The present application is a U.S. National Phase of International Application No. PCT/AT2021/060051 entitled “AXIAL FAN WITH OPENINGS IN THE HUB,” and filed on Feb. 11, 2021. International Application No. PCT/AT2021/060051 claims priority to Austrian Patent Application No. GM 50025/2020 filed on Feb. 11, 2020. The entire contents of each of the above-listed applications are hereby incorporated by reference for all purposes.
The invention relates to an axial fan, comprising:
a fan hub which is rotatable about a center axis and comprises a bottom wall and an annularly circumferential side wall,
a plurality of fan blades, which protrude from the annularly circumferential side wall of the fan hub,
wherein the fan hub comprises a plurality of outlet openings for letting out gaseous, liquid and/or solid accumulations from the interior of the fan hub to the outside of the fan hub.
Such an axial fan is already known from EP 1718 872 B1. In this prior art, a cup-shaped hub with a bottom and an annular side wall is provided. Ribs are arranged on the inside of the hub. In order to remove deposits such as water, sand, soil or sludge from the cavity of the hub, the hub comprises passage openings at the bottom. The passage openings are located at those corner areas of the hub bottom which are formed by the side wall and the internal ribs. In use, the centrifugal force drives the deposits along the ribs into the corner areas and from there they are discharged to the outside through the passage openings. Hereby, the side wall and the respective rib form a double barrier which is intended to facilitate the removal of the deposits.
In practice, however, it has been shown that the removal of deposits from the inside of the hub does not always function reliably. Deposits can accumulate at the corners inside the hub. Furthermore, the centrifugal force for the removal of the dirt deposits is insufficiently utilized. Furthermore, there is a need for improvement with regard to the air throughput, especially if the axial fan is operated in both directions of rotation.
Further devices are known from EP 2 085 618 A2, EP 0 521 285 and US 2011/280729 A1.
Accordingly, the object of the present invention is to alleviate or eliminate at least some of the disadvantages of the prior art. In particular, the invention sets itself the goal of improving the removal of accumulations from the interior of the fan hub.
According to the invention, the plurality of outlet openings are provided on the annularly circumferential side wall of the fan hub.
Surprisingly, it has been found that the accumulations, such as moisture or dirt, but also gases, in the interior of the fan hub on the side of the motor can be removed particularly well through the outlet openings in the annularly circumferential side wall. In the rotating state of the axial fan, the accumulations are conveyed outward by the centrifugal force and discharged in the direction of the centrifugal force through the outlet openings in the annularly circumferential, i.e. in particular cylinder-jacket-shaped, side wall. The flow conditions for the removal of the accumulations have proven to be particularly favorable at the side wall. Furthermore, operation of the axial fan in both directions of rotation can be achieved with favorable air throughput.
Preferably, the outlet openings are spaced apart from both annular side edges of the side wall so that the outlet openings are located entirely within the side wall of the fan hub. In a preferred embodiment, the bottom wall is free of passage openings for the accumulations coming from the interior of the fan hub. However, the bottom wall can include a lead-through for a motor shaft. In the assembled state, the motor shaft is arranged in a substantially precisely fitting manner in the lead-through, which is preferably located in the center of the bottom wall.
In a preferred embodiment, at least one outlet opening is provided on the annular side wall of the fan hub for each fan blade. In this way, residues can be reliably removed from the interior of the fan hub. Preferably, the outlet openings are arranged at regular intervals on the side wall of the fan hub so that uniform removal over the circumference of the fan hub is achieved.
In order to achieve effective extraction of the accumulations from the fan hub the outlet openings are, in a further embodiment, directly adjacent to the fan blades. In this embodiment, the air flow is guided along the fan blade after passing through the outlet opening, thus achieving particularly effective removal of the accumulations.
In a further embodiment, it is favorable if one outlet opening is provided on each of the opposite outer sides of the fan blades. Thus, two outlet openings can be provided per fan blade. This embodiment is particularly favorable in that the fan can be operated effectively in both directions of rotation.
The outlet openings can be implemented as slots.
To further improve extraction from the interior of the fan hub, elevations which protrude from the annular side wall can be provided next to the outlet openings. Comprehensive investigations have shown that these elevations increase the airflow through the outlet openings, thereby improving the removal of accumulations from the fan hub.
In one embodiment variant, the elevations rise toward the outlet openings so that the elevations are in the form of ramps.
Depending on the embodiment, the elevations can each comprise a substantially constant slope or a slope that increases toward the respective outlet opening.
If the fan hub has a plurality of sector elements which are connected to one another via interlocking connecting elements, the axial fan can be disassembled and reassembled with little effort.
Strip elements and recesses can be provided as interlocking connecting elements. The strip elements and the recesses have corresponding cross sections. A positive-locking connection is thus achieved. For example, the strip elements and the recesses can each be formed to have a round cross section.
In order to establish a secure and durable connection, in a preferred embodiment, the interlocking connecting elements extend substantially over the entire height of the annular side wall.
Depending on the embodiment, at least four, in particular at least six, for example eight, sector elements can be provided. Preferably, each sector element comprises exactly one fan blade. The sector elements together form the fan hub with the annularly circumferential side wall. Accordingly, each sector element has an opening angle which corresponds substantially to the ratio of 360 degrees and the number of sector elements. For example, with eight sector elements, the opening angle of the sector elements is 45 degrees.
In order to guide the air flows to the outlet openings on the annular side wall of the fan hub, the fan hub, in a preferred embodiment, comprises ribs on the inside of the bottom wall. Stiffening ribs which extend to the inside of the side wall can be provided. Furthermore, air guide ribs can be provided between the stiffening ribs, which preferably end at a distance from the side wall.
For operation of the axial fan, a shaft of a motor can be connected to the fan hub. The shaft extends through the interior of the fan hub to the lead-through which is arranged in the center of the bottom wall. The motor can be an electric motor, in particular a “brushless” motor.
The invention is further explained below with reference to two exemplary embodiments, which are illustrated in the drawings.
The fan hub 2 has a plurality of outlet openings 8 which are arranged to transport gaseous, liquid and/or solid accumulations produced during operation from the interior 2a of the fan hub 2 to the outside 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 annularly circumferential side wall 6, thus not on the bottom 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 both sides of each fan blade 7. The outlet openings 8 are formed here as slots. 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.
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Number | Date | Country | Kind |
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GM 50025/2020 | Feb 2020 | AT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/AT2021/060051 | 2/11/2021 | WO |
Publishing Document | Publishing Date | Country | Kind |
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WO2021/159161 | 8/19/2021 | WO | A |
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Number | Date | Country | |
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20230104569 A1 | Apr 2023 | US |