Patent Description:
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'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.

<CIT> discloses a double-acting electromagnetic linear motor, which has an armature, which can be deflected to both sides from a centre position, and an electric coil, which is located radially outside the armature and can be energized in opposite directions. The armature and the electric coil are separated from one another by means of a tubular element, which is arranged between them and separates the coil from a pressure medium filled armature space. The linear motor has two axially magnetized permanent magnets, which are installed with opposite polarity within the coil. The tubular element is configured as a substantially sleeve-shaped pressure tube, which receives the armature and at an outer circumference thereof the permanent magnets are arranged. The pressure tube has two non-magnetic intermediate elements, which form two pole shoes.

<CIT> discloses a discloses a linear motor which has permanent magnets that are separated by a yoke.

<CIT> discloses a magnet which has a moving magnet part comprising an armature, which is dynamically coupled to a shut-off needle. The moving magnet part is provided with a permanent magnet part, i.e. an axially magnetized ring magnet part, which is arranged such that the permanent magnet part exerts additional magnetic force on the armature in movement direction. A pole ring is arranged between magnetic rings. The armature is displaced within the magnetic rings, which are coaxially arranged with each other. The magnetic rings and the pole ring are held by fixing- and/or guiding tubes. The magnetic rings and the pole ring are provided in a fixed tube made of non-magnetic material.

In view of the foregoing, it is an object of the present disclosure to provide a single coil apparatus and method.

The invention is defined by claims <NUM> to <NUM>.

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.

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 +/- <NUM> from center. It should be appreciated that embodiments include a single coil solenoid having a stroke length of greater or less than +/-<NUM> 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>, shown is a cross-sectional view of a device <NUM> suitable for use in practicing exemplary embodiments of the present disclosure. Generally the device <NUM>, such as in the configuration of a solenoid assembly, includes a core tube <NUM>, 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> is the device <NUM> having the core tube <NUM> defining a hollow core <NUM> extending along a longitudinal axis. The core tube <NUM> includes a first ferromagnetic end section or piece <NUM> having a confronting end <NUM> and a second ferromagnetic end section or piece <NUM> having a confronting end <NUM>, wherein the confronting ends are longitudinally spaced along the longitudinal axis. The core tube <NUM> also includes a first non-ferromagnetic section, such as a first spacer <NUM> adjacent the confronting end <NUM> and a second non-ferromagnetic section, such as a spacer <NUM> adjacent to and contacting the confronting end <NUM>. The core tube <NUM> includes a ferromagnetic central spacer <NUM> longitudinally intermediate the non-ferromagnetic spacer <NUM> and the non-ferromagnetic spacer <NUM>. The core tube <NUM> 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 <NUM>, <NUM> includes a respective axially extending protrusion or shoulder <NUM>, <NUM> mating with a corresponding axial shoulder <NUM>, <NUM> of the respective first and second non-ferromagnetic sections <NUM>, <NUM>, wherein the shoulders <NUM>, <NUM> are radially inward of the shoulders <NUM>, <NUM> and form a portion of the inside surface of core tube <NUM>. In this regard, the ferromagnetic end piece <NUM> radially underlies a portion of the non-ferromagnetic section <NUM> and the ferromagnetic end piece <NUM> radially underlies a portion of the non-ferromagnetic section <NUM>.

The first and second non-ferromagnetic sections, spacers <NUM>, <NUM> 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 <NUM> within the hollow core <NUM> in response to magnetic flux created by the wound coil <NUM>. The armature assembly includes a push-pull rod <NUM> and an armature <NUM>. The push-pull rod <NUM> carrying the armature <NUM> is disposed within at least a portion of the hollow core <NUM>. The push-pull rod <NUM> is moveable along the longitudinal axis within hollow core <NUM>.

The armature <NUM> is disposed on the push-pull rod <NUM>, and defines an outer diameter that is greater than an adjacent portion of the push-pull rod <NUM>.

A first bearing <NUM> can be located between the push-pull rod <NUM> and the first ferromagnetic end piece <NUM>, and a second bearing <NUM> located between the push-pull rod <NUM> and the second ferromagnetic end piece <NUM>, wherein the hollow core <NUM> (also referred to as a cavity) is partly defined thereby. In one configuration, the first and the second bearing <NUM>, <NUM> support the push-pull rod <NUM>. While the solenoid assembly is shown with the first and second bearings <NUM>, <NUM> it is understood alternative mechanisms can be employed for enabling relative motion between the push-pull rod <NUM> (and armature) and the core tube <NUM>. It is understood the bearings <NUM>, <NUM> can be made of ferromagnetic or non-magnetic materials.

In an alternative construction, it is contemplated a low friction core liner <NUM> can be disposed on an inside surface of the core tube <NUM>. The core liner and outer diameter (surface) of the armature can thus provide the sliding interface between the armature and the core tube <NUM>. The low friction core liner <NUM> 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 <NUM>, or the inside surface of the core tube <NUM> or both to provide the bearing surface between the two components.

As depicted in <FIG>, when the coil assembly is not powered, the push-pull rod <NUM> is in a zero, or neutral or center position, which is radially inward from and equally spaced from permanent magnets <NUM>, <NUM>. Push-pull rod <NUM> is centered at the zero, neutral, or centered position by mechanical positioning or force from compression springs (e.g., meandering springs <NUM> shown in <FIG>) that are compressed against hard stops or first and second ferromagnetic end sections <NUM>, <NUM> (e.g., with a spring centered spool valve). Push-pull rod <NUM> with armature <NUM> 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 <NUM> and the second bearing <NUM>, 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 <NUM> 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 <NUM>. The magnet assembly is generally cylindrically shaped and sized to slideably receive the core tube <NUM> and be slideably received within the excitation coil assembly.

The magnet assembly includes a cylindrically shaped first permanent magnet <NUM>, a second permanent magnet <NUM> and at least one ferromagnetic spacer(s) <NUM>, wherein the ferromagnetic spacer is axially intermediate the first permanent magnet and the second permanent magnet. Referring to <FIG>, shown is an exemplary cylindrically shaped permanent magnet <NUM> (e.g., first or second permanent magnet <NUM>, <NUM>). In the embodiment depicted in <FIG>, permanent magnet <NUM> is one unitary piece such that permanent magnet <NUM> is operable to circumscribe core tube <NUM>. It should be appreciated that in an alternative embodiment, permanent magnet <NUM> may not be a single unitary piece, but can comprise a plurality of pieces <NUM> that when combined circumscribe the entire outside surface of core tube <NUM> (shown in <FIG>). It should be appreciated that while <FIG> depicts spaces between each piece <NUM>, in practice, each piece <NUM> will be in contact with the adjacent pieces to circumscribe the outside surface of core tube <NUM> such that there are no spaces between pieces <NUM>. In yet another embodiment illustrated at reference character <NUM>, permanent magnet <NUM> comprises a plurality of pieces <NUM> that when combined do not fully circumscribe the outside surface of core tube <NUM>. In this embodiment, each piece <NUM> is spaced from one another around the outside surface of core tube <NUM>. While <FIG> only depicts <NUM> pieces <NUM>, it should be appreciated that embodiments include more or less pieces <NUM> than <NUM>. In one embodiment, pieces <NUM> are evenly spaced around the outside surface of core tube <NUM>. In another embodiment pieces <NUM> are not evenly spaced around the outside surface of core tube <NUM>. The magnet assembly is sized to locate the magnets <NUM>, <NUM> and the ferromagnetic spacer outside the outer diameter of the core tube <NUM>. The components of the magnet assembly can be connected or bonded together or assembled and retained in an operable position about the core tube <NUM>. The at least one ferromagnetic spacer <NUM> contacts magnets <NUM>, <NUM> and is located approximately centered over ferromagnetic spacer <NUM> as shown in <FIG>. Embodiments of ferromagnetic spacer <NUM> including a non-ferrous section intermediate along the longitudinal axis of ferromagnetic spacer <NUM>. In this embodiment, ferromagnetic spacer <NUM> (shown in <FIG>) includes ferromagnetic spacer <NUM> and ferromagnetic spacer <NUM>. Longitudinally intermediate ferromagnetic spacer <NUM> and ferromagnetic spacer <NUM> is non-ferrous spacer <NUM>. Non-ferrous spacer <NUM> can be made of any non-ferrous material, such as a non-ferrous metal. Non-ferrous spacer <NUM> is bonded or affixed to ferromagnetic spacer <NUM> and ferromagnetic spacer <NUM> such that a sealed interface is created between ferromagnetic spacer <NUM>, non-ferrous spacer <NUM> and ferromagnetic spacer <NUM> operable to prevent a fluid from passing through the sealed interface.

As shown in <FIG>, the magnets <NUM>, <NUM> are oriented along the longitudinal axis such that like poles of the magnets are nearest or facing each other. Referring to <FIG>, the south pole of each magnet <NUM>, <NUM> are facing one another. Alternative embodiments include the north pole of each magnets <NUM>, <NUM> facing one another. The magnets <NUM>, <NUM> are longitudinally spaced from one another along the longitudinal axis by the at least one ferromagnetic spacer <NUM>. In this regard, the magnets <NUM>, <NUM> are positioned such that like magnetic poles are facing one another and separated by the at least one ferromagnetic spacer <NUM>. In other words, the at least one ferromagnetic spacer <NUM> is longitudinally intermediate magnet <NUM> and magnet <NUM>. As shown in <FIG>, the at least one ferromagnetic spacer <NUM> is located at the same or common longitudinal position and has the same approximate longitudinal dimension as the ferromagnetic spacer <NUM>. Embodiments include two or more ferromagnetic spacers <NUM> located longitudinally between magnets <NUM>, <NUM>. Embodiments further include ferromagnetic spacer <NUM> including a gap between the ferromagnetic spacers <NUM>. For example, as shown in <FIG>, ferromagnetic spacer <NUM> includes ferromagnetic spacer <NUM> and <NUM> each spaced from one another along the longitudinal axis by gap <NUM>. Embodiments include gap <NUM> 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 <NUM> 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 <NUM> and <NUM> with respect to one another are maintained such that the size or volume of the gap <NUM> remains constant by a spring <NUM>. Spring <NUM> is in contact with the face of ferromagnetic spacers <NUM> and <NUM> that face each other to urge ferromagnetic spacers <NUM>, <NUM> away from one another to maintain gap <NUM>. Embodiments of spring <NUM> include a wave spring, o-ring, or any other non-magnetic spring. In another embodiment, gap <NUM> can be replaced with a non-ferrous material, such as a metal. In this embodiment, the interior facing lateral sides of ferromagnetic spacers <NUM> that are facing one another would be in contact with a non-ferrous material, such a non-ferrous metal.

It is contemplated the magnets <NUM>, <NUM> and the spacer <NUM> can be operably retained by bonding or mechanical retention. For example, in one configuration the magnets <NUM>, <NUM> 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 <NUM>, <NUM> relative to core tube <NUM> during operation. Alternatively, as set forth below the magnets <NUM>, <NUM> can be operably retained by a bias mechanism, such as by a spring as shown in <FIG>.

Embodiments of ferromagnetic spacer <NUM> 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 <NUM>, the magnets <NUM>, <NUM> are respectively spaced radially outward from the inside surface of the hollow core <NUM> as shown in <FIG> by the two non-ferromagnetic spacers <NUM>, <NUM>. The ferromagnetic spacer <NUM> is located radially inward of and longitudinally intermediate magnets <NUM>, <NUM> along the inside surface of the hollow core <NUM>. Non-ferromagnetic spacer <NUM> is located radially inward and adjacent to magnet <NUM> along the inside surface of core tube <NUM>. In other words, non-ferromagnetic spacer <NUM> and a portion of magnet <NUM> occupy a common position along the longitudinal axis of device <NUM>. Non-ferromagnetic spacer <NUM> is located radially inward and adjacent to magnet <NUM> along the inside surface of core tube <NUM>. In other words, non-ferromagnetic spacer <NUM> and a portion of magnet <NUM> occupy a common position along the longitudinal axis of device <NUM>.

The shoulders <NUM>, <NUM> of the respective ferromagnetic end pieces <NUM>, <NUM> axially extend into the respective non-ferromagnetic sections <NUM>, <NUM> along the inside surface of hollow core <NUM> such that the radially outside portion of ferromagnetic end pieces <NUM>, <NUM> terminates longitudinally at approximately the longitudinal end of the magnets <NUM>, <NUM>, while the shoulders (protrusions) <NUM>, <NUM> extend passed the lateral edge of magnets <NUM>, <NUM> to terminate within the longitudinal dimension of the respective magnet. The protrusions <NUM>, <NUM> do not extend further than the entire length of magnets <NUM>, <NUM>, respectively along the longitudinal direction. Embodiments of device <NUM> do not require magnets located at the end of the stroke length of armature <NUM> that are meant to alter the magnetic forces acting on the armature <NUM>.

The excitation coil assembly includes a housing, a frame within the housing and a wound coil <NUM> disposed about the frame, wherein the assembly is disposed radially outward from the magnets <NUM>, <NUM> and thus is disposed about and encompasses the magnets and the core tube <NUM>. The wound coil <NUM> is operable to have a current passed through the coil to create a magnetic flux. Some non-limiting embodiments of wound coil <NUM> can be made of copper or aluminum insulated magnet wire. Embodiments also include the wound coil <NUM> being operable to conduct a current by a pulse-width modulation signal. The direction of movement of armature <NUM> is determined by the polarity of the electrical current applied to the wound coil <NUM>, the direction of the winding of the wound coil, and the orientation of the polarity of magnets <NUM>, <NUM>.

The armature <NUM> has an approximate zero, center, or neutral position relative to magnets <NUM>, <NUM> which is depicted in <FIG>. The zero, center, or neutral position of the armature <NUM> is when the armature is located longitudinally symmetrically centered with respect to the magnets and the at least one ferromagnetic spacer <NUM>. Embodiments include ferromagnetic spacer <NUM> including two or more ferromagnetic spacers. The armature <NUM> is operable to move longitudinally through the hollow core <NUM> of the core tube <NUM> along the longitudinal axis of device <NUM> from left or right from the zero, center, or neutral position, as seen in <FIG>. The direction the armature <NUM> moves is dependent on the polarity of the current that passes through wound coil <NUM> and the orientation of the magnets <NUM>,<NUM>.

In one embodiment, the bearings <NUM>, <NUM> are replaced with meandering springs <NUM> (shown in <FIG>). Embodiments of the meandering springs <NUM> are operable to aid in centering the armature <NUM> to its zero, center, or neutral position relative to magnets <NUM>, <NUM> and ferromagnetic spacer <NUM> when no current is passing through the wound coil <NUM>. The meandering spring <NUM> is thus operable to aid in centering the armature <NUM> by physically urging and moving rod <NUM> with the armature <NUM> to its zero, center, or neutral position.

Referring to <FIG>, shown is an alternative embodiment of device <NUM> suitable for performing exemplary embodiments of the present disclosure. Illustrated in <FIG> is device <NUM> in the configuration of a solenoid having a fixed excitation coil assembly having a wound coil <NUM>, a fixed magnet assembly with magnets <NUM>, <NUM>, with a ferromagnetic spacer <NUM>, a core tube <NUM>, and a ferromagnetic armature assembly.

The core tube <NUM> includes a ferromagnetic spacer <NUM> longitudinally intermediate non-ferromagnetic spacers <NUM>, <NUM>, which in turn are respectively bounded by first and second ferromagnetic end pieces <NUM>, <NUM>.

In the fixed magnet assembly of this embodiment, a ferromagnetic spacer <NUM> is longitudinally intermediate the magnets <NUM>, <NUM>, which in turn are longitudinally bounded by ferromagnetic ends pieces <NUM>, <NUM> respectively.

In this configuration each of the first and second ferromagnetic end pieces <NUM>, <NUM> includes a respective axially extending protrusion or shoulder <NUM>, <NUM> mating with a corresponding axial shoulder <NUM>, <NUM> of the respective first and second non-ferromagnetic sections <NUM>, <NUM>, wherein the shoulders <NUM>, <NUM> are radially inward of the shoulders <NUM>, <NUM> and form a portion of the inside surface of core tube <NUM>. In this regard, the ferromagnetic end piece <NUM> radially underlies a portion of the non-ferromagnetic section <NUM> and the ferromagnetic end piece <NUM> radially underlies a portion of the non-ferromagnetic section <NUM>. The longitudinal dimension of the shoulder with respect to the radially outward magnet is between approximately <NUM>% to <NUM>% of the axial dimension of the magnet.

Axial retention of the ferromagnetic spacer <NUM> and the bounding magnets <NUM>, <NUM>, which in turn are longitudinally bounded by ferromagnetic ends pieces <NUM>, <NUM> can be accomplished by a bias mechanism, such as a spring <NUM>. The spring <NUM> is operable to be located between a portion of the coil assembly and one of the ferromagnetic end pieces <NUM> and/or <NUM> such that the spring urges and maintains a force on the magnets <NUM>, <NUM>, the ferromagnetic spacer <NUM>, and the ferromagnetic ends <NUM>. In one embodiment, the spring <NUM> is a Belleville spring.

In this embodiment, the wound coil assembly, the magnets <NUM>, <NUM>, the ferromagnetic spacer <NUM>, and the ferromagnetic ends <NUM>, <NUM> are operable to slideably move along the longitudinal axis over the core tube <NUM> including the ferromagnetic spacer <NUM>, and the non-ferromagnetic spacers <NUM>, <NUM> such that coil assembly (e.g., in the event of failure of wound coil <NUM>) can be removed without needing to disassemble the core tube <NUM>. This embodiment thus allows replacement of the wound coil <NUM>, and/or the magnets <NUM>, <NUM> without the risk of fluid leaking from the hollow core <NUM>.

In this regard, the core tube <NUM> defines an inner surface that is a sealed surface. Embodiments further include the core tube <NUM> defining an inner surface that is a fluid tight surface, which substantially prevents the passage of fluid there through. Additionally, the magnets <NUM>, <NUM> are removeable such that they can be replaced without disrupting the integrity of the core tube <NUM>. The magnets <NUM>, <NUM> are mounted with a close slip fit I. of magnet to OD. of core tube <NUM> Embodiments include the core tube <NUM> (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 <NUM> can be removed without fluid leaking from hollow core <NUM> because the core tube <NUM> (including non-ferrous spacers <NUM>, <NUM>, and ferrous spacer <NUM>) remains intact. In this embodiment, magnets <NUM>, <NUM> ferrous spacers <NUM>, <NUM> and spring <NUM> are operable to slideably receive core tube <NUM>, and wound coil assembly including the wound coil <NUM> is operable to slideably receive the magnets <NUM>, <NUM> ferrous spacers <NUM>, <NUM> and spring <NUM>.

Embodiments of device <NUM> and device <NUM> provide that core tube <NUM>, <NUM> are operable to maintain a high internal fluid pressure between <NUM> to <NUM>,<NUM> PSIA. However, it should be appreciated that embodiments include an internal core tube <NUM> fluid pressure greater than <NUM>,<NUM> PSIA. Embodiments provide that the core tube <NUM> has a diameter ranging between <NUM> to <NUM> inches. However, it should be appreciated that embodiments includes a core tube <NUM> having a diameter that is smaller than <NUM> inches or greater than <NUM> inches. Embodiments provide that core tube <NUM> has an internal diameter is generally smaller than present cores due to the placement of magnets <NUM>, <NUM> (or <NUM>, <NUM>), which allows for a thinner core tube <NUM> wall is operable to maintain a higher working pressure within the hollow core <NUM>. Embodiments of magnets <NUM>, <NUM> (and <NUM>, <NUM>) 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 <FIG> 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 <NUM> and device <NUM> are operable such that a magnetic field or magnetic flux is created when current passes through wound coil <NUM>. The magnetic flux urges or causes armature <NUM> (with rod <NUM>) to move through the longitudinal axis of hollow core <NUM>. The distance through which armature <NUM> moves is referred to as the stroke length. Embodiments of the present disclosure provide an increased stroke length of between <NUM> to <NUM> inches. Embodiments of the present disclosure provide an increase stroke length of greater than <NUM> inches. Embodiments provide that device <NUM> is operable to cause or urge armature <NUM> to move in one direction through core tube <NUM> along the longitudinal axis of device <NUM> in response to the current flowing through wound coil <NUM> having a first polarity. Embodiments provide that device <NUM> is operable to cause or urge armature <NUM> to move in an opposite direction through core tube <NUM> along the longitudinal axis of device <NUM> in response to the current flowing through wound coil <NUM> having a second polarity. In this embodiment, the first polarity is different from the second polarity. In this regard, embodiments of device <NUM> are operable to cause armature <NUM> to move in both (push and pull) directions through the longitudinal axis of core tube <NUM>. That is, the solenoid assembly can provide bidirectional movement by reversing the polarity to the single wound coil.

Referring to <FIG>, 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> indicates the stroke length in inches (<NUM> inch is equal to <NUM>) along the x-axis and pounds of force (<NUM> pound of force (lbf) is equal to <NUM> N) along the y-axis. Each curve on the graph illustrates how force from a device <NUM> changes over a given stroke length in the pull direction while a particular current (i.e., amps) is passed through the wound coil <NUM>. As depicted, the force stroke curve for <NUM> milliamps, <NUM> milliamps, <NUM>
milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, and <NUM> milliamps are shown. Embodiments provide that a particular position of the armature <NUM> relative to the core tube <NUM> can be controlled by the flow of current through wound coil <NUM> up to at least a stroke length of <NUM>. Stroke length refers to the total distance traveled along the longitudinal axis of the device <NUM> of the armature <NUM> relative to the core tube <NUM> in a single direction. It should be appreciated that the force stroke curve lines shown in <FIG> relate to the device <NUM> having the magnets <NUM>, <NUM> wherein the south pole of the magnets are facing one another. The spring constant associated with spring <NUM> will affect the stroke length to the extent that the spring constant of spring <NUM> enables spring <NUM> to oppose movement forces of armature <NUM> based on the applied milliamps to the wound coil.

Referring to <FIG>, 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> 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 <NUM> changes over a given stroke length in the push direction while a particular current (i.e., amps) is passed through the wound coil <NUM>. As depicted, the force stroke curve for <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, and <NUM> milliamps are shown. Embodiments provide that a particular position of the armature <NUM> relative to the core tube <NUM> can be controlled by the flow of current through the wound coil <NUM> up to at least a stroke length of <NUM>. It should be appreciated that the force stroke curve lines shown in <FIG> relate to the device <NUM> having the magnets <NUM>, <NUM> wherein the south pole of magnets are facing one another.

Referring to <FIG>, 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> is a graph illustrating a stroke curve of a device with reversed polarity in the pull direction. Reversed polarity refers to the device <NUM> having the magnets <NUM>, <NUM> wherein the north poles of the magnets are facing one another. The graphs shown in <FIG> and <FIG> indicate the stroke length in inches (<NUM> inch is equal to <NUM>) along the x-axis and pounds of force (<NUM> pound of force (lbf) is equal to <NUM> N) along the y-axis. Each curve on the graphs illustrate how force from a device <NUM> changes over a given stroke length in the pull direction while a particular current (i.e., amps) is passed through the wound coil <NUM>. As depicted, the force stroke curve for <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, <NUM> milliamps, and <NUM> milliamps are shown.

Referring to <FIG>, 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> is device <NUM> having magnets <NUM>, <NUM>, a wound coil <NUM>, ferromagnetic spacers <NUM>, <NUM>, non-ferromagnetic spacers <NUM>, <NUM>, ferromagnetic ends <NUM>, <NUM>, and an armature <NUM>. In this embodiment there is no physical stop for the movement of armature <NUM> along the pull direction (indicated by line <NUM>). This embodiment includes a gap <NUM> which allows armature <NUM> to have a greater range of movement in the pull direction than in the push direction since ferrous end <NUM> provides a physical stop for armature <NUM> in the push direction. Embodiments provide that gap <NUM> allows for movement of armature <NUM> along the pull direction to be greater than <NUM> inches from armature <NUM>'s zero position. Embodiments provide that gap <NUM> allows for movement of armature <NUM> along the pull direction to be greater than. Embodiments of device <NUM> provide that wound coil <NUM> is operable to have a current passed through it, which creates a magnetic flux that is operable to urge or move armature <NUM> through the longitudinal axis of core tube <NUM>. The magnetic flux created by the current that passes through wound coil <NUM> is shown by concentric lines <NUM>. Due to gap <NUM>, concentric lines <NUM> do not extend into hollow core <NUM> of device <NUM>. Embodiments provide that core tube <NUM> is operable to maintain a fluid (e.g., liquid and/or gas) that allows for movement of armature <NUM> through hollow core <NUM>. Embodiments provide that core tube <NUM> is operable to maintain a gaseous media that allows for movement of armature <NUM> through hollow core <NUM>.

Referring to <FIG>, 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> is device <NUM> having magnets <NUM>, <NUM>, wound coil <NUM>, ferrous spacers <NUM>, <NUM>, non-ferrous spacers <NUM>, <NUM>, ferrous ends <NUM>, <NUM>, and armature <NUM>. This embodiment also includes a gap <NUM> which allows armature <NUM> to have a greater range of movement in the pull direction (shown in <FIG>) than in the push direction (indicated by line <NUM>) since ferrous end <NUM> provides a physical stop for armature <NUM>. Embodiments of device <NUM> provide that wound coil <NUM> is operable to have current passed through it, which creates a magnetic flux that is operable to urge or move armature <NUM> through the longitudinal axis of core tube <NUM>. The magnetic flux created by the current that passes through wound coil <NUM> is shown by concentric lines <NUM>.

Reference is now made to <FIG>, which depicts an exemplary graph of a force stroke performance finite element analysis (FEA) curve. This graph shows the performance of embodiments of device <NUM> with no bearing located in the magnetic circuit path in the pull direction. In other words, there is a gap <NUM> which allows for greater range of movement in the pull direction for armature <NUM>. As is evident, the force curve performance illustrated in <FIG> is relatively the same as that shown in <FIG> for a device having no gap located in the pull direction of the armature. Embodiments of device <NUM> 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 <NUM> such that the bearing does not fall within the magnetic flux path.

Referring to <FIG>, presented is an exemplary logic flow diagram in accordance with a method, and apparatus for performing exemplary embodiments of this disclosure. Block <NUM> 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 <NUM> 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> following block <NUM>. Block <NUM> specifies wherein proximal poles of the first magnet and the second magnet are like. Block <NUM> states wherein the first nonmagnetic section contacts the first confronting end of the first ferromagnetic end section of the core tube. Then block <NUM> relates to wherein the second nonmagnetic section contacts the second confronting end of the second ferromagnetic end section of the core tube. Next block <NUM> 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 <NUM> 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> 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> 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 +/-<NUM> relative to the armature'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 +/-<NUM>. 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 <NUM>-<NUM>,<NUM> PSIA. However, embodiments provide an internal fluid pressure of core tube greater than <NUM>,<NUM> 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>, which illustrates a cross-sectional view of another exemplary device <NUM>. Shown in <FIG> is device <NUM> having a core tube <NUM> that includes ferromagnetic spacer <NUM> and non-ferromagnetic spacers <NUM>, <NUM>. Radially outside core tube <NUM> are magnets <NUM>, <NUM> separated by ferromagnetic spacer <NUM>. In the embodiment shown in <FIG>, ferromagnetic spacer <NUM> includes a gap <NUM>, however, it should be appreciated that embodiments include ferromagnetic spacer <NUM> being made of a single solid material without a gap. Radially outside magnets <NUM>, <NUM> is wound coil <NUM>.

Also shown in <FIG> is armature <NUM>. Armature <NUM> includes inwardly radially angled sides <NUM>, <NUM> that are shaped such that each radial end of armature <NUM> along its longitudinal axis are conically shaped. Core tube <NUM> includes angled shoulders <NUM>, <NUM> that are angled radially inward to correspond to the angled sides <NUM>, <NUM>. Angled shoulders <NUM>, <NUM> extend radially underneath non-ferromagnetic spacers <NUM>, <NUM> within hollow core <NUM>. However, angled shoulders <NUM>, <NUM> do not extend underneath the entire length of non-ferromagnetic spacers <NUM>, <NUM>. In this regard, angled shoulders <NUM>, <NUM> only underlie a portion of non-ferromagnetic spacers <NUM>, <NUM>.

Referring to <FIG>, which illustrates a cross-sectional view of another exemplary device <NUM>. Shown in <FIG> is device <NUM> having a core tube <NUM> that includes ferromagnetic spacer <NUM> and non-ferromagnetic spacers <NUM>, <NUM>. Radially outside core tube <NUM> are magnets <NUM>, <NUM> separated by ferromagnetic spacer <NUM>. In the embodiment shown in <FIG>, ferromagnetic spacer <NUM> includes a gap <NUM>, however, it should be appreciated that embodiments include ferromagnetic spacer <NUM> being a single piece without a gap <NUM>. Radially outside magnets <NUM>, <NUM> is wound coil <NUM>. Also shown is armature <NUM> operable to move through the hollow core <NUM>. Armature <NUM> includes indentations <NUM>, <NUM> located on the long ends of armature <NUM>. Core tube <NUM> includes protruding surfaces <NUM>, <NUM> on either side of armature <NUM>. Protruding surfaces <NUM>, <NUM> correspond to the indentations <NUM>, <NUM> located on the longitudinal axis ends of armature <NUM> such that protruding surfaces <NUM>, <NUM> fit within indentations <NUM>, <NUM>. Embodiments include the protruding surfaces <NUM>, <NUM> being cone shaped and indentations <NUM>, <NUM> being inwardly cone shaped to correspond with the shape of protruding surfaces <NUM>, <NUM>.

Referring now to <FIG>, shown is a cross-sectional view of another exemplary device <NUM>. Shown in <FIG> is device <NUM> having a core tube <NUM> that includes ferromagnetic spacer <NUM> and non-ferromagnetic spacers <NUM>, <NUM>. Radially outside core tube <NUM> are magnets <NUM>, <NUM> separated by ferromagnetic spacer <NUM>. In the embodiment shown in <FIG>, ferromagnetic spacer <NUM> includes an gap <NUM>. It should be appreciated that embodiments include ferromagnetic spacer <NUM> being made of a single piece without a gap <NUM>. Radially outside magnets <NUM>, <NUM> is wound coil <NUM>.

Device <NUM> also includes armature <NUM> operable to move through the hollow core <NUM>. Armature <NUM> includes flat edges <NUM>, <NUM> located on the long ends of armature <NUM>. Core tube <NUM> includes flat ends <NUM>, <NUM> on either side of armature <NUM>. Flat ends <NUM>, <NUM> have a surface shape that corresponds to the flat edges <NUM>, <NUM>. Embodiments include flat edges <NUM>, <NUM> being substantially <NUM> degrees from the radial surface of armature <NUM>. In this embodiment, flat ends <NUM>, <NUM> is positioned to correspond to flat edges <NUM>, <NUM> such that flat ends <NUM>, <NUM> are substantially parallel to flat edges <NUM>, <NUM>. In this embodiment, core tube <NUM> is made of a single unitary piece of stainless steel (e.g., chromium-nickel-aluminum, austenitic stainless steel <NUM>-7PH) rather than having multiple pieces of ferromagnetic and non-ferromagnetic material that are welded together. In this embodiment, the core tube <NUM> is annealed such that a portion of core tube <NUM> portions becomes non-magnetic (e.g., spacers <NUM>, <NUM>). In other words, embodiments of core tube <NUM> include having a uniform integral one-piece design and then annealing the portion of the core tube <NUM> radially inward from magnets <NUM>, <NUM> such that those annealed areas exhibit non-ferromagnetic or non-magnetic properties.

Reference is now made to <FIG>, which shown is a cross-sectional view of another exemplary device <NUM>. Shown in <FIG> is device <NUM> having a core tube <NUM> that includes non-ferromagnetic spacer <NUM>. Radially outside core tube <NUM> are magnets <NUM>, <NUM> separated by ferromagnetic spacer <NUM>. In the embodiment shown in <FIG>, ferromagnetic spacer <NUM> includes a gap <NUM>. Embodiments include ferromagnetic spacer <NUM> being a single piece without a gap <NUM>. Radially outside magnets <NUM>, <NUM> is wound coil <NUM>. As illustrated in <FIG>, core tube <NUM> is made of a single non-ferromagnetic material since it does not include any ferromagnetic spacers within the core tube <NUM>. Accordingly, magnets <NUM>, <NUM> are located radially outside from a non-ferromagnetic core tube <NUM>. Likewise, ferromagnetic spacer <NUM> with gap <NUM> are located radially outside non-ferromagnetic core tube <NUM>. It should be appreciated that in this embodiment, magnetic flux created by current passing through coil <NUM> will not pass through core tube <NUM> as easily as the embodiments set forth above, which may cause the force created by movement of armature <NUM> to be less than that found in the other embodiments.

Device <NUM> also includes armature <NUM> operable to move through the hollow core <NUM>. Armature <NUM> includes steps <NUM>, <NUM> located on the radial edge of armature <NUM> such that steps <NUM>, <NUM> circumscribe the radial edge of armature <NUM>. Core tube <NUM> includes ridges <NUM>, <NUM> on either side of armature <NUM>. Ridges <NUM>, <NUM> have a shape that corresponds to the steps <NUM>, <NUM> such that ridges <NUM>, <NUM> are sized to fit within steps <NUM>, <NUM>, respectively. Embodiments include steps <NUM>, <NUM> extending along the long axis (the long axis is the same axis that armature <NUM> is operable to move through) such that the steps <NUM>, <NUM> only extend through a portion of the long axis of armature <NUM>. In this regard, steps <NUM>, <NUM> do not extend the entire length of armature <NUM>. Embodiments include steps <NUM>, <NUM> being positioned relative to the core tube <NUM> end piece such that the core tube <NUM> end piece is substantially <NUM> degrees with respect to steps <NUM>, <NUM>. Likewise, embodiments include ridges <NUM>, <NUM> are positioned substantially <NUM> degrees with respect to the long axis edge of armature <NUM>.

Referring to <FIG>, shown is a cross-sectional view of another exemplary device <NUM>. Shown in <FIG> is device <NUM> having a core tube <NUM> that is made of a single unitary non-ferromagnetic material. Radially outside core tube <NUM> are magnets <NUM>, <NUM> separated by ferromagnetic spacer <NUM>. Ferromagnetic spacer <NUM> includes a gap <NUM>. Although shown as having a gap <NUM>, embodiments include ferromagnetic spacer <NUM> being a single piece without a gap <NUM>. Radially outside magnets <NUM>, <NUM> is wound coil <NUM>. Also shown in <FIG> is armature <NUM> operable to move through the longitudinal axis of device <NUM>. Armature <NUM> includes bores <NUM>, <NUM> located on the longitudinal ends of armature <NUM>. Bores <NUM>, <NUM> are defined by the radial edge <NUM> of armature <NUM> such that radial edge <NUM> extends along the longitudinal axis further than bore <NUM>, <NUM>. Core tube <NUM> includes extensions <NUM>, <NUM> which extend longitudinally inward toward armature <NUM>. Extensions <NUM>, <NUM> are spaced from the radial inside surface of core tube <NUM>. Thus, the radial edge of extensions <NUM>, <NUM> and the radial inside surface of core tube <NUM> define a space <NUM>, <NUM>, respectively. Space <NUM>, <NUM> are sized to maintain or accommodate radial edge <NUM>. Likewise, bores <NUM>, <NUM> are sized to maintain or accommodate extensions <NUM>, <NUM>.

Reference is now made to <FIG>, which shows a cross-sectional view of another exemplary device <NUM>. Illustrated in <FIG> is device <NUM> having an excitation coil <NUM>, an armature <NUM>, and a core tube <NUM> including ferromagnetic spacer <NUM> and non-ferromagnetic spacers <NUM>, <NUM>. Radially outside core tube <NUM> are magnets <NUM>, <NUM> separated by ferromagnetic spacer <NUM>. Armature <NUM> is operable to move through the cavity <NUM> defined by core tube <NUM> in either the push or pull direction in response to current passing through excitation coil <NUM>. Ferromagnetic spacer <NUM> includes a gap <NUM>. Although shown as having a gap <NUM>, embodiments include ferromagnetic spacer <NUM> being a single piece without a gap <NUM>. In the embodiment shown in <FIG>, gap <NUM> is located approximately in the midsection or middle of spacer <NUM>. However, it should be appreciated that gap <NUM> can be located adjacent to the midsection of spacer <NUM>. Radially outside magnets <NUM>, <NUM> is wound coil <NUM>. Device <NUM> also includes armature <NUM> operable to move through the longitudinal axis (as indicated by line <NUM>) of device <NUM>.

Reference is now made to <FIG>, which illustrates a close-up cross-sectional view of device <NUM>. Similar to <FIG>, <FIG> depicts magnets <NUM>, <NUM>, ferromagnetic core tube <NUM>, ferromagnetic spacer <NUM>, ferromagnetic spacer <NUM> with gap <NUM> and non-ferromagnetic spacers <NUM>, <NUM>. The core tube <NUM> includes two channels <NUM>, <NUM> that circumscribe the radial outside surface of core tube <NUM>. Channels <NUM>, <NUM> each include at least a first surface <NUM>, <NUM> that is angled radially inward toward spacer <NUM> (e.g., between <NUM> degrees to <NUM> degrees from the surface of core tube <NUM>), and a second surface <NUM>, <NUM> angled radially outward toward spacer <NUM>. Each channel <NUM>, <NUM> is comprised of non-ferromagnetic material that form spacers <NUM>, <NUM>, respectively. In other words, spacers <NUM>, <NUM> are not uniformly the same radial thickness along the longitudinal direction. Rather, the radial thickness of spacers <NUM>, <NUM> changes along the longitudinal direction. As shown in <FIG>, non-ferromagnetic spacers <NUM>, <NUM> do not have the same length along the longitudinal axis as magnets <NUM>, <NUM>. Rather embodiments include spacers <NUM>, <NUM> being coextensive with the portion of magnets <NUM>, <NUM> that is in contact with spacer <NUM>, but do not extend the entire length of magnets <NUM>, <NUM> in the longitudinal direction. In other words, spacers <NUM>, <NUM> terminate (i.e., the diameter of core tube <NUM> returns to the same uniform diameter) or have a length that is shorter in the longitudinal direction than magnets <NUM>, <NUM>. This also means that core tube <NUM> extends radially underneath a portion of magnets <NUM>, <NUM>. Embodiments include core tube <NUM> extending radially underneath <NUM>% to <NUM>% of the length of magnets <NUM>, <NUM> in the longitudinal direction.

Referring to <FIG>, shown is a cross-sectional view of another embodiment of device <NUM> suitable for practicing embodiments of this disclosure. Illustrated in <FIG> is a cross-sectional view of device <NUM> having magnets <NUM>, <NUM>, ferromagnetic core tube <NUM>, ferromagnetic spacer <NUM>, armature <NUM>, ferromagnetic spacer <NUM> with gap <NUM> and channel gaps <NUM>, <NUM>. As illustrated in <FIG>, spacer <NUM> is approximately the same length in the longitudinal direction as spacer <NUM> such that a portion of spacer <NUM> is radially inward from magnets <NUM>, <NUM>. It should be appreciated that in the embodiment shown in <FIG> channel gaps <NUM>, <NUM> are defined by the space between the outer radial surface of core tube <NUM> (i.e., created by the shunt or channel) and the inner radial surface of magnets <NUM>, <NUM>, respectively. Channel gaps <NUM>, <NUM> are created by the outer radial diameter of core tube <NUM> decreasing along angled surfaces <NUM>, <NUM> (e.g., between <NUM> degrees to <NUM> degrees relative to the outer radial surface of core tube <NUM>) and then increasing along angled surface <NUM>, <NUM>. Embodiments of channel gaps <NUM>, <NUM> can be formed by removing a portion of the core tube <NUM> radially inward from magnets <NUM>, <NUM> such that a channel that circumscribes the outside radial surface of core tube <NUM> is formed. It should be appreciated that the thickness (i.e., distance between the outside radial surface of core tube <NUM> and the radial outside surface of channel gaps <NUM>, <NUM>) is less than the wall thickness of core tube <NUM>. In other words, channel gaps <NUM>, <NUM> do not create a passageway between the interior and the exterior of core tube <NUM>. Rather, a portion of core tube <NUM> remains radially inward from magnets <NUM>, <NUM>. As depicted in <FIG>, channel gaps <NUM>, <NUM> do not have the same length in the longitudinal direction as magnets <NUM>, <NUM>. Thus, a portion of core tube <NUM> extends radially inward from magnets <NUM>, <NUM>. It should be appreciated that embodiments include channel gaps <NUM>, <NUM> have a length in the longitudinal direction equal to magnets <NUM>, <NUM> such that channel gap <NUM> is coextensive with magnet <NUM> and channel gap <NUM> is coextensive with magnet <NUM>. As shown in <FIG>, channel gaps <NUM>, <NUM> are located radially inward and adjacent to spacer <NUM>, however, embodiments include channel gaps <NUM>, <NUM> being located spaced from spacer <NUM> in the longitudinal direction. In this embodiment, core tube <NUM> is made of a single piece of ferromagnetic or steel material, which aides in maintaining the structural integrity of core tube <NUM> and the ability for core tube <NUM> to maintain a higher internal core pressure.

Armature <NUM> as shown in <FIG> is in the centered position relative to coil <NUM>. Armature is made of a ferrous material and is operable to move in both directions through the longitudinal axis <NUM> of core tube <NUM>. Movement of armature <NUM> is restricted by ends <NUM>, <NUM>.

Referring now to <FIG>, 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> is device <NUM> having magnets <NUM>, <NUM>, a wound coil <NUM>, ferromagnetic spacer <NUM>, ferromagnetic spacer <NUM>, gaps <NUM>, <NUM>, ferromagnetic ends <NUM>, <NUM>, and an armature <NUM>. In this embodiment, ferromagnetic spacer <NUM> includes an gap <NUM> that extends from the outer radial surface of ferromagnetic spacer <NUM> to the radially inner surface of ferromagnetic spacer <NUM>. It should be appreciated that in this embodiment gaps <NUM>, <NUM> are the same length in the longitudinal direction <NUM> as magnets <NUM>, <NUM>. However, it should also be appreciated that embodiments include gaps <NUM>, <NUM> not being coextensive or having the same length in the longitudinal direction as magnets <NUM>, <NUM>. Embodiments of device <NUM> provide that wound coil <NUM> is operable to have a current passed through it, which creates a magnetic flux that is operable to urge or move armature <NUM> through the longitudinal axis <NUM> of core tube <NUM>. The magnetic flux created by the current that passes through wound coil <NUM> is shown by concentric lines <NUM>. As shown in <FIG>, when current passes through coil <NUM>, magnetic flux is created and passes through magnets <NUM>, <NUM>, ferromagnetic spacers <NUM>, <NUM>, core tube <NUM>, armature <NUM> and a portion of gaps <NUM>, <NUM>. It should be noted that a portion of gaps <NUM>, <NUM> do not have magnetic flux passing through it. In other words, concentric lines <NUM> only partially extend into gaps <NUM>, <NUM>.

It should be appreciated that coil <NUM> is not located in the center in the longitudinal direction of magnets <NUM>, <NUM>, and spacer <NUM>. Rather, coil <NUM> is positioned such that coil <NUM> is predominately located radially outside magnet <NUM> and to the right of spacer <NUM>. In this embodiment, when current passes through coil <NUM>, the force created by the movement of armature <NUM> is greater in the direction in which coil <NUM> is positioned. In other words, the embodiment depicted in <FIG> provides for greater force in the direction to the right. Likewise, embodiments include coil <NUM> being positioned predominately radially outside magnet <NUM> such that greater force can be produced by the movement of armature <NUM> in the opposite direction to the left.

Claim 1:
A solenoid assembly (<NUM>) comprising:
(a) a core tube (<NUM>) extending along a longitudinal axis, the core tube having a first ferromagnetic end section (<NUM>) with a first confronting end (<NUM>) longitudinally spaced from a second ferromagnetic end section (<NUM>) with a second confronting end (<NUM>), a first non-ferromagnetic section (<NUM>) adjacent the first confronting end (<NUM>) and a second non-ferromagnetic section (<NUM>) adjacent the second confronting end (<NUM>), a first ferromagnetic spacer (<NUM>, <NUM>, <NUM>) longitudinally intermediate the first non-ferromagnetic section (<NUM>) and the second non-ferromagnetic section (<NUM>);
(b) a first magnet (<NUM>) and a second magnet (<NUM>) located outside the core tube (<NUM>), the first magnet (<NUM>) spaced along the longitudinal axis from the second magnet (<NUM>),
wherein a second ferromagnetic spacer (<NUM>) is longitudinally intermediate the first magnet (<NUM>) and the second magnet (<NUM>),
wherein the first non-ferromagnetic section (<NUM>) is radially inward of the second magnet (<NUM>) and the second non-ferromagnetic section (<NUM>) is radially inward of the first magnet (<NUM>); and
wherein the first ferromagnetic spacer (<NUM>, <NUM>, <NUM>) is radially inward of the second ferromagnetic spacer <NUM>, <NUM>, <NUM>); and
(c) an excitation coil (<NUM>) disposed radially outward of the first magnet (<NUM>) and the second magnet (<NUM>);
characterised in that the second ferromagnetic spacer (<NUM>) comprises a gap (<NUM>) extending from a radial outer surface of the second ferromagnetic spacer (<NUM>) to a radial inner surface of the second ferromagnetic spacer (<NUM>) forming second ferromagnetic spacers (<NUM>, <NUM>) each spaced apart from one another along the longitudinal axis by the gap (<NUM>), wherein the gap (<NUM>) is spaced apart longitudinally from the first magnet (<NUM>) and the second magnet (<NUM>);
wherein a spring (<NUM>) is in contact with the second ferromagnetic spacers (<NUM>, <NUM>) configured to maintain the gap (<NUM>).