Impeller for a ventilator

Abstract

The invention relates to an impeller (11) with two support parts (15, 16) and several impeller blades (17) arranged between the two support parts (15, 16) and connected to the first support part (15) by a first longitudinal edge (20) and to the second support part (16) by a second longitudinal edge (21). An outer edge (19) of each impeller blade (17) connects the two longitudinal edges (20, 21) and has an edge recess (25) at which the outer edge (19) has a local low point (P). The position of the low point (P) is closer to the support part (15, 16) in which higher internal stresses or loads occur during operation of the impeller (11).

Description

[0001] The invention relates to an impeller for a fan. During operation of the fan, the impeller is driven to rotate about an axis of rotation, thereby generating a flow, for example a gas flow, in particular an air flow. The fan can be designed as a radial fan or a diagonal fan.

[0002] The impeller has a first support section, a second support section, and impeller blades arranged between the two support sections. These blades are connected to the first support section along a first longitudinal edge and to the second support section along a second longitudinal edge. The mechanical stress and strength requirements for the impellers increase with rotational speed, with the total stress potentially increasing quadratically with speed. This can be addressed, at least in the highly stressed areas, by a more robust design, for example, with greater wall thicknesses. However, this makes the impeller heavier and more expensive. The fan's energy consumption also increases, especially when the impeller is accelerated to change its rotational speed.

[0003] EP 2 942 531 A1 shows an impeller for a multi-blade fan extending between a cover plate and a base plate. Each blade has a curved trailing edge spaced from a chord connecting the corners of the trailing edge. The trailing edge has a curved profile but no indentation.

[0004] DE 11 2023 001 908 T5 shows a wheel with wings, each having a point at the trailing edge in the middle between the support parts.

[0005] From DE 11 2020 007 795 T5 a wheel with wings is known whose trailing edges are curved but do not have a depression.

[0006] It may therefore be the object of the present invention to create an impeller that can withstand increasing mechanical stress without increased material usage.

[0007] This problem is solved by a wheel with the features of claim 1.

[0008] The impeller according to the invention is designed to rotate about an axis of rotation. In its installed state, the impeller is part of a fan whose motor drives the impeller about the axis of rotation to generate a fluid flow, in particular a gas flow and preferably an air flow. The fan can be a radial fan or a diagonal fan.

[0009] The impeller has a first support section and a second support section. The support sections are arranged axially – parallel to the axis of rotation – at a distance from each other. Between the two support sections, the impeller has several impeller blades. The impeller blades are attached to the first support section by a first longitudinal edge and to the second support section by a second longitudinal edge. Preferably, the longitudinal edges are curved. Furthermore, preferably, the longitudinal edges are not congruent when viewed in the axial direction.

[0010] In a preferred embodiment, the impeller blades are attached to the support components by a material-bonded connection or an adhesive bond. The connection between the impeller blades and the support components can be made, for example, by welding. The impeller blades and / or the support components can be made of a metallic alloy, such as an aluminum alloy, or of a plastic or composite material.

[0011] In one embodiment, the impeller blades and the two support parts can form a monolithic body.

[0012] For example, the first support part can be the bottom plate of the fan and the second support part can be the top plate of the fan. The fan motor can be located in the area of ​​the bottom plate during installation.

[0013] The two support parts are preferably uneven. The two support parts preferably have non-identical geometries. The first support part may have one or more beads to increase strength. The second support part may have a corrugated geometry.

[0014] Each impeller blade has an inner edge and an outer edge. The inner and outer edges connect the two longitudinal edges on opposite sides. The outer edge has a greater radial distance to the axis of rotation than the inner edge.

[0015] The outer edge has a first connection point at the transition to the first longitudinal edge and a second connection point at the transition to the second connection edge. At the first connection point, the first longitudinal edge is in contact with the first support segment. At the second connection point, the second longitudinal edge is in contact with the second support segment.

[0016] The outer edge defines a recess in the impeller blade. Viewed in the direction of extension of the respective impeller blade from the inner edge to the outer edge, the impeller blade has a shorter length in the area of ​​the recess. Compared to a virtual connecting line through the first and second connection points, the outer edge is a certain distance from this line in the area of ​​the recess. The recess is preferably asymmetrical, starting from a low point where the recess is furthest from the connecting line.

[0017] Outside the edge recess, the outer edge can extend along the connecting line or, compared to the edge recess, run on the opposite side of the connecting line, forming a kind of edge projection. In a preferred embodiment, the outer edge does not pass through the virtual connecting line, so that no edge projection is present.

[0018] The edge recess formed on the outer edge of the impeller blades reduces their stiffness, but significantly reduces internal stresses during impeller operation in the area of ​​the connection between the impeller blades and the first and / or second support section. This allows the impeller to be used for fans with higher maximum speeds without increasing the material thickness of the support sections and / or the impeller blades.

[0019] The design according to the invention allows for speed increases of at least 8% to 9% and up to over 25% compared to impellers of similar size. For smaller sizes up to 450 mm in diameter, the impellers are suitable for speeds of at least 3500 revolutions per minute up to 4350 revolutions per minute. For impellers with diameters of 500 mm and above, speeds of at least 2300 revolutions per minute up to 2900 or 3000 revolutions per minute can be achieved.

[0020] Along its curved extension between the inner and outer edges, the first longitudinal edge has a first length. Similarly, the second longitudinal edge has a second length from the inner to the outer edge. The lengths of the longitudinal edges are measured between connection points where the longitudinal edges transition into the inner or outer edge and where they are in contact with the first or second support member, respectively. For the outer edge, these are the first and second connection points, as explained above. The inner edge forms a third connection point at the transition to the first longitudinal edge and a fourth connection point at the transition to the second longitudinal edge. Thus, the first longitudinal edge extends between the first and third connection points, and the second longitudinal edge extends between the second and fourth connection points.

[0021] Along the virtual connecting line, the first connection point has a distance from the second connection point that defines a paddle wheel height.

[0022] The edge depression has a local minimum, and preferably only a single local minimum. At this local minimum, the outer edge, viewed perpendicular to the connecting line, has a minimum distance of [missing value]. Parallel to the virtual connecting line, the local minimum has a distance from the first longitudinal edge that defines a first height. The distance parallel to the virtual connecting line from the local minimum to the second longitudinal edge defines a second height. The first height and the second height are of different magnitudes.

[0023] It is preferred that the minimum distance is at least 2.5%, 5.0%, 7.5%, or 10% of the first length. Additionally or alternatively, the minimum distance may be at most 25%, 20%, 15%, or 12.5% ​​of the first length.

[0024] For example, the minimum distance can be in one of the following ranges, including the respective range boundary: 2.5% to 25% of the first length, or 2.5% to 20% of the first length, or 5.0% to 15% of the first length, or 7.5% to 12.5% ​​of the first length.

[0025] The first height is preferably at least 5.0%, 7.5%, 10%, or 15% of the paddle wheel height. Additionally or alternatively, the first height is at most 40%, 30%, 25%, 20%, or 17.5% of the paddle wheel height.

[0026] The first height may preferably be in one of the following ranges, including the respective range limit: 5.0% to 40% or 7.5% to 30% or 10% to 25% or 10% to 20% or 15% to 20% of the paddle wheel height.

[0027] In a preferred embodiment, the outer edge along the edge recess has a concavely curved first edge section and a concavely curved second edge section, which preferably adjoin each other directly and whose maximum curvatures are of different magnitudes. In one embodiment, the two edge sections adjoin each other directly at the local low point.

[0028] Preferably, the outer edge is cornerless and / or continuous. Mathematically speaking, the course of the outer edge can be continuous and differentiable.

[0029] In one embodiment, a convexly curved third edge segment can follow the concavely curved first edge segment. Additionally or alternatively, a convexly curved fourth edge segment can follow the concavely curved second edge segment.

[0030] It is advantageous if at least one of the convexly curved edge sections (for example, the third and / or fourth edge section) is followed by another concavely curved edge section, for example, a concavely curved fifth edge section and / or a concavely curved sixth edge section.

[0031] It should be explicitly noted here that the numbering of features serves only to distinguish them and does not represent any order or prioritization. For example, the mention of a sixth edge segment does not imply that a fifth edge segment also exists.

[0032] Positioning the edge depression or local low point closer to the first support section reduces stresses, particularly in the connection area between the first support section and the impeller blade. This is especially advantageous when higher stresses occur in the first support section than in the second during impeller operation. Depending on the embodiment, the first support section can be the bottom plate and the second support section the cover plate of the impeller, or vice versa.

[0033] Advantageous embodiments of the invention will become apparent from the dependent claims, the description, and the drawing. The invention is explained in detail below based on the accompanying drawing. The drawing shows: Figure 1 a schematic perspective view of a fan with an embodiment of an impeller according to the invention and Figures 2 and 3Each is a partial representation of an exemplary embodiment of an impeller in the area of ​​one of the impeller blades in a perspective view.

[0034] In Figure 1 A fan 10 (e.g., a radial or diagonal fan) is shown schematically, which has an embodiment of an impeller 11 according to the invention. The impeller 11 is configured to rotate about an axis of rotation D. The fan 10 has an electric motor 12 for rotating the impeller about the axis of rotation D.

[0035] The impeller 11 comprises a first support section 15, a second support section 16, and several impeller blades 17. The impeller blades 17 are arranged between the first support section 15 and the second support section 16, with the two support sections 15 and 16 spaced apart from each other in an axial direction A that is parallel to the axis of rotation D. The impeller blades 17 are spaced away from the axis of rotation D and extend in a curved shape from an inner edge 18 to an outer edge 19. The inner edge 18 of each impeller blade 17 is a smaller distance from the axis of rotation D than the outer edge 19.

[0036] Each impeller blade 17 also has a first longitudinal edge 20 and a second longitudinal edge 21. The two longitudinal edges 20, 21 are spaced apart from each other in the axial direction A and, preferably, are not congruent in the axial direction B. The impeller blade 17 is connected to the first support part 15 along the first longitudinal edge 20. The impeller blade 17 is connected to the second support part 16 along the second longitudinal edge 21.

[0037] The first support part 15 can be a bottom disk and the second support part 16 a top disk, or vice versa. For example, the first support part 15 is arranged adjacent to the motor 12 of the fan 10, while the second support part 16 is located on the inlet side of the fan 10, i.e., upstream of the second support part 15.

[0038] The transition from the first longitudinal edge 20 to the outer edge 19 forms a first connection point X1. The transition from the second longitudinal edge 21 to the outer edge 19 forms a second connection point X2. The transition from the first longitudinal edge 20 to the inner edge 18 forms a third connection point X3. The transition from the second longitudinal edge 21 to the inner edge 18 forms a fourth connection point X4. At connection points X1 to X4, the longitudinal edges 20 and 21 are connected to their respective associated support sections 15 and 16.

[0039] The connection between the impeller blades 17 and the support parts 15, 16 is achieved, for example, by a material-bonded connection, e.g., a welded joint. Additionally or alternatively, an adhesive bond can also be achieved. In a modified embodiment, the two support parts 15, 16 and the impeller blades 17 are designed as a monolithic body and are therefore seamless.

[0040] A virtual connecting line G extends through the first connection point X1 (transition from the first longitudinal edge 20 to the outer edge 19) and the second connection point X2 (transition from the second longitudinal edge 21 to the outer edge 19). Along the connecting line G, the distance between the first connection point X1 and the second connection point X2 defines a paddle wheel height S. Along the first longitudinal edge 20, the paddle wheel 17 has a first length L1 between the first connection point X1 and the third connection point X3. Along the second longitudinal edge 21, the paddle wheel 17 has a second length L2 between the second connection point X2 and the fourth connection point X4.

[0041] Compared to the virtual connecting line G, the outer edge 19 is recessed at least at one point and there forms the boundary of an edge recess 25. The edge recess 25, viewed from the connecting line G, is concave and has a local minimum point P.

[0042] The minimum point P, viewed perpendicular to the line G, has a minimum distance T from the line G. Parallel to the line G, the minimum point P has a distance from the first point X1, which defines a first height H1, and a distance from the second point X2, which defines a second height H2. The sum of the first height H1 and the second height H2 equals the impeller height S. The first height H1 is, in particular, less than the second height H2.

[0043] Preferably, the first height H1 has a value of at least 5.0%, 7.5%, 10%, or 15% of the impeller height S. Preferably, the first height H1 has a value of at most 40%, 30%, 25%, 20%, or 17.5% of the impeller height S. The specified minimum and maximum values ​​can be combined arbitrarily.

[0044] It is preferred that the minimum point spacing T is at least 2.5%, 5.0%, 7.5%, or 10% of the first length L1. Preferably, the minimum point spacing T is at most 25%, 20%, 15%, or 12.5% ​​of the first length L1. The minimum and maximum values ​​can be combined arbitrarily.

[0045] It is preferred if the outer edge 19 has only a single minimum point P, the distance between which T lies within the specified range. Preferably, the outer edges 19 have a profile in which they only define a single minimum point P, or, if several local minimum points P are present, the minimum points P have different distances T between them.

[0046] Starting from the lowest point P, the outer edge at the in the Figures 2 and 3 In the illustrated embodiments, a first edge section 26 is provided on the side facing the first longitudinal edge and a second edge section 27 on the side facing the second longitudinal edge. The first edge section 26 and the second edge section 27 are concavely curved and preferably have different maximum curvatures. Preferably, the maximum curvature of the first edge section 26 is greater than that of the second edge section 27.

[0047] Optionally, the outer edge 19 can have additional edge sections besides the first edge section 26 and the second edge section 27, e.g. a third edge section 28 and / or a fourth edge section 29 ( Figure 2 The third edge segment 28 can connect to the first edge segment 26 and / or the fourth edge segment 29 can connect to the second edge segment 27. The third edge segment 28 and the fourth edge segment 29 are convex when viewed from the virtual connecting line G.

[0048] Optionally, the outer edge 19 can have another edge segment, which may be concavely curved from the perspective of the connecting line G, for example a fifth edge segment 30. The fifth edge segment 30 can connect to the fourth edge segment 29 and / or the second connection point X2.

[0049] In a variation of the in Figure 2In the illustrated embodiment with concave and convex edge sections, the impeller blades 17 can also have outer edges 19 that have only concave edge regions, for example the first edge section 26 and the second edge section 27. The edge sections 26, 27 can extend from the lowest point P to the first connection point X1 and to the second connection point X2, respectively.

[0050] The invention relates to an impeller 11 with two support parts 15, 16 and several impeller blades 17, which are arranged between the two support parts 15, 16 and are connected to the first support part 15 by a first longitudinal edge 20 and to the second support part 16 by a second longitudinal edge 21. An outer edge 19 of each impeller blade 17 connects the two longitudinal edges 20, 21 and has an edge recess 25 at which the outer edge 19 has a local low point P. The position of the low point P is closer to the support part 15, 16 in which higher internal stresses or loads occur during operation of the impeller 11. Reference symbol list:

[0051] 10Fan 11Impeller 12Electric motor 15 first support part 16 second support part 17 impeller blade 18 inner edge 19 outer edge 20 first longitudinal edge 21 second longitudinal edge 25 Edge recess 26 First edge section 27 Second edge section 28 Third edge section 29 Fourth edge section 30 Fifth edge section Axial direction D axis of rotation G connecting line H1 first height H2 second height L1 first length L2 second length Local low point S impeller height T low point distance X1 first connection point X2 second connection point X3 third connection point X4 fourth connection point

Claims

1. Impeller (11) for a fan (10), comprising: - a first support part (15), - a second support part (16) arranged parallel to an axis of rotation (D) of the impeller (11) and spaced apart from the first support part (15), - several impeller blades (17) extending between the support parts (15, 16) and attached to the first support part (15) with a first longitudinal edge (20) and to the second support part (16) with a second longitudinal edge (21), wherein an outer edge (19) of each impeller blade (17) extends between a first connection point (X1) at the transition to the first longitudinal edge (20) and a second connection point (X2) at the transition to the second longitudinal edge (21) and defines an edge recess (25) when compared with a virtual connecting line (G) extending through the connection points (X1, X2),and wherein the outer edge (19) is located at a greater distance from the axis of rotation (D) of the impeller (11) than an inner edge (18) of the same impeller blade (17) connecting the two longitudinal edges (20, 21) on the side opposite the outer edge (19), wherein the first longitudinal edge (20) has a first length (L1), wherein an impeller height (S) is defined by the distance, measured parallel to the connecting line (G), between the first connection point (X1) and the second connection point (X2), wherein the edge depression (25) has a local low point (P) which has a low point distance (T) from the connecting line (G), measured perpendicular to the connecting line (G),wherein a first height (H1) defines a distance of the local minimum (P) from the first longitudinal edge (20) to be measured parallel to the connecting line (G), and a second height (H2) defines a distance of the local minimum (P) from the second longitudinal edge (21) to be measured parallel to the connecting line (G), and wherein the first height (H1) is less than the second height (H2).

2. Wheel according to claim 1, wherein the low point distance (T) is at least 2.5% or at least 5.0% or at least 7.5% or at least 10% of the first length (L1).

3. Wheel according to claim 1 or 2, wherein the low point distance (T) is at most 25% or at most 20% or at most 15% or at most 12.5% ​​of the first length (L1).

4. Impeller according to one of the preceding claims, wherein the low point distance (T) is 2.5% to 25% of the first length (L1) or 2.5% to 20% of the first length (L1) or 5.0% to 15% of the first length (L1) or 7.5% to 12.5% ​​of the first length (L1).

5. Impeller according to any of the preceding claims, wherein the first height (H1) is at least 5.0% or at least 7.5% or at least 10% or at least 15% of the impeller height (S).

6. Impeller according to any of the preceding claims, wherein the first height (H1) is at most 40% or at most 30% or at most 25% or at most 20% or at most 17.5% of the impeller height (S).

7. Impeller according to any of the preceding claims, wherein the first height (H1) is 5.0% to 40% or 7.5% to 30% or 10% to 25% or 10% to 20% or 15% to 20% of the impeller height (S).

8. Wheel according to one of the preceding claims, wherein the outer edge (19) has a concavely curved first edge section (26) and a concavely curved second edge section (27) along the edge recess (25), which adjoin each other and whose maximum curvatures are of different sizes.

9. Wheel according to claim 8, wherein the first edge section (26) and second edge section (27) connect to the local low point (P) of the edge recess (25).

10. Wheel according to claim 8 or 9, wherein a convexly curved third edge section (28) is connected to the concavely curved first edge section (26).

11. Wheel according to one of claims 8 to 10, wherein a convexly curved fourth edge section (29) is connected to the concavely curved second edge section (27).

12. Wheel according to claim 10 or 11, wherein at least one of the convex curved edge sections (28, 29) is joined by a further concave curved edge section (30).

13. Impeller according to one of the preceding claims, wherein the stresses occurring during operation within the first support part (15) are greater than within the second support part (16).

14. Impeller according to one of the preceding claims, wherein the support parts (15, 16) and the paddle wheels (17) are connected to each other by means of a material-bonded connection and / or an adhesive connection or wherein the support parts (15, 16) and the paddle wheels (17) form a monolithic body.

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