Patent Application
20180008118
The invention relates to a dishwasher comprising a working chamber and a sensor according to the preamble of claim 1.
A dishwasher of this kind is described, for example, in DE 10034546 A1. In the case of this item according to the prior art, the interior of a dishwasher is monitored by means of one or more radar sensors using the Doppler effect. This sensor system is very complicated and accordingly costly. Furthermore, it has not been possible to realize technically problem-free functioning of a dishwasher of this kind to date.
The object of the invention is to propose a dishwasher having improved program control, proceeding from a dishwasher according to the preamble of claim 1.
This object is achieved by the characterizing features of claim 1.
Accordingly, a dishwasher according to the invention comprising a sensor unit for identifying a spray arm movement in the working chamber is distinguished in that said sensor unit comprises at least one infrared transmitter and/or one infrared receiver.
This sensor unit is at least partially in the housing of the apparatus which is designed as an insert part and serves to supply and meter a working substance, such as a detergent, rinse aid etc.
An apparatus of this kind is called a metering apparatus in the text which follows. Furthermore, the terms “warewasher”, “dishwashing machine” and “dishwasher” are used synonymously in the text which follows, as are the terms “jet of water” and “jet of washing solution”.
A sensor unit according to the invention can be used to check program sequences during operation. In particular, it is therefore possible to detect whether the spray arm and/or which spray arm is rotating properly or is malfunctioning.
The use of infrared light allows reliable detection, in particular of the movement of the spray arm, largely without problems under the environmental conditions in the working chamber of a dishwashing machine during operation. Spray arms which are at a relatively large distance from the sensor unit or in an unfavorable position, for example in respect of the angular orientation, can also be detected owing to the large range of an infrared beam.
In this case, the functional principle of the sensor unit is based on infrared light being emitted by an infrared transmitter, being reflected in the working chamber and being detected again by an infrared receiver.
In order to identify spray arm rotation, an infrared beam, for example, can be reflected to the receiver by means of a reflector which is located in a stationary manner in the working chamber of the machine, wherein changes in the IR beam, for example in the intensity, which are induced by a rotating spray arm, a component which is fastened to the spray arm or by a jet of water or washing solution from the spray arm can be detected.
In this case, the stationary reflector used can be a separate component or a component which is present in any case, for example a region of the wall of the working chamber.
In another embodiment of the invention, a beam which is emitted by the IR transmitter is reflected into the receiver by the rotating spray arm or an element which is connected to said spray arm, for example a region of the spray arm wall, a separate reflector element which is fastened to the spray arm, a jet of water or washing solution from a spray arm nozzle etc. These reflections are therefore directly correlated with the rotation of the spray arm.
The reflections and/or changes in reflections are to be detected in a significant manner in particular when they take place in the vicinity of the transmitter and/or receiver, for example by a spray arm or jet of water rotating directly past the transmitter/and or receiver.
In a particular embodiment of the invention, reliably detectable reflection of the infrared light is ensured in that at least one spray arm nozzle is oriented in such a way that the jet of water or the jet of washing solution at least partially crosses the beam path of the infrared light. The reflections desired according to the invention can be created by the water or the washing solution in this case.
In an embodiment of this kind, the beam path of the infrared light is preferably formed, for example by additional optical elements, such that a focal point or at least one focusing zone is produced which is struck by said jet of water or washing solution.
In another likewise advantageous embodiment of the invention, the desired reflection is created by the spray arm itself. To this end, the arrangement and surface design of the spray arm can be provided in a corresponding manner. For example, a spray arm can have, at least in regions, a coating which is highly reflective to infrared light. Furthermore, the beam path of the infrared light and the position of the spray arm relative to one another can be arranged in such a way that the spray arm crosses the beam path at least by way of its reflection zone. A beam path which has a focal point or at least one focusing zone through which the spray arm is passed by way of its reflection zone can advantageously also be used in this embodiment.
In a further advantageous embodiment of the invention, the spray arm is equipped with a special reflector for infrared light. Reflectors of this kind can be formed by mirror surfaces and/or by refraction of light, possibly with the additional use of optical elements, so that incident infrared light is reflected in a targeted manner. In the visible range, reflectors of this kind are also known by the term “cat's eye” or “Luneburg lens”.
With reflectors of this kind, a reflection angle can also be provided in particular, which reflection angle takes into account the relative arrangement of the infrared receiver in relation to the infrared transmitter.
The housing of the metering apparatus, which housing contains the sensor unit, is advantageously of water-tight design. In this case, accommodating the sensor unit in the housing of the metering apparatus which is present in any case makes it easier to arrange it in the interior of the working chamber of the warewasher. Firstly, it is not necessary to provide an additional opening in the inner wall or the door of the working chamber as a result of this since the metering apparatus is to be arranged in a recess of this kind in the inner wall in any case. Furthermore, the housing is already of water- and washing solution-tight design in the case of the known metering apparatuses. All of the electrical control elements, even for the metering apparatus, which are located in the interior of the dishwashing machine door are already protected against the water or the dishwashing solution by the design of the housing according to the prior art.
Therefore, a sensor unit can advantageously be accommodated within a metering apparatus of this kind without relatively major sealing problems, for which reason an infrared-permeable window, for example, is provided in the housing. A window of this kind can be realized in a simple manner by appropriate seals or else by a fixed connection, for example by welding or adhesive bonding, to the housing wall of the metering apparatus in a reliably sealed-off manner.
In an advantageous embodiment of the invention, the additional arrangement of guide elements is further provided in order to keep water which is running off away from the beam path of the infrared light after passing through the spray arm. Water which is running down could cause reflections which produce undesired interference signals. Owing to guide elements, for example in the form of a canopy above the outlet of the infrared light from the housing, for example above a passage window, it is possible to ensure that water which is running down is guided laterally around said outlet.
In another embodiment of the invention, guide elements of this kind are provided on the inner wall of the working chamber, as a result of which the entire that here apparatus is protected against water which is running down, as is the infrared beam path.
Furthermore, the sensor unit, in particular the infrared transmitter and/or receiver, is preferably arranged in such a way that it is not situated directly in a jet of water or washing solution from a spray arm nozzle. Interference signals due to undesired reflections are also avoided as a result.
In a particular embodiment of the invention, the time sequence of the sensor signal is detected and an evaluation unit is provided in order to detect the periodicity or frequency of the sensor signal which is induced by the rotating spray arm.
Since the rotational movement of the spray arm is to be monitored according to the invention, it can be assumed that the signal is a periodic or frequency-dependent signal. Therefore, owing to the time detection of the sensor signals with subsequent evaluation in an electronic evaluation unit, selective evaluation for periodic signals can therefore be performed. On account of this measure, virtually all non-periodically occurring interference signals are already filtered or suppressed.
By virtue of determining the frequency, the rotation speed or speed of the spray arm can then be determined. if no periodic signal can be detected, this is a sign of a stationary spray arm, but at least of a non-freely rotating spray arm.
In the event of a malfunction of this kind of the spray arm, this can be, for example, displayed to an operator or else an intervention in the control of the program sequence can be made.
In a particular embodiment of the invention, an analog evaluation circuit is provided in order to detect the periodicity or frequency of the sensor signal which is induced by the rotating spray arm. A circuit of this kind can be realized, for example, using a so-called PPL (phase lock loop). Therefore, an oscillating input signal can be compared with the sensor signal in a comparator or differential amplifier and changes in the output voltage can be used to draw conclusions about proper rotation of a spray arm. Even if digital components are technically readily available for evaluating a sensor signal according to the invention, the use of an analog circuit may provide the technically more advantageous solution from cost points of view given appropriate numbers. The combination of an analog circuit with a digital evaluation arrangement, which intervenes only given a faulty output voltage of the analog circuit for example, would also be conceivable.
In the case of a digital evaluation unit, different algorithms can further be provided in order to analyze and to rule out disturbing influences. Instead of or in combination with the use of the periodicity as stated above, integration of the signal peaks, that is to say determining the area covered by the signal, for example, can also be used to identify and to rule out fault peaks. In this way, fault signals which do not follow the time sequence and the intensity of the reflections generated by the spray arm or the jet of water or washing solution can be identified and ruled out. Threshold value analysis can also be used instead of or in addition to other fault identification methods.
An exemplary embodiment of the invention is illustrated in the drawing and will be explained in more detail below with reference to the figures.
Specifically:
A warewasher door 7 is fitted to the front side in a rotatable manner, as is indicated by a rotation axis 8. A metering apparatus 9 for adding dishwashing agent is located in the warewasher door 7.
A sump container 10 is located in the base of the warewasher 1, said sump container containing, for example, the customary filters and the water outlet.
The evaluation and control unit can also be arranged in the interior of the warewasher door, as indicated in
The infrared sensor unit 11 is installed, for example, at the edge of the housing 19 of the metering apparatus
The graph according to
These interference peaks S1 and S2 can be identified and eliminated by suitable evaluation by means of the evaluation unit 18. This evaluation can be configured, for example, in such a way that only periodically recurring signals P1 to P5 are perceived as real sensor signals, non-periodic signals however being perceived as interference signals. Another way of identifying the interference signals involves, for example, integrating the corresponding signal peaks with respect to time, as a result of which the area which is covered by the peaks is mathematically determined. Since an integral value is to be expected within a specific interval given regular sensor signals, other signals, such as the linear interference signals S1 and S2 for example, can be identified and ruled out in this way.
These exemplary methods of else further methods for identifying interference signals, for example by means of threshold values in respect of the intensity or the like, can be used on their own or else in combination with one another.
If a malfunction, for example a stationary spray arm or a spray arm which is rotating too slowly, is identified on the basis of the sensor signal, thio can be displayed to the operator in a display.
The warewasher according to the invention can also be controlled depending on the sensor signal. For example, the quantity of water and/or the pump pressure can be varied. Nozzles which are controllable in respect of the orientation of the jet and/or shape of the jet are also optionally conceivable.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102016112442.7 | Jul 2016 | DE | national |
