Method and apparatus for generating an airflow for a vehicle

Abstract

Method for generating an airflow (1) to protect a vehicle (10) from precipitation, the method comprising the following steps: Capturing information, Generating the airflow (1), and Setting the direction of the airflow (1) depending on the information, where the collection of information includes recording the size of a person to be protected (14), and wherein the direction of the airflow (1) is adjusted depending on the size of the person (14) such that the airflow (1) flows over the person (14).

Description

[0001] The present invention relates to a method and a device for generating an airflow for a vehicle, in particular to protect the vehicle's occupants from precipitation.

[0002] JP 2004-058929 A2 discloses a device by which air is generally blown horizontally out of a door top edge to create a kind of air curtain for protection against rain.

[0003] DE 10 2011 102 213 A1 describes a motor vehicle in which an airflow is formed that extends continuously through a door opening and is directed outside the motor vehicle in order to prevent, for example, snow from entering the vehicle.

[0004] German patent application DE 10 2010 033 515 A1 discloses a device that prevents the ingress of foreign particles into a vehicle interior by briefly generating positive air pressure inside the vehicle. A key feature is that a monitoring device detects an anticipated opening of the vehicle door, for example, during the unlocking process, and then triggers the generation of positive air pressure, for instance, by the vehicle's own ventilation system. Activation can also optionally be conditional upon sensors, such as rain, temperature, or light sensors, having previously detected the presence of foreign particles on the vehicle.

[0005] Chinese utility model CN ​​202 944 185 U describes a rain protection device with airflow generation, consisting of an airflow generation unit, an automatic control switch, and a proximity sensor. The airflow generation unit creates a cascading airflow over a vehicle door. This cascading airflow covers the opening and closing area of ​​the vehicle door. The automatic control switch is mounted on the vehicle and connected to the airflow generation unit to automatically control its opening and closing. When the vehicle door is opened, as well as when entering and exiting the vehicle, the airflow generation unit creates a cascading airflow. This protects the opening and closing area of ​​the vehicle door from rain. The proximity sensor is connected to the automatic control switch.If the proximity sensor detects that the user is approaching the cascading airflow, the automatic control switch controls the airflow generation unit and stops the generation of the cascading airflow.

[0006] US Patent 6,290,361 B1 discloses a cleaning system for the exterior mirrors and side windows of a vehicle, which directs compressed warm air to an air distribution unit. This unit is equipped with multiple openings to direct the airflow onto the surface of the mirror or a side window. In one embodiment, the air compressor, air heater, and an optional air filter are located in the housing of the exterior mirror. In another embodiment, an additional air distribution unit is provided, which is mounted along the vehicle door to increase the coverage of the side window. In a further embodiment of the invention, the system is adjustable to allow for the optimal angle of the air openings to the mirror and the side window. It is also intended to be used in newly developed vehicles and to integrate the system components into the design of the vehicle door.Alternatively, additional components are described to allow existing vehicles to benefit from the system. Additional air distribution units can be connected to the main system to improve visibility throughout the vehicle.

[0007] US Patent 2011 / 0097985A1 describes an air shield located across a portal access opening between a vehicle access element and a stationary vehicle body panel. The vehicle access element provides access to the vehicle interior. An air supply device is located within the vehicle. This device generates a burst of air that is released when the vehicle access element is opened. An air concentrator device is in fluid communication with the air supply device. This device releases the burst of air, which forms the air shield, substantially transversely to the portal opening. The air shield extends over at least a portion of the circumference of the portal access opening between the vehicle access element and the stationary vehicle body panel. The air shield prevents precipitation from entering the vehicle interior during a pressure equalization phase that occurs after the vehicle access element is opened.

[0008] Based on the aforementioned prior art, the present invention aims to improve protection against precipitation by means of an airflow.

[0009] According to the invention, this problem is solved by a method for generating an airflow according to claim 1, by a device for generating an airflow according to claim 4, and by a vehicle according to claim 10. The dependent claims define preferred and advantageous embodiments of the present invention.

[0010] The present invention provides a method for a vehicle, wherein the airflow is used to protect the vehicle's occupants from precipitation. The airflow is generated, in particular, in the area of ​​a door, a tailgate, or an interior space (e.g., in convertibles) of a vehicle. The method according to the invention comprises the following steps: • Information acquisition. Information acquisition can occur, for example, when a vehicle occupant activates a control element and the information is provided and recorded. However, it is also possible for the information to be acquired using a sensor. • Generating the airflow. For example, compressed air is generated using a pump, which is then expelled as an airflow at a suitable location. • Adjusting the airflow direction depending on the information. The direction in which the airflow flows is determined and adjusted depending on the information. where the collection of information includes recording the size of a person to be protected, and the direction of the airflow is adjusted depending on the size of the person so that the airflow flows over the person.

[0011] Advantageously, by being able to adjust the direction of the airflow, this direction can be set automatically or manually, in contrast to the prior art, depending on the properties of the precipitation or on a person to be protected.

[0012] The airflow in the door area is generated to protect vehicle occupants from precipitation, especially when exiting the vehicle. Similarly, the airflow in the tailgate area is generated, particularly when the tailgate is open, to protect occupants from precipitation while loading or unloading the trunk. The airflow in the interior of the vehicle is intended for vehicles where the interior or passenger compartment is at least temporarily open, as is the case with convertibles. In this case, the airflow protects the occupants from precipitation, especially when the vehicle is traveling at speeds below a certain threshold (e.g., 70 km / h), which includes when the vehicle is stationary.

[0013] In particular, the information gathering can include determining the direction from which precipitation is striking the vehicle in that area. The direction of the airflow is then adjusted depending on the size of the person and / or the direction of the precipitation, so that the airflow both passes over the person and provides the best possible protection from the precipitation.

[0014] By adjusting the airflow direction according to the size of the person being protected, the airflow can be set at a greater angle to the horizontal for a taller person than for a shorter person. By taking the direction of precipitation into account, the airflow direction can advantageously be adjusted to provide the best possible protection for the person being protected. For example, the angle at which the airflow exits the vehicle can be set greater when the precipitation falls obliquely onto the side of the vehicle being protected than when the precipitation falls almost vertically.

[0015] According to the invention, the direction of the airflow can therefore be set manually, for example with the help of a suitable operating device, or automatically depending on the outputs of the sensor.

[0016] According to one embodiment of the invention, the approach of an object (for example, an occupant's hand) to the airflow is detected in the area of ​​an airflow outlet from the vehicle. The airflow from this outlet is then either no longer generated or is weakened when the corresponding approach has been detected.

[0017] By reducing or completely disabling the airflow at points where the approach of an object is detected, injuries from the airflow can be avoided.

[0018] Within the scope of the present invention, a device for generating an airflow to protect a vehicle from precipitation is also provided. The device comprises means for automatically generating the airflow, means for adjusting the direction of the airflow, and a control mechanism. The device is configured to allow the direction of the airflow to be adjusted by means of the control mechanism.

[0019] The device is specifically designed to generate airflow in the area of ​​a door, a tailgate or the interior of the vehicle.

[0020] In a similar manner to the method according to the invention, the device according to the invention is able to adjust the direction of the generated airflow, for example depending on properties of the precipitation or properties of the person to be protected, in order to improve protection against precipitation compared to the prior art.

[0021] According to the invention, it is possible that the direction in which the airflow flows is specified for the device, for example, by a corresponding operating instruction from an occupant of the vehicle (i.e., with the help of a corresponding control element of the vehicle).

[0022] However, according to the invention, it is also possible for the device to include a sensor, wherein the device is configured to adjust the direction of the airflow by means of the control system using the means for changing the direction of the airflow depending on an output of the sensor, wherein the sensor is configured to detect the size of a person to be protected, and wherein the device is configured to adjust the direction of the airflow by means of the control system using the means for changing the direction of the airflow depending on the size such that the airflow flows over the person.

[0023] This sensor can automatically detect properties of precipitation (e.g., precipitation volume, falling speed, or direction) or characteristics of the person being protected. The airflow direction can then be adjusted based on the sensor readings to provide optimal protection for the individual.

[0024] In a further embodiment of the invention, the sensor can be configured to detect a direction from which precipitation in the area strikes the vehicle, and the device is configured to adjust the direction of the airflow by means of the control system using the means for changing the direction of the airflow in such a way that the airflow protects the person from the precipitation.

[0025] By using the sensor, the direction of the airflow can advantageously be automatically adjusted to the size of the person to be protected and / or to the direction of the precipitation, in order to protect the person to be protected as optimally as possible from the precipitation.

[0026] Furthermore, the sensor can be designed to detect wind speed. In this case, the device is designed to generate the airflow only when the wind speed is below a predetermined threshold.

[0027] At high wind speeds, there is a very high risk that the airflow generated according to the invention will be directed by the wind towards the person to be protected. To avoid this, the airflow is not generated at excessively high wind speeds.

[0028] According to one embodiment of the invention, the device comprises one or more air outlets from which the airflow (i.e., a specific portion of the airflow) emerges, and at least one proximity sensor with which the approach of an object (for example, an occupant's hand) to the airflow in a region of one of these air outlets is detected. In this embodiment, the device is configured to reduce or completely deactivate the portion of the airflow from the respective outlet when the proximity sensor detects the approach of an object to that air outlet.

[0029] 3. By at least reducing the proportion of airflow from a particular air outlet when an object is detected approaching that outlet, injuries due to the airflow can advantageously be avoided.

[0030] According to the invention, it is possible for the means for generating the airflow to be located in the area of ​​the corresponding air outlets or in the area of ​​the corresponding air outlet. However, it is also possible for the means for generating the airflow to be arranged at some distance from the corresponding air outlet(s) in the vehicle, and for the airflow to be directed to the corresponding air outlet(s) via one or more channels.

[0031] The embodiment in which the airflow is directed via channels to the actual air outlet has advantages when the air outlet(s) are located in an area of ​​the vehicle where there is no installation space for accommodating the means for generating the airflow.

[0032] For adjusting the direction of the airflow, there are two particular variants according to the invention. Firstly, the means for changing the direction of the airflow can comprise a nozzle (or several nozzles) from which the airflow emerges and which can be changed or adjusted in its position or orientation to adjust the direction of the airflow. Secondly, the means for changing the direction of the airflow can comprise an air flap (or several air flaps) onto which the airflow from the nozzle(s) flows and which can also be changed or adjusted in its position or with respect to its angle of incidence to adjust the direction of the airflow. Of course, these two variants can also be combined. In this combination, the airflow emerges from a nozzle and encounters an air flap.By adjusting the nozzle, the direction of the airflow striking the air flap can be controlled. Conversely, the direction of the airflow exiting the air flap can be adjusted, depending on the direction of the airflow striking the air flap.

[0033] The variant of adjusting the airflow direction by means of a nozzle setting has the advantage that no air damper is required. The variant of adjusting the airflow direction by means of an air damper setting has the advantage that the air outlet from which the airflow exits towards the air damper can be mechanically simple, since the airflow direction is set by the corresponding adjustment of the air damper.

[0034] According to a further embodiment of the invention, the device comprises a guide rail. Nozzles are arranged side by side along the longitudinal direction of this guide rail, with a proximity sensor additionally arranged adjacent to each of these nozzles. In this embodiment, two variants exist for adjusting the direction of the airflow. In the first variant, the means for changing the direction of the airflow are designed such that they are able to pivot the entire guide rail in order to adjust the direction of the airflow. In other words, the guide rail can be rotated or pivoted about an axis of rotation extending in the longitudinal direction of the guide rail.In the second variant, the means for changing the direction of the airflow include an air flap towards which the airflow exiting the nozzles is directed and which can be changed in its position in order to adjust the direction of the airflow.

[0035] This compact design generates a planar airflow whose width corresponds to the length of the guide rail. Therefore, if the guide rail is positioned across the width of the vehicle at the end of the tailgate or at the top edge of the windshield, the airflow advantageously covers the entire width of the vehicle.

[0036] Within the scope of the present invention, a vehicle is also provided which has a device according to the invention.

[0037] According to one embodiment of the vehicle according to the invention, the device according to the invention has only one air outlet, which is located centrally in the upper area of ​​the tailgate when it is open. This single air outlet functions as a diffuser nozzle, distributing the airflow in a fan shape across the entire width of the tailgate into the area behind the vehicle.

[0038] Discharging the airflow through a single air outlet offers the advantage, compared to multiple outlets, of requiring less installation space for both the outlet itself and the airflow supply. Positioning the air outlet in the center of the tailgate still allows the airflow to effectively protect the entire area behind the vehicle from precipitation, spanning its entire width.

[0039] To distribute the airflow in a fan shape, the spreader nozzle can include ribs that extend outwards from the nozzle's air outlet in a star shape. More precisely, the extensions of the ribs intersect near or within the air outlet. When the tailgate is open, the ribs extend from the air outlet towards the rear of the vehicle.

[0040] The ribs are a relatively inexpensive way to direct the airflow in a fan shape to the area behind the vehicle.

[0041] According to another embodiment of the vehicle according to the invention, the device according to the invention comprises several air outlets which are arranged along an upper edge of the door, along an upper edge of the tailgate, or along an upper edge of a windshield of the vehicle. The air outlets are designed such that the airflow exiting the air outlets flows out in parallel partial airflows.

[0042] By creating an airflow that is essentially composed of several parallel air streams, the occupant located in the area of ​​the door, tailgate or interior of the vehicle can be protected almost optimally from precipitation if the air streams are generated essentially across the entire width of the door, tailgate or windshield.

[0043] If the air outlets are arranged along the upper edge of the windshield, it may be advantageous if the device according to the invention detects the speed of the vehicle and is designed in such a way that it only generates the airflow when the speed is below a predetermined speed threshold (e.g. 70 km / h).

[0044] When driving at high speed, the occupants of a convertible are also protected from precipitation by the wind. Therefore, it is advantageous to generate the airflow according to the invention only at low speeds or when the vehicle is stationary, for protection against precipitation.

[0045] If the airflow exits from multiple air outlets, only one air flap can be used to adjust the direction of the airflow, onto which the partial airflows of all air outlets impinge.

[0046] The present invention uses a focused airflow, for example at a flow velocity of 50–100 km / h (e.g., 70 km / h), to create a stable and virtually impervious protective barrier capable of repelling precipitation, such as rain. By optimally adjusting the angle at which the airflow flows, the rain absorption area created by the airflow can also be optimally designed to protect a vehicle occupant. In addition to protecting the occupant, the present invention has the further advantage that the airflow prevents precipitation from entering the vehicle interior.

[0047] The present invention is particularly suitable for use in motor vehicles. Of course, the present invention is not limited to this preferred application area, as it can also be used, for example, in ships, aircraft, and rail-bound or track-guided vehicles. Furthermore, the present invention can also be used in stationary installations, for example, to generate an airflow in the area of ​​an exterior door of a building.

[0048] The present invention will now be described in detail with reference to the figures and to preferred embodiments according to the invention. In Fig. Figure 1 shows the generation of an airflow in the area of ​​a side door of a vehicle according to the invention. In Fig. Figure 2 shows the generation of an airflow in the area of ​​a tailgate of a vehicle according to the invention. In Fig. 3. The generation of the airflow from the Fig. 2 shown in detail. In Fig. 4. The generation of the airflow from the Fig. 2 is presented in the form of a different variant from a different perspective. In Fig. Figure 5 shows a guide rail with integrated air nozzles and sensors to generate an airflow. In Fig. 6 is the one in Fig. 5 Guide rail shown in cross-section as a variant. In Fig. Figure 7 shows the generation of an airflow for a convertible according to the invention. Fig. Figure 8 schematically shows a vehicle according to the invention with a device according to the invention for generating an airflow.

[0049] In Fig. Figure 1 shows a vehicle 10 according to the invention with a side door 13. Several adjustable nozzles 2 are located in the upper edge 3 of the door 13 to generate an airflow 1. The nozzles 2 are designed and adjusted such that, when the door 3 is open, they generate the airflow 1 obliquely upwards towards the rest of the vehicle 10. The direction in which the nozzles 2 generate the airflow 1 is adjusted such that an occupant exiting or entering the vehicle 10 is optimally protected from precipitation 11.

[0050] At the in Fig. In the embodiment shown in Figure 1, the nozzles 2 are pivotable about a rotation axis running parallel to the upper edge 3 of the door 13, so that the direction of the airflow 1 can be adjusted over an angular range 12.

[0051] In Fig. Figure 2 shows a vehicle 10 according to the invention with a tailgate 15. In this embodiment, the airflow 1 is generated from an upper area of ​​the tailgate 15 when it is open, in order to protect a person 14 from precipitation 11 when loading or unloading the trunk of the vehicle 10.

[0052] Based on the Fig. 2. A variant of the invention can be explained. If the size of the person 14 is detected by means of a sensor, the direction of the airflow 1 can be adjusted so that the airflow 1 flows as close as possible (for example, at a distance of no more than 30 cm) over the head of the person 14 in order to protect the person 14 as optimally as possible from the precipitation 11.

[0053] In Fig. 3 is the embodiment from the Fig. Figure 2 shows a detailed illustration of a variant according to the invention. It can be seen that the airflow 1 exits from an air outlet below a logo 16 and then impinges on an air flap 6, which is used to adjust the direction of the airflow 1. To adjust the direction of the airflow 1, the angle 22 that the air flap 6 has relative to the rear area of ​​the tailgate 15 is adjusted accordingly. In this embodiment, the airflow 1 exits only from the air outlet below the logo 16 and is then distributed in a fan shape (for example, with the aid of guide ribs) across the entire width of the vehicle 10. By a corresponding pivoting movement of the logo 16, the air outlet can be opened or closed when no airflow 1 is required.

[0054] In Fig. 4 is another variant of the in Fig. The embodiment shown in Figure 2 is illustrated. In this variant, the airflow is generated with a nozzle 2 which is movable about an axis of rotation in the lateral direction of the vehicle 10, whereby the direction of the airflow 1 can be adjusted over an angular range 12.

[0055] In Fig. Figure 5 shows a further embodiment of the invention in the form of a guide rail 9. Several nozzles 2 and proximity sensors 8 adjacent to each nozzle are arranged along the longitudinal direction of this guide rail 9. An air damper 6 is provided to adjust the direction of the airflow 1 exiting the nozzles 2. The guide rail 9 is designed such that the airflow 1 exiting the nozzles 2 strikes the air damper 6. The air damper 6 is adjusted relative to the guide rail 9 to adjust the direction of the airflow 1.

[0056] At the in Fig. In the embodiment shown in Figure 5, there is exactly one air flap 6 for all nozzles 2. However, according to the invention, it is also possible that several air flaps 6 are present, so that with the help of one of these air flaps only a corresponding partial airflow, which exits from the nozzles 2 assigned to this air flap, is adjusted with regard to its direction.

[0057] If one of the proximity sensors 8 detects the approach of an object, for example the hand 7 or the head of a person, a partial airflow which is located adjacent to the respective proximity sensor 8 that detects this approach is switched off or at least weakened in order to avoid injury.

[0058] The in Fig. The guide rail 9 shown in Figure 5 can be inserted into the upper edge 3 of the door 13, into the upper edge 4 of the tailgate 15 or into the upper edge 5 of the windscreen 17 of a vehicle 10 according to the invention.

[0059] In Fig. 6 is a variant of the in Fig. The guide rail 9 shown in section 5 is depicted. In this variant, the entire guide rail 9 is pivoted about a rotation axis running in the longitudinal direction of the guide rail 9 to adjust the direction of the airflow 1. This allows the direction of the airflow 1 to be adjusted within the angular range 12 shown.

[0060] In Fig. Figure 7 shows a vehicle 10 according to the invention as a convertible. In this embodiment, the airflow 1 exits from the upper edge 5 of the windshield 17 of the vehicle 10 in order to protect the occupants 14 of the vehicle 10 from precipitation at low speeds or when the vehicle 10 is stationary.

[0061] Finally, in Fig.Figure 8 schematically shows a vehicle 10 according to the invention, which comprises a device 20 according to the invention. The device 20 according to the invention in turn comprises a control unit 18, a sensor 19, a pump 21 for generating compressed air, and an air flap 6 for adjusting the direction of the airflow 1 generated by the pump 21. Reference symbol list 1 Airflow 2 nozzles 3 Top edge of a door 4 Top edge of a tailgate 5 Top edge of a windshield 6 Air flap 7 Hand 8 Proximity sensor 9 Guide rail 10 vehicles 11 rain 12 rotation angles 13 Door 14 people 15 Tailgate 16 Logo 17 Windscreen 18 Control 19 Sensor 20 Device 21 Pump 22 angles

Claims

[1] Method for generating an airflow (1) to protect a vehicle (10) from precipitation, the method comprising the following steps: Capturing information, Generating the airflow (1), and Setting the direction of the airflow (1) depending on the information, where the acquisition of the information includes the acquisition of a size of a person to be protected (14), and wherein the direction of the airflow (1) is adjusted depending on the size of the person (14) such that the airflow (1) flows over the person (14). [2] Method according to claim 1, characterized by , that the acquisition of the information includes the acquisition of a direction from which the precipitation (11) strikes the vehicle (10), and that the direction of the airflow (1) is adjusted depending on the direction of the precipitation (11) such that the airflow (1) protects the person (14) from the precipitation (11). [3] Method according to claim 1 or 2, characterized by , that an approach of an object (7) to the airflow (1) is detected in an area of ​​an outlet of the airflow (1), and that the airflow (1) from the outlet is at least reduced when such an approach is detected. [4] Device for generating an airflow (1) to protect a vehicle (10) from precipitation wherein the device (20) comprises means (21) for automatically generating the airflow, means (2; 6) for changing a direction of the airflow and a control (18), wherein the device (20) is configured to adjust a direction of the airflow (1) by means of the control (18) by means of the means (2; 6) for changing the direction of the airflow (1), wherein the device (20) comprises a sensor (19), wherein the device (20) is configured to adjust the direction of the airflow (1) by means of the control (18) using the means (2; 6) for changing the direction of the airflow (1) depending on an output of the sensor. (19), wherein the sensor (19) is designed to detect the size of a person (14) to be protected, and wherein the device (20) is designed to adjust the direction of the airflow (1) by means of the control (18) using the means (2; 6) for changing the direction of the airflow (1) depending on the size such that the airflow (1) flows over the person (14). [5] Device according to claim 4, characterized by , that the sensor (19) is designed to detect a direction from which precipitation (11) strikes the vehicle (10), and that the device (20) is designed to adjust the direction of the airflow (1) by means of the control (18) using the means (2; 6) for changing the direction of the airflow (1) depending on the direction such that the airflow (1) protects the person (14) from the precipitation (11). [6] Device according to claim 4 or 5, characterized by , that the sensor (19) is designed to detect wind speed, and that the device (20) is designed to generate the airflow (1) only when the wind speed is below a predetermined wind speed. [7] Device according to one of claims 4-6, characterized by , that the device (20) comprises at least one air outlet from which the airflow (1) exits, and a proximity sensor (8) which is designed to detect an approach of an object (7) to the airflow (1) in an area of ​​one of the air outlets, and that the device (20) is designed to at least reduce the airflow (1) from the respective air outlet when the proximity sensor (8) detects the approach. [8] Device according to one of claims 4-7, characterized by , that the means for changing the direction of the airflow (1) comprise a nozzle (2) from which the airflow (1) exits and which is adjustable in its position in order to adjust the direction of the airflow (1), and / or that the means for changing the direction of the airflow (1) include an air flap (6) which can be changed in its position in order to adjust the direction of the airflow (1). [9] Device according to one of claims 4-7, characterized by , that the device (20) comprises a guide rail (9) in which several nozzles (2) and a proximity sensor (8) adjacent to each nozzle (2) are arranged in a longitudinal direction of the guide rail (9), and that the means for changing the direction of the airflow (1) are designed to pivot the guide rail accordingly, or that the means for changing the direction of the airflow (1) comprise an air flap (6) which is adjustable in its position in order to adjust the direction of the airflow (1). [10] Vehicle with a device (10) according to one of claims 4-9. [11] Vehicle according to claim 10, characterized by , that the device (20) comprises only one air outlet, which is arranged centrally in the area of ​​the tailgate (15), and that the air outlet acts as a spreading nozzle (2) to distribute the airflow (1) in a fan shape over the entire width of the tailgate (15). [12] Vehicle according to claim 11, characterized by , that the spreading nozzle (2) includes ribs which extend outwards in a star shape from an air outlet of the spreading nozzle (2) in order to distribute the airflow (1) in a fan shape. [13] Vehicle according to claim 11 or 12, characterized by , that the device (20) comprises several air outlets arranged along an upper edge (3) of the door (13), along an upper edge (4) of the tailgate (15) or along an upper edge (5) of a windscreen (17) of the vehicle (10), and that the air outlets are designed such that air streams (1) exiting the air outlets run parallel. [14] Vehicle according to claim 13, characterized by , that the air outlets are arranged along the upper edge (5) of the windscreen (17), that the device (20) is designed to detect the speed of the vehicle (10), and that the device (20) is designed to generate the airflow (1) only when the velocity is below a predetermined velocity.

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