Abstract
A pipe bend, in particular for an exhaust air duct of a fume extraction hood, which has a deflection of 60° to 120°, preferably 90°, with an inflow side and an outflow side, wherein the pipe bend has at least one air guide element which is curved in deflection direction and which extends in the interior of the pipe bend, characterized in that the pipe bend has a cross-sectional widening in flow direction behind the inflow side, in particular adjacent thereto, and a cross-sectional tapering in front of the outflow side, in particular adjacent thereto, the course of the bend of the outer wall of the bend deviating from the course of a quarter circle and having a bulge lying outside the vertex of the bend, in particular downstream of the vertex in the direction of flow.
Claims
1. A pipe bend an exhaust air duct of a fume extraction hood comprising: the pipe bend having a deflection of 60° to 120°, preferably 90°, with an inflow side and an outflow side, wherein the pipe bend has at least one air guide element which is curved in deflection direction and which extends in the interior of the pipe bend, wherein the pipe bend has in flow direction (x) behind the inflow side, in particular adjacent thereto, a cross-sectional widening and in front of the outflow side, in particular adjacent thereto, a cross-sectional tapering, wherein the course of the bend of the outer wall of the pipe bend deviates from the course of a quarter circle and has a bulge lying outside the vertex of the pipe bend, in particular downstream of the vertex in the direction of flow (x).
2. The pipe bend according to claim 1, wherein the radius of the pipe bend inner wall corresponds to the course of a quarter circle.
3. The pipe bend according to claim 1, the cross-sectional area of which over the entire course of the bend is larger than the inflow cross-section and the outflow cross-section of the pipe bend.
4. The pipe bend according to claim 1, in which the at least one air guide element has a concave terminating edge at the end face on the inflow side of the pipe bend.
5. The pipe bend according to claim 4, in which the concave terminating edge of the at least one air guide element on the inflow side of the pipe bend projects into the inflow cross section in the region of the opposite wall regions.
6. The pipe bend according to claim 1, in which the at least one air guide element has a convex terminating edge on the end face on the outflow side of the pipe bend.
7. The pipe bend according to claim 6, in which a central region of the end-face terminating edge of the at least one air guide element on the outflow side of the pipe bend projects into the outflow cross section.
8. The pipe bend according to claim 1, in which the at least one air guide element has a comb-like serrated end on the end face on an outflow side of the pipe bend.
9. The pipe bend according to claim 1, in which the at least one air guide element has on its surface at least one trip edge arranged perpendicularly and/or parallel to the flow direction.
10. The pipe bend according to claim 1, wherein the air guiding element is multi-part, wherein a first and a second part element of the air guiding element have an offset (d) with respect to each other in a radial direction (R) of the pipe bend.
11. The pipe bend according to claim 10, which comprises a plurality of air guide elements arranged substantially parallel side by side in the pipe bend, wherein the air guide element closest to the pipe bend outer wall is multi-part in the sense of claim.
12. The pipe bend according to claim 11, which has three air guide elements arranged parallel next to one another in the pipe bend, the middle and the inner air guide element each being of one-piece design.
13. Pipe bend according to claim 12, wherein the distances of the air guide elements increase towards the pipe bend outer wall, wherein the average distance of the outer air guide element to the middle air guide element is greater by 1.4-1.8 times, preferably by 1.5-1.7 times, particularly preferably by 1.6 times, than the distance of the middle air guide element to the inner air guide element.
14. The pipe bend according to claim 11, wherein the distance of the inner air guide element from the inner pipe bend wall is at most 20%, preferably at most 15%, particularly preferably at most 9% of the mean pipe bend radius.
15. The pipe bend according to claim 1, which has spaced guide grooves on opposite inner sides for lateral insertion and fixation of the air guide elements in the pipe bend.
16. The pipe bend according to claim 1, which has an installation indicator, in particular in the form of an arrow, for indicating the installation direction on the outside of the pipe bend.
17. The pipe bend according to claim 1, which is formed as a flat duct bend or as a transition bend from a rectangular flat duct connection to a round duct connection, or vice versa.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] Further features, advantages and characteristics of the invention can be seen in the following description of preferred embodiments of the invention with reference to the accompanying drawings, in which show:
[0035] FIG. 1 is a top view of an embodiment of the pipe bend according to the invention;
[0036] FIG. 2 is a perspective view of an embodiment of the pipe bend according to the invention;
[0037] FIG. 3 is a perspective view of a further embodiment of the pipe bend according to the invention;
[0038] FIG. 4 is a top view of a further embodiment of the pipe bend according to the invention; and
[0039] FIG. 5 is an exploded view of a further embodiment of the pipe bend according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] FIG. 1 shows a first embodiment of a pipe bend 1 according to the invention in the form of a flat duct which deflects the air to be discharged from an extraction hood by 90°. The pipe bend 1 has an inflow side 10 and an outflow side 12, by which the flow direction x is defined. As a result, when the elbow is installed, care must be taken to ensure that it is inserted in the correct orientation so that the exhaust air flows in through the inflow side 10 and out through the outflow side 12. Three air guide elements 3 are arranged in the pipe bend 1, with the air guide element 3 closest to the outer wall 9 of the pipe bend consisting of two partial elements 4 and 5, which overlap in an overlap area 6 with opposite ends 2 and have an offset d from each other. The rear sub-element 5 in the direction of flow x is arranged closer in the direction of the inner pipe bend wall 8 compared with the front sub-element 4. In the overlap area 6, the partial element sections 4, 5 run equidistantly to each other. Furthermore, the partial elements 4, 5 each run equidistantly to the adjacent middle air guide element 3, which in turn runs equidistantly to the innermost air guide element 3. The air guide elements 3 and the partial elements 4, 5 each have a double concave curvature. A first curvature follows the course of the pipe bend 1 and a second concave curvature is characterized by a curvature of the elements around their extension in the flow direction x, so that they are each concave towards the inner wall 8 of the pipe bend. In particular, it can be seen that the inner air guide element 3 has a greater second concave curvature than the middle one, and the middle one has a greater second concave curvature than each of the partial elements 4, 5 of the outer air guide element 3. Accordingly, the inner air guide element 3 projects further toward the outer wall 9 of the pipe bend than the middle and outer ones, and correspondingly the middle one projects further than the outer air guide element 3. These different degrees of curvature result in an optimum deflection of the air at each point of the pipe bend, taking into account the different sharp radii of curvature at which the different air deflection elements 3 are positioned. In the region between the vertex of the pipe bend 1 and the outflow side 12, the pipe bend outer wall has a bulge 19 directed towards the outside of the pipe bend 1. This can be one-dimensional, for example, so that a constant bulge 19 is realized over the course of the height of the pipe bend 1. Alternatively, it can be provided that the bulge 19 is bubble-shaped, so that its largest elevation is provided in or approximately in the height course in the center of the pipe bend 1, and in contrast the areas of the pipe bend outer wall 9 adjacent to the inner walls 15 have no elevation or a smaller elevation in comparison. In the direction of flow x, the bulge 19 can have an initially flat rise, compared with the course of a quarter circle, up to a vertex of the bulge 19. Behind the vertex of the bulge 19, it can then have a steeper drop to the level of the quarter circle compared to the rise. On the inflow side 10 as well as on the outflow side 12, the pipe bend 1 in the embodiment shown has connection sleeves with the same connection cross-section 7. It can be seen that all air guide elements 3 extend approximately up to the connection sleeves. On the inflow side, a cross-sectional widening 17 is provided behind the connection sleeve, and in front of the outflow side 12, a cross-sectional tapering 18 adjoins the connection sleeve on the outflow side. In the area between the connection sleeves, the pipe bend 1 thus has no point at which its cross section is smaller than or equal to the connection sleeve cross section 7. Furthermore, it can be seen that the distances of the air guide elements 3 from the inner pipe bend wall 8 to the outer pipe bend wall 9 increase. The inner air guide element 3 is arranged very close to the pipe bend inner wall, approximately at one tenth of the pipe bend width. The outer air guide element 3, on the other hand, is arranged far away from the pipe bend outer wall 9 and in the range ½ to ⅔ of the pipe bend width.
[0041] FIG. 2 shows a further embodiment of the pipe bend 1, which also has connecting sleeves with identical connecting cross sections 7 on the inlet and outlet sides, with a cross-sectional widening 17 adjoining the inlet side 10 and a cross-sectional tapering 18 being arranged immediately upstream of the outlet side 12. A number of assembly indicators 20 are arranged on the upper side of the pipe bend 1, which are realized in the form of arrows. On the one hand, these indicate to an installer the installation direction of the pipe bend 1 and, on the other hand, the flow direction x of the pipe bend 1 after installation. The installation indicator can be realized by material recesses as shown, or alternatively by material thickenings. Furthermore, it is conceivable that this is highlighted in color on the outside of the pipe bend 1. In particular, it can be seen in the perspective shown that the air guide elements 3 have concave end edges 11 on the inflow side, so that the average height of the air guide elements 3 projects into the pipe bend 1 in the direction of flow x with respect to the outer edges located on the inner sides 15 of the pipe bend. On the outflow side, on the other hand, the terminating edges 13 of the air guide elements 3 are convex in shape, so that the average height of the air guide elements 3 projects out of the pipe bend 1 in the direction of flow x with respect to the outer edges lying on the inner sides 15 of the pipe bend. The air guide element 3 closest to the inner wall 8 of the pipe bend cannot be seen in the perspective shown, but likewise has terminating edges 11, 13 which are concave on one side and convex on the other. The air guide elements 3 are each fixed in the pipe bend by guide grooves 16. It is not shown that the guide grooves 16 associated with an air guide element 3 are formed on both opposing inner sides 15 of the pipe bend 1 and are aligned with one another. The air guide elements 3 can either be inserted into them laterally or inserted vertically into them before the half-shells of the pipe bend 1 are assembled. The air guide elements further have trip edges 14, or tripwires, which in the embodiment shown are arranged in a grid-like manner on the air guide elements 3 and help to improve the air flow in the pipe bend 1. The tripwires can be step-like material thickenings which are formed on the air guide elements 3.
[0042] FIG. 3 shows a further embodiment of the pipe bend 1 in the already installed state. This also has, in particular, the bulge 19 and three equidistantly extending air guide elements 3, of which the one closest to the outer wall 9 of the pipe bend is divided into two sub-elements 4, 5. In particular, it can be seen that the outflow-side terminating edges 13 of the air guide elements 3 have comb-like serrated ends 22, which are modeled on the course of owl wings and ensure the quietest possible air guidance by reducing sound even at different flow velocities.
[0043] FIG. 4 shows a further embodiment of the pipe bend 1 according to the invention. This has, in particular, connection points 21 in the form of undercut locking elements which are arranged on the inflow side and outflow side on the outer sides, top and bottom, of the pipe bend 1 and via which connection elements can be connected to the pipe bend 1. In the embodiment shown, the assembly indicator 20 is realized by a wide arrow at the tip of which further arrows are connected at intervals in the direction of flow.
[0044] Finally, FIG. 5 shows an embodiment of the elbow 1 in exploded view. This has a lower shell and an upper shell which can be detachably connected to one another via snap-in connections arranged at the contact points. The shells separate the pipe bend 1 parallel to the deflection plane. The air guide elements 3 or their sub-elements 4, 5 are accommodated between the shells and can be fixed in guide grooves 16 on the inner sides 15 of the upper shell and the lower shell of the pipe bend 1. In contrast to the embodiment in FIG. 4, the connection points 21 are now arranged on the sides of the pipe bend 1.
[0045] The features of the invention disclosed in the foregoing description, in the drawings as well as in the claims may be essential to the realization of the invention both individually and in any combination.
