A method of determining air flow rate through motor assembly of air mobile device

Abstract

A method of determining an air flow rate value through a motor assembly of an air moving device includes measuring a first value of a first pressure at a first location in the motor assembly during motor operation of the motor assembly. The method further includes measuring, during motor operation of the motor assembly, a second value of a second pressure at a second location in the motor assembly, the second location downstream of the first location; and performing a determination process to determine an air flow rate value through the motor assembly based on the first value and the second value.

Description

Technical Field

[0001] The present invention relates to a method of determining air flow rate through a motor assembly of an air moving device, a set of machine-readable instructions for causing the method to be performed, and an air moving device having a memory including such instructions and a processor configured to perform the method by executing the instructions. Background Art

[0002] It is generally desirable to improve air moving devices, such as vacuum cleaners, in a variety of ways. For example, improvements may be needed in terms of efficiency, manufacturing costs, flexibility of use, and reliability. Summary of the invention

[0003] According to a first aspect of the present invention, a method for determining an air flow rate value through a motor assembly of an air moving device is provided, the method comprising: measuring a first value of a first pressure at a first position in the motor assembly during motor operation of the motor assembly; measuring a second value of a second pressure at a second position in the motor assembly during motor operation of the motor assembly, the second position being downstream of the first position; and performing a determination process to determine an air flow rate value through the motor assembly based on the first value and the second value.

[0004] The method provides an accurate and reliable method for measuring air flow rate in an air moving device. The method can be easily calibrated for an air moving device and is applicable regardless of the configuration of the motor assembly of the device. The method can also provide a computationally efficient way of determining air flow rate because the first value and the second value can be accurately and robustly mapped to air flow rate values.

[0005] The determining process may include determining a first dynamic pressure value of the motor based on the first value and the second value, and wherein the determination of the air flow rate through the motor assembly is based on the first dynamic pressure value.

[0006] The first value and the second value may easily allow obtaining a dynamic pressure measurement which may be efficiently mapped to an air flow rate value.

[0007] The method may include determining an ambient pressure value, and wherein determining the air flow rate includes compensating the determined ambient pressure value.The method may also include compensating the determined ambient temperature value.

[0008] Determining and compensating for ambient pressure and / or temperature values ​​may provide for the determination of reliable and accurate air flow rate values ​​over a range of different ambient conditions.

[0009] The method may include measuring an ambient pressure value at the first location when the motor is not operating. The method may also include measuring an ambient temperature value. The ambient temperature value may also be measured at the first location.

[0010] Measuring the ambient pressure and / or temperature at the first location allows obtaining a reliable and accurate value of the ambient pressure and / or temperature at the first location, which value may be used to compensate the first value for ambient conditions.

[0011] The first location may be located in a first portion of the motor assembly having a first cross-sectional area, and the second location may be located in a second portion of the motor assembly having a second cross-sectional area different from the first cross-sectional area.

[0012] The first position and the second position are located at the first and second parts of the motor assembly with different cross-sectional areas, respectively, and a reliable and measurable pressure difference can be provided between the first position and the second position when the motor is operating. This can allow the calculation of the air flow rate value based on the first value and the second value to be robust and accurate.

[0013] The first cross-sectional area may be greater than the second cross-sectional area.

[0014] A first cross-sectional area that is greater than a second cross-sectional area may provide a geometry corresponding to a bell mouth such that a given difference between the first value and the second value accurately indicates a given air flow rate.

[0015] The first position may be upstream of the motor coil assembly and the second position may be downstream of the motor coil assembly and upstream of the motor impeller.

[0016] These may be convenient corresponding locations for the first and second values ​​to be measured, so that the first and second values ​​may be used to reliably infer the air flow velocity.

[0017] Measuring a second value of a second pressure at a second location may include measuring the second value at a third location fluidly connected to the second location via a first fluid connection, or measuring a first value of a first pressure at a first location may include measuring the first value at a fourth location fluidly connected to the first location via a second fluid connection.

[0018] This may allow the first value or the second value to be measured at a convenient location in the motor assembly, which may allow accurate inference of the air flow rate when the pressure sensor is positioned at a location other than the first location or the second location in the motor assembly. This may be convenient in situations where, for example, it may be impractical to position the sensor at one or the other of the first location and the second location.

[0019] The first fluid connection and / or the second fluid connection may be provided by one or more respective conduits.

[0020] This may provide a convenient method of measuring the pressure at the first location and / or the second location by means of sensors located at locations other than the first location and the second location, respectively.

[0021] At least one of the one or more respective conduits may be integral with the housing of the motor assembly.

[0022] A conduit that is integral with the housing of the motor assembly may be a convenient way of providing the conduit in a space saving manner and may also involve minimal additional manufacturing expense.

[0023] The first value and the second value may be measured by respective first and second pressure sensors located at an upstream location in the motor assembly, and the second pressure sensor may be configured to measure the second value at a third location fluidly connected to the second location via the first fluid connection.

[0024] This may allow both the first and second pressure sensors to be located in a convenient location upstream of the motor, such as on a PCB of the air moving device.

[0025] The first value and the second value are measured by first and second pressure sensors, respectively, wherein the first pressure sensor is located upstream of the motor assembly and the second pressure sensor is located downstream of the motor assembly.

[0026] This may provide a second value to be measured without providing a fluid connection to allow the second value to be measured.For example, the second pressure sensor may be located at the inlet or outlet of the motor impeller.

[0027] The method may include using the determined air flow rate to determine: a filter loading condition of the air moving device; a blockage condition of the air moving device; or a dynamic loading condition of the air moving device.

[0028] This may allow the air flow rate provided by the method to be used to reliably and accurately determine other parameters that may be inferred based on the flow rate, such as filter loading conditions, clogging conditions, or dynamic loading conditions of the air moving device.

[0029] According to a second aspect of the invention, there is provided a set of machine readable instructions which, when executed by a processor of an air moving device, cause the air moving device to perform a method according to the first aspect of the invention.

[0030] According to a first aspect of the present invention, there is provided an air moving device, comprising: a processor; and a memory comprising a set of machine-readable instructions, which, when executed by the processor, cause the processor to perform the method according to the first aspect of the present invention.

[0031] The air moving device may include a first pressure sensor configured to measure a first value of a first pressure at a first location in the motor assembly and a second pressure sensor configured to measure a first value of the first pressure at the first location in the motor assembly.

[0032] The air moving device may be a vacuum cleaner.

[0033] Where appropriate, optional features of one aspect of the invention may be equally applied to other aspects of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will now be described, by way of example only, with reference to the following drawings, in which:

[0035] Figure 1 A schematic diagram showing an example motor assembly of an air moving device;

[0036] Figure 2 An example of an air moving device is shown;

[0037] Figure 3 is a flow chart representing a method of determining an air flow rate value through a motor assembly of an air moving device;

[0038] Figure 4 Aspects of an example method of determining air flow rate through a motor assembly of an air moving device are shown;

[0039] Figure 5 A schematic diagram showing another example motor assembly of an air moving device;

[0040] Figure 6 a schematic diagram showing certain components of a motor assembly of an air moving device according to an example; and

[0041] Figure 7 A schematic diagram is shown of certain components of an example motor assembly of an air moving device according to another example. DETAILED DESCRIPTION

[0042] Figure 1 An example schematic diagram of a motor assembly 100 of an air moving device is shown. The motor assembly 100 includes a set of coils 102, a shaft 104 on which magnets (not shown) are mounted, a bearing 106, and an impeller 108. The motor assembly 100 includes a motor air inlet 110 and an air outlet / diffuser 112. The motor assembly includes a circuit board 114 on which sensors, an ambient temperature sensor 116, and a first pressure sensor 118 are mounted. The motor assembly 100 includes a housing 124 in which other components are housed. The motor assembly 100 also includes a pre-motor filter 126 for filtering air that is drawn into the motor during use.

[0043] Figure 2An exemplary air moving device 200 including the motor assembly 100 is shown. The air moving device 200 is a vacuum cleaner. The vacuum cleaner 200 includes an inlet tube 202, and a tool 204 is attached to the distal end of the inlet tube 202. The tool 204 is used to engage with a surface to be cleaned by the vacuum cleaner and includes an air inlet (not shown) leading to the vacuum cleaner 200. The tool 204 can be active, including one or more mechanically operated components, such as a rotating brush bar, to assist in the cleaning task. In an example, the inlet tube 202 or a portion thereof can be removable. When the inlet tube 202 or a portion thereof is removed, a tool such as a passive tool can be attached to the device 200. Alternatively, the tool 204 can be passive and does not include any such mechanically operated components. However, the passive tool can include elements such as bristles or the like to help complete the cleaning task. The vacuum cleaner 200 also includes a dust separation chamber 206, which can be, for example, a cyclone chamber. The vacuum cleaner 200 also includes a processor 208 and a memory 210 for storing machine-readable instructions executed by the processor 208 to control the operation of components of the vacuum cleaner 200 including the motor 100. The machine-readable instructions, when executed, may cause the processor 208 to perform any of the example methods described herein.

[0044] In use, the motor of the motor assembly 100 draws air into the air moving device 200 through the air inlet, through the air moving device 200, and out of the exhaust port. The air is drawn through the device 200 along the air flow path 128, which passes through the inlet duct 202, the dust separation chamber 206, the motor assembly 100, and leaves the device 200 through the exhaust port.

[0045] Back to Figure 1 When the motor is used in the air moving device 200, current is passed through the coil 102, causing a changing magnetic field to be generated. The changing magnetic field is configured to act on the magnets on the shaft 104 to rotate the shaft 104 about its longitudinal axis. This in turn causes the impeller 108 to rotate. Air driven by the impeller 108 is drawn into the air moving device 200 along an air flow path 128. The air flow path 128 enters the motor assembly 100, passes through the pre-motor filter 126 that removes particulate matter from the air, and enters the housing 124 through the air inlet 110. The air flow path 128 continues through the motor to the impeller 108, and after passing through the impeller 108, leaves the motor assembly 100 through the air outlet 112.

[0046] The motor assembly 100 also includes a second pressure sensor 120 and wires 122 that electrically connect the second pressure sensor 120 to the circuit board 114. The motor assembly 100 also includes an inlet tube 132 that provides a fluid connection through the housing 124 from the second pressure sensor 120 to the inlet 130 of the impeller 108. This allows the second pressure sensor 120 to measure the pressure at the impeller inlet 130. Figure 1 It can be seen from the schematic diagram that the cross-sectional area of ​​the motor is narrower at the impeller inlet 130 than at the motor inlet 110.

[0047] Figure 3 A flow chart representation of an example method 300 of determining an air flow rate value through a motor assembly of an air moving device is shown.

[0048] The method 300 includes, at block 302, measuring a first value of a first pressure at a first location in the motor assembly during motor operation of the motor assembly. The first value may be a value measured by a first pressure sensor located upstream of the motor assembly. For example, Figure 1 In the example motor assembly 100 , the first value may be measured by the first pressure sensor 118 .

[0049] The method 300 includes, at block 304, measuring a second value of a second pressure at a second location in the motor assembly during motor operation of the motor assembly, the second location being downstream of the first location. The second location at which the second pressure is measured can be located at a location in the air moving device having a second cross-sectional area that is smaller than a first cross-sectional area at the location in the air moving device at which the first pressure is measured. This can allow a difference in reliable pressure values ​​to be measured between the first location and the second location. In some examples, the relationship between the first cross-sectional area and the second cross-sectional area can allow the difference between the first pressure and the second pressure to be associated with an air flow rate in a predefined manner. The second value can be a value measured by a second pressure sensor. For example, at Figure 1 In the motor assembly 100 of FIG. 1 , the second value may be measured by the second pressure sensor 120. In some examples, the second value may be measured by a second pressure sensor that is not located at the second position, which will be described in more detail below.

[0050] Method 300 includes, at box 306, performing a determination process to determine an air flow rate value through the motor assembly based on a first value and a second value. The determination process may include determining a first dynamic pressure value of the motor based on the first value and the second value. The determination of the air flow rate may be based on the first dynamic pressure value. For example, the first dynamic pressure value may be related to the air flow rate through the motor assembly by a predetermined relationship. The predetermined relationship may be determined, for example, by a calibration process, in which a dynamic pressure value determined based on the first pressure and the second pressure values ​​is measured simultaneously with the air flow rate through the motor, which air flow rate may be measured using a suitable measuring device. In some examples, the calibration process may include normalizing the measurements of the air flow rate and the dynamic pressure based on other operating parameters of the device, such as the input power provided to the motor.

[0051] In one example, the determination process includes: determining a gauge static pressure value in the motor assembly based on a first value of a first pressure at a first location and an ambient pressure value; determining a gauge total pressure at an impeller inlet based on a first value and a second value of a second pressure at a second location; determining a dynamic pressure based on the gauge static pressure and the gauge total pressure; determining a dynamic pressure value at standard temperature and pressure (STP) based on the dynamic pressure, the first value, and an ambient temperature value; and determining an air flow rate through the motor assembly based on the dynamic pressure at STP. Such an example is described in more detail below.

[0052] Figure 4 An example schematic relationship between an air flow rate value and a first dynamic pressure value is shown, which is determined based on first and second pressure values ​​at respective first and second locations in the air moving device, as described above. The air flow rate is shown in standard liters per second (slps) on the y-axis and the first dynamic pressure is shown in kPa on the x-axis. The first dynamic pressure may be a dynamic pressure at standard temperature and pressure (STP). As described above, the second location may be at the air inlet of an impeller of the device.

[0053] In an example, as described above, the first pressure and the second pressure are measured at portions of the motor assembly having different cross-sectional areas. Thus, the airflow path through the device may be such that the air velocity is different between the first location where the first pressure is measured and the second location where the second pressure is measured. The air velocity difference may result in different absolute pressure measurements being recorded at the first location and the second location, which are located at different points along the airflow path. This may allow the geometry of the motor assembly along the airflow path to resemble a bellmouth, and allow the air flow rate to be reliably and conveniently determined based on the first pressure and the second pressure values.

[0054] When using the device, it may be impractical and / or expensive to use such a measuring device to measure the air flow rate when using the device. However, by performing such a calibration process, a reliable and accurate measurement of the air flow rate through the device can be determined based on appropriate pressure measurements. Reliable and accurate measurement of the air flow rate value of the device in use can allow the value to be used for various purposes. For example, certain control aspects of the device can be based on the air flow rate value. For example, a determined relationship between motor speed and air flow rate can be used as a fault or blockage indicator. For example, if the speed of the motor is high and the air flow rate is low, this may indicate that there is a blockage in the air flow through the device. For example, this may be due to dust clogging the filter and / or an object blocking the inlet pipe of the device. In one example, the air flow rate can be used to determine a filter loading value for the device. The filter loading can be the loading level of the filter that filters particulate matter from the air flow through the motor. For example, in Figure 1 In the motor assembly 100 of the present invention, the filter load can be the load level of the pre-filter 126. The load level of the filter can determine how much dust the filter has collected. In an example, this can be expressed in terms of the amount of dust that the filter may collect before it is considered to need to be replaced or cleaned. For example, a filter load of 100% may indicate that the filter has collected a certain amount of dust and is therefore considered to need to be replaced or cleaned. A filter load level of 0% may indicate that the filter has not collected any dust, for example, because it has been completely cleaned or newly replaced. Typically, during the use of the device 200, the filter load level can gradually increase. As the filter collects more dust, it may provide greater dynamic resistance to the airflow entering the motor. In some examples, the air flow rate can be used, for example in combination with a determined speed at which the motor rotates, to estimate the filter load level.

[0055] By determining the air flow rate value in an accurate and reliable manner, the control of the device can be made more reliable. For example, the occurrence of incorrect fault notifications can be reduced. In addition, the accurate method for determining the air flow rate can allow the motor power to be increased. For example, the maximum motor power may be limited in part by the minimum air flow rate measured. A more accurate determination of the air flow rate can allow the motor input power to be increased because the tolerance and uncertainty around the minimum air flow rate through the motor is reduced.

[0056] Figure 5 Another exemplary schematic diagram of a motor assembly 500 is shown. The motor assembly 500 includes the same Figure 1 For features corresponding to those of the motor assembly 100 described above, such features are labeled with the same reference numerals where labeled. For clarity, Figure 5 The pre-motor filter is not shown.

[0057] Except in Figure 5In the motor assembly 500, the second pressure sensor 520 is located outside the circuit board 514, and the motor assembly 500 is Figure 1 The motor assembly 100 is the same as the motor assembly 100 of FIG. The passage or conduit 522 provides a fluid connection between the second pressure sensor 520 and the impeller inlet 530. The passage 522 allows the second pressure sensor 520 to measure the pressure at the impeller inlet 530 without the second pressure sensor being located at the impeller inlet 530.

[0058] Such a passage can be provided in a variety of ways. In one example, the passage 526 can be formed by a conduit. The conduit can, for example, extend along the outer surface of the housing 524 and extend through a hole 526 in the housing to provide a fluid connection from the second pressure sensor 520 to the impeller inlet 530. At one end of the passage 526 where the second pressure sensor 520 is located, an airtight seal can be formed around the second pressure sensor 520. The seal can, for example, include a circular, EPDM foam seal that seals the conduit to the location on the circuit board 514 where the second pressure sensor 120 is located. Figure 1 A similar seal is formed around the second pressure sensor 120 of the motor assembly 100 .

[0059] In another example, the passageway may be integral to the housing of the motor assembly. Figure 6 An example schematic diagram of such a housing 624 is shown, wherein the passage 622 extends through the housing 624. In such an example, the housing 624 can be formed by an injection molding process, and the passage through the housing 624 is formed during the injection molding, for example, by using removable pins 630a, 630b during the injection molding. In use, with reference to Figure 5 In the manner described, a hole 626 through the housing 624 leads to the impeller inlet of the motor. In use, the second pressure sensor is located at the upstream end 628 of the channel 622. This provides a fluid connection to the second pressure sensor via the channel 622 and allows the second pressure to be configured to measure the pressure at the impeller inlet. This can allow the second pressure sensor to be conveniently positioned. The second pressure sensor can be located, for example, on a circuit board of the device. In addition, it can be cost-effective and convenient to form the channel 622 integrally with the housing 624.

[0060] In another example, a channel may be formed between an outer surface of the housing and a mount positioned against the outer surface of the housing. Figure 7 Such an example is schematically illustrated. Figure 7In the embodiment, a mounting member 732, for example made of rubber, has a groove 734 therein. The mounting member 732 seals the outer surface of the housing 724 in an airtight manner, and the housing 724 has a hole 726 which, in use, leads to the impeller inlet. The passage 722 is formed by the gap provided by the groove 734 in the mounting member 732 between the mounting member 732 and the outer surface of the housing 724. Figure 6 and Figure 7 In the example of , in use, the second pressure sensor is sealed to the channel 622, 722 in an airtight manner at the upstream end 628, 728 of the channel 622, 722. For example, in Figure 7 In the example of FIG. 7 , the mount 732 may be a rubber mount that forms a seal around the second pressure sensor.

[0061] In reference Figure 6 and Figure 7 In each of the above described example motor assemblies 100, 400 and variations thereof, the first pressure sensor 118, 418 is positioned to take pressure measurements at the air inlet 110, 410. The pressure measurements obtained by the first pressure sensor 118, 418 include the ambient pressure p measured before the motor is started. a Furthermore, the pressure measurements performed by the first pressure sensor 118, 418 include measurements of the first pressure p1 performed during operation of the motor. The temperature sensor 116, 416 is configured to measure the ambient temperature T a The second pressure sensor 120, 420 is configured to measure the second pressure p2 at the impeller inlet 130, 430 during operation of the motor. a , each of the first pressure p1 and the second pressure p2 is an absolute pressure.

[0062] In an example, measurements taken by the first pressure sensor 118, 418, the second pressure sensor 120, 420, and the temperature sensor 116, 416 are used to determine a dynamic pressure value. The dynamic pressure value can be used to determine the air flow rate through the motor assembly 100, 400. In one example, the dynamic pressure measurement is determined as follows.

[0063] By subtracting the ambient pressure p from the first pressure p1 a To determine the static pressure p in the motor static The first pressure p1 is usually lower than the ambient pressure p a , because the operation of the motor causes a partial vacuum to be created within the motor housing 124 , 424 .

[0064] The total instrument pressure p at the impeller inlet is determined by subtracting the second pressure p2 from the first pressure p1 total The total pressure at the impeller inlet is p total From the static pressure pstatic and dynamic pressure p dyn The second pressure p2 is generally lower than the first pressure p1 due to the smaller cross-sectional area at the impeller inlet 130 , 430 compared to the motor inlet 110 , 410 and the higher associated air velocity.

[0065] Dynamic pressure p at the impeller inlet 130, 430 dyn By the total pressure p at the impeller inlet 130, 430 total Subtract the static pressure p in the motor from static The dynamic pressure p dyn May also be called air velocity pressure.

[0066] The dynamic pressure p dyn , first pressure p1 and temperature T a Input into the density ratio formula to determine the dynamic pressure value p at STP dyn@STP . p dyn@STP The value of is the dynamic pressure value corrected for standard temperature and pressure. The dynamic pressure value is therefore normalized for the ambient conditions in which the motor is operating. This allows, for example, the definition of a single lookup curve relating dynamic pressure values ​​to air flow rate or other parameters. The applicable density ratio for a given motor depends on the type of motor. For example, the following density ratio formulas (1) to (3) apply to constant power motors, AC series motors, and constant speed motors, respectively:

[0067] (1)

[0068] (2)

[0069] (3)

[0070] Among them, p dyn@STP , p1 and p dyn In kPa, T a In degrees Celsius, 101.325 is the standard pressure in kPa, 293 is the standard temperature in Kelvin, and 273.15 is 0 degrees Celsius in Kelvin.

[0071] The dynamic pressure value may be mapped to an air flow rate value through the motor. The mapping of the dynamic pressure value to the air flow rate may be determined, for example, by a calibration process. In such a calibration process, the air moving device may be operated with an air flow rate measuring device, which may include a bellmouth, a venturi tube, or an orifice plate, for measuring the air flow rate through the device, while measurements are taken that allow determination of a dynamic pressure value corresponding to the air flow measurement. Thus, when the device is operated after calibration, a dynamic pressure value may be determined and mapped to an air flow rate value in order to determine the air flow rate through the device in use.

[0072] The above embodiments should be understood as illustrative examples of the present invention. Other embodiments are contemplated. It should be understood that any feature described with respect to any one embodiment may be used alone or in combination with other features described, and may also be used in combination with one or more features of any other embodiment, or in combination with any combination of any other embodiment. In addition, equivalents and modifications not described above may also be employed without departing from the scope of the present invention as defined by the appended claims.

Claims

1. A method for determining a value of air flow rate through a motor assembly of an air moving device, the method comprising: measuring, during motor operation of the motor assembly, a first value of a first pressure at a first location in the motor assembly; measuring, during motor operation of the motor assembly, a second value of a second pressure at a second location in the motor assembly, the second location being downstream of the first location; and A determination process is performed to determine a value of the air flow rate through the motor assembly based on the first value and the second value. 2 . The method of claim 1 , wherein the determining process includes determining a first dynamic pressure value of the motor based on the first value and the second value, and wherein the determination of the air flow rate through the motor assembly is based on the first dynamic pressure value.

3. The method according to claim 1 or 2, wherein the method comprises determining an ambient pressure value and / or an ambient temperature value, and wherein determining the air flow rate comprises compensating the determined ambient pressure value and / or the determined ambient temperature value.

4. The method according to claim 3, wherein the method comprises measuring an ambient pressure value and / or an ambient temperature value at the first location when the motor is not operating.

5. The method of any one of the preceding claims, wherein the first position is located in a first portion of the motor assembly having a first cross-sectional area and the second position is located in a second portion of the motor assembly having a second cross-sectional area different from the first cross-sectional area. The method of claim 5 , wherein the first cross-sectional area is greater than the second cross-sectional area.

7. A method according to any one of the preceding claims, wherein the first position is upstream of a coil assembly of a motor and the second position is downstream of the coil assembly of the motor and upstream of an impeller of the motor.

8. A method according to any of the preceding claims, wherein measuring a second value of a second pressure at the second position includes measuring the second value at a third position fluidly connected to the second position via a first fluid connection, or measuring a first value of a first pressure at the first position includes measuring the first value at a fourth position fluidly connected to the first position via a second fluid connection.

9. The method of claim 8, wherein the first fluid connection and / or the second fluid connection is provided by one or more respective conduits.

10. The method of claim 9, wherein at least one of the one or more respective conduits is integral with a housing of the motor assembly.

11. The method according to any one of claims 8 to 10, wherein the first value and the second value are measured by a first pressure sensor and a second pressure sensor located upstream of the motor assembly, respectively, and wherein, The second pressure sensor is configured to measure the second value at a third location fluidly connected to the second location by the first fluid connection.

12. The method according to any one of claims 1 to 7, wherein the first value and the second value are measured by a first pressure sensor and a second pressure sensor, respectively, wherein the first pressure sensor is located upstream of the motor assembly and the second pressure sensor is located downstream of the motor assembly.

13. A method according to any one of the preceding claims, wherein the method comprises using the determined air flow rate to determine: filter loading conditions of the air moving device; A blockage condition of the air moving device; or Dynamic loading conditions of the air moving device.

14. A set of machine readable instructions which, when executed by a processor of an air moving device, cause the air moving device to perform the method of any one of claims 1 to 13.

15. An air moving device, comprising: processor; and A memory comprising a set of machine-readable instructions which, when executed by the processor, cause the processor to perform a method according to any one of claims 1 to 13.

16. The air moving device according to claim 15, comprising: a first pressure sensor configured to measure a first value of a first pressure at a first location in the motor assembly; and A second pressure sensor is configured to measure a first value of a first pressure at a first location in the motor assembly.

17. An air moving device according to claim 15 or 16, wherein the air moving device is a vacuum cleaner.

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