Abstract:
A cockpit oxygen supply device includes at least one oxygen mask which is conductively connectable to an oxygen tank, wherein at least one throughput measurement device is arranged in the flow path of the device. A breathing activity of the pilot and/or an undesired outflow from the mask may be recognized with the help of an evaluation device.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2008 057 991.2-22 filed Nov. 19, 2008, the entire contents of which are incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a cockpit oxygen supply device with at least one oxygen mask conductively connectable to an oxygen tank. 
     BACKGROUND OF THE INVENTION 
     Cockpit oxygen supply devices are common in aircraft, in order to supply the cockpit crew with oxygen in the case of decompression of the cockpit. Such oxygen supply devices as a rule comprise at least one oxygen tank, to which several oxygen masks are connected, wherein the number of the oxygen masks connected to the oxygen tank is usually directed to the number of persons acting in the cockpit. 
     With the oxygen supply devices of this type which have been known until now, operating errors often lead to the oxygen inadvertently being let off out of the oxygen tanks, so that often an inadequate oxygen pressure prevails at the oxygen masks in a case of need. Such an inadequate pressurisation of the oxygen masks, although being displayed visually by way of mechanical switch logics on the oxygen masks and their storage containers, this display however disadvantageously is only effected when the cockpit oxygen supply device is no longer operational or only operational to an insufficient degree, and in the most unfavourable case, an aborting of the flight for refilling the oxygen tank with a correspondingly long airport stay is required. 
     SUMMARY OF THE INVENTION 
     Against this background, it is the object of the invention to provide a cockpit oxygen supply device which permits an improved functional monitoring. 
     The cockpit oxygen supply device according to the invention comprises at least one oxygen mask which may be conductively connected to an oxygen tank. The basic idea of the invention is to arrange at least one throughput measurement device in the flow path from the oxygen tank to the inner space of the mask body of the oxygen mask, with which throughput measurement device an unintended flow of oxygen out of the oxygen tank may be immediately recognized. This puts the cockpit crew, as the case may be, in the position of preventing a further outflow of oxygen by way of suitable measures, and in this manner, of avoiding the otherwise necessary aborting of the flight for refilling the oxygen tank. 
     Apart from the timely recognition of an outflow of oxygen from the cockpit oxygen supply device due to a fault, the throughput measurement device, in situations in which an oxygen supply of the cockpit crew is necessary by way of the cockpit oxygen supply device, also advantageously permits their proper use by way of the persons occupying the cockpit. For this, the throughput measurement device is usefully signal-connected to means for detecting a breathing activity. I.e. the throughput measurement device advantageously communicates with such means, with which one may ascertain whether the throughput values detected by the throughput measurement device are constant, which indicates a non-use of the cockpit oxygen supply device, or whether these throughput values change depending on breathing frequency and/or breathing depth, thus indicate a proper use of the cockpit oxygen supply device. 
     Particularly advantageously, the means for detecting the breathing activity form a part of the flight control system of the aircraft. In this context, one makes use of the fact that the breathing behaviour of the cockpit crew changes in certain flight situations. Thus for example the breathing frequency rises on descent. Advantageously, with the help of the means for detecting the breathing activity, it is possible to check the data which is determined by the flight control system and relates to the flight condition of the aircraft, by which means the flight safety may be further increased. 
     Given a faulty outflow of oxygen from the oxygen supply device as well as given a non-use of the oxygen supply device when this should actually be used, it is typically useful for the cockpit crew to be made aware of these facts. For this purpose, the throughput measurement device may advantageously be signal-connected to an alarm device. This alarm device may be designed in a manner such that it produces an acoustic warning signal and/or visual warning information in the situations specified above, wherein this signal or information then prompts the cockpit crew to rectify the error. 
     The throughput measurement device of the cockpit oxygen supply device according to the invention may basically have all types of sensors, which are suitable for detecting a volume flow in the flow path of the oxygen supply device. Preferably however, a differential pressure sensor is provided for determining the volume flow or for detecting the throughput of oxygen through the device. Usefully, this differential pressure sensor is designed in a manner such that it produces electrical or electronic measurement signals. Hereby, it may be the case of analog or digital measurement signals, which are led further to an electrical or electronic control. This control may be part of a throughput measurement device or it may hereby be the case of avionics which are usually present in aircraft. The evaluation of these signals is effected in the control device, wherein, as the case may be, an alarm device which may be part of the control, is prompted to issue an alarm signal. 
     A further advantageous design of the cockpit oxygen supply device according to the invention envisages arranging an orifice plate (orifice) in the flow path, for producing a pressure difference in this flow path from the oxygen tank to the oxygen mask, said pressure difference preferably being detectable by a differential pressure sensor. Thus a cross-sectional narrowing may be provided in the flow path, at which narrowing the flow speed through the flow path increases, wherein the oxygen pressure reduces downstream of the cross-sectional narrowing, so that a difference between the oxygen pressure in front of the orifice and the oxygen pressure behind the orifice arises. 
     In order to be able to assign a non-use of the cockpit oxygen supply device to a certain member of the cockpit crew, preferably a throughput measurement device is arranged upstream of each oxygen mask of this cockpit oxygen supply device. With regard to this, a design with which at least one conduit branching is provided in a feed conduit connected to the oxygen tank at the exit side is advantageous, wherein this branching comprises a flow inlet and two flow outlets in each case leading to an oxygen mask, wherein a differential pressure sensor is assigned to each flow outlet and whereby in the context of the invention, a differential pressure sensor is to be understood as any differential pressure recognition. Typically, with more than two cockpit crew positions, one may provide a further such conduit branching or the conduit branching comprises more than two flow outlets. 
     Advantageously, in each case the flow inlet and a flow outlet of the conduit branching form pressure chambers of a differential pressure sensor, which are separated from one another by way of a membrane. Advantageously, a cross-sectional narrowing of the flow path is provided at the transition of the flow inlet to the flow outlet, for producing different pressures in the two pressure chambers of the differential pressure sensor. 
     The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a cockpit oxygen supply device in a simplified block diagram; and 
         FIG. 2  is a conduit branching of the cockpit oxygen supply device according to  FIG. 1 , in a schematic longitudinal section. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings in particular, the cockpit oxygen supply device represented in  FIG. 1  is designed for the oxygen supply of four members of a cockpit crew of an aircraft. It comprises an oxygen source in the form of an oxygen tank  2 , which is conductively connected via a conduit  4  connected to its oxygen outlet, to a distributor  6 . On the exit side of the oxygen tank  2 , a pressure reducer  8  is arranged in the usual manner in the conduit  4 , with which pressure reducer the tank pressure of the oxygen tank  2  is reduced at least to a medium pressure. 
     The conduit  4  branches at the distributor  6  into two conduit lines  10  and  12 . The conduit line  10  ends at a conduit branching  14 . Corresponding to this, the conduit line  12  ends at a conduit branching  16 . Both conduit branchings  14  and  16  in each case have two flow outlets, wherein oxygen masks  18  and  20  are connected to the flow outlets of the conduit branching  14 , and oxygen masks  22  and  24  are connected to the flow outlets of the conduit branching  16 . 
     In each case, a differential pressure sensor, with which an outflow of oxygen from the respective flow outlet is detected via a differential pressure, and which is not shown in  FIG. 1 , is provided on each of the flow outlets formed on the conduit branches  14  and  16 . The pressure values detected at the conduit branching  14  are led further via a signal lead  15  to an evaluation device  19 . Correspondingly, the pressure values determined at the conduit branching  16  are transferred likewise by way of a signal lead  17  to the evaluation device  19 . The pressure values are evaluated in the evaluation device  19 , which e.g. may be part of the avionics of the aircraft, and a suitable acoustic and/or visual alarm is activated via a signal lead  21  at an alarm device  23  in the case of incorrect pressure values. 
       FIG. 2  in a detailed manner shows the construction of the conduit branching  14  which is designed in an identical manner to the conduit branching  16 . The conduit branching  14  has the shape of a T-piece, wherein two flow outlets  26  and  28  are arranged aligned perpendicularly to a flow inlet  30 . In the conduit branching  14 , a flow channel  32  departing from the flow outlet  30  crosses a flow channel  34 , wherein a branch  34   a  of the flow channel  34  leads to the flow outlet  26 , and a branch  34   b  to the flow outlet  28 . A cross-sectional narrowing which forms an orifice  36 , is formed where the flow channel  32  merges into the branch  34   a  of the flow channel  34 , in the flow path from the flow channel  32  to the flow channel  34 . In a corresponding manner, a cross-sectional narrowing at the transition from the flow channel  32  to the branch  34   b  of the flow channel  34  forms an orifice  38 . 
     Two cavities  40  and  42  are formed in the conduit branching  14 , at opposite sides of a middle plane A of the flow channel  32 , which is aligned parallel to the cross-sectional area of the flow channel  34 , and in each case on the side of a middle plane B of the flow channel  34 , said side being distant to the flow inlet  30  and being aligned parallel to the cross-sectional area of the flow channel  32 . These cavities  40  and  42  are separated by a membrane  44  or  46  into two halves, wherein the halves of the cavity  40  form chambers  48  and  50 , and the halves of the cavity  42  form chambers  52  and  54 . 
     The chamber  50  of the cavity  40  is conductively connected via a channel  56  to the flow channel  32  and thus to the flow inlet  30 . In an analogous manner, the channel  52  of the cavity  42  is conductively connected via a channel  58  to the flow channel  32  and thus also to the flow inlet  30 . A channel  60  connects the chamber  48  of the cavity  40  to the branch  34   a  of the flow channel  34 , whilst the chamber  54  of the cavity  42  is conductively connected by way of a channel  62  to the branch  34   b  of the flow channel  34 . In this manner, the chambers  48  and  50  form the pressure chambers  48  and  50  of a first differential pressure sensor, and the chambers  52  and  54  form the pressure chambers  52  and  54  of a second differential pressure sensor. 
     With respect to the middle plane A of the flow channel  32 , in each case a further cavity  64  or  66  is arranged on the outside of the cavity  40  and of the cavity  42  respectively. Three electrical strip conductors  68 ,  70 ,  72  are led into the cavity  64 . A two-way switch  74  is arranged on the middle strip conductor  70 , and may be switched such that in a first switch position the strip conductors  70  and  72  form a common flow circuit, and in a second switch position the strip conductors  68  and  70  form a common flow circuit. Corresponding to this, three strip conductors  76 ,  78  and  80  are also led into the cavity  66 , wherein a two-way switch  82  is arranged on the middle strip conductor  78  and in a first switch position connects the strip conductors  76  and  78  to one another, and in a second switch position connects the strip conductors  78  and  80  to one another. 
     If oxygen coming from the flow inlet  30  flows through the orifice  36 , then the pressure of the oxygen behind, i.e. downstream of the orifice, reduces. Accordingly, the pressure chamber  48  is impinged with a lower pressure than the pressure chamber  50 . The result of this is that the membrane  44  everts in the direction of the inner wall of the pressure chamber  48 , which is arranged opposite it. By way of this, a peg  84  which is movably guided through the wall between the pressure chamber  48  and the cavity  64 , is moved by the membrane  44  in a manner such that the two-way switch  74  coupled in movement with the peg  84  changes its switch position. In a similar manner, the membrane  46  everts in the direction of the outer wall of the pressure chamber  54 , which lies opposite it, by which means a plug  86  which is movably guided through the wall between the pressure chamber  54  and the cavity  66 , is moved such that the two-way switch  82  coupled in movement thereto likewise changes its switch position. The change of the switch position of the two-way switches  74  and  82  is detected by the evaluation device  19 , to which the strip conductors  68 ,  70 ,  72 ,  76 ,  78  and  80  are connected, whereupon an optical and/or acoustic alarm signal may be produced by an alarm device, which is likewise not shown and which may be a constituent of the control or which may be signal-connected to the control. 
     While specific embodiments of the invention have been described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles. 
     APPENDIX 
     List of Reference Numerals 
     
         
           2 —oxygen tank 
           4 —conduit 
           6 —distributor 
           8 —pressure reducer 
           10 —conduit line 
           12 —conduit line 
           14 —conduit branching 
           15 —signal lead 
           16 —conduit branching 
           17 —signal lead 
           18 —oxygen mask 
           19 —evaluation device 
           20 —oxygen mask 
           21 —signal lead 
           22 —oxygen mask 
           23 —alarm device 
           24 —oxygen mask 
           26 —flow outlet 
           28 —flow outlet 
           30 —flow inlet 
           32 —flow channel 
           34 —flow channel 
           34   a —branch 
           34   b —branch 
           36 —orifice 
           38 —orifice 
           40 —cavity 
           42 —cavity 
           44 —membrane 
           46 —membrane 
           48 —chamber, pressure chamber 
           50 —chamber, pressure chamber 
           52 —chamber, pressure chamber 
           54 —chamber, pressure chamber 
           56 —channel 
           58 —channel 
           60 —channel 
           62 —channel 
           64 —cavity 
           66 —cavity 
           68 —strip conductor 
           70 —strip conductor 
           72 —strip conductor 
           74 —two-way switch 
           76 —strip conductor 
           78 —strip conductor 
           80 —strip conductor 
           82 —two-way switch 
           84 —plug 
           86 —plug 
         A—middle plane 
         B—middle plane