RADIAL FAN WITH TAPERED TONGUE GEOMETRY

Abstract

Radial fan has tapered tongue geometry, impeller with impeller blades extending in radial direction about axis of rotation, and volute casing accommodating impeller rotatable about axis of rotation. Impeller blades each have a radially outward end edge, and end edges directly adjacent in circumferential direction that span an imaginary surface therebetween. Volute casing has outlet port for radially ejecting a fluid flow by impeller that is delimited in circumferential direction about axis of rotation by a tongue. At transition to a spiraled casing part of volute casing, the tongue has radially inward inner edge with two sections transitioning into one another via an extremum at a transition point. At least one section is inclined relative to axis of rotation and/or relative to radially outward end edges of impeller blades and intersects with at least one radially outward end edge and adjacent lateral surface up to its center in radial direction.

Claims

1. A radial fan (1) with a tapered tongue geometry, having an impeller (10) with a plurality of impeller blades (11) extending in the radial direction (R) about an axis of rotation (X), and a volute casing (20) accommodating the impeller (10) rotatable about the rotational axis (X), wherein the impeller blades (11) each have a radially outward end edge (12) and respective two end edges (12) directly adjacent in the circumferential direction (U) span an imaginary lateral surface therebetween, wherein the volute casing (20) has an outlet port (21) for radially ejecting a fluid flow that may be generated by the impeller (10) and which is delimited in the circumferential direction (U) about the axis of rotation (X) by a tongue (22), characterized in that the tongue (22) has a radially inward inner edge (25) at a transition (23) to a spiraled casing part (24) of the volute casing (20), having two sections which transition into one another via an extremum at a transition point (26), wherein at least one of the sections is inclined relative to the axis of rotation (X) and/or relative to the radially outward end edges (12) of the impeller blades (11) and intersects with at least one of the radially outward end edges (12) and a respective adjacent lateral surface up to its center in a projection in the radial direction (R).

2. The radial fan according to claim 1, wherein at least one of the sections in a projection in the radial direction (R) intersects with two of the radially outward end edges (12) and the lateral surface therebetween.

3. The radial fan according to claim 1, wherein the inner edge (25) has at least one uniform or varying concave and/or convex curvature, the vertex of which forms the extremum.

4. The radial fan according to claim 1, wherein the transition point (26) is located in a central plane (E) centrally dividing the outlet port (21) and/or the impeller blades (11) in the axial direction.

5. The radial fan according to claim 1, wherein the inner edge (25) has two outer peripheral points (27) in the axial direction and an intermediate point (26) located therebetween and, in particular, centrally between the peripheral points (27), in particular corresponding to the transition point (26) of the inner edge (25), wherein the peripheral points (27) and the intermediate point (26) have a substantially identical distance from the axis of rotation (X) in the radial direction (R), or wherein the peripheral points (27) have a greater distance from the axis of rotation (X) than the intermediate point (26).

6. The radial fan according to claim 1, wherein the transition (23) of the tongue (22) to the spiraled casing part (24) of the volute casing (20) is rounded and/or stepless and/or free of kinks.

7. The radial fan according to claim 1, wherein the tongue (22) terminates at a radially outward outer edge (30) which has two sections (31, 32) transitioning into one another via an extremum at a transition point (33), wherein at least one of the sections (31, 32) is inclined relative to the axis of rotation (X) and/or relative to the radially outward end edges (12) of the rotor blades (11) and intersects in a projection in the radial direction (R) with at least one of the radially outer end edges (12) and a respective adjacent lateral surface, in particular, by a quarter and/or up to its center.

8. The radial fan according to claim 7, wherein the outer edge (30) has at least one uniform or varying concave and/or convex curvature, the vertex of which forms the extremum.

9. The radial fan according to claim 7, wherein the transition point (33) is located in a central plane (E) centrally dividing the outlet port (21) and/or the impeller blades (11) in the axial direction.

10. The radial fan according to claim 7, wherein the outer edge (30) has two outer peripheral points (34) in the axial direction and an intermediate point (33) located therebetween and, in particular, centrally between the peripheral points (34), in particular corresponding to the transition point (33) of the outer edge (30), wherein the peripheral points (34) and the intermediate point (33) have a substantially identical distance from the axis of rotation (X) in the radial direction (R), or wherein the peripheral points (34) have a greater distance from the axis of rotation (X) than the intermediate point (33).

11. The radial fan according to claim 8, wherein the curvature and/or individual curvatures of the outer edge (30) is/are less than a curvature of the inner edge (25), and/or the cross-section of the outlet port (21) passable by a flow is smaller at the inner edge (25) than at the outer edge (30).

12. The radial fan according to claim 7, wherein, at the tongue (22), a curved and/or stepless plane spans between the inner edge (25) and the outer edge (30), the curvature of which decreases in particular uniformly from the inner edge (25) to the outer edge (30).

Description

[0033] Other advantageous developments of the invention are characterized in the dependent claims or are presented in detail below along with the description of the preferred embodiment of the invention with reference to the figures. In the drawings:

[0034] FIG. 1 shows a radial fan in an axial top view;

[0035] FIG. 2 shows the radial fan in a sectional view;

[0036] FIG. 3 shows the radial fan in a side view;

[0037] FIG. 4 is a perspective detailed view of the region of the tongue of the radial fan.

[0038] The figures are schematic for illustration. Similar reference numbers in the figures indicate similar functional and/or structural features.

[0039] FIG. 1 shows a radial fan 1 in an axial top view with the suction or inlet port 28 of the volute casing 20 and, therethrough, the impeller 10 arranged in the volute casing 20 being visible.

[0040] The impeller 10 is arranged in the volute casing 20 so as to be rotatable about the axis of rotation X, a plurality of impeller blades 11 of the impeller 10 extending radially outwards in the radial direction R, whereby an air or fluid flow may be generated when the impeller 10 is rotating.

[0041] Thus, the impeller 10 draws in air or a fluid through the inlet port 28 while rotating in the circumferential direction U about the axis of rotation X, transports it into the spiraled casing part 24 and there, as in the variant shown, clockwise about the axis of rotation X in order to eject the fluid from the volute casing 20 at the outlet port 21 opening in the radial direction R.

[0042] Radially outward, this fluid flow is directed by the casing wall 29 radially delimiting the volute casing 20 or the spiraled casing part 24, wherein the fluid flow or the fluid, upon passage from the spiraled casing part 24 into the outlet port 21, impacts radially inward on a transition 23 of the spiraled casing part 24, on the so-called tongue 22 of the outlet port 21, delimiting it radially inward.

[0043] This results in power losses and noise generation which are to be optimized, i.e., minimized.

[0044] To reduce the losses and the noise generated, in the illustrated variant of the radial fan 1, as shown in FIG. 2 in particular, it is provided for the tongue 22 to have a radially inward inner edge 25 at the transition 23 to a spiraled casing part 24 of the volute casing 20, which is inclined relative to the axis of rotation X and relative to radially outward end edges 12 of the impeller blades 11 and intersects with at least two of the radially outward end edges 12 of the impeller blades 11 in a projection in the radial direction R.

[0045] As also shown in FIG. 2, the inner edge 25 is not arranged in the transition 23 from the tongue 22 into the spiraled casing part 24, but rather forms the boundary or boundary line between a section of the tongue 22 extending linearly in the axial view and the transition 23 characterized by radii and fillets into the spiraled casing part 24.

[0046] The inner edge 25 has two sections, exactly one such section being visible in the sectional view of FIG. 2, since the section is in the central plane E which centrally divides the outlet port in the axial direction, as shown in FIG. 3. The two sections extend from a respective outer peripheral point 27 located on the outside of the tongue 22 in the axial direction to a common transition point 26, at which the sections transition into one another. The two sections are inclined or tilted in opposite directions relative to one another, each intersecting with two of the radially outward end edges 12 in a projection in the radial direction. Two dotted projection lines P are indicated for illustration, a first projection line P extending from the transition point 26 and a second projection line P extending from the visible peripheral point 27 in the radial direction R to the axis of rotation X. As may be seen from the projection lines P, the sections of the inner edge 25 each and always intersect with exactly two of the end edges 12 of the impeller blades 11, independently of the rotational position of the impeller 10.

[0047] This geometric ratio already results in a particularly advantageous reduction of power loss and noise or sound level generated during operation. This advantageous behavior is additionally improved by the fact that, in a side view in the radial direction, as shown in FIG. 3, for example, the inner edge 25 or the sections of the inner edge 25 do not extend linearly, but are concavely curved, the inner edge 25 in the variant shown being determined substantially by two or three curvatures steplessly transitioning into one another without any kinks.

[0048] At the outer peripheral points 27, a first curvature is provided, which respectively transitions into a common second curvature having an extremum in the transition point 26 and being less curved than the first curvature.

[0049] In order not to lose the advantageous effects generated at the inner edge 25 across the tongue 22, it is provided for an outer edge 30 of the tongue 22 located outward in the radial direction R, as also visible in FIGS. 1 and 2, is designed similarly to the inner edge 25.

[0050] With reference to FIG. 3, it should be noted that the outer edge 30 of the tongue 22, at or with which the outlet port 21 terminates in the radial direction R, also has two sections 31, 32 inclined in opposite directions relative to one another and extending towards one another from a respective outer peripheral point 34 to an intermediate or transition point 33 located in the central plane E and where the sections 31, 32 transition into one another.

[0051] The outer edge 30 or the extension of the outer edge 30 is also determined by two or three curvatures, a respective first curvature at the peripheral points 34 transitioning into a common and also smaller second curvature through the transition point 33 with its extremum at the transition point 33.

[0052] However, contrary to the inner edge 25, the sections 31, 32 of the outer edge 30 are not required to intersect with respective two of the end edges 12 of the impeller blades 11 in a projection in the radial direction. Herein, for example, it is provided for the sections 31, 32 of the outer edge 30 to each and always intersect with exactly one of the end edges 12, i.e., independently of the rotational position of the impeller 10.

[0053] The plane at the tongue 22 delimiting a cross-section of the outlet port 21 passable by a flow from the inner edge 25 to the outer edge 30 is also curved and stepless and free of any kinks, and the curvatures at the inner edge 25 transition uniformly into the curvatures of the outer edge 30.

[0054] Moreover, FIG. 4 shows a perspective detailed view of the radial fan 1 according to FIGS. 1 to 3, the detailed view showing the region of the tongue 22 or of the outlet port 21 in an enlarged manner. The perspective representation particularly clearly shows the extension of the inner edge 25 that forms the boundary line between a plane spanned by the tongue 22 and the transition 23 of the tongue 22 into the spiraled casing part 24. The inner edge 25 or the tongue 22 curves concavely at the inner edge 25, such that the cross-section of the outlet port 21 passable by a flow flares from the visible peripheral point 27 to the intermediate or transition point 26.

[0055] As shown in the sectional view according to FIG. 2, the schematically indicated projection 40 of the inner edge 25 according to FIG. 4 or the section shown between the visible peripheral point 27 and the intermediate or transition point 26 of the inner edge 25 directed along the schematically indicated projection lines P in the radial direction R intersects with at least one of the radially outward end edges 12 and a respective adjacent lateral surface up to its center and, herein, specifically two directly adjacent radially outward end edges 12 and the lateral surface therebetween spanned by the two end edges 12. For further illustration, by way of example, an imaginary lateral surface 41 is indicated between two end edges 12 adjacent to the intersected end edges 12.

[0056] The practice of the invention is not limited to the preferred exemplary embodiments set forth above. Instead, a number of variants may be contemplated which make use of the solution shown even in case of basically different embodiments.