Patent Publication Number: US-11664144-B2

Title: Single coil apparatus and method

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present disclosure relates to a single coil apparatus and method. The present disclosure relates more specifically to a single coil solenoid assembly apparatus and method. 
     Description of Related Art 
     Electromechanical solenoids include a electromagnetically inductive coil, wound around a moveable steel or iron armature. The coil is shaped such that the armature can be moved in and out of the center, altering the coil&#39;s inductance and thereby becoming an electromagnet. The armature is used to provide a mechanical force to some mechanism, such as an actuator. Solenoids may be controlled directly by a controller circuit, and thus have very fast response times. 
     BRIEF SUMMARY OF THE INVENTION 
     In view of the foregoing, it is an object of the present disclosure to provide a single coil apparatus and method. 
     A first exemplary embodiment of the present disclosure provides an apparatus. The apparatus includes a core tube extending along a longitudinal axis, the core tube having a first ferromagnetic end section with a first confronting end longitudinally spaced from a second ferromagnetic end section with a second confronting end, a first non-ferromagnetic section adjacent the first confronting end and a second nonmagnetic section adjacent the second confronting end, a first ferromagnetic spacer longitudinally intermediate the first non-ferromagnetic section and the second non-ferromagnetic section. The apparatus further includes a first magnet and a second magnet located outside the core tube, the first magnet spaced along the longitudinal axis from the second magnet wherein a second ferromagnetic spacer is longitudinally intermediate the first magnet and the second magnet, and wherein the first non-ferromagnetic section is radially inward of the first magnet and the second non-ferromagnetic section is radially inward of the second magnet, and the first ferromagnetic spacer is radially inward of the second ferromagnetic spacer, and an excitation coil is disposed radially outward of the first magnet and the second magnet. 
     A second exemplary embodiment of the present disclosure provides a method of forming. The method includes providing a core tube extending along a longitudinal axis, the core tube having a first ferromagnetic end section with a first confronting end longitudinally spaced from a second ferromagnetic end section with a second confronting end, a first non-ferromagnetic section adjacent the first confronting end and a second non-ferromagnetic section adjacent the second confronting end, a first ferromagnetic spacer longitudinally intermediate the first non-ferromagnetic section and the second non-ferromagnetic section. The method further includes providing a first magnet and a second magnet located outside the core tube, the first magnet spaced along the longitudinal axis from the second magnet wherein a second ferromagnetic spacer is longitudinally intermediate the first magnet and the second magnet, and wherein the first non-ferromagnetic section is radially inward of the first magnet and the second non-ferromagnetic section is radially inward of the second magnet, and the first ferromagnetic spacer is radially inward of the second ferromagnetic spacer. The method still further includes providing an excitation coil disposed radially outward of the first magnet and the second magnet. 
     The following will describe embodiments of the present disclosure, but it should be appreciated that the present disclosure is not limited to the described embodiments and various modifications of the invention are possible without departing from the basic principle. The scope of the present disclosure is therefore to be determined solely by the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         FIG.  1    presents a cross-sectional view of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  2    presents a close up cross-sectional view of a portion of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  3    presents a graph illustrating a stroke curve of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  4    presents a graph illustrating another stroke curve of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  5    presents a cross-sectional view of an alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  6    presents a cross-sectional view of the alternative embodiment of a device in the push direction suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  7    presents a graph illustrating another stroke curve of a device with a gap suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  8    presents a logic flow diagram in accordance with a method and apparatus for performing exemplary embodiments of the present disclosure. 
         FIG.  9    presents a graph illustrating a stroke curve of a device with reversed polarity in the push direction suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  10    presents a graph illustrating another stroke curve of a device with reversed polarity in the pull direction suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  11    presents an exemplary flexible bearing suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  12    presents an exemplary cross-sectional view of another alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  13    presents an exemplary cross-sectional view of yet another alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  14    presents an exemplary cross-sectional view of a further alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  15    presents an exemplary cross-sectional view of an even further alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  16    presents an exemplary cross-sectional view of another alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  17    presents an exemplary cross-sectional view of an exemplary device having counter bores suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  18    presents an exemplary cross-sectional view of an exemplary device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  19    presents an exemplary close-up cross-sectional view of an exemplary device suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  20    presents an exemplary cross-sectional view of an exemplary device having spacers suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  21    presents an exemplary cross-sectional view of an exemplary device with magnetic flux lines suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  22    presents a perspective view of an exemplary cylindrical magnet suitable for use in practicing exemplary embodiments of the present disclosure. 
         FIG.  23    presents a perspective view of an exemplary magnet suitable for use in practicing exemplary embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Current solenoid designs have a limited stroke range capability. Additionally, current solenoid designs are constructed from many different components. This can make it difficult or simply more costly to manufacture solenoid products. Moreover, current solenoid designs are limited in their application since every valve the solenoid interacts with or mates with needs to be adjusted due to its short stroke capabilities. The actuator that drives the solenoid also has to have its stroke adjusted because of the short working stroke range making it cumbersome to produce products in high volumes. Lastly, the construction of current solenoid designs require a large core diameter, which limits the design to having very low pressure inside the core cavity. Embodiments of the present disclosure seek to cure these issues with current solenoid designs. 
     Embodiments of the present disclosure provide a push pull single coil solenoid having a stroke length of +/− 2.5 mm from center. It should be appreciated that embodiments include a single coil solenoid having a stroke length of greater or less than +/−2.5 mm from center provided it is constructed as set forth below. It should be appreciated that the term push pull refers to movement of the armature in two opposite directions through the longitudinal axis of the core tube of the solenoid. Embodiments provide a solenoid having a single coil with magnets located radially outside the core tube, which permits a higher internal core fluid pressure. Embodiments allow for a higher internal core fluid pressure because the magnets are mounted, coupled or affixed radially outside the core tube. Accordingly, this configuration allows the diameter of the core tube to be smaller, which allows for higher internal fluid pressure. Embodiments further provide a core tube having non-magnetic sections, breaks or spacers that circumscribe the core tube. Embodiments of this configuration allow magnetic flux produced by current passing through the coil to travel through the armature into the core tube wall to provide a proportional like force over the entire stroke range of the solenoid. 
     Embodiments of the present disclosure provide a solenoid having fixed magnets and a single fixed excitation coil and a ferrous armature that is moveable through the longitudinal axis of the solenoid with respect to the fixed magnets and the fixed excitation coil. Embodiments provide that the direction of movement of the armature is determined by the polarity of the electrical signal applied to the single excitation coil, the direction of the winding of the single excitation coil (e.g., clockwise or counterclockwise), and the orientation of the magnets polarity as assembled (e.g., N-S to S-N, or S-N to N-S). 
     Embodiments of the core tube of the solenoid utilizes a multi piece design of ferrous and non-ferrous materials that are adhered together by brazing, welding, or the like such that it is operable to form a core tube cavity that can withstand pressurized fluid. Embodiments include a core construction made of a single ferrous material having gaps radially inward of the magnets that can be utilized with magnetic shunts to contain internal fluid pressure. 
     Embodiments provide that the armature is moveable along on a low friction bearing material between the interior core wall and the armature. Embodiments include the armature being suspended on a rod maintained in the radial center of the core tube with bearings located on stop ends or flexible bearings. The flexible bearings (also referred to as a meandering spring) aide in spring centering or urging the armature to its zero position when the coil is not powered. In an alternative embodiment, the solenoid may not include any bearings, but includes a friction core liner being located between the armature and the interior wall of the core tube. In yet another embodiment, bearings or low-friction coatings can be applied to the portion of the armature that contacts the interior wall of the core tube. 
     Embodiments of a solenoid include two cylindrical magnets positioned radially outside of the core tube. Between the two cylindrical magnets along the longitudinal axis are two ferrous metal spacers separated by a gap. Embodiments include the magnets and spacer(s) being secured radially outward from the core tube and radially inward from the excitation coil. Embodiments of magnets include a uniform cylindrically shaped magnet or segmented magnets that when combined form a cylinder. In one embodiment, the segmented magnets when combined form a complete cylinder. In another embodiment, the segmented magnets when combined do not form a complete cylinder. Rather, in this embodiment the segmented magnets in practice will be evening spaced around the core tube. The number of segment magnets will depend on the desired force to be generated by solenoid. Accordingly, spacing between the magnet segments will be dependent on the number of segments utilized and their size with relation to the circumference of the core tube. 
     Embodiments of the present disclosure allow the force created by the solenoid to be increased in one direction as opposed to the other direction by biasing the excitation coil off center towards one end of the solenoid. Embodiments allow for an excitation coil and ferromagnetic flux path coil assembly to surround the core tube assembly such that they are retained in place by a retention nut or similar device. Thus, embodiments allow for removal of the coil in the event of a coil failure without having to disassemble the core tube, which can cause fluid from the core tube to leak. 
     Referring to  FIG.  1   , shown is a cross-sectional view of a device  100  suitable for use in practicing exemplary embodiments of the present disclosure. Generally the device  100 , such as in the configuration of a solenoid assembly, includes a core tube  105 , a fixed magnet assembly, a single fixed excitation coil assembly and a ferromagnetic armature assembly. The ferromagnetic armature assembly is slideably received within the core tube, wherein the core tube is received within the fixed magnet assembly and the magnet assembly is then slideably received within the coil assembly. The term ferromagnetic includes ferrous materials and includes those material having a high susceptibility to magnetization, the strength of which depends on that of the applied magnetizing field, and which may persist after removal of the applied field. It should be appreciated that embodiments include any ferromagnetic materials described herein being replaced with any material that is comprised of iron based steels, irons, and cast irons. This is the kind of magnetism displayed by iron, and is associated with parallel magnetic alignment of neighboring atoms. 
     Shown in  FIG.  1    is the device  100  having the core tube  105  defining a hollow core  112  extending along a longitudinal axis. The core tube  105  includes a first ferromagnetic end section or piece  130  having a confronting end  131  and a second ferromagnetic end section or piece  132  having a confronting end  133 , wherein the confronting ends are longitudinally spaced along the longitudinal axis. The core tube  105  also includes a first non-ferromagnetic section, such as a first spacer  124  adjacent the confronting end  133  and a second non-ferromagnetic section, such as a spacer  126  adjacent to and contacting the confronting end  131 . The core tube  105  includes a ferromagnetic central spacer  122  longitudinally intermediate the non-ferromagnetic spacer  124  and the non-ferromagnetic spacer  126 . The core tube  105  can be constructed of a multi piece design of ferromagnetic and non-ferromagnetic materials that are affixed, coupled or connected together by brazing, welding, bonded or the like. 
     In one configuration each of the first and second ferromagnetic end pieces  130 ,  132  includes a respective axially extending protrusion or shoulder  138 ,  140  mating with a corresponding axial shoulder  139 ,  141  of the respective first and second non-ferromagnetic sections  126 ,  124 , wherein the shoulders  138 ,  140  are radially inward of the shoulders  139 ,  141  and form a portion of the inside surface of core tube  105 . In this regard, the ferromagnetic end piece  130  radially underlies a portion of the non-ferromagnetic section  126  and the ferromagnetic end piece  132  radially underlies a portion of the non-ferromagnetic section  124 . 
     The first and second non-ferromagnetic sections, spacers  126 ,  124  thus have an inner longitudinal dimension and an outer longitudinal dimension, wherein the outer longitudinal dimension is greater than the inner longitudinal dimension. 
     The armature assembly is operable to move along the longitudinal axis of the device  100  within the hollow core  112  in response to magnetic flux created by the wound coil  106 . The armature assembly includes a push-pull rod  118  and an armature  108 . The push-pull rod  118  carrying the armature  108  is disposed within at least a portion of the hollow core  112 . The push-pull rod  118  is moveable along the longitudinal axis within hollow core  112 . 
     The armature  108  is disposed on the push-pull rod  118 , and defines an outer diameter that is greater than an adjacent portion of the push-pull rod  118 . 
     A first bearing  114  can be located between the push-pull rod  118  and the first ferromagnetic end piece  130 , and a second bearing  116  located between the push-pull rod  118  and the second ferromagnetic end piece  132 , wherein the hollow core  112  (also referred to as a cavity) is partly defined thereby. In one configuration, the first and the second bearing  114 ,  116  support the push-pull rod  118 . While the solenoid assembly is shown with the first and second bearings  114 ,  116  it is understood alternative mechanisms can be employed for enabling relative motion between the push-pull rod  118  (and armature) and the core tube  105 . It is understood the bearings  116 ,  114  can be made of ferromagnetic or non-magnetic materials. 
     In an alternative construction, it is contemplated a low friction core liner  120  can be disposed on an inside surface of the core tube  105 . The core liner and outer diameter (surface) of the armature can thus provide the sliding interface between the armature and the core tube  105 . 
     The low friction core liner  120  can be a variety of materials such as ceramic, as well as polymeric materials such as phenolics, acetals, polytetrafluoroethylene (PTFE), ultra high molecular weight polyethylene (UHMWPE), and nylon. 
     In a further configuration, the low friction coatings can be applied to the outer surface of the armature  108 , or the inside surface of the core tube  105  or both to provide the bearing surface between the two components. 
     As depicted in  FIG.  1   , when the coil assembly is not powered, the push-pull rod  118  is in a zero, or neutral or center position, which is radially inward from and equally spaced from permanent magnets  102 ,  104 . Push-pull rod  118  is centered at the zero, neutral, or centered position by mechanical positioning or force from compression springs (e.g., meandering springs  103 ) that are compressed against hard stops or first and second ferromagnetic end sections  130 ,  132  (e.g., with a spring centered spool valve). Push-pull rod  118  with armature  108  is operable to move to the left or right along the longitudinal axis depending on the electrical input polarity to the excitation coil. 
     It is contemplated, a bushing or meandering spring can be used in place of, or in conjunction with the first bearing  114  and the second bearing  116 , wherein the spring applies a bias on the push-pull rod tending to center the rod at the zero or neutral position. 
     The hollow core  112  is operable to retain a volume of fluid, such as a liquid or gas including but not limited to hydraulic fluid. 
     The magnet assembly is located radially outside the core tube  105 . The magnet assembly is generally cylindrically shaped and sized to slideably receive the core tube  105  and be slideably received within the excitation coil assembly. 
     The magnet assembly includes a cylindrically shaped first permanent magnet  102 , a second permanent magnet  104  and at least one ferromagnetic spacer(s)  128 , wherein the ferromagnetic spacer is axially intermediate the first permanent magnet and the second permanent magnet. Referring to  FIG.  22   , shown is an exemplary cylindrically shaped permanent magnet  2200  (e.g., first or second permanent magnet  102 ,  104 ). In the embodiment depicted in  FIG.  22   , permanent magnet  2200  is one unitary piece such that permanent magnet  2200  is operable to circumscribe core tube  105 . It should be appreciated that in an alternative embodiment, permanent magnet  2200  may not be a single unitary piece, but can comprise a plurality of pieces  2302  that when combined circumscribe the entire outside surface of core tube  105  (shown in  FIG.  23   ). It should be appreciated that while  FIG.  23    depicts spaces between each piece  2302 , in practice, each piece  2302  will be in contact with the adjacent pieces to circumscribe the outside surface of core tube  105  such that there are no spaces between pieces  2302 . In yet another embodiment illustrated at reference character  2304 , permanent magnet  2200  comprises a plurality of pieces  2306  that when combined do not fully circumscribe the outside surface of core tube  105 . In this embodiment, each piece  2306  is spaced from one another around the outside surface of core tube  105 . While  FIG.  23    only depicts 4 pieces  2306 , it should be appreciated that embodiments include more or less pieces  2306  than 4. In one embodiment, pieces  2306  are evenly spaced around the outside surface of core tube  105 . In another embodiment pieces  2306  are not evenly spaced around the outside surface of core tube  105 . The magnet assembly is sized to locate the magnets  102 ,  104  and the ferromagnetic spacer outside the outer diameter of the core tube  105 . The components of the magnet assembly can be connected or bonded together or assembled and retained in an operable position about the core tube  105 . The at least one ferromagnetic spacer  128  contacts magnets  102 ,  104  and is located approximately centered over ferromagnetic spacer  122  as shown in  FIG.  1   . Embodiments of ferromagnetic spacer  122  including a non-ferrous section intermediate along the longitudinal axis of ferromagnetic spacer  122 . In this embodiment, ferromagnetic spacer  122  (shown in  FIG.  12   ) includes ferromagnetic spacer  1208  and ferromagnetic spacer  1210 . Longitudinally intermediate ferromagnetic spacer  1208  and ferromagnetic spacer  1210  is non-ferrous spacer  1212 . Non-ferrous spacer  1212  can be made of any non-ferrous material, such as a non-ferrous metal. Non-ferrous spacer  1212  is bonded or affixed to ferromagnetic spacer  1208  and ferromagnetic spacer  1210  such that a sealed interface is created between ferromagnetic spacer  1208 , non-ferrous spacer  1212  and ferromagnetic spacer  1210  operable to prevent a fluid from passing through the sealed interface. 
     As shown in  FIG.  1   , the magnets  102 ,  104  are oriented along the longitudinal axis such that like poles of the magnets are nearest or facing each other. Referring to  FIG.  1   , the south pole of each magnet  102 ,  104  are facing one another. Alternative embodiments include the north pole of each magnets  102 ,  104  facing one another. The magnets  102 ,  104  are longitudinally spaced from one another along the longitudinal axis by the at least one ferromagnetic spacer  128 . In this regard, the magnets  102 ,  104  are positioned such that like magnetic poles are facing one another and separated by the at least one ferromagnetic spacer  128 . In other words, the at least one ferromagnetic spacer  128  is longitudinally intermediate magnet  102  and magnet  104 . As shown in  FIG.  1   , the at least one ferromagnetic spacer  128  is located at the same or common longitudinal position and has the same approximate longitudinal dimension as the ferromagnetic spacer  122 . Embodiments include two or more ferromagnetic spacers  128  located longitudinally between magnets  102 ,  104 . Embodiments further include ferromagnetic spacer  128  including a gap between the ferromagnetic spacers  128 . For example, as shown in  FIG.  12   , ferromagnetic spacer  128  includes ferromagnetic spacer  1202  and  1204  each spaced from one another along the longitudinal axis by gap  1206 . Embodiments include gap  1206  having a vacuum, being made of air, non-magnetic gaseous materials, or non-magnetic materials. In this regard, the interior facing lateral sides of ferromagnetic spacers  128  that are facing one another would be in contact with vacuum, air or other non-magnetic gaseous materials. In this embodiment, the location of the ferromagnetic spacers  1202  and  1204  with respect to one another are maintained such that the size or volume of the gap  1206  remains constant by a spring  1214 . Spring  1214  is in contact with the face of ferromagnetic spacers  1202  and  1204  that face each other to urge ferromagnetic spacers  1202 ,  1204  away from one another to maintain gap  1206 . Embodiments of spring  1214  include a wave spring, o-ring, or any other non-magnetic spring. In another embodiment, gap  1206  can be replaced with a non-ferrous material, such as a metal. In this embodiment, the interior facing lateral sides of ferromagnetic spacers  128  that are facing one another would be in contact with a non-ferrous material, such a non-ferrous metal. 
     It is contemplated the magnets  102 ,  104  and the spacer  128  can be operably retained by bonding or mechanical retention. For example, in one configuration the magnets  102 ,  104  can be maintained in place through the use of a bonding agent. In one embodiment, the bonding agent is an epoxy. Embodiments of the bonding agent include any type of adhesive operable to maintain a location of magnets  102 ,  104  relative to core tube  105  during operation. Alternatively, as set forth below the magnets  102 ,  104  can be operably retained by a bias mechanism, such as a by a spring as shown in  FIG.  2   . 
     Embodiments of ferromagnetic spacer  128  are made of ferromagnetic materials. Some non-limiting embodiments of ferromagnetic materials include alloy low carbon steels and ferritic stainless steels. 
     With respect to the core tube  105 , the magnets  102 ,  104  are respectively spaced radially outward from the inside surface of the hollow core  112  as shown in  FIG.  1    by the two non-ferromagnetic spacers  124 ,  126 . The ferromagnetic spacer  122  is located radially inward of and longitudinally intermediate magnets  102 ,  104  along the inside surface of the hollow core  112 . Non-ferromagnetic spacer  124  is located radially inward and adjacent to magnet  102  along the inside surface of core tube  105 . In other words, non-ferromagnetic spacer  124  and a portion of magnet  102  occupy a common position along the longitudinal axis of device  100 . Non-ferromagnetic spacer  126  is located radially inward and adjacent to magnet  104  along the inside surface of core tube  105 . In other words, non-ferromagnetic spacer  126  and a portion of magnet  104  occupy a common position along the longitudinal axis of device  100 . 
     The shoulders  138 ,  140  of the respective ferromagnetic end pieces  130 ,  132  axially extend into the respective non-ferromagnetic sections  124 ,  126  along the inside surface of hollow core  112  such that the radially outside portion of ferromagnetic end pieces  130 ,  132  terminates longitudinally at approximately the longitudinal end of the magnets  102 ,  104 , while the shoulders (protrusions)  138 ,  140  extend passed the lateral edge of magnets  102 ,  104  to terminate within the longitudinal dimension of the respective magnet. The protrusions  138 ,  140  do not extend further than the entire length of magnets  102 ,  104 , respectively along the longitudinal direction. Embodiments of device  100  do not require magnets located at the end of the stroke length of armature  108  that are meant to alter the magnetic forces acting on the armature  108 . 
     The excitation coil assembly includes a housing, a frame within the housing and a wound coil  106  disposed about the frame, wherein the assembly is disposed radially outward from the magnets  102 ,  104  and thus is disposed about and encompasses the magnets and the core tube  105 . The wound coil  106  is operable to have a current passed through the coil to create a magnetic flux. Some non-limiting embodiments of wound coil  106  can be made of copper or aluminum insulated magnet wire. Embodiments also include the wound coil  106  being operable to conduct a current by a pulse-width modulation signal. The direction of movement of armature  108  is determined by the polarity of the electrical current applied to the wound coil  106 , the direction of the winding of the wound coil, and the orientation of the polarity of magnets  102 ,  104 . 
     The armature  108  has an approximate zero, center, or neutral position relative to magnets  102 ,  104  which is depicted in  FIG.  1   . The zero, center, or neutral position of the armature  108  is when the armature is located longitudinally symmetrically centered with respect to the magnets and the at least one ferromagnetic spacer  122 . Embodiments include ferromagnetic spacer  122  including two or more ferromagnetic spacers. The armature  108  is operable to move longitudinally through the hollow core  112  of the core tube  105  along the longitudinal axis of device  100  from left or right from the zero, center, or neutral position, as seen in  FIG.  1   . The direction the armature  108  moves is dependent on the polarity of the current that passes through wound coil  106  and the orientation of the magnets  102 ,  104 . 
     In one embodiment, the bearings  114 ,  116  are replaced with meandering springs  103  (shown in  FIG.  11   ). Embodiments of the meandering springs  103  are operable to aid in centering the armature  108  to its zero, center, or neutral position relative to magnets  102 ,  104  and ferromagnetic spacer  122  when no current is passing through the wound coil  106 . The meandering spring  103  is thus operable to aid in centering the armature  108  by physically urging and moving rod  118  with the armature  108  to its zero, center, or neutral position. 
     Referring to  FIG.  2   , shown is an alternative embodiment of device  100  suitable for performing exemplary embodiments of the present disclosure. Illustrated in  FIG.  2    is device  200  in the configuration of a solenoid having a fixed excitation coil assembly having a wound coil  206 , a fixed magnet assembly with magnets  202 ,  204 , with a ferromagnetic spacer  228 , a core tube  205 , and a ferromagnetic armature assembly. 
     The core tube  205  includes a ferromagnetic spacer  222  longitudinally intermediate non-ferromagnetic spacers  224 ,  226 , which in turn are respectively bounded by first and second ferromagnetic end pieces  223 ,  225 . 
     In the fixed magnet assembly of this embodiment, a ferromagnetic spacer  228  is longitudinally intermediate the magnets  202 ,  204 , which in turn are longitudinally bounded by ferromagnetic ends pieces  236 ,  238  respectively. 
     In this configuration each of the first and second ferromagnetic end pieces  223 ,  225  includes a respective axially extending protrusion or shoulder  338 ,  340  mating with a corresponding axial shoulder  339 ,  341  of the respective first and second non-ferromagnetic sections  224 ,  226 , wherein the shoulders  338 ,  340  are radially inward of the shoulders  339 ,  341  and form a portion of the inside surface of core tube  205 . In this regard, the ferromagnetic end piece  223  radially underlies a portion of the non-ferromagnetic section  224  and the ferromagnetic end piece  225  radially underlies a portion of the non-ferromagnetic section  226 . The longitudinal dimension of the shoulder with respect to the radially outward magnet is between approximately 20% to 80% of the axial dimension of the magnet. 
     The first and second non-ferromagnetic sections, spacers  224 ,  226  thus have an inner longitudinal dimension and an outer longitudinal dimension, wherein the outer longitudinal dimension is greater than the inner longitudinal dimension. 
     Axial retention of the ferromagnetic spacer  228  and the bounding magnets  202 ,  204 , which in turn are longitudinally bounded by ferromagnetic ends pieces  236 ,  238  can be accomplished by a bias mechanism, such as a spring  234 . The spring  234  is operable to be located between a portion of the coil assembly and one of the ferromagnetic end pieces  236  and/or  238  such that the spring urges and maintains a force on the magnets  202 ,  204 , the ferromagnetic spacer  228 , and the ferromagnetic ends  236 . In one embodiment, the spring  234  is a Belleville spring. 
     In this embodiment, the wound coil assembly, the magnets  202 ,  204 , the ferromagnetic spacer  228 , and the ferromagnetic ends  230 ,  236  are operable to slideably move along the longitudinal axis over the core tube  205  including the ferromagnetic spacer  222 , and the non-ferromagnetic spacers  224 ,  226  such that coil assembly (e.g., in the event of failure of wound coil  206 ) can be removed without needing to disassemble the core tube  205 . This embodiment thus allows replacement of the wound coil  206 , and/or the magnets  202 ,  204  without the risk of fluid leaking from the hollow core  212 . 
     In this regard, the core tube  205  defines an inner surface that is a sealed surface. Embodiments further include the core tube  205  defining an inner surface that is a fluid tight surface, which substantially prevents the passage of fluid there through. Additionally, the magnets  202 ,  204  are removeable such that they can be replaced without disrupting the integrity of the core tube  205 . The magnets  202 ,  204  are mounted with a close slip fit I.D. of magnet to O.D. of core tube  205  Embodiments include the core tube  205  (including the non-ferromagnetic sections or spacers, and the intermediate ferromagnetic spacer) being retained in place by an end nut or similar mechanical retention device. Thus, the wound coil  206  can be removed without fluid leaking from hollow core  212  because the core tube  205  (including non-ferrous spacers  224 ,  226 , and ferrous spacer  222 ) remains intact. In this embodiment, magnets  202 ,  204  ferrous spacers  228 ,  236  and spring  234  are operable to slideably receive core tube  205 , and wound coil assembly including the wound coil  206  is operable to slideably receive the magnets  202 ,  204  ferrous spacers  228 ,  236  and spring  234 . 
     Embodiments of device  200  and device  100  provide that core tube  105 ,  205  are operable to maintain a high internal fluid pressure between 0 to 30,000 PSIA. However, it should be appreciated that embodiments include an internal core tube  105  fluid pressure greater than 30,000 PSIA. Embodiments provide that the core tube  105  has a diameter ranging between 0.25 to 1.250 inches. However, it should be appreciated that embodiments includes a core tube  105  having a diameter that is smaller than 0.25 inches or greater than 1.250 inches. Embodiments provide that core tube  105  has an internal diameter is generally smaller than present cores due to the placement of magnets  102 ,  104  (or  202 ,  204 ), which allows for a thinner core tube  105  wall is operable to maintain a higher working pressure within the hollow core  112 . Embodiments of magnets  102 ,  104  (and  202 ,  204 ) include each being comprised of a single magnet and may be formed of a plurality of magnets stacked on one another. 
     Thus, the magnets are longitudinally aligned with the non-ferromagnetic sections and are coincident with the longitudinal dimension of the outer surface of the non-ferromagnetic sections. The ferromagnetic spacer of the core tube, longitudinally intermediate the non-ferromagnetic sections of the core tube is longitudinally aligned with the ferromagnetic spacer of the magnet assembly which spacer is longitudinally intermediate the first and second magnet. The core tube thus includes two non-ferromagnetic sections which bound a ferromagnetic spacer there between and in turn are longitudinally bounded by ferromagnetic end pieces, wherein the components are fused together to form a pressure vessel. It should be appreciated that while the embodiments described in  FIGS.  1 - 2    include a core tube having separate non-ferromagnetic sections, and a ferromagnetic spacer, embodiments include the core tube being a single homogenous tube having non-ferromagnetic portions separated by a homogenous ferromagnetic portion. In this regard, embodiments include both a core tube being a single homogenous core and a core tube wherein each non-ferromagnetic section and ferromagnetic spacer is a separate element that is non-homogenous. 
     Embodiment of device  100  and device  200  are operable such that a magnetic field or magnetic flux is created when current passes through wound coil  106 . The magnetic flux urges or causes armature  108  (with rod  118 ) to move through the longitudinal axis of hollow core  112 . The distance through which armature  108  moves is referred to as the stroke length. Embodiments of the present disclosure provide an increased stroke length of between 0.01 to 0.25 inches. Embodiments of the present disclosure provide an increase stroke length of greater than 0.25 inches. Embodiments provide that device  100  is operable to cause or urge armature  108  to move in one direction through core tube  105  along the longitudinal axis of device  100  in response to the current flowing through wound coil  106  having a first polarity. Embodiments provide that device  100  is operable to cause or urge armature  108  to move in an opposite direction through core tube  105  along the longitudinal axis of device  100  in response to the current flowing through wound coil  106  having a second polarity. In this embodiment, the first polarity is different from the second polarity. In this regard, embodiments of device  100  are operable to cause armature  108  to move in both (push and pull) directions through the longitudinal axis of core tube  105 . That is, the solenoid assembly can provide bidirectional movement by reversing the polarity to the single wound coil. 
     Referring to  FIG.  3   , shown is a graph illustrating a stroke curve in the pull direction of a device suitable for use in practicing exemplary embodiments of the present disclosure. The graph shown in  FIG.  3    indicates the stroke length in inches along the x-axis and pounds of force along the y-axis. Each curve on the graph illustrates how force from a device  100  changes over a given stroke length in the pull direction while a particular current (i.e., amps) is passed through the wound coil  106 . As depicted, the force stroke curve for 100 milliamps, 200 milliamps, 300 milliamps, 400 milliamps, 500 milliamps, 600 milliamps, 700 milliamps, 800 milliamps, 900 milliamps, 1000 milliamps, and 1100 milliamps are shown. Embodiments provide that a particular position of the armature  108  relative to the core tube  105  can be controlled by the flow of current through wound coil  106  up to at least a stroke length of 2.5 mm. Stroke length refers to the total distance traveled along the longitudinal axis of the device  100  of the armature  108  relative to the core tube  105  in a single direction. It should be appreciated that the force stroke curve lines shown in  FIG.  3    relate to the device  100  having the magnets  102 ,  104  wherein the south pole of the magnets are facing one another. The spring constant associated with spring  234  will affect the stroke length to the extent that the spring constant of spring  234  enables spring  234  to oppose movement forces of armature  108  based on the applied milliamps to the wound coil. 
     Referring to  FIG.  4   , shown is a graph illustrating another stroke curve in the push direction of a device suitable for use in practicing exemplary embodiments of the present disclosure. The graph shown in  FIG.  4    indicates the stroke length in inches along the x-axis and pounds of force along the y-axis. Each curve on the graph illustrates how force from a device  100  changes over a given stroke length in the push direction while a particular current (i.e., amps) is passed through the wound coil  106 . As depicted, the force stroke curve for 100 milliamps, 200 milliamps, 300 milliamps, 400 milliamps, 500 milliamps, 600 milliamps, 700 milliamps, 800 milliamps, 900 milliamps, 1000 milliamps, and 1100 milliamps are shown. Embodiments provide that a particular position of the armature  108  relative to the core tube  105  can be controlled by the flow of current through the wound coil  106  up to at least a stroke length of 2.5 mm. It should be appreciated that the force stroke curve lines shown in  FIG.  3    relate to the device  100  having the magnets  102 ,  104  wherein the south pole of magnets are facing one another. 
     Referring to  FIG.  9   , shown is a graph illustrating a stroke curve of a device with reversed polarity in the push direction suitable for use in practicing exemplary embodiments of the present disclosure.  FIG.  10    is a graph illustrating a stroke curve of a device with reversed polarity in the pull direction. Reversed polarity refers to the device  100  having the magnets  102 ,  104  wherein the north poles of the magnets are facing one another. The graphs shown in  FIGS.  9  and  10    indicate the stroke length in inches along the x-axis and pounds of force along the y-axis. Each curve on the graphs illustrate how force from a device  100  changes over a given stroke length in the pull direction while a particular current (i.e., amps) is passed through the wound coil  106 . As depicted, the force stroke curve for 100 milliamps, 200 milliamps, 300 milliamps, 400 milliamps, 500 milliamps, 600 milliamps, 700 milliamps, 800 milliamps, 900 milliamps, 1000 milliamps, and 1100 milliamps are shown. 
     Referring to  FIG.  5   , shown is a cross-sectional view of an alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. Shown in  FIG.  5    is device  500  having magnets  502 ,  504 , a wound coil  506 , ferromagnetic spacers  508 ,  510 , non-ferromagnetic spacers  512 ,  514 , ferromagnetic ends  516 ,  518 , and an armature  520 . In this embodiment there is no physical stop for the movement of armature  520  along the pull direction (indicated by line  522 ). This embodiment includes a gap  524  which allows armature  520  to have a greater range of movement in the pull direction than in the push direction since ferrous end  518  provides a physical stop for armature  520  in the push direction. Embodiments provide that gap  524  allows for movement of armature  520  along the pull direction to be greater than 0.125 inches from armature  520 &#39;s zero position. Embodiments provide that gap  524  allows for movement of armature  520  along the pull direction to be greater than. Embodiments of device  500  provide that wound coil  506  is operable to have a current passed through it, which creates a magnetic flux that is operable to urge or move armature  520  through the longitudinal axis of core tube  505 . The magnetic flux created by the current that passes through wound coil  506  is shown by concentric lines  526 . Due to gap  524 , concentric lines  526  do not extend into hollow core  528  of device  500 . Embodiments provide that core tube  505  is operable to maintain a fluid (e.g., liquid and/or gas) that allows for movement of armature  520  through hollow core  528 . Embodiments provide that core tube  505  is operable to maintain a gaseous media that allows for movement of armature  520  through hollow core  528 . 
     Referring to  FIG.  6   , shown is a cross-sectional view of the alternative embodiment of a device in the push direction suitable for use in practicing exemplary embodiments of the present disclosure. Shown in  FIG.  6    is device  600  having magnets  602 ,  604 , wound coil  606 , ferrous spacers  608 ,  610 , non-ferrous spacers  612 ,  614 , ferrous ends  616 ,  618 , and armature  620 . This embodiment also includes a gap  624  which allows armature  620  to have a greater range of movement in the pull direction (shown in  FIG.  5   ) than in the push direction (indicated by line  622 ) since ferrous end  618  provides a physical stop for armature  620 . Embodiments of device  600  provide that wound coil  606  is operable to have current passed through it, which creates a magnetic flux that is operable to urge or move armature  620  through the longitudinal axis of core tube  605 . The magnetic flux created by the current that passes through wound coil  606  is shown by concentric lines  626 . 
     Reference is now made to  FIG.  7   , which depicts an exemplary graph of a force stroke performance finite element analysis (FEA) curve. This graph shows the performance of embodiments of device  500  with no bearing located in the magnetic circuit path in the pull direction. In other words, there is a gap  524  which allows for greater range of movement in the pull direction for armature  520 . As is evident, the force curve performance illustrated in  FIG.  7    is relatively the same as that shown in  FIG.  3    for a device having no gap located in the pull direction of the armature. Embodiments of device  500  provide that the bearing (e.g., flexible mechanical centering device such as a linear compression spring or meandering spring) located in the pull direction is positioned at a distance from the wound coil  506  such that the bearing does not fall within the magnetic flux path. 
     Referring to  FIG.  8   , presented is an exemplary logic flow diagram in accordance with a method, and apparatus for performing exemplary embodiments of this disclosure. Block  800  presents providing a core tube extending along a longitudinal axis, the core tube having a first ferromagnetic end section with a first confronting end longitudinally spaced from a second ferromagnetic end section with a second confronting end, a first nonmagnetic section adjacent the first confronting end and a second nonmagnetic section adjacent the second confronting end, a first ferrous spacer longitudinally intermediate the first nonmagnetic section and the second nonmagnetic section; providing a first magnet and a second magnet located outside the core tube, the first magnet spaced along the longitudinal axis from the second magnet wherein a second ferrous spacer is longitudinally intermediate the first magnet and the second magnet, and wherein the first nonmagnetic section is radially inward of the first magnet and the second nonmagnetic section is radially inward of the second magnet, and the first ferrous spacer is radially inward of the second ferrous spacer; and providing an excitation coil disposed radially outward of the first magnet and the second magnet. Block  802  relates to wherein the first ferrous spacer is located at approximately the same longitudinal position as the second ferrous spacer. 
     Some of the non-limiting implementations detailed above are also summarized at  FIG.  8    following block  802 . Block  804  specifies wherein proximal poles of the first magnet and the second magnet are like. Block  806  states wherein the first nonmagnetic section contacts the first confronting end of the first ferromagnetic end section of the core tube. Then block  808  relates to wherein the second nonmagnetic section contacts the second confronting end of the second ferromagnetic end section of the core tube. Next block  810  relates to wherein the first nonmagnetic section contacts the first confronting end of the ferromagnetic end section of the core tube such that a portion of the first ferromagnetic end section of the core tube radially underlies a portion of the first nonmagnetic section. Then block  812  states wherein the second nonmagnetic section contacts the second confronting end of the second ferromagnetic end section of the core tube such that a portion of the second ferromagnetic end section of the core tube radially underlies a portion of the second nonmagnetic section. 
     The logic diagram of  FIG.  8    may be considered to illustrate the operation of a method, a result of execution of computer program instructions stored in a computer-readable medium. The logic diagram of  FIG.  8    may also be considered a specific manner in which a device is formed, whether such a device is a solenoid, or other device, or one or more components thereof. 
     Embodiments of the present disclosure provide a solenoid having a single wound coil (or excitation coil) that is operable to conduct a current which creates a magnetic flux through the solenoid to move an armature. Embodiments further include a single coil solenoid having two magnets that are radially between a radially exterior wound coil and a radially interior core tube. Embodiments include a single coil solenoid, wherein the two magnets are spaced from one another longitudinally by a ferromagnetic material. Embodiments include a single coil solenoid, wherein the two magnets are radially outward from two non-ferromagnetic materials. Embodiments of the present disclosure include a single coil solenoid having a ferromagnetic armature operable to move in both the push and pull direction along the longitudinal axis of the solenoid between two bearings that form a portion of the solenoid core tube. Embodiments of the present disclosure provide a single coil solenoid, wherein one direction of movement of the armature is obstructed and wherein the opposite direction of movement of the armature is unobstructed. Embodiments include a single coil solenoid having two magnets that are maintained in place relative to the core tube by a spring, and wherein the two magnets are removeable from the core tube. 
     Embodiments of the present disclosure present a tubular solenoid assembly, which permits movement in the push and pull directions. Embodiments provide movement of an armature of +/−2.5 mm relative to the armature&#39;s center location. It should be appreciated, that embodiments of the present disclosure provide that movement of an armature relative to its center location can be less than or greater than +/−2.5 mm. Embodiments of the present disclosure provide for high internal fluid pressure within a core tube of a solenoid in which that the armature resides. Embodiments provide an internal fluid pressure of core tube between 030,000 PSIA. However, embodiments provide an internal fluid pressure of core tube greater than 30,000 PSIA. Embodiments provide a device having a magnetic core tube constructed with non-magnetic breaks that allow magnetic flux to pass through the armature into the core wall to provide a proportional like force output performance with current changes applied over its stroke range with no obstructions in the movement of the armature. Embodiments provide a tubular solenoid assembly wherein the amount of force generated from movement of the armature with push-pull rod varies proportionally based on the applied milliamps to the wound coil over the stroke length. That is, the core tube, while being predominantly ferromagnetic includes two non-ferromagnetic breaks along the longitudinal axis, wherein the non-ferromagnetic breaks allow for magnetic flux to pass through the armature into the wall of the core tube to provide a proportional like force output performance over the designed stroke range without requiring fixed stop gaps as employed in the prior art. The present tubular solenoid design provides movement similar to a moving magnet actuator, without the drawbacks of the moving magnet actuator. 
     Reference is now made to  FIG.  13   , which illustrates a cross-sectional view of another exemplary device  1300 . Shown in  FIG.  13    is device  1300  having a core tube  1305  that includes ferromagnetic spacer  1322  and non-ferromagnetic spacers  1324 ,  1326 . Radially outside core tube  1305  are magnets  1302 ,  1304  separated by ferromagnetic spacer  1328 . In the embodiment shown in  FIG.  13   , ferromagnetic spacer  1328  includes a gap  1330 , however, it should be appreciated that embodiments include ferromagnetic spacer  1328  being made of a single solid material without a gap. Radially outside magnets  1302 ,  1304  is wound coil  1306 . 
     Also shown in  FIG.  13    is armature  1308 . Armature  1308  includes inwardly radially angled sides  1350 ,  1352  that are shaped such that each radial end of armature  1308  along its longitudinal axis are conically shaped. Core tube  1305  includes angled shoulders  1338 ,  1340  that are angled radially inward to correspond to the angled sides  1350 ,  1352 . Angled shoulders  1338 ,  1340  extend radially underneath non-ferromagnetic spacers  1324 ,  1326  within hollow core  1312 . However, angled shoulders  1338 ,  1340  do not extend underneath the entire length of non-ferromagnetic spacers  1324 ,  1326 . In this regard, angled shoulders  1338 ,  1340  only underlie a portion of non-ferromagnetic spacers  1324 ,  1326 . 
     Referring to  FIG.  14   , which illustrates a cross-sectional view of another exemplary device  1400 . Shown in  FIG.  14    is device  1400  having a core tube  1405  that includes ferromagnetic spacer  1422  and non-ferromagnetic spacers  1424 ,  1426 . Radially outside core tube  1405  are magnets  1402 ,  1404  separated by ferromagnetic spacer  1428 . In the embodiment shown in  FIG.  14   , ferromagnetic spacer  1428  includes a gap  1430 , however, it should be appreciated that embodiments include ferromagnetic spacer  1428  being a single piece without a gap  1430 . Radially outside magnets  1402 ,  1404  is wound coil  1406 . Also shown is armature  1408  operable to move through the hollow core  1412 . Armature  1408  includes indentations  1450 ,  1452  located on the long ends of armature  1408 . Core tube  1405  includes protruding surfaces  1438 ,  1440  on either side of armature  1408 . Protruding surfaces  1438 ,  1440  correspond to the indentations  1450 ,  1452  located on the longitudinal axis ends of armature  1408  such that protruding surfaces  1438 ,  1440  fit within indentations  1450 ,  1452 . Embodiments include the protruding surfaces  1438 ,  1440  being cone shaped and indentations  1450 ,  1452  being inwardly cone shaped to correspond with the shape of protruding surfaces  1438 ,  1440 . 
     Referring now to  FIG.  15   , shown is a cross-sectional view of another exemplary device  1500 . Shown in  FIG.  15    is device  1500  having a core tube  1505  that includes ferromagnetic spacer  1522  and non-ferromagnetic spacers  1524 ,  1526 . Radially outside core tube  1505  are magnets  1502 ,  1504  separated by ferromagnetic spacer  1528 . In the embodiment shown in  FIG.  15   , ferromagnetic spacer  1528  includes an gap  1530 . It should be appreciated that embodiments include ferromagnetic spacer  1528  being made of a single piece without a gap  1530 . Radially outside magnets  1502 ,  1504  is wound coil  1506 . 
     Device  1500  also includes armature  1508  operable to move through the hollow core  1512 . Armature  1508  includes flat edges  1550 ,  1552  located on the long ends of armature  1508 . Core tube  1505  includes flat ends  1538 ,  1540  on either side of armature  1508 . Flat ends  1538 ,  1540  have a surface shape that corresponds to the flat edges  1550 ,  1552 . Embodiments include flat edges  1550 ,  1552  being substantially 90 degrees from the radial surface of armature  1508 . In this embodiment, flat ends  1538 ,  1540  is positioned to correspond to flat edges  1550 ,  1552  such that flat ends  1538 ,  1540  are substantially parallel to flat edges  1550 ,  1552 . In this embodiment, core tube  1505  is made of a single unitary piece of stainless steel (e.g., chromium-nickel-aluminum, austenitic stainless steel 17-7 PH) rather than having multiple pieces of ferromagnetic and non-ferromagnetic material that are welded together. In this embodiment, the core tube  1505  is annealed such that a portion of core tube  1505  portions becomes non-magnetic (e.g., spacers  1524 ,  1526 ). In other words, embodiments of core tube  1505  include having a uniform integral one-piece design and then annealing the portion of the core tube  1505  radially inward from magnets  1502 ,  1504  such that those annealed areas exhibit non-ferromagnetic or non-magnetic properties. 
     Reference is now made to  FIG.  16   , which shown is a cross-sectional view of another exemplary device  1600 . Shown in  FIG.  16    is device  1600  having a core tube  1605  that includes non-ferromagnetic spacer  1624 . Radially outside core tube  1605  are magnets  1602 ,  1604  separated by ferromagnetic spacer  1628 . In the embodiment shown in  FIG.  16   , ferromagnetic spacer  1628  includes a gap  1630 . Embodiments include ferromagnetic spacer  1628  being a single piece without a gap  1630 . Radially outside magnets  1602 ,  1604  is wound coil  1606 . As illustrated in  FIG.  16   , core tube  1605  is made of a single non-ferromagnetic material since it does not include any ferromagnetic spacers within the core tube  1605 . Accordingly, magnets  1602 ,  1604  are located radially outside from a non-ferromagnetic core tube  1605 . Likewise, ferromagnetic spacer  1628  with gap  1630  are located radially outside non-ferromagnetic core tube  1605 . It should be appreciated that in this embodiment, magnetic flux created by current passing through coil  1606  will not pass through core tube  1605  as easily as the embodiments set forth above, which may cause the force created by movement of armature  1608  to be less than that found in the other embodiments. 
     Device  1600  also includes armature  1608  operable to move through the hollow core  1612 . Armature  1608  includes steps  1650 ,  1652  located on the radial edge of armature  1508  such that steps  1650 ,  1652  circumscribe the radial edge of armature  1608 . Core tube  1605  includes ridges  1638 ,  1640  on either side of armature  1508 . Ridges  1638 ,  1640  have a shape that corresponds to the steps  1650 ,  1652  such that ridges  1638 ,  1640  are sized to fit within steps  1650 ,  1652 , respectively. Embodiments include steps  1650 ,  1652  extending along the long axis (the long axis is the same axis that armature  1608  is operable to move through) such that the steps  1650 ,  1652  only extend through a portion of the long axis of armature  1608 . In this regard, steps  1650 ,  1652  do not extend the entire length of armature  1608 . Embodiments include steps  1650 ,  1652  being positioned relative to the core tube  1605  end piece such that the core tube  1605  end piece is substantially 90 degrees with respect to steps  1650 ,  1652 . Likewise, embodiments include ridges  1638 ,  1640  are positioned substantially 90 degrees with respect to the long axis edge of armature  1608 . 
     Referring to  FIG.  17   , shown is a cross-sectional view of another exemplary device  1700 . Shown in  FIG.  17    is device  1700  having a core tube  1705  that is made of a single unitary non-ferromagnetic material. Radially outside core tube  1705  are magnets  1702 ,  1704  separated by ferromagnetic spacer  1728 . Ferromagnetic spacer  1728  includes a gap  1730 . Although shown as having a gap  1730 , embodiments include ferromagnetic spacer  1728  being a single piece without a gap  1730 . Radially outside magnets  1702 ,  1704  is wound coil  1706 . Also shown in  FIG.  17    is armature  1708  operable to move through the longitudinal axis of device  1700 . Armature  1708  includes bores  1750 ,  1752  located on the longitudinal ends of armature  1708 . Bores  1750 ,  1752  are defined by the radial edge  1754  of armature  1708  such that radial edge  1754  extends along the longitudinal axis further than bore  1750 ,  1752 . Core tube  1705  includes extensions  1738 ,  1740  which extend longitudinally inward toward armature  1708 . Extensions  1738 ,  1740  are spaced from the radial inside surface of core tube  1705 . Thus, the radial edge of extensions  1738 ,  1740  and the radial inside surface of core tube  1705  define a space  1760 ,  1762 , respectively. Space  1760 ,  1762  are sized to maintain or accommodate radial edge  1754 . Likewise, bores  1750 ,  1752  are sized to maintain or accommodate extensions  1738 ,  1740 . 
     Reference is now made to  FIG.  18   , which shows a cross-sectional view of another exemplary device  1800 . Illustrated in  FIG.  18    is device  1800  having an excitation coil  1806 , an armature  1808 , and a core tube  1805  including ferromagnetic spacer  1822  and non-ferromagnetic spacers  1824 ,  1826 . Radially outside core tube  1805  are magnets  1802 ,  1804  separated by ferromagnetic spacer  1828 . Armature  1808  is operable to move through the cavity  1803  defined by core tube  1805  in either the push or pull direction in response to current passing through excitation coil  1806 . Ferromagnetic spacer  1828  includes a gap  1830 . Although shown as having a gap  1830 , embodiments include ferromagnetic spacer  1828  being a single piece without a gap  1830 . In the embodiment shown in  FIG.  18   , gap  1830  is located approximately in the midsection or middle of spacer  1828 . However, it should be appreciated that gap  1830  can be located adjacent to the midsection of spacer  1828 . Radially outside magnets  1802 ,  1804  is wound coil  1806 . Device  1800  also includes armature  1808  operable to move through the longitudinal axis (as indicated by line  1809 ) of device  1800 . 
     Reference is now made to  FIG.  19   , which illustrates a close-up cross-sectional view of device  1800 . Similar to  FIG.  18   ,  FIG.  19    depicts magnets  1802 ,  1804 , ferromagnetic core tube  1805 , ferromagnetic spacer  1822 , ferromagnetic spacer  1828  with gap  1830  and non-ferromagnetic spacers  1824 ,  1826 . The core tube  1805  includes two channels  1811 ,  1813  that circumscribe the radial outside surface of core tube  1805 . Channels  1811 ,  1813  each include at least a first surface  1815 ,  1817  that is angled radially inward toward spacer  1822  (e.g., between 5 degrees to 60 degrees from the surface of core tube  1805 ), and a second surface  1819 ,  1821  angled radially outward toward spacer  1828 . Each channel  1811 ,  1813  is comprised of non-ferromagnetic material that form spacers  1824 ,  1826 , respectively. In other words, spacers  1824 ,  1826  are not uniformly the same radial thickness along the longitudinal direction. Rather, the radial thickness of spacers  1824 ,  1826  changes along the longitudinal direction. As shown in  FIG.  19   , non-ferromagnetic spacers  1824 ,  1826  do not have the same length along the longitudinal axis as magnets  1802 ,  1804 . Rather embodiments include spacers  1824 ,  1826  being coextensive with the portion of magnets  1802 ,  1804  that is in contact with spacer  1822 , but do not extend the entire length of magnets  1802 ,  1804  in the longitudinal direction. In other words, spacers  1824 ,  1826  terminate (i.e., the diameter of core tube  1805  returns to the same uniform diameter) or have a length that is shorter in the longitudinal direction than magnets  1802 ,  1804 . This also means that core tube  1805  extends radially underneath a portion of magnets  1802 ,  1804 . Embodiments include core tube  1805  extending radially underneath 25% to 50% of the length of magnets  1802 ,  1804  in the longitudinal direction. 
     Referring to  FIG.  20   , shown is a cross-sectional view of another embodiment of device  2000  suitable for practicing embodiments of this disclosure. Illustrated in  FIG.  20    is a cross-sectional view of device  2000  having magnets  2002 ,  2004 , ferromagnetic core tube  2005 , ferromagnetic spacer  2022 , armature  2008 , ferromagnetic spacer  2028  with gap  2030  and channel gaps  2024 ,  2026 . As illustrated in  FIG.  20   , spacer  2022  is approximately the same length in the longitudinal direction as spacer  2028  such that a portion of spacer  2022  is radially inward from magnets  2002 ,  2004 . It should be appreciated that in the embodiment shown in  FIG.  20    channel gaps  2024 ,  2026  are defined by the space between the outer radial surface of core tube  2005  (i.e., created by the shunt or channel) and the inner radial surface of magnets  2002 ,  2004 , respectively. Channel gaps  2024 ,  2026  are created by the outer radial diameter of core tube  2005  decreasing along angled surfaces  2032 ,  2034  (e.g., between 5 degrees to 60 degrees relative to the outer radial surface of core tube  2005 ) and then increasing along angled surface  2036 ,  2038 . Embodiments of channel gaps  2024 ,  2026  can be formed by removing a portion of the core tube  2005  radially inward from magnets  2002 ,  2004  such that a channel that circumscribes the outside radial surface of core tube  2005  is formed. It should be appreciated that the thickness (i.e., distance between the outside radial surface of core tube  2005  and the radial outside surface of channel gaps  2024 ,  2026 ) is less than the wall thickness of core tube  2005 . In other words, channel gaps  2024 ,  2026  do not create a passageway between the interior and the exterior of core tube  2005 . Rather, a portion of core tube  2005  remains radially inward from magnets  2002 ,  2004 . As depicted in  FIG.  20   , channel gaps  2024 ,  2026  do not have the same length in the longitudinal direction as magnets  2002 ,  2004 . Thus, a portion of core tube  2005  extends radially inward from magnets  2002 ,  2004 . It should be appreciated that embodiments include channel gaps  2024 ,  2026  have a length in the longitudinal direction equal to magnets  2002 ,  2004  such that channel gap  2024  is coextensive with magnet  2002  and channel gap  2026  is coextensive with magnet  2004 . As shown in  FIG.  20   , channel gaps  2024 ,  2026  are located radially inward and adjacent to spacer  2028 , however, embodiments include channel gaps  2024 ,  2026  being located spaced from spacer  2028  in the longitudinal direction. In this embodiment, core tube  2005  is made of a single piece of ferromagnetic or steel material, which aides in maintaining the structural integrity of core tube  2005  and the ability for core tube  2005  to maintain a higher internal core pressure. 
     Armature  2008  as shown in  FIG.  20    is in the centered position relative to coil  2006 . Armature is made of a ferrous material and is operable to move in both directions through the longitudinal axis  2009  of core tube  2005 . Movement of armature  2008  is restricted by ends  2040 ,  2042 . 
     Referring now to  FIG.  21   , shown is an exemplary embodiment of a cross-sectional view of an alternative embodiment of a device suitable for use in practicing exemplary embodiments of the present disclosure. Shown in  FIG.  21    is device  2100  having magnets  2102 ,  2104 , a wound coil  2106 , ferromagnetic spacer  2122 , ferromagnetic spacer  2128 , gaps  2124 ,  2126 , ferromagnetic ends  2116 ,  2118 , and an armature  2108 . In this embodiment, ferromagnetic spacer  2128  includes an gap  2130  that extends from the outer radial surface of ferromagnetic spacer  2128  to the radially inner surface of ferromagnetic spacer  2128 . It should be appreciated that in this embodiment gaps  2124 ,  2126  are the same length in the longitudinal direction  2109  as magnets  2102 ,  2104 . However, it should also be appreciated that embodiments include gaps  2124 ,  2126  not being coextensive or having the same length in the longitudinal direction as magnets  2102 ,  2104 . Embodiments of device  2100  provide that wound coil  2106  is operable to have a current passed through it, which creates a magnetic flux that is operable to urge or move armature  2108  through the longitudinal axis  2109  of core tube  2105 . The magnetic flux created by the current that passes through wound coil  2106  is shown by concentric lines  2125 . As shown in  FIG.  21   , when current passes through coil  2106 , magnetic flux is created and passes through magnets  2102 ,  2104 , ferromagnetic spacers  2128 ,  2122 , core tube  2105 , armature  2108  and a portion of gaps  2124 ,  2126 . It should be noted that a portion of gaps  2124 ,  2126  do not have magnetic flux passing through it. In other words, concentric lines  2125  only partially extend into gaps  2124 ,  2126 . 
     It should be appreciated that coil  2106  is not located in the center in the longitudinal direction of magnets  2124 ,  2126 , and spacer  2128 . Rather, coil  2106  is positioned such that coil  2106  is predominately located radially outside magnet  2106  and to the right of spacer  2128 . In this embodiment, when current passes through coil  2106 , the force created by the movement of armature  2108  is greater in the direction in which coil  2106  is positioned. In other words, the embodiment depicted in  FIG.  21    provides for greater force in the direction to the right. Likewise, embodiments include coil  2106  being positioned predominately radially outside magnet  2104  such that greater force can be produced by the movement of armature  2108  in the opposite direction to the left. 
     It is to be understood that any feature described in relation to any one embodiment may be used along, or in combination with one or more features of any other of the embodiments. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of this disclosure, which is defined in the accompanying claims.