Abstract:
A mechanism for coupling motion of a piezoelectric actuator in axisymmetric devices like modulating proportional valves uses actuator extension motion to cause translation away from a mechanism mounting plane and thereby enables lifting open of a valve element instead of the usual pushing closed of the valve element. The mechanism does not contain any gears nor leadscrew threads, and in usual practice is constantly loaded, so apparent change of direction is achieved without mechanical backlash introducing hysteresis. The mechanism surrounds a piezoelectric stack actuator by contacting opposite ends of the piezoelectric stack, whereby extension motion lengthening the actuator causes a lifting portion of the mechanism to translate toward the bulk of the actuator while the proximally adjacent mounting portion of the mechanism remains at a fixed location.

Description:
This application claims the benefit under 35 U.S.C. 119            of the filing date of Provisional U.S. Application Ser. No. 61/959,865, entitled Interlace Lifting Mechanism to Change Actuator from Push to Pull in Proportional Valve, filed on Sep. 4, 2013. This application is also related to U.S. patent application Ser. No. 13/794,517 entitled Multiflex Coupling, filed 11 Mar. 2013. Both of the foregoing applications are expressly incorporated herein by reference, in their entirety.
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is related to a mechanism for coupling motion of an actuator in axisymmetric devices like modulating proportional valves and is especially useful with regard to piezoelectric actuators. The mechanism uses actuator extension motion to cause translation away from a mechanism mounting plane and thereby enables lifting open of a valve element instead of the usual pushing closed of the valve element. The present inventive Interlace Lifting Mechanism can also be combined with the inventor&#39;s Multiflex Coupling, as disclosed in related application Ser. No. 13/794,517, already expressly incorporated by reference, in its entirety, herein, to provide increased stroke. The invention is particularly useful in valves intended for proportional, or modulating, control of fluid delivery within industrial processes making semiconductor devices, pharmaceuticals, or fine chemicals, and many similar fluid delivery systems. 
     The field of control valves intended for use within automated process control systems is broad and well known. Many proportional control valves have one or more movable elements that may be actively positioned, anywhere between an extreme open condition and an extreme closed condition, to adjust the flow of fluid passing therethrough. Fluid delivery apparatuses intended for manipulating process materials within semiconductor manufacturing equipment usually require attention to maintaining high purity of the delivered reactants and also are typically much smaller than valves used in petrochemical plants, for example. Nonetheless, many different types of powered valve actuators are found in high purity instrumentation and control apparatus such as mass flow controllers. U.S. Pat. No. 4,695,034 issued to Shimizu et al. describes use of a stack of piezoelectric disc elements to effect movement of valve parts in a mass flow controller. U.S. Pat. No. 4,569,504 issued to Doyle describes use of a magnetic solenoid with interleaved magnetic circuit elements. U.S. Pat. No. 5,660,207 issued to Mudd describes use of a heated resistance wire that changes length with temperature to effect valve element movement. U.S. Pat. No. 6,178,996 issued to Suzuki describes use of a pressurized fluid, such as nitrogen gas, in a bellows actuator to control the degree of opening of a diaphragm-operated control valve. 
     One disadvantage of both magnetic solenoid and thermal expansion type actuators is inherent constant power consumption when controlling valve elements are positioned at an intermediate condition, such as when actively regulating fluid flow. A piezoelectric actuator is effectively a capacitor in an electrical circuit, and therefore does not consume current when an applied voltage is constant. Consequently, typical piezoelectric control valve applications only require low power and avoid the undesirable generation of heat found in electromagnetic actuators. A piezoelectric actuator advantageously may produce substantially more force than a solenoid actuator of comparable size, but achievable strain severely limits the distance a piezoelectric stack can move. Valve power consumption is of particular concern in instrumentation devices such as compact mass flow controllers. 
     Piezoelectric actuators nearly always are used in a manner wherein applying an activation voltage causes an extensional increase in the stack length (see Shimizu et al. &#39;034 and U.S. Pat. No. 5,094,430 to Shirai et al.). Shimizu et al. increase the available movement by interposing a force transmission member, comprising a plurality of radial lever-arm fingers, between the stack of piezoelectric disc elements and the moving portion of the control valve. These force transmission members are complicated and difficult to manufacture correctly. Piezoelectric actuators are typically associated with normally open valves wherein increasing applied voltage then causes the valve to decrease fluid flow. Normally closed valves using piezoelectric actuators, wherein increasing applied voltage then causes the valve to increase fluid flow, often have a complicated fluid flow path structure with a poppet driven by a shaft passing through the valve seat orifice (e.g. see FIG. 3 and FIG. 10 of Shimizu et al. &#39;034) which may adversely impact fluid purity. A valve designer will benefit from having a mechanism to seemingly reverse the direction of actuator extension motion which thereby allows normally closed valves to use a piezoelectric actuator lifting a diaphragm to open the valve while avoiding the complexities and compromises of a shaft through the valve seat. 
     SUMMARY OF THE INVENTION 
     In consideration of the foregoing, the inventor has invented a mechanism that surrounds a piezoelectric stack actuator and contacts opposite ends of the piezoelectric stack, whereby extension motion (lengthening) of the actuator causes a lifting portion of the mechanism to translate toward the bulk of the actuator while the proximally adjacent mounting portion of the mechanism remains at a fixed location. The mechanism does not contain any gears nor leadscrew threads, and in usual practice is constantly loaded, so apparent change of direction is achieved without mechanical backlash introducing hysteresis. The following description may use notional directions (up and down, above and below, left and right, front and back, etc.) to assist understanding of relationships among the mechanism pieces, and illustrative drawing figures generally will match said notional directions, but it should be appreciated that an apparatus using the invention may attain any orientation in space, including actively translating or rotating or tumbling, without effect on the mechanism function. 
     In a typical embodiment the inventive mechanism is comprised of a mounting portion, a lifting portion, a cross-over support, and a coupling disc. The mounting portion has a central opening through which part of the lifting portion projects and the cross-over support sits against the mounting portion astride the lifting portion projection. The coupling disc functions as a resilient element uniting the mounting portion and the lifting portion, while maintaining radial and angular alignment, yet it allows axial movement of the lifting portion relative to the mounting portion and cross-over support. This over and under relationship among the fixed and moving parts of the mechanism prompts the inventor to identify his invention as an “Interlace Lifting Mechanism” for convenience of identification, but no additional significance nor limitation shall be thereby presumed. 
     In one embodiment  100  of an Interlace Lifting Mechanism a mounting portion may be formed as a circular mounting nut  10  with a threaded region  11  for engaging a mating thread formed in the body  99  of a fluid delivery apparatus. The mounting nut  10  is pierced axially by an oblong slot  12  and has a step feature  15  beyond the periphery of the oblong slot  12  to receive and locate a cross over plate  20 . A cross over plate  20  may conveniently be a disk shape with alignment  21  and clearance  22  features on its upper and lower surfaces. A lifting portion of the one embodiment may be comprised of three parts including a lifting housing  30 , an actuator housing  40 , and a housing lock nut  50 . The lifting housing  30  may be formed as a circular shell having an outward axially projecting traverse bar  32  of shape and dimension similar to the oblong slot  12  and extending diametrically across the open lower end  35  of the shell only partially covering the shell open lower end  35 . The lifting housing  30  is connected to a coupling disc  60  and the coupling disc  60  is connected to the mounting nut  10  thereby locating the traverse bar  32  projection within the oblong slot  12 . The cross over plate  20  may be positioned inside the lifting housing  30  against the partially exposed mounting nut  10  and located by the step feature  15  to be astride the traverse bar  32  axial projection and oblong slot  12 . 
     In the embodiment  100  of an Interlace Lifting Mechanism a lower end  91  of an actuator  90  may be coupled against the cross over plate  20 . The actuator housing  40  may be formed as a circular tube shape having threads  41  to engage mating threads  31  formed on the lifting housing  30  and an inward directed lip  45  may be formed on the upper end of the actuator housing  40  to contact the upper end  95  of the actuator  90 . Engagement between the actuator housing  40  and the lifting housing  30  may thus be adjusted until the actuator  90  is properly captured between the cross over plate  20  and the lip  45 . The housing lock nut  50  may then be used to prevent unintended changes of this engagement. An actuator preload spring  88  may be located between an inward lip  37  at the lower end of the lifting housing  30  and the lower end  91  of the actuator  90  to provide static compression of the actuator. Such preload spring  88  is particularly useful in the application of piezoelectric stack actuators. Applying an activation voltage to the piezoelectric stack causes an extensional increase in the actuator length that translates the actuator housing  40  away from the cross over plate  20  which rests upon the mounting nut  10 , and thereby moves the lifting housing  30  with its traverse bar  32  relative to the mounting nut  10  while deflecting the coupling disc  60 . A fluid driven actuator of hermetic design (without sliding seals) such as a hydraulic bellows may also be considered for use with the one embodiment  100  of an Interlace Lifting Mechanism. 
     It should be appreciated that a circular cross-section is chosen for the axisymmetric lifting housing  30  and actuator housing  40  merely for convenience, while an open frame type (typically but not solely bilaterally symmetric) structure would also suffice. In the situation of an open frame, a rectangular structure may surround a piezoelectric stack similar to a picture frame with the bottom of the frame comprising the lifting portion of the mechanism. It should also be appreciated that a flange may be used for attachment of the mounting portion of the mechanism and threaded fasteners, or other attachment methods such as welding or adhesives, can be used to secure the mechanism to a fluid delivery apparatus body  99 . 
     Another embodiment  500  of an Interlace Lifting Mechanism is constructed with a Multiflex Coupling, as described in detail within U.S. patent application Ser. No. 13/794,517, placed in series with a piezoelectric stack actuator within the inventive mechanism. A mounting portion of this other embodiment may be formed as a circular mounting nut  510  with a threaded region  511  for engaging a mating thread formed in the body  599  of a fluid delivery apparatus. The mounting nut  510  is pierced axially by an oblong slot  512  and has a step feature  515  beyond the periphery of the oblong slot  512  to receive and locate a cross over plate  520 . A cross over plate  520  may conveniently be a disk shape with alignment  521  and clearance  522  features on its upper and lower surfaces. A lifting portion of this other embodiment may be comprised of four parts including a lifting housing  530 , a Multiflex Coupling assembly, an actuator housing  540 , and a housing lock nut  550 . The lifting housing  530  may be formed as a circular shell having an outward axially projecting traverse bar  532  of shape and dimension similar to the oblong slot  512  and extending diametrically across the open lower end of the shell only partially covering the shell open lower end. The lifting housing  530  is connected to a coupling disc  560  and the coupling disc  560  is connected to the mounting nut  510  thereby locating the traverse bar  532  projection within the oblong slot  512 . The cross over plate  520  may be positioned inside the lifting housing  530  against the partially exposed mounting nut  510  and located by the step feature  515  to be astride the traverse bar  532  axial projection and oblong slot  512 . 
     In this other embodiment  500 , a Multiflex Coupling is placed in contact with the cross over plate  520  and also engaged with the lifting housing  530 . A threaded post feature  521  on the upper surface of the cross over plate  520  may conveniently fit into a mating threaded hole  579  in the lower reactive element  578  portion of the Multiflex Coupling. The upper passive element  575  portion of the Multiflex Coupling may be held against a shoulder  535  of the lifting housing  530  by a locking ring  584  (or other means such as threads, pins, crimping, or welding) whereby the passive element  575  and lifting housing  530  remain in located contact with each other and move in unison. A preload spring  588  between the cross over plate  520  and the Multiflex Coupling reactive element  578  provides force which is additional to that resulting from the mere zero-clearance adjustment of the mechanism elements and is particularly useful with piezoelectric actuator stacks. 
     In this other embodiment  500  of an Interlace Lifting Mechanism the lower end  591  of an actuator  590  may be placed in contact with the upper active shaft element  580  portion of the Multiflex Coupling. The actuator housing  540  may be formed as a circular tube shape having threads  541  to engage mating threads  531  formed on the lifting housing  530  and a top capping end  545  may be formed on the upper end of the actuator housing  540  to contact the upper end  595  of the actuator  590 . Engagement between the actuator housing  540  and the lifting housing  530  may thus be adjusted until the actuator  590  is properly captured between the Multiflex Coupling and the top capping end  545 . The housing lock  550  nut may then be used to prevent unintended changes of this engagement. Applying an activation voltage causes an extensional increase in the actuator stack length that translates the actuator housing  540  away from the active shaft element  580  which is connected to the pivot pin  582  within the Multiflex Coupling. The actuator housing  540  being in fixed engagement with the lifting housing  530 , in combination with the lifting housing  530  being in located contact with the passive element  575 , causes the passive element  575  to move relatively away from the active shaft  580  and pivot pin  582 . Relative motion between the pivot pin  582  and passive element  575  causes the rockers  576 , 577  to tip slightly and thereby increase the distance between the reactive element  578  and the passive element  575  by an amount defined by the mechanical gain of the Multiflex Coupling and the actuator extensional length increase. The passive element  575  being in located contact with the lifting housing  530 , while the reactive element  578  contacts the cross over plate  520  resting against the mounting nut  510 , thus moves the lifting housing  530  with its traverse bar  532  relative to the mounting nut  510  while deflecting the coupling disc  560 . 
     In one particular aspect of the invention, there is provided a mechanism for coupling motion of an actuator, the mechanism being adapted to surround the actuator and to contact opposite ends of the actuator, whereby an extension motion lengthening the actuator causes a lifting portion of the mechanism to translate toward a bulkier portion of the actuator while a proximally adjacent mounting portion of the mechanism remains at a fixed location. This mechanism is axisymmetric. The actuator may be a piezoelectric stack actuator. An actuator preload spring provides a compressive force against the actuator which is independent from valve closing forces. A coupling is interposed between the actuator and the mounting portion of the mechanism for increasing a stroke of the actuator. An actuator spring provides a compressive force against the actuator which is independent from valve closing forces. The axisymmetric mechanism comprises a modulating proportional valve. 
     In another aspect of the invention, there is provided a mechanism used for lifting a valve actuator which is powered by a piezoelectric stack. The mechanism comprises a mounting portion, a lifting portion, a cross-over support, and a coupling disc. The mounting portion comprises a mounting nut. The mounting nut is threaded for connection to a valve body. A shutoff spring is positioned by the mounting portion. In certain embodiments, the shutoff spring comprises a Belleville spring washer. The cross-over support comprises a cross-over plate. The lifting portion comprises a lifting housing, an actuator housing, and a housing lock nut. The coupling disc comprises a substantially flat ring fabricated from a resilient material having spring-like characteristics. 
     The invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in conjunction with the accompanying illustrative drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a cross-sectional view of one embodiment of an Interlace Lifting Mechanism cut axially across the oblong slot, and traverse bar, also showing the cross over plate sitting atop the mounting nut; 
         FIG. 1B  is a cross-sectional view of the embodiment of  FIG. 1 , cut axially along the oblong slot and showing the traverse bar passing under the cross over plate (section is perpendicular to that of  FIG. 1A ); 
         FIG. 2A  is a perspective view of a mounting nut for the inventive apparatus; 
         FIG. 2B  is a perspective view of a lifting housing of the present invention; 
         FIG. 2C  is a perspective view of a coupling disc of the present invention; 
         FIG. 3A  is an exploded view of the inverted stack of lifting housing, coupling disc, and mounting nut of the present invention; 
         FIG. 3B  is an exploded view like that of  FIG. 3A  with a quarter segment section removed to reveal the relationship of weld enabling features; 
         FIG. 3C  is a cross-sectional view of the apparatus of  FIG. 3B , fully assembled with welds indicated; 
         FIG. 4A  is a cross-sectional view through the inverted stack of lifting housing, coupling disc, and mounting nut, taken along lines B-B of  FIG. 4C , showing the weld attachment of the coupling disc and mounting nut; 
         FIG. 4B  is a cross-sectional view through the inverted stack of lifting housing, coupling disc, and mounting nut, taken along lines A-A of  FIG. 4A , showing the weld attachment of the coupling disc and lifting housing; 
         FIG. 4C  is a top view of the apparatus shown in  FIGS. 4A and 4B ; 
         FIG. 4D  is an enlarged cross-sectional view of the portion of  FIG. 4A  identified as DETAIL A; 
         FIG. 4E  is an enlarged cross-sectional view of the portion of  FIG. 4B  identified as DETAIL B; 
         FIG. 5A  is a cross-sectional view of another embodiment of an Interlace Lifting Mechanism constructed in accordance with the principles of the present invention, wherein the mechanism is cut perpendicular to the oblong slot and traverse bar while also being parallel to the pivot pin of the incorporated Multiflex Coupling assembly and thus sectioning both rockers; 
         FIG. 5B  is a cross-sectional view of the embodiment of  FIG. 5A , wherein the mechanism is cut parallel to the oblong slot and traverse bar while revealing one rocker of the Multiflex Coupling assembly; 
         FIG. 6A  is a perspective view of an alternative mounting nut; 
         FIG. 6B  is a perspective view of an alternative lifting housing; 
         FIG. 6C  is a perspective view of an alternative coupling disc; 
         FIG. 7A  is an exploded view of the inverted stack of the modified lifting housing, coupling disc, and mounting nut of  FIGS. 5A-6C , with connection pins to be inserted; 
         FIG. 7B  is an exploded view of the embodiment of  FIG. 7A  with a quarter segment section removed to reveal the relationship of pin receiving features; 
         FIG. 7C  is an assembled view of the embodiment as shown  FIG. 7B ; 
         FIG. 8A  is a cross-sectional view through the inverted stack of lifting housing, coupling disc, and mounting nut of the alternative embodiment of  FIGS. 5A-7C , taken along lines B-B of  FIG. 8C , showing the pinned attachment of the coupling disc and mounting nut; 
         FIG. 8B  is a cross-sectional view through the inverted stack of lifting housing, coupling disc, and mounting nut of the alternative embodiment of  FIGS. 5A-8A , showing the pinned attachment of the coupling disc and lifting housing; 
         FIG. 8C  is a top view of the apparatus shown in  FIGS. 8A and 8B ; 
         FIG. 8D  is an enlarged cross-sectional view of the portion of  FIG. 8A  identified as DETAIL A; and 
         FIG. 8E  is an enlarged cross-sectional view of the portion of  FIG. 8B  identified as DETAIL B. 
     
    
    
     DETAILED DESCRIPTION 
     This invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, the phrasing and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     Referring now more particularly to the drawings, a representative example of an Interlace Lifting Mechanism  100  may be affixed to a body  99  of a typical fluid delivery apparatus as illustrated in the assembly cross sectional views of  FIG. 1A  and  FIG. 1B . The fluid delivery apparatus may include a valve structure comprising a flow modulating element  97  movable by lifting a central shaft  96  and flexing a diaphragm  98  by action of the Interlace Lifting Mechanism  100 . The contemplated fluid delivery apparatus may be an active subsystem such as, for example, a mass flow controller or more simply an individual modulating valve. In fluid delivery equipment intended for semiconductor manufacturing, the valve body  99  will typically be made from high purity 316L stainless steel alloy, Hastelloy® C22® nickel alloy, or similar materials. The Interlace Lifting Mechanism  100  may have a mounting portion formed as a circular mounting nut  10  with a threaded region  11  for engaging a mating thread formed in the body  99  of the valve.  FIG. 2A  is a perspective view of the mounting nut  10  showing the described features. The mounting nut  10  may be made from a material similar to the apparatus body  99  or other more easily machined material because it is outside the fluid flow path and not in contact with delivered chemistries for which purity is an overarching consideration. An exterior threaded region  11  may function to secure the mounting nut  10  within the valve body  99 . It should be appreciated that a skilled designer may alternatively use a flange and threaded fasteners, or other attachment methods such as welding or adhesives, to secure the mounting nut  10  to the apparatus body  99 . 
     The mounting nut  10  may also axially position a shutoff spring  89  used to provide valve closing force which urges the movable flow modulating element  97  in the flow stopping direction. Such a spring provides valve closing force which is additional to the simple flexural characteristics of the valve diaphragm  98 . In one particular convenient implementation, the shutoff spring  89  may comprise a Belleville spring washer interposed between the mounting nut  10  and a thrust bushing  93 , which rides on the central shaft  96  to impart valve closing force to the diaphragm  98  and the flow modulating element  97 . One or more shims  87   a  may optionally be placed between the shutoff spring  89  and the thrust bushing  93  for purposes of finely adjusting the added valve closing force, and additional shims  87   b  may also function as a hardened bearing surface for the shutoff spring  89  to push against the mounting nut  10 . 
     The mounting nut  10  is pierced axially by an oblong slot  12  and has on its upper surface a step feature  15  beyond the periphery of the oblong slot  12  to receive and locate a cross-over plate  20 . The cross-over plate  20  may conveniently be a disk shape with alignment and clearance features on its upper and lower surfaces.  FIG. 1A  is a cross-section of the representative embodiment  100  of an Interlace Lifting Mechanism, cut perpendicularly to the oblong slot  12 , and a traverse bar  32  described further below, thereby showing the cross-over plate  20  sitting atop the mounting nut  10 . An alignment feature on the upper surface of the cross over plate  20  may be formed as a conical receptacle  21  and associated spherical bearing (or alternatively a hemispherical tipped load concentration pin) to mate with a suitable conical or similar concavity on a lower end  91  of an actuator  90  to accommodate minor actuator misalignment. A clearance feature on the lower surface of the cross-over plate  20  may be formed as a circular relief  22  to prevent interference with the coupling of the Interlace Lifting Mechanism  100  to movable elements of the valve, such as the central shaft  96  and associated retaining nut  94 . The cross-over plate  20  may be made from a heat treatable material such as 17-4PH steel, for example. Placement of the cross-over plate  20  is further described below. 
     A lifting portion of the illustrated embodiment may be comprised of three parts, including a lifting housing  30 , an actuator housing  40 , and a housing lock nut  50 . The lifting housing  30  (as illustrated in  FIGS. 1A &amp; 1B , and detailed in  FIG. 2B ) may be formed as a circular shell having the aforementioned outward axially projecting traverse bar  32  of shape and dimension similar to the mounting nut oblong slot  12  and extending diametrically across an open lower end  35  of the shell, but only partially covering the shell open lower end  35 . A stem hole  14  may be provided in the traverse bar  32  to facilitate linkage with the moveable portion of the valve such as the central shaft  96 . The open lower end  35  of the shell may optionally include a lip  37  for convenience in making the shell and traverse bar from a single piece of material. In the case of a lifting housing which includes a lip  37 , there may be one or more (typically two diametrically opposite) reliefs or axial penetrations  38 ,  39  cut into the lip  37 , thereby providing weld clearance when attaching to a coupling disc  60  as described further below. Additionally, the lip  37  may also axially position a preload spring  88  used to provide compressive preload to the actuator  90 . The preload spring  88  is particularly useful in the application of piezoelectric stack actuators by providing actuator compressing force which is additional to that resulting from the mere zero-clearance adjustment of the mechanism elements. A convenient implementation may comprise the aforementioned Belleville spring washer  88  interposed between the lip  37  and the lower end  91  of the piezoelectric stack actuator  90 . One or more shims  86  may optionally be placed between the preload spring  88  and the lip  37  for purposes of finely adjusting the added actuator compressing force, and these shims may also function as a hardened bearing surface for the preload spring  88  to push against. The circular shell of the lifting housing  30  may have one or more inward radial penetrations  33   a ,  34   a ,  33   b ,  34   b  (passing either partially or fully through the shell wall) that serve as points of engagement for a spanner wrench to help assemble the mechanism. The circular shell may include a threaded region  31  near the upper end for engagement of the actuator housing  40  as also described further below. 
     The lifting housing  30  is connected to the coupling disc  60  (as illustrated in  FIGS. 1A &amp; 1B , and detailed in  FIG. 2C ) and the coupling disc  60  is connected to the mounting nut  10 , thereby locating the traverse bar  32  projection within the oblong slot  12 . The coupling disc  60  may be formed as a flat ring shape with radially directed (inward directed being more convenient but not limiting for the representative embodiment  100 ) diametrically opposite tabs  68   a ,  69   a ,  68   b ,  69   b  as illustrated in  FIG. 2C  and made from a material suitable for use as a spring, such as 17-4PH steel for example, while being compatible with connecting to the lifting housing  30  and connecting to the mounting nut  10 . A convenient method of making these connections is by welding. In a typical manufacturing sequence the lifting housing shell  30 , the coupling disc  60 , and the mounting nut  10  are inverted and stacked in angular alignment as illustrated in  FIGS. 3A, 3B , &amp;  3 C. Weld forming energy, such as laser light or an electron beam, is directed into blind reliefs  18   a ,  19   a  in the underside of the mounting nut  10  to create welds  66   a ,  67   a  connecting the mounting nut  10  and coupling disc tabs  68   a ,  69   a  as illustrated in  FIG. 4A . During the same set-up, weld-forming energy may be directed through holes  18   b ,  19   b  through the mounting nut  10  to create welds  66   b ,  67   b  connecting the coupling disc tabs  68   b ,  69   b  to the lifting housing  30  as illustrated in  FIG. 4B . Threaded fasteners commensurate with dimensions of a particular Interlace Lifting Mechanism implementation may be used as an alternative to welding. 
     An alternative design using interference fit pins to connect a lifting housing to a coupling disc and the coupling disc to a mounting nut is described further below in conjunction with  FIGS. 6A-8E . The symmetry of the coupling disc  60 , sandwiched between and secured to the lifting housing  30  and mounting nut  10 , functions as a balanced pair of leaf springs allowing relative axial movement of the housing and nut while maintaining correct angular and radial location of the traverse bar  32  within the oblong slot  12 . 
     The actuator housing  40  in the embodiment  100  may be formed as a circular tube shape having threads  41  to engage mating threads in the threaded region  31  formed on the lifting housing  30  and an inwardly directed lip  45  may be formed on the upper end of the actuator housing  40  to contact an upper end  95  of the actuator  90 . Engagement between the actuator housing  40  and the lifting housing  30  may thus be adjusted until the actuator  90  is properly captured between the cross-over plate  20  and the lip  45 . The ring-shaped housing lock nut  50  may then be used to prevent unintended changes of this engagement. The housing lock nut  50  may have one or more inward radial penetrations  53   a ,  54   a ,  53   b ,  54   b  (passing either partially or fully through the ring wall) that serve as points of engagement for a spanner wrench to help assemble the mechanism. A simple sliding fit between the actuator housing  40  and the lifting housing  30  may be used as an alternative to threads  31 ,  41  along with other locking means such as pins, crimping, adhesives, or welding which are also contemplated. The actuator housing  30  may be made from materials having a chosen low coefficient of thermal expansion, such as Invar alloys or Molybdenum metal, in applications having potentially problematic temperature variations. One or more annular elastomeric elements  55 ,  56  such as O-rings may be placed between the actuator periphery and the actuator housing interior to assist with assembly, handling, and mounting. 
     The cross-over plate  20  may be positioned inside the lifting housing  30  against the partially exposed mounting nut  10  and located by the step feature  15  to be astride the axial projection and oblong slot  12  of the traverse bar  32 . In embodiment  100 , the lower end  91  of the piezoelectric stack actuator  90  may be coupled against the cross-over plate  20  by use of a hard spherical ball engaging the conical alignment feature  21 . Applying an activation voltage causes an extensional increase in the actuator stack length that translates the actuator housing  40  away from the cross-over plate  20 , which rests upon the mounting nut  10 , and thereby moves the lifting housing  30  with its traverse bar  32  relative to the mounting nut  10  while deflecting the coupling disc  60 . This motion may be observed as a decrease of a clearance  18  between the retaining nut  94  and a cross-over plate clearance feature  22 , a decrease of a clearance  17  between the top of the traverse bar  32  and the bottom of the cross-over plate  20 , and an increase of a clearance  16  between the bottom of the traverse bar  32  and the mounting nut  10  as illustrated in  FIG. 1B . 
     The aforementioned alternative embodiment  500  of an Interlace Lifting Mechanism is constructed with a Multiflex Coupling, as described in detail within U.S. patent application Ser. No. 13/794,517, placed in series with an actuator within the inventive Interlace Lifting Mechanism. This alternative example of an Interlace Lifting Mechanism  500  may be affixed to a body  599  of a typical fluid delivery apparatus as illustrated in the assembly cross-sectional views of  FIGS. 5A &amp; 5B . The fluid delivery apparatus may include a valve structure comprising a flow modulating element  597  movable by lifting a central shaft  596  and flexing a diaphragm  598  by action of the Interlace Lifting Mechanism  500 . The actuator may typically be a piezoelectric stack type actuator, but other high-force, low-strain devices (e.g. magnetostrictive elements) might also benefit from the stroke multiplication afforded by the Multiflex Coupling. In fluid delivery equipment intended for semiconductor manufacturing, the apparatus body  599  will typically be made from high purity 316L stainless steel alloy, Hastelloy® C22® nickel alloy, or similar materials. The apparatus  500  may have a mounting portion formed as a circular mounting nut  510  (as illustrated in  FIGS. 5A &amp; 5B ) with a threaded region  511  for engaging a mating thread formed in the body  599  of the apparatus. The mounting nut  510  may be made from a material similar to the apparatus body  599  or other more easily machined material, because it is outside the fluid flow path and not in contact with delivered chemistries for which purity is an overarching consideration. An exterior threaded region  511  may function to secure the mounting nut  510  within the apparatus body  599 , while it should be appreciated that a skilled designer may alternatively use a flange and threaded fasteners, or other attachment methods such as welding or adhesives, to secure the mounting nut  510  to the fluid delivery apparatus body  599 . 
     The mounting nut  510  may also axially position a shutoff spring  589  used to provide valve closing force, which urges the movable flow modulating element  597  in the flow stopping direction. Such shutoff spring provides valve closing force which is additional to the simple flexural characteristics of the valve diaphragm  598 . In one convenient implementation, the shutoff spring  589  may comprise a Belleville spring washer interposed between the mounting nut  510  and a thrust bushing  593 , which rides on the central shaft  596  to impart a valve closing force to the diaphragm  598  and flow modulating element  597 . One or more shims  587   a  may optionally be placed between the shutoff spring  589  and the thrust bushing  593  for purposes of finely adjusting the added valve closing force, and additional shims  587   b  may also function as a hardened bearing surface for the shutoff spring  589  to push against the mounting nut  510 . 
     The mounting nut  510  is pierced axially by an oblong slot  512  and has on its upper surface a step feature  515  beyond the periphery of the oblong slot  512  to receive and locate a cross-over plate  520 . The cross-over plate  520  (shown sectioned in  FIGS. 5A &amp; 5B ) may conveniently be a disk shape with alignment and clearance features on its upper and lower surfaces. An alignment feature on the upper surface of the cross over plate  520  may be formed as a post  521 , which may conveniently fit into a mating hole  579  in the lower reactive element  578  portion of the Multiflex Coupling (post  521  and mating hole  579  may additionally be actively coupled by mating threads when desired). A clearance feature on the lower surface of the cross over plate  520  may be formed as a circular relief  522  to prevent interference with means for coupling the mechanism  500  to movable elements of the valve, such as the central shaft  596  and associated retaining nut  594 . The cross-over plate  520  may be made from a heat treatable material such as 17-4PH steel, for example. Placement of the cross-over plate  520  is further described below. 
     A lifting portion of this alternative embodiment may be comprised of four parts including a Multiflex Coupling, a lifting housing  530 , an actuator housing  540 , and a housing lock nut  550 . The lifting housing  530  (as illustrated in  FIGS. 5A &amp; 5B ) may be formed as a circular shell having an outward axially projecting traverse bar  532  of shape and dimension similar to the mounting nut oblong slot  512  and extending diametrically across the open lower end of the shell only partially covering the shell open lower end. A stem hole  514  may be provided in the traverse bar  532  to facilitate linkage with the moveable portion of the valve such as the central shaft  596 . The open lower end of the shell may optionally include a lip  537  for convenience in making the shell and traverse bar. In the case of a lifting housing which includes a lip  537  there may be one or more (typically two diametrically opposite) reliefs and axial penetrations cut into the lip  537  for pins used to attach the coupling disc  560  as described further below. The circular shell of the lifting housing  530  may have one or more inward radial penetrations  533   a ,  534   a ,  533   b ,  534   b  (passing either partially or fully through the shell wall) that serve as points of engagement for a spanner wrench to help assemble the mechanism. The circular shell may include a threaded region  531  near the upper end for engagement of the actuator housing  540  as also described further below. 
     The lifting housing  530  is connected to a coupling disc  560  (as illustrated in  FIGS. 5A &amp; 5B ), and the coupling disc  560  is connected to the mounting nut  510 , thereby locating the traverse bar  532  projection within the oblong slot  512 . The coupling disc  560  may be formed as a flat ring shape with radially directed diametrically opposite tabs (inwardly directed being more convenient but not limiting for the representative embodiment  500 ), as illustrated in the example of  FIG. 6C  and made from a material suitable for use as a spring, such as 17-4PH steel for example, while being compatible with connecting to the lifting housing  530  and connecting to the mounting nut  510 . A convenient method of making these connections is by using interference fit pins  671 ,  672 ,  673 ,  674  to connect the lifting housing  530  to the coupling disc  560  and the coupling disc  560  to the mounting nut  510 , and is described and illustrated further below in conjunction with  FIGS. 6A-6C ,  FIGS. 7A-7C , and  FIGS. 8A-8E . An alternative design may use welding in a manner similar to that previously described for the Interlace Lifting Mechanism lacking a Multiflex Coupling as illustrated in  FIGS. 4A &amp; 4B . Threaded fasteners commensurate with dimensions of a particular Interlace Lifting Mechanism implementation may also be used. The symmetry of the coupling disc  560 , sandwiched between and secured to the lifting housing  530  and mounting nut  510 , functions as a balanced pair of leaf springs, allowing relative axial movement of the housing and nut while maintaining correct angular and radial location of the traverse bar  532  within the oblong slot  512 . 
     The cross-over plate  520  may be positioned inside the lifting housing  530  against the partially exposed mounting nut  510 , and located by the step feature  515  to be astride the traverse bar  532  axial projection and oblong slot  512 , as may be appreciated by considering  FIG. 5A . In the apparatus  500 , a Multiflex Coupling is placed in contact with the cross-over plate  520  and is also engaged with the lifting housing  530 . A threaded post feature  521  on the upper surface of the cross-over plate  520  may conveniently fit into a mating threaded hole  579  in the lower reactive element  578  portion of the Multiflex Coupling. The periphery of the upper passive element  575  portion of the Multiflex Coupling, and an associated center disk spring  585 , may be held against a shoulder  535  by a locking ring  584  threaded into the lifting housing  530 , whereby the passive element  575  and lifting housing  530  remain in located contact with each other and move in unison. The Multiflex Coupling passive element  575  is pierced through by a hole  570  to accommodate an active shaft  580 . The lower end  591  of a piezoelectric stack actuator  590  may be placed in contact with the upper active shaft element  580  portion of the Multiflex Coupling. An alignment feature on the upper end of the active shaft  580  may be formed as a hemispherical tipped load concentration pin  581  (or alternatively a conical receptacle and associated spherical bearing) to mate with a suitable conical or similar formed receptacle on the lower end  591  of the piezoelectric stack actuator  590  to accommodate minor actuator misalignment. The active shaft  580  may be centered and prevented from binding with the through hole  570  by use of a disk spring  585  conveniently located against a shoulder formed on the upper end of the active shaft  580 . An optional preload spring  588  may be placed between the cross-over plate  520  and the lower reactive element  578 , whereby action of the Multiflex Coupling causes the load concentration pin  581  to be urged against the lower end  591  of the piezoelectric stack  590 . Such preload spring  588  provides force which is additional to that resulting from the mere zero-clearance adjustment of the mechanism elements, and is particularly useful with piezoelectric actuator stacks. A convenient implementation may comprise a Belleville spring washer  588  interposed between the lower reactive element  578  and the top of the cross over plate  520 . One or more shims (not shown) may optionally be placed between the preload spring  588  and the active element  578  for purposes of finely adjusting the added actuator compressing force and these shims may also function as a hardened bearing surface for the preload spring  588  to push against. The active shaft  580  may be made from a heat treatable material such as 17-4PH steel, for example, while the disk spring  585  may be made from the same or other suitable material such as 300 series stainless steel. 
     The actuator housing  540  may be formed as a circular tube shape having threads  541  to engage mating threads  531  formed on the lifting housing  530 . A top capping end  545  may be formed on the upper end of the actuator housing  540  to contact most of the upper end  595  of the piezoelectric stack actuator  590  excepting any electrical connections. Engagement between the actuator housing  540  and the lifting housing  530  may thus be adjusted until the piezoelectric stack  590  is properly captured between the Multiflex Coupling upper active shaft  580  and the top capping end  545 . The housing lock nut  550  may then be used to prevent unintended changes of this engagement. The ring-shaped housing lock nut  550  may have one or more inward radial penetrations  553   a ,  554   a ,  553   b ,  554   b  (passing either partially or fully through the ring wall) that serve as points of engagement for a spanner wrench to help assemble the mechanism. In a similar manner the actuator housing  540  may have one or more inward radial penetrations  551   a ,  552   a ,  551   b ,  552   b  (passing either partially or fully through the tube wall) that serve as points of engagement for a spanner wrench to help assemble the mechanism. A simple sliding fit between the actuator housing  540  and the lifting housing  530  may be used as an alternative to threads  531 ,  541  along with other locking means such as pins, crimping, adhesives, or welding which are also contemplated. The actuator housing  540  may be made from materials having a chosen low coefficient of thermal expansion, such as Invar alloys or Molybdenum metal, in applications having potentially problematic temperature variations. One or more annular elastomeric elements  555 ,  556  such as O-rings may be placed between the actuator periphery and the actuator housing interior to assist with assembly, handling, and mounting. 
     Operation of the Multiflex Coupling is fully described in U.S. patent application Ser. No. 13/794,517, entitled Multiflex Coupling, as already referenced above. A complete Multiflex Coupling assembly for the instant embodiment includes an upper disk shaped element  575 , two rocker elements  576 ,  577  placed side by side and below the upper disk, and a lower disk shaped element  578  under the rocker elements. A single pivot pin  582  passes through the pivot pin hole of the two semicircular rocker elements and lock pins (four pins  571 ,  572 ,  573 ,  574  being shown in  FIG. 5B ), to secure the ends of four links within respective axial slots in the several elements. Two links descend from two axial slots of the upper disk shaped element  575  and each link engages a corresponding axial slot in the below adjacent rocker element (the identical rocker elements  576 ,  577  being mirrored). Two additional links descend from the second axial slot of each rocker element  576 ,  577 , and each link engages a corresponding axial slot in the below adjacent lower disk shaped element  578 . In accordance with the embodiment  500  of the inventive mechanism, the upper disk shaped element  575  is made passive and held axially fixed relative to the bulk of the actuator  590  by function of the lifting housing shoulder  535  in conjunction with the locking ring  584  and the top capping end  545  of the actuator housing  540 . Extension of the actuator  590  is coupled by the active shaft  580  to move the pivot pin  582  which functions in an active manner, whereby extension of the actuator  590  moves the active pivot pin  582  axially away from the actuator bulk while the reactive lower disk shaped element  578  also extends away from the actuator bulk. The upper end of each rocker element  576 ,  577  is restrained by the attached link pointing upward from each rocker coupled to the axially fixed upper disk shaped passive element  575 , as may be appreciated by considering the lock pins  573 ,  574  visible in the cross section illustration of  FIG. 5B . Axial movement of the actuator  590  displaces the active shaft  580  that passes through the upper disk-shaped passive element  575 , and engages the active pivot pin  582 , whereby axial movement of the active pivot pin  582  is directly coupled to the rocker elements  576 ,  577 . The illustrated rocker element  576  is thereby caused to slightly rotate about the lock pin  573  of its upward pointing link (not visible) at one end (left) of the illustrated rocker  576  and downward motion of the middle of the illustrated rocker (imparted by the pivot pin  582 ) results in further downward motion of the other end (right) of the illustrated rocker  576 . The downward moving other end of the illustrated rocker  576  is coupled to the reactive lower disk shaped element  578  by the attached downward pointing link (not visible) and its associated lock pins  571 ,  572 . The other rocker  577  is not illustrated in  FIG. 5B , due to being located within the mechanism portion that is illustratively removed by creating the sectioned view, but functions in like manner. The reactive lower element  578  translates axially in proportion to motion of the active shaft  580  and in the same direction. The proportionality between motion of the active shaft  580  and motion of the reactive element  578  may be adjusted by choice of the separation between the lock pin holes and the pivot pin hole in the pair of rocker elements  576 ,  577 . 
     Applying an activation voltage to the piezoelectric stack actuator  590  causes an extensional increase in the actuator length that translates the actuator housing  540  away from the active shaft element  580 , which is connected to the pivot pin  582  within the Multiflex Coupling. The actuator housing  540 , being in fixed engagement with the lifting housing  530 , in combination with the passive element  575  being in fixed contact with the lifting housing shoulder  535 , causes the passive element  575  to move relatively away from the pivot pin  582 . Relative motion between the pivot pin  582  and passive element  575  cause the rockers  576 ,  577  to tip slightly and to thereby increase the distance between the reactive element  578  and the passive element  575  by an amount defined by the mechanical gain of the Multiflex Coupling and the actuator extensional length increase. The passive element  575  being axially fixed with the lifting housing  530 , while the reactive element  578  contacts the cross over plate  520  resting against the mounting nut  510 , thus moves the lifting housing  530  with its traverse bar  532  relative to the mounting nut  510  while deflecting the coupling disc  560 . This motion may be observed as a decrease of the clearance  518  between the retaining nut  594  and cross-over plate clearance feature  522 , a decrease of the clearance  517  between the top of the traverse bar  532  and the bottom of the cross over plate  520 , and an increase of the clearance  516  between the bottom of the traverse bar  532  and the mounting nut  510  as illustrated in  FIG. 5B . 
     Another alternative design using interference fit pins to connect a lifting housing to a coupling disc and the coupling disc to a mounting nut will now be described. This pinned attachment design may be used with a simple Interlace Lifting Mechanism as illustrated in  FIGS. 1A &amp; 1B , or a more complicated Interlace Lifting Mechanism design incorporating a Multiflex Coupling as illustrated in  FIGS. 5A &amp; 5B . The pinned attachment design uses a mounting nut  610  illustrated in  FIG. 6A , which is substantially similar to previously shown mounting nuts  10 ,  510  wherein it is pierced axially by an oblong slot  612  and has on its upper surface a step feature  615  beyond the periphery of the oblong slot  612  to receive and locate a cross over plate (not shown). The pinned attachment design uses a lifting housing  630  as illustrated in  FIG. 6B , which is substantially similar to previously shown lifting housings  30 ,  530  wherein it is formed as a circular shell having an outward axially projecting traverse bar  632  of shape and dimension similar to the oblong slot  612  and extending diametrically across the open lower end  635  of the shell only partially covering the shell open lower end  635 . A stem hole  614  may be provided in the traverse bar  632  to facilitate linkage with the moveable portion of the valve. The open lower end  635  of the shell includes a lip  637  for convenience in making the shell and traverse bar from a single piece of material. In the case of this alternative lifting housing design, the lip  637  has two diametrically opposite blind bores  642 ,  644  to receive attachment pins  672 ,  674  and two diametrically opposite reliefs  641 ,  643  cut into the lip  637 , providing head clearance for similar pins  671 ,  673  pointed in the opposite axial direction. Similarly, the pinned attachment mounting nut  610  has cut into the underside two diametrically opposite blind bores  621 ,  623  to receive attachment pins  671 ,  673  and two diametrically opposite reliefs  622 ,  624  cut into the underside providing head clearance for the opposing pins  672 ,  674 . 
     The pinned attachment design lifting housing  630  is connected to a coupling disc  660  (detailed in  FIG. 6C ) and the coupling disc  660  is connected to the mounting nut  610  thereby locating the traverse bar  632  projection within the oblong slot  612 . The coupling disc  660  may be formed as a flat ring-shaped spring with radially directed diametrically opposite (inward directed being more convenient but not limiting) tabs  661 ,  662 ,  663 ,  664  having corresponding pin accommodating through holes  666 ,  667 ,  668 ,  669  as illustrated in  FIG. 6C . The attachment connections are effected by pins  671 ,  672 ,  673 ,  674 , with low profile heads being inserted into the coupling disc tab through holes  666 ,  667 ,  668 ,  669  and the pin bodies forced into interference fit within the corresponding blind bores  621 ,  623 ,  642 ,  644  of the mounting nut and lifting housing. The illustrations show a smooth shank on the pins and a smooth blind bore but designers will appreciate the feasibility of using grooved or serrated pins, serrated blind bores, and other known methods of achieving a desirable tight mechanical connection. 
     In a typical manufacturing sequence, the lifting housing shell  630 , the coupling disc  660 , and the mounting nut  610  are inverted and stacked in angular alignment as illustrated in  FIGS. 7A, 7B , &amp;  7 C. The lifting housing  630  would first be positioned, then a first pair of pins  671 ,  673  projecting upward would be placed head down into the reliefs  641 ,  643 ; next the coupling disc  630  would be placed over the first pair of pins  671 ,  673  with those pins projecting upward through a first pair of opposite tabs  661 ,  663 ; then a second pair of pins  672 ,  674  would be inserted downward through the second pair of opposite tabs  662 ,  664  and starting to enter the pair of housing blind bores  642 ,  644 ; then the mounting nut  610  would be aligned so the oblong slot  612  accommodates the traverse bar  632  and the pair of underside blind bores  621 ,  623  begin to engage the upward projecting first pair of pins  671 ,  673 . The connection of the pieces in the stacked assembly would next be completed by applying axial compression force urging the housing  630  and mounting nut  610  together thereby forcing the pins  671 ,  672 ,  673 ,  674  into the corresponding blind bores  621 ,  623 ,  642 ,  644 . It is also feasible to use a light press fit between the tab through holes  666 ,  667 ,  668 ,  669  and the pins  671 ,  672 ,  673 ,  674 , allowing the pins to be inserted into the coupling disc  660  and handled as a single subassembly item. The cross-sectional illustrations of  FIGS. 8A &amp; 8B  further reveal the first pair of pins  671 ,  673  attaching the coupling disc  660  to the mounting nut  610  and the second pair of pins  672 ,  674  attaching the coupling disc  660  to the housing  630 . 
     Having thus described several aspects of this invention, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.