BURST PROTECTION DEVICE FOR AN AVIATION FAN OR COMPRESSOR

Description

Technical field of the invention

[0001] The present invention relates to a device for producing a fan or compressor, in particular for the aeronautical industry, this device comprising in particular an annular casing and a bladed wheel mounted inside this casing. Technical background

[0002] The technical background includes, in particular, documents US-A1-5,431,532, US-A1-2011 / 0052383, US-A1-4,902,201, JP-2006177364A and US-A1-2019 / 0106996A1.

[0003] A fan or compressor for the aeronautical industry comprises an assembly comprising a casing and a bladed wheel, this assembly being called a “device” in the context of the present invention.

[0004] There figure 1 shows a device 10 of this type, the casing being designated by the reference 12 and the bladed wheel by the reference 14.

[0005] The casing 12 of this device 10 has an annular shape defining an internal vein for circulation of a gas flow (arrows F).

[0006] This gas flow is intended to be accelerated or compressed by the bladed wheel 14 which is mounted inside the casing 12 and which has an axis of rotation A coincident with the main or revolution axis of the casing.

[0007] In some applications, the bladed wheel 14 can reach high rotational speeds, for example between 2,000 and 40,000 rpm. In the event of a mechanical problem or impact of foreign bodies on the bladed wheel 14, this wheel can break and the breakage of the wheel generates debris. At high speed, this debris can pierce the casing 12. It is important to identify a solution to stop the trajectory of this debris and prevent it from reaching, for example, a passenger cabin of an aircraft equipped with the fan or the compressor.

[0008] The present invention makes it possible to remedy this problem thanks to a simple, effective and economical solution. Summary of the invention

[0009] The present invention provides a fan or compressor, according to claim 1, in particular for the aeronautical industry, this fan or this compressor comprising a device comprising: an annular casing comprising a main axis and defining an internal vein for circulating a flow of gas along this axis, a bladed wheel mounted inside the casing and having an axis of rotation coinciding with the axis of the casing, the fan or compressor further comprising a debris retention system in the event of breakage of the bladed wheel, this system comprising a retaining ring which is mounted around the casing, the casing comprising two annular bosses projecting radially outwards which are located respectively upstream and downstream of the bladed wheel and on which are applied and fixed upstream and downstream edges of the retaining ring, and characterized in that the upstream and downstream edges of the retaining ring comprise orifices which are aligned with tapped holes in the bosses for mounting fixing elements, such as screws or rivets.

[0010] The debris retention system ensures that debris generated by the bladed impeller breaking is prevented from exiting the device. In the event of a break, debris from the impeller is likely to pass through the casing. The impeller is located between the bosses of the casing, so the debris passes through the casing between the bosses, due to the centrifugal forces applied to the impeller during operation. The bosses ensure the fixation of the retaining ring around the casing but also have the function of channeling the debris, after passing through the casing, to the retaining ring. The debris will then reach the retaining ring, which is intended to block the debris and absorb the energy linked to the impact, for example by deforming. The debris is therefore not expelled outside the device.

[0011] The fan or compressor according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: the casing comprises, between the two bosses and around the bladed wheel, a tubular wall having a constant radial thickness; the tubular wall comprises free and bare internal and external cylindrical surfaces; the casing is made of metal or composite material, and / or the retaining ring is made of metal or composite material; the upstream and downstream edges of the retaining ring are bonded to the bosses; the retaining ring is continuous over 360° or is formed by winding a strip of material whose circumferential ends overlap; the bladed wheel has an external diameter less than or equal to 1 meter, and preferably less than or equal to 60 centimeters; the bosses each have an axial dimension representing between 5 and 30% of a maximum axial dimension of the bladed wheel; the bosses each have a radial dimension representing between 200% to 1000% of a radial thickness of the casing between the bosses;and the retaining ring has a radial thickness of between 1 and 5 mm.;

[0012] The present invention also relates to a fan or compressor, in particular for an aeronautical application, comprising at least one device as described above. Brief description of the figures

[0013] The invention will be better understood and other details, characteristics and advantages of the invention will appear on reading the following description given by way of non-limiting example with reference to the appended drawings, in which: [ Fig. 1 ] there figure 1 is a schematic perspective view in partial section of a device for a fan or a compressor, this device comprising a casing and a bladed wheel; [ Fig.2 ] there figure 2 is a schematic axial sectional view of a device according to the invention, this device comprising a casing and a debris retention system; [ Fig.3 ] there figure 3 is a schematic perspective view of a housing and debris retention system for a device according to the invention; [ Fig.4 ] there figure 4 is a schematic axial sectional view of the device and system of the figure 3 ; [ Fig.5 ] there Figure 5 is a partial schematic in perspective of the casing of the figure 2 ; [ Fig.6 ] there figure 6 is a schematic perspective and axial sectional view of a device according to the invention; [ Fig.7 ] there figure 7 is a schematic perspective view of a retaining ring for a device according to the invention; and [ Fig.8 ] there figure 8 is a partial schematic perspective view of the ring of the figure 7 . Detailed description of the invention

[0014] There figure 1 has been described in the above.

[0015] THE figures 2and following illustrate the present invention which relates to a device 10 for producing a fan or compressor, in particular for the aeronautical industry, this device comprising: an annular casing 12 comprising a main axis A and defining an internal vein for circulation of a gas flow along this axis A, a bladed wheel 14 mounted inside the casing and having an axis of rotation coinciding with the axis A of the casing 12.

[0016] The casing 12 has a generally tubular shape along the axis A. In the example shown, it has a straight shape but could alternatively have a bent shape. The casing 12 comprises an internal annular surface 12a, here cylindrical, and an external annular surface 12b, here also cylindrical.

[0017] The bladed wheel 14 is very schematically represented in the figure 2 and is not shown in the following figures. As seen in the figure 1, this bladed wheel 14 may comprise a hub 14a centered on the axis A and blades 14b regularly distributed around the axis A and extending radially outwards from the outer periphery of the hub 14a. The bladed wheel 14 is driven in rotation by a shaft which is centered on the axis A and which is not shown in the drawings.

[0018] The bladed wheel 14 is schematically represented by a rectangle at the figure 2 . This wheel 14 has an axial length or dimension noted L1.

[0019] The bladed wheel 14 has an external diameter R1 less than or equal to 1 meter, and preferably less than or equal to 60 centimeters. The application of the invention is therefore essentially aimed at fans and compressors of relatively small size (for the aeronautical industry).

[0020] The device 10 according to the invention further comprises a system 18 for retaining debris in the event of breakage of the bladed wheel 14.

[0021] This system 18 comprises a retaining ring 20 which is mounted around the casing 12. For this, the casing 12 comprises two annular bosses 22 projecting radially outwards, in particular on the surface 12b, which are located respectively upstream and downstream of the bladed wheel 14. This means that there is a first boss 22 upstream of a transverse plane passing through the upstream end of the bladed wheel 14, for example at the leading edges of its blades 14b, and a second boss 22 downstream of another transverse plane passing through the downstream end of the bladed wheel 14, for example at the trailing edges of its blades 14b. This also means that the axial distance D1 between these bosses 22 is greater than the length L1.

[0022] Each of these bosses 22 has a generally square or rectangular axial section. Each boss 22 has an axial length or dimension L2 and a radial thickness or dimension R2. The two bosses 22 are identical here.

[0023] L2 preferably represents between 5 and 30% of L1.

[0024] Each boss 22 comprises an external cylindrical surface 22a and radial lateral surfaces 22b (cf. figure 6 ). The bosses 22 define between them an annular space E which is empty in the example shown. The bosses 22 are connected to each other by a tubular wall 12c of the casing 12 which has a constant thickness E3 over its entire axial extent. Preferably, the tubular wall 12a comprises free and bare internal 12ca and external 12cb cylindrical surfaces. In other words, this wall 12c is devoid of local excess thickness and in particular of stiffening ribs.

[0025] R2 preferably represents between 200% and 1000% of E3.

[0026] The retaining ring 20 extends around the bosses 22 and comprises an upstream edge 20a which covers the upstream boss 22 and in particular its surface 22a, and is fixed to this upstream boss. The ring 20 comprises a downstream edge 20b which covers the downstream boss 22 and in particular its surface 22a, and is fixed to this downstream boss.

[0027] The ring 20 has a generally cylindrical and tubular shape and may have a constant thickness E4 over its entire axial dimension. This thickness E4 is for example between 1 and 5 mm.

[0028] In the examples shown in figures 3 to 6 , the upstream 20a and downstream 20b edges of the ring 20 comprise orifices which are aligned with tapped holes 24 of the bosses 22 for mounting fixing elements 26, such as screws or rivets.

[0029] Alternatively or additionally, the upstream and downstream edges 20a, 20b of the ring 20 can be glued to the bosses 22.

[0030] The ring 20 closes the space E and has the function of ensuring the retention of debris in the event of breakage of the wheel 14, as will be explained in more detail below.

[0031] The casing 12 is preferably made of metal but could alternatively be made of composite material, for example, filled plastic. The retaining ring 20 is preferably made of metal but could alternatively be made of composite material. In a preferred embodiment of the invention, the ring 20 is made of austenitic stainless steel, such as 304L or 316L steel. This type of steel has the advantage of having a relatively high elongation rate.

[0032] As can be seen in the figures 7 And 8, the retaining ring 20 may be continuous over 360° or may be formed by winding a strip of material whose circumferential ends 20a overlap. These ends may undergo a grooving operation.

[0033] The debris retention system 18 ensures that debris generated by the breakage of the bladed wheel 14 is prevented from exiting the device 10. In the event of breakage, debris from the wheel 14 is likely to pass through the casing 12. The wheel 14 is located between the bosses 22 of the casing, so the debris will pass through the casing between the bosses 22, due to the centrifugal forces applied to the wheel 14 in operation. The bosses 22 ensure the attachment of the retaining ring 20 around the casing 12 but also have the function of channeling the debris, after passing through the casing 12, to the retaining ring 20. The debris will then reach the retaining ring 20, the purpose of which is to block the debris and absorb the energy linked to the impact, for example by deforming. The debris is thus not expelled outside the device 10.

Claims

1. A fan or compressor, in particular for the aeronautical industry, this fan or this compressor comprising a device comprising: - an annular casing (12) comprising a main axis (A) and defining an internal flow duct for a gas flow along this axis, - a bladed wheel (14) mounted inside the casing (12) and having an axis of rotation coincident with the axis (A) of the casing, the fan or compressor further comprising a system (18) for retaining debris in the event of breakage of the bladed wheel (14), this system comprising a retaining annulus (20) which is mounted around the casing (12), the casing (12) comprising two radially outwardly projecting annular bosses (22) which are located respectively upstream and downstream of the bladed wheel (14) and to which upstream and downstream edges (20a, 20b) of the retaining annulus (20) are applied and attached, and characterized in that the upstream (20a) and downstream (20b) edges of the retaining annulus (20) comprise orifices that are aligned with threaded holes (24) of the bosses (22) for mounting attachment elements (26), such as screws or rivets.

2. The fan or compressor of claim 1, wherein the casing (12) comprises, between the two bosses (22) and around the bladed wheel (14), a tubular wall (12c) having a constant radial thickness (E3).

3. The fan or compressor of claim 2, wherein the tubular wall (12c) comprises free and bare internal (12ca) and external (12cb) cylindrical surfaces.

4. The fan or compressor according to any of the preceding claims, wherein the casing (12) is made of metal or composite material, and / or the retaining annulus (20) is made of metal or composite material.

5. The fan or compressor of any of claims 1 to 4, wherein the upstream (20a) and downstream (20b) edges of the retaining annulus (20) are further bonded to the bosses (22).

6. The fan or compressor of any of the preceding claims, wherein the retaining annulus (20) is continuous through 360° or is formed by winding a strip of material with overlapping circumferential ends.

7. The fan or compressor of any of the preceding claims, wherein the bladed wheel has an external diameter of less than or equal to 1 meter.

8. The fan or compressor of any of the preceding claims, wherein the bosses (22) each have an axial dimension (L2) representing between 5 and 30% of a maximum axial dimension (L1) of the bladed wheel (14).

9. The fan or compressor of any of the preceding claims, wherein the bosses (22) each have a radial dimension (R2) of between 200% and 1000% of a radial thickness (E3) of the casing (14) between the bosses (22).

10. The fan or compressor of any of the preceding claims, wherein the retaining annulus has a radial thickness between 1 and 5 mm.