EP1774554B1 - Device for connecting a plurality of heating devices of a cooking appliance, and cooking appliance comprising one such device - Google Patents

Abstract

An appliance for a hotplate has two heating devices installed parallel to one another. With an energy control device and as a function of an angular position, either a first heating device is operated in controlled manner or a second heating device is connected thereto in fixed form. The power of the second heating device is defined so low that no temperature limiter for protecting a glass ceramic plate has to be provided in the control path of the second heating device. On connecting in the second heating device, the controlled power of the first heating device is lowered to an initial value by roughly the amount of the power of the second heating device. The total power results from the summated power of the two heating devices.

Description

Field of application and state of the art

The invention relates to a device for switching or switching on and off of several heating devices of a cooking appliance and a cooking appliance with such a device.

Radiant heater with a certain diameter, which is greater than 230 mm, for example, have the problem that their energy supply by so-called energy control devices on the one hand and overtemperature protection for a glass ceramic plate above the radiant heater by so-called temperature limiter on the other hand limited by maximum achievable benefits and a so-called Flicker standard are. The Flicker standard states how often in a certain time a particular power can be switched on or off with a cooking appliance and should prevent larger network perturbations in the sense of the energy supply companies.

The switching capacity of both the energy control devices and the temperature limiter, which work with so-called snap-action switches, as for example in the EP 898 291 A and the DE 33 33 645 A are usually limited. For example, for the US, these are 12 and 13 amps respectively. This is because 100,000 switching cycles must be achievable.

At usually given mains voltage thus a further increase in the power of a radiant heater is not possible.

The US-A-5847636 shows a device for switching a plurality of heaters, for example in a hob. It has more than two switching devices, in addition to an adjustable by turning clocking switch several contact switch. These contact switches are each switched at different locations or in different rotational positions.

Task and solution

The invention has for its object to provide an aforementioned device and a cooking appliance, with which the disadvantages of the prior art can be avoided and in particular the activation of another heater to increase the heat output of a cooking stove can be achieved with the least possible effort.

This object is achieved by a device having the features of claim 1 and a cooking appliance with the features of claim 7. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. The wording of the claims is incorporated herein by express reference. For the purposes of this application, "having" means that this feature may be provided inter alia, independently of other features.

According to the invention, this object is achieved in that the device has a clocking energy control device, as for example from the aforementioned EP 898 291 A is known, which has a change in distance for a trip path of a first switching device, which is included in the power control unit. The change in distance, in turn, can be influenced by a set adjustment path on the energy control device, for example by a rotary movement by means of a rotary knob of the energy control unit. The trip path in turn defines the on or off times or their relationship to each other, with which the heater is either disabled or activated at full power. By the clock ratio or the length of the respective on and off times, the so-called average energy production can take place or results in the so-called average power. At one point of the trip path, a second trip point is provided, on which a second switching device is activated or turned on, with which a second heating device can be activated. This second heating device is advantageously an additional heater for the first heating device.

If both heaters form a cooking point, it is possible in this way that the power for the second heater does not have to be switched via the same first switching device which also switches the first heating device. This means that larger heating capacities are possible at a cooking place than before.

According to the invention, the change in distance is designed such that it resets the triggering path for the first switching device to an initial value at the second triggering point for the definition of the on and off times and their relationship to one another, wherein the triggering path is then changed again as the adjustment path increases further, especially in the same direction as before. In other words, the change in distance causes the triggering path to increase from an initial value to the second triggering point, in each case with an overall increasing adjustment travel, and thus correspondingly influences the first shifting device. At the second triggering point, the second heating device is activated via the second switching device in addition to the first heating device. The triggering for the first heating device in turn is reset and thus also their average power output over a certain period of time, so for example at a Cooking device set to a low level again. According to the invention, this second triggering point is set so that the average power generated by the first heating device until shortly before the second triggering point corresponds to that which then generates the second heating device. The average power generated by the first heater from the second trigger point is again greatly reduced and begins with increasing Setting path and increasing triggering path to rise again. Thus, at the second trigger point, a certain constant value of the average power is generated by the second heating device. The variable component, which can be influenced by the energy control device at the first heating device in its height, then comes again in an increasing manner from the heater. An advantage with this arrangement is that only the first heater must be clocked, namely with a slightly lower power than the total average power generated.

The device may include or be connected to a temperature limiter, which is arranged in the effective range of the first heating device, under certain circumstances also in the effective range of the second heating device. This temperature limiter can be formed, for example, as described in the aforementioned De 33 33 645 A and switch off the first heating means when a certain temperature is exceeded, in particular for the protection of a glass ceramic plate arranged above the heating device. For this purpose, the temperature limiter may have a switch in the connection path for the first heating device.

As stated above, the clocking power control device may be designed as an electromechanical device such that the adjustment path is influenced by a linear movement or preferably a rotary movement. When turning it should be slightly less than 360 °. About the change in distance, the rotational movement is converted into a substantially rectilinear tripping. For this purpose, the energy control unit or the change in distance, for example, have a rotary shaft with a non-circular running disk, at the outer edge of a part of a switching device and the first switching device is applied. Their switching behavior with respect to the on-off times or their relationship to each other depends on the variable triggering path, ie the variable radius of the disc. For the second trigger point, a similar, triggering can be provided, in particular by a non-circular disc or a kind of cam. At the second trip point, this disc or cam activates the second switching device to turn on the second heater. Here, however, no continuously changed radius is required because no increasing trip path is required.

The second trigger point at which the second heater detaches the generation of the heating power from the first heater, so to speak, may preferably be set so that the average power of the first heater at that point is less than half the maximum total power, for example, about one One-third. At such a point, usually for cooking or cooking, the transition between cooking, such as liquids, and frying, such as meat in a pan, takes place. The particularly advantageous with the invention particularly large heating capacities at a cooking area are in addition to the fastest possible boiling of pots with water for such frying with high performance advantage.

In a cooking appliance according to the invention two heaters may be provided for a cooking area, wherein the cooking appliance is a hob with a glass ceramic plate and radiant heaters underneath and may have a plurality of such cooking zones. The second heating device has a maximum continuous power corresponding to a power density of about 2.5 W per cm ² . With this value, the second heating device can generally be operated without temperature monitoring against overheating of the glass ceramic plate. Thus, no temperature monitoring against overheating of the glass ceramic needs to be provided for the second heating device or its operation. The power density can also be chosen over 2.5 W / cm ² , if the Specifications or tests of the manufacturer of the glass ceramic give this or permit.

The two heaters are advantageously electrically separated from each other. In particular, they are contained in a so-called single-circuit radiator in contrast to two-circuit radiators, which allow a size extension of a cooking area for larger cooking vessels. It may be provided that the first heating device and the second heating device consist of elongated heating resistors, in particular in flat band form, which are laid in a spiral or meandering shape on a surface. In this case, the two heating devices can each extend in parallel as heating strips and cover the same total area overall. Thus, in such a cooking zone of a hob by the second heater not an enlarged heating surface is achieved, but on a constant heating surface an increased heating capacity.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections as well as intermediate headings does not restrict the general validity of the statements made thereunder.

Brief description of the drawings

Fig. 1

eine Schaltungsanordnung gemäß einem Erfindungsaspekt,

Fig. 2

eine Anordnung von zwei Nockenscheiben auf einer Drehwelle eines Energiesteuergeräts mit zwei Schalteinrichtungen,

Fig. 3

eine Draufsicht auf eine mögliche Anordnung von zwei Heizein- richtungen an einer Kochstelle eines Kochfeldes,

Fig. 4

eine Seitenansicht der Anordnung aus Fig. 3 bei einem Koch- feld und

Fig. 5

ein Diagramm der Verteilung der mittleren Leistung abhängig von der Winkelstellung einer Einstellung an dem Energiesteu- ergerät nach Fig. 2.

Embodiments of the invention are shown schematically in the drawings and will be explained in more detail below. In the drawings show:

Fig. 1

a circuit arrangement according to an aspect of the invention,

Fig. 2

an arrangement of two cams on a rotary shaft of a power control device with two switching devices,

Fig. 3

a top view of a possible arrangement of two heating devices at a hotplate of a hob,

Fig. 4

a side view of the arrangement Fig. 3 in a hob and

Fig. 5

a diagram of the distribution of the average power depending on the angular position of a setting on the power control device after Fig. 2 ,

Detailed description of the embodiments

In Fig. 1 a functional diagram of a device 11 according to the invention is shown, with which a first heating device 13 and a second heating device 15 can be controlled. These form a common hotplate 19, as seen from Fig. 3 can be removed. It should be noted that the two heaters 13 and 15 do not form a basic and an additional heating zone, but both heat approximately the same area. The second heating device 15 serves only to provide additional heating power on the surface of the hotplate 19.

Both heaters 13 and 15 may be so-called radiant heaters, as shown for example in the EP 590 315 A are described, to which express reference is made. They are operated with mains voltage, in Germany for example 230V and in the USA 120V - 240V. Their operation is usually carried out in a clocking manner such that a heating device either rests on the supply voltage and operates at full power or is disconnected from the supply voltage and is thus deactivated. The amount of energy production takes place over a certain period of time not by lowering the supply voltage for continuous operation, but by clocking with on-times and off-times. By the clock ratio or the duration of the respective on and off times, the so-called average power generation can take place or results in the so-called average power.

In the present example, the first heater 13 is clocked to determine the height of the average continuous power, as well as the second heater 15. For the control of the heaters in the aforementioned manner with on and off times in a clocking manner is a Energy control device 21 is provided. A similar power control device 21 is, for example, in the aforementioned EP 898 291 A or the DE 102 004 020 977 A described, which is expressly referred to. By a rotational movement of a knob 22 by an operator, a certain cooking level can be set, which determines the height of the average power of the heaters or hotplate 19 over a long period of time. The knob 22 is seated on a rotary shaft 23. In response, the power control device 21 turns on and off the first heater 13 with the illustrated first switching device 24.

How out Fig. 2 can be seen, a first shift drum 27 is mounted on the rotary shaft 23, which has a certain course. At the first shift drum 27 is located on a slider 26 which carries the first switching device 24 with the contacts 25. The switching device 24 is designed as a snap-action switch. Regarding the more accurate function is based on the aforementioned EP 898 291 A Reference is made to the content of this application by express reference. The exact shape of the first shift drum 27 will also be explained in detail below.

Furthermore, sits on the rotary shaft 23, a cam 34. At this is a grinder 32 of a second switching device 30 with contacts 31, which the second heater 15 on and off. The exact course of the cam plate 34 will also be explained in more detail below.

In Fig. 3 is a plan view of the hotplate 19 shown schematically. It can be seen how the two heaters 13 and 15 as elongated Heizleiterbänder or resistors parallel to each other, the surface of the cooking area 19 cover approximately. Furthermore, a temperature limiter 40 is provided, as it is for example in the aforementioned DE 33 33 645 A is described. It has a long sensor 41 and includes a temperature limiting switch 42. Concerning the exact training and function is on the aforementioned DE 33 33 645 A Reference is made to the content of this application by express reference.

The sensor 41 covers a certain area of the cooking zone 19 and preferably passes over a type of free zone between the tracks of the first heater 13 and the second heater 15. The temperature limit switch 42, however, can only interrupt the supply of the first heater 13. Thus, although it detects the temperature of the entire cooking zone 19, but only interrupts the power supply to the first heater 13 in the case of too high a temperature or a temperature corresponding to a covering glass ceramic plate 18 according to Fig. 4 is considered harmful.

In this case, it is provided according to the invention that the second heating device 15 is designed for a continuous power which does not exceed a value of about 2.5 W per cm ² of covered area. For this value, it is possible and allowed to operate the second heater 15 permanently, without an excess temperature on the glass ceramic plate 18 could arise. Thus, no temperature limiter 40 must be provided here. The power of the second heater 15 may provide an overall desired total output in addition to the power of the first heater 13.

The advantage of this division 'of the total power Pges on the two heaters is that via the energy control unit 21 and the two switching devices 24 and 30 contained therein both heaters 13 and 15 are turned on with respect to their be specified by an operator cooking level. Since the total power of the cooking zones 19 distributed to the two switching devices 24 and 30, there are no problems here with too large to be switched currents or overload. The temperature limiter 40 or its switch 42 only has to switch or interrupt the power of the first heating device 13 when the overtemperature is to be threatened. Since the maximum average power for the second heater 15 is in a range for which no temperature limitation is necessary, it can still be operated even if the first heater 13 must be turned off due to otherwise too high temperature.

function

How the exact control of the individual heaters 13 and 15 takes place both with respect to the on and off times to achieve an average power as well as in the event of impending excess temperature for the glass ceramic plate 18, has already been explained above. Furthermore, it is now necessary to design in detail the training and control of the heaters so that it is as simple as possible for an operator and desired functionalities of the heating are guaranteed. In this context, the exact shape of the shift drum 27 and cam plate 34 is discussed, which are important for this purpose.

In the in Fig. 2 shown position both heaters 13 and 15 are turned off, since the contacts 25 and 31 of the switching devices 24 and 30 are disconnected. In order to set a small cooking level, the rotary shaft 23 is rotated counterclockwise via the rotary knob 22. It can be seen that the circumference of the shift drum 27 decreases in a counterclockwise rotation. This causes the wiper 26 and thereby the support for the middle part of the snap spring of the first switching device 24 to move downwards. Thereby comes a point where the spring snaps around and the switching device 24 closes. The further the shift drum 27 is rotated counterclockwise, the deeper the slider 26 can be pressed down. The longer the renewed release for separating the switching device 24, which means a higher cooking level. This is detailed in the above EP 898 291 A which is expressly referred to in this regard.

In a first region 27a, which extends from 0 ° to about 140 °, so the radius of the shift drum 27 decreases steadily from the largest value. At the region 27a with the increase, which causes the off-state, followed by a second region 27b. Here, the radius increases again, to such an extent that it corresponds to that radius in the region 27a at which the smallest cooking level is reached, ie the smallest average continuous power which the first heating device 13 generates via the energy control device 21. This is just past the outermost point of the shift drum 27 in the area 27a. From this increase, the radius decreases again in the area 27b over substantially the remaining angular range to just before 360 °. There again, the area 27a begins with the strong increase.

At the point or angle at which the region 27b begins, the cam disk 34 has the beginning of the region 34b. This extends from this angle α of about 140 ° to about 360 °, wherein here the radius is increased compared to the radius in the region 34a and is approximately constant. Over an angle of about 0 ° to about 140 °, the range extends. If the grinder 32 of the second switching device 30 at the region 34a, so the contacts 31 are opened and the second heater 15 is turned off. Energy is generated at the cooking area 19 only via the first heating device 13. If the full power of the second heating device 15 is switched via the second switching device 30, then it is recommended that these also be designed as snap-action switches for improved switching behavior.

In the diagram in Fig. 5 For example, the average powers P1 for the first heater 13, P2 for the second heater 15 and Pges for the entire cooking point 19 are shown in the course of the rotation angle. P2 is shown dotted, Pges dot-dashed. Over the rotation angle α of 0 ° to about 140 °, the power P1 increases from a certain starting value, for example, just over 100 watts, up to about 1,200 watts at 140 °. By further rotation of the slider 26 together with the first switching device 24 is pushed up again by the beginning of the range 27b, and as far as in the area 27a after the survey and at the lowest possible switched on average power. So these are just over 100 watts again. From here, the power P1 increases again due to the decreasing radius of the region 27b, as shown.

Furthermore, at the angle α = 140 °, the second switching device 30 switches on through the second region 34b on the cam disk 34, and the second heating device 15 is activated. As can be seen in the diagram, the power P2 is constant even as the angle increases. The total power Pges is given by adding P1 and P2. Lowering P1 by about the value of P2 at the angle of α = 140 ° results in an overall approximately constant and continuous history for the overall performance Pges. The value for P2 can be selected at about 1,100 watts. P1 can be a maximum of 2,100 watts, so that a total of 1900 heating power of 3,200 watts is generated, which is well above current maximum heating power. In the case of overtemperature of the glass ceramic plate 18, the temperature limiter 40 disconnects only the first heater 13 via the switch 42. The second heater 15, however, continues to operate without risk of over-temperature.

The size of the hob 19 may be about 230mm or correspond to such a conventional hob. At a voltage of 240V, this normally only has a power of 2,500 watts, so that an increase of the heating power by more than 25% is possible.

Furthermore, it is noteworthy here that the cyclic operation of the energy control device 21 does not affect the second heating device 15. This is depending on the angular position of the rotary shaft 23 either on or off. This must be taken into account when dimensioning the respective heating devices for a certain average power.

By dividing the services to be switched according to Fig. 5 Flicker regulations are not violated or complied with in the range of less than 140 ° in only one standard load to be switched in the usual way and at more than 140 ° in a non-switching base load and an additional control load.

The coverage of the second heater 15 by the sensor 41 of the temperature limiter 40 affects or does not interfere with the function here. Although the second heater 15 contributes to increase the temperature. However, due to the choice of its maximum heating power of about 2.5 W per cm ² , it can even when reaching an excess temperature and subsequent shutdown of the first heater 13 continue to be easily operated. Continuous heating may even be beneficial for some cooking operations because it is more uniform.

In a modification of an embodiment of an energy control device, it is possible via the cam '34 does not directly control the circuit breaker for the second heater 15, but to provide a signal switch that switches only a small power. About this a power relay can be controlled as a second switching device, which turns on and off the second heater 15. Thus, only a switch with high performance must be present in the housing of the power control unit, which the formation of insulation distances or the like. improved.

An advantageous embodiment of the invention can thus have a device for power supply for a cooking place two heaters, which are laid parallel to each other. About an electromechanical energy control device, depending on an angular position, either only a first heater operated regulated or a second heater firmly connected. The power of the second heater is chosen so low that no temperature limiter must be provided in the drive path of the second heater to protect a glass ceramic plate against overheating. When the second heater is switched on, the regulated power of the first heater is reduced to an initial value by approximately the amount of power of the second heater. The total power results from the added power of the two heaters.

Claims (9)

1. Device (11) for switching on and off of a plurality of heating devices (13, 15) of a cooking appliance, where the heating devices are arranged on the cooking appliance, where the device has a cyclical energy control unit (21) for setting the cycle times of a first heating device (13), where the energy control unit has a first switching device (24) with a triggering travel and with a first triggering point for the first switching device and a second switching device (30) with a triggering travel and with a second triggering point (34b) for the second switching device and a distance changing means (26, 27, 32, 34) for the triggering travel of the switching devices (24, 30), where the energy control unit has a device for a setting travel for influencing the distance changing means, where the triggering travel defines the on / off times or their ratio to one another and where at the second triggering point (34b) of the second triggering travel the second switching device (30) for the second heating device (15) is activated / switched on by the setting travel, characterized in that at the second triggering point (34b) the distance changing means (26, 27, 32, 34) sets the triggering travel for the first switching device (24) back to the initial value (27a) of the definition of the on / off times or their ratio to one another for a further change of the triggering travel with increasing setting travel, where the second triggering point (34b) for activation of the second switching device (30) is located on the triggering travel where the power (P1) averaged over several on and off times of the first heating device (13) is at least as large as the power (P2) of the second heating device (15).
2. Device according to Claim 1, characterized in that at the second triggering point (34b) the settable power (P1) averaged for the first heating device (13) is less than half of the maximum averaged power (P_ges).
3. Device according to one of Claims 1 or 2, characterized in that it has a temperature limiter (40) arranged at least inside the effective area of the first heating device (13) and switching the latter off when a certain temperature is exceeded, where the temperature limiter preferably has a switch (42) arranged in the connecting travel for the first heating device (13).
4. Device according to one of the preceding claims, characterized in that the cyclical energy control unit (21) is designed for a rotary motion as a setting travel, where the setting travel is less than 360°, where the distance changing means (26, 27, 32, 34) preferably converts the rotary motion into a substantially straight-line triggering travel.
5. Device according to Claim 4, characterized in that the cyclical energy control unit (21) has a rotary shaft (23) for setting, where a second trigger (34) for the second switching device (30) is arranged on the rotary shaft at the second triggering point (34b).
6. Device according to one of the preceding claims, characterized in that the first triggering travel and the second triggering travel vary depending on the setting travel, where the setting travel for both triggering travels is the same.
7. Cooking appliance with a device (11) according to one of the preceding claims, having a first and a second heating device (13, 15), where the cooking appliance is a hob with a glass ceramic plate (18) and radiation heaters (13, 15) as heating devices thereunder, where the second heating device (15) has a maximum continuous output of about 2.5 W per cm².
8. Cooking appliance according to Claim 7, characterized in that the two heating devices (13, 15) are electrically isolated from one another.
9. Cooking appliance according to Claim 7 or 8, characterized in that the heating devices (13, 15) are laid parallel to one another, where they run in substantially one and the same area.

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