EP2417360B1 - Reinforcing element for use with a ventilator hub - Google Patents

Description

The present invention relates to a fan hub, comprising means for connecting to a fan shaft and a substantially cylindrical mounting portion with radial seats for a number of fan blades, wherein the mounting portion has an inner circumferential surface.

DE2313070 shows a fan hub according to the prior art.

Finally, the invention relates to a method for producing a fan with a fan hub according to one of claims 1 to 7. Fans for subways or tunnels and / or closed vehicle buildings such as underground garages, must be reliable for very long service lives under various load and environmental conditions work. Typically, the installation of fans in subways or tunnels or underground car parks is designed for operation over several years or decades. In particular, when using fans as smoke extraction fans in subways or tunnels, the metro or tunnel operator has requirements for the operability of the ventilator at high temperatures, such as occur especially in cases of fire. The requirements are partly prescribed by law.

On the other hand, there is, as is common practice, the desire to produce fans as low as possible and save material. In general, fans consist of their basic construction of a fan hub to which a number of fan blades is mounted radially. The Attachment of the fan blades is done by means of fasteners such as bolts.

Against the background of the general requirements for fans described above, different fan hubs are known. In order to keep the mass low, fan hubs are known that consist of solid aluminum or an aluminum alloy. A disadvantage of fan hubs made of aluminum, however, is their limited applicability at temperatures above about 300 ° C. Because the tensile strength of aluminum decreases sharply at the temperatures mentioned, so that the aluminum begins to flow gradually. Even special aluminum alloys are not able to significantly improve this inadequacy. As a result of this detrimental nature of aluminum, fan blades may be released from a fan hub made of aluminum at high temperatures, such as may occur in fires.

Due to this inadequacy of fan hubs made of aluminum, fan hubs made of solid steel are used in the prior art for smoke exhaust fans at high loads, ie at high speeds and / or with large blade lengths. However, steel fan hubs have the disadvantage of having a very high mass.

It is therefore an object of the present invention to provide a fan hub of the type mentioned above, which ensures attachment of fan blades with sufficient traction even at high temperatures, as may occur in tunnel fires, without having an undesirably high mass.

Finally, the present invention is based on the object to provide a method for producing a fan with a fan hub according to one of claims 1 to 7.

According to the invention this object is achieved with a fan hub of the type mentioned with the features of claim 1, wherein a substantially separate from the mounting portion, substantially annularly closed reinforcing element is provided with means for tension-resistant attachment of the fan blades. It is therefore within the scope of the invention to add a reinforcing element in the form of an additional component to the fan hub.

Characterized in that according to the invention, the reinforcing element is configured substantially annular, the reinforcing element can absorb radial forces and completely keep away from the Axiallaufradnabe example made of aluminum. In the case of balanced fans, the reinforcing element exerts no force on the fan hub. The hot tensile strength of the unit fan hub and reinforcing element is determined solely by the material of the reinforcing element. Advantageously, a material optimized for the purpose of tensile fastening of the fan blades to the fan hub can be selected in this way. At the same time, independently of this, a material optimized for the actual fan hub can be selected. In particular, the reinforcing element can be advantageously selected from a material with high hot tensile strength and good creep behavior at high temperatures. According to the invention for the fan hub a particular lighter material without affecting the overall hot tensile strength of the fan.

In an advantageous embodiment of the invention it is provided that the reinforcing element has at least two segments which can be welded together. The production of a fan hub, which is provided with a reinforcing element according to the invention, is particularly simple due to this measure. In particular, it is possible to retrofit an axial impeller hub of conventional type with a reinforcing element according to the invention in order to improve the hot tensile strength.

In a further advantageous embodiment of the invention, it is provided that the number of segments corresponds to half the number of fan blades to be accommodated. For example, in a four-wheel, so a fan with a total of four fan blades, two segments may be provided. In a six-wheel impeller, three segments may be provided. With an eighth wheel, four segments can accordingly be provided.

The attachment of the reinforcing element to a fan hub is further improved if, in an embodiment of the invention, the reinforcing element has at least one substantially planar section, the surface normal of which can be oriented in the radial direction of a fan hub when used as intended.

In a preferred embodiment of the reinforcing element, the number of planar sections corresponds to twice the number of fan blades to be accommodated. Thus, according to this embodiment of the invention in a four-wheel eight-plane sections exist. Due to the generally to be demanded symmetry of the rotating structures results in a cross-sectional area of the substantially annular reinforcing element corresponding to an n-corner. Correspondingly, a six-wheel would have twelve planar sections, a six-way eight-way wheel and a twelve-wheel impeller twenty-four planar sections.

The
Reinforcement element is essentially made of steel. The hot tensile strength and the creep behavior of steel are also excellent at temperatures above 300 ° C, for example. In particular, the hot tensile strength at the temperatures mentioned is much better than that of aluminum.

The object underlying the invention is achieved by a fan hub according to claim 1 having means for connection to a fan shaft and / or a hub core and a substantially cylindrical mounting portion with radial receptacles for a number of fan blades, wherein the mounting portion has an inner circumferential surface, which with one of the fastening portion substantially separately configured, substantially annularly closed reinforcing element is provided with means for tensile fastening of the fan blades. The substantially annular attachment portion can be made with advantage of a material with higher tensile strength than the fan hub, moreover. The attachment portion may for example have the shape of a bent steel belt. The means for tensile fastening of the fan blades can be holes with or without thread in the simplest case.

The fan hub according to the invention is further improved if the reinforcing element is arranged substantially along the inner circumferential surface of the fastening section. The interior of the fan hub is usually free of superstructures. Therefore, according to the invention can be retrofitted with advantage according to the invention, a reinforcing element, such as in the form of a bent steel belt without constructive adjustments of the impeller hub are required. In addition, in the event of unbalance of the fan, the cylindrical mounting portion of the hub may need to receive additional radial forces to hold the reinforcing member in position.

A particularly strong grip between the reinforcing element and the fan hub, which is also suitable for absorbing axial forces, results in a further development of the fan hub according to the invention if the inner lateral surface has a substantially planar area in an area around at least one radial receptacle whose surface normal is essentially in the radial direction the fan hub is oriented. The flat areas can be made for example by milling.

It is particularly favorable that according to the invention, the fan hub is made essentially of aluminum. For weight reasons, aluminum is the preferred material for an axial impeller hub. According to the invention, a fan hub made of aluminum, despite the unfavorable properties of aluminum in terms of hot tensile strength in conjunction with a reinforcing element according to the invention have the required hot tensile strength. Because the reinforcing element is simultaneously made according to the invention of steel.

In particular, in an advantageous embodiment, the fan hub according to the invention according to one of claims 2 to
7 designed.

1. a. zunächst jedes Segment des Verstärkungselements der Innenmantelfläche des Befestigungsabschnitts der Ventilatornabe derart angenähert wird, dass die Mittel zur zugfesten Befestigung mit den radialen Aufnahmen des zylindrischen Befestigungsabschnitts in radialer und axialer Richtung in Deckung gelangen;
2. b. anschließend Gewindebolzen der zu befestigenden Ventilatorschaufeln in die radiale Aufnahme des zylindrischen Befestigungsabschnitts sowie in die Mittel zur zugfesten Befestigung eingeführt werden;
3. c. anschließend jedes Segment des Verstärkungselements mit dem zylindrischen Befestigungsabschnitt der Ventilatornabe mittels des Gewindebolzens der jeweiligen zu befestigenden Ventilatorschaufel verschraubt wird;
4. d. schließlich die mit dem zylindrischen Befestigungsabschnitt der Ventilatornabe verschraubten Segmente des Verstärkungselements miteinander zur Bildung eines zusammenhängenden im wesentlichen ringförmig geschlossenen Verstärkungselements verschweißt werden.

The method task underlying the present invention is achieved by a method for manufacturing a fan with a fan hub according to one of claims 4 or 5, in which

1. a. First, each segment of the reinforcing element of the inner circumferential surface of the fastening portion of the fan hub is approximated such that the means for tensile fastening with the radial receptacles of the cylindrical mounting portion in the radial and axial direction coincide;
2. b. then threaded bolts of the fan blades to be fastened are introduced into the radial receptacle of the cylindrical mounting portion and in the means for tension-resistant attachment;
3. c. then, each segment of the reinforcing member is screwed to the cylindrical attachment portion of the fan hub by means of the threaded bolt of the respective fan blade to be fastened;
4. d. finally, the segments of the reinforcing element screwed to the cylindrical attachment portion of the fan hub are welded together to form a continuous substantially annularly closed reinforcing element.

The inventive method allows retrofitting of conventional, made of aluminum Axiallaufradnaben or other hubs for fans with a reinforcing element according to the invention. Because the ring shape of the steel element only by welding of individual segments of the Reinforcement element is carried out after attachment of the individual segments with the hub, eliminating a possibly problematic fitting a one-piece reinforcing element, in which, for example, a fan hub made of aluminum could be damaged by scratches. In addition, by the manufacturing method according to the invention with reinforcing element consisting of individual segments, an optimum fitting of the reinforcing element to the inner lateral surface of the fan hub can be achieved.

The invention will be described by way of example in a preferred embodiment with reference to a drawing, wherein further advantageous details are shown in the figures of the drawing.

Functionally identical parts are provided with the same reference numerals.

Figur 1

Eine aus Aluminium gefertigte Axiallaufradnabe als Bestandteil einer Ausführungsform der Erfindung;

Figur 2

• a) Radialschnitt durch einen Stahlverstärkungsgurt und
• (b) einen Radialschnitt durch die Axiallaufradnabe gemäß Figur 1, ergänzbar durch den Verstärkungsgurt

gemäß Teil (a), wobei der Schnitt entlang der Linie II-II in Figur 1 verläuft;

Figur 3

eine axiale Draufsicht auf verschiedene Ausgestaltungen des Verstärkungselements gemäß Figur 2 (a) in schematischer Darstellung.

The figures of the drawing show in detail:

FIG. 1

An axial impeller hub made of aluminum as part of an embodiment of the invention;

FIG. 2

• a) radial section through a Stahlverstärkungsgurt and
• (B) a radial section through the Axiallaufradnabe according to FIG. 1 , supplemented by the reinforcing strap

according to part (a), wherein the section along the line II-II in FIG. 1 runs;

FIG. 3

an axial plan view of various embodiments of the reinforcing element according to FIG. 2 (a) in a schematic representation.

The FIG. 1 shows a perspective view of a Axiallaufradnabe 1. The Axiallaufradnabe 1 substantially corresponds to that of a hub according to the prior art. It has a central bore 2 for connecting, optionally via a hub core, not shown, with a fan shaft, not shown. Around the central bore 2 around arranged on a circular line mounting holes 3 for producing a flange with the hub core, not shown, for attachment to a fan shaft, not shown, are present.

The Axiallaufradnabe 1 also has a cylindrical mounting portion 4. The mounting portion 4 has an inner circumferential surface 5. In the cylindrical mounting portion 4 radial mounting holes 6 are at equal angular intervals to each other. In the schematic representation according to FIG. 1 not all mounting holes 6 are shown, which are actually needed for the power-free operation of a fan.

The receiving holes 6 are used to receive fan blades, not shown, by means of blade bolts, which are attached to the ends of the fan blades. In the prior art, the attachment of fan blades by inserting the blade bolts in the radial mounting holes 6 in the cylindrical mounting section 4 of the Axiallaufradnabe 1 and then screwing the threaded shovel bolt takes place based on an attached to the inner surface 5 shell nut. At the cylindrical mounting portion 4 with the radial mounting holes 6, a conically tapered skirt portion 11 connects. If the Axiallaufradnabe 1 is made of aluminum, this arrangement, however, at temperatures such as can occur in tunnel fires, ie at 300 ° C to 400 ° C, insufficient tensile strength.

Based on FIG. 2 illustrates how in the invention with an axial impeller hub 1, the problem of insufficient hot tensile strength of an axial impeller hub 1 made of aluminum is solved. Part (a) of the FIG. 2 shows in a radial section corresponding to the cutting direction according to II - II FIG. 1 a reinforcing element in the form of a reinforcing belt 7.

The reinforcing belt 7 is at bend lines 8 each by the same angle α (see FIG. 3 ) bent. In perspective according to FIG. 2 (a) is to understand the bend out of the plane of the drawing. Between the bending lines 8, the reinforcing belt 7 extends in the form of a flat, unbent portion 9, respectively. The non-bent portions 9 each have the same length and width according to this embodiment. Each third planar section 9 is provided with a bore 10. According to another embodiment of the invention, which is based on FIG. 3 (a ') is described below, longer portions 9 are arranged adjacent to respective shorter portions 9'.

In FIG. 2 (a) It can also be seen that the reinforcing belt 7 consists of the segments 7a, 7b. The segments 7a, 7b are interconnected along the welding nad 12. The Schweißnad 12 is also a bending line in the sense of bending lines. 8

The FIG. 2 (b) shows in the same section perspective as part (a) of FIG. 2 a Axiallaufradnabe 1, which substantially like the in FIG. 1 Perspective Axiallaufradnabe 1 is constructed. In FIG. 2 (b) However, beyond the special design of the inner circumferential surface 5 can be seen. In the inner circumferential surface 5, planar surfaces 13 which are aligned with one another in the axial direction are arranged. The planar surfaces 13 have approximately the same dimensions as the planar sections 9 of the reinforcing belt 7 in a direction perpendicular to the axial direction.

In FIG. 3 various embodiments of the invention reinforcing belt 7 are shown in axial side view. It shows the FIG. 3 (a) a reinforcing belt 7 for use in a Axiallaufradnabe 1 for a four-wheel, so an impeller with a total of four fan blades. The reinforcing belt 7 is composed of two segments 7a, 7b. The segments 7a, 7b are connected or connectable along the welding seams 12.

FIG. 3 (a ') shows an alternative embodiment of the reinforcing belt according to FIG. 3 (a) ,

In accordance with the reinforcing belt according to FIG. 3 (a) is the in FIG. 3 (A ') illustrated reinforcing belt for use in a Axialradlaufradnabe 1 for an impeller provided with a total of four fan blades. Notwithstanding the embodiment according to FIG. 3 (a) However, the non-bent portions 9 in pairs have different lengths in the radial direction. Like in the FIG. 3 (a '), adjacent non-bent portions 9 and 9' have different lengths in the radial direction. However, radially opposite sections 9, 9 'each have the same radial length. In this design, the longer sections 9 do not touch the fan hub.

In FIG. 3 (b) an embodiment of the reinforcing belt 7 is shown for a six-wheel. The reinforcing belt 7 according to FIG. 3 (b) consists of three segments, which are connected or connectable to the welds 12.

FIG. 3 (c) shows an embodiment of the reinforcing belt 7 for an eight-wheel, which consists of four segments 7a, 7b, 7c, 7d. Finally shows FIG. 3 (d) an embodiment of the reinforcing belt 7, which is for a twelve-wheel is suitable and also composed of four segments. The structure of the execution according to FIGS. 3 (c) and (d) otherwise corresponds to the embodiments according to the figures (a) and (b).

To a Axiallaufradnabe according to FIG. 1 or FIG. 2 (b) According to the invention to be provided with a reinforcing belt 7, first each segment 7a, 7b, ..., screwed to the inner circumferential surface 5 of the Axiallaufradnabe 1. For this purpose, the blade bolt of the fan blades to be fastened is inserted through the radial receiving bore 6 into the cylindrical attachment section 4 of the axial-wheel hub 1 and then through the hole 10 brought into coincidence with the receiving bore 6 in the reinforcing belt 7. The flat sections 9 of the reinforcing belt 7 engage in the cutouts 13 in the inner circumferential surface 5 of the fastening section 4 of the hub 1.

The unit of the segment of the reinforcing belt 7 and the Axiallaufradnabe 1 is then bolted by a locknut in the usual way. After each of the segments 7a, 7b,... Of the reinforcing belt 7 has been screwed to the inner circumferential surface 5 of the cylindrical mounting portion 4 of the axial impeller hub 1 in the manner described, the individual segments 7a, 7b of the reinforcing belt 7 will be welded together along the welds 12 in the interior the
Axial wheel hub 1 welded.

In this way one obtains according to the invention a Axiallaufradnabe 1, which on the one hand is light and on the other hand, at high temperatures, such as may occur in fires in subways or tunnels, has sufficient tensile strength. This is achieved by according to the invention the reinforcing belt made of steel, in particular a structural steel, such as S235JR, manufactures and the axial hub 1 made of aluminum or an aluminum alloy.

LIST OF REFERENCE NUMBERS

1

Axiallaufradnabe

2

drilling

3

mounting hole

4

cylindrical attachment section

5

Inner surface area

6

radial receiving bore

7

Reinforcing element, reinforcing strap

7a

segment

7b

segment

8th

elastic line

9

level section

10

drilling

11

conically tapered shell section

12

Weld

13

plane surface

α

bending angle

Claims (8)

1. Fan hub (1) for a smoke extraction fan, comprising means (2, 3) for connection to a fan shaft and/or a hub core, and a substantially cylindrical fastening portion (4) comprising radial receptacles (6) for a number of fan blades, the fastening portion (4) comprising an inside lateral surface (5), characterised in that it is provided with a substantially annularly closed reinforcement element (7) that is designed so as to be substantially separate from the fastening portion (4) and comprises means (10) for tension-proof fastening of the fan blades, the reinforcement element (7) being produced substantially from steel, and the fan hub (1) being produced substantially of aluminium.
2. Fan hub (1) according to claim 1, characterised in that the reinforcement element (7) is arranged substantially along the inside lateral surface (5) of the fastening portion (4).
3. Fan hub (1) according to either claim 1 or claim 2, characterised in that the inside lateral surface (5) comprises a substantially planar region (13), in a region around at least one radial receptacle (6), the surface normal of which substantially planar region is oriented substantially in the radial direction of the fan hub (1).
4. Fan hub according to any of claims 1 to 3, characterised in that the reinforcement element (7) comprises at least two segments (7a, 7b) that can be welded together.
5. Fan hub according to claim 4, characterised in that the number of segments (7a, 7b) corresponds to half the number of fan blades to be received.
6. Fan hub according to any of the preceding claims, characterised in that the reinforcement element comprises at least one substantially planar portion (9), the surface normal of which can be oriented in the radial direction of a fan hub (1), when used as intended.
7. Fan hub according to claim 6, characterised in that the number of planar portions (9) corresponds to twice the number of fan blades to be received.
8. Method for producing a fan comprising a fan hub (1) according to either claim 4 or claim 5, characterised in that

   a. firstly, each segment (7a, 7b) of the reinforcement element (7) is moved closer to the inside lateral surface of the fastening portion (4) of the fan hub (1), such that the means for tension-proof fastening coincide with the radial receptacles (6) of the cylindrical fastening portion (4), in the radial and axial direction;

   b. subsequently, threaded bolts of the fan blades to be fastened are introduced into the radial receptacle (6) of the cylindrical fastening portion (4) and into the means (10) for tension-proof fastening;

   c. subsequently, each segment (7a, 7b) of the reinforcement element (7) is bolted to the cylindrical fastening portion (4) of the fan hub (1) by means of the threaded bolt of the particular fan blade that is to be fastened:

   d. finally, the segments (7a, 7b) of the reinforcement element that are bolted to the cylindrical fastening portion (4) of the fan hub (1) are welded together in order to form a continuous, substantially annularly closed, reinforcement element (7).

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