Abstract:
An outflow valve ( 10 ) for an aircraft has a frame ( 12 ) for arrangement in an opening ( 14 ) of an outer shell ( 16 ) of the aircraft, a first flap ( 18 ) pivotably arranged in the frame ( 12 ) for controlling a flow cross-section of at least one first inflow opening ( 24 ) and at least one outflow opening ( 15 ). To achieve a simplified construction of the ventilation system of the aircraft, the outflow valve ( 10 ) has a second inflow opening ( 26 ) configured to be closable by means of a drivable adjustable member ( 28 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A “SEQUENCE LISTING” 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an outflow valve for an aircraft comprising a frame to be disposed in an opening of an outer shell of the aircraft, a first flap pivotably arranged within the frame for controlling a flow cross-section, at least one first inflow opening and at least one outflow opening. The invention also relates to a method for controlling such an outflow valve. 
     2. Description of Related Art 
     Outflow valves of the initially mentioned type are used in aircraft to vent the cabin and to adjust the cabin pressure. When air uniformly flows into the cabin, a positive pressure relative to the outside of the aircraft is created within the cabin. The outflow valve of the initially mentioned type allows an adjustable amount of air per unit time to escape through its flow cross-section, which is determined by a flap. This is how the pressure in the interior of the aircraft is adjustable by means of the flap. 
     After landing it may be found that the cabin pressure in an aircraft has a substantial difference with respect to the pressure on the outside of the aircraft. If the cabin pressure is higher than the pressure on the outside, the doors of the aircraft would be suddenly thrown open by the air pressure upon opening. To avoid this risk the outflow valves of an aircraft are generally fully opened prior to opening of the doors to achieve pressure compensation. 
     The electronics of an aircraft are cooled by an airflow controlled in a similar manner to the cabin air by means of an inflow valve and an outflow valve. The amount of air necessary for cooling the electronics is often substantially larger than the amount of air necessary to ventilate the cabin. 
     To protect passengers against undesirable drafts, smells and noises in aircrafts, it is provided to substantially separate the airflows for fresh air supply of the cabin and for cooling of the electronics. The airflows for the main cabin, for example, and the aircraft electronics are thus vented via separate outflow valves. 
     Only in the case where one or more of the valves fail and remain closed (“failed closed”), the airflows are commonly vented via one of the remaining valves. To enable this, the individual valves must be designed to have a relatively large size. In the case of failure, the airflows may then be redirected in a manner unfavorable for passengers. 
     An outflow valve of the initially mentioned type is described in US 2004/0217317 A1. The outflow valve described there has a cylinder-shaped valve body and a flap defining a flow cross-section within the cylinder-shaped body and capable of closing off the cross-section. To improve the properties of the valve at small opening angles of the flap, walls have been inserted. 
     DE 197 13 125 C2 describes a method for regulating the cabin pressure in an aircraft and a stepped valve for use with said method. The stepped valve has a large flap to control an outflowing airflow. A smaller flap is inserted in the large flap for fine control of the airflow. 
     At large pressure differentials the airflow is controlled by means of the position of the small flap. If the pressure differential is small, the airflow is controlled by means of the position of the large flap. 
     BRIEF SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide an outflow valve of the initially mentioned type enabling a simplified construction of the ventilation system of an aircraft. 
     To solve this problem, an outflow valve of the initially mentioned type is suggested, which has a second inflow opening configured to be closable by means of a drivable adjustable member. 
     The outflow valve according to the present invention has the advantage, in particular, that it can combine two venting paths to a single venting opening in the outer shell of an aircraft. By these means the number of aerodynamically and structurally disadvantageous points on the outer shell of the aircraft is reduced. Furthermore, it is possible to vent airflows in a selective manner via a small number of outflow valves to thus reduce the complexity of the ventilation system. In the most advantageous case it is possible to fully eliminate some of the valves. 
     Advantageous embodiments are the subject matter of the dependent claims. 
     Advantageously, the frame has a contacting surface against which the adjustable member can come into contact to close off the second inflow opening. This improves the ease of manufacture. 
     In an advantageous embodiment, the adjustable member has a cylindrical shape, so that it may be inserted in a simple manner into an outflow valve having a cylindrical basic shape. 
     Advantageously, the contacting surface can have an annular shape to adapt to the shape of the adjustable member. 
     The adjustable member and the contacting surface can have a rectangular basic shape in an advantageous embodiment. Advantageously, the outflow opening has an essentially rectangular configuration. This can help to utilize energetic advantages of the outflow, for example during thrust recuperation. 
     The outflow opening can have an essentially circular or oval-shaped configuration. 
     The first flap is advantageously pivotable about an axle mounted in the frame. This enables the flap to be precisely oriented on the frame. 
     The first flap can have a pivotable second flap enabling a portion of the outflow opening to be opened while the first flap is closed. This enables particularly small flow cross-sections to be created in a simple manner. 
     In a further advantageous embodiment, the frame has a supply duct connected to it in a moveable manner, wherein a flexible attachment element can be provided to connect the frame and the supply duct. 
     Advantageously, the frame has recesses defining the second outflow opening. The assembly of the outflow valve is simplified by this one-piece configuration. 
     Advantageously, the frame has a converging constriction element. This constriction element creates a Venturi effect in the manner of a nozzle as it is flowed through creating a negative pressure in the area of the further inflow openings causing the airflows to be sucked off. Additional means for air transport can thus be eliminated. 
     Advantageously, exhaust air from an electronics area is supplied to the first inflow opening and cabin air is supplied to the second inflow opening. 
     Furthermore, a method for controlling the outflow valve according to the present invention is suggested, wherein, in a first flight phase, in which the aircraft is grounded and only moves at low speed, the first flap opens. This allows simple and rapid pressure compensation. In a second flight phase, in which the aircraft is airborne, the first flap can be closed, and the flow cross-section can be controlled by the second flap. This has the advantage that the airflow flowing at a particularly high speed due to the high pressure difference between the outside and the inside of the aircraft in flight can be more precisely controlled with a small cross-section. 
     The adjustable member can open the second inflow opening as required. This can be done both for pressure compensation and to support other outflow valves or to replace their function. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWINGS 
       The invention will be explained in more detail with reference to an exemplary embodiment schematically shown in the accompanying drawings, wherein: 
         FIG. 1  is a cross-section of an outflow valve according to an embodiment of the present invention during a first flight phase; 
         FIG. 2  is a view as in  FIG. 1  during a second flight phase; and 
         FIG. 3  is a view as in  FIG. 2 , wherein the adjustable member has opened the second inflow opening. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiment shown in  FIG. 1  of an outflow valve  10  comprises a frame  12  inserted in an opening  14  of an outer shell  16  of an aircraft. To simplify installation, a centering flange  16   a  is provided in the outer shell  16  at opening  14 , in which frame  12  is inserted. Frame  12  has an outflow section  12   b  defining a circular outflow opening  15 . 
     Outflow opening  15  is closable by means of a first flap  18 . First flap  18  is pivotable about a first axle (not shown), mounted on frame  12 . Depending on the position of first flap  18 , outflow opening  15  is opened to a certain degree. 
     A second flap  38  is provided in first flap  18 , by means of which an essentially rectangular section of outflow opening  15  can be opened, when first flap  18  is closed. 
     Frame  12  further has an inflow section  12   c  defining a first inflow opening  24  for the introduction of exhaust air  34  from the electronics of the aircraft. Inflow section  12   c  has a cylindrical configuration and has a constriction element  12   d  converging in the flow direction of exhaust air  34 . 
     Inflow section  12   c  has a circumferential mounting bead  12   e  at first inflow opening  24  on which an elastic connection element  30  is mounted, connecting inflow section  12   c  with a supply duct  32 . Exhaust air  34  is guided from the aircraft electronics to outflow valve  10  through supply duct  32 . Supply duct  32  in turn also has a mounting bead  32   a  to mount connection element  30 . 
     Frame  12  has recesses  12   f  between inflow section  12   c  and outflow section  12   b  for defining a second inflow opening  26 . Second inflow opening  26  allows cabin air  36  to flow out through outflow valve  10  in addition to exhaust air  34 . 
     Second outflow opening  26  is closable by means of an adjustable member  28  arranged in recesses  12   f.    
     Adjustable member  28  has a cylindrical configuration and is moveably arranged on the outer circumference of inflow section  12   c  and constriction element  12   d . Adjustable member  28  is adjustable in a direction y by means of a drive (not shown). If adjustable member  28  is adjusted, as shown in  FIG. 2 , so that it comes into contact against a contacting surface  13  of frame  12 , second inflow opening  26  is fully closed. 
     Frame  12  has a stop  12   g  at inflow section  12   c , which limits the movement of adjustable member  28  and thus defines a maximum opening of second inflow opening  26 . 
       FIG. 1  shows outflow valve  10  for the case in which the aircraft is grounded. Generally, the doors of the aircraft are not opened until the pressure difference between the inside and the outside has fallen to a few mbars. Due to the small pressure difference, the full area of outflow opening  15  is necessary to ensure rapid pressure compensation. To enable good pressure compensation of the aircraft electronics and the cabin with the ambient atmosphere, adjustable member  28  is raised up to stop  12   g , and first flap  18  is opened. 
     Exhaust air  34  flowing out through outflow valve  10  is accelerated in constriction element  12   d  due to the reduction in cross-section. Due to the Venturi effect, a negative pressure is created at the exit of constriction element  12   d , which sucks cabin air  36  through second inflow opening  26 . The mixed airflow consisting of exhaust air  34  and cabin air  36  can then flow out of the aircraft through fully opened outflow opening  15 . 
     If, however, as shown in  FIG. 2  the aircraft is in a second flight phase, for example, at 43,000 ft, a great pressure difference can be observed between the outside and the inside of the aircraft. In the present exemplary embodiment it is assumed, that a pressure of 770 mbars is present in the cabin and a pressure of 162 mbars is present outside of the aircraft. 
     In this flight phase, adjustable member  28  is closed and is in contact with frame  12 . Cabin air  36  is vented via other valves. 
     At this pressure difference, reliable and precise control of the outflowing amount of air is no longer ensured exclusively by means of first flap  18 . First flap  18  is therefore closed in this case. Instead, the flow cross-section of outflow opening  15  is defined by means of second flap  38 , which is pivotable about an axle  20 . The amount of outflowing air can thus be controlled by means of second flap  38 . 
     By the combined action of a plurality of outflow valves  10 , it is possible to control the airflows in the cabin of an aircraft (flow regulation). 
     Second flap  38  has a substantially smaller surface area than first flap  18 . Due to the smaller closure surface area, smaller forces are necessary to position second flap  38  than are necessary to position first flap  18 . The position of second flap  38  can thus be controlled more precisely than that of first flap  18 . 
     If there is a malfunction of any of the other valves via which cabin air  36  is vented, it is possible to raise adjustable member  28  and to thus vent cabin air  36  through outflow valve  10  in a controlled manner, as shown in  FIG. 3 . In this case outflow valve  10  replaces the function of the failed valves. 
     In a second embodiment, frame  12  has a groove having a form corresponding to adjustable member  28  in such a manner that adjustable member  28  contacts the bottom of the groove in the closed state. This increases the sealing effect in the closed state. 
     To further improve the sealing effect, a bulge is arranged at the bottom of the groove to reliably seal any spaces between adjustable member  28  and frame  12 . 
     Opening  14  can also have a polygonal or round shape. The precise shape of opening  14  can thus be adapted to each installation position and according to aerodynamic criteria, such as thrust recuperation. 
     It is also possible to connect adjustable member  28  and first flap  18  by means of a positive actuation mechanism, so that a position change of adjustable member  28  causes rotation of first flap  18 . 
     Outflow valve  10  according to the present invention combines a plurality of exhaust air paths in an aircraft and thus enables simple venting of the cabin even in case of individual valves failing, simple pressure regulation in the second flight phase, and rapid and efficient pressure compensation in the first flight phase.