WO2005074321A2

WO2005074321A2 - Method for switching heating devices in an electrical cooking appliance and corresponding device

Info

Publication number: WO2005074321A2
Application number: PCT/EP2005/000707
Authority: WO
Inventors: Martin Baier
Original assignee: E.G.O. Elektro-Gerätebau GmbH
Priority date: 2004-01-28
Filing date: 2005-01-25
Publication date: 2005-08-11
Also published as: WO2005074321A3; DE102004005272A1

Abstract

According to the invention, it is possible, for example, on a ceramic top (11), to increase the life expectancy of the timing relays (RT), for individual hobs (12), which are divided into groups (14) of more than one hob. The groups (14) are each provided with a phase-separation relay (RP), for connection to an external line on a three-phase supply. Supply to a line for a hob (12) can be achieved, by means of a controller (16), whereby as many current supplying timing or switching processes as possible are carried out by the phase separation relay (RP) and not by a timing relay (RT), provided for the hob.

Description

Description Method for switching heating devices in an electric cooking device and device therefor, field of application and prior art

The invention relates to a method for switching a heating device in an electric cooking appliance, the electric cooking appliance advantageously having a plurality of heating devices and being, for example, an electric hob. The invention also relates to a device for carrying out the method, in particular an electric hob.

Electrical loads in electrical cooking appliances such as electrical hobs or ovens are usually switched via relays. With each switching process, there is sparking, which changes the contacts of the relay and reduces their service life. On the one hand, higher quality contact materials for the relays have been developed, as can be seen, for example, from EP 1 109 188. However, this is considered to be complex and expensive.

Furthermore, DE 197 50 559, for example, shows how a more homogeneous magnetic field can be generated in a micro-relay in order to achieve a higher contact pressure of the contact elements on the contact surfaces. However, this is also structurally complex.

The usual clock relays used are those that are classified according to a standard (EN 60 335-2-6) as a contact with automatic operation. At a current of 10 amperes to be switched, they are tested so that they have to withstand 100,000 switching operations. In the case of controls for, for example, radiant heaters in a hob, there is usually a clock relay for each radiant heater and, in addition, two phase separation relays. With the clock relay, each radiant heater is operated in the desired clock mode with adjustable power generation by connecting to the operating voltage, usually mains voltage with 230 volts or an outer conductor of a three-phase network. If a radiant heater or the control system or the entire electric cooking appliance is switched off completely, a phase separation relay completely disconnects it from the operating voltage or from the neutral conductor. Since the phase separation relay may have to switch the operating current of several radiant heaters, the nominal current of 16 amps is assumed here.

Task and solution

The invention has for its object to provide a method mentioned above and a corresponding device with which the disadvantages of the prior art can be avoided and in particular the life of the clock relay or an electric cooker or its associated control as a whole can be increased.

This object is achieved by a method having the features of claim 1 and an apparatus having the features of claim 8. Advantageous and preferred embodiments of the invention are the subject of the further claims and are explained in more detail below. The wording of the claims is made the content of the description by express reference.

According to the invention, these are used in a method for switching one or more heating devices in an electric cooking appliance for setting a specific power generation on a heating device operated clocked via respectively assigned clock relays or switched to the operating voltage. This means that a clock relay is looped into the connection line of each heating device, in particular on an outer conductor of a three-phase network. Furthermore, the electric cooking device has at least one phase separation relay, with which a heating device, groups of such heating devices or the electric cooking device can be completely or partially disconnected or switched off from the operating voltage or from the neutral conductor. In addition to the possibility of using the clock relay assigned to each heating device when the electric cooking appliance is switched on for clock operation, it is possible to close the clock relay during clock operation permanently or at least for one or more clocks and via clocks of the Phase separation relay to achieve the desired power generation or the clock operation for the heating device. In this application, clocks are used to refer to the switching of a relay in the live state.

In simple words, this means that, for example, a heating device can be supplied with an operating voltage via a clock relay and a phase separation relay. The clocking for the clock operation can take place via one of the two relays when the other is closed. In this way, the clock operation can be at least partially shifted to the phase separation relay to relieve the clock relay. This reduces the number of clock cycles at the clock relay which occur over a normal life expectancy of the electric cooking appliance, which is usually much higher than that with the phase separation relay, so that it can take over a number of clock cycles without any problems ,

In some electric cooking appliances it can be provided that a heating device can be connected to the operating voltage via a plurality of phase separation relays. In this case the phase separation relays alternately and advantageously used approximately equally frequently for the cycle operation of the heating device. The other relays in the power supply are then only switched when de-energized.

In many cases, particularly in the case of electric cooktops, several heating devices have a common phase separation relay as a type of group, as a rule these are two heating devices. For the clock operation of one or more of these heating devices, it can be provided that the clock relays only switch when they are currentless or the phase separation relay is open and thus disconnects them from the mains. It is thus possible to de-energize the clock relays of each heating device by means of the phase separation relays, then to set the clock relays in accordance with the desired clock operation and then to re-enable the electrical power via the phase separation relays, in which case the phase separation Switch relay live. This applies in particular if the clock operation, which is to take place differently in the case of a plurality of heating devices connected to a phase separation relay, is nevertheless to be carried out as a clock operation with the phase separation relays being loaded by the current supply. In an extension of this possibility, it can be provided, above all, to adapt the clock patterns or time intervals provided for a specific power generation of a heating device in such a way that regular clock patterns are interrupted in order to generate switching points that are as common as possible.

Advantageously, in particular in order to adhere to the usual regular clock patterns, in the event that several heating devices have a common phase separation relay, the phase separation relay is only clocked if only one in a larger time frame or only for one or a few clock cycles of these heating devices is to be operated. The clock relays of the other heating devices of this phase separation relay are currentless or have open ones Contacts. If, in an extension of this constellation, several heating devices are to be operated by a user with a common phase separation relay in the clock mode and if this is also different under certain circumstances, then it is advisable to use the clock mode exclusively via the clock relay produce.

In an extension, an electronic control is advantageously used, which detects when at least one disconnection takes place at about the same time as part of the cycle operation of the heating device. A disconnection can then take place via the common phase separation relay, so that at least this switching process is carried out by the phase separation relay to relieve the clock relays. Before switching on at least one heating device again, the clock relays, which are then de-energized and consequently the switching process takes place without load, can be set in such a way that the desired operation continues when the phase separation relay is switched on again.

If, in a further embodiment of the invention, a plurality of heating devices as a group has a single assigned phase separation relay, such heating devices can be selected as a group which are designed either with respect to the nominal operating power or the geometrical arrangement on the electric cooking appliance in such a way that they are conventional Operations are not shared. In particular, in the case of an electric cooktop, these are a rear and a front heating device, which have a common phase separation relay.

Namely, it has been found that in many cases users either use mainly only the front heaters or only the rear heaters. In this way it can be achieved that, even if several heating devices of the electric cooking appliance are likely to be expected to operate, it is very likely that these because different phase separation relays are assigned. Cycle operation can then take place exclusively via the phase separation relays, to which only a single heating device is then attached.

In a further embodiment of the invention, a detection can be provided for the number of clock processes carried out for each relay. When selecting a relay of a heating device, that is to say either a clock relay or a phase separation relay, it can be taken into account that the number of switching operations carried out is distributed as evenly as possible. Relays with a large number of switching operations that have already been carried out are thus relieved as far as possible or are not used for current-carrying switching operations. For this purpose, in addition to a microcontroller for counting, a memory, for example an EEPROM, can be provided in the electric cooking appliance or a controller. This is usually also used for other functions, for example for storing properties of the control element or the like.

Furthermore, it is advantageous if, in order to ensure the function of the control, it either has its own energy source, which at least enables short-term operation. Alternatively, it can be provided that the controller is never disconnected from the network, so that a supply of the controller is guaranteed at all times. It can also be provided that the control, which is not used for the heating devices and therefore does not have to be switched, is supplied via a third phase.

With regard to the device according to the invention, above all features are provided which have already been partially described above.

This applies in particular to a correspondingly designed control of the electric cooking appliance, which is a microcontroller and can also have a memory or the like. Furthermore, the controller can advantageously have means by means of which it can detect which switching state each relay, in particular the clock relay, has. In particular, it is of interest to determine whether a relay is de-energized or not. This can advantageously be done by detecting the switching state.

These and further features emerge from the claims and also from the description and the drawings, the individual features being realized individually or in groups in the form of sub-combinations in one embodiment of the invention and in other fields and being advantageous and capable of being protected Can represent designs for which protection is claimed here. The division of the application into individual sections and sub-headings do not limit the general validity of the statements made under these.

Brief description of the drawings

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

1 is an inventive hob with various relays for the electrical power supply and a controller,

2 and 3 different switching cycles or clock sequences of individual heating devices of the hob.

Detailed description of the exemplary embodiments

1 shows a hob 11 according to the invention as an electric cooking appliance. It is advantageous to have a glass ceramic hob. It has four different hotplates 12a to 12d, which can be formed in particular by radiant heaters. The hotplate 12d is divided into an inner and an outer heating circuit, the inner heating circuit in the basic state being always on when the two-circuit hotplate 12d is in operation. With correspondingly large pots, the outer heating circuit can be switched on via the relay RZd, the two heating circuits then being subjected to power together and operated in the same cycle by the clock relay RTd.

The left hotplates 12a and 12b are combined in the left group 14a of hotplates, which is indicated by the dashed outline. The hotplates 12c and 12d are combined in the right group 14b. This division into groups results from the fact that a clock relay RTa-d is provided for each individual hotplate. In conventional known hobs, these clock relays are responsible for the amount of power applied by opening and closing the contacts in cycle mode to switch the connected hotplate on and off. A first phase separation relay RPa is provided for the two left hotplates 12a and b or the group 14a, which is connected to the neutral conductor N of a three-phase connection for the hob 11. The two right hot plates 12c and d of the right group 14b are connected to a second phase separation relay RPb and thus also to the neutral conductor N.

All clock relays RTa-d, the additional relay RZd and the phase separation relays RPa and b can be controlled individually and independently of one another by the controller 16. The controller 16 is independent of clocking of the relays with regard to its energy supply.

The control element 18 is intended to symbolically represent how an operator specifies a power level for a specific hotplate 12, which is then fed to the control 16. Cooking programs can be called up under certain circumstances via the associated memory 19, which is advantageously an EEPROM. On the other hand, the controller 16, alone or in conjunction with the memory 19, can use the operating state of each individual hotplate 12a-d or respectively the groups 14a and b of hotplates 12 to determine how the power is applied to a hotplate desired by the operator. Likewise, the number of current-carrying, advantageously also currentless, circuits of the relays RT and RP can be stored in the memory by the controller 16. function

If, for example, in a first case, power is applied to the hotplate 12b, which can be achieved by means of a clock pattern of switching on and off shown in FIG. 2, then essentially the amount of the desired power, which is set on the control element 18, the clock pattern shown in Fig. 2 fixed. If now only the hotplate 12b is to be operated in group 14a, that is, the hotplate 12a is not, then the clocking, as shown in FIG. 2, takes place exclusively via the phase separation relay RPa. However, before this closes the contacts for the first time, the controller 16 actuates the clock relay RTb. If the contacts of the phase separation relay RPa are now closed in the specified cycle, this supplies the hotplate 12b directly with power or connects it to the operating voltage. The labeling of the curve with RPa or RTb is irrelevant in this first case.

As long as the additional hotplate 12a from group 14a is not required, only the phase separation relay RPa takes over the clocking for the power supply to the hotplate 12b. This also applies in the event that an operator sets a changed power level via the control element 18 and thus the cycle changed in FIG. 2 changes towards higher or lower power overall.

The aforementioned method can be applied analogously in any case if only a single hotplate 12 is operated from a group 14 of hotplates. It should be noted that it is irrelevant for the clock operation via the clock relay RTd or the phase separation relay RPb with regard to the hotplate 12d whether the outer heating circuit is switched on via the additional relay RZd or only the inner heating circuit is working. As described above, the number of current-carrying, advantageously also currentless, circuits of the relays RT and RP can be stored by the controller 16 in the memory 19. Depending on which of the two relays in question, namely the respective clock relay or the phase separation relay, has the smaller number of switching operations carried out, one of the two relays can be selected with the lower performance, provided that it can basically be used freely Has switching operations.

The relays RTa-d and RPa and b are connected to the controller 16 and are controlled by it. The state of the current supply can be recorded either by checking the control. Means for detecting the current supply can also be provided, for example in the relay itself or in the connecting lines of the relays to the heating devices.

3 shows a further clock pattern of the power supply, specifically for the hotplate 12a or via the clock relay RTa. If the diagrams in FIGS. 2 and 3 are now considered as simultaneous operation of the hotplates 12a and 12b of the group 14a in a second case, the desired cycle patterns clearly being different, it is obvious that it is no longer exclusive can be clocked by the phase separation relay RPa. In an embodiment of the invention, it can be provided here that, depending on the correspondence with the clock pattern, clocking is carried out either via the phase separation relay RPa or via one of the clock relays RTa and b, that is to say it is switched live. The clocking is carried out differently by means of elevations in the clock patterns each shown differently, namely provided with RP for the phase separation relay or RT for one of the clock relays. The controller 16 decides for each individual cycle via which of these relays it is carried out. Before the time t = 0, both hotplates 12a and b and the associated relays are de-energized. Since the first cycle coincides exactly at both hotplates, this can take place via the phase separation relay RPa. For this purpose, both cycle relays RTa and b are closed in the de-energized state and then the phase separation relay RPa is closed in a current-carrying manner at time t = 0. After the cycle has ended, the phase separation relay RPa is opened. The clock relay RTb remains closed for the next pending cycle that occurs at the hotplate 12b. The clock relay RTa of the other hotplate is opened. The second cycle of the hotplate 12b is again carried out via the phase separation relay RPa. By opening the contacts of the clock relay RTa, this hotplate 12a is not subjected to power.

After the second cycle of the hotplate 12b has ended, the hotplate 12a is to be clocked next. Thus, either the clock relay RTb is opened, as shown in FIG. 3, the clock relay RTa is closed in the de-energized state because of the open phase separation relay RPa, and then the second clock cycle is performed exclusively by closing and opening the phase separation relay RPa performed. Or the clock relay RTb is opened, the phase separation relay RPa is closed and the second clock is carried out via the clock relay RTa. For the next pending cycle, which occurs at the hotplate 12b, either with the phase separation relay RPa closed, the clocking can take place exclusively via the assigned clock relay RTb. Or it is possible to open the phase separation relay RPa directly after the clocking of the second cycle at the hotplate 12a, likewise the clock relay RTa, while the clock relay RTb is closed and then the third one by closing the phase separation relay RPa Clock is generated. This process can thus be continued for all further measures, both this and a similar pattern. It should be noted, however, that in cases where clocks overlap, it is necessary for clocking to take place via the clock relay RT when the phase separation relay RP is closed. In the cases in which a cycle of a hotplate 12 of a group 14 is to take place when no cycle is present at one or all of the other hotplates of these groups, this can be done via the phase separation relays RP.

Claims

claims

Method for switching a heating device (12a-d) in an electric cooking appliance (1 1), preferably a hob with several heating devices, whereby for setting a specific power generation of a heating device (12a-d), this is done via an assigned clock relay (RTa -d) operated in a clocked manner or switched to an operating voltage (L1, L2), the electric cooking appliance having phase separation relays (RPa-c) for disconnecting the electric cooking appliance or groups (14a, 14b) from heating devices ( 12a-d) of the operating voltage, characterized in that, in addition to an associated clock relay (RTa-d), at least one phase separation relay is also used for the clock operation of a heating device by connecting to the operating voltage, during the clock operation with the phase separation relay (RPa-c) the clock relay (RTa-d) assigned to the heating device (12a-d) is closed.

A method according to claim 1, characterized in that the electric cooking appliance has a plurality, in particular two, phase separation relays (RPa, RPb), which are used in particular alternately and approximately equally frequently for clocking a heating device (12a-d).

A method according to claim 1, characterized in that several, in particular two, heating devices (12a-d) have a common phase separation relay (RPa, RPb), with one or more of these heating devices being operated in cycles via a clock assigned to each heating device. Relay (RTad) the heating devices are only switched or clocked if the phase separation Relay has open contacts or the clock relays are de-energized.

4. The method according to claim 1 or 2, characterized in that several, in particular two, heating devices (12a-d) have a common phase separation relay (RPa, RPb), the clock relays (only one heating device in clock mode) RTa-d) of the other heating devices of the common phase separation relay have open contacts or are de-energized and the clock operation takes place via the phase separation relay.

5. The method according to claim 4, characterized in that during the simultaneous clock operation of several heating devices (12a-d) with a common phase separation relay (RPa, RPb), the clock operation takes place exclusively via the clock relay (RTa-d) , preferably if the cycle times of the heating devices are different.

6. The method according to any one of the preceding claims, characterized in that several, in particular two, heating devices (12a-d) have a single assigned phase separation relay (RPa, RPb), the heating devices with respect to the nominal operating power and the geometric arrangement the electric cooking appliance or on an electric hob (11) are designed such that they are not used together in conventional cooking processes, in particular in each case a rear and a front heating device as a group (14a, 14b) in the case of an electric hob Have phase separation relays.

7. The method according to any one of the preceding claims, characterized in that it is counted and stored how often each relay (RTa-d, RPa, RPb) of the electric cooking appliance (11) is clocked. tet and a selection when using a heating device (12a-d) associated clock relay (RTa-d) or phase separation relay (RPa, RPb) is then made, which of these relays has the smaller number of clocking operations performed.

8. Device for performing the method according to one of the preceding claims for an electric cooking device (11) with a plurality of heating devices (12a-d), characterized by a controller (16) for the electric cooking device, which for controlling both the clock relay (RTa-d) as well as the phase separation relay of the electric cooking appliance, in particular for performing a cycle operation by means of all relays.

9. The device according to claim 8, characterized in that the controller (16) has means for detecting the switching state of each relay (RTa-d, RPa, RPb), in particular for detecting whether a relay is de-energized or not.

10. The device according to claim 8 or 9, characterized in that the controller (16) has a counting device and a memory (19) for detecting and storing how often which relay (RTa-d, RPa, RPb) has carried out a clocking process, wherein this information can be queried by the controller to determine the timing of one of the relays for power generation via a heating device (12a-d).