Abstract:
A control plate for effecting superior shut-off in a proportional control valve comprises a moveable disk-shaped element that has a flat surface, generally perpendicular to the valve axis of symmetry when closed, and translates toward or away from an orifice surrounded by a narrow lip or orifice ridge. Enhanced leak tightness in the valve shut-off condition is achieved by selectively incorporating into the control plate materials that are softer than the material comprising the orifice ridge.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 62/190,478 titled “CONTROL PLATE IN A VALVE,” filed Jul. 9, 2015, and Provisional Application Ser. No. 62/292,526 titled “CONTROL PLATE IN A VALVE,” filed Feb. 8, 2016, each of which is incorporated by reference herein in its entirety for all purposes. 
     
    
     BACKGROUND 
       [0002]    The present invention is related to a moveable portion of a fluid control valve that may be actively positioned, anywhere between an extreme open condition and an extreme closed condition, to adjust a flow of fluid passing therethrough. 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 high-purity fluid delivery systems that simultaneously demand a leak-tight shut-off in the fully closed condition along with proportional control. Many combinations of metallic and elastomeric elements enhancing valve shut-off are known in the art. 
       SUMMARY 
       [0003]    Applicant has invented uniquely manufacturable configurations of a moveable valve element suited for use with various sized valve orifices. The moveable disk-shaped element has a flat surface generally perpendicular to the valve axis of symmetry when closed and translates toward or away from an orifice surrounded by a narrow lip or orifice ridge. This combination of valve structures is sometimes referred to as being the jet &amp; seat class of fluid pathway element combinations. In this disclosure the flat surfaced element (colloquially a seat) which closes against the narrow lip (colloquially a jet) surrounding the orifice is often referred to as a control plate. Enhanced leak tightness in the valve shut-off condition is provided by selectively incorporating into the control plate materials that are softer than the material comprising the lip or ridge surrounding the orifice. Control plate materials being softer than the orifice ridge-lip allows elastic deformation of the control plate surface as it presses against the orifice ridge-lip and thereby enhances the sealing effected between the control plate and the orifice ridge-lip. The disclosed arrangements can use welding or interference press-fit pieces to avoid problems associated with having threads within high purity fluid pathways. 
         [0004]    One embodiment comprises a metallic seat housing having a small diameter central insert of polymer material held in place by a metallic retaining ring pressed into a gap between the outside diameter of the polymer insert and the inside diameter of a seat housing counterbore. Another embodiment comprises a ring of polymer material held in place by a metallic retaining ring pressed into a gap between the inside diameter of the polymer ring and the small internal diameter of a trepanned channel in the control plate, and a metallic retaining ring pressed into the gap between the outside diameter of the polymer ring and the large internal diameter of the trepanned channel in the control plate. Another embodiment comprises a small diameter central insert of a corrosion resistant Nickel alloy typically retained by welding to the larger control plate. Another embodiment comprises a control plate substantially made of a corrosion resistant Nickel alloy with a cover piece optionally made from another alloy. 
         [0005]    In one aspect of the present disclosure, a valve control plate is provided that is configured to sealingly engage a fluid conduit opening surrounded by a planar orifice ridge. The valve control plate comprises a valve control plate body and a valve seat insert. The valve control plate body is formed from a first material having a first hardness, the valve control plate body having a first surface configured to face toward the fluid conduit opening. The valve control plate body has a recess defined in the first surface of the valve control plate body. The valve seat insert is formed from a second material having a second hardness that is less than the first hardness, the valve seat insert having a first surface configured to face toward the fluid conduit opening and sealingly engage the planar orifice ridge, the valve seat insert being received in the recess. 
         [0006]    In some embodiments, the recess is one of a counterbore or a trepanned groove. 
         [0007]    In some embodiments, a volume of the second material is smaller than a volume of the first material. 
         [0008]    In some embodiments, the first material is a metal, the recess is a counterbore defined in the first surface of the valve control plate body, the second material is a polymer material, and the valve seat insert is retained in the counterbore by a retaining ring located at an outer periphery of the valve seat insert. In accordance with an exemplary embodiment, the valve seat insert may be configured to engage a planar orifice ridge having a diameter of 4 mm or less. 
         [0009]    In some embodiments, the second material is a polymer material, the recess is a trepanned groove defined in the first surface of the valve control plate body, the valve seat insert is ring-shaped, and the first material is a metal. In some embodiments, the valve seat insert is retained in the trepanned groove by an inner retaining ring located at an inner periphery of the valve seat insert and an outer retaining ring located at an outer periphery of the valve seat insert. In other embodiments, the valve seat insert is retained in the trepanned groove by posts, columns, and/or bridges. In accordance with an exemplary embodiment, the valve seat insert may be configured to engage a planar orifice ridge having a diameter of 4 mm or greater. 
         [0010]    In some embodiments, the first material is a first metal, the recess is a counterbore defined in the first surface of the control plate body, the second material is a second metal different from the first metal, and the valve seat insert is retained in the counterbore by welding the valve seat insert to the control plate body. In accordance with an exemplary embodiment, the valve seat insert may be configured to engage a planar orifice ridge having a diameter of 4 mm or less. 
         [0011]    In some embodiments, a region of the first surface of the valve seat insert that sealingly engages the planar orifice ridge is planar. 
         [0012]    In another aspect of the present disclosure, a valve bonnet for use with a control valve body is provided. The control valve body is formed from a first material having a first hardness and has a fluid conduit opening surrounded by a planar orifice ridge. The valve bonnet comprises a bonnet body, a valve diaphragm in sealing engagement with the bonnet body at an outer periphery of the valve diaphragm, a control shaft secured to the diaphragm, the control shaft having a shank projecting from the control shaft, and a valve control plate. The valve control plate is secured to the shank and at least a portion of the valve control plate is formed from a second material having a second hardness that is less than the first hardness, the at least a portion of the valve control plate being configured to sealingly engage the planar orifice ridge. In some embodiments, the at least a portion of the valve control plate is configured to engage a planar orifice ridge that is one of circular and non-circular. In some embodiments, the valve diaphragm is formed integrally with the bonnet body and the control shaft is integrally formed with the diaphragm. In other embodiments, the diaphragm is formed separately from the bonnet body and is welded to the bonnet body. 
         [0013]    In some embodiments, the valve control plate further includes a valve control plate body having a trepanned groove defined in the valve control plate body, and the at least a portion of the valve control plate is a valve seat insert that fills the trepanned groove. In some embodiments, the valve seat insert is molded into the trepanned groove, and in some embodiments, the valve seat insert is retained in the trepanned groove by posts, columns, and/or bridges. 
         [0014]    In another aspect of the present disclosure, a control valve is provided. The control valve comprises a valve body, a bonnet body secured to the valve body, a valve diaphragm, a control shaft, and a valve control plate. The valve body has a fluid inlet conduit terminating at a first fluid conduit opening, a fluid outlet conduit commencing at a second fluid conduit opening, and an orifice ridge formed from a first material having a first hardness and surrounding the first fluid conduit opening. The valve diaphragm is in sealing engagement with the bonnet body at an outer periphery of the valve diaphragm. The control shaft is secured to the diaphragm, and a shank projects from the control shaft. The valve control plate is secured to the shank and at least a portion of the valve control plate is formed from a second material having a second hardness that is less than the first hardness, the at least a portion of the valve control plate being configured to sealingly engage the orifice ridge. 
         [0015]    In some embodiments, the orifice ridge is circular or non-circular. 
         [0016]    In some embodiments, the valve control plate includes a valve control plate body having a trepanned groove defined in the valve control plate body, and the at least a portion of the valve control plate is a valve seat insert that fills the trepanned groove. In some embodiments, the valve seat insert is molded into the trepanned groove, and in some embodiments, the valve seat insert is retained in the trepanned groove by posts, columns, and/or bridges. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0017]      FIG. 1  is a cross-sectioned perspective view of a representative valve with a control plate having a polymer material insert and a small orifice ridge of maximal span. 
           [0018]      FIG. 2  is a cross-sectioned perspective view of a representative valve with a control plate having a polymer material insert and a large orifice ridge of typical span. 
           [0019]      FIG. 3  is a cross-sectioned perspective view of a representative valve with a control plate having a soft corrosion resistant alloy insert and a small orifice ridge of maximal span. 
           [0020]      FIG. 4  is a cross-sectioned perspective view of a representative valve with a control plate having a soft corrosion resistant alloy body and a large orifice ridge of typical span. 
           [0021]      FIG. 5  is a cross-sectioned perspective view of another representative valve with an alternate design soft corrosion resistant alloy control plate. 
           [0022]      FIG. 6A  is a cross-sectioned perspective view of another representative valve with an alternate design polymer insert control plate. 
           [0023]      FIG. 6B  is an enlarged perspective section view of the control plate illustrated in  FIG. 6A  to further illustrate construction of the polymer material insert. 
           [0024]      FIG. 6C  is a view of a molded polymer insert without the metal control plate body, to further illustrate the geometry of the polymer material insert. 
           [0025]      FIG. 6D  is an enlarged perspective section view of an alternate control plate for use in the valve illustrated in  FIG. 6A  to further illustrate construction of the polymer material insert. 
           [0026]      FIG. 6E  is a view of a molded polymer insert without the metal control plate body, to further illustrate the geometry of the polymer material insert 
           [0027]      FIG. 6F  is an enlarged perspective section view of another alternate control plate for use in the valve illustrated in  FIG. 6A  to further illustrate construction of the polymer material insert. 
           [0028]      FIG. 6G  is a view of a molded polymer insert without the metal control plate body, to further illustrate the geometry of the polymer material insert. 
       
    
    
     DETAILED DESCRIPTION 
       [0029]    Embodiments of the present invention are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. Aspects of the present invention are 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. The use of directional adjectives “inner”, “outer,” “upper,” “lower,” and like terms, are meant to assist with understanding relative relationships among design elements and should not be construed as meaning an absolute direction in space nor regarded as limiting. In the following design discussions fluid flow is typically described as proceeding from a first fluid conduit, through the controlling portion of the valve, and then through a second fluid conduit. Designers will of course appreciate the discussed direction is merely a matter of descriptive convenience, fluid flow may proceed in an opposite sequence, and should not be considered as limiting. 
         [0030]    In most current high purity valve designs a diaphragm type of moveable sealing structure is the preferred approach. Using a diaphragm to contain a controlled fluid, while allowing easy motion of a moveable control element, has become standard practice. In many such valve designs the diaphragm serves as the moveable control element and valve shut-off is achieved by having the diaphragm itself press against a narrow ring of polymer material surrounding a fluid conduit opening. Designers making valves intended for proportional, or modulating, control of fluid delivery within industrial processes making semiconductor devices may find direct contacting type diaphragm valves have insufficiently gradual control curves. One type of known alternative design has a substantially flat control plate moving toward or away from a metallic lip or orifice ridge surrounding a fluid conduit opening. Complications may however arise when the diaphragm itself is not the element best suited to blocking fluid flow through the valve and shut-off sealing against a metallic structure can be problematic. 
         [0031]      FIG. 1  illustrates a representative example of a proportional control valve  100  using diaphragm sealing and also having a control plate  140  which abuts an orifice ridge  118  surrounding a centrally located fluid conduit opening  112 . The proportional control valve  100  comprises a valve body  119  having a first fluid conduit  110  and a second fluid conduit  114 , each of which communicates fluid to or from a valve chamber  150 , and a valve bonnet (bonnet body)  169  sealed to the valve body  119  by a gasket  165 , the bonnet  169  having a diaphragm  167  allowing movement of the attached control plate  140  within the valve chamber  150 . The manner of controlling fluid flow may be further understood by considering the fluid conduit opening  112 , in fluid communication with the first fluid conduit  110  and surrounded by the orifice ridge  118 , whereby at least a portion of the control plate  140  may be moved toward or away from the orifice ridge  118  to create a small clearance control gap (not shown) through which fluid may controllably flow. The controllable fluid flow may transit into the valve chamber  150  from whence it may exit through an offset fluid conduit opening  116  in fluid communication with the second fluid conduit  114 . In the present example valve  100 , an actuator (not shown) may apply a retracting force to a control shaft  182  to deflect the diaphragm  167  and thereby modulate the conductance through the valve by changing the control gap. In the present  FIG. 1  illustration the valve  100  is completely closed in a no-flow condition so there is no control gap shown. 
         [0032]    Achieving leak-free valve shut-off when the control plate  140  contacts the orifice ridge  118  may be difficult and moreover the criteria for what constitutes leak-free operation may differ among design applications. For example, not producing any gas bubbles when the valve outlet is submerged in water might be sufficient in one circumstance while having a helium gas leak rate less than 10 e-9 sccm/sec might be required for another situation. A valve design having a polymer material contact a metallic material upon closure is known to generally provide among the most leak-tight of shut-off arrangements. But polymer materials usually absorb moisture and consequently in high purity applications it is desirable to minimize the total amount of polymer material exposed to the controlled fluid. In the representative proportional control valve  100  this goal of reducing polymer content is achieved by creating a control plate  140  comprising a metallic control plate body  146  and an insert  130  of polymer material having a relatively small volume. The orifice ridge  118  may be considered as having a “maximal span” relative to the polymer insert  130  in that the orifice ridge engages the polymer insert adjacent an outer periphery of the insert. 
         [0033]    A metallic control plate body  146  of the control plate  140  can be machined as a flat disk having a central thru-hole  142  with a counterbore  144  on the side intended to face the central fluid conduit opening  112 . The counterbore  144  will enable the metallic control plate body  146  to function as a seat housing whereby a polymer seat insert  130  may be retained therein to provide a more compliant sealing material of reduced volume. In manufacturing the illustrated valve design  100  the control plate body  146  is placed onto a shank  181 , projecting from the control shaft  182  and diaphragm  167 , which passes through the central thru-hole  142 . The shank  181  and control plate body  146  may be welded together at the central thru-hole  142  interface using electron beam, laser, TIG, or any equivalent welding process. Any resulting minor weld bead excess may be machined off to match the bottom of the counterbore  144 . The polymer material insert  130  may subsequently be placed into the counterbore  144  and held in place by inserting a metallic retaining ring  132  into a space around the outer periphery of the polymer material insert  130  within the outer diameter of the counterbore  144 . The complete assembly may then undergo final finishing for flatness (by lapping, for example) as needed for good valve function. This design approach is especially advantageous for valves having an orifice ridge of about 4 mm diameter or less. 
         [0034]    The polymer material insert  130  includes a planar first surface configured to sealingly engage the planar upper end of the orifice ridge  118 . 
         [0035]      FIG. 2  illustrates a representative example of a proportional control valve  200  using diaphragm sealing and also having a control plate  240  which abuts an orifice ridge  218  surrounding a central fluid conduit opening  212 . The proportional control valve  200  comprises a valve body  219  having a first fluid conduit  210  and a second fluid conduit  214 , each of which communicates fluid to or from a valve chamber  250 , and a valve bonnet  269  sealed to the valve body  219  by a gasket  265 , the bonnet  269  having a diaphragm  267  allowing movement of the attached control plate  240  within the valve chamber  250 . The manner of controlling fluid flow may be further understood by considering the fluid conduit opening  212 , in fluid communication with the first fluid conduit  210  and surrounded by the orifice ridge  218 , whereby at least a portion of the control plate  240  may be moved toward or away from the orifice ridge  218  to create a small clearance control gap (not shown) through which fluid may controllably flow. The controllable fluid flow may transit into the valve chamber  250  from whence it may exit through an offset fluid conduit opening  216  in fluid communication with the second fluid conduit  214 . In the present example valve  200 , an actuator (not shown) may apply a retracting force to a control shaft  282  to deflect the diaphragm  267  and thereby modulate the conductance through the valve by changing the control gap. In the present  FIG. 2  illustration the valve  200  is completely closed in a no-flow condition so there is no control gap shown. 
         [0036]    In the representative proportional control valve  200  the goal of reducing polymer content is achieved by creating a control plate  240  comprising a metallic control plate body  246  and a ring-shaped insert  230  of polymer material having a relatively small volume. The orifice ridge  218  may be considered as having a “typical span” relative to the ring-shaped insert  230  in that the orifice ridge engages the insert adjacent a more central region of the insert  230  located between an inner periphery and an outer periphery of the insert. It should be appreciated that  FIG. 2  is not drawn to scale, and that the volume of the polymer can be less than that illustrated in at least some embodiments. The metallic control plate body  246  of the control plate  240  can be machined as a flat disk having a central thru-hole  242  and a trepanned (i.e., ring-shaped) groove  245  on the side intended to face the central fluid conduit opening  212 . The trepanned groove  245  will enable the metallic control plate body  246  to function as a seat housing whereby a polymer material insert  230  may be retained therein to provide a more compliant sealing material of reduced volume. In manufacturing the illustrated valve design  200  the ring-shaped polymer material insert  230  may be placed into the trepanned groove  245  and held in place by inserting a metallic inner retaining ring  234  into a space around the inner diameter of the trepanned groove  245  within the inner diameter of the ring-shaped polymer insert  230 , and inserting a metallic outer retaining ring  236  into a space around the outer periphery of the ring-shaped polymer insert  230  within the outer diameter of the trepanned groove  245 . The control plate  240  is subsequently placed onto a shank  281 , projecting from the control shaft  282  and diaphragm  267 , which passes through the central thru-hole  242 . The shank  281  and control plate body  246  may be welded together at the central thru-hole  242  interface using electron beam, laser, TIG, or any equivalent welding process. Any resulting minor weld bead excess may be machined off the control plate  240  surface as well as any splatter on the ring-shaped polymer insert  230 . The complete assembly may then undergo final finishing for flatness (by lapping, for example) as needed for good valve function. This design approach is especially advantageous for valves having an orifice ridge maximal span greater than about 4 mm. It should be appreciated the orifice ridge maximal span may be other than a diameter in the case of a non-circular orifice ridge structure. 
         [0037]    In addition to concerns discussed above regarding moisture absorption by polymer materials, it is also known that many gases will diffuse through polymers. Although the diffusion occurs at a very low rate it may amount to detectable quantities which are considered undesirable or even problematic. Additionally, in nuclear science applications a problematic diffusion of radioactive gas may also lead to a simultaneous destruction of the polymer material. A valve having metal to metal sealing is free of these concerns but it is difficult to achieve good shut-off performance in such designs. Moreover, cold welding between very clean valve metallic components can be a potential problem. One design approach is to make the valve of two dissimilar metallic materials to avoid cold welding and also provide dissimilar hardness to enhance shut-off.  FIG. 3 ,  FIG. 4 , and  FIG. 5  illustrate embodiments of a control plate for implementing a metal to metal valve design. 
         [0038]    The polymer material insert  230  includes a planar first surface configured to sealingly engage the planar upper end of the orifice ridge  218 . 
         [0039]      FIG. 3  illustrates a representative example of a proportional control valve  300  using diaphragm sealing and also having a control plate  340  which abuts an orifice ridge  318  surrounding a central fluid conduit opening  312 . The proportional control valve  300  comprises a valve body  319  having a first fluid conduit  310  and a second fluid conduit  314 , each of which communicates fluid to or from a valve chamber  350 , and a valve bonnet  369  sealed to the valve body  319  by a gasket  365 , the bonnet  369  having a diaphragm  367  allowing movement of the attached control plate  340  within the valve chamber  350 . The manner of controlling fluid flow may be further understood by considering the fluid conduit opening  312 , in fluid communication with the first fluid conduit  310  and surrounded by the orifice ridge  318 , whereby at least a portion of the control plate  340  may be moved toward or away from the orifice ridge  318  to create a small clearance control gap (not shown) through which fluid may controllably flow. The controllable fluid flow may transit into the valve chamber  350  from whence it may exit through an offset fluid conduit opening  316  in fluid communication with the second fluid conduit  314 . In the present example valve  300 , an actuator (not shown) may apply a retracting force to a control shaft  382  to deflect the diaphragm  367  and thereby modulate the conductance through the valve by changing the control gap. In the present  FIG. 3  illustration the valve  300  is completely closed in a no-flow condition so there is no control gap shown. 
         [0040]    In the representative proportional control valve  300  enhancing shut-off performance is achieved by creating a control plate  340  comprising a metallic control plate body  346  and a metallic insert  330  of less hardness than the orifice ridge  318 . The orifice ridge  318  may be considered as having a “maximal span” relative to the metallic insert  330  in that the orifice ridge engages the metallic insert adjacent an outer periphery of the insert. The metallic control plate body  346  of the control plate  340  can be machined as a flat disk having a central thru-hole  342  with a counterbore  344  on the side intended to face the central fluid conduit opening  312 . The counterbore  344  will enable the metallic control plate body  346  to function as a seat housing whereby an annealed, or preferably fully annealed, corrosion resistant metallic alloy insert  330  may be retained therein to provide a more compliant sealing material. In manufacturing the illustrated valve design  300  the control plate body  346  is placed onto a shank  381 , projecting from the control shaft  382  and diaphragm  367 , which passes through the central thru-hole  342 . 
         [0041]    The shank  381  and control plate body  346  may be welded together at the central thru-hole  342  interface using electron beam, laser, TIG, or any equivalent welding process. Any resulting minor weld bead excess may be machined off to match the bottom of the counterbore  344 . The annealed, or fully annealed, corrosion resistant metallic alloy insert  330  may subsequently be placed into the counterbore  344  and held in place by using electron beam, laser, TIG, or any equivalent welding process around the outer periphery of the insert  330  and the inner diameter of the counterbore  344 . Alternatively, an interference fit between the outer diameter of the metallic alloy insert  330  and the inner diameter of the counterbore  344  may be considered sufficient to retain the insert  330 . The complete assembly may then undergo final finishing for flatness (by lapping, or single point diamond turning, for example) as needed for good valve function. This design approach is especially advantageous for valves having an orifice ridge of about 4 mm diameter or less. In a typical application the orifice ridge  318  will be made of one alloy while the metallic alloy seat insert  330  will be made from a different alloy. One usual choice of materials is type 316 stainless for the orifice ridge  318  and a corrosion resistant nickel alloy (such as Hastelloy® C-22® available from Haynes International) for the insert  330 . 
         [0042]    The metallic insert  330  includes a planar first surface configured to sealingly engage the planar upper end of the orifice ridge  318 . 
         [0043]      FIG. 4  illustrates a representative example of a proportional control valve  400  using diaphragm sealing and also having a control plate  440  which abuts an orifice ridge  418  surrounding a central fluid conduit opening  412 . The proportional control valve  400  comprises a valve body  419  having a first fluid conduit  410  and a second fluid conduit  414 , each of which communicates fluid to or from a valve chamber  450 , and a valve bonnet  469  sealed to the valve body  419  by a gasket  465 , the bonnet  469  having a diaphragm  467  allowing movement of the attached control plate  440  within the valve chamber  450 . The manner of controlling fluid flow may be further understood by considering the fluid conduit opening  412 , in fluid communication with the first fluid conduit  410  and surrounded by an orifice ridge  418 , whereby at least a portion of the control plate  440  may be moved toward or away from the orifice ridge  418  to create a small clearance control gap (not shown) through which fluid may controllably flow. The controllable fluid flow may transit into the valve chamber  450  from whence it may exit through an offset fluid conduit opening  416  in fluid communication with the second fluid conduit  414 . In the present example valve  400 , an actuator (not shown) may apply a retracting force to a control shaft  482  to deflect the diaphragm  467  and thereby modulate the conductance through the valve by changing the control gap. In the present  FIG. 4  illustration the valve  400  is completely closed in a no-flow condition so there is no control gap shown. 
         [0044]    In the representative proportional control valve  400  enhancing shut-off performance is achieved by creating a control plate  440  comprising a metallic control plate body  446  of less hardness than the orifice ridge  418  and a metallic cover piece  430 . The orifice ridge  418  may be considered as having a “typical span” relative to the control plate body  446  in that the orifice ridge engages the control plate body adjacent a more central region of the control plate body  446  located between an inner periphery and an outer periphery of the control plate body  446 . The metallic control plate body  446  of the control plate  440  can be machined from an annealed, or preferably fully annealed, corrosion resistant alloy as a flat disk having a central thru-hole  442  with a counterbore  444  on the side intended to face the central fluid conduit opening  412 . The counterbore  444  enables the attachment process by providing access to the moveable valve elements. In manufacturing the illustrated valve design  400  the control plate body  446  is placed onto a shank  481 , projecting from the control shaft  482  and diaphragm  467 , which passes through the central thru-hole  442 . The shank  481  and control plate body  446  may be welded together at the central thru-hole  442  interface using electron beam, laser, TIG, or any equivalent welding process. Any resulting minor weld bead excess may be machined off to match the bottom of the counterbore  444 . A suitable metallic cover piece  430  may subsequently be placed into the counterbore  444  and held in place by using electron beam, laser, TIG, or any equivalent welding process around the outer periphery of the cover piece  430  and the inner diameter of the counterbore  444 . Alternatively, an interference fit between the outer diameter of the metallic cover piece  430  and the inner diameter of the counterbore  444  may be considered sufficient to retain the cover piece  430 . The complete assembly may then undergo final finishing for flatness (by lapping, or single point diamond turning, for example) as needed for good valve function. This design approach is especially advantageous for valves having an orifice ridge maximal span greater than about 4 mm. It should be appreciated the orifice ridge maximal span may be other than a diameter in the case of a non-circular orifice ridge structure. In a typical application the orifice ridge  418  will be made of one alloy while the metallic control plate body  446  will be made from a different alloy. One usual choice of materials is type 316 stainless for the orifice ridge  418  and a corrosion resistant nickel alloy (such as Hastelloy® C-22® available from Haynes International) for the control plate body  446 . The metallic cover piece  430  may be made from the same material as either the orifice ridge  418  or the control plate  440 , or from yet another different alloy. 
         [0045]    The cover piece  430  and the control plate body  446  are provided as separate components in  FIG. 4  to allow for improved welding of the control plate  440  to the shank  481 . First, the control plate body  446  is welded to the shank  481 . Next the cover piece  430  is welded to the control plate body  446 . Then cover piece  430  and the control plate body  446  can undergo finishing for flatness (e.g. by lapping, or single point diamond turning, or another method). 
         [0046]    In some embodiments, the structure of  FIG. 4  could be provided without the cover piece  430 , because the cover piece  430  is not used to engage the orifice ridge  418 . 
         [0047]    The term cover piece, as used herein, is used to describe an insert in which the insert itself is not used to sealingly engage the orifice ridge. 
         [0048]    The control plate body  446  includes a planar first surface configured to sealingly engage the planar upper end of the orifice ridge  418 . 
         [0049]      FIG. 5  illustrates a representative example of a proportional control valve  500  using diaphragm sealing and also having a control plate  540  which abuts an orifice ridge  518  surrounding a central fluid conduit opening  512 . The proportional control valve  500  comprises a valve body  519  having a first fluid conduit  510  and a second fluid conduit  514 , each of which communicates fluid to or from a valve chamber  550 , and a valve bonnet  569  sealed to the valve body  519  by a gasket  565 , the bonnet  569  having a diaphragm  567  allowing movement of the attached control plate  540  within the valve chamber  550 . The manner of controlling fluid flow may be further understood by considering the fluid conduit opening  512 , in fluid communication with the first fluid conduit  510  and surrounded by an orifice ridge  518 , whereby at least a portion of the control plate  540  may be moved toward or away from the orifice ridge  518  to create a small clearance control gap (not shown) through which fluid may controllably flow. The controllable fluid flow may transit into the valve chamber  550  from whence it may exit through an offset fluid conduit opening  516  in fluid communication with the second fluid conduit  514 . In the present example valve  500  an actuator (not shown) may apply a retracting force to a control shaft  582  to deflect the diaphragm  567  and thereby modulate the conductance through the valve by changing the control gap. In the present  FIG. 5  illustration the valve  500  is completely closed in a no-flow condition so there is no control gap shown. 
         [0050]    The metallic control plate  540  can be machined from an annealed or preferably fully annealed corrosion resistant alloy, of less hardness than the orifice ridge, as a flat disk having a blind central counterbore  542  on the side intended to face the diaphragm  567 . In manufacturing the illustrated valve design  500  the control plate  540  may be press fit onto a shank  581 , projecting from the control shaft  582  and diaphragm  567 . Alternatively, the shank  581  and control plate  540  may be welded together using electron beam, laser, or any equivalently energetic welding process suitable to penetrate the thin central portion  530  of the control plate  540  and fuse it to the shank  581 . It should be noted that in the embodiment depicted in  FIG. 5 , the shank  581  may extend deeper into the control plate  540  than, for example, the embodiments depicted in  FIGS. 3 and 4  to aid in the welding process. The thin central portion  530  may further include a detent or other type of weld preparation (not shown) to reduce the amount of material in the central portion  530  of the control plate to minimize the amount of energy or time needed to weld the central portion  530  of the control plate  540  to the shank  581 . Any resulting minor weld bead excess may be machined off and the complete assembly may then undergo final finishing for flatness (by lapping, or single point diamond turning, for example, or another method) as needed for good valve function. This design approach is especially advantageous due to the lesser number of machined pieces and its suitability for use with a variety of orifice ridge sizes and shapes. It should be appreciated the orifice ridge maximal span may be other than a diameter in the case of a non-circular orifice ridge structure and an ensemble plurality of coplanar orifice ridges is also contemplated. In a typical application the orifice ridge  518  will be made of one alloy while the metallic control plate  540  will be made from a different alloy. One usual choice of materials is type 316 stainless for the orifice ridge  518  and a corrosion resistant nickel alloy (such as Hastelloy® C-22® available from Haynes International) for the control plate  540 . 
         [0051]    The control plate  540  includes a planar first surface configured to sealingly engage the planar upper end of the orifice ridge  518   
         [0052]      FIG. 6A  and  FIG. 6B  illustrate a representative example of a proportional control valve  600  using diaphragm sealing and also having a control plate  640  which abuts an orifice ridge  618  surrounding an inner fluid conduit opening  612 . The proportional control valve  600  comprises a valve body  619  having a first fluid conduit  610  and a second fluid conduit  614 , each of which communicates fluid to or from a valve chamber  650 , and a valve bonnet  669  sealed to the valve body  619  by a gasket  665 , the bonnet  669  having a diaphragm  667  allowing movement of the attached control plate  640  within the valve chamber  650 . The manner of controlling fluid flow may be further understood by considering the inner fluid conduit opening  612 , in fluid communication with the first fluid conduit  610  and surrounded by the orifice ridge  618 , whereby at least a portion of the control plate  640  may be moved toward or away from the orifice ridge  618  to create a small clearance control gap (not shown) through which fluid may controllably flow. The controllable fluid flow may transit into the valve chamber  650  from whence it may exit through an outer fluid conduit opening  616  in fluid communication with the second fluid conduit  614 . In the present example valve  600 , an actuator (not shown) may apply a retracting force to a control shaft  682  to deflect the diaphragm  667  and thereby modulate the conductance through the valve by changing the control gap. In the present  FIG. 6A  illustration the valve  600  is completely closed in a no-flow condition so there is no control gap shown. 
         [0053]    In the representative proportional control valve  600  the goal of reducing polymer content is achieved by creating a control plate  640  comprising a metallic control plate body  646  and a molded insert  630  of polymer material. As may be seen in  FIG. 6B , the metallic control plate body  646  of the control plate  640  can be machined as a flat disk having a central thru-hole  642  and a plurality of concentric ring-shaped grooves  648  on the side intended to face the inner fluid conduit opening  612 . The grooves  648  enable the metallic control plate body  646  to function as a seat housing whereby a polymer material insert  630  may be retained therein, as will be further explained, to provide a more compliant sealing material of reduced volume. The remaining metal  649  between the concentric grooves  648  in the control plate body  646  provides meaningful reduction of the total volume of the molded insert  630 . Vent holes  644 , defined in the flat back side of the disk facing away from the inner fluid opening  612 , are made centered between the grooves  648  deep enough with sufficient diameter to intersect the bottoms of adjacent grooves  648  while leaving the majority of the remaining metal  649  intact. In manufacturing the illustrated control plate  640  the polymer material insert  630  may be formed by compression molding (e.g. starting with polychlorotrifluoroethene (PCTFE) powder and polymerizing under the effect of heat and pressure) directly into the control plate body  646  by known methods. During the molding process bridges  634  of polymer material will surround parts of the remaining metal  649  and fill the vent holes  644 . The polymer material bridges  634  surrounding the remaining metal  649  thus lock the molded polymer insert  630  into the metallic control plate body  646 .  FIG. 6C  shows a perspective view of a molded polymer insert  630 , with the metallic control plate body  646  not shown for the purpose of illustrating the geometry of the molded polymer insert  630 . The molded polymer insert  630  has a plurality of annular ridges  638 , that are complementary with the grooves  648  and which fill the grooves  648  that are defined in the control plate body  646 . 
         [0054]    The control plate  640  comprising the metallic control plate body  646  including the molded polymer insert  630  may be attached to a shank  681 , projecting from the control shaft  682  and diaphragm  667 , by press fit into the central thru-hole  642 . Alternatively, prior to the above described molding, the control plate body  646  may first be placed onto the shank  681  and welded together at the central thru-hole  642  interface using electron beam, laser, TIG, or any equivalent welding process. Any resulting minor weld bead excess may be machined off the control plate body  646  surface before molding the insert  630  into the control plate body  646 . The process sequence choice will depend upon practitioners&#39; preference in compression molding techniques. The complete assembly may then undergo final finishing for flatness (by lapping, for example) as needed for good valve function. This design approach is especially advantageous for use with valve bodies having a variety of orifice ridge sizes and shapes. It should be appreciated the orifice ridge maximal span may be other than a diameter in the case of a non-circular orifice ridge structure. Careful examination of the illustrated example of  FIG. 6A  will reveal the orifice ridge  618  is circular but placed off geometric center of the diaphragm  667  and control plate  640  to accommodate a correspondingly large non-circular outer fluid opening  617  because the orifice ridge is so large in diameter. 
         [0055]    An alternate control plate  660  suitable for use in the representative proportional control valve  600  is illustrated in  FIG. 6D . A metallic control plate body  676  of the control plate  660  can be machined as a flat disk having a central thru-hole  672  and a wide shallow ring-shaped groove  675  on the side intended to face the inner fluid conduit opening  612 . The groove  675  enables the metallic control plate body  676  to function as a seat housing whereby a polymer material insert  670  may be retained therein, as will be further explained, to provide a more compliant sealing material of reduced volume. A plurality of thru-holes  674  defined in the flat back side of the disk facing away from the inner fluid opening  612  penetrate the wide shallow ring-shaped groove  675 . In manufacturing the illustrated control plate  660  the polymer material insert  670  may be formed by compression molding (e.g. starting with PCTFE powder and polymerizing under the effect of heat and pressure) directly into the control plate body  676  by known methods. During the molding process a plurality of columns  673  of polymer material will fill the thru-holes  674  thereby frictionally locking the polymer material into the groove  675  defined in the metallic control plate body  676 . The geometry of the polymer material insert  670  that is formed by the molding process is shown in  FIG. 6E , with the control plate body  676  not shown for illustration purposes. The control plate  660  comprising the metallic control plate body  676  including the molded polymer insert  670  may be attached to a shank  681 , projecting from the control shaft  682  and diaphragm  667 , by press fit into the central thru-hole  672 , or attached in another manner as previously described. 
         [0056]    Another alternate control plate  680  suitable for use in the representative proportional control valve  600  is illustrated in  FIG. 6F . A metallic control plate body  696  of the control plate  680  can be machined as a flat disk having a central thru-hole  692 , a wide shallow counterbore  695 , and a plurality of wedge-shaped (being approximately circular sectors) cavities  697 , 698  cut into the bottom of the counterbore  695  on the side intended to face the inner fluid conduit opening  612 . The counterbore  695  and plurality of cavities  697 , 698  enable the metallic control plate body  696  to function as a seat housing whereby a polymer material insert  690  may be retained therein, as will be further explained, to provide a more compliant sealing material of reduced volume. The metal between the between the plurality of wedge-shaped cavities  697 , 698 , in the wide shallow counterbore  695  of the control plate body  696 , form radial ribs  699 . Vent holes  691 , defined in the flat back side of the disk facing away from the inner fluid opening  612 , are made centered over the radial ribs  699  deep enough with sufficient diameter to intersect the bottoms of adjacent wedge-shaped cavities  697 , 698  while leaving the majority of the remaining metal rib  699  intact. A plurality of thru-holes  694 , also defined in the flat back side of the disk facing away from the inner fluid opening  612 , penetrate the bottom of each of the wedge-shaped cavities  697 , 698 . In manufacturing the illustrated valve design  600  the polymer material insert  690  may be formed by compression molding (e.g. starting with PCTFE powder and polymerizing under the effect of heat and pressure) directly into the control plate body  696  by known methods. During the molding process polymer material will fill the thru-holes  694  and surround the metal radial ribs  699  to fill the vent holes  691 . The molded polymer material forms bridges  689  to fill the vent holes and posts  693  to fill the thru-holes  694 . The molded polymer material also forms wedge portions of the insert  690  to fill respective wedge-shaped cavities  697 ,  698 . The polymer material surrounding the metal ribs  699  thus lock the molded insert  690  into the metallic control plate body  696 . The geometry of the polymer material insert  690  that is formed by the molding process is shown in  FIG. 6G , with the control plate body  696  not shown for illustration purposes. The control plate  680  comprising the metallic control plate body  696  including the molded polymer insert  690  may be attached to a shank  681 , projecting from the control shaft  682  and diaphragm  670 , by press fit into the central thru-hole  692 , or attached in another manner as previously described. 
         [0057]    In each of  FIGS. 6A-6G , the respective polymer material insert  630 ,  670 ,  690  includes a planar first surface configured to sealingly engage the planar upper end of the orifice ridge  618 . 
         [0058]    It should be appreciated that the specific sizes of features shown in  FIGS. 6A-6G  may be varied and are not necessarily drawn to scale. 
         [0059]    Referring again to  FIG. 2 , the ring-shaped insert  230  could be molded in the control plate body  246  of the control plate  240  and secured within the control plate body  246  of the control plate  240  by retaining features such as the structure of  FIGS. 6A-6G . That is, for example, the ring-shaped insert  230  could have columns that are positioned in thru-holes defined in the control plate body  246 , posts that are positioned in thru-holes defined in the control plate body  246 , and/or bridges that are positioned in vent holes defined in the control plate body in a manner similar to that described with respect to  FIGS. 6A-6G . 
         [0060]    The counterbores and grooves described above are examples of recesses that can be defined in a control plate body. In some embodiments, an insert can be secured in another type of recess that is defined in the control plate body. 
         [0061]    In some embodiments, a retention mechanism is used to retain an insert in one or more counterbores and/or one or more grooves defined in a control plate body. Some examples of a retention mechanism include a retaining ring located at an outer periphery of the insert, an inner retaining ring located at an inner periphery of the insert and an outer retaining ring located at an outer periphery of the insert, a post, a column, a bridge, and a weld. Other retention mechanisms are possible. It should be appreciated that although embodiments of the present disclosure have been primarily described with respect to diaphragm sealed valves in which a control plate is disposed below and attached to or integrally formed with the diaphragm, aspects of the present disclosure may be readily adapted for use with other types of valves, such as bellows sealed valves similar to those described in U.S. Pat. No. 3,295,191. Moreover, although embodiments of the present disclosure have been described with respect to control valves in which an actuator is used to move an orifice ridge sealing surface of the control plate toward and away from an orifice ridge, this movement need not need not be uniform across the orifice ridge sealing surface of the control plate. For example, embodiments of the present disclosure may readily be used with a valve stroke amplification mechanism, such as disclosed in US Patent Publication No. US2016/0138730 A1, in which an amplifier disc may be used to effect a wedge shaped gap having a higher conductance than would otherwise be obtained. 
         [0062]    Although the embodiments depicted in  FIGS. 1-6A  are all depicted as showing a valve bonnet body  169 ,  269 ,  369 ,  469 ,  569 ,  669  in which the diaphragm  167 ,  267 ,  367 ,  467 ,  567 ,  667  is integrally formed with the bonnet body, it should be appreciated that the present invention is not so limited. Indeed, embodiments of the present disclosure encompass diaphragms that are stamped, punched, or cut out of a piece of sheet metal that is later attached (for example, by welding) to a bonnet body, as well as those in which the diaphragm and bonnet body are integrally formed from a single block of starting material, as shown herein. 
         [0063]    Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated 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.