Air ventilator with non-return valve and filter for leading replacement air into a room

Abstract

 The invention is an air ventilator (2) which comprises an air inlet (2.1), an air outlet (2.2), and an air channel (2.3) to enable air flow between the air inlet (2.1) and the air outlet (2.2). The air ventilator (2) also comprises a backflow trap (1) for preventing air flowing to a backwards direction in the air channel (2.3). The air ventilator (2) further comprises a first section (2.7) and a second section (2.8). The first section (2.7) having a first height (h1) comprises channelling means (2.9) for controlling the direction of the air flow in the air channel (2.3). The height (h2) of the second section (2.8) is greater that the height (h1) of the first section (2.7). The second section (2.8) comprises a filter (9) for filtering impurities from the air flowing through the air channel (2.3).

Description

Field of the Invention

[0001] The present invention relates to an air ventilator which comprises a air inlet, an air outlet, and an air channel to enable air flow between the air inlet and the air outlet.

Background of the Invention

[0002] Air ventilators are known which can be used to input replacement air from outside to a room to improve the air quality in the room. Air ventilators are known which can be installed above a window, either in the frame of the window or in a narrow space (slit) just above the frame of the window. These kinds of air ventilators usually have an internal air channel for guiding the incoming air to a certain direction in the room when the air leaves the air ventilator. The direction is e.g. partly upwards and partly sidewards from the window so that the air flow is not perpendicular to the plane of the window. For example, the publication EP 0 801 275 discloses such an air ventilator which can be installed in a narrow slit above a window.

[0003] The above described air ventilators do not have fans or other means which would force the air to flow from outside to the room. The operation of such air ventilators is based on a pressure difference between the room and the outside air. When there is an underpressure in the room, that is, the air pressure in the room is lower than the pressure of the outside air, air flows through the air ventilator from outside to inside the room. The underpressure is typically generated in the room by an exhaust fan which suctions air from the room to outside. However, sometimes it may happen that the pressure difference between the room and the outside air becomes very low or it may even happen that the room will become overpressurized with respect to the outside i.e. the air pressure in the room is greater than the air pressure outside the room.

[0004] The publication EP 1 988 341 discloses a backflow protection apparatus for an air ventilator. The backflow protection apparatus prevents or reduces the amount of air flowing through the air ventilator from the room to the outside air.

[0005] In the above types of air ventilators the height of the air channel is quite low which may affect that the air filters of the air ventilators may resist the air flow through the ventilator to the room. The filters are needed to prevent impurities of the air flow from entering the room.

Summary of the Invention

[0006] An aim of the present invention is to provide an air ventilator in which the filter has less resistance to the air flow compared to the air ventilators of prior art. The invention is based on the idea that the air channel of the air ventilator has a higher section in which the filter is positioned. Therefore, the cross section of the filter can be enlarged which reduces the resistive effect of the filter against the air flow but still keeping the filtering properties of the filter at an appropriate level.

[0007] According to a first aspect of the present invention there is provided an air ventilator which comprises an air inlet, an air outlet, an air channel to enable air flow between the air inlet and the air outlet, and a backflow trap for preventing air flowing to a backwards direction in the air channel, characterised in that the air ventilator comprises:

• a first section comprising channelling means for controlling the direction of the air flow in the air channel, and said first section having a certain height; and
• a second section in which the height is higher than the height of the first section, and the second section comprises a filter for filtering impurities from the air flowing through the air channel.

[0008] According to a first advantageous embodiment of the present invention the second section comprises a sheet-like support for the backflow trap which reduces the cross section of the air channel in the second section to increase the speed of the air flowing out from the air ventilator and to maintain the sound absorption properties of the air ventilator at a good enough level.

[0009] The air ventilator according to the present invention improves the operation of air ventilators of prior art by keeping the overall air flow resistance of the air ventilator at a low level and still enabling good filtering properties and sound absorption properties. In addition, the backflow trap of the air ventilator is also operating at a very low pressure differences and still prevents or at least reduces the backflow through the air ventilator.

[0010] The air ventilator according to the present invention can be installed, for example, in a slit above a window or above a casing of a drawable blind curtain which can be installed above a window.

Description of the Drawings

[0011] In the following the present invention will be described in more detail with reference to the attached drawings in which

Fig. 1

depicts a wall of a room and an air ventilator installed in a slit above a window of the room,

Fig. 2

depicts a wall of a room and an air ventilator installed above a casing of a mechanism of a drawable curtain of a window of the room,

Fig. 3

depicts from the above a first embodiment of the air ventilator of the present invention and a cross-sectional side view of air ventilator at the location I-I,

Fig. 4

depicts a cross-sectional side view of the backflow trap according to the present invention installed in a slit above a window,

Fig. 5

depicts a cross-sectional side view of the first embodiment of the backflow trap according to the present invention installed above the casing of the mechanism of the draw curtain,

Figs. 6a-6c

depict some details of the operation of the backflow trap according to the present invention,

Fig. 7

shows as a perspective view an example of the backflow trap of the air ventilator, and

Fig. 8

shows a cross-sectional view of an inlet of the air ventilator according to another example embodiment of the present invention.

Detailed Description of the Invention

[0012] In the following, the structure of an example embodiment of an air ventilator 2 according to the present invention will be described in more detail with reference to Fig. 3. The air ventilator 2 comprises a air inlet 2.1 and one or more air channels 2.3 between the air inlet 2.1 and an air outlet 2.2. An example embodiment of the air channels 2.3 are shown in Fig. 3. The air inlet can comprise a wall 2.1.1 which protects the air ventilator 2 from water due to e.g. rain and also defines together with e.g. the window frame a perimeter of the air inlet.

[0013] The air ventilator has a first section 2.7 and a second section 2.8. The first section 2.7 comprises at least part of said one or more air channels 2.3. The first section 2.7 has a certain height h1 so that the air ventilator 2 can be installed above a window 3, e.g. in the narrow slit between the upper part of the window and the upper side of the opening which is made into the wall 4 of the room. The first section 2.7 comprises channelling means 2.9 for controlling the direction of the air flow in the air channel. the shape of the channelling means 2.9 is advantageously such that the air channels 2.3 diverge from each other in the direction of the air flow in the air channels 2.3 as can be seen from Fig. 3. However, the height of the channelling means 2.9 is advantageously not the same than the height of the first section 2.7 but slightly less. Although a small portion of the air flowing through the air ventilator 2 can traverse above the channelling means 2.9, it does not deteriorate the operation of the air ventilator but can even improve the operation of the air ventilator. This is due to the fact that a little bit more air can flow through the air ventilator 2 but still the direction of the flow which traverses in the air channels 2.3, i.e. in the space between the channelling means 2.9, determines the direction of the flow of the air at the air outlet 2.2.

[0014] The second section 2.8 of the air ventilator comprises the backflow trap 1 and the filter 5. The height h2 of the second section 2.8 is greater than the height h1 of the first section 2.7. This has the effect that the speed of the air flow slightly reduces but the cross section of the filter 5 can be made larger compared to the situation in which the height of the second section 2.8 were the same than the height of the first section 2.7. Hence, the filtering efficiency can be improved and the air flow resistance of the filter can be reduced.

[0015] The second section 2.8 also comprises a first support element 2.10 for the backflow trap 1. The first support element 2.10 is preferably a sheet like structure which is fixed to the upper wall 2.8.1 of the second section 2.8 so that no air can flow between the first support element 2.10 and the upper wall 2.8.1 of the second section 2.8. The length of the first support element 2.10 is advantageously the same or slightly less than the width w2 of the cross section of the second section 2.8. The first support element 2.10 has also the effect that the cross section of the air channel in the second section is reduced by the first support element 2.10. Preferably, the area of the cross section of the second section 2.8 is smaller at the location of the first support element 2.10 than at the location of the filter 9. Hence, the speed of the air flow increases before it leaves the air ventilator 2 via the air outlet 2.2. This prevents the air flow from turning downwards at or immediately after the air outlet 2.2. This kind of effect in which the air flow would turn downwards might cause a feeling of draft to persons which are in the room near the window 3. The air ventilator 2 of the present invention directs the air upwards, not downwards, so that the air flow traverses near the roof of the room before it begins to fall downwards farther from the window. Further, the structure of the air channel 2.3 inside the air ventilator makes the air flow spreading at least slightly sidewards further improving the distribution of the air inside the room wherein the air flow is not perpendicular with respect to the plane of the window.

[0016] The backflow trap 1 is a sheet like element preferably made of a thin plastic sheet or a thin metal sheet. The air channel in the air outlet 2.2 of the air ventilator 2 has a rectangular form in such a way that the height of the air channel is smaller than the width of the air channel. Therefore, the backflow trap 1 is a rectangular element so that the length of the backflow trap 1 is almost the same than the width of the air channel in the air outlet 2.2 of the air ventilator 2 and the width of the backflow trap 1 is greater than the height of the air channel in the air outlet 2.2 of the air ventilator 2. Hence, the backflow trap 1 can totally, or almost totally close the air channel inside the air outlet 2.2 of the air ventilator 2 to effectively prevent backflow through the air ventilator 2. This will be discussed in more detail below in this specification. An example of the backflow trap 1 is illustrated in Fig. 7.

[0017] The backflow trap 1 can be curved in the width direction of the backflow trap 1 i.e. the cross section of the backflow trap 1 is convex when looked at one narrower side of the backflow trap 1.

[0018] The second section 2.8 can also have a second support element 1.3 which can be used as a guidance for the installation of the backflow trap 1. The first 2.10 and the second support elements 2.11 also keep the backflow trap 1 in proper position with respect to the air channel of the air outlet 2.2 of the air ventilator 2. The first support element 2.10 prevents one edge 1.1 of the backflow trap 1 dropping down when the backflow protection apparatus 1 has been installed in the air outlet 2.2 of the air ventilator 2. The backflow trap 1 is adapted to be rotatable e.g. by tilting with respect to the first support element 2.10 by the air flowing from the air inlet 2.1 to the air outlet 2.2 of the air ventilator 2. Preferably, the backflow trap 1 is adapted to be movable between a first position and a second position. In the first position (Figs. 6a and 6c) the air channel of the outlet 2.2 of the air ventilator 2 is substantially closed and in the second position the air channel of the outlet 2.2 of the air ventilator 2 is open so that air can flow from the air channel 2.3 of the air ventilator 2 through the outlet 2.2. to the room.

[0019] Preferably, the backflow trap 1 is not fixed to the air ventilator 2, which enables the backflow trap 1 to move easily in the air ventilator 2. The backflow trap 1 can be installed to the air ventilator 2 at the manufacturing stage of the air ventilator 2. Therefore, the second support element 2.11 can prevent the backflow trap 1 from falling away from the air ventilator 2 when the air ventilator 2 is not yet installed to the wall. This can be achieved by, for example, using rivets as the second support elements 2.11 and drilling holes through the backflow trap 1 through which the rivets can be installed. The diameter of the holes is greater than the diameter of the rivets so that the rivets do not prevent the backflow trap 1 from moving between the first and the second position.

[0020] When the air pressure inside the room is lower than the outlet air pressure i.e. the room is underpressurized, the air flows from outside to the air channel 2.3 through the air inlet 2.1 or through the second air inlet 2.4. From the air channel 2.3 the air flows to the air outlet 2.2 and reaches the backflow trap 1 as shown by the arrow F1 in Fig. 6a. The force caused by air flow F1 makes the trailing edge 1.2 of the backflow trap 1 to rise thus opening the air channel of the air outlet 2.2.

[0021] In a situation in which the pressure difference between outside and indoors is almost zero, there is no air flow in the air ventilator 2, or the air flow is very weak. Hence, the backwards trap 1 returns to the rest position i.e. the trailing edge 1.2 is resting on the lower wall 2.8.2 of the second section 2.8 of the air ventilator 2. This closes the air channel of the air outlet 2.2 of the air ventilator 2. If the room becomes overpressurized, i.e. the air pressure in the room becomes greater than the air pressure outside, the air attempts to flow backwards (arrow F2 in Fig. 6c) from the air outlet 2.1 to the air inlet 2.1, 2.4. However, because the backflow trap 1 closes the air channel inside the air outlet 2.2, air cannot flow to the air channel 2.3 of the air ventilator 2 thus backflow is prevented. The curved form of the backflow trap 1 now improves the tightness of the backflow trap 1 because the air flow coming from the room in the air outlet 2.2 pushes the trailing edge 1.2 of the backflow trap 1 towards the lower wall 2.8.2 of the first support element of the air ventilator 2. The first support element 2.10 can be formed as a separate piece which is attached to the upper wall 2.8.1 of the second section 2.8 e.g. by rivets or by welding. In another embodiment the first support element 2.10 is formed by punching a U-shaped slit on the upper wall 2.8.1 of the second section 2.8 and then bending the U-shaped part of the wall so that it forms a kind of a shelf on which one edge of the backflow trap 1 can be supported. However, these are not the only possibilities to form the first support element 2.10 for the backflow trap 1.

[0022] The air ventilator 2 of the present invention can be installed in a slit above the window 3 i.e. between a window frame and the upper edge of the opening in the wall of the room as is disclosed in Figs. 1, 3 and 4. It is also possible that a slit is made to the window frame wherein the air ventilator 2 can also be installed in the slit of the window frame.

[0023] In some situations there may be a drawable curtain installed in front of the window, outside the room. This kind of curtain can be drawn ahead of the window to e.g. prevent sunlight entering the room. This kind of a curtain has a mechanism 10.2 inside a casing 10.1 which can be installed above the window 3 or which is a part of the window 3. Therefore, the air ventilator 2 of the present invention can also be installed directly at the top of the casing 10.1 of the curtain 10 as illustrated in Figs. 2 and 5.

[0024] In another embodiment the air inlet 2.1 of the air ventilator may also comprise channelling means (not shown) to provide some directionality to the air which enters the air ventilator.

[0025] In Fig. 8 yet another embodiment of the air inlet 2.1 of the air ventilator is depicted as a cross-sectional view. In this embodiment the air inlet 2.1 comprises a first wall 2.1.1 and a second wall 2.1.2 which define the peripheral for the air flow through the air inlet 2.1. The first wall 2.1.2 is nearer to the window than the second wall 2.1.2 and the cross section of the first wall 2.1.1 has an L-shape which forms preferably a 90 degrees angle a (i.e. a first angle) as can be seen from Fig. 8. The second wall 2.1.2, which is farther from the window, is also formed in such a way that the cross section of the second wall 2.1.2 has L-shape. However, the angle β of this L-shape (i.e. a second angle) is less than 90 degrees.

[0026] The air inlet 2.1 has a small overhang 2.1.3 preferably at the angle of the first wall 2.1.1. The overhang 2.1.3 is directed towards the second wall 2.1.2. This overhang 2.1.3 is provided to prevent or at least hinder water from entering the air channel 2.3 of the air ventilator through the air inlet 2.1. For example, when it is raining and windy, the wind may cause that rainwater may flow on the surface of the first wall 2.1.1 of the air inlet upwards. When rainwater hits the overhang 2.1.3, rainwater cannot easily circumvent the overhang 2.1.3.

[0027] The overhang 2.1.3 reduces the cross-sectional area of the air inlet at some amount. Therefore, the angle of the second wall 2.1.2 is preferably less than 90 degrees. Another purpose for the angle being less than 90 degrees is to further hinder water entering the air channel 2.3 of the air ventilator 2.1.

[0028] In the following some non-limiting examples of some dimensions of the air ventilator 2 of the present invention are provided. For example, the dimension of the air inlet 2.1 is about 9 mm in horizontal direction and 300-1800 mm in vertical direction, preferably 9 mm x 600 mm. The height of the first section 2.7 i.e. the first height h1 is, for example, 9 mm and the height of the second section 2.8 i.e. the second height h2 is, for example, 12 mm. The protrusion of the overhang 2.1.3 is preferably between 3 and 5 mm. It is obvious that the invention is not limited to these dimensions but also other dimensions are applicable.

Claims

1. An air ventilator (2) which comprises an air inlet (2.1), an air outlet (2.2), and an air channel (2.3) to enable air flow between the air inlet (2.1) and the air outlet (2.2), and a backflow trap (1) for preventing air flowing to a backwards direction in the air channel (2.3),
characterised in that the air ventilator (2) comprises:

- a first section (2.7) comprising channelling means (2.9) for controlling the direction of the air flow in the air channel (2.3), and said first section (2.7) having a first height (h1); and

- a second section (2.8) having a second height (h2) which is higher than the first height (h1), and the second section (2.8) comprises a filter (9) for filtering impurities from the air flowing through the air channel (2.3).

2. An air ventilator (2) according to claim 1, characterised in that the backflow trap (1) is adapted to be tiltable by air flowing from the air inlet (2.1) to the air outlet (2.2) of the air ventilator (2).

3. An air ventilator (2) according to claim 1 or 2, characterised in that the second section (2.8) comprises a first support element (2.10) for supporting a first edge (1) of the backflow trap (1).

4. An air ventilator (2) according to claim 3, characterised in that the length of the first support element (2.10) is equal to the width (w2) of the second section (2.8).

5. An air ventilator (2) according to claims 3 or 4, characterised in that the area of the cross section of the second section (2.8) is smaller at the location of the first support element (2.10) than at the location of the filter (9).

6. A window (3) comprising an air ventilator (1) according to any of the claims 1 to 5.

7. A window (3) according to claim 6, characterised in that the window (3) comprises a curtain (10) having a casing (10.1), wherein the air ventilator (2) is fixed on top of the casing (10.1).

8. A window (3) according to any of the claims 1 to 7, characterised in that the air inlet (2.1) comprises a first wall (2.1.1) and a second wall (2.1.2) both having an L-shaped cross section, wherein the first wall (2.1.1) is formed to have a first angle (α) which is 90 degrees, and the second wall (2.1.1) is formed to have a second angle (β) which is less than 90 degrees.

Drawing