AIR TREATMENT APPARATUS

TECHNICAL FIELD

[0001]The present disclosure relates to an air treatment apparatus, such as an air purifying apparatus.

BACKGROUND

[0002]Air treatment apparatuses, such as air purifiers, typically include an air passage extending from an inlet to an outlet, and an air treatment device for treating air flowing along the air passage. In some cases, air may be driven along the air passage by a fan.

[0003]Some apparatuses also include sensors that detect characteristics of air that has not been treated (such as that from the surrounding environment). This can be useful for controlling how the air is treated. For example, it can be desirable to sense ambient temperature, humidity, and the presence of pollutants (e.g. particles or gases such as formaldehyde) in the surrounding air. This can lead to treatment that is optimised to the environment in which the apparatus is located.

[0004]In some cases, however, the performance of such an apparatus can change over time. This can be caused, for example, by clogging of a filter or a fault in a component of the apparatus.

[0005]There is therefore a general need to identify when the performance of an apparatus changes so that maintenance, repair or an adjustment of the operating parameters of the apparatus can be performed to address any issue.

[0006]The present disclosure has been devised in light of the above considerations.

SUMMARY

[0019]In the baseline configuration, the air that is sensed by the one or more sensors flows from the first opening, which is arranged to receive air that is untreated by the air treatment device (e.g. air from the external environment). The sensors therefore sense untreated (e.g. ambient) air in this configuration. On the other hand, in the diagnostic configuration, the air that is flowing across the one or more sensors flows from the second opening, which is open to the primary air flow passage downstream of the air treatment device. Thus, in the diagnostic configuration the air that is sensed is air that has been treated by the air treatment device. Accordingly, the airflow director provides for sensing of both untreated (e.g. ambient air) and treated air.

[0020]The sensed characteristics of the untreated (e.g. ambient air) can be used for control of the air treatment device and/or the primary air mover. The sensed characteristics of the treated air can be used to determine the performance of the system (e.g. the performance of the air treatment device). In some cases, the sensed characteristics of the treated air can be compared with those of the untreated (e.g. ambient) air.

[0021]Such a comparison may, for example, be used to indicate whether the treatment process is operating correctly (i.e. the air treatment device is performing as expected), when a consumable component requires replacement (e.g. a filter such as a carbon filter).

[0022]Importantly, these functions are achieved without the need to provide two separate arrangements of sensors (i.e. one for each of the two configurations). This reduces the cost and complexity of the apparatus.

[0023]Optional features of the first aspect will now be set out.

[0024]The first opening may open to the external environment. In such embodiments, in the baseline configuration air entering the first opening and passing across the one or more sensors will be ambient air. Accordingly, in such arrangements the baseline configuration may be referred to as an ambient configuration.

[0025]When the first opening opens to the external environment, the apparatus may be configured such that in the diagnostic configuration air that has passed over the sensor is discharged to the external environment though the first opening. In this way, the first opening may have dual functionality (i.e. may be an inlet in the baseline (e.g. ambient) configuration and an outlet in the diagnostic configuration). Again, this may simplify the construction of the apparatus.

[0026]The first opening may open to the primary airflow passage upstream of the air treatment device. In such embodiments, in the baseline configuration, the air entering the first opening and passing across the one or more sensors is air that is untreated by the air treatment device. This may be ambient air or may be air that has already been treated in some manner (albeit not by the air treatment device).

[0027]When the first opening opens to the primary airflow passage upstream of the air treatment device, the apparatus may be configured such that in the diagnostic configuration air that has passed over the one or more sensors is discharged into the primary airflow passage through the first opening. In this way, the first opening may have dual functionality (i.e. may be an inlet of the secondary airflow passage in the baseline (e.g. ambient) configuration and an outlet in the diagnostic configuration).

[0028]The apparatus may comprise one or more additional air treatment devices, and (when open to the primary airflow passage) the first opening may be arranged to receive air treated by at least one of the one or more additional air treatment devices. Thus, the air received by the sensors in the baseline configuration may be treated by the one or more additional air treatment devices (but not the air treatment device that is downstream of the first opening).

[0029]The apparatus may comprise one or more further air treatment devices, and the first opening may open to the primary airflow passage upstream of the further air treatment devices. In embodiments comprising one or more further air treatment devices, in the diagnostic configuration the sensors may receive air treated by the air treatment device and one or more further air treatment devices, and in the baseline configuration the sensors may receive air untreated by the air treatment device and one or more further air treatment devices. As may be appreciated, in this case, a comparison of measurements made in the diagnostic configuration with measurements made in the baseline configuration can provide insight on the combined performance of the air treatment device and the one or more further air treatment devices.

[0030]For clarity, the phrase “additional” air treatment devices as used above refers to air treatments devices upstream of the first opening and the phrase “further” air treatment devices is used to refer to air treatment devices downstream of the first opening. The apparatus may include both “additional”and “further”air treatment devices.

[0031]Regardless of whether the first opening opens to the external environment or to the primary airflow passage, the airflow director may be in the form of a secondary air mover arranged to move air along the secondary airflow passage. The secondary air mover may be arranged between the one or more sensors and the first opening. The secondary air mover may alternatively be arranged between the one or more sensors and the second opening.

[0032]The secondary air mover may be a bi-directional fan. The controller may be configured to control the fan to drive airflow in a first direction in the baseline (e.g. ambient) configuration and a second direction, opposite to the first direction, in the diagnostic configuration (e.g. the fan may be selectively driven to rotate in two different rotational directions).

[0033]As an alternative to a bi-directional fan, the airflow director may comprise two air movers (e.g. fans) configured to drive air in opposite directions to one another. In this case, one air mover may be deactivated while the other is active.

[0034]In some embodiments, as will now be described, it may not be necessary to provide a fan that is bi-directional. Instead, the controller may be configured to control the flow speed of the secondary air mover relative to the primary air mover such that, in the diagnostic configuration, the primary air mover moves air from the primary airflow passage to the sensor through the second opening, and in the baseline (e.g. ambient) configuration the secondary air mover moves air from the first opening and across the sensor to the second opening.

[0035]For example, the controller may be configured to control the secondary air mover to have a first flow speed in the diagnostic configuration and a second flow speed in the baseline (e.g. ambient) configuration that is different to the first flow speed.

[0036]In such arrangements, one of the first and second flow speeds will be lower than the other. The apparatus may be configured such that when the secondary air mover is at the lower flow speed, the primary air mover overpowers the secondary air mover in the secondary airflow passage (such that flow through the secondary airflow passage is provided by the primary air mover). Likewise, the apparatus may be configured such that when the secondary air mover is at the higher flow speed, the secondary air mover overpowers the primary air mover (in the secondary passage) such that flow through the secondary passage is provided by the secondary air mover. In such arrangements, the secondary air mover may be configured to move air in the secondary passage in an opposite direction to the primary air mover.

[0037]As may be appreciated, depending on the configuration of the apparatus (e.g. the location and orientation of the second opening), it is possible for the primary air mover to push air through the second opening or to draw air from the second opening (and/or to push or draw air into/from the first opening).

[0038]For example, the second opening may face at least partly in an upstream direction of the first airflow passage so as to receive air from the first airflow passage (the momentum of the air meaning air flows form the first airflow passage through the second opening). Alternatively, the second opening may face at least partly in a downstream direction of the first airflow passage and air may be drawn from the second opening into the first airflow passage. To promote flow of air into the first airflow passage from the second opening, the first airflow passage may comprise a narrowed portion (i.e. a portion of smaller cross-sectional area) at or proximate to the second opening. In other words, the apparatus may be configured to exploit the venturi effect so as to draw air from the second opening into the primary airflow passage.

[0039]When the configuration of the apparatus is such that the primary air mover can push air through the second opening, the secondary air mover may be arranged to move air towards the second opening (i.e. such that the primary and secondary air movers act against one another on air within the secondary airflow passage). In such embodiments, the first flow speed of the secondary air mover (in the diagnostic configuration) may be lower than the second flow speed (in the baseline (e.g. ambient) configuration). Accordingly, in the diagnostic configuration, the primary air mover may overpower the secondary air mover in the secondary airflow passage such that it pushes are air through the second opening and across the sensors. Likewise, in the baseline (e.g. ambient) configuration (when the flow speed of the secondary air mover is higher) the secondary air mover may instead overpower the primary air mover such that air is moves in the secondary passage in a direction towards the second opening.

[0040]On the other hand, when the configuration of the apparatus is such that primary air mover can draw air through the second opening, the secondary air mover may be arranged to move air in a direction away from the second opening (again, such that the primary and secondary air movers act against one another on air within the secondary airflow passage). In such embodiments, the first flow speed of the secondary air mover (in the diagnostic configuration) may be higher than the second flow speed (in the baseline (e.g. ambient) configuration). Accordingly, in the diagnostic configuration, the secondary air mover may overpower the primary air mover such that air moves in a direction away from the second opening. Likewise, in the baseline (e.g. ambient) configuration, the primary air mover may overcome the (lower flow speed of) the secondary air mover such that air is drawn across the one or more sensors and through the second opening.

[0041]As may be appreciated from the above, such arrangements can achieve bi-directional flow within the secondary passage with a single unidirectional air mover in the secondary passage. This can reduce the complexity of the apparatus.

[0042]In some embodiments, the “low flow speed” of the secondary air mover may be zero. That is, the controller may be configured to deactivate the secondary air mover in the diagnostic or baseline (e.g. ambient) configuration.

[0043]For the avoidance of doubt, the term “flow speed” is a reference to the air flow rate which the air mover would provide in the absence of any external influence (i.e. such as that provided by another air mover). In the example of a fan, the flow speed will be determined by the speed at which the blades of the fan are rotated (i.e. the flow speed will be the fan speed).

[0044]The primary air mover may, in use, be active (i.e. operating) in both the baseline (e.g. ambient) and diagnostic configurations. The controller may be configured to control the flow speed of the primary air mover independently of whether the airflow director is in the baseline (e.g. ambient) or diagnostic configuration. The flow speed of the primary air mover may be the same in baseline (e.g. ambient) and diagnostic configurations.

[0045]The controller may be configured to adjust the flow speed of the secondary air mover in response to changes in the flow speed of the primary air mover. The flow speed of the primary air mover may, for example, be user adjustable, or may be adjusted by the controller in response to a detected condition (e.g. a detected ambient condition such as temperature). As may be appreciated, the flow speed of the primary air mover may affect the flow rate of air through the secondary airflow passage. Thus, the flow speed of the secondary air mover may be adjusted to accommodate for this change in flow rate (e.g. in order to maintain a consistent flow rate of air through the secondary passage).

[0046]The airflow director may comprise a valve. The valve may be configured to alter the orientation of the second opening. For example, in the baseline (e.g. ambient) configuration, the second opening may face at least partly upstream in the primary airflow passage. In the diagnostic configuration, the valve may be positioned such that the second opening faces in a different direction to that of the baseline (e.g. ambient) configuration (e.g. downstream in the primary airflow passage, or transverse to the primary airflow passage).

[0047]Alternatively, the valve may be arranged to divert airflow in the secondary airflow passage (e.g. by at least partly obstructing a portion of the secondary airflow passage). For example, when the first opening opens to the external environment, the secondary airflow passage may comprise a first branch that extends to the second opening and a second branch that extends to a further opening. The second opening may be downstream of the primary air mover and may be arranged such that, in use, air is pushed by the primary air mover into the second opening. The further opening may be upstream of the primary air mover and arranged such that, in use, air is drawn from the further opening by the primary air mover. In the baseline (e.g. ambient) configuration, the controller may control the valve to be positioned so as to obstruct the second branch (so that air is pulled from the first opening through to the further opening via the first branch). In the diagnostic configuration, the controller may control the valve to be positioned so as to obstruct the first branch (so that air is pushed from the second opening to the first opening via the second branch).

[0048]In another example (in which the valve is arranged to divert airflow in the secondary airflow passage), when the first opening opens to the primary airflow passage, the secondary passage may comprise a further opening. The further opening may open to the external environment or the primary airflow passage (e.g. downstream of the air treatment device). In this case, the secondary passage may include a first branch extending to the first opening and a second branch extending to the second opening. Each branch may be in fluid communication with the further opening (to the external environment). For example, the first and second branches may join, to a further branch that extends to the further opening. The one or more sensors may be disposed in the further branch. One or more further (e.g. secondary) air movers may be provided to move air in a direction from the first opening to the further opening and from the second opening to the further opening. The valve may be controlled to obstruct the passage of airflow from the first opening to the further opening, or to obstruct the passage of airflow from the second opening to the further opening. Thus, in the baseline configuration, the valve may be controlled to obstruct the passage of airflow from the second opening, such that air that passes across the one or more sensors comes from the first opening. In the diagnostic configuration, the valve may be controlled to obstruct the passage of airflow from the first opening, such that air that passes across the one or more sensors comes from the second opening.

[0049]Regardless of the nature of the airflow director, the primary airflow passage may comprise a narrowed portion (i.e. a region of smaller cross-sectional area than adjacent regions). The second opening may open to the narrowed portion. In use, airflow may increase in speed (and lower in pressure) as it passes through the narrowed portion. This may promote movement of air from the secondary airflow passage into the primary airflow passage (through the second opening).

[0050]The apparatus may be configured such that in the baseline (e.g. ambient) configuration air that has passed over the sensor is discharged into the primary airflow passage through the second opening. In this way, the second opening may have dual functionality (i.e. may be an inlet in the diagnostic configuration and an outlet in the baseline (e.g. ambient) configuration). This may simplify the construction of the apparatus.

[0051]The secondary airflow passage may comprise a third opening which is open to the external environment (this third opening may be the further opening discussed above). The apparatus may be configured such that in the baseline (e.g. ambient) configuration air that has passed over the sensor is discharged to the external environment through the third opening (e.g. a branch of the secondary passage may extend to the third opening).

[0052]The apparatus may comprise a filter upstream of the one or more sensors in one of the baseline (e.g. ambient) configuration and the diagnostic configuration. For example, the filter may be disposed between the first opening and the one or more sensors (e.g. may be disposed at the first opening). In this way, air (e.g. ambient air) received by the sensors may be filtered. Such an arrangement may be particularly desirable when the air subsequently flows from the sensors into the primary airflow passage (i.e. for subsequent discharge through the outlet of the device). The one or more sensors may comprise one or more of a gas sensor, particle sensor, and environmental condition sensor.

[0053]The gas sensor (when present) may be configured to detect volatile organic chemicals and/or volatile inorganic chemicals. The gas sensor may be configured to detect total volatile inorganic compounds.

[0054]The particle sensor (when present) may be configured to detect particles that are 10 microns or less in diameter (PM10 particles) or particles 2.5 microns or less in diameter (PM2.5 particles). The particle sensor may be configured to detect particles of other given (maximum) diameters. The particle sensor may be configured to detect one or more of silica, pollen, soot and heavy metals.

[0055]The one or more sensors may comprise an environmental condition sensor configured to detect one or more of temperature, relative or absolute humidity, air pressure sensor, a wet bulb temperature and dry bulb temperature.

[0056]In some embodiments, the apparatus may comprise sensors in the primary airflow passage. Such sensors may thus be arranged for detecting a characteristic of ambient air, but will not receive treated air in the diagnostic configuration (i.e. will only receive ambient air in normal use).

[0057]The controller (e.g. a microcontroller) may be configured to move or switch the airflow director from the ambient configuration to the diagnostic configuration for a predetermined period of time. The controller may be configured to move or switch the airflow director from the ambient configuration to the diagnostic configuration at predetermined intervals. The apparatus may comprise a user interface configured to generate a signal upon input from a user. The controller may be configured to move or switch the airflow director from the ambient configuration to the diagnostic configuration upon receipt of a signal from the user interface. The controller may be configured to be activated remotely.

[0058]The air treatment device may comprise an air purifier. Alternatively or additionally the air treatment device may comprise a heater, humidifier, de-humidifier and/or cooler. For example, the air treatment device may comprise an air purifier and a heater downstream of the air purifier. The air treatment device may comprise a catalyst configured to remove one or more chemicals from air flowing along the primary airflow passage. For example, the catalyst may be configured to capture formaldehyde.

BRIEF SUMMARY OF THE FIGURES

[0059]Embodiments will now be discussed with reference to the accompanying figures in which:

[0060]FIGS. 1A and 1B are schematic views of an air treatment apparatus according to a first embodiment;

[0061]FIGS. 2A and 2B are schematic views of an air treatment apparatus according to a second embodiment;

[0062]FIGS. 3A and 3B are schematic views of an air treatment apparatus according to a third embodiment;

[0063]FIGS. 4A and 4B are schematic views of an air treatment apparatus according to a fourth embodiment;

[0064]FIGS. 5A and 5B are schematic views of an air treatment apparatus according to a fifth embodiment

[0065]FIGS. 6A and 6B are schematic views of an air treatment apparatus according to a sixth embodiment;

[0066]FIGS. 7A and 7B are schematic views of an air treatment apparatus according to a seventh embodiment;

[0067]FIGS. 8A and 8B are schematic views of an air treatment apparatus according to a eighth embodiment; and

[0068]FIGS. 9A and 9B are schematic views of an air treatment apparatus according to a ninth embodiment.

DETAILED DESCRIPTION

[0069]Aspects and embodiments will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art.

[0070]FIGS. 1A and 1B illustrate an air treatment apparatus 10 in the form of an air purifier. The air treatment apparatus 10 includes a primary airflow passage 11 extending from an inlet 12 to an outlet 13. A primary air mover 14 is disposed in the primary airflow passage 11 to move air along the primary airflow passage 11 from the inlet 12 to the outlet 13. An air treatment device 15 is also arranged in the primary airflow passage 11 and is configured to treat (i.e. purify) air flowing along the primary airflow passage 11. The primary airflow passage 11 thus provides for flow of a main (primary) airflow that supports the main function of the air purifier (providing purified air to a user).

[0071]The apparatus 10 also includes a secondary airflow passage 16 that extends between a first opening 17 that opens to the external environment, and a second opening 18 that is connected to the primary airflow passage 11. Specifically, the second opening 18 connects to the primary airflow passage 11 at a region of the primary airflow passage 11 that is downstream of the air treatment device 15. One or more sensors 19 are arranged in or adjacent to the secondary airflow passage 16 for sensing various characteristics of the air in the secondary airflow passage 16. The sensors 19 may include one or more gas sensors, particle sensors and/or environmental condition sensors.

[0072]The apparatus 10 further includes an airflow director (not shown) and a controller (not shown) configured to control the airflow director between a baseline (in this case, an ambient) configuration and a diagnostic configuration.

[0073]The ambient configuration is shown in FIG. 1A. In this configuration, air flows through the secondary airflow passage 16 from the first opening 17 (which acts as an inlet in this configuration), across the sensors 19 and then to the second opening 18 (which acts as an outlet) so as to join air flowing through the primary airflow passage 11. In other embodiments, instead of flowing to the second opening 18, the air may be diverted elsewhere (e.g. to a further outlet of the apparatus 10). In this ambient configuration, the air that flows across the sensors 19 is ambient air. Hence, the sensors 19 can detect characteristics of the ambient air (i.e. characteristics of the air of the surrounding environment). This may be useful, for example, in control of the apparatus 10 (such as in control of the primary air mover 14 or the air treatment device 15).

[0074]The diagnostic configuration is shown in FIG. 1B. In this configuration, air flows through the secondary airflow passage 16 from the second opening 18 (which now acts as an inlet), across the sensors 19 and is discharged through the first opening 17 (which now acts as an outlet). In other embodiments, the air may be diverted for discharge elsewhere (e.g. to a further outlet of the apparatus 10). In this diagnostic configuration, the air that flows across the sensors 19 is treated air (i.e. air that has been treated by the air treatment device 15). In this case, the measurements performed by the sensors 19 may be useful in understanding the performance of the air treatment device 15. Measurements taken in the diagnostic configuration may be compared with measurements taken in the ambient configuration to determine the performance of the air treatment device 15.

[0075]Accordingly, the arrangement described above and shown in FIGS. 1A and 1B is capable of providing both baseline (i.e. ambient) and diagnostic measurements with a single arrangement of sensors 19. This can reduce the complexity and cost of the apparatus 10.

[0076]The flow director can take various forms. In the embodiment of FIGS. 2A and 2B (in which the same reference numerals have been used), for example, the flow director is in the form of a bi-directional fan 20 (i.e. a fan that is capable of operating in two opposite directions) provided within the secondary airflow passage 16.

[0077]FIG. 2A illustrates the ambient configuration of the bi-directional fan 20. In this configuration, the bi-directional fan 20 is controlled to operate in a first direction that moves air from the first opening 17 to the second opening 18, such that the air that flows across the sensors 19 is ambient air. The air the passes into the primary airflow passage 11 and is discharged with the primary airflow through the outlet 13.

[0078]In FIG. 2B, the bi-directional fan 20 is controlled to operate in a second direction (opposite to the first direction) such that it draws air from the primary airflow passage 11, through the second opening 18. The air drawn into the secondary airflow passage 16 is then drawn across the sensors 19 and is discharged through the first opening 17. Hence, in this configuration, the air that flows across the sensors is treated air that has been treated by the air treatment device.

[0079]In FIGS. 3A and 3B, the flow director is in the form of a unidirectional fan 21, which is configured to move air through the secondary airflow passage 16 in a direction from the second opening 18 to the first opening 17. This embodiment also differs from that previously described in that the primary airflow passage 11 is provided with a narrowed portion 22 that increases the speed of the airflow, and thus reduces its pressure, in the region of the primary airflow passage 11 which is connected to the secondary airflow passage 16 via the second opening 18.

[0080]FIG. 3A shows the unidirectional fan 21 in the ambient configuration. In this configuration, the unidirectional fan 21 is deactivated (i.e. it is not driving airflow along the secondary airflow passage 16). Instead, airflow is drawn from the secondary airflow passage 16, through the second opening 18 due to the reduced pressure in the narrowed portion 22 of the primary airflow passage 11. In other words, this arrangement exploits the venturi effect to draw air from the secondary airflow passage 16 into the primary airflow passage 11. In other embodiments, it may not be necessary to provide the narrowed portion 22 (i.e. the pressure drop created by the primary air mover 14 may be sufficient to draw airflow from the secondary airflow passage 16). As airflow is drawn from the secondary airflow passage 16, it flows in a direction from the first opening 17 to the second opening 18, across the sensors 19. Accordingly, the sensors 19 are able to measure characteristics of the ambient air.

[0081]In FIG. 3B, the unidirectional fan 21 is shown in the diagnostic configuration. In this configuration, the unidirectional fan 21 is activated. The flow speed of the unidirectional fan 21 is such that it is able to overpower the suction formed by the narrowed portion 22 of the primary airflow passage 11. Accordingly, air is drawn from the primary airflow passage 11 into the secondary airflow passage 16, through the second opening 18, by the unidirectional fan 21. In this way, treated air flows across the sensors 19 for measurement of characteristics thereof, and is subsequently discharged through the first opening 17.

[0082]As may be appreciated, the ambient configuration (described above with respect to FIG. 3A) may be achieved with the unidirectional fan 21 activated, but at a lower flow speed than in the diagnostic configuration (i.e. the flow speed may be sufficiently low in the diagnostic configuration that air is nevertheless drawn from the secondary airflow passage 16 into the primary airflow passage 11).

[0083]In FIGS. 4A and 4B, the flow director is in the form of a valve 23, which is rotatable to alter the position of the second opening 18 in the primary airflow passage 11. FIG. 4A illustrates the valve 23 in the ambient configuration. In this configuration the valve 23 is arranged such that the second 18 opening faces downstream in the primary airflow passage 11. As a consequence of this, air is drawn into the primary airflow passage 11 from the secondary airflow passage 16 (due to the faster air speed, and thus lower pressure in the primary airflow passage 11).

[0084]On the other hand, in the diagnostic configuration of the valve 23 (shown in FIG. 4B), the second opening 18 faces upstream in the primary airflow passage 11. In this case, the momentum of the airflow in the primary airflow passage 11 causes air to flow into the secondary airflow passage 16 through the second opening 18. Accordingly, in this configuration, air flows across the sensors 19 from the second opening 18 to the first opening 17 (i.e. opposite to that shown in FIG. 4A).

[0085]A further embodiment is illustrated in FIGS. 5A and 5B. In this embodiment, the flow director is a valve in the form of a door 24. This embodiment differs from those previously described in that the secondary airflow passage 16 includes a first branch 25 that extends to the second opening 18, and a second branch 26 that extends to a further opening 27, the further opening 27 being connected to the primary airflow passage 11 at a position upstream of the second opening 18. In the ambient configuration (FIG. 5A) the door 24 is controlled so as to obstruct the first branch 25 (and open the second branch 26). This causes air to be drawn from the secondary airflow passage 16 into the primary airflow passage 11 via the second branch 26, driven by the primary air mover 14. On the other hand, in the diagnostic configuration (FIG. 5B), the door 24 is controlled so as to obstruct the second branch 26 (and open the first branch 25). This causes air to flow into the secondary airflow passage 16 from the primary airflow passage 11 via the first branch 25. Accordingly, in the ambient configuration the air flowing over the sensors 19 is ambient air, and in the diagnostic configuration the air flowing over the sensors 19 is treated air.

[0086]FIGS. 6A and 6B depict a variation of the previously described embodiments. This variation differs in that the apparatus 10 includes a secondary airflow passage 16 that is open to the primary airflow passage 11 upstream of an air treatment device 15 (via a first opening 17) rather than the external environment. This variation is discussed in further detail below.

[0087]The apparatus 10 of this embodiment comprises a primary airflow passage 11 extending from an inlet 12 to an outlet 13. A primary air mover 14, in the form of a compressor, is provided in the primary airflow passage 11 to move air along the primary airflow passage 11 from the inlet 12 to the outlet 13. The air treatment device 15, which comprises a catalyst element is provided in the primary airflow passage 11 and is configured to treat air flowing along the primary airflow passage 11.

[0088]Also provided in the primary airflow passage 11 is a filter assembly 29 (which may comprise one or more of a HEPA filter, carbon filter and selective catalytic oxidisation (SCO) filter), which removes various components in the airflow upstream of the air treatment device 15.

[0089]The apparatus 10 further comprises a secondary airflow passage 16 that extends between the first opening 17 (open to the primary airflow passage 11 upstream of the air treatment device 15) and a second opening 18 open to the primary airflow passage 11 downstream of the air treatment device 15. One or more sensors 19 are provided in the secondary airflow passage 16 for sensing various characteristics of the air in the secondary airflow passage 16. The sensors 19 may include one or more gas sensors, particle sensors and/or environmental condition sensors.

[0090]The apparatus 10 also includes an airflow director 20 (in this case, a bi-directional fan) and a controller (not shown) configured to control the airflow director between a baseline configuration and a diagnostic configuration. In the baseline configuration, the airflow director 20 is controlled by the controller so as to direct airflow from the first opening 17 to the second opening 18 (such that air flowing across the one or more sensors 19 is untreated). In the diagnostic configuration the airflow director 20 is controlled by the controller so as to direct airflow from the second opening 18 to the first opening 17 so that air flowing across the one or more sensors 19 is air that has been treated by the air treatment device 15.

[0091]FIGS. 7A and 7B illustrate a further embodiment that is the same as that shown in FIGS. 6A and 6B, except that the air mover 14 is upstream of the first opening 17 and the airflow director 20 is a unidirectional fan (rather than bi-directional fan).

[0092]In this embodiment, in the baseline configuration (shown in FIG. 7A), the controller deactivates the airflow director 20 (i.e. the fan), which means air is pushed into and along the secondary airflow passage 16 by the air mover 14. Thus, in the baseline configuration, air flowing across the one or more sensors 19 is not treated by the air treatment device 15.

[0093]On the other hand, in the diagnostic configuration (FIG. 7B), the airflow director (fan) 20 is activated by the controller. The airflow director 20 is configured such that, when activated, moves airflow in the secondary passage 16 in a direction from the second opening 16 to the first opening 17. In this diagnostic configuration the air that flows over the one or more sensors 19 is air that has been treated by the air treatment device 15.

[0094]FIGS. 8A and 8B illustrate yet a further embodiment. In this embodiment, the secondary airflow passage 16 differs in that it includes a further opening 27 which opens to the primary airflow passage 11, downstream of the air treatment device 15 (and of the second opening 18). In this embodiment, both the first 17 and second 18 openings act as inlets into the secondary airflow passage 16 and the further opening 27 acts as an outlet (discharging air into the primary airflow passage 11). The airflow director is in the form of a door 24 which is moveable such that airflow enters the secondary airflow passage 16 either through the first opening 17 or through the second opening 18. In particular, the door 24 is moved so as to obstruct/open first 25 and second 26 branches of the secondary airflow passage 16 (which extend from the first 17 and second 18 openings respectively).

[0095]In the baseline configuration (FIG. 8A) the door 24 is controlled by the controller to move into a position in which the door 24 obstructs the second branch 26 of the secondary airflow passage 16. This prevents air from flowing into the secondary airflow passage 16 via the second opening 18 but allows air to flow into the secondary airflow passage 16 via the first opening 17. Thus, in this configuration, air is pushed into and along the secondary airflow passage 16 by the air mover 14 through the first opening 17 and passes across the one or more sensors 19. Accordingly, the air that is sensed in this configuration has not been treated by the air treatment device 15 (which is downstream of the first opening 17).

[0096]On the other hand, in the diagnostic configuration (FIG. 8B), the door 24 is moved by the controller to obstruct the first branch 25 of the secondary airflow passage 16. This prevents air from flowing into the secondary airflow passage 16 via the first opening 17, while allowing air to flow in via the second opening 18. Thus, in this configuration, air is pushed into and along the secondary airflow passage 16 by the air mover through the second opening 18 and passes across the one or more sensors 19. Accordingly, the air that is sensed in this configuration has been treated by the air treatment device 15 (which is upstream of the second opening 18).

[0097]The embodiment of FIGS. 9A and 9B is similar to that shown in FIGS. 5A and 5B in that the airflow director is in the form of a door 24. However, in this embodiment of the apparatus 10, a secondary air mover 30 (in the form of a fan) is provided in the secondary airflow passage 16. In this embodiment, both the first 17 and second 18 openings act as inlets and the secondary air mover 30 is arranged to draw airflow into the secondary airflow passage 16 through these openings.

[0098]In the baseline configuration (FIG. 9A), the door 24 is controlled to obstruct airflow received through the second opening 18 and allow airflow through the first opening 17. Thus, in this configuration the air that is sensed by the one or more sensors 19 has not been treated by the air treatment device 15, which is downstream of the first opening 17.

[0099]In the diagnostic configuration (FIG. 9B), the door 24 is controlled to obstruct airflow received through the first opening 17 and allow airflow through the second opening 18. Thus, in this configuration the air that is sensed by the one or more sensors 19 has been treated by the air treatment device 15, which is upstream of the second opening 18.

[0100]In both the baseline configuration and diagnostic configuration of this embodiment, the sensed air can then be discharged to the external environment or can be routed back to the primary airflow passage 11.

[0101]The exemplary embodiments set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

[0102]Although not illustrated, the air treatment apparatus may include a filter (e.g. in one or both of the primary and secondary airflow passages). The filter may be a particle filter, gas filter (or both).

[0103]Further, in the above-described embodiments, air is discharged through the first opening in the diagnostic configuration, but in other embodiments the air may be discharged through e.g. a third opening.

[0104]Likewise, in the embodiments described above, the air treatment device is provided downstream of the primary air mover. It should be appreciated, that the air treatment device may instead be upstream of the primary air mover.

[0105]The air treatment device may comprise one or more of an air purifier, heater, humidifier, de-humidifier, cooler. That is, one or more of these components may be provided in primary airflow passage 11. For example, an air purifier and a heater (e.g. downstream of the air purifier) may be provided in primary airflow passage 11.

[0106]For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations.

[0107]Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0108]Throughout this specification, including the claims which follow, unless the context requires otherwise, the word “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. It must be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about,” it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means for example +/−10%.