FI91890C - Washing or drying machine in which the weight of the washing is determined automatically - Google Patents

Description

91890

Washing or drying machine in which the weight of the laundry is determined automatically

The invention relates to a washing or drying machine in which the 5 rotating drums are preferably driven by a general type of electric motor and in which the garment load is automatically determined as a function of the inertia of the garments relative to the rotation axis of the drum.

It is known in the art that in household washing machines it is advantageous that the amount of water supplied to the machine as well as the amount of detergent and other parameters of the various stages of operation of the washing machine depend on the load on the drum. The operation of the dryers depends on myOs clothing load.

15 Various devices for automatically determining the load have already been presented. The invention relates to an improvement to the material described in EP Patent No. 84,402,090, in which the garment load is measured as the moment L of the inertia of the garments running around the axis of rotation of the drum. This torque is measured from the moment of use of the drum. The torque is measured by the intensity of the electric current flowing through the universal motor.

According to the invention, the general-purpose drive motor has an alternating current, and its speed is determined by the phase output of the processor. This processor makes it possible to measure the inertial movement of the garments from the value of the phase angle without the need for a special device for measuring the intensity of the electric current.

The phase angle usually depends on the value of the supply voltage 30 Vs given to the motor using the drum. This voltage can vary within wide limits from 187 to 242 volts, i.e. said value Vs is known within a margin of uncertainty which can sometimes lead to an undesirable lack of accuracy in measuring the load of clothing.

2 91890

In order to overcome this shortcoming, a washing or drying machine is provided according to the invention, which, in order to determine the garment load on the rune, includes means for determining the moment of inertia of the garments relative to the axis of rotation of the drum. The washing or drying machine according to the invention is characterized in that the drum motor is controlled by a computer, in particular a microprocessor, in a phase-connected cascade, which processor additionally determines the inertia torque from the phase angle and the input voltage value, and To measure the supply voltage.

The measurement is preferably performed without the use of Lisa devices such as a voltmeter, using only the information already in the computer. For this purpose, the computer sets a fixed value for the phase angle for a certain period of time, and during this time the rotational speed of the motor is determined, whereby the voltage is calculated from the predetermined phase angle and thus the measured rotational speed.

The ratio that connects the supply voltage to the phase angle 20 and the speed depends on other parameters which, in principle, do not vary. However, some of them, especially the friction torque that resists the rotation of the drum, may have values that change over time, i.e. due to the aging of the machine. To account for this variation, in one embodiment, a table is stored in a computer. This table shows the variations of the standard parameters according to the number of operating cycles of the machine in the silent relationship between the supply voltage and the phase angle and speed. For example, each time the machine is used, one unit is added to the calculator 30 to provide variation in a constant (or constants) in said ratio.

Preferred embodiments of the invention are characterized by what is set out in the following claims. The features and advantages of the invention will become apparent from the following description of some embodiments thereof.

II

3,91890, taken in connection with the accompanying drawings, in which Fig. 1 is a diagram showing a drum of a washing machine with its circuits, and Figs. 2 and 3 are diagrams showing the operation of a washing machine obtained according to the invention.

In the example, the washing machine (not shown in its entirety) is a type of household machine with a clothes drum with perforated cylindrical walls, which drum rotates on the inside of the tank 10 on a horizontal axis.

The drum electric motor 10 (Fig. 1) is of a general type. It receives an alternating current 11, for example at a mains frequency of 50 Hz, when applied by one of the switch switches 12, such as a triac.

15 The device 12 for the switch 12 and thus the motor 10 of the myGs has a microprocessor 13 connected to the input electrode 14 of the triac 12.

The microprocessor 13 calculates the setpoint speed for the motor 10. This setpoint speed depends on the program stored in its memory. This microprocessor generates a myGs comparator in terms of speed. For this purpose, there is an input 13x to which the output signal of the tachogenerator (i.e. tachometer) 15 used by the motor 10 is connected.

The microprocessor 13 transmits the opening angle Θ (Fig. 2) of the triac 12 in each half-cycle of the AC signal 11, i.e. the duration which this switch 12 conducts during each phase of the signal 11.

The curve in Fig. 2 shows the opening angle Θ on the x-axis-30a and the AC signal 11 on the y-axis. During one half cycle of the AC signal 11, i.e. with the phase angles Θ being 0 and π the valence of the radians, the triac is open, i.e. in the non-conductive state, the valence of the angles 0 and Θ and is the leading valence of the angles Θ and π. The microprocessor 13 emits a pulse of G-35 to close the triac 12.

«4 91890

This phase angle Θ, defined by the microprocessor 13, is used to measure the moment L of inertia L of the garments in the drum, i.e. to measure the load of the garments.

5 To this end, start with the following formula: C = (L + J) + CR (1)

dt R

In this formula, C is the operating torque, L is the moment of inertia of the garments with respect to the axis of the drum, J is the moment of inertia of the rune with respect to its axis of rotation, de / dt is the acceleration rate (or deceleration) of the drum and C is the load torque given by the drum.

In a universal motor, the operating torque is proportional to the intensity of the current flowing through its side as follows: C = KI (2) 15 where K is the constant in the motor and I is the intensity of the current flowing through its motor.

It is further known that the counter-electroelectric force E of the universal motor is proportional to its pyO-20 ripple speed. Therefore we can show: E = Κ'ω (3) where K 'is a constant.

It is also known that the voltage U at the motor terminals depends on the counterelectromotive force E, the impedance Z given by this motor 25 and the intensity I in the following ratio: 5 91890 U = E + ZI (4)

From this formula it can be deduced that S: U = E + ZI = Κ'ω + ZI = Κ '(ύ + (5) Λ

The voltage U applied to the motor is a function of the angle Θ 5 (Fig. 2) as follows: C7 = Vs f (θ) = + ig (6) Λ where Vs is the maximum amplitude of the voltage 11.

From formulas (5) and (6) the following can be boat:

Vsf (0) = K ^ + - ^ = K ^ + 4- <L + J ^ (7)

* K K dt K

According to the invention, the value L of the moment of inertia of the garments can be calculated from the above formula (7). However, it has been found that this formula takes advantage of the value Vs of the mains voltage, which can vary. For this reason, it is advantageous to measure the voltage Vs indirectly using a method in which no special measuring device is used.

In the first embodiment, the microprocessor 13 is programmed to set predetermined phase angle Θ values during successive cycles 20 and 21 with durations tx and t2 (Fig. 3). During the first period 20, when the mid-20 ton is t2, the phase angle is Øj. During the second period 21, when the duration is t2, the phase angle is equal to the second determined value 02.

Each value of the phase angle Θ corresponds to the rotation speed ω of the drum, which is measured by a tachogenerator (i.e. tachomet-25 rill) 15.

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During each of the phases 20 and 21, where the durations have been and t2, respectively, the rotational speed of the drum is constant, i.e. the acceleration άω / dt is zero.

Thus, during period 20, the above formula (7) may be represented in the form

Vsf (ei) K '<Ji1 ^ R (8)

/ C

During period 21, formula (7) may be represented in a corresponding manner

Vsf (e2) = K'v2 + - ^ R (9) 10 From formulas (8) and (9) it is possible to derive

Vs [f (02) -fiBj)] = κ '{<ύ2- <ύ2) (10) from which is obtained. O). - ω, ^ mj - Av (11> 15 Nain Vs can be calculated in the microprocessor as a function of θ2: η and θ2: η, which are constants, and ω2: η and ω ^ η as a function, which are measured.

The calculation is facilitated if we assume that f (Θ) is proportional to Ø, f (0) = Κχβ (12) where Kx is constant.

In the case of TM 20 7 91890 γΐ ω, - ω, ν · ί π (13>

In the calculations presented above, it was assumed that the load torque CR has the same value at the speed as at the speed ω2. The assumption is not strictly accurate.

5 However, it can be confirmed without compromising the accuracy of the measurement if the values 0: and θ2 do not differ too much from each other, i.e. if the said values are l & HellS.

For example, the values of Øx and θ2: η are selected so that during period 20 the drum rotates at an order of magnitude of 200 rpm and during period 21 the drum rotates at an order of magnitude of 40C rpm. In this example, the duration of the cycles is the same, about 18 seconds.

In the embodiment shown in Figure 3, periods 20 and 23 are followed by periods 22 and 23, the durations of which are t3 and t4, respectively, during which accelerations of a specified magnitude are applied to the drum. During each of these acceleration gradients, the phase angles and 0'2 are determined for the same velocity only. Here, L is determined by the following formula: 20 where dω1 / dt is the acceleration corresponding to the gradient 22 and d <i> 2 / dt is the acceleration corresponding to the gradient 23. These accelerations take place, for example, at speeds of 200 rpm and 400 rpm.

25 Em. the value Vs in formula (14) is obtained from a previous calculation performed in connection with formula (11) or (13). This value of Vs can be mytts measured directly.

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In the second embodiment, instead of having two successive phases 20 and 21, during which different phase angle values are arranged, there is only one period with a duration t5 (not shown), during which the phase angle θ3 is set and the speed ω3 is measured by the tachogenerator 15.

The value of Vs is thus determined by the following formula:

Vsf (d3) = ^ 83 = * 'ω3 + R (15) Λ

The term ZCR / K is considered to be constant, the Silia rotation speed ω3 deviates relatively slightly from the predetermined average of 10 v.

This term ZCK / K is entered into the read-only memory of the microprocessor when designing the washing machine supply system. Janni te Vs can thus be defined by the following relation: = S f (03) 15 In this formula

Kn = —R K

The correlation table ω3 and Vs vile are fed into the memory of the microprocessor. The value of Vs in Tai is immediately determined from the value ω3.

20 The load torque CR, which is mainly due to friction, varies as a function of the number of times the washing machine is used or the number of times it is used.

The law of variation of CR as a function of said usage speed can be determined experimentally and a silent correspondence table between the speed 25 and the value of torque CR is entered into the memory of the microprocessor.

• 9,91890

The number of revolutions performed by the machine is stored, for example, in an EEPROM-type memory connected to the microprocessor. In any figure, one unit is added after each cycle of operation, i.e. after it has first been detected that the power is on and secondly that the last stage of the washing machine operating program has been completed. It is clearly possible to store the number of revolutions in another device, such as an electromechanical calculator.

Claims (11)

1. Washing or drying machine which, for determining the load from the drums contained in the drum, includes means for determining the inertia of the clothes in relation to the axis of rotation of the drum, which can be controlled by a drum motor (10) (13), in particular a microprocessor, by means of a phase control command, which further determines the moment of inertia from the value of the phase angle and from the value Vs of the supply voltage, and that there is also a means for supplying said supply voltage to the machine. 2. A washing or drying machine according to claim 1, characterized in that the phase angle for supplying the supply voltage Vs at the beginning of the operation of the device is given a fixed value θ3, that the rotational speed of the drum ω3 is determined, for example, by a roof generator (15). and that the processor determines the chip value Vs from the value given for the phase angle θ3 and the measured velocity value ω3. 3. Washing or drying machine according to claim 2, characterized in that a speed feeder (15) has been connected to the input of the processor (13) for controlling the speed of the motor as a function of a ·. Of the processor's existing program memory. Washing or drying machine according to Claim 2 or 3, characterized in that the voltage Vs is determined from the previous condition: Κ'ω ^ + K "γ = -_ (21) sf (e3) 30 K 'and K' constants, f (03) a definite function of the predetermined phase angle θ3 and ω3 the rotational speed of the drum at phase angle θ3. «91890 A washing or drying machine according to claim 4, characterized in that the means for storing the number of operating cycles for the machine and for bringing the parameter K '' were due to this number. 6. A washing or drying machine according to claim 1, characterized in that a second phase is arranged, during which the phase angle maintains a constant value θ2, which is different from an understanding each Blf and the rotational speed ω2 is measured, the voltage Vs being determined from the given the phase angles θ2, and from the velocities measured during these two phases (ω2 and ωχ). 7. Washing or drying machine according to claim 6, characterized in that the voltage Vs is determined on the basis of the following ratio: jd_ ω2 - s 'Kl θ2 - Θ, 15 bad K' and K '' are constants. 8. Washing or drying machine according to claim 6 or 7, characterized in that the phase angles of care and θ2 are such that the velocity ωχ wins the 20 one phase years in the range 200 rpm and during the following year the rotational speed of the drum in the range 400 rpm. 9. A washing or drying machine according to any one of the preceding claims, characterized in that the processor determines the moment of inertia L from the phase angle and the voltage Vs on the basis of the following ratio: Vsf (Q) = κ'ω + -Ζ £ = Κ'ω + - ^ (L + Jj + ~ RKK at K bad ω is the rotational speed of the motor, K 'and K are constants, Z is the motor impedance, J the moment of inertia and CR is the torque of the drum. «91890 A washing or drying machine according to any one of the preceding claims, characterized in that the drum can be rotated with two different successive acceleration values for determining the moment of inertia, and that the moment of inertia L can be calculated on the basis of the difference between the one measure challenge during it understand the acceleration, and second, one measure challenge during the second acceleration. 11. A washing or drying machine according to any one of the preceding claims, characterized in that the drum motor is a universal AC motor. in