Abstract:
A pressure regulator comprising a housing containing a channel arranged to communicate a fluid from a fluid inlet to a fluid outlet, said channel comprising a valve seat and closure member with said closure member operable with valve seat to control fluid flow through the channel and; wherein the housing comprises a resilient diaphragm in fluid communication with the fluid and in physical communication with the closure member such that the diaphragm is operable to deform in response to a change in pressure of the fluid and such that deformation of the diaphragm causes the closure member to change position and; wherein a hollow member is located in the channel and the stem of said hollow member defines a narrow path between the channel and outside of said stem in a region proximate to the fluid outlet such that fluid passing through the channel is communicated from the fluid inlet to the fluid outlet via said narrow path such that the pressure of the fluid emerging from said narrow path into the channel is communicated to the diaphragm via the inside of the hollow member.

Description:
FIELD 
       [0001]    This invention relates to a pressure regulator for controlling fluid pressure. Particularly, but not exclusively, the invention pertains to miniature pressure regulators for medical devices. 
       BACKGROUND 
       [0002]    Pressure regulators for use in medical devices such as a gas delivery system often require high accuracy of the regulated output pressure. In recent years there has been a move towards miniaturisation and weight reduction of medical devices including devices using pressure regulators to allow for increased convenience and portability. Accordingly there have been attempts to produce miniature pressure regulators to satisfy these size and weight requirements including single stage regulators for use with supply pressures of typically 4-10 bar, producing a reduced regulated output pressure. Such single stage miniature pressure regulators may also have applicability in scientific equipment and high precision industrial machinery. 
         [0003]    “Pressure droop” is a characteristic seen in known regulators whereby the pressure at the regulator outlet falls, deviating away from the set point pressure as the flow rate through the regulator is increased. 
         [0004]    In seeking to reduce the size of pressure regulators the size often has to be compromised to achieve the required regulator performance particularly for increased flow capacity and the reduction of outlet “pressure droop”—typically by increasing the size of regulator to achieve the performance requirement. The present invention seeks to provide a solution to these problems. 
       SUMMARY 
       [0005]    According to the present invention there is provided a pressure regulator, said pressure regulator comprising a housing containing a channel arranged to communicate a fluid from a fluid inlet to a fluid outlet, said channel comprising a closure member operable with a valve seat to control the flow of fluid wherein the housing comprises a resilient diaphragm in fluid communication with the fluid and in physical communication with the closure member such that the diaphragm is operable to deform in response to a change in pressure of the fluid and such that deformation of the diaphragm causes the closure member to change position; wherein a hollow member is located in the channel and the stem of said hollow member defines a narrow path between the stem and the channel in a region proximate to the fluid outlet, such that fluid passing through the channel is communicated from the fluid inlet to the fluid outlet via said narrow path. The outside profile of the stem of the hollow member may be one of several forms—it may have a portion which is generally tapered or curved to provide a gradual reduction in the cross-sectional area of the narrow path between the outside of the stem and the channel or it may have a cylindrical portion. The Venturi effect of fluid moving at a higher velocity through the narrow path between the stem of the hollow member and the channel then entering the slower moving fluid in the channel towards the fluid outlet results in reduced pressure which is transferred to the diaphragm via the inside passage in the hollow member. 
         [0006]    This approach, of the diaphragm sensing the reduced pressure produced by the Venturi effect of flow exiting the narrow path formed between the stem of the hollow member and the channel, helps to partially compensate for fluid pressure drop through the regulator between the downstream side of the valve seat and the regulator outlet wherein the communication of the said reduced pressure to the diaphragm urges movement of the diaphragm in the direction that tends to increase the opening between the closure member and valve seat, thereby reducing outlet pressure droop. The provision of the hollow member has proved satisfactory in reducing regulator outlet pressure droop. This reduction of pressure droop in turn allows the flow capacity of the pressure regulator to be increased. Furthermore, sampling the pressure in near to the fluid outlet with the sensing end of the stem of the hollow member at or near to the centre region of the outlet channel cross-section, allows a fast response of the pressure regulator to be obtained in response to changes in the regulator fluid inlet pressure or change in flow to the fluid outlet. 
         [0007]    It has been found that the use of such a hollow member in the configuration described provides a regulator with good or low hysteresis and good repeatability of outlet fluid pressure. 
         [0008]    Furthermore, the use of such a hollow member allows for a compact configuration of pressure regulator. The structural approach of providing a hollow member in this way facilitates a low-cost manufacturing approach while providing reduction of outlet pressure droop. 
         [0009]    Beneficially the pressure regulator of the present invention comprises a deflection member located in the said channel that is arranged to deflect fluid flowing in downstream direction in the channel such that the closure member is shielded to substantially prevent fluid flow that is generally parallel with the movement axis of the closure member, from impinging on surfaces of the closure member that are upstream of the valve seat. 
         [0010]    Beneficially the deflection member deflects fluid around the closure member such that fluid is directed to the valve seat via apertures or slots in the deflection member in a generally symmetric manner in a plane substantially perpendicular to the movement axis of the closure member. By this approach, the use of the deflection member to provide shielding, allows the magnitude of forces urging the closure member towards the valve seat along the movement axis of the closure member to be reduced, thereby reducing the outlet pressure droop. This reduction in pressure droop in turn allows the flow capacity of the pressure regulator to be increased. 
         [0011]    Furthermore, the use of such a deflection member further allows for a compact configuration of pressure regulator. The structural approach of providing a deflection member in this way facilitates a low-cost manufacturing approach while providing reduction of outlet pressure droop. 
         [0012]    In some examples, the movement axis of the closure member may be substantially coaxial with the fluid inlet. Additionally or alternatively, the deflection member may be located in the channel proximate to the fluid inlet. Such a configuration allows for a compact configuration of pressure regulator. 
         [0013]    In some examples, the longitudinal axis of the hollow member may be substantially parallel with the axis of movement of the regulator closure member. 
         [0014]    Alternatively, the longitudinal axis of the hollow member may be substantially perpendicular to the axis of movement of the closure member. Such a configuration allows for a compact configuration of pressure regulator, as well as allowing for simplified assembly. In some examples, the regulator may comprise a plurality of hollow members. 
         [0015]    The use of multiple hollow members enables increased flow through the regulator—provided that the flow capacity is not limited by other limiting flow areas in the flow path through the regulator. 
         [0016]    In some examples, the closure member maybe an elongate element. Such a structure allows the closure member to be in physical communication with the diaphragm in a simplified manner while at the same time being operable to open and close the channel. 
         [0017]    In some examples, the fluid inlet may be substantially parallel to the fluid outlet. 
         [0018]    Alternatively, the fluid inlet may be substantially perpendicular to the fluid outlet. Such a configuration allows for a compact configuration of pressure regulator. 
         [0019]    In some examples, the regulator may comprise a bias spring to bias the closure member into abutting the diaphragm. Such a structure allows the closure member to remain in physical communication with the diaphragm and to apply a force to the diaphragm. Furthermore such a configuration allows for physical contact to be maintained in a manner which simplifies manufacture and/or assembly. 
         [0020]    In some examples, the closure member may be fixedly attached to the diaphragm. Such a configuration allows the closure member to remain in physical communication with the diaphragm and allows the application of a bias force to the closure member acting towards the diaphragm to be avoided. In some examples, the closure member may be removably attached to the diaphragm. Such a configuration allows the closure member to remain in physical communication with the diaphragm and allows the application of a bias force to the closure member acting towards the diaphragm to be avoided. Furthermore such a configuration allows the removability of the closure member such that it can be replaced for repair. 
         [0021]    In some examples, the diaphragm may be biased by a force acting on the diaphragm by a diaphragm load spring to urge the diaphragm and therefore the closure member towards a position that provides an opening between the closure member and the valve seat. Such a structure allows a force to be applied to the diaphragm through the selection of the spring stiffness and length and the magnitude of spring compression. 
         [0022]    In some examples, the regulator may comprise an adjustment mechanism which is operable to adjust the compression of the diaphragm load spring such that the force acting on the diaphragm by the diaphragm load spring can be varied. Such a structure allows for an end user to adjust the fluid output pressure. 
         [0023]    In some examples, a section of the diaphragm which is not in fluid communication with the channel may have a fluid communication path to the exterior of the pressure regulator to the exterior environment. Such a structure allows for fluid pressure on the channel side of the diaphragm to be referenced to the exterior pressure. In some examples, the pressure of a pressurised control fluid acting on the side of the diaphragm which is not in contact with the channel may be adjusted to vary the force of the pressurised control fluid acting on the diaphragm. Such a configuration allows an end user to adjust the regulator fluid outlet pressure. 
         [0024]    In some examples, the fluid pressure at the fluid outlet may be determined by a net spring force acting on the diaphragm. Such a configuration allows for the fluid outlet pressure to be predetermined in a simplified manner without the need for elements other than the diaphragm and those producing a force on the diaphragm to be adjusted. 
         [0025]    In some examples, the net force acting on the closure member may comprise two or more forces selected from the group comprising: the restoring force of the resilient diaphragm itself; a force applied through the closure member by the bias spring; the force applied by the diaphragm load spring; and the force applied by a pressurised control fluid. Such a configuration allows for the pressure regulator to be adjusted by adjusting the force acting on the diaphragm from one or more of the elements making up the net force. Furthermore such a configuration allows for pressure regulators to be used for a wide range of applications. 
         [0026]    In some examples, the pressure regulator may be a non-relieving pressure regulator. Such a configuration allows for fluid wastage to be reduced and allows for the release of potentially dangerous fluids to be reduced. 
         [0027]    In some examples, the pressure regulator may be a relieving pressure regulator. Such a configuration allows the relief of excess pressure above a set point in the event of induced pressure from a system or device connected to the regulator outlet 
         [0028]    In some examples, the wetted components of the pressure regulator may be suitable for use with medical gases. Such a configuration allows such pressure regulators to be used for a wide range of applications, in particular for use in medical applications. 
         [0029]    Some examples provide a multi-stage pressure regulator wherein at least one stage of the multi-stage pressure regulator is a regulator according to the invention. For example a regulator in accordance with the invention may be used as a second stage in a two stage regulator to reduce fluid pressure to a low outlet pressure, from an intermediate pressure provided by the first stage of the regulator which reduces the fluid pressure from a high supply pressure to the two stage regulator. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0030]    Embodiments of the present invention will now be described in greater detail with reference to the accompanying drawing in which: 
           [0031]      FIG. 1 a    shows an end view of a pressure regulator; 
           [0032]      FIG. 1 b    shows a lengthwise cross-section through the pressure regulator shown in  FIG. 1   a;    
           [0033]      FIG. 1 c    shows an enlarged portion of the cross-section through the pressure regulator shown in  FIG. 1   b;    
           [0034]      FIG. 2 a    shows a lengthwise cross-section through a pressure regulator; 
           [0035]      FIG. 2 b    shows an enlarged portion of the cross-section through the pressure regulator shown in  FIG. 2   a;    
           [0036]      FIG. 3 a    shows a lengthwise cross-section through the pressure regulator shown in  FIG. 3   c;    
           [0037]      FIG. 3 b    shows an enlarged portion of the cross-section through the pressure regulator shown in  FIG. 3   a;    
           [0038]      FIG. 3 c    shows an end view of the pressure regulator shown in  FIG. 3   a;    
           [0039]      FIG. 3 d    shows an enlarged portion of the cross-section through the pressure regulator shown in  FIG. 3   f;    
           [0040]      FIG. 3 e    shows a lengthwise view of the pressure regulator shown in  FIG. 3   a;    
           [0041]      FIG. 3 f    shows a lengthwise partial cross-section through the pressure regulator shown in  FIG. 3   e;    
           [0042]      FIG. 4  shows a lengthwise cross-section through a pressure regulator; and 
           [0043]      FIG. 5  shows a lengthwise cross-section through a pressure regulator. 
       
    
    
       [0044]    While the invention is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are herein described in detail. It should be understood however that the drawings and detailed description attached hereto are not intended to limit the invention to the particular form disclosed, but rather the invention is to cover all modifications, equivalents and alternatives falling within the appended claims. 
       DETAILED DESCRIPTION 
       [0045]    A pressure regulator is illustrated in  FIGS. 1 a -1 c   . The pressure regulator shown in  FIGS. 1 a -1 c    has a main body  10 , into which is assembled a valve structure that includes a movable closure member  14  (also known, for example, as a valve poppet), a valve seat  17  and a valve seat housing  12 . The valve seat housing  12  is dimensioned to receive valve seat  17  which in the present example is an elastomeric flat disc with an aperture. The closure member  14  is movable under action of the regulator mechanism described below to move along a movement axis so as to in one position cause obstruction of a fluid path and in other positions provide restriction to the fluid path. 
         [0046]    To allow the fluid path to be opened, the closure member  14  is moved to a position where a gap is provided between the aperture of the valve seat  17  and the closure member  14  such that the fluid path is open. 
         [0047]    In the structure illustrated in  FIGS. 1 a -1 c   , the closure member  14  is assembled into the pressure regulator by way of being inserted into a receiving structure of the main body  10  along with a closure member housing  11 , a bearing  15 , a bias spring  16 , the closure member  14 , the valve seat  17 , a valve seat housing  12 , and a retainer  13 . The bore in the retainer  13  and the bore in the bearing  15  are dimensioned to slidably receive the closure member to provide guidance for the closure member along an axis coaxial with the valve seat and valve seat housing. The bias spring  16  registers against a shoulder on the closure member  14  and against a shoulder on the bearing  15  to provide an urging or biasing force acting on the closure member  14  towards the valve seat  17 . The retainer  13  has a threaded portion that engages with the main body  10  and is torque tightened to secure the valve seat housing  12 , the valve seat  17 , the closure member  14 , the bias spring  16 , the bearing  15  and the  0  ring seal  32  in position in the main body  10 . The structure of the main body  10  together with the retainer  13  and the orifice plug  31  provides a partition between the main fluid path and the diaphragm. The chamber between the said partition and diaphragm is referred to as the diaphragm chamber  76 . Fluid communication between the main fluid path of the regulator and the diaphragm chamber is provided by the orifice in the orifice plug  31  and also the significantly smaller fluid connection provided by the clearance between the closure member  14  and the bore of retainer  13 . The closure member housing or deflection member  11  is shaped so as to cause fluid to be deflected around the closure member housing  11  and to enter the inside of the closure member housing  11  into the region where the closure member  14  engages with the valve seat  17 , via apertures or slots  71  in the closure member housing  11 , in a plane substantially perpendicular to the movement axis of closure member  14 . 
         [0048]    In the arrangement illustrated in  FIGS. 1 b  and 1 c   , the closure member  14  has a conical portion which is referred to as ridge  14   a.  The presence of the ridge  14   a  allows an opening between the closure member  14  and the valve seat  17  to be at or between fully open and closed positions by movement of the closure member  14  along its movement axis. Movement of the ridge  14   a  to a closed position will close a fluid path through the regulator and movement of the ridge  14   a  away from such a closed position will open the fluid path through the regulator. The arrangement of these assembled elements is shown in  FIG. 1 b    and in an enlarged view in  FIG. 1   c.    
         [0049]    The diaphragm in the present example  21  is formed from a flexible or resilient material such as a moulded elastomer. The diaphragm  21  can be preassembled so as to be sandwiched between a stud  20  and a spring cup  22  by torque tightening the stud  20  into the spring cup  22  to form a diaphragm subassembly  55 . 
         [0050]    The diaphragm subassembly  55  is installed in the body  10  such that the stud  20  engages with the closure member  14 . The engagement between the stud  20  and the closure member  14  is provided by locating the closure member  14  into a recess formed in the stud  20 . In alternative arrangements, the closure member may be engaged with and/or retained to the stud  20  by providing a gripping engagement of some form, such as by using threaded engagement, barbed engagement or clip. The diaphragm assembly  55  is assembled into position using a non-threaded grip ring  30  which in turn has a clamp force applied thereto by torque tightening clamp ring  29   a.    
         [0051]    The illustrated arrangement uses a load spring  23  arranged to provide a biasing or load force to the closure member  14  acting counter to the bias spring  16  by application of force via the diaphragm subassembly  55  onto the closure member  14 . 
         [0052]    To provide an acting surface against which the load spring can act, and to provide for adjustment in the net load force according to the present example, a spring guide  25  is fitted to an internal spigot in an adjuster housing  24  which is itself mounted to the main body  10 . The fit between the spring guide  25  and the spigot of the adjuster housing  24  is a close clearance fit to provide for smooth, unrestricted movement of the spring guide  25  over the spigot. The load spring  23  is installed between the spring guide  25  and the spring cup  22 . An adjuster  26  is threadedly received through an opening in the end of the spigot of the adjuster housing  24 . A ball  28  is received into a hole on the end of the adjuster  26  using an interference fit to form an adjuster and ball subassembly  56 . The adjuster and ball subassembly  56  can be wound in and out along the threaded engagement between the adjuster  26  and the spigot to provide for adjustment in the compression of the load spring  23  by causing movement of the spring guide  25 . 
         [0053]    An adjuster subassembly comprises the adjuster housing  24 , a spring guide  25  and the adjuster and ball subassembly  56 . The adjuster subassembly  57  is assembled into the main body  10  and the adjuster housing  24  is held in place into the receiving structure of the main body  10  by a torque tightened clamp ring  29   b.    
         [0054]    As illustrated, the load spring  23  side of the diaphragm  21  is vented to exterior pressure via a vent hole  100  in the adjuster housing  24 . The bias spring  16  urges the closure member  14  towards the diaphragm stud  20  thereby obtaining physical communication with diaphragm subassembly. The net spring force acting on the diaphragm is the load spring  23  force minus the bias spring force provided by spring  16 . 
         [0055]    The fluid flow through the pressure regulator illustrated in  FIGS. 1 a  to 1 c    will now be discussed. In use, a fluid enters the pressure regulator from a fluid source connected to the regulator at fluid inlet  70 . The fluid path is deflected around the closure member housing  11 . The upstream end of the closure member housing  11 , which is directed towards the incoming fluid proximate to the inlet of regulator has, in the present example, a conical shape. In other examples, the end of the closure member housing  11  may have a domed shape, a frusto-conical shape or a flat profile with chamfers or the like. The fluid path then passes between the annulus formed by the bore (receiving structure) of main body  10  and the closure member housing  11  and into the chamber inside the closure member housing  11  through radial holes or slots  71  in the closure member housing  11 . 
         [0056]    To set the pressure regulator with the desired outlet pressure set below the pressure of fluid supplied to the regulator inlet; the set screw  26  is adjusted to obtain a net load force acting on the closure member  14  via the load spring  23  and diaphragm subassembly  55  which urges the valve closure member  14  to provide an opening  72  with the valve seat  17  and to allow fluid to flow from the inside of the closure member housing  11  through to the radial holes or slots  73  in the valve seat housing  12 , into the gallery  74 , then to position  75 , then into a passage  75   a  connecting to the fluid outlet  75   b.  Pressure feedback to the diaphragm chamber  76  is substantially provided by communication of fluid pressure from the fluid path at position  75  near the entry to the outlet passage  75   a  to the diaphragm chamber via the aperture in orifice plug  31 . Fluid pressure in the diaphragm chamber  76  will increase until the force applied by fluid pressure and the closure member  14  acting on the diaphragm subassembly  55  is sufficient to move the diaphragm subassembly  55  to a position towards the left hand side of  FIG. 1 b    such that the total force applied towards the left balances with the net load force acting on the diaphragm towards the right. This balance position of the diaphragm subassembly, and therefore the closure member  14 , occurs when the opening  72  between the closure member  14  and the valve seat  17  is of a size that provides the required reduction in fluid pressure from the inlet pressure to obtain a pressure acting on the diaphragm at which there is force balance with the net load force. 
         [0057]    The pressure regulator therefore operates depending upon the outlet pressure to open or close the opening  72  by movement of the closure member  14  such that the ridge  14   a  blocks or provides a variable restriction to the flow path through valve seat  17 . The feedback pressure control enables the regulator to self-regulate to a set outlet pressure. The set outlet pressure can be adjusted using the adjuster  26  to vary the net load force acting on the diaphragm. 
         [0058]    By providing the configuration shown in  FIGS. 1 a -1 c    and as discussed above, using a deflection member to avoid direct impingement of incoming fluid flow on the closure member in a direction substantially parallel with the movement axis of the closure member, a compact design of pressure regulator can be produced having a high maximum fluid flow throughput. 
         [0059]    An embodiment of the present invention is illustrated in  FIGS. 2 a , 2 b   . The pressure regulator shown in  FIGS. 2 a  and 2 b    has a main body  10  into which the component parts of the pressure regulator are assembled as for the example shown in  FIGS. 1 a -1 c   . The operation of the closure member housing  11 , seat housing  12 , retainer  13 , closure member  14 , bearing  15 , bias spring  16 , valve seat  17 , diaphragm sub assembly  55 , and adjuster subassembly  56 , are similar to the corresponding arrangements described above with reference to  FIGS. 1 a   - 1   c.    
         [0060]    The main difference between the pressure regulator of this example and the regulator of the earlier example above is in the method and structure by which the diaphragm chamber senses the pressure of the fluid proximate to the regulator outlet. According to the arrangement illustrated in  FIGS. 2 a    &amp;  2   b , a hollow member  41  is assembled to the main body  10  (in a similar location to the orifice plug in the example shown in  FIG. 1 b   ). The deflection member discussed in relation to  FIGS. 1 a -1 c    is not an essential element of the present invention, but is a beneficial optional feature thereof. The hollow member  41  is mounted in the wall between the diaphragm chamber  76  and the channel  75 , with the stem of the hollow member  41  located in the transfer passage  75   a.  The hollow member  41  is assembled into the main body  10  by torque tightening a shouldered head of the hollow member  41  into a counterbore of a threaded hole in the main body  10 , similar to the hole through which the orifice plug is fitted in the earlier example above. 
         [0061]    As with the above examples shown in  FIGS. 1 a -1 c   , in-use, a fluid path through the regulator starts at fluid inlet  70 , is deflected by the closure member housing  11  and passes between the annulus formed by the bore of main body  10  and the closure member housing  11 . The fluid path enters into the chamber inside closure member housing  11  through radial holes or slots  71  in the closure member housing  11 . 
         [0062]    When the pressure regulator is, at least, partially open, fluid passes through opening  72  provided by the valve seat  17  and the ridge  14   a  of the closure member  14 . When the pressure regulator is fully closed, for example when the set pressure is set to zero fluid outlet pressure, opening  72  is closed off by valve seat  17  and the ridge  14   a  of closure member  14 . 
         [0063]    After passing through the opening  72 , the fluid path emerges through radial holes or slots  73  disposed around the axis of the valve seat housing  12 . The fluid flow through the plurality of radial holes/slots  73  in the valve seat housing  12  flows into the gallery  74  and exits the gallery through a passage  85  formed between the outside surface of the stem of hollow member  41  and a transfer passage  75   a.  Fluid exits the passage  85  to emerge into the transfer passage at  75   a.  The cross-sectional area of transfer passage  75   a  is larger than that of passage  85  resulting in higher velocity fluid entering slower velocity fluid at  75   a  with the associated reduction in pressure at  75   a  caused by the Venturi effect. The pressure at  75   a  is transferred to the diaphragm  21  via passage  87  through the inside of the hollow member  41  and the diaphragm chamber  76 . The fluid flow path continues from the transfer passage  75   a  to the fluid outlet  75   b.    
         [0064]    The method of sensing or transferring pressure proximate to the outlet of the regulator by use of the hollow member provides partial pressure compensation for the pressure drop between the downstream side of the valve seat and the regulator outlet. In other words it reduces the change in outlet port pressure for a change in flow through the regulator. This results in reduced pressure droop of the outlet pressure. 
         [0065]    As illustrated the stem of the hollow member  41  is circular in cross-section, but other cross-sections are contemplated. Also, as illustrated the passage  87  through the hollow member  41  is coaxial with the centreline axis of the hollow member  41 , but other orientations of the passage through the hollow member are envisaged. The cross-sectional area of the passage  85  formed between the outside of the stem of the hollow member  41  and the transfer channel  75   a  can vary between the point at which flow enters the narrowed section passage and the point at which the flow exits the passage into the full cross section of the transfer passage. 
         [0066]    As illustrated, the passage  85  cross section reduces in the direction of flow along the flow path by having a tapered outside profile of the stem of the hollow member  41  whilst installed in a cylindrical passage. In an alternative embodiment a hollow member with a cylindrical stem can be installed in a tapering transfer passage to provide a passage which gradually accelerates fluid as it flows through the passage formed between the stem of the hollow member and the transfer passage. 
         [0067]    In an alternative embodiment both the transfer passage and the outside of the hollow stem can have a tapered portion to provide a passage which reduces in cross-section towards the downstream end of the hollow member. 
         [0068]    In an alternative embodiment the cross-section of the passage between the outside of the stem of the hollow member and the transfer passage is substantially constant. 
         [0069]    In other examples, the fluid connection from the gallery  74  to the start of the passage  85  past the hollow may be via a slot or aperture with a cross sectional area preferably equal to or larger than that of the cross-sectional area of the full transfer passage. 
         [0070]      FIGS. 3 a -3 f    show a further example of a pressure regulator according to the present invention. 
         [0071]    The arrangement shown in  FIGS. 3 a -3 f    allows an even more compact construction than the example shown in  FIGS. 2 a -2 b   . This is achieved by disposing the hollow member  41  in a direction substantially perpendicular to the movement axis of the closure member  14  as opposed to disposing the hollow member  41  in a direction generally parallel to the movement axis of closure member  14  as shown in  FIGS. 2 a   - 2   b.    
         [0072]    The fluid path through the pressure regulator shown in  FIGS. 3 a -3 f    is substantially similar to that described with reference to  FIGS. 2 a -2 b   . The main differences being an additional transfer passage  97   a,  disposed on the fluid path between transfer passage  75   a  and fluid outlet  75   b,  additional transfer passages  99 ,  99   a  disposed on the fluid path between passage  87  and diaphragm chamber  76 , and additional transfer passage  95  disposed on the fluid path between gallery  74  and passage  85 . These additional transfer passages are included to allow for the disposal of the hollow member  41  in a direction substantially perpendicular to the movement axis of closure member  14 . By arranging the hollow member  41  in this orientation, the size of the pressure regulator can be made smaller as there is no need to allow sufficient depth for the hollow member  41  to extend between gallery  74  and the fluid outlet  75   b.    
         [0073]      FIG. 4  shows a pressure regulator according to another example. In this example, multiple fluid outlets  75   b  are provided, each having a corresponding hollow member  41 . By providing the pressure regulator with more than one hollow member  41 , the flow capacity of a regulator can be increased, unless or until the flow is limited by other limiting flow areas in the regulator flowpath. 
         [0074]    The remainder of the structure and operation of the pressure regulator is the same as that described for  FIG. 2 a -2 b    except that the fluid outlet flow from the gallery  74  is divided between the plurality of outlet paths with the corresponding plurality of hollow members  41 . In the present example, the plurality of fluid outlets  75   b  and corresponding plurality of hollow members are equally spaced around the axis of the pressure regulator to allow for a substantially symmetrical distribution of sensed pressures from the plurality of sensing positions downstream of the hollow members. 
         [0075]      FIG. 5  shows a pressure regulator according to another embodiment of the invention. The Figure shows an alternate arrangement where the fluid inlet and fluid outlet are substantially perpendicular to the movement axis of the closure member. In such an arrangement the deflection effect of closure member housing  11  is less pronounced than in the pressure regulator described with reference to  FIGS. 1 a - c   . However, the closure member housing  11  will substantially prevent fluid impinging on the closure member in a direction parallel with the movement axis of the closure member. 
         [0076]    In all of the examples shown in  FIGS. 2 to 4  the pressure droop in the outlet pressure at location  75   b  in the regulators is reduced and the useable flow range is increased by the use of the hollow member and deflection member configuration. 
         [0077]    For the regulator example shown in  FIG. 5  the hollow member and deflection member configuration reduces the droop in outlet pressure and increases the useable flow range, with the hollow member providing the main contribution to the reduction in droop in outlet pressure. 
         [0078]    The use of the hollow member configuration described, allows for a compact design of pressure regulator with reduced droop in outlet pressure with a high maximum fluid flow throughput, particularly, but not exclusively, when used in a regulator which has a deflection member configuration to partially shield the closure member as described for the first aspect of the invention. 
         [0079]    In an alternate embodiment of the regulators shown in  FIGS. 1-5  the valve closure member can be a ball operating in conjunction with a piston with said ball serving as the closure member acting on valve seat  17  and said piston being dimensioned to slidably operate in the bore of retainer  13  such that the load spring  23  can transmit force to the ball closure member via the diaphragm subassembly  55 . In this configuration one end of said piston is in physical contact with the ball and the other end is in physical contact with the diaphragm subassembly  55 . 
         [0080]    The above described concepts for producing a compact high throughput pressure regulator can be adapted to produce a pressure regulator with a variety of overall dimensions and flow capabilities. The above described concepts may also be used to provide pressure regulating valve for the second stage of a two stage pressure regulator valve. However, it will also be appreciated that although the techniques described herein are suited to the provision of a compact miniature pressure regulator, such techniques may also be employed to make compact larger scale pressure regulators. 
         [0081]    The above-described concepts for producing a compact high throughput pressure regulator can be adapted to produce a pressure regulator of either the relieving type (where excess downstream pressure is vented to the exterior of the pressure regulator) or the non-relieving type (where excess downstream pressure is not vented to the exterior of the pressure regulator). 
         [0082]    Although various components discussed above are described as being assembled in a particular order or as being held in place by particular structures, a pressure regulator consistent with the present teachings can be constructed using a variety of orders and directions of assembly for the various components and a variety of securing elements and mechanisms can be deployed. As just one example, it will be apparent from the figures that the receiving structure formed in the main body is illustrated in such manner as to indicate that this receiving structure could be manufactured by milling the receiving structure from the main body with the cross-section tending to generally reduce along the axis of the receiving structure. 
         [0083]    The principles, preferred embodiment and mode of operation of the present invention have been described in the foregoing specification. However, the invention which is intended to be protected is not to be construed as limited to the particular embodiments disclosed. Further, the embodiments described herein are to be regarded as illustrative rather than restrictive. The embodiments described above are given by way of example only and modifications will be apparent to persons skilled in the art without departing from the scope of the invention as defined by the appended claims.