FAN WHEEL FOR AN AXIAL FAN

Abstract

A fan wheel for an axial fan may include a hub and a plurality of blades extending from the hub. Each blade of the plurality of blades may include a blade root coupled to the hub, a blade tip radially distant from the hub, a blade central region lying radially between the blade root and the blade tip, a blade front side facing a pressure side, a blade back side facing a suction side, a transverse profile lying in a cross-sectional plane extending perpendicularly to a radial direction, and a transverse curvature in the transverse profile configured such that the blade front side is curved concavely toward the pressure side and the blade back side is curved convexly toward the suction side. The transverse curvature of at least one blade of the plurality of blades may decrease from the blade central region to the blade tip.

Claims

1. A fan wheel for an axial fan for producing a cooling air flow, comprising: a hub; a plurality of blades extending from the hub, each blade of the plurality of blades including, radially inside, a blade root coupled to the hub and, radially outside, a blade tip distant from the hub; each blade having a blade front side facing a pressure side, a blade back side facing a suction side, and a transverse profile lying in a cross-sectional plane extending perpendicularly to a radial direction; each blade having a transverse curvature in the transverse profile configured such that the blade front side is curved concavely toward the pressure side in the transverse profile and the blade back side is curved convexly toward the suction side in the transverse profile; wherein each blade has a blade central region lying radially between the blade root and the blade tip; and wherein the transverse curvature of the transverse profile of at least one blade of the plurality of blades decreases from the blade central region to the blade tip.

2. The fan wheel according to claim 1, wherein the transverse curvature is constant from the blade central region to the blade root.

3. The fan wheel according to claim 1, wherein the transverse curvature decreases from the blade central region to the blade root.

4. The fan wheel according to claim 3, wherein the transverse curvature decreases more intensively from the blade central region to the blade tip than from the blade central region to the blade root.

5. The fan wheel according to claim 3, wherein the transverse curvature is smaller at the blade tip than at the blade root.

6. The fan wheel according to claim 1, wherein: each blade has a leading edge facing the suction side, a trailing edge facing the pressure side, and a longitudinal profile lying in a longitudinal section plane extending parallel to the radial direction; and at least one blade of the plurality of blades has, in the longitudinal profile, a longitudinal curvature configured such that the blade back side is curved convexly toward the suction side.

7. The fan wheel according to claim 6, wherein, in the longitudinal profile, in a region of the longitudinal curvature the blade front side is concavely curved toward the pressure side.

8. The fan wheel according to claim 6, wherein the longitudinal curvature extends at least from the blade central region to the blade tip.

9. The fan wheel according to claim 6, wherein the longitudinal curvature extends only from the blade central region to the blade tip and the longitudinal profile is rectilinear from the blade central region to the blade root at least on the blade back side.

10. The fan wheel according to claim 6, wherein the longitudinal curvature extends at least in a central region of the transverse profile lying in the transverse profile between the leading edge and the trailing edge.

11. The fan wheel according to claim 6, wherein the longitudinal curvature extends only in a central region of the transverse profile lying in the transverse profile between the leading edge and the trailing edge.

12. The fan wheel according to claim 1, wherein a radius of curvature of the transverse curvature increases from the blade central region to the blade tip.

13. The fan wheel according to claim 1, wherein a radius of curvature of the transverse curvature increases from the blade central region to the blade root.

14. The fan wheel according to claim 1, wherein the plurality of blades extend from the hub in a freestanding manner.

15. An axial fan for producing a cooling air flow for a vehicle radiator, comprising: a fan wheel including: a hub; and a plurality of blades extending from the hub, each blade of the plurality of blades including a blade root coupled to the hub, a blade tip radially distant from the hub, a blade central region lying radially between the blade root and the blade tip, a blade front side facing a pressure side, a blade back side facing a suction side, a transverse profile lying in a cross-sectional plane extending perpendicularly to a radial direction, and a transverse curvature in the transverse profile configured such that the blade front side is curved concavely toward the pressure side in the transverse profile and the blade back side is curved convexly toward the suction side in the transverse profile; wherein the transverse curvature of the transverse profile of at least one blade of the plurality of blades decreases from the blade central region to the blade tip; a fan cover including a casing enclosing the fan wheel in a circumferential direction; and wherein a radial gap is defined radially between the casing and the blade tip of each blade of the plurality of blades.

16. The axial fan according to claim 15, wherein the transverse curvature decreases from the blade central region to the blade root.

17. The axial fan according to claim 16, wherein the transverse curvature decreases more intensively from the blade central region to the blade tip than from the blade central region to the blade root.

18. The axial fan according to claim 15, wherein: each blade has a leading edge facing the suction side, a trailing edge facing the pressure side, and a longitudinal profile lying in a longitudinal section plane extending parallel to the radial direction; and at least one blade of the plurality of blades has, in the longitudinal profile, a longitudinal curvature configured such that the blade back side is curved convexly toward the suction side.

19. A fan wheel for an axial fan, comprising: a hub; and a plurality of blades extending from the hub, each blade of the plurality of blades including a blade root coupled to the hub, a blade tip radially distant from the hub, a blade central region lying radially between the blade root and the blade tip, a blade front side facing a pressure side, a blade back side facing a suction side, a leading edge facing the suction side, a trailing edge facing the pressure side, a transverse profile lying in a cross-sectional plane extending perpendicularly to a radial direction, a transverse curvature in the transverse profile configured such that the blade front side is curved concavely toward the pressure side in the transverse profile and the blade back side is curved convexly toward the suction side in the transverse profile, and a longitudinal section plane extending parallel to the radial direction; wherein the transverse curvature of the transverse profile of at least one blade of the plurality of blades decreases from the blade central region to the blade tip and from the blade central region to the blade root; and wherein the longitudinal curvature of the longitudinal profile of at least one blade of the plurality of blades is configured such that the blade back side is curved convexly toward the suction side.

20. The fan wheel according to claim 19, wherein the longitudinal curvature extends only from the blade central region to the blade tip and the longitudinal profile is rectilinear from the blade central region to the blade root at least on the blade back side.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] There are shown, respectively diagrammatically,

[0025] FIG. 1 an isometric partial view onto a suction side of a fan wheel of an axial fan,

[0026] FIG. 2 an isometric view onto the suction side of the fan wheel in the region of a blade,

[0027] FIG. 3 an isometric complete view onto the suction side of the fan wheel,

[0028] FIG. 4 an axial view onto the axial side of the fan wheel in the region of a blade,

[0029] FIG. 5 a cross-section of the blade of FIG. 4 according to section lines V in FIG. 4,

[0030] FIG. 6 a cross-section of the blade of FIG. 4 according to section lines VI in FIG. 4.

DETAILED DESCRIPTION

[0031] According to FIG. 1, an axial fan 1, which is only partially illustrated, by means of which a cooling air flow can be produced for a vehicle radiator, comprises a fan wheel 2 and a fan cover 3. The fan cover 3, which can also be designated as a fan shroud, directs, in the mounted state of the axial fan 1, the cooling air flow produced by means of the fan wheel 2 from the vehicle radiator to the fan wheel 2. The fan cover 3 has a casing 4, which encloses the fan wheel 2 in a circumferential direction 5, which is indicated in FIG. 1 by a double arrow. A radial gap 6 is formed radially between the casing 4 and the fan wheel 2.

[0032] As can be seen in particular from FIG. 3, the fan wheel 2 has a hub 7 and a plurality of blades 9 projecting substantially radially from the hub 7. The fan wheel 2 with the hub 7 and the blades 8 can be formed by a one-piece injection-moulded part from plastic or metal, in particular light metal.

[0033] The fan wheel 2 has a longitudinal centre axis 9, with respect to which the fan wheel 2 is configured rotationally symmetrically. In the installed state of the fan wheel 2, the longitudinal centre axis 9 forms a rotation axis 10 of the fan wheel 2. This rotation axis 10 defines an axial direction 11, which is indicated in the figures by a double arrow. Perpendicularly to the rotation axis 10 a radial direction 12 extends, which is indicated in the figures for individual blades 8 respectively by a double arrow. The circumferential direction 5 also relates to the rotation axis 10.

[0034] According to FIGS. 1 to 4, each blade 8 has radially inside a blade root 13, which is connected to the hub 7, and radially outside a blade tip 14, which is distant from the hub 7. The fan wheel 2 has a suction side 15, which faces the observer in FIGS. 1 to 4. In the mounted state, this suction side 15 faces the vehicle radiator. Furthermore, the fan wheel 2 has a pressure side 16, which faces away from the observer in FIGS. 1 to 4. The pressure side 16 and suction side 14 form axial sides of the fan wheel 2, which face away from one another.

[0035] Each blade 8 has a blade front side 16 facing the pressure side 16, and a blade back side 18 facing the suction side 15. In addition, each blade 8 has a transverse profile 19, which in FIGS. 1 to 4 is indicated by a broken line respectively for at least one blade 8, and which lies in a cross-sectional plane 20, which is indicated by a broken line in FIG. 4. The cross-sectional plane 20 extends here perpendicularly to the radial direction 12. In FIGS. 5 and 6 such a transverse profile 19 can also be seen. In FIGS. 5 and 6, the cross-sectional plane 20 lies in the plane of the drawing.

[0036] In addition, each blade 5 has in the transverse profile 19 a transverse curvature 21. This transverse curvature 21 causes the respective blade front side 17 in the cross-sectional profile 19 to be curved concavely toward the pressure side 16. At the same time, the respective blade back side 18 in the cross-sectional profile 19 is curved concavely toward the suction side 15.

[0037] According to FIG. 1, the radial gap 6 is therefore situated radially between the casing 4 and the respective blade tip 14. During the operation of the axial fan 1, therefore on rotation of the fan wheel 2, through the radial gap 6 a gap flow 22 can occur, which is indicated in FIG. 1 in a simplified manner by flow arrows. A rotation direction of the fan wheel 2 is indicated here by an arrow 23.

[0038] In order to reduce or respectively minimize these gap flows 22 during the operation of the fan wheel 2, provision is made with regard to the blades 8 that the transverse curvature 21 of the transverse profile 19 decreases from a blade central region 24 to the blade tip 14. This blade central region 24 lies here radially between the blade root 13 and the blade tip 14. The transverse curvature 21, decreasing in the direction of the blade tip 14, can be seen in a particular manner in FIGS. 2 and 4 to 6. Thus, FIG. 5 shows a sectional view according to section lines V of FIG. 4, which corresponds to a cross-section of the blade 8 in the blade central region 24. Compared thereto, FIG. 6 shows a cross-section according to section lines VI in FIG. 4, which lies in the region of the blade tip 14. Therefore, in the transverse profile 19 according to the cross-section of FIG. 5 the transverse curvature 21 is noticeably larger than in the transverse profile 19 of the cross-section according to FIG. 6. In particular, therefore, a radius of curvature 25 in the transverse profile 19 of FIG. 5 is smaller than in the transverse profile 19 of FIG. 6. The greater the radius of curvature 25, the smaller is the transverse curvature 21.

[0039] In FIGS. 5 and 6, the transverse profile 19 according to the invention is depicted by a filled-in black contour. Compared thereto, a conventional transverse profile 19 is illustrated in FIGS. 5 and 6 by a hatched contour, which has a constant transverse curvature 21 from the blade central region 24 to the blade tip 14 and a constant radius of curvature 25. In the blade central region 24, the curvature 21 according to FIG. 5 in the transverse profile 19 presented here is noticeably more strongly pronounced than in the conventional transverse profile 19. In contrast thereto, according to FIG. 6 in the transverse profile 19 which is presented here, the curvature 21 is more weakly pronounced than in the conventional transverse profile 19.

[0040] Through the reduced transverse curvature 19 in the region of the blade tip 14, the previously mentioned gap flow 22 can be reduced. The reduction of the gap flow 22 increases the stability of the fan wheel 2 in operation. The increase of the transverse curvature 19 in the blade central region 24 compensates for the drop in efficiency of the fan wheel 2, which occurs through the reduced transverse curvature 19 in the region of the blade tips 14.

[0041] According to FIGS. 1 to 4, each blade 8 has a leading edge 26 facing the suction side 15, a trailing edge 27 facing the pressure side 16, and a longitudinal profile 28, which in FIGS. 1 to 4 respectively is indicated in the case of at least one blade 8 by means of a broken line. The longitudinal profile 28 lies here in a longitudinal section plane 29, which is indicated by a broken line in FIG. 4 and which extends parallel to the radial direction 12.

[0042] As can be seen from FIGS. 2 and 3, the blades 8 are equipped here in addition in the longitudinal profile 28 respectively with a longitudinal curvature 30. This longitudinal curvature 30 causes the respective blade back side 18 to be curved convexly toward the suction side 15. For clarification of this convex longitudinal curvature 30 with regard to the suction side, on the blade back side 18, in FIGS. 2 and 3 respectively a comparative straight line 31 is drawn by a broken line, which represents the course of a non-curved, rectilinear blade back side 18 in the respective longitudinal profile 28. In FIG. 2 in addition a contour 32 is indicated with a broken line, which occurs in the region of the blade tip 14 in a conventional blade 8, in which on the one hand in the longitudinal profile 28 no longitudinal curvature 30 is provided, and in which on the other hand the transverse curvature 21 is constant from the blade central region 24 to the blade tip 14.

[0043] Expediently, the blade front side 17 is concavely curved toward the pressure side 16 in the region of the longitudinal curvature 30.

[0044] In the examples shown here, the longitudinal curvature 30 extends only from the blade central region 24 to the blade tip 14. In addition, in the example shown here, provision is made that the longitudinal profile 28 extends in a rectilinear manner from the blade central region 24 to the blade root 13 at least on the blade back side 18. In addition, provision is made here that the longitudinal curvature 30 extends at least in a central region 33 of the transverse profile 19. This central region 33 lies here in the transverse profile 19 between the leading edge 26 and the trailing edge 27. An embodiment is preferred here in which the longitudinal curvature 30 extends only in this central region 33.

[0045] The blade central region 24 extends maximally over 50% of a radially measured blade length, which is indicated in FIG. 2 and is designated by 35, and is arranged in the radial direction 12 centrally between blade root 13 and blade tip 14. Accordingly, an outer region 34, indicated in FIG. 2, begins here at the blade central region 24 and extends up to the blade tip 14, wherein the outer region 34 comprises the blade tip 14. In this outer region 34, the decreasing transverse curvature 21 is contained in the transverse profile 19. In addition, preferably the longitudinal curvature 30 is formed in this outer region 34. This outer region 23 extends over at least 25% of the blade length 35 measured in the radial direction 12. The outer region 34 can occupy maximally 50% of the blade length 35. The blade central region 34 then lies precisely in the centre on 50% of the blade length 35.

[0046] As can be seen in particular from FIG. 3, all the blades 8 are arranged in a freestanding manner, so that they are connected to one another only via the hub 7.