Patent Grant
8432160
This application is a United States national application which claims the benefit of the priority date of Dec. 27, 2007, which is the priority date of commonly assigned International Application PCT/IB2008/0003786, which was filed on Apr. 2, 2008, by Enrico Smargiassi for a METHOD FOR ESTIMATING THE WEIGHT OF THE CONTENTS OF A HOUSEHOLD APPLIANCE, upon which the present application is based, and which is incorporated by reference herein.
The present invention relates to a method for estimating the value of the weight of the contents of the oscillating assembly of a household appliance, in particular a washing machine, washing/drying machine or clothes dryer, adapted to carry out at least one treatment on textile items, in particular washing or rinsing or drying or spinning or dyeing. The household appliance is of the electronically controlled type, and the oscillating assembly is connected to the frame of the household appliance by means of a suspension system comprising at least one damper, which in turn comprises at least two mechanical elements adapted to move reciprocally, at least one magnetic element, preferably at least one permanent magnet, and at least one magnetic sensor, preferably a Hall effect or magnetoresistive sensor. The magnetic element and the magnetic sensor are housed in the damper, so as to detect the reciprocal motion of said at least two mechanical elements of the damper. The present invention also relates to a household appliance, in particular a washing machine, washing/drying machine or clothes dryer, adapted to implement said method.
In order to improve the washing performance of a laundry washing machine and optimize water and/or washing agent and/or energy consumption, it is useful to be able to estimate the value of the weight of the textile items loaded in the drum of said washing machine before starting a wash cycle.
Among the various possible methods for estimating the weight of said textile items, it is possible to measure the relative movement of the oscillating assembly of the washing machine with respect to the frame occurring when laundry is loaded into the drum: several types of sensing devices are currently available on the market which are adapted to measure said relative movement and which can be conveniently mounted to a damper of a washing machine, the relative movement between the piston and the cylinder of the damper being used for detecting the relative movement of the oscillating assembly with respect to the frame.
Patent application WO2007/031821 describes a washing machine wherein the relative movement between two mechanical elements (piston and cylinder) of a damper of the washing machine is detected by means of a magnetic sensor (e.g. a sensing device based on the Hall effect) applied to one of the two mechanical elements of the damper, a permanent magnet being applied to the other element.
Patent DE102006027295 describes an algorithm for obtaining a reading of a magnetic sensor such as the one installed in the damper of a washing machine according to patent application WO2007/031821 and for deriving the weight of the contents of the oscillating assembly of the washing machine from said reading. Said algorithm is based on theoretical curves of the suspension system (springs and dampers), which however do not take into account the tolerances of said system that arise once the system has been installed in a certain washing machine and cannot be foreseen a priori. This may lead to systematic errors in the detection of the weight of the contents of the oscillating assembly, since it is not possible to perform a calibration procedure capable of adapting the detection of the magnetic sensor to the different operating conditions of said magnetic sensor when installed in different washing machines (this also applies to machines of the same model).
In addition to the above-mentioned drawback, the algorithm of DE102006027295 also has the further drawback that it cannot take into account the deterioration suffered by the suspension system and/or other components connected thereto, such as the gasket, over the life of the washing machine, said deterioration affecting the detection of the weight of the contents of the oscillating assembly.
The object of the present invention is to overcome the aforementioned problems and/or drawbacks through a method, which is alternative to the one described in DE102006027295, for estimating the value of the weight of the contents of the oscillating assembly of a household appliance, in particular a washing machine, washing/drying machine or clothes dryer, adapted to carry out at least one treatment on said contents, in particular washing or rinsing or drying or spinning or dyeing.
The method according to the present invention is based on the idea of estimating the weight value by starting from identifying a mathematical function that relates the quantities involved to one another according to a measurement taken at no load from time to time, i.e. not stored in advance (e.g. in table format). In other words, a mathematical function y=f(x) is found which relates the measured quantity y, said measured quantity being preferably an electric parameter, in particular voltage, of the electric signal generated by a magnetic sensor, to the quantity x to be determined, said quantity to be determined being preferably the weight of the contents of the oscillating assembly of the washing machine. The quantity x to be determined can thus be quantified directly through the inverse mathematical function x=f−1(y).
Advantageously, the method according to the present invention has been so conceived as to take into account different phenomena which may affect accuracy in the determination of the quantity x after measuring the quantity y, and which may overlap or affect one another. Such phenomena may include: stuck damper; hysteresis in the positioning of the damper; structural tolerances of the household appliance and/or damper; settling of the oscillating assembly after the first few cycles; non-linearity of the magnetic field generated by the permanent magnet; ageing of the household appliance, causing wear of the mechanical parts thereof.
The above-mentioned objects and other objects are achieved through a method for estimating the value of the weight of the contents of the oscillating assembly of a household appliance incorporating the features set out in the appended claims 1 to 16, which are intended as an integral part of the present description.
The present invention also relates to a household appliance adapted to implement the aforementioned method and incorporating the features set out in the appended claims 17 to 21, which are intended as an integral part of the present description.
The method and household appliance according to the present invention will become more apparent from the following detailed description, which should be considered as a non-limiting explanatory example, and from the annexed drawings, wherein:
A household appliance, in particular a washing machine, washing/drying machine or clothes dryer, according to the present invention comprises a frame and an oscillating assembly, in turn comprising a drum adapted to house textile items to be treated and to be rotated about its axis by means of a motor device, and a tub adapted to contain water and/or wash liquid used for performing the treatment. A suspension system keeps the oscillating assembly suspended, while connecting it to the frame. Said household appliance also comprises an electronic control system with a central controller, and possibly also an interface device adapted to provide information to the user of the household appliance. Said interface device may be a luminous device, e.g. an electronic display or a LED array, and/or an acoustic device, e.g. a buzzer or a voice synthesizer.
A washing machine or washing/drying machine or clothes dryer according to the present invention comprises, within its suspension system, dampers connected to the oscillating assembly through a top mount and to the frame through a bottom mount hinged to a pin, which dampers provide the fundamental function of damping the oscillations of the oscillating assembly, especially during the spin phases. Said dampers comprise a cylinder, i.e. a cylindrical tubular element, within which a piston, which typically is also a cylindrical tubular element, slides and is braked by an element capable of generating adequate friction between the outer surface of the piston and the inner surface of the cylinder. Two different configurations are possible in regard to the installation of the dampers in the washing or washing/drying machine: piston constrained to the oscillating assembly and cylinder constrained to the frame, or cylinder constrained to the oscillating assembly and piston constrained to the frame. The above two different configurations are wholly equivalent for the purposes of the present invention.
A free-stroke damper, which is particularly suitable for use as a damping element in a laundry washing machine, is characterized by a characteristic curve similar to the one shown in FIG. 6 of patent DE102006027295. The range of relative movement between the cylinder and the piston of a free-stroke damper is divided into a first portion (generally called “free zone”), wherein the two elements are free to move with respect to each other without the damper exerting any resistant force, and a second portion consecutive to the first portion in both moving directions, wherein the resistant force of the damper grows considerably as the relative movement between cylinder and piston increases.
In the non-limiting example of
An electronic board 6 is applied to the surface of cylinder 3, secured thereto, for example, by means of a suitable base. Said electronic board 6 comprises:
The electronic control system of the washing machine is adapted to generate, instant by instant, at least one piece of information relating to the operating state of the household appliance, said information being usable by said processing means for the purpose of generating the digital signal representing the value of the weight of the contents of the oscillating assembly of the washing machine. It is also conceivable that the estimation of the value of the weight of the contents of the oscillating assembly of the washing machine does not take place by means of microcontroller 30 housed on damper 1, but through a different processing device on board of the washing machine: in such a case, damper 1 may have no processing means of its own.
The washing machine may advantageously comprise means for detecting the value of at least one physical quantity of said laundry treatment, said detection means preferably comprising a conductivity sensor and/or a turbidity sensor and/or a surface tension sensor and/or a pressure sensor and/or a temperature sensor and/or an unbalance sensor and/or a rotation speed sensor. Said detection means, which are operationally connected to the electronic control system of the washing machine, may assist said electronic control system in generating the information relating to the operating state of the household appliance. The electronic control system is suitable for adapting the wash cycle to be carried out by the washing machine as a function of both the reading of Hall effect sensor 12 and the readings of other detection means, if present.
The block diagram of
Said method has been developed by the Applicant after experimental studies conducted on the behaviour of a magnetic sensor, such as Hall effect sensor 12, applied to a free-stroke type damper like the one shown in
From the set of curves of
Block 100 represents the step of reading an initial value y0 of an electric parameter y, in particular voltage, of said electric signal when the oscillating assembly of the household appliance is empty. Once said reading has been taken, the method proceeds to step 200, wherein, based on the initial value y0 and on a plurality of predetermined parameters (said plurality of predetermined parameters comprising two to ten predetermined parameters, preferably four to six predetermined parameters, more preferably five predetermined parameters), a mathematical function is generated in order to relate said electric parameter y, in particular voltage, to the value of the weight x of the contents of the oscillating assembly of the household appliance, at least a portion of said mathematical function being preferably of the second order (i.e. the significant one for the estimation to be made). It is then assumed that the family of functions describing the relationship between the electric parameter y and the estimated weight x is the following second degree polynomial:
y=ƒ(x)=ax2+bx+c (1)
Subsequently, at step 300, a further value y1 of said electric parameter y, in particular voltage, is read after some contents have been loaded into the oscillating assembly.
Finally, at step 400, the weight x of said contents is estimated by using said mathematical function and said further value y1 of the electric parameter.
Steps 300 and 400 are preferably repeated every time some contents are loaded into and/or unloaded from the oscillating assembly of the washing machine.
Step 200 includes reading, at block 500, some predetermined parameters which may comprise, by way of non-limiting example:
Some of the aforementioned predetermined parameters are obtained through a calibration procedure which may be carried out on the household appliance at the end of the production line, whereas the remaining ones are determined during the household appliance development stage, based on the physical and geometrical characteristics of the assembly obtained after damper 1 has been installed in the oscillating assembly of the household appliance. In particular, they are obtained when calibrating third parameter y* and fourth parameter m.
As regards the determination of the predetermined parameters, it is carried out by studying and analyzing the curves of
First parameter Δy0 represents the difference between the maximum possible value y0sup and the minimum possible value y0inf of the electric parameter y in the absence of load (x=0). It is thus obtained that:
Δy0=y0sup−y0inf (2)
The second parameter Δy∞ represents the difference between the maximum possible value y∞sup and the minimum possible value y∞inf of the electric parameter y at full load (assuming x=32 as a full load condition). It is thus obtained that:
Δy∞=y∞sup−y∞inf (3)
The third parameter y* corresponds to the minimum possible value y0inf of the electric parameter y in the absence of load (x=0). It is thus obtained that:
y*=y0inf (4)
The fourth parameter m represents the slope of the characteristic load curve of the magnetic sensor when the damper is operating within the substantially linear operation range. θ being the angle of inclination of said characteristic curve with respect to the X axis, it is thus obtained that:
m=tg(θ) (5)
The fifth parameter γ corresponds to the ratio between the active range of the electric parameter y in the absence of load (x=0), which would be obtained if the active range at full load (x=32) were half the actual range Δy∞, and the actual range Δy0 in the absence of load. y0rif being the starting point corresponding to a final value exactly equal to ½ the active range at full load, it is thus obtained that:
In a simplified embodiment of the present invention, the aforementioned predetermined parameters may be valid along the entire active reading range of magnetic sensor 12. Should a higher resolution of the measurement of the relative distance between magnetic sensor 12 and permanent magnet 9, and thus of the weight x, be desirable, it will be possible, according to an advantageous embodiment, to divide the active reading range in the absence of load of magnetic sensor 12 into a plurality of sub-ranges, so that the first parameter Δy0 and/or the second parameter Δy∞ and/or the third parameter y* and/or the fourth parameter m and/or the fifth parameter γ may have different values in the different sub-ranges. This advantageous variant may provide for storing and reading values to/from a table.
In block 600 shown in
As intermediate coefficients, one may use three coefficients h, k, l, the expressions of which have been obtained from said experimental activity. By way of non-limiting example, some formulae which are suitable for calculating the three intermediate coefficients are listed below:
The method then proceeds to block 700, wherein the final point yf is calculated as a function of the three intermediate coefficients, and thus indirectly also as a function of the five predetermined parameters. For this calculation, it is assumed that the curvature of the function to be determined increases according to a quadratic law which is a function of the difference between the initial value y0 and the absolute minimum value y*. The final point of each curve therefore depends on the difference y0−y* according to the following quadratic law:
yf=h(y0−y*)2+k(y0−y*)+l (8)
The mathematical function generation step 200, which is at least partly of the second order and which relates electric parameter y, in particular voltage, to the weight x of the contents of the oscillating assembly of the household appliance, thus ends at block 900, wherein the coefficients a, b, c of the function itself are calculated. In general, said function coefficients depend on the five predetermined parameters, on the initial value y0 and on the final point yf. Since the experimental activity has revealed that the slope of the tangent to the full load curve is substantially equal to the linear progress of the free zone of damper 1, the Applicant has verified that the following formulae, provided herein by way of non-limiting example, are appropriate for determining the function coefficients:
The method according to the present invention may suitably take into account any physical phenomena that over time may modify the structure of the washing machine in which damper 1 is installed, thus altering the value of function coefficients a, b, c. Said phenomena comprise, in particular, the settling of the structure, which tends to move the oscillating assembly downwards and which begins after the very first few operating cycles of the washing machine and proceeds asymptotically until stability is achieved after some dozens of cycles, and ageing, which depends on the wear of the mechanical components (plastic catches, gaskets, plastic deformation, and so on) of the washing machine, and which as time goes by inevitably leads to a shift of the balance position of the oscillating assembly.
In order to cope with said physical phenomena, a group of predetermined parameters are modified in the course of the life of the household appliance, preferably by using a corrective function that relates the predetermined parameters belonging to said group to the number of operating cycles of the appliance and/or the operating time of the appliance and/or the trend of the readings of the electric parameter y over time. In particular, said group comprises the third predetermined parameter y*, which is appropriately modified at block 800 before determining the function coefficients a, b, c at block 900.
The present invention offers several advantages. First of all, it allows to overcome the drawbacks of the algorithm according to DE102006027295, because the estimation of the weight of the contents of the oscillating assembly is made more reliable by a calibration procedure capable of adapting the detection activity of the magnetic sensor to the characteristics of the damper and of the household appliance, in particular a washing machine or washing/drying machine or clothes dryer, adapted to carry out at least one treatment on textile items, in particular washing or rinsing or drying or spinning or dyeing, in which said magnetic sensor is installed. Secondly, the present invention advantageously allows to take into account, for the purpose of estimating the weight of the contents of the oscillating assembly, any phenomena which may occur during the life of the household appliance, such as settling, ageing and/or any other deterioration phenomena affecting components of the damper and/or appliance. In the third place, if the household appliance, in particular a washing machine or washing/drying machine or clothes dryer, adapted to carry out at least one treatment on textile items, in particular washing or rinsing or drying or spinning or dyeing, comprises interface means, consisting in particular of a visual interface such as a screen, operationally connected to the magnetic sensor, preferably a Hall effect 12, the present invention makes said household appliance capable of providing the user with useful information as the oscillating assembly is being loaded.
The method according to the present invention may in fact comprise the step of:
v) communicating to the user of the household appliance, through the interface means, at least one piece of information relating to or depending on the estimation of the weight of the contents of the oscillating assembly.
Once it has been finished, step iv) is followed by step v); this step may be carried out automatically every time any contents are loaded into and/or unloaded from said oscillating assembly, or else under a specific request by the user of said household appliance, said request being in particular sent through the interface means (e.g. by pressing an appropriate push-button included in the interface means or by issuing an appropriate voice command).
The information relating to or depending on the estimation of the weight of the contents of the oscillating assembly, which is made available to the user, may comprise:
The present invention has been described with reference to a particular example of embodiment of the method it relates to, but it is clear that many changes may be made thereto by those skilled in the art without departing from the scope defined by the appended claims. In particular, the formulae used in the present description for determining parameters and coefficients may be replaced with equivalent or alternative ones.
| Number | Date | Country | Kind |
|---|---|---|---|
| TO2007A0943 | Dec 2007 | IT | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2008/000786 | 4/2/2008 | WO | 00 | 11/30/2010 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2009/083760 | 7/9/2009 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6065170 | Jang | May 2000 | A |
| 20060053839 | Matsushima et al. | Mar 2006 | A1 |
| Number | Date | Country |
|---|---|---|
| 8905566 | Jun 1989 | DE |
| 4319614 | Aug 1994 | DE |
| 10 2006 027295 | Jul 2007 | DE |
| 0972874 | Jan 2000 | EP |
| 1094239 | Apr 2001 | EP |
| 1258556 | Nov 2002 | EP |
| 1220961 | Feb 2004 | EP |
| 2169039 | Sep 1973 | FR |
| 09313777 | Dec 1997 | JP |
| WO 02097374 | Dec 2002 | WO |
| WO 2007031821 | Mar 2007 | WO |
| WO 2008012651 | Jan 2008 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20110062952 A1 | Mar 2011 | US |
