EP0754838B1 - Disengageable manual inching gear for a turbomachine - Google Patents

Description

The invention relates to a turbomachine, and more particularly a way to manually train the rotor rotation for endoscopic control of the blades of this rotor.

STATE OF THE ART

Turbomachinery and in particular turboshaft engines for aircraft are subject to inspections and controls regular. Some inspections are done using endoscopes that are introduced inside the turbine engine by closable openings provided for this purpose and which allow examination without disassembly of non- visible from the outside. To inspect the rotor blades, an endoscope is introduced into the fluid vein by closable openings of the turbine engine housing, and successively each dawn in front of the endoscope by making turn the rotor step by step. This step-by-step rotation of the rotor is usually done by hand training an organ turning mechanically connected to the rotor.

Usually, one of the gears of the equipment case, which allows to make turn the high pressure rotor through the mechanical transmission rotatingly connecting the rotor to gears of the equipment case. We access this gable by a closable opening of the casing of the equipment case. This opening is generally at the end of the shaft of the pinion, and we simply rotate the pinion using a steering wheel or a standard ratchet which we introduce the end in, or on, a non-circular span, by square example, fitted at the end of the pinion shaft at train.

This opening is usually closed by a cover that must be removed and then put back when the operation is finished. Sometimes it's a piece of equipment that needs to be removed to access the shaft transmitting the movement to this equipment.

In case the access to the pinion is done by removing a cover, it happened that the officer performing the inspection then forget to put the cover back on, causing the oil leaking through the opening left open and the rapid exhaustion of the turbomachine's oil reserve during its operation.

This oversight is hardly possible in the event that it is necessary deposit equipment, but the obligation to deposit and then reassemble equipment to carry out an inspection rotor blade endoscopy takes time, extends the operation, increases the cost of maintenance and the rest of it does a drawback.

1) Du fait de la température de fonctionnement et de la fiabilité exigée, notamment dans le cas des turbomoteurs pour aéronefs; il faudrait utiliser un joint d'étanchéité du type à anneau de céramique ou de carbone qui est coûteux.

2) Bien que fiable, un tel joint introduit une cause de panne supplémentaire alors que l'on exige habituellement des turbomachines un fonctionnement prolongé sans intervention.

We could consider extending the pinion shaft outside the casing and ensuring a seal between the shaft and the casing, which would allow this shaft to be driven without dismantling anything. This solution however has two drawbacks:

1) Because of the operating temperature and the reliability required, in particular in the case of aircraft turbine engines; an expensive ceramic or carbon ring type seal should be used.

2) Although reliable, such a seal introduces an additional cause of failure whereas turbomachines are usually required to operate for a long time without intervention.

SUMMARY OF THE INVENTION

To solve this problem, the invention proposes to train a turbomachine shaft connected in rotation to the rotor, to the by means of a drive shaft passing through the wall of the casing surrounding the tree to be trained, the training tree and the tree to train being connected together by a disengageable coupling controlled by a declutching means automatic. An at least static sealing means, effective at least in the disengaged position, is arranged between the drive shaft and the housing. The training tree will be rotated by its end outside the casing.

We understand that such an arrangement makes it possible to rotate manually the rotor without opening the casing. Mating controlled by an automatic clutch ensures that the shaft drive will remain stationary during operation of the turbomachine, and the at least static sealing means associated with these previous means reliably avoids and little expensive oil losses that could result from movable mechanism passing through the wall of the casing.

Advantageously, the drive shaft, the means of automatic declutching and the sealing means at least static are mounted on a removable support fixed to the housing on the opening to reach the tree to train. This provision is inexpensive and can be substituted for the cover of the prior art without modification of the casing, this which allows inexpensive to apply retroactively the invention with turbomachinery already in service.

Advantageously, the drive shaft will be coaxial with the shaft to train, which simplifies the coupling of which the automatic release can be ensured by a spring pushing the drive shaft outward.

DESCRIPTION OF THE FIGURES

The invention will be better understood and the advantages it will appear more clearly when seen from an example detailed realization and attached figures:

Figure 1 is a simplified sectional view of a turbofan of the turbofan type with double body and double flow showing the kinematic chain from the rotor to the gearbox.

FIG. 2 illustrates an example of the state of the art.

FIG. 3 illustrates an example of implementation of the invention.

DETAILED DESCRIPTION

We will first refer to Figure 1. In this example, the turbomachine 1 is a double-body turbofan and double flow of a well known and commonly used type for propel transport aircraft. We will not describe this fact that the parts of the turbomachine 1 related to the invention. The high pressure rotor 2 has a shaft 3 integral with several stages of blades 4 of the high compressor pressure at the front of the combustion chamber 5, and integral with one or more stages of blades 6 of the turbine the rear of said chamber 5. The low pressure rotor 7 comprises a shaft 8 coaxial and inside the shaft 3, this shaft 8 being integral with the front of a stage of fan blades 9 and of several stages of blades 10 of the low pressure compressor, this shaft 8 also being integral with the back of one or several stages of blades 11 of the low pressure turbine. The kinematic chain going from the shaft 3 of the high rotor pressure at the equipment support 14 comprises a succession of shafts 16 operating inside housings 20 and connected in rotation directly or indirectly to the rotor 2. There is thus successively a first bevel gear 15 to 90 ° with two bevel gears, a first shaft transmission 16a perpendicular to shaft 3, a second angle gear 17 at 90 ° with two bevel gears, and one second transmission shaft 16b parallel to the shaft 3 and driving in rotation one of the shafts and pinions 16c of equipment support 14. Different equipment, such as starter or oil or fuel pumps are connected to the shafts and pinions 16c of the equipment support 14. Because difficult operating conditions, the components 16 of the drive train operate at inside of waterproof housings 20 and are lubricated by oil or oil mists.

The low pressure rotor 7 is directly accessible from the outside of the engine from the front or rear, and the step by step rotation of said low pressure rotor is done simply by hand. On the contrary, the high pressure rotor 2 is not directly accessible from outside the motor, and the stepwise rotation of said rotor 2 takes place in hand-driving one of the trees 16.

Reference will now be made to FIG. 2. The equipment support 14 comprises a casing 20c surrounding and supporting a plurality of shafts and pinions 16c meshing with each other. The shaft referenced 16b in FIG. 1 transmits the movement to one of the shafts and pinions 16c of the equipment support 14 by means of a coupling generally of the fluted type 21. This movement is transmitted gradually. with different trees and gables 16c. An opening 22 in the casing 20c is arranged opposite the end of a shaft 16c and is closed by a removable cover 23, while a non-circular bore, for example square 24 is arranged in the geometric axis 25 and at the end 26 of the shaft 16c.
Thus, to rotate the high pressure rotor manually and step by step and successively bring each blade 4 or 6 in front of an endoscope, it is necessary to disassemble the cover 23, introduce a handwheel or a crank with square tip in the square bore 24 and actuate said steering wheel or said crank. If we then forget to replace the cover 23, the oil distributed inside the casing 20c during the operation of the turbomachine escapes through the opening 22, which causes the rapid depletion of the reserve of turbomachine oil, resulting in damage to and failure of said turbomachine.

Referring now to Figure 3. A drive shaft 30 of geometric axis 31 aligned with the geometric axis 25 is held by a support 32 opposite the end 26 of the shaft 16c. The shaft 30 ends on the side of the shaft 16c by a non-circular male end piece 33 of shape complementary to that of the bore 24 and capable of being introduced into this bore by a translation of the shaft 30 in the direction of the shaft 16c along the geometric axis 31. It is understood that the end piece 33 and the bore 24 constitute a disengageable coupling which will be generally referenced 34.
The drive shaft 30 is guided in translation and rotation by a bearing 35 located in its middle part. This guidance is sufficient when the end piece 33 is introduced into the bore 24, that is to say when the shaft 31 is in the engaged position. Advantageously, the shaft 31 will also be guided by a second bearing 36 which can be reduced to a simple bore in the support 32, the shaft 31 being supported in this bearing 36 by the outermost parts of the end cap 33.

The shaft 30 has in its middle part a shoulder 37 against which comes to rest the end of a spring helical 38 surrounding the shaft 31, while the other end of the spring 38 bears against the support 32. The shoulder 37 can also be constituted by a circlip. The spring 38 pushes the shaft 31 outwards into position disengaged, the spring 38 and the shoulder 37 constituting more usually an automatic declutching means 39 of the coupling 34. In the disengaged position, the shaft 30 arrives by its shoulder 37 abutting against the bearing 35, said shoulder 37 thus ensuring an axial retention function from tree 30.

The sealing means 40 of the shaft 30 relative to the casing 20c is preferably ensured by a lip seal 40a mounted in the support 32 and pressing on a circular surface 40b of the tree 30. Advantageously, the surface 40b will be slightly conical with a slightly smaller diameter towards the end 41 of the shaft 30 furthest from the casing 20c, this reduction in diameter being sufficient for the contact between seal 40a and surface 40b becomes weak or nonexistent during manual rotation of the rotor.

In a preferred embodiment, a joint will be used 40a graphite-loaded Teflon ring with a section U-shaped opening opening facing the inside of the housing parallel to the geometric axis 31 of the shaft 30, sealing being achieved by the support of the U-shaped wings respectively on the surface 40b in its most part large diameter and against the bore not referenced in which is placed the seal 40a. In general, an annular spring not referenced surrounds the inner wing of the U and increases the pressure exerted by the seal 40a on the surface 40b. Such seal 40a is available for example under the brand BALSEAL commercial.

It is understood that during the operation of the turbomachine, the spring 38 maintains the shaft 30 in the disengaged position, this shaft 30 no longer being consequently driven by the shaft 16c and therefore remaining stationary.
The sealing means 40 acts under these conditions in a static manner, which gives it great reliability despite the harsh environment and allows the use of inexpensive means.

The use of a lip seal 40a with the lip turned inward is the preferred solution because during the operation of the turbomachine, it creates an overpressure inside the casing 20c which presses said lip on the surface 40b, which improves the sealing and reliability of the present device. Conversely when stationary, the overpressure no longer exists, the support of the lip of the seal 40a on the surface 40b is relaxed, which reduces the friction of the medium seal 40 and facilitates the operation of the shaft 30.

The reliability of the seal 40 is further improved by the taper of the surface 40b. Indeed, when we operate the shaft 30 to rotate the shaft 16c, it is necessary to press the shaft 30 in the casing to couple it to the shaft 16c, the joint 40a then being on surface 40b towards the end 41 of the shaft 31, the cylindrical surface 40b having a smaller diameter towards the end 41, the seal 40a no longer pressing lightly or not at all on the surface 40b, the seal 40a no longer risking being deteriorated or worn by the rotation of the shaft 30 or the radial deflection of this shaft 30 resulting from the play on the stages 35 and 36.

The support 32 will advantageously include a base 45 positioned in the bore 22a and the outer face 22b of the opening 22, and a cylinder 46, one end 46a of which is positioned on the base 45 while its other end 46b the outermost of the casing 20c receives the means 40. The bearing 36 is positioned in the base 45 and the bearing 35 in the cylinder 46, the spring 38 taking support on the base 45. The base 45 is statically sealed relative to the casing 20a, and the cylinder 46 is sealed by compared to base 45 for example by simple seals toric. The cylinder 46 surrounds the middle part of the shaft 33, the bearing 35 and the automatic declutching means 39, and thus ensures the protection of these organs. Support 32 is fixed on the casing 20c, for example by screws not depicted, as would be the cover of art prior.

The end 41 of the shaft 30 has a bore 50 no circular, for example square, and centered on its axis geometric 31. This bore makes it possible to couple a means of removable preemption of the shaft 30, for example a wrench standard ratchet or flywheel not shown, for manipulate this tree 30.

Advantageously, the end 41 of the shaft 31 will be protected protruding from cylinder 46 by a removable cap 51, fixed on cylinder 46, and at least dustproof by compared to this cylinder 46.

It is clear that the present invention does not apply only to the equipment support 14 of the turbomachine 1, but to any shaft 16 connected in rotation to the rotor 2 and easily accessible from the outside through an opening 22 in a casing 20 surrounding the shaft 16, this connection rotation must obviously be sufficient to cause the rotor 2.

It is also clear that the relative arrangement and the mode of coupling of the shafts 16 and 30 may be subject to variants. In the case where the shafts 16 and 30 remain aligned, it is also possible to use a clutch coupling. It is also possible to arrange the shafts 16 and 30 parallel to each other, or to make their geometric axes 25 and 31 concurrent, and use a gear coupling.
The static seal between the shaft 30 and the support 32 can also be ensured by a steep conical shoulder on the shaft 30 penetrating in the disengaged position in a bore of complementary shape of the support 32, the conical shoulder comprising at its surface a groove and an O-ring which ensures a perfect seal with the tapered bore without rubbing against it during disengagement.

Claims (6)

1. A turbomachine having manual means for turning its rotor (2), characterised in that it comprises:

   (a) a casing (20) containing a shaft (16) rotatably connected to the rotor (2), the casing (20) being formed with an aperture (22) giving access to the shaft (16);

   (b) a drive shaft (30) extending through the aperture (22) in the casing wall and being held by a detachable support (32) disposed over the aperture (22);

   (c) disengageable means (34) for rotatably coupling the shafts (16) and (30) together;

   (d) disengaging means (39) for automatically disengaging the coupling (34), and

   (e) at least static sealing means (40) between the drive shaft (30) and the casing wall, the sealing means (40) being operative at least when the shaft (30) is in the disengaged position.
2. A turbomachine according to claim 1, characterised in that the drive shaft (30) is capable of axial movement and in the disengaged position is urged outwards by a spring (38).
3. A turbomachine according to claim 2, the sealing means (40) comprising a seal (40a) rigidly secured to the detachable support (32) and bearing on a circular surface (40b) of the drive shaft (30), characterised in that the circular surface (40b) is conical with a minor diameter near the drive shaft end (41) remote from the casing (20), in order to reduce or obviate contact between the seal (40a) and the surface (40b) during manual rotation of the rotor.
4. A turbomachine according to any of claims 1 to 3, characterised in that the drive shaft (30) is coaxial to the shaft (16) to be driven and in that coupling is effected by engagement of a male member (33) of the drive shaft (30) in a non-circular bore (24) of the driven shaft (16), the male member (33) being shaped to match the bore (24).
5. A turbomachine according to any of claims 1 to 4, characterised in that the casing (20) is the casing (20c) of the accessory support (14).
6. A turbomachine according to any of claims 1 to 5, characterised in that the drive shaft end (41) which is outside the casing (20) is covered by a removable protective cap (51) which is statically sealed at least in respect of dust.

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