Abstract:
A door-type thrust reverser device for a turbojet engine nacelle is provided that includes a fixed structure, a mobile structure mobile with respect to said fixed structure, and at least one door mounted with the ability to pivot via pivots between a retracted position corresponding to the nacelle operating in direct-jet mode, and a deployed position corresponding to the nacelle operating in reverser-jet mode. The thrust reverser device includes a device for bleeding off some of a secondary or bypass airflow, which device is able to bleed off part of the secondary airflow from a duct through which the secondary airflow circulates and for conveying said bled-off airflow toward at least one pivot of the door, so as to cool areas on and/or around the door pivots.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/FR2015/050733, filed on Mar. 24, 2015, which claims the benefit of FR 14/53106 filed on Apr. 8, 2014. The disclosures of the above applications are incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a door-type thrust reverser, to a nacelle equipped with such a thrust reverser, and to a propulsion assembly comprising such a nacelle. 
       BACKGROUND 
       [0003]    The statements in this section merely provide background information related to the present disclosure and may not constitute prior art. 
         [0004]    An aircraft is propelled by one or several propulsion assemblies. Reference is made to  FIG. 1  illustrating an example of a propulsion assembly according to the prior art. A propulsion assembly  1  comprises a turbojet engine  3  housed in a tubular nacelle  5 . Each propulsion assembly is fastened to the aircraft by a mast, not represented, generally located under a wing or at the level of the fuselage. 
         [0005]    A nacelle presents generally a substantially tubular structure comprising an upstream section  7  defining an air inlet, a mid-section  9  intended to surround a fan of the turbojet engine, a downstream section  11  capable of accommodating a thrust reverser device  13 , and is generally terminated by an ejection nozzle the outlet of which is located downstream of the turbojet engine. 
         [0006]    Modern nacelles are intended to accommodate a bypass turbojet engine capable of generating, by means of the gas generator, a hot air flow F 1 , called primary flow, and by means of the blades of the rotating fan, a cold air flow F 2 , called secondary flow, which circulates outside of the turbojet engine  3  through an annular channel defining a flow path of the secondary air flow  15 . 
         [0007]    The flow path  15  is delimited between an inner fairing  17  of the turbojet engine and an outer envelope  19  accommodating the thrust reverser device. The two air flows F 1  and F 2  are ejected from the turbojet engine  3  from the rear of the nacelle. 
         [0008]    In the present application, the upstream and the downstream are defined with respect to the flow direction of air in the propulsion assembly in the direct jet operation, the air inlet being located upstream with respect to the ejection nozzle, located downstream of the nacelle. 
         [0009]    The role of a thrust reverser during the landing of an aircraft is to improve the braking capability of an aircraft by redirecting forward at least one portion of the thrust generated by the turbojet engine. In this phase, the thrust reverser obstructs the gas ejection nozzle and directs the ejection flow of the engine forwardly of the nacelle, thereby generating a counter-thrust which is added to the braking of the wheels of the aircraft. 
         [0010]    The means implemented to realize this reorientation of the flow vary depending on the thrust reverser type. However, in all cases, the structure of a thrust reverser comprises movable cowls displaceable between, on the one hand, a deployed position in which they open a passage in the nacelle intended to the diverted flow, and on the other hand, a retracted position in which they close this passage. Furthermore, these movable cowls may fulfill a diverting function or simply activate other diverting means. 
         [0011]    In cascade-type thrust reversers, for example, the movable cowls slide along rails so that, when moving backwards during the opening phase, they uncover cascade vanes disposed in the thickness of the nacelle. A system of connecting rods connects this movable cowl to blocking doors which are deployed inside the ejection channel and block the direct flow outlet. 
         [0012]    In door-type thrust reverser devices, such as the one which equips the nacelle represented in  FIG. 1 , each movable cowl pivots so as to block the flow and divert it and is therefore active in this reorientation. 
         [0013]    More specifically, a door-type thrust reverser device  21  comprises several doors  23  pivotally mounted so as to be able to switch, under the action of drive means, between a retracted position corresponding to an operation of the nacelle in direct jet, position according to which the doors  23  provide, with a fixed structure  31  of the thrust reverser device, an aerodynamic continuity of the nacelle, position illustrated in  FIG. 2 , and a deployed position causing an operation of the nacelle in reverse jet, position illustrated in  FIG. 3 , position according to which the doors  23  have pivoted so that a downstream portion  25  of each door obstructs at least partially the flow path  15  of the secondary air flow F 2 , and that an upstream portion  27  opens, in the downstream section  11  of the nacelle, a passage  31  allowing the air flows F 1  and F 2  to be partially ejected from the nacelle, then redirected upstream of the nacelle by the deployed doors  23 . 
         [0014]    When a door is in the retracted position, corresponding to all the flight phases with the exception of the landing phase, the door is in contact with the cold air flow passing through the flow path of the secondary air flow. 
         [0015]    When the door passes from its retracted position to its deployed position, a portion of the hot primary air flow passing through the turbojet engine enters into contact with the door. 
         [0016]    The door then undergoes a temperature rise, in particular at the level of the pivots of the door and adjacent areas  29  of the pivots of the door. Such a temperature rise considerably weakens the rigidity of the nacelle at these areas. 
         [0017]    In order to avoid such a structure weakening, the parts which compose the areas which surround the door pivots, and the door pivots themselves, are generally oversized, which considerably increases the mass of the nacelle. 
         [0018]    In addition, these parts are generally made of materials capable of withstanding such high temperatures, such as polybismaleimide-type thermosetting resins, or still aluminum 2219, which are very expensive materials. 
       SUMMARY 
       [0019]    The present disclosure provides a door-type thrust reverser device for an aircraft turbojet engine nacelle comprising:
       a fixed structure, and   a structure movable relative to said fixed structure, comprising at least one door pivotally mounted by means of pivots between a retracted position corresponding to an operation of the nacelle in direct jet, and a deployed position corresponding to an operation of the nacelle in reverse jet,   remarkable in that it comprises a device for collecting a portion of a secondary air flow, adapted to collect, when the thrust reverser is being deployed, a portion of the secondary air flow from an air path of the secondary air flow and to convey said collected air flow towards at least one pivot of the door, so as to cool the adjacent areas of the pivots of the door.       
 
         [0023]    Thus, by providing such a device for collecting a portion of the secondary air flow, adapted to collect a portion of the cold air flow circulating in the secondary flow path of the nacelle, then to convey the collected air towards a pivot of the door, the pivots of the door are permanently cooled, regardless of the position of the door, whether retracted or deployed. 
         [0024]    This advantageously allows avoiding the need to make the pivots of the door and the adjacent areas of these pivots in particularly heavy and expensive materials, which allows reducing both the mass of the nacelle and the manufacturing cost of door-type thrust reverser devices. 
         [0025]    According to features, which are all optional, of the of the present disclosure:
       the fixed structure comprises an outer wall and an inner wall in contact with the flow path of the secondary air flow and said inner wall comprises at least one ventilation aperture enabling a communication between the flow path of the secondary air flow and a space for channeling the collected secondary air flow, defined between said inner and outer walls;   the device for collecting a portion of the secondary air flow comprises at least one ventilation valve movable alternately between a closed position according to which it covers the ventilation aperture and an open position according to which it uncovers at least partially the ventilation aperture;   the ventilation valve is pivotally mounted on an axis substantially parallel to an axis transverse to a longitudinal axis of the thrust reverser device;   the device for collecting a portion of the secondary air flow comprises a device adapted to hold the ventilation valve in its closed position when the door is in the retracted position, and to enable the passage of said ventilation valve in its open position when said door is in the deployed position;   said device adapted to hold the ventilation valve in its closed position when the door is in the retracted position, and to enable the passage of said ventilation valve in its open position when said door is in the deployed position, in one form comprises at least one ramp secured to said ventilation valve, cooperating with said door when said door is in the retracted position and being shaped to enable the passage of the ventilation valve from its closed position to its open position when the door passes from its retracted position to its deployed position;   the door comprises a locking/unlocking device comprising at least one locking hook secured to said door, adapted to cooperate with a hook secured to the fixed structure of said thrust reverser device for a retracted position of said door, and the locking hook comprises a finger forming an extension supported by the ramp of the device for collecting a portion of the secondary air flow when the door is in the retracted position;   the ventilation valve comprises an elastic device adapted to permanently urge said valve in its open position, which allows an easy opening of the valve during maintenance operations, by a simple opening operation of the door of the thrust reverser;   the fixed structure of the thrust reverser device comprises at least one air outlet proximate to the door pivots shaped to evacuate at least one portion of the collected secondary air flow.       
 
         [0034]    The present disclosure also relates to a nacelle for an aircraft turbojet engine remarkable in that it comprises at least one door-type thrust reverser device as described herein. 
         [0035]    Finally, the present disclosure concerns a propulsion assembly for an aircraft comprising a turbojet engine housed in a nacelle, remarkable in that the device for collecting a portion of the secondary air flow is positioned upstream of an ejection plane of the primary air flow of the turbojet engine. 
         [0036]    Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0037]    In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which: 
           [0038]      FIG. 1  illustrates a propulsion assembly comprising a nacelle equipped with a door-type thrust reverser device according to the prior art; 
           [0039]      FIG. 2  represents an isometric view of the thrust reverser device of  FIG. 1 , represented in the direct jet operation position; 
           [0040]      FIG. 3  is a view similar to that of  FIG. 2 , according to which the thrust reverser device is represented in the reverse jet operation position; 
           [0041]      FIG. 4  is an isometric view of the thrust reverser device according to the present disclosure, represented in the direct jet operation position; 
           [0042]      FIG. 5  is an enlarged perspective view representing a device for collecting a portion of the secondary air flow according to the present disclosure; 
           [0043]      FIGS. 6 and 7  are enlarged perspective views representing the unlocking kinematics of the doors of the thrust reverser device according to the present disclosure; 
           [0044]      FIG. 8  is an enlarged perspective view illustrating the conveying of the collected air flow in the secondary flow path according to the present disclosure; and 
           [0045]      FIG. 9  is a perspective view representing the thrust reverser device in the reverse jet operation position. 
       
    
    
       [0046]    The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way. 
       DETAILED DESCRIPTION 
       [0047]    The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features. 
         [0048]    It is to be noted that in the description and in the claims, the terms “upstream” and “downstream” should be understood with reference to the circulation of the air flow inside the propulsion assembly formed by the nacelle and the turbojet engine, that is to say from the left to the right with reference to  FIGS. 1 to 9 . 
         [0049]    Similarly, the expressions “inner” and “outer” will be used without limitation with reference to the radial distance relative to the longitudinal axis of the nacelle, the expression “inner” defining an area radially closer to the longitudinal axis of the nacelle, as opposed to the expression “outer.” 
         [0050]    Moreover, in the description and in the claims, in order to clarify the description and the claims, the terms longitudinal, vertical and transverse will be adopted without limitation with reference to the direct trihedron L, V, T indicated in the figures, the longitudinal axis L of which is parallel to the longitudinal axis  51  of the nacelle represented in  FIG. 4 . 
         [0051]    Furthermore, in all figures, identical or similar reference numerals represent identical or similar members or sets of members. 
         [0052]    Reference is made to  FIG. 4 , representing the door-type thrust reverser device  21  according to the present disclosure in the direct jet operation position. 
         [0053]    The door-type thrust reverser device, hereinafter called “the thrust reverser,” comprises a fixed structure  31  and a structure  33  movable relative to said fixed structure. 
         [0054]    The fixed structure  31  is constituted by a beam of the thrust reverser, comprising an inner wall  35  in contact with the flow path  15  of the secondary air flow (visible in  FIG. 1 ), and an outer wall  37  (hidden in  FIG. 4 , visible in  FIG. 2 ) separated from the inner wall by a space  38 . 
         [0055]    In turn, the movable structure  33  comprises several doors  23 , for example two, pivotally mounted by means of pivots  39  between a retracted position according to which they provide, with the fixed structure  31  of the thrust reverser, an external aerodynamic continuity of the nacelle, corresponding to an operation of the nacelle in direct jet, position represented in  FIG. 4 , and a deployed position according to which it creates a passage in the nacelle, corresponding to an operation of the nacelle in reverse jet, position represented in  FIG. 9 . 
         [0056]    Holding the doors in the retracted position is achieved by means of an S-shaped hook  32  (visible in  FIG. 5 ) mounted on the fixed structure  31  of the thrust reverser, cooperating at each of its ends with a locking hook  34  secured to each of the doors. The hook  32  is pivotally mounted, by means of an actuation means, so that pivoting of the hook  32  releases the locking hooks  34  of the doors, thereby enabling the passage of the doors from a retracted position to a deployed position. 
         [0057]    As represented in  FIG. 1 , in the direct jet operation position, the cold air flow F 2 , generated by means of the blades of the rotating fan of the bypass turbojet engine housed in the nacelle, circulates in the annular channel defining the flow path  15  of the secondary air flow and is ejected downstream of the nacelle. 
         [0058]    According to the present disclosure, the thrust reverser comprises a device  41  for collecting a portion of the secondary air flow, adapted to collect a portion of the secondary air flow from a flow path of the secondary air flow and to convey said collected air flow towards at least one pivot of the door. 
         [0059]    The thrust reverser device may equip a nacelle supporting a bypass turbojet engine, and the device for collecting a portion of the secondary air flow is positioned upstream of an ejection plane of the primary air flow of the turbojet engine, which allows collecting only the cold air, not mixed with the hot primary air flow coming from the turbojet engine. 
         [0060]    Reference is made to  FIG. 5 , illustrating an enlargement of the area V of  FIG. 4 . 
         [0061]    According to the present disclosure, the inner wall  35  comprises, for each of the beams of the fixed structure of the thrust reverser, at least one ventilation aperture  43  forming a communication between the flow path of the secondary air flow and the space  38  for conveying the collected secondary air flow. 
         [0062]    The ventilation aperture  43  may be obturated by a ventilation valve  45  pivotally mounted by means of a hinge  47  about an axis  49  substantially parallel to an axis transverse to a longitudinal axis  51  of the thrust reverser, represented in  FIG. 4 . 
         [0063]    The locking hook  34  of the door is secured to a finger  52  forming an extension of the locking hook. 
         [0064]    The finger  52  is supported, when the door is in the retracted position represented in  FIG. 5 , by a ramp  55  secured to the outer wall  53  of the ventilation valve  45 . 
         [0065]    The operation of the device  41  for collecting a portion of the secondary air flow will now be described. 
         [0066]    When the door is in the retracted position, position represented in  FIG. 5 , the ramp  55 , secured to the ventilation valve  45 , cooperates with the door of the thrust reverser by means of the finger  52 , thereby holding the ventilation valve  45  in a closed position according to which it obturates the ventilation aperture  43 . 
         [0067]    At this level, the secondary air flow circulating in the secondary flow path passes through the flow path and is ejected conventionally downstream of the nacelle. 
         [0068]    When the operation of the nacelle in reverse jet is controlled, the S-shaped hook  32  pivots about an axis parallel to a substantially vertical axis of the thrust reverser, which releases the locking hook  34  of the door, as represented in  FIGS. 6 to 8  to which reference is now made. 
         [0069]    When the S-shaped hook  32  pivots according to the arrow F 3  represented in  FIG. 6 , the locking hook  34  secured to the door is unlocked, which causes the passage of the door from its retracted position to its deployed position, according to the arrow F 4  represented in  FIG. 7 . 
         [0070]    When the door is displaced towards its deployed position, the finger  52  secured to the hook  34  is displaced along the ramp  55 , thereby releasing the ventilation valve  45 . 
         [0071]    The ventilation valve, in permanent contact with the secondary air flow flowing in the secondary flow path, pivots about the axis  49  of the hinge  47 , in the direction of the space  38  contained between the inner and outer walls of the fixed structure of the thrust reverser under the effect of the pressure generated by the secondary air flow. 
         [0072]    The ventilation valve  45  passes then from its closed position to its open position, thereby uncovering the ventilation aperture  43 . 
         [0073]    Alternatively, an elastic device such as a torsion spring may be mounted on the pivot axis of the ventilation valve so as to permanently urge the valve in its open position, which allows an easy opening of the valve during maintenance operations, by a simple opening operation of the door of the thrust reverser. 
         [0074]    When the ventilation valve is in its open position, the secondary air flow flowing in the secondary flow path then passes through the ventilation aperture  43 , as represented by the arrow F 5  represented in  FIG. 8 . 
         [0075]    Afterwards, the air flow collected from the secondary flow path is conveyed along the inner wall  35  according to the arrow F 6  of  FIG. 9 , towards the pivots  39  of the doors  23 , thereby allowing cooling off the pivots  39  and the adjacent areas  29  of the pivots. 
         [0076]    The adjacent areas  29  of the pivots comprise air outlets  57  shaped to evacuate at least partially the collected secondary air flow, according to the arrows F 7 . 
         [0077]    Thus, thanks to the present disclosure, the mass of the nacelle and the manufacturing cost of the door-type thrust reverser devices are considerably reduced in that heavy door pivots made of materials capable of withstanding the significant temperatures generated by the primary air flow coming from the turbojet engine can be avoided. 
         [0078]    It goes without saying that the present disclosure is not limited to the sole forms of the thrust reverser device, of the nacelle and of the propulsion assembly, described hereinabove only as illustrative examples, but it encompasses on the contrary all variants involving technical equivalents of the described means as well as their combinations if these fall within the scope of the present disclosure.