Patent Publication Number: US-2022230824-A1

Title: Switching device with ceramic/glass eyelets

Description:
This application claims the benefit of U.S. Provisional Patent Appl. Ser. No. 63/140,073, filed on Jan. 21, 2021. 
    
    
     BACKGROUND 
     Field of the Invention 
     Described herein are electrical switching devices utilizing insulating eyelets or grommets around their fixed contacts that can be made of materials such as ceramic or glass, with some embodiments comprising a stud (stationary), insulating disk and flange as its means for forming a hermetic seal. 
     Description of the Related Art 
     Connecting and disconnecting electrical circuits is as old as electrical circuits themselves and is often utilized as a method of switching power to a connected electrical device between “on” and “off” states. Examples of devices commonly utilized to connect and disconnect circuits include contactors and relays (“contactor” or “contactors”), which are electrically connected to one or more devices or power sources. A contactor is configured such that it can interrupt or complete a circuit to control electrical power to and from a device. One type of conventional contactor is a hermetically sealed contactor. 
     In addition to contactors, which serve the purpose of connecting and disconnecting electrical circuits during normal operation of a device, various additional devices can be employed in order to provide overcurrent protection. These devices can prevent short circuits, overloading, and permanent damage to an electrical system or a connected electrical device. These devices include disconnect devices which can quickly break the circuit in a permanent way such that the circuit will remain broken until the disconnect device is repaired, replaced, or reset. One such type of disconnect device is a fuse device. The descriptions and features described below are primarily directed to contactors, but it is understood that the description and features can also be applied to fuse devices. 
     Some conventional contactors and fuses have moving components housed within a ceramic housing. These types of contactors can operate with a vacuum formed in the housing or with the housing having internal pressure from an injected gas. This allows the contactors to operate with higher voltage and/or lower resistance characteristics and ceramic housings also allow the contactors to operate at high temperatures and with smaller open gaps and envelope sizes. Ceramic housings, however, can be expensive and difficult to manufacture, can be sensitive to torque, temperature and axial loading, and are also not nodular. 
     Conventional contactors and fuses may also comprise a housing with a ceramic header. Ceramic headers offer many of the same voltage, resistance and/or temperature characteristics of ceramic housings as well as offering a means whereby contacts can be electrically isolated from one another. Traditional ceramic headers can be difficult and expensive to manufacture because they are complex shapes that require special tooling, difficult metallization, and time-consuming post processes. Traditional ceramic headers also offer limited options for geometry and are usually flat or box-like, and also provide limited options for the location spacing and orientation of the contactor&#39;s fixed contacts. Furthermore, multi-contact ceramic headers and ceramic housings can prohibit radial symmetry around the fixed contact, which can impose structural and thermal shock resistance weakness on the ceramic header and housing. 
       FIGS. 1-3  show a conventional switching device  10  and its ceramic header  12  and fixed contacts  1 - 4 . The header  12  is arranged to cover the entire opening of the housing/cup  16 . The contactor&#39;s internal moving components are held in the sealed internal chamber defined by the header  12  and the housing  16 . The header has fixed contact  20   a,    20   b  that pass through the header to interact with internal components of the contactor  10 . As further described below, an internal chamber is formed by the housing  16  and header  12 , and the internal chamber can be filled with gas by a tube  18  that passes through the header  12 . In other embodiments, the tube  18  can be used to form a vacuum in the internal chamber. 
     The header  12  can comprise a ceramic material. Ceramic is relatively expensive material and by covering the entire opening of the housing, the header can comprise an expensive component of the contactor  10 . In addition, the horizontal and single piece nature of the header  12  results in United options for spacing and orientation of the fixed contacts  20   a,    20   b.  The horizontal header limits the orientation of the fixed contacts  20   a,    20   b  to vertical unless the header undergoes very expensive customizing. The full ceramic header  12  can also result in practical limitations for implementing other features such as arc suppressing and insulation resistance features, and arc shadowing and shielding features. 
     SUMMARY 
     The present invention is directed to contactor switching devices such as contactors that utilize eyelets around the fixed contacts that can comprise insulating materials such as ceramic or glass. One embodiment of electrical switching device according to the present invention comprises a hermitically sealed housing and internal components within the hermetically sealed housing. The internal components are configured to change the state of the switching device from a closed state and an open state in response to input, wherein the closed state allows current flow through the device and the open state interrupts current flow through said device. The device further comprise a plurality of fixed contact electrically connected to the internal components for connection to external circuitry. A plurality of eyelets are included, each of which mounted to respective one of said fixed contacts. 
     In some embodiments that hermetically sealed housing can comprise a cup and a header, with the fixed contacts protruding from the header. Some embodiments of the eyelets can comprise ceramic or glass, and the header can comprise less expensive and easier to work with materials such as metals or plastics. By utilizing eyelets instead of a full header of ceramic or glass, the amount of expensive material needed for the header is reduced, which can reduce the overall cost of the contactor. Using eyelets can also optimize manufacturing in modular high-volume environments (e.g. pick and place). Using eyelets can also improve the contactor&#39;s performance characteristics such as reducing coefficient of thermal expansion (CTE) mismatch and improving mechanical robustness of joints in the contactor. 
     Eyelets can provide the same desired electrical and thermal characteristic of full ceramic headers, and are smaller and easier to handle during manufacturing. This allows the eyelets to be more easily manufactured to allow for the implementation of features in the eyelet that can increase the reliability of the contactor. Using eyelets also provides for flexibility in the spacing and orientation of the fixed contacts, and the eyelets can be provided with improved shadowing features and geometries. Some eyelet embodiments can be radially symmetric, which can provide increased structural strength and increased thermal shock resistance. 
     These and other further features and advantages of the invention would be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings, wherein like numerals designate corresponding parts in the figures, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a sectional perspective view of a conventional switching device with a ceramic header; 
         FIG. 2  is an exploded perspective view of the ceramic header and fixed contacts for the switching device shown in  FIG. 1 ; 
         FIG. 3  is perspective view of the ceramic header and fixed contacts for the switching device shown in  FIG. 1 ; 
         FIG. 4  is a sectional perspective view of one embodiment of a switching device according to the present invention; 
         FIG. 5  is an exploded perspective view of one embodiment of an eyelet and fixed contact header assembly according to the present invention; 
         FIG. 6  is a perspective view of an eyelet and fixed contact assembly according to the present invention with improved arc shadowing; 
         FIG. 7  is a sectional view of the assembly shown in  FIG. 6 ; 
         FIG. 8  is a side view of the assembly shown in  FIG. 6 ; 
         FIG. 9  is a top view of the assembly shown in  FIG. 6 . 
         FIG. 10  is a perspective view of another embodiment of an eyelet and fixed contact assembly according to the present invention; and 
         FIG. 11  is a sectional view of the assembly shown in  FIG. 10 . 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is generally directed to contactor devices having improved headers that can comprise a respective ceramic (or glass) eyelet at each of the fixed contacts instead of a full ceramic header covering the entire housing opening. The term eyelet refers to the use of ceramic or glass material around the fixed contact that covers less than all of the housing opening for the contactor. In some embodiments, the eyelets can be arranged such that they surround the fixed contacts, with some eyelet embodiments being symmetrical around the fixed contact. This can result less material needed to provide the thermal and electrical characteristics of ceramic, thereby reducing material costs of the contactor. The remainder of the header can be made of a less expensive material such as a low carbon steel. 
     Use of eyelets can also result in improved processing time and less complex manufacturing in that in that metallization of the ceramic is the same on both sides. Some embodiments of the eyelets can also be radially symmetric, which can increase the structural strength of the device and improve its thermal shock resistance. 
     Having separate ceramic eyelets at each of the fixed contacts can also provide flexibility in the features that can be formed in the eyelets. The size of the eyelets makes the formation of these features easier and less expensive. Many different features can be formed in the eyelets in many different locations, with some of the feature comprising trenches or channels around the fixed contacts. These trenches can serve different functions such as arc shadowing to prevent shorting from deposits formed on the eyelets during arcing events. 
     Having separate ceramic eyelets also provides design flexibility in the spacing and orientation of the fixed contacts. It is much easier to provide different spacing and orientation for the fixed contacts by mounting the eyelets at different spacings and orientations. 
     The present disclosure will now set forth detailed descriptions of certain embodiments of contactors according to the present invention. It is understood, however, that the present invention can also be used in other devices, such as fuse devices. These contactors can be electrically connected to an electrical device or system to turn power to the connected device or system “on” or “off.” 
     Throughout this description, the preferred embodiment and examples illustrated should be considered as exemplars, rather than as limitations on the present invention. As used herein, the term “invention,” “device,” “present invention,” or “present device” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “invention,” “device,” “present invention,” or “present device” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s). 
     It is also understood that when an element or feature is referred to as being “on” or “adjacent” to another element or feature, it can be directly on or adjacent to the other element or feature or intervening elements or features may also be present. It is also understood that when an element is referred to as being “attached,” “connected” or “coupled” to another element, it can be directly attached, connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly attached,” “directly connected” or “directly coupled” to another element, there are no intervening elements present. 
     Relative terms, such as “outer,” “above,” “lower,” “below,” “horizontal,” “vertical” and similar terms, may be used herein to describe a relationship of one feature to another. It is understood that these terms are intended to encompass different orientations in addition to the orientation depicted in the figures. 
     Although the terms first, second, etc. may be used herein to describe various elements or components, these elements or components should not be limited by these terms. These terms are only used to distinguish one element or component from another element or component. Thus, a first element or component discussed below could be termed a second element or component without departing from the teachings of the present invention. 
     The terminology used herein is for describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Embodiments of the invention are described herein with reference to different views and illustrations that are schematic illustrations of idealized embodiments of the invention. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances are expected. Embodiments of the invention should not be construed as limited to the particular shapes of the regions illustrated herein, but are to include deviations in shapes that result, for example, from manufacturing. 
     The present invention is described with reference to eyelets made of ceramic or glass. It is understood that the eyelets can be made of many different materials having the desired electrical or thermal characteristics suited for the particular device. It is understood that the present invention is not limited to eyelets made of ceramic or glass. 
       FIGS. 4-9  show one embodiment of a contactor  100  and its improved header  102  according to the present invention. The contactor  100  comprises a housing/cup  104  that is typically made of a metal material, with one example being a low carbon steel. In other embodiments housing can comprise other materials, such as a plastic, or can comprise a combination of materials. 
     The header  102  can be mounted to the opening of the housing  104  to form a chamber for holding the contactor&#39;s internal components. Fixed contacts  106   a ,  106   b  are included on the header  102  for connecting the contactor  100  to an electrical system. Operation of contactors is generally known in the art and is only briefly discussed with reference to the different components in contactor  100 . 
       FIG. 4  shows the internal components of the contactor  100 , which include a mechanism for changing the state of the contactor, with a preferred mechanism being a solenoid  108 . Many different solenoids can be used, with a suitable solenoid operating under a low voltage and with a relatively high force. Some commercially available solenoids that can be used are available from Bicron Inc., with one example being Bicron Inc. Model No. SD1564 N1200. 
     The internal components further comprise a plunger  120 , a plunger spring  122 , a plunger shaft  124 , a contact spring  126  and a moveable contact  128 . Most of the plunger  120  is arranged within solenoid  118  and the shaft  124  passes through the middle of the plunger  120 , with the plunger spring  122  held on the shaft within the plunger  120 . 
     When the solenoid  108  is energized, it moves the moveable contact  128  a certain distance known as the contact gap before it makes contact with the lower surface of the fixed contacts  106   a,    106   b.  The contact gap provides the electrical isolation to stop current flow through the fixed contacts  106   a,    106   b  when the movable contact  128  is not in contact with the fixed contacts  106   a,    106   b.  The compression force of the contact spring  126  is applied to the movable contact  128  to hold in contact with the fixed contacts  106   a,    106   b  when the solenoid is energized. 
     The header  102  is included over the opening of the housing  104  and is a flat shape to help make tooling arid manufacturing inexpensive. As discussed above, conventional headers can be made of ceramic. For contactor  100  the header can be made of a less expensive arid more easily fabricated such as a metal or plastic, or combinations of metals or plastics. In some embodiments, the header  102  can be copper or low carbon steel, or a combination thereof. 
     The header  102  rests on the upper lip of the housing  104  and can be affixed in place using different methods such as brazing or welding. Header  102  comprises first and second contact holes  132 ,  134  (best shown in  FIG. 5 ) sized so that fixed contacts  106   a,    106   b  can pass through the header  102  to be in position to make electrical contact with moveable contact  128 . 
     The header  102  also comprises an evacuation tube and first and second electrical conductors (not shown). In some embodiments, the housing  104  and header  102  can form a hermitically sealed chamber and the evacuation tube can be arranged to allow gasses to be injected into the chamber. In some embodiments, the gasses can be under pressure. In other embodiments, the tube can be used to create a vacuum in the chamber. After the gasses are injected (or vacuum created), the tube is sealed so that no further gasses can pass in or out. The sets of conductors can pass through the header  130  for applying an electrical signal to the internal components of the contactor  100 . The solenoid  108  can be energized by applying the appropriate bias to conductors. This can cause the movable contact  128  to move in and out of contact the fixed contacts  106   a,    106   b,  the the movable contact  128  forming a conductive path between the fixed contacts  106   a,    106   b  with in contact with the fixed contacts  106   a,    106   b.    
     As mentioned above, the header  102  is made of material other than ceramic, with some header embodiments comprising a metal or plastic. The contactor  100  according to the present invention can still provide the desired thermal and electrical characteristics of a ceramic header. Instead of having a full ceramic header covering the entire opening of the housing  104 , the contactor according to the present invention comprises ceramic “eyelets”  120  around each of the fixed contacts  106   a,    106   b.  Using eyelets  120  instead of full ceramic header can provide several advantages. 
     The eyelets  120  can provide the same electrical and thermal conductivity properties as a ceramic header covering the entire housing opening. By using eyelets, however, the amount of ceramic needed is reduced thereby reducing the overall cost of the contactor  100 . 
     Each of the eyelets can also be more easily shaped or contoured to include features to increase the performance and reliability of the contactor  100 . For example, and as best shown in  FIGS. 6 and 7 , each of the eyelets  120  can contain first and second trenches or channels  122   a,    122   b  around its one of the fixed contacts  106   a,    106   b.  In the embodiment shown, each of the fixed contacts  106   a,    106   b  can have a head  117   a  and body  117   b , with the body  117   b  passing through the opening in the eyelet  120  (and opening of the header as shown in  FIG. 4 ) and the head  117   a  rests on the top surface of the eyelet  120 . 
     The first channel  122   a  can be arranged below the fixed contact head  117   a  and in a circle around the fixed contact body  117   b.  The second channel  122   b  is also in a circle around the body  117   b,  but is outside the fixed contact head  117   a.  The channels  122   a,    122   b  can be arranged to provide for more reliable operation of the contactor  100  over the life of the contactor  100 . The channels  122   a,    122   b  can provide a series of varying surfaces that help maintain isolation and dielectric strength between the fixed contacts  106   a,    106   b  and the surrounding elements of the contactor  100 . 
     Contact arcing and material expulsions during operation can create contact deposits on the surfaces of the eyelet  120 . These deposits can be electrically conductive, and the build-up of these deposits can result in the formation of an electrical path over the eyelet surface that can result in a shorting path over the eyelet  120  or the surrounding header surface. This can ultimately result in an electrical short between the fixed contact  106   a,    106   b,  or a short between the fixed contact  106   a,    106   b  and other components of the contactor such as the header  102  or housing  104 . 
     The varying surface of the channels  122   a,    122   b  can help prevent build-up of these deposits in a way that would allow formation of an electrical path, thereby maintaining the dielectric withstand voltage required between the fixed contacts  106   a,    106   b.  These features are known as arc shadowing features, and can be included in many different locations in the contactor  100  beyond the eyelets  120 . It is also noted that the arc shadowing features can take many different shapes and can be in many different locations in the eyelets  120 . It is also noted that additional features can be included with the eyelet  120  and its fixed contact  106   a,    106   b  to help from deposit build-up, including but not limited to, O-rings in different locations around or adjacent to the fixed contact  106   a,    106   b.    
     The channels  122   a,    122   b  are only one example of the different features that can be included in the eyelets  120 . The use of eyelets  120  provide the advantage of being much easier to form features such as the channels compared to forming the same features in a full ceramic header. 
     The use of eyelets instead of a full ceramic header provides further advantages. In some embodiments, it may also be desirable to have one or both of the fixed contacts at any angle different from the standard orientation provided by a full planar ceramic header. The present invention allows for this differing angle arrangement by simply angling the features found below the eyelet, including a portion of the header  130  or the portion of the internal chamber  142  that passes up through the header holes  132 ,  134 . Using eyelets also allows for more flexibility in spacing of the fixed contacts  106   a,    106   b.  Different contacts can have different spacing between the header holes and the portion of the internal chamber passing into the header holes  132 ,  134 . For these different embodiments, the same eyelets  120  can be used. This allows for the manufacturing and stocking of eyelets that can be used in many different contactors. 
     It is understood that the eyelets according to the present invention can have many different shapes and sizes beyond those described herein, and can have many different features. It is also understood that the fixed contacts do not need to have eyelets of the same size or shape, or with the same features. 
     The eyelets  120  can be mounted to the header  130  using many different material and methods. In the embodiment shown, a metal ring (or flange)  144  can be attached to the bottom surface of the each of the eyelets  120 . Many different attachment mechanisms can be used including brazing or welding. The metal ring  144  has a flange  146  that rests on the header  130  and can also be mounted in place using brazing or welding. In some embodiments, the attachment of the ring  144  to the eyelets  120  and header  130  can also provide for a hermitic seal. 
     It is understood that the different embodiments of eyelets and fixed contacts according to the present invention can be arranged in many different ways.  FIGS. 10 and 11  show another embodiment of a fixed contact and eyelet assembly  150  according to the present invention that comprises many of the same components and features as the embodiment described above. The assembly comprises a fixed contact  152 , an eyelet  154  and a metal ring (or flange)  156 . Like the embodiment above, the fixed contact  152  can have a head  152   a  and body  152   b,  with the body  152   b  passing through the opening in the eyelet  154 , with the  152   a  resting on the top surface of the eyelet  152 . 
     In this embodiment, the metal ring  156  ring is affixed to the side surface of the eyelet  152 , instead of the bottom surface. The eyelets  152  can then be mounted to the header using many different material and methods. Many different attachment mechanisms can be used for attaching the ring  156  to the eyelet  152  including brazing or welding. Like the embodiment above, the metal ring  156  has a flange  158  that rests on the header and can also be mounted in place using brazing or welding. In some embodiments, the attachment of the ring  156  to the eyelets  152  and header can also provide for a hermitic seal. 
     Although the present invention has been described in detail with reference to certain preferred configurations thereof, other versions are possible. Embodiments of the present invention can comprise any combination of compatible features shown in the various figures, and these embodiments should not be limited to those expressly illustrated and discussed. Therefore, the spirit and scope of the invention should not be limited to the versions described above. 
     The foregoing is intended to cover all modifications and alternative constructions falling within the spirit and scope of the invention, wherein no portion of the disclosure is intended, expressly or implicitly, to be dedicated to the public domain if not set forth in any claims.