CROSS-REFERENCE TO RELATED APPLICATION

The present application is a U.S. national phase entry of pending International Patent Application No. PCT/EP2014/071945, international filing date Oct. 14, 2014, which claims priority to European Patent Application No. EP 13 188 594.9, filed Oct. 14, 2013, the contents of which are incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention pertains to a method for self-testing and checking certain functions of a cooking device in the form of a convection oven, a steamer, or a combination of the two, namely a convection steamer, which comprises a cooking chamber or compartment, which can be closed by a cooking compartment door, and a plurality of actuators such as pumps, at least one heating device, at least one steam injection device, at least one flow-generating device such as a blower, and flaps and/or valves as well as temperature sensors and an appliance control unit.

BACKGROUND OF THE INVENTION

Modern cooking appliances are highly sophisticated devices with a large number of individual components, some of which are subject to a certain amount of wear as a result of the frequent loads to which they are subjected; these loads have multiple causes, one of which is the high temperatures at which the device operates. A large number of malfunctions can therefore occur, which make it more difficult or even impossible to obtain the desired cooking result.

It is possible in principle to monitor certain appliance functions by means of complicated sensors. Thus, for example, the operation of the blower wheel can be monitored by appropriate monitoring of the blower motor by the use of Hall sensors, for example. The operation of pumps such as the drain pump can be monitored by using pressure sensors, for example, or by measuring the flow rate, or by measuring the current drawn by the pump. The sensors and control units required for this purpose are disadvantageous. Not only are they complicated and thus expensive, but the sensors themselves are also at risk of malfunction and failure, so that it cannot always determined whether the assembly responsible for the appliance function is itself defective or whether it is the monitoring sensor which is defective.

In particular, problems can also occur in the context of customer service visits, specifically in low-density population areas. The major problem is often that, because the operating personnel are becoming increasingly less knowledgeable, the appliance defect in question can no longer be identified, and when the call goes out to customer service, the customer cannot tell the service representative what spare parts he should bring with him When the customer service representative then arrives and is obliged to observe that he does not have the required spare part, he must often make an extra trip back and forth, often over quite a long distance.

An object of the present invention is therefore to propose a self-testing method which does not require additional sensors to check the functioning of the actuators of the cooking appliance, and which, after the test has been run automatically, makes it possible to determine whether any of the actuators is defective, and, if so, which one(s), so that effective maintenance procedures can be carried out and/or certain actuator malfunctions can be determined or ruled out. This object is achieved by the features of claim1.

SUMMARY OF THE INVENTION

The method according to the invention for self-testing and checking certain functions of a cooking appliance in the form of a convection oven, a steamer, or a combination of the two, namely a convection steamer, is characterized in that, by means of the temperature sensors of the cooking appliance, the functionality of the actuators of the cooking appliance can be checked by comparing the detected temperatures and temperature profiles with the reference temperature values and reference temperature profiles which are to be expected during operation of the actuator in question and which are stored in the electronic appliance control unit; and in that, if the detected value agrees with the corresponding reference value, the electronic appliance control unit concludes that the actuator in question is functioning properly, or, if a deviation is detected, that it is malfunctioning and displays, stores, and/or transmits the results for evaluation, wherein, at the beginning of each detection, the cooking appliance is in a defined initial state.

By means of the temperature measurements, which can be conducted by the temperature sensors installed in the cooking appliance, certain actuators are checked to determine their functionality. A basic principle of the self-testing method according to the invention is the evaluation of certain rates of temperature change. The evaluation is dependent on, for example, the size of the cooking appliance, on the type of energy and voltage, or on the type of gas. There are therefore certain limit values associated with the specific appliance. As a result of the temperature measurements, therefore, appliance defects can be confirmed or ruled out. By isolating the malfunction of the cooking appliance and identifying the individual components responsible, it is possible in particular to improve customer service efficiency.

Thus, within the scope of the present invention, all essential appliance components can be checked in the simplest possible way. The great advantage of the present invention also consists in that, to implement the self-testing, no additional sensors need to be installed in the cooking appliance; on the contrary, the temperature sensors necessary for the cooking programs in question and for the operation of the cooking appliance are themselves sufficient to carry out the various individual self-testing steps.

It is advantageous, furthermore, for at least two actuators to be checked in succession, and for the defined starting state of the at least second actuator test to be produced essentially by the preceding actuator test. Thus several actuators can be self-tested one after the other in correspondingly rapid sequence.

It can be provided, if desired, that the following actuator cannot be tested if the preceding actuator has failed its test, in which case the entire test procedure thus comes to a stop. This prevents false test results from being obtained, and there is no danger that a properly operating actuator is judged to be defective.

It is especially advantageous, furthermore, for the self-test to comprise a check of the oven/steamer compartment environment (temperature/humidity) control and/or the cleaning of the cooking appliance. This can be done either in different self-tests or in a one complete self-test.

Within the scope of the self-test, it is advantageous for it to be possible to check at least one of the following actuators of the cooking appliance: the heating device, the temperature controller, the steam generation, the dehumidifier, the recirculation pump, and drain pump for draining a liquid reservoir.

It is advantageous to determine the functionality of the heating device by heating the cooking compartment over a specific temperature range within a predetermined time interval.

In the case of cooking appliances with direct water injection, it is advantageous to determine the functionality of the steam generation by heating the cooking compartment to a predetermined temperature and then to detect the drop in temperature during the active steam generation. The steam generation test can thus be carried out immediately after the test of the heating device. In the case of cooking appliances which comprise an additional steam generator, the test can be carried out by detecting the increase in the temperature of the cold cooking compartment caused by the injection of 100° C. steam.

It is advantageous, furthermore, to determine the functionality of the dehumidification by a dehumidifier by heating the cooking compartment and then, after opening the dehumidifier, to detect the temperature measured by a sensor thermally coupled to the dehumidifier, preferably a sensor in a feed air pipe, which temperature should drop by a predetermined amount within a predetermined time interval. As a function of the appliance in question, it may be possible to use the cooking compartment temperature sensor for this test, if it is sufficiently well-coupled thermally to the dehumidifier. Dehumidification can be achieved by supplying outside air or by injecting water, i.e., by quenching the steam atmosphere.

It is advantageous, furthermore, to determine the functionality of the recirculation pump by heating the cooking compartment and, after activating the recirculation pump, by detecting the cooking compartment temperature, which should fall by a predetermined amount in a predetermined time interval. Thus here is no longer any need to detect the operation of the recirculation pump directly by means of appropriate sensors, as described above.

It is advantageous, furthermore, to determine the functionality of the drain pump by first filling the liquid reservoir and starting the recirculation pump, then by turning the drain pump on and heating the cooking appliance in convection mode. A temperature considerably greater than 100° C. should be measured after a predetermined time interval. The relationships are as follows: While the recirculation pump is running, the cooking compartment is cooled by the water being continuously pumped through the cooking compartment. As long as this circuit is operating, the temperature in the cooking compartment cannot rise much above 100° C. even at the maximum heat setting.

This water circuit is interrupted when a properly functioning drain pump is turned on. The liquid reservoir of the recirculation pump is emptied. The recirculation pump runs on empty and cannot pump any water into the cooking compartment. Without this supply of water, the cooking compartment can now heat up to the set nominal temperature of greater than 100° C.

It is advantageous, furthermore, for the self-testing method according to the invention to determine whether the door seal is providing a satisfactory sealing effect; this can be done by first heating the cooking compartment to a predetermined temperature and then, after making sure that the door is closed, turning off the heating device and the actuators and detecting the temperature drop. If the door seal is completely functional, the temperature will drop only slightly, whereas, if the door seal is defective, a correspondingly greater temperature drop will be detected.

The present invention is not limited to the situation in which an operating cooking appliance can be tested for functionality by the self-testing method according to the invention. The self-testing method according to the invention is also adapted, according to the invention, to the self-testing of a new appliance. This facilitates the final inspection of the new appliance before delivery to the intended customer. In addition, a calibration of the reference values can be carried out under standardized conditions when they are stored for the first time.

In particular, it is advantageous, according to the present invention, for the detected values to be stored in a values table for later checking Deviations can then be identified accordingly on the basis of this values table.

The method according to the invention can be advantageously initiated by a wired or a wireless connection to the cooking device.

It is a particular advantage of the present invention that the individual self-tests run essentially automatically, and that their results are automatically displayed and possibly transmitted and/or stored as data.

It is preferable to conduct the test during the night, when the cooking appliance is not being used. The user can also be instructed to perform the necessary preparations such as not to leave any cooking racks in the cooking compartment at the end of work on the preceding day.

The present invention also comprises a cooking appliance in the form of a convection oven, a steamer, or a combination of the two, namely, a convection steamer, with a cooking compartment, which can be closed by a cooking compartment door, and a plurality of actuators such as pumps, at least one heating device, at least one steam injection/generation device, at least one flow-generating device, and flaps and/or valves as well as temperature sensors and an electronic appliance control unit, wherein this cooking appliance is adapted to, and capable of, performing a self-testing method according to one of claims1-14.

