WO2024105630A1

WO2024105630A1 - Air extractor assembly

Info

Publication number: WO2024105630A1
Application number: PCT/IB2023/061643
Authority: WO
Inventors: Timothy Jukes; Jesal Patel; Rosanna WALLDOCK; Lucy RUIZ
Original assignee: Dyson Technology Limited
Priority date: 2022-11-18
Filing date: 2023-11-17
Publication date: 2024-05-23
Also published as: GB2625208A; GB202217293D0; GB2624441A

Abstract

An extractor assembly, comprising a jet unit and a suction unit. The jet unit comprises a jet outlet configured to emit a jet of air towards the suction unit. The jet unit is arranged such that, as the jet of air travels from the jet unit to the suction unit, the jet of air entrains ambient air from around at least a portion of a perimeter of the jet of air to create a combined airflow. The suction unit comprises a suction inlet through which the combined airflow is drawn into the suction unit, and a suction outlet through which the combined airflow is emitted from the suction unit.

Description

EXTRACTOR ASSEMBLY FIELD OF THE INVENTION The present invention relates to an extractor assembly, optionally comprising an air treatment unit. BACKGROUND OF THE INVENTION It can be desirable to treat the air in an environment. For example, to change a temperature or humidity of the air. It can also be desirable to extract suspended pollutants from the air, for example to remove unwanted particulates, chemicals, smells, or germs (e.g., organic matter). Conventional air treatment devices or extractors typically rely on high outlet flow rates to better mix treated air with untreated air within an environment. Accordingly, the untreated air is first spread around the environment before being treated or extracted. This can be disadvantageous when, for example, minimising the spread of the pollutants is important. SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided an extractor assembly comprising a jet unit and a suction unit. The jet unit comprises a jet outlet configured to emit a jet of air towards the suction unit. The jet unit is arranged such that, as the jet of air travels from the jet unit to the suction unit, the jet of air entrains ambient air from around at least a portion of a perimeter of the jet of air to create a combined airflow. The suction unit comprises a suction inlet through which the combined airflow is drawn into the suction unit, and a suction outlet through which the combined airflow is emitted from the suction unit. The term “extractor” is defined herein as a device which extracts air from an environment (e.g., a space or a room, optionally an internal/inside or enclosed space or room), and may expel the extracted air from the environment (e.g., to a different environment, such as to a different or external/outside or open space or room). The combined airflow emitted from the suction unit may be referred to herein as an “extracted airflow”. The extractor assembly may further comprise an air treatment unit for treating at least a portion of the combined airflow drawn into the suction inlet. The jet unit may be spaced apart from the suction unit. The jet unit may be at least partially adjacent to or at least partially adjoining the suction unit. The jet unit and the suction unit may be provided in separate housing units. Alternatively, the jet unit and the suction unit may be located in the same housing unit. In such embodiments, the housing unit may comprise both the suction inlet and the jet outlet. As such, the jet outlet and the suction inlet may be provided at substantially the same height from a common datum. For example, the jet outlet and the suction inlet may be fixed at a common height above a reference point. The reference point may be a surface (such as, a countertop) or at ground level (such as, a kitchen floor). According to a second aspect of the present invention there is provided an air treatment device comprising a jet unit and a suction unit spaced from the jet unit. The jet unit comprises a jet outlet through which a jet of air is emitted towards the suction unit and is arranged such that, as the jet of air travels from the jet unit to the suction unit, the jet of air entrains ambient air from around substantially all of a perimeter of the jet of air to create a combined airflow. The suction unit comprises a suction inlet through which the combined airflow is drawn into the suction unit, an air treatment unit for treating the at least a portion of the combined airflow, and a suction outlet through which treated airflow is emitted. The extractor assembly and/or air treatment device according to the first and/or second aspects of the present invention may be advantageous as the inventors of the present application have determined that providing a jet of air directed towards a suction unit can increase an amount of entrainment of ambient air into the jet of air to create a larger combined airflow, compared to providing only a suction unit. The extractor assembly and/or air treatment device according to the first and/or second aspects of the present invention may be advantageous as the inventors of the present application have determined that providing a jet of air directed towards a suction unit can increase a distance, relative to the suction unit, from which air can be drawn into the suction unit, compared to providing only a suction unit. That is, the extractor assembly and/or air treatment device may permit entrainment of ambient air that is both directly and/or not directly beneath the suction unit, and/or that is radially outward of or laterally distal to the extractor assembly and/or air treatment device. For example, the extractor assembly and/or air treatment device may permit entrainment of ambient air from a distance from the suction inlet that is at least two times greater than a maximum diameter of the suction unit. The extractor assembly and/or air treatment device according to the first and/or second aspects of the present invention may be advantageous as the inventors of the present application have determined that providing a jet of air directed towards a suction unit can reduce mixing of a suspended pollutant with the air in an environment in which the extractor assembly and/or air treatment device is operating, compared to providing only a recirculating suction unit. This may be important in settings in which contamination of airborne sources must be controlled, for example medical settings. The extractor assembly and/or air treatment device according to the first and/or second aspects of the present invention may be advantageous as the inventors of the present application have determined that providing a jet of air directed towards a suction unit can allow similar extraction and/or air treatment performance to be achieved with lower overall flow rates, compared to providing only a suction unit. This may reduce the energy expenditure, noise, size and/or cost of the extractor assembly and/or air treatment device to provide similar performance compared to providing only a suction unit. The extractor assembly and/or air treatment device according to the first and/or second aspects of the present invention may be advantageous as the inventors of the present application have determined that providing a jet of air directed towards a suction unit can allow improved extraction and/or air treatment performance to be achieved with similar overall flow rates, compared to providing only a suction unit. This may reduce the time taken by the extractor assembly and/or air treatment device to extract and/or treat the air within an environment in which the extractor assembly and/or air treatment device is operating compared to providing only a suction unit. The extractor assembly and/or air treatment device according to the first and/or second aspect of the present invention, respectively, may comprise any combination of the following features. The suction inlet may have a greater cross-sectional area than the jet outlet, for example five times greater or ten times greater. As the jet of air travels towards the suction inlet and entrains ambient air to form the combined airflow, the cross-sectional area of the combined airflow increases compared to the cross-sectional area of the jet of air at the jet outlet. Providing a greater cross-sectional area at the suction inlet compared to the jet outlet can allow a greater proportion of the combined airflow to be drawn through the suction inlet. The suction inlet may have a geometry sufficient to draw in all of the combined flow. For example, the suction inlet may have a greater equivalent diameter than the jet outlet. This may help to increase the efficiency and performance of the extractor assembly and/or air treatment device. A free jet of air tends towards a circular-shaped cross-section as it travels away from its source. However, a surface jet of air may be bounded along one side, such as by a wall. In embodiments, the jet outlet may be defined by a discrete aperture, and so the jet of air may tend towards a semi-circular shaped cross-section as it travels away from its source. In embodiments, the jet outlet may be defined by an elongate slot, and so the jet of air may tend towards a rectangular shaped cross-section as it travels away from its source. The suction inlet may have a cross-sectional area (or diameter or equivalent diameter) that is equal to or greater than the maximum cross-sectional area (or diameter or equivalent diameter) of the combined airflow at the suction inlet. The jet outlet may have a perimeter and a cross-sectional area, the cross-sectional area may have an equivalent diameter D and equivalent radius r, and a ratio of the perimeter to the cross-sectional area of the jet outlet may be at least D/2 mm^-1. In embodiments comprising a jet outlet defined by a discrete aperture, such as a smooth circular aperture, the ratio of the perimeter to the cross-sectional area of the jet outlet may be defined by at least 2/r or 4/D. This then has the benefit that, for a given cross-sectional area, the jet outlet has a relatively long perimeter. Consequently, the jet of air emitted from the outlet has a relatively large surface area which better encourages entrainment. The jet outlet may be substantially circular or annular in shape. Alternatively, the jet outlet may be non-circular in shape. An increased perimeter of the jet outlet is associated with an increase in an amount of entrainment of ambient air by the jet of air. Accordingly, a non-circular jet outlet may increase the efficiency and performance of the extractor assembly and/or air treatment device. For example, the jet outlet may be oval, triangular, rectangular, cross-shaped, or star-shaped. The jet of air may be emitted from the jet outlet at a first flow rate, and the combined airflow may be drawn into the suction inlet at a second, greater flow rate. Drawing the combined airflow through the suction inlet at a greater flow rate than a flow rate at which air is emitted from the jet outlet can allow a greater proportion of the combined airflow to be drawn through the suction inlet. A flow rate of air at the suction inlet may be equal to or greater than a flow rate of the combined airflow. This may help to ensure that substantially all of the combined airflow is drawn through the suction inlet. The suction unit may emit the combined airflow drawn into the suction unit, or a portion thereof, into an exhaust duct arranged to expel the combined airflow, or a portion thereof, from the environment. The jet outlet and the suction inlet may be co-axially arranged. That is, the centrelines of the jet outlet and the suction inlet are aligned. This may help to increase an amount of ambient air that is entrained by the jet of air and ultimately drawn into the suction unit to be extracted and/or treated by the extractor assembly and/or air treatment unit, respectively. The centrelines of the jet outlet and the suction inlet may be radially or laterally offset (e.g., they may be parallelly unaligned). The centrelines of the jet outlet and the suction inlet may be angularly offset (e.g., they may be angularly unaligned, or arranged at an angle to each other). The centrelines of the jet outlet and the suction inlet may be both radially/laterally offset and angularly offset (e.g., they may be both parallelly and angularly unaligned). The jet outlet may be arranged such that the emitted jet of air is substantially perpendicular to the plane of the suction inlet (e.g., parallel to the centreline of the suction inlet). Additionally, or alternatively, the jet outlet may be arranged such that the emitted jet of air is substantially parallel to the plane of the suction inlet (e.g., perpendicular to the centreline of the suction inlet). In some examples, the jet outlet may be arranged such that the emitted jet of air has a component parallel to the centreline of the suction inlet, and a component perpendicular to the centreline of the suction inlet. Depending on the orientation of the jet outlet relative to the suction inlet, the parallel and/or perpendicular component may be more dominant. The jet unit may comprise a first airflow generator for generating the jet of air. This may provide a more compact jet unit compared to providing a separate airflow generator. The suction unit may comprise a second airflow generator for drawing the combined airflow into the suction unit. This may provide a more compact suction unit compared to providing a separate airflow generator. The extractor assembly may further comprise an exhaust duct. The exhaust duct may be coupled to or otherwise aligned with the suction outlet. The exhaust duct may be arranged such that the combined airflow drawn through the suction inlet, or a portion thereof, is received by the exhaust duct via the suction outlet. The exhaust duct may additionally be arranged to expel the combined airflow, or part thereof, from the environment. The suction unit may comprise an airflow generator for drawing the combined airflow into the suction unit. The suction unit may comprise an airflow generator for drawing at least a portion of the combined airflow into the suction unit. The extractor assembly may further comprise a return duct arranged to return, to the jet unit, at least part of the combined airflow drawn through the suction inlet. The air treatment device may comprise a return duct arranged to return, to the jet unit, at least part of the combined airflow drawn through the suction inlet. The jet unit may emit the airflow returned by the return duct as at least part of the jet of air. This may provide a more efficient and compact extractor assembly and/or air treatment device compared to an extractor assembly and/or air treatment device comprising an airflow generator in each of the jet and suction units. The jet unit may comprise a jet inlet through which ambient air is drawn, said ambient air subsequently forming at least part of the jet of air. This may increase the distance, relative to the suction unit, from which ambient air is ultimately drawn into the suction unit and extracted and/or treated, compared to airflow returned by the return duct forming all of the jet of air. The jet unit may comprise at least one jet outlet. The jet unit may comprise a plurality of jet outlets. Each jet outlet may be configured to emit a jet of air towards the suction unit. The plurality of jet outlets may be arranged on at least one surface, such as on two surfaces which may be orthogonal. The plurality of jet outlets may be arranged such that a number of the jets of air emitted interfere with each other to create a reinforced jet of air. The reinforced jet of air may entrain ambient air from around at least a portion of a perimeter of the reinforced jet of air to create the combined airflow. In examples, a number of the plurality of jet outlets may be defined by elongate slots. Each slot may extend across the at least one surface. Each elongate jet outlet may be arranged substantially in parallel with an adjacent elongate jet outlet. In some examples, a number of the plurality of jet outlets may be defined by discrete apertures. The jet outlets may be arranged in substantially parallel rows and/or substantially parallel columns (e.g., in a regular array). In embodiments, a first row/column of jet outlets may be offset or staggered relative to a second, adjacent row/column. In other examples, the plurality of jet outlets may be defined by a combination of elongate slots and discrete apertures arranged across the at least one surface. The reinforced jet of air may entrain ambient air from around at least a portion of a perimeter of the reinforced jet of air to create a combined airflow. In examples, the suction unit may comprise at least one suction inlet, optionally a plurality of suction inlets. The or each surface may be one of flat, curved, convex, concave, S-shaped, U-shaped, L- shaped, semi-cylindrical and cylindrical. In examples, each, some, or all, of the plurality of jet outlets may be one of oval, triangular, rectangular, cross-shaped, or star-shaped. The jet unit may comprise a thermal unit arranged to heat and/or cool the jet of air relative to the ambient air. Depending on the relative positions of the jet and suction units, providing a jet of air that is hotter or cooler than the ambient air can increase an amount of entrainment of the ambient air as the jet of air travels from the jet outlet towards the suction inlet, compared to a jet of air at ambient temperature. By way of example, the thermal unit may employ an electric heater, a Peltier device, or a vapour-compression cycle. The jet unit may comprise one or more guides, such as one or more vanes or a fan, arranged to cause, in use, the jet of air to travel between the jet outlet and the suction inlet in a non- linear motion. This may help to increase an amount of entrainment of the ambient air as the jet of air travels from the jet outlet towards the suction inlet, compared to a jet of air travelling in a linear motion. A separation distance between the jet outlet and the suction inlet may be at least 200mm. Providing a separation distance of at least 200mm can help to increase an amount of entrainment of the ambient air as the jet of air travels from the jet outlet towards the suction inlet, compared to lesser separation distances. The extractor assembly and/or air treatment unit may comprise one or more of a thermal unit, a humidifier, a dehumidifier, a filter, and an ioniser to treat the combined airflow, or a portion thereof, drawn into the suction outlet via the suction unit. Accordingly, an extractor assembly and/or air treatment device according to the invention may be suitable for a plurality of air treatment processes. The suction unit may treat the combined airflow, and emit the treated airflow, or a portion thereof, back into the environment in which the air treatment device is located. Additionally, or alternatively, the suction unit may emit the treated airflow, or a portion thereof, into an exhaust duct arranged to expel the treated airflow from the environment. The air treatment device may comprise a detector arranged to detect a parameter of the ambient air. The air treatment device may comprise a controller connected to the detector and arranged to cause the jet of air to be directed towards the suction inlet in response to the detector indicating that a predetermined treatment criterion is met. This may help to increase the efficiency of the air treatment device. The detector may be arranged to detect a pollutant, air temperature and/or air humidity. For example, the detector may comprise a pollutant detector and the controller may be configured to cause the jet unit to emit an oscillating jet of air in the event that no pollutant is detected by the detector, and to cause the jet unit to direct the jet of towards the suction unit in the event that a pollutant is detected by the detector and until the pollutant is removed from the air. In another example, the air treatment device may be arranged to be inactive until the predetermined treatment criterion is met. The predetermined treatment criterion may be that a pollutant concentration, air temperature and/or air humidity percentage meets or exceeds a threshold level. The air treatment device may comprise a pollutant detector and a controller connected to the pollutant detector. The controller may be arranged to cause the jet of air to be directed towards the suction inlet in response to the pollutant detector detecting a pollutant. The air treatment device may comprise a user interface operable by a user to select one or more operating parameters of the device. This may allow the air treatment device to be operable as required by the user. The air treatment device may comprise at least one additional jet unit arranged to emit an (or at least one) additional jet of air towards the suction unit. The (or the at least one) additional jet of air entrains ambient air to create an additional combined airflow, and the suction inlet is arranged to draw at least a portion of each of the combined airflow and the additional combined airflow into the suction unit. Such an arrangement may increase an amount of entrainment of the ambient air as the jet of air travels from the jet outlet towards the suction inlet, compared to employing a single jet unit. Such an arrangement may increase the distance, relative to the suction inlet, from which ambient air is ultimately drawn into the suction unit via the suction inlet, which may increase the performance of the air treatment device. The suction inlet may have a geometry sufficient to draw in all of the combined airflow and the further combined airflow. This may help to increase the efficiency and performance of the air treatment device. The jet unit and the further jet unit may be inclined towards one another such that the combined airflow and further combined airflow cross paths as the combined airflows travel towards the suction inlet. This may decrease the sum of the cross-sectional areas of both combined airflows so that a smaller suction inlet is required to draw in both combined airflows compared to an example in which the combined airflow and the further combined airflow do not cross paths. The suction unit may take the form of an extractor hood. The suction unit may be arranged above one or more pollutant sources, for example, at least two pollutant sources. The jet outlet may be positioned at a side of the one or more pollutant sources. In embodiments, two or more pollutant sources may be arranged in an array. The two or more pollutant sources may be arranged symmetrically around the jet outlet. The jet outlet may be positioned substantially at a centre or a midpoint of the two or more pollutant sources. The jet unit and the suction unit may be located in the same housing unit. The housing unit may comprise the suction inlet and the jet outlet, such that the suction inlet and the jet outlet may be arranged at substantially the same height. As such, the jet outlet may also be arranged above the one or more pollutant sources. According to a third aspect of the present invention there is provided an extractor comprising an array of pollutant sources, an extractor hood arranged above the array and comprising a suction inlet, and a jet generator comprising a jet outlet, the jet outlet positioned substantially at a centre of the array and arranged to direct a jet of air towards the suction inlet. As the jet of air travels from the jet unit to the suction unit, the jet of air entrains ambient air from around substantially all of a perimeter of the jet of air to create a combined airflow, and the suction inlet is arranged to draw the combined airflow into the extractor hood. The extractor may, for example, be a kitchen extractor and the array of pollutant sources may comprise an array of cooking hobs. The extractor hood may comprise an air treatment unit as described with reference to the second aspect and an exhaust for emitting the combined airflow drawn into the extractor hood by the suction inlet. Optional features of aspects of the present invention may be equally applied to other aspects of the present invention, where appropriate. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view illustrating an air treatment device according to aspects and embodiments of the present invention; Figure 2 is a schematic cross-section view illustrating the air treatment device according to Figure 1; Figure 3 is a graph plotting average pollution concentration against time for a traditional air treatment device and an air treatment device according to aspects and embodiments of the present invention; Figure 4 is a schematic view illustrating an air treatment device according to aspects and embodiments of the present invention; Figure 5 is a schematic view illustrating an air treatment device according to aspects and embodiments of the present invention; Figure 6 is schematic view illustrating an extractor device according to aspects and embodiments of the present invention; Figure 7 is a schematic top view of a portion of the extractor device of Figure 6; Figure 8 is a schematic side view of an extraction assembly according to further aspects and embodiments of the present invention; and, Figure 9 is a schematic front view illustrating an extraction assembly according to further aspects and embodiments of the present invention. DETAILED DESCRIPTION OF THE INVENTION There will now be described air treatment devices for drawing in air from an environment in which the air treatment device is located and treating the air that is drawn in. The air treatment devices may be arranged to provide any suitable form of air treatment(s) in use, for example filtration, heating, cooling, purification, humidification, dehumidification, and ionisation. Figures 1 and 2 show a first example of an air treatment device 100. Figure 2 is a schematic cross-sectional view of the air treatment device 100 of Figure 1. The air treatment device 100 comprises a jet unit 110 and a suction unit 120 spaced apart from the jet unit 110 by approximately 1.5m. It will be appreciated that in other examples, the jet unit 110 and suction unit 120 may be at any other suitable distance apart. The jet unit 110 comprises a first airflow generator 116 for generating a jet of air 102. In this example the first airflow generator 116 comprises a rotating fan blade, but it will be appreciated that any other suitable airflow generator may be employed. The jet unit 110 comprises a jet inlet 114 through which air is drawn into the jet unit 110 when the first airflow generator 116 is in use. In this example, ambient air 104 from the environment is drawn into the jet unit 110 via the jet inlet 114. The jet inlet 114 comprises a plurality of apertures in an outer surface of the jet unit 110 and is fluidly connected to a jet outlet 112 of the jet unit 110, through which the jet of air 102 generated by the first airflow generator 116 is emitted towards the suction unit 120. The jet outlet 112 is substantially cross-shaped, but it will be appreciated that any other suitable shape may be employed. As noted below, the jet of air 102 emitted from the jet outlet 112 entrains ambient air from the surrounding environment. A benefit of using a cross-shaped jet outlet 112 is that, for a given cross-sectional area, the outlet 112 has a relatively long perimeter. Consequently, the jet of air 102 emitted from the outlet 112 has a relatively large surface area which better encourages entrainment. Accordingly, whilst the jet outlet 112 may have alternative shapes, there are potential benefits in having a jet outlet 112 for which the ratio of the perimeter to the cross-sectional area of the jet outlet 112 is relatively high. The jet unit 110 is arranged such that, as the jet of air 102 travels from the jet unit 110 to the suction unit 120, the jet of air 102 entrains ambient air 104 from the environment to create a combined airflow 106. As such, a cross-sectional area of the jet of air 102 increases as the combined airflow 106 is formed between the jet outlet 112 and the suction inlet 122. The jet of air 102 is emitted from the jet outlet 112 at a first flow rate, Q_J, and the combined airflow 106 reaches the suction inlet 122 at a second, greater flow rate, Q_C, due to the entrainment of the ambient air 104. Altering the first flow Q_J rate can alter an amount of entrainment of the ambient air 104 such that a ratio between the first and second flow rates Q_J, Q_C can be changed by changing the operating characteristics of the jet unit 110. The jet of air 102 entrains the ambient air 104 from around substantially all of a perimeter of the jet of air 102. That is, no physical barriers are positioned between the jet unit 110 and the suction unit 120 that might impede entrainment by the jet of air 102 of ambient air 104 that is radially outward of the jet of air. Accordingly, ambient air comprising pollutants emitted from a pollutant source located remotely from the air treatment device 100 is drawn towards the air treatment device 100 by the jet of air 102 and into the suction unit 120. The suction unit 120 comprises a second airflow generator 132 for drawing the combined airflow 106 into the suction unit 120. In this example, the second airflow generator 132 comprises a rotating fan blade, but it will be appreciated that any other suitable airflow generator may be employed. The first and second airflow generators 116, 132 may be communicably connected such that a change in a flow rate generated by the first airflow generator 116 causes a corresponding change in a flow rate generated by the second airflow generator 132. This may help to ensure that substantially all of the combined airflow 106 is drawn into the suction unit 120. The suction unit 120 comprises a suction inlet 122 through which the combined airflow 106 is drawn into the suction unit 120 when the second airflow generator 132 is in use. The suction inlet 122 and the jet outlet 112 are co-axially arranged along a longitudinal axis 10 of the air treatment device 100. The suction outlet 122 has a greater cross-sectional area than a cross-sectional area of the jet outlet 112 and a greater equivalent diameter than the jet outlet 112. In this example, the suction outlet 122 is at least five times greater in cross-sectional area than the jet outlet 112. The suction inlet 122 has a greater cross-sectional area than a cross-sectional area of the combined airflow 106 such that substantially all of the combined airflow 106 is drawn into the suction unit 120 via the suction inlet 122. The suction inlet 122 comprises a plurality of apertures formed in an inlet surface 124 and the combined airflow 106 is drawn through the plurality of apertures. It will be appreciated that in other examples, the suction inlet 122 may take any other suitable form, for example a single aperture. Air is drawn into the suction unit 120 by the second airflow generator 132 at a third flow rate, Q_S. In this example, the third flow rate Q_S is equal to or greater than the second flow rate Q_C corresponding to a flow rate of the combined airflow 106 at the suction inlet 122. This may help to ensure that substantially all of the combined airflow 106 is drawn into the suction unit 120. The suction unit 120 comprises an air treatment unit 126, which in this example comprises a HEPA filter 127. It will be appreciated that in other examples, any other suitable filter or combination of filters may be employed. It will be appreciated that in other examples, the air treatment unit 126 may comprise any other suitable form of air treatment unit for treating the air drawn into the suction unit 120. The filter 127 is arranged within the suction unit 120 such that substantially all of the combined airflow 106 drawn into the suction unit 120 passes through the filter 127 to remove particulates from the combined airflow 106 and generate a treated airflow 108. The suction unit 110 comprises a suction outlet 128 through which the treated airflow 108 is emitted from the suction unit 110. The suction outlet 128 may emit the treated airflow 108 in any direction other than a direction that opposes either the jet of air 102 or the flow of ambient air 104 towards the jet of air 102. The suction outlet 128 comprises a plurality of apertures formed in an outlet surface 130 and the treated airflow 108 is emitted through the plurality of apertures. It will be appreciated that in other examples, the suction outlet 128 may take any other suitable form, for example a single aperture. The suction outlet 128 is located on an upper surface of the suction unit 110. It will be appreciated that in other examples, the suction outlet 128 may be formed in more than one surface of the suction unit, for example on a plurality of side surfaces of the suction unit 110, which may ensure even distribution of the treated airflow 108 around the environment. In this example, the treated airflow 108 is emitted back into the environment in which the air treatment device 100 is located. In other examples, the treated airflow 108 may be emitted into an exhaust duct arranged to expel the treated air from the environment. The treated airflow 108 is emitted from the suction outlet 128 at a fourth flow rate, Q_T. In this example the fourth flow rate Q_T is substantially equal to the third flow rate Q_S, corresponding to a flow rate at which air is drawn into the suction unit 120 by the second airflow generator 132. The jet unit 110 comprises a thermal unit 118 arranged to heat and cool the jet of air 102 relative to the ambient air. The thermal unit 118 is arranged upstream of the first airflow generator 116, but in other examples could be positioned downstream of the first airflow generator 116. The thermal unit 118 comprises a temperature sensor (not shown) arranged to determine a temperature of the ambient air and to heat or cool the jet of air 102 in order to alter an amount of entrainment of the ambient air 104 by the jet of air 102. It will be appreciated that in other examples, the thermal unit 118 may be omitted. The jet unit 110 comprises a plurality of vanes (not shown) positioned adjacent to the jet outlet 112 and arranged to cause, in use, the jet of air 102 to travel between the jet outlet 112 and the suction inlet 122 in a swirling motion. It will be appreciated that in other examples, other forms of guide may be employed to cause the jet of air to travel between the jet outlet 112 and the suction inlet 122 in a non-linear motion. By moving in a non- linear motion (e.g., swirling), the jet of air 102 may entrain a greater amount of ambient air as the jet of air 102 travels between the jet outlet 112 and the suction inlet 122. The air treatment device 100 comprises a pollutant detector 140 and a controller (not shown) connected to the pollutant detector 140. The pollutant detector 140 is arranged to detect one or more pollutants in the environment and to send a signal indicative of whether the one or more pollutants are detected to the controller. The controller is arranged to cause the jet of air 102 to be directed towards the suction inlet 122 in response to the signal being indicative that one or more of the pollutants have been detected. It will be appreciated that in other examples, for example in which the air treatment device 100 is for providing other air treatment to the air, any other suitable type of detector may be employed. For example, the air treatment device 100 may comprise a dehumidifier and a humidity detector, and the controller may be arranged to cause the jet of air 102 to be directed towards the suction inlet 122 if a humidity of the environment is detected to be above a threshold humidity. In this example, the pollutant detector 140 is located on the jet unit 110, but it will be appreciated that the pollutant detector 140 may alternatively be located on the suction unit 120. The air treatment device 100 comprises a user interface 150 operable by a user to operate the air treatment device 100. The user interface 150 may comprise one or more of a button, switch, toggle, knob, touch screen or wireless communication module for communicating with a smart device. The user interface 150 may enable a user to turn the air treatment device 100 on or off and/or to adjust one or more operating parameters of the air treatment device 100, for example an amount of heating or cooling of the jet of air 102 by the thermal unit 118 or a flow rate of the first and/or second airflow generators 116, 132. In this example, the user interface 150 is located on the jet unit 110, but it will be appreciated that the user interface 150 may alternatively be located on the suction unit 210. Figure 3 is a graph depicting the performance of an air treatment device according to aspects and embodiments of the present invention (solid line, 156), in this case an air purifier, against a traditional air purifier (dashed line, 158) for corresponding flow rates. In this demonstration, the flow rate of the traditional air purifier was 60l/s and the flow rate at the suction inlet, Q_S, was also 60l/s. Figure 3 shows that the reduction in the average pollution concentration of the traditional air purifier rate follows a substantially exponential decay. Conversely, the rate of reduction in the average pollution concentration of the air treatment device according to aspects and embodiments of the present invention is significantly greater, particularly in the first 5 -10 minutes (T = 300s to T = 600s), and more particularly around T = 500s, as highlighted by reference 160. The graph can be explained by the increased amount of ambient air that is drawn towards the jet of air and into the suction unit. Figure 4 shows a further example of an air treatment device 200 according to aspects and embodiments of the present invention. The air treatment device 200 is substantially similar to the air treatment device 100 depicted in Figures 1 and 2 and described above. Like components have the same reference number, but increased by 100, and will not be described again for brevity. Any features described with reference to the air treatment device 100 may be equally applicable to the air treatment device 200. The air treatment device 200 comprises a return duct 260 for permitting airflow to pass from the suction unit 220 to the jet unit 210. The return duct 260 may comprise a non- return valve (not shown) to prevent airflow from passing in an opposite direction. In this example, the return duct 260 is positioned to a side of the suction unit 220 and the jet unit 210. In some examples, the return duct 260 adjoins a centre of the suction inlet 222 with a centre of the jet outlet 212, such that the return duct 260 is substantially coaxial with the longitudinal axis 20 of the air treatment device 200. This can help to provide a more compact arrangement without substantially inhibiting an amount of entrainment by the jet of air 202, since the outer perimeter of the jet of air 202 is not affected by the presence of the return duct 260 and the return duct does not impede ambient air 204 as it is drawn towards the jet of air 202. In this example, the suction unit 220 comprises an airflow generator and the jet unit 210 does not. In use, a proportion of the combined airflow 206 that is drawn into the suction unit 220 is exhausted from the suction unit 220 via the return duct 260 to form a return airflow. The return airflow forms the jet of air 202 that is emitted from the jet outlet 210. It will be appreciated that in other examples, the jet unit 210 may also comprise an airflow generator and the return airflow may form a portion of the jet of air 202. The return airflow has a flow rate, Q_R, which in this example is substantially equal to the first flow rate Q_J, corresponding to the flow rate at the jet outlet 212. In this example, the fourth flow rate Q_T, corresponding to the flow rate at the suction outlet 228, is less than the third flow rate Q_S, corresponding to the flow rate at the suction inlet 222. That is, Q_{T =} Q_S – Q_R The return duct 260 is positioned downstream of the air treatment unit (not shown) such that a portion of the treated airflow 208 is returned to the jet unit 210. Figure 5 shows another example of an air treatment device 300 according to aspects and embodiments of the present invention. The air treatment device 300 is substantially similar to the air treatment device 100 depicted in Figures 1 and 2 and described above. Like components have the same reference number, but increased by 200, and will not be described again for brevity. Any features described with reference to the air treatment devices 100, 200 may be equally applicable to the air treatment device 300. The air treatment device 300 comprises two jet units 310a, 310b each arranged to emit a jet of air 302a, 302b. The suction unit 320 is arranged to draw in the combined airflows 306a, 306b of each jet unit 310a, 310b. The flow rate Q_C of both of the combined airflows 306a, 306b is greater than a flow rate of the combined airflow of the air treatment devices 100, 200 described above, even when the combined flow rate (Q_Ja + Q_Jb) at the jet units 310a, 310b is substantially equal to the flow rate Q_J at the jet unit 110, 210, because providing two jets of air 302a, 302b causes a greater amount of entrainment of ambient air 304 compared to providing a single jet of air 102, 202. The jet units 310a, 310b are inclined towards one another such that the combined airflows 306a, 306b substantially entirely cross paths at the combined airflows 306a, 306b travel towards the suction unit 320. It will be appreciated that in other examples, the jet units 310a, 310b may be arranged to emit substantially parallel jets of air 302a, 302b that do not or only partially cross paths, and the suction unit 320 may be arranged such that the suction inlet 322 is of sufficient equivalent diameter to draw in substantially all of both combined airflows 306a, 306b. In embodiments, the combined airflows 306a, 306b may be treated by an air treatment unit (not shown) after being drawn in through the suction inlet 322, resulting in a treated airflow 308. The treated airflow 308, or a portion thereof, may be expelled from the suction outlet 328 at a rate Q_T. Figures 6 and 7 show an extractor 400 according to aspects and embodiments of the present invention. The extractor 400 is substantially similar to the air treatment device 100 depicted in Figures 1 and 2 and described above. Like components have the same reference number, but increased by 300, and will not be described again for brevity. Any features described with reference to the air treatment devices 100, 200, 300 may be equally applicable to the extractor 400. The extractor 400 comprises a suction unit 420 in the form of an extractor hood. The extractor hood 420 is arranged above an array of pollutant sources 480. The extractor hood 420 comprises a suction inlet 422 defined in a lower surface of the extractor hood 420. In this example, the array of pollutant sources 480 is an arrangement of four gas rings on a cooking hob. In the example shown in Figures 6 and 7, two of the gas rings are in use and are supporting and heating respective saucepans 482. The saucepans 482 are emitting unwanted heat, smells, and particulates. It will be appreciated that in other examples, there may be a greater or lesser number of pollutant sources in the array 480. The extractor 400 comprises a jet unit 410 comprising a jet outlet 412. The jet outlet is positioned at the centre of the array 480 and arranged to direct a jet of air 402 towards the suction inlet 422. As the jet of air 402 travels from the jet unit 410 to the suction unit 420, ambient air 404 is entrained from around substantially all of a perimeter of the jet of air 402 to create a combined airflow 406. The combined airflow 406 comprises the entrained unwanted heat, smells and particulates emitted from the saucepans 482. The jet outlet 412 is in the shape of a cross. As noted above, this increases the perimeter of the jet outlet 412 compared to, say, a circular outlet having the same cross-sectional area, which can help to increase an amount of entrainment of ambient air. It will be appreciated that any other suitable shape may be employed in other examples. There will now be described extractor assemblies 500, 600 for drawing in air from an environment in which the extractor assemblies are located, and extracting the air that is drawn in (e.g., expelling the extracted air from the environment). Figure 8 shows an extractor assembly 500 according to aspects and embodiments of the present invention. Like components have the same reference number, but increased by 400 (i.e., they are now preceded by a “5”). Any features described with reference to the air treatment devices 100, 200, 300 and extractor 400 may be equally applicable to the extractor assembly 500. The extractor assembly 500 comprises a jet unit 510 and a suction unit 520 located adjacent to and partially adjoining the jet unit 510. The suction unit 520 takes the form of an extractor hood or cooker hood arranged above a pollutant source 580. The suction unit 520 comprises a suction inlet 522 defined in a lower surface of the suction unit 520, and a suction outlet 528 located on an upper surface of the suction unit 520. In this example, the pollutant source 580 is provided by an arrangement of heating units on a cooker hob (for example, gas burners or electric rings). Two of such heating units are shown in use heating saucepans 582. In use, the saucepans 582 will emit unwanted heat, moisture, and smells. The jet unit 510 comprises a jet Inlet 514 and a plurality of jet outlets 512a, 512b, 512c. The plurality of jet outlets 512a, b, c may be defined by elongate slots or discrete apertures or a combination of both. In this example, ambient air 504 from the environment is drawn into the jet unit 510 via the jet inlet 514 at a flow rate Q_IN. The jet inlet 514 is fluidly connected to the plurality of jet outlets 512a, b, c, through which jets of air are emitted towards the suction unit 520. In this example, the jet unit 510 extends orthogonally to the suction unit 520. The jet unit 510 may take the form of, or comprise a, back-board or panel, which may be mounted on a wall or other surface located at a side of the cooker hob, typically behind the heating units. In this example, the back panel comprises the plurality of jet outlets 512a, b, c. The plurality of jet outlets 512a, b, c are arranged on a surface of the back-panel such that the jets of air emitted interfere with each other to create a reinforced jet of air 502. The jet unit 510 is arranged such that, as the reinforced jet of air 502 travels from the jet unit 510 to the suction unit 520, the reinforced jet of air 502 entrains ambient air 504 from the environment to create a combined airflow 506. The back panel provides a physical barrier which impedes entrainment of ambient air 504 on one half of the reinforced jet of air 502, such that the reinforced jet of air 502 only entrains the ambient air 504 from around a portion of a perimeter of the reinforced jet of air 502. A cross-sectional area of the reinforced jet of air 502 increases as the combined airflow 506 is formed between the jet outlet 512 and the suction inlet 522. Where each jet outlet 512a, b, c is defined by a discrete aperture, the cross-sectional area of the reinforced jet of air 502 tends towards a semi-circular-shaped cross-section as it travels away from its source. Where each jet outlet 512a, b, c is defined by an elongate slot, the cross-sectional area of the reinforced jet 502 tends towards a rectangular shape as it travels away from its source. In this example, the centreline through the suction inlet 522 and the centreline through each jet outlet 512a, b, c is radially offset (e.g., they are not parallelly aligned). Furthermore, the centrelines through each of the suction inlet 522 and each jet outlet 512a, b, c are angularly offset (e.g., they are not angularly aligned). The plane of each jet outlet 512a, b, c is therefore at an angle relative to the plane of the suction inlet 522. Therefore, each emitted jet of air has a component parallel to the centreline of the suction inlet 522 and a component perpendicular to the centreline of the suction inlet 522. The parallel component is more dominant in this example, such that each jet of air is directed towards the suction inlet 522 (and therefore the reinforced jet of air 502 and the combined airflow 506 is also directed towards the suction inlet 522). The reinforced jet of air 502 is emitted from jet outlet 512a at a flow rate Q_J1, from jet outlet 512b at a flow rate Q_J2, and from jet outlet 512c at a flow rate Q_J3. The rate of entrainment of the ambient air 504 is Q_EN. The combined airflow 506 then reaches the suction inlet 522 at a second, greater flow rate, Q_C, wherein Q_C = Q_J1 + Q_J2 + Q_J3 + Q_EN. Altering the flow rates Q_J1, Q_J2, and Q_J3 can alter the rate of entrainment Q_EN and therefore the amount of ambient air 504 entrained. As such, a ratio between the flow rates Q_J1, Q_J2, and Q_J3 and flow rate Q_C can be changed by changing the operating characteristics of the jet unit 510. The ambient air 504 adjacent to a boundary defining the combined airflow 506 will experience the strongest entrainment. A dividing streamline 505 depicts a boundary after which the ambient air 504 experiences no or negligible entrainment. Between these two boundaries, the ambient air 504 will experience diminishing entrainment as the distance from the jet unit 510 increases. The induced air flow, Q_IND, describes the ambient air 504 which is induced towards the jet outlets 512a, b, c, but is extracted by the suction inlet 522 before entrainment can occur. This is referred to herein as induced airflow 507. After the combined airflow 506 is drawn into the suction unit 520, it may be referred to as an exhaust airflow 508. The exhaust airflow 508 may be defined by flow rate Q_EX = Q_C + Q_IND. The suction inlet 522 is arranged to draw the at least a portion of the combined airflow 506 and at least a portion of the induced airflow 507 into the suction unit 520. In particular, the suction inlet 522 has a greater cross-sectional area than a cross-sectional area of the combined airflow 506 such that substantially all of the combined airflow 506 is drawn into the suction unit 520 via the suction inlet 522, along with at least a portion of the induced airflow 507. The exhaust airflow 508 is emitted from the suction unit 510 through suction outlet 528. In this example, the exhaust airflow 508 is emitted into an exhaust duct 529 coupled to the suction outlet 528. The exhaust duct 529 is arranged to receive the exhaust airflow 508 (or part thereof) and expel the exhaust airflow 508 from the environment (e.g., by venting the exhaust airflow 508 to an outside area). In a similar manner, Figure 9 shows an extractor assembly 600 according to aspects and embodiments of the present invention. Like components have the same reference number, but increased by 500 (i.e., they are now preceded by a “6”). Like components are assumed to be structurally and functionally similar to those described with regard to Figure 5, except where indicated otherwise. Any features described with reference to the air treatment devices 100, 200, 300, extractor 400, and extractor assembly 500, may be equally applicable to the extractor assembly 600. The extractor assembly 600 comprises a jet unit 610 and a suction unit 620 located within the same housing structure. The suction unit 620 takes the form of an extractor hood arranged above a pollutant source 680, and comprises a suction inlet 622 defined in a lower surface of the suction unit 620.and a suction outlet 628 located on an upper surface of the suction unit 620. The jet unit 610 comprises a jet inlet 614 and a plurality of jet outlets 612a, 612b, 612c, 612d. The plurality of jet outlets 612a, b, c, d may be defined by either elongate slots or discrete apertures or a combination of both. The jet outlets 612a, b, c, d and the suction inlet 622 are provided at substantially the same height from a common datum 609 (in this case, the common datum 609 is defined by the cooker hob). The plurality of jet outlets 612a, b, c, d are arranged on the lower surface of the suction unit 620 and arranged such that the jets of air emitted interfere with each other to create reinforced jets of air 602a and 602b. Ambient air 604 from the environment is drawn into the jet unit 610 via the jet inlet 614 at a flow rate Q_IN. The jet inlet 614 is fluidly connected to the plurality of jet outlets 612a, b, c, d through which jets of air are emitted towards the suction unit 620. As the reinforced jets of air 602a, b travel from the jet outlets 612a, b, c, d to the suction inlet 622, they entrain ambient air 604 from the environment to create combined airflows 606a and 606b, respectively. The lower surface of the suction unit 620 provides a physical barrier which impedes entrainment of ambient air 604, such that ambient air 604 is only entrained around a portion of a perimeter of the reinforced jets of air 602a, b. In examples where the jet outlets 612a, b, c, d are discrete apertures, the reinforced jets of air 602a, b each tend towards a semi-circular-shaped cross-section of increasing diameter as they travel away from their respective sources. However, in examples where the jet outlets 612a, b, c, d are elongate slots, the reinforced jets of air 602a, b each tend towards a rectangular shaped cross-section of increasing cross-sectional area (or increasing length and/or height) as they travel away from their respective sources. In this example, a centreline through the suction inlet 622 and a centreline through any of the jet outlets 612a, b, c, d are relatively radially and angularly offset. Therefore, each emitted jet of air has a component parallel to the centreline of the suction inlet 622 and a component perpendicular to the centreline of the suction inlet 622. The perpendicular component is more dominant in this example, such that each jet of air is directed towards the suction inlet 622 (and therefore the reinforced jets of air 602a, b and the combined airflows 606a, b are also directed towards the suction inlet 622). A jet of air is emitted from jet outlet 612a at a flow rate Q_J1, from jet outlet 612b at a flow rate Q_J2, from jet outlet 612c at a flow rate Q_J3, and from jet outlet 612d at a flow rate Q_J4. The rate of entrainment of the ambient air 604 is represented by Q_EN1 and Q_EN2. In some examples, Q_J1+ Q_J2 + Q_EN1 = Q_C1, and Q_J3+ Q_J4 + Q_EN2 = Q_C2, wherein Q_C1 and Q_C2 are the flow rates of combined airflows 606a and 606b, respectively. In some examples, when Q_J1= Q_J2 = Q_J3 = Q_J4, then Q_EN1 = Q_EN2 and Q_C1 = Q_C2. However, altering one or more of flow rates Q_J1, Q_J2, Q_J3, and Q_J4 can alter the rates of entrainment Q_EN1 and Q_EN2, and therefore the total amount of ambient air 604 entrained and the flow rates Q_C1 and Q_C2 at suction inlet 622. Each jet of air is emitted from a jet outlet 612a, b, c, d at a first flow rate. The combined airflow 606a is drawn into the suction inlet 622 at a second, greater flow rate, and the combined airflow 606b is drawn into the suction inlet 622 at a third, greater flow rate. The second and third flow rates may be substantially the same. Both the second and third flow rates may be greater than the first flow rate. The ambient air 604 adjacent to boundaries defining the combined airflows 606a, b will experience the strongest entrainment. Dividing streamlines 605a and 605b depict boundaries after which the ambient air 604 experiences no or negligible entrainment. Between these boundaries, the ambient air 604 will experience diminishing entrainment effects as the distance from the jet unit 610 increases. The rate of induced air flow 607 is represented by Q_IND. After the combined airflows 606a, b are drawn into the suction unit 620, it may become a single exhaust airflow 608. The exhaust airflow 608 through the suction inlet 622 is then defined by flow rate QEX = QC1 + QC2 + QIND. The suction inlet 622 is arranged to draw at least a portion of the combined airflows 606a, b and at least a portion of the induced airflow 607 into the suction unit 620. In particular, the suction inlet 622 has a greater cross-sectional area than a sum of the cross-sectional areas of the combined airflows 606a, b, such that substantially all of the combined airflows 606a, b is drawn into the suction unit 620 via the suction inlet 622, along with at least a portion of the induced airflow 607. The exhaust airflow 608 is emitted from the suction unit 610 through suction outlet 628. In this example, the exhaust airflow 608, or a portion thereof, may be emitted into an exhaust duct as described above. Alternatively, or additionally, the exhaust airflow 608, or a portion thereof, may be treated by an air treatment unit as described above. Furthermore, the exhaust flow 608, or a portion thereof, may be returned to the jet unit by a return duct as described above. Whilst particular examples and embodiments have been described, other embodiments are envisaged which fall within the scope of the invention. For example, the embodiments shown in Figures 8 and 9 may be combined, such that a plurality of jet outlets are located on a lower surface of the suction unit and on an orthogonal back panel surface, with each jet outlet being arranged to direct a jet of air towards the suction inlet.

Claims

CLAIMS 1. An extractor assembly comprising a jet unit and a suction unit, wherein: the jet unit comprises a jet outlet configured to emit a jet of air towards the suction unit; the jet unit is arranged such that, as the jet of air travels from the jet unit to the suction unit, the jet of air entrains ambient air from around at least a portion of a perimeter of the jet of air to create a combined airflow; and, the suction unit comprises a suction inlet through which the combined airflow is drawn into the suction unit, and a suction outlet through which the combined airflow is emitted from the suction unit.

2. An extractor assembly as claimed in claim 1, wherein the jet of air is emitted from the jet outlet at a first flow rate, and the combined airflow is drawn into the suction inlet at a second, greater flow rate.

3. An extractor assembly as claimed in either of claims 1 or 2, wherein the suction inlet has a cross-sectional area that is equal to or greater than the maximum cross-sectional area of the combined airflow at the suction inlet.

4. An extractor assembly as claimed in any preceding claim, wherein the jet outlet and the suction inlet are co-axially arranged.

5. An extractor assembly as claimed in any of claims 1 to 3, wherein a centreline through the jet outlet and a centreline through the suction inlet are radially and/or angularly offset.

6. An extractor assembly as claimed in any preceding claim, wherein the jet outlet is arranged such that the emitted jet of air has a component parallel to the centreline of the suction inlet and/or a component perpendicular to the centreline of the suction inlet.

7. An extractor assembly as claimed in any preceding claim, wherein the jet unit comprises a first airflow generator for generating the jet of air, and the suction unit comprises a second airflow generator for drawing the combined airflow into the suction unit.

8. An extractor assembly as claimed in any preceding claim, wherein the jet unit is spaced apart from the suction unit.

9. An extractor assembly as claimed in any of claims 1 to 7, wherein the jet unit is at least partially adjacent to and/or at least partially adjoining the suction unit.

10. An extractor assembly as claimed in any preceding claim, wherein the jet outlet and the suction inlet are provided at substantially the same height from a common datum.

11. An extractor assembly as claimed in any preceding claim, wherein the jet outlet is defined by a discrete aperture or an elongate slot.

12. An extractor assembly as claimed in any preceding claim, wherein a separation distance between the jet outlet and the suction inlet is at least 200 mm.

13. An extractor assembly as claimed in any preceding claim, further comprising an exhaust duct coupled to the suction outlet; wherein the exhaust duct is arranged such that the combined airflow drawn through the suction inlet, or a portion thereof, is received by the exhaust duct via the suction outlet; and wherein the exhaust duct is additionally arranged to expel the combined airflow, or part thereof, from the environment.

14. An extractor assembly as claimed in any preceding claim, wherein the jet unit comprises one or more guides arranged to cause, in use, the jet of air to travel between the jet outlet and the suction inlet in a non-linear motion.

15. An extractor assembly of any preceding claim, comprising at least one additional jet unit arranged to emit at least one additional jet of air towards the suction unit, wherein the at least one additional jet of air entrains ambient air to create an additional combined airflow, and the suction inlet is arranged to draw at least a portion of each of the combined airflow and the additional combined airflow into the suction unit.

16. An extractor assembly as claimed in any preceding claim, wherein the jet unit comprises a plurality of jet outlets, each jet outlet being configured to emit a jet of air towards the suction unit.

17. An extractor assembly as claimed in claim 16, wherein the plurality of jet outlets are arranged on at least one surface and arranged such that a number of the jets of air emitted interfere with each other to create a reinforced jet of air; and wherein the reinforced jet of air entrains ambient air from around at least a portion of a perimeter of the reinforced jet of air to create the combined airflow.

18. An extractor assembly as claimed in either of claim 16 or 17, wherein each of the plurality of jet outlets is defined by either a discrete aperture or an elongate slot.

19. An extractor assembly as claimed in any preceding claim, further comprising an air treatment unit for treating at least a portion of the combined airflow drawn into the suction inlet.

20. An extractor assembly as claimed in claim 19, further comprising a detector arranged to detect a parameter of the ambient air and a controller connected to the detector, wherein the controller is arranged to cause the jet of air to be directed towards the suction inlet in response to the detector indicating that a predetermined treatment criterion is met.

21. An extractor assembly as claimed in any preceding claim, wherein the suction unit is arranged above one or more pollutant sources.

22. An extractor assembly as claimed in claim 21, wherein the jet outlet is positioned at a side of the one or more pollutant sources.

23. An extractor assembly as claimed in claim 21, wherein the jet outlet is positioned substantially at a centre or a midpoint of two or more pollutant sources.