Rotary fan

Abstract

The present disclosure relates to an aircraft rotor fan (1) comprising a plurality of rotor blades (2) arranged rotationally symmetrically around a rotor shaft (3). Each rotor blade (2) is made of a composite material comprising reinforcing fibers (5) embedded in a matrix material (6), and comprises a blade body (4) extending longitudinally (7) between a bottom (8) and a top (9) and transversely (10) between a leading edge (11) and a trailing edge (12). The rotor fan (1) comprises a hub (13) having a hub body (13) at least partially made of a composite material comprising reinforcing fibers (14) embedded in a matrix material (15). The bottom (8) of each rotor blade (2) comprises a pedestal (17) at least partially embedded in the composite material of the hub (13).

Description

Technical Field

[0001] The present disclosure relates to a rotor fan made of a fiber-reinforced composite material and a method for manufacturing such a rotor fan.

Background Art

[0002] Patent Document 1 was first published in May 2019 on behalf of Safran Aircraft Engines and targets rotor blades. The rotor blade includes a blade body made of a composite material containing a fiber reinforcement material densified by a matrix. The blade body extends longitudinally between a root or bottom and a tip or top and extends transversely between a leading edge and a trailing edge. The fiber reinforcement material of the blade body includes a first portion composed of a plurality of yarn layers interconnected by a three-dimensional or multilayer weave. The second portion forms all or part of at least one leading edge or at least one trailing edge of the blade. The second portion includes a plurality of randomly oriented short fibers. The yarns of the plurality of yarn layers of the first portion and the short fibers of the second portion are embedded in the matrix.

[0003] Patent Document 2, first published in May 2018 on behalf of Safran Aircraft Engines, relates to a method for manufacturing an airfoil element from a composite material. The method includes the following method steps, namely, a step of producing a fiber preform impregnated with resin, a step of polymerizing the resin with a matrix to obtain an airfoil element made of a composite material containing a fiber reinforcement material densified by the matrix, and a step of clamping a metal reinforcement to the airfoil element of the composite material, wherein the metal reinforcement is clamped to the airfoil element by a rivet. The method further includes a step of inserting a spacer element between the fibers of the fiber preform before impregnating the fiber preform with resin to form at least one passage between the fibers of the fiber reinforcement of the airfoil element of the composite material, and a step of removing the spacer element after the resin has polymerized.

[0004] Patent Document 3 was first published in May 2018 on behalf of Rolls Royce Nam Tech Inc., and relates to a composite turbomachine comprising a hub composed of fibers and resin and a plurality of blade assemblies. Each blade assembly consists of a blade, a base, and a tongue. The plurality of blade assemblies are circumferentially arranged around the hub, each engaging with an adjacent blade assembly, and are held in place by the hub and a band covering the tongues of each of the plurality of blade assemblies.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

[0006] In today's aviation industry, there is a need for rotor fans that meet conflicting requirements such as an integrated design and easy recyclability. Manufacturing a rotor fan from plastic materials generally has the advantages of enabling mass production by the underlying process and obtaining a high degree of freedom in terms of shape. For this reason, recently, there has been a growing interest in replacing rotor parts made of metal materials with those made of lightweight composite materials at least partially. Rotor parts made of fiber-reinforced composite materials are not only lighter than metal parts but also demonstrate improved thermal properties and may have lower material and production costs than metal parts.

[0007] However, rotor parts made of composite materials tend to have drawbacks such as low resistance to loads and stresses. Nevertheless, parts in the aviation industry, especially rotor parts, are exposed to high loads, many load cycles, and temperature variations, so high structural integrity is essential. This creates a dilemma where it is necessary to use combinations of materials that are usually difficult to recycle or to select production processes that are not suitable for mass production.

[0008] Accordingly, one object of the present disclosure is to provide a rotor fan that enables efficient mass production and meets the need to suit high mechanical requirements, and a method for manufacturing such a rotor fan.

[0009] In one aspect, the present disclosure relates to a rotor fan for an aircraft. The rotor fan generally consists of a plurality of rotor blades arranged rotationally symmetrically around a rotor shaft. Good results are obtained when the rotor blades are made of a fiber-reinforced composite material that includes reinforcing fibers at least partially embedded in a surrounding matrix material. Each rotor blade generally includes a blade body that extends longitudinally between a bottom and a top.

[0010] Considering the possibility of combining variations related to heat and pressure, high mechanical stresses due to high speeds and acceleration forces, and potential effects by elements such as bird strikes, the selection of suitable materials is very limited, especially regarding materials suitable as matrix materials. Good results are obtained when the blade body is made of a fiber-reinforced composite material that includes continuous fibers, particularly in the direction of the generated loads. It should be understood that continuous fibers are fibers that are considerably long compared to their diameter. Good results are obtained when using fibers in the range of at least 20 mm or more. In a variant, the continuous fibers can be arranged directionally. The fibers are preferably arranged substantially parallel to the longitudinal direction of the rotor blade.

[0011] Alternatively, or in addition, the composite material of the blade body may include a number of fiber layers interconnected by three-dimensional or multi-layer weaving. The fibers or layers of fibers can be prepared by a preforming process. Thereby, the fibers can be arranged by an individual fiber placement process. Alternatively, or in addition to that, ready-made fiber tapes can be used. The fibers may be stitched together so that the layers of fibers are securely held in the desired arrangement. In the transverse direction, the blade body extends between a leading edge and a trailing edge. The continuous fibers or fiber layers can be pre-impregnated with a suitable composite material. Good results are obtained by using a prepreg, which is a fiber fabric pre-impregnated with resin.

[0012] In principle, either a thermoplastic material and / or a thermosetting material, for example in the form of a resin, can be used as the matrix material. Depending on the shape and desired properties, the blade body can be produced by a molding process such as a resin transfer molding process (RTM), or a molding process in which the matrix material is plasticized, such as a hot press, or a molding process in which the matrix material is injected, such as injection molding. In a variant, a hot press process can be used to produce the blade body, in which case the composite material of the blade body includes continuous fibers embedded in a matrix material. Good results are obtained by using a thermoplastic material from the polyaryletherketone (PAEK) family. For example, polyetheretherketone (PEEK) is a colorless organic thermoplastic polymer with excellent mechanical and chemical resistance maintained at high temperatures. The thermoplastic materials from the polyaryletherketone (PAEK) family are suitable for aerospace applications because they are one of the few plastic materials compatible with ultra-high vacuum applications.

[0013] For an aerodynamically optimized design, the blade body can be spatially curved transversely between the leading edge and the trailing edge. Alternatively or additionally, the blade body can also be bent longitudinally between the bottom and the top. To further enhance stability and wear resistance, the blade body can be provided with a reinforced leading edge. The reinforcement can be designed as an inlay or applied on or between the fiber layers of the blade body. The inlay can be fabricated as an insert and / or a bent metal plate made of, for example, titanium. When the ratio of fiber to matrix is between 2:1 and 1:1, a good compromise between the structural integrity and flexibility of the rotor blade is obtained.

[0014] The rotor fan typically further comprises a hub having a hub body made of a composite material containing reinforcing fibers at least partially embedded in a matrix material. Good results are obtained when the reinforcing fibers of the hub are short fibers having a length in the range of 0.5 - 10 mm and are arranged in a non-oriented manner, for example, by an injection molding process. The hub body can be designed as an annular sleeve fabricated, for example, by an injection molding process, a resin transfer process, or a combination thereof. The hub is typically designed to interconnect a plurality of rotor blades to the engine shaft. Thus, the bottom of each blade body and / or the pedestal interconnected thereto can be embedded in the matrix material of the hub body. The blade body between the bottom and the top of each rotor blade typically extends radially from the hub.

[0015] When the hub body has a conical outer surface, good results are obtained regarding an aerodynamically favorable design. The outer surface is to be understood as a covering surface of the hub body that surrounds the rotor shaft and faces away from the rotor shaft. Depending on the design of the rotor shaft, the central opening of the hub may have a staggered design. The hub may be provided with bushings so that the rotor fans can be assembled to their respective rotor shafts. The hub body can be attached to the rotor shaft by friction joining through the bushings. Good results are obtained when the hub body is shrink-fitted onto the rotor shaft.

[0016] To enable rapid and reliable production of the hub body, the bushings can be overmolded in the same manufacturing process together with the pedestals of the rotor blades. The bushings and pedestals of the rotor blades are preferably at least partially embedded in the composite material of the hub. To enable shrink-fitting and force transmission between the hub body and the rotor shaft, the bushings can be made of, for example, any one of the materials titanium, aluminum, steel, or a combination thereof.

[0017] To enable a structurally strong connection between the hub and the rotor blades while allowing for rapid production, the bottom of each rotor blade typically has a pedestal that is at least partially embedded (surrounded) in the composite material of the hub. The pedestal is usually attached to the hub body by an adhesive provided by the matrix material of the hub body. To enhance the mechanical load-bearing capacity of the hub body and thus the entire rotor fan, the hub body is usually made of a composite material containing reinforcing fibers. When the reinforcing fibers are short fibers, a good compromise between an efficient process and the desired mechanical stability can be achieved. The short fibers are typically in the range of 0.5 mm to 10 mm, preferably in the range of 3 mm to 5 mm. This enables an injection molding process in which the fibers are mixed into the plasticized matrix material and injected into the mold together with the matrix material.

[0018] Even when subjected to high loads or impacts from objects such as bird strikes in the air, the pedestal can be interconnected with the hub body by a form fit to securely attach the rotor blade to the hub body so that no separation occurs between the rotor blade and the hub body. Good results can be obtained if the bottom of the aerodynamically designed rotor blade actually has an undercut pedestal. The pedestal can be designed as a basically rectangular block with an undercut in the form of a recess.

[0019] In a variant, the recess extends at least partially along the pedestal in the transverse direction of each rotor blade. The recess can be designed as an essentially V-shaped or U-shaped channel. In a variant, the hub body has a conical outer surface. The pedestal can also be wedge-shaped to achieve a smooth transition between the top surface of the pedestal and the outer surface around the hub body. The top surface of the pedestal is understood as the surface facing the top of the rotor blade. To achieve a smooth flow of force from the hub body to each rotor blade, the rotor blade can be fused to a pedestal with a transition region that creates a smooth transition between the blade body and the top surface of the pedestal.

[0020] It is essential to have an adhesive joint between the pedestal and the hub because this joint is subjected to dynamic loads, vibrations, and bending loads that can cause joint failure, and as a result, the rotor blade may peel off from the hub body. To prevent this failure, a pedestal shape that is preferable for the manufacturing process of the rotor blade and also preferable for a stable connection with the hub body is desirable. Usually, since the pedestal is at least partially embedded in the hub body, it has been proven that a Y-shaped configuration is preferable. The Y-shaped pedestal has two legs that extend away from the bottom at an angle to the longitudinal direction. Such a design allows the continuous fibers or fiber layers of the hub body to reach from the top to the pedestal. The fiber layers of the two legs of the pedestal can be fused at the bottom and are stacked parallel to each other from the bottom to the top within the blade body and reach throughout. With this design, the reinforcing fibers can be well aligned within the mold during the production of the rotor blade and can be embedded in the hub body so that the loads and bending loads can be well compensated and transmitted from the blade body to the hub body via the two legs.

[0021] When the hub body is composed of multiple parts, good results can be obtained regarding accurately positioned attachment. The hub body can comprise at least one ring that is at least partially embedded within the composite material. The ring can be attached to the pedestal by a shape-fit connection before the pedestal and the ring are at least partially embedded in the matrix material of the hub body. The ring can be manufactured in a first manufacturing step and can consist of, for example, continuous fibers wound or woven together with each other, or metal, or a combination thereof. Usually, the pedestal is inserted into respective slots of the mold before the ring and the attached rotor blade are overmolded. These slots allow for a setup where the rotor blade can be positioned accurately and rotationally symmetrically around the rotor axis before the pedestal is at least partially embedded in the matrix material.

[0022] Good results regarding the torsional stiffness design can be achieved when the rings are interconnected with the pedestals in a shape - fitting manner, for example, when provided with a plurality of grooves facing away from the rotor axis configured to receive at least one pedestal of the rotor blade. By arranging the pedestals within each groove of the ring, the resistance of the rotor blade to torsion with respect to the rotor axis under load is further increased, thus improving the stability of the rotor fan. Further, by arranging the pedestals within each groove of the ring, the rotor blade is positioned relative to the ring, for example, before the ring is embedded by overmolding.

[0023] To further strengthen the connection between the rotor blade and the hub, the pedestal can be provided with protrusions that engage with the recesses of the ring. This shape - fitting connection improves the connectivity between the rotor blade and the hub even under high pull - out forces. Each groove can be provided with at least one lateral recess that can receive the protrusion of one pedestal of the plurality of rotor blades. In a variant, the protrusion is spherical and can protrude laterally away from the pedestal between the leading edge and the trailing edge. The ring can be arranged inside and at the same time function as a bushing that enables the assembly of the rotor fan to each rotor shaft as described above and hereinafter. The blade body of the rotor blade can be bent between its respective leading edge and trailing edge. Further, the blade body can be bent between the top and the bottom of the portion of the blade body embedded in the hub body, thereby forming an undercut between each blade body and the hub body. This undercut can increase the resistance that prevents the blade body from being pulled out of the hub body under load.

[0024] To reduce the moment of inertia and thus the torque required for the desired angular acceleration of the rotor fan, the hub body can be optimized in terms of its shape. In a variant, the hub body comprises an outer flange portion, an inner flange portion, and a bridge connecting these two flange portions to each other. The outer flange portion can be designed to surround the pedestal of the blade body embedded in the blade body. The inner flange portion can be connected to the bushing. The bridge can be designed as an annular bead attached to the inner flange portion and connected to the outer flange portion.

[0025] By manufacturing the individual blade bodies of the rotor blade by embedding reinforcing fibers in the matrix material within the first mold, an efficient manufacturing process can be realized that enables mass production and thus a large quantity of production. As a variant, each blade body is manufactured within a single cavity of the mold. The reinforcing fibers are preferably arranged within the first mold half of the mold together with the matrix material before the second mold half is connected to the first mold half to form the cavity. The reinforcing fibers and the matrix material are usually connected to each other within the cavity by a hot pressing process. Alternatively, the reinforcing fibers are surrounded by placing the reinforcing fibers in the first mold and injecting the plasticized matrix material after the mold is closed. After the rotor blade has cured, the blade is removed from the mold and grouped with a number of additional rotor blades to form the outer contour of the rotor fan. The blade body and the pedestal interconnected therewith are usually integrally produced in a common molding process within the first mold. This has the advantage that interfaces can be avoided and stress concentration in the transition region between the blade body and the pedestal is avoided.

[0026] In a known assembly process for a rotor fan with rotor blades made of a metallic material, it is usually necessary to individually insert the rotor blades into the respective slots in the hub and fix them along the rotor axis. Compared with the presented method, a plurality of rotor blades can be arranged rotationally symmetrically with respect to the rotor axis within a second mold, and the pedestals of the rotor blades can be at least partially embedded in the composite material of the hub in one process step.

[0027] Preferably, the rotor fan is produced by a combination of two molding processes briefly described below. Individual rotor blades are produced within a first mold by placing continuous fibers and a matrix material within the cavity of the first mold, closing the cavity of the first mold and hot pressing the continuous fibers and the matrix material so as to surround the continuous fibers with the matrix material. If appropriate, at least one additional component can be placed within the cavity of the first mold together with the continuous fibers. The at least one additional component will later form part of the rotor blade, for example the leading edge, reinforcement means, or a combination thereof. After the matrix material has sufficiently cured, the rotor blade is removed from the first mold. The bottom of the pre-manufactured rotor blade is positioned in a corresponding recess adjacent to the cavity of the second mold in an open position such that the rotor blades are arranged rotationally symmetrically around the (virtual) rotor axis of the rotor fan to be manufactured. The cavity at least partially corresponds to the hub body of the rotor fan. The second mold is closed so that the bottom of the rotor blade is surrounded within the cavity of the second mold. The liquefied plastic material is pushed through an opening into the cavity of the second mold, thereby filling the voids in the cavity and surrounding the bottom of the rotor blade disposed within the cavity. The liquefied plastic material typically includes a matrix material and relatively short reinforcing fibers disposed therein. After the plastic material has cured, open the second mold and remove the assembled rotor fan. After curing, the reinforcing short fibers within the hub body are typically randomly arranged based on the flow of the material when it is distributed within the cavity during injection molding. Where appropriate, at least one additional component may be placed within the cavity of the second mold before the material is inserted. The at least one additional component that forms part of the rotor fan is, for example, an edge, a bushing, a ring, a reinforcing means, or a combination thereof. The additional component may be made of a composite material, such as in the case of at least a partially embedded reinforcing ring, or of metal or a combination thereof.

[0028] It is understood that both the foregoing general description and the following detailed description present embodiments and are intended to provide an overview or framework for understanding the nature and characteristics of the present disclosure. The accompanying drawings are included to enhance understanding and are incorporated herein and form a part thereof. The drawings illustrate various embodiments and, in conjunction with the detailed description, assist in explaining the principles and operations of the disclosed concepts.

Brief Description of the Drawings

[0029] The disclosure described herein will be more fully understood from the following detailed description of the specification and the accompanying drawings, but should not be considered as limiting the disclosure set forth in the appended claims. The drawings show the following content.

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

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Figure 11

Figure 12

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Figure 17

Figure 18

Mode for Carrying Out the Invention

[0031] Here, specific embodiments will be referred to in detail. Examples thereof are shown in the accompanying drawings, and not all features are shown in the drawings, but some features are shown. In fact, the embodiments disclosed herein can be embodied in many different forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure meets the legal requirements applicable thereto. As far as possible, the same reference numerals are used to refer to the same components or parts.

[0032] Figures 1 to 4 show a first variant of the rotor fan 1. The illustrated variant of the rotor fan 1 is designed for an aircraft. The illustrated rotor fan 1 typically consists of a plurality of rotor blades 2 arranged rotationally symmetrically with respect to the rotor shaft 3. The rotor blades 2 are made of a composite material containing reinforcing fibers 5 embedded in a matrix material 6. The blade body 4 typically extends in the longitudinal direction 7 between a bottom 8 and a top 9. Good results are obtained when the blade body 4 is made of a fiber-reinforced composite material.

[0033] As can be seen from Figure 3, the illustrated variant of the rotor fan 1 comprises a hub 13 with a hub body 14, and the hub body 14 is made of a composite material containing reinforcing fibers 5 embedded at least partially in a matrix material 6. The illustrated hub body 14 is designed as an annular sleeve and is typically manufactured by an injection molding process. The individual rotor blades 2 are usually interconnected to the hub 13 by a molding process. Usually, the pedestals 17 of the pre-manufactured rotor blades 2 are arranged in the open position within the mold so that the rotor blades 2 are arranged rotationally symmetrically around the central axis corresponding to the subsequent rotor shaft 3 of the manufactured rotor fan 1. To manufacture the hub body 14, a liquefied plastic material is pushed through an opening 33 into the cavity of the mold, thereby filling the voids in the cavity and surrounding the pedestals 17 of the rotor blades 2 arranged within the cavity.

[0034] The liquefied plastic material generally includes a matrix material 16 and relatively short reinforcing fibers 15 disposed therein. The illustrated rotor fan 1 includes a bushing 22 having a castellation 26. Thereby, the hub body 14 can be attached to the rotor shaft by frictional connection, and the castellation enables a strong interconnection, preventing circumferential peeling between the bushing 22 and the matrix material 16 due to the transmitted torque. Even under high loads or impacts from objects such as bird strikes in the air, the pedestal 17 can be interconnected with the hub body 14 by shape fitting to securely maintain the state where the rotor blade 2 is attached to the hub body 14. When the rotor blade 2 actually includes a pedestal 17 having a shape with an undercut 20 at its bottom, good results can be achieved regarding the stable interconnection between the blade body 4 and the hub body 14. The pedestal 17 can be designed as a basically rectangular block with a concave undercut 20.

[0035] As can be seen from FIG. 4, when the hub body 14 has a conical outer surface, good results are obtained regarding an aerodynamically favorable design. The outer surface is understood as a covering surface of the hub body 14 that surrounds the rotor shaft 3 and faces away from the rotor shaft 3. Depending on the design of the rotor shaft, the central opening 21 of the hub 13 can have a staggered design. To enable the assembly of the hub body 14 to each rotor shaft, the illustrated hub body 14 includes a bushing 22.

[0036] When the hub body 14 is shrink-fitted onto the rotor shaft, good results can be obtained. To enable the rapid and reliable manufacture of the hub body 14, the bushing 22 is typically overmolded together with the pedestal 17 of the rotor blade 2. The bushing 22 and the pedestal 17 of the rotor blade 2 are at least partially embedded in the composite material of the hub 13. To enable shrink fitting and force transmission between the hub body 14 and the rotor shaft, the hub body 14 is typically made of a material of either titanium, aluminum, steel, or a combination thereof. The reinforcing fibers 15 of the hub body 14 can be short fibers. The short fibers are typically in the range of 1 mm to 10 mm, preferably in the range of 3 mm to 5 mm. This enables the reinforcing fibers 15 to be mixed into the plasticized matrix material 16 and injected into the mold together with the matrix material 16.

[0037] To enable rapid manufacture and at the same time a structurally strong connection between the hub 13 and the rotor blade 2, the bottom 8 of each rotor blade 2 typically comprises a pedestal 17 that is at least partially embedded in the composite material of the hub 13. The pedestal 17 is typically attached to the hub body 14 by an adhesive, which may be provided by the matrix material 16 of the hub body 14. Typically, the hub body 14 is made by an injection molding process. To enhance the mechanical load-bearing capacity of the hub body 14 and thus the mechanical load-bearing capacity of the entire rotor fan 1, the hub body 14 is typically made of a composite material containing the reinforcing fibers 15.

[0038] Figures 5 to 6 show a first modification example of the rotor blade 2. The illustrated rotor blade 2 includes a composite material including continuous fibers 5 embedded in a matrix material 6 made of polyetheretherketone (PEEK). Depending on the design of the rotor blade 2, the blade body 4 can include a continuous fiber material. Alternatively, or additionally, the blade body 4 can also include a fiber fabric and / or a fiber scrim. In the transverse direction 10, the blade body 4 extends between a leading edge 11 and a trailing edge 12. To further enhance stability and wear resistance, the blade body 4 can be provided with a reinforced leading edge 11. The reinforcement of the leading edge 11 can be designed as a reinforcing element 24 in the form of an inlay applied on top of the fiber layer of the blade body 4 or between the fiber layers. The inlay can be made as a titanium insert or a bent sheet metal.

[0039] As can be seen from FIG. 7, the illustrated composite material of the blade body 4 includes a number of fiber layers 25 interconnected by three-dimensional or multi-layer weaving or stacking. In the transverse direction 10, the illustrated blade body 4 extends between a leading edge 11 and a trailing edge 12. The illustrated blade body 4 is provided with a reinforced tip. The reinforcement is designed as an inlay. In a modification example, the undercut 20 of the pedestal 17 can be designed as a recess extending transversely between the leading edge 11 and the trailing edge 12 of each rotor blade 2.

[0040] The recess can be designed as an essentially V-shaped channel. In a modification example where the hub body 14 has a conical outer surface, the pedestal 17 can be made wedge-shaped to achieve a smooth transition between the top surface of the pedestal 17 and the outer surface around the hub body 14. The top surface of the pedestal is understood as the surface facing the top 9 of the rotor blade 2. To achieve a smooth flow of energy from the hub body 14 to each rotor blade 2, the rotor blade 2 can be fused to a pedestal having a transition region that creates a smooth transition between the blade body 4 and the top surface of the pedestal 17.

[0041] Figures 8 and 9 show a first molding process for manufacturing the rotor blades of the rotor fan 1. The rotor fan 1 is typically manufactured by two consecutive molding processes. As can be seen from FIG. 8, the individual rotor blades 2 are manufactured within the first mold 27 by placing continuous reinforcing fibers 5 within the cavity of the first mold 27 formed by the first mold half 28 and the second mold half 29. The blade body 4 is produced by placing the reinforcing fibers 5 together with the matrix material 6 in the first mold 27 and hot pressing the reinforcing fibers 5 and the matrix material 6 so that the matrix material 6 is plasticized and surrounds the reinforcing fibers 5. Alternatively, after closing the cavity of the first mold 27, the continuous fibers 5 can be surrounded by the matrix material 6 and pushed into the closed cavity of the first mold 27 through the opening 33 in a plasticized state, for example, by an injection molding process. As can be best seen from FIG. 9, after the matrix material 6 has fully cured, each rotor blade 2 is removed from the first mold 27. If appropriate, at least one additional component can be placed within the cavity of the first mold 27 together with the continuous reinforcing fibers 5. The at least one additional component forms part of the rotor blade 2 later, for example, the leading edge 11, the reinforcing element 24, or a combination thereof.

[0042] Figure 10 shows a second molding process for manufacturing the rotor fan 1. The pedestal 17 of the previously manufactured rotor blade 2 is placed within the corresponding recess 34 adjacent to the cavity of the second mold 30. The recess 34 is arranged in the second mold 30 such that the rotor blade 2 is rotationally symmetrically arranged about the central axis corresponding to the rotor shaft 3 of the rotor fan 1 to be manufactured in the open position.

[0043] The cavity at least partially corresponds to the hub body 14 of the rotor fan 1. After closing the cavity of the second mold 30, the pedestal of the rotor blade is received within the cavity of the second mold 30 between the first mold half 31 and the second mold half 32. The liquefied matrix material is pushed through the opening 33 into the cavity of the second mold 30, thereby filling the voids of the cavity and surrounding the pedestal 17 of the rotor blade 2 disposed within the cavity. The matrix material 16 of the hub body 14 is typically made from a plastic material that is liquefied and that normally contains relatively short reinforcing fibers 15 within the material.

[0044] After the matrix material 16 has cured, the second mold 30 is opened and the assembled rotor fan 1 is removed. After curing, the reinforcing short fibers 16 within the hub body 14 are typically randomly arranged based on the flow of the material when it is distributed within the cavity during injection. If appropriate, at least one additional component may be disposed within the cavity of the second mold prior to the introduction of the material. The at least one additional component that forms part of the rotor fan 1 may be a bushing 22, a ring 18, a reinforcing element 24, or a combination thereof. The additional component may be made of a composite material, such as in the case of at least partially embedded reinforcing ring 18, or of metal, or a combination thereof.

[0045] Figure 11 shows a modified example of the rotor blade 2 provided with a Y-shaped pedestal 17. The illustrated Y-shaped pedestal 17 includes two legs that extend obliquely with respect to the longitudinal direction 7 and away from the bottom 8 of the blade body 4. With such a design, the reinforcing fibers 5 of the blade body 4 in the form of continuous fibers or fiber layers 25 can reach from the top 9 to the pedestal 17. The fiber layers of the two legs of the pedestal 17 are fused at the bottom 8 and can be stacked between the bottom 8 and the top 9. The reinforcing fibers 5 can reach parallelly from the bottom 8 to the top 9 within the blade body 4. The adhesive bonding between the pedestal 17 of the rotor blade 2 and the hub 13 is particularly essential because the connection may be damaged by the dynamic load of the rotor blade 2 and the resulting vibration and bending load, and as a result, the rotor blade 2 may be detached from the hub body 4. The Y-shaped configuration has proven to be preferable because it enables the reinforcing fibers 5 shown in the form of continuous fibers or fiber layers 25 to be well-aligned within the mold during the manufacturing process of the rotor blade 2. The Y-shaped pedestal is beneficial in guiding the lateral load and bending force to the hub body 14 when it is embedded in the hub body 14.

[0046] Figures 12 to 14 and Figure 18 show a second modified example of the rotor fan 1. Similar to the first modified example, the second modified example of the rotor fan 1 is also designed for aircraft use. The illustrated rotor fan 1 includes a plurality of rotor blades 2 arranged rotationally symmetrically with respect to the rotor shaft 3. The rotor blades 2 are made of a composite material including reinforcing fibers 5 embedded in a matrix material 6. The blade body 4 usually extends in the longitudinal direction 7 between the bottom 8 and the top 9, and the bottom 8 and the pedestal 17 interconnected therewith are partially embedded in the hub body 14.

[0047] As can be best seen from FIG. 13, the pedestals 17 of the blade body 4 each have a protrusion 37 that projects laterally away from the blade body 4 between the leading edge 11 and the trailing edge 12. During assembly, the pedestals 17 of the blade body 4 are arranged in the ring 18, as can be best seen from FIG. 14. The illustrated ring 18 has a plurality of grooves 35 facing away from the rotor shaft 3, and each groove is configured to receive a pedestal 17 of one of the plurality of rotor blades 2. When the pedestal 17 is arranged in each groove 35 of the ring 18, under load, the resistance of the rotor blade 2 against torsion with respect to the rotor shaft 3 further increases, thus improving the stability of the rotor fan 1. After the pedestal 17 of the rotor blade 2 is arranged in the ring 18 that can be integrated with the bushing 22, the pre-assembled rotor fan 1 is arranged in the mold and overmolded. As can be best seen from the partial cross-sectional views shown in FIGS. 15 and 18, the bottom 8, the pedestal 17 and the ring 18 are overmolded on the hub body 14 and at least partially embedded.

[0048] FIGS. 16 and 17 show a fourth variant of the rotor blade 2. In the mounted state, the illustrated variant of the rotor blade 2 is attached to the ring 18. The illustrated ring 18 has a plurality of grooves 35 facing away from the rotor shaft 3, and each groove is configured to receive a pedestal 17 of one of the plurality of rotor blades 2. The illustrated pedestal 17 has a protrusion 37 that engages with the recess 36 of the ring 18. This form-fitting connection improves the connectivity between the rotor blade 2 and the hub 13 even under high withdrawal forces. Each groove 35 may include at least one lateral recess 36 configured to receive the protrusion 37 of a pedestal 17 of one of the plurality of rotor blades 2. In the variant, the protrusion 37 is spherical and projects laterally away from the pedestal 17 between the leading edge 11 and the trailing edge 12.

[0049] FIG. 18 shows a second modified example of the rotor fan 1 in a perspective view from the front and above, and is a partially cut-away view. As can be best seen from the cut-away portion, the illustrated rotor blade 2 is bent between the leading edge 11 and the trailing edge 12. Further, the blade body 4 is also bent between the top portion 9 and the bottom portion 8 at the portion of the blade body 4 embedded in the hub body 14, thereby forming an undercut between the blade body 4 and the hub body 14. The undercut increases the resistance against the blade body 4 being pulled out from the hub body 14 under a loaded state.

[0050] It should be understood that the language used in this specification is for the purpose of description rather than limitation, and various changes can be made without departing from the essence and scope of the present disclosure.

Explanation of Reference Numerals

[0051] 1 Rotor fan 2 Rotor blade 3 Rotor shaft 4 Blade body (rotor blade) 5 Reinforcing fiber (blade body) 6 Matrix material (blade body) 7 Longitudinal direction (blade body) 8 Bottom portion 9 Top portion 10 Transverse direction (blade body) 11 Leading edge 12 Trailing edge 13 Hub 14 Hub body 15 Reinforcing fiber (hub body) 16 Matrix material (hub body) 17 Pedestal 18 Ring (hub body) 19 Outer surface 20 Undercut (pedestal) 21 Central opening (hub) 22 Bushing 23 Outer shell surface 24 Reinforcing element 25 Fiber layer 26 Castration 27 First mold 28 First mold half (first mold) 29 Second mold half (first mold) 30 Second mold 31 First mold half (second mold) 32 Second mold half (second mold) 33 Opening 34 Recess 35 Groove (ring) 36 Recess (ring) 37 Protrusion

Claims

Claim 1 An aircraft rotor fan (1), wherein the aircraft rotor fan (1) comprises: a. A plurality of rotor blades (2) arranged rotationally symmetrically around a rotor shaft (3), each of the rotor blades (2) being made of a composite material comprising reinforcing fibers (5) embedded in a matrix material (6), i. A blade body (4) extending in a longitudinal direction (7) between a bottom (8) and a top (9), and ii. A transverse direction (10) between a leading edge (11) and a trailing edge (12); and a plurality of rotor blades (2); b. A hub (13) comprising a hub body (13) at least partially made of a composite material comprising reinforcing fibers (14) embedded in a matrix material (15); comprising c. An aircraft rotor fan (1), wherein each bottom (8) of each of the rotor blades (2) comprises a pedestal (17) at least partially embedded in the composite material of the hub (13). Claim 2 The rotor fan (1) according to claim 1, wherein the pedestal (20) of the rotor blade (2) is attached to the hub body (14) by an adhesive. Claim 3 The rotor fan (1) according to claim 2, wherein the adhesive is provided by the matrix material (16) of the hub body (14). Claim 4 The rotor fan (1) according to any one of claims 1 to 3, wherein the pedestal (17) is interconnected with the hub body (14) by a form fit. Claim 5 The rotor fan (1) according to claim 4, wherein the hub body (14) comprises at least one ring (18) at least partially embedded in the composite material of the hub body (14), and the pedestal (17) is interconnected with the ring (18) by a form fit. Claim 6 The rotor fan (1) according to claim 5, wherein each of the rings (18) comprises a plurality of grooves (35) facing away from the rotor shaft (3) and each receiving a pedestal of one of the plurality of rotor blades (2). Claim 7 The rotor fan (1) according to claim 6, wherein each of the grooves (35) comprises at least one lateral recess (36) receiving at least one protrusion (37) of one of the pedestals (17) of the plurality of rotor blades (2). Claim 8 The rotor fan (1) according to claim 7, wherein the at least one protrusion (37) is spherical and protrudes laterally away from the pedestal (17) between the leading edge (11) and the trailing edge (12).

9. The rotor fan (1) according to any one of claims 1 to 8, wherein the blade body (4) includes continuous fibers arranged substantially parallel to the longitudinal direction (7) of the blade body (4).

10. The rotor fan (1) according to any one of claims 1 to 9, wherein the leading edge (11) of the blade body (4) is provided with a reinforcing element (24).

11. The rotor fan (1) according to any one of claims 1 to 10, wherein the composite material of the hub body (14) includes short fibers mixed in the matrix material (16).

12. The rotor fan (1) according to any one of claims 1 to 11, wherein the hub body (14) has a conical outer surface (19).

13. The rotor fan (1) according to any one of claims 1 to 12, wherein the central opening (21) of the hub (13) has a staggered design.

14. The rotor fan (1) according to any one of claims 1 to 13, wherein the hub (13) is provided with a bushing (22) having a castellated design on the outer shell surface (23).

15. The rotor fan (1) according to any one of claims 1 to 14, wherein the hub (13) is provided with a bushing (22) made of any one of the materials titanium, aluminum, steel or a combination thereof.

16. A method for manufacturing the rotor fan (1) according to at least one of claims 1 to 15, wherein the manufacturing method comprises: a. positioning the pedestal (17) of the prefabricated rotor blade (2) in a corresponding recess (34) adjacent to the cavity of a second mold (30) in an open position such that a plurality of rotor blades (2) are arranged rotationally symmetrically around the rotor shaft (3) of the rotor fan (2) to be manufactured; b. closing the second mold (30) such that the pedestal (17) of the rotor blade (2) is surrounded within the cavity of the second mold (30); c. Filling the voids in the cavity by pushing the liquefied matrix material (16) through the opening (33) into the cavity of the second mold (30), thereby surrounding the pedestal (17) of the rotor blade (2) disposed in the cavity; d. After the matrix material (16) has cured, opening the second mold (30) and removing the rotor fan (1); A method for manufacturing a rotor fan (1), comprising the steps of.

17. A method for manufacturing a rotor fan (1) according to claim 16, wherein reinforcing fibers (5) and a matrix material (6) are disposed in the cavity of a first mold (27), and the continuous fibers and the matrix material (6) are hot-pressed, whereby the plasticized matrix material surrounds the reinforcing fibers (5), and individual rotor blades (2) are manufactured within the first mold (27).

18. A method for manufacturing a rotor fan (1) according to claim 16, wherein reinforcing fibers (5) are disposed in the cavity of the first mold (27), and a plasticized matrix material (6) surrounding the reinforcing fibers (5) is injected into the mold, whereby individual rotor blades (2) are manufactured within the first mold (27).

19. A method for manufacturing a rotor fan (1) according to at least one of claims 16 to 18, wherein at least one additional component is disposed in the cavity of the second mold (30) before inserting the matrix material (16).

20. A method for manufacturing a rotor fan (1) according to at least one of claims 16 to 19, wherein the at least one additional component forming part of the rotor fan (1) is, for example, a bushing (22), a ring (18), a reinforcing element (24), or a combination thereof.

21. A method for manufacturing a rotor fan (1) according to at least one of claims 16 to 20, wherein the liquefied matrix material (16) of the hub (13) contains short reinforcing fibers (15) randomly disposed in the hub body (14) after curing.

22. A method for manufacturing a rotor fan (1) according to at least one of claims 16 to 21, wherein the blade body (4) and each pedestal (17) are integrally formed in a common molding process in the first mold.

23. The method for manufacturing a rotary fan (1) according to at least one of claims 16 to 22, wherein before the composite material of the hub (13) is overmolded, the ring (18) and the pedestal (17) interconnected with the ring (18) are arranged in the second mold.

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