Abstract:
An electromagnetic flow control device, or valve is provided. The valve uses two sets of stationary electromagnetic windings, with corresponding movable electromagnetic cores, which are completely contained within the flow stream of the valve. The movable cores are connected to a valve needle which can seal against a seat or open. The device is powered by electromagnetic energy only.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of U.S. application Ser. No. 08/584,056 filed on Jan. 11, 1996, now U.S. Pat. No. 5,717,259. 
     The disclosure of the parent application, U.S. Ser. No. 08/584,056 is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates, generally, to devices for flow control, and particularly to flow control devices which can be remotely controlled. 
     2. Prior Art 
     Flow control devices are used in many industrial applications. Gate valves, ball valves, check valves, needle valves, and many other types of flow control devices are used in various industrial processes. A common configuration for a flow control device used in a industrial process is to have a flow control device located in a flow stream. The valve will include an actuator which is usually powered by compressed air. 
     The compressed air actuator on the valve will be activated by a control system which is electronically linked to a remote control station. This remote control station is usually a control room which monitors the process and controls the many flow control devices in the process. 
     There are two power systems necessary to run the conventional compressed air actuated valve. The first power system is the compressed air. Most petro-chemical facilities have a vast compressed air system running throughout the facility to supply compressed air to valve actuators and other equipment. The second power system is the electrical power system used for the electronic control system. 
     A disadvantage of compressed air actuators is that if power is lost to the actuator the valve will move to a default position, either open or closed. The inventors are not aware of actuator systems which leave the valve in the last known setting in the event that the compressed air supply is lost. Another disadvantage of compressed air actuators is that they require another piping infrastructure beyond the piping for the fluids used in the process. 
     Traditional control valves use a stem which traverses the casing of the valve. The section of the stem external to the valve is connected to the actuating mechanism. The section of the stem inside the valve is connected to a needle, ball, gate , disc, or some other structure which can be moved within the valve to control flow. 
     Regardless of the exact type of structure used in the control valve, a seal is used between the stem and casing. The goal of the seal (also known as packing) is to prevent leakage of the product in the pipe to the outside atmosphere. In applications involving negative pressure differentials, the seal prevents contamination of the product by the gases in the atmosphere. 
     There have been many advances in the field of flow control to improve seals. Improving the performance of seals is especially important in applications involving hazardous, corrosive, or toxic fluids. However, all of these advances in the seal do not change the basic configuration in which the stem is in contact with the product atmosphere, and moves (either vertically or by rotating) in relation to the casing. 
     What is needed is a flow control device which will eliminate the need for a seal between two moving parts so as prevent leakage of fluid to the atmosphere. What is also needed is a flow control device which does not require duplicate power systems. The flow control device should also be capable of remaining in the last known position if power to the flow control device is cut. 
     OBJECTS OF THE INVENTION 
     It is an object of the present invention to provide a flow control device which eliminates the need for seal between the valve stem and casing. 
     Another object of the present invention is to provide a flow control device which uses only one power source. 
     Another object of the present invention is to provide a flow control device which can operate without compressed air. 
     Another object of the present invention is to provide a device which will remain in the last set position if power to the device is cut. 
     SUMMARY OF THE INVENTION 
     An electromagnetic flow control device is provided. The flow control device includes a needle, a control system, a casing, and two electromagnetic machine sections which include windings and core sections. The electromagnetic machine sections are mirror images of each other. The machine sections and the needle are completely enclosed in the casing so that the fluid being controlled flows around the machine sections and the needle. In a preferred embodiment the machine sections and the needle have a channel filled with dampening fluid which flows from one machine section to the other as the needle moves. 
     An advantage of the electromagnetic flow control device is that there is no conventional valve stem which is exposed to both the fluid being controlled and the atmosphere. 
     A further advantage of the electromagnetic flow control device is that because there is no conventional valve stem, there is no need for a packing or sealing system to prevent leakage around the stem. 
     A further advantage of the electromagnetic flow control device is that it uses less power than valves which are actuated by a combination of compressed air with electronic control. 
     A feature of the flow control device is that it will remain in its last known setting even if power to the device is lost. 
     An additional feature of the flow control device is that it requires less maintenance than conventional valves. 
     An additional feature of the flow control device is that it eliminates the need for a compressed air piping system. 
     An additional feature of the flow control device is that it provides for smooth and accurate flow control. 
     These and other objects, advantages, and features of this invention will be apparent from the following descriptions of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a combined view of a preferred embodiment of the invention. The casing is shown as a sectional view while the remainder of the invention is shown as an elevation view. 
     FIGS. 2,  3 A, and  4  are sectional views of the left half section of the invention in various settings. 
     FIG. 2 shows the needle assembly of the invention in one of the closed positions. 
     FIG. 3A shows the needle assembly of the invention in the fully open position. 
     FIG. 3B shows is a sectional view of the core tube and core sections of the invention. 
     FIG. 4 shows the needle assembly of the invention in another of the closed positions. 
     FIG. 5 is a perspective view of the invention. A portion of the casing has been cut away to show one motive assembly and the needle assembly. 
     FIG. 6 is a combined view of the high-temperature embodiment of the invention. 
     FIG. 7 is a plan view of the invention, to include the electronic control assembly. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIGS. 1,  5 , and  7  a preferred embodiment of electromagnetic flow control device  100  is shown. Flow control device  100  will include casing  201 , motive assembly  301 , needle assembly  401 , and control assembly  501  (FIG.  7 ). In general, the following description lists only the parts contained in left half section  101  of flow control device  100 . Right half section  102  will include the same parts and those parts will perform the same function as will be described below. 
     FIGS. 2 through 4 show flow control device  100  in various settings. In FIG. 2 needle assembly  401  is set in one of the closed positions. It is believed by the inventors that this closed position shown in FIG. 2 is the preferred closed position for flow in the direction of Arrow A. 
     FIG. 3A shows needle assembly  401  in a fully open position. FIG. 4 shows needle assembly  401  in a second fully closed position. It is believed by the inventors that the closed position shown in FIG. 4 is the preferred closed position for flow which is opposite the direction of Arrow A. 
     FIGS. 2 through 4 depict the following components of left half section  101  of flow control device  100 . Outer casing  201  includes motive assembly casing  202  and needle assembly casing  203 . Motive assembly casing  202  is connected to needle assembly casing  203  by the use of needle assembly casing flange  204  and motive assembly casing first flange  205 . Motive assembly casing  202  is connected to the pipe in which flow control device  100  is installed by motive assembly casing second flange  205 . 
     Motive assembly  301  is held in place in the flowstream in motive assembly casing  201  by strut  302 . In one embodiment all sections of outer casing  201  are manufactured from stainless steel, as is strut  302 . Preferrably, strut is aerodynamically shaped so as to cause minimal disruption to the flow around motive assembly  301 . 
     Preferably, strut  302  is hollow or has passages within it which allow control wires  502  to pass from motive assembly  301  to the outside environment without being exposed to the product within the flowstream. Alternatively, one could run control wires  502  outside of strut  302 . Although only one strut  302  is shown, one could use a plurality of struts for extra stability. 
     Motive assembly  301  includes deflector cone  303 , winding sections  304 , and core sections  305 . Deflector cone  303 , while not required, is preferred so as to allow for the smooth flow of the product through flow control device  100 . Deflector cone  303  is rigidly connected to winding sections  304 . In the embodiment depicted, deflector cone  303  and winding sections  304  are integrated together within motive assembly shell  306 . Preferably, motive assembly shell  306  will be made of stainless steel. 
     To help contain the magnetic flux of winding sections  306 , they will preferably be surrounded not only by motive assembly shell  306 , but also by shielding layers  307  and  308 . Shielding layers  307 ,  308  can be manufactured of any material which has shielding characteristics. In a preferred embodiment an alloy with the following approximate proportions of elements is used: 80% nickel, 4.2% molybdenum, and the balance in iron. Such an alloy is available commercially from Carpenter Technology Corp. as “Carpenter HyMu 80®Alloy.” 
     Winding sections  304  are consist of wire wrapped around core tube  309 . Core tube  309  will be constructed of stainless steel or other metal with a permeability of as close to zero as possible. Molybdenum, copper, or any metal which is malleable, conducts electricity, and is heat resistant can be used for the wire in winding sections  304 . Each pair of control wires  502  for each winding are routed from motive assembly  301  out of motive assembly casing  202  via strut  302 . Each winding section  304  will be held in place and partitioned from the adjoining winding sections by winding partitions  310 . 
     In the embodiment depicted there are seven winding sections  304 . Those skilled in the art may want to vary the number of sections so as to have as few as two winding sections  304  or more than seven. Generally, the number of winding sections will be one less than the number of core sections  305 . The reason for this difference in number is that tail core section  402  of needle assembly  401  will act as the endmost core section and will correspond to the endmost winding section  304 . 
     Core sections  305  are cylindrical members made of a material with high permeability such as the molybdenum-nickel-iron alloy discussed above for shielding layers  307 ,  308 . Core section  305  nearest deflector cone  303  is rigidly fixed to core tube  309  so as to remain stationary. The remaining core sections  305  are allowed to slide within core tube  309  along long axis I of motive assembly shell  306 . 
     Core sections  305  are limited in their axial movement by core links which connect the core section to each other. As shown in FIG. 3B, each core section  305  will have female link  311  on the side towards needle assembly  401 . Each core section  305 , except for core section  305  nearest deflector cone  303 , will also include male link  312 . Each female link  311  and male link  312  will be integrated with or rigidly connected to its corresponding core section  305 . Tail core section  402  will also have a male link  312  integrated with it or rigidly attached to it. 
     The length of gap surfaces  313  shall be chosen to match each male link  312  and its corresponding connected female link  311 . In a preferred embodiment the length of gap surface  313  for core sections  305  nearest needle assembly  401  will be shorter than the length of gap surfaces  313  for core sections nearest deflector cone  303 . Varying the length of gap surfaces  313  in this manner will allow finer control of the settings at which needle assembly may be placed, and in turn very fine control of the flow of fluid through flow control device  100 . 
     Sealing section  403  of needle assembly  401  is sized so that it makes surface contact with the inner surface of core shell open end  314 . In a preferred embodiment sealing section  403  will include ring seat  404  and o-ring  405 . O-ring  404  may be made of any solid or resilient material which will provide a seal between fluid contained with motive assembly shell  306  and the fluid whose flow is being controlled. 
     In a preferred embodiment, the lengths of core sections  305 , tail core section  402 , gap surfaces  313 , and core tube open end  315  are chosen so that when core sections  305  are in the fully contracted position (as shown in FIG. 4) core sections  305  and tail core section  402  will be substantially adjacent to each other and the end of sealing section  403  of needle assembly  401  will be substantially adjacent to the winding partition  310  nearest needle assembly  401 . 
     Preferably, the lengths of core sections  305 , tail core section  402 , gap surfaces  313 , and core tube open end  315  are also chosen so that when the core sections are in the fully expanded position (as shown in FIG.  2 ), a portion of tail core section  402  will remain within core tube open end  315  and a portion of sealing section  403  will remain within motive shell open end  314 . 
     Each core section  305  includes core channel  316  and needle assembly  401  includes needle channel  406 . In a preferred embodiment all of the channels are aligned with each other and centered in core sections  305  and needle assembly  401 . Core channels  316  and needle channel  406  have a sufficient cross-section so that fluid contained within core tube  309  and motive shell open end  314  can move through the channels as the core sections  305  and needle assembly  401  move. 
     In a preferred embodiment core channels  316 , needle channel  406 , core tube  309 , and motive shell open  314  contain a dampening fluid. This dampening fluid will dampen the movement of the needle assembly  401  and core sections  305  and allow smoother control over the positioning of needle assembly  401 . In a preferred embodiment the dampening fluid will be hydraulic fluid. One could also simply allow air to serve as the dampening fluid. Alternatively, one could eliminate o-ring  405  and size sealing section  403  and motive shell open end  314  so that the fluid in the flow stream could enter into the channel and serve as the dampening fluid. 
     The spacing between core tube  309  and core sections  305  and tail core sections  402  can be designed so that dampening fluid can flow around those components. Alternatively, if one wanted a tighter fit between these components one could add radial channels (not shown). These radial channels would simply be holes placed in core sections placed perpendicular to core channels  316  and would allow dampening fluid to flow easier when core sections  305  moved. 
     In such an alternative embodiment it may be desirable to have an additional o-ring (not shown) placed between tail core section  402  and core tube  309 . Those skilled in the art may want to place bleeder holes through links  311 ,  312  to allow for the easier movement of dampening fluid as core sections  305  are moved. 
     In the closed position shown in FIG. 2, left needle mating portion  407  is in contact with needle casing left mating portion  408  so as to form a seal. In the fully open position shown in FIG. 3A, the fluid is free to flow around needle assembly  401 . In the second fully closed position shown in FIG. 4, right needle mating portion  409  is in contact with needle casing right mating portion  410 . 
     For ease of assembly, left needle portion  411  and right needle portion  412  are manufactured separately and are then joined together at junction  413  to form the completed needle assembly  401 . See FIG.  1 . 
     It is preferred that the dampening fluid be a liquid because liquids are substantially non-compressible. With a liquid as the dampening fluid, every movement of core sections  305  in left half section  101  of flow control device  100  will cause a reversed but otherwise mirror image movement of core sections  305  in right half section  102 . 
     FIG. 7 depicts the electronic control components which comprise control assembly  501 . Control wires  502  from winding sections  304  are grouped together for left half section  101  and right half section  102  and are routed to processor  504 . Flow sensor  503  can be any type of conventional sensor which detects the rate of flow just downstream or upstream of needle assembly  401 . Although in the embodiment depicted sensor  503  is located on a section of pipe joined to flow control device  100  one could also locate sensor  503  on flow control device  100  itself. 
     Control assembly  501  is a closed-loop feedback system. The operator will enter the desired flow rate into input device  505 . Input device  505  will send a corresponding desired flow rate signal to processor  501 . Processor  504 , upon receipt of the desire flow rate signal from input device  505 , will route the proper amount of current through each of the control wires  502 . 
     Sensor  503  will measure the rate at which the fluid being controlled is flowing through flow control device  100 . Upon measuring the actual flow rate, sensor  503  will send a corresponding actual flow rate signal to processor  504 . In some embodiments the signal will be amplified by an amplifier before being transmitted to processor  504 . Processor  504  will compare the actual flow rate signal received from sensor  503  to the desired flow rate signal received from input device  505 . 
     Preferably, control assembly  501  will use 9 volt DC power or some other type of DC power supply so that batteries can be used for backup power. In a particularly preferred embodiment, processor  504  will also include an oscillator which will pulse the DC signal to control wires  502 . Pulsing will allow for additional power savings and prevent excess heat build-up. 
     Once current corresponding to a particular setting is flowed into winding sections  304  winding sections  304  will remain magnetized even when the current is stopped. This ability of the device to remain in the last known position after the power is removed is one of the advantages of the invention. 
     If the operator desires to completely de-energize windings sections  304  the operator will enter this request into input device  505 . Processor  504 , upon receipt of the appropriate signal from input device  505 , will then cause a reverse polarity current to flow for only a very short period. This reverse polarity current will de-energize winding sections  304 . 
     FIG. 6 depicts an high temperature flow control device  601 . This alternate embodiment can be used in applications in which the fluid to be controlled is at a high temperature. In general, if motive assembly  301  is completely immersed in the main current of a flow stream of high temperature fluid it will be more difficult to maintain and operate flow control device  100 . High temperature flow control device  601  provides the advantages of the primary embodiment of FIG. 1 while protecting the motive assembly from the high temperature of the fluid being controlled. 
     The high temperature embodiment will still use motive assembly  301  (not shown). High-temp needle assembly  602  will include flow section  603  which has a smaller cross-section than plug sections  604  of high-temp needle assembly  602 . As with the conventional embodiment, high-temp needle assembly  602  will include needle channel  605 . 
     When high-temperature flow control device  601  is in the fully open position, flow section  603  will be aligned with transit openings  606 . When high-temperature flow control device  601  is in the fully closed position, one of the two plug sections  604  will block the flow of any fluid through transit openings  606 . One could also construct high-temperature device  601  so that the fluid could move around motive assembly  301 . Because motive assemblies  301  would still be perpendicular to the main flow, they would be protected from the worst effects of the heat transfer from the fluid being controlled. 
     There are of course other alternate embodiments which are obvious from the foregoing descriptions of the invention, which are intended to be included within the scope of the invention, as defined by the following claims.