Method for indirectly measuring influence on process air flow

Abstract

The invention relates to a method for determining an influence on a process air flow, in which a motor is controlled by a motor control device to drive a fan wheel and in particular to generate the process air flow in a process air channel, the motor power of the motor being determined on the basis of determined and / or measured motor parameters, wherein a volumetric flow rate of a process air flow through the process air channel is determined on the basis of the motor power, the determined volumetric flow rate being used to determine a pressure loss of the process air flow. The invention further relates to a method for determining the loading degree of a laundry tub and to a household appliance.

Description

Technical Field

[0001] The invention relates to a method for determining an influence on a process air flow, wherein an electric motor is controlled by a motor control device to drive a blower wheel and to generate a process air flow, for example in a process air duct. The invention also relates to a method for determining a charge level and to a household appliance. Background Art

[0002] The loading degree of a clothes dryer with damp laundry can vary significantly, which can have an impact on the drying program. A lower load or loading degree often results in a lower resistance to the process air flow than a larger load. If the speed of the fan is kept constant to generate the process air flow, a lower load results in a higher air flow due to the lower resistance to the air flow. A higher air flow is also accompanied by an increase in energy consumption. This mode of operation is a disadvantage of the clothes dryers used to date, in which the clothes drum and the fan are usually driven by a common motor. The speed of the fan cannot therefore be varied depending on the load.

[0003] However, even in clothes dryers with individually controllable motors for driving the fans, the load of the laundry drum must be determined in one step in order to subsequently adjust the speed of the fan. For example, it is known to measure the air flow by means of a differential pressure measurement before and after an orifice in a process air channel. There are also known methods which use an air flow meter to detect the pressure drop across the fabric in the laundry drum. However, such methods require retrofitting the clothes dryer with additional measuring devices and evaluation units.

[0004] US 8,474,152 B2 describes a method for determining the loading state of a clothes dryer using a time series of temperature values. As mentioned above, this method also requires the installation of temperature sensors and their complex long-term evaluation. In addition, the temperature measurement is prone to errors due to the dynamic conditions of the process air in the clothes dryer. Summary of the invention

[0005] The object of the present invention is therefore to specify a cost-effective method for indirectly determining the influence of the load of, for example, a laundry tub on the process air channel, as far as possible without making fundamental modifications to the system.

[0006] The object is achieved by a method for determining an influence on a process air flow having preferred features, a method for determining a filling level of a laundry tub having preferred features, and a domestic appliance having preferred features.

[0007] According to one aspect of the invention, a method for determining an influence on a process air flow is provided. An electric motor is controlled by a motor control device to drive a blower wheel and generate a process air flow, for example in a process air channel.

[0008] The process air stream can usually be generated in a domestic appliance which is provided according to a further aspect of the invention and is configured to carry out the method according to the invention.

[0009] The household appliance can be designed as an air-guiding household appliance, which can also be designed as a water-guiding household appliance. For example, the household appliance can be designed as a washing and drying machine, a clothes drying machine, a dishwasher, a washing machine with a process air flow guide, a steam boiler, an oven, an exhaust fan, etc.

[0010] The generated process air flow can be conveyed in a closed circuit (e.g. in a clothes dryer) or in an open circuit (e.g. in an exhaust fan) via a blower wheel. The process air channel can form part or all of such a circuit. The process air channel can include individual parts of the circuit, such as a clothes tub or a treatment chamber or a cleaning chamber, or at least couple these parts in a fluid-conducting manner.

[0011] The motor power of the motor is determined based on the determined and / or measured motor parameters. This can be done by a motor control, which can be designed, for example, as a so-called PWM, inverter, etc. The volume flow of the process air flow through the process air channel is determined based on the motor power. The determined volume flow is then used to determine the pressure loss of the process air.

[0012] This method makes it possible to indirectly measure the volume flow of process air, which is produced, for example, during the drying process of a clothes dryer or a washer-dryer. Here, the pressure loss due to the load of clothes or fabrics can also be determined. Depending on the design, this pressure loss can be used as an indicator of a disturbance in the process air flow. As the pressure loss increases, it can be assumed that the disturbance is getting stronger.

[0013] The disturbance may occur within the framework of normal operation of the household appliance or within the framework of abnormal operation of the household appliance. For example, a pressure loss caused by dirt or damage to the process air channel or the gas path can be classified as an abnormal operation of the household appliance. A pressure loss caused by the loading of fabrics in the laundry tub can be classified as a disturbance within the framework of normal operation of the household appliance.

[0014] Advantageously, the motor for driving the fan wheel can be designed as an axial fan wheel or a radial fan wheel and controlled by a separate motor control. The motor control can also be a component or module of the central control unit. For example, the motor can be a brushless DC motor. The motor control can thus predetermine or determine the number of revolutions or the speed of the motor. This can be done in the background within the framework of the operation of the domestic appliance.

[0015] Compared to other methods for measuring air flow or volume flow, the method according to the invention does not require additional sensors. The volume flow and pressure loss can be determined indirectly using only data or information from the motor control. The method allows particularly cost-effective measurement of volume flow and pressure loss.

[0016] According to one embodiment, the motor parameters of the motor are determined and / or measured in the form of motor voltage, motor current and motor speed. These measured data or predetermined values ​​can be determined and read out in a particularly simple technical manner within the framework of the motor control.

[0017] According to another embodiment, the volume flow is determined based on the motor parameters by means of formulas and / or look-up tables. This measure makes it possible to use previously created look-up tables or so-called look-up tables or corresponding derived formulas or approximation formulas that establish a relationship between motor parameters (e.g. motor power) and the volume flow of the generated process air flow. This makes it possible to determine the volume flow in a particularly simple technical manner.

[0018] According to another embodiment, the pressure loss is determined by a formula and / or a comparison table according to the determined volume flow and the previously determined motor speed. Here, one or more lookup tables or comparison tables in the form of approximate formulas can be used for technically simple determination of the pressure loss.

[0019] According to another embodiment, the speed of the motor can be determined. Alternatively, the speed of the motor is predetermined. At least one comparison table and / or at least one column or row of the comparison table and / or at least one formula is selected according to the speed to determine the volume flow and / or pressure loss. Due to physical relationships, the relationship between motor parameters and volume flow and pressure loss is obviously related to the speed of the motor or fan impeller. Therefore, a comparison table or formula can be determined for a predefined and constant speed and stored in a motor control device or other memory or external memory (such as a cloud) of a household appliance. Based on the controlled speed of the motor, a graphical curve, table or formula specific to this can be selected and then used to determine the volume flow and pressure loss particularly accurately.

[0020] According to another embodiment, the at least one comparison table, at least one column or row of the comparison table and / or at least one formula is created in advance within the framework of an initial series of measurements. Thus, one or more curves or tables can be initially created for a specific model or series of household appliances, which can then be used during operation to indirectly determine the volume flow and the pressure loss without the need for specific sensors.

[0021] According to another aspect of the present invention, a method for determining the loading amount of a laundry tub is provided. The motor is controlled by a motor control device to drive a blower wheel and generate a process air flow in a process air channel. The process air channel has a laundry tub or can be connected to the laundry tub in a fluid-conducting manner. The volume flow rate of the process air flow through the process air channel is measured or determined based on determined and / or predetermined motor parameters. The pressure loss of the process air flow when passing through the process air channel, in particular the laundry tub, is then determined directly or indirectly based on the determined volume flow rate. A curve or a value range is selected based on the volume flow rate and the pressure loss. Based on the selected curve or the selected value range, the loading degree of the laundry tub is determined.

[0022] In this case, a plurality of curves can be determined within the framework of a calibration or initial measurement, which establish a mathematical relationship between the degree of filling, the volume flow and the pressure loss. In particular, different graphical curves or regression lines can be provided, which are spaced apart from one another along the pressure axis due to different degrees of filling. Thus, the intersection point between the determined volume flow and the determined pressure loss can point to one of a plurality of graphical curves, which can all represent the degree of filling of the laundry tub.

[0023] The method makes it possible to determine the degree of charge of a clothes dryer or a washer-dryer in a technically particularly simple manner without requiring additional sensors or modifications.

[0024] In one embodiment, the degree of filling of the laundry drum is determined in the form of an unloaded laundry drum or in the form of a laundry drum loaded with fabric. This measure can be used to define a curve or a value range as a limit value between a loaded laundry drum and an unloaded or empty laundry drum. This measure allows a particularly simple and robust determination of the fabric content in the laundry drum.

[0025] According to another embodiment, the degree of filling of the laundry drum is determined as a percentage of the maximum possible laundry load or as the weight of the fabric in the laundry drum. Thus, a plurality of graphical curves can be recorded within the framework of the initial measurement. The number of determined curves or value ranges can represent the accuracy or degree of possible filling.

[0026] The advantages and features described above in conjunction with the device also apply to the method, and vice versa. The individual features or aspects of the present invention can be combined with each other and have the advantages described in this context. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention is explained in detail below with the aid of advantageous implementation methods with reference to the accompanying drawings. In the drawings:

[0028] Figure 1 A front view of a household appliance according to one embodiment is shown.

[0029] Figure 2 A schematic flow chart is shown for illustrating a method of determining an influence on a process air flow according to one embodiment.

[0030] Figure 3 Schematic pressure loss-volume flow diagram and motor power-volume flow diagram are shown for illustration purposes Figure 2 The steps of the method.

[0031] Figure 4 A schematic pressure loss / volume flow diagram is shown for determining the degree of charge of a domestic appliance.

[0032] In the figures, the same or corresponding elements are marked with the same reference numerals. Factors such as values, shapes, components, component positions, and the connection between components are only examples and are not restrictive. For the sake of clarity and to improve recognizability, different scales are sometimes used in the figures. DETAILED DESCRIPTION

[0033] Figure 1 A front view of a household appliance 100 according to one embodiment is shown. The illustrated embodiment shows the household appliance 100 in the form of a laundry dryer.

[0034] The household appliance 100 has a laundry tub 110. The laundry tub 110 is part of a closed circuit through which a process air flow can pass. In this case, the household appliance 100 has a first motor 120. The first motor 120 drives a fan wheel 121 and is controlled by a motor control device 122. To this end, the first motor 120 can be designed as a brushless DC motor. For example, the motor control device 122 can be designed as an inverter. In addition, the motor control device 122 can be configured to determine and / or predetermine motor parameters of the motor 120 or the first motor 120 so as to control the motor 120 according to the motor parameters. The motor parameters may include a rotational speed or frequency, a motor voltage, a motor current, a motor temperature, etc.

[0035] The shape of the blower wheel 121 may be a radial blower wheel, etc. The process air flow generated by the drive of the blower wheel 121 is indicated by arrows and may enter the laundry tub 110 through the process air passage 111 .

[0036] Another electric motor or drive motor 130 is provided for rotating the laundry tub 110 and thereby moving or circulating the fabrics 200 placed in the laundry tub 110 .

[0037] The generated process air flow can be dehumidified by cooling and then heated before passing through the laundry tub 110 so as to be able to more quickly absorb moisture from the fabrics 200. For the sake of clarity, corresponding heat exchangers or ambient heat exchangers, air channels, ducts, etc. are not shown in the figure.

[0038] Figure 2 A schematic flow chart is shown for illustrating a method 10 for determining an influence on a process air flow according to one embodiment. Here, steps 11-15 of the method can be used to determine an influence on a process air flow. In optional step 16, a method for determining a degree of loading of a laundry tub 110 according to one embodiment can be implemented.

[0039] exist Figure 3 A schematic pressure loss-volume flow diagram and a motor power-volume flow diagram are shown for illustration purposes. Figure 2 Steps 13, 14 and 15 of the method 10 are Figure 3 As shown in the diagram below, steps 14, 15, and 16 are Figure 4 This is shown visually in the diagram shown.

[0040] Exemplarily, the method 10 comprises: Figure 1 The illustrated household device 100 performs.

[0041] The figure schematically shows a pressure loss-volume flow diagram and a motor power-volume flow diagram, each of which has two curves for different rotational speeds N of motor 120 . The curves are shown here by way of example for two rotational speeds, wherein rotational speed N1 is greater than rotational speed N2 .

[0042] In a first step 11 of the method 10, a rotational speed set by the motor control 122 is read out. In the exemplary embodiment shown, a rotational speed N1 is used to explain the method 10.

[0043] In the next step 12, the relevant curve is selected for the set and read speed. The arrow indicates the selected curve or data set. The corresponding data set can also be in the form of a formula, regression and / or comparison table. They can be stored in the motor control device 122 or any control unit and / or storage unit inside or outside the device.

[0044] In a further step 13 of the method 10, motor parameters such as motor current and motor voltage are read out to determine the motor power P. In the exemplary embodiment shown, the motor power is determined to be 40 W. Based on the motor power-volume flow diagram, the volume flow of the process air flow generated by the blower wheel 121 is determined to be 160 m3 / h in step 14 of the method 10. Alternatively, a flow sensor can also be used to determine the volume flow in order to perform the measurement.

[0045] Based on the determined volume flow and the stored pressure loss / volume flow diagram, the pressure loss can be determined in a next step 15. In the exemplary embodiment shown, the determined pressure loss is 175 Pa. This pressure loss is caused by an obstruction of the process air flow in an open or closed circuit.

[0046] Figure 4 A pressure loss-volume flow diagram for determining the filling degree of a household appliance 100 is shown. The diagram is used to illustrate a method 20 for determining the filling degree of a laundry tub 110 according to one embodiment. Figure 1 The method 20 is illustrated with reference to the home device 100 shown in FIG.

[0047] To implement the method, a data set is used which has a plurality of curves or data sets of a pressure loss-volume flow diagram (see Figure 4 ). Here, the curves represent different loading levels of the laundry tub 110. In the illustrated embodiment, the loading level is expressed in the form of the weight of the wetted fabric 200. By way of example, pressure loss-volume flow-curves for three different loading levels are shown. As the loading level increases, the pressure loss also increases, so that as the volume flow increases, the distance between the curves along the Y-axis or pressure loss axis also increases.

[0048] In steps 11-13 of method 20, the motor 120 is controlled by the motor control device 122 to drive the fan wheel 121 and generate a process air flow in the process air channel 111. The volume flow of the process air flow through the process air channel 111 is measured or determined based on the determined and / or predetermined motor parameters 14. Here, the method for determining the volume flow is similar to Figure 2 The method 10 described in is similar. In the embodiment shown, the volume flow determined is 250 m3 / h.

[0049] Based on the determined volume flow, in a further step 15 the pressure loss of the process air flow through the process air channel 111 , in particular the laundry tub 110 , is determined directly or indirectly.

[0050] Based on the volume flow and the pressure loss, in a further step 16, an intersection point is displayed in the pressure loss-volume flow diagram, which intersection point is located on the average pressure loss-volume flow curve or falls within the value range of the pressure loss-volume flow curve for a filling degree of 8 kg. Therefore, the filling degree of the laundry tub 110 determined is 8 kg.

[0051] Reference numerals list

[0052] 100 Home appliances

[0053] 110 Clothes Bucket

[0054] 111 Process air channel

[0055] 120 Motor

[0056] 121 Fan wheel

[0057] 122 Motor control device

[0058] 130 Drive motor

[0059] 200 Fabric

[0060] 10 Methods for determining the impact on process air flow

[0061] 11 Reading the speed

[0062] 12 Select a curve or data set

[0063] 13 Read motor parameters

[0064] 14 Determining volume flow

[0065] 15 Determine the pressure loss

[0066] 20 Method for determining the degree of filling

[0067] 16 Select the value range and determine the filling degree.

Claims

1. A method (10) for determining an influence on a process air flow, wherein: The motor (120) is controlled by a motor control device (122) to drive a fan wheel (121) and, in particular, to generate a process air flow in a process air channel, wherein the motor power of the motor (120) is determined based on determined and / or measured motor parameters, wherein the volume flow of the process air flow through the process air channel (111) is determined based on the motor power, and wherein the determined volume flow is used to determine the pressure loss of the process air flow.

2. The method according to claim 1, wherein: The motor parameters of the motor (120) are determined and / or measured in the form of motor voltage, motor current and motor (120) rotation speed.

3. The method according to claim 1 or 2, wherein: The volume flow is determined based on the motor parameters by means of a formula and / or a look-up table.

4. The method according to any one of claims 1 to 3, wherein: The pressure loss is determined by means of a formula and / or a comparison table based on the determined volume flow and a previously determined rotational speed of the motor (120).

5. The method according to any one of claims 1 to 4, wherein: The rotational speed of the motor (120) is determined or predetermined, wherein at least one lookup table, at least one column or row of a lookup table and / or at least one formula is selected based on the rotational speed to determine the volume flow and / or the pressure loss.

6. The method according to claim 5, wherein: The at least one look-up table, at least one column or row of the look-up table and / or the at least one formula are created in advance within the framework of an initial series of measurements.

7. A method (20) for determining the degree of filling of a laundry tub (110), wherein: The motor (120) is controlled by a motor control device (122) to drive a blower wheel (121) and generate a process air flow in a process air channel (111), wherein the process air channel (111) has a laundry tub (110) or is connected to the laundry tub (110), wherein the volume flow of the process air flow through the process air channel (111) is measured or determined based on determined and / or predetermined motor parameters, wherein the pressure loss of the process air flow is directly or indirectly determined based on the determined volume flow, wherein a curve or a value range is selected based on the volume flow and the pressure loss, wherein the loading degree of the laundry tub (110) is determined by the curve or the value range.

8. The method according to claim 7, wherein: The loading degree of the laundry tub (110) is determined in the form of an unloaded laundry tub (110) or a laundry tub (110) loaded with fabrics (200).

9. The method according to claim 7 or 8, wherein: The loading degree of the laundry tub (110) is determined in the form of a percentage of the maximum possible loading of the fabrics (200) or in the form of the weight of the fabrics (200) in the laundry tub (110).

10. A domestic appliance (100) which is configured to carry out at least one method (10, 20) according to one of the preceding claims.

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