Airflow assembly

Abstract

An airflow assembly comprises a body 102 with an air inlet 104. The body comprises a first body section 102a coupled to a second body section 102b and rotatable relative to the second body section ar

Description

BACKGROUND A conventional domestic fan typically includes a set of blades mounted for rotation about an axis, and a drive apparatus for rotating the set of blades to generate an airflow. The fan may also oscillate in a side-to-side manner to direct the airflow in different directions. SUMMARY An aspect of the present disclosure provides an airflow assembly for outputting an airflow, the airflow assembly comprising: (i) a body, comprising: (a) an air inlet through which air is drawn into the airflow assembly, (b) a first body section, and (c) a second body section, the first body section being coupled to the second body section and being rotatable, relative to the second body section, around a first axis, and (ii) a head coupled to the body, wherein: the head comprises an air outlet for directing the airflow out of the airflow assembly, the head is rotatable, relative to the body, around a second axis from a first rotational position to a second rotational position, and the head is configured such that rotation of the head about the second axis varies an inclination angle, relative to the first axis, of the airflow output from the air outlet, and wherein the airflow assembly is configured to rotate the first body section around the first axis while the head rotates around the second axis. The airflow assembly (which may be alternatively known as a fan and / or an air purifier, a humidifier, a dehumidifier, an air conditioner, a heater, etc.) can provide advantages over conventional airflow assemblies. For example, because the head is configured to vary the inclination angle (i.e., upwards and downwards) of the airflow by rotating the head around the second axis, the airflow may be directed in different directions (i.e., in lateral directions) during this rotation. For example, the head may be asymmetric in cross-section, so that the airflow is not output in the same vertical plane as the inclination angle of the airflow is adjusted via the rotation of the head. The redirection of the airflow in the vertical direction with such an asymmetric head can therefore introduce an unwanted lateral / horizontal component to the airflow. This change in direction may be unpleasant to a user sat in front of the airflow assembly (for example, during the rotation, the airflow may no longer be directed towards them), or may be unpleasant for another user who is sat out of the airflow initially (for example, during the rotation, the person may be subjected to the airflow). Typically, a user may wish for the airflow to remain pointing in the same direction within a room. To reduce or avoid this issue, the airflow assembly according to the present disclosure includes a body that can rotate to keep the airflow directed in generally the same direction as the head rotates, and therefore as the horizontal / lateral component of the airflow is introduced. The body therefore rotates in a direction opposite to the direction of the horizontal / lateral component of the airflow that is introduced by the rotation of the head. The body rotation essentially “cancels out” the lateral component of the airflow, so that the airflow continues to point in the same direction before, during and after the rotation of the head from the first rotational position to the second rotational position. The head and body can therefore rotate in unison to provide an airflow assembly that has an airflow output direction that is more consistent. In examples, “the head is configured such that rotation of the head about the second axis varies an inclination angle, relative to the first axis, of the airflow output from the air outlet” may mean that “the head is configured such that rotation of the head about the second axis varies an inclination angle, relative to the first axis, of the air outlet”. In certain examples, the airflow assembly is a fan and / or an air purifier. In an example, the airflow assembly may be bladeless. In other examples, the airflow assembly is a humidifier, a dehumidifier, an air conditioner, or a heater. The first axis may be a longitudinal axis of the second body section. The first axis may be vertically orientated in use (i.e., when the airflow assembly is in operation). In a particular arrangement, the second body section forms a base of the airflow assembly. In examples, the second body section is stationary (such as stationary relative to a surface on which the airflow assembly is arranged) and the first body section moves relative to the stationary second body section. The first body section is therefore rotatable / moveable. In one arrangement, the air inlet is formed in the second body section. In another example the air inlet is formed in the first body section. In some examples, an angle of rotation of the first body section is between about 5 degrees and about 45 degrees, such as between about 20 degrees and about 30 degrees, and in particular about 22.5 degrees during rotation of the head. In an example, the body (such as the first body section) houses an impeller configured to draw the air into the body via the air inlet. The impeller may be orientated within the body such that the airflow is output from the impeller in a vertical direction (within the body). In a particular arrangement, the rotation axis of the impeller is orientated parallel to the first axis (such that the airflow flows along the first axis when exiting the impeller). In an example, the second axis is arranged obliquely relative to the first axis. That is, the axes are not parallel nor are they perpendicular to each other. In an example, an inclination angle of greater than 0 degrees and less than 90 degrees is subtended between the first axis and the second axis, or more particularly between 45 and 90 degrees, or more particularly between 60 degrees and 80 degrees, or between 65 degrees and 70 degrees, such as 67.5 degrees. In an example, the head is configured such that: a non-zero angle is subtended between the second axis and a direction in which the airflow is output from the air outlet. The angle may be oblique (such as greater than 0 degrees and less than 90 degrees). In one particular case, the angle subtended between the second axis and the direction in which the airflow is output from the air outlet is 22.5 degrees. As mentioned above, the airflow is directed out of the head at an inclination angle and the inclination is dependent / based on the rotational position of the head around the second axis. The inclination angle is therefore changeable by rotating the head around the second axis. In this disclosure, the inclination angle is an angle measured from the first axis (which may be vertically orientated). If instead the angle were to be measured from a horizontal plane / axis, the angle is equal to 90 degrees minus the inclination angle. In some arrangements, the air inlet comprises one or more inlet openings. Similarly, in some arrangements, the air outlet comprises one or more outlet openings. In examples, the first axis may be known as a body rotation axis and the second axis may be known as a head rotation axis, and vice versa. In examples, the airflow assembly is configured to rotate the first body section around the first axis in a first azimuthal direction and a second azimuthal direction, opposite to the first azimuthal direction, while the head rotates around the second axis from the first rotational position to the second rotational position. The first body section can therefore rotate in two opposite directions around the first axis to counteract the changes in direction of the airflow as the head rotates. For example, as the head rotates, the airflow may begin to rotate away from an initial pointing direction and at a particular rotational position, the airflow may be pointing away from its initial direction by a maximum amount, and as the head continues to rotate, the airflow may move back to pointing in the initial direction. The dual rotation direction of the first body section therefore accounts for the airflow pointing in different directions during the rotation. In a particular example, the airflow assembly is configured to: (i) rotate the head around the second axis from the first rotational position to the second rotational position via an intermediate position, (ii) rotate the first body section around the first axis in the first azimuthal direction while the head rotates around the second axis from the first rotational position to the intermediate position, and (iii) rotate the first body section around the first axis in the second azimuthal direction opposite to the first azimuthal direction, while the head rotates around the second axis from the intermediate position to the second rotational position. The airflow assembly is therefore configured such that an azimuth angle of the airflow that is output from the air outlet remains constant while the airflow assembly rotates the head around the second axis from the first rotational position to the second rotational position. The azimuth angle may be measured around the first axis. In some examples, an angle of rotation of the first body section as the head rotates from the first rotational position to the intermediate position is based on a rotational variation of the airflow output direction from the head as the head rotates from the first rotational position to the intermediate position. In some examples, the airflow assembly is configured to rotate the first body section around the first axis in response to the airflow assembly rotating the head around the second axis from the first rotational position to the second rotational position. Thus, as the head is caused to rotate, the body is caused to rotate. The body rotation can therefore be operated based on the action of the head. Having the airflow assembly rotate the body in response to the head rotation, may avoid the need to synchronize timings between different rotation mechanisms which may otherwise operate independently. In examples, the airflow assembly comprises a head rotation mechanism configured to rotate the head around the second axis from the first rotational position to the second rotational position. In examples, the airflow assembly also comprises a body rotation mechanism configured to rotate the first body section around the first axis while the head rotation mechanism rotates the head around the second axis from the first rotational position to the second rotational position. For example, the body rotation mechanism may be configured to rotate the first body section around the first axis in the first azimuthal direction and the second azimuthal direction, opposite to the first azimuthal direction, while the head rotation mechanism rotates the head around the second axis from the first rotational position to the second rotational position. The mechanisms can therefore work together to cause rotation of the body and head. In a particular example, the body rotation mechanism may act to rotate the body in response to the head rotation mechanism rotating the head. In examples, the head rotation mechanism comprises a motor. The airflow assembly may further comprise a controller, such as one or more processors configured to cause the head rotation mechanism to operate. In examples, the body rotation mechanism comprises a motor. The airflow assembly may further comprise a controller, such as one or more processors configured to cause the body rotation mechanism to operate. A single controller may cause both the body rotation mechanism and the head rotation mechanism to operate. In some examples, the body further comprises a head mounting section defining a rotation plane, the second axis extends from the rotation plane and is normal to the rotation plane, and the second axis is arranged obliquely relative to the first axis. In this example, obliquely means that the axes are not parallel nor are they perpendicular to each other. The head mounting section therefore defines a plane or surface on which the head can rotate. In examples, the head is rotatable on the rotation plane, relative to the head mounting section, around the second axis. In examples, the rotation plane is circular. In examples, the rotation plane is angled relative to a horizontal plane, so is not parallel to the horizontal plane, meaning that the head rotates obliquely relative to the horizontal plane. The horizontal plane is a reference plane parallel to the ground or surface on which the airflow assembly is located. In examples, the head mounting section is coupled to (or forms part of) the first body section (and so rotates with the first body section relative to the second body section). In some examples, the head defines an airflow output plane, the airflow being output from the air outlet along a direction that is normal to the airflow output plane, and an oblique angle is subtended between the airflow output plane and the rotation plane. In examples, the oblique angle is between about 10 degrees and about 30 degrees, or more particularly between about 20 degrees and about 25 degrees, such as about 22.5 degrees. Put another way, the head comprises an asymmetric cowl, the asymmetric cowl being rotatable around the second axis. The asymmetric nature of the head therefore causes the airflow direction to change in elevation as the head rotates. In examples, the head defines a second rotation plane that is parallel to the rotation plane of the head mounting section. The second rotation plane may be adjacent to the rotation plane of the head mounting section. In some examples, when the head is arranged in the first rotational position, the airflow is directed out of the head at a first inclination angle relative to the first axis, the first inclination angle being between about 95 degrees and about 75 degrees, such as between about 90 degrees and about 80 degrees. In some examples, when the head is arranged in the second rotational position, the airflow is directed out of the head at a second inclination angle relative to the first axis, the second inclination angle being between about 40 degrees and about 60 degrees, such as between about 45 degrees and about 55 degrees. Directing the airflow out of the air outlet at an inclination angle of between about 95 degrees and about 75 degrees, means that the airflow is output in a direction that is between about -5 degrees and about 15 degrees relative to a horizontal plane (the negative angle being an angle measured below the horizontal plane, from the horizontal plane down to the ground). This may be useful to allow the airflow assembly to operate in a fan / cooling / heating mode. For example, when placed on a desk or in a room, air is output substantially horizontally, which provides cooling for a user. Directing the airflow out of the air outlet at an inclination angle of between about 40 degrees and about 60 degrees, means that the air is output in a direction that is between about 50 degrees and about 30 degrees relative to a horizontal plane. Directing the airflow at about 45 degrees into a room has been found to maximise the cleaning efficiency of an airflow assembly that can act as an air purifier. For example, this can maximise the distance over which the airflow is ejected into the room. In examples, the first inclination angle is between about 90 degrees and about 80 degrees (the airflow output is between about 0 degrees and about 10 degrees relative to the horizontal plane) and the second inclination angle is between about 45 degrees and about 55 degrees (the airflow output is between about 45 degrees and about 35 degrees relative to the horizontal plane). In examples, the first inclination angle is about 90 degrees (i.e., the airflow is output in a direction that is about 0 degrees relative to the horizontal plane). In examples, the second inclination angle is about 45 degrees (i.e., the airflow is output in a direction that is about 45 degrees relative to the horizontal plane). In a particular example, the first inclination angle is about 90 degrees, and the second inclination angle is about 45 degrees. This particular configuration may provide an airflow assembly that provides both benefits above. That is, the airflow assembly provides a useful cooling / heating / fan mode and an effective air purifier mode. In some examples, an angle of rotation between the first rotational position and the second rotational position is about 180 degrees. Rotating the head through around 180 degrees allows the airflow assembly to effectively switch between cooling / fan mode and air purifier mode. As such, the airflow assembly (such as the head rotation mechanism) may therefore be configured to rotate the head around the second axis by about 180 degrees. As mentioned above, the rotation direction of the first body section may change when the head rotates beyond an intermediate position. In examples, an angle of rotation between the first rotational position and the intermediate position is about 90 degrees and an angle of rotation between the intermediate position and the second rotational position is about 90 degrees. In some examples, the head comprises an outer wall and a central bore, and an airflow passage extends through the head between the outer wall and the central bore, wherein an open end of the airflow passage forms the air outlet. The central bore can result in a smooth airflow path, so the airflow is quieter and lower in pressure. The central bore can also control the open area of the air outlet to maintain the airflow velocity at the outlet for mixing with the air in the room. In some examples, the central bore is enclosed such that airflow does not flow through / along the central bore. In examples, the central bore is fixed relative to the outer wall, such that the central bore and outer wall rotate together as the head rotates relative to the body. The central bore may be generally coaxial with the outer wall. In some examples, the central bore has a tapered end at an end of the central bore closest to the open end of the airflow passage. The tapered end can allow the air at the air outlet to be controlled. For example, the airflow velocity at the air outlet can be controlled, which determines the performance as a cooling or mixing device / fan. In some examples, the tapered end has a non-uniform taper. The tapered end is therefore asymmetric, for example, the tapered end is non-uniform in cross-section. In some cases, when the head is arranged in the first rotational position, a longest surface of the tapered end is positioned further from the second body section than a shortest surface of the tapered end. When the head is arranged in the second rotational position, the shortest and longest surfaces switch places, such that the longest surface of the tapered end is positioned closer to the second body section than the shortest surface of the tapered end. In alternative examples, the central bore has a flat end at an end of the central bore closest to the open end of the airflow passage. In some cases, as the airflow exits the impeller, the airflow may be flowing circumferentially around the first axis and around the central bore as it flows along the first body section and out of the air outlet. A vortex may therefore exist within the airflow. To stop or reduce this, the head may comprise a plurality of vanes, each vane of the plurality of vanes extending between the outer wall and the central bore. These vanes, which may each extend radially from the central bore to the outer wall and be spaced around the central bore, can slow down the circumferential flow that may exist in the airflow. The vanes may segment the airflow passage into two or more airflow channels (the channels together forming the airflow passage). In examples, the plurality of vanes are (rotationally) fixed relative to the central bore, such that the central bore, the plurality of vanes and the outer wall rotate together as the head rotates relative to the body. In other examples, the head comprises one or more vanes, each vane of the one or more vanes extending concentrically around the central bore. Concentric vanes can allow the air outlet area to be controlled. In examples, the body further comprises a head mounting section, the head mounting section comprising: an outer wall and a central bore. In some examples, the first body section has a circular cross-section in a plane perpendicular to the first axis and wherein the head has a circular cross-section in a plane perpendicular to the second axis. When both the first body section and the head have the same circular cross-sectional shape, the overall shape of the first body section and head remains unchanged during rotation of the head. This is because circles have an infinite rotational symmetry, and thus, any rotation of the head around the second axis preserves the alignment and overall shape. Contrast, for example, with a case where both the first body section and head have a square or rectangular cross-section where rotating the head would disrupt the alignment, resulting in a change in the overall shape. In examples, the cross-sectional shape is defined at an outer perimeter or circumference. In examples, the second body section may also have a circular cross-section in a plane perpendicular to the first axis to provide the same benefits as the first body section rotates relative to the second body section. In another arrangement, there is provided an airflow assembly for outputting an airflow, the airflow assembly comprising: a body, comprising: an air inlet through which air is drawn into the airflow assembly; a first body section and a second body section, the first body section being coupled to the second body section and being rotatable, relative to the second body section, around a first axis; a head mounting section defining a rotation plane, wherein a second axis extends from the rotation plane, the second axis being normal to the rotation plane, wherein a non-zero angle is subtended between the first and second axes; a head coupled to the head mounting section on the rotation plane, wherein: the head comprises an air outlet for directing the airflow out of the airflow assembly; the head is rotatable, relative to the head mounting section, around the second axis; and the head is configured such that rotation of the head about the second axis varies an inclination angle of the airflow from the air outlet relative to the first axis; a head rotation mechanism configured to rotate the head around the second axis from a first rotational position to a second rotational position via an intermediate position; and a body rotation mechanism configured to: rotate the first body section around the first axis in a first azimuthal direction while the head rotation mechanism rotates the head around the second axis from the first rotational position to the intermediate position; and rotate the first body section around the first axis in a second azimuthal direction opposite to the first azimuthal direction, while the head rotation mechanism rotates the head around the second axis from the intermediate position to the second rotational position. Such an arrangement may include any or all of the features or components discussed above. Any features or components described in the above aspects may be combined with any features or components described in the following aspects. Another aspect of the present disclosure provides an airflow assembly for outputting an airflow, the airflow assembly comprising: (i) a body, comprising an air inlet through which air is drawn into the airflow assembly, and (ii) a head coupled to the body. The head comprises an air outlet for directing the airflow out of the airflow assembly, and is rotatable, relative to the body, around a head rotation axis, from a first rotational position to a second rotational position. The head is configured such that rotation of the head about the head rotation axis varies an inclination angle, relative to a vertical axis, of the airflow output from the air outlet, the head rotation axis and the vertical axis being oblique. The head is configured such that: (a) when the head is arranged in the first rotational position, the airflow is directed out of the head at a first inclination angle relative to the vertical axis, the first inclination angle being between about 95 degrees and about 75 degrees, and (b) when the head is arranged in the second rotational position, the airflow is directed out of the head at a second inclination angle relative to the vertical axis, the second inclination angle being between about 40 degrees and about 60 degrees. The airflow assembly (which may be alternatively known as a fan and / or an air purifier, a humidifier, a dehumidifier, an air conditioner, a heater, etc.) can provide advantages over conventional airflow assemblies. For example, because the head is configured to vary the inclination angle (i.e., upwards and downwards) of the airflow by rotating the head around the head rotation axis, the airflow may be directed in a desired direction depending on the particular use requirements of a user. Furthermore, in contrast to an airflow assembly that may output airflow vertically, the airflow may be directed across a room in both rotational positions. Furthermore, directing the airflow out of the air outlet at an inclination angle of between about 95 degrees and about 75 degrees means that the airflow is output in a direction that is between about -5 degrees and about 15 degrees relative to a horizontal plane (the negative angle being an angle measured below the horizontal plane, from the horizontal plane down to the ground). This may be useful to allow the airflow assembly to operate in a fan mode. For example, when placed on a desk or in a room, airflow is output substantially horizontally, which provides cooling / heating for a user. Directing the airflow out of the air outlet at an inclination angle of between about 40 degrees and about 60 degrees means that the airflow is output in a direction that is between about 50 degrees and about 30 degrees relative to a horizontal plane. Directing the airflow into a room at an inclination angle of between about 50 degrees and about 30 degrees (and in particular about 45 degrees) has been found to maximise the air cleaning efficiency of an airflow assembly that can act as an air purifier. For example, this can maximise the distance over which the airflow is ejected into the room. In examples, the first inclination angle is between about 90 degrees and about 80 degrees (the airflow output is between about 0 degrees and about 10 degrees relative to the horizontal plane) and the second inclination angle is between about 45 degrees and about 55 degrees (the airflow output is between about 45 degrees and about 35 degrees relative to the horizontal plane). In examples, the first inclination angle is about 90 degrees (i.e., the airflow is output in a direction that is about 0 degrees relative to the horizontal plane). In examples, the second inclination angle is about 45 degrees (i.e., the airflow is output in a direction that is about 45 degrees relative to the horizontal plane). In a particular example, the first inclination angle is about 90 degrees, and the second inclination angle is about 45 degrees. This particular configuration may provide an airflow assembly that provides all of the benefits discussed above. That is, the airflow assembly provides a useful cooling / heating mode and an effective air purifier mode. In this example, oblique means that the axes are not parallel nor are they perpendicular to each other. In an example, an inclination angle of greater than about 0 degrees and less than about 90 degrees is subtended between the vertical axis and the head rotation axis, or more particularly between about 45 degrees and about 90 degrees, or more particularly between about 60 degrees and about 80 degrees, or between about 65 degrees and about 70 degrees, such as about 67.5 degrees. In an example, the head is configured such that: a non-zero angle is subtended between the head rotation axis and a direction in which the airflow is output from the air outlet. The angle may be oblique (such as greater than about 0 degrees and less than about 90 degrees). In one particular case, the angle subtended between the head rotation axis and the direction in which the airflow is output from the air outlet is about 22.5 degrees. In examples, “the head is configured such that rotation of the head about the head rotation axis varies an inclination angle, relative to the vertical axis, of the airflow output from the air outlet” may mean that “the head is configured such that rotation of the head about the head rotation axis varies an inclination angle, relative to the vertical axis, of the air outlet”. In certain examples, the airflow assembly is a fan and / or an air purifier. In an example, the airflow assembly may be bladeless. In other examples, the airflow assembly is a humidifier, a dehumidifier, an air conditioner, or a heater. The airflow is directed out of the head at an inclination angle and the inclination is dependent / based on the rotational position of the head around the head rotation axis. The inclination angle is therefore changeable by rotating the head around the head rotation axis. In this disclosure, the inclination angle is an angle measured from the vertical axis. If instead the angle were to be measured from a horizontal plane / axis, the angle is equal to 90 degrees minus the inclination angle. In some arrangements, the air inlet comprises one or more inlet openings. Similarly, in some arrangements, the air outlet comprises one or more outlet openings. In an example, the body (such as a first body section of the body) houses an impeller configured to draw air into the body via the air inlet. The impeller may be orientated within the body such that the airflow is output from the impeller in a vertical direction (within the body). In a particular arrangement, the rotation axis of the impeller is orientated vertically. In some examples, an angle of rotation between the first rotational position and the second rotational position is about 180 degrees. Rotating the head through around 180 degrees allows the airflow assembly to effectively adjust the inclination angle and / or switch between cooling / heating mode and air purifier mode. As such, the airflow assembly may therefore be configured to rotate the head around the head rotation axis by about 180 degrees. In examples, the head is rotatably positionable at a third rotational position between the first and second rotational positions, such that the airflow is directed out of the head at a third inclination angle relative to the vertical axis, the third inclination angle being between the first and second inclination angles. Accordingly, in some examples, the user may be able to set the inclination angle at a range of angles, by causing the head to be positioned at a range of different rotational positions. In one example, the third rotational position is referred to as an intermediate position. In examples, the body comprises: (i) a body section, the body section having a longitudinal axis arranged parallel to the vertical axis, and (ii) a head mounting section extending between the body section and the head, the head mounting section defining a rotation plane on which the head rotates, wherein the head rotation axis extends from the rotation plane and is normal to the rotation plane. The head mounting section therefore defines a plane or surface on which the head can rotate. In examples, the head is rotatable on the rotation plane, relative to the head mounting section, around the head rotation axis. In examples, the rotation plane is circular. In examples, the longitudinal axis is (or defines) the vertical axis, and is therefore vertical. In examples, the rotation plane is angled relative to a horizontal plane, so is not parallel to the horizontal plane, meaning that the head rotates obliquely relative to the horizontal plane. The horizontal plane is a reference plane parallel to the ground or surface on which the airflow assembly is located. As will be discussed in more detail below, in some examples, the body section may comprise a first body section and a second body section. The head mounting section may therefore extend between the first body section and the head. In examples where the body itself can rotate (for example, the first body section may rotate relative to the second body section), the longitudinal axis may be referred to as a body rotation axis. In examples, the head mounting section defines a curved airflow channel between the body section and the head. The head mounting section is therefore itself curved. A curved head mounting section can help to transition the airflow from the vertically orientated body section to the head. A curved airflow channel can reduce turbulence and noise. In an example, the body section is not curved, and may therefore define a straight airflow channel. An airflow channel is a channel along which the airflow can flow. In examples, the head defines an airflow output plane, the airflow being output from the air outlet along a direction that is normal to the airflow output plane, and an oblique angle is subtended between the airflow output plane and the rotation plane. In examples, the oblique angle is between about 10 degrees and about 30 degrees, or more particularly between about 20 degrees and about 25 degrees, such as about 22.5 degrees. Put another way, the head comprises an asymmetric cowl, the asymmetric cowl being rotatable around the head rotation axis. The asymmetric cowl can define an outer wall of the head, for example. The asymmetric nature of the head therefore causes the airflow direction to change in elevation as the head rotates. In examples, the head defines a second rotation plane that is parallel to the rotation plane of the head mounting section. The second rotation plane may be adjacent to the rotation plane of the head mounting section. In examples, the body comprises a first body section and a second body section, the first body section being coupled to the second body section and being rotatable, relative to the second body section, around a body rotation axis. Thus, in some examples, the body can rotate independently of the head, thereby allowing the airflow output direction to be controlled. In examples, the first and second body sections together form a body section of the body. In examples, the body rotation axis is coincident with the longitudinal axis of the body section. In some examples, because the head is configured to vary the inclination angle (i.e., upwards and downwards) of the airflow by rotating the head around the head rotation axis, the airflow may be directed in different directions (i.e., in lateral directions) during this rotation. For example, the head may be asymmetric in cross-section, so that the airflow is not output in the same vertical plane as the inclination angle of the airflow is adjusted via the rotation of the head. The redirection of the airflow in the vertical direction with such an asymmetric head can therefore introduce an unwanted lateral / horizontal component to the airflow. This change in direction may be unpleasant to a user sat in front of the airflow assembly (for example, during the rotation, the airflow may no longer be directed towards them), or may be unpleasant for another user who is sat out of the airflow initially (for example, during the rotation, the person may be subjected to the airflow). Typically, a user may wish for the airflow to remain pointing in the same direction within a room. To reduce or avoid this issue, the airflow assembly may include a body that can rotate to keep the airflow directed in generally the same direction as the head rotates, and therefore as the horizontal / lateral component of the airflow is introduced. The body therefore rotates in a direction opposite to the direction of the horizontal / lateral component of the airflow that is introduced by the rotation of the head. The body rotation essentially “cancels out” the lateral component of the airflow, so that the airflow continues to point in the same direction before, during and after the rotation of the head from the first rotational position to the second rotational position. The head and body can therefore rotate in unison to provide an airflow assembly that has an airflow output direction that is more consistent. Accordingly, in examples, the airflow assembly is configured to rotate the first body section around the body rotation axis while the head rotates around the head rotation axis from the first rotational position to the second rotational position. The body rotation axis may be vertically orientated in use (i.e., when the airflow assembly is in operation). In a particular arrangement, the second body section forms a base of the airflow assembly. In examples, the second body section is stationary (such as stationary relative to a surface on which the airflow assembly is arranged) and the first body section moves relative to the stationary second body section. The first body section is therefore rotatable / moveable. In one arrangement, the air inlet is formed in the second body section. In another example the air inlet is formed in the first body section. In some examples, an angle of rotation of the first body section is between about 5 degrees and about 45 degrees, such as between about 20 degrees and about 30 degrees, and in particular about 22.5 degrees during rotation of the head. In examples, the airflow assembly is configured to rotate the first body section around the body rotation axis in a first azimuthal direction and a second azimuthal direction, opposite to the first azimuthal direction, while the head rotates around the head rotation axis from the first rotational position to the second rotational position. The first body section can therefore rotate in two opposite directions around the body rotation axis to counteract the changes in direction of the airflow as the head rotates. For example, as the head rotates, the airflow may begin to rotate away from an initial pointing direction and at a particular rotational position, the airflow may be pointing away from its initial direction by a maximum amount, and as the head continues to rotate, the airflow may move back to pointing in the initial direction. The dual rotation direction of the first body section therefore accounts for the airflow pointing in different directions during the rotation. The airflow assembly is therefore configured such that an azimuth angle of the airflow that is output from the air outlet remains constant while the airflow assembly rotates the head around the head rotation axis from the first rotational position to the second rotational position. The azimuth angle may be measured around the body rotation axis. In a particular example, the airflow assembly is configured to: (i) rotate the head around the head rotation axis from the first rotational position to the second rotational position via an intermediate position, (ii) rotate the first body section around the body rotation axis in the first azimuthal direction while the head rotates around the head rotation axis from the first rotational position to the intermediate position, and (iii) rotate the first body section around the body rotation axis in the second azimuthal direction opposite to the first azimuthal direction, while the head rotates around the head rotation axis from the intermediate position to the second rotational position. In some examples, an angle of rotation of the first body section as the head rotates from the first rotational position to the intermediate position is based on a rotational variation of the airflow output direction from the head as the head rotates from the first rotational position to the intermediate position. In examples, an angle of rotation between the first rotational position and the intermediate position is about 90 degrees and an angle of rotation between the intermediate position and the second rotational position is about 90 degrees. In some examples, the airflow assembly is configured to rotate the first body section around the body rotation axis in response to the airflow assembly rotating the head around the head rotation axis from the first rotational position to the second rotational position. Thus, as the head is caused to rotate, the body is caused to rotate. The body rotation can therefore be operated based on the action of the head. Having the airflow assembly rotate the body in response to the head rotation, may avoid the need to synchronize timings between different rotation mechanisms which may otherwise operate independently. In examples, the airflow assembly comprises a head rotation mechanism configured to rotate the head around the head rotation axis from the first rotational position to the second rotational position. In examples, the airflow assembly comprises a body rotation mechanism configured to rotate the first body section around the body rotation axis while the head rotation mechanism rotates the head around the head rotation axis from the first rotational position to the second rotational position. For example, the body rotation mechanism may be configured to rotate the first body section around the body rotation axis in the first azimuthal direction and the second azimuthal direction, opposite to the first azimuthal direction, while the head rotation mechanism rotates the head around the head rotation axis from the first rotational position to the second rotational position. The mechanisms can therefore work together to cause rotation of the body and head. In a particular example, the body rotation mechanism may act to rotate the body in response to the head rotation mechanism rotating the head. In examples, the head rotation mechanism comprises a motor. The airflow assembly may further comprise a controller, such as one or more processors configured to cause the head rotation mechanism to operate. In examples, the body rotation mechanism comprises a motor. The airflow assembly may further comprise a controller, such as one or more processors configured to cause the body rotation mechanism to operate. A single controller may cause both the body rotation mechanism and the head rotation mechanism to operate. In some examples, the head comprises an outer wall and a central bore, and an airflow passage extends through the head between the outer wall and the central bore, wherein an open end of the airflow passage forms the air outlet. In some examples, the central bore is enclosed such that airflow does not flow through / along the central bore. In examples, the central bore is fixed relative to the outer wall, such that the central bore and outer wall rotate together as the head rotates relative to the body. The central bore may be generally coaxial with the outer wall. In some examples, the central bore has a tapered end at an end of the central bore closest to the open end of the airflow passage. In some examples, the tapered end has a non-uniform taper. The tapered end is therefore asymmetric, for example, the tapered end is non-uniform in cross-section. In some cases, when the head is arranged in the first rotational position, a longest surface of the tapered end is positioned further from the body than a shortest surface of the tapered end. When the head is arranged in the second rotational position, the shortest and longest surfaces switch places, such that the longest surface of the tapered end is positioned closer to the body than the shortest surface of the tapered end. In alternative examples, the central bore has a flat end at an end of the central bore closest to the open end of the airflow passage. In some cases, as the airflow exits the impeller, the airflow may be flowing circumferentially around the body rotation axis and around the central bore as it flows along the body and out of the air outlet. A vortex may therefore exist within the airflow. To stop or reduce this, the head may comprise a plurality of vanes, each vane of the plurality of vanes extending between the outer wall and the central bore. These vanes, which may each extend radially from the central bore to the outer wall and be spaced around the central bore, can slow down the circumferential flow that may exist in the airflow. In examples, the plurality of vanes are (rotationally) fixed relative to the central bore, such that the central bore, the plurality of vanes, and the outer wall rotate together as the head rotates relative to the body. In other examples, the head comprises one or more vanes, each vane of the one or more vanes extending concentrically around the central bore. In some examples, the body has a circular cross-section in a plane perpendicular to the vertical axis and the head has a circular cross-section in a plane perpendicular to the head rotation axis. When both the body and the head have the same circular cross-sectional shape, the overall shape of the body and head remains unchanged during rotation of the head. This is because circles have an infinite rotational symmetry, and thus, any rotation of the head around the head rotation axis preserves the alignment and overall shape. Contrast, for example, with a case where both the body and head have a square or rectangular cross section where rotating the head would disrupt the alignment, resulting in a change in the overall shape. In examples, the cross-sectional shape is defined at an outer perimeter or circumference. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A is a side view of an airflow assembly where the head is arranged in a first rotational position, according to an example; Figure IB is a perspective view of the airflow assembly of Figure 1A; Figure IC is a front view of the airflow assembly of Figure 1 A; Figure 2A is a side view of the airflow assembly of Figure 1A, where the head is arranged in an intermediate position; Figure 2B is a perspective view of the airflow assembly of Figure 2A; Figure 2C is a front view of the airflow assembly of Figure 2A; Figure 3 A is a side view of the airflow assembly of Figure 1A, where the head is arranged in a second rotational position; Figure 3B is a perspective view of the airflow assembly of Figure 3 A; Figure 3C is a front view of the airflow assembly of Figure 3A; Figure 4A is a schematic top-down view of an airflow assembly where the head is arranged in a first rotational position, where a body of the assembly does not rotate; Figure 4B is a schematic top-down view of the airflow assembly of Figure 4A, where the head is arranged in an intermediate position; Figure 4C is a schematic top-down view of the airflow assembly of Figure 4A, where the head is arranged in a second rotational position; Figure 5A is a schematic top-down view of an airflow assembly where the head is arranged in a first rotational position, where a body of the assembly can rotate; Figure 5B is a schematic top-down view of the airflow assembly of Figure 5A, where the head is arranged in an intermediate position; Figure 5C is a schematic top-down view of the airflow assembly of Figure 5A, where the head is arranged in a second rotational position; Figure 6A is a cross-sectional view through the airflow assembly of Figure 1 A; Figure 6B is a cross-sectional view through the airflow assembly of Figure 3 A; Figure 7A is a first perspective view of another example airflow assembly; and, Figure 7B is a second perspective view of the airflow assembly of Figure 7A. DETAILED DESCRIPTION Figures 1A, IB and IC depict an airflow assembly 100 according to an example. Figure 1A shows a side view of the airflow assembly 100, Figure IB shows a perspective view of the airflow assembly 100 and Figure IC shows a front view of the airflow assembly 100. The airflow assembly 100 comprises a body 102 and the body 102 comprises an air inlet 104 through which air can be drawn into the airflow assembly 100 during operation. An impeller (not shown) may cause ambient air to be drawn into the body 102 via the air inlet 104, for example. In this example, the air inlet 104 comprises a plurality of inlet openings in the form of apertures or holes formed in the body 102. The body 102 comprises a first body section 102a and a second body section 102b. In this example, the second body section 102b comprises the air inlet 104. In this example, the first body section 102a houses the impeller. As shown, the first body section 102a is coupled to the second body section 102b and is rotatable, relative to the second body section 102b, around a first axis 106 (also known as a body rotation axis 106). The second body section 102b may therefore be stationary as the first body section 102a rotates around the first axis 106. In this example, the first axis 106 is orientated vertically when the airflow assembly 100 is in operation. A body rotation mechanism (not shown) is configured to rotate the first body section 102a around the first axis 106. The body rotation mechanism of this example comprises one or more motors. The body defines a longitudinal axis that is parallel to (or coincident with) a vertical axis, such as the first axis 106. In other examples, the first and second body sections cannot, or do not, rotate relative to each other. In some examples, the first and second body sections may not be independent body sections, and instead, the assembly 100 may comprise a body section without independent body sections. In such examples, the head, described below, can still rotate around a head rotation axis. The airflow assembly 100 further comprises a head 108 which is coupled to the body 102. In this particular example, the body 102 further comprises a head mounting section 102c and the head 108 is coupled to the head mounting section 102c. The head 108 comprises an air outlet 110 for directing an airflow 112 out of the airflow assembly 100 in a particular direction. The head mounting section 102c of this example bends or curves and therefore defines a curved airflow path / channel for the airflow flowing through the airflow assembly 100. The airflow 112 flowing out of the air outlet 110 is moved through the airflow assembly 100 by the impeller. The airflow 112 may be directed into a room, for example. In this example, the head 108 is rotatable, relative to the body 102, around a second axis 114 (the second axis 114 may alternatively be known as a head rotation axis 114). For example, the head 108 may be rotated around the second axis 114 from a first rotational position (shown in Figures 1A, IB and IC) to a second rotational position by tuming / rotating the head 108. A head rotation mechanism (not shown) is configured to rotate the head 108 around the second axis 114. The head rotation mechanism of this example comprises one or more motors. As shown in Figure 1A, the second axis 114 is arranged relative to the first axis 106 such that an oblique angle 122 is subtended between the first axis 106 and the second axis 114. The oblique angle is therefore measured between a vertical axis (in this case the first axis 106) and the second axis 114. In this particular example, the angle 122 is around 67.5 degrees. Put another way, the second axis 114 is arranged at an angle of about 22.5 degrees relative to a horizontal axis / plane 124. As shown most clearly in Figure 1 A, the head 108 rotates on a rotation plane 116 defined by the head mounting section 102c. The second axis 114 extends from the rotation plane 116 and is normal to the rotation plane 116. The head 108 further defines an airflow output plane 118 and the airflow 112 is output from the air outlet 110 along a direction that is normal to the airflow output plane 118. As shown, an oblique angle 120 is subtended between the airflow output plane 118 and the rotation plane 116. In this particular example, the angle 120 is around 22.5 degrees. In this example, the rotation plane 116 is circular. In examples, the head 108 defines a second rotation plane 128 that is parallel to the rotation plane 116 of the head mounting section 102c. The second rotation plane 128 is arranged adjacent to the rotation plane 116 of the head mounting section 102c. In this example, the second rotation plane 128 is also circular. As will be understood, rotating the head 108 about the second axis 114 varies an inclination angle 126, relative to the first axis 106, of the airflow 112 output from the air outlet 110. This is due to the head 108 being defined by an asymmetric cowl. The inclination angle 126 is measured between the first / vertical axis 106 and the direction of the airflow 112. The airflow direction may be expressed as a vector, in some examples. In this particular configuration, when the head 108 is arranged at the first rotational position shown in Figures 1 A, IB and IC, the inclination angle 126 of the airflow 112 is about 90 degrees (or 0 degrees relative to a horizontal axis / plane 124). In Figure IC, the airflow 112 is directed out of the page in a direction that is perpendicular to a plane defined by the page. In examples, the first and second axes 106, 114 are fixed relative to each other as the head 108 rotates. In examples, the airflow assembly 100 may be operating in a fan mode while the head is arranged in the rotational position shown in Figures 1 A, IB and IC. Figures 2A, 2B and 2C show the airflow assembly 100 after the head 108 has been rotated by a particular angle around the second axis 114. In this case, the angle of rotation between the first rotational position shown in Figures 1A, IB and IC, and the rotational position shown in Figures 2A, 2B and 2C is about 90 degrees. In other words, the head 108 has been rotated through about 90 degrees. For reasons that will become apparent, the rotational position shown in Figures 2A, 2B and 2C will be referred to as an intermediate position, and in some cases a third rotational position. Figure 2A shows a side view of the airflow assembly 100, Figure 2B shows a perspective view of the airflow assembly 100 and Figure 2C shows a front view of the airflow assembly 100. As shown most clearly in Figure 2A, the rotation of the head 108 (having its asymmetric form) has caused the inclination angle 126 of the airflow 112 to change from that shown in Figure 1 A. In this particular configuration, when the head 108 is arranged at the intermediate position shown in Figures 2A, 2B and 2C, the inclination angle 126 of the airflow 112 is about 67.5 degrees (or about 22.5 degrees relative to a horizontal axis / plane 124). In Figure 2C, the airflow 112 is directed out of the page but at an angle that is no longer perpendicular to the plane defined by the page. From the perspective of Figure 2A, it appears that the airflow 112 is directed along the second axis 114, but in fact the airflow 112 is directed slightly towards the viewing position such that there is an angle subtended between the second axis 114 and direction of the airflow 112. Figures 3A, 3B and 3C show the airflow assembly 100 after the head 108 has been rotated by a particular angle around the second axis 114. The rotational position shown in Figures 3 A, 3B and 3C will be referred to as the second rotational position. In this case, the angle of rotation between the first rotational position shown in Figures 1 A, IB and IC, and the second rotational position shown in Figures 3A, 3B and 3C is about 180 degrees. The angle of rotation between the intermediate position shown in Figures 2A, 2B and 2C, and the second rotational position shown in Figures 3 A, 3B and 3C is therefore about 90 degrees. Figure 3 A shows a side view of the airflow assembly 100, Figure 3B shows a perspective view of the airflow assembly 100 and Figure 3C shows a front view of the airflow assembly 100. As shown most clearly in Figure 3 A, the further rotation of the head 108 (having its asymmetric form) has caused the inclination angle 126 of the airflow 112 output from the air outlet 110 to change from that shown in Figures 1A and 2A. In this particular configuration, when the head 108 is arranged at the second rotational position shown in Figures 3 A, 3B and 3C, the inclination angle 126 of the airflow 112 is about 45 degrees. In Figure 3C, the airflow 112 is directed out of the page but at an angle that is not perpendicular to the plane defined by the page since the airflow 112 is being directed diagonally “upwards” from the perspective of the airflow assembly 100. In examples, the airflow assembly 100 may be operating in an air purifier mode while the head is arranged in the rotational position shown in Figures 3 A, 3B and 3C. As will be described, in some examples, the airflow assembly 100 is configured to rotate the first body section 102a around the first axis 106 while the head 108 rotates around the second axis 114. This process can ensure that the airflow 112 output from the airflow assembly 100 points in substantially the same direction into a room while the head 108 rotates around the second axis 114. To illustrate, Figures 4A-4C will be described. Figures 4A, 4B and 4C show a schematic top-down view of an example airflow assembly that is not configured to rotate the first body section 102a around the first axis 106 while the head 108 rotates around the second axis 114. In Figure 4A, the head 108 may be arranged in the first rotational position (like that shown in Figures 1A-1C), and the airflow 112 generally flows outwards from the airflow assembly in a particular direction, such as towards a user 202. For example, the airflow may be defined by a vector along an x-axis shown in Figure 4A. The first axis 106 extends into and out of the page, along the z-axis. Because the inclination angle 126 in Figure 1A is about 90 degrees, the vector does not have any components along the z-axis. In Figure 4B, the head 108 may be arranged in the intermediate position (like that shown in Figures 2A-2C), and the airflow 112 flows outwards from the airflow assembly in a different azimuthal direction to that in Figure 4A owing to the particular configuration of the head 108. For example, the airflow may be defined by a vector that has components along the x-axis and the y-axis, as well as along the z-axis. The dashed line 204 may show the airflow direction of Figure 4A for comparative purposes, and a non-zero azimuth angle 206 may be subtended between the airflow 112 and the previous airflow output direction 204. All or a certain proportion of the airflow 112 may therefore be directed away from the user 202. In Figure 4C, the head 108 may be arranged in the second rotational position (like that shown in Figures 3A-3C), and the airflow 112 flows outwards from the airflow assembly in a particular direction, such as towards a user 202 again. As will be understood, in Figure 4C, the airflow 112 has an increased inclination angle 126 from the airflow 112 shown in Figure 4A, but nevertheless, the airflow 112 will still be generally directed outwards from the airflow assembly along the particular direction. For example, the airflow may be defined by a vector that has components along the x-axis and the z-axis, but not the y-axis. As previously explained, this introduction of an azimuthal component (along the y-axis) to the airflow during rotation of the head 108 may be unpleasant for the user or another user within the environment. It may therefore be desirable to limit the airflow vector to having components in just two dimensions (e.g., the x and z axes) during rotation of the head 108. To reduce or avoid this issue, the airflow assembly 100 can cause the first body section 102a to rotate to keep the airflow directed in generally the same direction as the head 108 rotates, and therefore as the azimuthal component of the airflow is introduced. The first body section 102a therefore rotates in a direction opposite to the direction of the azimuthal component of the airflow that is introduced by the rotation of the head. For example, to steer the airflow 112 in Figure 4B back towards the previous airflow output direction 204, the first body section 102a can rotate anti-clockwise as the head 108 rotates from the first rotational position to the intermediate position, and clockwise (returning to its original position) as the head 108 rotates from the intermediate position to the second rotational position. The rotation therefore essentially “cancels out” the azimuthal component of the airflow, so that the airflow continues to point in generally the same direction before, during and after the rotation of the head 108 from the first rotational position to the second rotational position. To illustrate, Figures 5A-5C will be described. Figures 5A, 5B and 5C show a schematic top-down view of an example airflow assembly 100 that is configured to rotate the first body section 102a around the first axis 106 while the head 108 rotates around the second axis 114. In Figure 5A, the head 108 may be arranged in the first rotational position (like that shown in Figures 1A-1C), and the airflow 112 generally flows outwards from the airflow assembly in a particular direction, such as towards a user 202. For example, the airflow may be defined by a vector along an x-axis shown in Figure 5A. As the head 108 rotates around the second axis 114 from the first rotational position to the intermediate position, the first body section 102a is caused to rotate around the first axis 106 in a first azimuthal direction (in this case an anti-clockwise direction). As shown in Figure 5B, the head 108 is arranged in the intermediate position (like that shown in Figures 2A-2C), and the airflow 112 flows outwards from the airflow assembly in generally the same direction to that in Figure 5 A owing to the first body section 102a having rotated around the first axis 106 by a particular angle of rotation, in this case about 22.5 degrees. For example, the airflow may be defined by vector that has components along the x-axis and the z-axis, but not the y-axis. Substantially all the airflow 112 may therefore be directed towards the user 202. In some cases, the airflow vector may be translated slightly from the original airflow direction of Figure 5A, as shown by the dashed line 208. As the head 108 rotates around the second axis 114 from the intermediate position to the second rotational position, the first body section 102a is caused to rotate around the first axis 106 in a second azimuthal direction opposite to the first azimuthal direction (in this case, in a clockwise direction). As shown in Figure 5C, the head 108 is arranged in the second rotational position (like that shown in Figures 3 A-3C), and the airflow 112 flows outwards from the airflow assembly in a particular direction, such as towards the user 202. As will be understood, in Figure 5C, the airflow 112 has an increased inclination angle 126 from the airflow 112 shown in Figure 5A, but nevertheless, the airflow 112 will still be generally directed outwards from the airflow assembly along the particular direction. For example, the airflow may be defined by a vector that has components along the x-axis and the z-axis, but not the y-axis. Accordingly, the airflow assembly 100 is configured to rotate the first body section 102a around the first axis 106 in a first azimuthal direction and a second azimuthal direction, opposite to the first azimuthal direction, while the head 108 rotates around the second axis from the first rotational position to the second rotational position (in this case, as the head 108 rotates through about 180 degrees). In some examples, the airflow assembly 100 is configured to rotate the first body section 102a around the first axis 106 in response to the airflow assembly 100 rotating the head 108 around the second axis 114 from the first rotational position to the second rotational position. The body rotation can therefore be operated based on the action of the head. For example, the body rotation mechanism may be operated based on a control signal, where the control signal causes the head rotation mechanism to operate / rotate. A central controller may generate the control signal or the head rotation mechanism may generate the control signal and send the control signal to the body rotation mechanism. Although in the above example, the airflow assembly 100 is configured such that when the head 108 is arranged in the first rotational position the inclination angle 126 of the airflow 112 is about 90 degrees (or about 0 degrees relative to a horizontal axis / plane 124), it will be appreciated that the inclination angle 126 may be different. For example, inclination angle 126 may be between about 95 degrees and about 75 degrees (between about -5 degrees and about 15 degrees to a horizontal axis / plane 124) or between about 90 degrees and about 80 degrees (between about 0 degrees and about 10 degrees to a horizontal axis / plane 124) when the head is arranged in the first rotational position. Similarly, although in the above example, the airflow assembly 100 is configured such that when the head 108 is arranged in the second rotational position the inclination angle 126 of the airflow 112 is about 45 degrees, it will be appreciated that the inclination angle 126 may be different. For example, inclination angle 126 may be between about 40 degrees and about 60 degrees (between about 50 degrees and about 30 degrees to a horizontal axis / plane 124) or between about 45 degrees and about 55 degrees (between about 45 degrees and about 35 degrees to a horizontal axis / plane 124) when the head is arranged in the second rotational position. In the above example, the angle 122 subtended between the first axis 106 and the second axis 114 is around 67.5 degrees (or put another way, the second axis 114 is arranged around 22.5 degrees relative to a horizontal axis / plane 124). The second axis 114 may therefore be arranged halfway between the inclination angle of the airflow when the head 108 is arranged in the first rotational position and the inclination angle of the airflow when the head 108 is arranged in the second rotational position. Figure 6A depicts a cross-section through the airflow assembly 100 shown in Figure 1A (although in this example, the first and second body sections 102a, 102b have different lengths along the axis 106 compared to the airflow assembly 100 shown in Figure 1A). Figure 6B depicts a cross-section through the airflow assembly 100 shown in Figure 3 A (although in this example, the first and second body sections 102a, 102b have different lengths along the axis 106 compared to the airflow assembly 100 shown in Figure 3 A). As shown, the airflow assembly 100 comprises an impeller 302 housed within the first body section 102a. Figures 6A and 6B schematically show the body rotation mechanism 318 and the head rotation mechanism 320. As shown throughout the Figures, the head 108 comprises an outer wall 304 and a central bore 306 (shown most clearly in Figures 6A and 6B), and an airflow passage 308 extends through the head 108 between the outer wall 304 and the central bore 306. An open end of the airflow passage 308 forms the air outlet 110. In this example, the airflow passage 308 is formed concentrically around the central bore 306. In this example, the impeller 302 drives the airflow along the airflow passage 308 and out of the air outlet 110. As shown in Figures 6A and 6B, the head mounting section 102c also defines a central bore 312 which is continuous with the central bore 306 in the head 108. The head mounting section 102c also has an outer wall 314 and an airflow passage 316 extends through the head mounting section 102c between the outer wall 314 and the central bore 312. In this example, the airflow passage 316 is formed concentrically around the central bore 312. The airflow passages 316, 308 are also continuous. As shown in Figures 6A and 6B, the central bore 306, 312 is enclosed, such that the airflow from the impeller 302 does not flow through / along the central bore 306, 312. In this example, at an end of the central bore 306, a tapered end 310 (such as a cone shape) is formed, where the tapered end 310 is arranged in the head 108. The tapered end 310 is therefore arranged at end of the central bore 306 that is arranged closest to the air outlet 110. In this example, the tapered end 310 has a non-uniform taper, but in other examples, the tapered end 310 may have a uniform and therefore symmetrical taper. In examples, the central bore 306 is fixed relative to the outer wall 304 of the head 108 such that the central bore 306 (i.e., the tapered end 310) and outer wall 304 rotate together as the head 108 rotates relative to the body. For example, as shown in Figure 6B, the tapered end 310 has been rotated by about 180 degrees around the second axis 114. In some cases, as the airflow exits the impeller 302, the airflow may be flowing circumferentially around the first axis 106 and around the central bore 312, 306 as it flows along the airflow passage 316, 308. To stop or reduce this, the head 108 comprises a plurality of vanes 322, each vane of the plurality of vanes 322 extending between the outer wall 304 and the central bore 306 in the head 108. These vanes, which each extend generally radially from the central bore 306 to the outer wall 304 and are spaced around the central bore 306, can slow down the circumferential flow that may exist in the airflow. In this particular example, the vanes 322 form a “star” shape (see Figures IB, IC, 2B, 2C, 3B, 3C for example), and the tapered end 310 resides towards the center of the star. Each vane 322 may have a length, measured along the airflow passage 308 in the head 108, where some of the vanes 322 have a greater length than other vanes 322, owing to the asymmetric shape of the head 108. In this example, the plurality of vanes 322 are rotationally fixed relative to the central bore 306, such that the central bore 306, the plurality of vanes 322 and outer wall 304 rotate together as the head 108 rotates relative to the head mounting section 102c. In alternative examples, rather than having a tapered end, as in the previous example, the central bore within the head may have a flat end at the end closest to the air outlet 110. Figures 7A and 7B show an example of an alternative airflow assembly 100’ having a central bore with a flat end. As will be described further below, the alternative airflow assembly 100’ also has concentrically arranged vanes extending around the central bore. Other than the alternative form of the central bore and the concentric vanes, the airflow assembly 100’ in Figures 7A and 7B functions the same as previously described, and comprises the same parts / components. In particular, Figure 7A depicts a perspective view of an airflow assembly 100’ where the head is arranged in the first rotational position and Figure 7B depicts a perspective view of an airflow assembly 100’ where the head is arranged in the second rotational position. As shown, the head 108 comprises an outer wall 304 and a central bore 306, and an airflow passage 308 extends through the head 108 between the outer wall 304 and the central bore 306. An open end of the airflow passage 308 forms the air outlet 110. In this example, the airflow passage 308 is formed concentrically around the central bore 306. In this example, the impeller 302 drives the airflow along the airflow passage 308 and out of the air outlet 110. As mentioned, in this example, the end of the central bore 306 has a flat end 324, where the flat end 324 is arranged in the head 108. The flat end 324 is therefore arranged at end of the central bore 306 that is arranged closest to the air outlet 110. In examples, the central bore 306 is fixed relative to the outer wall 304 of the head 108 such that the central bore 306 (i.e., the flat end 324) and outer wall 304 rotate together as the head 108 rotates relative to the body. In this example, the head 108 comprises a plurality of vanes 326, each vane of the plurality of vanes 326 extending concentrically around the central bore 306 in the head 108. Each vane 326 may have a length, measured along the airflow passage 308 in the head 108, where some of the vanes 326 have a greater length than other vanes 326, owing to the asymmetric shape of the head 108. In each of the examples discussed above, the first body section 102a has a circular crosssection in a plane perpendicular to the first axis and the head 108 has a circular cross-section in a plane perpendicular to the second axis. As mentioned, when both the first body section 102a and the head 108 have the same circular cross-sectional shape, the overall shape of the first body section 102a and head 108 remains unchanged during rotation of the head. This effect can be seen in Figures 6A and 6B for example, where the rotation of the head 108 around the second axis 114 preserves the alignment and overall shape.

Claims

1. An airflow assembly for outputting an airflow, the airflow assembly comprising: a body, comprising:an air inlet through which air is drawn into the airflow assembly;a first body section and a second body section, the first body section being coupled to the second body section and being rotatable, relative to the second body section, around a first axis; anda head coupled to the body, wherein:the head comprises an air outlet for directing the airflow out of the airflow assembly;the head is rotatable, relative to the body, around a second axis from a first rotational position to a second rotational position; andthe head is configured such that rotation of the head about the second axis varies an inclination angle, relative to the first axis, of the airflow output from the air outlet; andwherein the airflow assembly is configured to rotate the first body section around the first axis while the head rotates around the second axis.

2. An airflow assembly according to claim 1, wherein the airflow assembly is configured to rotate the first body section around the first axis in a first azimuthal direction and a second azimuthal direction, opposite to the first azimuthal direction, while the head rotates around the second axis from the first rotational position to the second rotational position.

3. An airflow assembly according to claim 2, wherein the airflow assembly is configured to:rotate the head around the second axis from the first rotational position to the second rotational position via an intermediate position;rotate the first body section around the first axis in the first azimuthal direction while the head rotates around the second axis from the first rotational position to the intermediate position; androtate the first body section around the first axis in the second azimuthal direction opposite to the first azimuthal direction, while the head rotates around the second axis from the intermediate position to the second rotational position.

4. An airflow assembly according to any preceding claim, wherein the airflow assembly is configured to rotate the first body section around the first axis in response to the airflow assembly rotating the head around the second axis from the first rotational position to the second rotational position.

5. An airflow assembly according to any preceding claim, further comprising: a head rotation mechanism configured to rotate the head around the second axis from the first rotational position to the second rotational position; anda body rotation mechanism configured to rotate the first body section around the first axis while the head rotation mechanism rotates the head around the second axis from the first rotational position to the second rotational position.

6. An airflow assembly according to any preceding claim, wherein:the body further comprises a head mounting section defining a rotation plane;the second axis extends from the rotation plane and is normal to the rotation plane; andthe second axis is arranged obliquely relative to the first axis.

7. An airflow assembly according to claim 6, wherein:the head defines an airflow output plane, the airflow being output from the air outlet along a direction that is normal to the airflow output plane; andan oblique angle is subtended between the airflow output plane and the rotation plane.

8. An airflow assembly according to any preceding claim, wherein: when the head is arranged in the first rotational position, the airflow is directed out of the head at a first inclination angle relative to the first axis, the first inclination angle being between about 95 degrees and about 75 degrees; andwhen the head is arranged in the second rotational position, the airflow is directed out of the head at a second inclination angle relative to the first axis, the second inclination angle being between about 40 degrees and about 60 degrees.

9. An airflow assembly according to claim 8, wherein the first inclination angle is about 90 degrees, and the second inclination angle is about 45 degrees.

10. An airflow assembly according to any preceding claim, wherein an angle of rotation between the first rotational position and the second rotational position is about 180 degrees.

11. An airflow assembly according to any preceding claim, wherein the head comprises an outer wall and a central bore, and an airflow passage extends through the head between the outer wall and the central bore, wherein an open end of the airflow passage forms the air outlet.

12. An airflow assembly according to claim 10, wherein the central bore has a tapered end at an end of the central bore closest to the open end of the airflow passage.

13. An airflow assembly according to claim 12, wherein the tapered end has a non-uniform taper.

14. An airflow assembly according to any of claims 11 to 13, wherein the head comprises a plurality of vanes, each vane of the plurality of vanes extending between the outer wall and the central bore.

15. An airflow assembly according to any of claims 12 to 13, wherein the head comprises one or more vanes, each vane of the one or more vanes extending concentrically around the central bore.

16. An airflow assembly according to any preceding claim, wherein:the body further comprises a head mounting section, the head mounting section comprising:an outer wall; and, a central bore.

517. An airflow assembly according to any preceding claim, wherein the first body section has a circular cross-section in a plane perpendicular to the first axis and wherein the head has a circular cross-section in a plane perpendicular to the second axis.10

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