(19)
(11)EP 2 474 712 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
08.12.2021 Bulletin 2021/49

(21)Application number: 12150180.3

(22)Date of filing:  04.01.2012
(51)International Patent Classification (IPC): 
F01D 25/24(2006.01)
B29C 65/48(2006.01)
F01D 21/04(2006.01)
B29C 70/00(2006.01)
(52)Cooperative Patent Classification (CPC):
B29C 65/5057; B29C 65/4835; F01D 25/243; B29C 66/72141; B29C 65/56; B29C 65/5014; B29C 65/5042; B29C 66/532; B29C 70/86; B29C 66/742; B29C 66/00145; B29C 65/02; B29C 65/64; B29L 2031/3076; B29K 2705/00; B29C 65/5021; F05D 2300/603; F01D 21/045; B29C 66/7212; B29C 66/919; B29C 66/721; F01D 25/28; B29C 66/1122; Y10T 29/49245; B29C 66/91411; B29C 65/5064
 
C-Sets:
  1. B29C 66/7212, B29K 2307/04;
  2. B29C 66/7212, B29K 2309/08;


(54)

Attachment of threaded holes to composite fan case

Befestigung von Gewindebohrungen an einem Bläsergehäuse aus Verbundwerkstoff

Fixation de trous taraudés à un carter de soufflante composite


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 07.01.2011 US 986209

(43)Date of publication of application:
11.07.2012 Bulletin 2012/28

(73)Proprietor: Raytheon Technologies Corporation
Farmington, CT 06032 (US)

(72)Inventors:
  • Lussier, Darin S.
    Berlin, CT 06037 (US)
  • Robertson, Thomas J.
    Glastonbury, CT 06033 (US)

(74)Representative: Dehns 
St. Bride's House 10 Salisbury Square
London EC4Y 8JD
London EC4Y 8JD (GB)


(56)References cited: : 
EP-A2- 1 020 845
WO-A1-02/066235
JP-A- 2008 215 465
US-A- 4 446 185
US-A- 5 267 828
US-A1- 2009 010 755
EP-A2- 1 927 732
JP-A- 2007 168 397
US-A- 4 113 910
US-A- 5 079 055
US-A1- 2008 128 073
  
  • None
  
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


Description

BACKGROUND AND TECHNICAL FIELD



[0001] This application relates to creating threaded bolt holes in the outer periphery of a composite fan case for a gas turbine engine to provide mount locations for external components.

[0002] Gas turbine engines are known, and typically include a fan which delivers air toward a compressor. The air is compressed in the compressor, and passed downstream into a combustion chamber where it is mixed with fuel and burned. Products of this combustion pass downstream, driving turbine rotors to in turn drive a turbine shaft.

[0003] One recent development in turbine engines is a case for surrounding the fan rotor formed of a composite material, such as carbon epoxy.

[0004] While these fan cases have many desirable characteristics, one challenge is that components must be attached to the outer periphery of the case, typically through threaded fasteners. However, the material utilized to form the fan case has not been accommodating of bolt holes.

[0005] US 5,079,055 discloses a reinforcement member for a plastic laminate structure consisting of at least two laminate layers bonded to one another, the reinforcement member comprising a synthetic body formed of reinforcement fibers and adapted to be chemically bonded between the laminate layers of the structure. The reinforcement member defines a body of generally flattened frustoconical shape with a hole formed therethrough for receiving fastening means such as a bolt. A threaded metal insert member may be incorporated in the reinforcement member for receiving a threaded fastening. A composite fan case is disclosed in US 2008/0128073 A1. A composite reinforcement member is disclosed in US 4,113,910. A method of attaching acoustic panels to aircraft structures is shown in EP 1020845 A2.

SUMMARY



[0006] The present invention provides a composite fan case as recited in claim 1, and a method of attaching an accessory to the composite fan case as recited in claim 5.

BRIEF DESCRIPTION OF THE DRAWINGS



[0007] 

Figure 1A shows a gas turbine engine.

Figure 1B schematically shows a fan case according to the present invention.

Figure 1C shows a detail.

Figure 2A is a cross-sectional view through a connection as incorporated into this invention.

Figure 2B shows an insert.

Figure 2C is a view of a bolt attachment.

Figure 3A shows a first step in assembling the attachment.

Figure 3B is a cross-sectional view through the Figure 3A structure.

Figure 4 shows a subsequent step.

Figure 5 shows another subsequent step.

Figure 6 is a cross-sectional view through an attachment assembly showing an embodiment of the composite fan case according to the present invention.


DETAILED DESCRIPTION



[0008] A gas turbine engine 10, such as a turbofan gas turbine engine, circumferentially disposed about an engine centerline, or axial centerline axis 12 is shown in Figure 1A. The engine 10 includes a fan 14, compressor sections 15 and 16, a combustion section 18 and a turbine 19. A fan case 20 surrounds the fan 14. As is well known in the art, air from fan 14 is compressed in the compressor 15/16, mixed with fuel and burned in the combustion section 18 and expanded in turbine 19. The turbine 19 includes rotors 122 and 124, which rotate in response to the expansion. The turbine 19 comprises alternating rows of rotary airfoils or blades 126 and static airfoils or vanes 128. In fact, this view is quite schematic, and blades 126 and vanes 128 are actually removable. It should be understood that this view is included simply to provide a basic understanding of the sections in a gas turbine engine, and not to limit the invention. This invention extends to all types of turbine engines for all types of applications.

[0009] A composite fan case 20 is illustrated in Figure 1B. The fan case 20 is part of a gas turbine engine, and includes the fan rotor (see Figure 1A) delivering air downstream towards the compressor.

[0010] Threaded bolt attachments 22 are mounted on the outer surface of the fan case 20, in a manner to be described below. A component 24 is attached to the attachments 22, such as through pins 26 mounted at a bracket 28. The component 24 is shown as a holding bracket for a fluid tube. Any number of other components, and types of mountings may benefit from the present invention. The bracket 28 is threadably attached, such as by bolts 29 (see Figure 1C), to the attachment 22.

[0011] Figure 2A shows a detail of the attachment 22, which includes a molded conical "bathtub" or boss which is formed of a composite material 30. Of course, the bathtub or boss may be any number of different shapes including rectangular, square, oval, etc. Metallic inserts 32 are embedded within the composite material 30. A combination 34 of fiberglass plies and adhesive 36 are attached to the outer surface of the composite material 30. Another combination 38 of adhesive 36 and fiberglass plies 37 is formed on an inner surface of the composite material 30. This combination will be attached to the outer peripheral surface of the composite fan case 20, as will be described below. While fiberglass plies 37 are disclosed, it should be understood that other fiber reinforced plies, such as carbon fiber reinforced plies, would come within the scope of this invention.

[0012] The insert 32 has flat ends 40 and 42, which will prevent rotation within the composite material 30. The other ends 46 and 48 are generally conical. An extending cylindrical portion 44 extends upwardly to a hole 50, which will receive a threaded insert, as will be explained below. Any number of other anti-rotation features can be utilized, such as any number of flat surfaces from one to any higher number.

[0013] Figure 2C shows that there are two of the inserts 32 received within the composite material 30. The conical portion 46 faces a short circular end 54, while the composite material 30 has elongated sides 56. Flat ends 40 and 42 of insert 32 face these sides 56.

[0014] As shown in Figure 3A, in assembling the attachment 22, the inserts 32 are initially inserted into openings 60 within pre-molded composite material 30. They could additionally be molded within the material 30. An adhesive may be placed on the metallic insert, to secure the metallic insert within the opening 60. Weight reduction or strengthening opening 62 (see Figure 3B) may be formed within the composite material 30, as desired.

[0015] Figure 4 shows a subsequent step, wherein an adhesive layer, plurality of fiberglass plies 37, and an outer adhesive 36 are all attached to the composite fan case 20 at a bottom of the composite material 30. The upper combination 34 includes plurality plies 37 of fiberglass, with an adhesive layer 36 attached to the outer surface of the composite material 30.

[0016] Then, as shown in Figure 5, the attachment 22 then has holes 80 drilled through the outer fiberglass and adhesive combination 34 to align with holes 50, and which then receives inserts 82 which are threaded.

[0017] A helical insert or key-lock insert may be utilized as the inserts 82. Examples of brand names would be Helicoil or Keensert. Each of these inserts is threaded into the holes 50. In fact, the holes 50 can be formed with threads to receive the inserts. The point of the insert is generally to provide a breaking point which will break away from the attachment 22 prior to the attachment 22 breaking away from the fan case 20.

[0018] When the combined attachment 22 is placed on fan case 20, it is then heated and the fiberglass and adhesive cures, forming to the outer surface of the fan case 20, and is securely fastened.

[0019] Figure 6 shows a cross-section, with the threaded insert 82 received within the insert 32. Openings 62 are formed on each side of the insert 32. As can be appreciated from Figure 6, the upper combination 34 extends beyond the edges of the boss, such that there is an overlap area 100 where the upper combination 34 and the lower combination 38 are directly in contact.

[0020] In a sense, the upper ply combination 34 captures the composite material 30 and the insert 32, and holds it on the fan case. The underlying fiber reinforced ply and adhesive combination 38 holds the combination against the fan case. The areas beyond the material 30 where the upper and lower plies are in contact form a strong bond.

[0021] To attach the structure to the fan case, the plies, such as seen for example in Figure 2A, are placed on the outer surface of a fan case. A vacuum may be applied, and the material heated, such as to about 250° F (121° C). An oven may be utilized to provide this heating. In this manner, the fiber reinforced plies and adhesive cure on the outer surface, and should not break away.

[0022] In examples, the upper adhesive 36 and fiberglass combination 34 includes three plies of fiberglass with a single ply of adhesive in contact with the boss. The lower adhesive and fiberglass combination 38 may include a ply of adhesive 26, three plies of fiberglass 37, and then a ply of adhesive 36. Also, in examples, the boss composite material 30 may be injection molded plastic, SMC, or some other filled epoxy. Of course, other materials may be utilized, and other arrangements of the adhesive and fiberglass can also be utilized.

[0023] Although examples and embodiments of this invention have been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.


Claims

1. A composite fan case (20) of a gas turbine engine comprising:

a composite fan case body having a radially outer surface; and

at least one bolt attachment (22) attached to said radially outer surface of said fan case body, said bolt attachment (22) including an internal composite boss (30) having a plurality of metallic inserts (32), each metallic insert (32) having a hole (50) formed with threads to receive a threaded insert (82) to provide an internally threaded opening, and said boss (30) being attached to said radially outer surface of said body with a radially inner combination (38) of at least one fiber reinforced ply (37) and adhesive (36), wherein a radially outer combination (34) of adhesive (36) and fiber reinforced plies (37) is applied to a radially outer surface of said boss (30), and wherein said at least one bolt attachment (22) is configured to receive threaded fasteners (29) to attach an accessory (24) to the bolt attachment (22).


 
2. The composite fan case (20) as set forth in claim 1, wherein said radially inner combination (38) of at least one fiber reinforced ply (37) and adhesive (36) which attaches said boss (30) to said body (20), and said radially outer combination (34) of adhesive (36) and fiber reinforced plies (37) applied to the radially outer surface of said boss (30) each extend beyond the edges of said boss (30), and are in contact with each other at a location (100) beyond the edges of said boss (30).
 
3. A gas turbine engine comprising the composite fan case (20) of claim 1 or 2.
 
4. The gas turbine engine as set forth in claim 3, further comprising an accessory (24), and threaded fasteners (29) received by said at least one bolt attachment (22), the accessory (24) attached to said at least one bolt attachment (22) of said composite fan case (20) by the threaded fasteners (29).
 
5. A method of attaching an accessory (24) to a composite fan case (20) as claimed in claim 1 or 2, the method comprising the steps of:

placing the radially inner combination (38) of at least one fiber reinforced ply (37) and adhesive (36) at the radially inner side of the composite boss (30);

placing the radially outer combination (34) of adhesive (36) and fiber reinforced plies (37) on the radially outer surface of said composite boss (30);

attaching the bolt attachment (22) to the radially outer surface of the composite fan case (20) by heating and curing the fiber reinforced ply (37) and adhesive (36) combinations (34, 38); and

attaching the accessory (24) to the threaded openings of the inserts.


 
6. The method as set forth in claim 5, wherein said radially outer combination (34) of adhesive (36) and fiber reinforced plies (37) on the radially outer surface of said composite boss (30) extends beyond the edges of the boss (30), and has a portion in contact with said fiber reinforced ply (37) and adhesive (36) combination (38) that is placed at the radially inner side of said boss (30).
 
7. The method as set forth in claim 5 or 6, including the step of attaching a single accessory (24) to said threaded inserts (82) by threaded fasteners (29).
 


Ansprüche

1. Verbundwerkstoff-Fangehäuse (20) eines Gasturbinentriebwerks, umfassend:

einen Verbundwerkstoff-Fangehäusekörper, der eine radial äußere Fläche aufweist; und

mindestens eine Bolzenbefestigung (22), die an der radial äußeren Fläche des Fangehäusekörpers angebracht ist, wobei die Bolzenbefestigung (22) einen inneren Verbundwerkstoff-Wulst (30) beinhaltet, der eine Vielzahl von metallischen Einsätzen (32) aufweist, wobei jeder metallische Einsatz (32) ein Loch (50) aufweist, das mit Gewindegängen ausgebildet ist, um einen Gewindeeinsatz (82) aufzunehmen, um eine mit Innengewinde versehene Öffnung bereitzustellen, und wobei der Wulst (30) an der radial äußeren Fläche des Körpers mit einer radial inneren Kombination (38) aus mindestens einer faserverstärkten Lage (37) und Klebemittel (36) angebracht ist, wobei eine radial äußere Kombination (34) aus Klebemittel (36) und faserverstärkten Lagen (37) auf eine radial äußere Fläche der Wulst (30) aufgebracht ist, und wobei die mindestens eine Bolzenbefestigung (22) so konfiguriert ist, dass sie mit Gewinde versehene Befestigungsmittel (29) aufnimmt, um ein Zubehörteil (24) an der Bolzenbefestigung (22) zu befestigen.


 
2. Verbundwerkstoff-Fangehäuse (20) nach Anspruch 1, wobei die radial innere Kombination (38) aus mindestens einer faserverstärkten Lage (37) und Klebemittel (36), die den Wulst (30) an dem Körper (20) befestigt, und die radial äußere Kombination (34) aus Klebemittel (36) und faserverstärkten Lagen (37), die auf die radial äußere Fläche des Wulsts (30) aufgebracht ist, sich jeweils über die Kanten des Wulsts (30) hinaus erstrecken und an einer Stelle (100) jenseits der Kanten des Wulst (30) miteinander in Kontakt sind.
 
3. Gasturbinentriebwerk, das Verbundwerkstoff-Fangehäuse (20) nach Anspruch 1 oder 2 umfassend.
 
4. Gasturbinentriebwerk nach Anspruch 3, ferner ein Zubehörteil (24) und mit Gewinde versehene Befestigungsmittel (29), die von der mindestens einen Bolzenbefestigung (22) aufgenommen sind, umfassend, wobei das Zubehörteil (24) an der mindestens einen Bolzenbefestigung (22) des Verbundwerkstoff-Fangehäuses (20) durch die mit Gewinde versehenen Befestigungsmittel (29) angebracht ist.
 
5. Verfahren zum Befestigen eines Zubehörteils (24) an einem Verbundwerkstoff-Fangehäuse (20) nach Anspruch 1 oder 2, wobei das Verfahren die folgenden Schritte umfasst:

Anordnen der radial inneren Kombination (38) aus mindestens einer faserverstärkten Lage (37) und Klebemittel (36) an der radial inneren Seite des Verbundwerkstoff-Wulsts (30);

Anordnen der radial äußeren Kombination (34) aus Klebemittel (36) und faserverstärkter Lagen (37) an der radial äußeren Fläche des Verbundwerkstoff-Wulsts (30);

Befestigen der Bolzenbefestigung (22) an der radial äußeren Fläche des Verbundwerkstoff-Fangehäuses (20) durch Erwärmen und Aushärten der Kombinationen (34, 38) aus faserverstärkter Lage (37) und Klebemittel (36); und

Befestigen des Zubehörteils (24) an den mit Gewinde versehenen Öffnungen der Einsätze.


 
6. Verfahren nach Anspruch 5, wobei sich die radial äußere Kombination (34) aus Klebemittel (36) und faserverstärkten Lagen (37) an der radial äußeren Fläche des Verbundwerkstoff-Wulsts (30) über die Kanten des Wulsts (30) hinaus erstreckt und einen Abschnitt aufweist, der in Kontakt mit der Kombination (38) aus faserverstärkter Lage (37) und Klebemittel (36), die an der radial inneren Seite des Wulsts (30) angeordnet ist, ist.
 
7. Verfahren nach Anspruch 5 oder 6, den Schritt des Befestigens eines einzelnen Zubehörteils (24) an den mit Gewinde versehenen Einsätzen (82) durch mit Gewinde versehene Befestigungsmittel (29) beinhaltend.
 


Revendications

1. Carter de soufflante composite (20) d'un moteur à turbine à gaz comprenant :

un corps de carter de soufflante composite ayant une surface radialement externe ; et

au moins une fixation à boulon (22) fixée à ladite surface radialement externe dudit corps de carter de soufflante, ladite fixation à boulon (22) comportant un bossage composite interne (30) ayant une pluralité d'inserts métalliques (32), chaque insert métallique (32) ayant un trou (50) formé avec des filetages pour recevoir un insert taraudé (82) pour fournir une ouverture taraudée intérieurement, et ledit bossage (30) étant fixé à ladite surface radialement externe dudit corps avec une combinaison radialement interne (38) d'au moins une couche renforcée de fibres (37) et d'adhésif (36), dans lequel une combinaison radialement externe (34) d'adhésif (36) et de couches renforcées de fibres (37) est appliquée sur une surface radialement externe dudit bossage (30), et dans lequel au moins une fixation à boulon (22) est configurée pour recevoir des attaches taraudées (29) pour fixer un accessoire (24) à la fixation à boulon (22).


 
2. Carter de soufflante composite (20) selon la revendication 1, dans lequel ladite combinaison radialement interne (38) d'au moins une couche renforcée de fibres (37) et d'adhésif (36) qui fixe ledit bossage (30) audit corps (20), et ladite combinaison radialement externe (34) d'adhésif (36) et de couches renforcées de fibres (37) appliquée à la surface radialement externe dudit bossage (30) s'étendent chacune au-delà des bords dudit bossage (30), et sont en contact l'une avec l'autre au niveau d'un emplacement (100) au-delà des bords dudit bossage (30).
 
3. Moteur à turbine à gaz comprenant le carter de soufflante composite (20) selon la revendication 1 ou 2.
 
4. Moteur à turbine à gaz selon la revendication 3, comprenant en outre un accessoire (24) et des attaches taraudées (29) reçues par ladite au moins une fixation à boulon (22), l'accessoire (24) étant fixé à ladite fixation à boulon (22) dudit carter de soufflante composite (20) par les attaches taraudées (29).
 
5. Procédé de fixation d'un accessoire (24) à un carter de soufflante composite (20) selon la revendication 1 ou 2, le procédé comprenant les étapes :

de placement de la combinaison radialement interne (38) d'au moins une couche renforcée de fibres (37) et d'adhésif (36) sur le côté radialement interne du bossage composite (30) ;

de placement de la combinaison radialement externe (34) d'adhésif (36) et de couches renforcées de fibres (37) sur la surface radialement externe dudit bossage composite (30) ;

de fixation de la fixation à boulon (22) à la surface radialement externe du carter de soufflante composite (20) en chauffant et en durcissant les combinaisons (34, 38) de couche renforcée de fibres (37) et d'adhésif (36) ; et

la fixation de l'accessoire (24) aux ouvertures taraudées des inserts.


 
6. Procédé selon la revendication 5, dans lequel ladite combinaison radialement externe (34) d'adhésif (36) et de couches renforcées de fibres (37) sur la surface radialement externe dudit bossage composite (30) s'étend au-delà des bords du bossage (30), et a une partie en contact avec ladite combinaison (38) de couche renforcée de fibres (37) et d'adhésif (36) qui est placée du côté radialement interne dudit bossage (30) .
 
7. Procédé selon la revendication 5 ou 6, comportant l'étape de fixation d'un seul accessoire (24) auxdits inserts taraudés (82) par des attaches taraudées (29).
 




Drawing




















Cited references

REFERENCES CITED IN THE DESCRIPTION



This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description