The invention relates to a device for regulating an airflow occurring therein, comprising:

- a frame for throughfeed of the airflow, the frame having a peripheral wall,

- at least one plate element, the plate element having a peripheral edge,

- wherein a part of the plate element peripheral edge and a part of the frame peripheral wall are hingedly attached to each other;

- wherein in a closed position of the device the plate element peripheral edge lies close-fittingly against the frame peripheral wall in order to substantially block the airflow, and

- wherein in an open position of the device a passage is provided for the airflow between a free part of the frame peripheral wall and a free part of the plate element peripheral edge.

Such devices are known in the field. At an edge adjacent to the passage the plate element can be opened downstream, i.e. in a direction of the airflow, in order to provide ventilation in a space located further downstream. The devices are usually embodied such that the plate element can be placed in different positions. In specific applications in which the ventilation must be introduced into the space in roughly dosed manner, such devices are provided with regulating systems for adjusting the plate element to and/or holding it in the opened position. In more specific applications, in which there must be a fine to very fine adjustment of the ventilation, the edge of the plate element adjacent to the passage is positioned such that the edge is in ajar position close to the frame. In an ajar position a slight airflow with a substantially turbulent characteristic occurs through the passage, wherein vortices are created close to the edge of the plate element adjacent to the passage, whereby the airflow is slowed by passing through the gap and descends immediately behind the plate element, particularly when the airflow is cold compared to the air present in the space, which can be undesirable. In order to allow a desired quantity of air to flow in through the gap, the plate element is nevertheless opened to a minimal ajar position by adjusting the position of the plate element arranged hingedly in the frame to a very small angle relative to the frame, wherein the problem of the airflow not being blown further into the space but descending immediately behind the plate element is overlooked. Apart from this problem, a small variation in the position of the hingedly arranged plate element, which may for instance occur during a gust of wind, has a great effect on a typical property of the airflow through the device. A substantially turbulent, weak airflow along the plate element, which is initially set in ajar position relative to the frame, may acquire a substantially laminar characteristic due to the plate element being rotated further downstream relative to the frame, this characteristic resulting in a stronger airflow, or at least stronger than desired and/or adjusted, which strong airflow can have highly disadvantageous further consequences in a situation in which the properties of the ajar plate element are taken into account. In a further case the plate element, for instance under the influence of a sudden decrease in the amount of wind, can slam shut so that no fresh air at all can enter the space, which can have other further disadvantageous consequences.

It is an object of the invention to provide a device for adjusting an airflow occurring therein and for instance flowing out into a space located downstream with which the above stated problem is prevented. The device according to the invention has for this purpose the feature that the free part of the plate element peripheral edge comprises a tip-like segment and that the free part of the frame peripheral wall is provided with a screen which extends in flow direction of the airflow and in a first open position of the device lies at least partially close-fittingly against the free part of the plate element peripheral edge in order to substantially block the airflow, such that the passage for the airflow is provided between the tip-like segment and the screen at the position of the tip-like segment, and the length of the tip-like segment is substantially smaller than the length of the hingedly attached part of the plate peripheral edge.

With this very surprising and not obvious measure a device is obtained for adjusting a substantially laminar airflow along the free part of the frame peripheral wall which flows out in the space located downstream, wherein the spectacular effect is achieved that a laminar airflow, which is therefore easy to regulate and control and desirable, can be adjusted even when the airflow is very weak, which airflow enters the space via the passage and can reach further into the space because of the laminar characteristic thereof. With the device according to the invention a predominantly turbulent characteristic of the entering airflow is prevented close to the edge of the plate element adjacent to the passage, i.e. the free part of the plate element peripheral edge, in that the screen lies at least partially close-fittingly against the device in the first open position thereof. The airflow is hereby thus also prevented from descending in the space behind the plate element immediately after entering the space, so that entering air can instead reach the part of the space situated further downstream. The tip-like segment of the free part of the plate element peripheral edge provides an airflow via the passage which cannot partially leak away or escape between the free part of the frame peripheral wall and a part of the free part of the plate element peripheral wall located at a distance from the tip-like segment because, in the first open position of the device, the screen lies at least partially close-fittingly against the part of the free part of the plate element peripheral edge located at a distance from the tip-like segment and substantially blocks the airflow.

In order to adjust the airflow through the passage which may be laminar but is also very weak and which is similar in respect of flow rate to the prior art device, the plate element according to the invention has to be rotated further open than the prior art plate element. A suddenly occurring gust of wind will indeed change the adjusted angle of the plate element relative to the frame by roughly the same value as the adjusted angle in the prior art plate element. This change relative to the adjusted angle is however relatively smaller than in the case of the plate element in the prior art device and thus has less effect on the force or the strength of the airflow. At least when there is a sudden decrease in the wind the passage will not move into an ajar position, so that close to the passage a substantially turbulent airflow is prevented, the airflow is not decelerated and does not descend immediately behind the plate element, but instead moves through the space over a desired distance in the desired direction in substantially laminar manner.

Because the length of the tip-like segment is substantially smaller than the length of the hingedly mounted part of the plate peripheral edge, the device is provided with the option of making a small concentrated opening adjustable. The tip-like segment of the free part of the plate element peripheral edge being small relative to the hingedly mounted part of the plate peripheral edge has the effect that the passage extends over only a small portion of the plate element edge and thereby provides a concentrated opening. With the concentrated opening a small first passage surface area can be adjusted instead of an elongate passage along which, in the case of a second passage surface area roughly equal to the first small passage surface area, a long gap extending over a large portion of the plate peripheral wall would occur which causes a turbulent flow. Typical for this embodiment is that, at a minimal ratio of the length of a passage peripheral edge relative to the passage surface area, an optimum concentrated passage opening is obtained. The shorter the passage peripheral edge, the shorter the length along which a gap can extend, the less friction air flowing therealong encounters and the less turbulence that can occur.

In conventional applications a desired airflow is achieved by closing a plurality of valves and further opening several valves. With the device according to the invention the desired airflow can be obtained with a smaller number of valves which are situated in the first opened position, whereby regulating of the airflow is less complex.

In a practical embodiment the tip-like segment extends substantially parallel to the hingedly mounted part of the plate element peripheral edge. In a detailed embodiment the plate element takes a substantially trapezoidal form. These embodiments provide a device according to the invention which is compact and can be placed in a passage opening present in a wall of a building, such as a rectangular passage opening in an existing building, wherein the device further has the above stated advantages.

In a particularly favourable and useful embodiment the plate element takes a substantially triangular form. The triangular form of the plate element provides a similarly shaped tip-like segment of the plate peripheral edge, this form being structurally favourable for building into a passage opening of a wall and/or building. The triangular form of the tip-like segment is a practical form aiming at a minimal ratio of the length of the peripheral wall of the passage relative to the surface area of the passage. An optimum concentrated passage opening is hereby obtained, whereby turbulence along the tip-like segment of the plate element peripheral edge remains limited to a minimum.

In an alternative embodiment the tip-like segment has a spout which has a form corresponding to the passage and which extends downstream for the purpose of guiding the airflow. With the plate element it hereby becomes possible, with the spout running close to the tip-like segment in the first opened position, to provide a passage having a length which is substantially smaller than the length of the hingedly mounted part of the plate peripheral edge.

In a particularly useful embodiment the plate element comprises

substantially a right angle close to the tip-like segment. It hereby becomes possible to apply the device according to the invention in renovation projects, wherein the device can be placed in a substantially rectangular passage opening present in an existing wall and/or building.

In a very particular and practical embodiment the device comprises a first and a second plate element, wherein the part of the first plate element peripheral edge is substantially parallel and adjacent to the part of the second plate element peripheral edge. In a more precise embodiment the first and the second plate element form substantially a rectangle, at least in the closed positions thereof. It hereby becomes possible to apply the device according to the invention in a standard rectangular recess present in the wall of a building. The plate element of the device according to the invention provided with the tip-like segment has, for the purpose of achieving the desired effect, a form which is new in the field and thus non-standard, which non-standard form can be obviated by applying the first and the second plate element in a substantially rectangular frame. An additional and particularly favourable advantage of this embodiment is that in a maximum opened position of the first and second plate elements the overall flow rate is substantially equal to the flow rate of for instance a frame which is already present in an existing building and which has, in accordance with legislation, a minimal cross-sectional dimension for the purpose of obtaining a minimum desired airflow.

The device is provided with the plate element according to the invention and with a further plate element according to the invention, wherein the hingedly mounted part of the plate element peripheral edge is situated lying against and/or close to and substantially parallel to a further hingedly mounted part of the further plate element peripheral edge. The plate element and the further plate element according to the invention each provide an adjustable passage with the above stated advantages.

In an optimized embodiment the screen extends downstream to at least the first position of the placed free part of the plate element peripheral edge. The screen of the device according to the invention hereby protrudes over a minimal distance in the space located downstream along a length which is at least necessary to lie at least partially close-fittingly against the free part of the plate element peripheral edge in the first open position of the device, for the purpose of substantially blocking the airflow such that the passage for the airflow is provided between the tip-like segment and the screen at the position of the tip-like segment.

In a practical embodiment an opening surface extending through a downstream edge of the frame peripheral wall is situated substantially at an equal distance from the plate element placed in the closed position. This measure provides a practical embodiment of the device which is easy to produce and such as can be manufactured in mass production with a standard dimension of the frame, such that the advantages of the device according to the invention can be realized with the frame.

According to a further aspect of the invention, a building or wall is provided with the device according to any of the foregoing embodiments. The buildings, such as halls in which for instance crops grow or in which animals are located , and which are provided with the device according to the invention, are thus equipped with frames and plate elements which make it possible to provide the internal space with an airflow which can be carried to a desired area in the space, wherein even for a relatively small airflow the plate element can be disposed at a rotation angle such that the plate element present in the frame, under the influence of for instance a gust of wind or the sudden disappearance thereof, need not move into an ajar or almost closing position, but provides a passage for a substantially laminar airflow.

The invention will now be elucidated by means of preferred embodiments and with reference to the accompanying drawings, in which:

Figure 1 shows schematically a perspective view of a preferred embodiment of the device according to the invention from a point lying downstream relative to the device, in which device are placed a frame and a plate element disposed hingedly in the frame.

Figures 2A, 2B and 2C show a schematic cross-section of the device according to figure 1 , in which the plate element disposed hingedly in the frame is situated successively in the closed position, in a first opened position and in a further opened position.

Figures 3A, 3B and 3C show a schematic cross-section of the device according to figure 1 , in which the plate element disposed hingedly in the frame is situated successively in the closed position, in the first opened position and in the further opened position, and in which the plate element is placed in the frame in an alternative manner relative to the device according to figures 2A, 2B and 2C.

Figure 4 shows schematically a perspective view of an alternative preferred embodiment of the device according to the invention from a point lying downstream relative to the device.

Figure 5 shows schematically a perspective view of a further alternative preferred embodiment of the device according to the invention from a point lying downstream relative to the device.

Figure 6A shows schematically a perspective view of an alternative preferred embodiment of the plate element of the device according to the invention.

Figure 6B shows a schematic cross-section of the alternative preferred embodiment of the plate element along a central plane shown in figure 6A.

Figure 7 shows schematically a perspective view of a preferred embodiment of an assembly of two plate elements of the device according to the invention from a point lying downstream relative to the device.

Figure 1 shows a downstream perspective front view of a preferred embodiment of a device 1 for regulating an airflow 5 occurring therein. Device 1 is adapted to allow passage of an airflow 5 directed substantially transversely of device 1 in accordance with a distribution 50 as shown in figure 2A, this figure 2A showing a cross-section of device 1. Device 1 is adapted for placing in a passage opening of for instance a wall substantially closing off a space, such as for instance an animal accommodation, from a surrounding area from which the airflow 5 originates, such as the outside air.

Device 1 comprises a frame 2 for throughfeed of airflow 5 and has a peripheral wall 21 , 22, 23, 24 generally forming a frame peripheral wall 21 , 22, 23, 24. Placed in frame 2 is a plate element 3 for regulating the airflow 5, plate element 3 having a peripheral wall 31 , 32, 34 generally forming a plate element peripheral edge 31 , 32, 34.

Plate element 3 is mounted in frame 2 such that plate element 3 is pivotable relative to frame 2 for pivoting therein about an axis H extending substantially transversely of airflow 5 during use. In this example first hinge elements 411 , 412 of plate element 3 are placed close to a first edge 31 of plate element 3 and first edge 31 substantially coincides with axis H. Close to a first side 21 of frame 2, this first side 21 extending parallel to axis H in this example, two hinge elements 421 , 422 are connected to frame 2, these hinge elements 421 , 422 being adapted to co-act with the first hinge elements 41 1 , 412. A part 31 1 , 312 of the plate element peripheral edge 31 , 32, 34 is hingedly attached to a part 221 , 222 of the frame peripheral wall 22, 23, 24.

Peripheral wall 21 , 22, 23, 24 of frame 2 is provided in a peripheral direction with mutually connecting wall segments, wherein a second side 22 is disposed transversely of a first outer end of first side 21 and wherein a third side 23 is disposed transversely of a second outer end of first side 21 remote from the first outer end. The second and the third side 22, 23 each have a portion running to a fourth side 24, this fourth side 24 extending in this example substantially parallel to and at a distance from axis H. Frame 2 extends downstream to an opening surface 20 shown in figure 2A which is formed by outer ends located downstream and forming a frame peripheral edge of frame 2.

The connected first, second, fourth and third sides 21 , 22, 24, 23 form a peripheral wall 21 , 22, 23, 24 facing toward airflow 5 during use, inside which peripheral wall 21 , 22, 23, 24 is situated plate element 3. Plate element 3 is provided in a peripheral direction with mutually connecting edge segments, wherein a second edge 32 is disposed transversely of a first outer end of first edge 31 and wherein a third edge 33 is disposed transversely of a second outer end of first edge 31 remote from the first outer end. The second and third edge 32, 33 each have a portion running to a fourth edge 34, this fourth edge 34 extending in this example substantially parallel to and at a distance from axis H. Plate element 3 is generally provided close to a zone thereof located remotely from axis H with a tip-like segment 30. In this example the tip-like segment 30 extends substantially parallel to the hingedly mounted part 32, 33, 34 of the plate element peripheral edge 31 , 32, 33, 34.

Figure 2A shows a situation in which plate element 3 is in a closed position for the purpose of substantially blocking airflow 5. Plate element 3, which is situated in the closed position, is adapted to substantially block airflow 5, in which closed position of device 1 the plate element peripheral edge 32, 33, 34 lies close-fittingly against the frame peripheral wall 22, 23, 24. With an operating mechanism (not shown) plate element 3 can be set in the first opened position shown in figure 2B for at least partial throughfeed of airflow 5 through at least a passage D. In the first opened position the fourth edge 34 of plate element 3 is situated close to and/or downstream relative to opening surface 20. In the first opened position of device 1 plate element 3 provides the passage D for airflow 5, which passage D extends in this position substantially between the fourth side 24 of the frame and the fourth edge 24 of plate element 3, and which passage D has a width dimension W as shown in figure 1 and which passage D is suitable for allowing through a

substantially laminar airflow 5. A substantially partly open gap extends in the opened position of plate element 3 between second side 22 and second edge 32, and at the same time also between third side 23 and third edge 33, through which the supplied airflow 5 can hardly pass, and provides only a weak, substantially turbulent airflow 5 therethrough which is practically blocked. In this example the length of tip-like segment 30 is substantially smaller than the length of the hingedly mounted part 31 of the plate peripheral edge 31 , 32, 34.

The second, third and fourth sides 22, 23, 24 form in other words a free part 22, 23, 24 of the frame peripheral wall 21 , 22, 23, 24 which is provided with a screen 21 , 22, 23, 24 which extends in flow direction 50 of airflow 5 and in the first open position of device 1 lies at least partially closed-fittingly against a free part 32, 33, 34 of the plate element peripheral edge 31 , 32, 33, 34 for the purpose of substantially blocking airflow 5 such that passage D for airflow 5 is provided between tip-like segment 30 and screen 21 , 22, 23, 24 at the position of tip-like segment 30.

In a further opened position of plate element 3 as shown in figure 2C, at least a portion, such as the tip-like segment 30, of plate element 3 located close to fourth edge 34 protrudes through opening surface 20, whereby the second and the third edge 32, 33 still ajar in the first opened position open at least partially further, i.e. become further removed from respectively the second and third sides 22, 23 of frame 2. The absence of the gap at plate element 3 in figure 2C in the further opened position provides for an enlargement of passage D of plate element 3 relative to the passage D of plate element 3 in the opened position shown in figure 2B. An even stronger airflow 5 can hereby be adjusted in the space located downstream relative to device 1.

Figures 2B and 2C show a plate element 3 placed at a rotation angle B relative to frame 2, wherein the mutually co-acting first and second hinge elements 41 1 , 412, 421 , 422, which are designated with a circle in figures 2A, 2B and 2C, make a rotation possible. The first and the second hinge elements 41 1 , 412, 421 , 422 are situated at a first distance D1 from opening surface 20. Close to passage D a protrusion 25 is arranged transversely of peripheral wall 21 , 22, 23, 24 of frame 2, in this case on the fourth side 24 of frame 2. During rotation of plate element 3 from the opened position to the closed position the protrusion 25 forms a limitation to a further rotation. In an embodiment of protrusion 25 the protrusion 25 is provided downstream with a hollow or cup-like concave guide surface 26 for guiding airflow 5 downstream. It is noted that it is also possible to opt for a smaller size of the concave guide surface 26. The concave surface can for instance begin only from the arrow point D in figure 2C.

Figures 3A, 3B and 3C show the plate element 3 of device 1 according to the invention placed in frame 2, wherein plate element 3 is situated in the same positions as in figures 2A, 2B and 2C respectively. First and second hinge elements 41 1 , 412, 421 , 422 are situated at a second distance D2 from opening surface 20, wherein the second distance D2 is substantially smaller than the first distance D1 . Figures 3A, 3B and 3C show an embodiment which, compared to device 1 according to figures 2A, 2B and 2C, has a larger passage D at the same rotation angle B.

Figures 3A, 3B and 3C show a passage opening in the frame wherein the protrusion 25 transversely of frame 2 is absent. Plate element 3 is bounded in an alternative manner against closing rotation further than the closed position, for instance in that plate element 3 has larger edge dimensions than a peripheral wall of frame 2 facing toward airflow 5 during use such that, when plate element 3 is situated in the closed position, airflow 5 is substantially blocked. In a further alternative embodiment drive elements such as an electric motor (not shown) are adapted to bring and hold plate element 3 in(to) positions such as the closed position, the opened position and the further opened position.

The tip-like segment 30 shown in figure 1 has a width dimension W which runs parallel to axis H and which is substantially smaller than a width dimension WH of plate element 3 located close to axis H. The width dimension W of tip-like segment 30 substantially corresponds in this example to the length of fourth edge 34, and the width dimension WH located close to axis H substantially corresponds in this example to the length of first edge 31.

In an alternative embodiment frame 2 of device 1 according to the invention and plate element 3 placed in frame 2 have an alternative form with which substantially the same advantages can be gained as with device 1 according to the foregoing figures. Characteristic forms can be indicated using guide lines 36, 37 and guide points 321 , 322, 333, 334 as shown in figure 1.

Second edge 32 of plate element 3 extends in this example between a first point 321 , which is also located on axis H, and a second point 322 which is also located on fourth edge 34. Third edge 33 of plate element 3 extends in this example between a third point 333, which is also located on axis H, and a fourth point 334 which is also located on fourth edge 34. A first imaginary straight guide line 36 is drawn from first point 321 to second point 322 and a second imaginary straight guide line 37 is drawn from third point 333 to fourth point 334. The first guide line 36 encloses an acute angle A with the second guide line 37 close to fourth edge 34. In the embodiment shown in figure 1 the acute angle A amounts to about 75 degrees. Plate element 3 shown in figure 1 takes a substantially trapezoidal form at least close to a portion thereof facing toward tip-like segment 30.

An even smaller width direction W6 running parallel to axis H for an even finer adjustability of airflow 5 is obtained with an embodiment of plate element 63 of the device according to the invention as shown in figures 6A and 6B, wherein plate element 63 has close to tip-like segment 630 thereof a spout 631 which has a form corresponding to the passage D and which extends downstream for the purpose of guiding airflow 5. Defined in figure 6A is a central plane M relative to which the plate element 63 extends substantially mirror-symmetrically in two substantially equal parts. Figure 6B shows a cross-section of plate element 63 at the position of central plane M. The longitudinal direction of spout 631 extends transversely of the width dimension W6 and has a length dimension smaller than the protrusion 25 protruding into the passage. The plate element 630 situated in the closed position hereby substantially closes passage D for the purpose of substantially blocking airflow 5. The plate element 630 situated in the first opened position provides a passage D according to the invention adjacent to spout 631.

Figures 4 and 5 show alternative preferred embodiments of device 1 according to the invention, wherein the portion of frame 2 and plate element 3 located in the first opened position close to passage D is substantially triangular.

The frame 2 shown in figure 4 has a peripheral wall 21 , 22, 23 which is provided in a peripheral direction with mutually connecting wall segments, wherein a second side 22 is disposed transversely of a first outer end of first side 21 , and wherein a third side 23 is disposed transversely of a second outer end of first side

21 remote from the first outer end. The second and the third side 22, 23 each have a portion running to a point 424. The connected first, second and third sides 21 , 22, 23 form a peripheral wall 21 , 22, 23 which is directed during use toward airflow 5 and inside which peripheral wall 21 , 22, 23 is situated plate element 3. Plate element 3 is provided in a peripheral direction with mutually connecting edge segments, wherein a second edge 32 is disposed transversely of a first outer end of first edge 31 , and wherein a third edge 33 is disposed transversely of a second outer end of first edge 31 remote from the first outer end. The second and the third edge 32, 33 each have a portion which runs toward a point 434 and which in this example forms tip-like segment 430.

Frame 2 shown in figure 5 has a peripheral wall 21 , 22, 23 which is provided in a peripheral direction with mutually connecting wall segments, wherein a second side 22 connects to a first outer end of first side 21 , which first and second sides 21 ,

22 enclose in this example a mutual angle of about 60 degrees, and wherein a third side 23 connects to a second outer end of first side 21 remote from the first outer end, which first and third sides 21 , 23 enclose in this example a mutual angle of about 60 degrees. The second and the third sides 22, 23 each have a portion running toward a point 524. The connected first, second and third sides 21 , 22, 23 form a peripheral wall 21 , 22, 23 which is directed during use toward airflow 5 and inside which peripheral wall 21 , 22, 23 is situated plate element 3. Plate element 3 is provided in a peripheral direction with mutually connecting edge segments, wherein a second edge 32 connects to a first outer end of first edge 31 , which first and second edges 31 , 32 enclose in this example a mutual angle of about 60 degrees, and wherein a third edge 33 connects to a second outer end of first edge 31 remote from the first outer end, which first and third edges 31 , 33 enclose in this example a mutual angle of about 60 degrees. The second and the third edge 32, 33 each have a portion which runs toward a point 534 and which in this example forms tip-like segment 530.

The frames 2 shown in figures 4 and 5 differ from each other in the form of the second and the third sides 22, 23. The peripheral walls of the second and third sides 22, 23 shown in figure 5 each extend substantially in one plane while the peripheral walls of the second and third sides 22, 23 shown in figure 4 are each disposed in two planes situated at a substantially obtuse angle relative to each other. Second and third edges 22, 23 shown in figure 5 each form a straight line, while second and third edges 22, 23 shown in figure 4 are each formed from two lines lying at a substantially obtuse angle relative to each other.

Device 1 according to figure 5 has a substantially triangular plate element 3 and, similarly to device 1 according to figure 1 , the first imaginary straight guide line 36 runs from first point 321 to second point 322, and the second imaginary straight guide line 37 runs from third point 333 to fourth point 334, wherein second point 322 substantially coincides with fourth point 334 and with the highest point 534. Close to the third and/or the fourth point 333, 334 the first guide line 36, which substantially coincides with second edge 32, encloses an acute angle A with second guide line 37 which substantially coincides with third edge 33.

In contrast to the embodiment shown in figure 1 , the embodiments shown in figures 4 and 5 show a passage D with an even smaller width dimension running parallel to axis H, whereby it is possible to adjust an even finer setting of airflow 5, wherein with the same passage relative to the passage D obtained in figure 1 the plate element has to be placed at an even greater rotation angle B, whereby airflow 5 through passage D encounters an even smaller amount of friction, whereby an initially substantially laminar airflow 5 even more easily retains a substantially laminar characteristic, substantially loses even less speed, whereby deflection of airflow 5 occurs still less and the airflow reach even further into the space situated downstream relative to device 1 , while in addition a variation in the adjusted angle B, which is for instance the consequence of suddenly occurring wind, has even less effect on the properties of the airflow 5 regulated by device 1.

In an alternative embodiment (not shown) the triangular plate element 3 has close to the tip-like segment substantially a right angle such that the first guide line 36 close to third and/or fourth point 333, 334 encloses an acute angle A of substantially 90 degrees with the second guide line 37, and plate element 3 forms a right-angled triangle.

Figure 7 shows a device 10 according to the invention comprising frame 2, which in this example is provided with a frame element 20 mounted diagonally therein, wherein a first and a second plate element 73, 74 are disposed hingedly about a further axis H7 extending parallel to the diagonal of frame 2. Frame 2 is adapted in this example for mounting of the second hinge elements 201 , 202, 203, 204 on the diagonally extending frame element 20, which second hinge elements co-act with respectively the first hinge elements 701 , 72 of first plate element 73 and the further first hinge elements 703, 704 of second plate element 732.

The first and the second plate element 73, 74 are substantially triangular in this example and comprise close to tip-like segments 301 , 302 thereof a right angle, an angle of substantially 90 degrees, using which tip-like segment 301 , 302, together and/or separately, particularly in the first opened position of the first and second plate element 73, 74 respectively, the intended advantages can be achieved.

The invention is of course not limited to the described and shown preferred embodiments. The invention relates generally to any embodiment falling within the scope of the protection as defined in the claims and as can be seen in the light of the foregoing description and accompanying drawings. Plate element 3 according to the invention is thus placed hingedly in frame 2 in that the part of the plate element peripheral edge is mounted hingedly on the part of the frame peripheral wall. In the shown embodiments two hinge pairs 41 1 , 421 and 412, 422 are arranged which, in an alternative embodiment, can also be embodied as a linear hinge extending over first edge 31 of plate element 3. In a further embodiment the hinge pairs can be situated at the corners of plate element 3. In yet another embodiment the pivot points can be situated on the second and third edges 32 and 33. An imaginary line then extends between the pivot points. The position of the pivot points on the edges can be adjustable. Instead of pivot points it is also possible to refer to tilting points over which the plate element can tilt or pivot. In the context of this patent application the hingedly mounted part of the plate element peripheral edge is generally understood to mean the length of the part situated between the two hinge pairs or the length of the part extending along the imaginary pivot axis or tilt axis.

In the context of this patent application the plate element generally forms an adjustable valve, and according to the invention can be made of for instance wood, plastic, steel, plaster, concrete or an alternative material having the property of not being transparent. In applications where a minimal quantity of light is provided in the space, the plate elements can also be made, if desired, from an at least partially transparent material adapted to admit a quantity of light, such as glass or a plastic.