MXPA06004415A - Method and apparatus for monitoring load size and load imbalance in washing machine - Google Patents

Abstract

A method of determining static and dynamic imbalance conditions in a horizontal axis washing machine is disclosed. The method utilizes a number of algorithms to automatically determine the total load size, the magnitude of any static load imbalance, and the magnitude of any dynamic load imbalance for anygiven load in a given washing machine based on power measurements from the washing machine motor. Methods of obtaining the algorithms for the given washing machine are disclosed.

Description

METHOD AND APPARATUS FOR VERIFYING THE LOAD SIZE AND UNBALANCE OF LOADING IN A WASHING MACHINE BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention is concerned with a method and apparatus for detecting the load size and detecting and correcting an imbalance condition in the rotating drum of a washing machine using energy information from an engine controller. It is particularly applicable to a washing machine that has a drum on an axis different from the vertical.

DESCRIPTION OF THE RELATED ART Washing machines use a perforated basket in general cylindrical to contain clothes and other items to be washed that is rotatably mounted inside an undrilled tub assembled to contain the washing liquid, which generally comprises water, detergent or soap and perhaps other constituents. In some machines, the basket rotates independently of the tub and in another machine the basket and the tub both rotate in this invention, the rotating structure is generically referred to as "drum", which includes the basket alone or the basket and / or any other structure that contains and rotates the load of clothes. Commonly, an electric motor drives the drum. Various washing cycles they introduce to the clothes and extract, from the clothes, the washing liquid, ending "usually with one or more cycles of centrifugation where the final rinse water is extracted from the clothes when the drum is turned in. - It is common to classify the machines washing machines by the orientation of the drum Vertical washing machines have the drum positioned to rotate around a vertical axis in relation to gravity Washing machines of a horizontal axis have the drum oriented to rotate around an essentially horizontal axis In relation to gravity, both washing machines "of vertical and horizontal axis extract the water from the clothes by rotating the drum around their respective axes, in such a way that the centrifugal force draws water from the clothes. The centrifugation speeds are commonly high in order to extract the maximum amount of water from the clothes in the shortest possible tube, thus saving time and energy. However, when the clothes and water are not equally distributed around the drum axis, an imbalance condition arises.

Typical centrifugation speeds in a vertical axis washing machine are 600-700. RPM and in a horizontal shaft at 1100 or 1200 RPM. In addition, the demand for greater load capacity establishes a demand for larger drums. The highest centrifugation speeds coupled with larger capacity boards aggravate emotional imbalance problems than in washing machines, especially in horizontal axis washers. Imbalance conditions become difficult to detect and correct exactly. As the drum of the washing machine rotates around its axis, there are generally two types of imbalances that can exhibit: static unbalance and dynamic unbalance. Figures 1-4 schematically illustrate different unbalance configurations in a horizontal shaft washer comprising a drum 10 having a horizontal axis 12. The drum 10 is suspended for rotation within a cabinet 14 having a front part 16 (in where access is normally provided to the interior of the drum) and a rear portion 18. A driving point 19 (usually a motor shaft) is commonly located at the rear 18. Figures 1 (a) and (b) show a condition of static imbalance generated by a static unbalanced load. Imagine a load 20 on one side of the drum 10 but centered between the front part 16 and the back part 18. A net torque t causes the axis 12 to rotate about the axis of rotation 22 of the combined mass of the drum 10 and load 20, resulting in displacement d of drum 10. This displacement, if minor, is often perceived as vibration at higher speeds. ' The suspension system is designed to handle such vibration under normal conditions. Static imbalances are detectable at relatively slow speeds such as 85 or 90 RPM when measuring the magnitude of the load imbalance (MOB) - because the loads. Static equilibria are correlated with the MOB. The dynamic disequilibrium is more complex and can be presented independently of the existence of any static imbalance. Figures 2-4 illustrate several different conditions where dynamic imbalances exist. In 2 (a) and (b), imagine a dynamic unbalanced load of two identical masses 30; one on one side 'of the drum 10 near the front 16 and the other near the back 18. In other words, the masses -30 are ~ on a line 32 inclined in relation to the geometrical axis 12. The moment of '• net torsion ti around the geometric axis 12 is zero, in such a way that there is no static unbalance. However, there is a net torque t2 along the geometric axis 12, such that the drum will tend to wobble around an axis different from the geometric axis. If the moment is high enough, the wobble may be unacceptable. Figures 3 (a) and (b) illustrate an imbalance static and dynamic combined caused by a frontal unbalanced load. Imagine a single charge 40 in drum 10 towards the front 16. There is a net torque t around the geometric axis 12, resulting in a static unbalance. There is also a twisting moment c21 around the geometric axis 12, resulting in a dynamic unbalance. The resulting movement of the drum is a combination of displacement and wobble. Figures 4 (a) and (b) illustrate a combined static and dynamic imbalance caused by a subsequent unbalanced load. Imagine a single charge 50 in the drum 10 towards the back 18. There is a net portion moment ti around the geometric axis 12 resulting in a static imbalance. There is also a torsional moment t2"around the geometric axis 12, resulting in a dynamic imbalance.The resulting movement of the drum is a combination of displacement and wobble.It can be seen that any individual unbalanced load has both static and dynamic effects. However, an unbalanced load coupled as shown in Figure 2 does not contribute to a static unbalance This coupled unbalanced load is equivalent to a combination of the two unbalanced individual loads in the analysis, which is the time of Figure 3 minus the moment of 'figure 4.

A single unbalanced load is detectable above a certain speed. to which the load of clothes sits inside the drum. At the rate of static unbalance detection (approximately 85 RPM for a horizontal axis washer), the torque t is transferred to the motor shaft, causing speed or power fluctuation in the motor. However, the estimated value is related only to the effect of the static imbalance. For example, in Figure 1, 3 and 4, the three individual unbalanced loads produce an identical value, regardless of whether the load is located in the front as in Figure 3 or in the back as in the figure 4. This static imbalance is correlated with the magnitude of the unbalance '(MOB) .. However, dynamically, there is a significant difference when an unbalanced load is in the front or in the back. The unbalanced frontal load in Figure 3 has a much larger torque t2 compared to that of the unbalanced rear load of Figure 4, because the engine driving point is at the rear. The effect of dynamic unbalance in a horizontal axis washing machine can be seen in Figure 5, where the magnitude of the unbalanced load (MOB) and the dynamic moment (or location of the part unbalance) posterior to front) are defined as two axes in a Cartesian coordinate plane. In this plane, the entire area is separated into two parts by a limit curve of the dynamic moment BE defined by the tolerances of the particular washing machine. Based on the theory of dynamic mechanics, the curve with BE is the moment that is related to the effects of the dynamic unbalanced load at given revolutions per minute. There is a set of such curves corresponding to different high speeds of centrifugation. The area above this limit curve is the area of unacceptable imbalance at a given centrifugation speed. The lower area is the accepted area of operation. Note that, as explained above, there is a significant difference in the effect of the moment on the .BE curve between the front and the back. "The unbalance on the front has larger dynamic effects that result in greater vibration. Imagine the detection of only the MOB, that is, the static imbalance.The dynamic effect is not taken into account.To avoid vibration in the front, you have to set a low MOB in the washing machine, assuming the worst case Consequently, the entire area between the curve BE and above the line AB represents an estimated difference between the actual speed allowed by the motor controller (limited by the line AB) and the maximum speed at which the machine could work (limited by the BE curve). A consequent result is an extra energy consumption during the drying cycle. If the MOB velocity were set higher, such-as in the CD line, the area between the BE curve and below the CD line represents a - sub-estimate for a frontal imbalance and the area between the BE curve and above of the CD line represents an over estimate for a subsequent imbalance. A consequent result is unacceptable vibration and high-speed noise due to under-estimation. - Thus, there is an additional need to detect the location of an unbalanced load in a horizontal axis washing machine, as well as the existence of any dynamic imbalance. Unfortunately, dynamic imbalance (DOB) is often detectable only at higher speeds. Both vertical axis and horizontal axis machines exhibit static imbalances, however dynamic imbalances are a major problem in horizontal axis machines. The vibrations caused by the imbalance result in higher energy consumption by the drive motor, excessive noise and decreased performance. Many solutions have been devised to detect and correct both static and dynamic imbalances. The correction is generally limited to abort the centrifugation, reduce the centrifugation speed or change the charges in or on the drum. . Detection presents the most difficult problem. It is known to detect the • vibration directly when using switches, such as mercury switches or micro-switches, which are coupled when excessive vibrations are encountered. The activation of these switches is released to a controller to alter the operational state of the machine. It is also known to use electrical signals from load cells on the drum support posts, which are sent to the controller. Other known methods take samples of speed variations during the centrifugation cycle and relate them to the energy consumption. For example, it is known that a controller sends a PWM signal (modulated pulse width). to the motor controller for the drum and measure a feedback signal for the RPM obtained at each revolution of the drum Fluctuations in the PWM signal correspond to the imbalance of the drum at any given RPM Still other methods measure the fluctuations of energy or momentum of torque when detecting current changes- in the drive motor Solutions to detect static imbalances when measuring torque fluctuations in motor are plentiful, however, there is no correlation between static imbalance conditions and imbalance conditions. dynamic; the application 'of the algorithm. from static imbalance to torque moment fluctuations will not accurately detect a dynamic imbalance. For example, an imbalance condition caused by a frontal unbalanced load (see Figure 3) will be underestimated by existing systems to measure static imbalances. Conversely, an imbalance condition caused by a subsequent unbalanced load (see Figure 4) will be overestimated, by existing systems to measure static imbalances. In addition, the - speed, torque and current in the engine. they can all fluctuate for reasons not related to the imbalance of the drum. For example, friction changes over time and from one system to another. Friction in a washing machine has two sources. One can be called "system friction". Due to differences in bearings, suspension rigidity, machine age, normal wear, engine temperature, belt tension and. similarly, the variation of system friction can be significantly significant between one washing machine and another. A second source of friction in a given washing machine is related to the size of the load and any condition of imbalance. U.S. Patent No. 6,640,372 to the applicant presents a solution for factoring conditions • no related to the imbalance of the drum by establishing a stepped speed profile where the average motor current is measured at each stage and an algorithm is applied to predetermined thresholds to investigate an unbalanced state of the drum. Corrective action by the controller will reduce the centrifugation speed to minimize vibration. The particular algorithm in the patent 372 may be accurate for investigating static imbalances. However, it is not completely accurate for horizontal axis washing machines because it does not accurately determine the various dynamic unbalance conditions and does not inquire information related to the load size. There is still another unacceptable condition of a rotating washing machine drum that does not involve static or dynamic unbalance, but instead establishes a point distribution that can deform the drum. A point distribution condition is illustrated in Figures 6 (a) and (b). Imagine two identical charges 60 evenly distributed around the geometric axis 12 and on a line 52 normal to the geometric axis. There is no torsional moment, either around the geometric axis 12 or along the geometric axis. Thus, there is no detectable imbalance at any speed. However, the centrifugal force, f acting on the loads 60 will tend to deform the drum. If the drum is a basket that rotates around a fixed tub as is common. In many horizontal axis washers, the basket can be deformed enough to touch the tub, increasing friction, degrading performance and causing unnecessary wear and noise. . Another problem in the reliable detection of imbalances in the production of washing machines regardless of the axis is presented by the fact that many motors, controllers and noise signal can vary considerably from one unit to another. Thus, for example, a change in the torque of the motor in a unit can be an exact correlation for a condition of imbalances given in that unit, but the same change in torque in another unit may not be an exact correlation for the same condition of imbalance. In effect, the problems of variation between units and signal noise are common to any device where the energy measurements are based on signals that are taken from electronic components and processed for additional use. There is a need in the art for an unbalance detection system for a washing machine, particularly horizontal axis washing machines, which can effectively, efficiently, reliably, and accurately detect the size of the load, the existence and magnitude of any condition of imbalance and detect other obstructions that can adversely affect performance. In addition, there is a need to determine. Exactly stable and robust energy information that can compensate variations in motors, controllers, system friction and signal noise from one unit to another.

BRIEF DESCRIPTION OF THE INVENTION These and other problems are solved by the present invention of a method for determining the size of a load based on its inertia in a given washing machine having a rotating drum driven by a variable speed motor. The method comprises the steps of establishing a speed profile for a washing machine that. it comprises a period of constant speed, an acceleration period and a deceleration period; start the engine to spin the drum sequentially to the constant speed period, acceleration period and deceleration period, measure the motor's energy output during each period, calculate an average power output by averaging the energy output in the constant velocity period, calculate a power fluctuation integral by adding the integral area above the average energy output for the acceleration period with the integral area below "the average energy output for the deceleration period, calculate a value that estimates the total load size by applying the power jitter integral to a predetermined algorithm and storing the total load size value in a memory location. Using the method of the invention, the total charge size for any given load can be determined automatically without regard to the friction in the washing machine. The value is available for later use in the detection of imbalances. Preferably, the algorithm is obtained empirically when modeling a machine. washing machine that has for meters similar to the parameters in the given washing machine. The data is obtained from the energy fluctuation integral of load sizes obtained. In another aspect of the invention, the magnitude of any load imbalance in the washing machine -given can be. determined by applying the energy jitter integral and the total load size value to a different predetermined algorithm. The resulting value is preferably stored in a memory location. The value represents the magnitude of a load imbalance and indicates whether or not there is a static unbalance in the given washing machine. The stored value is available for later use in the detection of dynamic imbalances. Preferably, the algorithm is obtained empirically when modeling a washing machine that has parameters similar to the parameters in the given washing machine. Data is obtained for the energy fluctuation integral of known load sizes at known sites along the horizontal axis. The method is preferably used in a horizontal axis layered machine. In a further aspect of the invention, the existence and magnitude of a dynamic load imbalance in a given washing machine can be found by recovering the magnitude of any load imbalance; operating the motor to rotate the drum at the lowest resonant speed for the washing machine given for a predetermined period of time; measure the energy output of the motor during the period of time; calculate the power integral of the energy output minus the average energy; calculate the value of the moment by applying the integal energy and the value of the total load size with a first predetermined algorithm if the magnitude of a load imbalance is equal to or exceeds a predetermined threshold and calculate a moment value to apply an integral of energy and the value of the total load size with uri second predetermined algorithm a certain magnitude of a load imbalance is less than the predetermined threshold. In this way, corrective action can be taken in a subsequent cycle of the washing machine given to minimize the agitation of the washing machine depending on the value of the moment. Preferably, the first and second algorithms are stopped empirically when modeling a machine, washing machine that has parameters similar to the parameters in the machine. washing machine given. Data are obtained for the energy integral of known load sizes at known sites along the horizontal axis. In another aspect of the invention, load imbalances are detected and manipulated when determining the energy jitter integral, the magnitude of any load imbalance and any moment value or before; The energy fluctuation integral is compared • a first maximum value; a signal is sent to the user indicating the need for manual re-balancing of the load if the power fluctuation integral equals or exceeds the first maximum value comparing the magnitude of any load imbalance with a second maximum if the integral of energy fluctuation is less than the "first maximum value, send a signal to the user that indicates the signal of manual rearrangement of the load if the magnitude of any load imbalance equals or exceeds the second maximum value, compare the value of the moment with a third maximum if the magnitude of any unbalance of discharge is less than the second maximum value, send a signal to the user indicating the need for manual rearrangement of the load if the magnitude of. The moment value equals or exceeds the third maximum value and sends a signal to the motor to advance at an optimum centrifugation speed if the magnitude of moment value is less than the third maximum value. The above methods can be used in a washing machine having a rotating drum, a variable speed motor to drive the motor and a programmable controller to "control the motor." Here, the control-designer is programmed to start the motor of the motor. according to any of the above methods.

BRIEF DESCRIPTION OF THE FIGURES In the figures: Figures 1"(a) and (b) is a schematic illustration of the concept of static imbalance, Figures 2 (a) and (b) is a schematic illustration of the concept of dynamic imbalance. caused by a dynamic unbalanced load Figures 3 (a) and (b) is a schematic illustration of the concept of dynamic imbalance caused by a frontal unbalanced load Figure 4 (a) and (b) is a schematic illustration of the concept of dynamic unbalance caused by a subsequent unbalanced load Figure 5 is a graph showing the magnitude 'of an unbalanced load (MOB) plotted against the dynamic moment (location) of the load. Figures 6 (a) and (b) is a schematic illustration of the concept of a point distribution condition. Figure 7 is a perspective view of a horizontal axis washing machine where the invention can be applied. Figure 8 is a graph showing a velocity profile according to the invention. Figure 9 schematically shows a circuit for measuring the DC distribution line voltage of a motor control inverter according to the invention. Figure 10 schematically shows a circuit for measuring the DC distribution line current of a motor control inverter according to the invention. Figure 11 is a flow diagram illustrating a calibration method of. displacement according to the invention. Figure 12 is a graph that schematically shows the calculation of the power fluctuation integral Pintegral. Figure 13 is a graph showing the velocity and energy curves over time for a balanced load of 7 kilograms.

Figure 14 is a graph showing the velocity and energy curves over time for a balanced load of 3 kilograms and an unbalanced load of 1 -kilogram. Figure 15 is a graph showing Pintegral plotted on the total load size. Figure 16 is a graph showing Pintegral plotted on the dynamic moment for several different load sizes, "derived from empirical modeling data, Figure 17 is a graph showing the curve resulting from the regression function applied to the curves of Figure 16. Figure 18 is a flow chart illustrating the determination of the magnitude of a load imbalance (MOB) and the total load size - (TL) according to the invention.- Figure 19 is a graph showing the energy integral of the actual energy minus the average energy a Spd2. { PINTmot) plotted on the dynamic moment for various sizes of 'different load with a static imbalance, derived from empirical modeling data. Figure 20 is a graph sng a moment ratio plotted on the total charge size, derived from the empirical modeling data of Figure 19.

Figure 21 is a graph that s., The energy integral of the actual energy minus the average energy in Spd2. { PINTmot) plotted on the dynamic moment for several different load sizes with a dynamic imbalance, derived from empirical modeling data. Figure 22 is a graph sng a momentum ratio plotted on the total load size, derived from the empirical modeling data of Figure 21. Figure 23 is a flow chart illustrating the determination of the existence and magnitude of a dynamic load imbalance. Figure 24 is a flow chart illustrating an unbalance detection system according to the invention.

DETAILED DESCRIPTION System 7 Figure 7 s a front loading horizontal shaft washing machine 100 of the most appropriate type for the present invention. Except for the incorporation of the methods and apparatuses according to the invention in the washing machine 100, the physical structure is conventional. Internally, the washing machine 100 has a drum 102 which comprises a rotary perforated basket 104, spliced inside . of an undrilled tub 106 containing the washing liquid during the various cycles of a washing process. It will be understood that the term "drum" refers to the rotating structure containing the laundry and washing liquid, whether that structure is the basket 104 alone or both the basket 104 and the tank 106 or any other equivalent structure, Variable speed motor 108 commonly drives the drum 102 either by means of a direct drive system or with pulleys via a band. The tub 106 is commonly supported by a suspension system (not s) which may include springs, dampers and the like. The present invention as illustrated in Figures 8 to 24 provides a system to reliably and effectively detect the total load (TL) size, the magnitude of any load imbalance (MOB) - and the existence of any dynamic imbalance (DOB ), using only motor control energy information and sufficiently premature in a wash cycle to effectively • prevent unacceptable vibration conditions and optimize the rotational speed for any given load. A predetermined velocity profile 120 is set as s in Figure 8, where the controller is programmed to start the engine at predetermined speeds Spdl-Spd4 for periods of TO to T9 time with ascending ramps and descending ramps. All periods of time are not more than a few seconds. The energy measurements of the motor controller are used to inquire values for TL, MOB and DOB. An appropriate corrective action can be directed by the controller depending on the derived values. In general, the time period from TO to T6 is used to estimate TL and MOB. The period of time T7 to T9 is for the detection of DOB. 1) Average energy value: The period of time T0-T1 is provided to measure and calculate the average value of energy for use in subsequent calculations. Pav is preferably investigated at Spd2, which in the illustrated embodiment is 100 rpm. 2) Integral of energy fluctuation: The period of time TI to T2 is provided to measure and calculate the energy fluctuation integral based on the average value of energy previously determined. The power fluctuation integral is correlated with MOB. 3) Estimated total load value: Time period T3 to T6 is provided to estimate the total load (TL) when measuring and calculating the total inertia during ascending ramps and descending ramps at identical speeds. Preferably it is made between Spdl and Spd3 where Spdl is 85 rpm in the embodiment illustrated. The Spd3 is 150 rpm in this case. The speed difference between Spdl and Spd3 is the velocity window for the estimated value of TL. 4) Dynamic load detection: Time period T7 to T9 is provided to detect the DOB effect. The drum is driven at a near speed, but under a first. Spd4 resonance speed. In this mode, Spd4 is 160 rpm. The lowest resonance speed for the illustrated mode is known to be 175 rpm. In the time period T7 to T8, the drum ramps upwards from Spdl to Spd4.

Energy measurement In this invention, an algorithm has been developed to verify the energy in real time. The energy input information is calculated from the DC distribution line voltage and the DC distribution line current of the motor control inverter. A microcontroller or digital signal processor (DSP) manipulates this signal processing. A variable speed motor control system drives the drum to follow the reference speed profile in a loop or closed loop state. A filtering technique is provided to reduce any noise impacts in signal processing. The energy P to detect TL, MOB and DOB in the The system of the invention is derived from the voltage of the main distribution line DC (Vdc) and the current of the main distribution line of CD (Idc) • The DSP preferably takes samples of Vdc and Ide simultaneously at a speed of taking of samples of 1 time every 50 microseconds or 20,000 times / second (20 kHz). In general, the sampling rate may be in a range of 20 to 50 kHz. Figures 9 and 10 show main line distribution DC voltage detection circuits and CD distribution main line current detection. It will be apparent that the components of the detection circuits, such as resistors, can vary from one controller to another, resulting in a displacement when measuring Idc of a given controller. Consequently, the calculation of energy P may not be exact from one controller to another. In practice, - current shifts in measurements are unavoidable. As a result, some autocalibration of the current shift is necessary for an exact energy calculation. The initial shift calibration occurs when automatically detecting both Vdc and Idc as soon as the controller is energized, determining the offset - and then making an adjustment to eliminate the offset. Detection at the normal sampling rate of 20-50 kHz occurs during the initialization of the controller of the motor where the induction motor is not driven (PWM is off) and the voltage of the CD distribution line is established. At the time of initialization, the measured current represents the current displacement. The current displacement is thus measured in each sample and averaged a variable number of times, preferably 216-512 (generally sufficient for accuracy). Preferably, a predetermined value is n = 512. Averaging occurs as follows: • '+72 +? + n 1 off -set n After averaging the measured current (shifted current) n times, a calibration value is calculated which, if applied to a sampled current when the motor is in operation, will result in a zero shift. After this, in the P energy calculations based on the sampled current and voltage, the calibration value is used to compensate the displacements. Referring now to Figure 11, you can see the flow of the stages in the calibration. After starting "200 of the motor controller, regardless of the architecture, normal initialization occurs, for example, initialization of the S / W modules, timers and other system parameters (202, 204, 206, 208). system reaches a predetermined 210 interrupt, the contexts are saved and the interruption flags are cleared. Then at 212, the system interrogates whether calibration has occurred or not. If not, then a loop begins where the PWM signals are turned off, so that the motor does not start and the sampling of current begins at the predetermined sampling rate (20-50 kHz). The displaced values are calculated according to the average in operation í0ff-set until the number of samples n (preferably 216-512) is reached, time in which the calibration is complete and the flag for the interrogation in 212 is adjusted to true. At that point, the control scheme of the motor 214 will be started. It is during the control scheme • of the motor presented the energy measurements P (adjusted in terms of displacement). The noise is always a component of the sampled signals received from the main distribution DC voltage and current circuits. The accuracy of the energy calculations can be improved by filtering the data points affected by the noise peaks. Such signals will have an acute transition between the sampled values. An adaptive mobile window average filter according to the invention filters such bad data points and is described herein. Suppose that at any instant k, the average energy of the last n (for example 256 points) of a Data sequence is given by: Similarly, at the previous time instant, k-1, the average energy of the last n samples is: * -? n? = k-n Therefore, "" t, v- "" V ", 1 /« and Pk ~ Pk- \ = - (2-? ~ L, PX = ~ (Pk -Pk-p) ni = k-n + li = kn "n 1 which can be expressed as: Pk ~ Pk-? + ~ (Pk ~ Pk-n) n Thus, at any time, a mobile window of values n is used to calculate the average energy of the data sequence. Three values can thus be continuously calculated for the mobile window: In addition, errors between the three average energy values can be calculated continuously compared, as follows: ek- \ - Pk + \ Pk- \ A comparison - in error operation will identify which errors' are large enough to be above a preset limit. In the event that the associated sample that resulted in the large error should be treated as a bad point, it will be discarded in the sense that the sample is not used and is no longer available for further processing. Thus, higher accuracy and stability are obtained. In the illustrated modes, discarding a bad sample means that neither the current samples. The voltage or the resulting energy calculation is not used in the imbalance detection routines described hereinafter, nor is it used in the calibration, nor is it used in addition to establish the mobile window of the filtering process. the output power information is stable, the motor control has to work at a steady state at a certain speed interval.In this speed range, all the parameters of the controllers and regulators operate in their unsaturated regions while driving the drum to strongly follow the special speed profile.

Determination of TL and MOB For a horizontal axis washer, there is a correlation between the total load size (TL) of the content on the drum and its inertia. Thus, the -independence is an appropriate variable to measure to determine the load size.

When the speed of the drum is suddenly changed, the inertia of the system makes an impact 'in the dynamic moment. The motor has to feed a higher torque to force the drum to follow the command speed profile 120. Accordingly, the torque information of the motor is correlated with the inertia of the system. In a variable speed motor system, the energy requirements will transfer the torque change to its energy P calculated from c and Idc. From here, the energy information is used as the variable to process. On the other hand, when present, an unbalanced load generates either speed or energy fluctuations. Such fluctuation is a link dominated by MOB. Thus, the processing of the jitter signal can be used to detect MOB. However, this fluctuation is also interacted by TL as a natural feature. Consequently, the TL information must be used to complete an exact determination of MOB.

Average energy value As mentioned above, the time TO to TI is the period to calculate the average energy value Pav, preferably at a slightly high speed Spd2. The average Pav energy will be used as a base energy value for the additional detection algorithms. The average energy is calculated as: P Paavv = ^? Pk N k = in. where, Pk is the real-time energy reading value in each sampling; and N are the total sample collection times in the period.

Integral of energy fluctuation Also as mentioned above, the time from TI to T2- is the period to calculate the value of the integral of the energy fluctuations. It is preferably taken at Spd2. Figure 12 is a diagram schematically illustrating the calculation of the integral area, where, Pintpos is the integral area of energy above the average energy; Pintneg is the integral area of energy below the average energy. The integral of the total energy fluctuation is the sum of the two values: Pintegral = Pin tpos - Pintneg (2) This value is related to the magnitude of the unbalanced load (MOB). However, the Pintegral value shows only partially the impact of the unbalanced load. The MOB value is determined when the TL information is available.

Estimated total load value The determination of the load size TL in a given washing machine at any given time must take into account the friction of the system and the friction induced by the load, including variations. As mentioned above, it is measured in a window between .Spdl and Spd3.-Thus, time period T2 to T3 is provided for the system to stabilize at the lowest Spdl of approximately 85 rpm. The time from T3 to T6 is the period, to 'estimate the load size TL. This portion of the speed profile 120 can be referred to as the "A" profile due to its appearance. It will be noted that the acceleration rate from T3 to T4 is the same as the deceleration rate from T5 to T6. In general, the dynamic performance of the system can be expressed as an equation Te - Tl = J- + B? + C (?) F (?) (5) dt where, Te is the moment of electromagnetic torsion of the motor; TI is the moment of torsion of the load; J is inertia and is assumed to be constant in the detection period; ? is the angular velocity of the motor; B is a viscous friction constant; C (?) Is a -function of friction that varies with speed due to the effects of unbalanced loading; and F (?) is a function of the fluctuation of speed, which covers all variations. - .-. When there is an unbalanced load, the system will demonstrate complex dynamic behavior due to variations in the components of the suspension. This dynamic behavior is too complicated to be expressed in a single well-defined function. However, the following is known: when there is no water inside the drum, TI is equal to zero. In the period of acceleration T3 to T4, equation (5) can be expressed as an integral in time on both sides: JTeposdt = J J-dt + J B? Dt + J C (?) F (?) Dt (6) In equation (6), - the item on the left side in the area of the torque curve of the engine as shown in Figure 5 and is expressed as: TEINTpos -Tav) dt. (7) The first item on the right side of equation (6) can be expressed as: \ j-? = J -Wir & (8) J dt where, 'Wint is the integral area in time of the angular velocity, and J is a constant inertia. In the deceleration period from T5 to T6, equation (5) can be expressed as an integral in time on both sides: JTenegdt = j J ~ dt + J B? Dt + J C { ?) F (?) Dt (9) Note that the first item on the right side is negative due to the deceleration. The left side of equation (9) can also be expressed as: TEINTneg = - Tav) dt (10) The first item on the right side of equation (10) is equal to equation (8) except that the sign changed to negative. Note that the items "on the right side for both equations (6) and (9) are identical because the velocity profile 120 runs at the same acceleration and deceleration ramp rate, subtracting equation (9) from the equation (6) produces: , _ (TEINTpos - TEINTneg) 2 'Wh? (eleven) In effect, Wint is "constant because the speed, ramp is fixed by the speed command.

When the torque is replaced with the energy, and the inertia with TL, the total load size TL can be expressed as: TL = Kl • (PINTpos - PINTneg) + K2 (12) Where, PINTpos = [Pk - Pav] ascending ramp (13) k PINTneg =? [Pk - Pav) descending ramp (14) and Kl and K2 are two constants, depending on the parameters of a washing machine. PINTpos and PINTneg are the energy calculated during acceleration and deceleration, respectively. Pintegral is like this PINTpos - PINTneg. Note that equation (12) arrives at a TL value without any calculation for friction. "It can be seen that the inertia of the system can be calculated by means of the two power integrals of the main distribution line- of CD without directly treating it. With no friction of the system, the impact of the friction has been automatically eliminated according to the invention.The integral of energy for acceleration is positive energy, the state of energization.However, the energy for the deceleration is in its Most negative part in braking state but can be positive (energized state) if the inertia of the system is too small, corresponding to the defined descending ramp speed, so both the torque and the energy can be used in this method It may be useful to discuss the friction compensation in greater detail.During the ramp-up period T3 to T4, the 'actual motor power exceeds any inertia and any friction of the system in order to reach Spd3. Commonly, there is a larger positive energy needed than would be expected if the friction forces were zero or minimal. During the ramp-down period T5 to T6, On the other hand, the engine is braking. The friction is always against the direction of movement and absorbs the dynamic energy stored in the system operating at high speed. Thus, in deceleration, the motor feeds only a portion of the energy otherwise necessary to follow the velocity profile. As the friction is greater, the positive motor energy will be - larger in ascending ramp, - but the negative motor energy will be smaller in descending ramp because - the dynamic energy of the system provides the energy consumed by the system. the friction Therefore, the sum total of the motor power in all. The detection cycle depends only on the inertia of the system, regardless of friction. These effects are transported empirically. Figure 13 shows the speed and energy curves over time for a balanced load of 7 kilograms in a horizontal axis washing machine. The velocity profile replicates a portion of the velocity profile 120 from 'T3 to T6. It can be seen that the energy to the ascending ramp exceeds the energy to the descending ramp. Similarly, Figure 14 shows the same graphs for an unbalanced load of 1 kilogram in a horizontal axis washing machine where the energy to the rising ramp still exceeds the energy to the descending ramp. Since the TL calculation is based on values Differentials, variations in the system are effectively canceled by the method of the invention which results in a robust estimate of TL. The method carries out an accurate estimation no matter how the friction of the system varies and how much unbalanced load exists. the determination The constants Kl and K2 for a given washing machine are obtained by modeling the washing machine with known total load sizes (TL). The data is collected by using a known load at a known location on the drum and measuring Pk while on the "A" portion of the velocity profile. TL is calculated as the sum of the known load and the unbalanced load created by the moment due to its location. The plot of TL versus Pintegral produces a linear curve. The slope of the curve is the constant Kl and the intersection with the Y axis is the constant K2, see Figure 15 for a sample chart of a horizontal axis washing machine given in accordance with the invention where Kl is 0.4835 and K2. "is 927.3. How I know . it states, MOB is a function of the integral energy fluctuation Pintegral, 'also as the total load size TL. Consequently, the MOB value can be quantified by a function defined as: MOB = F (Pintegral, TL) The determination of exactly what that function requires requires more modeling for a given washing machine. The Graph of known unbalanced load values for different known load sizes produces a series of linear curves. See, for example, Figure 16 which illustrates a graph of samples of the same horizontal shaft washer mentioned above. Each curve has a different slope. How the slopes change is key. Using a regression function, a resulting curve is shown in Figure 17, which can be identified as: .Kmobl • (1 + Kmob2 • TL) where Kmobl = 1/1450 and Kmob2 = 0.2. The average of the intersections on the y-axis of Figure 16 provides a constant Kmob3, which in this case is 380. Thus, for this example, MOB = Kmobi? i + Kmob2 'TL) •. { Pintegral-Kmob3) (16) Once the constants and functions are determined from the modeling for a given washing machine, TL and MOB can be calculated for any subsequent load when operating the "A" profile using the functions defined in equations (12) and (16) ). Figure 18 is a flow diagram showing the logic of how a processor can determine the values for MOB and TL using the above algorithms according to the invention. After loading the washing machine, the user starts a boot 300 to activate the system. A stopwatch is set to TO and the speed of the drum is ramped to Spd2 at 302. The sampling speed is determined. 'Real-time energy measurements of the engine are taken during TO to TI and Pav (304) is calculated. The energy fluctuations are measured from TI to T2 and Pintegral is calculated and saved (306). After this, the load size detection cycle in profile "A" from T3 to T6 is put into operation. At 308, the speed of the drum is reduced to Spdl and the timer is synchronized to T3. The real-time energy is again measured at the sampling rate and PINTpos is calculated during T3-T4 (310). ' Similarly, PINTneg is calculated during T5-T6 (312). After this, normally during T6-T7, TL is calculated and saved (314). In block 31-6, TL and Pintegral are introduced to the default function for MOB MOB is calculated.

Dynamic load detection In the system of the invention, the dynamic unbalanced load (DOB) detection is predicted in the fact that there are several resonance speeds below the operating speed where vibrations may appear due to DOB. A washing machine can vibrate detectably if it operates at one of these resonance speeds. This phenomenon provides the opportunity for early detection of DOB because DOB effects begin to show when the actual velocity is close to a resonance velocity. The system preferably uses a speed Spd4 that is close to, but below the lowest resonance speed for the given washing machine. With this speed, the DOB effects are shown and cause some measurable vibration, the vibration results in a detectable increase in system friction and energy consumption. Consequently, the motor controller has to emit a higher energy to maintain Spd4. When processing the. energy information, you can quantify DOB as long as it operates within speed profile 120. What speed to use to detect DOB. varies due to differences in the washing machine's suspension system and depends on the first resonance speed of the given washing machine. When the drum reaches a stable speed at Spd4, the integral of the energy of the real energy P a Spd4 minus the average energy Pav a Spd2 is calculated in the period of time T8 to T9.

PINTmot =? [Kc -Pk - Pav] During T8 to T9 (17) ür = l where, Kc is a constant, arbitrarily selected to amplify the resulting value for better processing. It will be understood that sometimes the value of Pk will be close to Pav, making PINTmot too small to be useful. In this case, Kc = 2.0. As with MOB, the energy integral calculated in time period T8 to T9. { PINTmot) is a DOB function. However, the final DOB value is also a function of MOB, if present, also as TL. Thus, there must be a determination of the existence of MOB. For a threshold determination of the existence of MOB, a value of 0.25 Kg is preferably used. Below that value, it is considered that MOB is non-existent. Above that value, it is considered that MOB exists. At an MOB value of 0.25 Kg or less, the washer will advance at a maximum centrifugation speed, without the detrimental effects of a coupled DOB. If MOB is absent, the dynamic detection for the MOT moment is caused by a single unbalanced load (SOB). If MOB exists, the detection for MOT is caused by an unbalanced coupled load (COB). If MOB exceeds the threshold, MOT can be expressed as : MOT = ^ (PINTmot - KfA) + Kf5 (18) 1 + Kf2 - ABS (TL - Kf3) where- Kfl, Kf2, Kf3, Kf4 and Kf5 are constants. The function and constants are determined by modeling the washing machine given as before. Here, the load size TL is known empirically (as determined previously). Also, the MOT moment is known since the various load sizes and their locations in the drum are known. PINTmot is calculated for several energy measurements at different loads and different moments. The graph of the moment. (MOT) against PINTmot for various load sizes produces different almost linear curves. See, for example, Figure 19, which illustrates a sample chart of the same horizontal axis washer mentioned above. Each curve has a different slope. Approximations of each curve produce a single intersection in the. axis x which is the constant Kf5. The constant Kf4 is the minimum value of PINTmot at the intersection of Kf5. The graph also of Ti against the ratio of the difference between known MOT and Kf5 to the difference between PINTmot and Kf4 produces a curve that can be defined as: m \ + Kf2 -ABS (TL-Kf3) where Kf3 is a maximum proportion. See Figure 20 as a sample chart of the v.TL ratio for the washer mentioned above. In this case, the constants have the following values: Kfl = 4.45 x 10"3, Kf2 = 0.09, Kf3 = 12, Kf4 = 7000, and Kf5 = 17 If MOB is less than 0.25 Kg, MOT can be expressed as, MOT = - (PINTmot- Km3) + Km where PINTmot > = Km3 (19) and MOT = Km5? PINTmot - Km6) + Km7 where PINTmot < Km3 (20) Kml, Km2, KM3, Km4, Km5, Km6 and Km7 are constant. As before, the function and constants are determined by modeling the given washing machine. Here, the plotting of a known moment (MOT) against the PINT ot calculated for the MOT at various load sizes produces several nearly linear curves above a certain point and a common near linear curve below the same point. See, for example Figure 21, which illustrates a sample graph of the same horizontal axis aforementioned. If Km3 is the coordinate on the y-axis of the certain point and Km4 is the coordinate of the x-axis, you can see that each curve by '5 above the coordinates (Km4, Km3) has a different slope. Similarly, the common curve below the coordinates • (Km4, Km3) seems to end at a point where PINTmot becomes flat. That point can be defined as (Km7, Km6). The slope of the common curve can be defined 0 as Km5. The graph also of TL- against the proportion of the difference between the known MOT and Km4. the difference between PINTmot and Km3 produces a curve that can be defined as: Kml \ + Km2 -TL 5 where Kml and Km2 are constant. See Figure 22 as a sample chart of the v.TL ratio for the washer mentioned above. In this case, the constants have 0 the following values: 'Kml = 2.8 x 10 ~ 3; Km2 = 0.11; Km3 = 9445; Km4 = 20.63; 5 Km5 = 2.1 x 10 ~ 3; Km6 = 7300; Km7 = 14.44. Figure 23 is a flow diagram showing the logic of how a processor can determine the existence and magnitude of a dynamic load imbalance (DOB), including whether it is a single unbalanced load (SOB) or an unbalanced load coupled (COB) using the above algorithms according to the invention. At the initialization of the sequence in block 400, the clock is set to T8 and the drum speed is accelerated to Spd4. In block 402, PINTmot is calculated according to equation (17) during time interval T8-T9. In block 404, MOB and TL are recovered from the memory and PINTmot is saved. MOB is compared to the threshold value at 406, which in the illustrated mode is 0.25 Kg. If MOB exceeds or is equal to the threshold, the routine moves to block 408 to begin the determination of MOT according to. a single load of dough. If MOB is less than the threshold, the routine moves to block 410 to begin the determination of MOT according to "a mass load coupled." Starting with block 408, a comparison is made in 412 between PINTmot and constant Kf4. If PINTmot is greater than or equal to Kf, then MOT is calculated at 414 according to equation (18). If PINTmoi is less than Kf4, then MOT will be very close to Kf5 and therefore it is supposed to be equal to Kf5. Starting with block 410, a comparison is made in 416 between PINTmot and the constant Km3. If PINTmot is greater than or equal to Km3, then MOT is calculated at 418 according to equation (19). If PINTmot is less than Km3, then MOT is calculated at 420 according to equation (20). Regardless of which route is taken, MOT is stored in memory for additional use. It will be understood that with the automatic de-termination of Pintegral, MOB, TL and MOT, the system according to the invention will have full capacity to handle a centrifugation cycle regardless of the size and distribution of any load on the drum. However, it is possible that the load may be so unbalanced that additional correction is impossible without physically redistributing the load. Thus, each washing machine will have a set of maximums for each respective value of Pintegral, MOB and MOT. Figure 24 shows a flow diagram of a typical imbalance detection process according to the invention, using the values mentioned above. At the beginning of cycle 500, Pintegral is calculated as explained above. In 502, if Pintegral is equal to or exceeds its corresponding maximum Maxl, then the system stops at 504 in "where the redistribution of the load may occur." Depending on the particular washing machine, the Redistribution can occur automatically when filling the tub with water, flipping the laundry load or some other means of distribution known in the art. It may be that manual redistribution is necessary, in which case the system can provide al-user notification. Preferably, a count is maintained at 504 and is incremented each time the redistribution cycle is put into operation. Ideally, a maximum M is provided and compared to the count at 505, such that the washing machine will avoid an endless circuit at 504. If the count is less than the M limit, the system then restarts and returns to start 500. If Pintegral is less than Maxl, then MOB is calculated at 506 as explained above. At 508, if MOB equals or exceeds its corresponding maximum Max2, then the system stops at 504 and notifies the user that manual redistribution of the load is necessary. If MOB is less than Max2, then MOT is calculated at 510 as explained above. At 512, if MOT equals or exceeds its corresponding maximum Max3, then the system stops at 504 and notifies the user that manual redistribution of the load is necessary. If MOT is less than Max3, then the system can continue at an appropriate centrifugation speed. Preferably, that centrifugation speed will be determined in accordance with the "energy centrifugation method" disclosed in the application for U.S. Patent No. 10 / 874,465 filed on 06/23/04, incorporated herein by reference. As shown in this process, the detection of . dynamic unbalance according to the invention can determine the location of a single imbalance when using 'the result of the estimated value of MOB and can make a precise decision on whether or not to advance at a high speed of centrifugation. For example, in the illustrated modality, the . The system will require either manual redistribution or a lower centrifugation speed for an unbalanced load of 1 Kg located on the front of the drum. On the other hand, the system will allow a maximum centrifugation speed for the same load located in the rear of the drum. In addition, any unbalanced charge coupled will be detected and the centrifugation speeds adjusted before the effects become harmful. While the invention has been specifically described in relation to certain specific embodiments or modalities thereof, it will be understood that this is by way of illustration and not limitation and. The scope of the appended claims should be interpreted as broadly as the prior art permits.

Claims (10)

1. CLAIMS 1.- A method for determining the size of a load based on its inertia in a washing machine given that it has a rotating drum driven by a variable speed motor, the method is characterized in that it comprises the steps of: establishing a profile of speed for the washing machine comprising a period of constant speed, an acceleration period and a deceleration period; put into operation the motor to spin the drum sequentially to the period of constant speed, acceleration period and deceleration period, measure the power output of the motor during each period, calculate an average power output by averaging the power allowed in the period of constant velocity, calculate 'an integral of energy fluctuation adding the integral area above the average energy output for the acceleration period with the integral area below the average integral output for the deceleration period, calculate a value which estimates the total load size by applying the energy jitter integral to a predetermined algorithm and storing the value of the total load size in a memory location, whereby the total load size is determined regardless of the friction in the washing machine and is available for later use in the detection of imbalances.
2. 2. The method according to claim 1, characterized in that the algorithm is obtained empirically when modeling a washing machine that has parameters similar to the parameters in the given washing machine and obtain data for the integral of energy-function of sizes of known load.
3. 3. A method for determining the magnitude of a load imbalance in a given washing machine having a rotating drum driven by a variable speed motor for rotation about a horizontal axis, by applying the energy jitter integral of the claim 1 and the value of the total load size of claim 1 to a predetermined algorithm and store the resulting value in a memory location, whereby the value represents the magnitude of a load imbalance and indicates whether or not there is an imbalance static in the given washing machine and also where the value is available for later use in the detection of dynamic imbalances.
4. 4. The method of compliance with the claim 3, characterized in that the algorithm is obtained empirically when modeling a washing machine having parameters similar to the parameters of the given washing machine and obtaining data for the energy fluctuation integral from known load sizes at known sites along the horizontal axis.
5. 5. The method according to claim 1, characterized in that the washing machine is a horizontal axis washing machine.
6. 6. A method for determining the existence and magnitude of a dynamic load imbalance in a given washing machine, which has a rotating drum driven by a variable speed motor, the method is characterized in that it comprises the steps of: determining the magnitude of a load imbalance according to claim 3; operating the motor to rotate the drum at the lowest resonant speed for a washing machine given for a predetermined period of time; measure the energy output of the motor during the period of time; calculate the energy integral of the energy output minus the average energy; calculate a moment value by applying the energy integral and the value of the total charge size to a first default algorithm, if the magnitude of the load imbalance equals or exceeds a predetermined threshold and calculate a moment value by applying the energy integral and the value of the total load size to a second predetermined algorithm, if the magnitude of the imbalance of load is less than the predetermined threshold; whereby corrective action can be taken in a subsequent cycle of the given washing machine to minimize-the vibration of the washing machine, depending on the value of the moment.
7. 7. The method according to claim 6, characterized in that the first algorithm is obtained empirically when modeling a washing machine that has parameters similar to the parameters in the washing machine. given and obtain data for the energy integral from known load sizes at known sites along the horizontal axis.
8. The method according to claim 6, characterized in that the second algorithm is obtained empirically when modeling a washing machine that has parameters similar to the parameters in the given washing machine and obtain data for the energy integral from load sizes known at known sites along the horizontal axis.
9. 9. A method to detect load imbalances in a given washing machine having a rotating drum driven by a variable speed motor, characterized in that it comprises the steps of: determining the power fluctuation integral, the magnitude of any load imbalance and any moment value according to the claim 6; compare the energy fluctuation integral with a first maximum value; send a signal to the user indicating the need for manual rearrangement of the load, if the power fluctuation integral equals or exceeds the first maximum value; compare the magnitude of any load imbalance with a second maximum, if the power fluctuation integral is less than the first maximum value; send a signal to the user indicating the need for manual rearrangement of the load, if the magnitude of any load imbalance equals or exceeds the second maximum value; compare the value of the moment with a third maximum if the magnitude of any load imbalance is less than the second maximum value; send a signal to the user indicating the need for manual rearrangement of the load, if the magnitude of the value of the moment equals or exceeds the third maximum value and sends a signal to the motor so that it advances at an optimum centrifugation speed, if the magnitude of the moment value is less than -the third maximum value.
10. 10. A washing machine having a rotating drum, a variable speed motor for driving the motor and a programmable controller for controlling the motor, characterized in that the controller is programmed to start the motor according to the method. of claim 9.