Abstract:
A switching device is provided. An electromechanical switch controls rotation and/or lateral displacement of a core inside a housing with a magnetic field. The core is magnetically aligned by the magnetic relationship between the core and the housing. An energizing device generates a magnetic field that is sufficiently strong to realign the core with the generated magnetic field. As a result, the core switches to an energized state. When the generated magnetic field is removed, the core switches back to the natural state.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application Ser. No. 61/237,114 filed Aug. 26, 2009 and entitled MAGNETICALLY LOADED ELECTROMECHANICAL SWITCHES, which application is incorporated by reference in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. The Field of the Invention 
     Embodiments of the invention relate generally to electromechanical switches. More particularly, embodiments of the invention relate to the control of fluidic, pneumatic, electrical and optical switching devices with electromechanical switches. 
     2. The Relevant Technology 
     Electronically controlled switches utilize some form of electromagnetic design to generate a change in state for a specific application. These designs commonly include a coil for electronic control, a spring to assist in either closing or opening a point of control, and various designs for the point of control. The point of control for switches in electrical applications commonly includes contacts, while a port hole with some form of plugging mechanism is the point of control for valves and a lens assembly is the point of control for optical switches. 
     The operation of conventional switches often involves the use of a direct solenoid coil around a core which opens or closes the valve as energy is added or removed from the coil. Some MEMs (Micro-Electro-Mechanical System) designs utilize a cavity squeezing effect, whereby applying energy to a piezo material results in the closure of a cavity or diaphragm. 
     Currently, springs and hinge mechanism designs often assist in the operation of switches used in valve applications. Some switches have a port hole which is sealed by placing a compliant material over the port hole. Unfortunately, these springs and hinge mechanisms place additional load demands upon the structure. To overcome these demands of the springs and hinge mechanisms, higher magnetic forces are required to operate the switch. 
     In addition, the switches are often subject to wear and tear. Many valve seats, for example, have a conically shaped needle such that insertion into a conical shaped seat will result in a seal. In most of these designs, any misalignment occurring by virtue of inherent manufacturing tolerances must be compensated for by using relatively stronger springs to forcibly urge the valve design into a fully seated condition. Misalignment can also cause leaking at the valve seat or binding of the mechanical structure. 
     Each of these conditions place additional demands upon the electromagnet and increase manufacturing costs. Additionally, valve materials used for sealing are under load conditions which increase wear with increased operation. It is desirable, from a cost standpoint, to limit the use of materials in the switches. More specifically, the conductors utilized in switches are generally of a highly conductive material, such as copper or aluminum, which tend to be expensive. It would be advantageous to reduce the materials used (at least in terms of size and/or quantity), power, and cost while maintaining or increasing performance of switches including electromechanical switches. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       To further clarify at least some of the advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only illustrated embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG. 1  illustrates a perspective view and a side view of one embodiment of a switch in a natural or non-energized state; 
         FIG. 2  illustrates a perspective view and a side view of the switch in an energized state; 
         FIG. 3  illustrates a gap between a core and a housing of a switch; 
         FIG. 4  illustrates a perspective view and a cross sectional view of a switch configured for a fluidic application; 
         FIG. 5  illustrates a perspective view of a core with multiple ports formed therein; 
         FIG. 6  illustrates a cross sectional view of a switch configured for an optical application; 
         FIG. 7  illustrates a cross sectional view of a switch configured for electrical application; 
         FIG. 8  illustrates an example of a switch that uses at least lateral translational switching action; and 
         FIG. 9  illustrates an example of a three way switch with a core that translates at least laterally. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Embodiments of the invention relate to switches including electromechanical switches that are compact, reliable, fast operating, capable of being inexpensively manufactured and/or exhibit long operational lifetimes. From a cost, power and size standpoint, embodiments of the invention reduce or minimize the structural demands upon the switch, compared at least to conventional switches. Reducing the load demands in an electromagnetic switch, for example, can aid in minimizing the number of ampere-turns required to operate an electromagnet in the switch. Advantageously, the amount of material required for the switch can also be reduced. Further, embodiments of the invention relate to a switch requiring very low power to operate and having a reduced number of components. 
     The switches or switching devices disclosed herein, including electromechanical switches, can be used at least in fluidic, electrical, pneumatic, and/or optical applications. Generally, an electromechanical switch is formed from a magnetically loaded material placed into a ring and plug configuration. A coil is then attached to provide a magnetic field to operate the switching device. 
       FIG. 1  illustrates one example of a switching device  100  including a perspective view and a side view of the switching device. The switching device includes a body  102  that includes a core  104  and a housing  106 . In one example, materials for both the core  104  and the housing  106  include a magnetic material or a material which contains material that can be magnetized, such as injection moldable plastic containing magnetic material. Alnico, neodymium, and samarium cobalt are examples of materials. Injected molding polymers can often be filled to a percentage based on desired material properties. 
     The housing  106  has an exterior surface or perimeter whose shape can vary. For example, a shape of the exterior surface can be varied according to the use of the switching device  100 . The exterior surface (and other features) may be shaped to fit in a particular location of a device or product. 
     The housing  106  typically includes a cavity  118  that is shaped to receive the core  104 . Typically, the cavity  118  has a circular cross section and the core  104  has a circular cross section. The cross section of the core  104  is typically less than the cross section of the cavity  118 , thus allowing the core  104  to fit within the cavity  118 . 
     Alternatively, the relationship between the housing  106  and the core  104  can take other configurations. In one example, the housing  106  may be ring shaped with a cavity  118  that may be occupied by the core  104 . In this example, the core  104  may be viewed as a plug that substantially fills the hole or cavity  118  of the housing  106 . As illustrated in  FIG. 8 , however, the core may not completely fill the cavity but may be allowed to translate laterally within the cavity. More specifically, a length of the core  104  relative to a length of the cavity  118  can vary. As discussed in more detail herein, the differences in length can be used to achieve one or more different states of the switching device  100 . 
     However, the cross sectional area of the housing  106  at the cavity  118  is substantially filled by the core  104 —thus the core  104  can be viewed as a plug in this sense. As discussed in more detail herein, the core  104  can be moved laterally within the cavity  118 . The core  104  may have a length that is less than a length of the cavity, more than the length of the cavity or the same as the length of the cavity. 
     In an alternative embodiment, the relationship of the cavity in the housing  106  and the external shape of the core  104  can vary and may not correspond to one another. For example, the cavity  118  and the core  104  can each have a conical shape. In another example, the cavity  118  may be cylindrical or tubular while the shape of the core  104  may be partially tubular and partially conical. The tubular portion of the core  104  may keep the core  104  aligned in the cavity  118  while the conical portion of the core  104  may be used as a point of control of the switching device  100 . 
     The shape of the cavity  118  in the housing  106  and the shape of the core  104  allow the core to provide a contactless interface such that the switch can be sealed without contact in at least one embodiment. For instance, the core  104  and the housing  106  are configured to allow the core  104  to rotate within the cavity  118 . The surface of the core  104  is thus adjacent an interior wall of the housing that defines the cavity  118 . The magnetic fields of the core  104  and the housing  106 , however, allow the core  104  to self align according to the magnetic poles. As discussed in more detail below, this allows the switching device  100  to provide a contactless seal, by way of example only and not limitation, in fluidic and pneumatic applications. 
     Advantageously, the magnetic fields can be configured to provide a substantially contactless interface. As discussed below, a gap  116  may be present around the circumference of the core  104 . This contactless interface between the core  104  and the housing  106  allows the core  104  to rotate within the housing  106  (or in the cavity  118 ) with substantially less friction. 
     The core  104  and the housing  106  naturally orient themselves according to aligning poles  108 , identified by North (N) and South (S) symbols in  FIGS. 1 and 2 .  FIG. 1  illustrates the switch in a natural state, where the magnetic poles of the core  104  are attracted to the corresponding magnetic poles of the housing  106 . In the natural state, the switching device  100  is generally not energized. 
       FIG. 1  further illustrates that the switching device  100  may include an armature  112  with a coil  110 . The armature  112  and/or coil  110  are typically fixed to the housing  106  of the switching device  100 . The connection can be, by way of example, mechanical fasteners (e.g., screws, bolts), epoxy, welding, and the like. The armature  112  and coil  110  are an example of an energizing device. The energizing device can control a position of the core within the cavity formed in the housing. The position can be controlled, by way of example, only, rotationally and/or laterally. 
     In one example, the armature  112  and/or coil  110  may include a cap that is configured to engage with an end of the housing  106 . The housing  106  may have a groove or other structure that engages with complementary structure in the cap to secure the cap, and thus the coil  110  and armature  112  in place. The complementary engagement structures may also have rotational structure to ensure that the placement of the armature  112  relative to the core  104  and housing  106  is correct to ensure proper operation of the switching device  100 . The armature  112  may also be attached to the housing  106  by a pressure sensitive adhesive, UV curing adhesive, and the like, placed between the housing  106  and the armature  112 . 
     When the coil  110  is energized, North and South poles  114  can be created in the armature  112 . The magnetic force generated by the coil  110  is preferably designed to overcome the magnetic energy required to retain the core in its natural state  104 A. When the coil  110  is energized and the magnetic field of the armature  112  is sufficient, the core  104  rotates within the cavity  118  to an energized state  104 B, as illustrated in  FIG. 2 . 
     In the energized state  104 B, the magnetic poles of the core  104  are aligned with the magnetic poles  114  generated within the armature  112 , as illustrated in  FIG. 2 . When energy to the coil  110  is removed, thereby removing the magnetic field generated by the armature  112 , the magnetic fields of the core  104  and the housing  106  cause the core  104  to return to the natural state  104 A, as illustrated in  FIG. 1 . When the energy is removed from the coil  110 , the core  104  can rotate in either direction to return to the natural state  104 A. 
     In one example, the housing  106  is typically held in location or fixed while the core  104  is able to alter its position relative to the magnetic field  114  generated in the armature  112 . Thus, the body  102  or the housing  106  may include means for connecting to a surface of an apparatus. Alternatively, the core  104  may be fixed while the housing  106  is free to move (e.g., rotate). In this example, the core  104  is configured to rotate within the housing  106  in response to the magnetic fields being applied as discussed herein. 
     Further, embodiments of the invention may contemplate multiple coils and multiple armatures to rotate the core  104  by specific amounts. For example, the various armatures can be arranged to rotate the core  104 , by way of example and not limitation, in steps (30 degree steps, 45 degree steps, etc.). Embodiments of the invention further contemplate both rotational movement and/or translational movement of the core  104  relative to the housing  106 . 
     For example, one coil/armature may rotate the core  104  (or otherwise move or translate the core  104 ) by 45 degrees while another coil/armature, when energized, may rotate the core  104  by 90 degrees. One of skill in the art can appreciate that other movements or degrees of displacement or rotation can be achieved by the orientation of the coil/armature relative to the core  104  and housing  106 . As previously mentioned, the core  104  can rotate in either direction according to the magnetic force being applied. 
     In another embodiment, the energy applied to the coil  110  can be controlled. As illustrated in  FIGS. 1 and 2 , the armature  112  is configured to rotate the core  104  approximately 90 degrees. By varying the energy applied to the coil  110 , the rotation of the core  104  can be controlled. As a result, the core  104  can be caused to rotate to any position between 0 and about 90 degrees. In some instances, this may allow the switching device  100  to control, by way of example only, fluid flow in a varying manner. Alternatively, the ability to variably control the rotation of the core  104  can allow the switching device  100  to provide multiple contact points for electrical connections at different positions. Thus, rotation of the core  104  (and/or of the housing  106 ) can be achieved using a variably energized coil and/or through the use of multiple armatures. 
     As previously stated, embodiments of the switching device  100  include multiple aligning poles  108 ,  114 . Multiple aligning poles can create an indexing function and/or enhanced alignment. With no energy applied to the coil  110 , the switch remains in its natural state  104 A with the magnetic poles of the core  104  attracted to the corresponding magnetic poles within the housing  106 . Thus, the switches or switching devices disclosed herein can automatically align themselves in a natural state  104 A, move to an energized state such as energized state  104 B and return themselves to their natural state after energy is removed. Because the core  104  may align itself within the housing  106 , which may be circular in nature, the core  104  may be able to rotate about an axis that provides substantially frictionless rotation. 
     In one example, the core  104  may rotate without touching the interior wall of the housing  106 . This contributes to the low power required to operate the electromechanical switch. More specifically, using current manufacturing methods, the gap  116  between the core  104  and the housing  106  can be controlled to tight tolerances. The nature of the magnetic forces in the switching device  100  results in a natural alignment of the core  104  to the center axis of rotation for the housing  106 . This feature can be leveraged to create a low power precision switch or switching device for several applications. 
     For example, the switching device  100  may be employed in a gas valve application. In this example, the ability to provide tight manufacturing tolerances can prevent leakage of the gas from the switching device  100 . For example, no leak will occur for all gasses, excluding hydrogen, if the gap  116  between the core  104  and the housing  106  can be controlled to the relationship 0.0001 inches≦D 2 -D 1 ≦0.0003 inches as illustrated in  FIG. 3 . D 2  is a diameter of the cavity in the housing  106  and D 1  is a diameter of the core  104  in this example. Due to the balanced magnetic forces that exist in the multiple poles of the switching device  100 , the gap  116  will be uniform around the core  104  as it is naturally centered in the housing  106 . 
     In one example of a fluidic application, the gap  116  can be manufactured to maintain the relationship of D 2 -D 1  to be less than 0.0001 inches. The lower limit of 0.0001 inches is the maximum gap allowed to seal against hydrogen gas. All other gasses can usually be sealed by limiting the gap to a maximum of 0.0003 inches. For liquid applications, the viscosity of the fluid can be adjusted to prevent leakage or slow operation. Additionally, the active surfaces of the switching device (e.g., a valve) can be treated lyophobicly to prevent fluid from wicking into the gap  116 . 
       FIG. 4  illustrates an example of an electromechanical switch  400  in a fluidic application (such as a gas) from a perspective view and in a cross sectional view along a port hole  418 . The switch  400  is an example of the switching device  100  and includes a housing  402  and a core  404 . In this example, the port hole  418  is formed (e.g., through the center) through the housing  406  and core  404 . In this example, the port hole  418  runs substantially orthogonal to the axis of rotation of the core  404 , although the port hole  418  can be arranged in another configuration and axis. 
     In a ‘normally open’ configuration of the switch  400 , fluid can flow freely through the valve in the natural state  404 A or energy off condition. In other words, fluid can flow through the port hole  418  because the core  404  is arranged to permit fluid flow through a bore or hole formed in the core  404 . 
     When a coil  410  is energized, the core  404  is rotated 90 degrees in this example to the energized state  404 B, thereby blocking the fluid flow through the switch  400 . 
     For a normally closed configuration of the switch  400 , the poles of the core  404  are offset 90 degrees relative to the poles of the core  404  in the normally open configuration of the switch  400 , resulting in a power-off or natural state of closed. In other words, the orientation of the poles of the core  404  relative to the port hole  418  can determine whether the switch  400  (e.g, a valve) is open or closed when no energy is applied to the coil  410 . 
     The size of the port hole  418  can vary according to a desired flow or flow rate. The flow rate can be controlled, for example, by a size of the bore or hole that forms the port hole  418 . 
       FIG. 5  illustrates another example of a core  500  that can be used in embodiments of the switch or switching devices disclosed herein to control fluidic flow. The core  500  illustrated in  FIG. 5  can provide a slow leak. In this example of the core  500 , the core  500  may include a port  502  and a port  504 . The port  502  has a larger cross sectional area than the port  504 . As a result, the flow of fluid is different for the two port holes  502  and  504 . 
     When a switch (e.g., the switch  400 ) is energized, for example, the fluid may flow freely through the port  502 . When energy is removed from the switch, then the switch provides a slow leak through the port  504  and fluid flow is more restricted compared to the port hole  502 . This may be useful for various kinds of fluid including gaseous fluids and liquid fluids. The port  504 , by way of example only, may have a diameter on the order of 0.01 inches while the port  502  may have a larger diameter. 
     In addition, the ports  502  and  504  are typically substantially orthogonally positioned relative to each other in one example. Further, the fit or gap between the core  500  and the housing of the switch substantially is configured such that the fluid does not typically leak from the port that is not aligned. For example, when the port  504  is aligned for fluid flow, the interface between the port  502  and the interior wall of the housing prevents additional fluid leak at that point from the port  502 . 
       FIG. 6  illustrates an example of a switch  600  in an optical application. The switch  600  is an example of the switching device  100 . In this example, a spherical lens  602  (or other optical element) can be attached to the center of axis on the core  606 . An optical fiber  612  can be inserted into the housing  610  of the switch  600  similar to the ports on the valve design described previously. Energizing the coil of the switch  600  rotates the lens  602  from position  614 A to position  614 B, blocking the light traveling in the optical fiber  612 . The magnetic forces naturally position the core  606  to the ideal center of rotation, significantly reducing manufacturing costs associated with alignment. As previously stated, the lens  602  or other optical assembly can be arranged in the core  606  such that the energized state of the coil can allow or block light. 
       FIG. 7  illustrates an example of a switch  700  in an electrical application. The switch  700  is an example of the switching device  100 . In an electrical switch application, a core  702  can contain a buss type conductor  704  or similar, with or without a contact(s)  706 . As the core  702  is rotated, as previously described, the contacts  706  will engage with a desired wiping action or other type of mechanical engagement to establish an electrical connection. Similar to a motor stator, an electrical switch may include a spring  708  design to engage and hold the contacts  706  closed. Such a design may require higher power to operate the switch  700 . Spring designs can be created that will either require or not require power to maintain electrical connection. 
       FIG. 8  illustrates another example of a switch  800 , which is an example of the switching device  100 . The switch  800  includes a housing  802  and a core  814 . In this example, however, the core  814  has a length that allows the core  814  to translate laterally within the cavity of the housing  802 . The magnetic fields are at the ends of the housing  802  and core  814  in this example, as illustrated by magnetic fields  812 . 
     When the coil and armature (collectively  804 ) is not energized, the core  814  is in a natural state  810  within the housing  802 . Because the core  814  has a shorter length compared to a length of the cavity in the housing  802 , the natural state  810  of the core  814  is naturally centered in the cavity of the housing  802  according to the magnetic fields  812  of the switch  800 . 
     A pull state  808  is illustrated when the coil  804  is energized in  FIG. 8 . The switch  800  can also be configured to enter a push state  822 . In the pull state  808 , the magnetic field generated by the coil  804  attracts the core  814  and overcome the magnetic fields of the housing  802  and the core  814  to pull the core  804  towards the coil/armature  804  end of the switch  800 . Of course, the coil/armature  804  can also be configured to generate a magnetic field to push the core  814  away as illustrated by the push state  822 . 
     The switch  800  illustrated in  FIG. 8  may also have a gap as previously described and may be operated in a fluidic application, pneumatic application, electrical application, optical application, and the like. Specifically, the items  816  and  818  can be contacts, ports, optical fibers, and the like or any combination thereof. The core  814  may be similarly configured as previously described herein with optical elements, contacts, holes, and the like. One or more additional items (port, contact, etc.) may be behind the core  814 . 
     Although  FIG. 8  illustrates that the core  814  is between the items  816  and  818 , the core  814  may have a length (or the items  816  and  818  may be positioned) such that at least one is covered by the core  814  when in the natural state  810 . One of skill in the art can appreciate, with the benefit of the present disclosure, that the items  816  and  818  can be configured such that the core  814  may by located to cover or contact or interface with one or more of the items in any of the natural or energized states. 
     Further, the field generated by the coil/armature  804  can be reversed such that at least three states are possible. As a result, both items  816  and  818  could be open in the natural state or one of the items  816  and  818  can be covered as illustrated by the energized states. 
       FIG. 9  illustrates an example of a switch  900  that can be a three way switch. The switch  900  is an example of the switch  800 . By energizing the switch  900  to push or pull the core  814  to different locations within the cavity of the core  802 , at least three states can be achieved with the switch in  FIG. 9 . The items  816 ,  818 , and  820  can be connected in different configurations by the core  814 . For example, the core  814  can connect items  820  and  818 , connect items  816  and  820 , or not connect any of the items  816 ,  818 , and  820 . 
     The switches or switching devices described herein may not have parts that degrade or wear due to port sealing load condition (e.g., loads that occur when a port is sealed such as mechanical binding, etc.). In some embodiments, the interface between the core and the housing is contactless and the core is automatically aligned by the magnetic fields. 
     In addition, the switches have minimal or no drag, minimal structural loading, are frictionless or substantially frictionless, and can be operated in low power or ultra low power modes. Further, the switches self align using the magnetic field. Also, the switches can be manufactured less expensively. Some embodiments of the invention eliminate springs that increase the electromagnetic forces required to open or close the switch. 
     The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.