Abstract:
A valve device, particularly for a breathing regulator ( 100 ) for divers, comprising an inlet chamber ( 111 ) which can be connected to a source of gas under super-atmospheric pressure, and an outlet chamber ( 112 ) which is under a regulated pressure. A seating ( 115 )—which is movable under the influence of the super-atmospheric pressure and the regulated pressure, seals between the inlet chamber and the outlet chamber and has a through-passing passageway ( 115   a ) that interconnects said chambers. Also included is a valve body ( 114 ) which is movably arranged in the seating such as to open and close the through-passing passageway in said seating. A servo element ( 116, 117, 118 ) exerts on the valve body a force that depends on the position of the movable seating, so that varying force-influence on the valve body from the super-atmospheric pressure will be compensated for by a corresponding varying force from the servo element. This results in an essentially constant valve characteristic, while providing a mechanically simple solution at the same time.

Description:
FIELD OF INVENTION  
         [0001]    The present invention relates to valve devices and then particularly to balanced valve devices for controlling the flow of pressurised breathable gas to breathing regulators. The invention also relates to such a breathing regulator.  
         DESCRIPTION OF THE BACKGROUND ART  
         [0002]    Diving equipment includes a so-called breathing regulator which is connected to one or more diving tanks or their technical equivalence and which is intended to adjust the tank pressure to a predetermined regulated pressure. The breathing regulator is provided with a valve device to this end. FIG. 1 illustrates diagrammatically one such valve device constructed in accordance with known technology. As will be seen, the valve includes an inlet side  11 , which is under tank pressure P inlet , and an outlet side  12 , which is under the regulated pressure P outlet . A conical valve body  14  is movable in a seating  15 . The outlet side  12  is delimited by a flexible diaphragm or membrane  16 , which is connected to a spring  17  that exerts a spring force F spring  on the diaphragm  16 . Thus, one side of the diaphragm  16  is subjected to forces from the regulated pressure P outlet , while the other side of the diaphragm is subjected to forces from the ambient pressure P ambient . The spring force, together, e.g., with forces exerted by the diaphragm  16 , acts/act on a rod  18  connected to the valve body and thus exerting a force F rod  onto said body.  
           [0003]    This known valve has the following modus operandi. Movement of the valve body  14  is determined by the forces to which it is subjected. These forces include (as shown in the figure) an upwardly directed force F inlet  determined by the tank pressure. This force is counteracted essentially by downwardly acting forces F outlet , which are comprised generally of the effect of the regulated pressure P outlet  on the valve body and of the rod force F rod . When a diver who has a nozzle connected to the outlet side inhales, therewith causing a decrease in the regulated pressure, the pressure on the diaphragm  16  decreases and the diaphragm then exerts an increasing force on the rod  18 . The force F rod  then increases and, in the case of a functioning valve, the valve body will be moved downwards, thereby allowing tank gas to flow in through the seating  15  until the regulated pressure has increased to an extent at which the valve body returns to the position shown in FIG. 1.  
           [0004]    One problem with such known valve devices is that movement of the valve body is dependent on the tank pressure, which in the case of a full tank can correspond to a super atmospheric pressure of about 300 bar and may fall to close on 0 bar during use. This means, in turn, that the valve characteristic will vary, together with the regulated pressure.  
           [0005]    Several solutions to this problem have been proposed. One example of these proposed solutions is illustrated in FIG. 2. The valve shown in FIG. 2 corresponds to the valve shown in FIG. 1 in many aspects, although in this latter case the homogenous valve body  14  has been replaced with a valve body  14 ′ that includes a through-passing passageway  14   a ′. This passageway connects the outlet  12  with a space  19 , which is sealed against the inlet  11  by means of an O-ring  20 . Consequently, those forces F inlet  acting on the valve body from the inlet side have essentially no axial component, thereby providing a balanced valve that gives a regulated pressure generally independent of P inlet .  
           [0006]    The use of a valve body of this design, however, has the drawback that the sealing surface between the valve body and the seating ultimately tends to leak. There are several reasons for this. The fit between the hole and the cone of the valve body must be perfect—no irregulatories can be permitted. After having been in use for a longer period of time, the cone becomes damaged, in the form of scratches and ruts in the hole-defining edge and the cone, this damage contributing to seal leakage. Furthermore, the valve body must be straight, meaning that the body must be guided with utmost precision. The O-ring may begin to leak as a result of abrasion and other type of wear, thereby preventing achievement of the desired balancing effect and sealing effect.  
           [0007]    These drawbacks associated with the use of a conical valve body are avoided when using a spherical sealing body. A spherical body is self-guiding, thereby obviating the need of the accurate guide required by a conical valve body.  
           [0008]    It will be realised, however, that the balancing solution illustrated in FIG. 2 cannot be applied when a spherical body is used as a valve-closing means.  
         SUMMARY OF THE INVENTION  
         [0009]    One object of the present invention is to provide a generally balanced valve device, in other words a valve device with which the pressure on the outlet side is held essentially constant regardless of the pressure on the inlet side.  
           [0010]    The invention is based on the realisation that balancing of the valve device can be achieved by causing the seating on which the valve-closing member rests to move under the influence of the pressure on both the inlet side and the outlet side of said valve.  
           [0011]    According to the invention, there is thus provided a valve device as defined in Claim  1 .  
           [0012]    Also provided in accordance with the invention is a breathing regulator that includes such a valve device.  
           [0013]    The inventive valve device and the inventive breathing regulator provide an essentially constant valve characteristic, while also affords a simple mechanical solution.  
           [0014]    In one particularly preferred embodiment, a spherical body, or ball, is used as a valve-closing member. The valve-closing member is thus beneficially self-guiding.  
           [0015]    Other preferred embodiments are defined in the dependent Claims. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    The invention will now be described in more detail by way of example and also with reference to the accompanying drawings, in which  
         [0017]    [0017]FIG. 1 is a diagrammatic illustration of an unbalanced valve device according to prior art;  
         [0018]    [0018]FIG. 2 is a diagrammatic illustration of a balanced valve device according to prior art;  
         [0019]    [0019]FIG. 3 is a diagrammatic illustration of a valve device according to the invention;  
         [0020]    [0020]FIG. 4 illustrates a breathing regulator that includes an inventive valve device, said valve being closed when high pressure prevails on the inlet side;  
         [0021]    [0021]FIG. 5 shows the breathing regulator of FIG. 4 with the valve open;  
         [0022]    [0022]FIG. 6 shows the breathing regulator of FIG. 4 with the valve closed when low pressure prevails on the inlet side; and  
         [0023]    [0023]FIG. 7 shows the breathing regulator of FIG. 6 with the valve open. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]    A preferred embodiment of an inventive valve device and an inventive breathing regulator will now be described, first with reference to FIG. 3. It will be noted that the directions mentioned in the description, such as up, down, etc., refer only to those directions shown in the figures and shall not therefore be considered to limit the scope of the invention when interpreting the accompanying Claims.  
         [0025]    [0025]FIG. 3 is a principle diagram of an inventive valve device. The valve device includes an inlet side  111 , an outlet side  112 , a diaphragm or membrane  116 , a diaphragm spring  117 , and a rod  118 . These valve components correspond to the valve components shown in FIG. 1. The valve device also includes a valve-closing body in the form of a ball  114 , which rests over an opening  115   a  in a seating  115 . Distinct from the seating used in said known valve technology, the seating  114  can move up and down, as indicated by the double-headed arrow in FIG. 3. Sealing between the inlet and the outlet sides is achieved by means of an O-ring  115   b , which abuts the movable seating, and a regulator housing (not shown in FIG. 3). The seating spring  119  is connected to the seating. Thus, the seating is able to move in response to a difference in the pressure between the inlet side  111  and the outlet side  112 , and also in accordance with the spring characteristic of the spring  119 . In order to obtain said essentially balanced valve function, it is necessary that the following ratios are fulfilled between relevant areas and spring characteristics:  
         k        (   119   )       =       k        (   117   )       ·         A        (     115      a     )       -     A        (     115      b     )           A        (     115      b     )                                 
 
         [0026]    where  
         [0027]    k( 119 )=the stiffness of the seating spring  119 ;  
         [0028]    k( 117 )=the stiffness of the diaphragm spring  117 ;  
         [0029]    A( 115   a )=the area of the opening  115   a  in the seating  115 ; and  
         [0030]    A( 115   b )=the area sealed by the O-ring  115   b.    
         [0031]    It should be noted that this is a somewhat simplified relationship that does not take, e.g., O-ring friction and sealing force into account.  
         [0032]    Because the seating is movable, the force of the spring will vary in accordance with the position of the seating, when the ball rests in the seating. This enables changes in gas pressure on the inlet side to be compensated for in respect of “automatically” changed spring forces. For instance, if the tank pressure should decrease, resulting in a smaller upwardly acting force F inlet , the seating  115  will move downwards in the figure. The spring is extended as a result of this downward movement of the seating, resulting in a decrease in the downwardly acting force F rod . The person skilled in this particular technical field will be able to readily dimension the regulator components so that the changes in upwardly directed and downwardly directed forces on the ball will cancel each other out, thereby achieving balancing of the valve device; see the above formula.  
         [0033]    An embodiment of a breathing regulator  100  that includes an inventive valve device will now be described with reference to FIGS. 4-7. The regulator comprises a housing  101  whose interior is sealed against the surroundings by means of the diaphragm  116 . The housing includes a lid or cover  102 , which functions as a counter-pressure means for the spring  117 . A tank coupling  103  is also sealingly connected to the housing.  
         [0034]    The breathing regulator includes an inlet side  111  which is adapted for connection to one or more diving tanks (not shown) and an outlet side  112  adapted for connection to a breathing nozzle (not shown). The inlet and outlet sides are mutually separated by a valve seating  115 . The valve seating is able to move up and down and is sealed against the housing  101  by means of an O-ring  115   b . The seating has an axially through-passing opening  115   a  of circular cross-section, said opening forming a connecting passageway between the inlet and outlet sides. Movement of the seating is regulated by a spring  119 .  
         [0035]    A ball  114  functions as a valve-closing body. The ball rests in the seating  115  and closes the passageway  115   a  in the position shown in FIG. 4. The ball acts on a rod  118  which, in turn, acts on the diaphragm  116  and thereby on a pressure plate  120  which is spring-biased downwards by means of the spring  117 . The rod is mounted in a holder  121  by means of a slide bearing (not shown). The function of the holder  121  is thus to guide the rod  118 , among other things, and also to hold the seating spring  119 . The holder is also designed to limit upward movement of the seating to an upper end position. The space in which the pressure plate  120  is disposed is divided by the flexible diaphragm  116  into a lower chamber  123   a , which is in connection with the outlet side  112 , and an upper chamber  123   b.    
         [0036]    The valve seating is comprised essentially of metal, although it has a plastic coating on the surface that abuts the ball. The ball is made of steel or a ceramic material. In the case of the preferred embodiment, the diaphragm  116  is a roll diaphragm.  
         [0037]    [0037]FIG. 4 shows the breathing regulator  100  in a closed state, with high pressure on the inlet side, wherewith it will be seen that the seating  115  has been displaced slightly upwards away from the bottom of the chamber  112 . This corresponds to the situation when a dive commences. FIG. 5 shows the breathing regulator in the same situation, but with inhalation when the valve device is open. Inhalation empties the inlet side of air, and therewith also the lower chamber  123   a , causing the pressure in the chamber to fall. This causes the flexible diaphragm  116  to move downwards and thereby exert force on the rod  118 , which, in turn, acts downwardly on the ball  114 . Because the downwardly acting forces on the ball in this position exceed the upwardly directed forces, the ball will leave its sealing placement in the seating and allow air to pass through the passageway  115   a . This state continues until the upwardly directed forces acting on the ball exceed the downwardly acting forces, in other words when the pressure on the inlet side, and therewith in the lower chamber  123   a , has increased to a desired regulated pressure. The diaphragm is therewith caused to return to the position shown in FIG. 4. The super-atmospheric pressure in the diving tank falls after being used for awhile and therewith also the pressure on the inlet side  111 . The regulated pressure on the outlet side  112 , however, shall remain at the desired regulated pressure. This means that the seating  115  gradually moves down and finally takes the lower end position shown in FIGS. 6 and 7. This means, in turn, that the forces exerted by the rod  118  on the ball become smaller, which balances the decreasing forces resulting from the drop in pressure in the diving tank. In other respects, opening and closing of the valve in the position shown in FIGS. 6 and 7 take place precisely as in the situation described above with reference to FIGS. 4 and 5.  
         [0038]    The inventive breathing regulator achieves the same valve balancing effect as that earlier achieved with the use of an O-ring sealed conical valve body as a valve-closing means, see FIG. 2. At the same time, there are obtained those advantages that are afforded by the use of a ball as a valve-closing body, such as a self-guiding effect.  
         [0039]    Although the invention has been described with reference to a preferred embodiment of a valve device and a preferred embodiment of a breathing regulator, the person skilled in this particular technical field will be aware that these embodiments can be varied or modified within the scope of the accompanying Claims. For example, the valve seating may consist entirely of metal, and the ball may be made of plastic. To avoid wear, the edge surface of the passageway  115   a  that functions as an abutment surface on the seating  115  against the ball  114  may be coated with a plastic material.  
         [0040]    In use, the ball  114  rests against the rod  118 . In order to counteract the force of gravity on the ball, and therewith ensure that the ball will not fall to the bottom at a given attitude on the regulator—which could cause the ball to be wrongly positioned in the seating as a result, e.g., of a very slow or very fast increase of P inlet —a spring (not shown) may be included between the ball and the bottom of the regulator housing. In such case, the spring shall be sufficiently weak to render its force addition negligible, or, alternatively, this force addition can be included when dimensioning the regulator.  
         [0041]    The seating has been shown to be movable under the effect of the pressure on the inlet and outlet sides. For obtaining desired movement characteristics, there has been described a seating spring  119 . Alternatively, several springs, for instance helical springs or cup springs, may be arranged between the seating and the holder  121 . Alternatively, the intrinsic springiness of the seating, i.e. its ability to bend under pressure, may be utilised to obtain the desired movement of the seating. In this case, the function of the seating spring  119  is replaced by a fixedly mounted seating in which outward bending or compression of the seating material replaces the function of the seating spring  119 .  
         [0042]    There has been shown a spring  117  that acts on the pressure plate  120 . Alternatively, the forces exerted by the diaphragm  116  may replace the forces exerted by the spring, therewith enabling the spring to be omitted.  
         [0043]    Although a ball has been described as a valve-closing body, it will be understood that a movable seating can also be used together with a conical body as a valve-closing means.  
         [0044]    The servo device may include a plunger instead of a flexible diaphragm.  
         [0045]    Although the valve device described is primarily intended for divers, it will be understood that similar applications are also encompassed by the inventive concept, such as in connection with equipment for smoke divers, medical care equipment, etc.