Abstract:
A fluid control device is disclosed that is configured to vent pilot volume through an exhaust port or exhaust passageway ( 140 ) integrated into the fluid control device. The fluid control device has a fluidic switch ( 112 ) configured to switch a pilot volume into the exhaust port or exhaust passageway ( 140 ) when a signal port or signal passageway ( 114 ) is de-pressurized. The fluidic switch ( 112 ) couples the signal port or signal passageway ( 114 ) to the pilot volume when the signal port or signal passageway ( 114 ) is pressurized.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Fluid control devices typically are activated using a pressurized fluid passed through a signal port or passageway. The fluid may be pneumatic, hydraulic, or any other type of liquid or gas. The pressurized fluid may be introduced into the signal port or passageway using an activating device, for example a solenoid, attached to the fluid control device. The pressurized fluid causes a movable part inside the fluid control device to shift from a non-activated position to an activated position. When the pressurized fluid is removed, the movable part shifts back to the non-active position. The fluid trapped in the volume between the activated and non-activated positions must be vented for the movable part to return to the non-activated position. Typically the fluid is vented or exhausted out through the signal port or passageway to the solenoid. The exhaust flows through the solenoid and out through an exhaust passageway in the solenoid. Some solenoids may have small exhaust passageways that limit the flow of the exhaust fluid through the solenoid and create back pressure in the fluid control device. The back pressure may create seal wear and limit the speed of the fluid control device. 
       SUMMARY OF THE INVENTION 
       [0002]    A fluid control device is disclosed that is configured to vent pilot volume through an exhaust port or passageway integrated into the fluid control device. The fluid control device has a fluidic switch configured to switch a pilot volume into the exhaust port or passageway when a signal port or passageway is de-pressurized. The fluidic switch couples the signal port or passageway to the pilot volume when the port or signal passageway is pressurized. 
       ASPECTS 
       [0003]    One aspect of the invention includes, a fluid control device, comprising: 
         [0004]    a body having a first cavity; 
         [0005]    a movable part having a first end located inside the first cavity where the first end is located at a first position inside the first cavity when the movable part is at an activated position and where the first end is positioned inside the first cavity at a second position when the movable part is at a non-activated position and where the first end displaces a first volume between the first position and the second position; 
         [0006]    a first passageway coupled to the first cavity where the first passageway is coupled to a first fluidic switch; 
         [0007]    a first signal port coupled to the first fluidic switch and a first exhaust passageway coupled to the first fluidic switch where the first fluidic switch is configured to couple the first passageway with the first signal port when the first signal port is pressurized and where the first fluidic switch is configured to couple the first passageway with the first exhaust passageway when the first signal port is not pressurized thereby exhausting the first volume through the first exhaust passageway. 
         [0008]    Preferably, where the movable part is a spool and the fluid control device is a spool valve. 
         [0009]    Preferably, where the movable part is a piston and the fluid control device is a spool valve. 
         [0010]    Preferably, where fluidic switch is selected from one of the following: a poppet valve, a flapper valve, a ball shuttle valve. 
         [0011]    Preferably, where the first end forms a fluid tight seal with the first cavity. 
         [0012]    Preferably, at least one seal configured to form a fluid tight seal between the movable part and the body. 
         [0013]    Preferably, the fluid control device further comprising: 
         [0014]    a second cavity in the body; 
         [0015]    a second end of the movable part, opposite the first end, and located inside the second cavity where the second end is located at a first position inside the second cavity when the movable part is at the activated position and where the second end is positioned inside the second cavity at a second position when the movable part is at the non-activated position and where the second end displaces a second volume between the first position and the second position; 
         [0016]    a second passageway coupled to the second cavity where the second passageway is coupled to a second fluidic switch; 
         [0017]    a second signal port coupled to the second fluidic switch and a second exhaust passageway coupled to the second fluidic switch where the second fluidic switch is configured to couple the second passageway with the second signal port when the second signal port is pressurized and where the second fluidic switch is configured to couple the second passageway with the second exhaust passageway when the second signal port is not pressurized thereby exhausting the second volume through the second exhaust passageway. 
         [0018]    Another aspect of the invention comprises a method for operating a fluid control device, comprising: 
         [0019]    displacing a part in a first direction by pressing against a first end of the part with a pressurized fluid where the pressurized fluid fills a first volume as the part displaces, where the pressurized fluid is introduced into the first volume through a first fluidic switch that couples a first signal port to the first volume when the first signal port is pressurized; 
         [0020]    displacing the part in a second direction, opposite the first direction, and venting the fluid in the first volume through a first exhaust passageway by coupling the first volume to the first exhaust passageway with the first fluidic switch where the first fluidic switch is located internally to the fluid control device. 
         [0021]    Preferably, the method further comprises where the fluid control device is a spool valve. 
         [0022]    Preferably, the method further comprises venting a fluid in a second volume, as the part is displaced in the first direction, through a second exhaust passageway by coupling the second volume to the second exhaust passageway with a second fluidic switch where the second fluidic switch is located internally to the fluid control device. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0023]    It should be understood that the drawings are not necessarily to scale. 
           [0024]      FIG. 1  is a sectional view of a spool valve  100  in an example embodiment of the invention. 
           [0025]      FIG. 2   a  is a cross sectional view of one end of spool valve  100  in an activated position in an example embodiment of the invention. 
           [0026]      FIG. 2   b  is a cross sectional view of one end of spool valve  100  in an un-activated position in an example embodiment of the invention 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]      FIGS. 1-2  and the following description depict specific examples to teach those skilled in the art how to make and use the best mode of the invention. For the purpose of teaching inventive principles, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations from these examples that fall within the scope of the invention. Those skilled in the art will appreciate that the features described below for the various examples can be combined in various ways to form multiple variations of the invention. As a result, the invention is not limited to the specific examples described below, but only by the claims and their equivalents. 
         [0028]      FIG. 1  is a sectional view of a spool valve  100  in an example embodiment of the invention. Spool valve  100  comprises body  102 , spool  104 , left end  106 , right end  108 , two end plates  110 , a first fluidic switch  112 , a second fluidic switch  113  and seals  134 . Spool  104  is installed into a cavity formed in body  102 . Left and right ends ( 106  and  108 ) attach to the left and right side of body  102  respectively, capturing spool  104  between the two ends. A number of openings ( 124 ,  126 ,  128 ,  130  and  132 ) are formed in the bottom of body  102 . In other embodiments openings ( 124 ,  126 ,  128 ,  130  and  132 ) may be formed in either side, or a combination of sides and bottom, of body  102 . Spool  104  is configured to have two positions inside body  102 , a left position and a right position. Spool  104  is shown in the right position. In the right position, spool  104  couples opening  126  to opening  128 , and couples opening  130  to opening  132 . In the left position, spool couples opening  124  to opening  126 , and opening  128  to opening  130 . In other embodiments, spool  104  may couple other openings together in the two positions. Spool  104  is moved between the two positions by fluidic pressure pushing against one or the other end of spool  104 . The fluid may be air, water, hydraulic fluid or any other gas or liquid. In some example embodiment of the invention, a piston may be positioned at each end of the spool to help generate the force that moves the spool between positions. Seals  134  may be attached to spool  104  to help form fluid tight seals between spool  104  and body  102 . Fluidic switch  112  is installed into left end  106  and fluidic switch  113  is installed into the right end  108 . End plates  110  are attached to the left and right ends ( 106  and  108 ) and capture the fluidic switches ( 112  and  113 ) inside the left and right ends ( 106  and  108 ). A signal port or channel may be formed in each end plate  110 , and/or in end plate  106  and  108 , and allows a signal fluid to be applied to either end of spool valve  100 . 
         [0029]    In operation, a fluid is directed into the fluid signal port  114 . Fluidic switch  112  seals against exhaust passageway  140  and allows fluid to pass into signal passageway  138 . The fluid exits the signal passageway  138  and enters chamber or cavity  122  and pushes against the left side of spool  104 , forcing spool  104  to move into the right position. As spool  104  moves to the right, fluid trapped in chamber or cavity  136  at the right end of spool  104  is forced from chamber or cavity  136 . The fluid exiting chamber or cavity  136  causes fluidic switch  113  to seal signal port  120  and direct the exhaust fluid  116  to exit through exhaust passageway  141 . In prior art fluid control devices, the exhaust fluid forced from chamber or cavity  136  would be vented through signal port  120 . Typically a solenoid valve would be coupled to signal port  120  and used to provide the pressurized fluid to the signal port  120 . The solenoid valve may be sized such that the passage of the exhaust fluid through the solenoid valve may be constricted. The restricted flow of the exhaust fluid may create back pressure against seals  134  on spool  104  and/or may slow the operation of spool valve  100 . 
         [0030]    By switching the exhaust fluid into exhaust passageway  141  formed in spool valve  100 , the restriction of passing the exhaust fluid through the solenoid valve can be eliminated. This may increase the operational speed of spool valve  100  and/or may increase the life of seals  134 . Because the exhaust passageway  141  is part of spool valve  100 , the size of the exhaust passageway  141  can be optimized for the chamber size  136  and spool  104  movement. This may make the performance of the spool valve  100  independent of the type or size of the solenoid valve coupled to the spool valve. This invention is not limited to spool valves, but may include any type of fluid control device that requires venting of exhaust fluid through a signal port, for example poppet valves and cylinders. 
         [0031]      FIG. 2  is a cross sectional view of one end of spool valve  100  in an example embodiment of the invention.  FIG. 2  shows the fluid switch  113  in the end of spool valve  100  implemented as a poppet valve in an example embodiment of the invention.  FIG. 2   a  shows the poppet valve in the activated position and  FIG. 2   b  shows the poppet valve in the un-activated position. 
         [0032]    In the activated position, fluid is introduced into signal port  120 . The fluid forces poppet seal  250  to seal against exhaust passageway  141 . A flexible membrane  252  allows the fluid to pass around poppet seal  250  and enter signal passageway  139 . The fluid exits from the signal passageway  139  into chamber or cavity  136  and presses against the right side of spool  104 , moving spool  104  to the left. In the un-activated position, pressure is removed from signal port  120 . Spool  104  moves to the right, forcing the fluid in chamber or cavity  136  into signal passageway  139 . Flexible membrane  252  seals against right end  108 , forcing poppet seal  250  to move away from exhaust passageway  141 , and seal against signal port  120 . Exhaust fluid exits signal passageway  139  and is exhausted through exhaust passageway  141 . 
         [0033]    The example embodiments shown above use a poppet valve for the fluidic switches on each side of the spool valve, however other fluidic switches may be used in other example embodiments. Some examples of other types of fluid switches that may be used include a ball trapped in a passageway that moves between two positions (sometimes called a ball shuttle valve), a flapper type fluid valve, or the like.