Support interface and device for an engine casing

The invention relates to the field of support interfaces, and in particular to such a support interface (30a, 30b) for an engine casing (90) and comprising a coupling part (50), a first plurality of bolts (80), and a plurality of pegs (70). The coupling part (50) has an outer face (52) presenting a cavity (42) suitable for receiving a support arm (20a, 20b), and an inner face (51) suitable for being mounted on an outer face (93) of the engine casing (90), together with a first plurality of orifices (53) between the outer face (52) and the inner face (51) of the coupling part (50). Each bolt (80) has a threaded shank (82) received in an orifice (53) of the first plurality of orifices (53), and a head (81) suitable for bearing against the outer face (52) of the coupling part (50). Each peg (70) has a threaded orifice (71) in which the threaded shank (82) of one of the bolts (80) of the first plurality of bolts (80) is engaged through a first end of the peg (70), each peg having a second end that is enlarged and suitable for bearing against an inner face (92) of the engine casing (90).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase entry under 35 U.S.C. § 371 of International Application No. PCT/FR2016/052341, filed on Sep. 15, 2016, which claims priority to French Patent Application No. 1558744, filed on Sep. 17, 2015, the entireties of each of which are herein incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a support interface. More particularly, the invention relates to a support interface for an engine casing, in particular for an aeroengine such as a turbojet or turbofan, and that is suitable for being used while the engine is being manufactured or maintained.

The invention also relates to a support device including such an interface, to an assembly comprising an engine casing and such a support device, and also to a method of mounting such an interface on an engine casing.

During engine assembly or handling, it is often necessary to hold the engine in a high position so as to give easier access to its various components. For that purpose, it is known to form at least two diametrically opposite cavities in the outer casing of an engine, and in particular of a turbine aeroengine, each of which cavities is to receive the end of a support arm secured to a frame. In order to hold the engine, a support arm is thus inserted into each cavity and is fastened to the casing, thereby holding the engine in a desired position.

With such a configuration, in order to ensure that each arm is well held, it is necessary for each cavity to present a working depth that is sufficient.

In order to obtain such a depth, the casing is generally provided with local extra thicknesses, also referred to as “bulges”, with the cavities for receiving the arms being machined therein.

Those extra thicknesses lead to a considerable increase in the weight of the engine. However, for manifest reasons of efficiency, it is desirable for the weight of the engine to be minimized, and in particular for it not to be impacted by parts that are not of any use while it is in operation.

In order to solve that problem, support interfaces have been proposed that comprise a coupling part with an outer face and an inner face, the outer face of the coupling part presenting a cavity suitable for receiving a support arm, and the inner face of the coupling part being suitable for being mounted on an outer face of the engine casing.

Nevertheless, although those prior art support interfaces make it possible, at least to some extent, to avoid the extra weight that would result from forming bulges directly on the engine casing, such support interfaces are relatively complicated to fasten compared to the engine casing and such fastening can require fastener means to be incorporated in the casing, thereby likewise making it heavier.

OBJECT AND SUMMARY OF THE INVENTION

The present disclosure relates to a support interface for an engine casing that makes it possible to further reduce the additional weight that the casing requires in order to be fastened, while also enabling fastening to be simpler and with accurate positioning on the engine casing. For this purpose, in at least one embodiment, the support interface comprises: a coupling part, a first plurality of bolts, and a plurality of pegs. The coupling part has an outer face presenting a cavity suitable for receiving a support arm, and an inner face suitable for being mounted on an outer face of the engine casing, together with a first plurality of orifices between its outer and inner faces. Each bolt of the first plurality of bolts has a threaded shank received in an orifice of the first plurality of orifices and a head suitable for bearing against the outer face of the coupling part, and each peg of the plurality of pegs has a threaded orifice in which the threaded shank of one of said bolts is engaged through a first end of the peg, each peg also having a second end that is enlarged and suitable for bearing against an inner face of the engine casing.

The pegs facilitate both positioning and fastening the coupling part to the engine casing by means of the bolts, without it being necessary for threaded orifices to be tapped directly in the engine casing or for use to be made of nuts, which could be difficult to access on the inner face of the engine casing.

In order to ensure reliable transmission of forces in at least one plane extending transversely to one of the bolts, at least one orifice of said first plurality of orifices may present an inside surface complementary to an outside surface of the first end of the corresponding peg. More specifically, at least two orifices of said first plurality of orifices may each present an axisymmetric inside surface that is complementary to an outside surface of the first end of the corresponding peg, so that together they form two sliding pivot type connections that co-operate to hold the support interface stationary in all directions relative to the casing.

Furthermore, in order to provide support that is more reliable, the coupling part may present a second plurality of orifices, each orifice of the second plurality of orifices being threaded and opening out in the outer face of the coupling part. The orifices of this second plurality can thus provide additional mechanical connection, in particular in traction, to a support arm having its end received in the cavity against the outer face of the coupling part, in particular in order to avoid any accidental exit of this end of the support arm from the cavity in which it is received.

The present disclosure also provides a support device comprising both a first support interface of the above-mentioned type and a first support arm connected to a frame and having one end received in the cavity of the coupling part of the first support interface. The interface and the support arm can thus provide a stable connection between the frame and the engine casing. In particular, the coupling part may present a second plurality of orifices, each orifice of the second plurality of orifices being threaded and opening out in the outer face of the support part, the device then further comprising a second plurality of bolts connecting the support arm to the coupling part through the threaded orifices of the second plurality of orifices, in particular for the purpose of avoiding any accidental exit of the support arm from the cavity in which it is received.

Furthermore, the support device may also include a second support interface of the same type together with a second arm connected to a frame and having one end received in the cavity of the coupling part of the second support interface.

The present disclosure also provides an assembly comprising at least one engine casing and a support interface of the above-mentioned type, wherein the pegs are received in orifices going from an inner face to an outer face of the engine casing, the pegs having enlarged second ends bearing against the inner face of the engine casing. In order to facilitate mounting this assembly the pegs may be received by being pressed into said orifices in the engine casing. Thus, mounting the pegs by pressing them in avoids them turning while the threaded shanks of the bolts in the first plurality are being engaged in the threaded orifices of the pegs, thereby facilitating that operation.

Finally, the present disclosure also provides a method of mounting a support interface of the above-mentioned type on an engine casing, the method comprising the following steps:

inserting each of the pegs as far as its enlarged second end from an inner face of the engine casing into the orifices going from an inner face to an outer face of the engine casing;

placing the coupling part with its inner face on the outer face of the engine casing and the orifices of the first plurality of orifices in alignment with the pegs; and

engaging the threaded shanks of the first plurality of bolts through the first plurality of orifices into the threaded orifices of the pegs in order to hold the coupling part stationary relative to the engine casing.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a support device100constituting an embodiment of the invention co-operating with an annular fan casing90of turbofan M. Nevertheless, such as support device100may be applied in analogous manner to any other type of engine having a casing.

In this example, the support device100comprises a frame28, two support arms20aand20bconnected to the frame and extending along respective horizontal longitudinal axes Xa and Xb, and two support interfaces30a,30beach provided with a reception cavity42for receiving one of the support arms20a,20b.

Each support interface30a,30bis thus for connecting the casing90to a support arm20a,20b. When in position mounted on the support device100, and as described in greater detail below, the casing90is thus supported by the arms20a,20b, via the two support interfaces30a,30b.

Movement means (not shown) enable each arm20a,20bto be moved, in particular along its longitudinal axis Xa, Xb.

As shown inFIG. 1, the support arms20a,20bare positioned substantially facing each other so as to leave between them sufficient space for receiving the engine casing90. In the example, the two support arms20aand20blie, more particularly, on the same axis.

In the example, each arm20a,20bhas a distal portion22of constant cylindrical section, in this example of circular profile, extending from its end.

At a distance from its distal end, each arm20a,20balso includes an outer collar24having fastener orifices26for a function that appears more clearly from the description below.

The first support interface30ais shown in greater detail inFIGS. 2A and 2B. As shown inFIGS. 2A and 2B, each support interface30a,30bcomprises a coupling part50and means for temporary assembly of the coupling part50on the casing90. In the example shown, the coupling part50has an inner face51, an outer face52in which the cavity42is formed, and a first plurality of orifices53passing from the inner face51to the outer face52, and the temporary assembly means comprise a plurality of pegs70together with a first plurality of bolts80. The second support interface30bis analogous to the first in all respects, having its cavity42arranged symmetrically relative to the cavity of the first support interface30a, although the geometrical configuration of the coupling part50and in particular of the orifices53therein could be different in order to match geometrical constraints that might differ on opposite sides of the casing90.

Each peg70has a threaded orifice71that opens out at a first end73of the peg70, and has an enlarged second end forming a collar72. Each peg70is permanently installed in a through orifice91in the casing90, with the collar72bearing against an inner face92of the casing90, and with the first end73projecting from an outer face93of the casing90. The pegs70are pressed into the orifices91so as to hold these pegs70both axially and against rotation relative to the casing90. Each bolt80has a head81and a threaded shank82. The heads81bear against the outer face52of the coupling part50, while the threaded shank82of each bolt80is complementary to the threaded orifice71in a corresponding peg70and is engaged in the threaded orifice71through a corresponding orifice53of said first plurality of orifices53in the coupling part50. For this purpose, the orifices53are in alignment with the pegs70and with the orifices91in the casing90in which the pegs70are installed.

The pegs70and the bolts80thus co-operate to hold the coupling part50axially with is inner face51pressed against an outer face93of the engine90. In the embodiment shown, each peg70has its projecting first end73in contact with an inner surface of the corresponding orifice53and thus takes up forces that are transverse relative to the axes of the bolts80. For this purpose, the inner surface of the orifice53and the outer surface at the first end73of the corresponding peg70are complementary. In particular, both of them may be axisymmetric, in particular they may be cylindrical or conical, so as to form a sliding pivot type connection. Such connections can thus suffice to hold an orifice part50stationary in all directions relative to the casing90.

Furthermore, the coupling part50also has a second plurality of orifices54arranged around the cavity42. These orifices54are threaded and in alignment with the fastener orifices26in the outer collars24of the arms20a,20b, so as to be capable of receiving through the fastener orifices26the threaded shanks of the bolts85connecting the outer collar24of the arms20a,20bto the coupling part50and taking up traction forces so as to avoid the ends of the arms20a,20baccidentally leaving the cavities42. There is no need for the bolts85to be screwed tight, and it may even be preferable to leave a certain amount of clearance between the heads of the bolts85and the outer collar24of the corresponding arms20a,20b.

A method of mounting the support device100is described with reference toFIGS. 3A to 3C. In a first step of the method, the pegs70are pressed into the orifices91in the casing90from the inner face92of the casing90. It should be specified that this step may be performed prior to assembling the casing90around the turbofan M, thereby facilitating access to the inner face92for the operation of inserting the pegs70.

In a second step, shown inFIG. 3B, the coupling part50is placed on the outer face93of the casing90, with the surfaces51a,51bof the inner face51of the coupling part50co-operating with the complementary surfaces93a,93bof the outer face93of the casing90, and the orifices53of the first plurality of orifices of the coupling part50being in alignment with the pegs70and the orifices receiving them.

Thereafter, in a third step, also shown inFIG. 3B, the threaded rods82of the bolts80are engaged in the threaded orifices71of the pegs70through the orifices53of the coupling part50and they are tightened to hold the coupling part50stationary relative to the casing90.

Once the coupling parts50are thus held stationary relative to the casing90so as to form the support interfaces30a,30b, it is possible to proceed to a fourth step, shown inFIG. 3C, in which each arm20a,20bis moved so as to be inserted into the corresponding cavity42. Finally, in a fifth step that is also shown inFIG. 3C, the threaded shanks of the bolts85are engaged in the threaded orifices54of each coupling part50through the fastener orifices26in the outer collar24of the corresponding arm20a,20bin order to retain each arm20a,20brelative to the corresponding coupling part50and thus avoid any accidental disengagement of the arms20a,20b. The bypass turbojet M can thus be supported by the frame28via the arms20a,20b, the support interfaces30a,30b, and the casing90.

Each of the second to fifth steps can be performed in reverse in the opposite order. Thus, if it is desired to separate the turbofan M from the frame28, the bolts85are withdrawn initially, and then the arms20a,20bare extracted from the corresponding cavities42. The bolts80and the coupling parts50can then be withdrawn so as to leave only the pegs70, which are permanently installed in the casing90in the orifices91.

Although the present invention is described with reference to a specific embodiment, it is clear that various modifications and changes may be undertaken on this embodiment without going beyond the general ambit of the invention as defined by the claims. Consequently, the description and the drawings should be considered in a sense that is illustrative rather than restrictive.