Patent Abstract:
A tube defines a cavity. Normally-open fitting ( 2 ) and normally-closed fitting ( 3 ) are respectively fitted into the tube to form ports ( 34 ),( 35 ) having seats ( 40 ),( 13 ). A body secured to fitting ( 3 ) defines a chamber ( 26 ) to which port ( 35 ) leads. Body ( 4 ) defines holes ( 27 ),( 30 ) leading into chamber ( 26 ). A solenoid assembly ( 6 ) is slidable within chamber ( 26 ), includes a coil, segregates chamber ( 26 ) to chambers ( 7 ),( 29 ) which communicate respectively with holes ( 27 ),( 30 ) and defines a chamber ( 16 ), a seat ( 18 ), a seal ( 14 ) and an orifice ( 33 ) leading between seat ( 18 ) and seat ( 13 ). A rod-piston assembly includes a rod ( 37 ) attached to: assembly ( 6 ), sealably passing through body ( 4 ) into cavity and preventing gas communication between cavity and chamber ( 7 ); and a piston with a seal ( 39 ). A magnetic rod ( 15 ) slides within chamber ( 16 ). Spring ( 17 ) urges rod ( 15 ) towards seat ( 18 ) to seal orifice ( 33 ). Spring ( 12 ) urges assembly ( 6 ) towards seat ( 13 ) to seal port ( 35 ). The coil moves rod ( 15 ) and assembly ( 6 ). Assembly ( 6 ) and the rod-piston assembly are movable between positions wherein: the piston seals against seat ( 40 ); and wherein seal ( 14 ) seals against seat ( 13 ).

Full Description:
FIELD OF THE INVENTION 
   The primary application field of the invention relates to a solenoid valve and more particularly, to a three-way, two-position in-tube solenoid gas valve assembly to switch the gas passage in high pressure pneumatic system. 
   BACKGROUND OF THE INVENTION 
   Compared to hydraulic systems, pneumatic systems often have many disadvantages in different fields of applications in the present market. For example, the typical pressure range of hydraulic system is from 500 to 5,000 psig while a typical pneumatic system, the common pressure range from 0 to 80 psig, sometimes up to 1,000 psig for some special applications. However, there are reasons people would prefer a pneumatic system to a hydraulic one because of the simplicity of a pneumatic system which provides a low cost. In addition, a pneumatic system can be easily adapted to current applications and can be less sensitive to environmental factors. Since the hydraulic power system requires more complex conversion equipment which is not suitable for the portable or movable applications; hence, the demand of high pressure gas in pneumatic system is increasing. High pressure pneumatics can reach a higher stiffness than that of less pressure so that it provides a much stronger support than the low pressure system. The three-way solenoid valve of prior arts, U.S. Pat. No. 5,135,027 and 5,618,087, has been disclosed. In those inventions, the piston or ball is directly driven by a solenoid device that is actuated by an electrical signal to enable the system. However, those solenoid valves are not applicable in high pressure pneumatic system. There are also many poppet and spool type solenoid valves in the market. For example, in the prior art, U.S. Pat. No. 5,996,629, it has a movable spool (a valve body) which is driven by solenoid devices in a cylindrical chamber (a valve hole), communicating with several intersect channels, to switch the route of fluid passage. The gap distance between the spool and the chamber is very crucial. Normally, the surface of the spool has to be very smooth so that the gap distance can be controlled. The chamber and channels in a manifold are made by milling and subsequent finishing procedures. However, burrs are generated during machining procedure; hence, to clean all foreign material as well as burrs before assembling the valve is mandatory. Due to the inefficiency of the manual operation processes of cleaning and de-burring, the quality control of production of valve is dismal. In this invention, an innovative design, described hereafter, based on the prior art, U.S. patent application Ser. No. 10/924,789, in-tube solenoid gas valve, is a three-way, two-position solenoid valve assembly. This assembly consists of a modified in-tube solenoid gas valve and two additional gas release valves to reach a fast and reliable operation. In this design, a solenoid gas valve is used to control the direction of the flow while the movement of the pneumatic system is controlled by the pressure difference exerted by the high pressure gas. 
   SUMMARY OF THE INVENTION 
   Accordingly, it is an object of the present invention to provide a three-way, two-position in-tube solenoid gas valve assembly of the above mentioned general type which avoids the disadvantages of the prior arts. 
   It is also an object of the present invention to provide a three-way, two-position in-tube solenoid gas valve assembly that can be used for high pressure pneumatic system. 
   It is also an object of the present invention to provide a three-way, two-position in-tube solenoid gas valve assembly that will virtually act instantaneously. 
   It is also an object of the present invention to provide a three-way, two-position in-tube solenoid gas valve assembly that will save the manufacturing costs. 
   A three-way, two-position in-tube solenoid gas valve assembly according to the invention has an inlet in the valve tube located in the radial direction of a modified in-tube solenoid gas valve and two outlets at each end of the modified in-tube solenoid gas valve. An extend piston molded with plastic insert is connected to a solenoid assembly with a rod. The gas flow through one of the outlet to one side of a pneumatic system when the solenoid is not energized. When solenoid is energized, the solenoid assembly is moved by gas pressure differential force, to let gas flow to the other side of the pneumatic system at the meantime, the extend piston, pushed by the solenoid assembly, closes one of the outlet. There are two gas release valves that are used for releasing gas in the pneumatic system. When the supply gas flows to the acting side of the pneumatic system, the gas in the other side of the pneumatic system is pushed out by the piston and is released by one of the gas release valves. 
   The modified in-tube solenoid gas valve, as described in the prior art, U.S. patent application Ser. No. 10/924,789, having the characteristic function that open and close valve instantaneously, acts as the main component of this three-way, two-position in-tube solenoid gas valve assembly. The modified in-tube solenoid gas valve controls the flow direction of the gas into the pneumatic system. 
   A gas release valve comprises of a body piston and a cap piston, which are actuated by gas pressure from the outlets of the modified in-tube solenoid gas valve. The gas release valve helps the residue gas in the pneumatic system to escape. 
   The novel features which are considered as characteristics for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of a pneumatic system with a three-way, two-position in-tube solenoid gas valve assembly. 
       FIG. 2  is a cross-sectional view of a modified in-tube solenoid gas valve. 
       FIG. 3  is a cross-sectional view of a gas release valve. 
       FIG. 4  is a connection diagram of modified in-tube solenoid gas valve and two gas release valves in the state of no gas is in valves. 
       FIG. 5  is a connection diagram of modified in-tube solenoid gas valve and two gas release valves in the state that the gas starts to input into valves and the solenoid is de-energized. 
       FIG. 6  is a connection diagram of modified in-tube solenoid gas valve and two gas release valves in the state that the gas is in valves and the solenoid is energized. 
       FIG. 7  is a connection diagram of modified in-tube solenoid gas valve and two gas release valves in the state that the gas is in valves and the solenoid is de-energized again. 
   

   DESCRIPTION OF PREFERRED EMBODIMENT 
   Attention is first directed to  FIG. 1 , which shows a schematic diagram of a pneumatic system cylinder  104  having sides A and B is attached to a three-way, two-position, in-tube solenoid valve assembly, which consists of a modified in-tube solenoid gas valve  101  and two identical gas release valves  102  and  103 . Side A of cylinder  104  is connected to exiting port  34  of the modified in-tube solenoid gas valve  101 , port  47  of gas release valve  102  and port  55  of gas release valve  103 . Side B of cylinder  104  is connected to the existing port  35  of the modified in-tube solenoid gas valve  101 , port  55  of gas release valve  102  and port  47  of gas release valve  103 . 
     FIG. 2  shows a section view of a modified in-tube solenoid gas valve  101 . The valve tube  1  has a hollow hole with internal thread at both ends to accept both outlet fittings  2  and  3 . Both fittings have an exiting port  34  and  35  respectively with internal threads for connecting adaptive fittings of piping system. A gas input port  41  is located at a side of the valve tube  1  of the modified in-tube solenoid gas valve  101 . Cavity  22  is formed by the valve body  1 , the two outlet fittings  2  and  3 . 
   A support cylindrical body  4  having only one chamber  26  provides a space for the movement of a solenoid assembly  6  that comprises a hollow sleeve  8 , a stop  9 , flange  10  and an electrical coil  11 . The opening end of the cylindrical body  4  is connected to the outlet fitting  3  with pins  5 . An o-ring  28  on the outside of flange  10  divides chamber  26  into a front side chamber  7  and back side chamber  29 . A rod  37  with extended piston  38  connects the movable solenoid assembly  6 , and is supported by the cylindrical body  4 . A pair of o-ring  36  blocks the gas communication between chamber  26  and cavity  22 . A plastic insert  39  which is molded on extended piston  38  presses on a seal seat  40  of outlet fitting  2  to provide a seal. 
   A compression spring  12  pushes the solenoid assembly  6  to a seal seat  13  of the outlet fitting  3  at the initial state. A plastic insert  14  is molded onto the flange  10  to provide seal. A magnetic rod  15  moveable axially in hollow chamber  16  of hollow sleeve  8 , while a compression spring  17  pushes magnetic rod  15  against a interior orifice seal seat  18  of the flange  10  at the initial state. A rubber insert  19  is molded onto magnetic rod  15  to provide seal. 
   An internal pass-through plug  20 , inserting into support cylindrical body  4 , provides the strain relief of lead wires of coil  21  which extends from electrical coil  11 , through the support cylindrical body  4 , to the cavity  22  of the valve tube  1 . The lead wires of coil  21  are soldered onto the terminals of an external pass-through connector  23  at the bottom of connector  23 . The external pass-through connector  23  is placed in the outlet fitting  2  with an o-ring  24  that seals high pressure gas. Because of the high pressure in the valve tube  1 , a metal plug  25  with a centre hole is threaded into the outlet fitting to hold the external pass-through connector  23 . Lead wire  32  connects to lead wire of coil  21  and connects to a external power supply. 
     FIG. 3  displays a section view of a gas release valve which consists of a cap  56  with a body  46  threaded into the cap  56 . Cap  56  consists of a compression spring  42  and a cap piston  58  which movable within chamber  52  of the cap  56 . Cap  56  has through ports  43  to provide a gas outlet to the atmosphere. Body  46  consists of a body piston  57 , a compression spring  50  and an inlet fitting  51 . A contact surface between cap piston  58  and the threaded side of body  46  defines a sealing seat ( 45 ). Body piston  57  is moveable within chamber  54 . A pair of o-ring  49  prevents the communication of gas between chambers  53  and  54 . A port  47  is located at the side of the body  46  to provide a gas inlet. The inlet fitting  51  having a port  55  to provide gas inlet is threaded into body  46 . A gas communication groove  48  is for the connecting the port  47  and front body piston chamber. 
     FIG. 4  displays the entire assembly configuration that the pneumatic system is not being used. It also shows the initial state of the assembly. Initially, the solenoid is inactive and there is no gas flow into the modified solenoid gas valve  101 ; outlet fitting  2  is normally open; and outlet fitting  3  is normally closed. 
     FIG. 5  shows when the gas is allowed to flow into the modified solenoid gas valve  101 . Initially, the compression spring  17  pushes the magnetic rod  15  to seal bleed orifice  33  to port  35  and compression spring  12  pushes solenoid assembly  6  to seal gas to port  35 . Gas flows through the input port  41  of the modified in-tube solenoid gas valve  101  via cavity  22  and exiting through the port  34 . The exiting gas enters port  47  of gas release valve  102 , port  55  of gas release valve  103  and the side A of cylinder  104  simultaneously. In the pressure release gas valve  103 , the gas enters chamber  54  via port  55  and builds up the pressure in chamber  54 . The sum of forces of gas pressure in chamber  54  and compression spring  50  is greater that of compression spring  42 . Piston  57  pushes piston  58  to open valve. In gas release valve  102 , gas from input port  41  flows to chambers  53  and  59  via port  47  and port  34 . The force exerted by gas pressure in chambers  53  and  59  is greater than that of compression spring, so that, compression spring  50  is compressed and body piston  57  is separated from cap piston  58 . However, the force exerted by gas pressure in chambers  53  and  59  is less than that of compression spring  42 , and cap piston  58  remains to seal valve. In cylinder  104 , the exiting gas from modified in-tube solenoid gas valve  101  flows into side A of the system cylinder pushes the piston towards side B. The residue gas initially in side B of cylinder  104  is being “squeezed” out and enters the gas release valve  103  via port  47 . Because valve is open, the exiting gas from side B of cylinder  104  can escape through chamber  52  and port  43  to atmosphere. At this stage, while the solenoid remains inactive, the gas filled up the chambers  26 ,  16  and  29  via pass-through holes  27 ,  31  and  30 . Because the pressure between chamber  26  and chamber  29  is equal, with the action of the compression spring  12 , the modified in-tube solenoid gas valve remains closed. 
   When the solenoid in the modified in-tube solenoid gas valve  101  is active, as shown in  FIG. 6 , the bleed orifice  33  opens to allow gas in the front side chambers  7  and  16  to flow to the port  35 , and thus reduces the pressure in the front side chamber  7 . Because the pressure in the back side chamber  29  is greater than that of the front side chamber  7  , the valve opens. (For detailed operation, please refer to U.S. Ser. No. 10/924,789). Due to the movement of the solenoid assembly  6  in the modified in-tube solenoid gas valve  101 , piston  38  presses against seal seat  40  of outlet fitting  2  and thus closes port  34  and opens port  35 . When port  35  is open, incoming gas through port  41  enters cavity  22  and exits at port  35  via through-hole  30 . The exiting gas enters the port  55  of gas release valve  102 , port  47  of gas release valve  103  and side B of cylinder  104  simultaneously. In gas release valve  102 , the exiting gas from the modified in-tube solenoid gas valve  101  enters chamber  54  via port  55  and builds up the pressure in chamber  54 . Because the sum of the force created by gas pressure in chamber  54  and the force exerted by the compression spring  50  is larger than the force exerted by the compression spring  42  and by gas pressure in chamber  53 , piston  57  pushes piston  58  to move and opens valve. The gas in side A of cylinder  104  is released to atmosphere. Because chambers  54  and  53  are not communicating, the exiting gas from the modified in-tube solenoid gas valve remains in chamber  54 . The exiting gas enters chamber  59  of the pressure release valve  103  via port  47 . Because the force exerted by pressure in the chamber  53  and  59  is less than that of by the compression spring  42 , piston  58  remains unmoved. In cylinder  104 , the exiting gas from the modified in-tube solenoid gas valve enters the side B of the pneumatic system cylinder  104  causes the piston to move towards side A of the system cylinder. The gas that was in the side A of the system cylinder is being “squeezed” out into both pressure release valve  102  and  103 . Because the only pressure release valve  102  is open at the moment, the gas in side A of cylinder  104  vents out through port  47  and outlet port  43 . 
   When the solenoid is turned off, as shown in  FIG. 1 , the magnetic rod  15  moves back to block the bleed orifice  33 . As the gas fills the front side chambers  7  and  16 , the gas pressure between front side chamber  7  and back side chamber  29  is equalized, and by the act of compression spring  12 , the solenoid assembly  6  moves back to close port  35 . At the same time, it opens port  34 . Gas flows through port  41  and exiting through port  34  via cavity  22  into port  47  of gas release valve  102 , port  55  of gas release valve  103  and side A of cylinder  104 . In gas release valve  103 , the gas enters chamber  54  via the inlet  55 . The pressure build up in chamber  54  pushes the piston  57  which in turn pushes piston  58 . As a result of the movement of piston  58 , the valve is opened. The gas in the side B of cylinder  104  is released to atmosphere. In gas release valve  102 , gas enters chambers  59  and  53  via groove  48 . Since the force exerted by gas in the chambers  53  and  59  is greater than that by compression spring  50 , piston  57  is separated from piston  58 . Because the force exerted by the compression spring  42  is large enough to overcome the pressure build up in chambers  53  and  59 , piston  58  remains unmoved. no gas is escaping through gas release valve  102 . However, because chambers  54  and  59  are not in communication, exiting gas from port  34  of the modified in-tube solenoid gas valve  101  remains in the chamber  54 . The exiting gas from the modified in-tube solenoid gas valve  101  enters the side A of cylinder  104  which pushes the piston towards side B of the system cylinder. The gas that was in the side B of the system cylinder is then being “squeezed” out to the two gas release valves  102  and  103  and the port  35  of the modified in-tube solenoid gas valve  101 . Because the port  35  of the modified in-tube solenoid gas valve  101  is closed, the gas from side B of cylinder  104  can only flow to gas release valves  102  and  103 . However, since only gas release valve  103  has a route for venting the gas, via passage way  48  and port  43 , all gas eventually will exit through this route.

Technology Classification (CPC): 5