GB2320527A

GB2320527A - Dismantling or assembling turbine engine front end bearing housing or LP compressor component

Info

Publication number: GB2320527A
Application number: GB9722228A
Authority: GB
Inventors: Gerhard Krambeer
Original assignee: BMW Rolls Royce GmbH
Current assignee: Rolls Royce Deutschland Ltd and Co KG
Priority date: 1996-10-21
Filing date: 1997-10-21
Publication date: 1998-06-24
Also published as: GB9722228D0; DE19643336C2; DE19643336A1

Abstract

With an aircraft engine in a horizontal position, its low pressure shaft (5, fig. 1) is fixed axially so it cannot rotate by means of a tool 8, comprising a central disc (8b, figs. 4a,4b) secured to an end disc of the shaft, and a cross piece (8a) connecting the disc to segments (8c) at its ends which are secured to the engine outlet guide vane housing. The front end bearing housing (or low pressure compressor component) 7a is then fastened to a lifting tool 10, after which it is removed from or pressed onto the shaft (5) by means of an hydraulic power tool 12.

Description

2320527 1 A Method for the dismantling of the front end bearing housing or

LP Compressor Shaft ComiDonent of an aircraft engine The present invention relates to a method of dismantling and/or assembling the bearing housing or low-pressure compressor shaft component of the low-pressure turbine shaft of an aircraft engine provided at the front end, which normally bears a lowpressure turbine on its rear side.

Up to now it has been relatively expensive to dismantle the first or front end bearing housing or LP compressor shaft component, or the corresponding bearing group of the low-pressure turbine shaft of an aircraft engine (Aircraft gas turbine), which can be necessary in service work. The low-pressure turbine shaft can be mounted itself in the front bearing housing, or a low- pressure compressor shaft component (= LP Compressor shaft component) or so-called fan shaft can be pressed onto the front end of the low-pressure turbine shaft.

Now for the dismantling of the front end bearing housing/LP Compressor shaft component the engine is as a rule removed from the aircraft and brought into a vertical position, i.e. the engine or its low-pressure turbine shaft assumes a vertical position. It is thereby possible to remove the (LP) lowpressure turbine from the engine. The engine is then brought into a horizontal position, whereby access to the front bearing group, 2 is is facilitated and this or the LP Compressor shaft component (= fanshaft) can be dismantled. For the later assembly of the front bearing housing or LP Compressor shaft component, the same expenditure of effort is required, in reversed order.

Since the removal of the entire engine from the aircraft, when only the front bearing housing or LP Compressor shaft component of the lowpressure turbine shaft has to be removed, represents an expenditure of effort to be avoided if possible, the present invention has the aim of providing a simplified dismantling and assembly method. The same problem arises also in the production assembly by the engine manufacturer, since here also up to now the engine has to be brought into a vertical position for the assembly work on the first bearing group or the LP Compressor shaft compon-.nt or fanshaft, which is expensive.

Accordingly the present invention is directed to a method as set out in the opening paragraph of the present specification in which with the aircraft engine in an essentially horizontal position the low-pressure turbine shaft is fixed in an axial direction so that it cannot turn, by means of a clamping tool, and in which the front end bearing housing or LP compressor shaft component, after a suitable lifting tool has been fastened to it, is drawn off the low-pressure turbine shaft, or pressed onto it, especially using a hydraulic power pressure tool.

Advantageously the clamping tool is fastened on the one hand to a rear end disc of the low-pressure turbine shaft and on the other hand to the housing structure of the OGVs (= outlet guide vanes = ring diffusor) of the low-pressure turbine.

A further aspect of the present invention is directed to a clamping tool for the performance of the (dis-)assembly method, in which a strap-shaped cross piece, which carries centrally a disc section matched to the lowpressure turbine shaft end disc and at its ends plates shaped as the segments of a circle, which match the housing structure o_f the OGVs, each with through holes for screw bolts.

An example method of the present invention will now be discussed in greater detail with reference to the attached drawings in which:

Figures 1 to 3 show longitudinal sectional views of different is stages of the dismantling process for an engine; and Figures 4a and 4b show a side and top view of a clamping tool which can be used in accordance with the present invention in greater detail.

In Figure 1 an aircraft engine 1 is shown in its entirety in a longitudinal section in a horizontal position. In this horizontal position the aircraft engine 1 can for instance be attached to the wing of an aircraft or lie on a suitable stand, not shown, (especially in the case of first assembly or production) 4 The aircraft engine 1 is constructed in the normal manner, that is to say a high pressure compressor 2b is connected onto a front end low-pressure (LP) compressor 2a (or fan), and is followed by an annular combustion chamber 3, whose hot gases are f irst taken to a high pressure turbine 4b and from there out through a low-pressure turbine 4a. As normal the turbine discs carrying the rotor blades of the low-pressure turbine are arranged on a low-pressure turbine shaft 5, which drives the lowpressure compressor 2a, (and actually connected either directly or via a LP shaft component or fanshaft, to the low-pressure turbine shaft 5), so that the rotor blades of the LP compressor (-in the aircraft engine 1 shown here this low-pressure compressor 2a is formed as a so- called fan-) similarly. sit on the low-pressure turbine shaft 5. The aircraft engine 1 shown here is a so-called twin shaft motor, whereby the front end and also the backward end parts of the housing 6 of the aircraft engine 1 are already separated in the representation according to Figures 1 to 3.

Similarly, there are as normal two bearing housings 7a, 7b provided for the low-pressure turbine shaft 5, furthermore the so-called LP Compressor shaft component or fanshaft is. also identified with the reference number 7a. The first front end bearing housing or LP Compressor shaft component 7a is in the region of the low-pressure compressor 2a or fan, the second rear end bearing housing 7b in the region of the low-pressure turbine 4a. The detailed construction of these bearing housings 7a, 7b is not important for the present invention, so that the very reduced representation is sufficient.

For servicing purposes it can be necessary to dismantle the front end bearing housing or LP compressor shaft component 7a, which is the subject of the present invention.

In the first stage of the dismantling method according to the present invention, which is shown in Figure 1, the low pressure turbine shaft 5 is firmly fixed using a clamping tool 8 in the axial direction. so that it cannot rotate. By the application of this clamping tool 8, whose details will be described later, the low-pressure turbine shaft 5 is held immovably in the housing 6 of the aircraft engine 1, that is to is say the low-pressure turbine shaft 5 can neither rotate about its axis 9, nor can the low-pressure turbine shaft 5 be moved in the axial direction 9 by the application of force within reasonable limits.

This non rotatable fixing of the low-pressure turbine shaft 5 permits the front end bearing housing or LP compressor shaft component 7a to be drawn off the low-pressure turbine shaft 5.

In accordance with Figure 2 a suitable lifting tool 10 is first fastened to the bearing housing or LP compressor shaft component 7a, for example by screwing, after the screwed connections between the bearing housing 7a and the housing 6 of the aircraft engine or the corresponding connections of the LP compressor shaft component 7a have previously been undone. The lifting tool 10 can then be matched to the individual geometries and outline conditions; the lifting tool 10 is here constructed as a U-shaped transom, which is held from above by a crane hook 11, alternatively however a suitable arm can engage from below in a matching part of the lifting tool 10, for instance if the bearing housing or LP compressor shaft component 7a has to be dismantled from an aircraft standing in the open air.

In the next step, which is shown in Figure 3, a power pressure tool 12 is applied to the bearing housing 7a or LP compressor shaft component 7a, which especially can be hydraulically actuated, and which is constructed in such a manner is that the bearing housing 7a or LP compressor shaft component 7a can be drawn off the low-pressure turbine shaft with the aid of this power pressure tool 12. In a similar fashion using a reversed procedure, that is during the assembly of the bearing housing 7a or the LP compressor shaft component 7a onto the low pressure turbine shaft 5, the bearing housing 7a or LP compressor shaft component 7a can be pressed onto the low-pressure turbine shaft 5 using this power pressure tool 12. Figure 3 shows a condition in which the bearing housing or LP compressor shaft component is already essentially withdrawn from the low-pressure, - 7 turbine shaft 5, compare the gap 13 against that in the condition shown in Figure 2. In the condition according to Figure 3 the bearing housing 7a or the LP Compressor shaft component 7a is held only by the lifting tool 10.

This dismantling procedure and the corresponding method for dismantling the front end bearing housing 7a or- LP compressor shaft component 7a is only possible in an essentially horizontal, and thus advantageous, position of the aircraft engine 1, because the low-pressure turbine shaft is firmly fixed in the first step in accordance with Figure 1, so that it can neither rotate nor move in an axial direction. This fixing using the clamping tool 8 mentioned above will now be described.

As Figures 4a, 4b show, this clamping tool 8 comprises a strap shaped cross piece 8a, which bears centrally, that is to is say in the middle, a disc shaped section 8b and at both its ends is provided with plates 8c in the form of segments of a circle.

Both in the plates 8c as well as in the disc section 8b through holes 14 are provided for screw bolts 15 (compared with Figures 1 to 3), not shown in Figures 4a, 4b.

The plates 8c are matched in their shape to the housing structure of the OGVs 16 of the low-pressure turbine 4a of the low-pressure turbine 4a. As readily apparent to a man. skilled in the art, these OGVs 16, that is to say the outlet guide vanes of the low-pressure turbine 4a, form a socalled ring diffusor, is whereby the housing structure of this ring diffusor, or the OGVs 16, is fixed as normal in the housing 6 of the aircraft engine 1. By means of these plates 8c the clamping tool 8 can be securely fastened to the housing 6 of the aircraft engine 1 using screw bolts 15, which are entered through the through holes 14 and screwed into the housing structure of the OGVs 16.

Similarly using screw bolts 15, which are explicitly shown in Figures 1 to 3, the low-pressure turbine-shaft 5 can further be securely fastened to the clamping tool 8, using the disc section 8b, which is matched in shape to the low-pressure turbine shaft end disc 5b. The screw bolts 15 are thus screwed on the one hand to the low-pressure turbine shaft end disc 5b and on the other to the clamping tool 8, whereafter the low-pressure turbine shaft 5 is f ixed as desired so that it can neither rotate nor move in an axial direction 9 with respect to the clamping tool 8. Since the latter is as already described fixed with respect to the housing 6, the low-pressure turbine shaft 5 cannot move at all with respect to the housing 6 of the aircraft engine 1, so that the dismantling procedure described or the assembly of the front end bearing housing 7a or the LP compressor shaft component can be carried out. This is - as has already been mentioned several times - especially possible in the horizontal position of the aircraft engine 1, so that it is no longer necessary for the dismantling of the bearing housing 7a or the - 9 LP compressor shaft component, first to bring this aircraft engine into a vertical position, whereby the dismantling of the bearing housing 7a or LP compressor shaft component 7a can also be carried out on aircraft engines 1 which remain fixed to the aircraft. Obviously a multiplicity of constructional details can be realised which deviate completely from the example of constuction shown, without departing from the scope of the present invention.

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Claims

Claims is A method of dismantling and/or assembling the bearing housing or

low- pressure (LP) compressor shaft component of the low-pressure turbine shaft of an aircraft engine provided at the f ront end, which normally bears a lowpressure turbine on its rear side, in which with the aircraft engine in an e ssentially horizontal position the low-pressure turbine shaft is fixed in an axial direction so that it cannot turn, by means of a clamping tool, and in which the front end bearing housing or LP compressor shaft component, after a suitable lifting tool has been fastened to it, is drawn off the low-pressure turbine. shaft, or pressed onto it, especially using a hydraulic power pressure tool.
2. A method according to Claim 1, in which the clamping tool is fastened on the one hand to a rear end disc of the lowpressure turbine shaf t and on the other hand to the housing structure of the WV5 (= outlet guide vanes ring diffusor) of the low-pressure turbine.
A method substantially as described herein with reference to the accompanying drawings.
4. A clamping tool for perf orming the method according to Claim 1 or Claim 2, in which a strap-shaped cross piece, 3.

which carries centrally a disc section matched to the low pressure turbine shaft end disc and at its ends plates shaped as the segments of a circle, which match the housing structure of the OGVs, each with through holes for screw bolts.

A clamping tool substantially as described herein with reference and as shown in Figure 4 of the accompanying drawings.