Abstract:
A control valve for operating a fluid-actuated device includes a fluid inlet, a fluid outlet and a passage in fluid communication between the fluid inlet and the fluid outlet, the passage defining a longitudinal axis. A valve seat is disposed in the passage and includes an upstream diameter and a downstream diameter, the downstream diameter smaller than the upstream diameter. A ball poppet is positionable in a seated line contact position with the valve seat. The valve seat has a valve seat angle relative to a centerline of the longitudinal axis that is greater than an angle formed by the centerline and a line tangent to the ball poppet at the seated line contact position.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 09/671,841 filed on Sep. 27, 2000, which is a continuation-in-part of U.S. patent application Ser. No. 09/527,395, filed Mar. 16, 2000. The disclosures of the above applications are incorporated herein by reference. 
     
    
     
       BACKGROUND AND SUMMARY OF THE INVENTION  
         [0002]    The invention relates generally to fluid control valves for operating a fluid-actuating device and, more particularly, to fluid control valves employing one or more ball-poppets.  
           [0003]    Fluid control valves are often used for a wide variety of high-pressure applications, such as blow-molding plastic bottles or other such containers. Although these control valves have generally functioned satisfactorily, they often have a short life span due to excessive wear caused by exposure to high fluid pressures and may also experience internal fluid leakage. These internal fluid leaks, such as cross-over leaks, may occur while opening the inlet port of the valve and simultaneously closing the exhaust port of the valve in order to drive the fluid-actuating device. As a result, these factors have contributed to the high operation costs and high maintenance costs of prior art systems.  
           [0004]    Moreover, in many commercial applications it is preferable that the control valve be capable of outputting multiple pressures. For example, with regard to blow-molding plastic bottles, it is often desirable to initially introduce a relatively low pressure to the mold in order to introduce the plastic (or other material) into the mold cavity or cavities and then to introduce a relatively high pressure to force or expand the material to conform to the mold cavity.  
           [0005]    Accordingly, there exists a need in the relevant art to provide a high-pressure or multi-pressure fluid control valve that is capable of minimizing the wear and internal fluid leakage thereof so as to maximize the useful life of the valve and minimize the associated operating and maintenance costs. Furthermore, there exists a need in the relevant art to provide a fluid control valve that is capable of selectively outputting multiple pressures to the fluid-actuating device.  
           [0006]    In accordance with the broad teachings of the present invention, a primary control valve for operating a fluid-actuated device includes a fluid inlet, a fluid outlet and a passage in fluid communication between the fluid inlet and the fluid outlet, the passage defining a longitudinal axis. A valve seat is disposed in the passage and includes an upstream diameter and a downstream diameter. The downstream diameter is smaller than the upstream diameter. A ball poppet is positionable in a seated line contact position with the valve seat. The valve seat has a valve seat angle relative to a centerline of the longitudinal axis that is greater than an angle formed by the centerline and a line tangent to the ball poppet at the seated line contact position.  
           [0007]    Each side of the preferred frusto-conical supply valve seat has a supply seat angle relative to the centerline of the supply valve seat that is greater than an angle formed by the centerline of the supply valve seat and a line tangent to the supply ball-poppet at the above-mentioned substantially line-contact when the supply ball-poppet is in its closed position. The included angular relationship of the valve seat angles on both sides of the centerline is preferably approximately ninety degrees. This results in a annular space being formed between the supply valve seat and the spherical supply ball-poppet, which defines a restricted supply flow area upstream of the above-mentioned substantially line-contact as the supply ball-poppet initially moves to its open position and as high-velocity and high-pressure working fluid initially flows downstream past the supply ball-poppet through the smaller-diameter end of the valve seat. This is greatly advantageous because any sonic flow erosion caused by the initial flow of the high velocity and high-pressure working fluid through the annular restricted supply flow area is thus shifted substantially immediately to an upstream surface of the supply valve seat that is adjacent to such annular restricted supply flow area. Most significantly, such upstream surface of the supply valve seat is an area that is not sealingly contacted by the supply ball-poppet. Therefore, this immediate shifting of the sonic damage-susceptible area substantially minimizes sonic erosion of the nearly “knife-edge” smaller-diameter downstream end of the supply valve seat that is substantially line-contacted by the supply ball-poppet. In control valves according to the present invention that have both supply valving and exhaust valving, a similar arrangement is preferably provided in the exhaust passage way in fluid communication for exhaust fluid between the load outlet passage (and load outlet) and the exhaust outlet. As mentioned above, this arrangement is equally applicable to a pressure selector fluid control valve, as described below.  
           [0008]    In addition, the present invention preferably includes a generally cylindrical cavity immediately upstream of the larger-diameter upstream ends of the supply and/or exhaust valve seats, with such cavity preferably being larger in diameter than the larger-diameter upstream end of the respective valve seats. A cylindrical poppet guide or ball-poppet guide is located in this enlarged-diameter cavity of the fluid passage, with the ball-poppet guide having a central guide bore extending axially therethrough. A number of circumferentially spaced-apart axially-extending guide fins protrude radially inwardly into the guide bore, with the ball-poppet being received within the guide bore for axial movement within radially inward edges of the guide fins between its open and closed positions. The inner diameter of the above-mentioned cavity is preferably slightly greater than the outer diameter of the ball-poppet guide in order to allow the ball-poppet guide and the ball-poppet to float radially somewhat within the cavity. This allows the generally spherical ball-poppet to be substantially self-centering for sealing line-contact with the smaller-diameter end of the respective supply or exhaust valve seat. Such circumferentially spaced guide fins allow high pressure working fluid to flow therebetween, and the ball-poppet guide substantially minimizes wear on the ball-poppet and/or the valve seat that would result if it were to be allowed to rattle or otherwise move radially in the high-velocity fluid flow. Such a ball-poppet guide can also be used in a selector fluid control valve, as described below.  
           [0009]    The present invention substantially also negates cross-over leakage in high-pressure fluid control valves having both supply and exhaust valving by energizing the exhaust ball-poppet actuator, thus closing the exhaust side of the control valve, just prior to energizing the supply ball-poppet actuator, which then opens the supply side and initiates supply flow to the load passage and port.  
           [0010]    The above-mentioned ball-poppets (for either primary or selector fluid control valves) are preferably composed of a metallic material, such as a stainless steel, for example, and the above-mentioned ball-poppet guides are preferably composed of a synthetic material, such as nylon, for example. Those skilled in the art will readily recognize that other metallic, synthetic, or non-synthetic materials can also be employed for the ball poppets and/or the ball-poppet guides, depending upon the particular working fluid (pneumatic or liquid) being employed, as well as the particular working fluid pressures involved, as well as depending upon the particular application in which the fluid control valve of the present invention is employed.  
           [0011]    The present invention also provides a pressure selector fluid control valve for selectively supplying at least two different working fluid pressures to a fluid-actuated device, either directly or by way of a primary fluid control valve, such as that discussed above. An exemplary selector fluid control valve according to the present invention preferably has a high-pressure inlet in fluid communication with a source of working fluid at a relatively high pressure, a low-pressure inlet in fluid communication with a source of working fluid at a relatively low pressure, and a load fluid outlet passage interconnected in fluid communication with the fluid-actuated device or primary fluid control valve inlet. Such a selector fluid control valve further includes a normally closed high-pressure valve mechanism in fluid communication between the high-pressure inlet and the load fluid outlet passage to selectively allow high-pressure fluid flow from the high-pressure inlet to the load fluid outlet passage, as well as a normally open low-pressure valve mechanism in fluid communication between the low-pressure inlet and the load fluid outlet passage to selectively allow low-pressure fluid flow from the low-pressure inlet to the load fluid outlet passage. A pilot actuator is provided and is selectively operable to force the normally closed high-pressure valve mechanism into an open position and allow said high-pressure fluid flow from the high-pressure inlet to the load fluid outlet passage. This high-pressure fluid being admitted into the load fluid outlet passage forces the normally open low-pressure valve mechanism into a closed position to prevent fluid flow between the low-pressure inlet and the load fluid outlet passage. Thus the selective actuation or energization of the pilot actuator, either the high-pressure or low-pressure working fluid (such as a pneumatic working fluid, for example) can be admitted to the inlet of a fluid-actuated device or the inlet of a primary fluid control valve, such as that described above or of virtually any type.  
           [0012]    At least one or preferably both of the above-discussed high-pressure and low-pressure valve mechanisms can include a generally frusto-conical valve seat located in a valve fluid passage in fluid communication with the load fluid outlet passage, with the valve seat having a smaller-diameter downstream end and a larger-diameter upstream end. A generally spherical ball-poppet is selectively movable between respective closed and open positions into and out of substantially ball-poppet line-contact for sealing with said smaller-diameter end of the supply valve seat. The generally spherical ball-poppet preferably has a chord dimension at said line-contact with the smaller-diameter downstream end of the valve seat that is smaller than the larger-diameter upstream end of the valve seat. The generally frusto-conical valve seat preferably has a seat angle relative to the centerline of the supply valve seat that is greater than an angle formed by the centerline of the valve seat and a line tangent to the spherical ball-poppet at the ball-poppet line-contact when the ball-poppet is in said closed position, with such seat angle preferably being approximately forty-five degrees such that the overall seat angle between diametrically opposite portions of the valve seat is approximately ninety degrees. An annular space formed between the valve seat and the spherical ball-poppet thus defines a restricted flow area upstream of the ball-poppet line-contact between the spherical ball-poppet and the smaller-diameter downstream end of the valve seat as the spherical ball-poppet initially moves out of said line-contact to its open position and as the working fluid initially flows downstream past the ball-poppet through the smaller-diameter end of said valve seat. By such an arrangement, any sonic flow erosion caused by the initial working fluid flow past the opening ball-poppet is shifted substantially immediately to an upstream area of the valve seat that is adjacent the restricted flow area and that is not sealingly contacted by the spherical ball-poppet. This substantially minimizes sonic damage to the smaller-diameter downstream end of said valve seat against which the ball-poppet is sealingly engaged when in its closed position. This greatly increases the life of the control valve by minimizing the wear on the sealing portion of the valve seat.  
           [0013]    One or both of the fluid valve passages can include a generally cylindrical cavity immediately upstream of the larger-diameter upstream end of the valve seat, the cavity being larger in diameter than the larger-diameter upstream end. The valve mechanism preferably includes a generally cylindrical ball-poppet guide located in the cavity of said fluid passage, with the ball-poppet guide having a central guide bore extending axially therethrough. The ball-poppet guide preferably has a number of circumferentially spaced-apart axially-extending guide fins protruding radially inwardly into the guide bore, with the ball-poppet being received within the guide bore for axial movement within radially inward edges of the guide fins between its open and closed positions. The inner diameter of the cavity is greater than the outer diameter of the ball-poppet guide in order to allow the ball-poppet guide to float radially within the cavity and to allow the spherical ball-poppet to be substantially self-centering for sealing line-contact with the smaller-diameter end of said frusto-conical valve seat.  
           [0014]    An exemplary selector fluid control valve according to the present invention may alternatively include a high-pressure inlet in fluid communication with a source of working fluid at a relatively high pressure, a low-pressure inlet in fluid communication with a source of working fluid at a relatively low pressure, and a load fluid outlet passage interconnected in fluid communication with the fluid-actuated device or primary fluid control valve inlet having a selectively adjustable control stem. The control stem selectively adjusts to a plurality of positions including a closed position, a fully open position and a plurality of intermediate positions therebetween for limiting the flow of working fluid through the low pressure inlet.  
           [0015]    In any of the primary or pressure selector fluid control valves according to the present invention, the frusto-conical valve seat can alternatively be located in a replaceable valve seat disc that is of a harder material than that of the valve body.  
           [0016]    Additional objects, advantages, and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.  
           [0017]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0019]    [0019]FIG. 1 is a cross-sectional illustration of an exemplary fluid control valve according to the present invention.  
         [0020]    [0020]FIG. 2 is an end view of the fluid control valve of FIG. 1;  
         [0021]    [0021]FIG. 3 is a top view of the fluid control valve of FIGS. 1 and 2, with the top cover or cap removed;  
         [0022]    [0022]FIG. 4 is a top view of a ball-poppet guide for use with either or both of a supply ball-poppet and an exhaust ball-poppet of the control valve of FIG. 1;  
         [0023]    [0023]FIG. 5 is a side view of the poppet guide of FIG. 4;  
         [0024]    [0024]FIG. 6 is an enlarged detail view of the supply valving portion of the control valve of FIG. 1, with the supply ball-poppet shown in its closed position;  
         [0025]    [0025]FIG. 7 is an enlarged detailed view similar to that of FIG. 6, but illustrating the supply ball-poppet in its initially opening condition;  
         [0026]    [0026]FIG. 8 is an enlarged detail view of the exhaust valving portion of the control valve of FIG. 1, with the exhaust ball-poppet shown in its closed position;  
         [0027]    [0027]FIG. 9 is an enlarged detail view similar to that of FIG. 8, but illustrating the exhaust ball-poppet in its initially opening condition;  
         [0028]    [0028]FIG. 10 is a cross-sectional illustration of an exemplary dual-pressure selector fluid control valve according to the present invention;  
         [0029]    [0029]FIG. 10 a  is a cross-sectional view taken generally along line  10   a - 10   a  of FIG. 10;  
         [0030]    [0030]FIG. 11 is a top view of the exemplary dual-pressure selector fluid control valve of FIG. 10, operatively interconnected with a primary fluid control valve, such as is illustrated in FIGS. 1 through 9, both of which being mounted on a fluid manifold;  
         [0031]    [0031]FIG. 12 is a front view of the fluid control valve arrangement of FIG. 11;  
         [0032]    [0032]FIG. 13 is an end view of the fluid control valve arrangement of FIGS. 11 and 12;  
         [0033]    [0033]FIG. 14 is a cross-sectional illustration of an exemplary pressure selector fluid control valve similar to that of FIG. 10, but showing an alternate tri-pressure version of the selector fluid control valve;  
         [0034]    [0034]FIG. 15 is an enlarged detailed view of an alternate version of the ball-poppet portion of a control valve according to the invention, having a replaceable valve seat disc and which is applicable to any of the fluid control valves of FIGS. 1 through 14; and  
         [0035]    [0035]FIG. 16 is a cross-sectional illustration of an exemplary dual-pressure selector fluid control valve including an adjustable control stem according to the present invention.  
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0037]    Referring to FIG. 1, an exemplary primary fluid control valve  10  is shown having a body  12 , a pilot cap  14 , and a manifold  16 . Body  12  and pilot cap  14  are secured to manifold  16  by way of a number of bolts  18 . However, it should be understood that body  12  and pilot cap  14  may be coupled together by way of fluid piping, without the use of the manifold  16 , if threaded ports are alternately provided.  
         [0038]    The exemplary primary control valve  10  includes an inlet port  20 , an outlet or load port  22 , and an exhaust port  24 . A working fluid supply passage  28  provides working fluid communication from the inlet port  20  to the outlet port  22 , which is connected, such as by way of the manifold  16 , to a fluid-actuated device. Similarly, an exhaust passage  30  provides exhaust fluid communication between the load port  22  and the exhaust outlet  24 .  
         [0039]    In the exemplary primary control valve  10 , the supply and exhaust passages  28  and  30  respectively include a frusto-conical supply valve seat  36  and a frusto-conical exhaust valve seat  46 . The supply valve seat  36  includes a smaller-diameter end  38  and a larger-diameter end  40 . Similarly the exhaust valve seat  46  includes a smaller-diameter end  48  and a larger-diameter end  50 . A generally spherical supply ball-poppet  42  and a similar generally spherical exhaust ball-poppet  52  are provided for opening and closing movement with respect to their respective frusto-conical supply and exhaust valve seats  36  and  46 .  
         [0040]    The supply ball-poppet  42  is preferably movably actuated by way of a supply pilot actuator  80 , which receives pilot air from a pilot air passage  97 , which is in turn connected in fluid communication with a pilot air inlet  96 . When the supply pilot actuator  80  is energized, the force of the pilot air is transmitted on to the supply piston  81  and in turn to supply push rod  82  to urge the supply ball-poppet  42  away from the supply valve seat  36 , thus opening the supply valving portion of the control valve  10 . When the supply pilot actuator  80  is deenergized, the ball-poppet  42  is returned to its closed position under the influence of the inlet fluid pressure and a return spring  58 .  
         [0041]    Similarly, the exhaust ball-poppet  52  is urged into its closed position with respect to the exhaust valve seat  46  by way of the energization of an exhaust pilot actuator  90 . In this regard, pilot actuator  90  acts to exert the force of pilot air on to an exhaust piston  91  and in turn to exhaust push rod  98  in drawing (FIG. 1), to the exhaust ball-poppet  52 . Upon deenergization of the exhaust pilot actuator  90 , the exhaust ball-poppet  52  is urged back to its open position under the influence of high-pressure working fluid in the exhaust passage  30 .  
         [0042]    One skilled in the art will readily recognize that actuators other than the exemplary electro-pneumatic supply pilot actuator  80  and electro-pneumatic exhaust pilot actuator  90 , can alternatively be employed. Such actuating devices could include for example, electromechanical solenoids, either local or remote, mechanical motion transmitting devices, or a wide variety of other actuating devices well-known to those skilled in the art.  
         [0043]    Referring primarily to FIGS. 6 and 7, the exemplary high-pressure fluid control valve  10  depicted in the drawings also preferably includes a generally cylindrical supply cavity  60  immediately upstream of the larger-diameter upstream end  40  of the supply valve seat  36 . As illustrated in FIGS. 4 through 6, a generally cylindrical supply poppet guide  62  is provided upstream within the preferred diametrically-enlarged cylindrical supply cavity  60 . The supply poppet guide  62  includes a generally cylindrical central supply guide bore  64  extending axially therethrough, with a number of circumferentially spaced-apart and axially-extending supply guide fins  66  protruding radially inwardly into the supply guide bore  64 . The supply ball-poppet  42  is received within the supply guide bore  64  for axial movement within the radially inward edges of the supply guide fins  66  between its open and closed positions with respect to the supply valve seat  36 . As is perhaps best illustrated in FIGS. 6 and 7, the inner diameter of the supply cavity  60  is slightly greater than the outer diameter of the supply ball-poppet guide  62 , thus allowing the poppet guide  62  and the ball-poppet  42  to float radially within the supply cavity  60 . As such the generally spherical supply ball-poppet  42  is self-centering for sealing substantially line-contact  44  with the smaller-diameter end  38  of the supply valve seat  36 .  
         [0044]    In addition, the supply guide fins  66  preferably extend axially downstream to form a supply guide fin extension portion  63  on one end of the supply poppet guide  62 . A resilient ring  61 , such as an O-ring, surrounds the extension portion  63  in order to resiliently urge the poppet guide  62  toward the opposite, upstream end of the supply cavity  60 . This action results from compression of the resilient ring  61  between the floor of the supply cavity  60  and the remainder of the supply ball-poppet guide  62 .  
         [0045]    It should be noted that the above arrangement, as depicted in FIGS. 4 through 7, is substantially typical with respect to the frusto-conical exhaust valve seat  46 . Explained further, the smaller-diameter upstream end  48  is arranged to engage in substantial line-contact the generally spherical exhaust poppet  52 , all of which are shown in FIG. 1. The supply poppet guide  62  depicted in FIGS. 4 and 5 is also substantially typical for the exhaust poppet guide  72 , which is received within the diametrically-enlarged generally cylindrical exhaust cavity  70  and has a similar central exhaust guide bore  74  and similar exhaust guide fins  76 , and which can also be seen in FIGS. 1, 8 and  9 .  
         [0046]    Referring in particular to FIGS. 6 and 7, an enlarged detail view of the supply valving portion of the exemplary control valve  10  is shown. The ball-poppet  42  is shown in its closed position in FIG. 6. Wherein the ball-poppet  42  is sealingly engaged in substantial line-contact  44  with the edge of the smaller-diameter end  38  of the supply valve seat  36 . Similarly, the ball-poppet  42  is shown partially opened and thus moved out of such substantial line-contact  44  in FIG. 7. The frusto-conical supply valve seat  36  preferably has a valve seat angle  37  (with respect to the centerline  57  of the valve seat  36 ) that is slightly larger than the tangent angle  59  of the tangent line  56  to the ball-poppet  42  (with respect to the centerline  57 ) when the ball-poppet  42  is in substantial line-contact  44  shown in FIG. 6.  
         [0047]    This valve seat arrangement results in an annular space  43  that creates a restricted supply flow area just upstream of the supply line-contact  44  and the smaller-diameter end  38 . The restricted flow area is created as the supply ball-poppet  42  initially moves out of such line-contact  44  to its open position shown in FIG. 7 as working fluid flows downstream past the ball-poppet  42  through the smaller-diameter end  38  of the supply valve seat  36 . Consequently, any sonic flow erosion damage caused by such initial flow of high-pressure working fluid is shifted substantially immediately to an upstream area  45  of the supply valve seat  36 . This is highly advantageous in that it shifts such wear or damage caused by such sonic flow erosion to an area of the supply valve seat  36  that is adjacent to the annular space  43  rather than in contact with ball-poppet  42 . Accordingly, the sonic damage to the smaller-diameter downstream sealing end  38  of the supply valve seat  36  is minimized, As a result, the damage to and wear of the actual sealing surface of the valve seat  36  on the ball-poppet  42  is likewise substantially minimized and the functional life of the exemplary control valve  10  is correspondingly greatly extended. In this regard, the downtime and the maintenance costs are reduced for a system employing a control valve  10  according to the present invention.  
         [0048]    As will be readily recognized by one skilled in the art, the above-described function of the ball-poppet  42  with respect to the supply valve seat  36  as shown in FIG. 6 and FIG. 7 is similar to that of the function and relationship of the exhaust ball-poppet  52  and exhaust valve seat  46 .  
         [0049]    Referring primarily to FIGS. 8 and 9, the exemplary high-pressure fluid control valve  10  depicted in the drawings also preferably includes a generally cylindrical exhaust cavity  70  immediately downstream of the larger-diameter downstream end  50  of the exhaust valve seat  46 . A generally cylindrical exhaust poppet guide  72  (similar to that of the supply poppet guide  62  of FIGS. 5 and 6) is provided downstream within the preferred diametrically-enlarged cylindrical exhaust cavity  70 . The exhaust poppet guide  72  includes a generally cylindrical central exhaust guide bore  74  extending axially therethrough, with a number of circumferentially spaced-apart and axially-extending exhaust guide fins  76  protruding radially inwardly into the exhaust guide bore  74 . The exhaust ball-poppet  52  is received within the exhaust guide bore  74  for axial movement within the radially inward edges of the exhaust guide fins  76  between its open and closed positions with respect to the exhaust valve seat  46 . The inner diameter of the exhaust cavity  70  is slightly greater than the outer diameter of the exhaust ball-poppet guide  72 , thus allowing the poppet guide  72  and the exhaust ball-poppet  52  to float radially within the exhaust cavity  70 . As a result, the generally spherical exhaust ball-poppet  52  is self-centering for sealing substantially line-contact  54  with the smaller-diameter end  48  of the exhaust valve seat  46 .  
         [0050]    The exhaust guide fins  76  preferably extend axially upstream to form an exhaust guide fin extension portion  73  on the exhaust poppet guide  72 . A resilient ring  71 , such as an O-ring, surrounds the extension portion  73  in order to urge the poppet guide  72  toward the opposite, downstream end of the exhaust cavity  70 . This action results from compression of the resilient ring  71  between the floor of the exhaust cavity  70  and the remainder of the exhaust ball-poppet guide  72 .  
         [0051]    Referring in particular to FIGS. 8 and 9, an enlarged detail view of the exhaust valving portion of the exemplary control valve  10  is shown. The exhaust ball-poppet  52  is shown in its closed position in FIG. 8 wherein the ball-poppet  52  is sealingly engaged in substantial line-contact  54  with the edge of the smaller-diameter end  48  of the exhaust valve seat  46 . Similarly, the ball-poppet  52  is shown partially opened and thus moved out of such substantial line-contact  54  in FIG. 9. The frusto-conical exhaust valve seat  46  preferably has an exhaust valve seat angle  47  (with respect to the exhaust centerline  67  of the valve seat  46 ) that is slightly larger than the exhaust tangent angle  69  of the exhaust tangent line  65  to the exhaust ball-poppet  52  (with respect to the centerline  67 ) when the ball-poppet  52  is in substantial line-contact  54  shown in FIG. 8.  
         [0052]    This valve seat arrangement results in an annular space  53  that creates a restricted exhaust flow area just downstream of the exhaust line-contact  54  and the smaller-diameter end  48 . The restricted flow area is created as the exhaust ball-poppet  52  initially moves out of such line-contact  54  to its initially opening position shown in FIG. 9 as exhaust fluid flows downstream past the ball-poppet  52  through the smaller-diameter end  48  of the exhaust valve seat  46 . Consequently, any sonic flow erosion damage caused by such initial flow of high-pressure exhaust fluid is shifted substantially immediately to an upstream flow area adjacent the exhaust valve seat  46 . This is highly advantageous in that it shifts such wear or damage caused by such sonic flow erosion to annular space  53  rather than in contact with the ball-poppet  52 . Accordingly, the sonic damage to the smaller-diameter upstream sealing end  48  of the exhaust valve seat  46  is minimized. As a result, the damage to and wear of the actual sealing surface of the valve seat  46  on the ball-poppet  52  is likewise substantially minimized and the functional life of the exemplary control valve  10  is correspondingly greatly extended. Valve seat  46  is preferably made of a rigid metal such as but not limited to stainless steel. In this regard, the downtime and the maintenance costs are reduced for a system employing a control valve  10  according to the present invention.  
         [0053]    Referring primarily to FIG. 1, the cross-over leakage of the exemplary fluid control valve  10  depicted in the drawings is substantially minimized by energizing the exhaust pilot actuator  90  to close the exhaust ball-poppet  52  just slightly prior to energizing the supply pilot actuator  80  to open the ball-poppet  42 . Because of the equipment and energy necessary to elevate the working fluid to such a high-pressure state, minimizing cross over leakage greatly reduces the operating costs that would otherwise result from excessive waste or exhaust of high-pressure working fluid. Such high-pressure working fluid, which can be either pneumatic or hydraulic, but which is preferably pneumatic, is often in the range of 300 psig to 900 psig, and is typically approximately 600 psig in the above-mentioned blow-molding processes.  
         [0054]    Finally, either or both of the ball-poppets  42  and  52  are preferably composed of a metallic material, such as stainless steel or other metallic or non-metallic materials deemed advantageous by one skilled in the art for a given application. Similarly, either or both of the supply poppet guide  62  and the exhaust poppet guide  72  are preferably composed of a synthetic material, such as nylon, but can also be composed of a metallic material, such a stainless steel, or other suitable materials known to those skilled in the art.  
         [0055]    [0055]FIGS. 10 through 15 illustrate various versions of a selector fluid control valve that can be used either alone or in conjunction (on the supply side) with the primary fluid control valve discussed above in connection with FIGS. 1 through 9. Because many of the components of the valves illustrated in FIGS. 10 through 15 are either identical or substantially similar, at least in function, with those of the valves depicted in FIGS. 1 through 9, such components in FIGS. 10 through 15 are indicated by reference numerals that are the same as those in FIGS. 1 through 9, but which have two hundred, three hundred, or four hundred prefixes.  
         [0056]    In FIGS. 10 through 13, an exemplary selector fluid control valve  210  includes a body  212 , a pilot cap  214 , and a manifold  216  (as shown in FIGS. 11 through 13). Body  212  and pilot cap  214  are secured to manifold  216  in a manner similar to that depicted above in connection with FIGS. 1 through 9. However, it should be understood that body  212  and pilot cap  214  may be coupled together by way of fluid piping, without the use of manifold  216 , if threaded ports are alternatively provided.  
         [0057]    The exemplary selector fluid control valve  210  includes an inlet port  220  and  221 , which are in fluid communication with separate sources of working fluid. Inlet port  220  is configured for communicating with fluid at a relatively higher pressure whereas inlet port  221  is configured for communicating with fluid at a relatively lower pressure. Such relatively higher pressures will be referred to herein as “high-pressure”, and such relatively lower pressures will similarly be referred to as “low-pressure”. It should be appreciated that the inlet and outlet ports described herein may alternatively be threaded.  
         [0058]    A load fluid outlet passage  228  extends through the body  212  of the selector fluid control valve  210  and is in fluid communication with an outlet load port  222 . The selector fluid control valve  210  can be used either alone, or in combination with a primary fluid control valve, such as the primary fluid control valve  10  of FIGS. 1 through 9. In such an application, the selector fluid control valve  210  can have its load outlet port  222  interconnected in fluid communication with the inlet port  20  of the primary fluid control valve  10 , either by fluid piping or by way of the manifold  216  of FIG. 11.  
         [0059]    The selector fluid control valve  210  also includes a normally closed high-pressure valve mechanism in fluid communication between the high pressure inlet port  220  and the load fluid outlet passage  228 . Similarly, a normally open low-pressure valve mechanism is in fluid communication between the low-pressure inlet port  221  and the load fluid outlet passage  228 . In the exemplary selector fluid control valve  210 , the high-pressure valve mechanism includes a frusto-conical valve seat  236 , which in turn includes a smaller-diameter end  238  and a larger-diameter end  240 . A ball-poppet  242 , which is preferably generally spherical in shape and configuration, engages the valve seat  236  in a substantially line-contact engagement, in a manner as previously explained in more detail in connection with the valve seat  36  and the ball-poppet  42  of FIGS. 1 through 9. Similarly, the low-pressure valve mechanism includes a valve seat  246  having a smaller-diameter end  248  and a larger-diameter end  250 , with the low-pressure ball-poppet  252  engaging the small-diameter end  248  in the same type of line-contact as is discussed above.  
         [0060]    The high-pressure ball-poppet  242  is received within a high-pressure ball-poppet guide  262  similar to the ball-poppet guide  62  of FIGS. 1 through 9. In a similar manner, the low-pressure ball-poppet  252  is received within a low-pressure ball-poppet guide  272 . The guides  262  and  272  maintain the radially-floating and ball-poppet centering capabilities, associated with the guides  62  and  72  of FIGS. 1 through 9. In contrast however, the fins  266  and  276  do not necessarily extend axially beyond the end of their respective guides  262  and  272  as with the fins  66  and  76  from the above-discussed guider  62  and  72 . In such an arrangement, instead of the O-rings  61  and  71  of FIGS. 1 through 9, resilient wavy washers or spring wave washers  261  and  271  are provided to resiliently bias the respective guides  262  and  272  toward their respective proper positions within the respective guide bores  264  and  274 . In substantially all other respects, however, the ball-poppet guides  262  and  272  perform in a substantially identical manner as the corresponding ball-poppet guides  62  and  72  discussed above.  
         [0061]    In the preferred selector fluid control valve  210 , the high-pressure ball-poppet  242  is biased toward its normally closed position by a return spring  258  acting on the ball-poppet  242  by way of a ball-poppet perch  275 . A pilot actuator  280  is provided in connection with the high-pressure ball-poppet  242  and is selectively actuable to force the ball-poppet  242  off of its respective valve seat  236  and into its open position, with the pilot actuator  280  acting through the high-pressure actuating piston assembly  281  and the push rod  282 .  
         [0062]    In the low-pressure valve mechanism, the ball-poppet  252  is in a normally-open position under the influence of the low-pressure working fluid from the low-pressure inlet  221  acting on the ball-poppet  252  and against the biasing force of a low-force retaining spring  251 . The low-pressure ball-poppet  252  is held in place by a retainer plug  249  having a generally U-shaped opening  278  extending therethrough, as is illustrated in FIG. 10 a.  The opening travel of the low-pressure ball-poppet  252  is limited by its contact with a stop rod or pin  277  fixedly interconnected with the retainer plug  249  and extending into the retainer plug passage  278 .  
         [0063]    In operation, the selector fluid control valve  210  can be used to selectively supply one of two different pressures of working fluid (preferably a pneumatic working fluid) to either a fluid-actuated device or to the inlet of a primary control valve (such as the primary fluid control valve  10  discussed above) by way of the outlet load port  222  of the selector fluid control valve  210 . Initially, a source of relatively low-pressure working fluid is supplied to the low-pressure inlet port  221  and passes by the normally-open ball-poppet  252  to the load fluid outlet passage  228  and the outlet load port  222 . Such relatively low-pressure working fluid exerts sufficient force on the low-pressure ball-poppet  252  to maintain it in its open position against the biasing force of the low-pressure retaining spring  251  as long as fluid is flowing in the circuit. Thus, in this condition, as is illustrated in FIG. 10, relatively high-pressure working fluid supplied to the high-pressure inlet port  220  is isolated from the relatively low-pressure working fluid in the load fluid outlet passage  228  by the normally closed high-pressure ball-poppet  242 . The normally closed high-pressure ball poppet is forced against its respective valve seat  236  under the influence of the return spring  258 . In this condition, such relatively low-pressure working fluid is supplied to the outlet load port  222 .  
         [0064]    However, when it is desired to admit relatively high-pressure working fluid to the load fluid outlet passage  228  and to the outlet load port  222 , the pilot actuator  280  is selectively energized. It should be noted that the pilot actuator  280  can be pneumatically operated, electrically operated, or mechanically operated, for example.  
         [0065]    The energization of the pilot operator  280  causes the piston assembly  281  and the push rod  282  to force the high-pressure ball-poppet  242  to its open position against the biasing force of the return spring  258  and the high-pressure fluid in the inlet  220 . This opening of the high-pressure ball-poppet  242  allows relatively high-pressure working fluid from the high-pressure inlet port  220  to pass into the load fluid outlet passage  228 . The high-pressure working fluid now admitted into the load fluid outlet passage  228  acts (in conjunction with the low-force retaining spring  251 ) to urge the normally open low-pressure ball-poppet  252  to its closed position in sealing engagement with the valve seat  246 . Thus, in this condition, the relatively low-pressure working fluid from the low-pressure inlet port  221  is isolated from the relatively high-pressure working fluid in the load fluid outlet passage  228 , the retainer plug passage  278 , and the outlet load port  222 . As mentioned above, this allows for selective supply of either the relatively low-pressure working fluid or the relatively high-pressure working fluid from the outlet load port  222  to a fluid actuated device or to the inlet  20  of a primary valve such as that of the primary control valve  10  illustrated in FIGS. 1 through 9. This latter arrangement is illustrated in FIGS. 11 through 13 where the selector fluid control valve  210  and the primary control valve  10  are mounted together on a manifold  216 . Again manifold  216  may alternately be replaced by separate fluid piping if alternate threaded ports are provided.  
         [0066]    In FIG. 14, an alternate embodiment of a selector fluid control valve according to the present invention is depicted for purposes of illustrating that the present invention is equally applicable to such control valves adapted for supplying more than two different working fluid pressures to a fluid-actuated device, either directly or through a primary fluid control valve, such as the primary fluid control valve  10  discussed above and shown in FIGS. 1 through 9. The selector fluid control valve  410  in FIG. 14 has numerous components that are either identical or functionally substantially similar to those of the fluid selector control valve  210  in FIG. 10. In FIG. 14, however, such corresponding components are indicated by reference numerals having four-hundred prefixes and a or b suffixes in the case of components that are identical with each other.  
         [0067]    The body  412  of the selector fluid control valve  410  includes two of the above-discussed high-pressure inlets  420   a  and  420   b,  with two of the above-described pilot actuators  480   a  and  480   b,  each of which are separately and selectively operable to urge their respective ball-poppets  442   a  and  442   b  into their respective open positions. In virtually all other respects, however, the selector fluid control valve  410  operates in substantially the same manner as the above-described selector fluid control valve  210 .  
         [0068]    The operational difference between the selector fluid control valve  410  and the selector fluid control valve  210  is that the pilot actuators  480   a  and  480   b  can be separately and selectively actuated or energized, or de-actuated or de-energized, in order to allow for the selective supply of three different pressures or working fluid to the fluid-actuated device, by way of the load outlet port  422 , either directly or by way of the above-mentioned primary fluid control valve. It should be noted that FIG. 14 illustrates merely an exemplary multi-pressure application of the present invention, and one skilled in the art will now readily recognize that any number of different pressures can be accommodated by the selector fluid control valve of the present invention.  
         [0069]    In FIG. 15, still another alternate arrangement of the present invention is depicted, in which the resilient spring wave washer  361  is moved to an opposite position with respect to the ball-poppet guide than that depicted in FIG. 10. In this arrangement, a replaceable valve seat disc  388 , which includes the valve seat  336  therein, is trapped between the ball-poppet guide  362  and the downstream end of the guide bore  364 . The valve seat disc  388  includes a chamfered edge  386  that is sealingly engaged by an O-ring  384  and is preferably composed of a harder material than that of the valve body. Such an arrangement allows for convenient replacement of a worn valve seat  336  by merely replacing the valve seat disc  388 , without the necessity of discarding or re-machining the valve seat  236  of the body  212  in FIG. 10. Thus, one selector fluid control valve can be partially disassembled and repaired by such replacement of the valve seat disc  388  while another selector fluid control valve is in service. Such repaired selector fluid control valve can then be maintained in reserve for immediate replacement of a worn selector fluid control valve that is currently in service. It should be noted that a similar replaceable valve seat disc can also alternatively be used in conjunction with any of the valve mechanisms or arrangements shown in FIGS. 1 through 15.  
         [0070]    Finally, the preferred pneumatic high-pressure working fluid or fluids can be at virtually any pressure above that of the low-pressure working fluid, such as, for example, pressures in the range of 300 psig to 900 psig, with one application requiring a high-pressure working fluid at approximately 600 psig. Similarly, the low-pressure working fluid can be at virtually any pressure lower than that of the high-pressure working fluid, such as, for example, pressures in the range of 10 psig to 300 psig, with at least one application requiring such low-pressure working fluid at a pressure of approximately 100 psig. Furthermore, as mentioned above, the primary fluid control valves and the selector control valves of the present invention have wide-ranging applicability in various liquid or pneumatic fluid control or actuation systems. One example of such an application is a pneumatic system for blow molding of plastic bottles or other containers, which requires a first relatively lower pressure to urge the plastic material into the mold cavity, followed by a relatively higher pressure working fluid to complete the blow molding process by forcing the plastic material against the internal contours of the mold. One skilled in the art will readily recognize, however, that this is merely one example of the many applications of the present invention.  
         [0071]    Turning now to FIG. 16, an alternate embodiment of the selector fluid control valve according to the present invention is shown. The selector fluid control valve  610  in FIG. 16 has numerous components that are either identical or functionally substantially similar to those of the fluid selector control valve  210  in FIG. 10. In FIG. 16, however, such corresponding components are indicated by reference numerals having five-hundred prefixes in the case of components that are identical with each other. Furthermore, components corresponding to selector valve  610  incorporating adjustment stem  602  are referenced with numerals having a six-hundred prefix.  
         [0072]    The body  512  of the selector fluid control valve  510  includes the above-discussed high-pressure inlet  520 , with the above-described pilot actuator  580  which is selectively operable to urge ball-poppet  542  into its respective open position. It is noted that wave springs  561  and  571  have been relocated to opposite sides of ball-poppets  542  and  552 . In addition, as will be explained in greater detail later, the normally-open low-pressure ball poppet  552  cooperates with fluid control adjustment stem  602 . In virtually all other respects, however, the selector fluid control valve  610  operates in substantially the same manner as the above-described selector fluid control valve  210 .  
         [0073]    With continued reference to FIG. 16, fluid control adjustment stem  602  is selectively linearly actuated through bore  604  upon rotation of flow control knob  606 . In this regard, the linear travel of adjustment stem  602  is restricted between surfaces  608  and  612  by collar  611 . Threads  624  are incorporated in plug  616  for cooperating with complimentary threads  618  on adjustment stem  602 . Fasteners  626  threadably secure plug  616  to pilot cap  614 . A jam nut  640  and washer  642  are positioned between control knob  606  and pilot cap  614 . Jam nut  640  engages threads  622  to lock stem  602  to pilot cap  614 . Pin or engagement portion  630  extends from a distal end of adjustment stem  602  for engaging ball poppet  552  and limiting the allowable displacement thereof. A return spring  632  is incorporated around pin  630 .  
         [0074]    The operation of adjustment stem  602  will now be described in greater detail. The flow rate allowed around ball poppet  552  is determined by the displacement of ball poppet  552  from valve seat  546 . In this regard, the flow rate is increased as ball poppet  552  moves away from valve seat  546 . The allowable displacement of ball poppet  552  from valve seat  546  is controlled by the location of pin  630  extending from adjustment stem  602 . Explained further, fluid flow through low-pressure inlet port  521  urges ball poppet  552  away from valve seat  546  into contact with pin  630 . In this manner, the adjustment stem  602  may be positioned at a predetermined location to obtain a desired flow rate around ball poppet  552 . Once a desired flow rate is reached, jam nut  640  may be advanced into engagement with pilot cap  614  to preclude inadvertent rotation of control knob  606 .  
         [0075]    The foregoing discussion discloses and describes merely exemplary embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from such discussion, and from the accompanying drawings and claims, that various changes, modifications, and variations can be made therein without departing from the spirit and scope of the invention as defined in the following claims.