DE102022131248A1 - Diagonal impeller with varying hub area - Google Patents

Abstract

The invention relates to a diagonal impeller (1) with a conical hub (10) which widens from an inflow side (A) to an outflow side (B) in the radial direction (R), wherein a plurality of blades (20) extend radially outward from the hub (10), wherein a pair of blades (23) of two immediately adjacent blades (21, 22) of the plurality of blades (20) defines between them a blade channel (2) through which flow can pass from the inflow side (A) to the outflow side (B), wherein the blade channel (2) is delimited radially inwardly by a surface of the hub (10) extending between the two blades (21, 22), wherein the surface of the hub (10) delimiting the blade channel (2) has a first section (11) and a subsequent second section (12) in the flow direction, wherein the surface is curved in the first section (11) and flat in the second section (12).

Description

The invention relates to a diagonal impeller, the hub of which, together with the blades of the diagonal impeller, defines blade channels, wherein the hub has a changing surface, i.e. a varying hub area, along the flow direction through the blade channel.

A variety of impellers for fans and ventilators are known from the state of the art. In addition to axial impellers and radial impellers, there are also diagonal impellers, as described for example in the documents WO 2020/099027 A1 and DE 20 2010 013 785 U1 be revealed.

So-called diagonal impellers, which can also be referred to as mixed flow impellers, occupy an intermediate position between axial impellers and radial impellers with backward curved blades. The typical design of a diagonal impeller causes an air or fluid flow similar to the widely used axial fans when it rotates around a rotation axis and at the same time achieves a higher static pressure.

The fluid to be pumped enters along the impeller axis, i.e. along the axis of rotation on an inflow side, and is blown out again at a certain angle to the axis of rotation on the outflow side, i.e. diagonally.

According to the state of the art, the hub of diagonal impellers is usually completely or purely conical, whereby the formation of vortices in the pumped fluid is to be minimized by the conical shape of the impeller hub.

As with all impellers, diagonal impellers also suffer from losses which reduce efficiency and power density. Diagonal impellers also produce noise when operating, which can be annoying depending on the application.

The invention is therefore based on the object of overcoming the aforementioned disadvantages and increasing the efficiency and power density of a diagonal impeller as well as improving the noise behavior of a diagonal impeller rotating during operation.

This object is achieved by the combination of features according to patent claim 1.

According to the invention, a diagonal impeller with a conical hub is therefore proposed, which can be rotated in particular about a rotation axis, wherein the conical hub widens in the radial direction from an inflow side to an outflow side. A large number of blades extend radially outwards from the hub - as is usual with diagonal impellers. Two immediately adjacent blades of the large number of blades each form a blade pair. The blade pair or blade pairs, and more precisely the two blades of the blade pairs, each define a blade channel between them through which fluid, for example air or another gas mixture, can flow from the inflow side to the outflow side. The blade channel is delimited radially inwards by a surface of the hub extending between the two blades. Since this is the surface of the hub, it can also be referred to as the hub surface. It is essential that the surface of the hub delimiting the blade channel has a first section and a subsequent second section in the flow direction, i.e. from the inflow side to the outflow side, wherein the surface is curved in the first section or has a curvature preferably in the radial direction and is flat in the second section. The surface or the hub area varies accordingly, so that the hub is in particular not purely or exclusively conical.

This results in a substantially angular or square shape of the hub or an angular or square cross-section or such a basic shape of the hub in a fluidically rear region of the hub, i.e. on the outflow side, which is determined by the second sections of the surface. In a front region of the hub, i.e. on the inflow side, this is - as described below - preferably determined by a common and rotationally symmetrical shape or a common and rotationally symmetrical, in particular round cross-section or such a basic shape.

If it is not already clear, it should be noted that the plurality of blades forms a plurality of blade pairs, each pair of blades defining a blade channel between them. This results in a plurality of blade channels, each of which is delimited by a respective first section and a respective second section of the surface of the hub.

Furthermore, it follows that the diagonal impeller is rotatable about a rotation axis to which the diagonal impeller is arranged concentrically.

Although the prior art generally provides for the hub to have a completely and exclusively conical shape, in which the cross-section is round at every point along the longitudinal axis, the inventive By flattening the first and second sections of the surface of the hub in the area of the blade channel or the blade channels, it is achieved that the surface or the hub is/are leveled in the aerodynamically rear area of the blade channel or the blade channels. The leveling or flattening in the aerodynamically rear area of the blade channel expands the flow cross-section of the blade channel, which leads to an improvement in efficiency, particularly in the very limited installation space. The design of the diagonal impeller according to the invention thus contributes to increasing the power density.

Typically for diagonal impellers, it can also be provided here that the outside diameter of the diagonal impeller determined by the blades widens from the inflow side to the outflow side and preferably according to the conical shape of the hub. If the blades are covered by a cover plate, which will be explained below, the cover plate can also widen in terms of its diameter from the inflow side to the outflow side and preferably according to the conical shape of the hub.

An advantageous development of the invention provides that the surface of the hub or the hub surface in the first section is curved rotationally symmetrically and/or convexly radially outward relative to an axis of rotation of the diagonal impeller and thus corresponds to a partial surface of a conical or conical body and preferably to a partial surface of the conical basic shape of the hub.

Preferably, all first sections of the surface of the hub correspond to partial surfaces of a common, i.e. single, imaginary cone or taper.

Alternatively, the first sections of the surface of the hub can also be partial surfaces of a common, i.e. single, imaginary sphere or hemisphere or an ellipsoid.

Analogously, all second sections can each correspond to partial surfaces of a side surface of an imaginary pyramid or an imaginary pyramid-shaped body. It follows that such a pyramid or such a pyramid-shaped body has, in addition to its base, a number of side surfaces corresponding to the number of second sections.

It also follows that, despite a conical basic shape, the hub does not have to be completely or purely conical, but the shape of the hub can correspond to a hybrid of a cone and a pyramid, in which the first sections form the conical part of the hub and the second sections form the pyramidal part of the hub.

To improve noise behavior, it can also be provided that the first section of the surface and the second section of the surface merge into one another continuously and/or rounded and/or via a continuous, i.e. jump-free, transition area. Such a corresponding transition results in less flow separation and turbulence, so that correspondingly less noise is generated.

The first section of the surface is preferably at least partially and in particular completely free of overlap, i.e. visible from an inflow-side plan view of the hub and is in particular not overlapped by the blades of the respective associated blade pair. Additionally or alternatively, the second section of the surface can be covered at least partially by a blade, i.e. a blade of the associated blade pair, from an inflow-side plan view of the hub.

Furthermore, it can be provided that the surface of the hub has a third section after the second section in the flow direction, which is arranged on the outflow side of the blade channel, i.e. after the blade channel or outside the blade channel.

In order to reduce noise, it is also preferably provided that the second section of the surface and the third section of the surface merge into one another continuously and/or rounded and/or via a continuous, i.e. again jump-free, transition region.

In particular, all second sections of the surface can merge into a common, i.e. single, third section, which is preferably an outer surface of an imaginary cylinder. It follows that the outer surface of the cylinder or the third section of the surface of the hub preferably completely encircles the axis of rotation in the circumferential direction and further preferably concentrically.

Furthermore, the diagonal impeller can have a cover plate which partially covers the blades, ie in particular all the blades of the plurality of blades on the inflow side in a radially outer region and in particular defines an inflow opening radially inside. The blade channel or the blade channels are thereby preferably limited radially outward by the cover plate. This results in the inventive Proper design allows for smaller angle differences between the cover plate and the hub, which also has a positive effect on noise behavior and efficiency.

Preferably, the blades, i.e. the blades of the blade pair and in particular all blades of the plurality of blades each have an inflow-side base point and an outflow-side base point, at which the blades each adjoin the hub, merge into the hub or are connected to it. According to the embodiment, a boundary line between the first section and the second section of the surface runs in particular in a straight line from an inflow-side base point of a first blade of the blade pair or of a respective blade pair to an outflow-side base point of a second blade of the blade pair or of the respective blade pair.

The first portion of the surface preferably extends from the first blade of the blade pair to the boundary line and the second portion of the surface from the boundary line to the second blade of the blade pair.

Furthermore, there can also be a further or second boundary line between the second section or sections and the third section of the surface, which in particular runs in a circle around an axis of rotation.

It can also or alternatively be provided that the boundary line between the second section or sections and the third section, i.e. the second or further boundary line, forms a tangent to the outflow-side base points of the blades and connects or tangentially connects them to one another. The boundary line between two outflow-side base points of two blades arranged directly next to one another can be curved in particular in the direction of flow and have a kink at each of the outflow-side base points.

Although the diagonal impeller can be made up of several parts, it is preferably made in one piece, so that the hub, blades and, if present, the cover plate are integrally connected to one another. Furthermore, the diagonal impeller is preferably manufactured in an injection molding process using a tool with one-piece slides.

The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

• 1 einströmseitige perspektivische Ansicht eines Diagonallaufrades;
• 2 Seitenansicht des Diagonallaufrades;
• 3 ausströmseitige perspektivische Ansicht des Diagonallaufrades;
• 4a,b einströmseitige Draufsicht auf das Diagonallaufrad;
• 5 einströmseitige Draufsicht auf das Diagonallaufrad mit Querschnitten schematischer Grundkörper.

Other advantageous developments of the invention are characterized in the subclaims or are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. They show:

• 1 inflow perspective view of a diagonal impeller;
• 2 Side view of the diagonal impeller;
• 3 outflow side perspective view of the diagonal impeller;
• 4a ,b inlet side view of the diagonal impeller;
• 5 Inflow side plan view of the diagonal impeller with cross-sections of schematic basic bodies.

The figures are schematic examples. Identical reference symbols in the figures indicate identical functional and/or structural features.

In 1 a diagonal impeller 1 is shown in perspective, with the diagonal impeller being viewed from the inflow side A.

The diagonal impeller 1 has a hub 10, from which blades 20, and in this case specifically five blades 20, extend outwards in the radial direction R. Furthermore, the diagonal impeller 1, which is completely formed in one piece, has a cover disk 30, which completely encircles the axis of rotation X in the circumferential direction U and is connected to the blades 20 in a radially outer region thereof, so that an inflow opening 3 remains free on the radial inside.

Two immediately adjacent blades 20 of the total of five blades 20 form a blade pair 23, so that there are five blade pairs 23. For better clarity, only one blade pair 23 is provided with the corresponding reference symbol. Furthermore, 4b a section with exactly one pair of blades 23 of the intake-side plan view of the diagonal impeller 1 according to 4a shown.

Each of the blade pairs 23 has a first blade 21 and a second blade 22, which define a blade channel 2 between them, through which a 2 The flow S shown as an example can flow from the inflow side A to the outflow side B or is promoted by the rotation of the diagonal impeller 1 about the rotation axis X.

In addition to the surfaces of the respective first blade 21 and second blade 22 facing the respective blade channel 2, the blade channels 2 are each delimited radially on the inside by the hub 10 or the surface of the hub 10. According to the embodiment variant shown, the blade channels 2 are delimited radially on the outside by the cover disk 30.

It is important that the surface of the hub 10 delimiting the blade channel 2 has a first section 11 and a subsequent second section 12 in the flow direction, wherein the surface is curved in the first section 11 or has a curvature in the radial direction R and is flat in the second section 12. The two sections 11, 12 and the transition area 14 between them are particularly visible in the detailed representation of the 4b advantageously. It follows that the flow cross-section, ie the cross-section of the flow channel 2 in its area adjacent to the second section 12, increases in particular compared to its area adjacent to the first section 11, which leads to an improvement in efficiency.

In order to avoid flow separation and vortices arising from a sharp transition between the first section 11 and the second section 12, the transition region 14 between the first and second sections 11, 12 of the surface of the hub 10 is rounded, resulting in a relatively wide transition region 14 which, however, runs along a boundary line or covers or replaces it.

It is further provided that the hub 10, in addition to the essentially conical section, ie the section which widens in the radial direction R and in which the first and second sections 11, 12 are located, has a cylindrical section which defines a third section 13 of the surface of the hub 10. As can be seen in particular in the side view according to 2 recognizable, the second sections 12, ie all five second sections 12, each merge into a common third section 13 by means of a corresponding further transition region 15, wherein the transition region 15 from the second sections 12 to the third section 13 is also rounded or continuous to minimize noise and runs along a corresponding boundary line between the second sections 12 and the third section 13 or covers or replaces them.

At the 2 In the side view shown, it is clearly visible that the boundary line and thus the transition region 15 between the respective second sections 12 and the third section 13 does not run in a straight line, but is curved or bulbous in the flow direction from the outflow-side base point 25 to the outflow-side base point 25 of two immediately adjacent blades 20.

The flattening of the hub 10 or the surface of the hub 10 in the second sections 12 results in the hub 10 not being completely conical, but rather partially angular or pyramid-shaped. This flattening, ie the flat formation of the surface in its second section 12 or in its second sections 12, is in 3 clearly.

Deviating from the transition area 15 between the respective second section 12 to the third section 13, the transition area 14 from the first section 11 to the second section 12 does not run from the outflow-side foot point 25 to the outflow-side foot point 25, but - as in 4a visible for all five transition areas 14 - from an inflow-side base point 24 of a first blade 21 of a blade pair 23 of two immediately adjacent blades 20 to an outflow-side base point 25 of a second blade 22 of the blade pair 23 of two immediately adjacent blades 20. In addition, the transition area 14 between the first section 11 and the second section 12 runs in a straight line between these base points 24, 25 for flow optimization.

4b corresponds to an enlarged detailed view of the diagonal impeller 1 according to 4a , wherein in particular a blade pair 23 formed from two immediately adjacent blades 20 and the blade channel 2 determined by the blade pair 23 are shown. This also makes the curved first section 11 of the surface of the hub 10, the flat or level second section 12 of the surface of the hub 10 and the transition region 14 between the first section 11 and the second section 12 particularly clearly visible.

The inflow side view in 5 corresponds to the inflow side plan view according to 4a , whereby imaginary cutting lines 16, 18 and base surfaces 17, 19 are drawn in for a clearer representation of the mixed form of the hub 10 consisting of a cone and a pyramid resulting from the first sections 11 and the second sections 12.

The first sections 11 correspond to partial surfaces of a single imaginary cone, which also determines the conical basic shape of the hub 10. In a cross section through the hub 10, the cutting lines 16 running in the first sections 11 form part circles or parts of a common, ie single, circle 17.

Furthermore, the second sections 12 each correspond to partial surfaces of a side surface of a single imaginary and in this case five-sided pyramid, which determines the angular partial shape of the hub 10 or the angular part of the shape of the hub 10. In a cross-section through the hub 10, the cutting lines 18 running in the second sections 12 form corresponding lines as parts of a side surface of a common, i.e. single, pentagon 19, i.e. a regular pentagon 19.

As shown, the blades 20 of the diagonal impeller 1 are preferably evenly distributed and curved in the circumferential direction U around the axis of rotation. In particular, the curvature of the blades 20 results in the second section 12 from the inflow side plan view of the hub 10, ie as shown in the 4a , 4b and 5 shown, partially covered by one of the blades 20 of the blade pair 23 and the first section 11 of the surface is free of coverage.

The invention is not limited in its implementation to the preferred embodiments given above. Rather, a number of variants are conceivable which make use of the solution presented even in fundamentally different embodiments.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• WO 2020099027 A1 [0002]
• DE 202010013785 U1 [0002]

Claims (12)

Diagonal impeller (1) with a conical hub (10) which widens from an inflow side (A) to an outflow side (B) in the radial direction (R), wherein a plurality of blades (20) extend radially outward from the hub (10), wherein a blade pair (23) of two immediately adjacent blades (21, 22) of the plurality of blades (20) defines between them a blade channel (2) through which flow can pass from the inflow side (A) to the outflow side (B), wherein the blade channel (2) is delimited radially inward by a surface of the hub (10) extending between the two blades (21, 22), wherein the surface of the hub (10) delimiting the blade channel (2) has a first section (11) and a subsequent second section (12) in the flow direction, wherein the surface is curved in the first section (11) and in the second section (12) is flat. Diagonal impeller according to Claim 1 , wherein the surface in the first section (11) is rotationally symmetrical and/or convexly curved radially outward to an axis of rotation (X). Diagonal impeller according to Claim 1 or 2 , wherein all first sections (11) each correspond to partial surfaces of a common imaginary cone or a common imaginary sphere or a common imaginary ellipsoid. Diagonal impeller according to one of the preceding claims, wherein all second sections (12) each correspond to partial surfaces of a side surface of an imaginary pyramid. Diagonal impeller according to one of the preceding claims, wherein the first section (11) of the surface and the second section (12) of the surface merge continuously and/or rounded and/or via a continuous transition region (14). Diagonal impeller according to one of the preceding claims, wherein the first section (11) of the surface from an inflow-side plan view of the hub (10) is at least partially and in particular completely free of overlap, and/or wherein the second section (12) of the surface from an inflow-side plan view of the hub (10) is at least partially covered by a blade (20, 22). Diagonal impeller according to one of the preceding claims, wherein the surface of the hub (10) in the flow direction after the second section (12) has a third section (13) which is arranged on the outflow side of the blade channel (2). Diagonal impeller according to the preceding claim, wherein the second section (12) of the surface and the third section (13) of the surface merge continuously and/or rounded and/or via a continuous transition region (15). Diagonal impeller according to one of the two preceding claims, wherein all second sections (12) of the surface merge into a common third section (13), which is in particular an outer surface of an imaginary cylinder. Diagonal impeller according to one of the preceding Claims 7 until 9 , wherein a boundary line between the second portion (12) and the third portion (13) of the surface runs in particular in a circle around an axis of rotation (X). Diagonal impeller according to one of the preceding claims, further comprising a cover disk (30) which partially covers the blades (20, 21, 22) on the inflow side in a radially outer region. Diagonal impeller according to one of the preceding claims, wherein the blades (20, 21, 22) each have an inflow-side base point (24) and an outflow-side base point (25), at which the blades (20, 21, 22) each adjoin the hub (10) or merge into the hub (10) or are connected to the hub (10), and where a boundary line between the first section (11) and the second section (12) of the surface runs in particular in a straight line from an inflow-side base point (24) of a first blade (21) of the blade pair (23) to an outflow-side base point (25) of a second blade (22) of the blade pair (23).