EP1448024A2 - Heating device with two areas - Google Patents

Abstract

Heating unit (11), especially for a cooker with a glass-ceramic hob, is divided into at least two heating regions (17, 19; 21). The first area is protected by a first excess-temperature fuse (13) and has a maximum power output, while the second region is not monitored by the excess-temperature fuse and has a maximum power output of approximately 2.5 W per cm2>.

Description

Field of application and state of the art

The invention relates to a heating device according to the preamble of claim 1. Such a heating device is in particular for a cooking area with a glass ceramic hob suitable

The heating time or warm-up time for radiant heaters as heating devices on the one hand depends on a adjusted glass-ceramic surface temperature and the quality of the cookware used and on the other hand, from the rated power of the radiant heater and thus its power density. In many cases, it is desirable to shorten this cooking time to a comfortable operation and to achieve fast cooking. The power density of a radiant heater However, it can not be increased to infinity. at Radiant heaters with Bandheizleitern can from a certain power density the heating conductor temperature is no longer in the specified Upper limits are kept.

Values for power densities in such radiant heaters are called, which represent a good compromise between the cooking time, quality of the cookware used and the heating conductor temperature. An advantageous power density can be close to 8 watts / cm ² . For radiant heaters with a nominal diameter of 140mm and 180mm, such a power density is used successfully.

However, this power density has certain limits. From one Nominal diameter of the radiator of 210mm with theoretically 2700 watts Performance is the breaking capacity of electromechanical rod regulators or protective temperature limiter, which protects the glass ceramic hob before overheating, exceeded. The switching capacity the protection temperature limiter is at a certain current, which results from the given mains voltage of 230 volts and results in a certain performance value.

Task and solution

The invention is based on the object, an aforementioned heating device to deal with the problems of the state of the Technique can be avoided and especially the size of a Radiant heater regardless of the power density or a Switching capacity of protection temperature limiters made more variable can be.

This problem is solved by a heating device with the Features of claim 1. Advantageous and preferred embodiments The invention are the subject of further claims and will be explained in more detail below. The wording of the claims becomes by express reference to the content of the description.

According to the invention, a heating device is in at least a first and split a second area. A first area can be from monitored for a first over-temperature fuse. This can for example, be a rod regulator or a protection temperature limiter, the at least partially overlaps this first area or above runs.

The first area has a maximum first power. This is matched to the above values. A second area of the heater is operated without monitoring by the first overtemperature fuse. In particular, the second area is operated at all without over-temperature protection. This is achieved by the maximum area coverage of the second area being approximately 2.5 watts / cm ² . Here it is possible to operate a radiant heater under a glass ceramic hob without rod controller or protection temperature limiter. With such a power value has been found within the scope of the invention that a conventional glass-ceramic is not endangered.

Thus, in a preferred embodiment of the invention, the heating device divided into two parts, so to speak. A first area is operated with a critical power density and must therefore have a protective temperature limiter. This first area can be chosen so large that the protective temperature limiter the resulting power just manage or switch. In addition to this maximum switchable power, the area of the To increase radiant heaters, a second area is added. This second area will in any case be without supervision operated by the over-temperature fuse of the first area, preferably without any monitoring by an overtemperature fuse. For this purpose, a value is chosen as the power density, which for a glass ceramic is technically possible and permissible.

Alternatively, a separate over-temperature fuse could be used for the second Be provided area. This would increase the effort, but also improve safety.

The second region can rest against the first region, advantageously at least along the half outer border. This gives you an approximate elongated heating device. Advantageously, the second area surrounds the first area, where they can be arranged concentrically. While the lateral connection of a second area to a first area in about a known elongated roasting heater corresponds, is a concentric arrangement for use either smaller or large round cookware advantageous.

In order to additionally increase the paring performance, the performance for the first range more than that for a radiant heater of this size usual basic service amount. In particular, here can the performance the maximum value of the overtemperature fuse, for example one Stabreglers, approach. For example, one performance for the first Range of a maximum of 2500 or 2700 watts be provided at one round area with a diameter of 230mm.

Furthermore, advantageously, the first area a switchable power have, which can be switched to the basic power. It is provided that the maximum first power is then present if the switchable power is also applied. Such a switchable Power can be, for example, a boil or the like his.

The performance for the second area may, in particular due to the lower power density, much lower. For example 600 watts can be provided here. Because this performance is beneficial in the outer or edge region is present as a second area, in which also Cooking pots with not very even floor get up, this is Performance in any case decreased. Thus, too much warming a glass ceramic hob avoided here. Furthermore has in heating mode without pot, so if no heat output removed is, the glass ceramic in the edge area due to the larger area the biggest heat loss. Even so, she is overheating protected.

In a further embodiment of the invention, the heating device have a controller or be connected to it. This controller can be an additional contact to the circuit of a basic service of Heating device or a switchable power for the first Range to the total combined maximum first power. Thus, the additional power can be defined, for example, as a boost and be used.

Furthermore, the heating device can have an electronic control, for example, with a touch switch arrangement for input. Another relay can be provided to the switchable Power in addition to the base load to the total maximum first To switch power.

Advantageously, a radiant heater is used as the heating device, which have a heating conductor made of resistance material can. The heating conductor is preferably in a so-called flat band shape, where he is standing upright on an insulating pad and partially embedded in it.

These and other features go beyond the claims as well from the description and the drawings, the individual Characteristics in each case alone or in the form of sub-combinations in one embodiment of the invention and on others Be realized and beneficial and protectable areas Represent embodiments for which claims protection here becomes.

Brief description of the drawings

Fig. 1

eine Draufsicht auf einen Strahlungsheizkörper mit einer Aufteilung in drei Heizbereiche sowie einem Stabregler und

Fig. 2

ein Wärmebild des Strahlungsheizkörpers aus Fig. 1 im Betrieb.

An embodiment of the invention is shown schematically in the drawings and will be explained in more detail below. In the drawings show:

Fig. 1

a plan view of a radiant heater with a division into three heating areas and a rod controller and

Fig. 2

a thermal image of the radiant heater of FIG. 1 in operation.

Detailed description of the embodiment

In Fig. 1, a radiant heater 11 is shown in plan view, as he known per se. Its heated area is controlled by a rod regulator 13 overlapped. The temperature limiter or rod controller 13 is with his Housing 14 attached to the side of the radiant heater 11. Of the Sensor rod 15 protrudes in the radial direction over the center of the radiant heater 11 a bit out.

With this rod controller 13, an over-temperature protection is achieved by he ensures that the above the radiant heater 11 generated Temperature at the bottom of a glass ceramic hob a particular Maximum temperature does not exceed. This maximum allowed Temperature is around 700 ° C. Such a rod regulator as well as his Function go, for example, from DE 33 33 645 or DE 34 23 086 forth.

The heating area of the radiant heater 11 is subdivided into a first one innermost region 17. The first region 17 is of an annular surrounded in the middle second area 19. This in turn is from Surrounding a relatively narrow circumferential third region 21, which forms the outermost heating area.

The first region 17 is formed by first heating coils 18, the are laid meandering. This basic structure of a radiant heater For example, from EP 590 315, incorporated herein by reference expressly referred to.

The second heating area 19 is formed by second heating coils 20. The third region 21 is again formed by third heating convolutions 22, which, as can be seen from Fig. 1, from a single loop consist.

The Heizwindungen 18, 20 and 22 are for example advantageous a heating tape formed in upright ribbon shape. You can be specially selected with regard to their characteristics certain power distribution or area performance achieved during operation or to achieve overall performance. It can also be seen that the Heating coils 18 of the first region 17 with a smaller distance from each other run as the second heating coils 20 of the second area 19th

By means of several terminal lugs 24, a connection of the heating coils to a power supply, such as power electronics or a so-called clocking energy regulator. The heating coils 18 and 20 of the first and second areas are respectively over the top terminal lug 24a contacted, as can be seen. This connection banner 24a is connected to the housing 14 of the rod controller 13. Your electrical connection is thus monitored by the rod controller 13 and interrupted in case of overheating to the switch off the first heating area 17 and the second heating area 19. As can be seen, although by means of the rod controller 13 in this way and a distinction between the first area 17 and the second region 19 in overtemperature case not possible. It would be insofar as possible in a further embodiment of the embodiment, Such a distinction is possible by means of a further bar controller do. However, this plays for the invention in the frame discussed here not matter.

The third heating coil 22 of the outer third region 21 is over the Connection lugs 24c and 24d connected. These are without that Interposing the rod controller 13 connected to a power supply. They are therefore not monitored by the rod controller 13 concerning overtemperature.

function

Already from Fig. 1 can be seen, as has been mentioned before, that the heating coils of the first region 17 are denser than in the two other areas, and in the area 19 again denser than in the third area 21. So there is a certain gradation. Already this gradation gives a gradation of area coverage, because the area performance is the higher, the denser Heizwindungen the same type are laid.

Furthermore, as has also been mentioned above, means the special design of the individual heating conductors whose performance and thus again the area performance are influenced.

FIG. 2 is a schematic thermal image of the radiant heater. FIG 11 of FIG. 1 in operation. Due to the different surface markings the temperature that prevails is displayed. ever brighter, the higher the temperature. The gradation is per brightness level 10 ° C. The first area 17 is predominantly the brightest, with the temperature here is between 545 ° C and 564 ° C respectively at about 555 ° C. The second region 19 has temperatures in the range of 524 ° C to 544 ° C. The third region 21 has predominantly temperatures in the Range between 494 ° C and 514 ° C or about 500 ° C.

It should be noted here in comparison with the patent claims that the first area 17 and the second area 19 of the radiant heater 11 according to the embodiment of FIG. 1 the first area according to claim 1 correspond. The third area 21 of the Radiant heater 11 corresponds to the second area according to claim 1.

As was already apparent from the description of FIG. 1, are the first area 17 and the second area 19 separately controllable. she however, are monitored jointly by the bar controller 13.

The radiant heater 11 is a two-circuit radiant heater. It has a diameter of 230 mm and a total nominal power of 2800 W. It accounts for the first area 17 1100 W, the second area 19 also 1100 W and the third area 21 600 W. This 600 W are the so-called unprotected or unregulated power. From Fig. 2 it can be seen that here the temperature in about 50 ° to 60 ° lower than in the first or second region, which are centrally in the radiant heater 11. Further, the area power of the third region 21 is less than 2.5 W / cm ² , while the power density in the first and second regions is 7.8 W / cm ² .

By Fig. 2 is thus proven that with heating areas with the previously described properties, ie in particular the outermost Heating area with low area performance, a radiant heater with additional power can be provided, which does not have a Rod controller or not regulated by a single common rod controller must become.

In the operation of the radiant heater, it is such that in single-circuit operation only the first area 17 is active. In the two-circuit operation of the second area 19 and the third area 21, although electrically separate, but timed together.

Due to the fact that the power of the third region 21 is not provided by the rod regulator 13 needs to be monitored and therefore not by this must be switched off, its maximum switching limit exploited by the performance of the first and second regions 17 and 19 become.

If the control of the heating areas at the terminal lugs 14th via a switching electronics, it is in a further embodiment of Invention possible to detect the response of the rod controller 13. In Dependent on this, in addition, the third heating area 21 could be the same be switched off, but not directly by the rod controller 13, but by its property as a signal generator indirectly. This Although not always because of the thermal load on the surface of the third area 21 is necessary. This would be a uniform Operation of all heating areas possible, so not from the glow pattern of the radiant heater, the outermost area continues to glow brightly, while the central area is dark.

Claims (11)

Heating device (11), in particular for a cooking area with a glass ceramic hob, which is divided into at least a first region (17, 19) and a second region (21), characterized in that a first region (17, 19) of a first overtemperature Fuse (13) is monitored and has a maximum first power and a second area (21) without monitoring by the first overtemperature fuse (13) is operated and has a maximum area performance of about 2.5 W / cm ² . Heating device according to claim 1, characterized in that the second region (21) is operated entirely without monitoring by an excess temperature fuse. Heating device according to claim 1 or 2, characterized in that the second region (21) on the first region (17, 19) rests at least along half the outer edge, wherein preferably the second region surrounds the first region and in particular the regions are arranged concentrically. Heating device according to claim 3, characterized in that the regions (17, 19, 21) are round, in particular circular. Heating device according to one of the preceding claims, characterized in that the power for the first region (17, 19) is more than the usual for such a radiant heater (11) basic power, preferably a maximum of 2500 watts in a round first region with a diameter of 230mm , Heating device according to claim 5, characterized in that the first region (17, 19) has a switchable power, which can be connected to the basic power, wherein in the state with the switched-on power, the maximum first power is applied. Heating device according to one of the preceding claims, characterized in that the power for the second region (21) is 600 watts. Heating device according to one of the preceding claims, characterized in that the excess temperature fuse is a rod regulator (13) which at least partially overlaps the first region (17, 19). Heating device according to one of the preceding claims, characterized in that it comprises a control device with an additional contact for switching a basic power or a switchable power for the first area (17, 19) to the total maximum first power. Heating device according to claim 8 or 9, characterized by an electronic control, preferably with a touch switch arrangement for input to the controller, wherein it has a further relay for switching the switchable power in addition to the basic power to the total maximum first power. Heating device according to one of the preceding claims, characterized in that the heating device is a radiant heater (11) with a heating conductor made of resistance material, preferably in flat band form.

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