Abstract:
The invention provides a method of, and means for, connecting components of a moveable sub-assembly in a fluid control valve. To control a dimensional characteristic of the moveable sub-assembly, a first component of the sub-assembly can be crimped to create a mechanical connection to a second component of the moveable sub-assembly. The sub-components may be configured such that in the absence of the crimp they can be moveably translated between a plurality of positions and they may be slideably translatable between a number of relative positions, while the crimp acts, once formed, to retain the sub-components in a chosen position relative to one another.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to actuation means for use in fluid control valves. In particular, the invention relates to assemblies and methods for fine adjustment and fixing of component sub-assemblies during manufacture of the valve. 
       BACKGROUND 
       [0002]    There can be a need in fluid control valves to fine-tune the dimensions of components of the valve, or of sub-assemblies of components of the valve. This can be due to potential variations in the dimensions of various sub-component parts, which may be the result of natural variance or inaccuracies in the manufacturing processes of components of the valve or its sub-assemblies. It is therefore important to be able to fine-tune dimensions of an assembly during the assembly process, to ensure that the correct sub-assembly dimensions, tolerances and/or clearances are achieved in the final valve assembly. 
         [0003]    One way to adjust the dimension of a component is to use a threaded connection to achieve variations in longitudinal dimensions of a sub-assembly, by rotation of the components of the sub-assembly relative to one another, and to optionally use a glue to lock the two sub-components at a chosen relative position. 
         [0004]    However, there are various problems with using a threaded connection and/or glue. Using a threaded connection has associated production costs and introduces mechanical gaps into the sub-assembly. These mechanical gaps may be detrimental to the valve performance, for example if the sub-component parts are a shaft and a plunger of a solenoid valve, using a threaded connection to connect the shaft and the plunger may reduce the magnetic performance of the solenoid valve. 
         [0005]    Various problems can occur when using a glue to connect sub-component parts. One problem can be that the glue may limit the potential uses of the valve, as the glue may not be suited to coming into contact with an incompatible liquid, for example a corrosive liquid or any liquid that may react with or dissolve the glue or cause any chemical from the glue to leach into the liquid. Another problem with using a glue to secure two sub-component parts can be that the glue takes time to set, which may increase the production time for the valve and causes associated costs. Another problem with using a glue to secure two sub-component parts is that the glue&#39;s quantity may not be easily controlled. Another problem with using a glue to secure sub-component parts can be that the method of using a glue to attach the two sub-components may be susceptible to errors both in the accuracy of the dimension of the component, and the accuracy of the adhesive property of the glue. For example, the chemical composition and setting time of the glue may need to be controlled in order to give the required adhesive property. The setting reaction of the glue may be susceptible small errors caused by variations in temperature, atmospheric conditions and manufacturing contaminations. Small errors in the glue setting reaction may affect the setting time, which in turn can reduce the ability to accurately control the final dimension of the component since movement could occur during setting of the glue. 
         [0006]    There is therefore a need for improved means to for attaching valve sub-components to one another. 
       STATEMENTS OF INVENTION 
       [0007]    The invention provides a method of; and means for, connecting components of a moveable sub-assembly in a fluid control valve. To control a dimensional characteristic of the moveable sub-assembly, a first component of the sub-assembly can be crimped to create a mechanical connection to a second component of the moveable sub-assembly. The sub-components may be configured such that in the absence of the crimp they can be moveably translated between a plurality of positions and they may be slideably translatable between a number of relative positions, while the crimp acts, once formed, to retain the sub-components in a chosen position relative to one another. 
         [0008]    A crimp is a plastic deformation of a first component, which causes it to fit with a second component to retain the components in a fixed relative position and/or orientation. One of the first and second components therefore grips the other once the crimp has been formed. The components are generally fixed to one another by a mechanical connection once the crimp has been formed. The crimp may restrict movement in any direction or orientation between the components or may restrict longitudinal or lateral movement while allowing movement in a second direction, or while allowing relative rotation of the components relative to one another. 
         [0009]    According to a first aspect of the invention, there is provided a valve. The valve comprises: a first fluid port; a second fluid port; an orifice providing a fluid connection between the first and second fluid ports; and a moveable sub-assembly. The moveable sub-assembly is moveable between a first position in which the fluid connection is open and a second position in which the fluid connection is closed by the moveable sub-assembly. The moveable sub-assembly comprises first and second sub-components. The first and second sub-components are mechanically connected by a crimp to fix a position of the first sub-component relative to the second sub-component. 
         [0010]    The valve may comprise a valve seat disposed about the orifice. The valve seat may be configured to engage the moveable sub-assembly in the second position. The moveable sub-assembly may comprise a sealing portion configured to seal the valve seat to close the fluid connection between the first and second ports. The sealing portion may comprise a flexible diaphragm. The sealing portion may comprise a rigid diaphragm. 
         [0011]    The valve may comprise a biasing means configured to bias the valve toward an open or closed position. The valve may comprise a biasing means configured to bias the valve toward a substantially open or a substantially closed position. 
         [0012]    The first sub-component may be at least partially received inside the second sub-component and the crimp may be a mechanical deformation of the first sub-component. The first sub-component may be a shaft received at least partially within the second sub-component. 
         [0013]    The second sub-component may comprise one or more openings configured to enable access to a crimping region to form the crimp. The second sub-component may comprise two openings, the two openings being arranged on substantially opposite sides of the second sub-component. The second sub-component may have a first end oriented away from the orifice, and a second end oriented towards the orifice, and the openings may be located towards the first end. 
         [0014]    The second sub-component may be configured to receive an actuating force of an actuator of a valve. The second sub-component may be connected to an actuator of the valve. The second sub-component may be a plunger of a solenoid for actuating the valve. The actuator may comprise a shape memory alloy (SMA) element. 
         [0015]    The actuator may be a thermal actuator, a magnetic actuator, a manual actuator, a hydraulic actuator, a piezoelectric actuator, a pneumatic actuator, or an electric actuator. The actuator may be isolated from the flow of fluid through the valve. 
         [0016]    The actuator may be arranged substantially to one side of the orifice, and fluid flow towards and away from the orifice may be substantially to and from the second side of the plane of the orifice. The first fluid port and the second fluid port may extend in substantially the same direction. Fluid flow may pass through the orifice in a first direction and turn through at least a right angle to flow away from the orifice. 
         [0017]    The second fluid port may be in fluid communication with a plurality of valve orifices. Each valve orifice may be configured to be opened or closed by a respective moveable member. Each moveable member may comprise first and second sub-components, the respective first and second sub-components being mechanically connected by a crimp to fix a position of each first sub-component relative to each respective second sub-component. The valve may comprise a plurality of first parts in fluid communication with the plurality of valve orifices. 
         [0018]    According to a second aspect of the invention, there is provided a method of forming a moveable valve sub-assembly for a fluid control valve comprising the steps of: providing first and second sub-components for a moveable subassembly of a fluid control valve; adjusting a position of the first and second sub-components relative to one another; and forming a crimp on one of the first and second sub-components to fix their relative positions in at least a first direction. 
         [0019]    The method of forming a moveable valve sub-assembly for a fluid control valve may comprise the step of; measuring the relative positions of the first and second sub-components in at least a first direction prior to forming the crimp. 
         [0020]    The method may comprise the step of; crimping one of the first and second sub-components using a mechanical crimping tool to fix the relative positions of the first and second sub-components in at least a first direction. 
         [0021]    The method may comprise the steps of: inserting the first sub-component at least partially into the second sub-component; and forming the crimp on the first sub-component within the second sub-component. 
         [0022]    The crimp may be formed directly on the first sub-component by the crimping tool. 
         [0023]    The second sub-component may comprise one or more openings, and the method may comprise inserting at least one crimping tool into the one or more openings. The two openings may be arranged on substantially opposite sides of the second sub-component. 
         [0024]    The first sub-component may be a shaft of a valve. The second sub-component may be a plunger of a solenoid or other actuating means for actuating a valve. 
         [0025]    The method described in the second aspect of the invention may be applied to the valve described in the first aspect of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0026]      FIG. 1  shows a prior art valve assembly; 
           [0027]      FIG. 2  shows an embodiment of a valve according to the present invention; 
           [0028]      FIG. 3  shows the valve sub-assembly of the valve of  FIG. 1  being crimped by a crimping tool; 
           [0029]      FIG. 4  shows an enlarged view of the valve sub-assembly of  FIG. 3  being crimped by a crimping tool; 
           [0030]      FIG. 5  shows a further embodiment of a valve comprising a sub-assembly according to the present invention; and 
           [0031]      FIG. 6  shows an embodiment of a valve sub-assembly according to the present invention being aligned by an alignment tool and crimped by a crimping tool. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0032]    The prior art valve  1  shown by the schematic illustration in  FIG. 1  has a valve body  2 , a moveable sub-assembly  10 ′, an actuating means  3  and a cover  29 . The moveable sub-assembly  10 ′ extends inside the valve  1  along an axis A. 
         [0033]    The moveable sub-assembly  10 ′ of the valve  1  has a shaft  100 ′, a seal  110 ′ formed on the shaft  100 ′ and a magnetic plunger  200 ′. The shaft  100 ′ extends at least partially inside the plunger  200 ′ along the axis A and the shaft  100 ′ extends at least partially outside the plunger  200 ′ along the axis A. 
         [0034]    The shaft  100 ′ is substantially cylindrical and has a first end  106 ′ and a second end  107 ′. The shaft  100 ′ terminates in a head  101 ′ at the shaft second end  107 ′. The head  101 ′ extends radially outwardly of the shaft such that in cross-section the head  101 ′ is symmetrical about the axis A. The shaft  100 ′ has a screw thread  102 ′ proximate the shaft first end  106 ′. 
         [0035]    The plunger  200 ′ is substantially cylindrical and has a first end  206 ′ and a second end  207 ′. The plunger  200 ′ has a first blind bore  208 ′ proximate the plunger first end  206 ′. The plunger  200 ′ has a biasing means  210 ′. The biasing means  210 ′ extends along the first blind bore  208 ′. The biasing means extends at least partially inside the plunger  200 ′ and at least partially outside the plunger  200 ′ along an axis A. The biasing means  210 ′ is a spring. The plunger  200 ′ has a second blind bore  209 ′ proximate the plunger second end  207 ′. The second blind bore  209 ′ is threaded. The thread of the second blind bore  209 ′ is adapted to engage with the screw thread  102 ′ of the shaft  100 ′. 
         [0036]    The shaft  100 ′ is attached to the plunger  200 ′ by the screw thread  102 ′ of the shaft and the threaded second blind bore  209 ′ of the plunger. The shaft  100 ′ and the plunger  200 ′ are fixed in place by a glue (not shown). 
         [0037]    The seal  110 ′ is attached to the shaft  100 ′ at the second end  107 ′ of the shaft. The seal  110 ′ has a flexible diaphragm  112 . The flexible diaphragm  112  extends radially from the shaft and terminates in a rim  111 . The diaphragm  112  acts to isolate the fluid path through the valve from the actuating means  3 , and the moveable sub-assembly  10 ′. 
         [0038]    The moveable sub-assembly  10 ′ extends inside the actuating means  3  along an axis A. The actuating means  3  is a solenoid. 
         [0039]    The cover  29  surrounds and/or encloses substantially all of the moveable sub-assembly  10 . The cover  29  surrounds and/or encloses substantially all of the actuating means  3 . 
         [0040]    The valve body  2  has a first fluid port  21 , a second fluid port  22  and a valve seat  23 . The valve body  2  has a body first end  26  and a body second end  27 . The first fluid port  21  and the second fluid port  22  extend from the body second end  27  towards the body first end  26 . The first fluid port  21  is aligned along the axis A. The second fluid port  22  is radially offset relative to the first fluid port  21 . The second fluid port  22  is separated from the first fluid port by a separating wall  28 . The valve seat  23  surrounds an orifice  24  providing a fluid connection between the first port  21  and the second port  22 . The valve seat  23  is configured to engage the seal  110 . 
         [0041]    The moveable sub-assembly  10 ′ is attached to the valve body  2  by the biasing means  210 . The moveable sub-assembly is also attached to the valve body  2  at the rim  111  of the seal  110 . 
         [0042]    The moveable sub-assembly  10 ′ is adapted to move axially between two positions, a fully closed position and a fully open position. In the fully open position, the first fluid port  21  and the second fluid port  22  are in fluid communication. In the fully closed position, the first fluid port  21  and the second fluid port  22  are not in fluid communication. In the fully open position, the shaft  100 ′ and the plunger  200 ′ are moved away from the valve body  2 , while in the fully closed position the shaft  100 ′ and the plunger  200 ′ are moved toward the valve body  2  to close the orifice  24 . 
         [0043]      FIG. 2  shows a valve according to a first embodiment of the present invention. The valve  20  shown by the schematic illustration in  FIG. 2  has a body  2 , a moveable sub-assembly  10 , an actuating means  3  and a cover  29 . The moveable sub-assembly  10  extends inside the valve  1  along an axis A. 
         [0044]    The valve body  2  is configured to define at least part of a fluid pathway through the valve  20 . The valve body  2  may be attachable to an apparatus that defines a continuation of the fluid pathway, the continuation of the fluid pathway being in fluid communication with the fluid pathway through the valve  20 . 
         [0045]    The valve sub-assembly  10  is adapted to move relative to the valve body  2 . The valve sub-assembly can be adapted to move relative to the valve cover  29 . The valve sub-assembly can be adapted to move relative to the actuating means  3 . 
         [0046]    The valve sub-assembly  10  is adapted to create at least a partial variation in flow restriction through the fluid pathway upon actuation by the actuating means  3 . The valve sub-assembly  10  may be adapted to completely close the fluid pathway upon actuation by the actuating means  3 . The valve sub-assembly  10  may be adapted to open the fluid pathway upon actuation of the actuating means  3 . 
         [0047]    The actuating means  3  is configured to apply an actuating force to the sub-assembly  10 . In particular, the actuating means  3  may apply an actuating force to the plunger  200 . The actuating force can move the sub-assembly  10  in a direction X. The direction X may be towards the valve body  2  as shown in  FIG. 2 . The actuating force may be in the opposite direction, such that the actuator  3  applies an actuating force to move the sub-assembly  10  in an opposite direction to direction X. The opposite direction can therefore be away from the valve body  2 . Suitable actuating means can be arranged to create an actuating force both in the direction of arrow X and/or in the opposite direction, to open and close the valve. 
         [0048]    The sub-assembly  10  may be subject to a biasing force, by way of a biasing means  210 . The biasing force may, for example, be provided by means of the illustrated spring  210  attached to the sub-assembly  10 . The biasing means  210  can be adapted to move the sub-assembly  10  in a direction X upon removal of an actuating force. The biasing means  210  may be adapted to move the sub-assembly  10  in an opposite direction to the direction X upon removal of an actuating force. 
         [0049]    The cover  29  can be provided to protect the components of the valve  20 . The cover  29  may be adapted to connect and/or contain components of the valve  20 . 
         [0050]    It will be apparent that some features of the valve of the invention are common to both the prior art valve of  FIG. 1  and the valves of the embodiments of the invention described in the following. Similar features are therefore labelled with common reference numerals. The principal differences lie in the methods and means used to connect parts of the moveable sub-assembly  10  to one another and embodiments are described in more detail in the following. 
         [0051]    The moveable sub-assembly  10  of a valve  1  according to embodiments of the invention has a shaft  100 , a seal  110  formed on the shaft  100 , and a plunger  200 . A limiter  108  may also be included as described in further detail below. 
         [0052]    The plunger  200  is configured to be actuated by the actuating means  3 . The plunger  200  may comprise a material susceptible to magnetisation and the actuating means  3  may comprise a solenoid coil. As will be shown in later embodiments, other forms of actuating means for the plunger can be envisaged. The illustrated plunger  200  has a longitudinal length L, in the direction of actuation of the plunger. 
         [0053]    The shaft  100  is configured to connect the plunger  200  to the seal  110 . The shaft  100  and the plunger  200  may be adjusted before crimping and their positions relative to each other may be measured and controlled before the crimping takes place. The shaft  100  is configured to fix the position of the plunger  200  relative to the position of the seal  110 . The shaft  100  is adapted to be fixed to the plunger  200  upon crimping of the shaft  100 . The shaft  100  may be adapted to be fixed to the plunger  200  such that no relative movement is permitted in a first direction. The first direction is preferably the direction of actuation of the plunger, or of its longitudinal axis A. The shaft  100  may be adapted to be fixed to the plunger  200  such that no relative movement is permitted in a second direction different to the first. The shaft  100  may be adapted to be fixed to the plunger  200  such that no relative movement is permitted in a third direction different to the first and second directions. The first, second and third directions may be substantially orthogonal. The first direction may be aligned with the direction X. The second direction may be a rotation, which may be about the axis A. The shaft and plunger may be adapted to be fixed to each other so that no relative movement in any direction is permitted. However, as described in the above, some degree of movement in one or more directions may be permitted after the crimp in certain examples. 
         [0054]    The seal  110  may have a substantially planar shape as illustrated in  FIG. 2 . The seal  110  may be arranged substantially perpendicularly to the longitudinal axis of plunger  200 . The seal may be arranged substantially perpendicularly to the shaft  100 . The seal  110  can be adapted to be movable within the valve  20 , such that the seal  110  may be moveable towards the valve body  2  and/or the orifice  24 . The seal  110  may be retained in the valve such that it can only move in two directions, substantially parallel to the axis A. The seal  110  may be restricted so that it can only move in two directions, in the direction X and in the opposite direction to the direction x. The seal  110  can be adapted to contact the valve body  2  upon movement of the sub-assembly  10  in the direction x. 
         [0055]    The limiter  108  may optionally be provided and can act to restrict the movement of the sub-assembly  10  relative to the valve body  2 . The limiter  108  may restrict movement of the valve sub-assembly  10  such that the valve sub-assembly  10  has at least one limit to translational movement controlled by the limiter  108 . The limiter  108  can place an upper limit on the distance that the sub-assembly  10  can move away from the valve body  2  if so desired. This can prevent the flexible diaphragm  112  from being over-extended. 
         [0056]    In the example shown, the shaft  100  extends at least partially inside the plunger  200  along the axis A and the shaft  100  extends at least partially outside the plunger  200  along the axis A. 
         [0057]    In a preferred embodiment, the shaft  100  is substantially cylindrical and has a first end  106  and a second end  107 . The shaft  100  can, in the illustrated example, have a stem  104 . The stem  104  can terminate in a head  101  at the shaft second end  107 . The bead  101  may extend radially outwardly of the shaft stem  104  and in cross-section the head  101  may be symmetrical about the axis A. The shaft may also have a shaft bulb  103 . The shaft bulb  103  may be attached to the shaft head  101  by a neck. The shaft may have a smaller diameter than the diameter of the head  101 . The optional shaft bulb  103  has a diameter that is larger than the diameter of the neck. The shaft bulb  103  may have a radial groove. The shaft bulb  103  is preferably symmetrical about the axis A. The radial groove of the shaft bulb  103  is symmetrical about the axis A. Axis A is preferably parallel to and may be coaxial with a longitudinal axis of the shaft  100 . 
         [0058]    The seal  110  is attached to the shaft  100  at the second end  107  of the shaft. The seal  110  is attachable to any or all of the shaft head  101 , shaft neck and shaft bulb  103 . The seal  110  preferably has a base  113 . The base  113  extends radially from the shaft and preferably terminates in a rim  111 . 
         [0059]    The illustrated example of a limiter  108  has a limiter base and a flange. The limiter base may be disposed between the base  113  of the seal  110  and the plunger  200 . The flange of the limiter  108  may extend both radially and axially from the limiter base. The flange may be frusto-conical. The flange may extend further radially than the plunger  200 , thus having a greatest radial dimension larger than that of the plunger  200 . 
         [0060]    The plunger  200  may be substantially cylindrical. The plunger  200  has a first end  206  and a second end  207 . The plunger  200  may have a plunger ledge  201 , taking the form of a substantially radial projection about at least a part of its outer surface. The plunger  200  may have a plunger rim  202 . The plunger  200  may have a bore  211  for receiving the shaft. The bore  211  may extend from the plunger first end  206  to the plunger second end  207 , or only partially trough the plunger. The bore  211  may terminate in a cavity  212  at the plunger second end  207 , having a larger diameter than the bore  211 . The plunger ledge  201  may extend radially from the plunger  200 . The plunger ledge  201  may be located between the plunger first end  206  and the plunger second end  207 . The plunger rim  202  can extend radially from the plunger  200 . The rim can act to provide a reaction surface for the biasing means for the plunger. The plunger rim  202  may be located at the plunger second end  207 . The axial dimension of the plunger ledge  201  may be larger than the axial dimension of the plunger rim  202 . 
         [0061]    The plunger  200  may have a biasing means  210 . The biasing means  210  may be located at least in part along the plunger  200  between the plunger ledge  201  and the plunger rim  202 . The biasing means  210  may be a spring or other resilient means such as an elastic member. 
         [0062]    The plunger  200  may have one or more openings  215 . The opening(s)  215  extend from the plunger bore  211  to the outer edge of the plunger  200 . The openings  215  are located between the plunger first end  206  and the plunger second end  207 . The openings  215  may be located towards the plunger first end  206 , such that a length defined between the openings  215  and the first end  206  is smaller than a length defined between the openings and the second end  207 . The openings  215  may be substantially cylindrical. The openings  215  may be on substantially opposite sides of the plunger  200 . The openings  215  may be oriented such that they collectively have rotational symmetry about the axis A of 180°. The openings  215  may be substantially perpendicular to the bore  211 . The openings  215  are adapted to receive a crimping tool and can allow the crimp to be applied to the shaft  104  internally to the plunger  200 . 
         [0063]    A person skilled in the art will recognise that there are many workable variations of the plunger opening form and location. Their primary function is to allow a crimp to be applied to the shaft inside the plunger  200 . The openings  215  may be located at the plunger second end  207 . The openings  215  may be located at any point along the plunger  200 . The openings  215  may define any arbitrary shape that allows a crimping tool to pass through the openings  215 . 
         [0064]    The shaft  100  may extend inside the plunger. The bore  211  of the plunger  200  may be adapted to receive the stem  104  of the shaft  100 . The shaft  100  may be adapted such that the shaft stem  104  can extend within the plunger  200 , such that the shaft stem  104  extends past the openings  215  along the axis A. The dimension defined between the openings  215  and the cavity  212  of the plunger  200  may be less than the axial dimension of the shaft stem  104 . The head  101  of the shaft  100  may have a diameter that is larger than the diameter of the bore  211 . The head  101  of the shaft may alternatively have a diameter that is smaller than the diameter of the cavity  212  of the plunger  200 . 
         [0065]    The shaft  100  is fixedly attachable to the plunger  200  by crimping. Upon crimping the shaft  100  by inserting a crimping tool into the openings  215 , the shaft  100  may locally deform radially outwards. Upon crimping, the shaft  100  may be fixedly attached to the plunger  200  in a region around the openings  215  of the plunger  200 . Upon attachment of the shaft  100  and plunger  200  by crimping, the shaft  100  and plunger  200  are held in a fixed position in at least one direction. 
         [0066]    Many workable variations in shape of the shaft  100  are possible. Many variations in the orientation and position of the shaft  100  relative to the plunger  200  are possible. Crimping of the shaft  100  is possible if the shaft  100  extends at least partially past at least one of the openings  215  of the plunger  200 . 
         [0067]    The moveable sub-assembly  10  may extend inside the actuating means  3  along an axis A. The cover  29  may surround and/or enclose substantially all of the moveable sub-assembly  10 . The cover  29  may surround and/or enclose substantially all of the actuating means  3 . 
         [0068]    As shown in the illustrated embodiment, the valve body  2  has a first fluid port  21 , a second fluid port  22  and an orifice  24  between the first and second fluid ports, the orifice preferably further having a valve seat  23 . The valve body  2  has a body first end  26  and a body second end  27 . The second fluid port  22  may extend substantially radially from the axis A. 
         [0069]    The first fluid port  21  may extend both axially along the axis A and radially from the axis A. The second fluid port  22  may be separated from the first fluid port  21  by a separating wall. The separating wall may extend radially. The valve seat  23  may surround the orifice  24 , which provides a fluid connection between the first fluid port  21  and the second fluid port  22 . The valve seat  23  may be configured to engage the seal  110 . 
         [0070]    The moveable sub-assembly  10  may be attached to the valve body  2  by the biasing means  210 . 
         [0071]    The moveable sub-assembly  10  is adapted to move axially between two positions, a closed position and a open position. The two positions may be a substantially closed position and a substantially open position. In the open position, the first fluid port  21  and the second fluid port  22  are in fluid communication. In the closed position, the first fluid port  21  and the second fluid port  22  are not in fluid communication. In the open position, the shaft  100  and the plunger  200  may be moved away from the valve body  2 , while in the fully closed position the shaft  100  and the plunger  200  may be moved towards the valve body  2  to close the orifice  24 . It will be appreciated that a range of intermediate positions between the open and closed positions can be envisaged, and a range of intermediate flow restrictions between the first and second ports will be provided by the valve over this range of positions. 
         [0072]      FIG. 3  shows a section through the valve sub-assembly  10  according to the present invention during the crimping process. The valve sub-assembly  10  of  FIG. 3  has the openings  215  of the plunger located inside the plunger ledge  201 . As shown by  FIG. 2 , the openings  215  of the plunger  200  may be located at any point along the plunger  200 . 
         [0073]    The crimping tool  30  may comprise one or more, preferably two, crimping toll members  31 . The crimping tool members  31  may be substantially cylindrical. The crimping tool members may each have a crimping apex  32 . The crimping tool members  31  may each be tapered to a line which defines an apex  32  of the respective crimping tool members  31 . Each opening  215  of the plunger  200  may be adapted so that a crimping tool members  31  can be inserted into the or each opening  215 . 
         [0074]    Although in  FIG. 3  the crimping tool apex  32  is tapered to a line, it will be appreciated that the crimping tool apex  32  may be any shape. For example, the crimping tool apex may be a point, a line, a circle, a polygon or any arbitrary shape. 
         [0075]      FIG. 3  shows one crimping tool member  31  inside one of the openings  215  of the plunger  200 , and one crimping tool member  31  aligned with the other opening  215  of the plunger  200 . 
         [0076]    As can be appreciated from  FIG. 3 , the crimping tool member or members can be used to apply a crimp to one or both sides of the shaft  100  and the resulting deformation causes a portion of the shaft to engage a portion of the plunger  200  and to lock them in fixed relative positions. 
         [0077]      FIG. 4  shows an enlarged view of the valve sub-assembly section of  FIG. 3 . The crimped region of the shaft  100  in  FIG. 4  is highlighted. 
         [0078]      FIG. 5  shows a valve assembly  130  according to a second embodiment of the present invention. Where reference numerals used in  FIG. 5  are the same as reference numerals used in  FIGS. 2 to 4 and 6 , the duplicated reference numeral refers to either the same component or a similar alternative component.  FIG. 5  illustrates how the crimping method of the invention may be utilised in conjunction with alternative valve actuating means. In this case a shape memory alloy actuating element is shown, but other actuating means can be envisaged. The primary function of the crimp is to set a distance between the sealing end of the moveable sub-assembly and the actuating means. 
         [0079]    As in the previous embodiments, the valve assembly  130  may have a valve body  2 , a moveable sub-assembly  10 , an actuating means  3  and may further include a support structure  503 . The moveable sub-assembly  10  may extend inside the valve  1  along an axis A. 
         [0080]    The moveable sub-assembly  10  of the valve  130  may have a shaft  100 , a membrane  505  formed on the shaft  100  and a plunger  200 . The shaft  100  may extend at least partially outside the plunger along the axis A. 
         [0081]    The shaft  100  may be substantially cylindrical. The shaft  100  has a first end  106  and a second end  107 . The shaft  100  may have a homogenous cross-section along the length of the shaft  100 . The shaft  100  may be the same shape as the shaft  100  shown in any of  FIGS. 1 to 4 and 6 . 
         [0082]    The membrane  505  may be attached to the shaft  100  at the second end  107  of the shaft. The membrane  505  may extend radially from the shaft  100  between the valve body  2  and the valve support structure  503 . 
         [0083]    The plunger  200  may be substantially cylindrical. The plunger  200  may have a first cod  206  and a second end  207 . The plunger  200  may have a homogenous cross-section along the length of the plunger  200 . The plunger  200  may be substantially the same shape or form as the plunger  200  shown in any of  FIGS. 1 to 4 and 6  and may include any or all of the feature of the plunger  200  of the earlier figures. 
         [0084]    The plunger  200  may have a bore  211 . The bore may extend from the plunger first end  206  to the plunger second end  207 . The plunger  200  may have a biasing means  210 . The biasing means  210  may be located at the plunger first end  206 . 
         [0085]    The plunger  200  may have two openings  215 . The openings  215  may extend radially from the plunger bore  211  to the outer edge of the plunger  200 . The openings  215  may be located between the plunger first end  206  and the plunger second end  207 . The openings  215  may be located towards the first end, such that a length defined between the openings  215  and the first end  206  is smaller than a length defined between the openings and the second end  207 . The openings  215  may be substantially cylindrical. The openings  215  may be on substantially opposite sides of the plunger  200 . The openings  215  may be oriented such that they collectively have rotational symmetry about the axis A of 180°. The openings  215  may be substantially perpendicular to the bore  211 . The openings  215  may be adapted to receive a crimping tool. 
         [0086]    The plunger  200  may have a mechanical connection  502 . The mechanical connection  502  may be arranged towards the plunger second end  207 . 
         [0087]    The shaft  100  may extend inside the plunger  200 . The bore  211  of the plunger  200  may be adapted to receive the shaft  100 . The shaft  100  may be adapted such that the shaft  100  can extend within the plunger  200 , such that the shaft  100  extends past the openings  215  along the axis A. 
         [0088]    The shaft  100  is fixedly attachable to the plunger  200  by crimping. Upon crimping the shaft  100  by inserting a crimping tool into the openings  215 , the shaft  100  may locally extend radially outwards. Upon crimping, the shaft  100  may be fixedly attached to the plunger  200  in a region around the openings  215  of the plunger  200 . Upon attachment of the shaft  100  and plunger  200  by crimping, the shaft  100  and plunger  200  are fixed in at least one direction. 
         [0089]    The valve body  2  may have a first fluid port  21 , a second fluid port  22  and a valve seat  23 . The valve body  2  may have a body first end  26  and a body second end  27 . 
         [0090]    The first fluid port  21  may extend from the body second end  27  towards the body first end  26 . The second fluid port  22  may extend from the body second end  27  towards the body first end  26 . 
         [0091]    The first fluid port  21  may be aligned along the axis A. The second fluid port  22  may be disposed radially to the first fluid port  21 . The second fluid port  22  may be separated from the fast fluid port by a separating wall. The separating wall may extend axially. The valve seat  23  may surround an orifice  24  providing a fluid connection between the first fluid port  21  and the second fluid port  22 . The valve seat  23  may be configured to engage the membrane  505 . 
         [0092]    The moveable sub-assembly  10  may be attached to the support structure  503  by the biasing means  210 . The support structure  503  may support the plunger  200  in a desired orientation for switching the valve between open and closed positions. The support structure  503  may be disposed about the plunger  200  such that the plunger  200  is substantially between opposite parts of the support structure  503 . The support structure  503  may comprise engagement points  501 . The engagement points  501  may be arranged toward the plunger first end  206 . 
         [0093]    The support structure  503  may be a Printed Circuit Board (PCB). The PCB  503  may be provided with electrical connection points  506  for providing electric current to the engagement points  501 . The engagement points  501  may be configured for coupling a Shape Memory Alloy (SMA) element  504  to the support structure. Likewise, the mechanical connection  502  may be configured to engage the SMA element  504  which is coupled to the support structure  503 . 
         [0094]    The moveable sub-assembly  10  may be adapted to move axially between two positions, a fully closed position and a fully open position. The two positions may be a substantially closed position and a substantially open position. In the fully open position, the first fluid port  21  and the second fluid port  22  may be in fluid communication. In the fully closed position, the first fluid port  21  and the second fluid port  22  may not be in fluid communication. In the fully open position, the shaft  100  and the plunger  200  may be moved away from the valve body  2 . In the fully closed position the shaft  100  and the plunger  200  may be moved towards the valve body  2  to close the orifice  24 . 
         [0095]    SMA element  504  may be coupled to an engagement point  501  toward a first side of the support structure  503  and to a further engagement point  501  toward a second side of the support structure. SMA element  504  may pass via a mechanical connection  502  on the plunger  200  on its route between those points. 
         [0096]    SMA element  504  may be a wire element. In the illustrated arrangements, it is possible to have a relatively simple connection between the SMA element and the plunger by effectively ‘looping’ the SMA element around the connection pin  502  and connecting to connection points to either side of the support structure  503 . 
         [0097]    This is a straight forward way to provide a balanced force to drive the plunger  200  in a straight direction. By providing a fixed connection between a single connection point  501  and the plunger, a single SMA element  504  can be provided between the plunger  200  and the SMA element  504  to actuate the plunger  200  relative to the support structure  503 . 
         [0098]    Pressure provided by the plunger  200  to isolation membrane  505  may move the membrane  505  to close the fluid flow path and maintains a tight seal. It will be appreciated that SMA elements  504  may comprise a plate, or a film deposition etc. and would still perform the appropriate function. 
         [0099]    The SMA element  504  is actuated to cause movement of the plunger  20 . When first engagement points  501  are energized through the provision of an electrical current, the SMA element  504  is thermoelectrically heated. Shape memory alloys are metals that are generally known for their physical transformation at a transition temperature. By combining the appropriate alloys, the transition temperature of the SMA element  504  can be determined and tailored. The transition temperature is generally understood as the temperature at which an SMA material transforms from a first crystal structure e.g. martensite, to a second crystal structure e.g. austenite. When the exemplary SMA element  504  is below the transition temperature, the metal has a martensitic crystal structure. Whilst in the martensitic crystal orientation, the alloy can be plastically deformed into a first size and/or shape, and remain in the deformed shape while below the transition temperature. When the deformed shape is heated to above the transition temperature, the exemplary material transforms into the austenite crystal structure, where the alloy returns to its “memorized”, pre-deformed, second size and/or shape. The transformation that occurs in SMA materials is relatively fast as no diffusion occurs. This unique property of SMA materials can be utilized in the valve  1  in order to selectively open or close the valve  1  as discussed below. 
         [0100]    The thermoelectrical heating of the SMA element or elements  504  is achieved through applying a differential voltage and/or current between two or more electrical contacts. Actuation of an attached SMA element  504  can cause the plunger to either open or close the fluid path between the first fluid port  21  and the second fluid port  22 . 
         [0101]    It will be appreciated that although one mechanical connection  502  is shown on the plunger  200 , the valve assembly  130  could operate having two mechanical connection points. 
         [0102]    The valve  130  may comprise a magnet  507  at the first end  206  of the plunger  200 . Magnet  507  may be a permanent magnet. A force/pressure sensor  508  may optionally be provided which can indicate, when the plunger is in the “open” position, the force or pressure of the fluid that is applied to the membrane  505 . The sensor can be connected to control electronics of the valve assembly, preferably on the PCB  503 . 
         [0103]      FIG. 6  shows the valve sub-assembly  10  of  FIG. 3 , a crimping tool  30  and a dimension-setting apparatus  40 . The valve sub-assembly  10  and crimping tool  30  are as described previously. 
         [0104]    The details of apparatus suitable for supporting and moving the valve components in the manner illustrated, and actuating the crimping members to form the crimp will be evident to one skilled in the manufacture of valve assemblies in light of the following teaching and so these are not described in detail in the following sections. The dimension-setting apparatus  40  may have a base platform  42 , a base rod  41  and a measuring arm  43 . Suitable supports and drive means can be provided by known means to support the base platform  42 , base rod  41  and measuring apparatus  43  and to permit them to be automatically or manually moved relative to one another. The crimping members  30  can be supported and/or driven by suitable linear drive means such as hydraulic rams, rack and pinion arrangements, or any other form of substantially linear drive, to advance the crimping members into and out of the openings  215  in the plunger  200 . 
         [0105]    Suitable manually or automatically moveable supports can also be provided for the measuring means  43 , base platform  42  and base rod  41 , to support and move them relative to one another. It will be appreciated that the main direction of movement required for the method described is in the direction of the axis of the plunger  200  and shaft  100 , to allow them to be moved relative to one another in a longitudinal direction, and for that longitudinal movement to be measured by the measurement means  43 . The measurement means  43  can be any suitable linear displacement measuring device, such as a linear variable differential transformer, piezoelectric measurement device or any other suitable means as will be apparent to the reader skilled in valve assembly methods and apparatus in light of the present disclosure. 
         [0106]    To perform the required crimping, the plunger  200  may be placed onto the base platform  42  and the shaft  100  is placed inside the plunger  200  so that the shaft  100  rests on the base rod  41 . The shaft  100  is configured so as to be moveable relative to the plunger  200 , in the axial direction of the shaft  100  and the plunger  200  until the above described crimp is formed to fix the two components together. It can therefore be appreciated that axial movement of the base platform  42  relative to the base rod  41  can create axial movement between shaft  100  and plunger  200 . This movement can vary the overall distance of the seal  110  from a set reference point on the plunger of the sub-assembly  10 . The measuring arm  43  may be moved towards the base platform  42  until the measuring arm  43  reaches the seal  110  of the shaft  100 . The measuring arm  43  can then measure a longitudinal dimension of the sub-assembly  10 , for example, between the end of the plunger resting on the base platform and the seal  110 . This distance can then be set to a chosen or predetermined position relative to the base platform  42 . The base rod  41  may be moved towards and/or away from the measuring arm  43 , simultaneously moving the shaft  100  relative to the plunger  200 , until the seal  110  of the shaft  100  reaches the chosen measured position measured by measuring arm  43 . Once the relative positions of the shaft  100  and the plunger  200  have been set by the dimension-setting apparatus, and whilst still held in place by the dimension-setting apparatus, the shaft  100  may be crimped by the crimping tool  30  to hold it in a fixed axial position relative to the plunger  200 . Although a radial crimp from opposite sides of the shaft  100  is shown, other types of crimp may be envisaged. A radial crimp from one side may be sued. Alternatively, a crimp may be formed to coincide with an outwardly extending groove in the bore of the plunger, so that although the longitudinal length of the sub-assembly  10  is fixed, a degree of rotation between the plunger  200  and shaft  100  can be realised if desired. The crimp therefore may not necessarily prevent all movement between the plunger and the shaft  100 . 
         [0107]    Although a specific form and arrangement of valve sub-assembly is shown in the figures, it will be appreciated that aesthetic changes could be made to the device shown whilst still performing the function of the present invention as defined in the appended claims. 
         [0108]    In particular, further to the solenoid actuator  3  and the SMA actuator described in the first and the second embodiments respectively, any workable valve actuator may be used. For example, the actuator  3  may be a manual actuator, a hydraulic actuator, a piezoelectric actuator, a pneumatic actuator, or an electric actuator. Other variations on the embodiments shown and described can be envisaged without departing from the scope of protection as defined in the appended claims