Abstract:
A hermetically-sealed electrical feed-through device includes a conductor, an insulating sleeve, and an outer ferule interconnected in a manner preventing relative rotation therebetween and/or includes a thermocouple in direct contact with the conductor for monitoring temperature. The conductor can have a body section extending along an axis and having an outer contour including flats or an outwardly-extending eccentrically-shaped lobe. The sleeve confronts and covers the body section of the conductor and accommodates and engages the outer contour at the flats or lobe to prevent rotation of the conductor relative to the sleeve, and the outer ferrule sandwiches the insulating sleeve between the outer ferrule and the outer contour of the conductor. The outer ferrule accommodates and engages the sleeve adjacent the outer contour of the conductor at the flats or lobe to prevent rotation of the insulator sleeve relative to the outer ferrule.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit under 35 USC §119(e) of U.S. Provisional Patent Application No. 61/605,494, filed Mar. 1, 2012. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to feed-through devices used, for instance, in the assembly of an energy storage device or the like. 
         [0003]    An electrical or optical feed-through device enables electrical or optical continuity from inside a sealed chamber or vessel through a wall of the chamber or vessel to a location external of the chamber or vessel. Typically, the feed-through device is required to withstand a harsh environment within the chamber or vessel without permitting the creation of leakage paths out of, or into, the sealed chamber or vessel. 
         [0004]    An example of a feed-through device includes a terminal feed-through device for a lithium cell or battery or other electrochemical device which may contain corrosive electrolytes. Feed-through devices may also be used in chemical reactor vessels, heat treating atmospheres, vacuum furnace, environmental test chambers, controlled atmosphere furnaces and ovens, and the like. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The foregoing features of the present invention should become apparent from the following description when taken in conjunction with the accompanying drawings, in which: 
           [0006]      FIG. 1  is an elevational view of a first embodiment of an electrical feed-through device providing an anti-rotational feature according to the present invention; 
           [0007]      FIG. 2  is a cross-sectional view along line  2 - 2  of  FIG. 1 ; 
           [0008]      FIG. 3  is an exploded perspective view of the electrical feed-through device of  FIG. 1 ; 
           [0009]      FIG. 4  is a perspective view of a second embodiment of an electrical feed-through device providing an anti-rotational feature according to the present invention; 
           [0010]      FIG. 5  is a perspective view of the underside of the electrical feed-through device of  FIG. 4 ; 
           [0011]      FIG. 6  is a cross-sectional view along line  6 - 6  of  FIG. 5 ; 
           [0012]      FIG. 7  is a perspective view of a third embodiment of an electrical feed-through device providing an anti-rotational feature according to the present invention; 
           [0013]      FIG. 8  is a perspective view of the underside of the electrical feed-through device of  FIG. 7 ; 
           [0014]      FIG. 9  is a cross-sectional view along line  9 - 9  of  FIG. 8 ; 
           [0015]      FIG. 10  is a perspective view of a fourth embodiment of an electrical feed-through device providing an anti-rotational feature according to the present invention; 
           [0016]      FIG. 11  is a perspective view of the underside of the electrical feed-through device of  FIG. 10 ; 
           [0017]      FIG. 12  is a cross-sectional view along line  9 - 9  of  FIG. 11 ; 
           [0018]      FIG. 13  is a plan view of a fifth embodiment of an electrical feed-through device providing an anti-rotational feature according to the present invention; 
           [0019]      FIG. 14  is a cross-sectional view through the device of  FIG. 13 ; 
           [0020]      FIG. 15  is a bottom plan view of the device of  FIG. 13 ; 
           [0021]      FIG. 16  is a perspective view of an embodiment of an electrical feed-through device cable of providing a temperature monitoring feature according to the present invention; and 
           [0022]      FIG. 17  is an elevational view of device of  FIG. 16  with the addition of a thermocouple and switching device. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    A feed-through device can be used as a terminal lead for the positive or negative electrode of a high voltage lithium-ion cell. Feed-through devices typically include an elongate center ter terminal conductor with opposite ends to which welded connections or mechanical connections can be formed on opposite sides of a wall of a chamber, vessel, or the like that separates a harsh environment, such as the inside of a lithium ion cell, from an adjacent environment, such as an environment exterior the lithium-ion cell. A center section of the conductor must be encased within an insulator sleeve to electrically insulate the conductor from the adjacent wall of the battery or the like through which the feed-through device extends. An outer ferrule extends over the insulator sleeve to sandwich the insulator sleeve between the conductor and the outer ferrule. The purpose of the ferrule is to provide a hermetic seal about the center section of the conductor and prevent liquids, gases, or other environmental contaminants from passing along the length of the conductor between the engaging surfaces of the conductor and insulator, as well as between the engaging surfaces of the insulator and ferrule. The hermetic seal is provided by crimping the above referenced components together. 
         [0024]    The exposed end of the conductor of the feed-through device which is located within a lithium-ion cell battery or the like is typically secured to an electrode. Thus, when the feed-through device is secured to the wall of the battery, the conductor must not be permitted to rotate about its central longitudinally-extending axis “A”. If the conductor rotates, the electrical connection to the electrode will be broken or damaged within the sealed battery or lithium-ion cell and the relatively expensive battery or cell may be permanently damaged. Unwanted rotation of the conductor is typically caused via the use of too much torque when applying a jam nut or the like to the opposite end of the conductor located exterior of the battery. If too much torque is applied to tighten the exterior jam nut, the conductor may rotate within and relative to the cell interior and break the electrical connection within the battery. 
         [0025]    Accordingly, embodiments of feed-through devices provided herein have an anti-rotational feature for purposes of preventing rotation of the conductor relative to the insulator sleeve, the ferrule, and the cell. The ferrule will be connected to the wall of the battery, such as by a weld or the like. Thus, provided the insulator sleeve cannot rotate within the ferrule and the conductor cannot rotate within the insulator sleeve, unwanted rotation of the conductor should be prevented. 
         [0026]    A first embodiment of an anti-rotation feed-through assembly  10  is shown in  FIGS. 1-3 . As shown in  FIG. 1 , the assembly  10  includes a conductor  12 , a plastic insulator sleeve  14 , a ferrule  16 , a ribbon cable  18 , a Belleville washer  20 , and a nut  22 . When assembled, as shown in  FIGS. 1 and 2 , a lower end  24  of the conductor  12  is exposed and can be electrically connected to an electrode or the like within a battery, and an electrical connection can be made to the upper exposed end  26  of the conductor such as via the ribbon cable  18 . The nut  22  is used to secure the ribbon cable  18  to the conductor. 
         [0027]    The assembly  10  is provided with means to prevent the conductor  12  from rotating relative to the insulator sleeve  14  and to prevent the insulator sleeve  14  from rotating relative to the ferrule  16 . Thus, even if too much torque is applied to the nut  22 , the conductor  12  should be prevented from any unwanted rotational movement about its longitudinal axis to permit any internal connections within the battery to remain unharmed. 
         [0028]    As shown in  FIGS. 1-3 , the ferrule  16  has upper and lower flanges,  28  and  30  which extend outwardly or perpendicularly from the conductor  12 . The indented region  32  of the ferrule  16  typically mates to and is secured to the wall of the battery. The insulator sleeve  14  extends within the ferrule  16  and isolates and separates any electrical connection between the conductor  12  and ferrule  16 . 
         [0029]    The conductor  12  includes an eccentric lobe  34  where upper flange  28  of the ferrule  16  is located. The eccentric lobe  34  is not centered relative to the central longitudinal axis of the conductor  12 . For instance, a segment  36  of the lobe  34  extends further from the central longitudinal axis of the conductor  12  than an opposite segment  38 . The eccentric lobe is received within an upper end  40  of the insulator sleeve  14  which fits tightly about the lobe  34 . Thus, the conductor  12  cannot rotate by itself within the insulator sleeve  14  due to the engagement of the eccentric lobe  34  with the corresponding eccentric walls of the upper end  40  of the insulator sleeve  14 . If the conductor rotates about its central longitudinal axis, the insulator sleeve will be forced to rotate therewith. 
         [0030]    However, the eccentric upper end  40  of the insulator sleeve  14  is tightly received by an accommodating opening  42  formed in the upper flange  28  of the ferrule  16 . Here, the adjacent walls of the ferrule  16  tightly engage about the upper end  40  of the insulater sleeve. Thus, due to the nature of the eccentric opening  42  of the ferrule  16 , the upper end  40  of the insulator sleeve  14  cannot rotate relative to the ferrule. Accordingly, if the ferrule  16  is welded or otherwise tightly connected to the wall of a battery, the ferrule  16  cannot rotate, which in turn prevents the insulator sleeve  14  from rotating, which in turn prevents the conductor from rotating. Thus, an anti-rotational feature is provided by the eccentric lobe  34  of the conductor  12 , the similarly shaped eccentric upper end  40  of the insulator sleeve  14  which tightly engages the lobe  34 , and the similarly shaped eccentric opening of the ferrule which receives the lobe  34  and upper end  40  of the insulator sleeve. 
         [0031]    It should be understood that any shape of lobe of the conductor and corresponding accommodating walls of the insulator body and ferrule can be used provided that respective rotation between these parts relative to the central longitudinal axis of the conductor is prevented. For instance, the lobe can have a square shape, a rectangular shape, an oval shape or any other shape that prevents rotation. Alternatively, as discussed above with respect to  FIGS. 1-3 , the lobe could simply be offset relative to the central longitudinal axis of the elongate conductor (i.e., an eccentric shape). A still further alternative is to provide flats on a conductor that are engaged by the insulator sleeve and ferrule to prevent rotation. In this alternative, instead of adding material to an otherwise substantially cylindrical portion of the conductor to form an outward extending lobe, one or more flats could be cut or formed into the conductor to form a conductor of a reduced amount of material and a smaller non-circular cross-section where the flats are cut or formed. Of course, other non-circular or offset lobes and flats could be provided. 
         [0032]    In addition to the above assembly,  FIGS. 4-12  show embodiments with feed-through devices having associated covers which can form part of the wall of a battery or the like or a cover that extends over part of a wall of a battery or the like. For example,  FIGS. 4-6  illustrate an embodiment of a feed-through device  110  including a conductor  112 , an insulator sleeve  114 , and a cover  116  having an integrally-formed upstanding ferrule portion  118 . Similar to the embodiment shown in  FIGS. 1-3 , the conductor includes an eccentric lobe  120  accommodated by similarly eccentric shaped recesses in the insulator body  114  and ferrule portion  118 . Thus, the eccentric shapes of these components provide the same anti-rotation function provided by the embodiment illustrated in  FIGS. 1-3  and discussed above in detail. The only significant difference is that lobe  120  is located adjacent an end of the conductor positioned within an interior of the battery instead of extending exteriorly of the battery. 
         [0033]    The embodiments shown in  FIGS. 7-9  and  FIGS. 10-12  are similar to the embodiment shown in  FIGS. 4-6 , except the feed-through devices  210  and  310  include conductors  212  and  312  having a square and rectangular lobes  220  and  320 , respectively, with similar shaped accommodating recesses in the insulator sleeves  214  and  314  and upstanding ferrule portions  218  and  318  of covers  216  and  316 . Thus, these embodiments also provide an anti-rotational feature that prevents rotation of the conductor even in the event excessive torque is applied to a nut or the like applied to the exterior free end of the conductor. 
         [0034]    An embodiment including a pair of feed-through devices is shown in  FIGS. 13-15 . The assembly  400  includes a cover  416  having spaced apart pair of upstanding ferrule portions  418 , a pair of insulator sleeves  414 , and a pair of conductors  412  (for instance, forming positive and negative terminals). In this embodiment, each of the conductors  412  includes an opposed pair of flats  420  where some of the material of the otherwise cylindrical conductors  412  has been removed to provide a non-circular outer periphery. The insulator sleeves  414  and ferrule portions  418  tightly confront the conductors  412  including along the flats  420  within the recesses  422  formed by the flats  420 . For example, the insulator sleeves  414  and ferrule portions  418  can be crimped therein. Accordingly, rotation of the conductors  412  is prevented relative to the insulator sleeves  414  and ferrule portions  418  due to the flats  420  and corresponding portions of the insulator sleeves  414  and ferrule portions  418  confronting the flats  420  of the conductors  412 . 
         [0035]    Turning to another aspect of a feed-through device, particularly when used as a battery electrical terminal, an additional function relating to monitoring the conditions of the battery can be provided by the feed-through device. For example, the monitoring of the temperature of lithium-ion cells is an important indicator of potential problems with the cell. For instance, excessive temperature may lead to premature failure of the lithium-ion cell or significantly shorten the life of the cell. Accordingly, the earlier a temperature rise is observed, the earlier corrective actions can be taken to correct cell charging or discharging problems in a meaningful manner. 
         [0036]    The conventional method for monitoring temperature of a lithium-ion cell is to use a thermocouple which is attached externally to a cell wall or battery stack case. Thus, as temperatures increase within the cell, the temperature will ultimately radiate to the exterior surface of the cell wall where it can be read and picked up by the thermocouple. However, the responsiveness to temperature changes provided by the externally located thermocouple is relative slow because the mass of the cell or stack forms part of the total mass involved with monitoring temperature change and it may take awhile before a temperature rise within the cell radiates and is transferred to an exterior surface of the cell. 
         [0037]    Thus, an embodiment of a feed-through device can include a thermocouple or like component embedded within the electrical terminal conductor of the hermetically-sealed feed-through device. The purpose of the thermocouple is to provide an earliest possible warning of temperature change occurring within the sealed lithium-ion cell. The materials used as the conductors of the feed-through devices will inherently possess excellent thermal conductivity (for instance, copper, aluminum, titanium, molybdenum or the like). In addition, the conductor of a hermetically-sealed feed-through device is inherently thermally isolated from the rest of the surrounding components and environment by the insulator, such as the plastic insulator sleeves discussed above. Thus, the conductor of the feed-through device, which has an exposed end positioned within the interior of the lithium-ion cell, provides a direct thermal link to the interior of the lithium-ion cell. Thus, the conductor provides a means for improving responsiveness with respect to the monitoring of temperature change within the cell, and the thermocouple embedded therein can be used to provide an early indication of sudden temperature changes occurring within the cell. 
         [0038]    In addition, the monitoring capability of the thermocouple embedded within the conductor can also be used in connection with an electronic switching device to switch off a cell during a potentially dangerous run-away lithium-ion cell situation. The thermocouple can be set to recognize such a situation and cause the electronic switching device to open or disconnect a circuit connection to the cell to save the cell and render an otherwise dangerous situation harmless. When current rises, the temperature of the conductor of the terminal feed-through device increases. Accordingly, when the current is beyond an acceptable predetermined limit and the embedded thermocouple recognizes a temperature increase associated with such a level, the electronic switching device which may be embedded in the terminal header or provided as an external separate unit can be used to open the circuit between the cell and an external electronic device to cut off the flow of current to the cell. Such an approach can be employed to permanently interrupt current flow from the cell to the external device or can automatically reset after an acceptable temperature is monitored by the embedded thermocouple for a preset period of time. 
         [0039]    An embodiment of a feed-through device  500  including an embedded thermocouple  502  is shown in  FIGS. 16 and 17 . Here, a spaced-apart pair of hermetically-sealed feed-through devices  500  is connected to a header  504  for use as positive and negative terminals of a lithium-ion cell or like battery. The feed-through devices  500  can be in the form of any of the above described feed-through devices providing a conductor anti-rotation feature or can be of a conventional or other configuration. Each feed-through device  500  includes a conductor  506  having an exposed end  508  for being positioned within the interior of the cell or battery and an exposed end  510  located externally of the cell or battery. The mid-portion of the elongate conductor extends within an insulator sleeve and ferrule as discussed above and is otherwise electrically and thermally isolated from the walls of the cell or battery. 
         [0040]    The thermocouple  502  is embedded within one of the conductors  506  and is electrically connected to an electronic switching device  512  mounted integrally on the header  504 . The electronic switching device  512  is electrically connected to a means for opening the circuit between the cell and an electronic device connected to the cell. Thus, as discussed above, when temperature rises internally within the cell or due to a run-away current flow situation, the thermocouple  502  is able to quickly pick up the rise or change in temperature and cause the switching device  512  to take corrective measures when necessary. 
         [0041]    Various alternative designs can be utilized. For example, the thermocouple need only be in contact with the conductor of the feed-through device and may not need to be fully embedded therein. Also, the positioning of the thermocouple can be altered such that it extends closer to the cell interior end of the conductor or closer to the cell exterior end of the conductor or midway therebetween. Still further, thermocouples can be used in both the positive and negative terminals and redundant thermocouples can also be included. Also, devices other than thermocouples for measuring temperature change or any other condition can be embedded into the conductor in the same manner discussed above for the thermocouple. 
         [0042]    While anti-rotational and temperature monitoring feed-through devices and assemblies have been described in detail, various modifications, alterations, and changes may be made without departing from the spirit and scope of the present invention.