Abstract:
A dual locking valve assembly includes two check valve elements in two cartridge bores. Each check valve element opens to permit forward flow of fluid under pressure in the cartridge bore from an input bore to an output bore. The check valve element closes to block back flow of fluid under pressure in the cartridge bore from the output bore towards the input bore. The back flow of fluid under pressure exerts a closing force upon the check valve element from within the output chamber. A counter force generating element, or pilot element, communicates with the valve element, to selectively open the valve, even in the presence of back flow pressure. The pilot element exists as a fluid crossover path from one cartridge bore to the other.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application Ser. No. 61/190,391, filed 28 Aug. 2008, and entitled “Dual Locking Flow Control Valve,” which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to fluid pressure operated systems and devices, particularly those featuring at least partially fluid tight operation. 
       BACKGROUND OF THE INVENTION 
       [0003]    A very popular valve in the automation industry is a 4-way directional control valve. This valve consists of a manifold with a set of flow control solenoids mounted onto the manifold. The solenoids shift a spool using a combination of air and electricity to redirect the flow of the air through the manifold. The spool and the bore within which it slides are often constructed of metal. The steel spool slides inside the metal bore to shift the direction of fluid, such as air, oil or water to different ports. This metal-on-metal seal has a tendency to leak after operating for a short period of time. 
         [0004]    There remains a need for a valve that can solve this tendency to leak problem, either by being an add-on to the leaking valve, or by being integrated into the valve, which, in turn, will lead to increased safety and operating life. There is also a need for easy attachment and compact size. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention provides a dual locking (DL) valve that can be easily attached to a manifold to solve the leaking problem. This is advantageous in automated systems that must hold position without drifting over time or where parts must be held in place in the event of a drop in pressure and is also advantageous for use in leak testing systems. A second advantage is that no mounting holes or extra space is required for mounting the valve. The valve may mount directly to a 4-way valve manifold with two fasteners. A third advantage is no additional plumbing is required, i.e., all plumbing is internal. The DL valve also has a manual release so that during system repair or during an emergency stop, the potential energy of the trapped air can be released. A variety of options can also be added, including flow controls, adjustable pilot, sensor ports, auto release with metered exhaust, manual exhaust to atmosphere. 
         [0006]    Additional advantages of the invention include:
   1. The addition of the DL valve makes the entire valve assembly fluid tight on both the output ports, which eliminates drift due to leaky or worn spools.   2. The DL valve can be added without having to drill holes for mounting the valve, i.e., direct mount to the base manifold.   3. No added plumbing is required, so time and money are saved.   4. Fast and easy to attach the DL valve—saving time and money, i.e., the DL may be assembled in approximately two minutes. The DL may also be added after a machine has already been assembled.   5. A manual release allows the release of trapped air from both ports independently.   6. The flow control option controls the velocity of the pneumatic device, for use on single manifolds.   7. The adjustable pilot option, also for use on single manifolds, can be used to overcome differential pressure problems and set for quicker stopping.   8. An embodiment of the DL valve incorporates compatibility with the International Organization for Standardization (ISO) port interface specification ISO 15407-2 (with electrical connector) or 15407-1 (without electrical connector), directed to pneumatic fluid power, five-port directional control valves.   
 
         [0015]    Generally, a valve according to the present invention includes a valve body having first, second, third and fourth reentrant bores formed therein. The valve body further includes a first cartridge bore in fluid communication with the first third reentrant bores and a second cartridge bore in fluid communication with the second and fourth reentrant bores. The cartridge bores preferably include a piston bore, an input counterbore, an output counterbore and a bearing sleeve counterbore. At least partially within each cartridge bore is a piston cartridge. Each piston cartridge includes a longitudinal piston rod, a first piston head secured to one end of the piston rod, and a second piston head secured to a second end of the piston rod. A poppet member is slidably disposed on the piston rod, biased in a poppet bias direction by a poppet bias spring. The valve body further includes a first fluid channel in fluid communication with the first reentrant bore and the second cartridge bore, preferably with its respective piston bore. Separated from the first fluid channel is a second fluid channel in fluid communication with the second reentrant bore and the first cartridge bore, preferably with its respective piston bore. A plurality of nonintersecting throughbores may be formed through said valve body. The plurality of nonintersecting throughbores may number three to five. 
         [0016]    According to an embodiment of a valve according to the present invention, the valve body may be a unitary member. The valve body may be at least substantially parallelepiped in shape, including a front surface, back surface, top surface, bottom surface, left surface and right surface. A plurality of nonintersecting throughbores may be formed through the valve body, including through the bottom surface and the top surface. 
         [0017]    According to an embodiment of a valve according to the present invention, the cartridge bores may extend through and include the left surface and the right surface. The first reentrant bore and the second reentrant bore may be formed into the valve body through the top surface. The third reentrant bore and the fourth reentrant bore may be formed into the valve body through the bottom surface. 
         [0018]    According to an embodiment of a valve according to the present invention, the valve may further include a manual release mechanism including a manual release cover, a manual release gasket and first and second manual release plungers. The manual release cover includes a pilot channel formed therein and is coupled to the valve body to cover one end of the cartridge bores. The manual release gasket includes a first plunger aperture, a second plunger aperture and a gasket pilot hole formed therethrough, where the gasket is situated between a portion of the manual release cover and the valve body placing the gasket pilot hold in fluid communication with the pilot channel. The first manual release plunger extends through the manual release cover, through the first plunger aperture in the gasket and into the first piston bore so as to be contactable with the first piston cartridge. The second manual release plunger extends through the manual release cover, through the second plunger aperture in the gasket and into the second piston bore so as to be contactable with the second piston cartridge. 
         [0019]    According to an embodiment of a valve according to the present invention, the valve may include a flow control mechanism. The flow control mechanism may include a mounting plate including a first adjusting aperture and a second adjusting aperture formed therethrough. A first threaded adjusting screw may extend through the first adjusting aperture into the first cartridge bore, preferably the output counterbore thereof, and a second threaded adjusting screw may extend through the second adjusting aperture into the second cartridge bore, preferably the output counterbore thereof. A first lock nut may be threaded onto the first adjusting screw, adapted to selectively prevent rotation of the first adjusting screw with respect to the mounting plate, and a second lock nut may be threaded onto the second adjusting screw, adapted to selectively prevent rotation of the second adjusting screw with respect to the mounting plate. The mounting plate is preferably coupled to the valve body to cover one end of the cartridge bores. 
         [0020]    A system according to the present invention includes a fluid controlled actuator, a manifold in fluid communication with the fluid controlled actuator, first and second check valves in fluid communication with the manifold, and a fluid controlled solenoid assembly in fluid communication with the check valves. The fluid controlled actuator generally includes a first fluid chamber and a second fluid chamber. Such fluid controlled actuator, or fluid motor, may be a linear actuator comprising a plunger coupled to an actuating rod, where the plunger separates the first fluid chamber and the second fluid chamber. The manifold generally includes a first fluid port in fluid communication through a first fluid line with the first chamber of the fluid actuator and a second fluid port in fluid communication through a second fluid line with the second chamber. The manifold further includes a third fluid supply port. The first check valve includes a first check valve input, a first check valve output, and a first check valve pilot input, wherein the first check valve output is in fluid communication with the first fluid port on the manifold. The second check valve includes a second check valve input, a second check valve output, and a second check valve pilot input, wherein the second check valve output is in fluid communication with the second fluid port on the manifold. Also, the second check valve input is in fluid communication with the first check valve pilot input, and the second check valve pilot input is in fluid communication with the first check valve input. The fluid control solenoid assembly includes a fluid flow control spool that is moveable between a first position in which the fluid supply port is in fluid communication with the first check valve input, and a second position in which the fluid supply port is in fluid communication with the second check valve input. 
         [0021]    According to one aspect of a system according to the present invention, when a supply fluid pressure in the fluid supply port is lost, the first check valve and the second check valve are closed. 
         [0022]    According to one aspect of a system according to the present invention, when the fluid control solenoid assembly is in either of the first and second positions and when the supply fluid pressure is greater than either of the first fluid pressure or the second fluid pressure by a predetermined flow amount, respectively, both check valves are opened. 
         [0023]    According to an aspect of a system according to the present invention, when the fluid control solenoid assembly is in the first position and when the supply fluid pressure is greater than the first fluid pressure, the supply fluid flows from the supply fluid port through the first check valve, through the first fluid line and into the first chamber, and a first exhaust fluid flows from the second chamber, through the second fluid line and through the second check valve. 
         [0024]    According to an aspect of a system according to the present invention, when the fluid control solenoid assembly is in the second position and when the supply fluid pressure is greater than the second fluid pressure, the supply fluid flows from the supply fluid port through the second check valve, through the second fluid line and into the second chamber, and exhaust fluid flows from the first chamber, through the first fluid line and through the first check valve. 
         [0025]    These and other features and advantages of the invention will become apparent from the following description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIGS. 1A ,  1 B and  1 C form a schematic representation of a first embodiment of a system according to the present invention. 
           [0027]      FIG. 1B  is a cross-section view taken along line  1 B of  FIG. 1A . 
           [0028]      FIG. 1C  is a cross-section view taken along line  1 C of  FIG. 1A . 
           [0029]      FIG. 2  is a front top right perspective view of a first embodiment of a valve according to the present invention. 
           [0030]      FIG. 3  is a front bottom left perspective view of the embodiment of  FIG. 2 . 
           [0031]      FIG. 4A  is a cross section partial assembly view taken along line  4 A- 4 A of  FIG. 2 . 
           [0032]      FIG. 4B  is a right elevation, partial exploded view of the embodiment of  FIG. 2 . 
           [0033]      FIG. 5A  is a cross section view of a second embodiment of a valve according to the present invention taken generally along a line similar to line  4 A- 4 A of  FIG. 2 , but further including a flow control option. 
           [0034]      FIG. 5B  is a left elevation view of the embodiment of  FIG. 5A . 
           [0035]      FIG. 6A  is a cross section view of a third embodiment of a valve according to the present invention taken generally along a line similar to line  4 A- 4 A of  FIG. 2 , but further including a flow control option. 
           [0036]      FIG. 6B  is a left elevation view of the embodiment of  FIG. 6A . 
           [0037]      FIGS. 7A ,  7 B and  7 C form a schematic representation of a first embodiment of a system according to the present invention. 
           [0038]      FIG. 7B  is a cross-section view taken along line  7 B- 7 B of  FIG. 7A . 
           [0039]      FIG. 7C  is a cross-section view taken along line  7 C- 7 C of  FIG. 7A . 
           [0040]      FIG. 8  is a front top right perspective view of a known manifold. 
           [0041]      FIG. 9  is a front top right perspective view of a fourth embodiment of a valve according to the present invention. 
           [0042]      FIG. 10  is a front bottom left perspective view of the embodiment of  FIG. 9 . 
           [0043]      FIG. 11A  is a partially exploded cross section view taken along line  11 A- 11 A of  FIG. 9 . 
           [0044]      FIG. 11B  is an assembly view of a piston cartridge shown in  FIG. 11A . 
           [0045]      FIG. 12A  is a bottom plan view of the embodiment of  FIG. 9 . 
           [0046]      FIG. 12B  is a plan view of a gasket used with the embodiment of  FIG. 9 . 
           [0047]      FIG. 13  is a top plan view of a fifth embodiment of a valve according to the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0048]    Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
       I. A System 
       [0049]    Turning to the figures,  FIGS. 1A ,  1 B and  1 C provide an embodiment of a system  10  in which an embodiment of a dual locking valve according to the present invention may be used. Generally, air pressure from a supply source  12 , is directed through a manifold  20  and through an embodiment of a dual locking valve  100 , to controlling solenoids  16 . An electrical signal (not shown) sent to the solenoids  16  shifts a spool  18  contained therein, directing air pressure back through the dual locking valve  100  and out the manifold  20  to a working air cylinder  30 . A plunger  32 , located at least partially in the air cylinder  30 , applies force to an object (not shown), as is known. 
         [0050]    The air cylinder  30  has a rod chamber  33  and a plunger chamber  35 . The rod chamber  33  is located between the plunger  32  and a rod end  34  of the cylinder  30 , and the plunger chamber  35  is located between the plunger  32  and the plunger end  36  of the cylinder  30 . In order for the plunger  32  to move towards the rod end  34  of the cylinder  30 , the rod chamber  33  of the air cylinder  30  must have an exhaust path to the atmosphere. This is accomplished by opening the piston cartridge  200   a  opposite the pressurized piston cartridge  200   b.    
         [0051]    As the piston  32  moves to extend the cylinder rod  38 , the air in the rod chamber  33  is pushed out. The exhaust air  13  travels back into the manifold  20 , through the valve  100 , through the solenoids  16 , back through the valve  100 , and out the manifold  20  to atmosphere. 
         [0052]    In the event that the supply air pressure  11  is lost or a drop in that pressure occurs, the valve  100  will trap air on both sides of the air cylinder  30 , locking the plunger  32  in a safe, at least substantially static position. 
       II. Valve 
       [0053]    Turning now to  FIG. 2  and  FIG. 3 , an embodiment  100  of a valve according to the present invention is shown. Generally, the valve  100  includes a valve body  102 , into which a plurality of reentrant bores  110  are formed, and through which a plurality of throughbores  120  may be formed. A first reentrant bore  112  and a second reentrant bore  114  may be formed in a spaced relationship into the valve body  102 . A third reentrant bore  116  and a fourth reentrant bore  118  may also be formed in a spaced relationship into the valve body  102 . The first and second reentrant bores  112 , 114  may be formed into the same surface of the valve body  102 , such as a top surface  104  thereof. The third and forth reentrant bores  116 , 118  may be formed into the same surface of the valve body  102 , such as a bottom surface  106  thereof. The top surface  104  and the bottom surface  106  may be substantially planar surfaces that may be at least substantially parallel to each other. Another reentrant bore that may be provided is a locating, or registration, bore  119 . The registration bore  119  may also be formed into the top surface  104 . 
         [0054]    The throughbores  120  provided may serve a variety of purposes. For instance, a first pair of mounting throughbores  122  may be provided. A second pair of control throughbores  124  may provide direct flowthrough to enable control of the solenoid  16 . A third pair of exhaust throughbores  126  may be provided. A supply air throughbore  128  and an electrical connector throughbore  129  may also be provided. It is to be understood that some or all of the throughbores  120  may be utilized in any given embodiment. The throughbores  120  preferably extend completely through the thickness of the valve body  102 , such as between and including the top surface  104  and the bottom surface  106 . 
         [0055]    Also with reference to  FIG. 4A , disposed within the valve body  102  are a first cartridge bore  142  and a second cartridge bore  144 . The first cartridge bore  142  is in fluid communication with the first reentrant bore  112  and the third reentrant bore  116 , and the second cartridge bore  144  is in fluid communication with the second reentrant bore  114  and the fourth reentrant bore  118 . The cartridge bores  142 , 144  may be formed substantially orthogonal to their respective reentrant bores  112 , 116  and  114 , 118 . 
         [0056]    Each cartridge bore  142 , 144  is preferably formed as a throughbore which may include one or more counterbores. 
         [0057]    Within each cartridge bore is a piston cartridge  200 . The cartridges  200  are interchangeable, fluid tight, and function to hold air in the cylinder  30  in the event of a pressure loss or a change in pressure. The piston cartridge  200  generally includes a longitudinal piston rod  202 , a first piston head  210 , a second piston head  220 , and a poppet member  230  slidably disposed on the piston rod  202  and located generally between the first and second piston heads  210 , 220 . The substantially free sliding movement of the poppet member  230  generally, without pilot pressure, checks air in one direction and allows free flow in the opposite direction. The first piston head  210  is connected to a first end  204  of the piston rod  202 , and the second piston head  220  is connected to a second end  206  of the piston rod  202 , which may include a threaded engagement means  208  to cooperate with the second piston head  220 . The first piston head  210  is preferably formed with an annular piston seal groove  212  about its circumference, which accommodates placement of a first piston seal  214 , such as a grooved elastomeric O-ring. The first piston head  210  also preferably provides a first poppet stop surface  216  and a piston bias bore  218  adapted to accept a piston bias spring, such as an end cap spring  256 . The second piston head  220  is preferably formed with an annular piston seal groove  222  about its circumference, which accommodates placement of a second piston seal  224 , such as a grooved elastomeric O-ring. The second piston head  220  also preferably provides a second poppet stop surface  226 . 
         [0058]    The poppet member  230  is slidably disposed on the piston rod  202 , the piston rod  202  preferably extending through the poppet member  230 . Situated between the poppet member  230  and the piston rod  202 , there may be a rod gasket or seal  203  such as an elastomeric O-ring that is disposed in an annular groove  205  formed about the piston rod  202 . Situated between the poppet member  230  and the first piston head  210  is a poppet bias spring  240 , which biases the poppet member  230  in a bias direction  242 , which is generally towards the second piston head  220 . The poppet member  230  itself may generally be formed as a frustoconical member extending between a first end  232  and a second end  234 , and further including an annular sealing flange  236  disposed thereabout. The annular sealing flange  236  includes a sealing surface  238 , which, when the piston cartridge  200  is assembled, generally faces towards the second piston head  220 . Disposed on and/or recessed into the sealing surface  238  is a poppet gasket  239 , which may be formed of an elastomeric material. 
         [0059]    The piston cartridge  200  may generally be assembled by situating the rod gasket  203  in the annular groove  205  provided on the piston rod  202 . The poppet bias spring  240  may be placed on the rod  202 , resting against the first piston head  210 . The poppet member  230  may be slid onto the piston rod  202  and the second piston head  220  may be secured to the piston rod  202 . The piston seals  214 , 224  are placed around their respective piston heads  210 , 220 . 
         [0060]    As indicated above, the cartridge bores  142 , 144  are provided with preferably at least one counterbore. For clarity in this section, only the first cartridge bore  142  will be described, with the understanding that the description also applies to the second cartridge bore  144 . The cartridge bore  142  includes a piston bore  142   a , an input counterbore  142   b , an output counterbore  142   c , and a bearing sleeve counterbore  142   d . The first, or input reentrant bore  112  intersects the cartridge bore  142  at the input counterbore  142   b  and the third, or output reentrant bore  116  intersects the cartridge bore  142  at the output counterbore  142   c . The output counterbore  142   c  provides a poppet seat, or sealing ledge  148  and further provides sufficient clearance for sliding movement of the poppet member  230  and desired fluid flow. To maintain the piston cartridge  200  in a preferred orientation, a bearing sleeve  250  may be used. The bearing sleeve  250  includes a piston aperture  252 , into which the first piston head  210  may be situated, the bearing sleeve  250  circumferentially contacting the first piston seal  214 . Disposed around the bearing sleeve  250  is preferably a bearing sleeve seal  254 , such as an elastomeric O-ring, which is adapted to sealingly engage the output counterbore  142   c  provided in the cartridge bore  142 . The second piston head  220  is received into the piston bore  142   a.    
         [0061]    In the first embodiment  100 , the piston cartridges  200  and bearing sleeves  250  are maintained in the valve body  102  by a piston cover  130 , which generally extends to cover one side of the cartridge bores  142 , 144  and is secured to the valve body  102 , such as by using a plurality of threaded fasteners  132 . On the opposite end of the cartridge bores  142 , 144  from the piston cover  130 , a manual release mechanism  150  may be provided. The manual release mechanism  150  includes a manual release cover  152 , a pair of manual release plungers  154 , and a manual release gasket  156 . The manual release plungers  154  are flanged posts that extend through the manual release cover  152 , sealed thereto by a manual release plunger gasket  158 , such as an elastomeric O-ring, through the gasket  156  to contact the second piston head  220  or second piston rod end  206  to enable manual override of the piston bias spring  256 . This allows the release of air that may be trapped in the air cylinder  30 . 
         [0062]    The manual release cover  152 , the manual release gasket  156  and certain features of the valve body  102  provide pilot fluid crossover fluid paths. That is, it has been found desirable to place the first reentrant bore  112  in fluid communication with the second piston bore  144   a  and the second reentrant bore  114  in fluid communication with the first piston bore  142   a . The first reentrant bore  112  is placed in fluid communication with the second piston bore  144   a  through a first crossover fluid path  160 . The first crossover fluid path  160  is created partially by a first pilot input reentrant bore  162  formed into the valve body  102 , terminating in fluid communication with the first reentrant bore  112 . A first pilot channel  164  is formed in the valve body  102  thereby fluidly coupling the first pilot reentrant bore  162 , and thus the first reentrant bore  112 , to the second piston bore  144   a . The second reentrant bore  114  is placed in fluid communication with the first piston bore  142   a  through a second crossover fluid path  165 . The second crossover fluid path  165  is created partially by a second pilot input reentrant bore  166  formed into the valve body  102 , terminating in fluid communication with the second reentrant bore  114 . A second pilot channel  168  is formed in the manual release cover  152 , separated from the first pilot channel  164  by the manual release gasket  156 . The second pilot channel  168  fluidly couples the second pilot reentrant bore  166 , and thus the second reentrant bore  114 , through a gasket pilot hole  169 , to the first piston bore  142   a.    
       III. Detailed Operation 
       [0063]    Turning back to  FIG. 1 , the operation of the system  10  in moving the plunger  32  in a single direction is described herein. It will be readily understood by a person of ordinary skill in the art that movement of the plunger  32  in the opposite direction would simply involve a shift in the solenoid spool  18 , and the operation would be identical, with each piston cartridge  200  swapping functionality with the other. Air pressure  11  from the supply source  12 , is connected to the supply port  22  on the manifold  20 . This port  22  is placed in fluid communication with the supply throughbore  128  on the valve  100 , thereby providing a direct flow path to the solenoids  16 . The solenoid  16  shifts the spool  18  with a combination of air pressure and an electrical signal, to direct the flow of the air pressure  11  to the first reentrant bore  112 , causing the poppet member  230  located in the first cartridge bore  142  to open due to a buildup of air pressure. The poppet member  230  is biased toward the poppet seat  148  by the poppet bias spring  240 , which allows the poppet member  230  to open when there is a 1-2 psi pressure difference across the poppet member  230 . With the poppet member  230  open, or spaced from the poppet seat  148 , the air moves through the first reentrant bore  112 , through the first cartridge bore  142  and into the third reentrant bore  116 . The third reentrant bore  116  is in fluid communication with a first control port  301  on the manifold  20 , which is in fluid communication with the plunger chamber  35  of the air cylinder  30 . 
         [0064]    The air in the rod chamber  33  needs a passage to exhaust to atmosphere. This is accomplished by using the pressure side of the valve  100  to open the cartridge  200  on the exhaust side of the circuit. This is accomplished by using the crossover fluid paths  160 , 165 . Through one of these paths at a time, the air from a reentrant bore on the pressure side unseats the poppet member  230  in the exhaust cartridge  200  allowing air to flow from the fourth reentrant bore  118 , which is in fluid communication with a second control port  302  on the manifold  20 , to the second reentrant bore  114 . The open path allows air to escape from the rod chamber  33  of the cylinder  30  up to the solenoids  16  where there is an open flow through the solenoid  16  and back into the valve  100  through an exhaust throughbore  126  which is connected to the manifold  20  and which is exhausted to atmosphere out of one of the exhaust ports  325  therein. 
         [0065]    The cartridges  200  fit into the valve body  102 , at least partially, but preferably entirely within the cartridge bores  142 , 144 . The cartridge  200  slides into the cartridge bore  142 , where the second piston seal  224  contacts the piston bore  142   a , the poppet member  230  is in the output counterbore  142   c  and is biased toward the poppet seat  148  resulting in an air-tight seal on the poppet seat  148 . The bearing sleeve  250  and the bearing sleeve seal  254  slide into the output counterbore  142   c  and rest on the bearing sleeve counterbore  142   d.    
         [0066]    The end cap spring  256  is placed in the end of the first piston head  210 , which may be formed as an integral part of the piston rod  202 , to bias the entire cartridge  200  toward the poppet seat  148 . The entire procedure is repeated for the second cartridge  200 . When both cartridges are in place, the piston cover  130  is fastened in place with screws  132 . When the cover  130  is in place, the poppet members  230  are closed against the poppet seats  148 . 
         [0067]    The solenoids  16  may likely require electrical signals to operate. Normally, the solenoids  16  are mounted directly to the manifold  20 , thereby allowing a direct connection between an electrical plug on the solenoids  16  and an electrical jack on the manifold  20 . When the valve  100  is placed between the manifold  20  and the solenoids  16 , however, the electrical signal to power the two solenoids may be carried by an electrical passthrough connector  170  on the valve  100  that plugs into a female connector on the manifold  20  and a male connector on the solenoids  16 . The air pressure required to shift the spool  18  in the solenoid assembly  16 , is supplied by the two control throughbores  124  in the valve body  102 . 
         [0068]    The air passages between the DL valve and the manifold are sealed with a gasket ( 28 ). The groove to retain the gasket is machined into the DL block ( 2 ). The air passages between the solenoids ( 4 ) and the DL valve are sealed with a gasket attached to the solenoids ( 4 ). 
         [0069]    The entire assembly comprising the solenoids  16 , the valve  100  and the manifold  20  may be held together with just two standoffs (not shown) that have a male thread on one end that threads into the manifold  20  and a female thread that connects to the solenoids  16 . The standoffs fit into the mounting throughbores  122  in the valve body  102  so that a standoff seal can seal air-tight in the standoff bore  122 . A small locating, or registration pin  172  helps to locate or align the connection between the manifold  20  and the valve  100 , and may cooperate with a registration bore  319  on the manifold  20 . 
         [0070]    The two control throughbores  124  provided through the valve body  102  supply air from the manifold  20  to the two solenoids  16  that help to open and close air passages in conjunction with electronic signals to help shift the spool  18  from side to side. 
       IV. Valve Options 
       [0071]    A. Flow Controls 
         [0072]    One option is a flow control for both cartridges  200  to control cylinder speed by metering airflow from the air cylinder  30 .  FIGS. 5A and 5B  depict a second embodiment of a valve according to the present invention, where, instead of a simple piston plate  130 , a flow control mechanism  133  is provided in its place. An flow control adjusting screw  135  is added to the end of each cartridge that limits the movement of the poppet member  230  when the cartridge  200  is pressurized to the open position. A lock nut  137  may be used to lock the adjusting screw  135  in position. Metering out is the preferred method of controlling air cylinder speed. This also eliminates the need to add an extra valve to control the air cylinder speed. 
         [0073]    B. Adjustable Pilots 
         [0074]    An additional or alternative option gives the valve  100  the ability to adjust the air pressure required to shift the cartridges  200  and open the valve. The end cap spring  256  may not function correctly in cases where there is a large pressure difference between the cylinder advance and retract circuits. This can happen when the air cylinder  30  is in the vertical position with a large load on the end of the cylinder rod  38 . This will require a greater air pressure to lift the load than to lower the load. The small pressure required to lower the load may not be large enough to pilot the cartridge  200  open, so adjusting the spring pressure for a lower pressure operation will result in smoother operation. 
         [0075]    Adjusting the spring pressure to a higher force will also make the air cylinder stop faster. In some cases due to system design, the exhaust pressure cannot escape fast enough, causing the cartridge  200  to stay open. When the pressure drops low enough where the end cap spring  256  can overcome the pilot pressure, the cartridge  200  will close. The spring force on the cartridge  200  is increased by turning an adjusting screw  138  clockwise. Increasing the force on the cartridge  200  will cause the cartridge  200  to close faster. A set screw  139  is supplied for each cartridge  200  in order to lock the respective adjusting screw  138  in place. 
       V. Cascaded Manifold System 
       [0076]    Turning now to  FIGS. 7A ,  7 B and  7 C, a second system  17  according to the present invention is shown. It may be desirable to cascade two or more stackable manifolds  21  adjacent to each other. The system  17  operates the same as the first system  10 , the only exception being that a plurality of manifolds  21  for controlling a plurality of working loads, such as the cylinder  30 , are disposed adjacent each other. An example of such a manifold  21  is shown in  FIG. 8 . Generally this type of manifold  21  has a plurality of lateral ports that are in fluid communication with at least substantially identical lateral ports of neighboring manifolds  21 . The lateral ports may include a supply port  22 , solenoid control ports  323 , and exhaust ports  325 . Also provided on the manifold  21  is a solenoid interface  320 . The solenoid interface  320  includes solenoid control ports  324 , exhaust ports  326 , a first circuit port  312  and a second circuit port  314 . 
         [0077]    Like in the first system  10 , a flow control solenoid  16  would normally be placed directly adjacent the solenoid interface  320 . In this system  17 , however, a fourth embodiment  400  of a valve according to the present invention is placed between the manifold  21  and a flow control solenoid  16 . The fourth valve embodiment  400  is depicted in  FIGS. 9 ,  10 ,  11 A,  11 B and  12 . Generally, the valve body  402  of this embodiment  400  is substantially the same as the valve body  102  of the first embodiment  100 . The primary difference between this embodiment  400  and the first embodiment  100  is that this embodiment  400  includes substantially planar right and left sides  408 , 409 . That is, the first embodiment  100  included a manual release mechanism  150  protruding from its right side  108  and a piston plate  130  or other optional features protruding from the left side  109 . Due to the nature of the stacking manifolds  21 , however, such protrusions are undesirable as they interfere with adding valves onto each adjacent manifold. 
         [0078]    Accordingly, to render the sides  408 , 409  substantially planar, the fourth embodiment  400  incorporates a recessed crossover channel cover  452  on the right side  408  and a pair of recessed piston plates  430  on the left side  409 . The crossover channel cover  452  generally serves to cover one end of the cartridge bores  142 , 144 , as well as provide the fluid pilot channels  164 , 168 , generally in the same manner in which they are provided by the manual release cover  152 . The crossover channel cover  452  may be secured to the valve body  402  with countersunk threaded fasteners  453 . The recessed piston plates  430  generally serve the same purpose as the piston plate  130 , which is to provide a stationary abutment for the piston bias spring  256  and to at least partially contain the piston cartridge  200  in the cartridge bore  142  or  144 . The recessed piston plates  430  may be secured to the valve body  402  with countersunk threaded fasteners  432 . 
         [0079]      FIG. 12A  depicts a bottom plan view of the fourth embodiment  400  of a valve according to the present invention. The valve body  402 , like the valve body  102  of the first embodiment  100 , preferably includes a gasket groove  480  formed partially into the bottom surface  406  of the body  402 . Disposed at least partially in the gasket groove  480  is a preferably elastomeric gasket  482  as shown in  FIG. 12B . Also, in  FIG. 12A , it is to be noted that into the bottom surface  406  of the valve body  402 , the third reentrant bore  116 , the fourth reentrant bore  118 , the exhaust throughbores  126 , and the supply air throughbore  128  may be provided in a standardized interface orientation, such as that disclosed by the International Organization for Standardization (ISO) specification 15407-2 (or 15407-1), or an orientation compatible therewith. Such orientation may be utilized with any of the valve embodiments disclosed herein. 
         [0080]      FIG. 13  depicts a fifth embodiment  500  of a valve according to the present invention. The fifth embodiment  500  generally comprises the fourth embodiment  400 , with the inclusion of a manual release mechanism  490  for each cartridge bore  142 , 144 . Each manual release mechanism  490  includes a reentrant release bore  491  extending through an outside surface of the valve body  402  and into one of the cartridge bores  142  or  144 . The release bore  491  preferably includes a first counterbore  492  into which a release bias spring  493  and a release plug  494 , the release bias spring  493  biasing the plug  494  away from the respective cartridge bore  142  or  144 . The release bore  491  also preferably includes a second counterbore  495  into which a release plug collar  496  is secured, such as by being press fit or threaded therein. In this arrangement, in normal operation, the release bias spring  493  acts within the first counterbore  492  to bias the release plug  494  against the release plug collar  496 , thereby preventing any leakage. However, when desirable to manually release air pressure from a cartridge bore  142  or  144 , the force of the release bias spring  493  may be overcome by exerting pressure against the release plug  494  from outside the valve body  402 , thereby forcing the release plug  494  away from the release plug collar  496 , thereby allowing air to escape from the cartridge bore  142  or  144  through the reentrant release bore  491 , around the release plug  494  and out to the atmosphere. Also, in  FIG. 13 , it is to be noted that into the top surface  404  of the valve body  402 , the first reentrant bore  112 , the second reentrant bore  114 , the exhaust throughbores  126 , and the supply air throughbore  128  may be provided in a standardized orientation, such as that disclosed by the International Organization for Standardization (ISO) specification 15407-2 (or 15407-1). Such orientation may be utilized with any of the valve embodiments disclosed herein. 
         [0081]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. For instance, it will occur that various combinations of the features herein described may be accommodated. For instance, the manual release mechanism  150  of the first valve embodiment  100  may be adapted for use with the second valve embodiment  400 , instead of the recessed crossover channel cover  452 . Also, while the preferred embodiment has been generally described as a pneumatic linear actuator, it is to be understood that an embodiment of the present invention may utilize or be utilized with any fluid motor. Furthermore, while the preferred embodiment has been described in connection with air as the fluid, it is to be understood that a valve according to the present invention would also function with other fluids such as oil and water. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.