DE69909492T2 - Method for determining the total inertia and unbalance in the drum of a laundry washing machine - Google Patents

Description

The present invention relates to a method for determining the total load and the imbalance load in a washing machine with a motor drive system for turning of the engine at a desired one Target speed. Under the expression "washing machine" all types of devices are supposed to a rotary drum, the speed of which is at least can reach a value at which the laundry by centrifugal force is pressed against the side wall of the drum. Washing machines and tumble dryers are intended to fall under the general expression above.

The technical problem for determination is the amount of laundry loaded in a washing machine drum known to the experts. The known technical solutions are based on the amount of water that is absorbed by the dry laundry on the Time to reach a certain target speed Drum needed or on the current drawn by the motor.

EP-A-0143685 discloses a method for determining the laundry mass from a measured value of the motor torque for driving the drum while an acceleration phase with constant acceleration. This Scripture does not teach the determination of whether and to what extent Load is imbalanced (i.e. not evenly on the side wall of the drum is distributed).

EP-A-71308 discloses a method to determine if there is an unbalanced distribution of laundry items in the Drum interior there by the current motor speed of the Washing machine is monitored with a speedometer (if the Engine speed changes by more than a certain amount means this that the laundry is unbalanced).

Neither of the above methods solve the problem of determining the load and the imbalance load, and a machine that simply combines the two methods mentioned would be used be too expensive since they have an electronic circuit for detection of the engine torque and a circuit for determining the engine speed change would require.

US-A-5507054 discloses a process with which the load by turning off the motor drive system and measuring that time to reach a certain lower speed is needed. This document reveals also a determination of the imbalance load by recognizing Variations in drum speed according to the aforementioned EP-A-71308. Such determinations are carried out one after the other, therefore the duration increases the wash cycle. Furthermore, do with the electronic circuit measured, various physical quantities (speed fluctuation, Time to reach a certain speed) this circuit quite expensive and complex, so that their reliability is reduced.

EP 0903845 also discloses a Method and a washing machine according to the preamble of the claim 1 or 8.

An object of the present invention is to avoid the aforementioned drawbacks and a process as well as creating a tax system that is both cheap, reliable and are fast, namely can make the two statements in a very short time.

According to a general aspect of Invention is accomplished by providing a known, a predetermined one Frequency pattern or spectrum signal that corresponds to the normal, periodic control signal at constant speed (which the Drum at the target speed) is added, the motor-drum / laundry system in such a way excited that by analyzing the speed feedback signal (e.g. by analyzing the frequency spectrum of this signal), the total inertia (and therefore the laundry mass) and at the same time determine the imbalance state of the system. According to one Aspect of the invention provides a mator drive system which an auxiliary signal with a predetermined frequency spectrum is supplied, the load and the imbalance load being determined by an analysis of the Frequency spectrum can be determined at different frequencies. The auxiliary signal is preferably a periodic signal with a Frequency, the frequency corresponding to the target speed of the motor is different. The imbalance load is very preferred and the total load by analyzing the frequency spectrum a frequency that corresponds to the target speed, or at a frequency that corresponds to the auxiliary frequency mentioned.

The main advantage of the method according to the present Invention is that the establishment of an imbalance condition the drum (and the measure of imbalance) and the amount of laundry in the drum in a very short time by the fact that Motor drive system supplied the auxiliary signal and the same frequency spectrum analysis at two different frequencies is used.

An advantage the advantage of the present Invention is that it is a method of compensation which provides load friction so that the load inertia or mass and the rotational speed selection, the on the inertia and imbalance moment based, lead to more accurate results than in known methods.

The present method can be used to determine the inertia or mass of the dry load and wet load can also be used. The present method can be used to determine the magnitude of the inertial load and the unbalanced load that helps select the speed of rotation.

The dynamic friction is caused by various components caused, for example, by friction the power transmission system, the ball bearing friction and in the case of horizontal axis washing machines Laundry friction at the front door. According to the present Invention can use lookup table data or the Neural fuzzy logic systems compensate data from the frequency spectrum analysis are derived. This lookup table data or this neural fuzzy logic system will or is for any type of washing machine as a result of experimental tests determined on the washing machine with predetermined values of Total friction performed have been. From the compensated data of the frequency spectrum analysis can be the compensated value of the total load and the imbalance load be determined, these values not by the dynamic friction to be influenced.

An embodiment of the invention is now based on the attached Drawings explained. Show it:

1 a schematic model of a washing machine,

2 1 is a schematic block diagram of the control system used in the invention.

3a . 3b . 3c Diagrams of system frequency gans used in the method according to the invention

4a and 4b Part of a flow slide program control used in the method according to the invention,

5a and 5b schematic diagrams showing the relationship between the frequency responses, the compensated frequency responses and the dynamic friction,

6 an example of fuzzy logic control for the imbalance and inertia determination system according to the present invention.

Detailed description of a preferred execution

The method according to the invention is used to the indolence or mass and the unbalanced laundry load in a rotating drum a washing machine, a dryer or a irrigation or to determine the drying machine. The procedure can also, if he wishes, compensate for the dynamic system friction of the rotary drum system.

wobei:
J die Gesamtträgheit ist, die an der Motorwelle vorhanden ist und das Trommel- und Lastdrehmoment umfasst,
γ der Viskositätsreibungskoeffizient ist,
T das Gesamtdrehmoment ist, das durch die Differenz zwischen dem Antriebsdrehmoment T_m und dem Widerstandsdrehmoment T_f gegeben ist,
ω die Trommeldrehgeschwindigkeit in rad/s ist.In 1 a mechanical washing and drying machine is shown. A motor M provides a torque T _m for the drum. Motor speed rotation is transmitted to the drum via a motion transmission system (not shown). The speed is maintained by means of a speed control system of a known type (not shown). Below is the simplified system of 1 Referenced without considering the particular engine control device. According to the second dynamic law applied to the shaft motor system, it can be said that the total torque provided is the sum of the inertial torque and the friction torque.

in which:
J is the total inertia that is present on the motor shaft and includes the drum and load torque,
γ is the viscosity friction coefficient,
T is the total torque, which is given by the difference between the drive torque T _m and the resistance torque T _f ,
ω is the drum rotation speed in rad / s.

The Laplace transform allows the transition from the time domain to the frequency domain, and the above equation can be written as follows: T (s) = s * J * Ω (s) + γ * Ω (s), where s = jω is the complex variable.

The transfer function between the total torque and drum angular velocity is:

An additional step can be carried out if it is taken into account that the motor torque is proportional to the input signal of the motor drive system a _s according to the formula T (s) = K _m * a _s (s). The above formula can be written as follows, assuming for simplicity that K _m = 1:

If the laundry load is not well distributed during drum revolutions, an unbalanced load with mass M _{u will} produce a speed variation that has an amplitude proportional to mass M _u .

If β is the angle between the axis of imbalance and a fixed reference axis, a new torque expression must be inserted into the torque equilibrium equation. This torque is due to gravity g and its value is given by: M u g r cos (β), where r represents the distance between the center of gravity of the imbalance load and the axis of rotation.

This additional torque can be taken into account in a very simple way by considering its effect as being added to the speed that would be achieved if M _{u were} zero. If this logical basis is used, the measured angular velocity ω (t) results in: ω (t) = ω 0 + M u gr | H (jω 0 ) | Cos (ω 0 t), where ω _{0 is} the system output signal under the same conditions with no unbalanced load and | H (jω ₀ ) | is the module of the transfer function H (s) calculated at frequency ω ₀ , namely:

The frequency spectrum of this function is in 3a given for a given value of the coefficient of friction γ (1 mm s / rad) and for some values of the inertial loads J (0.4 and 0.8). As can be seen, the amplitude of the frequency spectrum calculated at the frequency ω ₀ depends on three variables: the unbalanced load U, the inertial load J and the dynamic friction γ. In particular, the smaller the amplitude of the frequency spectrum, the higher the inertia.

In 3b (in which γ = 2 Nm s / rad), the great influence of friction on that under the analysis standing system can be recognized.

In summary it can be said: if an imbalance load occurs, contains the speed signal Fluctuations whose amplitude relates to the unbalanced weight, the total inertia of the system and the dynamic coefficient of friction.

The applicant discovered that the problem of determining the size of the imbalance and the total inertia is solved in a surprisingly simple manner by: 2 a periodic signal with a known frequency ω _inj (for example via a cosine wave signal) is introduced into the system and the frequency spectrum of the controlled variables is analyzed.

In 2 is instead of in 1 schematically shown open loop system considered the entire controlled system. All of the above considerations can be repeated in the same manner, using the closed loop transfer function H _c (s) instead of the open loop transfer function H, depending on the current control regulation of the speed control system. It should be obvious that the proposed method works excellently, regardless of the type of control device, because the method is based on the structural, mechanical properties of the system. Furthermore, to simplify the explanation, a constant target speed ω _{t should be} assumed, the value of which must be above the speed at which the laundry is pressed against the drum side wall by the centrifugal force.

With respect to the 2 the motor drive system is excited by two speed components, which are given analytical betting by: a s = + A * cos (2πt ω inj ).

Accordingly, the measured speed can be divided into two parts ω _t and ω _inj , so that the output w is the speed that results from the sum of the two drive component effects.

Null, und das vom Motor vorgesehene Drehmoment ist das geforderte, um die dynamischen Reibungen zu kompensieren. Im Fall der unausgeglichenen Lasten muss, wie vorher gezeigt wurde, das Drehmoment in der Lage sein, die Schwerkraft der Ungleichgewichtslast während deren Drehphasen zu kompensieren und die Durchschnittszielgeschwindigkeit aufrechtzuerhalten. Wenn dies erfolgt, wird ein Geschwindsgkestsschwankungssignal mit einer vom Ungleichgewicht selbst abhängigen Amplitude erzeugt. Das Geschwindigkeitsschwankungssignal wird generell dazu benutzt, die Ungleichgewichtsgröße auszuwerten, doch aufgrund der Tatsache, dass mit dem Ansteigen der Trägheitslast die Geschwindigkeitsschwankungsamplitude abnimmt, sehen die bekannten Verfahren angenäherte Schätzungen der wirklichen, unausgeglichenen Last vor. Die Folge bei diesen bekannten Verfahren ist, dass die Schleudergeschwindigkeit vermindert wird, um gefährliche Bedingungen zu vermeiden. Mit dem Verfahren gemäß der vorliegenden Erfindung ist es möglich, den aktuellen Wert der Ungleichgewichtslast zu bestimmen, so dass im Vergleich mit den bekannten Verfahren und Systemen höhere Schleudergeschwindigkeiten ohne jegliches Risiko eines mechanischen Fehlers der Waschmaschine eingesetzt werden können.The first component (a _c ) is determined by the error speed information and driven by the speed control activity. In the case of the balanced rest is the expression

Zero, and the torque provided by the engine is the one required to compensate for the dynamic friction. In the case of unbalanced loads, as previously shown, the torque must be able to compensate for the gravity of the unbalanced load during its rotation phases and to maintain the average target speed. When this occurs, a rate fluctuation signal is generated with an amplitude that is itself dependent on the imbalance. The speed variation signal is generally used to evaluate the imbalance quantity, but due to the fact that as the inertial load increases, the speed variation amplitude decreases, the known methods provide approximate estimates of the real unbalanced load. The consequence of these known methods is that the spin speed is reduced in order to avoid dangerous conditions. With the method according to the present invention, it is possible to determine the current value of the imbalance load, so that, compared to the known methods and systems, higher spin speeds can be used without any risk of a mechanical fault in the washing machine.

The second component (ω _inj ) has the task of "loading" the system in order to increase the effect of the inertial load. According to the invention, the analysis of the frequency spectrum of the motor speed is proposed in such a manner and

used that the inertial load (total load) and the imbalance load are clearly identified by means of the two frequency components ω _t and ω _inj . If it is difficult to solve this problem mathematically in the time domain, this problem is easily solved in the frequency domain. If the Laplace transform is used, the following equation applies: Ω (s) = H c (s) * a (s) = H c (s) * (a u (s) + a inj (S)).

Because of the frequency response theorem, the steady-state frequency response of the system upon a sinusoidal input signal is a sine wave with the same frequency (as the input wave) but with a different amplitude and phase shift φ. The system output signal thus results after the transition to: ω (t) = ω t + M u gr * | H c (jω t ) | Cos (ω t t) + A * | H c (jω inj ) | cos (ωinj t + φ)

wobei NSamp die Anzahl der abgetasteten Daten und ω = ω(T + kΔt) ist, wobei T die Anfangsabtastzeit ist.The behavior of the in 3c frequency response shown (where γ = 1 Nm s / rad) explains how the system reacts to different inertial loads. It is also easy to see that the higher the inertia, the higher the damping effect on the speed fluctuations when the transfer function modules H _c (jωt) | and | H _c (jω _inj t) | are considered (see the arrows at the target speed of 100 rpm, ie 1.66 Hz, in 3 ). The above equation can then be written as follows: ω (t) = ω t + Au * cos (ωt · t) + As * cos (ω inj · T + φ) l , where the expressions Au and As represent the transfer function _modules (multiplied by the M _u gr constant and the A constant) at the frequencies ω _t and ω _inj, respectively. Each expression can be calculated as follows:

where NSamp is the number of data sampled and ω = ω ( T + kΔt), where T is the initial sampling time.

The supplied signal type cos (ω _inj t) was selected only as an example and also because of its simple implementation, but the described method can also be carried out with any supplied signal type (periodic or non-periodic) with a known frequency spectrum. The inertial load and the imbalance load can now be calculated based on these two values Au and As.

Experimental tests with different inertia and imbalance loads have been carried out, allow implementation of a neural fuzzy logic system in a mini control device. Alternatively, a lookup table can be used from the inertia value from the combination of the system frequency response Au and As and the imbalance value is readable.

As already mentioned, the procedure allows according to the present Invention in a simple manner the compensation of the friction.

The following implementation is based on the average of the initial value of the speed control. Once the speed control, i.e. the PID parameters (proportional, integral or derivative expressions of the speed error) has been determined, a simulation of the dynamic friction, which is mainly caused by the load and the speed transmission system, can be carried out by means of a controlled braking system , If a constant inertia value is selected, the value provided by the speed control system a _c or different a _{s is} proportional to the friction in the steady state. The calculation of such a variable is thus determined by evaluating the average of a _s :

• – berechne das Alpha_Mean,
• – kompensiere das As* = f_π(As, Alpha_Mean) durch Kompensieren des As-Ausdrucks,
• – berechne die Ungleichgewichtslast, Trägheitslast = f_UL((Au, As*) auf der Basis der kompensierten As- und Au-Werte.

At this point, all variables are known; the sizes of the inertial load and the imbalance load can be calculated according to the following procedure:

• - calculate the alpha _mean ,
• - compensate the As * = f _π (As, Alpha _Mean ) by compensating the As expression,
• - calculate the imbalance load, inertial load = f _UL ((Au, As *) based on the compensated As and Au values.

The expressions f _π and f _UL are look-up table data or a neural fuzzy logic system which result from the experimental tests carried out.

Qualitative and simplified examples of the functions f _π and f _UL are given in the 5a and 5b played. The 5a shows the general correlation between the values of Alpha _Mean and the compensated value of As (ie As *), which is based on different curves of As and k. Once As * from the diagram of the 5a Such a value has been determined in the diagram of the 5b , which is based on different curves of the Au values, is used to determine the compensated value of Au. It is clear that the diagrams of the 5a and 5b are experimental diagrams designed for each type of watch machine for different values of known dynamic friction, total loads and imbalance loads. The lookup table data, the neural fuzzy logic system or the correlation diagrams can advantageously be stored in the central processor unit (in the microprocessor) that controls the washing machine.

wobei k von den Motoreigenschaften und dem Widerstandsdrehmoment des mechanischen Systems abhängt.The relationship found to compensate for the ace expression (in 5a shown) took the following general form:

where k depends on the motor properties and the resistance torque of the mechanical system.

A flowchart of the control algorithm is shown in the 4a and 4b shown. In 4a is the first blok 10 the start phase in which the scan counter is reset. If the number of samples is equal to or greater than a predetermined number, then the blocks compute 12 and 14 in 4b the frequency responses for determining the total load or the imbalance load. The one in the blocks 12 and 14 calculated values are the block 16 along with the value of Alpha _Mean , which stands for dynamic friction, to compensate for this friction. The compensated values of the inertial load (total load) and the imbalance load are the initial values of the control algorithm, and these values can be used by the washing machine's central processor unit for various purposes, for example to adjust the spin speeds or to adjust the amount of fresh water to be used during rinsing.

The 6 shows a scheme according to fuzzy rules, which is used in the case of a fuzzy control solution. The fuzzy rules are of the following types:

Rule 1 If As * is L and Au is M, then J is H and U is H.

Rule 2 If As * equals M and Au is L, then J is M and U is VL.

Rule 3 If As * is N and Au is VH, then J is VL and U is H.
Etc.

Claims (10)

Method for determining the load and the imbalance load in a washing machine with a motor drive system for rotating the motor at a target speed, characterized in that the motor drive system is supplied with an auxiliary signal which has a predetermined frequency spectrum, and that the total load and the imbalance load by means of a frequency spectrum analysis at different Frequencies are determined. A method according to claim 1, characterized in that the said auxiliary signal is a periodic signal Frequency that corresponds to the target speed Frequency is different. A method according to claim 2, characterized in that the total load and the imbalance load using a frequency spectrum analysis at a frequency that corresponds to the auxiliary signal mentioned, or at a frequency that corresponds to the target speed become. Method according to one of the preceding claims, characterized characterized that there is a compensation of the values of the total load and the. Has unbalanced load, the dynamic friction is considered and this compensation is based on experimental Tests based on different and predetermined values of the dynamic friction were. A method according to claim 4, characterized in that said compensation using lookup table data or of a fuzzy logic system is carried out. Method according to one of the preceding claims, characterized characterized in that said frequency spectrum analysis by means of the Laplace transform is performed. A method according to claim 6, characterized in that the module of the transfer function H (s), which is calculated at the frequency ω ₀ , has the following type:

where jω _{0 is} the complex variable, γ is the coefficient of friction and J is the inertial load value. Washing machine with an electronic control system, which is a motor drive system for rotating the motor under a target speed has, and with a rotating drum by the motor via a transmission system is driven, characterized in that the electronic Control system derat is designed to be the motor drive system supplied with an auxiliary signal that has a predetermined frequency spectrum has, the electronic control system being designed in this way is that it uses the total load and the imbalance load a frequency spectrum analysis at different frequencies certainly. Washing machine according to claim 8, characterized in that the electronic control system is designed such that a periodic signal is supplied to the motor drive system, which has a frequency equal to that of the target speed corresponding frequency is different. Washing machine according to claim 9, characterized in that the electronic control system is designed such that it the total load and the imbalance load by means of a frequency spectrum analysis at a frequency that corresponds to the auxiliary signal mentioned, or determined at a frequency that corresponds to the target speed.