Abstract:
A device for cleaning, for example degritting or desanding, a turbomachine module comprising: (i) means for isolating bearings of the module, by containment in a closed enclosure; (ii) means for overpressurising said enclosure; (iii) means for stripping material deposited in the walls of annular recesses of the module; and (iv) means for sucking up the material thus stripped.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a device for cleaning a turbine engine module, and in particular a device for de-sanding or de-gritting this module. 
       PRIOR ART 
       [0002]    When operating in some geographical regions, a turbine engine may absorb a certain amount of sand which agglomerates in the internal cavities of the turbine engine and in particular its low-pressure turbine, via the various ventilation channels. This mixture may then adhere to the internal walls of the turbine engine, downstream of the combustion component. 
         [0003]    The layer thus formed on said walls consists of both fine sand particles and an agglomerate of compacted contaminated sand. The presence of this layer makes it difficult or even impossible to visually inspect certain parts of the turbine engine during maintenance operations, in particular low-pressure and high-pressure turbines. There is also a risk that these particles may damage some bearings in the turbine engine, which are components very sensitive to contamination. 
         [0004]    Access to the internal space of the turbine engine is restricted and makes it difficult to clean the walls concerned, which makes it necessary to carry out lengthy and expensive dismantling of the various parts of the turbine engine in order to be able to clean them. 
         [0005]    A turbine engine comprises a plurality of major modules that are each composed of a plurality of sub-modules. Thus a turbine engine may comprise a major low-pressure turbine module that comprises three sub-modules, a first sub-module comprising the rotor and stator of the turbine, a second sub-module comprising the low-pressure shaft, and a third sub-module comprising an exhaust casing. This major module comprises rotor discs that define between them annular cavities that are difficult to access and therefore difficult to clean. In the prior art, it is therefore in general necessary to at least partially dismantle the first sub-module in order to facilitate access to the walls of the inter-disc cavities. This does however have numerous drawbacks in terms of duration and cost of the cleaning operation. This is because the duration of the cleaning operation is prolonged by the duration of dismantling the sub-module. Moreover, the criteria for inspecting a dismantled module or sub-module are stricter than those of an assembled module or sub-module. The operations of inspecting the dismantled components are therefore longer than those of assembled components, which further prolongs the duration of the cleaning operation. 
         [0006]    One solution to this problem would consist of performing a cleaning operation directly on a module or sub-module, while protecting the sensitive components of the module or sub-module, such as the bearings. However, there do not currently exist any satisfactory technologies for providing optimum and effective protection of the bearings. 
         [0007]    The present invention provides a simple, effective and economical solution to this need. 
       DISCLOSURE OF THE INVENTION 
       [0008]    The invention proposes for this purpose a device for cleaning, and in particular for de-sanding or de-gritting, a turbine engine module, this module comprising rotor discs defining between them at least one annular cavity to be cleaned, these discs extending around at least one bearing, the device being characterised in that it comprises:
       means for isolating said at least one bearing by confinement in a closed enclosure which is intended, at least in part, to be surrounded by said at least one annular cavity to be cleaned,   means for establishing an excess pressure in said enclosure,   means for removing material deposited on at least one wall of said at least one cavity in the module, for example by spraying compressed air onto this wall, and   means for suctioning removed material.       
 
         [0013]    According to the invention, the bearing or bearings of the module are protected since they are confined in a closed enclosure in which an excess pressure is established. In the present application, “excess pressure enclosure” means an enclosure in which a pressure higher than the pressure outside the enclosure prevails, it being possible for this external pressure to be ambient pressure. The material removed from the module therefore remains outside the enclosure and therefore cannot contaminate the bearings and its environment close to the module, which makes it possible to clean the module (such as a major module or at least one sub-module) without prior dismantling. 
         [0014]    Advantageously, the confinement means comprise two annular members configured so as to be mounted coaxially in front of and behind the module respectively. 
         [0015]    Preferably, each of these members comprises annular sealing means configured so as to cooperate with an annular element of the module. 
         [0016]    A first of these members may comprise an annular skirt which is made of a resilient material (such as elastomer) and is elastically deformable between a first position in which it is substantially cylindrical and a second position in which it is substantially frustoconical and is capable of cooperating, by means of its external periphery, with a first annular element of the module, such as the internal periphery of a rotor disc. 
         [0017]    This first member may comprise a body made of plastics material. This member is thus relatively light, which facilitates manipulation thereof. The body of the member may be shaped so as to match the shape of components of the module. It may for example comprise a tubular part intended to extend around a shaft portion of the module. This first member is preferably a rear or downstream member, that is to say it is mounted to the rear of or downstream of the module. 
         [0018]    The first member may comprise an air chamber that is inflatable and radially expandable and is surrounded by the aforementioned annular skirt so that the inflation and radial expansion of the air chamber causes deformation of the skirt from its first to its second position. 
         [0019]    This air chamber may be equipped with a valve that is connected to one end of a hose, the opposite end of which is located substantially at one end of the first member. In the aforementioned case where the first member is mounted to the rear of or downstream of the module, the opposite end of the hose is preferably located at the rear end of the first member so as to facilitate connection of this end to means for inflating the component, such as a pump. 
         [0020]    A second of the members may comprise a cylindrical sleeve configured so as to receive a shaft of the module. This sleeve may comprise a first closed end and a second end comprising means for fixing to a second annular element of the module, such as a cylindrical wall of the module, for example by fitting together. 
         [0021]    This second member is preferably a front or upstream member, that is to say it is mounted at the front or upstream of the module. The sleeve of this member may be produced from a flexible material such as a fabric coated with a plastics material. This sleeve is preferably airtight. This member is thus relatively lightweight, which facilitates manipulation thereof. The dimensions of the sleeve such as its length and diameter depend in particular on those of the shaft to be protected. 
         [0022]    The second end of the sleeve is preferably connected to the internal periphery of an annular membrane, the external periphery of which comprises said means for fixing to the second element of the module, said membrane preferably being made of a resilient material, such as elastomer. 
         [0023]    The sleeve preferably comprises a pressure relief valve. This valve limits the pressure inside the sleeve and the aforementioned enclosure to a maximum value, which may be around 2 bar. 
         [0024]    The sleeve may comprise means for connecting to the means for establishing an excess pressure in the enclosure. These means for establishing excess pressure comprise for example a pump that can be configured to deliver compressed air at a pressure slightly greater (by a few tenths of a bar for example) than atmospheric pressure. 
         [0025]    The suction means preferably comprise a bell housing configured so as to be mounted coaxially with the module and comprising means for connecting to a suction unit, such as a vacuum cleaner. 
         [0026]    Advantageously, the cleaning device is installed in a closed ventilated room (or premises) in which the operation of cleaning the module takes place. The suction unit is preferably located outside the room and connected by the connection means to the bell housing of the device. These connection means then pass through a wall of the room, this wall advantageously being equipped with a valve. 
         [0027]    The bell housing may comprise at its top an opening for the sleeve to pass through. The bell housing thus surrounds the sleeve as well as the shaft of the module housed in the sleeve. 
         [0028]    The suction means may further comprise an annular plate that is coaxial with the bell housing, this plate being configured so as to be applied to the module and comprising means for rotationally guiding the bell housing about its axis. The bell housing is thus able to move in rotation relative to the plate. In the case where the plate is fixed to the module for conjoint rotation, it can be seen that the bell housing is able to rotate relative to the plate and the module and, conversely, that the plate and the module are able to rotate relative to the bell housing. The aforementioned sleeve is mounted on the module and turns with the module relative to the bell housing, in the opening located at the top of the bell housing. 
         [0029]    Advantageously, the bell housing comprises a window for access to said at least one annular cavity in the module and for manipulation of said removal means. This window may be formed by an angular sector that is missing from the bell housing. The bell housing may thus have an angular extent of 360°-P about its longitudinal axis, P being the angular extent of its window, which is for example between 90° and 150°. 
         [0030]    Preferably, the device further comprises a carriage comprising means for supporting and rotationally guiding the module about its longitudinal axis, which is oriented substantially vertically. This carriage is designed to support the mass of the module, which may be as much as several hundreds of kilograms. The cleaning operation can thus be carried out on this carriage, which is preferably equipped with wheels for moving the module, for example as far as the aforementioned closed and ventilated room. The carriage may be equipped with a removable handle or handles. Its rotational guidance means may comprise an annular platform supporting the module, which is mounted so as to be able to rotate freely on the carriage by means of at least one antifriction bearing. Rotation of the module placed on the platform may be caused manually by at least one operator and/or may be motorised (compressed air, electric motor, etc.). 
         [0031]    The present invention also relates to a method for cleaning, and in particular de-sanding or de-gritting, a turbine engine module, this module comprising rotor discs defining between them at least one annular cavity to be cleaned, these discs extending around at least one bearing, the method being characterised in that it comprises the steps consisting of: 
         [0000]    a) isolating said at least one bearing by confining it in a closed enclosure, which is intended, at least in part, to be surrounded by said at least one annular cavity to be cleaned,
 
b) establishing an excess pressure in said enclosure,
 
c) removing the material deposited on at least one wall of said at least one cavity in the module, for example by spraying compressed air onto this wall, and simultaneously suctioning the material thus removed.
 
     
    
     
       DESCRIPTION OF THE FIGURES 
         [0032]    The invention will be better understood and other details, features and advantages of the invention will emerge upon reading the following description given by way of non-limiting example and with reference to the accompanying drawings, in which: 
           [0033]      FIG. 1  is a schematic perspective view of a major low-pressure turbine module of a turbine engine, 
           [0034]      FIG. 2  is a schematic axial section of the major module of  FIG. 1 , without the exhaust casing, 
           [0035]      FIG. 3  is a highly schematic view of a cleaning device according to the invention, 
           [0036]      FIG. 4  is a cross section corresponding to that in  FIG. 2  and showing an enclosure confining the bearings of the major module of  FIGS. 1 and 2 , 
           [0037]      FIGS. 5 and 6  are a schematic perspective view and a schematic side view, respectively, of a first confinement member of an embodiment of the cleaning device according to the invention, 
           [0038]      FIG. 7  is a schematic perspective view of a second confinement member for the same embodiment of the device according to the invention, and 
           [0039]      FIG. 8  is a schematic perspective view of a plate and a suction bell housing for the same embodiment of the device according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0040]    Reference is made first of all to  FIG. 1 , which shows a major low-pressure turbine module  10  (termed module MMO3 in the case of a CFM56 engine) of an aircraft turbine engine. This major module comprises three sub-modules (termed sub-module “54”, “55” and “56” in the aforementioned example), a first sub-module  12  comprising the rotor and the stator of the turbine, a second sub-module  14  comprising the turbine shaft, and a third sub-module  16  comprising an exhaust casing. 
         [0041]      FIG. 2  shows a part of the sub-modules  12  and  14 , the exhaust casing therefore not being visible in this figure. The sub-module  12  comprises a plurality of rotor wheels between which annular rows of stator blades are interposed. Each rotor wheel comprises a disc  18  carrying, at its periphery, an annular row of blades. The discs  18  are arranged coaxially behind one another and comprise upstream and downstream annular flanges  20  for fixing to the flanges of the adjacent discs, as well as to the external periphery of a drive cone  22 . The internal periphery of the drive cone  22  is fixed to a journal  24  that is connected to the turbine shaft  26  of the sub-module  14  for conjoint rotation. 
         [0042]    The drive cone  22  comprises a first frustoconical wall  28  that is splayed in the downstream direction and connected by its upstream end to the upstream end of a second frustoconical wall  30  that is splayed in the upstream direction. The cone  22  comprises through-openings  32  for the circulation of air in the axial direction, which are here formed in its second frustoconical wall  30 . The annular zone connecting the first and second walls  28 ,  30  of the cone comprises a cylindrical rib  34  oriented upstream. An abrader carrier  36  is fixed upstream of the cone  22  and comprises a cylindrical wall  38  surrounded by the rib  34 . This cylindrical wall  38  carries an abradable coating on its internal cylindrical surface and comprises, on its external cylindrical surface, a radially outer downstream annular rim  40  for axial abutment on the upstream end of the rib  34 , and a radially outer upstream annular rim  42  that is free here. 
         [0043]    The journal  24  in this case supports two antifriction bearings  44 ,  46 . These antifriction bearings  44 ,  46  have diameters appreciably smaller than those of the discs  18 . 
         [0044]    Before an operation of visual inspection of the major module  10  or of the sub-modules  12  and  14  assembled together, it may be necessary to clean said module by de-gritting or de-sanding. Some zones of the module are, however, difficult to access. This is particularly the case with the inter-disc annular cavities  48  located upstream of the drive cone  22 . The lateral walls of the discs  18  and the lateral walls facing the flanges  20  of these discs may be covered with agglomerated material composed essentially of sand and possibly other contamination elements. The thick lines  50  in  FIG. 2  represent the zones where this material has a tendency to accumulate, reference numeral  52  designating the places that are particularly difficult to access. 
         [0045]    The present invention proposes a solution to this problem by means of a cleaning device  100 , one embodiment of which is shown schematically in  FIG. 3 . 
         [0046]    Essentially, the cleaning device  100  comprises:
       means  102 ,  104  for isolating the antifriction bearings of the module  110 , by confinement in an enclosure  106  that is intended, at least in part, to be surrounded by the annular cavities  108  in this module that are to be cleaned,   means  111  for establishing an excess pressure in said enclosure  106 ,   means  114  for removing material deposited on the walls of the cavities  108 , and   means  116  for suctioning material thus removed.       
 
         [0051]    The module  110  is either a major module  10  as described above (comprising the sub-modules  12 ,  14  and  16 , here referenced  112 ,  114  and  116  respectively), or the assembly comprising the sub-modules  112 ,  114 , the module  116  comprising the exhaust casing having been dismantled and removed from the major module. 
         [0052]    It will be noted that the module  110  is arranged vertically, that is to say its longitudinal axis X is oriented vertically. The module  110  rests on a support carriage  120 , as will be described in more detail hereinafter. 
         [0053]    The means  102 ,  104  for isolating the antifriction bearings of the module (such as the bearings  44 ,  46  shown in  FIG. 2 ) here comprise two independent members  102 ,  104  intended to be mounted behind (or below) the module  110  and in front of (or above) the module, respectively. These members  102 ,  104  are intended to cooperate with elements of the module in order to define the enclosure  106  confining the bearings. 
         [0054]    In the example shown, the enclosure  106  extends over the entire length of the module  110  and contains the whole of the sub-module  114 , that is to say the turbine shaft, and an internal peripheral part of the sub-module  112  comprising the bearings (or even also a peripheral part of the sub-module  116  if said sub-module is present). The internal peripheral part of the sub-module  112  is shown schematically here by dashed lines. 
         [0055]    It will be noted that the cavities  108  to be cleaned are located outside this enclosure  106  and are therefore freely accessible for the purpose of the cleaning thereof. Here, the cavities  108  extend around the enclosure  106 . 
         [0056]    The enclosure  106  is closed and relatively sealed, in particular airtight. It is intended to be connected to the means  111  for establishing excess pressure, so that the pressure of the air in the enclosure  106  is greater (by a few tenths of a bar, for example greater by 0.5 to 0.6 bar) than the pressure of the air outside the enclosure, it being possible for this external pressure to be ambient or atmospheric pressure. 
         [0057]    The means  111  for establishing excess pressure may comprise a source  122  of compressed air connected by a hose  124  and optionally a pressure gauge  126  to an opening  128  for supplying compressed air to the enclosure  106 . The air source  122  may be associated with an oil-removal/dehumidification system in order to ensure that the air supplied to the enclosure  106  is dry air, thus limiting the risks of corrosion of the module  110 . 
         [0058]    The means  114  for removing material deposited on the walls of the cavities  108  may be of the type spraying compressed air. These means  114  may comprise a compressed-air gun  130  that is connected by a hose  132  and optionally a pressure gauge  134  to a compressed-air source  136  (which delivers air at a few bar, for example at approximately 6 bar). The compressed air spray opening of the gun  130  may be equipped with a flexible and deformable rod  138  that can be inserted in the cavities  108  to be cleaned. This rod  138  comprises for example a tubular copper core covered with a protective sheath made of plastics material, this sheath being intended to protect the components of the module  110  likely to come into contact with the rod  138  during the cleaning operation. 
         [0059]    The means  116  for suctioning removed material that becomes detached from the walls of the cavities  108  here comprise a bell housing  140  that is mounted on the module  110 , coaxially therewith, and is connected by a flexible tube  142  to a suction unit  144 . The suction unit  144  comprises for example a vacuum cleaner, such as the one sold by the company Nilfisk under the reference CTS40L (equipped with a D460* category M particle filter). The air-suction rate is for example around 7020 litres/minute. 
         [0060]    The suction unit  144  is preferably equipped with a filter intended to retain the suctioned particles having a size greater than or equal to 5 μm, which corresponds substantially to the minimum size of the grains of sand likely to be removed from the cavities  108 . The grains of sand removed from the cavity  108  are thus collected in a filter and not discharged to the atmosphere, which is ecological. 
         [0061]    As explained above, the module  110  may be mounted on a carriage  120  during the cleaning operation. This carriage  120  is equipped with wheels  150  and handles  152 , preferably removable, to facilitate movement thereof. The carriage  120  comprises an annular platform  154  that supports the module and is mounted so as to rotate freely. Locking means  156  may be provided to rotationally lock the module relative to the platform  154 . Other locking means (not shown) may be provided to rotationally lock the platform  154  relative to the rest of the carriage  120 . 
         [0062]    The carriage  120  may further be equipped with means for adjusting the working height, that is to say the height of the module  110  after mounting on the carriage. Before it is mounted on the platform, a tool (not shown) is in general mounted at the rear of the module  110 , in particular to immobilise the rotor and the stator of the turbine and thus prevent their coming into contact with one another. The module  110  may be placed on the platform  154  by means of this tool and also be rotationally immobilised relative to the platform by means of this tool. 
         [0063]    As will be explained hereinafter, the bell housing  140  is able to rotate relative to the module  110 . An operator can thus rotate the module  110  about its axis X, relative to the carriage  120 , while keeping the bell housing  140  immobile. The following description will comprise a complete example of the method for cleaning the module  110  and the use of the device  100  according to the invention. 
         [0064]    As shown schematically in the drawing, the cleaning operation is preferably performed in a closed and ventilated room  160 , in which the cleaning device  100  according to the invention is housed. The room  160  is for example parallelepiped, the lateral walls of which carry:
       means, located inside the room  160 , for connecting the hose  124  and/or the pressure gauge  126  to the compressed-air source  122 , which is located outside the room,   means, located inside the room  160 , for connecting the hose  132  and/or the pressure gauge  134  to the compressed-air source  136 , which is located outside the room,   means  161 , located inside the room  160 , for connecting the tube  142  to the suction unit  144 , which is located outside the room; these connection means  161  may comprise a valve mounted in the wall of the room  160 .       
 
         [0068]    The room  160  is aerated and ventilated by the circulation of air. 
         [0069]      FIGS. 5 to 8  show a more specific embodiment of the cleaning device  100  according to the invention.  FIGS. 5 and 6 , and  FIG. 7 , show the aforementioned rear members  102  and front members  104 , respectively.  FIG. 8  shows the bell housing  140  and a plate  162  for supporting and rotationally guiding this bell housing  140 . 
         [0070]    Reference is made first of all to  FIGS. 5 and 6 , which show the rear member or shutter  102 , that is to say the member that is intended to be mounted at the rear of the module  110  (which is its bottom end in the position of the module as shown in  FIG. 3 ). 
         [0071]    This member  102  comprises a body  164 , preferably made of plastics material. This body  164  comprises two parts, front  166  and rear  168  respectively, which each have a tubular cylindrical shape, the front part having an outside diameter greater than that of the rear part. Each of these parts is intended to surround and protect a different element of the rear part of the module  110 . 
         [0072]      FIG. 4  shows the member  102  in the mounting position at the rear of the module  10 ,  110 . The smaller-diameter rear part  168  of the body  164  surrounds a rear turbine shaft portion, and the larger-diameter front part  166  of said body surrounds a cylindrical wall that is rigidly connected to the journal  24 . The rear part  168  is closed at its rear end by a radial wall. The rear part  168  is connected at its front end by another radial wall to the rear end of the front part  166  of the body. 
         [0073]    The front part  166  of the body comprises an annular ring  170  comprising, at its external periphery, a radially external annular groove for housing an inflatable air chamber  172 . The groove receiving the air chamber  172  is axially delimited by two radially external annular walls  174  of the ring  170 . When the air chamber  172  is not inflated or is only slightly inflated, it is completely housed in the groove in the ring  170 . When said chamber is inflated, it projects radially outside the groove in the ring  170 . 
         [0074]    An elastically deformable annular skirt  176  extends around the groove in the ring  170  and comprises a rear end fixed to the external periphery of the rear annular wall  174 . This skirt  176  is preferably made of elastomer and is intended to deform when the air chamber  172  is inflated, and expands radially towards the outside of the groove. The skirt  176  is thus movable between an idle position where it is substantially cylindrical and an elastically deformed position where it is substantially frustoconical, its front end then having a diameter greater than that of its rear end, as shown in  FIG. 6 . 
         [0075]    The air chamber  172  comprises a supply valve  178  that is connected to the end of a hose  179  that extends along the body  164  and the end of which opposite to the air chamber  172  is located at the rear end of the body and comprises an end piece  180  for connection to a pump (not shown) for inflating the air chamber. The hose  179  is fixed to the body by suitable means. The body  164  may comprise reinforcement means that are arranged between the ring and the front part (reference numeral  182 ) and between the front and rear parts of the body (not shown). 
         [0076]      FIG. 4  shows that, in the mounting position of the rear member  102  and when the skirt  176  is frustoconical (inflated air chamber  172 ), the skirt  176  may bear axially on the cone  22  and/or radially on the internal periphery of a disc  18  of the module  10 ,  110 . The skirt  176  has a dual function. It cooperates with the internal periphery of the disc  18 , on the one hand in order to provide a seal between the member  102  and this disc, and on the other hand to ensure that the member  102  is held relative to the disc and therefore the module  10 ,  110 . This is because the member  102  is mounted at the rear of the module by axial translation towards the module  10 ,  110 , until its skirt  176  bears axially on the cone  22 . The air chamber  172  is then inflated, which causes the elastic deformation of the skirt  176 . Said skirt can then come into abutment on the internal periphery of the disc  18  in order to prevent rearward axial withdrawal of the member  102 . If the module  110  is arranged vertically, as described above, the cooperation of the skirt  176  of the member  102  with the disc  18  prevents the member from dropping. The skirt also has the role of protecting the air chamber  172 . This abutment of the skirt  176  on the disc  18  is therefore sufficient to hold the member  102  in place on the module  10 ,  110 . 
         [0077]    Reference is now made to  FIG. 7 , which shows the front member or shutter  104 , that is to say the member that is intended to be mounted at the front of the module  110  (which is its top end in the position of the module as shown in  FIG. 3 ). 
         [0078]    This member  104  comprises a sleeve  184 , preferably made of flexible material, one end 186 of which is closed and the other end of which is connected to an annular membrane  188  that is preferably made of an elastically deformable material such as elastomer. The sleeve  184  is connected to the internal periphery of the membrane  188 , the external periphery of which comprises a cylindrical rim  190  for mounting on an element of the module  10 ,  110 , preferably by fitting together. 
         [0079]      FIG. 4  shows the member  104  in the mounting position in front of the module  10 ,  110 . The sleeve  184  extends around the turbine shaft  26  of the sub-module  114 , over the entire length thereof, and the membrane  188 , located here at the bottom end of the sleeve, which has its rim  190  engaged on the aforementioned cylindrical wall  38  of the module  10 ,  110  and preferably comprises a radially internal annular groove in which the external radial rim  42  of the wall  38  is engaged. This provides firstly a seal between the member  104  and the wall  38 , and secondly axial holding of the member  104  relative to the wall  38  and therefore the module  10 ,  110 . 
         [0080]    In the mounting position, the two members  102 ,  104  define, together with elements of the module, a closed and relatively sealed enclosure  106 . It can be seen in  FIG. 4  that the elements that are involved in the delimitation of the enclosure  106  are in particular the drive cone  22 , and in particular its first frustoconical wall  28 , and a part of the rotor of the sub-module  12 ,  112 . It can also be seen that the enclosure  106  comprises two parts, a bottom part  106   a  delimited between the rear member  102  and the second frustoconical wall  30  of the cone  212 , and a top part  106   b  delimited between the front member  104  and the second frustoconical wall  30  of the cone  22 . The parts  106   a ,  106   b  of the enclosure  106  communicate with each other, in particular via the through-openings  32  in the second frustoconical wall  30  of the cone  22 . The top part  106   b  of the enclosure comprises the space contained in the sleeve  184 . 
         [0081]    As can be seen in  FIG. 7 , the sleeve  184  comprises the aforementioned opening  128 , which is equipped here with an end piece  192  for connecting the enclosure  106  to the means  112  for establishing excess pressure, that is to say to the aforementioned source  122  for supplying compressed air at a pressure greater than that of atmospheric pressure outside the enclosure  106 . It is clear that the supply of compressed air and the excess pressure in the internal space of the sleeve  184  will establish excess pressure in the parts  106   a ,  106   b  of the enclosure  106 , because of their communication with each other. 
         [0082]    The sleeve  184  also comprises a pressure relief valve  194  that limits the pressure inside the enclosure  106  to a maximum value, such as 2 bar. The sleeve  184  further comprises, at its top end, a strap  196 , one end of which is fixed to the sleeve and the other end of which may comprise a Velcro® type system for fixing to the sleeve. This strap is advantageously used to hold and guide the hose  124 . 
         [0083]    The material of the sleeve  184  preferably comprises a fabric coated with an airtight plastics material. 
         [0084]    Finally, reference is made to  FIG. 8 , which shows part of the suction means  116  of the device  100  according to the invention, and in particular the suction bell housing  140  and the plate  162  for supporting and rotationally guiding the bell housing about its axis X. 
         [0085]    The plate  162  is annular and planar and is intended to be placed on the module  10 ,  110  at the front thereof, so as to cover the entrance to the turbine flow path, as shown in  FIG. 4 . It is thus intended to extend above the rows of rotor and stator blades of the turbine, its inside diameter preferably being less than the inside diameter of the blades, and its outside diameter preferably being greater than the outside diameter of the blades. 
         [0086]    The plate  162  comprises foolproofing means intended to cooperate with the module in order to ensure correct positioning of the plate relative to the module  110 . In the example shown, the plate  162  carries centring pins  198  that project on the bottom face of the plate and are intended to be engaged in openings in the module, such as openings for bolts to pass through. 
         [0087]    The plate  162  also comprises manipulation handles  200 . 
         [0088]    The plate  162  further comprises, on its internal periphery, a rail  202  for centring and rotationally guiding the bell housing  140  about the axis X. 
         [0089]    Here, the bell housing  140  is roughly hemispherical and is also divided into sectors, one bell-housing sector being missing in order to define a window  204  for access to the cavities  108  of the module  110  to be cleaned, and for manipulating the gun  130 . 
         [0090]    The bell housing  140  cooperates by means of its larger-diameter bottom end with the rail  202  located at the internal periphery of the plate  162 . The smaller-diameter top end or vertex of the bell housing defines a neck  206  for the shaft  26  of the sub-module  14  and the sleeve  184  of the member  104  to pass through. The neck  206  comprises a cylindrical wall of a length (along the axis X) that is sufficient to limit the risk of wear on the sleeve  184  when it rotates relative to the bell housing  140 . 
         [0091]    The window  204  in the bell housing  140  is laterally delimited by two walls  208  having a substantially radial orientation relative to the axis X. 
         [0092]    The bell housing  140  comprises an opening  210  for connecting to one end of the aforementioned flexible tube  142  ( FIG. 2 ), the opposite end of which is connected to the suction unit  144 . 
         [0093]    The plate  162  can be produced from plastics material, such as Teflon® (PTFE). The bell housing  140  (including its walls  208 ) is preferably made of a transparent material such as Plexiglass® (PMMA). The operator can thus view parts of the module  10 ,  110  during cleaning, through the material of the bell housing  140 . 
         [0094]    The device  100  according to the invention can be used in the following manner. In other words, a cleaning operation or method can take place as follows, using the device  100  according to the invention. 
         [0095]    The members  102 ,  104  are mounted one after the other on the module  10 ,  110 . The rear member  102  (with its air chamber  172  deflated or partially inflated) is mounted as indicated above, by engaging it at the rear of the module until its skirt  176  is in axial abutment on the cone  22 , and then inflating the air chamber  172  by means of a pump, so as to deform its skirt  176 , which then adopts a frustoconical shape and can come into abutment on the disc  18  in order to ensure the member  102  is held relative to the module  10 ,  110 . The front member  104  is mounted as indicated above, by fitting the sleeve  184  on the shaft  26  like a sock, and then fixing the rim  190  of the membrane  188  to the cylindrical wall  38  of the module  10 ,  110 . 
         [0096]    The module  10 ,  110  is then positioned on the carriage  120 , and in particular on the movable platform  154  of this carriage ( FIG. 3 ). The platform  154  is locked so as to prevent it from turning on the carriage during this operation. The module  10 ,  110  is then locked so as to rotationally lock it relative to the platform  154 , using the means  156  ( FIG. 3 ). The carriage  120  is next brought into the room  160  in which the cleaning operation is to be performed. The wheels  150  of said carriage are then locked in order to immobilise it in the middle of the room. The handles  152  of the carriage can be removed in order to facilitate the cleaning operation. 
         [0097]    The plate  162  is mounted around the sleeve  184  and placed and centred on the module  10 ,  110 , and then the bell housing  140  is mounted around the sleeve  184  and placed and centred on the plate  162 . One end of the flexible tube  142  is then engaged in the opening  210  in the bell housing  140  ( FIG. 8 ) and one end of the hose  124  is connected to the end piece  192  of the sleeve  184  ( FIG. 7 ). 
         [0098]    The operation of cleaning the cavities  108  of the module  10 ,  110  can then commence. The source  122  is activated so as to establish an excess pressure in the enclosure  106 . Owing to this excess pressurise, the rear member  102  is applied with a greater force to the disc  18  of the module, which thus contributes to the sealing in this region. Moreover, the sleeve  184  inflates and adopts a substantially cylindrical shape, and is surrounded, with a small radial clearance, by the neck  206  of the bell housing  140  ( FIG. 8 ). 
         [0099]    The suction unit  144  is started up, which creates a negative pressure in the bell housing  140 , intended to suction the material removed during cleaning, which material is then discharged through the tube  142  as far as the unit  144  located outside the room. 
         [0100]    The supply of compressed air to the gun  130  is activated and an operator can manipulate the gun in the window  204  of the bell housing  140  in order to remove the aforementioned material. For this purpose, the barrel  138  of the gun is inserted in each cavity  108  to be cleaned and the operator presses on the trigger of the gun  130  so that compressed air is sprayed onto the walls of the cavities, preferably in directions substantially tangent to these walls. The material removed by spraying compressed air is then immediately suctioned through the bell housing  140  and discharged through the tube  142 . The operator can use a tube brush to force the material to detach, this tube brush (not shown) preferably comprising nylon bristles in order not to damage the components of the module. The operator can also use a petroleum product in liquid form or soaked cloths in order to facilitate the removal of the sand and contamination elements. 
         [0101]    The operator can manually rotate the module  10 ,  110  on the carriage  120 . The bell housing  140  then remaining immobile and the sleeve  184  turning inside the bell housing  140  at the same time as the module  10 ,  110 . It can, however, be envisaged that this rotation be carried out by means of a motor. The tube  142  can be held in position by means of a telescopic arm (not shown) fixed to a wall of the room  160 . 
         [0102]    The operator is preferably equipped with full overalls, a noise-reducing headset and a pressurised mask throughout the duration of the cleaning operation. 
         [0103]    Naturally, the confinement means described above are adapted to the design of the module to be cleaned. It can thus be envisaged that the rear member  102  of these confinement means be replaced by simple rubber plugs intended to close openings of a tool mounted at the rear of the module, and for example at the rear of the exhaust casing of a major low-pressure turbine module. The use of a closure system for closing off the downstream part  12  of the module and the upstream part  16  of the module may also be necessary.