Axial fan with openings in the hub

Abstract

The invention relates to an axial fan (1), having: - a fan hub (2) which is rotatable about a centre axis (3) and has a bottom wall (5) and an annularly circumferential side wall (6), - a plurality of fan blades (7), which protrude from the annularly circumferential side wall (6) of the fan hub (2), - wherein the fan hub (2) has a plurality of outlet openings (8) for letting out gaseous, liquid and / or solid accumulations from the interior (2a) of the fan hub (2) to the outside of the fan hub (2), wherein - the plurality of passage openings (8) are provided on the annularly circumferential side wall (6) of the fan hub (2).

Description

[0001] The invention relates to an axial fan comprising: a fan hub rotatable about a central axis, which has a bottom wall and an annular circumferential side wall, a plurality of fan blades which protrude from the annular circumferential side wall of the fan hub, wherein the fan hub has a plurality of outlet openings for the outlet of gaseous, liquid and / or solid accumulations from the interior of the fan hub to the outside of the fan hub, wherein the plurality of outlet openings are provided on the annular circumferential side wall of the fan hub.

[0002] Such an axial fan is already known from EP 1 718 872 B1. This prior art features a cup-shaped hub with a base and an annular side wall. Ribs are arranged on the inside of the hub. To remove deposits such as water, sand, earth, or mud from the hub cavity, the hub has openings on the base. The openings are located at those corner areas of the hub base formed by the side wall and the internal ribs. During use, the deposits are driven by centrifugal force along the ribs into the corner areas and from there discharged outward through the openings. The side wall and the respective rib form a double barrier, which is intended to facilitate the removal of the deposits.

[0003] CN 205895693 U discloses an axial fan with a hub having an annular sidewall, first and second fan blades attached to an outer side of the sidewall, and an air outlet provided in the sidewall. The hub also has a funnel-shaped insert in which a mounting opening for a motor shaft is formed.

[0004] JP H11 230092 A discloses an axial fan with a cup-shaped hub having an annular sidewall from which fan blades protrude. Outlet openings are provided in the sidewall near a base of the fan blades, particularly near the top and bottom of the fan blades, to discharge air from the hub to the outside.

[0005] JP H04 31697 A discloses an axial fan with first fan blades arranged away from a center and second fan blades arranged near the center. The first fan blades are mounted on a peripheral edge of a frame, within which the second fan blades are mounted and extend radially from the center of the frame to the peripheral edge. Holes are provided on the frame between the respective first fan blades for the passage of fluid supplied by the second fan blades.

[0006] In practice, however, it has been shown that the removal of deposits from the inside of the hub does not always work reliably. Deposits can accumulate in the corners of the hub's interior. Furthermore, centrifugal force is not sufficiently utilized to remove dirt deposits. Furthermore, there is a need for improvement regarding airflow, especially when the axial fan is operated in both directions.

[0007] Further devices are known from EP 2 085 618 A2, EP 0 521 285 and US 2011 / 280729 A1.

[0008] Accordingly, the object of the present invention is to alleviate or eliminate at least some of the disadvantages of the prior art. The invention specifically aims to improve the removal of accumulations from the interior of the fan hub.

[0009] This object is achieved by an axial fan having the features of claim 1. Preferred embodiments are specified in the dependent claims.

[0010] According to the invention, elevations are provided next to the outlet openings, which protrude from the annular circumferential side wall, and the elevations rise towards the outlet openings, wherein the elevations each have a gradient increasing towards the respective outlet opening.

[0011] It has surprisingly been found that accumulations such as moisture or dirt, but also gases, in the interior of the fan hub on the motor side can be removed particularly effectively through the outlet openings in the annular, circumferential side wall. When the axial fan is rotating, the accumulations are pushed outwards by centrifugal force and discharged in the direction of the centrifugal force through the outlet openings on the annular, i.e., particularly cylindrical, side wall. The flow conditions for the removal of accumulations have proven particularly favorable on the side wall. Furthermore, the axial fan can be operated in both directions of rotation with favorable air throughput.

[0012] To improve extraction from the interior of the fan hub, raised portions are provided next to the outlet openings, protruding from the circular side wall. Extensive testing has shown that these raised portions increase the airflow through the outlet openings, thereby improving the removal of debris from the fan hub. Furthermore, the raised portions rise toward the outlet openings, forming ramps. Each raised portion has a gradient that increases toward the respective outlet opening.

[0013] Preferably, the outlet openings are spaced apart from both annular side edges of the side wall, so that the outlet openings are arranged entirely within the side wall of the fan hub. In a preferred embodiment, the bottom wall is free of passage openings for the accumulations from the interior of the fan hub. However, the bottom wall can have a passage for a motor shaft. In the assembled state, the motor shaft is arranged with a substantially precise fit in the passage, which is preferably located in the center of the bottom wall.

[0014] In a preferred embodiment, at least one outlet opening is provided per fan blade on the annular, circumferential side wall of the fan hub. This allows residues to be reliably removed from the interior of the fan hub. The outlet openings are preferably arranged at regular intervals on the side wall of the fan hub, ensuring uniform removal across the circumference of the fan hub.

[0015] To achieve effective extraction of debris from the fan hub, another design features outlet openings directly adjacent to the fan blades. In this configuration, the airflow is guided along the fan blade after passing through the outlet opening, thereby achieving particularly effective removal of debris.

[0016] In another embodiment, it is advantageous to provide one outlet opening on each of the opposite outer sides of the fan blades. Thus, two outlet openings can be provided per fan blade. This design is particularly advantageous in that the fan can be operated effectively in both directions of rotation.

[0017] The outlet openings can be designed as slots.

[0018] If the fan hub has several sector elements that are connected to each other via interlocking connecting elements, the axial fan can be disassembled and reassembled with little effort.

[0019] Strip elements and recesses can be provided as interlocking connecting elements. The strip elements and the recesses have corresponding cross-sections. This creates a positive connection. For example, the strip elements and the recesses can each be designed with a round cross-section.

[0020] In order to create a secure and durable connection, the interlocking connecting elements in a preferred embodiment extend substantially over the entire height of the annular circumferential side wall.

[0021] Depending on the design, at least four, in particular at least six, for example eight, sector elements can be provided. Preferably, each sector element has exactly one fan blade. The sector elements together form the fan hub with a ring-shaped, circumferential side wall. Accordingly, each sector element has an opening angle that is essentially the ratio of 360 degrees to the number of sector elements. With eight sector elements, the opening angle of the sector elements is, for example, 45 degrees.

[0022] To guide the airflow to the outlet openings on the annular side wall of the fan hub, the fan hub, in a preferred embodiment, has ribs on the inside of the bottom wall. Reinforcing ribs can be provided that extend to the inside of the side wall. Furthermore, air guide ribs can be provided between the reinforcing ribs, which preferably end at a distance from the side wall.

[0023] To operate the axial fan, a motor shaft can be connected to the fan hub. The shaft extends through the interior of the fan hub to the bushing located in the center of the base wall. An electric motor, particularly a brushless motor, can be used as the motor.

[0024] Two exemplary embodiments are explained below with reference to the drawings. The second exemplary embodiment is suitable for illustrating the invention. Fig. 1 shows a plan view of an axial fan which is not within the scope of the invention. Fig. 2 shows a diagrammatic view of the axial fan of the Fig. 1 . Fig. 3 shows a view of the axial fan of the Fig. 1, 2 in the dismantled state of individual sector elements of the axial fan. Fig. 4 shows a side view of the axial fan of the Fig. 1 bis 3 . Fig. 5 shows detail A of the Fig. 2 in enlarged view. Fig. 6 shows detail B of the Fig. 4 in enlarged view. Fig. 7 und Fig. 8 show diagrammatic views of a single sector element of the axial fan of the Fig. 1 bis 4 . Fig. 9 shows a rear view of the sector element of the Fig. 7 und 8 . Fig. 10 shows a side view of the sector element of the Fig. 7 bis 9 . Fig. 11 shows detail C of the Fig. 7 in enlarged view. Fig. 12 shows detail D of the Fig. 7 in enlarged view. Fig. 13 shows detail E of the Fig. 8 in enlarged view. Fig. 14 shows detail F of the Fig. 8 in enlarged view. Fig. 15 shows detail G of the Fig. 9 in enlarged view. Fig. 16 shows detail H of the Fig. 9 in enlarged view. Fig. 17 shows a top view of another axial fan. With a slightly different geometry than shown in the illustrations, this axial fan would be an embodiment of the invention. Fig. 18 shows a rear view of the axial fan of the Fig. 17 . Fig. 19 shows a diagrammatic view of the axial fan of the Fig. 17 und Fig. 18 . Fig. 20 shows detail I of the Fig. 20 in enlarged view. Fig. 21 shows a section along the line XXI-XXI in Fig. 17 . Fig. 22 shows detail J of the Fig. 21 in enlarged view. Fig. 23 shows detail K of the Fig. 19 in enlarged view.

[0025] Fig. 1 shows an axial fan 1 with a fan hub 2, which rotates around a central axis 3 (cf. Fig. 4 ) rotates. In the embodiment shown, the axial fan can be effectively operated in both directions of rotation. One direction of rotation is shown by way of example with an arrow. The fan hub 2 has a central passage 4 for a shaft of a motor (not shown). The fan hub 2 has a bottom wall 5 which is circular in plan view and a side wall 6 in the shape of a cylinder jacket. The bottom wall 5 is arranged essentially perpendicular to the central axis 3. The side wall 6 runs axially symmetrically around the central axis 3. The fan hub 2 is therefore cup-shaped, with the bottom wall 5 and the side wall 6 delimiting an interior space 2a. The motor can be arranged at least partially within the interior space 2a. The axial fan 1 also has a plurality of fan blades or fan vanes 7, eight fan vanes 7 in the example shown, which protrude radially outwards from the side wall 6 of the fan hub 2.

[0026] The fan hub 2 has a plurality of outlet openings 8, which are designed to transport gaseous, liquid and / or solid accumulations arising during operation from the interior 2a of the fan hub 2 to the exterior 2b of the fan hub 2. Such accumulations can be, for example, water, dirt or gases, which could impair the operation of the axial fan 1 if they remain in the interior 2a. In the embodiment shown, the passage openings 8 are formed on the annular, circumferential side wall 6, i.e. not on the base wall 5. At least one outlet opening 8 is provided for each fan blade 7. In the embodiment shown, two outlet openings 8 are provided on either side of each fan blade 7. The outlet openings 8 are designed as slots here.Since the outlet openings 8 in the embodiment shown are directly adjacent to the outer sides of the fan blades 7, the air flows are guided along the outer sides of the fan blades 7 after passing through the outlet openings, as indicated in the drawings by flow lines 9.

[0027] In the execution of the Fig. 1 bis 16 The fan hub 2 is composed of several sector elements 10, here, for example, eight sector elements 10. The individual sector elements 10 are connected to one another via interlocking connecting elements 11. The connecting elements 11 can be inserted into one another in the axial direction (i.e., in the direction of the central axis 3). In the embodiment shown, outer connecting elements 11a are provided on the side wall 6, and inner connecting elements 11b are provided on a projection 12, which delimits the passage 4 for the motor shaft.

[0028] In the embodiment shown, strip elements 13 (cf. in particular Fig. 16 ) and recesses 14 (see in particular Fig. 15 ) are provided, which have corresponding cross-sections, in this case round cross-sections, so that the connecting elements can be connected to one another with a substantially precise fit. The connecting elements 11 extend essentially over the entire height of the annular, circumferential side wall 6.

[0029] As is particularly evident from Fig. 2 As can be seen, the fan hub 2 has individual ribs 15 on the inner side 6a of the base wall 6 (facing the interior space 2a). For example, one rib 15 can be provided per fan blade 7. In the illustrated embodiment, therefore, eight ribs 15 are provided in the interior space 2a of the fan hub 2.

[0030] In the Fig. 17 bis 23 A further embodiment of the axial fan 1 is shown. In this embodiment, outlet openings 8 are also provided on the annular side wall 6 of the fan hub 2, whereas the bottom wall 5 is free of such outlet openings. The outlet openings 8 are spaced apart from the fan blades 7. Furthermore, next to the outlet openings, individual elevations 16 (which are separate from the fan blades 7) are provided (cf. in particular Fig. 23 ) which protrude outward from the outside of the annular, circumferential side wall 6. The elevations 23 rise in a ramp-like manner toward the outlet openings 8. In the illustration shown, the elevations 23 each have a substantially constant gradient. However, the gradient can also increase toward the adjacent outlet opening 8 (not shown). The last alternative would make the axial fan an embodiment of the invention.

[0031] As from Fig. 18 und Fig. 19As can be seen, ribs 15 are also provided in this embodiment, with stiffening ribs 15a extending to the side wall 6 on the one hand and air guiding ribs being arranged between them, which end in front of the side wall 6.

Claims

1. Axial fan (1), comprising: - a fan hub (2) rotatable about a center axis (3), which comprises a bottom wall (5) and an annular side wall (6), - a plurality of fan blades (7) projecting from the annular side wall (6) of the fan hub (2), - wherein the fan hub (2) comprises a plurality of outlet openings (8) for the discharge of gaseous, liquid and / or solid accumulations from the interior (2a) of the fan hub (2) to the outside of the fan hub (2), - wherein the plurality of outlet openings (8) are provided on the annular circumferential side wall (6) of the fan hub (2), - wherein elevations (23) are provided next to the outlet openings (8), which elevations project from the annularly encircling side wall (6), and the elevations (23) rise towards the outlet openings (8), characterized in that the elevations (23) each comprise a slope which increases towards the respective outlet opening (8).

2. Axial fan (1) according to claim 1, characterized in that at least one outlet opening (8) per fan blade (7) is provided on the annularly encircling side wall (6) of the fan hub (2).

3. Axial fan (1) according to claim 1 or 2, characterized in that the outlet openings (8) are directly adjacent to the fan blades (7).

4. Axial fan (1) according to one of claims 1 to 3, characterized in that an outlet opening (8) is provided on each of the opposite outside surfaces of the fan blades (7).

5. Axial fan (1) according to one of claims 1 to 4, characterized in that the fan hub (2) comprises a plurality of sector elements (10) which are connected to one another via interlocking connecting elements (11).

6. Axial fan (1) according to claim 5, characterized in that strip elements (13) and recesses (14) are provided as interlocking connecting elements (11).

7. Axial fan (1) according to claims 5 and 6, characterized in that the interlocking connecting elements (11) extend essentially over the entire height of the annularly encircling side wall (6).

8. Axial fan (1) according to one of claims 5 to 7, characterized in that at least four, in particular at least six, for example eight, sector elements (10) are provided.

9. Axial fan (1) according to one of claims 1 to 8, characterized in that the fan hub (2) comprises ribs (15) on the inside of the bottom wall (5).

10. Axial fan (1) according to one of the claims 1 to 9, characterized in that a motor is connected to the fan hub (2).

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