SI25920A - The procedure for detecting characteristic frequencies in a drum washing machine - Google Patents

Abstract

The present invention relates not to a process for detecting the natural frequencies of oscillation of the housing of a washing machine, during its operation, with regard to the quality of its installation and the substrate on which it is installed. The process comprises an active system for detecting the transfer of force to the ground, which enables the simultaneous detection of extraordinary and dynamic loads in the drum and the identification of the dynamic properties of the washing machine. By controlling the speed of the washing machine drum, it is possible to actively adjust the washing cycle according to the loads in the drum and the dynamic properties of the washing machine. According to the present invention, at least one calibration is provided at the place of installation of the washing machine at the user, thus identifying the dynamic properties of the entire washing machine - substrate system.

Description

OWN FREQUENCY DETECTION PROCEDURE FOR DRUM WASHING MACHINE

The present invention relates not to a method of detecting the natural frequencies of oscillation of the housing of a washing machine, in the operation of it, according to the quality of its installation and the substrate on which it is installed. The washing machine comprises a housing with a front wall in which the filling opening is designed, a movable door with which it is possible to close said filling opening, a washing tub arranged in said housing and comprising an opening facing the front wall of said housing and in it a washing a laundry receiving drum, the washing drum comprising an opening at least approximately aligned with the opening of said bathtub and said filling opening in the front wall, a sensing means for directly or indirectly measuring vibrations, a storage, process, control and display unit

During the operation of the washing machine, relatively large centrifugal forces occur mainly due to the eccentricity of the center of gravity of the laundry rotating together with the drum, causing dynamic forces on the tub in which the drum is arranged and through connecting elements such as springs and damping elements. , also on the housing of the washing machine. A large part of these forces is transmitted to the surroundings via the support legs of the washing machine, which are attached to the housing of the washing machine. As a result, elements of the surrounding building and unwanted noise may vibrate. A marked increase in vibration amplitudes occurs in the resonant range of the washing machine, ie in the case of the interaction of the rotational frequency of the washing machine drum and the natural frequency of the washing machine. The natural frequency of the washing machine is conditioned by the structure of the washing machine as such and by the elasticity of the substrate on which the washing machine is mounted.

The extraordinary arrangement of the laundry or its center of gravity in the drum causes increased vibrations during the operation of the washing machine, which is usually solved by repeated redistribution of the laundry until an acceptably small eccentricity is reached. Such a solution is disclosed, for example, in US Pat. No. 6,401,284 BI. Despite the acceptably small mass weight of the distributed laundry, the laundry can still be distributed during the operation of the washing machine, when the weight mass of the distributed laundry is acceptably small, but at the same time a large mass deviation load is present. To eliminate the increased vibrations, however, the perception of the extraordinary mass of the distributed laundry is not sufficient, as information on the mass deviation load is also required, which the mentioned known solution does not teach.

From the publication of patent application no. WO 2014/004328 is a known solution for reducing the vibrations of the washing machine by installing a trio acceleration sensor on the washing group. Such a solution makes it possible to detect an extraordinary and mass deviation load in the drum of the washing machine, thus avoiding increased vibrations and the transfer of force to the ground in the operating range of the washing machine when spinning is switched on. This type of solution is aimed at reducing the vibrations of the washing group or. excitation forces, but does not provide information on the dynamic properties of the entire washing machine, such as natural frequency, resonance, and the like.

It is further from the publication of patent application no. DE 10 2015 106 849 Al known solution by installing a triaxial accelerometer on the housing of the washing machine, which enables active control of vibrations of the entire washing machine. Known solutions for active vibration control of the washing machine are based on the measurement of accelerations on the tub or housing, where the vibration control is performed using the maximum allowable amplitudes without knowledge or. identification of the dynamic properties of the washing machine.

It is an object of the present invention to provide a method for detecting the natural frequencies of oscillation of the housing of a washing machine, during its operation, according to the quality of its installation and the substrate on which it is installed.

According to the present invention, the object of the present invention is solved by an active system of sensing the transmission of force to the substrate, which enables the simultaneous detection of the extraordinary and dynamic load in the drum and the identification of the dynamic properties of the washing machine. By controlling the speed of the washing machine drum, it is possible to actively adjust the washing cycle according to the loads in the drum and the dynamic properties of the washing machine. According to the present invention, at least one calibration is provided at the place of installation of the washing machine at the user, thus identifying the dynamic properties of the entire washing machine - substrate system.

Based on the mentioned measured dynamic properties of the whole system, the washing cycle is adjusted to the individual user in order to avoid the operation of the washing machine in the resonance range. In addition, based on the measurement of the force on the ground, the limit value of the permitted force transmission is defined, thus ensuring a lower level of vibration and consequently a calmer living environment.

In addition to automatically adjusting the washing cycle, the process according to the invention also offers the user an interactive insight into the quality of the installation of the washing machine on the substrate. With the proposed procedure it is possible to identify a possible incorrect position or. uneven loading of the support legs of the washing machine, which is reflected in the unstable position of the washing machine on the base.

The measurement of the force on the ground additionally enables the identification of the mass deviation or dynamic loads in the washing machine drum. Said load, which shows zero eccentricity, cannot be detected by measuring the torque on the electric motor, so according to the invention, indirect measurement of mass deviation load by means of simultaneous measurement of force transmission to the ground and indirect measurement of eccentricity by torque on the electric motor is provided. Increased force transfer to the ground indicates an extraordinary or. deviation load, and the data from the electric motor on the eccentricity enables the separation between these two loads.

The invention is further presented in more detail on the basis of a non-limiting embodiment and with reference to the accompanying drawings, in which FIG. 1 shows a washing machine with a sensor arrangement for measuring the transmission of force to the ground, FIG. 2 shows a characteristic curve giving the absolute amplitude of the force transfer to the ground, FIG. 3 shows a characteristic curve which is the basis for determining the quality of the substrate on which the washing machine is arranged, FIG. 4 shows a weighted characteristic curve, which is the basis for understanding the natural frequency and the corresponding normalized amplitude, FIG. 5 shows the weighted characteristic curve which is the basis for determining the critical operating ranges, FIG. 6a, 6b show an embodiment of the loading agent being inserted into a washing machine.

At least one sensor 1 for indirectly measuring the force from the washing machine 2 to the substrate is placed near at least one of the support legs 3 of the washing machine 2, where the deformations of the housing 4 of the washing machine are directly related to the amount of transmitted force to the substrate. The spatial arrangement of the sensor 1 is optional, preferably in the lower part of the housing, particularly preferably in the area of the bottom or near at least one of the support legs 3. Said sensor 1 is attached directly to the washing machine 2 either in a removable or non-removable manner. or material joints, for example by gluing, riveting, screwing and the like.

The arrangement of the sensor 1 on the housing 4 in the immediate vicinity of the support legs 3 allows, in addition to measuring the force, also indirectly determining the natural frequencies of the washing machine 2. The value of the maximum force at a given frequency of the washing machine drum 2 coincides with the natural frequency it is considered that the washing drum of said washing machine 2 is arranged in the washing tub in such a way that it can rotate about approximately horizontal axis

According to the present invention, it is envisaged that at least one calibration is performed on site at the respective user. Throughout the description, the word user refers to both the end user of the washing machine 2 and the advanced user, for example the service technician of the washing machine 2. This calibration determines the dynamic properties of the washing machine 2 including the substrate on which it is arranged. The calibration is based on measuring the deformations on the lower part of the housing 4 of the washing machine 2, measuring the deformations in the vicinity of at least one of the support legs 3. According to the invention, an embodiment is also possible in the immediate vicinity of all support legs 3 washing machine 2.

The deformation measurement is performed with at least one sensor 1, for example with a polymer measuring sheet, which directly generates a stress response during deformation. Compared to the resistance meter, neither the use of additional electronic power supply components nor the final amplification of the signal from said sensor 1 is required. The voltage signal from said at least one sensor 1 can be directly integrated into existing electronic components of the washing machine 2. All necessary calculations are performed with processing power of said existing electronic components.

The sensor 1 can also be mounted on the housing 4 of the washing machine 2 indirectly by means of an additional holder, so that the sensor 1 is arranged on an additional holder by an adhesive process, after which the sensor-additional holder assembly is provided by said force-coupling, form-joint or material-joint install the connections on the housing 4 of the washing machine 2.

The method according to the invention provides that the calibration for determining the natural frequencies of the washing machine 2 is performed when it is installed at the end user. Based on the calibration, the quality of the substrate on which the washing machine 2 is arranged is evaluated. Based on the algorithm, it is also possible to detect possible incorrect installation of support legs 3 of the washing machine 2. The mentioned algorithm refers to the washing machine is mainly in contact with the ground via only three support legs 3.

By means of calibration, critical operating areas are evaluated by means of said algorithm. During the operation of the washing machine 2, the washing mode is actively adjusted so as to avoid operation in critical areas. By means of the measurement of deformations and in connection with the measurement of the torque on the motor of the washing machine 2, dynamic loads in the drum of the washing machine 2 can be detected.

The calibration of the washing machine 2 is carried out in such a way that the transport guards 2a, which are intended to prevent damage to the washing machine 2 during transport, are first dismantled. After installation in the intended place, the washing machine 2 is connected to the water, drain and electrical connection.

[0020] When the user switches on the operation of the washing machine 2, the processor unit proposes to him to perform the calibration procedure of the appliance via the display unit. The display of said template appears due to the preset state of the display unit by the washing machine manufacturer 2. When the user confirms said proposal, the display unit shows a sign for inserting the intended load means 2b into the drum of the washing machine 2 (shown in Fig. 6b by a dashed line). The load means 2b must assume the intended position in relation to the inside of the drum when inserted into the drum or during the calibration program. This is achieved, for example, in such a way that the load means 2b comprises fastening points which coincide with the receiving means in the drum of the washing machine 2. Alternatively, the load means is of such a shape that when inserted into the drum or. during its rotation at a circumferential speed at which the centrifugal force at the center of gravity of the load means 2b is greater than its force of gravity, it assumes a precisely defined position inside the drum of the washing machine 2. From the point of view of economy, it is particularly advantageous if the load means 2b a component of transport fuses 2a.

Figure 6 shows an embodiment where the load means 2b is part of the transport guards 2a. After inserting the load means 2b into the drum, the user closes the door of the washing machine 2 and starts the calibration by pressing the start button. Of course, communication between the user and the washing machine 2 is also possible in some other known way, such as by voice communication.

The rotational speed of the drum of the washing machine 2 is automatically increased from the idle state with constant acceleration to the final revolutions during calibration by means of a calibration program which is part of said algorithm and where the course of the angular speed of the electric motor is entered as a function of time. During a gradual increase in the rotational speed of the drum, the signal from said at least one sensor 1 is read and the equivalent force is converted to the ground on which the washing machine 2 is arranged. it is merely programmatically upgraded by said algorithm, which is not the subject of the present invention. The result of the calibration is a characteristic curve 5, which gives the absolute amplitude of the force transfer to the ground (Fig. 2).

Based on said characteristic curve 5, the dedicated algorithm deciphers the eigenfrequencies 5 ', 5 ”of the washing machine 2. The eigenfrequency value 5', 5 is stored during the settings of the washing machine 2, where they remain as default values until the next calibration. The mentioned algorithm is switched on by the user himself, whereby the normal washing mode or the silent mode is available. Here, the user is reminded that the final spin speeds may be different from those set under the washing mode.

During the washing cycles, the t.i. silent calibration of the washing machine 2 when the deformations of the housing 4 of the washing machine 2 are measured and the natural frequencies 5 ', 5 are identified.

The values of the natural frequencies 5 ’, 5 depending on the washing cycles are recorded in the memory of the washing machine 2 and, depending on any changes in the values of the natural frequencies 5’, 5 ”, warn the user that the calibration process must be restarted. The reason for changing the natural frequencies 5 ', 5 "can be loose joints in the components of the washing machine 2, the movement of the washing machine 2, the possible unscrewing of the support legs 3 and the like. With the mentioned silent calibration, the condition of the washing machine 2 is monitored during its entire service life.

The result of the performed calibration process is the values of the natural frequencies 5 ', 5 of the washing machine 2 on a given basis. The algorithm for detecting the quality of the substrate gives for each type of washing machine 2 at least three reference values of natural frequencies 5 ', 5 ", which are determined by the manufacturer of the washing machine 2 under ideal conditions. These natural frequency reference values are as follows:

the natural frequency f _{max of the} washing machine 2 on an ideally rigid surface, the natural frequency f _{mln of the} washing machine 2 on a very soft surface, and the natural frequency f _{3 of the} washing machine 2 when in contact with the surface on which the washing machine 2 is arranged, only three support legs 3.

According to the reference values of said natural frequencies 5 ', 5 ”, it is possible to determine the quality of the substrate on which the washing machine 2 is arranged (Fig. 3). The natural frequency range between f _min and f _max is divided into a set of classes, preferably five. Depending on the range in which the measured natural frequency 5 ', 5 ”of the washing machine 2 is located, the quality of the substrate can be deduced. However, if the washing machine 2 is inadequately supported, this is only detected when the natural frequency 5 ', 5 ”of the washing machine 2 lies in the vicinity of said natural frequency f ₃ . In this case, the mentioned algorithm warns the user that the washing machine 2 is not installed correctly and that it is necessary to start the calibration process again.

Active adjustment of the washing cycle according to the quality of the substrate is aimed at quieter and quieter operation of the washing machine 2. The concept is based on the identified natural frequencies 5 ', 5 "within the calibration process. The user consciously decides to operate the washing machine 2 in calm and quiet mode by pressing the appropriate button. With the help of the instructions, the user is warned that due to the changed mode of operation of the washing machine 2, the rotational speed of the washing drum in the spinning phase may be slightly different from the selected rotational speed within the washing program.

Said algorithm for actively adjusting the washing mode comprises the following steps.

On the basis of the completed calibration of the washing machine 2, the weighting of the characteristic curve 5 is performed, preferably dividing the amplitudes by the square of the rotational frequency of the washing drum. From the weighted characteristic curve 6, the eigenfrequencies 5 ', 5 ”and the corresponding normalized amplitude are automatically deduced via the mentioned algorithm (Fig. 4).

Based on the weighted characteristic curve 6, the critical operating ranges 6 are determined as those rotational frequencies of the washing drum where the response amplitude reached Xmax of the maximum amplitude of one of the mentioned natural frequencies 5 ', 5 ”(Fig. 5). The frequency ranges suitable for operation are those frequency ranges where the amplitude is less than X _min .

Said steps are performed as part of the calibration of the washing machine 2, wherein the critical frequency bands and the frequency bands suitable for operation are stored in the memory of the washing machine 2 until the next calibration.

Only the washing cycle adjustment is performed at rotational speeds higher than 400 rpm. The adjustment of the washing cycle is preferably carried out in the centrifugation phase as follows:

the desired spin speed is determined, the maximum possible acceleration speed is determined in the critical frequency ranges in order to pass the critical areas quickly; in other frequency ranges, the acceleration speed is unchanged, in the range of the desired spin speed, the nearest frequency range suitable for operation is identified, after which the washing machine 2 performs spinning in this frequency range.

When stopping the washing machine 2, the washing drum is braked with the greatest possible deceleration.

The detection of dynamic loads is based on the instantaneous detection of deformations from said at least one sensor 1 in connection with the identification of the torque on the electric motor. Namely, the dynamic load is characterized by the fact that it results in zero eccentricity, due to which it cannot be detected by the torque on the electric motor. By measuring the deformations on the housing 4, it is possible to detect the increased level of vibrations that occur in the presence of such deviation and extraordinary loads. Furthermore, it is possible to determine with the help of the torque on the electric motor whether it is a normal extraordinary load or a deviation load. If the torque value does not change, it is obvious that the eccentricity value is small, indicating a deviation load.

Claims (8)

Patent claims A method of reducing vibrations of a washing machine housing and / or a base on which said washing machine is mounted during operation of said washing machine, which is loaded from the front, said washing machine comprising a housing with a front wall in which there is provided a filling opening, a movable door with which it is possible to close said filling opening, a washing tub arranged in said housing and comprising an opening facing the front wall of said housing, a washing drum for receiving laundry, the washing drum comprising an opening, which is at least approximately aligned with the opening of said tub and said filling opening in the front wall, a sensing means for directly or indirectly measuring vibrations, a memory unit, a processor unit, a control unit and a display unit, characterized in that it comprises: a) detecting the natural frequencies and the corresponding oscillation amplitudes of the washing machine with the base on which said washing machine is mounted, by means of said sensing means arranged in the lower part of the housing of the washing machine, b) storing information on said natural frequencies and the corresponding oscillation amplitudes and / or the corresponding directly or indirectly measured forces transmitted from the housing to the substrate in a storage unit, c) comparing in the processor unit the values of said amplitudes or said forces with the limit values stored in the memory unit, d) adaptation of at least one operating program and / or display of information for the user on the display unit on the condition of the washing machine and / or display of instructions to the user on the necessary corrective measures. Method according to claim 1, characterized in that said detection of the natural oscillation frequencies of the washing machine with the substrate comprises the steps of: a) installation of the load medium in the drum of the washing machine, b) implementation of a performance measurement program, c) measuring the vibrations of the housing during the execution of said measuring program with said sensing means at at least two different speeds of rotation of the drum, d) comparison of the measured values with the limit values stored in the storage unit. Method according to claim 1, characterized in that the display of indirect information of said measured values on the display unit contains the number of revolutions of the drum at which said values have occurred. Method according to claim 1, characterized in that said instruction from step d) comprises checking for the user the suitability of the arrangement of said washing machine. The method according to claim 1, characterized in that said change of at least one washing program comprises an increase in the speed of passage in accelerating and / or decreasing the speed of the washing machine drum through areas associated with said natural frequencies. Method according to claim 2, characterized in that said adaptation of the at least one washing program comprises omitting the speed of the washing machine drum in areas associated with said natural frequencies. 7. A washing machine for washing which is mounted in operation on a base to be loaded from the front, said washing machine comprising a housing with a front wall in which a filling opening is designed, a movable door with which said a filling opening, a washing tub arranged in said housing and comprising an opening facing the front wall of said housing, a washing drum for receiving laundry, the washing drum comprising an opening at least approximately aligned with the opening of said bath and said filling opening in front wall, sensing means for direct or indirect vibration measurement, memory unit, processor unit, control unit and display unit, characterized in that it comprises reducing the vibrations of the washing machine housing and / or the base on which said washing machine is mounted at operation of said washing machine according to a method according to any one of claims 1 to 6. Washing machine according to claim 7, characterized in that the load means to be installed in the drum of the washing machine according to claim 2 is part of transport guards.