This application claims priority from French Patent Application 1903585 filed Apr. 3, 2019, the entire content of which is incorporated by reference herein.
The invention relates to the assembly and disassembly of bleed lines supported by panels of a turbojet intermediate case.
A twin spool turbojet comprises an intake duct into which air enters drawn in by a fan, before being divided into a central core engine flow and a fan flow surrounding the core engine flow. After passing through the fan, the fan flow is directed in the aft direction to generate a thrust.
After passing through the fan, the core engine flow passes through a low pressure compressor and then a high pressure compressor before reaching a combustion chamber and is then expanded in a high pressure turbine and then in a low pressure turbine, before being expelled, generating an auxiliary thrust.
Each turbine and each compressor comprises blades supported by a rotor rotating about a longitudinal axis and supported by an intermediate case. This intermediate case comprises a hub fitted with external radial arms through which it is connected to an external case that surrounds it, and internal radial arms through which it supports an internal bearing.
The primary flow circulates in an annular space called the core flow stream, delimited internally by the rotor and externally by an inter-flow stream fairing of which the intermediate case forms part. The fan flow circulates in a different space called the fan flow stream, delimited internally by the inter-flow stream fairing and externally by the external case.
The intermediate case is fitted with bleed lines associated with bleed valves referred to as VBV (Variable Bleed Valves), that are open in some situations to evacuate air from the core engine flow to the fan flow, to avoid setting up a surging phenomenon due to overpressurisation of compressors that can damage them.
Due to maintenance constraints, the bleed lines must be easy to remove and reassemble, to facilitate access to components located in the region of the intermediate fairing, in other words located radially between the core engine flow stream and the fan flow stream.
The purpose of the invention is to provide a solution that simplifies removal and reassembly of these bleed lines.
To achieve this, the purpose of the invention is an intermediate turbojet case, comprising a hub that supports a shell formed from removable panels and bleed lines at an orientation that is oblique from a longitudinal axis, the hub comprising a flank provided with openings in the downstream part, each bleed line having an upstream end engaged in an opening in the flank and a downstream end terminated by a base plate through which the bleed line is fixed to an internal face of a removable panel by means of screws passing through this panel and screwed into the base, each removable panel having a front edge at which it is fixed to an external lip of the hub by means of screws that pass through this removable panel to be screwed into the hub, characterised in that at least one removable panel is equipped with an element retaining the base plate along the internal face during a phase in which the removable panel is fixed to the hub by screwing, this phase preceding attachment of the base plate to the internal face of the removable panel by screwing.
The invention thus makes it possible to preinstall bleed lines to facilitate final attachment by screws.
The invention also relates to an intermediate case thus defined, wherein at least one removable panel comprises a downstream edge, and in which the retaining element is supported by this downstream edge and extends along the internal face.
The invention also relates to an intermediate case thus defined, wherein the downstream edge extends perpendicular to the remaining part of the removable panel, and wherein the retaining element extends at a distance from the internal face of the removable panel.
The invention also relates to an intermediate case thus defined, wherein the retaining element is supported by the downstream edge and by the internal face, and wherein this retaining element is provided with a groove running along the internal face.
The invention also relates to an intermediate case thus defined, wherein the retaining element fitted on the removable panel is made of a elastomer material.
The invention also relates to an intermediate case thus defined, wherein the base plate is fitted with a spur engaging with the retaining element.
The invention also relates to a turbojet equipped with an intermediate case thus defined.
On
After passing through the fan 3, the core engine flow passes through a low pressure compressor 4 and then a high pressure compressor 6, to reach a combustion chamber 7 before being expanded in a high pressure turbine 8 and then in a low pressure turbine 9.
Each turbine and each compressor comprises blades supported by a rotor 11 rotating about a longitudinal axis AX and supported by an intermediate case 12. This intermediate case comprises a hub 13 fitted with external radial arms 14 through which it is connected to an external case 16 that surrounds it, and internal radial arms 17 through which it supports an internal bearing.
The primary flow circulates in an annular space called the core flow stream, delimited internally by the rotor 11 and externally by an inter-flow stream fairing 18 of which the intermediate case 12 forms part. The fan flow circulates in a different space called the fan flow stream, delimited internally by the inter-flow stream fairing 18 and externally by the external case 16.
As can be seen on
This intermediate case 12 supports several bleed lines 23 uniformly distributed about the AX axis and each having an orientation oblique to this axis. Each line 23 comprises an upstream end 24 engaged in a corresponding opening 26 in the flank 19 and a downstream end 27 fixed to an internal face of a removable panel 21, to open up through an opening 28 in this removable panel 21. The opening 26 formed in the flank 19 forms a seat for the upstream end of the line 23.
The general shape of each removable panel 21 is generally a portion of a cylinder. It comprises an external face 29 and an internal face 31 oriented towards the AX axis, these faces being marked on
As can be seen in more detail on
The upstream end 24 of the line 23 is engaged in the opening 26 but it is held in place by attachment of its downstream end 27 to the internal face of the panel 21 by means of screws 37 passing through this panel 21. These screws 37 are screwed into a base plate 38 terminating the downstream end 27 of the duct, these screws 37 having their heads located at the external face of the panel 21 and extending radially from the AX axis.
Taking account of the upstream border 32 that positions the panel 21 relative to the lip 22, it is impossible to fix firstly the downstream end 27 of the line to the panel 21 so that the assembly formed by the panel 21 supporting this line 23 can then be installed on the hub 13. In general, the panel and line installation operation is complicated by the fact that the access available to the operator is limited to the region adjacent to the external face of the removable panels.
It is possible to install the line 23 due to a retaining element 39 located at the downstream end of the panel 21, so that the downstream end 27 of the line 23 can be positioned relative to the panel 21, when the panel 21 is fixed to the hub 13, and before making the actual attachment of the downstream end 27 to this panel 21 using the attachment screw.
The retaining element 39 projects upstream from the downstream edge 33, which extends perpendicular to the internal face 31. This element 39 extends along the internal face 31 at a small distance from it so that a downstream edge of the base plate 38 can be engaged between the internal face 31 and the retaining element 39. The base plate 38 is thus prepositioned relative to the panel 21, and the line assembly is held pulled in the upstream direction when the panel is put into position.
The assembly is made by an operator who can access only the region R facing the external face 29 of the panel 21 downstream from the internal radial arms.
The assembly consists firstly of engaging the upstream end 24 of the line 23 in the opening 26 of the flank 19 of the hub 13, and then engaging the downstream edge of the base plate 38 between the element 39 and the internal face 31 of the panel 21. At this stage that corresponds to the situation in
The operator can then turn the upstream end of the panel 21 towards the X axis, to apply it in contact with the lip 22, so as to engage and tighten the screws 34 so as to completely fix the panel 21 on the hub 13. At this stage that corresponds to the situation in
The operator then simply needs to engage the screws 37 through the panel 21 to screw them into the corresponding threaded holes in the base plate 38, to as to completely fix the line 23 to the panel 21, which corresponds to the situation in
Disassembly of the panel 21 and the line 23 consists of performing similar actions but in the reverse order.
As can be seen more clearly on
The globally parallelepiped-shaped retaining element 39 can be an element made of an elastomer material fixed to the upstream face of the edge 33, to avoid damaging, in other words locally deteriorating the surface, of the base plate 38 during assembly operations.
In the second embodiment shown on
In the case of this third embodiment, the retaining element reference 39″, cooperates with a spur 42 supported by a base plate 38 to form a connection with this spur. More particularly, and as can be seen on
Additionally, and as can be seen on
In this third embodiment, fixation of the line 23 to the panel 21 consists of engaging the cylindrical spur 42 in the hole 45 by insertion. Once the assembly is in place, as can be seen on
In this third embodiment, the retaining element 39″ can also be made of an elastomer material so that the cylindrical spur 42 can then be engaged in the element 39″ by insertion following a displacement oriented parallel to the AX axis.
Number | Date | Country | Kind |
---|---|---|---|
1903585 | Apr 2019 | FR | national |
Number | Name | Date | Kind |
---|---|---|---|
20160039528 | Caruel | Feb 2016 | A1 |
20170273390 | Maloney | Sep 2017 | A1 |
20180080343 | Groleau | Mar 2018 | A1 |
Number | Date | Country |
---|---|---|
3018548 | Sep 2015 | FR |
3041380 | Mar 2017 | FR |
Entry |
---|
Preliminary Search Report issued in French Patent Application No. 1903585 dated Dec. 4, 2019. |
Number | Date | Country | |
---|---|---|---|
20200318494 A1 | Oct 2020 | US |