EP3106673A1 - Fan with at least one fan wheel and/or further fan parts and method for producing a fan part of a fan - Google Patents

Abstract

The fan has a fan with fan blades (2), which are connected to at least one ring (1). The fan wheel, the fan blade (2) and / or another fan part (1, 2, 3) have at least one load-critical area, which is reinforced with at least one reinforcing element (5, 6). It is a coil which can be unwound from a coil and consists of a thermoplastic matrix which encloses unidirectional, quasi-continuous fibers running parallel to the length of the reinforcing strip (5, 6). The reinforcing element (5, 6) is inserted and positioned in an injection mold. Subsequently, plastic is injected, which surrounds the reinforcing element (5, 6) partially or completely. An injection-molding blank may also be prefabricated and at least one reinforcing strip (5, 6) attached to it. Subsequently, the injection molding blank is overmolded with further thermoplastic material in such a way that the reinforcing strip (5, 6) is partially or completely enclosed.

Description

The invention relates to a fan according to the preamble of claim 1 and a method for producing a fan part of a fan according to the preamble of claim 11 and 14 respectively.

The load capacity of injection molded plastic parts is limited. For fans in which such parts are in use, this leads in particular to a limit speed above which the fan can no longer be operated. In the case of injection-molded plastic parts, so-called tie-in seams frequently represent weak points. A flat area within an injection-molded part is designated as a tie-line, which results from the fact that two separate partial flows of the liquid plastic flow together in the mold cavity during the injection molding process. Since the temperature of these partial flows is usually too low, an optimal fusion of the partial flows is no longer possible, whereby the weld line is formed. In the liquid plastic contained reinforcing fibers are usually aligned along the weld line, that is, they do not bridge the weld line and therefore do not reinforce. Tie lines occur in particular when the injection-molded part has a not simply contiguous component volume, for example as a result of holes or more fan blades, which are integrally connected to a hub and a cover ring. In addition, weld lines can also occur when plastic is injected at an injection molding in several places. Nevertheless, to achieve a high load capacity in injection-molded plastic parts with weld lines, different precautions met. For example, more material is used, especially in the weld line region or high-strength materials, which, however, drives up the manufacturing costs and / or the weight of the fan part, which means that fans can no longer be produced economically. With fans, it is also customary to manufacture particularly loaded fan parts made of metal. This also leads to additional costs and / or extra weight in the production of the fan.

Blow molded parts made of injection molded plastic also have strength-critical areas in addition to weld lines. For example, transition points within a component, for example, from fan blades to rings, such as hub ring or cover ring, are often critical to strength. Furthermore, connection areas, such as, for example, holes for screws, bushes or other inserts or receptacles for shafts or the like, may be strength-critical points. Often fan parts with such strength-critical areas are not feasible in plastic injection molding, or only with the use of expensive, high-strength injection molding or large wall thicknesses.

Often, fan parts, in particular fan wheels, fan blades, suspensions or adapter hubs, are also critical to deformation, i. a permissible for the proper operation of a fan deformation is so low that a fan part is not feasible in plastic injection molding, or only by the use of very expensive injection molding or very large wall thicknesses.

The invention has the object of providing the generic fan and the generic method in such a way that the fan can be made with high resilience in terms of component failure and allowable component deformation easy, low component weight and cost.

This object is achieved according to the invention in the generic fan with the characterizing features of claim 1 and in the generic method according to the invention with the characterizing features of claims 11 and 14, respectively.

In the fan according to the invention reinforcing elements are used in the stress-critical or deformation-critical areas, which are developable from a coil, quasi-endless fiber reinforced tapes. The reinforcing tapes can be easily unwound from the bobbin and cut to the required length. This allows a simple, flexible and economical way of manufacturing. The reinforcing bands are partially or completely embedded in the thermoplastic material, from which a fan, a fan blade or another fan part is made. One or more fan parts of the fan according to the invention can thus be manufactured inexpensively by injection molding. The reinforcing straps substantially increase the load capacity of at least one fan member, whereby the limit speed at which the fan can be operated can also be greatly increased, or whereby wall thickness and thus material usage and weight can be saved in the design of the fan member, or whereby a fan portion can be realized in plastic injection is only possible. The high load capacity of a fan has the advantage that for a required amount of air small, compact fans can be used, which can be operated with correspondingly higher speeds. The thermoplastic material is preferably a fiber-reinforced plastic, in which the reinforcing bands are additionally introduced. The reinforcing bands can be specifically introduced with regard to the position and the direction of action in a fan, a fan blades or in other fan parts. The reinforcing straps may be positioned and aligned to accommodate the major stresses of the corresponding fan member or to avoid or at least reduce deformation in critical directions.

In an advantageous embodiment, the reinforcing band surrounds an inflow opening of a fan wheel in an annular manner at a distance. The reinforcing band ensures that the critical edge region of this inflow opening is sufficiently reinforced.

In an advantageous embodiment, at least one reinforcing strip extends transversely to at least one weld line of a fan part. Binding seams form stress-critical areas of a fan part, which are advantageously reinforced by transverse reinforcing bands. A reinforcing strip advantageously crosses weld lines, which may be located, for example, on the hub ring and / or cover ring of a fan wheel or on an adapter hub or a hub body.

Depending on the design of the stress-critical areas, a plurality of reinforcing tapes can be provided above and / or next to each other in the fan part. As a result, an optimal positioning and thus reinforcement of the fan part in the region of its load-critical areas and / or its deformation-critical areas is easily possible.

Another stress critical area of a fan is in a fan the transition of the fan blades to at least one integrally made with the fan blades ring, such as a hub ring or a cover ring. Therefore, it is advantageously possible to provide at least one reinforcement band in the region of this transition in such a way that it crosses the transition. With the reinforcement band, a fan wheel can be optimally reinforced in this critical area.

In fan wheels, the fan wheels, fan blades or other fan parts are often critical to deformation, ie their deformation, for example, their deflection in operation often reaches critical values for the operation. This is especially the case when fan blades, as often provided, have thin trailing edges, which are low in size Noise development be sought. Therefore, if in a preferred embodiment, the reinforcing tape is positioned in the region of the front and / or trailing edge of the fan blades, the fan blades can keep the advantage of acoustic reasons thin trailing edge or running with thin leading edges, without the use of the impeller to large deflections or Deformations for the fan blades to achieve. This training also leads to a considerable saving of material in the manufacture of a fan wheel.

The reinforcing band may extend along the leading and / or trailing edges of the fan blades in the fan blade, the extension length being selected so that the fan blades are optimally reinforced in their critical edge region. The reinforcing tape can therefore extend over the entire length in the spanwise direction, but also only over a partial length of a fan blade.

In a particularly advantageous embodiment, within the fan blade, ie in the region between the front and the rear edge, a plurality of reinforcing ribbons over the width thereof, which extends from the front edge to the rear edge, distributed. This makes it possible to provide the fan blades with a very strong sickle shape. Without the use of the reinforcing bands there is the risk of strongly sickened fan blades, as they are used in particular for axial fan, that they deform heavily in use and on the wall surrounding the fan wheel ring. Through the use of the reinforcing bands, even with a thin wall thickness of the fan blade and high speeds, a very strong sickling of the fan blade can be used without an undue deformation of the fan blade is to be feared. Since the sickle shape is sought in terms of optimum acoustic values, the use of the reinforcing bands, the desired high noise level of the fan can be achieved in a very simple and cost-effective manner.

A fan can be made in one piece as injection molded part. But there are also fan wheels possible, which are composed of individual wings, which each consist of one piece of fan blades and connecting element, which are connected to a hub ring. In this case, the fan blades are each provided with a connection element, preferably designed as a wing base, with which the fan blades are held on the hub ring. Wing feet are advantageously dome-shaped, so that there is the possibility of turning the individual wings at least during assembly relative to the hub so that optimum angle of attack of the fan blades can be adjusted.

In order for the individual wing to ensure a high load capacity in the region of the connection element, reinforcing strips are advantageously accommodated in the connection element in such a way that they extend over the transition region from the connection element into the fan blade. The critical transition region between the connection element and the fan blade is thus optimally reinforced.

If the fan wheel has a hub ring, then advantageously at least one reinforcing band runs helically in the hub ring over the circumference of the hub ring. The hub ring is a heavily loaded component because it must ensure power transmission from the fan blades to the engine. In some cases, a hub ring is pressed onto a shaft or other receptacles, resulting in significant stresses. By using an over the circumference extending reinforcing tape these voltages are absorbed so that an impairment of the function of the fan wheel is avoided. The reinforcing band can be easily arranged in the injection mold. A helical shape ensures in a simple manner over the entire circumference of the hub ring a high load capacity. Since the reinforcing tape is unwound from the spool, different sized hub rings can be easily provided with the helically extending reinforcing tape. It is also advantageous to arrange a plurality of layers of reinforcing bands in each case helically such that the bands intersect. As a result, for example, a high torsional stiffness or bending stiffness of a hub ring can be achieved, depending on the choice of the pitch angle of the helical course.

Preferably, the helical reinforcing band extends over the entire height of the hub ring.

In an advantageous embodiment with individual wings of the hub ring consists of at least two mutually clamped hub bodies, of which at least one is approximately annular. Such hub bodies are used in particular when individual wings with their connecting element designed as a wing foot are to be fastened to the hub ring. For this purpose, at least one hub body is provided with depressions on the front side facing a further hub body, into which the wing base engages in the mounted state.

In order for the hub ring or the hub body to have a sufficiently high stability, at least one reinforcing band is advantageously provided near the end face of the approximately annular hub body, which advantageously extends over the circumference of the hub body. This allows the hub body with the interposition of the wing feet of the individual wings are firmly clamped against each other. For example, if the hub is pressed onto a shaft and very high stresses occur, these can be absorbed by the use of the reinforcing straps, although the hub or hub bodies are made of injection-molded plastic. The high operating forces that must be introduced via the wing feet in the hub ring and absorbed by the hub ring can also be absorbed by the use of the reinforcing bands. The use of metallic hubs is therefore no longer necessary.

The reinforcing ribbons are in this case advantageously provided in the hub bodies such that they also run underneath the indentations in the end face of the hub body, in which the winged feet of the individual wings engage in the assembled state.

Frequently fan wheels, especially in the area of the hub ring, mounting holes for the passage of mounting screws, with which the fan can be attached to a motor or an adapter. In the field of mounting holes, injection-molded joints often form weld lines whose adverse effects are eliminated or significantly reduced by the reinforcing bands. In this case, each attachment opening is advantageously surrounded by at least one reinforcement band. The use of the reinforcing tape allows to press bushes and the like into the mounting holes. The resulting clamping forces are absorbed by the reinforcing strip.

In a method according to the invention, a fan wheel, a fan blade or another fan part is produced in one piece by injection molding by means of thermoplastic material. For this purpose, the reinforcing tape is inserted and positioned in the injection mold. It is previously unwound from a spool and cut to the correct length. A special pre-shaping or a special blank of the reinforcing tape is not required. In particular, no preforming tools are necessary. There is no waste, as is often unavoidable when using flat semi-finished products based on fiber fabrics. The reinforcing tape is positioned and held in the injection molding tool via appropriate devices. For example, a reinforcing band can be fixed with special pins in the tool. Subsequently, the thermoplastic material is injected into the injection mold, which partially or completely surrounds the prepositioned reinforcing tape. Shortly before the end of the injection process, the pins can by means of hydraulic or the pneumatics are withdrawn, so that the cavities created by the pins themselves fill with plastic material.

A particularly advantageous method of positioning the reinforcing tapes is to glue them with a special adhesive to the tool surface in the cavity of the injection molding tool. For example, a thermal adhesive can be used, with which the tapes are already coated on one side of the coil and unfolds its adhesive effect only at a certain temperature, as given on the injection mold. In this method, the reinforcing tapes appear visible on the component surface of a finished fan part, so are not completely embedded in surrounding plastic.

In another procedure, a Spritzgiessrohling is prefabricated and secured to him or the reinforcing bands, for example by gluing or welding. Subsequently, the injection molding blank is encapsulated with the further thermoplastic to the finished injection molding so that the / the reinforcing bands is completely enclosed (are).

Depending on the design of the fan part, the corresponding reinforcing bands can be positioned in the injection molding tool or on the incomplete injection molding blank at several positions. The reinforcing straps are designed to absorb the major loads or to prevent deformation in critical directions. Also, the manufacturing-related vulnerabilities, such as the aforementioned weld lines are reinforced by a corresponding arrangement of the reinforcing bands. Unnecessary use of relatively heavy, expensive and energetically expensive to produce fibers with an orientation in which no fiber reinforcement is necessary, can be specifically avoided.

In order to determine the correct position and orientation of the reinforcing bands in the injection molding tool, it is advantageous to position the reinforcing bands determined in the injection mold by mold filling simulation and / or stress-strain simulation. With stress-strain simulations, expected stresses and deformations can be predicted using a computer program. With mold filling simulations, production-specific properties, such as fiber orientation and weld lines, can also be predicted using a computer program. Computer programs for stress-strain simulations or mold-filling simulations are known and available on the market.

It is also possible to experimentally determine critical areas where reinforcement with reinforcing ribbons is necessary. This can be done for example by analyzing the fracture behavior of unreinforced or insufficiently reinforced components. A great advantage of the method described here is that it is comparatively easy to provide otherwise otherwise identical fan parts with additional reinforcing bands, if one identifies insufficient reinforcement in an already existing fan part. There are no changes or adjustments of injection molds, semi-finished products, stamping tools or Preformwerkzeugen needed.

The subject of the application results not only from the subject matter of the individual claims, but also by all the information and features disclosed in the drawings and the description. They are, even if they are not the subject of the claims, claimed as essential to the invention, as far as they are new individually or in combination over the prior art.

Further features of the invention will become apparent from the other claims, the description and the drawings.

Fig. 1

in Axialansicht eine erste Ausführungsform eines erfindungsgemäßen Radiallüfterrades,

Fig. 2

in einer Darstellung entsprechend Fig. 1 eine zweite Ausführungsform eines erfindungsgemäßen Radiallüfterrades,

Fig. 3

in perspektivischer Darstellung einen Teil eines erfindungsgemäßen Radiallüfterrades,

Fig. 4

in perspektivischer Darstellung ein erfindungsgemäßes Axiallüfterrad,

Fig. 5

in perspektivischer Darstellung eine weitere Ausführungsform eines erfindungsgemäßen Radiallüfterrades,

Fig. 6

in Axialansicht eine weitere Ausführungsform eines erfindungsgemäßen Axiallüfterrades,

Fig. 7

in schematischer Darstellung einen Flügel eines Axiallüfterrades mit gesichelten Lüfterflügeln,

Fig. 8

einen Einzelflügel eines erfindungsgemäßen Axiallüfterrades,

Fig. 9

in Axialansicht eine weitere Ausführungsform eines erfindungsgemäßen Axiallüfterrades,

Fig. 10

das Axiallüfterrad gemäß Fig. 9 in perspektivischer Darstellung,

Fig. 11

in perspektivischer Darstellung einen Nabenkörper eines erfindungsgemäßen Axiallüfterrads,

Fig. 12

einen Ausschnitt aus einem erfindungsgemäßen Lüfterrad,

Fig. 13

in Ansicht eine Adapternabe eines erfindungsgemäßen Lüfters,

Fig. 14

in vergrößerter Darstellung einen Schnitt durch ein mit Endlosfasern verstärktes Lüfterteil eines erfindungsgemäßen Lüfters,

Fig. 15

einen Schnitt durch einen Lüfterflügel eines erfindungsgemäßen Lüfters in einer Ausbildung beispielsweise entsprechend den Fig. 5 oder 6,

Fig. 16

in einer Darstellung entsprechend Fig. 13 eine weitere Ausbildung einer Adapternabe eines erfindungsgemäßen Lüfters,

Fig. 17

in perspektivischer Darstellung ein weiteres Lüfterrad eines erfindungsgemäßen Lüfters, welches ein Nachleitrad ist.

The invention will be explained in more detail with reference to some embodiments shown in the drawings. Show it

Fig. 1

in axial view a first embodiment of a radial fan according to the invention,

Fig. 2

in a representation accordingly Fig. 1 a second embodiment of a radial fan according to the invention,

Fig. 3

in a perspective view a part of a radial fan according to the invention,

Fig. 4

in a perspective view of an axial fan according to the invention,

Fig. 5

a perspective view of another embodiment of a radial fan according to the invention,

Fig. 6

in axial view a further embodiment of an axial fan according to the invention,

Fig. 7

a schematic representation of a wing of an axial fan with sickle fan blades,

Fig. 8

a single wing of an axial fan according to the invention,

Fig. 9

in axial view a further embodiment of an axial fan according to the invention,

Fig. 10

the axial fan according to Fig. 9 in perspective,

Fig. 11

a perspective view of a hub body of a Axiallüfterrads invention,

Fig. 12

a section of a fan according to the invention,

Fig. 13

in view of an adapter hub of a fan according to the invention,

Fig. 14

in an enlarged view a section through an endless fiber-reinforced fan part of a fan according to the invention,

Fig. 15

a section through a fan blade of a fan according to the invention in an embodiment, for example, according to the Fig. 5 or 6 .

Fig. 16

in a representation accordingly Fig. 13 a further embodiment of an adapter hub of a fan according to the invention,

Fig. 17

in perspective view another fan of a fan according to the invention, which is a Nachleitrad.

In the following, various injection molded plastic parts of fans are described which are provided with continuous fiber reinforced thermoplastic tapes in critical areas. Such fan parts may in particular be fan wheels or fan blades, but also other loaded fan parts such as suspensions, wall rings, adapter hubs or hub body. Fan wheels may in operation be rotating axial, radial or diagonal fan wheels, or in-service idler or idler gears.

The thermoplastic bands are specifically embedded in the injection molding of the fan parts with respect to the installation point and the direction of action, so that these thermoplastic bands absorb the main loads of the component or ensure that deformations of these components in critical directions are specifically avoided. The injection molding material is preferably made of a thermoplastic polymer such as polyamide (PA6, PA66, PA66 / 6, PAPA, PPA, PA4,6, PA12), polyester (PBT, PET), polypropylene (PP), PPS, PES, PESU, PEEK , ABS, PC, ASA or the like, which is preferably reinforced with short or long fibers, such as glass, carbon, aramid, or natural fibers. The placement and orientation of the thermoplastic tapes can be made, for example, based on stress-strain simulations of the expected stresses and deformations and / or based on mold filling simulations with which manufacturing-specific properties, such as fiber orientation and weld lines, can be simulated.

The thermoplastic tapes form reinforcing tapes, which in the unprocessed state advantageously consist of quasi-endless fibers which are embedded in a matrix material. The fibers may in particular be glass, carbon, aramid or natural fibers. The matrix material may in particular be a thermoplastic such as polyamide (PA6, PA66, PA66 / 6, PAPA, PPA, PA4.6, PA12), polyester (PBT, PET), polypropylene (PP), PPS, PES, PESU, PEEK, ABS, PC, ASA and the like. Preferably, a polyamide, a polypropylene or a polyester is used as the material for the tapes. Preferably, the matrix material of the ribbons is the same or similar to the polymer of the injection molding material. The orientation of the quasi-endless fibers in such bands is parallel to the extent of the thermoplastic bands and unidirectional. This allows a very targeted introduction of the fiber reinforcement exactly in an orientation in which the reinforcing fibers can absorb critical component stresses and / or reduce critical component deformations. The thermoplastic tapes are flexible in the initial state transverse to their longitudinal extent, so that they can be wound up and unwound from a coil and flexibly placed with respect to the fan part to be manufactured, for example in an injection mold or an injection molding blank. Such thermoplastic tapes can be found in the market large lengths as meter goods rolled up on coils can be purchased inexpensively.

Fig. 1 shows a radial fan with a cover ring 1, which is connected in a known manner by fan blades 2 with a hub ring 3. The cover ring 1, the fan blades 2 and the hub ring 3 are formed integrally with each other by injection molding.

During injection molding, partially visible weld lines are formed when two different partial flows of liquid plastic material flow together during the injection molding process in the mold cavity. Such weld lines in the cover ring 1 are in Fig. 1 indicated by thin dashed lines 4. They affect the strength of the cover ring 1 and thus ultimately the fan wheel. The embedded in the material of the cover ring 1 short or long fibers are aligned substantially along the weld lines 4. Thus, the tie lines 4 often form the weak points of a cover ring 1 or other fan parts.

In the cover ring 1 are therefore in the embodiment, the reinforcing bands 5, 6 embedded, whose location are characterized by thick dashed lines. They extend over the circumference of the cover ring 1 and are approximately parallel to each other. The reinforcing tapes 5, 6 each have a distance from the outer edge 7 and from the inner edge 8 of the cover ring 1. The reinforcing tapes 5, 6 are completely or partially embedded in the material of the cover ring 1, ie they are in the injection molding in a region within the cavity the associated injection molding and are firmly and permanently connected after the injection molding with the surrounding plastic, but may be visible depending on the placement in the component on the surface of the finished fan part. The reinforcing tapes 5, 6 extend transversely to the stitching seams 4, which they, in the axial direction according to Fig. 1 seen, cross. Since the reinforcing bands 5, 6 extend over the circumference of the cover ring 1, it is ensured that independently of the number and / or the position of the binding lines 4, the reinforcing bands 5, 6 intersect the binding lines 4.

The reinforcing tapes 5, 6 in the unprocessed state advantageously consist of quasi-endless fibers which are embedded in a matrix material. In the course of the injection molding process, these reinforcing bands are completely or partially embedded in the injection-molded part.

Due to the reinforcing bands 5, 6, the cover ring 1, despite the existing weld lines 4 high strength. The radial fan wheel can therefore be used even at very high speeds, even with relatively small wall thicknesses of the cover ring. 1

While in the embodiment according to Fig. 1 the position of the weld lines 4 over the circumference of the cover ring 1 need not be known, because the reinforcing bands 5, 6 extend over the entire circumference of the cover ring 1, according to the embodiment Fig. 2 provided to provide the reinforcing bands 5, 6 only in the areas in which the weld lines 4 are located. It is generally known to the person skilled in the art, where the weld lines form during casting of the fan wheel in the cover ring 1. In addition, the course of the injection molding of the impeller can be simulated by a mold filling simulation, wherein the resulting weld lines 4 can be specified with respect to their position on the cover ring 1. The course of weld lines can also be determined by means of pattern fan wheels, which are manufactured without reinforcing bands. It is then possible to arrange the short reinforcing bands 5, 6 selectively in the injection mold at the locations where the weld lines 4 occur on the cover ring 1. The short reinforcing tapes 5, 6 are tuned in their length to the weld lines 4 so that the desired gain is achieved.

Fig. 3 shows at a section of a radial fan a further critical point on a fan. This is the transition between a fan blade 2 and a cover ring 1 of a radial fan. Such transitions 9 can be strength-critical points. For this reason, this transition region 9 is reinforced by the reinforcing ribbons 5. They extend transversely to the transition region 9 and are partially or completely embedded in the fan blades 2 and the cover ring 1. The reinforcing bands 5 may be located on the surface of the fan blades 2 and the cover ring 1, respectively. With the aid of stress-strain simulations or fracture patterns of unreinforced fan wheels, the locations and with stress-strain simulations the length of the reinforcement bands 5 can be determined so that they sufficiently reinforce these strength-critical transition regions 9. The reinforcing ribbons 5 are placed over the length of the transition regions 9 so that the critical transition region 9 is reliably reinforced over its length.

A strength-critical transition region 9 can also exist between the fan blades 2 and the other hub ring 3. This applies to fan impellers of radial, diagonal or axial design as well as for leading or Nachleiträder of fans (stators). For this reason, the reinforcing bands 5 are provided at the required locations in these transition areas.

Corresponding to axial fan wheels Fig. 4 these strength-critical transitions 9 are provided at the transition from the fan blades 2 in a hub ring 3. The fan blades 2 are here approximately radially from the outer wall of the hub ring 3, which is cylindrical and has on its inside inwardly projecting eyes 11, which has at least one passage opening 12 for fastening screws. The transition point 9 extends on the outside of the hub ring 10 with a slope. The reinforcing bands 5 in turn extend transversely, preferably perpendicular to the transition point 9. The placement of the reinforcing bands 5 and also their length are determined by a stress-strain simulation properly determined, so that the Axiallüfterrad in use has the desired strength.

It can be provided per transition 9 more or a plurality of reinforcing bands 5, depending on the desired requirements of the respective fan. In the Fig. 3 and 4 is shown only schematically for each transition 9 a reinforcing tape 5.

Fig. 5 shows a radial fan with the two rings 1, 3, between which extend the fan blades 2, which are integrally formed with the two rings 1, 3. In fan blades are often the leading and trailing edges 13, 14 deformation critical. In use, their deflection can often reach critical values for the functioning of the fan wheel. For acoustic reasons, however, in particular the trailing edges 14 should be as thin as possible. With the help of the reinforcing bands, this requirement can be met without the deflection of the fan blades during operation of the fan wheel reaches critical values. In the fan blades 2, at least the trailing edges 14 are reinforced by the reinforcing ribbons 5. They extend advantageously over the entire length of the trailing edge 14. As in the previous embodiments, the reinforcing ribbons 5 are partially or completely embedded in the material of the fan blade 2. The reinforcing ribbons 5 are provided along the trailing edge 14 so as to be a short distance from the trailing edge.

A reinforcing tape 5 may also be provided on the front edge 13. Also in this case, the reinforcing strip 5 is partially or completely embedded in the material of the fan blade 2. The reinforcing strip 5 advantageously extends over the entire length of the front edge 13.

It is also possible to provide the reinforcing ribbons 5 at the front edge 13 and at the trailing edge 14 of the fan blade 2, if this should be required for strength or load reasons. It is also conceivable Provide bands in the middle regions over the entire width of a fan blade between the front edge 13 and trailing edge 14, which in the spanwise direction, so transverse to hub or cover ring, extend to reduce the deflection of the fan blades.

The length and / or the width of the region in which the reinforcing ribbons 5 are provided and their orientation are calculated and determined in advance by stress-strain simulations. The use of the reinforcing ribbons 5 makes it possible to form the fan blades 2 relatively thin, whereby a considerable material savings is possible. Due to the reinforcing bands 5, the fan blades 2 may be made thinner than the conventional fan blades, which are provided only with the spritzvergossenen short or long fibers. It may also be possible under certain circumstances a cheaper and / or lighter plastic used for the injection molding, for example, with less fiber content, since the reinforcing bands can relieve the surrounding plastic.

Fig. 6 shows an axial fan with the hub ring 3 and the projecting from him fan blades 2. They have the leading edge 13 and the trailing edge 14. The leading edge 13 and the trailing edge 14 have a crescent shape. Such sickled axial fan blades often deform very much in the radial direction during operation. There is the risk that the fan blades 2 rub against the surrounding wall ring. For this reason, in the conventional blower blades made of injection-molded plastic, the sickle is reduced, which, however, leads to the fact that the acoustic values are larger.

Through the use of the reinforcing bands 5, it is possible to provide the fan blades 2 with optimum sickling, so that the acoustic values are in the optimum range, without the risk that the axial fan blades 2 will deform greatly. In particular, through the use of reinforcing tapes 5 prevents the fan blades 2 from touching the surrounding wall ring.

The reinforcing ribbons 5 are positioned within the fan blades 2 so that the deformation of the fan blades 2 is minimized. The reinforcing bands 5 extend in the illustrated embodiment over most of the spanwise length of the fan blades 2. With the help of stress-strain simulations, the position and the number of reinforcing bands 5 can be determined.

The fan blades 2 may be wound or have any other shape required for the application. The reinforcing bands 5 ensure that the fan blades can not deform excessively in operation. The reinforcing bands 5 are in turn partially or completely embedded in the injection molding of the fan blades 2. The length of the individual reinforcing ribbons 5 within a fan blade 2 and their distance from each other can be determined by stress-strain simulations.

Based on Fig. 7 , which schematically shows an axial view of an axial fan blade, the term sickle of an axial fan blade is to be defined. By the fan blades 2 15 coaxial cylinder cuts are placed to the fan wheel. Incomplete cylinder cuts of fan blades should not be considered. A complete cylinder cut includes fan blade portions from the leading edge 13 to the trailing edge 14 as a contiguous surface. The centerlines 18 of these cylinder cuts each have their longitudinal center point 19. The particular centerline 18a of the radially outermost complete cylinder section has the center point 19a. Each center 19 defines with the Lüfterradachse 15 a plane 16, specifically forms the center 19 a with the Lüfterradachse the plane 16 a. For each radial position, the angle α is now defined between the associated plane 16 and the plane 16a. With the course of the angle α Here the sickling of an axial fan blade defined. A strongly sinuated wing is said to be, if the maximum occurring amount of α is greater than 10 °, from a very sinewy, if this maximum amount is greater than 20 °. It is known that a strong sickle is advantageous in particular for low noise emission of an axial fan.

Based on Fig. 8 Another critical area of an axial fan is described. It consists of individual wings 2a, which are attached to a hub ring 3. Each individual wing 2a consists of a respective fan blade 2 and a connection element 20, which is designed in the embodiment as a wing base, with which it is attached to the hub ring 3 in a known manner. In such individual wings 2a, a critical point is the transition from the connection element 20 into the fan blade 2. Here, the force is introduced from the connection element 20 into the fan blade 2. This area is reinforced with the reinforcement strips 5, as illustrated by the dashed lines.

An attachment element 20 designed as a wing foot advantageously has a circular outline and is approximately mushroom-shaped. The reinforcing tapes 5 extend from the connecting element 20 into the fan blade 2. They run transversely to the transition region 9 between the connecting element 20 and the fan blade 2. The distribution and the length of the reinforcing tapes 5 can in turn be determined by stress-strain simulations. The reinforcing bands 5 ensure that high forces can be absorbed at the critical area 9 without having to fear that the individual wing 2a will break off at the transition point 9. The reinforcing bands 5 are advantageously distributed over the circumference of the connecting element 20 designed as a wing foot and are partially or completely embedded in the material of the individual wing 2a.

Connecting elements 20 of a single wing 2a may also have a different embodiment than that of a wing base. For example, a single wing 2a can be fastened with a screw to a correspondingly shaped hub ring 3. Accordingly, the attachment elements 20 consist of a corresponding bearing surface on the side of the individual wing 2a, against which the individual wing 2a rests in the assembled state on a counterpart of the hub ring 3, and a through-hole for a screw. Such connection elements 20 and their transition 9 to the fan blade 2 are highly stressed areas and can be advantageously reinforced with reinforcing bands 5, 6. In the case of a connection element 20 having a through-hole, in particular a reinforcing strip which surrounds the through-hole in the injection-molding material can advantageously reinforce the individual leaf 2a.

The Fig. 9 and 10 show an axial fan, in which the hub ring 3 is reinforced inside the material with reinforcing bands 5. The hub rings 3 are often highly stressed parts in operation because they must ensure the transmission of power from the engine to the wings 2. In some cases, the hub rings 3 are also pressed onto a shaft or other receptacles, which leads to additional stresses in the hub ring 3.

These high loads of the hub ring 3 are absorbed by the fact that in the hub ring 3, the reinforcing tape 5 is embedded. It runs in the exemplary embodiment helically almost over the entire axial height of the hub ring 3. The slope of the reinforcing strip 5 and the height range in which the reinforcing strip is based on the critical areas within the hub ring 3. The position and the course of the helical reinforcing strip 5 can again be determined by stress-strain simulations. The reinforcing band 5 is partially or completely embedded in the material of the hub ring 3.

Depending on the load of the hub ring 3, more than just one reinforcing band 5 can be provided, wherein these several reinforcing bands are each arranged helically extending in the hub ring 3. Multiple layers of helically extending reinforcing ribbons may also be disposed so that the reinforcing ribbons of adjacent layers intersect. Reinforcement bands 5 can also be introduced in approximately circular running in the hub ring 3.

Fig. 11 1 shows a hub body 22 of an axial fan wheel constructed from individual wings 2a with a connecting element 20 designed as a wing foot. Two such hub body 22 are mirror images of each other firmly connected to each other, wherein between the two hub bodies, the single fan blades 2a according to Fig. 7 be clamped with their trained as a wing foot attachment element 20. The hub body 22 has recesses 23 distributed over its circumference, each receiving a connection element 20 of the single leaf 2a.

The hub body 22 has a bottom 24 in which an opening 25 is located centrally. In the mounted state protrudes through the opening 25, a shaft on which the hub body 22 is attached. The opening 25 is surrounded by a circumferential annular wall 26. Along the outer edge of the bottom 24 extends a peripheral edge 27 which is higher in the axial direction of the hub body 22 than the annular wall 26. In the end face of the annular raised edge 27, the recesses 23 are arranged. In the area between the adjacent recesses 23 are receiving openings 28 for screws, with which the two hub body 22 are screwed together with the interposition of the wing feet formed as connecting elements 20 against each other. Due to the bracing processes arise in the hub body 22 very high voltages. For this reason, hub body made of metallic material are often used. By using the reinforcing bands 5, it is possible to produce the hub body 22 despite the high voltage of plastic injection molding. The reinforcing bands 5, 6 extend over the circumference of the hub body 22 and are provided in the edge 27. The two reinforcing tapes 5, 6 run near the front side 29 of the edge 27 and are guided around the recesses 23 in such a way that they run at a small distance from the bottom 30 of the recesses 23. The reinforcing bands 5, 6 are positioned so that they do not come into the region of the receiving openings 28. As in the previous embodiments, the reinforcing bands 5, 6 are partially or completely embedded in the material of the hub body 22.

In the embodiment, two approximately mutually parallel reinforcing bands 5, 6 are provided. Depending on the loads occurring in the hub body 22 further reinforcing ribbons can be embedded in the required areas in the material of the hub body 22. The reinforcing tapes 5, 6 are provided so that they can absorb the stresses that occur in the region of the recesses 23. If, therefore, the individual wings 2a are braced with their connecting element 20 designed as a wing foot in the depressions 23 of the two hub bodies 22, the stresses can be reliably absorbed with the aid of the reinforcing bands 5, 6. This has the consequence that the hub body 22 can no longer be made of metallic material, but as plastic injection molded parts.

Im in Fig. 11 illustrated embodiment, two identical hub body 22 are screwed mirror-inverted to a hub ring 3 against each other. In similar embodiments, two or more different hub body to a hub ring 3 can be connected to each other, so that the wing feet formed as connecting elements 20 are clamped in the hub ring 3. The associated with the jamming of the wing feet high component voltages in one or more of the hub body can be intercepted by analogy with embedded reinforcing bands.

Im in Fig. 11 illustrated embodiment, the hub ring is mounted on a shaft. Other embodiments may be configured to be mounted on the flange of, for example, an external rotor motor. In such hub rings, the parts 24, 26 are completely missing.

Fig. 12 shows another critical point on a fan. Shown as a section of the area in which the fan is attached to a motor or to an adapter, similar to the in Fig. 1 to be recognized inner area for attachment of the hub ring 3 to a motor or an adapter. For this purpose, mounting holes 31 are provided which are distributed over the circumference of a central opening 32 in the hub ring 3. Between the mounting holes 31 and the edge 33 of the opening 32, which in particular takes over the function of centering to a motor or an adapter hub, there are narrow areas 34, which represent weak points of the hub ring 3. In addition, narrow seams 4 often result in these narrow regions 34, which lead to a further weakening of the already weak region 34.

For this reason, the fastening holes 31 are reinforced over their circumference by a reinforcing tape 5. The reinforcing bands 5 are spaced from the edge of the mounting holes 31 and the edge 33 of the central opening 32 and are partially or completely embedded in the material of the hub ring 3 as in the previous embodiments. Due to the reinforcing bands 5, bushes or the like can be pressed into the fastening holes 31, without this measure having an adverse effect on the strength in the narrow regions 34.

Fig. 13 shows an adapter hub 35 of a fan, which also consists of plastic injection molding. The adapter hub 35 has the central, central opening 36, which is surrounded in the embodiment of two spaced-apart reinforcing bands 5, 6. The reinforcing bands 5, 6 and the edge 37 of the opening 36 are approximately coaxial or concentric with each other. Due to this design, the very high voltages can be absorbed, resulting from the pressing of the adapter hub 35 on a shaft or a cone. The reinforcing tapes are partially or completely embedded in the material of the adapter hub 35. The number and the course of the reinforcing bands 5, 6 about the central opening 36 can be optimized by a stress-strain simulation, so that the reinforcing bands 5, 6 can be arranged so that a maximum reinforcement of the adapter hub 35 in the region of the opening 36 is reached.

Fig. 14 shows by way of example in cross section three superimposed reinforcement bands 5, 6, which are incorporated in a plastic component of a fan (fan part). They are the same design in the embodiment, but may also have a different training depending on the application. The reinforcing bands 5 are completely embedded in the material of the fan part 38. The same reinforcing bands 6 are only partially embedded in the material of the fan part 38 and are visible on the surface of the finished fan part 38. The reinforcing tapes 5, 6 have the quasi-endless fibers 39 embedded in the matrix 40. The fibers 39 are unidirectionally aligned and parallel to each other. The fibers 39 can absorb in particular high tensile stresses perpendicular to the plane of the drawing. Therefore, the reinforcing ribbons 5, 6 are arranged in the injection-molded component so that the fibers 39 can absorb the corresponding stresses. The exact placement of the reinforcing tapes 5, 6 and the position of the fibers 39 can be optimized, for example, by stress-strain simulations.

Fig. 15 shows a section through a fan blade 2, as it is, for example, in the embodiments according to the Fig. 5 . 6 or 17 can represent. He has in cross section the profile of a wing and has in the region of the leading edge 13 and in the region of the thin trailing edge 14 respectively a reinforcing tape 5. In particular, the reinforcing band 5 in the region of the thin trailing edge 14 leads to a very high load capacity of the fan blade 2.

Depending on the load capacity of the fan blade 2, further reinforcing ribbons may be embedded in the fan blade 2 in the area between the front edge 13 and the trailing edge 14.

The profile of the fan blade 2 is advantageously designed so that its thickness d increases steadily both from the leading edge 13 and from its trailing edge 14. The maximum thickness dmax has the fan blade 2 in a region which is closer to the front edge 13 than to the rear edge 14.

In order to achieve low acoustic values, the trailing edge 14 of the fan blade 2 is according to Fig. 15 especially thin. To achieve this, the wing thickness of the already thin wing profile again decreases sharply over the relatively short area shk near the trailing edge. Thus, for example, the wing thickness in a range shk, which is less than 10% of the total chord length, to the trailing edge 14 down again by 30% -70% decrease. With such thinly tapering trailing edges, the introduction of one or more reinforcing ribbons 5 in the spanwise direction (transverse to the drawing surface) prevents excessive deformation during operation.

Fig. 16 shows the adapter hub 35, in which the mounting holes 31 are provided near the outer edge 41. The mounting holes 31 and the central opening 36 are each surrounded by reinforcing bands 5. The fastening holes 31 are each surrounded by a reinforcing band 5 and the central opening 36 by way of example by two reinforcing bands 5, 6. The arrangement and the course of the reinforcing bands 5, 6 corresponds to that of FIG Fig. 13 described embodiment. The reinforcing bands 5 surrounding the attachment openings 31 are corresponding Fig. 12 provided and arranged.

The example according to Fig. 16 shows that at the same time various parts of the fan can be reinforced by the reinforcing bands 5, 6 on the fan.

Fig. 17 Finally, shows a reinforced with reinforcing bands fan impeller of plastic injection molding, which is a Nachleitrad. For the purposes of the present invention, in addition to impellers of axial, diagonal or radial design also Vorleit- or Nachleiträder are fan wheels. The Nachleitrad according to Fig. 17 consists essentially of fan blades 2, a hub ring 3 and a cover ring 1. The Nachleitrad has in the embodiment in addition to aerodynamic functions also the function of suspension of a (not shown) motor (not shown) rotating Axiallüfterrad which in the installed state of the cover ring 1 of Nachleitrads are surrounded. For attachment of the motor, a flange 43 is provided on the hub ring 3, in which holes 31 are provided for fixing a motor. For attachment of the Nachleitrads on a device wall or the like, a further mounting flange 44 is provided with holes 42 on the cover ring 1. The Nachleitrad must now hold a motor fan during transport, storage and operation positional relative to the device wall and in particular also relative to the cover ring 1. The wings of a motor fan must not touch the inner wall 45 of the cover ring 1 of the Nachleitrades. Therefore, only a very small deformation of the flange 43 of the hub ring 3 relative to the cover ring 1 is permissible even under high loads. Thus, the wings 2 of the Nachleitrades may deform only to a very small extent. In order to make this possible with justifiable use of material in a plastic injection-molded part, one or more reinforcing bands 5, 6 are introduced in the areas of front edge 13 and rear edge 14 of the fan blades 2, which are completely or partially embedded in the surrounding plastic. Such reinforcing tapes are advantageously provided on all fan blades 2 of the Nachleitrads. In the exemplary embodiment, these bands simultaneously reinforce the transitions 9 between fan blades 2 and hub or cover ring 3, 1.

In the embodiment according to Fig. 17 are also the holes 42 reinforced with reinforcing bands, similar to the holes 31 in the embodiment according to Fig. 12 , Also in the embodiment according to Fig. 17 Binding seams and high loads in the areas of the holes 42 are to be expected. The reinforcing bands 5 are in this embodiment, however, in the holes 42 on the workpiece surface, ie they are not completely embedded in the surrounding plastic. The reinforcing tapes were wound before the injection molding process directly on the pins in the injection mold, which are the negative parts of the holes, wound and then encapsulated. Advantageously, the bands are still fixed on the pins, for example with a special adhesive, such as a thermal adhesive.

From the various examples, it can be seen that fan wheels and other fan parts, such as hub body, wall rings or suspensions can be made of injection-molded, fiber-reinforced plastic with a high strength by additionally or partially embedded in the injection molded part, the quasi-continuous fiber reinforced bands 5, 6 are. These reinforcing bands 5, 6 are selectively introduced with respect to their position and in their direction of effect in the component so that the desired gain is achieved. The reinforcing bands 5, 6 can be placed in the injection molding tool itself via appropriate devices prior to the injection molding process and held with suitable devices. If the plastic is introduced into the injection mold, the reinforcing bands are completely or partially encapsulated by the liquid plastic mass.

For example, the reinforcing ribbons in the injection molding tool can be held by special pins, which are withdrawn before completion of the injection molding process so that the areas that were still occupied by the pins at the beginning of the injection molding, still filled with plastic melt.

Another very advantageous method of placing the reinforcement bands in the injection molding tool is to attach them to the inner walls of the injection molding tool in the area of the tool cavity. This can preferably be achieved by gluing, for example with a thermal adhesive, which develops its adhesive effect only at the elevated temperature of the injection molding tool. In this technique, a reinforcing tape may be at least partially visible on the finished workpiece surface.

But it is also possible to prefabricate a Spritzgiessrohling, which does not yet have the entire volume of the finished component, and to him the reinforcing tape 5, 6 to fix, which can be carried out for example in a simple manner by welding or gluing. This injection molding blank with the attached reinforcing tape is then encapsulated again in a further injection molding process, so that the injection molding blank is brought to the finished contour.

As explained with reference to the various examples, one or more reinforcing bands may be incorporated in the injection-molded part. They are positioned and aligned in such a way that they absorb the main loads of the respective component or specifically avoid deformations in critical directions. Also manufacturing-related vulnerabilities, in particular the weld lines 4, can be specifically reinforced by the use of the reinforcing bands 5.

The positioning and orientation of the reinforcing bands within the injection-molded part can be simulated and optimized by stress-strain simulations with regard to the expected stresses and deformations. With mold filling simulations manufacturing-specific properties can be simulated, such as fiber orientation and weld lines.

Mold-fill simulation software and stress-strain simulation software are well known and commercially available.

Fan wheels, fan blades, adapter hubs, suspensions or other fan parts can be made entirely of plastic. The wheels can be operated with high limiting speeds. Due to the reinforcing bands 5, 6 no expensive material, such as metallic material must be used, but it can be used for the production of inexpensive plastic. Despite the cheaper material, the same or even higher limit speeds can be achieved as when using metallic material. The deformations in the operating state, for example in heavily sickled axial fans, are considerably reduced. Wall thicknesses and thus injection molding material use in the manufacture of fan parts can be reduced.

Claims (15)

Fan with at least one fan wheel with fan blades (2), which are connected to each other with at least one ring (1, 3), wherein at least one fan wheel, a fan blade (2) and / or another fan part (1, 2, 3, 20, 22, 35, 38) has at least one load-critical region which is reinforced with at least one reinforcing element (5, 6),
characterized in that the reinforcing element (5, 6) is a coil developable from a coil, which consists of a thermoplastic matrix enclosing unidirectional, parallel to the length of the reinforcing strip, quasi-endless fibers, and that the fan part (1, 2, 3 , 20, 22, 35, 38) is a molded part of thermoplastic material, in which the reinforcing element (5, 6) is partially or completely embedded. Fan according to claim 1,
characterized in that the reinforcing band (5, 6) annularly surrounds an inlet or outflow opening of a ring (1, 3) of the impeller, and in that the reinforcing band (5, 6) preferably transversely to at least one weld line (4) of a fan part (1, 2, 3, 20, 22, 35, 38) runs and this crosses. Fan according to claim 1 or 2,
characterized in that a plurality of reinforcing bands (5, 6) and / or side by side and / or transversely to each other in the fan part (1, 2, 3, 20, 22, 35, 38) are arranged. Fan according to one of claims 1 to 3,
characterized in that the reinforcing ribbons (5, 6) are provided near the leading and / or trailing edges (13, 14) of fan blades (2) and preferably along the leading and / or trailing edges (13, 14) of FIG Fan blades (2) extend. Fan according to one of claims 1 to 4,
characterized in that the reinforcing bands (5, 6) in the region of fan blades (2) distributed over the width between the front edge (13) and trailing edge (14) are arranged and each extending approximately in the spanwise direction of the fan blades (2). Fan according to one of claims 1 to 5,
characterized in that in the hub ring (3) and / or cover ring (1) at least one reinforcing strip (5) preferably helically over the circumference of the hub ring (3) and the cover ring (1). Fan according to one of claims 1 to 6,
characterized in that the reinforcing bands (5, 6) at the transition (9) from a fan blade (2) to at least one ring (1, 3) are provided so as to intersect the transition (9). Fan according to one of claims 1 to 6,
characterized in that the fan wheel has individual wings (2a) which in each case consist in one piece of a fan blade (2) and a connection element (20), preferably designed as a wing base, with which the individual wings (2a) are connected to a hub ring (3), and that advantageous in the connection element (20) reinforcing strips (5, 6) are housed, preferably extending transversely across the transition region (9) between the connection element (20) and fan blades (2) in the fan blades (2). Fan according to claim 8,
characterized in that the hub ring (3) consists of at least two mutually clamped hub bodies (22), and that advantageously near the end face (29) of an annular hub body (22) at least one reinforcing band (5, 6) is provided which extends over the Extends the circumference of the hub body (22). Fan according to one of claims 1 to 9,
characterized in that at least one reinforcing strip (5, 6) surrounds at least one fastening opening (31, 42) of a fan part (1, 2, 3, 20, 22, 35, 38). Method for producing a fan part of a fan according to one of Claims 1 to 10, in which a fan wheel, a fan blade (2) or another fan part (1, 2, 3, 20, 22, 35, 38) is produced in an injection mold,
characterized in that in the injection mold at least one reinforcing tape (5, 6) is inserted and positioned, which has previously been unwound from a spool and separated to the correct length, and that subsequently the plastic is injected, the reinforcing tape (5, 6 ) partially or completely encloses. A method according to claim 11, characterized in that at least one reinforcing element (5, 6) has been fixed in position in the region of the mold cavity of the injection mold before the actual injection molding process on the tool inner wall, preferably with a thermal adhesive, and thus only partially embedded in the surrounding plastic. A method according to claim 11 or 12, characterized in that at least one reinforcing element (5, 6) is fixed in position by means of pins in the cavity of the injection mold, which is withdrawn from the mold cavity before completion of the injection molding process be that an area in which they were still at the beginning of the injection molding process, closed with plastic melt. A method of manufacturing a fan according to any one of claims 1 to 10, wherein a fan wheel, a fan blade (2) or another fan part (1, 2, 3, 20, 22, 35, 38) is produced in an injection mold,
characterized in that a Spritzgiessrohling prefabricated and at least one reinforcing strip (5, 6) is fixed, preferably by welding or gluing, and that the Spritzgiessrohling is then overmolded with further thermoplastic so that the reinforcing strip (5, 6) partially or is completely enclosed. Method according to one of claims 11 to 14,
characterized in that the positioning of a reinforcement strip (5, 6) in the mold or on the Spritzgiessrohling is made based on a stress-deformation simulation and / or a mold filling simulation.

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