Method for determining a current operating point of a ventilator unit and ventilator system

Abstract

The invention relates to a method and to a ventilator system set up for carrying out the method. The method serves to determine a current operating point of a ventilator unit (11) having a ventilator (13) and at least one filter (12). By determining the current operating point, it is also possible, for example, to infer the degree of contamination of the filter (12). It is also possible to identify whether a filter (12) is present. At a plurality of time points, a power value for the electrical power of the ventilator (13) can be determined in each case. Depending on the current rotational speed of the ventilator (13), a power characteristic can be selected from a composite characteristic curve or calculated on the basis of a reference characteristic describing the relationship between the electrical power of the ventilator and the pressure difference of the ventilator unit (11). The power characteristic thus relates not only to the ventilator (13) but also to the entire ventilator unit (11). By this means, a single-valued and sufficiently precise determination of the current operating point A of the ventilator unit (11) is achieved.

Description

Technical Field

[0001] This invention relates to a method and apparatus for determining the current operating point of a ventilation fan unit. The ventilation fan unit includes a fan and at least one filter. The fan is configured to generate airflow through the at least one filter. This allows, for example, the determination of changes in flow resistance along a flow path arranged within the ventilation fan unit, and particularly the determination of the state of the at least one filter in the ventilation fan unit. Background Technology

[0002] The flow resistance of the airflow generated by the fan can be altered by changes in the flow path (which may occur upstream or downstream of the fan unit). For example, changes in flow resistance can be caused, for instance, by altering the flow cross-section of the airflow upstream or downstream of the fan when the inlet or outlet opening becomes larger or smaller. Changes in flow resistance can also be caused by the accumulation of particles over time at the at least one filter. The atmosphere in the environment may be loaded with particles. Over time, particles transported in the airflow may be captured by the filter. The filter's ability to achieve airflow at the desired volumetric flow rate decreases. Therefore, the filter must be cleaned or replaced from time to time.

[0003] EP 2620 202 B1 describes a method and apparatus for monitoring the condition of an air filter. In this method, the motor of a fan is controlled via a frequency converter. Torque and speed are measured by the operation of the frequency converter, and the frequency converter estimates the mechanical power of the fan based on this. A characteristic curve is determined for the fan, illustrating the relationship between mechanical power and flow rate. Based on the characteristic curve, mechanical power, and speed, the current operating point is then determined, thereby deriving the flow rate of the fan. From this, the current values ​​of operating parameters, such as dynamic flow resistance or a specific fan power, can be determined. By comparing these operating parameters with their original values ​​when the filter was uncontaminated, a measure of filter contamination can be derived.

[0004] US 2003 / 0052791 A1 proposes a method for monitoring the condition of a filter by means of a sensor that detects the volumetric flow rate of air passing through the filter. The disadvantage is that an additional volumetric flow rate sensor must be present at the filter.

[0005] US 8,672,733 B2 describes a method in which a ventilator is adjusted to take into account changes in airflow and, for example, to compensate for partial blockage of a filter.

[0006] A system and method for determining the condition of a filter are known from US 2003 / 0070544 A1. There, the rotational speed and motor current of a fan motor are evaluated to identify the filter's state of particle load. The motor current indicates whether the filter's condition remains acceptable.

[0007] Filter condition prediction based on models is known from US 2005 / 0247194 A1. To do this, the resistance of the filter to airflow is determined. Based on this resistance, detection statistics are measured to determine the current condition and remaining service life of the filter. For example, the detection statistics can be compared to a threshold, and if the threshold is exceeded, filter clogging can be inferred. The detection statistics take into account the time-varying nature of the measured resistance values ​​and can, for example, be the average of multiple individual resistance values.

[0008] DE 10 2015 012 462 B3 describes a method and apparatus for sensorless adjustment of a ventilator. Here, the use of pressure sensors and volumetric flow sensors is omitted. The motor operates at a preset operating point for the motor adjustment amount. The motor adjustment amount is detected to determine if there is a deviation from the theoretical value. If so, the system operates at another operating point. The operating point is iteratively changed until the deviation between the theoretical and actual values ​​for the motor adjustment amount is sufficiently small.

[0009] US 8,346,507 B2 assesses the time-varying power in ventilation systems. Based on the power slope, conditions can be differentiated: whether valves in the flow path are closed, whether cooling coils in the cooling system are frozen, or whether filters are clogged. Different power slope values ​​over time allow for the differentiation and identification of different states. Summary of the Invention

[0010] Based on the known prior art, the object of the present invention can be considered as creating a simple and accurate method for determining the state of filters in a ventilation unit, and providing a ventilation system designed for this purpose.

[0011] This objective is achieved by a method according to one aspect of the invention and a ventilation system according to one aspect of the invention.

[0012] This invention provides a method and a ventilation system for performing the method. The method is configured to measure changes in flow resistance in a flow path through which a ventilation unit is arranged. The ventilation unit has a fan and at least one filter. The fan is particularly a radially curved fan. In one embodiment, the at least one filter is arranged upstream of the fan in an inflow channel. The housing of the ventilation unit may restrict the inflow channel and an outflow channel arranged downstream of the fan.

[0013] The ventilation unit also includes a ventilation control device configured to control or regulate the electric motor of the ventilation fan. The ventilation control device may optionally be communicatively connected to at least one sensor to detect the current operating status of the ventilation fan, such as its actual rotational speed. The actual rotational speed of the ventilation fan may be the rotational speed of the fan impeller and / or the rotational speed of the rotor of the electric motor. Preferably, the fan impeller is anti-rotationally connected to the rotor of the electric motor such that the rotational speed of the electric motor rotor is synchronized with the rotational speed of the fan impeller.

[0014] An airflow is generated within the flow chamber and passes through at least one filter in the fan unit using a fan. The fan unit's fan is particularly a rearward-curved radial fan. In this type of fan, the fan wheel has fan blades that are curved rearward with respect to the direction of rotation. Each fan blade has an inner edge and an outer edge, wherein the inner edge is arranged closer to the axis of rotation in the radial direction relative to the axis of rotation than the outer edge. With respect to the direction of rotation, the outer edge is arranged after the inner edge of the fan blade.

[0015] The fan unit has a power characteristic curve for each rotational speed of the fan, which describes the relationship between the electrical power of the fan and the flow parameters of the fan unit, particularly the pressure difference between the inlet and outlet pressures of the fan unit. The inlet pressure is measured upstream of the fan unit in the inflow channel, and the outlet pressure is measured downstream of the fan unit in the outflow channel. The volumetric flow rate or mass flow rate of the airflow through the fan unit can also be used as a flow parameter. The power characteristic curve is determined and stored, in particular, through measurement and / or simulation of the fan unit (which has a fan and at least one filter), for example, in the memory of the fan control device or in an external computing unit communicatively connected to the fan control device. Power characteristic curves can be measured and stored separately for different rotational speeds. Therefore, a composite characteristic curve can be obtained from multiple stored power characteristic curves.

[0016] An airflow is generated along a flow path and passes through the at least one filter using a fan. The fan's operating speed is known and can be controlled or adjusted. The theoretical speed can be preset by the fan control unit and / or an external computing unit. The actual speed of the fan can be detected by a speed sensor and provided to the fan control unit and / or the external computing unit. Alternatively, the theoretical speed can be used instead of the actual speed, assuming that the actual speed is at least substantially consistent with the theoretical speed.

[0017] The electrical power of the fan is the electrical power received by the fan's electric motor. Specifically, the motor current and motor voltage are measured for this purpose, and the electrical power is calculated from them. The motor current and / or motor voltage can be measured. The motor voltage can be set to a constant value, thus eliminating the need for measurement.

[0018] The stored power characteristic curve can be selected based on either the actual or theoretical rotational speed. Here, a power characteristic curve is selected where the difference between the current actual or theoretical rotational speed and the speed associated with the stored power characteristic curve is minimized. Alternatively, the power characteristic curve can also be calculated based on a reference characteristic curve using the similarity law.

[0019] At least one power characteristic curve of the fan unit has a range of multiple power values. Within this range, one power value is associated with two possible flow parameter values. Therefore, within this range, the operating point of the fan unit cannot be identified based on a single current power value. Outside this range, the power characteristic curve may have a range in which each current power value is associated with exactly one flow parameter value.

[0020] To determine the current operating point, at least the current power value of the electrical power for the fan must be measured, and the current flow parameter value (e.g., differential pressure value) can be measured at least within the range of single power values ​​of the selected power characteristic line.

[0021] According to the invention, in addition to the current power value representing the second power value at a second time point, at least one power value at a previous time point can also be measured and considered, said at least one power value representing the first power value at a first time point. This is at least necessary if the second power value falls within a range of multiple power values ​​and the current operating point needs to be determined. The current operating point can thus also be determined single-valued within a range of multiple power values. For example, it can be assumed that the operating point of the fan unit changes with the increase of the operating duration due to variations in said at least one filter, and that said at least one filter becomes increasingly contaminated during the operating duration. Flow parameter values ​​may increase or decrease only due to this increased contamination, depending on which physical quantity is used as the flow parameter. For example, the pressure difference between the inlet and outlet pressures of the fan unit may only increase with increased contamination, and the volumetric flow rate or mass flow rate through the fan unit may only decrease. Therefore, two power values ​​measured using a time interval are sufficient to determine the current operating point single-valued.

[0022] Alternatively, three or more power values ​​can be measured sequentially over time, allowing the current operating point to be determined based on two or more previous power values.

[0023] The operating point and the resulting flow parameter values ​​(e.g., the pressure difference between the resulting inlet and outlet pressures) also characterize the flow resistance along the flow path and through the fan unit. Therefore, the filter condition can be inferred from the current operating point, and appropriate measures can be implemented. For example, information indicating whether the filter must be cleaned or replaced can be generated and output. Here, the filter condition can be described qualitatively and / or quantitatively. For example, the filter condition can be divided into multiple levels, and the levels of filter condition can be output. For example, one level of filter condition may correspond to a good filter condition, while another level requires immediate filter replacement. A level or condition can also describe a non-existent or installed filter.

[0024] With the aid of this invention, a very precise determination of the current operating point can be achieved. The power characteristic curve of the fan unit differs from that of the fan itself. Especially in radially curved fans, the fan characteristic curve is very flat within the maximum value range of the flow parameters, meaning that within this range, the electrical power cannot be correlated with the flow parameter values ​​with sufficient reliability or accuracy. In contrast, the power characteristic curve of the fan unit is less wide within the maximum value range, and the correlation between the electrical power and flow parameter values ​​can be sufficiently accurate within this range.

[0025] The determination of the mechanical power of the fan is eliminated. For example, by measuring or otherwise determining the motor current and / or motor voltage, the electrical power (the electrical power received by the electric motor) for the fan can be determined very accurately and very simply. From the power value, based on the selected power characteristic curve, the flow parameter values ​​(differential pressure, volumetric flow rate, etc.) of the fan unit and therefore the current operating point can be directly determined. If a comprehensive characteristic curve consisting of multiple power characteristic curves for different fan speeds is stored, it is unnecessary to use similarity laws to convert the reference characteristic curve to the power characteristic curve for the current speed. This reduces computational costs and improves the accuracy of determining the current operating point.

[0026] Advantageously, the fan speed can be adjusted so that the speed is known with high accuracy, and the relevant power characteristic curve can be calculated selectively or alternatively.

[0027] This invention can be used, for example, to determine the condition of the at least one filter, for instance, by comparing the current operating point with a previous operating point, and thereby inferring increased contamination of the filter. This is especially possible if filter contamination is a significant factor contributing to increased flow resistance to airflow through the fan unit. This can be assumed in many cases.

[0028] Advantageously, the determination of the current operating point of the fan unit is always performed based on a first power value, a second power value, and a selected or measured power characteristic curve, regardless of whether the second power value falls within or outside the range of multiple power values. In this embodiment of the method, no case distinction is required.

[0029] Alternatively, different scenarios can be considered. If the second power value is outside the range of multiple power values, the current operating point of the fan can be determined independently of the first power value. The operating point is then generated by the current second power value and the power characteristic curve.

[0030] The power characteristic curve of the fan unit has a maximum value within a range of multiple power values, and therefore has segments with positive slopes and segments with negative slopes. If pressure difference is used as the flow parameter, the power of the fan unit increases with increasing pressure difference in the segments with positive slopes, and decreases with increasing pressure difference in the segments with negative slopes.

[0031] The flow parameter values ​​of the fan unit may alternatively or additionally depend on other parameters affecting the flow resistance of the airflow, such as the opening and / or closing of valves in the flow path or the gas flow path. Such changes in flow parameters occur significantly faster in time and can therefore be distinguished from slower changes in flow parameters due to increased filter clogging, for example, by taking into account the time gradient of the flow parameters.

[0032] Furthermore, it is advantageous to take the fan speed into account when determining the current operating point. In particular, the power characteristic curve to be used when determining the operating point can depend on the speed and can be calculated based on the speed or selected from the characteristic field.

[0033] For example, the power characteristic line to be used can be calculated based on the rotational speed and a known, preset reference characteristic line. For example, the reference characteristic line can be empirically adopted within the framework of the fan's development or commissioning. Then, the current power characteristic line can be determined based on the following equation (the law of similarity):

[0034]

[0035] Advantageously, the fan in the ventilation unit is speed-controlled or speed-regulated. In particular, a constant theoretical speed can be preset as the regulation value. Therefore, the fan speed is stationary or at least quasi-stationary during operation.

[0036] Furthermore, it is advantageous that the fan unit communicates with an external computing unit. The determination of the current operating point and / or the status of the filter, and / or the preset of other, new operating points, can be performed via the external computing unit. The external computing unit can be located remotely from the fan unit and communicates with it, for example, via an internet connection. The external computing unit can be a cloud computing unit. The external computing unit can communicate with multiple fan units.

[0037] The ventilation system according to the invention may have at least one ventilation unit and an external computing unit. If multiple ventilation units exist, they can be connected to a common modem or other communication interface via a communication network. The communication network may be a bus system. The bus system may have any known architecture or conform to any known standard, such as fieldbus standards like PROFIBUS or MODBUS.

[0038] A modem or communication interface may be provided for communicating with an external computing unit, wherein the communication connection between the modem and the external computing unit may be achieved, for example, via a LAN connection, a WLAN connection, an Ethernet connection, a GSM connection, any combination thereof, or any other Internet connection. Attached Figure Description

[0039] Advantageous designs of the present invention are derived from the specification and accompanying drawings. The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Wherein:

[0040] Figure 1 A schematic, block-like illustration of an embodiment of a ventilation fan system is shown.

[0041] Figure 2 It shows Figure 1 A schematic, block-like illustration of an embodiment of a ventilation fan unit in a ventilation fan system.

[0042] Figure 3 A schematic diagram of the comprehensive characteristic curve is shown, which has the following characteristics based on... Figure 2 Multiple power characteristic lines of the fan unit and fan characteristic lines used for comparison,

[0043] Figure 4 and Figure 5 Schematic diagrams of power characteristic lines are shown to illustrate the method for determining the current operating point based on the power characteristic lines. Detailed Implementation

[0044] Figure 1 A block diagram of an embodiment of a ventilation system 10 is shown. The ventilation system 10 has at least one ventilation unit 11. The ventilation unit 11 has at least one filter 12 and a ventilation fan 13. The ventilation fan 13 is configured to generate airflow through the at least one filter 12. The at least one filter 12 may be arranged upstream or downstream of the ventilation fan 13.

[0045] The fan 13 is, for example, a rearwardly curved radial fan 14. The radial fan 14 has a fan wheel 15, which is rotatably supported about a rotation axis D. A plurality of fan blades 16 are arranged circumferentially around the rotation axis D at the fan wheel 15. Each fan blade 16 is spaced relative to the rotation axis D and has an inner edge radially inward and an outer edge radially outward. In the rotational direction about the rotation axis D, the outer edge is positioned behind the inner edge of the fan blade 16. Therefore, each fan blade 16 is curved rearward from the inner edge to the outer edge in the rotational direction. Figure 2 An embodiment of a backward-curved radial fan 14 is illustrated in a highly schematic manner.

[0046] Figure 2An embodiment for a fan unit 11 is shown. In this embodiment, the fan unit 11 has a housing 17 that defines an inflow channel 18 and an outflow channel 19. The inflow channel 18 is located upstream of the fan 13 and, by example, upstream of a radial fan 14, and is oriented substantially parallel to the axis of rotation D of the fan 13. In the radial fan 14 shown here, the outflow channel 19 is oriented radially to the axis of rotation D. By example, a single filter 12 is arranged in the inflow channel 18. In a variation of the illustrated embodiment, multiple filters 12 may also be arranged in the inflow channel 18 and / or the outflow channel 19.

[0047] An inlet pressure pe exists at the inlet of the ventilation unit 11, and an outlet pressure pa exists at the outlet of the ventilation unit 11. Between the locations where the inlet pressure pe and the outlet pressure pa exist, the at least one filter 12 and the ventilation fan 13 of the ventilation unit 11 are arranged in the flow path.

[0048] To drive the fan wheel 15 to rotate around the axis of rotation D, the fan 13 has an electric motor 20. The electric motor 20 is preferably a brushless DC motor, which can also be referred to as a permanent magnet regulated electronically commutated DC motor. Brushless DC motors have minimal wear and excellent speed regulation. Furthermore, higher energy efficiency can be achieved using brushless DC motors.

[0049] The ventilation system 10 includes a ventilation control device 25 for controlling or regulating the ventilation fan 13 and, consequently, the electric motor 20. Specifically, the ventilation control device is configured to control or regulate the rotational speed of the rotor of the electric motor 20. In an embodiment, the ventilation fan wheel 15 is anti-rotationally connected to the rotor of the electric motor 20 such that the rotational speed of the rotor of the electric motor 20 is the same as the rotational speed of the ventilation fan wheel 15, which can also be collectively referred to as the rotational speed of the ventilation fan 13.

[0050] In the embodiment illustrated here, the rotational speed of the fan 13 is preferably adjusted. The rotational speed of the rotor of the electric motor 20 and / or the fan wheel 15 is detected by means of a speed sensor 26 and provided to the fan control device 25. For this purpose, the speed sensor 26 is communicatively connected to the fan control device 25. In addition to the speed sensor 26, at least one other sensor may be present to detect at least one other operating parameter of the electric motor 20. For example, a current sensor for measuring motor current and / or a voltage sensor for measuring motor voltage may be present.

[0051] If the fan 13 is speed-regulated by the fan control 25, the speed sensor 26 can optionally be omitted, and it can be assumed that the actual speed of the fan 13 is sufficiently consistent with the preset theoretical speed. Instead of the detected actual speed, the theoretical speed can be used to determine the current operating point A of the fan unit 11. The method for determining the current operating point A of the fan unit 11 will be explained in more detail below.

[0052] The fan control device 25 also has a memory 27. Information for transmission or access can be stored in the memory 27. Such information or data in the memory 27 may include current operating parameters, such as actual rotational speed, or may store immutable data, such as one or more power characteristic lines of the fan unit 11.

[0053] The fan control device 25 has an interface 28 through which the fan unit 11 can be connected to a communication network 29. The communication network 29 is preferably a bus system, such as a fieldbus system, which may correspond to known standards such as MODBUS or PROFIBUS. The communication network 20 can be wired and / or wireless.

[0054] Multiple individual ventilation units 11 can be connected to the communication network 29. Each ventilation unit 11 is communicatively connected to a communication module 30 (e.g., modem 31) via the communication network 29. The communication module 30 forms an interface between the communication network 29 on one hand and a network connection 32 having an external computing unit 33 on the other. The network connection can be established, for example, as a LAN connection, a WLAN connection, a GSM connection, or any other known method. The external computing unit 33 can be a component of a cloud system and thus forms a cloud computing unit.

[0055] The ventilation system 10 is configured to determine the current operating point A of one, more, or all ventilation units 11 based on the method according to the invention. The determination of the current operating point A of the ventilation unit 11, or the determination of the state of the filter 12 of that ventilation unit 11, is performed, as an example, by an external computing unit 33. The computational power required for this can be provided by the external computing unit 33. The data and information required to determine the current operating point A can be distributed in the memory 27 and / or centrally located in the external computing unit 33. Therefore, the external computing unit 33 can centrally manage and / or control the ventilation system 10. For example, by means of the external computing unit 33, presets for controlling or adjusting each ventilation unit 11 of the ventilation system 10 can be transmitted to the corresponding ventilation control device 25, such as theoretical values ​​to be set, for example, the theoretical rotational speed of the fan 13 of the ventilation unit 11.

[0056] The external computing unit 33 can also be connected to multiple communication modules 30 via network connection 32, and the communication modules are in turn connected to at least one ventilation unit 11 via communication network 29. In other words, the external computing unit 33 can also be a component of multiple separate ventilation systems 10.

[0057] During operation of the fan unit 11, particles contained in the air are filtered out of the airflow by at least one filter 12. Therefore, as the operating duration of the fan unit 11 increases, the filter 12 experiences an increased particle load, and its ability to achieve a preset air volumetric flow rate or air mass flow rate through the fan unit 11 decreases. Based on the determination of the current operating point A of the fan unit 11, the condition of the filter 12 can also be determined, for example, providing information about whether or when the filter 12 must be cleaned or replaced.

[0058] Figure 3 The diagram illustrates the concept of having according to Figure 1 and Figure 2 An embodiment of the combined characteristic curve of multiple power characteristic lines K1, K2, K3 of the ventilation fan unit 11 is shown. Three power characteristic lines K1, K2, K3 are illustrated, each of which is associated with a rotational speed n1, n2, n3 of the ventilation fan 13. That is, each power characteristic line K1, K2, K3 is valid at the relevant rotational speed of the ventilation fan 13 and describes the relationship between the electrical power P of the ventilation fan 13 and the flow parameters of the entire ventilation fan unit 11 at that rotational speed n1, n2, n3.

[0059] As flow parameters, for example, pressure difference dp can be used, or alternatively, other flow parameters characterizing the flow resistance along the flow path, such as the volumetric flow rate or mass flow rate through the fan unit. As an example, each power characteristic line K1, K2, K3 describes the relationship between the electrical power P of the fan 13 and the pressure difference dp at preset rotational speeds n1, n2, n3 of the fan 13. The pressure difference dp corresponds to the difference between the inlet pressure pe and the outlet pressure pa of the fan unit 11. Therefore, the pressure difference dp depends on the operating state of the fan 13 on the one hand, and on the other hand, on the state of the filter 12 and, in particular, its load of particles to be filtered from the air. The greater the load or contamination of the filter 12, the greater the pressure difference dp.

[0060] For this method, a comprehensive characteristic curve composed of multiple power characteristic lines Kl, K2, K3 at different rotational speeds nl, n2, n3 of the fan wheel 16 or the fan 13 can be stored in the external computing unit 33 or the memory 27. A reference characteristic line R can also be measured and stored for each type of fan 13 under a preset reference rotational speed. For example, the reference characteristic line R and / or the comprehensive characteristic curve composed of multiple power characteristic lines Kl, K2, K3 can be determined empirically and / or through simulation, especially within the framework of commissioning the fan unit 11 in a laboratory, at the manufacturer's location, or at the installation site.

[0061] If the fan 13 operates at a speed different from the reference speed associated with the reference characteristic line R, or at a speed not associated with the stored characteristic lines K1, K2, K3 of the comprehensive characteristic curve, the power characteristic line K required for the current speed can be determined based on the following equation (similarity law):

[0062]

[0063] Therefore, for each actual rotational speed of the fan 13, either a sufficiently accurate power characteristic line Kl, K2, K3 can be selected from the stored comprehensive characteristic curves, or the current power characteristic line can be calculated based on equations (1) and (2).

[0064] like Figure 4 As shown, each power characteristic line K has a multi-value power value range I and, for example, a single-value power value range II. Within the multi-value power value range I, each power value of the electrical power P of the fan 13 or the electric motor 20 is associated with two pressure difference values. Therefore, when the current power value of the received electrical power P for the fan 13 is measured, if the currently measured power value is within the multi-value power value range I, the operating point A of the fan unit 11 cannot be determined based on that power value. However, if the currently measured power value is within the single-value power value range II, the operating point A of the fan unit 11 has already been determined from the currently measured power value and the power characteristic line K of the fan unit 11.

[0065] In order to determine the operating point A as a single value even for power values ​​that fall within the multi-value range I, the following steps are taken:

[0066] At a first time point, a first power value P1 is measured of the electrical power received by the fan 13. For this purpose, the motor current and / or motor voltage and / or related parameters of the electric motor 15 can be measured or calculated, for example. At a second time point with a sufficient time interval from the first time point, a second power value P2 is measured. The second power value P2 can be the current power value for which the operating point A of the fan unit 11 should be determined. The first power value P1 corresponds to the power of the fan 13 at an earlier time point, for example, at a time point that just occurred in a previous measurement. Preferably, the power value is measured according to time or according to an event, for example, within a preset time interval. The last measured power value can be the second power value P2, and preferably the power value determined in a previous measurement can be the first power value P1. Unlike the embodiment described herein, more than two power values ​​can also be measured sequentially in time, wherein the last measured power value defines the current power value, which characterizes the current operating point of the fan unit 11.

[0067] According to Figures 3 to 5 It can be seen that the power characteristic line K has a maximum value, which separates the segment with a positive slope S from the segment with a negative slope F. Figure 4 In the section with a positive slope S, the power P increases with increasing pressure difference dp. In the section with a negative slope F, the power P decreases with increasing pressure difference dp.

[0068] Suppose that a second power value P2 is measured at the second time point within a range of multiple power values. For example... Figure 4 As shown, at the current speed of the fan 13, the power characteristic line K associates the second power value P2 with the lower pressure difference dp21 and the upper pressure difference dp22. Therefore, based solely on the measurement of the current power value, the operating point A of the fan unit 11 cannot be determined under the current condition based solely on the measurement of the second power value P2.

[0069] Therefore, the first power value P1 previously measured at the first time point is additionally considered. For example... Figure 5 As illustrated in the diagram, the power characteristic line K associates the first power value P1 with the lower pressure difference dp11 and the upper pressure difference dp12.

[0070] In the ventilation fan unit 11 Figure 2In the schematic embodiment, it can be assumed that the flow resistance in the flow path, i.e., the flow resistance in the inflow and outflow channels of the fan unit 11, is affected only or substantially by the accumulation of particles in the filter 12, which in turn characterizes the flow parameters and, according to the example, the pressure difference dp during the operation of the fan unit 11. Therefore, it can be assumed that the pressure difference dp increases and does not decrease as the contamination of the filter 12 gradually increases over time. This understanding is sufficient to determine the current operating point A using two power values ​​P1, P2 based on the selected power characteristic line K. More than two power values ​​can also be determined sequentially over time to identify the current operating point A.

[0071] Therefore, under the current circumstances, it can be assumed that the pressure difference associated with the second power value P2 of the electrical power at the current operating point A is greater than the pressure difference dp associated with the first power value P1. Figure 4 and Figure 5 In the example shown, the current operating point A is therefore located in segment F with a negative slope. Therefore, based on the power characteristic line K for the first power value P1 and the second power value P2, it can be determined that the current operating point A corresponds to the value pair of the second power value P2 and the upper pressure difference dp22 for the second power value P2. Operating point A is... Figure 5 The diagram is composed of triangles.

[0072] If at the second time point, the current second power value P2 should be within the power value range II of a single value, then the second power value P2 and the power characteristic line K are sufficient to determine the current operating point A.

[0073] Therefore, based on the measurement at the current operating point A, the current pressure difference can be determined, and this pressure difference is... Figure 5 The example shown corresponds to the upper pressure difference dp22 for the second power value P2. The pressure difference dp depends on the particle load on filter 12, from which the state of filter 12 can be inferred.

[0074] Based on this, the state of filter 12 can be determined quantitatively and / or qualitatively, and corresponding information can be output for the operator. For example, state levels can be formed, wherein the number of state levels can vary. The filter state can be characterized as "good," "critical but acceptable," and "clogged," for example, in three levels. From this, treatment recommendations, such as cleaning or replacing the filter, can be derived.

[0075] If there are other devices affecting flow resistance in the fan unit or in the airflow path, their current position can also be determined using the methods described above. For example, if a valve or throttling device in the flow path is opened or closed, the pressure difference dp changes very rapidly. Such changes can be measured if the power value of the electrical power P is measured frequently enough. Based on the time-varying difference in pressure, i.e., based on the pressure gradient, the expansion or contraction of the flow cross-section of the airflow path due to the manipulation of structural elements present there can be distinguished from the relatively slow, continuous increase in pressure difference due to increased clogging of the filter. Changes in the flow cross-section due to the manipulation of valves, throttling devices, etc., can also be determined and displayed when necessary.

[0076] Furthermore, it can be identified, based on at least one stored power characteristic line, when the fan unit 11 unintentionally does not include a filter insert in the support of the filter 12 or when the filter 12 is completely omitted. Then, the current values ​​for the electrical power and flow parameters are outside at least one stored power characteristic line.

[0077] In this invention, at least one power characteristic line of the ventilation unit 11, consisting of the fan 13 and the at least one filter 12, or a composite characteristic curve consisting of multiple power characteristic lines K1, K2, K3, is stored in the memory 27 or the external computing unit 33. For example, the at least one power characteristic line K1, K2, K3 can be determined by measurement and / or simulation at the manufacturer's end in a testing laboratory or during field installation, and is associated with the ventilation unit 11. Ventilation units 11 with the same construction have the same power characteristic lines.

[0078] Compared to using the fan characteristic line KV of fan 13, the detection and use of the power characteristic line K(K1,K2,K3,...) of fan unit 11 when determining the current operating point A has the following advantages: the correlation between the measured power value P and the flow parameter value within the range of the maximum value of the characteristic line is sufficiently accurate or reliable, especially for radial fans 14 with backward curvature. For comparison, Figure 3 The fan characteristic line KV of the backward-curved radial fan 14 is shown as a dashed line at the first rotational speed n1. It can be seen that, compared to the first power characteristic line K1, the fan characteristic line KV has a flat range within the maximum value range, and this flat range extends over a larger differential pressure range compared to the power characteristic line K1 of the fan unit 11. When using the fan characteristic line KV, there is insufficient reliability in providing a correlation between power values ​​and differential pressure. It is precisely when using the backward-curved radial fan 14 that using the power characteristic line K for the entire fan unit 11 represents a significant advantage.

[0079] This invention relates to a method and a ventilation system for performing the method. The method is used to determine the current operating point of a ventilation unit 11 having a fan 13 and at least one filter 12. By determining the current operating point A, for example, the degree of contamination of the filter 12 can also be inferred. The presence of the filter 12 can also be identified. At one or more time points, the power value of the electrical power for the fan 13 can be measured separately. Based on the current rotational speed of the fan 13, the power characteristic line K can be selected from a composite characteristic curve or calculated based on a reference characteristic line R describing the relationship between the electrical power of the fan 13 and the flow parameters of the ventilation unit 11. Therefore, the power characteristic line K relates not only to the fan 13 but also to the entire ventilation unit 11. Thus, a single-valued and sufficiently accurate determination of the current operating point A of the ventilation unit 11 is achieved.

[0080] List of reference numerals

[0081] 10. Ventilation fan system

[0082] 11 Ventilation Fan Unit

[0083] 12 Filters

[0084] 13 Ventilation Fan

[0085] 14. Backward-curved radial fan

[0086] 15 Ventilation fan wheels

[0087] 16. Fan blades

[0088] 17. Casing

[0089] 18 Inflow Channel

[0090] 19 Outflow Channel

[0091] 20 Electric Motors

[0092] 25. Ventilation fan control device

[0093] 26 Speed ​​sensor

[0094] 27. Memory

[0095] 28 Interfaces

[0096] 29. Communication Networks

[0097] 30 Communication Module

[0098] 31 Modem

[0099] 32 Network Connection

[0100] 33 External Computing Unit

[0101] I. Multi-value power range

[0102] II. Range of power values ​​for a single value

[0103] Work Point A

[0104] D Rotation axis

[0105] dp pressure difference

[0106] dp11 Lower pressure difference value of the first power value

[0107] dp12 The upper pressure difference value of the first power value

[0108] dp21 Regarding the lower pressure difference of the second power value

[0109] dp22 The upper pressure difference value of the second power value

[0110] F is a segment with a negative slope.

[0111] K power characteristic line

[0112] K1 First Power Characteristic Line

[0113] K2 Second Power Characteristic Line

[0114] K3 Third Power Characteristic Line

[0115] KV Fan Characteristic Line

[0116] n rotational speed

[0117] n1 First rotational speed

[0118] n2 Second rotation speed

[0119] n3 Third speed

[0120] P power

[0121] P1 First power value

[0122] P2 Second Power Value

[0123] Pa output pressure

[0124] PE input pressure

[0125] R Reference Characteristic Line

[0126] S is a segment with a positive slope.

Claims

1. A method for determining the current operating point (A) of a fan unit (11), the fan unit having at least one filter (12) and a fan (13), wherein, The method comprises the following steps: - An airflow through the at least one filter (12) is generated by means of the ventilator (13). - Determine the power values ​​(P1, P2) of the electrical power (P) of the ventilator (13) at at least two time points, namely, the first power value (P1) at the first time point and the second power value (P2) at the second time point. - Measure or select the power characteristic line (K) of the fan unit (11), wherein the power characteristic line (K) characterizes the relationship between the electrical power (P) of the fan (13) and the flow parameters of the fan unit (11), wherein the power characteristic line (K) has a range of multiple power values ​​(I), wherein one power value is associated with two possible flow parameter values. - At least when the second power value (P2) is within the range (I) of multiple power values, the current operating point (A) of the fan unit (11) is determined based on the first power value (P1), the second power value (P2) and the power characteristic line (K), wherein the flow parameter is the pressure difference (dp) between the inlet pressure (pe) and the outlet pressure (pa) of the fan unit (11), wherein the pressure difference (dp) increases and does not decrease as the contamination of the filter (12) increases over time, wherein the second power value (P2) defines the current power value, which characterizes the current operating point (A) of the fan unit (11), and wherein the first power value (P1) is the power value determined in a previous measurement that just occurred.

2. The method according to claim 1, wherein, The flow parameter is the volumetric flow rate or mass flow rate of the fan unit (11).

3. The method according to claim 1 or 2, wherein, The determination of the current operating point (A) of the fan unit (11) is always performed based on the first power value (P1) of the electric power (P) of the fan (13), the second power value (P2) of the electric power (P) of the fan (13) and the power characteristic line (K) of the fan unit (11), regardless of whether the second power value (P2) is within or outside the multi-value power value range (I).

4. The method according to claim 1 or 2, wherein, If the second power value (P2) is outside the multi-value power value range (I) but in the single-value power value range (II), then when determining the current operating point (A) of the fan unit (11), only the current power value of the electric power (P) of the fan is used as at least one power value.

5. The method according to any one of claims 1 to 2, wherein, The ventilator (13) is a rearward-curved radial ventilator (14).

6. The method according to any one of claims 1 to 2, wherein, When determining the current operating point (A), the rotational speed (n) of the fan (13) is also taken into consideration.

7. The method according to claim 6, wherein, The power characteristic line (K) is selected from the comprehensive characteristic curve of the power characteristic lines (K1, K2, K3) based on the rotational speed (n1, n2, n3).

8. The method according to claim 6, wherein, The power characteristic line (K) is calculated based on the rotational speed (n) and a preset reference characteristic line (R) or a selected power characteristic line (K), wherein the reference characteristic line (R) characterizes the relationship between the power (P) of the fan (13) and the flow parameters of the fan unit (11) with respect to the reference rotational speed (n) of the fan (13).

9. The method according to any one of claims 1 to 2, wherein, A constant theoretical speed is preset for the ventilation fan unit (11) as the adjustment amount.

10. The method according to any one of claims 1 to 2, wherein, The ventilation unit (11) is communicatively connected to an external computing unit (33), wherein the external computing unit (33) is configured to determine the current working point (A) and / or preset other working points.

11. A ventilation system (10) having at least one ventilation unit (11) and an external computing unit (33), the computing unit being communicatively connected to the at least one ventilation unit (11), wherein, The ventilation system (10) is configured to perform the method according to any one of the preceding claims.

12. The ventilation system according to claim 11, wherein, The at least one fan unit (11) has a fan control device (25) which is communicatively connected to a modem (31) via a communication network (29).

13. The ventilation system according to claim 12, wherein, The modem (31) is communicatively connected to the external computing unit (33).

14. The ventilation system according to any one of claims 11 to 13, wherein, The ventilator (13) is a rearward-curved radial ventilator (14).

15. The ventilation system according to any one of claims 11 to 13, wherein, The ventilator (13) has a ventilator wheel (15) and a brushless electric motor (20), the electric motor being configured to rotate the ventilator wheel (15).

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