Abstract:
A second-stage regulator for scuba divers, wherein the user&#39;s inhalation effort is lessened considerably by the reduction of the friction between selected components thereof. Coaxially to the regulator poppet, a flexible sleeve is sealingly connected to the poppet and the baffle, so as to avoid blow-by of gaseous mixture through the baffle opening through which there extends the tail of the poppet connected to the lever of the regulator extending in the outlet chamber thereof. The poppet head is placed in ferrule with an at least part-circular profile abutting the inner part of the intermediate chamber to allow the poppet oscillation. The lever end contacting the diaphragm, separating the outlet chamber from the outside, has a generally arched shape with a profile such that the length of the arch between two adjacent contact points measured along the lever is generally equal to the length of the segment between the same adjacent contact points measured along the diaphragm.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates generally to diving equipment and more particularly refers to an improved second-stage regulator for scuba diver. More precisely, the invention concerns an improvement to a regulator constituting the second pressure-reducing stage in a device for delivering air, or a mixture of air and oxygen, to the scuba diver&#39;s mouthpiece.  
       BACKGROUND ART  
       [0002]     It is known that the supply of air, or of the air-oxygen mixture, which is fed to the mouthpiece of the scuba diver from a high-pressure tank, passes via a primary pressure-reducing regulator to a second-stage regulator which supplies the mixture to the mouthpiece of the scuba diver when pressure within the regulator is diminished by a diver&#39;s inhalation.  
         [0003]     Second-stage regulators of the known type have an inlet chamber connected to the outlet of the first-stage regulator, and an outlet chamber connected to the mouthpiece of the user and separated from the outside environment by an elastically deformable diaphragm. The diaphragm is connected via a lever to a poppet which closes off the passage between the two chambers.  
         [0004]     The pressure inside the inlet chamber is kept constant at approximately ten bars as the pressure in the tank varies thanks to appropriate calibration of the first-stage regulator.  
         [0005]     When the user does not breathe, his or her lungs, the mouthpiece, the outlet chamber and the outside environment are at the same pressure.  
         [0006]     When the user inhales, a vacuum is created inside the outlet chamber and the diaphragm bends towards the interior of said chamber, moving the poppet, which normally closes the passage between the inlet chamber and the outlet chamber, towards its opening position.  
         [0007]     The opening of the passage between the inlet chamber and outlet chamber creates an overpressure in the outlet chamber, so that the diaphragm returns into the rest position, moving the lever and returning the poppet into the starting position wherein the passage between the inlet chamber and the outlet chamber is closed once again.  
         [0008]     The movement of these mechanical actuating members, i.e. the diaphragm, the lever and the poppet, is consequently controlled by the vacuum produced by the user when he inhales and the energy required must also allow for the energy dissipated by friction between these interconnected mechanical members. For a better understanding of the various causes of friction occurring in a second-stage regulator of known type, it is useful to examine its structure in detail, referring to the attached  FIGS. 1-4 .  
         [0009]      FIG. 1  shows a second-stage regulator of known type, generically identified by the letter D, which comprises an inlet chamber D 1 , which is always at the first-stage regulator&#39;s outlet pressure, an intermediate chamber D 2  and an outlet chamber D 3  connected to the user&#39;s mouthpiece D 4 . The inlet chamber D 1  is separated from the intermediate chamber D 2  by a valve seat D 5  supporting the seal D 6  on the head D 7  of a poppet D 8 , whose tail D 9  passes loosely through the hole D 10   a  in a baffle D 10  placed between the intermediate chamber D 2  and the outlet chamber D 3 .  
         [0010]     The purpose of the baffle D 10  is to support a spring D 11  that compresses the head of the poppet D 8  against the valve seat D 5 .  
         [0011]     The outlet chamber D 3  is separated from the outside environment D 12  by a diaphragm D 13 . Against a thin rigid plate D 14  on the inner surface of the diaphragm D 13 , there rests the outer end D 15  of a lever D 16  whose other, inner end D 17  is hinged to the baffle D 10  and supports the tail D 9  of the poppet D 8  projecting from the baffle D 10  into the outlet chamber D 3 .  
         [0012]     It is known that, under balanced conditions, the outlet chamber D 3  of the second-stage regulator is at the same pressure as the user&#39;s lungs, which are at the same pressure as the outside environment D 12 . When the user inhales, a vacuum is created in the outlet chamber D 3  with respect to the outside environment D 12  and this causes the diaphragm D 13  to flex inwards, with a consequent rotation of the lever D 16  in the direction of the arrow F 1  (indicated by a dotted line in  FIG. 2 ) and a displacement of the poppet D 8  in the direction of the arrow F 2 , with the consequent passage of breathable gas mixture under pressure from the inlet chamber D 1  to the outlet chamber D 3 , through the intermediate chamber D 2  connected to the outlet chamber D 3  by a wide passage D 18 .  
         [0013]     As soon as the mixture coming from the inlet chamber D 1  reaches the outlet chamber D 3 , thereby increasing the pressure in the latter, the diaphragm D 13  returns to its rest position, and so do the lever D 16  and the poppet D 8 , which closes the seat D 5  once again, separating the inlet chamber D 1  from the intermediate chamber D 2  and from the outlet chamber D 3  until the user inhales again.  
         [0014]     In an ideal second-stage regulator, the vacuum created by the user inhaling should be minimal in order to facilitate his unavoidable respiratory effort. As mentioned earlier, however, the vacuum that the user produces by inhaling must also cope with the unavoidable friction accompanying the movement of the diaphragm D 13 , the lever D 16  and the poppet D 8 . Moreover, said vacuum cannot be reduced by increasing the dimensions of the diaphragm D 13  because the size of the second-stage regulator must be limited in relation to the apparatus connected upstream and downstream of the regulator.  
         [0015]     A first cause of friction is due to the blow-by of the gas mixture from the intermediate chamber D 2  to the outlet chamber D 3 , through the annular opening between the tail D 9  of the poppet D 5  and the hole D 10   a  in the baffle D 10 . Although the majority of the breathable gas mixture passes from the intermediate chamber D 2  to the outlet chamber D 3  through the wide passage D 18 , a modest quantity nonetheless inevitably also passes through the above-mentioned annular opening and, since the passage of the mixture from the intermediate chamber D 2  to the outlet chamber D 3  is accompanied by expansion, and consequently also cooling, the humidity contained in the mixture is converted into tiny ice crystals that generate friction during the axial movement of the tail D 9  of the poppet D 8 .  
         [0016]     A second cause of friction is due to rubbing of the outer end D 15  of the lever D 16  against the inner surface of the plate D 14  applied under the diaphragm D 13 , as the latter flexes into the outlet chamber D 3  under the effect of the vacuum induced by the user inhaling. Despite the generally curved shape of the outer end D 15  of the lever D 16 , the point of contact between lever and diaphragm varies as the latter flexes, thereby creating a sliding friction that has to be overcome by part of the vacuum generated by the user.  
         [0017]     A third cause of friction is due to rubbing of the inner end D 17  of the lever D 16  where it comes into contact with the tail D 9  of the poppet D 8 .  
         [0018]     As shown in  FIGS. 2, 3  and  4 , the inner end of the lever D 16  usually comprises a first flange D 19 , substantially perpendicular to the inner end D 17  of the lever D 16 . At the end of flange D 19  there is a second flange D 20 , substantially parallel to the inner end of the lever D 16 , and then a third flange D 21  parallel to the first flange D 19  and facing in the same direction. The profile of the inner end D 17  of the lever D 16  is consequently shaped substantially in the form of a Z by this succession of flanges D 19 , D 20  and D 21 . Finally, the presence of a longitudinal slot D 22  gives rise to the two branches of a Z-shaped fork that can fit around the tail D 9  of the poppet D 8  between a washer D 23 , supported by a nut D 24  screwed onto the threaded end of the tail D 9 , and the side of the baffle D 10  facing towards the outlet chamber D 3 .  
         [0019]     The baffle D 10  acts as a fulcrum for the third flange D 21  of the inner end D 17  of the lever D 16  and, as it turns, it displaces the washer D 23 , together with the poppet D 8 , in the direction of the arrow F 2 , overcoming the force of the spring D 1 . As the lever D 16  turns, the two branches of the third flange D 21  inevitably slide against the washer D 23  and the baffle D 10  and the consequent friction has to be overcome by part of the vacuum generated by the user when he inhales.  
       OBJECTS AND SUMMARY OF THE INVENTION  
       [0020]     The general object of the present invention is to provide an improved second-stage regulator for scuba divers whose opening demands less effort from the user than known second-stage regulators, thereby facilitating the user&#39;s inhalatory action.  
         [0021]     A particular object of the present invention is to provide an improved second-stage regulator for scuba divers of the above-mentioned type, wherein the friction due to the mechanical members is significantly reduced by comparison with the case of second-stage regulators of known type.  
         [0022]     A further object of the present invention is to provide an improved second-stage regulator for scuba divers of the above-mentioned type, wherein the relative sliding of the various mutually contacting, mechanical members is eliminated and rolling friction essentially occurs.  
         [0023]     An important characteristic of the second-stage regulator according to the present invention lies in that, inside the intermediate chamber and coaxial to the poppet, there is a flexible sleeve with an airtight connection to both the poppet and the baffle around said opening, thus preventing any blow-by of the gas mixture through the opening created by the tail of the poppet and the opening in the baffle containing said poppet, with the consequent formation of tiny ice crystals, which are one of the sources of friction and therefore of energy dissipation.  
         [0024]     Another important characteristic of the second-stage regulator according to the present invention lies in that the head of the poppet is inside a ferrule of substantially rectangular cross section, whose section in the median longitudinal plane (which also includes the lever) has at least a part with a circular profile abutting against the inside wall of the intermediate chamber and enabling the poppet to oscillate in the longitudinal plane. In this way, the end of the lever attached to the tail of the poppet moves integrally with the tail, with negligible sliding, and any friction induced is only of the rolling type as the circular profile of the ferrule turns against the inner wall of the intermediate chamber.  
         [0025]     Another important characteristic of the second-stage regulator according to the present invention lies in that the end of the lever in contact with the rigid plate associated with the diaphragm separating the outside environment from the regulator&#39;s outlet chamber has an arched shape following a profile such that the arch extending between two adjacent points of contact measured on the lever is equal to the length of the segment between the same adjacent points of contact measured on said rigid plate, so that the friction generated by the relative movement between the two members is substantially of the rolling type. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0026]     Further characteristics and advantages of the improved second-stage regulator according to the present invention will become apparent from the following description of one of its embodiments by way of a non-limiting example, with reference to the accompanying drawings, wherein:  
         [0027]      FIG. 1  is a simplified longitudinal section of a second-stage regulator of known type;  
         [0028]      FIG. 2  is an enlarged detail of the end portion of the actuating lever in the second-stage regulator of  FIG. 1 ;  
         [0029]      FIG. 3  is a longitudinal section taken along line III-III of  FIG. 2 ;  
         [0030]      FIG. 4  is a perspective view of the foot of the actuating lever in the regulator of  FIG. 1 ;  
         [0031]      FIG. 5  is a front perspective view of the second-stage regulator according to the invention;  
         [0032]      FIG. 6  shows, on a larger scale, a longitudinal section taken along line VI-VI of  FIG. 5 ;  
         [0033]      FIG. 7  is an enlarged portion of  FIG. 6 ;  
         [0034]      FIG. 8  is an enlarged partial view of the actuating lever, controlled by the movement of the diaphragm;  
         [0035]      FIG. 9  shows, on a larger scale, a section taken along line IX-IX of  FIG. 6 ;  
         [0036]      FIG. 10  is a side view of the second-stage regulator according to the invention;  
         [0037]      FIG. 11  is a side view, wherein the regulator of  FIG. 10  is shown with the cover protecting the diaphragm raised, with an exploded view of the diaphragm and its protection grid;  
         [0038]      FIG. 12  is a perspective view of the same regulator showing the means for locking the cover to the regulator body;  
         [0039]      FIG. 13  is a side view of the means for locking the regulator body&#39;s cover in the closed position;  
         [0040]      FIG. 14  is an isometric view of the means for locking the cover of  FIG. 12 .  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0041]      FIG. 5  and thereafter illustrate a preferred embodiment of the regulator according to the present invention. The reference numbers used in the figures are the same as those used in describing the second-stage regulator according to the known art, illustrated in FIGS.  1  to  4 , except that the letter D is removed when describing similar structural elements. The components not contained in the second-stage regulator of known type are numbered starting from the reference numeral  30 .  
         [0042]     With reference to  FIGS. 5 and 6 , the numeral  30  is used to indicate a regulator body with an inlet conduit  31  and an outlet conduit  32 . The inlet conduit  31  connects a first-stage regulator that delivers a breathable gas mixture at a constant pressure and its interior forms an inlet chamber  1  and an intermediate chamber  2 , separated by a valve seat  5  supporting the seal  6  of the head  7  of a poppet  8 . The tail  9  of the poppet  8  passes loosely through the hole  10   a  in a baffle  10 , which separates the intermediate chamber  2  from an outlet chamber  3  communicating, through the outlet conduit  32 , with a mouthpiece applied thereto (not shown). The baffle  10  provides support for a spring  11  that compresses the head of the poppet  8  against the valve seat  5 .  
         [0043]     The regulator body also has a large opening  25  closed by a deformable diaphragm  13  that separates the outlet chamber  3  from the outside environment  12 . Against a thin rigid plate  14  on the inner surface of the diaphragm  13 , there rests the outer end  15  of a lever  16 , the inner end  17  of which is hinged to the baffle  10  and attached to the tail  9  of the poppet  8  projecting from the baffle  10  into the outlet chamber  3 . The mixture flows into the outlet chamber  3  through a passage  18 . The end  17  of the lever  16  is shaped like a fork, as in the case of the previously-described known technique, see  FIG. 4  in particular.  
         [0044]     As also shown in greater detail in  FIGS. 7 and 9 , the annular opening between the hole  10   a  in the baffle  10  and the tail  9  of the poppet  8  is closed by a flexible sleeve  33 , having a first, outer flange  34  facing the baffle  10 , against which it is pressed by the spring  11  to form a seal inside a groove  10   b . At its other end, the sleeve  33  has a second, inner flange  35  coupled in a circumferential groove  36  on the surface of the poppet  8  to form an airtight seal. The mixture can thus only pass from the intermediate chamber  2  to the outlet chamber  3  through the wide passage  18 , preventing any blow-by, with its consequent cooling and freezing of the humidity contained in the escaping fraction of mixture, which would otherwise remain partly in the form of tiny ice crystals in the above-mentioned annular opening, creating friction against the tail of the poppet  8 .  
         [0045]     With reference to  FIG. 9 , the baffle  10  separating the intermediate chamber  2  from the outlet chamber  3  comprises the end of a first bush  37 . At the end opposite the baffle  10 , the bush  37  has an internal thread  38  coupled to the external thread of a second bush  39  that has an internal thread  40  in its medial region for screwing in a third bush  41 , whose end facing the head  7  of the poppet  8  has an annular rib forming the valve seat  5  for engaging with the seal  6 .  
         [0046]     As a result, the third bush  41  forms the inlet chamber  1  inside the second bush  39 , and the intermediate chamber  2  is formed between the third bush  41  and the baffle  10  of the first bush  37 .  
         [0047]     With reference to  FIGS. 6 and 9 , the head  7  of the poppet  8  has a ferrule  42  of rectangular cross section, whose section in the longitudinal plane shown in  FIG. 6  has at least a partially-circular profile coming up against the inside wall of the intermediate chamber  2 , which also has a substantially rectangular cross section, so that the whole poppet  8  can oscillate around a transversal axis C. To enable said poppet movement, the width of the ferrule, measured on the axis of oscillation, is narrower than the width of the intermediate chamber  2 . Said oscillation enables the washer  23  (mounted so that it can slide on the tail  9  of the poppet  8 ) to move transversally in the direction of the arrows F 3  ( FIG. 7 ) together with the third flange  21  on the inner end  17  of the lever  16 . There is consequently no sliding between the washer  23  and the two arms of the third flange  21  on the lever  16 . This eliminates the second cause of friction, further reducing the vacuum that the user needs to generate when he inhales.  
         [0048]     The assembly of this group of members in the second-stage regulator according to the present invention is as follows ( FIGS. 6, 7 ,  9 ):  
         [heading-0049]     the flexible sleeve  33  is placed at the end of the first bush  37  and the spring  11  rests on its outer flange  34 ;  
         [heading-0050]     the ferrule  42  is fitted on the poppet  8  and the tail  9  of the poppet is then inserted through the spring  11 , the sleeve  33  and the hole  10   a  in the baffle  10  forming the end of the first bush  37 , in that order;  
         [heading-0051]     the washer  23  is inserted on the threaded end of the tail  9  of the poppet  8  and then the nut  24  is screwed into place;  
         [heading-0052]     the Z-shaped inner end  17  of the lever  16  is inserted between the washer  23  and the surface of the baffle  10  on the side facing the outlet chamber  3 .  
         [0053]     By adjusting the nut  24 , the degree of tightness of the second bush  39 , inside the first bush  37 , and the degree of tightness of the third bush  41  inside the second bush, on the one hand it is possible to calibrate the force with which the seal  6  of the poppet  8  is pressed against the valve seat  5  and, on the other hand, by adjusting the degree of tightness of the nut  24  it is possible to calibrate the exact position of the end  15  of the lever  16 .  
         [0054]     The above-described assembly can be adjusted with the aid of a suitable tool before its installation in the regulator body  30  through the inlet conduit  31  on the regulator body. As shown in  FIGS. 5 and 9 , two opposite grooves  43  are formed into the outer surface of the first bush  37 , perpendicular to the longitudinal axis of symmetry, and two holes  44 , formed on the inlet conduit  31  at the same transversal distance from the grooves  43 , are designed to contain two pins  45  when the aforesaid grooves are aligned with the holes  44 . The relative longitudinal position of the assembly of the second-stage regulator vis-a-vis the inlet conduit  31  is thus perfectly defined. It is finally fixed in place by means of a nut  46  engaging the external thread on the second bush  39  until it abuts against the end of the inlet conduit  31 .  
         [0055]     As explained above, second-stage regulators of known type have a third source of friction due to sliding of the rounded outer end of the lever resting against the plate underneath the inner surface of the diaphragm. According to the invention, such sliding motion—and the consequent sliding friction—is converted into a rolling motion and the sliding friction is consequently replaced by a far more limited rolling friction.  
         [0056]     For this purpose, the outer end  15  of the lever  16  has a profile such that it rolls along the underside of the plate  14 , remaining at a tangent to the latter, as the diaphragm  13  and the plate  14  flex inwards from the resting position to the maximum expansion of the diaphragm.  FIG. 8  shows a possible configuration of said end of the lever designed to operate as described above.  
         [0057]     In practical terms, to achieve a rolling instead of a sliding motion between the lever and plate, it is necessary for the segment AB on the plate, coinciding with the set of points of contact between the lever and plate between the resting position and the maximum extension of the diaphragm, to coincide with the length of the arch A′B′ on the lever, and for the tangent in B′ to remain horizontal.  
         [0058]     As illustrated in  FIG. 5 , the regulator body  30  is of elongated shape suitable for containing a diaphragm  13  that, according to the invention, takes on an elliptical shape. This solution enables the transversal dimension of the regulator to be kept within the overall dimensions of the surrounding apparatus, while nonetheless increasing the surface area of the diaphragm, with an evident benefit for the user, who saves energy because the vacuum he has to create by inhaling is lower the greater the surface area of the diaphragm. Moreover, the elliptical shape enables the plate  14  to remain parallel as it descends under the effect of a vacuum in the outlet chamber  3 , a behavior that is fundamental to the proper operation of the lever and of the other moving parts in the regulator.  
         [0059]     In second-stage regulators of known type, the diaphragm is attached to the edge of the corresponding opening by means of a covering frame generally screwed onto the regulator body after inserting an axially-movable control button, so that a slight pressure on said button enables the proper operation of the second-stage regulator to be checked.  
         [0060]     According to the present invention ( FIGS. 10 and 11 ), the diaphragm  13  and the corresponding control button  47  are held against the edge of the corresponding opening in the regulator body  30  by means of a covering frame  48 , one end of which is hinged at  49  to the regulator body  30 , while the other end is hinged at  50  to a bracket  51  with a long through hole  52  suitable for aligning with a corresponding hole  53  in the regulator body, when the frame is in the closed position shown in  FIG. 10 . In this position, a pin  54  with an elongated head  55  is used to lock the assembly over the regulator body  30 .  
         [0061]     As shown in  FIGS. 12, 13  and  14 , the elongated head  55  on the pin  54  can take the form of a cross member engaging a seat  56  situated at the end of a cam profile  57 . A spring  58  keeps the cross member  55  elastically in the closed position.  FIGS. 13 and 14  show that the members  59  and  60  are integral to the regulator body  30 , while the member  61  belongs to the end of the bracket  51 . Any unwanted or accidental opening of the regulator due to the release of the bracket  51  and frame  48 , and the consequent detachment of the diaphragm  13 , is prevented by the fact that the pin  54  has a head  54   a  with a prism-shaped cavity designed so that a special key is needed to open it.