FR2713766A1 - Method and measuring device for determining the level, the turbidity and a foam component of the detergent in a washing machine or a dishwasher which can be controlled automatically. - Google Patents

Abstract

One or more beams of optical radiation (9) are directed, by means of the measuring device (3), on the fictitious surface of the laundry contained in a tank (1), at a respective angle of incidence greater than 0 degree and less at 90 degree, and the reflections are determined, with regard to their places of emission and / or reception, their dispersion and their attenuation, using a reception screen (4) of the measuring device (3) . Application in particular to automatic machines for washing clothes or dishes.

Description

The invention relates to a method for determining, using a device

  measurement, level, turbidity and any foam component of the detergent, which is located in a tank of the detergent system of a washing machine or a dishwasher

  can be controlled automatically.

  Previously known methods for determining the level of detergent usually use pressure sensors or so-called electronic level transmitters, the accuracy of which is poor. Furthermore, with such measuring devices, it is not possible to determine the turbidity of the detergent or of the foam component in the detergent. For this purpose, it is necessary to use other measuring devices in

  complex parts (German patent application DE-A-

  19 57 422, European patent application EP-A-393311).

  For their part, other devices for measuring

  this type are again unable to determine respec-

  one of the two or two other parameters. For example, turbidity sensors for laundry are known, which detect the transmissibility of light through the laundry, by means of a photoelectric relay with transmission or reflection of light. Foam detectors are also known based on another principle (see for example European patent application EP-A-278 239), according to which for example pressure pulses appearing at the level of the body of the heating element under the effect of bursts when foam appears are observed by means of a pressure sensor

sensitive.

  The object of the invention is to indicate a method and a measuring device of the type mentioned above, with which all the parameters indicated above can be determined without the implementation of a high expense, by means of a measuring device. measurement based on a single

physical principle.

  This problem is solved in accordance with the invention thanks to the fact that one or more beams of optical radiation are directed, by means of the measuring device, onto the imaginary surface of the detergent, at a respective angle of incidence greater than 0 and less than 90 and that the reflections are determined, with regard to their places of emission and / or reception, their dispersion and their weakening, using a reception screen of the measuring device. Thanks to the method according to the invention, it is possible, for the first time, to identify, by means of a measurement device based on a single physical principle, both the level and the turbidity of the detergent and a surface. detergent, possibly covered with foam, and determine the respective value with great precision, which is sufficient for applications in washing machines and in

dishwashing machines.

  A measuring device for implementing the method according to the invention is advantageously characterized in that a radiation beam from an optical transmitter disposed below the maximum service level is oriented at a greater angle of incidence at 0 and less than 90 on the fictitious level and that several optical receivers are arranged in the zone of possible reflected rays. Such an optical transmitter can be a simple infrared diode equipped with an optical system, or a laser diode, which sends its rays at a determined angle of incidence, on the fictitious surface of the detergent. At a location below the detergent and which one can expect to see the incident rays, are arranged several optical receivers in the form of photosensitive semiconductors. Depending on which of these receivers is illuminated and the intensity with which this illumination is carried out, an electronic evaluation circuit can determine which

  is the nature and magnitude of the parameter measured.

  These possibilities are provided by a measuring device for implementing the method according to the invention, which is arranged differently from the previous measuring device and in which a multiplicity of radiation beams from several optical transmitters arranged above the operating level maximum are directed at a respective angle of incidence greater than 0 and less than 90, in a time-phased manner, at the notional level and that at least one optical receiver is placed in the area of all rays

thoughtful possible.

  The indicated measuring devices identify a formation of foam on the surface of the detergent when, from the received light, a diffuse distribution, that is to say an irregular reflecting surface, can be identified. The measuring device can determine turbidity when the received beams of light are uniformly weakened. This is done by means of a cloudy detergent by the fact that parts of the rays which are emitted by the emitter in the direction of the surface of the detergent, are absorbed in the cloudy detergent. The level of the detergent surface can be determined in an explanable way by the fact that the light cone meets a horizontal or vertical receiver or inclined according to the level on different receivers. In a particularly advantageous manner, the measuring device according to the invention must be developed in such a way that the place (s) of emission and / or the place (s) of reception and / or the angle (s) of incidence are adjustable . This can be obtained on the one hand by the fact that several transmitters or receivers having the same angles of incidence are provided or that several transmitters or receivers having different angles of incidence are provided, the transmitters and / or receivers being able to be activated by an electronic circuit when requirements are imposed on the measuring device which are different in different sections of a program

washing and / or rinsing.

  The method according to the invention and a measuring device for the implementation of this method will be explained below in more detail, with reference to

several schematic figures.

  Figures 1 to 3 show, according to schematic representations, sections of a detergent container of a washing machine in which is placed a detergent, with different levels for the detergent in Figure 1, a detergent whose surface is covered with foam in Figure 2 and a detergent with a

  some turbidity in figure 3.

  Figures 4 to 6 show examples which correspond to those shown in Figures 1 to 3, on

  the basis of another exemplary embodiment, in which more

  Several light sources send their light rays reflected on the surface of the water to a light receptor. The lower part of the laundry tub 1 receives respectively a determined amount of laundry, which is shown in Figures 1 and 4 in the form of a non-cloudy and foam-free laundry located at different levels. In Figures 2 and 5, there is shown respectively a detergent, the surface of which is covered with foam and, in Figures 3 and 6, a cloudy detergent is shown respectively. In Figures 1 to 3,

  there is shown respectively an emitter 2 and an agency-

  ment 3 formed of several individual light receptors 4, which are fixedly arranged above a level

maximum possible amount of detergent.

  Above the arrangement of receivers 3 there is shown respectively a diagram of the light output, from which the lighting distribution is obtained with the light reflected on the light receivers 4 of the arrangement of receivers. In the example of FIG. 1, the light detergent situated in the detergent tank 1 produces, for the upper level, a reflection of light 5, which provides, in the case of receivers 4 arranged on the left according to arrangement 3, a light output having a high amplitude and a low propagation, in accordance with diagram 6. In the case of the low level of the detergent, which is represented by dashed lines, in the detergent tank 1 in FIG. 1, the reflections 7 reach the receptors on the right 4 of the arrangement of receptors 3 and produce, in these receptors, a light output corresponding to diagram 8. As a result, it is possible to make a clear and precise differentiation of the reflective level of the detergent in the laundry tub 1. The higher the level, the less the performance diagram 6 or 8

  light is shifted to the left and vice versa.

  The beam of emission light 9 finely focused in FIG. 2 is very widely dispersed at the level of the very irregular surface of the foam mat located on the detergent located in the detergent tank 1. Correspondingly, the light output for each light receiver here is naturally weaker, in their arrangement 3, than in the case of the plane reflecting surfaces of FIG. 1. But on the contrary a

  very large number of light receptors and possible-

  Even all light receptors are irradiated and deliver a corresponding lower voltage. This results in a very wide diagram curve, but also

  very flat 10 in the arrangement of receivers 3.

  In the case where the detergent contained in the detergent tank 1 is cloudy as shown in FIG. 3, the beam of rays is generally not widely dispersed at the level of the detergent surface, but is only simply reflected. Part of the light from the light beam 9 is however absorbed by the cloudy lye so that the beam of reflected rays 11, which is still still narrow, meets only a small number of receptors 4 of the receptor arrangement 3, and this with a reduced intensity also due to the absorption occurring in the cloudy detergent. Consequently, a curve 12 of the diagram of the light output is obtained, which turns out to be as narrow as in the case of the examples in FIG. 1, but with an intensity

significantly lower.

  All the criteria, which are illustrated here in detail in Figures 1 to 3, namely the detergent level, foaming and the turbidity of the detergent, can be detected in a measurement system 2 to 4 in one single measure. To this end, the detection of the place of impact of the reflection, the intensity of the light and the width of impact in the arrangement 3 can be measured and evaluated. This includes locating the maximum light output for the level of the reflective surface, i.e. detergent. The intensity makes it possible to distinguish between a light detergent and a cloudy detergent, and the propagation of the reflected rays received provides an indication concerning the inequality of the surface of the detergent, that is to say concerning the presence

foam.

  In the embodiment shown in Figures 4 to 6, the measurement system consists of a number of fixed light sources 13, which are successively excited, so as to emit light rays, according to the diagram shown in - below light sources, with a phase shift that is always constant and known to the receiver evaluation system. These light rays arrive with different staggered intervals over time, on the single light receiver 14, even in the case of different states of the detergent introduced into the detergent tank 1. For a high level of the corresponding detergent

  in FIG. 4, the light rays, which are emitted successively

  by light sources 13 starting from the left, in the form of reflections 15, 16 and 17 do not reach the receiver 14 - like for example reflection 15 - or only reach it in a very weakened - like reflection 16 - or reach the receiver completely - like reflection 17. Correspondingly, we obtain, in the intensity / time diagram, a light output curve 18 for receiver 14, the maximum of which is associated with a subsequent instant at which the rightmost light source 13 emitted its radiation beam. The high level in the

  laundry tub 1 can be associated with this later time.

  At a corresponding early instant, a maximum of light intensity already appears in the intensity curve 19, when the level of detergent is adjusted in accordance with the curve formed by dashes in the detergent tank 1. In fact already the reflected beam of radiation 20 completely reaches the receiver 14 while the beam of ray 21 meets this receiver only in a still very weakened manner and the beam of radiation 22 almost no longer reaches the receiver. Correspondingly, the intensity curve 19 decreases

  after the maximum towards zero.

  If, in accordance with FIG. 5, foam is present on the surface of the detergent, the beams of rays emitted successively by the light sources 13 are respectively reflected in a diffuse manner so that the receiver 14 is charged by a mixture of reflections with wide distribution, which results in the intensity curve 23 certainly flat, but dilated in

  the time for this purpose, above the receiver 14.

  In the case of the cloudy detergent contained in the laundry tub of Figure 6, an intensity curve 24 next to the receiver 14 is formed in a manner which resembles curve 18 in Figure 4. Due to the component of absorption which is strong compared to the component of reflection, the beams of reflected ray are however much weakened than in the case of the example of a light detergent, represented on figure 4. Consequently, the curve of intensity 24 appears with a lot shape

  more flattened than curve 18 in FIG. 4.

  The intensity curves 18, 19, 23, 24, which are obtained on the basis of different parameters, can be determined and decoded by an electronic evaluation circuit. Consequently, it is also possible, in the example of FIGS. 4 to 6, to precisely set and determine the three parameters (level of detergent, foaming and turbidity of the detergent) by means of a single measuring device formed by light sources 13 and a receiver 14 as well as an associated evaluation circuit, and not shown here in detail. In all the examples, the transmission locations and / or the reception locations are arranged so as to be adjustable so that the measuring device can be adjusted to the conditions respectively required. Naturally, a combination of the measuring devices drawn from the two examples shown is possible by the fact that, in the case of the use of an arrangement 3 of receivers, it is also possible to provide, instead of a light source 3 , also several light sources, which either emit beams of radiation successively in a time-phased manner, or among which always only one light source

  determined emits a beam of radiation, the reflection result of which in the arrangement 3 of receivers is compared with another reflection result, which comes from one of the other light sources.

Claims (5)

REVENDI CATIONS   1. Method for determining, by means of a measuring device, the level, the turbidity and a possible foam component of the detergent, which is located in a tank (1) of the detergent system of a washing machine linen or dishwashing machine, which can be controlled automatically, characterized in that one or more beams of optical radiation (9) are directed, by means of the measuring device, onto the imaginary surface of the detergent , under a respective angle of incidence greater than 0 and less than 90 and that the reflections are determined, with regard to their places of emission and / or reception, their dispersion and their weakening, using a reception screen (4) of measuring device (3).   2. Measuring device for implementing the method according to claim 1, characterized in that a radiation beam (9) from an optical transmitter (2) disposed below the maximum service level is oriented along a angle of incidence greater than 0 and less than "on the imaginary level and that several optical receivers (4) are arranged in the ray area thoughtful possible.   3. Measuring device for implementing the method according to claim 1, characterized in that a multiplicity of radiation beams from several optical transmitters (13) arranged above the maximum operating level are directed at a respective angle incidence greater than 0 and less than 90 ', in a time-phased manner, on the notional level and that at least one optical receiver (14) is arranged   in the area of all possible reflected rays.   4. Measuring device according to one of   claims 2 or 3, characterized in that the one or more   places of reflection are adjustable.   5. Measuring device according to one of   Claims 2 to 4, characterized in that the location (s) are adjustable.