AXIAL FLOW FAN

Abstract

The invention relates to an axial flow fan (1) comprising a stationary hub (2); comprising an annular stationary frame (3), which surrounds the hub (2) on the outer peripheral side and which is connected to the stationary hub (2) via at least one strut (4, 5, 6); and comprising a fan wheel (8), which is in drive connection with a fan wheel drive (9), which has a rotating fan wheel hub (10), and which has a plurality of fan wheel blades (11), which each comprise a back edge (12), characterized in that the contour of the strut (4, 5, 6) is designed as sine wave shaped, and wherein the back edge (12) is preferably designed as toothed at least in a partial area (13).

Claims

1. An axial flow fan (1) comprising a stationary hub (2); comprising an annular stationary frame (3), which surrounds the hub (2) on the outer peripheral side and which is connected to the stationary hub (2) via at least one strut (4, 5, 6); and comprising a fan wheel (8), which is in drive connection with a fan wheel drive (9), which has a rotating fan wheel hub (10), and which has a plurality of fan wheel blades (11), which each comprise a back edge (12), wherein the back edge (12) faces the at least one strut (4, 5, 6), characterized in that the contour of the strut (4, 5, 6) is designed as sine wave shaped, and wherein the back edge (12) is preferably designed as toothed at least in a partial area (13).

2. The axial flow fan according to claim 1, characterized in that a plurality of struts (4, 5, 6) is provided, of which each has a sine wave shaped contour.

3. The axial flow fan according to claim 2, characterized in that the plurality of struts (4, 5, 6) is distributed in strut groups (14-19) arranged spaced apart from one another.

4. The axial flow fan according to claim 1, characterized in that the strut (4, 5, 6) has a front side (7) which is designed as sine wave shaped.

5. The axial flow fan according to claim 1, characterized in that the strut (4, 5, 6) is designed as asymmetrical.

6. The axial flow fan according to claim 1, characterized in that the strut (4, 5, 6) has an inflow surface (24) which inclines from inside to outside when viewed in the flow direction.

7. The axial flow fan according to claim 1, characterized in that the geometry of the strut (4, 5, 6) is aerodynamically optimized to achieve a low air resistance.

8. The axial flow fan according to claim 1, characterized in that the fan wheel blades (11) are arranged spaced equally apart from one another.

9. The axial flow fan according to claim 1, characterized in that the fan wheel blades (11) are arranged spaced unequally apart from one another.

10. The axial flow fan according to claim 1, characterized in that the toothed partial area (13) is arranged adjacent to the frame (3).

11. The axial flow fan according to claim 4, characterized in that the front side (7) of the strut (4, 5, 6) is not arranged parallel to the back edge (12) of the fan wheel blades (11).

Description

[0025] Additional details, features, and advantages of the present invention arise from the subsequent description of an embodiment by way of the drawings. As shown in:

[0026] FIG. 1 a perspective view of an axial flow fan according to the invention,

[0027] FIG. 2 a perspective partial depiction of an area of the fan wheel, the frame, and the hub of the axial flow fan according to the invention according to FIG. 1, and

[0028] FIG. 3 a perspective partial depiction of an area of the fan wheel, the frame, and the hub of the axial flow fan of a variant of the axial flow fan according to the invention.

[0029] FIG. 1 shows an axial flow fan 1 according to the invention which has a stationary hub 2 and a stationary frame 3 surrounding hub 2 on the outer peripheral side. Frame 3 is, in the example case, designed as annular and has a trough shaped outer contour on which fastening lugs may be applied of which three lugs are visible in FIG. 1 and are designated with the reference numerals 21, 22, and 23.

[0030] Hub 2 and frame 3 may be connected to one another via a strut, wherein the particularly preferred embodiment depicted in FIG. 1 comprises a plurality of struts, of which three are designated with reference numerals 4, 5, and 6. As is clear in FIG. 1, a total of 18 of these types of struts 4, 5, and 6 are provided in this embodiment which are respectively collected into triplet groups 14, 15, 16, 17, 18, or 19. Struts 4, 5, and 6 are arranged closely adjacent in said triplet groups 14 through 19, and the triplet groups are each arranged at the same angular distance between hub 2 and frame 3, as this is shown in detail in the depiction of FIG. 1.

[0031] Axial flow fan 1 according to FIG. 1 additionally has a fan wheel 8, which may be driven by means of a suitable fan drive 9, which is symbolized in FIG. 1 by a dashed circle. Fan drive 9 may be arranged, e.g., in stationary hub 2.

[0032] Fan wheel 8 additionally has a rotatable fan wheel hub 10, on which a plurality of fan wheel blades is arranged, of which one fan wheel blade is designated in FIG. 1 with reference numeral 11 as representative for all fan wheel blades. In the embodiment depicted in FIG. 1, the fan wheel blades extend from fan wheel hub 10 up to an outer encompassing fan collar 20, as this is shown in detail in the depiction of FIG. 1.

[0033] As is clear from an overview of FIGS. 1 and 2, the contours of struts 4, 5, and 6 is designed as sine wave shaped, wherein the sine wave shaped design arises from the sine wave shaped course of a front edge 7 of struts 4, 5, and 6 in the particularly preferred embodiment shown in FIG. 2.

[0034] Furthermore, FIG. 2 illustrates in particular that a back edge 12 of fan wheel blades 11 is designed as toothed at least in a partial area 13. In the embodiment depicted in FIG. 2, toothed partial area 13 connects to the frame and extends across a partial section of back edge 12 in the direction of hub 2. It is basically also possible, to design entire back edge 12 as toothed.

[0035] As is additionally clear from FIG. 2, struts 4, 5, and 6 have inflow surfaces, of which inflow surface 24 as represented on strut 4 is designated as representative of all inflow surfaces. Said inflow surface 24 is inclined from inside to outside when viewed in the inflow direction on the strut.

[0036] In the embodiment depicted in FIGS. 1 and 2, the fan wheel blades are provided spaced uniformly apart from one another.

[0037] FIG. 3 shows that wider struts 4 may also be used instead of the relatively thin struts from FIGS. 1 and 2. According to FIG. 3, front side 7 of strut 4 has the sine wave shaped contour. Front side 7 transitions into inflow surface 24 with a flow optimized radius R. Radius R is preferably at least 3 mm, particularly preferably at least 5 mm.

[0038] It is, however, also possible to provide fan wheel blades 11 in unequal distances to one another which, at least in many embodiments, may produce another improvement in the noise behavior of axial flow fan 1 according to the invention.

[0039] In addition to the preceding written disclosure of the invention, reference is hereby explicitly made to the graphic representation of the invention in FIGS. 1 and 2 as a supplemental disclosure.

REFERENCE SIGN LIST

[0040] 1 Axial flow fan [0041] 2 Hub [0042] 3 Frame [0043] 4, 5, 6 Struts [0044] 7 Front side, also; front edge [0045] 8 Fan wheel [0046] 9 Fan wheel drive [0047] 10 Fan wheel hub [0048] 11 Fan wheel blades [0049] 12 Back edge [0050] 13 Partial area [0051] 14-19 Strut groups/triplet groups [0052] 20 Fan collar [0053] 21-23 Fastening lugs [0054] 24 Inflow surface