Abstract:
A directional valve for a respirator product shall be improved with regard to a low flow resistance. To accomplish the object, two diaphragm-like valve disks ( 12, 13 ) abutting against one another at a central line of separation ( 16 ) that are attached to the valve housing ( 11 ) in a point-like manner and can be moved in a flap-like manner by the breathing gas stream are provided. A central web ( 19 ) at the valve housing ( 11 ), which runs along the line of separation ( 16 ) and support webs ( 21 ) additionally arranged on both sides, is used as a valve seat.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority under 35 U.S.C. §119 of German Patent Application DE 10 2010 008 923.0 filed Feb. 23, 2010, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention pertains to a directional valve for a respirator product. 
       BACKGROUND OF THE INVENTION 
       [0003]    A directional valve of the type mentioned in the form of an exhalation valve on a respirator mask has become known from DE 10 27 518. The directional valve consists of a valve lower part with a valve seat and a closing element held in the center by a web. To limit the lateral forces developing during deformation of the closing element, the closing element has a truncated-cone-shaped design and has disk-shaped sections offset against one another in a step-like manner. The drawback of the prior-art directional valve is that in the direction of flow through the closing element, only a part of the cross-sectional area is released, and, if the directional valve is within a breathing tube, the breathing gas is deflected through the closing element towards the tube wall, which increases the flow resistance. In the use of directional valves in closed-circuit respirators, low flow resistances are required in order to limit the breathing effort of the user of the device to a minimum. 
         [0004]    Closed-circuit respirators supply a user of the device with breathing gas when work has to be done in an environmental atmosphere with toxic gases. Within the closed-circuit respirator the breathing gas is guided in the closed circuit, wherein exhaled carbon dioxide is removed and then consumed breathing gas is replaced. To achieve a directed breathing gas transport within the breathing closed circuit, directional valves are provided both in the inhalation tube and in the exhalation tube. A closed-circuit respirator of the type mentioned is disclosed in, for example, DE 39 30 362 C2. 
       SUMMARY OF THE INVENTION 
       [0005]    The basic object of the present invention is to improve a directional valve of the type mentioned with regard to a low flow resistance. 
         [0006]    According to the invention, a directional valve for a respirator product is provided with an inner area and an outer area, a ring-shaped valve housing in the outer area and two diaphragm-like valve disks abutting against one another at a line of separation, which valve disks have each a first section fixed at the valve housing and a movable second section running towards the line of separation. The valve housing has a central web as a valve seat running along the line of separation and support webs arranged on both sides of the central web. The valve disks are designed as resting on the central web and the support webs in the locking direction and as removable in a flap-like manner by the breathing gas stream in the passing direction. 
         [0007]    The valve disks may advantageously consist of disk-shaped rubber or elastomer material, and preferably of silicone rubber. The valve disks may have an average thickness between 0.6 mm and 1.2 mm. 
         [0008]    The inside diameter of the valve housing may advantageously be between 35 mm and 50 mm. The valve disks may have a Shore hardness of 20° Sha to 30° Sha. 
         [0009]    The directional valve according to the present invention has two valve disks abutting against one another at a line of separation, which have a semicircular design, wherein the line of separation is the axis of symmetry of the valve disks. The valve disks consist of thin, flexible elastomer material and are each attached in a punctiform manner in a first section at a valve housing with a ring-shaped design. The valve disks cover the inside cross-sectional area of the valve housing. In a second section adjacent to the first section, which runs up to the line of separation, the valve disks are freely movable. As a contact surface for the valve disks, the valve housing has a central web running along the line of separation, and support webs are additionally arranged on both sides of the central web. In the locking direction of the directional valve, the valve disks lie on the central web and the support webs, and in the passing direction, they are opened in a flap-like manner by the breathing gas stream. If the directional valve is arranged in a breathing tube, the valve disks lie against the inner wall of the breathing tube in the passing direction, and the breathing gas can flow freely through the valve housing without the gas stream being deflected or obstructed in any way by the valve disks. The punctiform attachment of the valve disks in the first section additionally brings about that the valve disks are able to move in the breathing gas stream without greater restoring forces. 
         [0010]    The valve disks may comprise thin rubber or elastomer material, and preferably of silicone rubber. The average thickness of the valve disks is between 0.6 mm and 1.2 mm; a preferred thickness is 0.8 mm. To achieve a good flow of the valve housing, its inside diameter is between 35 mm and 50 mm, the preferred diameter is 40 mm. The valve disks have a Shore hardness between 20° Sha and 30° Sha. 
         [0011]    An exemplary embodiment of the directional valve according to the present invention is shown in the figures and explained below in greater detail. 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 
         [0012]    In the drawings: 
           [0013]      FIG. 1  is a sectional view showing a first directional valve according to the state of the art; 
           [0014]      FIG. 2  is a perspective sectional view showing a directional valve according to the present invention; 
           [0015]      FIG. 3  is a perspective view showing the directional valve according to  FIG. 2  in the flow direction; 
           [0016]      FIG. 4  is a perspective view showing the directional valve according to  FIG. 2  in the locking direction; 
           [0017]      FIG. 5  is a schematic view showing an arrangement for testing a respirator; 
           [0018]      FIG. 6  is a view showing measurement curves for the directional valve according to the present invention and a directional valve according to the state of the art, for a respiratory minute volume of 50 L; and 
           [0019]      FIG. 7  is a view showing measurement curves according to  FIG. 6  for a respiratory minute volume of 100 L. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    Referring to the drawings in particular,  FIG. 1  shows a longitudinal section of a first directional valve according to the state of the art. A first valve housing  2  is connected to a breathing tube  4  in the outer area  3 . The valve housing  2  has a flat contact surface  6  provided with holes  5  for a closing element  7 , which is attached to a web  8  arranged in the center. In the flow direction of the first directional valve  1  shown in  FIG. 1 , the closing element  7  lifts up from the contact surface  6  and a gas flow through the holes  5  is possible. In the locking direction, the closing element  7  lies on the contact surface  6  and closes the holes  5 . 
         [0021]      FIG. 2  illustrates a longitudinal section of a second directional valve  10  according to the present invention. A second, ring-shaped valve housing  11  is connected to the breathing tube  4 . Two semicircular valve disks  12 ,  13  are attached to the second valve housing  11  in such a way that they, starting from a fixed section  14 ,  15  at the second valve housing  11 , have a movable, second section  17 ,  18 , running towards a common line of separation  16 . The second valve housing  11  is provided with a central web  19  running along the line of separation  16 , which serves as the valve seat for the valve disks  12 ,  13 , wherein additional support webs  20 ,  21  are located on both sides of the central web  19 . 
         [0022]      FIG. 2  shows the second directional valve  10  in the flow direction, in which the valve disks  12 ,  13  lift up in a flap-like manner from the webs  19 ,  20 ,  21 . In the locking direction the valve disks  12 ,  13  lie on the webs  19 ,  20 ,  21 . 
         [0023]      FIG. 3  shows a perspective view of the second directional valve corresponding to  FIG. 2  in the flow direction. By contrast,  FIG. 4  shows the locking direction of the second directional valve. Identical components are provided with the same reference numbers of  FIG. 2 . The outer area  3  of the second valve housing  11  is used for attaching the valve disks  12 ,  13  to the fixed sections  14 ,  15 , while the inner area  23  of the second valve housing  11  is covered by the valve disks  12 ,  13 . 
         [0024]      FIG. 5  schematically shows an arrangement for testing a respirator, which consists of a closed-circuit respirator  30  and a reciprocating pump  31 . The closed-circuit respirator  30  comprises an inhalation tube  32  with an inhalation valve  33 , an exhalation tube  34  with an exhalation valve  35 , a regeneration cartridge  36  for the absorption of carbon dioxide, a breathing bag  38  loaded by a spring  37  and a demand oxygen system  39  with a pressurized gas source  40 . The inhalation tube  32  and the exhalation tube  34  are connected to one another at a breathing connection  41 , and the connection is made via the breathing connection  41  to a pressure space  42  of the reciprocating pump  31 . The pressure space  42  of the reciprocating pump  31  is defined by an elastomer diaphragm  43  with a piston  44 , whereby breaths are produced by means of a drive  45 , which is connected via a push rod  46  to the piston  44 . 
         [0025]    A first pressure pickup  47  determines the differential pressure ΔP 1  via the inhalation valve  33 , and a second pressure pickup  48  determines the differential pressure ΔP 2  via the exhalation valve  35 . The pressure pickups  47 ,  48  and the drive  45  are connected via data lines  49 ,  50 ,  51  to a control unit  52 , which controls the testing and issues measured values via a display unit  53 . 
         [0026]    The demand oxygen system  39 , which replaces the consumed breathing gas during the normal use of the device, serves only for replacing the gas loss due to leaks during the testing. 
         [0027]    A certain excess pressure is produced within the breathing circuit of the closed-circuit respirator  30  by the spring  37  which presses on the breathing bag  38 . During exhalation, the breathing gas flows from the breathing connection  41  via the exhalation tube  34 , the exhalation valve  35  and the regeneration cartridge  36  into the breathing bag  38  as storage volume. During inhalation, the breathing gas arrives from the breathing bag  38  and the inhalation valve  33  into the inhalation tube  32  and to the breathing connection  41 . 
         [0028]    Measurement results with directional valves according to the state of the art according to  FIG. 1  and directional valves according to the present invention according to  FIG. 2  are compared in  FIG. 6 . The testing was performed with a respiratory minute volume of 50 L, corresponding to 25 strokes per minute with the reciprocating pump  31  and a stroke volume VT of 2 L. 
         [0029]      FIG. 6  shows pressure measurement curves for a complete breathing cycle each, consisting of inhalation stroke and exhalation stroke. The time course of the breath V(t) with the maximum value VT is shown on the abscissa and the measured pressure differences ΔP 1  and ΔP 2  are shown on the ordinate. The measurement curves  60  and  61  illustrate the pressure courses in a directional valve according to  FIG. 1 . Curve  60  shows the pressure course ΔP 1  for the inhalation valve  33  in the inhalation phase and curve  61  shows the pressure course ΔP 2  for the exhalation valve  35  during the exhalation phase. During the inhalation phase the breathing gas is removed from the breathing bag  38 , and the breathing resistance of the inhalation valve  33  must be overcome, which causes a certain inhalation effort. In the exhalation phase according to curve  61  for ΔP 2 , a rise in pressure is shown, since, in addition to the exhalation valve  35 , the resistance of the regeneration cartridge  36  must be overcome, and the breathing bag  38  is filled against the force of the spring  37 . 
         [0030]    Curve  62  illustrates the pressure course ΔP 1  during the inhalation phase for a directional valve according to the present invention according to  FIG. 2 . A marked reduction in the inhalation effort can be seen compared to curve  60 . During the exhalation according to curve  63  and the pressure ΔP 2 , only the system-related flow resistances, caused by the regeneration cartridge  36  and the breathing bag  38  loaded by the spring  37 , have to be overcome. 
         [0031]      FIG. 7  shows measurement results for a respiratory minute volume of approximately 100 L corresponding to 29 strokes per minute with a stroke volume of 3.5 L. The curves  64 ,  65  show the pressure courses ΔP 1  and ΔP 2  for a directional valve according to FIG.  2 . During the inhalation phase with the pressure course ΔP 1 , the directional valve according to  FIG. 2 , represented by the curve  66 , shows a significantly lower flow resistance than the directional valve according to  FIG. 1 , with the curve  64 . 
         [0032]    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. 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
           1  First directional valve 
           2  First valve housing 
           3  Outer area 
           4  Breathing tube 
           5  Hole 
           6  Contact surface 
           7  Closing element 
           8  Web 
           10  Second directional valve 
           11  Second valve housing 
           12 ,  13  Valve disk 
           14 ,  15  Fixed section 
           16  Line of separation 
           17 ,  18  Second section 
           19  Central web 
           20 ,  21  Support web 
           23  Inner area 
           30  Closed-circuit respirator 
           31  Reciprocating pump 
           32  Inhalation tube 
           33  Inhalation valve 
           34  Exhalation tube 
           35  Exhalation valve 
           36  Regeneration cartridge 
           37  Spring 
           38  Breathing bag 
           39  Demand oxygen system 
           40  Pressurized gas source 
           41  Breathing connection 
           42  Pressure space 
           43  Elastomer diaphragm 
           44  Piston 
           45  Drive 
           46  Push rod 
           47  First pressure pickup 
           48  Second pressure pickup 
           49 ,  50 ,  51  Data lines 
           52  Control unit 
           53  Display unit 
           60 ,  61 ,  62 ,  63 ,  64 ,  65 ,  66 ,  67  Measurement curve