Abstract:
This invention relates to an improved air operated fluid control valve which tends to inhibit or impede the travel of a fluid to the air controlled side of the control valve. The air operated fluid control valve includes a control valve having a valve body provided with at least one fluid inlet port and at least one fluid outlet port, at least one air inlet port and at least one air outlet port, and a piston assembly selectively controlled by the air inlet and outlet ports so as to regulate the flow of a fluid through the valve body from the at least one fluid inlet port to the at least one fluid outlet port. According to one preferred embodiment of this invention, the control valve includes at least one shield member carried by piston assembly which is operative to inhibit the travel of a fluid from a fluid side of the control valve into an air controlled side of the control valve.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to fluid control valves and in particular to an improved air operative fluid control valve. 
     Air operated fluid control valves are known for supplying a fluid to a workpiece, workstation, or for other desired applications. A typical air operated fluid control valve includes a fluid side and an air side. The air side provides a source of air which is used to regulate the valve in order to deliver a fluid, such as a glue, adhesive, sealant, etc., from the valve to the desired application. Over time, the seals provided in the control valve will tend to wear and eventually, the fluid will migrate from the fluid side to the air side of the valve. When this occurs, the fluid will travel past the seals to the air side and prevent the proper operation of the control valve. 
     SUMMARY OF THE INVENTION 
     This invention relates to an improved air operated fluid control valve which tends to inhibit or impede the travel of a fluid to the air controlled side of the control valve. The air operated fluid control valve includes a control valve having a valve body provided with at least one fluid inlet port and at least one fluid outlet port, at least one air inlet port and at least one air outlet port, and a piston assembly selectively controlled by the air inlet and outlet ports so as to regulate the flow of a fluid through the valve body from the at least one fluid inlet port to the at least fluid outlet port. According to one preferred embodiment of this invention, the control valve includes at least one shield member carried by piston assembly which is operative to inhibit the travel of a fluid from a fluid side of the control valve into an air controlled side of the control valve. 
     Other advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiments, when read in light of the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional view of a first embodiment of a prior art pneumatically controlled glue valve. 
         FIG. 2  is a plan view of a portion of a prior art glue supply system including the first embodiment of the prior art air operated fluid control valve illustrated in  FIG. 1 . 
         FIG. 3  is a sectional view of a second embodiment of a prior art glue valve. 
         FIG. 4  is a sectional view of a first embodiment of a fluid control valve in accordance with the present invention. 
         FIG. 5  is a sectional view of a second embodiment of a fluid control valve in accordance with the present invention. 
         FIG. 6  is a sectional view of a third embodiment of a fluid control valve in accordance with the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, there is illustrated in  FIGS. 1 and 2  a prior art air operated fluid control valve, indicated generally at  10 . The prior art air operated fluid control valve  10  is commercially available from Sealant Equipment and Engineering, Inc., of Plymouth, Mich., Model No. 2200-396-016 No-Drip® 60:1 Dispense Valve. The general structure and operation of the prior art air operated fluid control valve  10  is conventional in the art. Thus, only those portions of the prior art air operated control valve  10  which are necessary for a full understanding of this invention will be explained and illustrated. Although this invention will be described and illustrated in conjunction with the particular air operated fluid control valve constructions disclosed herein, it will be appreciated that this invention may be used in conjunction with other pneumatically and non-air operated fluid control valve constructions. 
     As shown therein, the prior art fluid control valve  10  includes a valve body  12 , a fluid body  14 , a valve cap  16 , and a piston rod assembly  18 . The valve body  12  is formed from a suitable material, such as for example, steel or aluminum, and is of a generally stepped configuration. The valve body  12  includes a generally opened first end  20  and a generally opened opposite second end  22 . The first end  20  includes a generally cylindrical non-threaded counterbore or recess  24  provided therein. The first end  20  includes an outer surface  26  having an externally threaded section  28  along a portion thereof. The second end  22  of the valve body  12  includes an internally threaded counterbore or recess  32  provided therein. 
     The valve body  12  further includes openings  34 ,  36 ,  38  and  40 . The opening  34  is a threaded opening and, as shown in prior art  FIG. 2 , is adapted to receive a suitable threaded connector C 1  of a supply line S 1  for a purpose to be discussed below. The opening  36  defines a passageway and is effective to operatively connect the supply line S 1  to the counterbore  24  of the valve  10  as will be discussed below. In this embodiment, the supply line S 1  is a pneumatic supply line and is operative to supply compressed air to the prior art fluid control valve  10  to actuate and open the valve as will be discussed below. The opening  38  is a generally elongated opening and extends at least through a portion of the valve body  12 . The opening  38  defines a drip or relief opening. The opening  40  extends clear through the valve body  12  from the first end  20  to the second end  22  and also extends through the opening  38  so as to be in communication therewith for a purpose to be discussed below. 
     The valve head  14  is formed from a suitable material, such as for example, steel or aluminum, and is of a generally stepped configuration. The valve head  14  includes a generally opened first end  50  and a generally opened opposite second end  52 . The first end  50  includes a generally cylindrical non-threaded counterbore or recess  54  provided therein and outer surface  56  having an externally threaded section  58  along a portion thereof. The externally threaded section  58  of the valve head  14  is adapted to be threadably disposed in the internally threaded counterbore  32  of the valve body  12  to secure the first end  50  of the valve head  14  to the second end  22  of the valve body  12 . The second end  52  of the valve head  14  includes a stepped counterbore or recess  60  provided therein. The counterbore  60  includes an internally threaded first portion  62  and a reduced diameter non-threaded second section  64  which extends toward the first end  50 . 
     The valve head  14  further includes an opening  66  provided therein. The opening  66  is a threaded opening  34  and, as shown in prior art  FIG. 2 , is adapted to receive a suitable threaded connector C 2  of a supply line S 2  for a purpose to be discussed below. The opening  66  is effective to operatively connect the fluid supply line S 2  to the counterbore  54  of the valve  10  as will be discussed below. In this embodiment, the supply line S 2  is a fluid supply line and is operative to supply a glue or sealant to the prior art fluid control valve  10  as will be discussed below. 
     The valve cap  16  is formed from a suitable material, such as for example, steel or aluminum, and is of a generally stepped configuration. The valve cap  16  includes a generally closed first end  70  and a generally opened opposite second end  72 . The first end  70  includes an opening  74  formed therethrough. The opening  74  includes an internally threaded section  76  and is adapted to receive a suitable threaded connector C 3  of a supply line S 3  for a purpose to be discussed below. The opening  74  is effective to operatively connect the supply line S 3  to the first end  20  of the valve body  12  as will be discussed below. In this embodiment, the supply line S 3  is a pneumatic supply line. The supply line S 3  cooperates with the supply line S 1  to regulate the supply and flow of the compressed air to the prior art fluid control valve  10  to thereby selectively open and close the valve to supply an adhesive from the fluid supply line S 2  to the valve where it is discharged through the fluid body  14  to a fluid supply line S 4  (shown in prior art  FIG. 2 ), as will be discussed below. 
     The second end  72  of the valve cap  16  includes a stepped counterbore or recess  78  provided therein. The counterbore  78  is provided with internal threads  80 . The externally threaded section  28  of the valve head  12  is adapted to be threadably disposed in the internally threaded counterbore  78  of the valve cap  16  to secure the first end  20  of the valve body  12  to the second end  72  of the valve cap  16 . A gasket or seal  82  is disposed in the counterbore  78  of the valve cap  16  and is operative to sealingly engage the first end  20  of the valve body  12  during the assembly of the valve body  12  to the valve cap  16  to provide an air-tight seal therebetween. 
     The piston rod assembly  18  includes a piston  90  and a piston rod  92 . The piston  90  is formed from a suitable material, such as for example, steel, aluminum or plastic, and is generally annular shaped. The piston  90  includes an annular recess or groove  94  provided in an outer surface  96  thereof and a generally central opening  98  formed therethrough. A seal  100  formed from a suitable material, such as an elastomeric material, is disposed in the piston groove  94 . The seal  100  sealingly engages a side wall surface  24 A of the counterbore  24  of the valve body  12  to define a pair of pneumatic chambers P 1  and P 2  on the opposite sides of the piston  90 . In the illustrated embodiment, the seal  100  is an O-ring seal. 
     The piston rod  92  is formed from a suitable material, such as for example, steel or aluminum, and includes a first end  102  and an opposite second end  104 . The first end  102  of the piston rod  92  is attached to the piston  90  by suitable means. In the illustrated embodiment, this is accomplished by a threaded fastener  106 . The fastener  106  extends through the opening  98  of the piston  90  and external threads  108  thereof are threadably received in an internally threaded opening  118  provided in the first end  102  of the piston rod  92  to thereby secure the first end  102  of the piston rod  92  to the piston  90 . The second end  104  of the piston rod  92  has a generally ball-shaped configuration for a purpose to be discussed below. 
     The prior art air operated fluid control valve  10  includes a first seal  110 , a second seal  112 , and a bearing  116  disposed about the piston rod  92 . The first seal  110  is an annular fluid seal and is disposed in an annular groove  114  provided in the valve body  12 . The second seal  112  is disposed in the counterbore  54  of the first end  50  of the fluid body  14 . The bearing  116  is disposed in the counterbore  54  of the first end  50  of the fluid body  14  adjacent the second seal  112 . 
     The prior art fluid control valve  10  further includes a fluid connector or coupling  120  attached to the second end  52  of the fluid body  14 . The coupling  120  is formed from a suitable material, such as for example, steel or aluminum. The coupling  120  includes a generally opened first end  122  and a generally opened opposite flanged second end  124 . The coupling  120  is provided with a stepped opening  126  formed therethrough. The opening  126  includes a non-threaded portion  128  adjacent the first end  122 , an intermediate shoulder  130 , and an internally threaded portion  132  adjacent the second end  124 . The threaded portion  132  of the coupling  120  is adapted to receive a suitable threaded connector C 4  of a supply line S 4  for a purpose to be discussed below. In this embodiment, the supply line S 4  is a fluid supply line and is operative to supply the glue or sealant from the prior art fluid control valve  10  to a desired work station, surface of a component part, or the like (none of which are shown). 
     The coupling  120  further includes an outer surface  134  provided with external threads  136 . The external threads  136  of the coupling  120  are adapted to be threadably disposed in the internally threaded counterbore  62  of the fluid valve  14  to secure the coupling  120  to the second end  52  of the fluid valve  14 . A gasket or seal  140  is disposed in counterbore  60  of the valve head  14  and is operative to sealingly engage a portion of the first end  122  of the coupling  120  during the assembly of the coupling  120  to the fluid body  14 . The coupling  120  further includes a seat member  142  disposed in the non-threaded portion  128  of the opening  126  of the coupling  120  between the gasket  140  and the shoulder  130 . The seat member  142  is operative to sealingly engage the ball shaped end  104  of the piston rod  92  for a purpose to be discussed below. The seat member  142  is formed from a suitable material, such as for example, and elastomeric material. 
     In operation, a suitable fluid, such as compressed air, is selectively supplied to the prior art fluid control valve  10  to cause the fluid control valve  10  to be selectively moved or actuated between a closed position (shown in prior art  FIG. 1 ) and an opened position (not shown). In particular, pressurized or compressed air is supplied to the fluid control valve  10  via the supply line S 1  to cause the piston rod assembly  18  to be moved to the left when viewing  FIG. 1 . As a result of this movement of the piston rod assembly  18 , the ball shaped second end  104  of the piston rod  92  is moved off of the seat member  142  to allow a fluid, such as for example, adhesives, sealants and lubricants, to travel through the valve  10  from the supply line S 2 , through the fluid body  14  and the coupling  120 , to the supply line S 4 . This is the opened position or actuated state of the prior art fluid control valve  10  (not shown). To move the fluid control valve  10  back to the closed position (shown in  FIG. 1 ), the compressed air is supplied to the valve  10  via the supply line S 3  to cause the piston rod assembly to move to the right when viewing  FIG. 1 . As a result of this movement of the piston rod assembly  18 , the ball shaped second end  104  of the piston rod  92  is moved against the seat member  142  to prevent the flow of a fluid through the valve. The structure and operation of the prior art air operated fluid control valve  10  thus far described is conventional in the art. 
     Referring now to  FIG. 3 , there is illustrated a prior art air operated fluid control valve, indicated generally at  300 , which is similar in structure and operation to that of prior art fluid control valve  10  described above and illustrated in prior art  FIGS. 1 and 2 . The main differences between the prior art fluid control valves  10  and  300  is that prior art fluid control valve  300  includes a dual piston rod assembly which is operative to dispense a two component material, as will be discussed below, and which in cooperation with the fluid supply lines is operative to create a vacuum when the valve is closed which tends to withdraw or suck back any fluid contained therein. The prior art air operated fluid control valve  300  is commercially available from Sealant Equipment and Engineering, Inc., of Plymouth, Mich., Model No. 2200-250-019 Snuf-Bak™ Dual Component Dispense Valve. The general structure and operation of the prior art air operated fluid control valve  300  is conventional in the art. Thus, only those portions of the prior art air operated fluid control valve  300  which are necessary for a full understanding of this invention will be explained and illustrated. Although this invention will be described and illustrated in conjunction with the particular air operated fluid control valve constructions disclosed herein, it will be appreciated that this invention may be used in conjunction with other air and non-air operated fluid control valve constructions. 
     As shown therein, the prior art fluid control valve  300  includes a valve body  312 , a valve head  314 , a valve cap  316 , and a dual piston rod assembly  318 . The valve body  312  is formed from a suitable material, such as for example, steel or aluminum, and includes a generally opened first end  320  and a generally opened opposite second end  322 . The first end  320  includes a generally cylindrical non-threaded counterbore or recess  324  provided therein. The first end  320  includes an outer surface  326  having an externally threaded section  328  along a portion thereof. The valve body  312  further includes openings  334 ,  336 ,  338  and  340 . The openings  334  and  336  are threaded openings and each is adapted to receive a suitable threaded connector (not shown) of an associated fluid supply line, schematically shown by arrows S 10  and S 11 , respectively, for a purpose to be discussed below. 
     The valve head  314  is formed from a suitable material, such as for example, steel or aluminum, and is of a generally stepped configuration. The valve head  314  includes a generally opened first end  350  and a generally closed opposite second end  352 . The first end  350  includes a pair of generally cylindrical non-threaded counterbores or recesses  354  provided therein. The valve head  314  is secured to the valve body  312  by appropriate means, such as for example, by fasteners (not shown). An annular fluid seal  450  is disposed in each of the annular grooves  452  provided in the first end  350  of the valve head  314 . The seals  450  are operative to provide a seal between the adjacent end surfaces  322  and  350  of the valve body  312  and valve head  314 , respectively. 
     The second end  352  of the valve head  314  includes a pair of openings  366 A and  366 B provided therein. The openings  366 A and  366 B define a pair of nozzles and are in communication with the respective openings  334  and  336  to operatively connect the fluid supply lines S 10  and S 11  to the respective nozzles  366 A and  366 B as will be discussed below. Also, the valve head  14  is provided with external threads  368  which are adapted to threadably receive a nozzle fitting (not shown) having a desired nozzle outlet size. In this embodiment, the supply lines S 10  and S 11  are operative to supply a two component glue or sealant to the prior art fluid control valve  300  as will be discussed below. 
     The valve cap  316  is formed from a suitable material, such as for example, steel or aluminum, and is of a generally stepped configuration. The valve cap  316  includes a generally closed first end  370  and a generally opened opposite second end  372 . The first end  370  includes a first internally threaded opening  374  formed therethrough. The opening  374  is adapted to receive a suitable threaded connector (not shown) of a pneumatic supply line, schematically shown by arrow S 12 , for a purpose to be discussed below. The opening  374  is effective to operatively connect the associated pneumatic supply line S 12  to the first end  320  of the valve body  312  as will be discussed below. The valve body  312  further includes a suitable opening (illustrated for discussion purposes at  312 A) which is operatively connected to an associated pneumatic supply line, schematically illustrated by arrow S 13 . In this embodiment, the supply lines S 12  and S 13  are operative to regulate the supply of pressurized or compressed air to the prior art fluid control valve  300  to thereby selectively open and close the valve to supply adhesive from the lines S 10  and S 11  to the valve where it is discharged through the nozzles  366 A and  366 B as will be discussed below. In prior art  FIG. 3 , the control valve  300  is shown in the closed position. The first end  370  of the valve cap  316  is further provided with a threaded opening  376  formed therethrough. The opening  376  is adapted to receive an adjust screw  378 . 
     The second end  372  of the valve cap  316  includes a counterbore or recess  382  provided therein. The counterbore  382  is provided with internal threads  384 . The externally threaded section  328  of the valve body  312  is adapted to be threadably disposed in the internally threaded counterbore  382  of the valve cap  316  to secure the first end  320  of the valve body  312  to the second end  372  of the valve cap  316 . A gasket or seal  384  is disposed in the counterbore  382  of the valve cap  316  and is operative to sealingly engage the first end  320  of the valve body  312  during the assembly of the valve body  312  to the valve cap  316 . 
     The piston rod assembly  318  includes a piston  390  and a pair of piston rods  392 . The piston  390  is formed from a suitable material, such as for example, steel or aluminum, and is generally annular shaped. The piston  390  includes an annular recess or groove  394  provided in an outer surface  396  and a generally central threaded opening  398  formed therethrough. An annular seal  400  formed from a suitable material, such as an elastomeric material, is disposed in the groove  394 . The seal  400  engages the side wall of the counterbore  324  of the valve body  312  to define a pair of pneumatic chambers on opposite sides of the piston  390 . In the illustrated embodiment, the seal  400  is an O-ring seal. 
     Each of the piston rods  392  are formed from a suitable material, such as for example, steel or aluminum, and includes a first end  402  and an opposite second end  404 . The first ends  402  of the piston rods  392  are attached to a retainer  406  by suitable means. In the illustrated embodiment, this is accomplished by a threaded fastener  408 . The retainer  406  is attached to the piston  390  by suitable means. In the illustrated embodiment, this is accomplished by a threaded fastener  410 . The fastener  410  extends through the retainer  406  and is threadably received in the threaded opening  398  of the piston  390  to thereby secure the retainer  406 , and therefore the piston rods  392 , to the piston  390 . The piston rods  392  near the second ends  404  have a necked down or reduced diameter portion  412  for a purpose to be discussed below. 
     The prior art air operated fluid control valve  300  includes a pair of first seals  420 , a pair of second seals  424 , a pair of third seals  426 , a pair of bearings  428  disposed about the piston rods  392 , and a pair of retainers  430 . The pair of first seals  420  are annular fluid seals and are disposed in associated annular groove  430  provided in the valve body  312  and retained therein by a retainer  434  and a fastener  436 . The pair of second seals  424  and the bearings  428  are disposed in an associated counterbore  440  provided in the valve body  312 . The pair of third seals  426  are disposed in the counterbores  354  of the first end  350  of the fluid body  314 . Each of the retainers  430  is disposed in the valve body  312  between an associated pair of the seals  424  and  426 . 
     In operation, a suitable fluid, such as compressed air, is selectively applied to the prior art fluid control valve  300  to cause the fluid control valve  300  to be selectively moved or actuated between a closed position (shown in  FIG. 3 ) and an open position (not shown). In particular, compressed air is supplied to the fluid control valve  300  via the supply line S 12  to cause the piston rod assembly  318  to move to the right when viewing in  FIG. 3 . As a result of this movement of the piston rod assembly  318 , the ends  404  of the piston rods  392  are moved to the right in  FIG. 3  away from contact with the seals  426  and the reduced diameter portions  412  are operative to allow a fluid, such as glue, to travel through the valve  300  from supply lines S 10  and S 11 , through the openings  334  and  336 , into the valve head  314  and then out through the nozzle openings  366 A and  366 B. This is the open position or actuated state of the fluid control valve  300 . To move the fluid control valve  300  back to the closed position, compressed air is supplied to the fluid control valve  300  via the supply line S 13  to cause the piston rod assembly to move to the left in  FIG. 3  to illustrated closed position. The structure and operation of the prior art air operated fluid control valve  300  thus far described in conventional in the art. 
     Turning now to  FIG. 4  and using like reference numbers to indicate corresponding parts, there is illustrated a first embodiment of an air operated fluid control valve, indicated generally at  200 , constructed in accordance with this invention. As shown therein, the fluid control valve  200  is similar to the prior art fluid control valve  10  discussed above except for the structure of the associated valve body and piston rod. 
     As shown in the embodiment illustrated in  FIG. 4 , the fluid control valve  200  includes a two-piece valve body, indicated generally at  212 . The two-piece valve body  212  includes a first valve body  214  and a second valve body  216  secured to and spaced apart from one another. In the illustrated embodiment, a plurality of threaded fasteners  218  and nuts  220  are used to secure the first valve body  214  and the second valve body  216  together (two of such fasteners  218  and nuts  220  being illustrated in  FIG. 3 ). Each fastener  218  extends through a pair of aligned openings  222  and  224  formed in respective outer flanges  226  and  228  of the valve bodies  214  and  216 , respectively. A rigid tube  230  is disposed about the body of the fastener  218  to space the valve bodies  214  and  216  apart from one another a predetermined distance X. Alternatively, other methods can be used to space apart and/or secure together the valve bodies  214  and  216 . For example, a threaded rod (not shown) and nuts (not shown) on each end thereof can be used to secure the valve bodies together. Also, the valve body  212  can include more or less than two components if so desired. For example, the valve body  212  could be of a one-piece construction. 
     The fluid control valve  200  further includes a plurality of shields or baffles  240  installed on the piston rod  92 . In the illustrated embodiment, the piston rod  92  includes three shields  240  installed thereon and spaced apart from one another by suitable means. Each shield  240  is generally annular in shape and formed from a suitable material, such as for example, metal or plastic. In accordance with the present invention, the shields  240  are operative to prevent or slow down the migration of the fluid (i.e., glue, sealant, adhesive, etc.), along the piston rod  92  from the fluid side of the valve  300  (i.e., the right side in  FIG. 4 ) to the air side of the valve  300  (i.e., the left side in  FIG. 4 ) so as to prolong the operating life of the valve  300  before the valve  300  needs to be serviced/replaced. Such fluid travel occurs after sufficient wear of the fluid seal  112  occurs. 
     Each shield  240  can be permanently secured to the piston rod  92  by a suitable method, such as for example, by welding or using adhesives, or can be removably secured to the piston rod  92  by a suitable method, such as for example, by using mechanical fasteners or an interference fit therewith. Also, the shields  240  could be integrally formed with the rod  92 . Preferably, once the shields  240  are secured to the piston rod  92  the shield  240  is not free to move relative thereto. Alternatively, the number, structure, material, location and/or the attachment of the shields  240  can be other than illustrated and described if so desired. For example, the valve  200  of this invention can include only a single shield  240  installed on the piston rod  92 . Also, in this embodiment, the shield  240  is formed separate from the piston rod  92 . Alternatively, the piston rod  92  could include one or more shields  240  which are formed integral therewith if so desired. Also, in this embodiment, the valve body  212  has an essentially open framework or construction between the first valve body  214  and the second valve body  216  except for the tubes  230 . Alternatively, the valve body  214  could be of a more closed framework than that which is illustrated and provided with one or more openings formed therein, such opening(s) being similar in function to that of the opening  38  described and illustrated above in connection with the prior art fluid control valve  10  illustrated in prior art  FIGS. 1 and 2 . Also, one or more shields  240  could be secured, permanently or removably, by suitable means, to the valve body  212  itself (such as the shields  240 A shown in phantom in  FIG. 4 ), instead of to the piston rod  92  so long as the shields  240  achieve their intended purpose. 
     Turning now to  FIG. 5  and using like reference numbers to indicate corresponding parts, there is illustrated a second embodiment of an air operated fluid control glue valve, indicated generally at  500 , constructed in accordance with this invention. As shown therein, the fluid control valve  500  is similar to the prior art fluid control valve  300  discussed above except for the structure of the associated valve body and piston rod. 
     As shown in  FIG. 5 , the fluid control valve  500  includes a two-piece valve body, indicated generally at  512 . The two-piece valve body  512  includes a first valve body  514  and a second valve body  516  secured to and spaced apart from one another. In the illustrated embodiment, a plurality of threaded fasteners  518  and nuts  520  are used to secure the first valve body  514  and the second valve body  516  together (two of such fasteners  518  and nuts  520  being illustrated in  FIG. 5 ). Each fastener  518  extends through a pair of aligned openings  522  and  524  formed in respective outer flanges  526  and  528  of the valve bodies  514  and  516 , respectively. A rigid tube  530  is disposed about the fastener  518  to space the valve bodies  514  and  516  apart from one another a predetermined distance X 1 . Alternatively, other methods can be used to space apart and/or secure together the valve bodies  514  and  516 . For example, a thread rod (not shown) and nuts (not shown) on each end thereof can be used to secure the valve bodies together. Also, the valve body  512  can include more or less than two components if so desired. For example, the valve body  512  could be of a one-piece construction. 
     The fluid control valve  500  further includes a plurality of shields or baffles  540  installed on the piston rods  392 . In the illustrated embodiment, each of the piston rods  392  includes three shields  540  installed thereon and spaced apart from one another by suitable means. In accordance with the present invention, the shields  540  are operative to prevent or slow down the migration of the fluid (i.e., glue, sealant, adhesive, etc.), along the piston rod  392  from the fluid side of the valve  500  (i.e., the right side in  FIG. 5 ) to the air side of the valve  500  (i.e., the left side in  FIG. 5 ) so as to prolong the operating life of the valve  500  before the valve  500  needs to be serviced/replaced. Such fluid travel occurs after sufficient wear of the fluid seals  424  occurs. 
     Each shield  540  is generally annular in shape and formed from a suitable material, such as for example, metal or plastic. Each shield  540  can be permanently secured to the associated piston rod  392  by a suitable method, such as for example, by welding or using adhesives, or can be removably secured to the piston rod  392  by a suitable method, such as for example, by using mechanical fasteners or an interference fit therewith. Also, the shields  540  could be integrally formed with the rod  392 . Preferably, once the shield  540  is secured to the piston rod  32  the shield  540  is not free to move relative thereto. Alternatively, the number, structure, material, location and/or the attachment of the shield  540  can be other than illustrated and described if so desired. For example, the valve  500  of this invention can include only a single shield  540  installed on each of the piston rod  392 . Also, in this embodiment, the shield  540  is formed separate from the piston rod  392 . Alternatively, the piston rod  392  could include one or more shields  540  which are formed integral therewith if so desired. Also, in this embodiment, the valve body  512  has an essentially open framework or construction between the first valve body  514  and the second valve body  516  except for the tubes  530 . Alternatively, the valve body  514  could be of a more closed framework than that which is illustrated and provided with one or more openings formed therein, such opening(s) being similar in function to that of the openings  338  and  340  described and illustrated above in connection with the prior art fluid control valve  300  illustrated in prior art  FIG. 3 . For example, the valve  300  of this invention can include only a single shield  540  installed on each of the piston rods  392 . Also, in this embodiment, the shield  540  is formed separate from the associated piston rods  392 . Alternatively, each of the piston rods  392  could include one or more shields  540  which are formed integral therewith if so desired. Also, one or more shields  540  could be secured, permanently or removably by suitable means, to the valve body  512  itself (such as the shields  540 A shown in phantom in  FIG. 5 ), instead of to the piston rod  392  so long as the shields  540  achieve their intended purpose. 
     Turning now to  FIG. 6  and using like reference numbers to indicate corresponding parts, there is illustrated a third embodiment of an air operated fluid control valve, indicated generally at  600 , constructed in accordance with this invention. As shown therein, the fluid control valve  600  is similar to the prior art fluid control valve  10  discussed above except for the structure of the associated valve body  612 , piston rod assembly  648 , and valve cap  614 . 
     As shown in  FIG. 6 , the fluid control valve  600  includes a two-piece valve body, indicated generally at  612 , a valve cap  614 , and a piston member  616 . The two-piece valve body  612  includes a first valve body  620  and a second valve body  622  secured to and spaced apart from one another by fasteners and rigid support rods  624 . 
     In the illustrated embodiment, a plurality of threaded fasteners  626  (two of such fasteners  626  being illustrated in  FIG. 6 ), are used to secure the first valve body  620  and also the valve cap  614  to a first end of the support rods  624 . Each fastener  626  extends through a pair of aligned openings  630  and  632  formed through the valve cap  614  and the first valve body  620 , respectively, and are received in a threaded opening  634  provided in the support rod  624 . 
     The second valve body  622  is secured to an opposite end of the support rods  624 . In the illustrated embodiment, to accomplish this the support rods  624  include a threaded fastener  640  which is disposed therein and has a threaded end which is in installed in an internally threaded opening  642  provided in the second valve body  622 . Alternatively, the construction of the valve body  612  can be other than illustrated if so desired. 
     The piston rod assembly  648  includes a coupler  650 , a combination shaft connector and shield  652 , the piston rod  92 , and a piston (not shown but can be similar to the piston  90  shown in connection with the prior art fluid control valve illustrated and described above in prior art  FIGS. 1 and 2 ). The coupler  650  includes a first end (not shown) operatively connected to the piston (not shown), and an opposite second end  660  connected to the shaft connector and shield  652  by suitable means. In the illustrated embodiment, to accomplish this the coupler  650  includes an internally threaded opening  662  and the shaft connector and shield  652  includes an externally threaded end  664 . The shaft connector and shield  652  is connected to the piston rod  92 . In the illustrated embodiment, to accomplish this the shaft connector and shield  652  includes an externally threaded extension  666  which is threadably disposed in the internally threaded opening  118  of the piston rod  92 . Alternatively, the number, structure, material, location and/or the attachment of the shaft connector and shield  652  can be other than illustrated and described if so desired. For example, the valve  600  of this invention can include a shaft connector and shield  652  having more than one shield member installed thereon. Also, in this embodiment, the shield member is formed integral with the shaft connector portion. Alternatively, the piston rod assembly  648  could include one or more shields formed separate from the shaft connector portion and secured thereto by suitable means if so desired. In accordance with the present invention, the shields  652  is operative to prevent or slow down the migration of the fluid (i.e., glue, sealant, adhesive, etc.), along the piston rod  92  from the fluid side of the valve  600  (i.e., the right side in  FIG. 6 ) to the air side of the valve  600  (i.e., the left side in  FIG. 6 ) so as to prolong the operating life of the valve  600  before the valve  600  needs to be serviced/replaced. Such fluid travel occurs after sufficient wear of the fluid seal  112  occurs. 
     Also, in this embodiment, the valve body  612  has an essentially open framework or construction between the first valve body  620  and the second valve body  620  except for the support rods  624 . Alternatively, the valve body  612  could be of a more closed framework than that which is illustrated and provided with one or more openings formed therein, such opening(s) being similar in function to that of the openings  338  and  340  described and illustrated above in connection with the prior art fluid control valve  300  illustrated in prior art  FIG. 3 . 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been described and illustrated in its preferred embodiments. However, it must be understood that the invention may be practiced otherwise than as specifically explained and illustrated without departing from the scope or spirit of the attached claims.