Abstract:
A rising stem valve with a magnetic actuator having an outer and as inner magnet assembly that are magnetically coupled to each other so that the inner and outer magnet assemblies rotate together and a ball screw that is connected to the rising stem valve and that converts rotary to reciprocal motion. The inner magnetic cartridge assembly and valve body comprise a sealed lower section that is completely sealed to the outside environment.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Pursuant to 35 U.S.C. §119(e), this application claims priority back to U.S. Patent Application No. 62/080,289 filed on Nov. 15, 2014. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to the field of valves, and more specifically, to a rising (or reciprocating) stem valve that incorporates a ball screw mechanism and prevents leakage offend to the atmosphere. 
     2. Description of the Related Art 
     Attempts have bean made to provide leak-free protection for rising stem valves, which include gate, globe, knife and needle valves. Currently, metal bellows are employed around rising stems in these valves, especially when the valves are handling hazardous fluids. The bellows surround the stems and their associated packings to contain any leaks that penetrate through the packing assembly. Bellows, however, are not inherently leak-free because they eventually tail as metal fatigue begins to form cracks in the bellows. This kind of failure may result in a catastrophic release of hazardous fluid because when the bellows fails, the packing leaks without restraint. 
     An alternative, inherently leak-free technology is needed to replace bellows in places like chemical plants, refineries, paint factories, and cryogenic applications, where rising stem valves are integral to the functioning of the plant itself. This alternative technology must provide the advantage ox completely containing any leakage of fluids from valves. 
     A number of patent applications have been filed for valve actuators that mitigate stem leakage through the use of a magnetic interlock. These actuator chambers either enclose the dynamic seal that is present in every valve around the stem of the valves or eliminate the need for the seal entirely. This dynamic seal is known as a packing or mechanical seal. The magnetic interlock is employed to transmit force from the outside to the inside of the actuator chamber, thus avoiding the penetration of the chamber wall by a mechanical stem actuator. Penetration of the chamber wall would nullify the purpose tor the chamber in the first place—to enclose the dynamic seal around the stem and prevent leakage from the seal. 
     The problem with various proposed magnetic actuators is that the amount of force transmitted by the magnets is not adequate to ensure the proper function of the valve. If an actuator is designed to provide adequate force to open and close the valve, the magnet coupling is so large as to make it impractical. Even with the use of modern rare-earth magnets such as Neodymium Iron Born and Samarium Cobalt, the ability to transmit adequate force to the valve stem is still difficult. The forces provided by the magnets are only a fraction (usually less than 20%) of the force that a mechanical stem actuator can provide. This does not give the valve operator the confidence that his valve can be opened or closed under situations where high force is required, such as high fluid pressure, dry seals, or debris in the fluid path. 
     Rather than increasing force by building ever larger magnetic couplings, the present invention incorporates a ball screw assembly that multiplies the force supplied by the inner magnetic coupling while at the same time converting that force from rotary to reciprocal motion. For example, a torque of 120 in-lbs. can be converted to an axial force of 2000 lbs. or more by using a typical 0.75″ ball screw with a lead of 0.5″, the lead being the distance that the screw moves axially with each full rotation of the ball nut. This allows the use of a much smaller magnetic coupling. The reduction in size is desirable because the magnetic coupling is the most expensive component of the actuator. 
     Through the incorporation of a ball screw subassembly, the present invention provides a magnetically activated valve actuator that can be used in the harshest conditions. Magnetic actuation is no longer appropriate for light applications only. Rather, it is a robust alternative that provides force to the stem that is equivalent to that of low- and medium-pressure dynamically sealed stemmed valves. This innovation is most needed in places like chemical plants, refineries, and pipelines where valves are the central workhorses of the plant or pipeline. 
     In addition to increasing force and/or decreasing the size of the magnetic coupling, the present invention has the advantage of completely containing any leakage of fluids from the valve bonnet. The present invention is intended to be coupled to valves that are used in hazardous fluid or chemical applications, where stem leakage poses a pollution threat to the outside environment or a safety threat to personnel working nearby. At the very least, leakage from stem packings results in the loss of product, which can be costly. Fugitive emissions account for over 125,000 metric tons of lost product per year in the United States alone. Of this amount, the percentage of fugitive emissions that come from valve stems is estimated to be between 60% and 85%. 
     The threat posed to the environment by leaking valve stems is great, particularly when the product that is leaked is a fugitive emission, that is, a leaked or spilled product that cannot be collected back from the environment. An example of a fugitive emission would be methane leaking from a valve on a pipeline or in a refinery, in which case the methane immediately goes into the atmosphere and cannot be recaptured. Another example would be crude oil leakage from a valve on an offshore rig, where the oil is earned away by ocean currents and cannot be recovered. 
     Safety requirements are becoming more stringent with each passing year. Personnel who are required to work near hazardous chemicals—such as operators in a petrochemical plant—are subject to injury from leaking valve stems, especially from reciprocating stems where the hazardous material inside the valve is transported to the outside environment via the stem as it retracts from the valve body. For example, if the valve is handling chlorine, a leaking stern transports it to the outside environment, where it becomes hydrochloric acid when it reacts with moisture in the air. This acid corrodes the stem, which makes it even more difficult to seal over time. 
     The magnetic actuator of the present invention safely encloses the stem of all reciprocating stemmed valves because it is able to transfer torque through the enclosure magnetically without physically penetrating the enclosure itself. Magnetic actuators have been proposed previously for rotating stem valves. For these devices, the torque is magnified inside of the actuator chamber by the use of a worm gear or a planetary gear set. In the case of rising stem valves, however, the torque must also be converted to reciprocal motion. The present invention proposes the use of a ball screw, which not only magnifies the force of the magnetic actuator, but also converts the rotary motion to reciprocal motion. 
     Currently, ball screws are being used to actuate high-pressure gate and globe valves where large forces are required to move the valve stem up and down. For example, in a high-pressure, ASME Class #2500 gate valve, the fluid pressure on one side of the gate may be in the range of 5,000 psi, pushing the gate against the downstream valve seat with several tons of force. To lift the gate, the stem must provide as much as 20,000 lbs. or more of lifting force. 
     Ball screws and helical spline actuators are employed in high-pressure, self-contained hydraulic, electric, or pneumatic actuators, where the actuation force is transferred into the sealed chamber or outer casing by means of electrical wires, hydraulic fittings, or pneumatic fittings. The hundreds or thousands of ft-lbs. of torque required to move these valve stems cannot be transferred magnetically in a practical way; therefore, it has not been obvious that magnetic couplings could ever be coupled to ball screws to actuate rising stem valves. Instead, the automated versions of these valves are self-contained; that is, the mechanical energy required to actuate these valves is provided internally by hydraulic, electric, or pneumatic means. 
     The present invention cannot be used tor the applications described above for the reasons stated; however, it can be used for low- and medium-pressure applications known as ASME class #150, #300, and #600 valves. The ball screw specified in the present invention is much smaller in diameter than those currently being used to actuate high-pressure valves. This accomplishes three things: (1) the lower torque requirement allows the use of magnetic actuation rather than self-contained power (that is, the transfer of torque through the sealed chamber by means of a magnetic coupling is now possible); (2) the smaller diameter ball screw allows for more room for the inner magnetic cartridge, making it possible to consider high-temperature Alnico magnets tor use at temperatures up to 950 degrees Fahrenheit; and (3) the mechanical advantage provided by the smaller diameter ball screw (i.e., the ratio of reciprocal force over supplied torque) is much greater than that of the larger high-pressure ball screws when given the same amount of axial travel (or lead) per rotation. (A larger diameter screw has a larger circumference per rotation, which results in a greater axial movement per rotation than with a smaller screw that has the same lead angle. Thus, the smaller screw must have a steeper lead angle in order to supply the same amount of axial travel per rotation as a larger diameter screw. A steeper lead angle increases the efficiency of the screw when converting rotary motion to reciprocal motion.) These advantages are not present in any of the prior art valves that utilize a magnetic actuator. 
     Examples of valve designs involving magnetic actuators include: U.S. Pat. No. 3,908,959 (Fichtner, 1975); U.S. Pat. No. 4,284,262 (Ruyak, 1981); U.S. Pat. No. 4,296,912 (Ruyak, 1981); U.S. Pat. No. 4,327,892 (Ruyak, 1982); U.S. Pat. No. 4,382,578 (Ruyak, 1983); U.S. Pat. No. 4,384,703 (Ruyak et al., 1983); U.S. Pat. No. 4,671,486 (Giannini, 1987); U.S. Pat. No. 5,039,061 (Heard et al., 1991); U.S. Pat. No. 5,129,619 (Castetter, 1992): U.S. Pat. No. 5,129,620 (Castetter, 1992); U.S. Pat. No. 5,372,351 (Oliver, 1994); U.S. Pat. No. 8,297,315 (Esveldt, 2012); U.S. Pat. No. 8,490,946 (Burgess et al., 2013); U.S. Pat. No. 8,496,228 (Burgess et al., 2013); and U.S. Pat. No. 8,690,119 (Burgess et al., 2014). An example of an attempt to solve the problem of providing a leak-proof valve for cryogenic applications is U.S. Pat. No. 5,356,112 (Simar et al., 1994). An example of a valve that converts rotary motion to linear (reciprocating) motion is U.S. Pat. No. 7,325,780 (Arai et al., 2008). An example of a gate valve that utilizes a motorized ball screw actuator is U.S. Patent Application Pub. No. 2011/0308619 (Martino et al.). 
     BRIEF SUMMARY OF THE INVENTION 
     A rising stem valve comprising: a pneumatic actuator assembly comprised of a pneumatic actuator, an upper ball nut, and a ball nut mount, wherein the upper ball nut threads into a bottom end of the ball nut mount, and the ball nut mount threads into a pneumatic piston, the upper bah nut being configured to move up and down with the pneumatic piston; a valve body comprised of a top flange; a gate assembly with a lower ball screw, a gate mount and a gate, wherein a bottom end of the lower ball screw resides within the gate mount, and a lower portion of the gate mount is inserted into a guide channel in the gate; an inner magnetic cartridge assembly comprised of a magnet housing and an inner magnetic cartridge, wherein the inner magnetic cartridge is comprised of an inner magnet carrier around which a plurality of inner magnets are arranged radially and spaced apart from one another, and wherein the inner magnetic cartridge resides within the magnet housing; an outer magnetic assembly comprised of an outer magnet carrier and an outer magnet top that is fixedly secured to the outer magnet carrier, a plurality of outer magnets held within the outer magnet carrier, the outer magnets being magnetically coupled to the inner magnets so that when the outer magnets rotate, the inner magnets rotate in a same direction; and an upper ball screw with a top end that threads into the upper ball nut so that the upper ball screw rotates as the ball nut moves linearly up and down, and a bottom part that is coupled to the outer magnet top so that the outer magnet top rotates with the upper ball screw; wherein the gate assembly is contained within the valve body, and the inner magnetic cartridge assembly and valve body comprise a sealed lower section that is completely sealed to an outside environment; wherein the outer magnetic assembly is secured to the scaled lower section; wherein the magnet housing is fixedly attached to the top flange of the valve body; wherein an inner ball nut is locked rotationally to the inner magnet carrier; and wherein the inner ball nut is configured to cause the lower ball screw to move linearly up and down within the valve body as the inner ball nut rotates. 
     In a preferred embodiment, the inner magnets are situated within channels in the inner magnet carrier. Preferably, the inner magnetic cartridge assembly further comprises a spacer that abuts up against a bottom surface of the inner magnet carrier, and a spring ring that is situated on an upper surface of the spacer between the spacer and the inner magnet carrier. A first upper tapered roller bearing is preferably situated inside of the magnet housing directly underneath a ceiling of the magnet housing. A first lower tapered roller bearing is preferably situated inside of the magnet housing between the spacer and a compression nut. 
     In a preferred embodiment, the spacer is configured to rotate along with the inner ball nut and the inner magnet carrier. Preferably, the outer magnetic assembly further comprises a second upper tapered roller bearing and a second lower tapered roller bearing, the second upper tapered roller bearing being situated inside a bottom end of the outer magnet top and the second lower tapered roller bearing being held in a recess on an inside of the outer magnet carrier. The second upper tapered roller bearing preferably comprises an outer raceway that is constrained by the outer magnet top and an inner raceway that is constrained by the magnet housing, and the second lower tapered roller bearing preferably comprises an outer raceway that is constrained by the magnet housing and an inner raceway that is constrained by the magnet housing. 
     In an alternate embodiment, the present invention is a rising stem valve comprising: a manual actuator assembly comprised of a handle assembly and a manual actuator mount assembly; a valve body comprised of a top flange; a gate assembly with a lower ball screw, a gate mount and a gate, wherein a bottom end of the lower ball screw resides within the gate mount, and a lower portion of the gate mount is inserted into a guide channel in the gate; an inner magnetic cartridge assembly comprised of a magnet housing and an inner magnetic cartridge, wherein the inner magnetic cartridge is comprised of an inner magnet carrier around which a plurality of inner magnets are arranged radially and spaced apart from one another, and wherein the inner magnetic cartridge resides within the magnet housing; and an outer magnetic assembly comprised of an outer magnet carrier and an outer magnet top that is fixedly secured to the outer magnet carrier, a plurality of outer magnets held within the outer magnet carrier, the outer magnets being magnetically coupled to the inner magnets so that when the outer magnets rotate, the inner magnets rotate in a same direction; wherein the outer magnet top is configured to rotate as the handle assembly rotates; wherein the gate assembly is contained within the valve body, and the inner magnetic cartridge assembly and valve body comprise a sealed lower section that is completely sealed to an outside environment; wherein the outer magnetic assembly is secured to the sealed lower section; wherein the magnet housing is fixedly attached to the top flange of the valve body; wherein an inner ball nut is locked rotationally to the inner magnet carrier; and wherein the inner ball nut is configured to cause the lower ball screw to move linearly up and down within the valve body as the inner ball nut rotates. 
     In a preferred embodiment, the inner magnets are situated within channels in the inner magnet carrier. Preferably, the inner magnetic cartridge assembly further comprises a spacer that abuts up against a bottom surface of the inner magnet carrier, and a spring ring that is situated on an upper surface of the spacer between the spacer and the inner magnet carrier. A first upper tapered roller bearing is preferably situated inside of the magnet housing directly underneath a ceiling of the magnet housing. A first lower tapered roller bearing is preferably situated inside of the magnet housing between the spacer and a compression nut. 
     In a preferred embodiment, the spacer is configured to rotate along with the inner ball nut and the inner magnet carrier. Preferably, the outer magnetic assembly further comprises a second upper tapered roller bearing and a second lower tapered roller bearing, the second upper tapered roller bearing being situated inside a bottom end of the outer magnet top and the second lower tapered roller bearing being held in a recess on an inside of the outer magnet carrier. The second upper tapered roller bearing preferably comprises an outer raceway that is constrained by the outer magnet top and an inner raceway that is constrained by the magnet housing, and the second lower tapered roller bearing preferably comprises an outer raceway that is constrained by the outer magnet carrier and an inner raceway that is constrained by the magnet housing. 
     In one embodiment, the handle assembly comprises a handle and a key, and the key fits into a first keyway in a center hole of the handle and a second keyway in the outer magnet top. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the present invention fully assembled with a pneumatic actuator. 
         FIG. 2  is a perspective view of the valve body and gate assembly. 
         FIG. 3  is a perspective view of the lower ball screw and gate assembly. 
         FIG. 4  is an exploded view of the lower ball screw and gate assembly. 
         FIG. 5  is an exploded view of the inner magnetic cartridge assembly. 
         FIG. 6  is an exploded view of the inner magnetic cartridge. 
         FIG. 7  is a section view of the inner magnetic cartridge assembly. 
         FIG. 8  is a section view of the inner magnetic cartridge assembly with relief gap. 
         FIG. 9  is a perspective view of the sealed lower section with valve body and inner magnetic cartridge assembly. 
         FIG. 10  is a section view of the sealed lower section with valve body and inner magnetic cartridge assembly shown with the valve closed. 
         FIG. 11  is a section view of the sealed lower section with valve body and inner magnetic cartridge assembly shown with the valve open. 
         FIG. 12  is a perspective view of the outer magnetic assembly. 
         FIG. 13  is an exploded view of the outer magnetic assembly. 
         FIG. 14  is a section view of the outer magnetic assembly. 
         FIG. 15  is a perspective view of the sealed lower section with valve body and outer magnetic assembly. 
         FIG. 16  is a perspective view of the pneumatic actuator mounting assembly. 
         FIG. 17  is an exploded view of the pneumatic actuator mounting assembly. 
         FIG. 18  is a section view of the pneumatic actuator mounting assembly. 
         FIG. 19  is a top view of the magnetic coupling between the outer magnetic assembly and the inner magnetic cartridge assembly. 
         FIG. 20  is a perspective view of the pneumatic actuator assembly. 
         FIG. 21  is an exploded view of the pneumatic actuator assembly. 
         FIG. 22  is a top section view of the pneumatic actuator rotational stop. 
         FIG. 23  is an exploded view of the present invention with the pneumatic actuator. 
         FIG. 24  is a section view of the present invention shown with the valve in an open position. 
         FIG. 25  is a section view of the present invention shown with the valve in a closed position. 
         FIG. 26  is a perspective view of the present invention fully assembled with a manual actuator. 
         FIG. 27  is an exploded view of the present invention with the manual actuator. 
         FIG. 28  is an exploded view of the manual actuator mount assembly. 
         FIG. 29  is a section view of the manual actuator mount assembly. 
         FIG. 30  is an exploded view of the manual actuator handle. 
         FIG. 31  is a section view of the valve body showing the interaction between the valve gate guide channel and valve gate guide. 
         FIG. 32  is a section view of the outer magnetic assembly and sealed lower section. 
     
    
    
     REFERENCE NUMBERS 
       6  Pneumatic actuator assembly 
       7  Pneumatic actuator mount assembly 
       8  Outer magnetic assembly (pneumatic actuator) 
       9  Inner magnetic cartridge assembly 
       10  Gate assembly 
       11  Valve body 
       11   a  Left flange (of valve body) 
       11   b  Right flange (of valve body) 
       11   c  Central portion (of valve body) 
       11   d  Top flange (of valve body) 
       12  Inner magnetic cartridge 
       13  Manual actuator mount assembly 
       14  Handle assembly 
       15  Outer magnetic assembly (manual actuator) 
       20  Upper tapered roller bearing 
       22  Inner ball nut 
       23  Spring ring 
       24  Lower tapered roller bearing 
       25  Lower ball screw 
       26  Gate mount 
       27  Lock pin 
       28  Gate 
       29  Upper ball screw 
       30  Set screw 
       33  Spring washer 
       34  Upper tapered roller bearing 
       35  Snap ring 
       36  Lower tapered roller bearing 
       37  Pneumatic actuator 
       38  Upper ball nut 
       39  Handle 
       40  Snap ring 
       41  Key 
       42  Washer 
       43  Retaining bolts 
       44  Bolt 
       45  Cylinder bead bolt 
       46  Set screw 
       47  Set screw 
       60  Magnet housing 
       61  Inner magnets 
       62  Inner magnet carrier 
       63  Spacer 
       64  Compression nut 
       65  Compression jam nut 
       66  Outer magnet top 
       67  Retaining cap 
       68  Outer magnet carrier 
       69  Outer magnets 
       70  Ball nut mount 
       71  Mount can top (pneumatic actuator) 
       72  Mount can divider 
       73  Mount can (pneumatic actuator) 
       74  Retaining ring 
       75  Mount can top (manual actuator) 
       76  Alternate embodiment of mount can (manual actuator) 
       101  Relief gap 
       104  Valve gate guide channel 
       105  Valve gate guide 
       108  Sealed lower section 
       111  Pneumatic shaft guide 
       112  Clamp-on guide 
       117  Shoulder (of mount can) 
       118  Key way 
       120  Pneumatic piston 
       150  Channel (in inner magnet carrier) 
       151  Bolts 
       152  Nuts 
       153  Channel (in outer magnet carrier) 
       155  Guide rollers 
       157  Bolt holes 
       158  Flange gasket 
       160  Keyway 
       161  Set screw hole 
       163  Bolt holes 
       164  Groove 
     DETAILED DESCRIPTION OF INVENTION 
       FIG. 1  is a perspective view of the present invention fully assembled with a pneumatic actuator. This figure shows the major parts of the invention, namely, the pneumatic actuator  37 , pneumatic actuator assembly  6 , pneumatic piston  120 , ball nut mount  70 , pneumatic actuator mount assembly  7 , mount can  73 , magnet housing  60 , and valve body  11 . As shown in the figures, the magnet housing  60  serves as a barrier between the inner and outer magnets  61 ,  69  of the magnetic actuator (see, in particular,  FIG. 19 ). All of these parts are described more fully below. 
       FIG. 2  is a perspective view of the valve body and gate assembly. As shown in this figure, the gate assembly  10  is situated within the valve body  11 . The valve body  11  is comprised of a left and right flange  11   a ,  11   b  and a central portion  11   c  situated between the two flanges. The gate assembly  10  is comprised of a lower ball screw  25 , a gate mount  26 , and a gate  28  (as well as set screw  27  shown in  FIG. 4 ). The gate assembly  10  is further comprised of a valve gate guide channel  104  and a valve gate guide  105 . In a preferred embodiment, the ball screw  25  is Part No. S5-016100L-305/280-D(3)B-Y/N manufactured and distributed by Heli-Tek of Muskego, Wis. The ball screw  25  is preferably comprised of grade 5 stainless steel and is seven inches long with a diameter of 16 mm and a 10 mm lead, left helix; the helix is preferably ground as opposed to rolled. In a preferred embodiment, the upper ball screw  29  is the same part as the lower ball screw  25  except with respect to length; the upper hail screw  29  is preferably 8.25 inches long. In alternate embodiments, the lead of the upper ball screw  29  may be different than the lead of the lower ball screw  25  in accordance with the requisite torque load. 
     This high lead angle screw is also used in the pneumatic piston actuator shown in  FIG. 12 . In this application, the same high lead angle ball screw is used to convert linear motion to rotary motion in order to power the driver magnet cartridge. Because the exact same ball screw is preferably used prior to the magnetic coupling as well as after the magnetic coupling, the axial motion produced by the pneumatic cylinder is replicated exactly by the motion supplied to the gate valve. This makes it easy for a technician to calibrate the proper stroke for a given gate valve, knowing that the stroke supplied from the pneumatic cylinder is identical in length to the stroke inside of the valve. 
       FIG. 3  is a perspective view of the lower ball screw and gate assembly. The gate assembly  10  comprises the lower ball screw  25 , the bottom end of which resides within the gate mount  26 . The lower portion of the gate mount  26  is inserted into a guide channel  104  in the gate  28 . 
       FIG. 4  is an exploded view of the lower ball screw and gate assembly. As shown in this figure, a lock pin  27  secures the bottom end of the lower ball screw  25  in the gate mount  26 . The bottom portion of the gate mount  26  slides into the recess shown in the guide channel  104  at the front of the gate  28 . 
       FIG. 5  is an exploded view of the inner magnetic cartridge assembly. As shown in this figure, the inner magnetic cartridge assembly  9  is comprised of a magnet housing  60 , an upper tapered roller bearing  20 , and the inner magnetic cartridge  12 . It is further comprised of an inner ball nut  22 , spring ring  23 , spacer  63 , lower tapered roller bearing  24 , compression nut  64  and compression jam nut  65 . These pieces fit together, as shown, to form the inner magnetic cartridge assembly  9 . 
       FIG. 6  is an exploded view of the inner magnetic cartridge. The inner magnetic cartridge  12  is comprised of an inner magnet carrier  62  around which the inner magnets  61  are arranged radially and spaced apart from one another so that no two magnets  61  are in contact with one another. The inner magnets  61  are situated within inner magnet channels  150  in the inner magnet carrier  62 . The inner magnet carrier  62  preferably comprises a set screw hole  161  into which a set screw  30  is inserted. This set screw  30  ensures that the ball nut  22  (see  FIG. 10 ) does not rotate. 
       FIG. 7  is a section view of the inner magnetic cartridge assembly. This figure shows the magnet housing  60 , as well as the spacer  63 , compression nut  64  and compression jam nut  65 . The spacer  63  allows access to the ball nut  22 , and it also provides a mounting surface for the spring ring  23 . The spacer  63  also serves to lower the surface upon which the lower tapered roller bearing  24  is acting. The compression nut  64  enables tightening of all of the parts contained within the magnet housing  60 , and the compression jam nut  65  ensures that the compression nut  64  does not slip. A spring ring  23  is situated on an upper surface of the spacer  63 , as shown, between the spacer  63  and the inner magnet carrier  62 . A lower tapered roller bearing  24  is situated inside of the magnet housing  60  between the compression nut  64  and the spacer  63 ; the lower tapered roller bearing holds the spacer  63 , inner ball nut  22  and inner magnet carrier  62  concentrically within the magnet housing  60 . An upper tapered roller bearing  20  is situated inside of the magnet housing  60  directly underneath the ceiling of the magnet housing  60 ; its purpose is to provide a counterforce to the lower tapered roller bearing  24  and maintain the spacer  63 , inner ball nut  22  and inner magnet carrier  62  concentric within the magnet housing  60 . As the gate  28  and ball screw  25  move upward, force is exerted on the upper tapered roller bearing  20 . Similarly, as the gate  28  and ball screw  25  move downward, force is exerted on the lower tapered roller bearing  24 . The upper and lower tapered roller bearings  20 ,  24  work together to maintain the concentricity of the parts located within the magnet housing  60 . Note that the angle of the upper tapered roller bearing  20  is opposite that of the lower tapered roller bearing  24 . 
       FIG. 8  is a section view of the inner magnetic cartridge assembly with relief gap. In  FIG. 7 , the spring ring  23  is compressed; in  FIG. 8 , on the other hand, the spring ring  23  has been uncompressed, which creates a gap  101  between a bottom surface of the inner magnet carrier  62  and the spacer  63 , as shown. (Note that the degree of tightening of the compression nut  64  determines the magnitude of this gap  101 .) The purpose of this gap  101  is to allow for thermal expansion of the spacer  63 , inner ball nut  22  and inner magnet carrier  62  in certain high-temperature applications. 
       FIG. 9  is a perspective view of the sealed lower section with valve body and inner magnetic cartridge assembly. This figure shows the magnet housing  60  and the bolts  151  and nuts  152  that secure the magnet housing  60  to the flange  11   d  on top of the valve body  11 . Note that the sealed lower section  108  is completely sealed to the outside environment. 
       FIG. 10  is a section view of the sealed lower section with valve body and inner magnetic cartridge assembly shown with the valve closed. The inner magnet carrier  62  and inner magnets  61  reside inside of the magnet housing  60 . The outer magnets  69  are not shown in this figure, but as they rotate, the magnetic coupling between the outer and inner magnets  69 ,  61  causes the inner magnets  61  (and, therefore, the inner magnet carrier  62 ) to rotate in the same direction as the outer magnets  69 . The inner magnet carrier  62  is fixedly attached to the inner ball nut  22  so that the inner ball nut  22  also rotates with the outer magnets  69 . The ball nut  22  is locked rotationally to the inner magnet carrier  62  via the set screw  30 . The inner ball nut  22  converts the rotary motion of the inner magnet carrier  62  to a reciprocating motion. As the inner ball nut  22  rotates, it causes the ball screw  25  to move linearly up and down within the valve body  11  and magnet housing  60 . The gate  28 , gate mount  26  and ball screw  25  (in other words, all parts shown in  FIG. 3 ) move together (up and down) as a single unit. 
     When the inner ball nut  22  and inner magnet carrier  62  rotate, the spacer  63  also rotates. The spacer  63  comprises a neck that slips into the bottom of the inner magnet carrier  62  (see  FIG. 8 ). The compression nut  64  puts pressure on both the inner magnet carrier  62  and the spacer  63 , which forces them to rotate together. The ball screw  25  moves up or down, depending on the direction of rotation of the inner magnet carrier  62 . The flange gasket  158 , which is situated between the bottom flange of the magnet housing  60  and the upper flange  11   c  of the valve body, prevents fluid from escaping between the magnet housing  60  and the valve body  11 . The valve gate guide  105  that was shown in  FIG. 1  is also shown in this figure. The valve gate guide  105  prevents the gate  28  from rotating, thereby ensuring that the gate  28  moves only up or down within the valve body  11 . The valve gate guide channel  104  in the gale  28  (see also  FIG. 2 ) receives the valve gate guide  105 , which extends inward in two parts on opposite sides of the central portion  11   c  of the valve body.  FIG. 31  shows in greater detail the relationship between the valve gate guide channel  104  and the valve gate guide  105 . 
       FIG. 11  is a section view of the sealed lower section with valve body and inner magnetic cartridge assembly shown with the valve open. The same parts are shown as in  FIG. 10 , except that the lower ball screw  25  has been moved upward by virtue of the rotation of the inner ball nut  22 , thereby causing the gate  28  to move upward as well. 
       FIG. 12  is a perspective view of the outer magnetic assembly. As shown in this figure, the outer magnet top  66  (more specifically, the bottom flange of the outer magnet top) is secured to the top of a cylindrical outer magnet carrier  68  with cylinder head bolts  45 . As shown in greater detail in  FIG. 13 , the outer magnet top  66  is comprised of a cylindrical top part, a bottom flange with a protruding base, and a skirt section that joins the cylindrical top part to the bottom flange. The bottom part of the upper ball screw  29  is inserted into a central threaded hole in the outer magnet top  66  and secured with a set screw  46 . This set screw  46  ensures that the upper ball screw  29  does not rotate independently of the outer magnet top  66 . 
       FIG. 13  is an exploded view of the outer magnetic assembly. This figure shows the outer magnetic assembly  8 , which rotates as a single unit. The bottom end of the ball screw  29  threads into the outer magnet top  66  and is secured with set screw  46 . The outer magnet top  66  comprises a keyway  118 , which receives the key  41  shown in  FIG. 30 ; note that this particular part (the keyway  118 ) is relevant only in connection with the manual actuation embodiment shown in  FIGS. 26-30 . The outer magnet top  66  is bolted to the outer magnet carrier  68 . A snap ring  35  is situated inside of the outer magnet top  66  (see also  FIG. 14 ). To assemble the unit, the bolt  44 , spring washer  33 , retaining cap  67  and upper tapered roller bearing  34  are compressed together and inserted into the bottom of the outer magnet top  66 . The snap ring  35  is inserted into a groove in the interior of the outer magnet top  66  to maintain these parts in place. The bolt  44  fastens the outer magnetic assembly  8  to the sealed lower section  108  (see  FIG. 32 ). The outer magnets  69  are slipped inside of the outer magnet carrier  68  and held in place by magnetic force. Note that there are grooves inside of the outer magnet carrier  68  for receiving the outer magnets  69  (see  FIG. 19 ). The lower tapered roller bearing  36  slides into the bottom of the outer magnet carrier  68  and into a recess on the inside of the outer magnet carrier  68  (see  FIG. 14 ). 
       FIG. 14  is a section view of the outer magnetic assembly. Channels  153  on the inside of the outer magnet carrier hold the outer magnets  69  inside of the outer magnet carrier  68 . In this figure, the channels  153  are longer than the magnets themselves  69 ; this is to accommodate longer magnets if greater torque is desired. Bolt  45  attaches the outer magnet top  66  to the outer magnet carrier  68 . Tightening of bolt  44  ensures that the outer magnetic assembly  8  is concentric on the lower sealed section  108 . The bolt  44  is preferably secured to the sealed lower section  108  with some manner of thread lock. The purpose of the upper and lower tapered roller bearings  34 ,  36  is to hold outer magnetic assembly  8  concentric to the magnet housing  60 . Note that the outer magnet carrier  68  is constraining the outer race way of the lower tapered roller bearing  36 , and the magnet housing  60  is constraining the inner raceway of the lower tapered roller bearing  36 . The inner raceway of the upper tapered roller bearing  34  is constrained by the magnet housing  60 , and the outer raceway of the upper tapered roller bearing is constrained by the outer magnet top  66 , which is concentrically and fixedly attached to the outer magnet carrier  68 . 
       FIG. 15  is a perspective view of the sealed lower section with valve body and outer magnetic assembly. In this figure, the parts shown in  FIGS. 9 and 12  have been combined to form the assembly shown in  FIG. 15 . The bolt  44  (see  FIG. 14 ) is inserted into the threaded hole on the top of the magnet housing  60  to secure the outer magnetic assembly  8  to the lower sealed section  108  (see  FIG. 32 ). 
       FIG. 16  is a perspective view of the pneumatic actuator mounting assembly. This figures shows the mount can  73  and retaining ring  74 . The purpose of the mount can  73  is to mount the pneumatic piston  120  so that it can move up and down. The mount can  73  is placed over the top of outer magnetic assembly  8  shown in  FIG. 15 , and then the retaining ring  74  is placed onto the bottom end of the mount can  73 . Bolts are used to fasten the retaining ring  74  to the bottom flange of the magnet housing  60  (see holes in flange in  FIG. 15  for receiving these bolts). 
       FIG. 17  is an exploded view of the pneumatic actuator mounting assembly. The mount can top  71  is mounted via bolt holes  163  to the bottom of the pneumatic actuator assembly  6  (see  FIG. 23 ). The mount can divider  72  is an optional feature and is inserted just inside the top of the mount can  73  to prevent flames from coming into contact with the outer magnet assembly during fire-testing of the valve. 
       FIG. 18  is a section view of the pneumatic actuator mounting assembly. The mount can  73  preferably has a shoulder  117  machined into it at the bottom end of the mount can  73 ; this shoulder  117  holds the retaining ring  74  shown in  FIG. 17 . 
       FIG. 19  is a top view of the magnetic coupling between the outer magnetic assembly and the inner magnetic cartridge assembly. As shown in this figure, the inner magnets  61 , which are held by the inner magnet carrier  62 , are configured so that they align radially with the outer magnets  69 . In this manner, there is a magnetic coupling between the outer and the inner magnets such that when the outer magnet carrier  68  is rotated, thereby causing the outer magnets to rotate, the inner magnets and inner magnet carrier  62  rotate as well. 
     In a preferred embodiment, the inner and outer magnets are SmCo grade to accommodate −423 to +500 degrees Fahrenheit and magnetized across the full dimension of their thickness (i.e., from outside to inside). The inner and outer magnets are preferably flat on one side and slightly curved on the other side. As shown in  FIG. 19 , the flat side of the inner magnets  61  faces inward toward the inner magnet carrier  62 , and the slightly curved (convex) side of the inner magnets  61  faces the magnet housing  60 . Similarly, the flat side of the outer magnets  69  faces the outer magnetic carrier  68 , and the slightly curved (concave) side of the outer magnets  69  faces the magnet housing  60 . 
       FIG. 20  is a perspective view of the pneumatic actuator assembly. The pneumatic actuator assembly  6  is comprised of the pneumatic actuator  37 , an upper ball nut  38 , and a ball nut mount  70 . Referring to  FIG. 21 , the top end of the upper ball screw  29  (see  FIG. 12 ) threads into the ball nut  38 , which threads into the bottom of the ball nut mount  70 . Set screw  47  secures the ball nut  38  to the ball nut mount  70  so that it cannot rotate independently of the ball nut mount  70 . The ball nut  38  moves up and down but does not rotate (whereas the entire assembly shown in  FIG. 12  rotates); as the ball nut  38  moves up and down, it forces the upper ball screw  29  to rotate. The ball nut mount  70  threads into the pneumatic piston  120  and is held in place by set screw  46  (see  FIG. 21 ). A pneumatic shall guide (in the form of a protruding ridge)  111  on the inside of the pneumatic actuator  37  interacts with the clamp-on guide  112  so that the clamp-on guide rides up and down the guide  111  and prevents the pneumatic piston  120  from rotating (see  FIG. 22 ). Once the ball nut mount  70  is securely fastened to the pneumatic piston  120 , the piston  120  moves up and down within the pneumatic actuator  37  as air pressure is applied. 
       FIG. 21  is an exploded view of the pneumatic actuator assembly. The pneumatic actuator  37  is mounted to the mount can top  71  (shown in  FIG. 16 ) via bolt holes  157  (in  FIG. 21 ) and  163  (in  FIG. 16 ). 
       FIG. 22  is a top section view of the pneumatic actuator rotational stop. Guide rollers  155  are a pair of roller bearings that ride up and down the protruding ridge  111  on the inside of the pneumatic actuator  37 , ensuring that the pneumatic piston  120  does not rotate. The roller bearings  155  are bolted to the clamp-on guide  112 . 
       FIG. 23  is an exploded view of the present invention with the pneumatic actuator. All of the parts referenced in this figure are shown in an assembled state in  FIG. 1 . The valve body  11 , flange gasket  158 , inner magnetic cartridge assembly  9 , pneumatic actuator mount assembly  7 , and pneumatic actuator assembly  6  are all mounted as a single unit and not able to rotate. The pneumatic actuator assembly  6  contains the pneumatic piston  120 , which moves up and down. 
       FIG. 24  is a section view of the present invention shown with the valve in an open position. As compared to  FIG. 11 , the following parts have been added: pneumatic actuator assembly  6 , pneumatic actuator mount assembly  7 , and outer magnetic assembly  8 . 
       FIG. 25  is a section view of the present invention shown with the valve in a closed position. As compared to  FIG. 10 , the following parts have been added: pneumatic actuator assembly  6 , pneumatic actuator mount assembly  7 , and outer magnetic assembly  8 . 
       FIG. 26  is a perspective view of the present invention fully assembled with a manual actuator. In lieu of the pneumatic actuator shown in the preceding figures, this embodiment incorporates a manual actuator. Specifically, the mount can  73  shown in  FIG. 17  has been replaced with the alternate mount can  76  shown in  FIG. 28 . The alternate mount can  76  is preferably shorter than the mount can  73  because it contains fewer parts. 
       FIG. 27  is an exploded view of the present invention with the manual actuator. All parts are the same as previously described, except that the handle assembly  14  has been added in lieu of the pneumatic actuator assembly  6 , and the pneumatic actuator mount assembly  7  has been replaced with the manual actuator mount assembly  13 . As compared to  FIG. 23 , the pneumatic actuator assembly  6 , the pneumatic actuator mount assembly  7 , and the outer magnetic assembly  8  have been removed. The outer magnetic assembly  15  is similar to the outer magnetic assembly  8  of  FIG. 23 , except that the upper ball screw  29  has been eliminated. The manual actuator mount assembly  13  is similar to the pneumatic actuator mount assembly  7  except that the top of the mount can  73  has been removed so that the top of the alternate mount cart  76  is flush with the mount can divider  72  (see  FIG. 17 ). Note that the bolt line shown at the top of the alternate mount can  76  is the same bolt line shown in the center of the mount can  73  in  FIG. 17 . (In  FIG. 17 , the mount can divider  72  is pushed downward within the mount can  73  so that the bolt holes of the mount can divider are aligned with this bolt line.) The inner magnetic cartridge assembly  9 , gate assembly  10 , flange gasket  158  and valve body  11  are the same as described previously. 
       FIG. 28  is an exploded view of the manual actuator mount assembly. Note that the mount can top  75  differs from the mount can divider  72  in that the top surface of the mount can top  75  has been extended so that it covers the top edge of the alternate mount can  76 . 
       FIG. 29  is a section view of the manual actuator mount assembly. This figure shows the parts shown in  FIG. 28  fully assembled. The alternate mount can  76  is secured to the mount can top  75  with bolts  159 . 
       FIG. 30  is an exploded view of the manual actuator handle. Referring to  FIG. 15 , the snap ring  40  fits into the groove  164  in the outer magnet top  66 . Once this is snapped into place, the handle  39  shown in  FIG. 30  slips on top of the snap ring  40 . The diameter of the hole in the center of the handle  39  is the same as the outer diameter of the top part of the outer magnet top  66 . The snap ring  40  creates a shoulder on which the handle  39  sits. The washer  42  rests on the top surface of the handle  39  in the center of the handle, directly above the hole. The retaining bolt  43  threads into the hole in the top of the outer magnet top  66  (see  FIG. 13 ). The key  41  fits into the key way  160  in the center hole of the handle and also into the keyway  118  in the outer magnet top  66  (see  FIG. 13 ). As such, when the handle  39  is rotated (either manually or via a motor or other source of kinetic energy), the outer magnet top  66  and outer magnet carrier  68  rotate, thereby causing the inner magnets  61  and inner magnet carrier  62  to rotate, as described above. 
     Although the preferred embodiment of the present invention has been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the invention in its broader aspects. The appended claims are therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.