Method for operating a washing appliance and washing appliance

Abstract

A method for operating a laundry washing appliance having a washing chamber to wash laundry the method includes selecting a default washing temperature and/or a washing cycle having a default washing temperature; supplying a detergent to the washing chamber; and determining a type of the detergent which has been added. When the detergent is of a first type, then the method includes comparing the default washing temperature with a threshold temperature and if the default washing temperature is higher than the threshold temperature, then emitting a warning signal and/or changing said default washing temperature.

Claims

1. A method for operating a laundry washing appliance having a washing chamber to wash goods, said method including: selecting a default washing temperature or a washing program having a default washing temperature; supplying a detergent to the washing chamber; detecting, by a sensor, a physical property of the detergent; determining a type of said detergent which has been added based on the physical property of the detergent detected by the sensor; wherein, in case said detergent is determined to be a first type including a deterrent in liquid or gel form, the method includes: comparing said default washing temperature with a threshold temperature; and when said default washing temperature is higher than said threshold temperature, emitting a warning signal or changing said default washing temperature.

2. The method according to claim 1, wherein said changing said default temperature includes: lowering said default washing temperature to a reference temperature.

3. The method according to claim 2, wherein said reference temperature is identical to said threshold temperature.

4. The method according to claim 1, wherein emitting a warning signal includes: emitting a visual or acoustic signal indicating that the default washing temperature is too high.

5. The method according to claim 1, wherein, after emitting said warning signal, the method includes allowing a user to modify said default washing temperature or said washing program.

6. The method according to claim 1, wherein, after changing said default washing temperature, the method includes: allowing a user to modify the changed temperature.

7. The method according to claim 1, wherein, in ease said detergent is of a second type, the method includes leaving the default washing temperature or washing cycle unmodified.

8. The method according to claim 7, wherein said detergent of the second type is a detergent in powder form.

9. The method according to claim 1, wherein determining the type of said detergent includes: measuring the conductivity of a washing liquid present in said washing chamber.

10. The method according to claim 9, wherein said measuring the conductivity of the washing liquid includes: determining the rate of change in conductivity caused by dissolution of said detergent in said washing liquid.

11. The method according to claim 1, including: measuring the turbidity of a washing liquid present in said washing chamber.

12. The method according to claim 11, wherein measuring the turbidity of a washing liquid present in said washing chamber includes: determining the rate of change in turbidity caused by dissolution of said detergent in said washing liquid.

13. The method according to claim 9, wherein determining the type of said detergent includes: measuring the conductivity of a washing liquid present in said washing chamber; and measuring the turbidity of a washing liquid present in said washing chamber; and determining that said detergent is a liquid or gel detergent when said conductivity is below a conductivity threshold and said turbidity is below a turbidity threshold; or determining that said detergent is a powder detergent when said conductivity is above a conductivity threshold and said turbidity is above a turbidity threshold.

14. The method according to claim 1, wherein determining the type of said detergent includes: selecting the type of detergent among a list of possible detergent types.

15. The method according to claim 1, wherein said threshold temperature depends on said selected washing program.

16. The method according to claim 1, wherein selecting a default washing temperature or a washing program having a default washing temperature includes: automatically selecting a washing program on the basis of one or more parameters of said goods.

17. A washing appliance including: a washing chamber to wash laundry apt to rotate around an axis; a control panel including one or more selection devices apt to select a default washing temperature or a washing program having a default washing temperature to wash laundry inside said washing chamber; a sensor configured to detect a physical property of a detergent in the washing chamber; and a control unit in communication with said sensor and said control panel, said control unit configured to: determine a type of the detergent in said washing chamber based on the physical property of the detergent detected by the sensor, and in response to determining that the type of detergent is a liquid or a gel, check whether said default washing temperature is higher than a given threshold, and send a warning signal or change said default washing temperature when said default washing temperature is higher than said threshold.

18. The washing appliance according to claim 17, wherein said sensor is located within said washing chamber.

19. The washing appliance according to claim 17, including a recirculating water circuit and said sensor is located within said circuit.

20. The washing appliance according claim 17, wherein said sensor includes a conductivity sensor.

21. The washing appliance according to claim 17, wherein said sensor includes a turbidity sensor.

22. The washing appliance according to claim 17, wherein said washing appliance is a washing machine or a washer-dryer.

23. The washing appliance according to claim 17, including a warning device connected to said control unit apt to warn a user when said default washing temperature is higher than a given threshold.

24. The washing appliance according to claim 17, wherein said control unit is apt to modify said default washing temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the present invention will be now described in greater details with reference to the attached drawings in which:

(2) FIG. 1 is a schematic view of a washing appliance operating according to the method of aspects of the invention;

(3) FIG. 2 is a graph showing the optimal temperature for liquid or powder detergents;

(4) FIG. 3 is a flowchart of the method according to aspects of the invention;

(5) FIG. 4 is a schematic view of a washing appliance according to an embodiment of the invention;

(6) FIGS. 5a and 5b are two graphs of an embodiment of a phase of the method of the invention; and

(7) FIG. 6 is a graph showing the optimal temperature for a liquid or a gel detergent.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

(8) With initial reference to FIG. 1, a laundry washing appliance operating according to the method of the invention is globally indicated with 1.

(9) The washing appliance 1, depicted here as the preferred embodiment, not limiting the scope and applicability of the invention, is a washing machine. The machine 1 includes a washing chamber 2, where goods, in this case laundry, are placed and removed. Washing chamber 2 is preferably contained in a casing 3 having an aperture closed by a door 4 pivotably mounted on the casing 3.

(10) The washing machine 1 includes further a control panel 10 apt to be used by a user to set parameters of washing programs (e.g. temperature, number of rinsing cycles, speed of spinning, etc.) and/or to select a washing program from a given list, through suitable push buttons 11 or knobs 12. Moreover, control panel 10 includes preferably a display 13 and one or more light elements 14.

(11) The washing machine 1 is programmed to function according to the one or more washing programs. These programs include for example a wool program, a cotton program, a quick program, etc. Each of these programs includes one or more washing cycles, these cycles being a pre-wash cycle (if needed), a main washing cycle, one or more rinsing cycles, a spinning cycle and optionally, in case of a washer-dryer, a drying phase.

(12) Washing programs are stored for example in a memory (not depicted in the appended drawings) accessible by a control unit 50 of the appliance 1. A washing program, among the available washing programs, is selected by the user using the control panel 10. Alternatively, the program is selected automatically by the washing machine 1 after laundry has been introduced within the washing chamber 2. Moreover additional parameters, as mentioned, can be selected by the user. The user can input the type of washing program desired and/or the default washing temperature of such a program. The maximum temperature of the water during the washing program is called default washing temperature. Control unit 50 controls the washing machine 1 according to the selected program.

(13) This is phase 23 of the method of the invention as per FIG. 3.

(14) The user, before or after phase 23, inserts a detergent of a given type inside the washing appliance 1, for example in a detergent dispenser or drawer (not shown in the drawings). The detergent is then flushed from the drawer and then introduced within the washing chamber. This is phase 22 of the method of the invention. Alternatively, the detergent can be supplied automatically by the appliance 1 itself as soon as the need of detergent is required during the washing program. In this case, the machine 1 includes a detergent tank (not depicted) in which the detergent is stored and, for example by means of a pump, is introduced in the washing chamber. The introduction of the detergent in the washing chamber can be made before or during the beginning of the washing program.

(15) At the beginning of the washing cycle, which could be the main washing cycle or of the pre-wash cycle if selected, of the selected washing program, the water inlet is opened and fresh water is inserted in the washing chamber 2.

(16) In order to determine the type of detergent introduced by the user, as required in step 24 of the method of the invention, either the user has selected the type of detergent introduced, for example inputting this information via the control panel 10, or the appliance 1 does the recognition automatically by means of one or more sensors. In the latter case, for example a conductivity sensor (not shown) can be positioned inside the washing chamber 2. Alternatively, the conductivity sensor can be located in a recirculation water circuit of the washing appliance.

(17) In the latter case, preferably, during the filling of the washing chamber 2 with fresh water, the conductivity of the fresh water can be measured so as to obtain a fresh water conductivity reference value, or alternatively a fresh water conductivity reference value may be preset in an operating program of the appliance 1.

(18) After or during the introduction of fresh water into the washing chamber, the detergent introduced by the user is also flushed into the washing chamber 2 or injected in the chamber by means of the pump connected to the detergent tank. After a given time, and preferably at given time intervals, the conductivity of the so obtained liquid (water and detergent mixture) is measured.

(19) The conductivity so measured is compared with one or more thresholds and also preferably the time in which the measurements have been made is taken into account. From the above mentioned comparisons and from the time in which the measurements have been taken, the detergent's type can be determined.

(20) In a different embodiment of the invention, as depicted in FIG. 4, the sensor includes a turbidity sensor 200 and a sensor of conductivity 500.

(21) The washing chamber 2 is suspended in a basin 412 having a downward first duct 414 connected to a drain 416 via a first valve 418. During operation of the machine 400, the basin 412 generally contains an amount of washing liquid and the first valve 418 is in the closed position. Washing liquid is fed via an inlet 426 by opening a second valve 428. A pump 420 is adapted to recirculate fluid exiting the basin 412 via a second duct 424. Means for influencing the course of the washing cycle, notably the valves 418, 428 and the pump 420, are controllable by the control unit 50. In this example, the sensor 200 is provided around the second duct 424 and provides a signal indicative of the turbidity to the control unit 50.

(22) More precisely, the sensor 200 may include a light-emitting portion 210 and a light-receiving portion 220 is provided on one side and on the opposite side of the second duct 424.

(23) After determining the turbidity of the fluid on the basis of the emitted and received intensities, the control unit 50 determines the type of detergent used.

(24) Advantageously, the walls of the second duct 424 are transparent to the wavelength of the light emitted by the sensor 200, at least in a segment around the sensor 200. Alternatively, apertures may be provided in the second duct 424, so that the light-emitting 210 and light-receiving portions 220 of the sensor 200 make direct contact with the washing fluid.

(25) Furthermore, washing machine 1 includes an additional sensor 500 located within the washing chamber 2, which measures the conductivity of the washing liquor as detailed above.

(26) According to an embodiment of the invention, the two measurements are used in the following way in order to determine the type of detergent introduced in the washing chamber 2.

(27) As visible in the graphs of FIGS. 5a and 5b, it is evident the large gap between signals when one or the other of the two type of detergents are used. In FIG. 5a, the upper curve is a plot of the conductivity versus time of a washing liquor with a powder detergent, while the lower curve is a plot of the conductivity versus time of a washing liquor with a liquid detergent. In FIG. 5b, the generally upper curve is a plot of the turbidity of a washing liquor with a liquid detergent, while the lower curve is a plot of the turbidity versus time of a washing liquor with a powder detergent.

(28) FIG. 5a shows that powder detergent is characterized by higher conductivity, since there is almost a factor of 10 between the two signals. Experimental tests performed by the Applicant have shown that conductivity signals of powder and liquid detergent do not superimpose even when high liquid amount is compared to small powder amount, so making this kind of measurements robust and reliable.

(29) Analogously, on FIG. 5b the percentage of transmitted light as measured by turbidity sensor 200 is plotted: powders cause greater water opaqueness, increasing light scattering and absorbance. So less light reaches the receiver 220 and lower output is given. In this case difference between two signals is less evident, but provides an additional parameter to be compared to conductivity in order to avoid mismatch or reading failure.

(30) It is important to underline these values, both referring to conductivity and turbidity, are scarcely affected by the specific brand of detergent (that is, different brands show similar pattern).

(31) Preferably, the conductivity is measured calculating a difference between conductivity of tap water (coming to the washing machine 1 via mains) and one of washing liquor (mainly, water and detergent dissolved therein) due to the fact that the conductivity of the water in the mains can change quite relevantly from one location to another. Therefore, conductivity of pure water is to be taken as zero-level in order to evaluate the role of detergent in determining conductivity itself. On following paragraph, the term conductivity is to be meant as difference between two conductivities measured: with detergent and the one of mains water.

(32) It is not necessary to compare washing liquor turbidity to tap water one, since it is reasonable that mains water is almost totally pure.

(33) Since powder detergent cause low optical transmittance (i.e. high turbidity) and high conductivity; while liquid detergent cause low optical absorbance (i.e. low turbidity) and low conductivity, both conductivity and turbidity signal can be compared to a specific threshold defined ad hoc in order to distinguish the type of detergent. One possible implementation of the algorithm is shown by the table reported below:

(34) TABLE-US-00002 TABLE 1 Type of detergent Conductivity Optical Transmittance Liquid LOW HIGH Powder HIGH LOW
where low and high have the meaning of below threshold and above threshold.

(35) Conductivity could be evaluated only on part of washing cycle, e.g. analyzing initial peak (clearly distinguishable at minute 1-2 on plot of FIG. 5a). This could be done in two different ways: analyzing graph slope over 1-2 minutes after initial peak (that is, conductivity variation over time, whose absolute value is greater when dealing with powder detergent). For example, on said plot after initial peak powder conductivity changes from c.a. 7 mS to c.a. 2 mS in about 90 s (55 S/s on average), while liquid one ranges on average only of c.a. 8 S/s (from 1250 to 500 on 90 s). These orders of magnitude are scarcely dependent on the specific brand of detergent taken into account. analyzing the maximum value of the peak, that is the point where difference between conductivities is maximum. For example, on said plot maximum value for powder detergent is above seven thousand, while liquid detergent gives a maximum conductivity between one and two thousands. These orders of magnitude are scarcely dependent on the specific brand of detergent taken into account.

(36) Such differences on conductivity and turbidity signals between liquid and powder detergents are due to their composition. At first, powder detergents contain great amounts of fillers, builders and alkali: zeolites are one of main components which do increase turbidity; on the other hand, zeolites aren't part of liquid detergents' composition.

(37) Carbonate, sulphate and silicate salts are responsible for high conductivity in powder.

(38) Combined use of turbidity and conductivity sensors prevents the measurements to be affected by water pollution from load high soiling levels and/or load pigments dissolution in water. Using only one sensor (e.g. turbidimeter) could imply in some circumstances that high soiling levels may lead to misleading results: particulate dirt cause high turbidity levels, which may refer to powder detergent. Since particulate dirt scarcely affects conductibility, the presence of powder detergent is excluded and the final feedback could be liquid detergent plus high level of particulate soil. As above mentioned, such problem would be solved using the combination of two said sensors.

(39) Similarly, some specific types of dirt may increase water conductivity even without affecting turbidity: simplest case is sweat. This may cause water to get high conductivity levels, even if liquid detergent is used. In this case turbidimetric analysis is supposed to avoid detergent wrong recognition.

(40) Therefore, according to the phase above described, the type of detergenteither liquid or powderis determined automatically by the washing machine 1 using two sensors 200 and 500. The output of those sensors is sent to the control unit 50 which calculates, for example using a suitable software, the type of detergent present in the washing chamber. Any other method to determine the detergent's type can be used as well in phase 24.

(41) In dependency of such determination, the method of the invention selects and adjusts the further phases. If it is determined that the detergent is of a first type, e.g. it is a liquid or gel detergent, as checked in phase 25, then a temperature check phase takes place, phase 26. If the detergent is not of a first type, for example it is a detergent in a powder form, then no action is required and the washing program can continue unmodified (phase 27), in particular the default washing temperature is unchanged.

(42) As shown in FIG. 2, the liquid or gel detergents are optimized for working in water at a temperature below or equal to 40 C. Therefore, if the detergent used is for example liquid or in gel form, a default washing temperature higher than 40 C. should preferably be avoided. For detergents in powder form, all temperatures are suitable, i.e. temperatures from 0 C. to 90 C.

(43) In the temperature checking phase 26, it is checked whether the default temperature selected either by the user or by the program itself is above or below a certain threshold. The threshold is memorized in a memory (not visible in the appended drawings) included in the washing appliance 1. In this example, the threshold is equal to 40 C., being the detected detergent a detergent in liquid form. However, the value of the threshold can be washing program dependent and also detergent's type dependent. If the default temperature is below the memorized threshold, then again no action is required and the washing program continues unmodified and unchanged. In particular, the washing temperature remains the default washing temperature (phase 28). Alternatively, if the default washing temperature lies below the threshold temperature (e.g. the user has selected a 90 cotton program using liquid detergent), then action is taken by the appliance 1.

(44) As depicted in phase 29, this action phase may include either: A. Warning the user by means of any warning device, for example making one of the light elements 14 blinking; B. Changing the default washing temperature to a temperature below or equal to the threshold temperature; C. As in B, but in addition warning the user of the change, substantially as in A.

(45) In this phase 29, therefore, the default temperature is changed to a value below or equal the changes the threshold, and/or the user is warned of the mismatch.

(46) As shown in FIG. 6, the threshold temperature of 40 C. represents the temperature at which liquid or gel detergents have their peak of activity. Therefore, in a preferred embodiment, if a temperature higher than such a peak temperature=threshold temperature is the selected default temperature, by the method of the invention the temperature is changed back to the optimal peak temperature.

(47) In some embodiments, the user is either allowed to change the temperature again following the advice of the washing appliance, or stick with the original selected high default washing temperature.