DIAGONAL IMPELLER FOR A DIAGONAL FAN, AND DIAGONAL FAN

Abstract

A diagonal impeller for a diagonal fan (11), comprising a carrier plate (33) over the outer periphery of which a plurality of vanes (36) are distributed and which consists of a rotationally symmetrical main body (60), which upstream has a closed head region (63), which transitions in a flowing manner into a lateral surface (67), which extends as far as the foot region (68), wherein the diameter of the foot region (68) is greater than that of the head region (63) and the vanes (36) extend at least over portions along the lateral surface (67), and wherein the lateral surface (67) has at least one S-shaped undulation (70) between the foot region (68) and the head region (63). (See FIG. 1).

Description

This application claims priority of German Patent Application No. 10 2012 106 411.3 filed Jul. 17, 2012, which is hereby fully incorporated herein by reference.

The invention relates to a diagonal impeller for a diagonal fan, and to a diagonal fan for gaseous media.

A diagonal impeller in a diagonal fan is known from DE 10 2010 032 168 A1. Such diagonal fans can convey a flow medium consisting of air or other gases from inside diagonally to outside. Fans of this type can be used for example at the start, within, or at the end of pipelines, wherein the use is not limited to the use of pipeline systems.

Such a diagonal fan comprises a diagonal impeller, to which a guide device for increasing the pressure of the flow medium adjoins in the axial direction. The diagonal impeller consists of a carrier plate with vanes arranged thereon, which extend radially outwardly in the direction of a cover plate. The cover plate is fastened to an inlet nozzle, which is in turn arranged on an outer housing portion of an intake unit. The diagonal impeller is driven by a motor, wherein the motor shaft of said motor carries the carrier plate. This consists of a rotationally symmetrical main body, which comprises a closed head region upstream, which transitions in a flowing manner into a lateral surface, which extends into a foot region, wherein the diameter of the foot region is greater than that of the head region. The lateral surface is conical in this case and forms a diagonally outwardly extending flow duct with the cover plate.

An analogously formed carrier plate is known from GB 8 49 744 B.

A diagonal impeller with a carrier plate is also known from US 2003/0206800 A1, in which the lateral surface is formed in the manner of a paraboloid of revolution instead of being conical. Due to increasingly stricter guidelines on energy conservation, it is necessary to improve the efficiency of such diagonal impellers so as to reduce the increased noise formation caused by the geometry thereof.

The object of the invention is to create a diagonal impeller for a diagonal fan, and a diagonal fan, with which the efficiency is further increased and the noise emission is further reduced.

This object is achieved by the features in the independent claims relating to the diagonal impeller and the diagonal fan. Further advantageous embodiments and developments are disclosed in the other claims.

With the diagonal impeller according to the invention the lateral surface extending between the foot and head region of the rotationally symmetrical main body of the carrier plate has at least one S-shaped undulation. As a result of this S-shaped undulation, the inclination changes along the lateral surface and, as a result of the S-shaped contour of the lateral surface, a changed boundary-layer separation of the flow is enabled by the lateral surface. This leads both to a noise reduction and to an increase in efficiency. It has surprisingly been found that at least one S-shaped undulation in the contour of the lateral surface results in these advantages.

The S-shaped undulation in the lateral surface is preferably formed in that, starting from the head region, a first portion with a small gradient angle to the axis of rotation is provided and transitions, in a second portion of the lateral surface arranged downstream, into a larger flow angle to the axis of rotation. This is the simplest geometrical form of the S-shaped undulation. Flowing transitions are provided therebetween so as to achieve an aerodynamic guidance of the flow medium and to convey said medium in this manner.

The transition from a small gradient angle in the lateral surface in the vicinity of the head region to a larger gradient angle of the lateral surface, which transitions into the foot region, is preferably provided in the central region along the flow path of the carrier plate. This has proven to be particularly energy efficient.

In accordance with a further embodiment, starting from a virtual conical lateral surface between the foot region and the head region, a first undulation of the S-shaped undulation runs radially outside the virtual conical lateral surface and an adjoining second undulation runs within the virtual conical lateral surface and a successive third undulation again runs outside the virtual conical lateral surface, which transitions into the foot region. This course of the lateral surface constitutes a further optimisation for noise reduction and an increase in efficiency.

A preferred embodiment of the diagonal impeller is enabled by a bell-shaped main body of the carrier plate. The flow first entering the intake unit thus experiences a slight deflection, whereas the change in direction of the flow is increased in the direction of the foot region and a build-up of pressure is obtained. As a result of this bell shape of the main body, the saving in energy is further increased.

The object of the invention is also achieved by a diagonal fan, in which the diagonal impeller according to the invention is used. This diagonal impeller interacts with a cover plate in an intake unit and enables both an increase in efficiency and a noise reduction.

In accordance with a first embodiment a gap is formed between the vanes on the carrier plate and the cover plate. In this embodiment the carrier plate is arranged separately from the cover plate, wherein the increase in efficiency is also achieved with the stationary cover plate and the rotating carrier plate.

In accordance with an alternative embodiment the cover plate is arranged fixedly on the free ends of the carrier plate. In this embodiment too, in which the cover plate and the carrier plate are driven together in a rotating manner, the embodiment of the at least one S-shaped undulation in the lateral surface has proven to be advantageous for saving energy.

In accordance with a further preferred embodiment of the invention, the cover plate has at least one S-shaped undulation along its lateral surface between an inlet region and an outlet region. The flow conditions can be promoted further as a result of this additionally contoured lateral surface of the cover plate.

In the embodiment of the at least one S-shaped undulation at the carrier plate and the cover plate, these are preferably associated with one another in a corresponding manner so as to achieve favourable flow conditions.

The invention and further advantageous embodiments and developments thereof will be described and explained in greater detail hereinafter on the basis of the examples illustrated in the drawings. The features to be derived from the description and the drawings can be applied in accordance with the invention either individually or together in any combination. In the drawings:

FIG. 1 shows a schematic sectional illustration of a diagonal fan according to the invention,

FIG. 2 shows a perspective view of a diagonal impeller according to the invention,

FIG. 3 shows a schematically simplified illustration of the diagonal impeller according to FIG. 2 without vanes, and

FIG. 4 shows a schematically simplified sectional view of a diagonal impeller and a cover plate according to a diagonal fan according to FIG. 1.

A schematic sectional illustration of a diagonal fan 11 is illustrated in FIG. 1, said fan comprising an outer housing portion 12, in particular a housing casing, which surrounds a circular cylindrical straight cylinder interior. At the left-hand and right-hand end wall 14, 15 of said housing portion, a right-hand and left-hand flange 17, 18 respectively are fixedly attached externally to the housing portion 12. By means of these flanges 17, 18, a respective pipeline 21, 22 (illustrated schematically) can be connected to either end of the housing portion 12 and therefore to the diagonal fan 11. The diagonal fan 11 can thus be installed between these pipelines 21, 22. An outer diameter of the pipelines 21, 22 may also correspond to the outer diameter of the housing portion 12. The pipelines 21, 22 may also each have a diameter deviating from the diameter of the housing portion 12, and may be connected via a corresponding pipe adapter to the diagonal fan 11.

The diagonal fan 11 has a diagonal impeller 26, which is assigned on the inflow side to an intake unit 29. On the outflow side of the diagonal impeller 26, a guide device 28 followed by a diffuser 30 are formed inside the diagonal fan 11. The diffuser 30 is formed by a blow-out unit 31. The gaseous flow medium pushed through the diagonal fan 11 by means of the diagonal impeller 26 circulates around a central interior of the diagonal fan 11, which is defined inwardly by a carrier plate 33 of the diagonal impeller 26 and an intermediate casing 34 adjoining the carrier plate 33 aerodynamically. The carrier plate 33 curves on the outflow side in an axial direction, so that it contacts the intermediate casing 34, oriented in the axial direction, aerodynamically. The flow medium therefore flows radially outwardly past the carrier plate 33 and the intermediate casing 34.

The diagonal impeller 26 has peripherally distributed vanes 36, which are fastened on one side to the carrier plate 33. On the opposite side, free vane ends 37 of the vanes 36 point toward a peripheral face 39 of a cover plate 40, which is fastened to the housing portion 12. A gap 43 is formed therebetween between the vane ends 37 of the vanes 36 and the peripheral surface 39. The vanes 34 are profiled cross-sectionally for example and are three-dimensionally twisted. The inlet edges of the vanes 36 on the inflow side oriented approximately perpendicularly to the direction of flow of the inflowing flow medium and are provided with a rounded portion. The outlet edge of the vanes 36 on the outflow side is likewise oriented approximately perpendicularly to the diagonal flow leaving on the outflow side. The cover plate 40 may form part of an inlet nozzle 41. Alternatively, the inlet nozzle 41 can be fastened to the housing portion 12 and may engage around or carry the cover plate 40, so that an aerodynamic transition between the intake unit 29 and guide device 28 is provided. If the inlet nozzle 41 and cover plate 40 are each formed separately, an intermediate annular gap is produced, which can be sealed by a seal element. Alternatively, such an annular gap may also be formed as a flow labyrinth.

The flow leaving the diagonal impeller 26 then flows through the region of the guide device 28. In this portion of the diagonal fan 11, peripherally distributed stationary guide vanes 45 are arranged between the intermediate casing 34 and the housing portion 12. The flow leaving in a helical, diagonal direction of the diagonal impeller 26 is deflected in an axial direction of flow by the guide vanes 45. Similarly to the vanes 36 of the diagonal impeller 26, the guide vanes 45 in the present example are also profiled and three-dimensionally twisted. Alternatively, the profiling of the vanes 36 and/or the guide vanes 45 could also be omitted.

A motor 50, which drives the diagonal impeller 26 by means of a driveshaft 51, is located in the interior space 47 formed by the carrier plate 33 of the diagonal impeller 26 or by the intermediate casing 34 of the guide device 28. The motor 50 is flange-mounted on a motor holder, which extends from the intermediate casing 34 into the interior space 47.

After the guide device 28, the diffuser 30 is formed downstream thereof. The diffuser 30 is constructed by an annular flow duct, that increases in a downstream direction, between a motor cover 54 and a housing wall 56 of the blow-out unit 31. The motor cover 54 is fastened to the intermediate casing 34 of the guide device 28 by means of a plurality of screws (not illustrated here) and closes the interior space 47 on the outflow side.

The carrier plate 33 of the diagonal impeller 26 is fastened to the motor 50, in particular to the driveshaft 51, via a fastening element 61. In this embodiment the gap 43 is set between the free vane ends 37 of the diagonal impeller 26 and the peripheral surface 39 of the cover plate 40 by means of the fastening element 61 and the driveshaft 51.

The diagonal impeller 26 is illustrated in perspective view in FIG. 2. The carrier plate 33 consists of a rotationally symmetrical main body 60, which, upstream, has a head region 63 with an end face 64. For example, an opening 65 is provided within the end face 64 so as to introduce a fastening element of the fastening device 61 and so as to exchangeably fix the carrier plate 33 to the motor 50 or the driveshaft 51 thereof. The head region 63 transitions in a flowing manner into a lateral surface 67, which ends in a foot region 68.

To illustrate a first contour of the main body 62 of the carrier plate 33 more clearly, the carrier plate 33 is shown without vanes 36 in FIG. 3.

The main body 60 of the carrier plate 33 has an S-shaped undulation 70. This results for example in the bell shape of the main body 60. In this case the lateral surface 67 has a first portion 71, which directly adjoins the head region 63 and which has a gradient angle α1 to the longitudinal central axis 62 or axis of rotation. A second portion 73 of the lateral surface 67 adjoins this portion 71 and has a gradient angle α2, which is greater than the gradient angle α1. A rounded transition is provided therebetween. A contour deviating from a frustum-shaped contour known from the prior art can thus be obtained, which surprisingly leads to an energy saving. In the exemplary embodiment the portions 71, 73 are of approximately equal length as viewed in the direction of flow. Alternatively, one of the two portions 71, 73 may also be larger than the other portion.

The transitions between the end face 64 in the head region 63 to the first portion 71 and the second portion 73 of the lateral surface 67 in the foot region 68 are formed by radii so as to prevent interruptions to the flow.

A further embodiment of the diagonal impeller 36 with a lateral surface 67, which has at least one S-shaped undulation 70, will be described in greater detail on the basis of FIG. 4. A frustum-shaped cross-sectional geometry of the carrier plate 33 is known from the prior art. This has a lateral surface of the frustum extending in a straight line, which is illustrated as a virtual line 75. An S-shaped undulation 70 may be formed in such a way in this instance that a first undulation 77 extends radially outside the virtual lateral surface 75 and transitions into a second undulation 78, which lies radially within the virtual lateral surface 75, wherein there is then a transition to a third undulation 79, which lies outside the virtual lateral surface 75. Flowing transitions are provided therebetween. Aerodynamic properties can be achieved as a result of this line design. The respective characteristics of the undulations 77, 78, 79, which run within or outside the virtual frustum line 75, are dependent on the length of the carrier plate 33 and the size and further boundary conditions of the intake unit 31. A double or triple S-shaped undulation may also be provided in the lateral surface 67 of the carrier plate 33.

In an embodiment not illustrated in greater detail, the peripheral surface 39 of the cover plate 40 may be formed analogously to the lateral surface 67 of the main body 60 of the carrier plate 33. The S-shaped undulations 70 preferably run in a corresponding manner in the cover plate 40 and the carrier plate 33. The vane ends 37 are adapted to this contour of the cover plate 40.

The above also applies analogously to a further embodiment not illustrated in greater detail, in which the cover plate 40 is connected to the free vane ends 36 of the carrier plate 33 so that the cover plate 40 is received rotatingly with the carrier plate 33 in the intake unit 29.

Claims

1. Diagonal impeller for a diagonal fan, comprising a carrier plate over the outer periphery of which a plurality of vanes are distributed and which consists of a rotationally symmetrical main body, which upstream has a closed head region, which transitions in a flowing manner into a lateral surface, which extends as far as the foot region, the diameter of the foot region being greater than that of the head region and the vanes extending at least over portions along the lateral surface, characterised in that the lateral surface has at least one S-shaped undulation between the foot region and the head region.

2. Diagonal impeller according to claim 1, wherein the lateral surface, starting from the head region, has a first portion with a small gradient angle to the axis of rotation and transitions in a second portion, arranged downstream of the first portion, with a gradient angle greater than then gradient angle of the first portion.

3. Diagonal impeller according to claim 1, wherein the transition from a smaller gradient angle into a steeper gradient angle of the lateral surface is provided in the central region of the flow path along the carrier plate.

4. Diagonal impeller according to claim 1 wherein, starting from a virtual conical lateral surface between the foot region and the head region, a first undulation of the S-shaped undulation runs radially outside the virtual conical lateral surface and an adjoining second undulation of the S-shaped undulation runs within the virtual conical lateral surface and a successive third undulation of the S-shaped undulation runs outside the virtual conical lateral surface.

5. Diagonal impeller according to claim 1, wherein the main body of the carrier plate is bell-shaped.

6. Diagonal fan for gaseous media, comprising a diagonal impeller, which has a carrier plate with a plurality of vanes arranged thereon, with a guide device attached to said diagonal impeller in a downstream direction to increase the pressure of the medium and with a cover plate, which surrounds the carrier plate in the radial direction and extends along the carrier plate, at least over portions, in the axial direction, wherein the diagonal impeller is designed according to claim 1.

7. Diagonal fan according to claim 6, wherein a gap is formed between the vanes of the carrier plate and the cover plate.

8. Diagonal fan according to claim 6, wherein the cover plate is arranged on the vane ends of the vanes of the carrier plate.

9. Diagonal fan according to claim 6, wherein the cover plate has at least one S-shaped undulation along its peripheral surface between an inlet region and an outlet region.

10. Diagonal fan according to claim 6, wherein the S-shaped undulation runs in the cover plate in a manner corresponding to the S-shaped undulation in the carrier plate.