EP2052191B1 - Air flap for controlling flow within a conduit - Google Patents

Description

Technical area

The invention relates to a device for controlling an air flow in a ventilation pipe, comprising a pivotable air damper, which can take adjustable open positions and which prevents the air flow in the vent pipe in a closed position, and coupled to the air damper drive for pivoting the air damper, wherein the Drive is arranged inside the ventilation pipe.

State of the art

The term "ventilation pipe with cross-sectionally continuous pipe wall" is used in particular for pipes of inside round or elliptical cross-section. Ventilation systems are used in buildings, in particular residential, office, commercial and industrial buildings and tunnels, usually combined with fire and smoke protection equipment, but also in the automotive industry. In contrast, a rectangular cross-section is not "continuous" in the sense of this definition.

In ventilation systems, the volume flow control with pivoting air dampers plays an essential role. The volumetric flow is measured with a suitable measuring instrument, for example with a NMV-D2M from Belimo Automation AG, CH-8340 Hinwil designed as a compact unit of drive, pressure sensor and controller, which device enables the display of the volume flow in m ³ / h. This considerably simplifies the regulation and optimization of the ventilation system and enables lower operating costs.

The geometric shape of the planar louvers is adapted to the geometric pipe cross-section, particularly suitable is a round, elliptical or rectangular shape. In the closed position, the plane of the flap is usually perpendicular or at a defined angle between 50 ° and 90 °. In the case of a round ventilation pipe, therefore, a round or elliptical flap results as the optimal solution.

The US Pat. No. 6,105,927 A describes a louver with a sandwich structure. Two rigid circular discs of slightly smaller diameter than the inner diameter of the vent tube support an inner third disc made of a soft material, which protrudes peripherally annular and is bent in the direction perpendicular to the longitudinal axis of the vent tube end position. Thus, a better closure than with two superposed rigid materials can be produced. The pivoting movement is effected by a connecting rod, which acts on a lever arm.

From the US 2,733,889 (Coleman Company) is a valve for the control of a hot air flow at a relatively high pressure and high speed known. To avoid turbulence and whistling a flap is proposed, which is held on one side or at a location with a leaf spring on the pipe inner wall and is opened with an attacking in the center of the flap chain against the spring force from the diagonal closed position. The flap is oval and consists of two concave metal sheets, between which a sealing material is held. The flap can also consist of a plastic.

Further examples of valves with a concave flap are, for example EP 0 501 073 A2 and US 4,605,198 known. However, these are complicated mechanisms on the basis of guide slots to perform a linear lifting movement with a subsequent pivoting movement.

US 2002/179159 and US 6,105,927 are concerned with mechanisms for flat flaps, wherein the axis of rotation is spaced from the louver.

The WO 2005/053975 A1 describes a fundamentally new device for controlling the air flow in a ventilation pipe with one or more synchronously operable air dampers, which prevent the air flow in the closed position. On a longitudinal run The inner plane of the plane of symmetry of the ventilation pipe has a fastening web with a pivot bearing for the drive axis of the flap and means for transmitting force and / or torque to the drive axle connected to the air flap. The same, with different louvers can be fitted mounting bar is suitable for cross-section differently sized ventilation pipes. The air flap is of circular or elliptical basic shape, the drive axle lies on its small diameter. Preferably, the fastening web extends at an angle of 15 to 90 °, relative to the longitudinal axis of the ventilation pipe.

The WO 2005/05 39 75 A1 thus discloses an apparatus according to the preamble of claim 1 and an air damper according to the preamble of claim 14.

Presentation of the invention

The present invention has for its object to provide a device of the type mentioned, which further improves the efficiency of the air damper without external drives, lever systems or through the pipe wall leading bearings. Next, the device should be easier to install in an existing ventilation pipe or replaceable.

The object is achieved by a device according to claim 1 and an air damper according to claim 14. In this case, the air flap on a curved and thereby biased elastic sheet, which rests in the open positions on two with respect to a crest line of the sheet diametrically opposite support point areas in the ventilation pipe.

Preferred embodiments of the invention are defined in the dependent claims. The air flap or the surface body (for example, a plastic sheet) is thus clamped in the ventilation pipe and is supported on two support points, which act as fulcrums of the air damper.

Preferably, the elastic, with respect to the longitudinal center plane of the ventilation tube symmetrically or approximately symmetrically curved, biased self-stable on the pipe wall supporting air damper in the region of its apex via an angled lever arm at a distance a rigidly mounted on the drive shaft of the drive motor. The air damper is thus held in principle at three points. The mechanical connection to the drive can also be done in other ways.

This ensures that the air damper is always supported on the inner tube wall self-centering on the migrating with the flap position support points and rests in the closed position along a closed, continuous circumferential sealing surface on the inner tube wall, the support points on the virtual points of intersection of the longitudinal axis Drive shaft with the pipe wall lie. Specific and further developing embodiments of the device are the subject of dependent claims.

The drive housing containing the drive housing is freely pivotably mounted on an inner wall of the ventilation tube in a defined or clamped together with the apex line longitudinal center plane of the ventilation tube. The drive motor transmits its torque by means of the reduction gear on the drive shaft and the lever arm on the air damper. During a closing and opening movement of the air flap, the angle of the drive housing to the longitudinal center axis of the ventilation tube self-centering inevitably shifts. Accordingly, the contact points of the air flap on the inner tube wall. The closing movement is completed when the air damper rests sealingly along the entire circumference of the pipe wall and forms a sealing surface. The maximum flow is achieved when the apex line of the air damper runs parallel to the mentioned longitudinal axis of the central axis. Between the closed position and the maximum open position, each position of the air flap can be adjusted for flow control.

Preferably, the air damper in the direction of flow is considered, ie upstream, concave. As a result, the contact pressure on the pipe wall is increased by the pressure-dependent bias and the sealing effect is increased. In other words, can be used for a set working pressure, a louver with a lower residual stress, which means a significant material savings or a possibility for a cheaper material.

Preferably, the apex line of the air damper does not intersect the pivot axis, which is expediently identical to the drive shaft, but extends with leverage at a distance therefrom. The blank of the relaxed in-plane louver (ie, the sheet) is therefore not elliptical, but has a mathematical, more complex shape which is symmetrical with respect to the apex line, but is asymmetrical at right angles thereto. The plane air damper with a constant circumference is calculated with respect to a certain optimal closing angle of the inserted inside the tube, curved air damper with the longitudinal center axis. This angle (measured between the longitudinal center axis of the ventilation tube and the apex line of the air damper) is preferably less than 90 ° and is z. B. in the range of 60 to 80 °, in particular at about 70 °.

The point of intersection which exists between the transverse line (R) and the crest line (S) divides the crest line (S) into two different sections. The sections are of different lengths, with one section (f) not more than 4/5 of the length of the other section (e). With this geometry, an advantageously curved and with a closing angle of less than 90 ° working air damper is created.

• bei geschlossener Luftklappe deren stetiger Umfang auf der inneren Rohrwand eine umlaufende Dichtfläche bilden, und
• bei jeder teilweisen oder vollständigen Öffnungsposition die beiden Auflagepunkte auf der inneren Rohrwand im virtuellen Schnittpunkt mit der verlängerten Schwenkachse liegen.

The air flap is preferably made of a corrosion-resistant elastic metal, in particular spring steel, or a mechanically dimensionally stable, resilient plastic, in particular a Polyethylentherephtalat or a polyamide. The thickness of the air damper is material-specific according to the required contact pressure of the curved damper on the pipe wall by means of residual stress, taking into account the pressure exerted by the pressure on them, calculated. The plane dimensions of the air damper are calculated from the parameters of the inner diameter of the pipe wall to be populated, closing angle of the apex line to the longitudinal center axis of the ventilation tube, radius of curvature of the air damper used and distance of the apex line of the air damper of the drive shaft forming the pivot axis, said

• form a circumferential sealing surface on the inner tube wall when the air flap is closed, and
• at each partial or complete opening position, the two support points lie on the inner tube wall in the virtual intersection with the extended pivot axis.

According to a preferred embodiment of the invention over the entire continuous circumference of the air damper, a ring-shaped projecting or a U-shaped elastic seal is arranged, which expediently consists of rubber, an elastomer or a soft plastic.

The sealing lip may be integrally formed on the sheet body forming the air damper. Advantageously, the sealing lip is smaller at the contact point areas than in a region of the apex line. As a result, the resistance when rotating the air damper can be reduced compared to an embodiment with a constant wide sealing lip.

In particular, the sheet is composed of a disc of the highly elastic material, which is arranged as a peripherally projecting core layer between two metallic, duroplastic or thermoplastic cover disks. It is therefore an air damper made of a flexible composite material, which compensates for any leaks through ovality of the tube along the circumference of the air damper and seals.

According to a particularly advantageous variant of the invention, the two cover plates are not arranged congruently. Alternately, one of the cover disks with a smaller radius runs over one half-circumference lying between the support points, that is to say it is arranged set back. The continuous circumferential annular seal thus does not run as usual with two equal sized cover plates. The arrangements with a over the entire circumference regularly projecting sealing lip have the disadvantage that the sealing material in the closed position of the damper strongly deformed and jammed, which can make a significantly larger torque required when opening. The mutually set back cover plates prevent jamming of the sealing material. When opening the air flap, the larger cover plate can push away the sealing material unhindered, so it is a much smaller torque required.

According to a further embodiment of the invention, the region of the apex line of the air flap is reinforced with longitudinal webs or ribs, which can extend to the periphery. As a result, the curvature formed in the ventilation pipe is not or only insignificantly affected, but reinforces the air damper in the direction of the apex line. These longitudinal ribs are applied to the louver, for example, by welding, soldering or gluing, or integrally formed with it.

With regard to the method for inserting or replacing the device, the object is achieved by cutting out an opening, in particular a rectangle elongated in the axial direction of the ventilation pipe, from the ventilation pipe, fastening the device to a blank of tubular material or transparent material protruding on all sides , introduced with strongly bent elastic air flap, and the opening is again tightly closed.

Preferably, the blank is made of transparent material, the device used with the air damper can be observed.

• Die Luftklappe ist so ausgebildet, das sie sich selbstzentrierend an der Rohrwand ohne wanddurchführende Drehlager etwa mittig abstützt. Es ergibt sich eine Dreipunktabstützung, wodurch eine Ebene definiert wird, was zur Stabilität beiträgt.
• Durch die konkave Wölbung in Durchflussrichtung wird die Luftklappe mit zunehmendem Druck im Lüftungsrohr stärker an die Rohrwand gedrückt, was die Abdichtung verbessert.
• Die Luftklappe ist sehr einfach zu montieren, der Zuschnitt kann gebogen durch eine verhältnismässig schmale Öffnung geführt werden, losgelassen stützt sich die Luftklappe augenblicklich an die Innenwand ab. Die Luftklappe kann in jeder beliebigen Lage eingebaut werden. Die Montageöffnung erstreckt sich über weniger als die Rohrhälfte, was wesentlich zur Erhaltung der Stabilität des Lüftungsrohrs beiträgt.
• Es wird lediglich eine Aufhängung, welche die Energie- und Signalleiter für den innen liegenden Antrieb durch die Rohrwand führt, gebraucht.

In summary, the invention has the following advantages:

• The air damper is designed so that it self-centering on the pipe wall without wall-carrying pivot bearing is supported approximately in the middle. The result is a three-point support, whereby a plane is defined, which contributes to stability.
• Due to the concave curvature in the direction of flow, the air flap is pressed more strongly against the pipe wall with increasing pressure in the ventilation pipe, which improves the seal.
• The air flap is very easy to assemble, the blank can be bent through a relatively narrow opening to be guided, let loose, the air damper is based immediately on the inner wall. The damper can be installed in any position. The mounting opening extends over less than half of the pipe, which significantly contributes to the maintenance of the stability of the ventilation pipe.
• It is only a suspension, which leads the energy and signal conductors for the internal drive through the pipe wall, needed.

Brief description of the drawings

Fig. 1

eine Ansicht einer Vorrichtung mit einer in einem aufgeschnitten dargestellten Lüftungsrohr eingesetzten, maximal geöffneten Luftklappe,

Fig. 2

die Seitenansicht von Fig. 1 in Richtung des Luftstroms,

Fig. 3

eine perspektivische Darstellung der Vorrichtung nach Fig. 1 mit offener Luftklappe,

Fig. 4

die Vorrichtung nach Fig. 3 mit geschlossener Luftklappe,

Fig. 5

eine Draufsicht auf eine plan ausgelegte Luftklappe aus Verbundmaterial,

Fig. 6

die Seitenansicht von Fig. 5,

Fig. 7

eine perspektivische Darstellung von Fig. 5,

Fig. 8

ein Schnitt durch einen peripheren Bereich einer geschlossenen Luftklappe,

Fig. 9

eine perspektivische Darstellung einer verstärkt ausgebildeten Luftklappe,

Fig. 10 - 15

eine perspektivische Darstellung des Einbaus einer Vorrichtung gemäss Fig. 1 - 4 in ein Lüftungsrohr.

Fig. 16 - 18

eine Schnittdarstellung des Flächenkörpers der Luftklappe und eine Draufsicht auf diesen.

The invention will be explained in more detail with reference to embodiments shown in the drawing, which are also the subject of dependent claims. They show schematically:

Fig. 1

a view of a device with a ventilation pipe used in a cut open, maximum open air damper,

Fig. 2

the side view of Fig. 1 in the direction of the airflow,

Fig. 3

a perspective view of the device according to Fig. 1 with open air damper,

Fig. 4

the device after Fig. 3 with closed air damper,

Fig. 5

a plan view of a plan designed air damper made of composite material,

Fig. 6

the side view of Fig. 5 .

Fig. 7

a perspective view of Fig. 5 .

Fig. 8

a section through a peripheral region of a closed air damper,

Fig. 9

a perspective view of a reinforced trained air damper,

Fig. 10 - 15

a perspective view of the installation of a device according to Fig. 1 - 4th in a ventilation pipe.

Fig. 16 - 18

a sectional view of the sheet of the air damper and a plan view of this.

Fig. 1 to 4 show a device 12 used in a ventilation pipe 10 for controlling an air flow A. The device 12 essentially comprises a freely pivotable drive housing 32 with a drive motor 14 and a reduction gear 16, which exerts a torque on a drive shaft 18. This drive shaft 18 is rigidly connected to a right-angled cantilevered lever arm 20, which in turn is bent at right angles in the direction of the drive housing and thus forms a support surface 22 for a fixed thereto elastic air damper 24. If the lever arm 20 is formed U-shaped according to a variant, not shown, via two legs connected to the drive shaft 18, the base forms the support plate 22 for the air damper 24. This is according to Fig. 4 fixed with two screws 26 on the support plate 22, which has a distance a from the longitudinal axis of the drive shaft 18.

The device 12 or the drive housing 32 is suspended on a pivot bearing 30, which in turn is fastened with a through the ventilation tube 10 by cross-bolt 28 or snapped to a variant, not shown. The position angle a of the freely rotatable in a longitudinal center plane L _M drive housing 32 to the longitudinal central axis L _{A of} the ventilation tube 10 is dependent on the tilt angle of the curved damper 24. About the hollow screw 28 electrical conductors for energy and signal transmission are directed into the tube interior.

The introduced into the vent pipe 10 elastic air valve 24 is - apart from the closed position - curved in two diagonally opposite support points 36, 38 on the inner tube wall 34. The air flap 24 is dimensioned such that the support points 36, 38 simultaneously form the virtual transmission points of the longitudinal axis L _{W of} the drive shaft 18 with the pipe wall 34. Of course, these support points 36, 38 are not interpreted in a purely geometric sense, they are designed as a minimally expanding support surface. Of essential to the invention is that at these support points 36, 38 is not pierced through the pipe wall 34, but that these support points 36, 38 in function of the pivot angle of the flap 34 with the changing angle α of the motor housing 32 wander. In the closed position according to Fig. 4 the support points 36, 38 are no longer recognizable. The air flap 24 is now instead of the support points 36, 38 along its entire, continuously extending circumference U on the pipe wall 34 and thus seals the vent pipe 10 completely.

The curvature of the air damper 24 and its symmetry with respect to the longitudinal center plane L _M is particularly good Fig. 2 recognizable. Out Fig. 4 shows that the air damper in Closing position in the direction of the air flow A, ie upstream, concavely rests. In other words, the concave curvature is formed on the side of the sheet holding lever arm 20. This is done on the one hand by the resilience of the damper 24 and on the other hand by the pressure of the air flow A.

The apex line S of the symmetrically curved air damper 24 always runs independently of its pivoting position on the longitudinal center plane L _{M of} the ventilation pipe 10.

In Fig. 5 to 7 is a relaxed, lying on a plane elastic air damper 24 shown, which is designed as a layer composite. Between the two cover plates 40, 42 of about 0.2 mm thick spring steel, a core layer 44 is disposed of an approximately 0.5 mm thick elastomer layer, which protrudes peripherally. The in the direction of Fig. 5 Upper cover plate 40 covers the elastic air damper 24 practically completely. The elastic louver 24 is symmetrical with respect to the virtual crest line S formed in bending. The apex line extends through two boreholes 46, 48 via which the air flap 24 on the support plate 22 (FIG. Fig. 3 ) is fixed.

In contrast to an ellipse, the substantially egg-shaped air damper 24 has no plane perpendicular to the apex line S extending plane of symmetry. However, the two cover disks 40, 42 overlap in the peripheral area only in the two tangential areas T. Here, the core layer 44 is cut back parallel to the apex line S so that in the mentioned tangential areas T the two cover disks 40, 42 remain without a core layer lying therebetween. As a result of this measure, the air flap 24 inserted in a ventilation tube 10 can be displaced and pivoted on the support points 36, 38 with less resistance.

In FIGS. 5 and 7 the lower cover plate 42 is recognizable only as a small spill. The continuous circumference U formed by the two cover disks 40, 42 is also formed in the overlapping tangential region T.

From above ( Fig. 5 ) or right ( Fig. 6 ), the elastomeric core layer 44 projects peripherally around c in the upper part and around b + c in the lower part. From underneath ( Fig. 5 ) or ( Fig. 6 ), the elastomeric core layer 44 projects in the upper region by b + c, in the lower region only by c.

Fig. 8 , shows the peripheral area of a closed air damper outside the tangential areas T (FIG. Fig. 5 ), in particular in the region of the apex line (S), with a formed as a sealing lip 52, protruding core layer 44 made of an elastomer. The curved in a vent pipe 10 with a tube wall 34 arranged air damper 24 is rotated in the direction of arrow 54 until it hits with its peripheral edge 56 on the inner tube wall 34 and forms a first sealing surface. In the final phase of this pivoting movement, the sealing lip 52 is bent over and forms on the inner tube wall 34, a second sealing surface 58. The created by the return of the upper cover plate 40 relative to the lower cover plate 42 clearance prevents the highly elastic material of the core layer 44 is deformed too much and when opening the air damper 24 in the opposite direction to the arrow 54 leads to jamming. On the diagonally opposite side of the air flap 24 takes place with respect to the median plane between the cover layers 40, 42 mirror image the same. An arrangement according to Fig. 8 is also called a double lip.

The elastic air damper 24 according Fig. 9 has two reinforcing plates 60 in the region of the longitudinal central axis L, which clamp the elastic air flap lying in between. Further, longitudinal reinforcing ribs 62 are arranged, which, like the angled lever arm 20, are glued, soldered or welded to the support plate 22. If the upper cover plate 40 is made of plastic, the reinforcing elements 60, 62 and the lever arm 20 may also be integrally formed. Finally, the distance a of the pivot axis of the drive shaft 18 is indicated by the support plate 22 for the elastic air damper. As mentioned, this distance a is a determinant for the calculation of the surface shape of the air flap 24, the greater the distance a, the more it deviates from the elliptical shape.

The in the FIGS. 10-15 shown sequence shows the installation of an inventive device in a ventilation pipe at any point.

Fig. 10 , From a vent pipe 10 a rectangular in the projection opening 64 is cut out. For clarity, the drawn opening 64 extends over a greater part of the circumference than is necessary in practice. On in no case may the opening be greater than half the circumference, the opening 64 is as small as possible, so that the stability of the ventilation tube 10 is not impaired.

Fig. 11 , Above the vent tube 10 with the opening 64, a device 12 for controlling the air flow with a hollow screw 28 is mounted on a blank 66 of tube material. The elastic air damper 24 is relaxed and lies on one level.

Fig. 12 , The air flap 24, which is raised to a curvature on both sides in the direction of the arrows 68, 70, is already partially inserted into the opening 64.

Fig. 13 , The already completely inserted into the vent pipe 10 air damper 24 has partially relaxed, it is under residual stress on the inner pipe wall 34.

Fig. 14 , The device 12 with the freely pivotable drive housing 32 and the not visible air damper is completely inserted into the ventilation pipe 10. The blank 66 is located as the opening 64 on all sides overlapping tangent plane. The next step, the bending of the blank 66 on the vent pipe 10 is indicated by arrows 72, 74.

Fig. 15 , The blank 66 is the opening 64 on all sides sealingly on the vent pipe 10 and is detachably or permanently connected thereto, in this case by means of screws 76th

According to one variant, the blank 66 also consists of other than tube material, in particular of a flexible transparent material. In this case, the device 12 can be observed with the elastic damper 24 from the outside and monitored.

Fig. 16 to 18 show a further preferred embodiment of the invention. The air flap is essentially formed by a flexible one-piece plastic disk 80. The plastic disk 80 is oval and can be characterized by the crest line S and the transverse line R perpendicular to it. The apex line S is determined by the longest diameter line of the plastic disk 80. The transverse line R is defined by the diameter line of greatest length perpendicular thereto. At the crossing point of crest line S and transverse line R, the transverse line R is halved. In Fig. 17 is half the cross line R designated g. In contrast, the apex line S is divided by the transverse line R into two unequal sections e and f.

Preferably applies

$$f\approx \frac{4}{5}e$$

als besonders gut. Die Scheitellinie S ist geringfügig grösser als die Querlinie R. Bei einem Schliesswinkel von z.B. 70° erweisen sich Werte im Bereich $$0.96<\left(e+f\right)/2g\le 0.99$$

als besonders bevorzugt. Die Werte sind also <1 und >0,95. Dabei ist festzuhalten, dass für einen Schliesswinkel unter 90° sowohl die Scheitellinie S=(e+f) als auch die Querlinie R=2g geringfügig grösser als der Innendurchmesser des Lüftungsrohrs ist, in welches die Luftklappe eingesetzt wird.Thus, in the closed position of the damper, an angle of 60-80 ° can be achieved. For an angle of about 70 ° and a pipe diameter of 125 - 150 mm, a ratio of $$f\approx \frac{3}{4}e$$

as especially good. The crest line S is slightly larger than the transverse line R. At a closing angle of eg 70 °, values in the range prove $$0.96<\left(e+f\right)/2G\le 0.99$$

as particularly preferred. The values are thus <1 and> 0.95. It should be noted that for a closing angle of less than 90 ° both the apex line S = (e + f) and the transverse line R = 2g is slightly larger than the inner diameter of the ventilation tube, in which the air damper is used.

In the embodiment according to Fig. 16-18 are two sealing lips 81, 82 integrally formed on the plastic disc 80. The width of the sealing lip 81, 82 varies continuously along the circumference of the plastic disk 80. In the edge regions 85, 86, in which the transverse line R meets the circumference, sealing lips are missing. Where the crest line S abuts the circumference of the plastic disc 80, they are maximally wide and stand there, for example, at an angle of 45 ° to the plane of the plastic disc 80 FIGS. 16 and 18 can be seen, the sealing lips 81 and 82 are thinner than the plastic disc 80 and put on opposite major surfaces 83 and 84 at. In the edge regions 85, 86 are in the installed state of the air damper according to the invention contact or pivot points of the air damper.

Parallel to the apex line S, but slightly offset laterally, 83 reinforcing ribs 87, 88 are provided on the one main surface. They extend in the embodiment shown approximately over half the length of the apex line S and indeed in the region of the designated a portion of the apex line (see Fig. 17 ).

Between the reinforcing ribs 87, 88, a first fastening element 90 is provided. With respect to the transverse line R mirror image, a second fastening element 89 is present. The two fastening elements 89, 90 rise from the main surface 83, and are overall plate-shaped or ramp-shaped and strip-shaped in plan view. They may additionally serve as reinforcement of the plastic disk 80 along the crest line S. On the sides facing each other, the fastening elements 89, 90 snap-lock devices 92, 93 for an actuating lever of a damper drive. Furthermore, from the main surface 83, there is an edge 91 which laterally delimits the free region formed between the fastening elements 89, 90. The flank 91 represents in the present example, an extension of the rib 87 and preferably also has latching elements for fixing the (not shown) fastening lever.

In the embodiment according to Fig. 16 to 18 Each of the two snap-lock devices 92, 93 is associated with a (production-related) through-opening 94, 95. These are covered by the coupling element formed on the actuating lever (which cooperates with the snap-lock devices 92, 93). In the mounted state, the plastic disc 80 is thus airtight.

The described embodiments can be modified in many ways. The reinforcement along the crest line may be integrated with the plastic disk 80 (e.g., in the form of integrated material reinforcements). The attachment of the plastic disc can also be done by screwing or sticking, instead of by snapping. The sealing lips 81, 82 may be made of the same material as the plastic disk 80 or of another material. It is also not mandatory that their width varies continuously along the circumference.

The described embodiments are dimensioned for a closing angle of about 70 °. At other closing angles, the lengths are crest line and cross line different. But you will not vary more than 10% for variants with a closing angle in the range of 60 ° -80 ° or even up to 90 °.

In summary, it should be noted that with the invention, a structurally simple air damper has been created, which can be very easily and quickly install.

Claims (15)

1. Device (12) for controlling an airflow (A) in a ventilation duct (10), comprising:

   a) a pivotable air flap (24) which can assume adjustable opening positions and which prevents the airflow (A) in the ventilation duct (10) when in a closed position, and

   b) a drive which is coupled to the air flap (24) for pivoting the air flap (24), the drive being arranged on the inside of the ventilation duct (10),
   characterized in that

   c) the air flap (24) has an elastic surface body which is curved and thus under load and contacts, in the open positions, two contact points (36, 38) or edge regions (85, 86), diametrically opposing each other with respect to an apex line (S) of the surface body, in the ventilation duct, wherein the elastic surface body is clamped in the ventilation duct and rests on the two contact points (36, 38) or edge regions (85, 86) acting as points of rotation of the air flap.
2. Device according to Claim 1, characterized in that the surface body has an oval surface contour having a maximum extension along the apex line (S) and a minimum extension along a transverse line (R) perpendicular to the apex line (S), and in that an intersection of the transverse line (R) with the apex line (S) divides the apex line (S) into two portions of differing length, one portion (f) being no more than 4/5 of the length of the other portion (e).
3. Device according to one of Claims 1 to 2, characterized in that in the closed position the apex line (S) is at a closure angle α of less than 90° relative to a longitudinal mid axis of the ventilation duct, preferably at a closure angle of from 60° to 80°, in particular of approximately 70°.
4. Device according to Claim 1, characterized in that a drive housing (32), which contains the drive, is mounted at an inner wall (34) of the ventilation duct (10) such that it may pivot freely about a longitudinal mid plane (LM), which is defined together with the apex line (S), of the ventilation duct (10) and in that the surface body (80) is embodied so as to be mirror-symmetrical with respect to the apex line (S) and asymmetrical perpendicularly thereto.
5. Device according to one of Claims 1 to 4, characterized in that the air flap is symmetrically or approximately symmetrically curved about the apex line (S) and is rigidly fixed to a drive shaft (18) of the drive motor, by an angled lever arm (20) with a predefined separation (a), in the region of the apex line (S) lying in the longitudinal mid plane.
6. Device according to one of Claims 1 to 5, characterized in that the surface body (80) contacts, in the closed position, an inner duct wall (34) of the ventilation duct along a sealed, endless peripheral sealing surface (58) and in that the surface body has at the edge side a sealing lip (81, 82) which is smaller at the edge regions (85, 86) than in a region of the apex line (S).
7. Device according to one of Claims 1 to 6, characterized in that the contact points (36, 38) lie on virtual intersections of a longitudinal axis (LW) of the drive shaft (18) with the duct wall (34).
8. Device (12) according to one of Claims 1 to 7, characterized in that the air flap (24) or the surface body is curved in a concave manner in the flow direction.
9. Device (12) according to one of Claims 1 to 8, characterized in that the air flap (24) is made of a corrosion-resistant, elastic metal, in particular spring steel, or a mechanically dimensionally stable, resilient plastics material, in particular a polyethylene terephthalate or a polyamide.
10. Device (12) according to Claim 9, characterized in that an annularly protruding, highly elastic seal, made preferably of a rubber, an elastomer or a soft plastics material, is arranged over the entire circumference (U) of the air flap.
11. Device (12) according to one of Claims 1 to 10, characterized in that the air flap (24) is made of a composite material, preferably of a peripherally protruding core layer made of a rubber, an elastomer or a soft plastics material, and two metallic or thermoplastic cover disks (40, 42).
12. Device (12) according to Claim 11, characterized in that one of the cover disks (40, 42) runs alternately with a smaller radius over a half-circumference lying between the contact points (36, 38).
13. Device (12) according to one of Claims 1 to 12, characterized in that the region of the apex line (S) is embodied so as to be reinforced, preferably by longitudinally running reinforcement plates (60) and/or reinforcement ribs (62) which also extend up to the circumference (U), and in that the lever arm (20) with the contact plate (22), the reinforcement plates (60) and the reinforcement ribs (62) and also the air flap (24) are formed in one piece.
14. Air flap for a device according to Claim 1, characterized in that it has an elastic surface body (80) which can be curved under load for insertion into a ventilation duct and which has a shape which is mirror-symmetrical with respect to an apex line (S) and asymmetrical perpendicularly thereto wherein the surface body (80) can contact, in the open positions, two contact points (36, 38) or edge regions (85, 86), diametrically opposing each other with respect to an apex line (S) of the elastic surface body (80), in the ventilation duct, wherein the elastic surface body (80) can be clamped in the ventilation duct and can rest on the two contact points (36, 38) or edge regions (85, 86) acting as points of rotation of the air flap (24).
15. Air flap according to Claim 14, characterized in that two edge regions (85, 86), which diametrically oppose each other with respect to the apex line (S) of the surface body, are embodied for mounting in a ventilation duct, the edge regions (85, 86) being preferably free from a sealing lip.

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