.

4. The method of claim 1, wherein the step (iv) comprises switching on the heating system with a defined delay when the level has fallen below the predetermined filling level.

5. The method of claim 1, further comprising switching off the heating system when the heating system has overheated in step (v).

6. The method of claim 1, wherein the step (vi) comprises dividing a liquid volume of the vaporizer by the emptying duration.

7. The method of claim 1, further comprising, after the step (vi), the steps of: (a) filling the vaporizer at least to the predetermined filling level; (b) establishing a duration for filling to the predetermined filling level; and (c) calculating a delivery output during filling by dividing a liquid volume of the vaporizer by the duration for filling.

8. The method of claim 7, wherein in normal operation filling of the vaporizer is stopped, when a safety threshold value that is determined based on the delivery output during filling is reached or exceeded.

9. The method of claim 1, further comprising executing the steps (i) to (vi) only in an abnormal operation where there is an absence of a vapor processing of food.

10. A vapor processing appliance, comprising: a vaporizer including a level detector configured to detect a predetermined filling level, a heating system, and an overheating detector configured to determine when the heating system has overheated; a filling arrangement for filling the vaporizer at least to a predetermined filling level; an emptying arrangement which includes a pump for emptying the vaporizer; a time measuring arrangement responsive, when a filling level falls below the predetermined filling level, thereby causing switching on of the heating system, said time measuring arrangement being configured to stop a time measurement when the heating system has overheated; and a calculating arrangement configured to at least calculate a delivery output of the pump during emptying of the vaporizer, from a duration for emptying that is determined by the time measurement arrangement, thereby to avoid the pump from running dry.

11. The vapor processing appliance of claim 10, wherein the vapor processing appliance comprises a steam cooking appliance.

12. The vapor processing appliance of claim 10, wherein the vaporizer has a receiving chamber for liquid, said heating system being configured as a surface heating system which is arranged on a base of the receiving chamber, said receiving chamber capable of being filled via the filling arrangement and emptied via the emptying arrangement.

13. The vapor processing appliance of claim 10, wherein the heating system serves as an overheating detector.

14. The vapor processing appliance of claim 10, wherein the filling arrangement includes a pump or is a pump.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The properties, features and advantages of this invention that have been described above, and the way in which they are achieved, will become clearer and more readily understood in conjunction with the schematic description below of an exemplary embodiment that is explained in more detail in conjunction with the drawings.

(2) FIG. 1 shows, as an exploded illustration in perspective view, a vaporizer that is suitable for performing the method according to the invention;

(3) FIG. 2 shows, as a sectional illustration in side view, a vapor processing appliance having the vaporizer from FIG. 1;

(4) FIG. 3 shows, as a sectional illustration in side view, a detail of the assembled vaporizer;

(5) FIG. 4 shows an exemplary embodiment of the method when emptying the vaporizer, by way of a flow chart; and

(6) FIG. 5 shows an exemplary embodiment of the method when filling the vaporizer, by way of a flow chart.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

(7) FIG. 1 shows, as an exploded illustration in perspective view, a vaporizer 1 that is provided for example for use in a domestic appliance H (see FIG. 2), for example in an independent steam cooker or a baking oven with steam cooker function.

(8) The vaporizer 1 has a base part 2 with a region 3 in the base and, attached thereto, a peripheral rim 4 that projects toward the front. The region 3 in the base has in this case, by way of example, a planar basic shape with a rectangular outer contour A having rounded edges. In the region 3 in the base there are at least two openings, in this case comprising a water passage opening 5 and a leadthrough opening 6 for leading through an electrical connector. A plurality of resilient latching tabs 7 extends upward from the rim 4. Moreover, at least one securing tab 8 protrudes toward the rear, for example for screwing to the domestic steam cooking appliance H.

(9) The region 3 in the base is covered, sealingly and over the entire inside surface, by an electrically operated surface heating system 9. On its rear side, the surface heating system 9 has an electrical connector 10 that projects through the leadthrough opening 6. Further, the surface heating system 9 has a hole 11 that is congruent with the water passage opening 5. Water can be introduced and drained away through the hole 11 and the water passage opening 5.

(10) The surface heating system 9 may be heated over its surface and for this purpose may for example have an electrically conductive surface 9a facing the liquid. Moreover, it has a film (for example internally) that, when a predetermined threshold temperature is exceeded, becomes electrically conductive. Thus, a pronounced change in the electrical conductivity or the electrical resistance or a current that may be conducted through this film indicates that the threshold temperature has been reached and thus also that overheating has started. The threshold temperature may be for example around 200 C. The surface heating system 9 thus at the same time serves as an overheating detector for establishing that it has overheated.

(11) Optionally, the surface heating system 9 has at least one heatable or heated partial region or at least one heated zone B1 and at least one unheated partial region or at least one unheated zone B2. While for example at least one heat conductor is laid to the heated zone B1 (for example in the shape of a coil), it is not present in the unheated zone B2. In the switched-on condition, the heated zone B1 is at a temperature above a predetermined temperature T, while in the switched-on condition the unheated zone B2 is at a temperature below the predetermined temperature T. In particular, this may greatly agitate or even boil the water in the heated zone B 1, while the water, or its free surface, remains comparatively still in the unheated zone B2. The unheated zone B2 in this case occupies at least a corner region of the surface heating system 9.

(12) Placed together, the surface heating system 9 and the cover 13 form a receiving chamber R for water. The surface heating system 9 in this case forms the base of the receiving chamber R.

(13) Seated on the rim 4 over a peripheral seal 12 is a domed or dish-like cover 13. The seal 12 may be drawn, for example at the rim, onto the surface heating system 9 and seal it off from the region 3 in the base and the cover 13. The cover 13 has on the outside a plurality of latching lugs 14 that are provided for engagement with the latching tabs 7 and enable a simple latching connection between the base part 2 and the cover 13. The cover 13 has, in its opposite upper wall 15 to the base part 2 and spaced therefrom, two holes (not illustrated) for leading through electrically conductive contact pins 16, in particular metal pins. The contact pins 16 are left free in the receiving chamber R.

(14) The two contact pins 16 end in particular at the same height on the underside and are electrically connected to one another by water in the receiving chamber R or 2, 13 once the water reaches a predetermined (in particular upper) filling level L1 (see also FIG. 3). The fact that this electrical short circuit has been established can be used to determine the predetermined filling level L1, for example by a control system 24 (see also FIG. 2). The control system 24 may apply a low alternating voltage to the contact pins 16 in order to eliminate electrolytic effects.

(15) Once the predetermined filling level L1 has been reached, the vaporizer 1 is filled with a volume V of water.

(16) The contact pins 16 lie above the unheated zone B2 of the surface heating system 9 in order to enable more reliable determining of a predetermined upper filling level L1, in particular little influenced by agitation of the water surface.

(17) A vapor outlet 18 is located on a peripheral side wall 17 of the cover 13, close to the upper wall 15. The vapor outlet 18, which in this case takes the form for example of a pipe socket, may be attached for example to a hose for guiding the vapor that is generated by the vaporizer in the food processing chamber S of the domestic steam cooking appliance H. The vapor outlet 18 is arranged above the unheated zone B2, so that no small drops of water that are produced by agitated water in the heated zone B1 are carried along by the stream of vapor. This improves the quality of the vapor. The fewer water droplets there are in the stream of vapor, the higher its energy content and thus the efficiency. Furthermore, the material for cooking, or food, in the food processing chamber S is prevented from being damaged by the water droplets.

(18) FIG. 2 shows, as a sectional illustration in side view, a domestic steam cooking appliance H that has the vaporizer from FIG. 1. The domestic steam cooking appliance H has a tap water connector 20 that is connected, by way of a filling pump 21 that serves as the filling arrangement, to the water passage opening 5 of the vaporizer 1. Further, the vaporizer 1 is connected through its water passage opening 5, by way of a drainage pump 22 that serves as the emptying arrangement, to a wastewater connector 23 of the vaporizer 1. Operation of the filling pump 21 and the drainage pump 22 is controlled by way of a control system 24. The control system 24 is also connected to the contact pins 16 and may establish that there is a short circuit across the contact pins 16.

(19) The control system 24 may be for example a central control system of the domestic steam cooking appliance H, which may for example also control further functions such as operation of the surface heating system 9 of the vaporizer 1 and/or at least one heating arrangement (not illustrated) for heating a food processing chamber S.

(20) The water passage opening 5 is illustrated here as taking the form of two spatially separated openings, a water inlet opening and a water outlet opening, but may be a joint water passage opening (that is to say a combined water inlet and water outlet opening), as in FIG. 1.

(21) During operation of the vaporizer 1 for the vapor processing of food, vapor is introduced into the where appropriate heated-up food processing chamber S of the domestic steam cooking appliance H, by way of the vapor outlet 18 of the vaporizer 1. For this purpose, first water is pumped into the receiving chamber R by means of the filling pump 21 until a short circuit between the contact pins 16 establishes that the predetermined filling level L1 that is shown in FIG. 3 has been reached. Once the fact of the short circuit, and hence of the predetermined filling level, has been established, the filling pump 21 is stopped immediately or after a defined delay (e.g. between 1 second and 3 seconds). The surface heating system 9 that is then activated allows the water to vaporize, with the result that the water level falls. When the water level falls below the filling level L1, the short circuit created by the water is removed again and the control system 24 activates the filling pump 21 again for filling the receiving chamber R with water, and so on. Typically in this context, the filling pump 21 is activated twice to three times a minute, for five to seven seconds each time. The construction of the vaporizer 1 enables the water that is introduced to be vaporized particularly rapidly and without delay, for example as a result of the introduction of energy over a large surface area by means of the surface heating system 9, and as a result of a small predetermined filling level L1 in the millimeter range, for example between eight and ten millimeters, preferably 9 mm.

(22) As is further shown in FIG. 3, partition walls 25 and 26 project internally into the receiving chamber R from the upper wall 15 of the cover 13. At least one of the partition walls 25 and 26 crosses a region between the two contact pins 16 and hence lengthens a path between the contact pins 16. This lengthens an electrical creepage distance between the two contact pins 16, which may be formed as a result of a fine coating of water-absorbing lime scale on the inside of the cover 13.

(23) As illustrated in FIG. 4, the vaporizer 1 may also be operated such that at least the delivery output Le of the drainage pump 22 may be determined or calibrated when the vaporizer 1 or its receiving chamber is emptied. In this context, the vaporizer 1 is operated in an abnormal operation or using an abnormal program that does not serve for the vapor processing of food. This abnormal operation may be carried out for example on first start-up of the domestic steam cooking appliance H, after a power recovery, following certain maintenance programs, as part of a descaling program and/or in the context of a function test of the drainage pump 22.

(24) For this purpose, controlled by a control system 24, in a step S1 the vaporizer 1 is filled by means of the filling pump 21 to slightly above its predetermined filling level L1 such that the contact pins 16, which serve as level detectors, are short circuited. This is identified by a control system 24. The control system 24 then stops the filling pumps 21 and, in a step S2, starts the drainage pump 22. This empties the vaporizer 1 or its receiving chamber R.

(25) In a subsequent step S3, once at least one of the contact pins 16 is no longer covered with water and consequently the level falls below the upper filling level, at a starting time t0 a time measurement Z0 is started (for example by the control system 24) by means of a time measuring arrangement, or timer, that is integrated in the control system 24.

(26) In a step S4, directly once the time measurement Z0 begins or with a predetermined delay, the surface heating system 9 is switched on. As the time progresses, the vaporizer 1 empties. Then the surface heating system 9 overheats with only a slight time delay, and this fact may be established for example by the control system 24. The control system 24 then stops the time measurement, in a step S5, at an end time t1. The control system 24 moreover disconnects or switches off the surface heating system 9 and stops the drainage pump 22.

(27) In a further step S6, the control system 24, which also serves as a calculating arrangement, calculates the delivery output Le of the drainage pump 22, for example using equation (1) or equation (2).

(28) FIG. 5 shows an exemplary embodiment of the method, including a filling that follows the emptying according to steps S1 to S6.

(29) Here, the previously emptied vaporizer 1 is filled again, in a step S7, by means of the filling pump 21. As filling of the vaporizer 1 begins, a time measurement Z1 is started at a starting time t2, for example by means of the control system 24. Once the water reaches the contact pins 16, the upper filling level L1 is reached.

(30) At this end time t3, the control system 24 then stops the time measurement Z1 and, in a step S8, establishes a duration tb=t3t2 required for filling the receiving chamber R up to the filling level L1.

(31) In a subsequent step S9, the control system 24 calculates a delivery output Fb during filling by means of dividing the known volume V of water at the upper filling level L1 by the duration tb in a manner similar to equation (1) or similar to equation (2), for example.

(32) The present invention is of course not restricted to the exemplary embodiment that is shown.

(33) In general, the terms a, an and so on may be understood as singular or plural, in particular in the context of at least one or one or more and so on, provided this is not explicitly ruled out, for example by the expression precisely one and so on.

(34) It is also possible for a numerical specification to comprise precisely the specified number and also a conventional tolerance range, provided this is not explicitly ruled out.