Patent Publication Number: US-11387068-B2

Title: Active/passive fuse module

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 62/948,728, filed Dec. 16, 2019 and U.S. Provisional Patent Application No. 63/036,613, filed Jun. 9, 2020, both of which applications are incorporated by reference herein in their entireties. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates generally to the field of circuit protection devices and relates more particularly to an active/passive fuse module that includes both passive and active circuit protection elements. 
     BACKGROUND OF THE DISCLOSURE 
     Fuses are commonly implemented in electrical systems for providing overcurrent protection. Most fuses are “passive” devices that include fuse elements that are configured to carry a rated amount of electrical current during normal operation. If current flowing through a fuse element exceeds the fuse element&#39;s rated current, the fuse element will melt, disintegrate, or otherwise separate, thereby arresting the current to prevent or mitigate damage to connected electrical components. 
     In some cases, it may be desirable to “actively” create a physical opening in an electrical circuit regardless of an amount of electrical current flowing through the circuit. For example, if an automobile is involved in a collision, it may be desirable to physically open an electrical circuit in the automobile to ensure that connected electrical components are deenergized to mitigate the risk of fire and/or electrocution in the aftermath of the collision. To that end, so-called pyrotechnic interrupters (PIs) have been developed which can be selectively actuated upon the occurrence of specified events to interrupt the flow of current in a circuit. For example, in the case of an automobile collision, a controller (e.g., an airbag control unit, battery management system, etc.) may send an initiation signal to a PI, causing a pyrotechnic ignitor within the PI to be detonated. A resultant increase in pressure within the PI rapidly forces a piston or blade to cut through a conductor that extends through the PI. Electrical current flowing through the PI is thereby interrupted, and the piston, which is formed of a dielectric material, provides an electrically insulating barrier between separated portions of the conductor to prevent electrical arcing therebetween. 
     In certain applications it may be desirable to implement both passive and active circuit protection elements. It may further be desirable to implement such elements in a compact, space-saving form factor that facilitates convenient installation. 
     It is with respect to these and other considerations that the present improvements may be useful 
     SUMMARY 
     This Summary is provided to introduce a selection of concepts in a simplified form further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is the summary intended as an aid in determining the scope of the claimed subject matter. 
     An active/passive fuse module in accordance with a non-limiting embodiment of the present disclosure may include a base, a busbar disposed on a top surface of the base and including a fuse element and first and second terminal portions extending from opposite ends of the fuse element, the fuse element extending over a cavity in the top surface of the base, a pyrotechnic interrupter (PI) disposed atop the base, the PI including a piston disposed within a shaft above the fuse element, a first pyrotechnic ignitor coupled to a controller, the first pyrotechnic ignitor configured to detonate and force the piston through the fuse element upon receiving an initiation signal from the controller, and a second pyrotechnic ignitor coupled to the busbar by a pair of leads, the second pyrotechnic ignitor configured to detonate and force the piston through the fuse element upon an increase in voltage across the leads. 
     An active/passive fuse module in accordance with another non-limiting embodiment of the present disclosure may include an electrically insulating base, a busbar disposed on a top surface of the base and comprising a fuse element and first and second terminal portions extending from opposite ends of the fuse element, the fuse element extending over a cavity formed in the top surface of the base, a pyrotechnic interrupter (PI) disposed atop the base, the PI including a piston disposed within a shaft above the fuse element, a current sensing module connected to the busbar and configured to measure a current flowing through the busbar, and a pyrotechnic ignitor coupled to a controller and to the current sensing module, wherein the pyrotechnic ignitor is configured to detonate and force the piston through the fuse element upon receiving an initiation signal from at least one of the controller and the current sensing module. 
     An fuse module in accordance with another non-limiting embodiment of the present disclosure may include a base, a busbar disposed on a top surface of the base and including a fuse element and first and second terminal portions extending from opposite ends of the fuse element, the fuse element extending over a cavity in the top surface of the base, a pyrotechnic interrupter (PI) disposed atop the base, the PI including a piston disposed within a shaft above the fuse element, a first pyrotechnic ignitor coupled to a controller, and a pyrotechnic ignitor coupled to the busbar by a pair of leads, the pyrotechnic ignitor configured to detonate and force the piston through the fuse element upon an increase in voltage across the leads. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross sectional view illustrating an embodiment of an active/passive fuse module in accordance with the present disclosure in a non-actuated state; 
         FIG. 2  is a cross sectional view illustrating the active/passive fuse module shown in  FIG. 1  in an actuated state; 
         FIG. 3  is a cross sectional view illustrating another embodiment of an active/passive fuse module in accordance with the present disclosure; 
         FIG. 4  is a cross sectional view illustrating another embodiment of an active/passive fuse module in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     An active/passive fuse module in accordance with the present disclosure will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the active/passive fuse module are presented. It will be understood, however, that the active/passive fuse module may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will convey certain exemplary aspects of the active/passive fuse module to those skilled in the art. 
     Referring to  FIGS. 1 and 2 , cross-sectional views illustrating an active/passive fuse module  10  (hereinafter “the fuse module  10 ”) in accordance with an exemplary, non-limiting embodiment of the present disclosure are shown. For the sake of convenience and clarity, terms such as “front,” “rear,” “top,” “bottom,” “up,” “down,” “vertical,” and “horizontal” may be used herein to describe the relative placement and orientation of various components of the fuse module  10 , each with respect to the geometry and orientation of the fuse module  10  as it appears in  FIGS. 1 and 2 . Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import. 
     The fuse module  10  may generally include a base  12 , a busbar  14 , and a pyrotechnic interrupter (PI)  18 . The base  12  may be formed electrically insulating material, such as plastic, polymer, ceramic, etc. The present disclosure is not limited in this regard. The base  12  may include a cavity  20  formed in a top surface thereof. 
     The busbar  14  may be formed from a single piece or length of conductive material (e.g., stamped from a single sheet of copper or the like) and may include a fuse element  22  and first and second terminal portions  26   a ,  26   b  extending from opposite ends of the fuse element  22 . The busbar  14  may be disposed on the top surface of the base  12  in a horizontal orientation with the fuse element  22  extending over the cavity  20 . The first and second terminal portions  26   a ,  26   b  may extend outside of, or beyond, the sides of the base  12  for facilitating connection of the fuse module  10  within a circuit. 
     The fuse element  22  may be configured to melt, disintegrate, or otherwise open if current flowing through the busbar  14  exceeds a predetermined threshold, or “current rating,” of the fuse module  10 . In various examples, the fuse element  22  may include perforations, slots, thinned or narrowed segments, and/or various other features for making the fuse element  22  more susceptible to melting or opening than other portions of the busbar  14 . In a non-limiting example, the fuse element  22  may be configured to have a current rating in a range between 30 amps and 1000 amps. The present disclosure is not limited in this regard. 
     The PI  18  may include a housing  36  having a mounting flange  38  projecting from a lower portion thereof. The housing  36  may be disposed atop the base  12  with mechanical fasteners  40   a ,  40   b  extending through the mounting flange  38  and into the base  12  for fastening the components together in a vertically stacked relationship. The housing  36  may include a hollow, vertically oriented shaft  43  extending therethrough. The shaft  43  may have an open bottom end located directly above the fuse element  22  and the cavity  20 . 
     The housing  36  may contain a movable piston or blade  42  (hereinafter “the piston  42 ”) disposed within a hollow shaft  43  located above the cavity  20  of the base  12 . The housing  36  may further contain a first pyrotechnic ignitor  44   a  disposed within the shaft  43  above the piston  42 . The first pyrotechnic ignitor  44   a  may be coupled to a controller  45  (e.g., an airbag control unit, battery management system, etc. of an automobile). Upon the occurrence of a predefined event, such as an automobile collision (i.e., if the fuse module  10  is implemented in an automobile), the controller  45  may send an initiation signal to the pyrotechnic ignitor  44   a , causing the pyrotechnic ignitor  44  to be detonated. A resultant increase in pressure within the shaft  43  rapidly forces the piston  42  downwardly in the shaft  43 , through the fuse element  22  of the busbar  14  as shown in  FIG. 2 . Electrical current flowing through the busbar  14  is thereby interrupted, and the piston  42 , which may be formed of a dielectric material, may provide an electrically insulating barrier between the separated ends of the fuse element  22  to prevent electrical arcing therebetween. 
     The above-described manner in which the pyrotechnic ignitor  44   b  is triggered (i.e., via the controller  45  sending an initiation signal to the pyrotechnic ignitor  44   b  upon occurrence of a collision, etc.) may be referred to as “external triggering” of the pyrotechnic ignitor  44   b . In various embodiments, the fuse module  10  may additionally or alternatively include an “arc triggering” capability, wherein a second pyrotechnic ignitor  44   b  may be disposed within the shaft  43  adjacent the first pyrotechnic ignitor  44   a . A pair of leads  52   a ,  52   b  may extend from the second pyrotechnic ignitor  44   b  to the first and second terminal portions  26   a ,  26   b , respectively. In various embodiments, the leads  52   a ,  52   b  may extend through/across the shaft  43  below the piston  42 . When the fuse element  22  is melted (e.g., upon occurrence of an overcurrent condition), the voltage across the separated first and second terminal portions  26   a ,  26   b  may create sufficient current in the leads  52   a ,  52   b  to cause the second pyrotechnic ignitor  44   b  to be detonated. A resultant increase in pressure within the shaft  43  rapidly forces the piston  42  downwardly in the shaft  43 , through the fuse element  22  of the busbar  14  (as described above and as shown in  FIG. 2 ). Additionally, the piston  42  severs the leads  52   a ,  52   b  to eliminate any potential alternative current paths between the first and second terminal portions  26   a ,  26   b.    
     The above-described configuration is not intended to be limiting, and it is contemplated that the leads  52   a ,  52   b  may be severed at various locations other than within the shaft  43  and by structures other than the piston  42 . For example, instead of extending through the shaft  43 , the leads  52   a ,  52   b  may extend through the cavity  20  or elsewhere adjacent the shaft  43 . In various embodiments, the leads  52   a ,  52   b  may be located outside of or away from the path of the piston  43  and, instead of being severed directly by the piston  43 , may be severed by a shank or protrusion extending from the piston  43  or by an electrical/mechanical structure or device that may be triggered by movement of the piston  43 . The present disclosure is not limited in this regard. 
     Various additional or alternative devices, configurations, and/or arrangements for ensuring electrical isolation between the first and second terminal portions  26   a ,  26   b  after detonation of the second pyrotechnic ignitor  44   b  may be implemented without departing from the scope of the present disclosure. 
     Since the fuse element  22  begins to separate (e.g., melts) before the pyrotechnic ignitor  44   b  detonates and drives the piston  42 , the fuse element  22  is weakened (e.g. partially melted) before the piston  42  is driven therethrough, making it easier for the piston  42  to cut through the fuse element  22 . Thus, the fuse element  22  may be thicker/larger (and therefore capable of handling higher currents) than would be possible if the piston  42  were required to break through an unweakened portion of the busbar  14  (i.e., a portion of the busbar  14  other than the partially melted fuse element  22 ) as in conventional fuse modules incorporating pyrotechnic interrupters. 
     While the above-described fuse module  10  includes a first pyrotechnic ignitor  44   a  coupled to the controller  45  and a second pyrotechnic ignitor  44   b  coupled to the first and second terminal portions  26   a ,  26   b  of the busbar  14 , respectively, embodiments of the present disclosure are contemplated in which the first pyrotechnic ignitor  44   a  and the controller  45  are omitted, and wherein the fuse module  10  includes only a single pyrotechnic ignitor connected to the busbar  14  and configured to be detonated upon separation of the fuse element  22  (as described above with respect to the second pyrotechnic ignitor  44   b ). 
     Referring to  FIG. 3 , an embodiment of the present disclosure is contemplated in which a positive temperature coefficient (PTC) element  60  may be connected in parallel with the fuse module  10 . The PTC element  60  may be formed of any type of PTC material (e.g., polymeric PTC material, ceramic PTC material, etc.) formulated to have an electrical resistance that increases as the temperature of the PTC element  60  increases. Particularly, the PTC element  60  may have a predetermined “trip temperature” above which the electrical resistance of the PTC element  60  rapidly and drastically increases (e.g., in a nonlinear fashion) in order to substantially arrest current passing therethrough. The PTC element  60  may have, within its normal operating temperature range (i.e., below its trip temperature), a resistance that is greater than a resistance of the fuse element  22 . 
     During normal operation of the fuse module  10 , current may flow through the busbar  14 , between the first and second terminal portions  26   a ,  26   b . Upon the occurrence of an overcurrent condition, wherein current flowing through the fuse module  10  exceeds the current rating of the fuse element  22 , the fuse element  22  may melt or otherwise separate. The current may then be diverted to flow through the only available alternate path, i.e., through the PTC element  60 . Since the current can flow through this alternate path, electrical potential is not able to accumulate between the separated ends of the melted fuse element  22 , thereby precluding the formation and propagation of an electrical arc therebetween. 
     Referring to  FIG. 4 , another embodiment of the present disclosure is contemplated in which a current sensing module  70  (e.g., a current sensor with a microprocessor) may be connected to one of the terminal portions  26   a ,  26   b  of the busbar  14  and to the pyrotechnic ignitor  44   a  of the PI  18 . The current sensing module  70  may be configured to measure a current in the busbar  14  and, upon detection of a current above a predefined threshold, may send an initiation signal to the pyrotechnic ignitor  44   a , detonating the pyrotechnic ignitor  44   a  and breaking the fuse element  22  as described above. The current sensing module  70  may be programmed to send the initiation signal immediately or after a desired, predetermined amount of time (e.g., 10 milliseconds) and in response to detecting a desired, predetermined amount of current in the busbar  14 . In various embodiments, the current sensing module  70  may also be connected to the controller  45 , and the current sensing module  70  may be configured to send an initiation signal to the pyrotechnic ignitor  44   a  only if certain predetermined conditions are met. For example, the current sensing module  70  may be configured to send an initiation signal to the pyrotechnic ignitor  44   a  if the current sensing module  70  detects more than a predetermined amount of current in the busbar  14  and if the controller  45  provides an indication of a collision to the current sensing module  70 . The present disclosure is not limited in this regard. 
     In view of the foregoing description, it will be appreciated that the active/passive fuse modules of the present disclosure facilitate the implementation of both passive and active circuit protection elements (e.g., conventional fuse elements and a pyrotechnic interrupter) in single, compact, space-saving form factor that facilitates convenient installation for various applications. 
     As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “one embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. 
     While the present disclosure makes reference to certain embodiments, numerous modifications, alterations and changes to the described embodiments are possible without departing from the sphere and scope of the present disclosure, as defined in the appended claim(s). Accordingly, it is intended that the present disclosure not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof.