FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION AIR VENT
APPLICANT
TATA MOTORS LIMITED
An Indian Company
Bombay House, 24 Homi Mody Street,
Hutatma Chowk, Mumbai 400 001,
Maharashtra, India;
TATA MOTORS EUROPEAN TECHNICAL CENTRE Plc,
Nationality United Kingdom
18 Grosvenor Place, London, SW1X 7HS,
United Kingdom;
The following specification particularly describes the invention and the manner in which it is to be performed.

TITLE OF THE INVENTION
The present disclosure relates to an air vent. Particularly, but not exclusively, the present invention relates to an air vent for a vehicle, where said air vent comprises a Coanda surface. Aspects of the invention relate to an air vent, a vehicle and a component of a seat.
BACKGROUND OF THE INVENTION
Generally, a vehicle will have a cabin in which passengers are transported. Prevailing weather conditions can cause discomfort for the confined passengers and as such several methods of keeping the passengers at an appropriate temperature have been conceived.
Previous methods of cooling passengers involved using fans and blowers with air vents that include slats which can be used to direct the flow of the air coming out of the vent. There are several problems associated with this design.
First, air directed to come out of the vent is partially prevented from doing so due to the presence of the slats. This causes noise as the air collides with the slats, leading to discomfort for passengers. The presence of the slats prevents a stable stream of air from coming from the vent, such that the air flow is turbulent and cannot effectively cool a passenger that is sat a short distance from the vent.
Secondly, prior art systems are inefficient, as only a relatively low proportion of the electrical energy consumed by the blower is converted into kinetic energy in a stream of air that is felt by the passengers. Accordingly, prior art systems may place significant demands on the vehicle battery.
Finally, prior art systems are complex to manufacture, as they require multiple parts to function, including several parts which need to be fitted together.
At least in certain embodiments, the present invention seeks to address or ameliorate at least some of the disadvantages associated with the prior art.

BRIEF SUMMARY OF THE INVENTION
Aspects and embodiments of the invention provide an air vent for a vehicle, a vehicle and a seat component comprising an air vent.
According to one aspect of the invention there is provided an air vent for a vehicle, the air vent comprising a Coanda surface and an annular primary flow inlet arranged to direct a primary flow over the Coanda surface, the air vent further comprising a nozzle downstream of the Coanda surface, the nozzle comprising a diverging portion and a converging portion downstream of the diverging portion. The air vent may be an air vent for an interior of a vehicle cabin, and the air vent may be arranged to direct a flow of air towards a vehicle occupant. The air vent may be an air vent for the inside of a cabin of a vehicle. In some embodiments, the air vent may be provided within a cabin of a vehicle.
The above aspect of the invention provides a vent which can generate focussed, temporally stable air flows up to and exceeding 1.2m away from the nozzle. Focussed in this context means that the vent produces a low-spread, columnar jet of air. For example, the cone angle of the air flow coming from the vent may be less than or equal to 12 degrees. This is ideal for use in passenger vehicles such as cars wherein the passengers may be cooled by a constant air flow, even at relatively large distances from the vent, without requiring a loud blower which can be unpleasant over long periods of time. Such a vent can produce an air flow that has an appropriate diameter when reaching the passenger such that a large amount of the air flow contacts bare skin, increasing the efficacy and efficiency of the cooling effect.
In an embodiment of the present invention the annular primary flow inlet is coupled to an interior cavity of the air vent. The interior cavity is a cavity within the air vent in which the pressure may be raised to cause a substantially continuous flow of air through the primary flow inlet.

In another embodiment, the air vent comprises a compressor arranged to increase pressure in the interior cavity, thereby to cause a flow of air through the primary flow inlet.
Utilising a compressor generates the air flow through the primary flow inlet. The air flowing through the primary flow inlet generates a low-pressure region, which causes a secondary flow through the middle of the annular primary flow inlet. Approximately 20% of the flow through the air vent is provided by the compressor and 80% generated by a low-pressure region at the secondary flow inlet. There is no noticeable air turbulence near the secondary flow inlet, meaning it can be placed near other passengers without causing disruption or discomfort.
Advantageously, this arrangement will draw air from the front of the cabin which may be cooler than the ambient temperature in the rear, as the air conditioning in typical vehicles is arranged to more efficiently cool the front of the cabin than the rear.
In a further embodiment of the present invention the air inlet for the compressor is on the lower half of the cabin of the vehicle. Having the inlet in the lower portion of the cabin makes it easier to conceal as it will be out of the normal eyeline for passengers.
In a further embodiment, the compressor is located within the centre console of the vehicle cabin.
The centre console may provide a convenient, spatially efficient, location for the compressor.
In a further embodiment, the Coanda surface is rotationally symmetrical about a central axis of the air vent. Having the Coanda surface be rotationally symmetrical around the central axis of the air vent provides for a similarly symmetrical air flow from the nozzle of the vent.
In a further embodiment, the air vent further comprises a substantially circular outlet, the outlet having a smaller diameter than the primary flow inlet.
The cone angle of the air flow from the vent is decided by the ratio of these diameters. By having the outlet smaller than the primary flow inlet the cone angle

is appropriate to have the jet provide cooling at a reasonable distance from the vent over an appropriate area.
In a further embodiment of the present invention the distance between the primary flow inlet and the outlet is between 3.5 cm and 7 cm.
In a further embodiment of the present invention the ratio of an inner diameter of the air vent to a length of the air vent is between 1.15 and 2.3.
In a further embodiment of the present invention the maximum diameter of the diverging portion of the nozzle is 1 to 2 mm larger than the maximum diameter of the converging portion of the nozzle. This provides a diverging-converging portion that has a net converging effect, thereby accelerating the flow passing through the diverging-converging portion.
In a further embodiment of the present invention the ratio of the diameter of the outlet to the diameter of the primary flow inlet is between 1.1 and 0.9. Optimizing the dimensions of the air vent allows for maximised energy and spatial efficiency as well as providing an air flow profile that improves passenger comfort.
In a further embodiment of the present invention the air vent is formed from two unitary moulded pieces. Using just two pieces to form the vent will make producing the vent cheap as well as making it more durable since there will be fewer small, detailed components that need to be assembled during manufacture and that may break off during use.
Another aspect of the present invention provides an air vent for a vehicle comprising a Coanda surface and an annular primary flow inlet arranged to direct flow over the Coanda surface, the air vent further comprising a converging nozzle downstream of the Coanda surface and a substantially circular outlet downstream of the converging nozzle, the outlet having a smaller diameter than the primary flow inlet.
An air vent arranged in this fashion provides a focussed and temporally stable flow of air which can be utilised to regulate the temperature of passengers of a vehicle.

In a further embodiment of the present invention the Coanda surface has a curved longitudinal cross section.
Another aspect of the present invention provides a component of a seat of a vehicle comprising an air vent, said air vent comprising a Coanda surface and an annular primary flow inlet arranged to direct a primary flow over the Coanda surface.
Providing the air vent within a component of a seat of a vehicle is an efficient method of providing more vents as the interior of a seat component often contains considerable dead space. Such a component of a seat would not cause discomfort to the occupant of the seat because the vent does not cause noticeable turbulent flow at the secondary flow inlet, and the vent is silent or nearly silent in operation.
In a further embodiment of the present invention the air vent provided in the headrest is the air vent provided in the preceding aspects or embodiments.
In a further embodiment, the air vent provided in a headrest is shaped as a hollow trapezoidal prism.
In a further embodiment of the present invention, the compressor for the vent located in a component of a seat is located proximate the bottom of the back rest of the seat.
In a further embodiment of the present invention, the air inlet for the compressor is located proximate the rear of the back rest of the seat, proximate the compressor.
According to another aspect of the invention, there is provided a vehicle comprising an air vent as claimed in any preceding claim.
In a further embodiment of the present invention the air vent is located in a component of a seat and is arranged to direct flow towards an occupant of a second or third row seat of the vehicle.
Providing the air vents in a component of a seat allows for a location for an air vent in front of passengers in the second-row seats.

In an embodiment, the seat component may be a head rest. Alternatively, the seat component may be a back rest. The vent may be provided in an upper portion of the back rest.
In a further embodiment of the present invention the air vent is located in a centre console of the vehicle and is arranged to direct flow towards an occupant of a second or third row seat of the vehicle.
Providing the air vents in the centre console may provide an air vent for a passenger in the middle seat or an auxiliary air vent for another passenger.
According to another aspect of the invention for which protection is sought there is provided a vehicle comprising an air vent or a seat component as described above. In an embodiment, the air vent is located in a portion of a seat and is arranged to direct flow towards an occupant of a second or third row seat of the vehicle. In an alternative embodiment, the air vent is located in a centre console of the vehicle and is arranged to direct flow towards an occupant of a second or third row seat of the vehicle.
According to another aspect of the invention for which protection is sought there is provided a vehicle cabin comprising an air vent or a seat component as described above.
Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS
One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which;
Figure 1 shows a view of an embodiment of the present invention with Coanda air vents in the backrests of the seats and a Coanda air vent attached to the centre console;
Figure 2 shows another view of an embodiment of the present invention showing air inlets for the compressor located on the seats and on the centre console;
Figure 3a shows another embodiment of the present invention, the secondary inlet, the Coanda surface and the nozzle of the vent;
Figure 3b shows a cross sectional view of an embodiment of the vent;
Figure 3c shows a detailed view of one embodiment of the primary flow inlet of the vent;
Figure 4 shows another embodiment of the present invention, with a compressor attached to the vent;
Figure 5a shows a wireframe view of an embodiment of the present invention, in which a Coanda vent is located in a headrest and the compressor is connected to the vent via the inside of the seat;
Figure 5b shows a cross sectional view of a seat which has a Coanda vent installed in the headrest;
Figure 6a shows a velocity profile of air moving through the Coanda air vent with a converging and diverging shape profile;
Figure 6b shows a velocity profile of air 1.2 metres away from the nozzle of the Coanda air vent with a converging and diverging shape profile;
Figure 7a shows a velocity profile of air moving through the Coanda air vent;
Figure 7b shows a velocity profile of air 1.2 metres away from the nozzle of the Coanda air vent; and

Figure 8 shows a vehicle, into which aspects and embodiments of the present invention are installed.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 shows an air vent 1 for a vehicle 100 mounted upon a centre console 2 of the vehicle 100 by means of a conduit 3, which allows air to be delivered from a compressor (not shown in figure 1) located in the centre console 2 to the air vent 1. Conduit 3 has an outer surface that forms a ball part of a ball and socket joint, with the socket being formed in the centre console 2. Accordingly, the conduit 3 allows directable motion of the air vent by allowing the vent to be rotated about three mutually perpendicular axes. The air vent 1 has an inner diameter in the range of 120mm, although it will be realised that in other embodiments other diameters may be used, for example 100 mm to 150 mm. Also shown is an air vent 4 in another embodiment of the invention, which has a different shape and is in the component of the seat 5 of the vehicle 100.
Figure 2 also shows an air vent 1 for a vehicle 100 mounted upon a centre console of a vehicle 2 by means of a conduit 3. The centre console shown in figure 2 also comprises an air inlet 6 and a user interface means 7 for an HVAC system which includes the vent 1. In the illustrated embodiment the user interface means comprises a rotary knob, but it will be understood that other user interface means such as a button or dial or combination thereof would also be suitable. The air inlet 6 is located in a side panel of the centre console 2 and a compressor (not shown in figure 2) is disposed between the air inlet 6 and the conduit 3. Also shown in figure 2 is another embodiment of the air vent 4, which has a trapezoidal shape and is in a component of a seat 5 of a vehicle 100. Specifically, the air vent 4 is located in a head rest 5b of the seat 5. The vent may be positioned such that a passenger of approximately average height sitting in the seat 5 would be able to rest their head on the headrest 5b. In other embodiments, the seat may comprise a separate headrest and back rest. Furthermore, the vent may be located in the back rest 5a rather than the headrest 5b.

A further user interface means 9 is also provided. The user interface means 9 may be used to control an HVAC system which includes the air vent 4. In the embodiment illustrated in figure 2 the user interface means 9 is a rotary knob, but it will be understood that other types of user interface means would also be suitable. Also shown in figure 2 is an air inlet section 8 on the seats 5. A compressor (not shown in figure 2) is arranged to pump air from the inlet section 8 to the vent 4.
Figure 3a shows a detailed view of the vent 1 which has a generally annular shape. Figure 3b shows a cross section of a vent 1 shown in figure 3a, and figure 3c shows an enlarged cross-sectional view of a portion of the vent 1, in which the cavity 35 and the primary flow inlet 10 can both be clearly seen.
Referring to figure 3a, this embodiment of the vent 1 has a substantially annular shape, with an annular primary flow inlet 10 located towards the rear of the vent and located away from the visible zone of the air vent from a user looking into the vent from the rear. The primary flow inlet emits air from the cavity 35, which is pressurised by the compressor 11. The inner surface of the air vent comprises a substantially curved surface 13 located adjacent the annular primary flow inlet. Air from the inlet 10 forms a flow attachment to the curved surface 13 according to the Coanda principle, the surface diverges and then converges in the accelerator surface 14 of the vent (as best seen in figure 3c). The accelerator surface 14 comprises a diverging portion followed by a converging portion and may be referred to as a diverging-converging section.
The accelerator surface 14 of the vent 1 is arranged such that the surface flow attachment is not broken and such that high pressure zones do not form. This helps to provide a temporally stable, focussed flow downstream from the vent 1. The guide surface 15 is downstream of the accelerator surface 14 and is parallel to the longitudinal axis of the air vent. The length of the guide surface in the present embodiment is greater than 8 mm. Downstream of the guide surface 15 is the flow separation surface 16 which diverges such that it forms a large angle (in some embodiments the angle may be greater than 50º) with respect to the guide surface 15 to promote flow separation. The outer surface 17 is orthogonal to the

guide surface 15 and forms the visible portion of the air vent. The total length of the air vent in this embodiment is 55 mm and may range from 40 to 80 mm.
Referring to figure 3b, pressurized air flows through the conduit 3 into the cavity 35, before entering the vent via the primary flow inlet 10. The air that flows through the primary flow inlet 10 attaches to the curved surface 13 according to the Coanda principle. The air flows downstream towards the guide surface 15 and then disengages from the vent at the flow separation surface 16. This causes a low-pressure zone within the lumen of the vent which draws air from the region of ambient pressure towards the rear of the vent at the secondary flow inlet 39. It will be understood that the lumen of the vent refers to the space inside the generally annular vent.
The arrows to the rear of the vent show the air flow direction caused by this low-pressure zone. This secondary flow combines with the primary flow to produce a substantially continuous flow through the opening 12. This flow continues, with substantially the same diameter as the opening as shown by the arrows passed the opening. The air flow will spread at larger distances forming a cone-shaped air flow profile.
Referring to figure 3c, the air vent comprises a hollow cavity 35. The cavity 35 is provided with pressurised air from the conduit 3 which is connected to the compressor 11. The inner surface of the vent comprises a substantially curved surface 13 located adjacent the annular primary flow inlet 10 and over which the air provided from the air source forms a flow attachment according to the Coanda principle, the surface also forms a converging surface leading the air flow to a diverging-converging surface 14, which may also be referred to as an accelerator surface. This diverging and then converging surface profile helps to produce a focussed, temporally stable flow profile downstream from the vent 1. The diverging and then converging surface has been observed to help to provide a temporally stable, focussed flow for a vent with a low ratio of outlet diameter to inlet diameter. For example, the ratio of outlet diameter to inlet diameter may be in the range of 0.9-1.1.

The guide surface 15 is substantially parallel about its rotational axis of symmetry although in some embodiments it may be convergent with an angle of convergence of 20º to 40º. An end of the surface 16 forms an aperture and has a large angle such that the surface attached air flow detaches rather than attaching to the outer surface 17. The angle of the flow separation surface 16 with respect to the guide surface 15 is large, in some embodiments it may be 50º or more.
Figure 4 shows an example of a compressor 11 which may be used to generate the primary flow in an air vent such as the vent shown in figure 1. The compressor is attached to the vent 1 via an air duct 20 and conduit 3. Also shown is a mounting bracket 18 for mounting the compressor 11 to a part of a vehicle 100. When the compressor 11 is activated, pressurised air flows through the air duct 20 and the conduit 3 and into the hollow cavity 35. Pressurised air from the hollow cavity 35 then flows through the annular primary flow inlet 10 and attaches the curved surface 13 due to the Coanda effect, thereby forming a Coanda attachment flow. The Coanda attachment flow continues downstream, flowing over the accelerator surface 14, which increases the air velocity by 20 – 25 %. The Coanda attachment flow then flows over the guide surface 15 which may be a converging surface. Finally, the Coanda attachment flow 40 disengages from the vent 1 as the flow separation surface 16 tapers divergently at a large angle, possibly more than 50º relative to the guide surface. This produces a cone-shaped air flow which diverges slightly such that at a distance of approximately 1.2m away from the vent the air cone is large enough to cover the face and neck of a user. The present inventors have recognised that a user feels a more noticeable cooling effect if air flow having a velocity over 0.7 m/s is provided around a region of bare skin such as their face and neck.
Figure 5a shows a wireframe view of a seat 5 for a vehicle 100 which comprises several components, including a back rest 5a and a head rest 5b. The back rest 5a comprises one or more air inlets 8, a compressor 11 and an air duct 20, wherein the compressor and the air duct are concealed within the seat 5. The head rest 5b comprises an air vent substantially as previously described except that it is substantially a hollow trapezoidal pyramid shape. The vent 4 in this embodiment

has a height of approximately 50 mm and a maximum width of approximately 150mm.
Figure 5b shows a cross section of the seat 5 shown in figure 5a as well as a detailed view of the trapezoidal shaped air vent 4. The secondary flow inlet 39 is disposed at the rear of the vent 4, which is the foreword facing part of the headrest 5b (relative to the normal direction of travel of the vehicle 100). The outlet 12 is disposed at the front of the vent 4 which is on the rearward facing part of the headrest 5b. Although the seat shown in figures 5a and 5b comprises a monolithic upright portion having both a headrest 5b and a backrest 5a, it will be understood that in other embodiments a seat may comprise a headrest that is removable from the rest of the upright portion. The headrest may have an adjustable height. In this case, an air vent 4 may be provided either in the headrest or in the back rest, especially the upper portion of the back rest.
Referring to the section detail part of figure 5b the air vent comprises a hollow cavity 35. The cavity 35 is provided with pressurised air from the conduit 20 which is connected to the compressor 11. The inner surface of the vent comprises a substantially curved surface 13 located adjacent the annular primary flow inlet 10 and over which the air provided from the air source forms a flow attachment according to the Coanda principle, the surface also forms a converging surface leading the air flow to a diverging and then converging surface 14, which may be referred to as an accelerator surface or a diverging-converging section. This diverging and then converging surface profile helps to provide a temporally stable, focussed air flow. The guide surface 15 is substantially straight, with parallel top and bottom surfaces. However, in some embodiments the guide surface may be convergent with an angle of convergence of up to 40º, for example between 20o and 40o. The flow separation surface 16 forms an aperture and has a large angle such that the surface attached air flow detaches rather than continuing to flow to the outer surface 17. The angle of the flow separation surface 16 with respect to the guide surface 15 is large, in some embodiments it may be larger than 50º. The total length of the vent 4 will depend on the seat 5 design.

In a further embodiment, the seat component in which the vent 4 is disposed is a back rest 5a of the seat 5. In an alternative embodiment, the seat component in which the vent 4 is disposed is a headrest 5b.
Figure 6a shows a velocity profile of one embodiment of the present invention in which the nozzle comprises a diverging portion downstream of the Coanda surface and a converging surface downstream of the diverging portion. Figure 6b shows a velocity profile from 1.2m away from the vent from the perspective of a user facing the vent, on a plane normal to the direction of air flow. In both of figures 6a and 6b, the velocity is shown in metres per second (m/s).
Figure 6a shows an air velocity profile for one embodiment of the air vent 1 in operation. It is an objective of this embodiment of the present invention to provide a focussed, temporally stable air flow at 1.2m away from the vent. Figure 6b shows the velocity profile at 1.2m away from the vent. The embodiment of the vent 1 shown in figure 6a comprises a conduit 3 which is connected to the hollow cavity 35. The annular primary flow outlet 12 is adjacent the hollow cavity 35 and allows the pressurized air to flow from the hollow cavity. This air flow generates a low-pressure volume on the interior of the vent such that air is drawn from the ambient air pressure region adjacent to the secondary flow inlet, in this way a large percentage of the total air flow is drawn from the ambient air, not the compressor. Advantageously, the secondary flow inlet 39 is larger than the outlet 12, such that air is drawn from a significantly larger volume of air, meaning that the pressure gradient near the secondary flow inlet is very small and imperceptible to a user, so the vent 4 can be installed into a headrest 5b to direct an air flow behind the seat 5 without causing discomfort to the user in that particular seat 5. The air forms a Coanda attachment flow 40 on the curved surface 13. The Coanda attachment flow then flows over the accelerator surface 14 which increases flow velocity at a distance of 1.2m from the vent by 20 – 25 %.
Downstream of the accelerator surface the air flows over the guide surface which is substantially parallel (i.e. it does not diverge or converge). In the embodiment shown here there is no flow separation surface 16, the nozzle merely ends with the outer surface 17. The total length of the vent from secondary flow inlet to outlet is

45 mm. The length of the Coanda attachment flow 40 after the annular primary inlet 10 is 36 mm. The length of the accelerator surface is 9 mm and diverges and converges at an angle of 8.5 degrees. The difference between the maximum diameter and the minimum diameter of the accelerator surface is 0.8 mm. The guide surface 15 is 15 mm long. These features lead to a cone angle for the air flow coming from the vent of 12 degrees.
Figure 6b shows the velocity profile in a plane orthogonal to the plane of the section illustrated figure 6a and at a distance of 1.2 m from the nozzle. At this distance, the jet flow will still be focussed, such that the cone angle between the vent 1 and the outer edges of the jet stream is low, between 6 and 10 degrees. A range of maximum velocities will be obtainable depending on the output of the compressor, with 0.5 m/s and 4 m/s being an obtainable range. The diameter of the jet flow at 1.2m from the nozzle will be 20 to 40 cm. At this diameter and velocity, the jet stream will be ideal for evaporating moisture from the skin of users, causing a cooling effect to keep skin at a comfortable temperature.
Figure 7 shows a velocity profile of another embodiment of the present invention in which the nozzle is substantially flat. Figure 7b shows a velocity profile from 1.2m away from the vent from the perspective of a user facing the vent.
In the embodiment of Figure 7a there is no accelerator surface and the guide surface is extended. The total length of the vent from secondary flow inlet to outlet is 40 mm. The length of the Coanda attachment flow 40 after the annular primary inlet 10 is 30 mm. The guide surface 15 is 15 mm long and converges at an angle of 30 degrees with respect to the central axis of the air vent 1. These features lead to a cone angle for the air flow coming from the vent of 6 to 10 degrees which makes the area of the air flow 300 to 700 cm2 at a distance of 1.2 m from the vent.
Figure 7b shows the velocity profile orthogonal to figure 7a at a distance of 1.2 m from the nozzle. In both of figures 7a and 7b, the velocity is shown in m/s.
Figures 6 and 7 both show results of simulations based on a primary air flow (i.e. the flow through the annular inlet) having a volume flow rate of 100 cubic metres

per hour (CMH). It will be understood that this may be somewhat higher than the flow rate that would be expected to be employed in normal use and may correspond to a maximum flow rate through the vent. Indeed, it is expected that in normal use the primary air flow may be in the range of 20-30 CMH or lower, and good cooling performance can be obtained at such flow rates. Furthermore, it is expected that the velocity profile observed at a flow rate of 20-30CMH may be similar to that observed at 100 CMH, albeit scaled accordingly. Simulations are shown at the maximum expected flow rate, as this is the condition considered most likely to show temporally-unstable flow features, which were not observed.
Figure 8 shows another embodiment of the invention comprising a vehicle 100 having one or more of the foregoing aspects and embodiments of the present invention.
As used herein the term “air vent” refers to any apparatus with an interior surface through which air may flow.
The term “downstream” refers to the direction of flow of the average flow direction of air during normal operation of the present invention.
The term “upstream” refers to the opposite direction to the average flow direction of air during normal operation of the present invention.
As used herein the term “Coanda surface” refers to any surface to which a jet of fluid can become entrained upon contact.
As used herein the term “annular primary flow inlet” refers to a breach or gap, through which fluid may flow, disposed around an interior surface of a vent.
As used herein the term “compressor” refers to any device for changing, varying or causing fluctuations in the pressure of a fluid in a volume, including but not limited to fans and blowers.
As used herein the term “nozzle” refers to a section of an object which affects the flow profile of a fluid flowing through it. It is not limited to objects that cause flow through them to diverge. The term “flow profile” includes but is not necessarily limited to the velocity, pressure gradients, pressure, density of the flowing fluid. The nozzle referred to herein may comprise any or all of the

following sections in any combination; a curved surface, an accelerator surface, a guide surface, a flow separation surface and an outer surface.
The term “guide surface” refers to a surface which does not significantly converge or diverge relative to upstream surfaces.
As used herein the term “accelerator surface” refers to a surface which diverges and then converges without necessarily being planar in between.
As used herein “user interface means” refers to a device via which a user may input commands, including but not limited to one or more buttons, a rotary knob, a GUI on a computer or tablet computer or a touch screen device.
As used herein “HVAC system” refers to a system which controls the heating, ventilation and air conditioning of an environment, such as a cabin of a vehicle.
Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.
Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including

any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

WE CLAIM
1. An air vent for a vehicle, the air vent comprising a Coanda surface and an
annular primary flow inlet arranged to direct a primary flow over the Coanda
surface,
the air vent further comprising a nozzle downstream of the Coanda surface, the nozzle comprising a diverging portion and a converging portion downstream of the diverging portion.
2. An air vent as claimed in claim 1, wherein the annular primary flow inlet is coupled to an interior cavity of the air vent.
3. An air vent as claimed in claim 2, further comprising a compressor arranged to increase pressure in the interior cavity, thereby to cause a flow of air through the primary flow inlet.
4. An air vent as claimed in claim 3 wherein the air inlet for the compressor is on the lower half of a cabin of the vehicle.
5. An air vent as claimed in claim 3 wherein the compressor is concealed within the centre console of the vehicle cabin.
6. An air vent as claimed in any preceding claim, wherein the Coanda surface is rotationally symmetrical about a central axis of the air vent.
7. An air vent as claimed in any preceding claim, wherein the air vent further comprises a substantially circular outlet, the outlet having a smaller diameter than the primary flow inlet.
8. An air vent as claimed in claim 7, wherein the distance between the primary flow inlet and the outlet is between 3.5 cm and 7 cm.

9. An air vent as claimed in claim 7 or claim 8 wherein the ratio of a diameter of the air vent to a length of the air vent is between 1.15 and 2.3.
10. An air vent as claimed in any one of claims 7-9 wherein the maximum diameter of the diverging portion of the nozzle is 1 to 2 mm larger than the maximum diameter of the converging portion of the nozzle.
11. An air vent as claimed in any one of claims 7-10 wherein the ratio of the diameter of the outlet to the diameter of the primary flow inlet is between 1.1 and 0.9.
12. An air vent as claimed in any preceding claim wherein the air vent is formed of two unitary moulded pieces.
13. An air vent for a vehicle comprising a Coanda surface and an annular
primary flow inlet arranged to direct flow over the Coanda surface,
the air vent further comprising a converging nozzle downstream of the Coanda surface and a substantially circular outlet downstream of the converging nozzle, the outlet having a smaller diameter than the primary flow inlet.
14. An air vent as claimed in claim 13, wherein the Coanda surface has a curved cross section.
15. A seat component for a seat of a vehicle comprising an air vent, said air vent comprising a Coanda surface and an annular primary flow inlet arranged to direct a primary flow over the Coanda surface.
16. The seat component of claim 15 wherein the air vent is the air vent of any of claims 1 to 14.
17. The seat component of claim 15 or claim 16 wherein the air vent is shaped as a hollow trapezoidal prism.

18. The seat component of claim 15 - 17 wherein there is a compressor located
proximate the bottom of the back rest of the seat.
19. The seat component of any of claims 15 – 18 wherein the air inlet for the
compressor is located proximate the rear of the back rest of the seat, proximate
said compressor.
20. The seat component of any of claims 15-19 wherein the seat component is a head rest.
21. The seat component of any of claims 15-19 wherein the seat component is a back rest.
22. A vehicle comprising an air vent as claimed in any of claims 1 – 14 or a seat component as claimed in any one of claims 15-21.
23. A vehicle as claimed in claim 22, wherein the air vent is located in a portion of a seat and is arranged to direct flow towards an occupant of a second or third row seat of the vehicle.
24. A vehicle as claimed in claim 22, wherein the air vent is located in a centre console of the vehicle and is arranged to direct flow towards an occupant of a second or third row seat of the vehicle.