Turbofan

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DESCRIPTION

Turbojet.

The present invention concerns the field of multi-body and multi-flow turbojets, especially double-body, double-flow turbojets. This refers to the mounting of an auxiliary equipment and the mechanical transmission between it and an engine shaft.

For the operation of auxiliary machines mounted on the engine, such as electric generators, oil or fuel pumps, necessary for its operation or for the operation of the aircraft in which it is mounted, the required power is generally taken. of the main tree. A double-body turbojet comprises two coaxial shafts, one, called low-pressure or BP, which joins the low-pressure compressor to the low-pressure turbine and which together form the BP body, the other, called high-pressure or HP, that joins the high pressure compressor to the high pressure turbine and that together form the HP body. In the case of an engine of this type, the transmission of power to the auxiliaries is generally ensured by a radial shaft, housed in an arm of the intermediate casing, one of whose ends comprises a conical pinion that cooperates with a pinion integral with the body of the engine. high pressure. The other end is mechanically connected to a box comprising a plurality of gears and which forms a support for the auxiliary machines while ensuring their operation. When the motor is dual flow, the radial transmission shaft passes through the two primary flow and secondary flow veins respectively because the accessory drive gearbox, also called the AGB for accessory gear box, is mounted on the crankcase of the blower that generates the secondary flow.

Due to the evolution of engines and the conditions of their use, it has been proposed to mount supplementary equipment in the primary flow casing in cooperation with the radial drive shaft of the accessory machines between the two extremities of the latter. Such equipment can be constituted, for example, by a motor that makes it possible to drive the radial transmission shaft, supporting the body HP. Indeed, a support of this type is useful in the case where the arrangement of the engine involves a significant demand for power at the idle speed of the latter, to ensure the operation of certain auxiliary machines such as electric generators. At idle speed, the HP body cannot satisfactorily supply all the power required within the framework of such a design.

The present invention therefore concerns the mounting of an auxiliary machine or equipment in the crankcase of the engine, in an intermediate position between the two ends of the radial transmission shaft, as well as the arrangements relating to the radial transmission shaft.

According to the invention, a turbojet having the characteristics of claim 1 and comprising an intermediate casing with a drive shaft of a gearbox of the auxiliary machines mounted on a radial arm of the intermediate casing, said shaft being attached at a first end, to a mechanical transmission means with a motor shaft of the turbojet, at a second end, to a mechanical transmission means with said box, and comprising a conical pinion between the two extremities that allows to ensure a mechanical transmission with supplementary auxiliary equipment, it is characterized by the fact that the shaft with said pinion is contained in a casing that has a tight oil circuit with respect to the quoted arm.

The drive shaft structure according to the invention has the advantage of preventing oil leakage and thus limiting fire zones. This is particularly advantageous in the case where the intermediate casing structure comprises an added external ferrule, as the risk of oil leakage generally increases with the number of bolted parts.

According to a preferred embodiment, the casing comprises a casing for the pinion and two sleeves for the parts of the shaft located on either side of the pinion.

The invention applies in particular to the case in which the transmission shaft is in three cylindrical parts that are coupled one into the other, with a first cylindrical element in which the pinion is mounted and two cylindrical shaft elements extending one and the other. the first cylindrical element starts.

According to another characteristic of the invention, the auxiliary equipment comprising a drive shaft cooperates with said pinion of the shaft and is arranged in such a way as to form with it a modular assembly according to claim 8. This arrangement is particularly advantageous because It simplifies the assembly of the equipment in the factory, as well as its maintenance, and allows to have an interchangeable equipment. In this way, the delicate mounting and adjustment of the bevel torque can be carried out precisely outside the turbojet, which is space-constrained and generally very busy. For the assembly in this, it only remains to couple the different cylindrical elements of the radial transmission shaft. Such an operation does not require the use of precision tools.

The modular auxiliary equipment comprises a support on which the pinion is mounted.

A non-limiting embodiment of the invention is now described, referring to the attached drawings, in which:

ES 2 345 124 T3 Figure 1 shows, in axial section, a general view of a dual-flow, double-body turbojet engine to which the invention can be applied, Figure 2 shows, in axial section, a view through a radial arm of the intermediate casing in which a drive shaft of the AGB box is housed with supplementary auxiliary equipment according to the invention, Figures 3 to 6 show an assembly sequence of the shaft according to the invention comprising supplementary auxiliary equipment.

Figure 1 schematically represents a turbojet dual-flow, double-body with its different main components. This comprises a first shaft 3 that connects, on the left of the figure, a blower rotor 5 and the first stages 7 of the compressor to the low pressure turbine 9; the whole forms the low pressure body BP. Coaxial with the first shaft, a second shaft 11 in the shape of a drum, joins the high pressure stages 13 of the compressor to the high pressure turbine 15; the assembly forms the high-pressure body HP with the combustion chamber 17. The shaft 3 is supported, upstream, by the bearing 3a mounted on the casing 19 which is designated intermediate casing and, downstream, by the mounted bearing 3c on the exhaust crankcase 21. The shaft HP is supported in this case by the bearing 3b of the intermediate casing 19 and in the rear part by the shaft 3 by means of the inter-shaft bearing 3d.

The intermediate casing is made up of a hub 19a that supports the bearings 3a and 3b, by an outer shell 19b, provided with front fixing means to the aircraft and that supports the blower casing, as well as radial arms 19c that join the hub. 19a to ferrule 19b. This intermediate casing is constituted at least in part by a piece obtained in cast iron to which radial arms have optionally been added. Auxiliary machines, such as generators and fuel or oil pumps, are mounted in a gearbox 23, as is known, which in this field is designated AGB. This box is externally mounted on the blower housing in a location that allows access for maintenance. The gears are mechanically connected to a shaft of the motor by means of a radial drive shaft 25 which is housed in a radial arm 19c of the intermediate case. This drive shaft is connected to a first conical pinion at its inner radial end. This pinion cooperates with a bevel pinion integral with the HP body. The shaft 25 is also connected to a second pinion at its outer radial end that cooperates with an input shaft of the AGB gear set.

In operation, an engine of this type sucks the air through the blower that compresses it into a primary flow that passes through the compression stages, the combustion chamber and the turbine stages and a secondary flow that is ejected into the atmosphere surrounding the chamber. combustion. The turbines drive the compression means through the BP and HP shafts respectively.

It has been proposed to place a supplementary auxiliary equipment in the space arranged inside the crankcase between the two flows, primary and secondary. This equipment, according to one example, is a support motor that participates in driving the radial transmission shaft 25 when the HP body is not sufficient. This is the case in engines where the number of auxiliary machines driven and the power required are important at idle. Such a support motor can be an air turbine, fed from the primary flow.

Beyond this particular example, the invention applies to any supplementary auxiliary equipment, receiving or driving machine, that is housed in this space.

The problem found in this case comes from lubrication, the need for oil flow widely exceeding the existing means for the drive shaft of auxiliary machines. The present invention relates to an arrangement that makes it possible to alleviate this problem.

In figure 2, a partial view of the motor at the level of the radial transmission shaft, according to the invention, has been represented in axial section.

The parts corresponding to those in figure 1 bear the same reference increased by 100. Thus, there is the intermediate casing 119 in whose radial arm 119c the radial shaft 125 for driving the auxiliary machines not visible in figure 2 is housed. The shaft 125 passes through the shell 119b of the intermediate casing and its outer radial end is mechanically connected, for example by a connection of grooves, to a pair of conical pinions that has not been shown.

Arm 119c is hollow and is made up of three radially distinct parts: 119c1, 119c2, and 119c3.

The aerodynamically profiled part 119c3 passes through the primary flow vein P on one side of which is seen a part of the BP 107 compressor and on the other the HP 113 compressor. The part 119c3 of the arm 119c is adjacent to the hub 119a of the intermediate casing .

The radial arm 119c comprises a portion 119c2 that passes through the secondary flow vein S. The portion 119c2 is adjacent to the ferrule 119b.

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The arm comprises a part 119c1 between the first two. This part delimits a sector of annular space that extends on one side the separation nozzle between the primary and secondary flows, and on the other it extends itself through an annular space 129 between the two flows.

In the hub 119a, the bearing 103a supports the shaft 103 of the body BP and the bearing 103b supports a shaft 111 which forms the upstream end of the compressor 113 of the body HP.

The shaft 125 is housed in this radial arm of the intermediate casing. Arm 125 is in three elements: 125a, 125b and 125c. The first central element 125a is cylindrical, hollow and is integral with a conical pinion 125a1. The second element 125b is coupled, on the radially inner side, to the first element 125a and is held therein by a joint of grooves. At its inner end, it is connected by a union of grooves to a pair of conical pinions 126 that cooperates with the axis 111 of the body HP. In this way, the element 125b is driven by the body HP.

The third element 125c is coupled, on the radially outer side, to the first element 125a and is held by a joint of grooves. As has been seen, the radial end of this element is not visible in the figure. This is mechanically linked by a pair of bevel pinions to the input shaft of the AGB box. The rotational movement of the body HP is thus transmitted, by the transmission means constituted by the pair of conical pinions 126 and the shaft 125, to the input shaft of the AGB box.

A supplementary auxiliary equipment 128 is housed in the space provided by the crankcase between the primary flow stream and the secondary flow stream. The equipment comprises a motion transmission shaft 128a terminated by a bevel pinion 128a1. The kit 128 is bolted to the flank of the portion 119c1 of the radial arm 119c that extends the preceding annular space.

This team can be anyone; it can be a motor, air turbine, hydraulic motor, to drive the transmission shaft 125 in support, when this is necessary. It can also be a supplementary receiving machine driven by the shaft 125.

A support housing 128b is integral with the equipment housing 128. This housing 128b supports the central element 125a of the transmission shaft 125 through two bearings 128b1 and 128b2 in such a way that the conical pinion 128a1 meshes with the conical pinion 125a1 of the element 125a for a transmission of rotational movement from one to the other. To facilitate assembly, the support case 128b comprises a cover 128b ', in which the bearing 128b2 is mounted.

The equipment 128 with the shaft 128a, the support case 128b and the element 125a of the shaft 125 together form a module 130 in the sense that this assembly can be separately assembled and mounted in the turbojet as a block as will be explained later.

The module 130 associated with the shaft 125 is isolated from the interior space of the arm 119c thanks to a casing 131.

This casing is made up of a casing 131a and two sleeves 131b and 131c. The casing 131a surrounds the support casing 128b of the equipment 128 and the element 125A that it supports. This comprises three openings, one for the passage of the equipment 128 and two for the shaft elements 125b and 125c respectively.

Sleeve 131b surrounds element 125b of shaft 125 and sleeve 131c surrounds element 125c. Appropriate gaskets ensure the tightness between the casing 131a and the two sleeves 131b and 131c. Likewise, they are provided together at the two ends of the two sleeves.

The crankcase 128b is bolted to the wall of the arm 119c.

Thanks to this envelope, the oil necessary for the lubrication of the equipment and the mechanical transmission elements can be carried through a circuit that does not interfere with the radial arms of the intermediate casing. For example, the oil that has served to lubricate the pair of bevel pinions 128a1 and 125a1 is recovered in the space between the shaft elements 125b and 125c and the sleeves 131b and 131c respectively to be recycled.

For a more efficient recovery, a specially dedicated device can be installed at the bottom point of the crankcase 131a, in order to redirect directly to the engine recovery circuit, most of the oil that has served to lubricate the bevel torque and its bearings. . A device of this type would avoid forwarding this oil flow to the AGB, which may be contaminated by residues that come from mechanical components of the module.

In relation to Figures 3 to 6, the assembly of the assembly is described.

Figure 3 shows the assembly of the module 130. The support housing 128b is fixed to the equipment 128 whose axis 128a is not seen here. Next, the element 125a of the transmission shaft 125 is inserted, and the crankcase is closed with the cover 128b '. The bearings between element 125a and support casing 128b have not been shown.

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In figure 4 the module 130 is assembled. It is understood that this operation can be carried out in a workshop other than the engine assembly workshop or at the supplier's premises. The module can be facilitated assembled, which has a certain advantage because the delicate operations of adjusting the pair of bevel pinions must be carried out by specialized personnel and means.

Figure 5 shows the placement of the casing 131a of the casing 131 inside the intermediate casing 119 in the housing 119c1. Radial arms 119c have not been shown. The next step consists in introducing the sleeve 131b equipped with its seals from the outside through the radial openings of the casing 131a, and then the sleeve 131c equipped with its seals.

In FIG. 6, the module 130 is inserted into the casing 131a through the axial opening of the intermediate casing 119, after the sleeve 131b has been fitted. The module 130 in place prevents the sleeve 131b from coming out of its housing. The module 130 is then bolted to a radial wall of the crankcase 119, and then the assembly of this assembly is completed by positioning the two shaft elements 125b and 125c.