Intermediate bearing with oil return for radial drive shaft

Abstract

The invention relates to an accessory drive assembly (1) for an aircraft turbine engine, which accessory drive assembly (1) comprises a radial drive shaft (2) with a longitudinal axis (A) and a gearbox (3). The radial drive shaft (2) is mounted in a rotating manner in an intermediate bearing that has a first flared portion (4') and a second flared portion located opposite the first, the two flared portions defining a hollow space (5) between them where oil circulates. The first flared portion (4') has a cylindrical housing (6) communicating with the hollow space (5) and extending along the longitudinal axis (A) so as to house the radial drive shaft (2). It also has an oil circulation pipe (9) that has an inlet port (10) which opens into the hollow space (5) and an outlet port which communicates with a device for treating, storing or using oil.

Description

Intermediate bearing with oil return for radial drive shaft TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of aircraft turbomachinery, and more particularly that of accessory drive assemblies for aircraft turbomachinery.

[0002] The present invention relates to a new intermediate bearing for an accessory drive assembly for an aircraft turbomachine. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] In a turbomachine, the energy from the exhaust gases is converted into mechanical energy to drive a compressor, accessories, and possibly a receiver. The accessories may be necessary for the operation of the turbomachine or other auxiliary devices. The accessory drive is achieved by a device known as the accessory drive assembly, which takes the motion from a reduction gear or the shaft connecting the turbine to the compressor. This accessory drive assembly typically includes a radial drive shaft, also known as an RDS (Radial Drive Shaft), and a gearbox, for example, mounted on an intermediate casing.

[0004] The radial drive shaft is typically a cylindrical shaft that connects the low-pressure compressor shaft, located at an intermediate housing hub, to the gearbox. It starts the turbomachine by transmitting torque from the gearbox to the low-pressure shaft, thus rotating the low-pressure compressor. It also transmits power between the low-pressure compressor and the operating gearbox.

[0005] The radial drive shaft is usually a single piece received in a cylindrical housing designated as the RDS hole and provided within a support arm designated as the RDS arm. The support arm is a structural component of the secondary flow, which absorbs mechanical stresses and is usually located between the intermediate housing shell and the intermediate housing hub. Given Its positioning in the secondary flow also gives this part an aerodynamic function to direct the airflow in the turbomachine.

[0006] Due to vibration issues with the radial drive shaft, it may come into contact with the cylindrical housing of the support arm, causing wear on the parts. An intermediate bearing, such as a ball bearing, can therefore be mounted on the radial drive shaft to limit these vibrations.

[0007] In some modern turbomachinery, the radial drive shaft is in two parts. It comprises a primary shaft, for example, connected to the intermediate housing hub, and a secondary shaft, for example, connected to the gearbox. In this case, the provision of an intermediate bearing further limits the deflection of the radial drive shaft. The intermediate bearing is preferably located at the junction between the primary and secondary shafts, for example, approximately in the middle of the radial drive shaft.

[0008] Like all bearings, the intermediate bearing is lubricated by circulating engine oil, in particular to reduce friction between the radial drive shaft and the surrounding structure of the intermediate bearing.

[0009] However, due to the rotation of the radial drive shaft, this oil heats up through friction. Therefore, the oil needs to be cooled to maintain its lubricating properties. Metallic particles are also likely to contaminate this oil, which must then be drained and filtered.

[0010] Now every turbomachine includes a complex circuit which is responsible for supplying oil, via pumps, to all systems which need lubricating oil, for recovering this oil, cooling it and filtering it to remove impurities which come from the normal operation of the turbomachine.

[0011] The intermediate bearing is therefore also connected to such an oil supply circuit, and there is a need to remove this oil from the intermediate bearing in order to cool, filter and reuse it, for example at the intermediate bearing or elsewhere in the turbomachine, for example in the gearbox.

[0012] The proposed solution for draining oil from the intermediate bearing must be functional even when the radial drive shaft is rotating, including at high speeds. The solution must also be functional when the radial drive shaft is not vertical but inclined, as is the case in many aircraft turbomachinery.

[0013] To date, there is no satisfactory solution for evacuating oil outside of a bearing in which a shaft is driven at a high rotational speed, i.e., at a speed sufficient to drive the oil into rotation so that it cannot flow by gravity along said shaft for evacuation.

[0014] There is therefore a need for an accessory drive assembly designed to capture the oil circulating inside an intermediate bearing in which a radial drive shaft is housed for rotation, in order to redirect it elsewhere in the turbomachine. SUMMARY OF THE INVENTION

[0015] The invention offers a solution to the problems mentioned above, by providing an intermediate bearing in which oil can be driven into rotation, and adapted so as to trap this oil and facilitate its evacuation elsewhere in the turbomachine.

[0016] This intermediate bearing is, for example, located at the junction between the primary shaft and the secondary shaft of a two-part radial drive shaft to limit its deflection.

[0017] It can also be used to guide, maintain and / or reduce vibration of a one-piece radial drive shaft.

[0018] The terms "top" and "bottom" used in this text refer to the orientation of the parts as illustrated in the figures, it being understood that this orientation will not necessarily always be maintained. It should be noted, however, that the support arm, the intermediate housing hub, and the radial drive shaft do not rotate around the turbomachine's engine axis, so their orientation does not change during a "normal" flight.

[0019] Generally speaking, up refers to the direction where the turbomachine intermediate casing hub and the shaft linking the turbine to the compressor are located, while down refers to the direction where the gearbox and the intermediate casing ferrule are located.

[0020] One aspect of the invention relates to an accessory drive assembly for an aircraft turbomachine, which accessory drive assembly comprises a radial drive shaft with longitudinal axis A and a gearbox, characterized in that it further comprises an intermediate bearing mounted around the radial drive shaft, the intermediate bearing having a first flared part and a second flared part situated opposite the first flared part, the first flared part and the second flared part delimiting between them a hollow volume in which oil circulates, and in that the first flared part: has a cylindrical housing communicating with the hollow volume, extending along the longitudinal axis A and housing the rotating radial drive shaft;features an oil circulation conduit having an inlet orifice that opens into the hollow volume and an outlet orifice suitable for communicating with an oil treatment or reuse device.

[0021] The oil circulation channel and its orifices thus form an oil orifice which, due to its location and shape, advantageously captures rotating oil from the intermediate bearing and redirects it elsewhere in the turbomachine. The oil can then be returned to an oil treatment or reuse device, such as an oil cooling device, an oil filtration device, an oil storage device, or a device requiring an oil supply, such as the gearbox. This oil circulation can be achieved, for example, by gravity and / or by a pumping system.

[0022] The oil circulation channel and its orifices allow the oil present in the intermediate bearing to be recovered even when the radial drive shaft is driven at a high rotational speed, and even when the radial drive shaft is inclined.

[0023] In addition to the features mentioned in the preceding paragraph, the accessory drive assembly according to one aspect of the invention may have one or more of the following complementary features, considered individually or in all technically possible combinations: the oil circulation channel extends parallel to the longitudinal axis A; the first flared portion has a skirt laterally delimiting the hollow volume, and the inlet port is located between the cylindrical housing and said skirt; the first flared portion has a lower portion bordering the cylindrical housing and an upper portion bordered by the skirt, and the inlet port is located in the upper portion.The first flared section features a spiral gutter, starting from a high point located at the top of the first flared section and extending to a low point where it meets the inlet opening, along longitudinal axis A. The low point is closer to the cylindrical housing than the high point. The gutter spiral completes a single 360-degree turn. The gutter widens progressively from its high point to its low point. The cylindrical housing is circular and centered around the longitudinal axis A. The skirt is circular and centered around the longitudinal axis A. The first flared section includes a flange or mounting tabs extending laterally outwards. The first flared section has a radial notch that opens into the cylindrical housing.The accessory drive assembly further includes a support arm located between an intermediate housing ferrule and an intermediate housing hub, with part of the radial drive shaft housed in it. said support arm, and the first flared part being formed in an upper end of the support arm.

[0024] The spiral's characteristics are designed to trap the oil and direct it towards the inlet of the oil circulation line to facilitate its drainage. This spiral is particularly well-suited for redirecting oil into the oil circulation line while the oil is driven into rotation within the flared oil receiving section by the rotation of the drive shaft with which it is in contact.

[0025] One aspect of the invention also relates to an aircraft turbomachine comprising an accessory drive assembly according to the invention as previously described.

[0026] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0027] The figures are presented for illustrative purposes only and are in no way limiting to the invention.

[0028] [Fig. 1] is a cross-sectional view of an accessory drive assembly for an aircraft turbomachine according to an exemplary embodiment of the invention.

[0029] [Fig. 2] is a perspective detail view of one end of an intermediate bearing equipped with an oil hole according to an exemplary embodiment of the invention, where the radial drive shaft is shown in ghost lines.

[0030] [Fig. 3] is a detailed perspective view of the intermediate bearing of [Fig. 2] centered on the oil hole. DETAILED DESCRIPTION

[0031] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0032] The invention relates to an accessory drive assembly 1 for an aircraft turbomachine, as illustrated by way of example in [Fig. 1],

[0033] The accessory drive assembly 1 includes a radial drive shaft 2 with longitudinal axis A and a gearbox 3.

[0034] According to an embodiment given by way of example and illustrated on [Fig. 1], the radial drive shaft 2 can be in two parts, and comprise a primary shaft 2a for example connected to an intermediate housing hub 16 and a secondary shaft 2b for example connected to the gearbox 3.

[0035] Gearbox 3, for example, is mounted on an intermediate casing ferrule 15.

[0036] The accessory drive assembly 1 further includes an intermediate bearing 4 mounted on the radial drive shaft 2 and comprising, for example, a ball or roller bearing. The radial drive shaft 2 is rotatably housed within the intermediate bearing 4. The intermediate bearing 4 serves, for example, to guide, maintain, and / or limit the deflection of the radial drive shaft 2. It is, for example, located approximately in the middle of the radial drive shaft 2.

[0037] In the case where the radial drive shaft 2 is in two parts 2a, 2b, the intermediate bearing 4 can be located at the junction between the primary shaft 2a and the secondary shaft 2b.

[0038] The intermediate bearing 4 has a first flared portion 4' and a second flared portion 4" located opposite the first flared portion 4'. These two flared portions 4', 4" each preferably have an inner face shaped like a cup or bowl. The first flared portion 4' and the second flared portion 4" define a hollow volume 5 through which oil circulates. Preferably, the first flared portion 4' is located in the lower part of the intermediate bearing 4, while the second flared portion 4" is located in the upper part of said intermediate bearing 4.

[0039] For clarity of the figures, the oil supply device of the intermediate bearing 4 is not shown in the drawings.

[0040] Bearings, not shown, are preferentially housed in the hollow volume 5.

[0041] The first flared part 4' illustrated as an example on [Fig. 2] has a cylindrical housing 6 communicating with the hollow volume 5 and extending along the longitudinal axis A to house the rotating radial drive shaft 2.

[0042] The cylindrical housing 6 is preferably of circular cross-section and centered around the longitudinal axis A.

[0043] The first flared part 4' is distinguished by having an oil circulation channel 9 with an inlet orifice 10 which opens into the hollow volume 5 and an outlet orifice 11 suitable for communicating with an oil processing, storage or use device 18 for example via an oil line 19. The inlet orifice 10 of the oil circulation channel 9 serves as the oil drain hole for the intermediate bearing 4.

[0044] The oil circulation conduit 9 extends preferentially parallel to the longitudinal axis A, along the cylindrical housing 6 and at a distance from it.

[0045] The first flared part 4' preferentially has a skirt 8 laterally delimiting the hollow volume 5. The inlet orifice 10 is then located between the cylindrical housing 6 and said skirt 8, preferably in the immediate vicinity of the latter.

[0046] The first flared part 4' is preferentially circular and centered around the longitudinal axis A. It is presented for example in the form of a cup whose edges are formed by the skirt 8. Similarly, the skirt 8 is preferentially circular and centered around the longitudinal axis A.

[0047] The first flared part 4' can be substantially conical. It has a lower part 4b bordering the cylindrical housing 6 and an upper part 4h, for example bordered by the skirt 8. The inlet orifice 10 of the oil circulation conduit 9 is preferably located in the upper part 4h.

[0048] According to one embodiment of the invention, the first flared portion 4' has a spiral gutter 7, starting from a high point 7h located in the upper part 4h of the first flared portion 4' and continuing to a low point 7b of the first flared portion 4' where the gutter 7 joins the inlet 10 of the oil circulation conduit 9. Considering a height along the longitudinal axis A, the low point 7b is located lower and closer to the cylindrical housing 6 than the high point 7h. The high point 7h is preferably located against the skirt 8, at its base.

[0049] The concave shape of the spiral gutter 7, as well as the difference in elevation between its beginning, located at the level of the cylindrical housing hole 6 in the lower part 4b, and its end, located at the level of the inlet opening 10 in the upper part 4h, allows for trap the oil and guide it towards the inlet port 10 of the oil circulation line 9.

[0050] Without this spiral gutter 7, and due to the rotation of the oil created by the rotation of the radial drive shaft, an "air plug" would be likely to form in the inlet orifice 10 of the oil circulation conduit 9 and the oil would then not be evacuated.

[0051] Furthermore, without this spiral gutter 7, impurities would be likely to accumulate in the lower part 4b of the first flared section 4'. The spiral gutter 7 facilitates the movement of oil towards the inlet orifice 10 of the oil circulation channel 9.

[0052] The inlet orifice 10 of the oil circulation conduit 9 preferentially connects the high point 7h and the low point 7b of the spiral gutter 7.

[0053] The spiral of gutter 7 preferentially makes a single 360-degree turn.

[0054] According to one embodiment of the invention, the gutter 7 does not have a constant width. For example, it can gradually widen from its highest point 7h to its lowest point 7b.

[0055] If the oil is driven in rotation in one direction of rotation in the first flared part 4' by the radial drive shaft 2, the direction of rotation of the spiral of the gutter 7 is preferably provided so that this oil, starting from the high point 7h, makes a complete turn in said first flared part 4', before reaching the inlet port 10 of the oil circulation conduit 9. Thus, the gutter 7 illustrated in the figures, widening in the clockwise direction, is provided for a radial drive shaft 2 rotating in a clockwise direction illustrated on [Fig. 2] by an arrow F.

[0056] According to these embodiments of the invention, with reference to [Fig. 3], when the oil reaches the inlet orifice 10 of the oil circulation conduit 9, it enters the conduit at a low point 10b located opposite a high point 10h of said inlet orifice 10. This facilitates the penetration of the oil into the inlet orifice 10 rather than allowing the oil to continue its rotational movement in the first flared portion 4'. The variation in height along axis A between the low point 10b and the high point 10h of the inlet orifice 10 forces the oil to enter the inlet orifice 10.

[0057] Similarly, as the groove 7 gradually widens, after a complete rotation from the high point 7h, the oil reaches a lip 7r formed by the difference in height of the groove 7 from its high point 7h to its low point 7b. This lip 7r also facilitates the penetration of the oil into the inlet orifice 10 rather than allowing the oil to continue its rotational movement in the first flared section 4'. In its upper part (left side of the lip 7r in [Fig. 3]), this lip 7r joins the inlet orifice 10 of the oil circulation channel 9, while in its lower part (right side of the lip 7r in [Fig. 3]), it can be located in the immediate vicinity of the cylindrical housing 6. Indeed, the more extensive this lip 7r is, the greater the quantity of oil is directed towards the inlet orifice 10.

[0058] According to one embodiment of the invention, the first flared portion 4' has a radial notch 13, for example located at the lowest point 7b of the channel 7, which opens into the cylindrical housing 6. When the turbomachine is stopped or at very low speed, this notch 13 serves to return oil through the cylindrical housing 6, for example to an oil treatment, storage, or utilization device. The oil can thus return naturally by gravity to the gearbox 3. Indeed, in this situation, the rotation of the radial drive shaft 2 is not sufficient to drive the oil towards the inlet 10 of the oil circulation channel 9. This notch promotes the "flowing" of the oil along the radial drive shaft 2 to then reach, for example, an oil treatment, storage, or utilization device 18.

[0059] According to an embodiment given by way of example and illustrated in [Fig. 1], the accessory drive assembly 1 may also include a support arm 17, for example located between the intermediate housing shell 15 and the intermediate housing hub 16 of the turbomachine. According to this embodiment, a portion of the radial drive shaft 2, preferably the secondary shaft 2b, is housed within the support arm 17.

[0060] In the case where the accessory drive assembly 1 includes a support arm 17, the first flared part 4' can be formed into an upper end of the support arm 17.

[0061] Similarly, in the case where the accessory drive assembly 1 includes a support arm 17, an oil line 19 connects the outlet port 11 of the intermediate bearing 4 to an oil processing, storage or use device 18 can be shaped or housed in the support arm 17, for example parallel to the axis A.

[0062] According to one embodiment of the invention, the skirt 8 comprises a flange or mounting tabs 12 extending laterally outwards, for example to allow the intermediate bearing 4 to be secured to another part. Each flange or mounting tab 12 preferably has one or more through holes 14 for the passage of a screw or a bolted assembly.

[0063] In the case where the first flared part 4' is formed in an upper end of the support arm 17, the flange or the fixing tabs 12 can allow the support arm 17 to be fixed to the intermediate housing hub 16.

[0064] The invention also relates to an aircraft turbomachine comprising an accessory drive assembly 1 according to the invention as previously described.

[0065] Although described through a number of examples, variants and embodiments, the accessory drive assembly according to the invention includes various variants, modifications and improvements which will be obvious to a person skilled in the art, it being understood that these variants, modifications and improvements form part of the scope of the invention.

Claims

DEMANDS

1. Accessory drive assembly (1) for an aircraft turbomachine, which accessory drive assembly (1) comprises a radial drive shaft (2) with longitudinal axis (A) and a gearbox (3), characterized in that it further comprises an intermediate bearing (4) mounted around the radial drive shaft (2), the intermediate bearing (4) having a first flared portion (4') and a second flared portion (4") situated opposite the first flared portion (4'), the first flared portion (4') and the second flared portion (4") delimiting between them a hollow volume (5) through which oil circulates, and in that the first flared portion (4'): - has a cylindrical housing (6) communicating with the hollow volume (5), extending along the longitudinal axis (A) and housing the rotating radial drive shaft (2); - presents an oil circulation conduit (9) having an inlet port (10) which opens into the hollow volume (5) and an outlet port (11) suitable for communicating with an oil processing, storage or use device (18).

2. Accessory drive assembly (1) according to claim 1, characterized in that the oil circulation conduit (9) extends parallel to the longitudinal axis (A).

3. Accessory drive assembly (1) according to claim 1 or 2, characterized in that the first flared part (4') has a skirt (8) laterally delimiting the hollow volume (5) and in that the inlet orifice (10) is located between the cylindrical housing (5) and said skirt (8).

4. Accessory drive assembly (1) according to claim 3, characterized in that the first flared part (4') has a lower part (4b) bordering the cylindrical housing (5) and an upper part (4h) bordered by the skirt (8), and in that the inlet orifice (10) is located in the upper part (4h).

5. Accessory drive assembly (1) according to claim 4, characterized in that the first flared part (4') has a spiral gutter (7), starting from a high point (7h) located in the upper part (4h) of the first flared part (4') and going down to a low point (7b) where it joins the inlet orifice (10), according the longitudinal axis (A) the lowest point (7b) being closer to the cylindrical housing (5) than the highest point (7h).

6. Accessory drive assembly (1) according to claim 5, characterized in that the gutter (7) widens progressively from its high point (7h) to its low point (7b).

7. Accessory drive assembly (1) according to any one of the preceding claims, characterized in that the first flared part (4') comprises a flange or mounting tabs (12) extending laterally outwards. [Claims] Accessory drive assembly (1) according to any one of the preceding claims, characterized in that the first flared part (4') has a radial notch (13) which opens into the cylindrical housing (5). [Claims] Accessory drive assembly (1) according to any one of the preceding claims, characterized in that it further comprises a support arm (17) situated between an intermediate housing ferrule (15) and an intermediate housing hub (16), a portion of the radial drive shaft (2) being housed in said support arm (17), and in that the first flared portion (4') is formed in an upper end of the support arm (17).

10. Aircraft turbomachine, characterized in that it comprises an accessory drive assembly (1) according to any one of the preceding claims.

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