Dynamically adjustable yoke assembly for electromechanical switching device

Abstract

The invention discloses an electromechanical switching device including a dynamically adjustable yoke assembly and a method of manufacturing the electromechanical switching device. In a particular embodiment, an electromechanical switching device includes: a movable contact; one or more magnetic upper yokes disposed above the movable contact and separated from the movable contact; a magnetic lower yoke disposed below the movable contact; and one or more collapsible biasing members supporting the magnetic upper yoke.

Description

Technical Field

[0001] The present invention relates to a dynamically adjustable yoke assembly for an electromechanical switching device. Background Art

[0002] As power levels across industries continue to increase, it becomes increasingly difficult to design systems that safely handle accidents and emergencies that result in high current short circuits. This difficulty is often caused by the inability to find switching devices designed to withstand such short circuits. Switching devices that cannot withstand exposure to short circuit events experience a variety of failure modes, from loss of switch function to fire and / or explosion. These failures are typically caused by short circuit currents that generate sufficient force to separate internal electrical contacts. This contact separation (or suspension) generates an arc that increases the series resistance of the switching device, generating extreme heat and the above-mentioned failure modes. Separation can be prevented by increasing the force between the electrical contacts that conduct the short circuit current, typically by assemblies of ferromagnetic yokes arranged around the current-carrying member. The yoke is physically separated by a functional gap, wherein an attractive magnetic field is generated in response to the current in the current-carrying member. The size of the functional gap affects the amount of increased contact force. Existing solutions have a static and constant-size functional gap when the electrical contacts are mated and the switching device is turned on, regardless of the applied current. This results in a static relationship between the current and the resulting increase in contact force, negatively affecting the characteristics of other devices. Summary of the invention

[0003] In a specific embodiment, a mechanism for preventing separation of electrical contacts during a short circuit of a switching device (such as a high voltage DC contactor, a fuse, and a pyrotechnic fuse) is described that utilizes a ferromagnetic yoke with a functional gap that is dynamically adjusted in response to an applied current when the electrical contacts are mated and the switching device is turned on. This creates a dynamic relationship between current and increased contact force that allows short circuit withstand performance to be maximized without the negative effects (e.g., reduced current interruption) experienced by prior solutions that utilize static and unchanging functional gaps.

[0004] Embodiments relate to an electromechanical switch device having a dynamically adjustable yoke assembly. The switch device includes: a movable contact; one or more magnetic upper yokes disposed above the movable contact; a magnetic lower yoke disposed below the movable contact; and one or more collapsible biasing members supporting the one or more yokes. In some examples, the one or more collapsible biasing members include one or more springs. In other examples, the one or more collapsible biasing members include one or more disconnect structures that release and allow movement in the one or more yokes. In some variations, the switch device includes a support member having one or more cavities for accommodating the one or more collapsible biasing members, wherein the one or more yokes are mounted on the one or more collapsible biasing members.

[0005] Another embodiment contemplates a method of manufacturing an electromechanical switch device having a dynamically adjustable yoke assembly. The method includes: mounting one or more magnetic upper yokes on one or more collapsible biasing members above a movable contact; and mounting a magnetic lower yoke below the movable member. In some variations, the one or more collapsible biasing members include one or more springs. In other variations, the one or more collapsible biasing members include one or more breakaway structures.

[0006] The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of exemplary embodiments of the invention, as illustrated in the accompanying drawings, wherein like reference numerals generally represent like parts of exemplary embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a diagram illustrating a cross-sectional view of an example simplified switchgear including a yoke assembly having a static functional gap.

[0008] Figure 2 is a diagram illustrating a cross-sectional view of another example simplified switch device including a yoke assembly having a static functional gap.

[0009] Figure 3 is a diagram showing the forces on the yoke assembly.

[0010] Figure 4 is a simplified illustration of a yoke assembly.

[0011] Figure 5 is a diagram illustrating a cross-sectional view of an example dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure.

[0012] Figure 6 is a diagram illustrating a cross-sectional view of another example dynamically adjustable yoke assembly according to at least one embodiment of the present disclosure;

[0013] Fig. 7A is a diagram illustrating a cross-sectional view of an example simplified switchgear including a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure.

[0014] Figure 7B is shown in the short circuit state Fig. 7A Illustration of a cross-sectional view of an example switching device.

[0015] Figure 8 is a diagram illustrating a side cross-sectional view of an example electromechanical switching apparatus including a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure.

[0016] Fig. 9 It shows Figure 8 Illustration of another side cross-sectional view of an example electromechanical switching device, where the view is rotated 90 degrees.

[0017] Fig.10 It shows Figure 8 Illustration of an exploded view of an example electromechanical switching device.

[0018] Fig.11A It shows Figure 8 An illustration of a side cross-sectional view of an example electromechanical switching device, wherein the switching device is in an open state.

[0019] Fig. 11B It shows Figure 8 Illustration of another side cross-sectional view of an example electromechanical switching device, wherein the switching device is in a closed state.

[0020] Fig. 11C It shows Figure 8 An illustration of a side cross-sectional view of an example electromechanical switching device, wherein the switching device is in a short circuit state.

[0021] Fig.12 is a diagram illustrating an upper isometric view of an electromechanical switch apparatus including a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure.

[0022] Fig.13 is a diagram illustrating an upper isometric view of a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure.

[0023] Fig.14 is a diagram illustrating an upper isometric view of an upper yoke of a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure.

[0024] Fig.15 is a graph of data indicative of short circuit and current interrupting performance of an electromechanical switching device having a dynamically adjustable yoke assembly according to at least one embodiment of the present disclosure.

[0025] Fig.16 is a graph of data indicating yoke force versus functional clearance for an electromechanical switching device including a dynamically adjustable yoke assembly according to at least one embodiment of the present disclosure.

[0026] Fig.17 A flow chart illustrating a method of manufacturing a dynamically adjustable yoke assembly for an electromechanical switch device according to at least one embodiment of the present disclosure. DETAILED DESCRIPTION

[0027] The terms used herein for the purpose of describing a particular example are not intended to limit other examples. Whenever a singular form such as "one", "a kind of" and "the" is used and only a single element is neither explicitly nor implicitly defined as mandatory, other examples may also use plural elements to implement the same function. Similarly, when a function is subsequently described as being implemented using multiple elements, further examples may use a single element or processing entity to implement the same function. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including" specify the presence of the features, wholes, steps, operations, processes, actions, elements and / or parts when used, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, processes, actions, elements, parts and / or any groups thereof.

[0028] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, these elements may be directly connected or coupled or via one or more intermediate elements. If two elements A and B are combined using "or", this should be understood to disclose all possible combinations, i.e., only A, only B, and A and B. An alternative wording for the same combination is "at least one of A and B". The same applies to combinations of more than two elements.

[0029] Therefore, although other examples can have different modifications and alternative forms, some specific examples thereof are shown in the drawings and will be described in detail later. However, this detailed description does not limit other examples to the specific forms described. Other examples may cover all modifications, equivalents and alternatives that fall within the scope of the present invention. Throughout the description of the drawings, the same reference numerals represent the same or similar elements, which, when compared to each other, can be implemented identically or in a modified form while providing the same or similar functions.

[0030] Electromechanical switching devices (such as contactors and relays) are designed to carry a certain amount of current for a specific period of time. Existing designs are difficult to perform during very high current, short duration events, commonly referred to as short circuits, which can cause internal electrical contacts to destructively separate (commonly referred to as contact suspension). The solution to this problem involves the use of ferromagnetic components (called yokes or armatures) that are configured around the electrical contacts so that the short-circuit current induces a magnetic field and attracts an "anti-suspension" force between the ferromagnetic components that prevent the electrical contacts from separating. For example, these yokes can be rigidly mounted to the moving components and the enclosure, thereby creating a functional gap between these yokes that does not change once the switching device is turned on. Static functional gaps and rigid mounting introduce performance compromises, thereby negatively affecting important performance characteristics (such as coil power consumption and current interruption). For example, the use of rigidly mounted yokes and static functional gaps means that high forces are generated any time current is applied to the switching device. This creates a compromise between the short-circuit withstand performance of desired high forces and the current interruption performance of desired low forces.

[0031] from Figure 1 Initially, exemplary apparatus, systems, and methods for manufacturing a dynamically adjustable yoke assembly for an electromechanical switchgear according to the present disclosure are described with reference to the accompanying drawings. Figure 1 A block diagram of an example of a floating yoke design for an electromechanical switch assembly 100 is shown. Figure 1 In the example of FIG. 1 , the assembly 100 includes a floating ferromagnetic upper yoke 102 and a ferromagnetic lower yoke 104, and a movable contact 106 driven by a plunger shaft 114. Figure 1In the example of , the upper yoke 102 is substantially planar and the lower yoke 104 is U-shaped. However, other examples may adopt a configuration opposite to this configuration, wherein the upper yoke 102 is U-shaped and the lower yoke 104 is planar. When the electromechanical switch is in the actuated position, the movable contact 106 is maintained in contact with one or more terminals (not shown) by the contact spring 108 and the actuator 112, thereby closing the switch. When the electromechanical switch is not in the actuated position, the movable contact 106 is pulled away from the terminal by the actuator 112 and the shaft 114, thereby opening the switch. During a short circuit event, the Lorentz force 116 generated by the increased current induced in the upper yoke 102 and the lower yoke 104 causes the yoke to clamp down on the movable contact 106, thereby maintaining the movable contact 106 in contact with the terminal to prevent a fault mode. During the circuit breaking period, the Lorentz force between the yokes 102, 104 helps to break the contact between the movable contact 106 and the terminal. However, in a floating yoke arrangement, the upper yoke 102 is coupled to the actuator subassembly via the support member 110, so the upper yoke 102 moves with the actuator subassembly (e.g., the actuator 112 and the shaft 114). While this may be advantageous because the tolerance stack-up of the yokes 102, 104 is constrained to a single subassembly, the anti-floating effect is constrained by the solenoid actuator. Furthermore, while the yokes 102, 104 supplement the spring force applied by the contact spring 108, they do not supplement the force applied by the actuator.

[0032] To explain further, Figure 2 A block diagram of an example of a fixed yoke design for an electromechanical switch assembly 200 is shown. Figure 1 In the example of FIG. 2 , the assembly 200 includes a fixed ferromagnetic upper yoke 202 and a ferromagnetic lower yoke 204 , and a movable contact 206 driven by an actuator 212 and a plunger shaft 214 within a guide member 210 . Figure 2 In the example of , the upper yoke 102 is substantially planar and the lower yoke 204 is U-shaped. However, other examples may adopt a configuration opposite to this configuration, wherein the upper yoke 202 is U-shaped and the lower yoke 204 is flat or planar. When the electromechanical switch is in the actuated position, the movable contact 206 is maintained in contact with one or more terminals (not shown) by the contact spring 208 and the actuator 212, thereby closing the switch. When the electromechanical switch is not in the actuated position, the movable contact 206 is pulled away from the terminal by the actuator 212 and the shaft 214, thereby opening the switch. During the disconnection period, the Lorentz force 216 between the yokes 202, 204 helps to disconnect the contact between the movable contact 206 and the terminal. In the fixed yoke arrangement, the upper yoke is fixed within the chamber of the electromechanical switch. Although the mass of the moving actuator subassembly is lower than that of the floating yoke design, the yokes 202, 204 may interfere with the actuator disconnection speed. Furthermore, arc interruption capability is directly coupled to the Lorentz force and requires very tight tolerances to balance anti-floating and interruption performance.

[0033] To explain further, Figure 3 A force diagram of an example electromechanical switch assembly 300 is shown. Figure 3 In the example of , the electromechanical switch assembly 300 includes two terminals 302, 304 and a movable contact 306 that contacts the terminals 302, 304 when the switch is closed, as depicted. During a short circuit event, arrow 310 represents the yoke force applied by the two yokes that hold the movable contacts 306 in the closed position, arrow 312 represents the spring force applied by the contact spring that holds the movable contacts 306 in the closed position, arrow 314 represents the repulsive force caused by the short circuit, and arrow 316 represents the reaction force of the actuator.

[0034] To explain further, Figure 4 A block diagram of an example yoke assembly 400 is shown, which has a fixed upper yoke 402 and a lower yoke 404 connected to a movable contact 406. In a fixed yoke arrangement, a static functional gap 408 is maintained between the upper yoke 402 and the lower yoke 404 when the movable contact 406 is in a closed position maintained by a contact spring 410. The distance selected for the static functional gap represents a trade-off between interruption performance and short circuit (anti-suspension) performance. While a high short circuit anti-suspension mechanism uses a magnetic yoke to increase contact force and prevent contact separation at high currents, the circuit breaking mechanism needs to quickly disconnect the contacts to interrupt the current, which is slowed down by the anti-suspension mechanism. The ideal performance of an electromechanical switch may depend on the current experienced by the switch. For example, a large functional gap results in a low anti-suspension force, but a faster circuit breaking. A small functional gap results in a high anti-suspension force, but a slower circuit breaking. In addition, the tolerance stacking between the yoke and actuator parameters may further confuse the performance of suspension and circuit breaking. Thus, a yoke assembly utilizing a static or fixed functional gap when the contacts are closed results in a greater trade-off between shorting performance and breaking performance because the shorting performance requires higher forces while the breaking performance requires lower forces (because higher forces reduce opening speed and negatively impact breaking).

[0035] In order to better coordinate these competing factors, a dynamically adjustable yoke assembly for an electromechanical switching device is provided in accordance with an embodiment of the present disclosure. An embodiment provides a movable upper yoke that is positioned and stabilized by one or more collapsible biasing members (e.g., springs) to create a Z-axis degree of freedom for the upper yoke so that it is no longer fixed. As will be explained in detail below, the position of the upper yoke is a function of the current level so that once the electromechanical switch transitions to a fault current level outside of the normal trip level, the upper yoke will be "pulled in" toward the lower yoke. During tripping, the upper yoke should not slow the disconnection speed of the contacts; however, at the suspended current of the contact spring, the yoke should help keep the contacts closed.

[0036] To explain further, Figure 5A diagram showing a front view of an example dynamically adjustable yoke assembly 500 for an electromechanical switch device is presented. The example yoke assembly 500 includes a ferromagnetic upper yoke 502, a ferromagnetic lower yoke 504, and a movable contact 506 coupled to or otherwise connected to the lower yoke 504. The upper yoke 502 is supported on a platform 510 of a support structure, housing, body or other fixed component by a collapsible biasing member that supports a biased position of the upper yoke 502 below the trigger current (i.e., during normal operation or circuit breaking operation) and facilitates the upper yoke 502 to assume different positions at or above the trigger current (i.e., during short circuit operation).

[0037] exist Figure 5 In the example of , these collapsible biasing members are implemented by springs 508. The springs 508 support the upper yoke 502 in a first position at normal current levels, where the Lorentz force acts to keep the movable contacts in a closed state. In this first position, the functional gap 512 between the upper yoke 502 and the lower yoke 504 can be relatively large to facilitate rapid disconnection. When the current exceeds the threshold, the spring 508 begins to collapse under the increased Lorentz force, thereby reducing the functional gap 512 between the upper yoke 502 and the lower yoke 504, and increasing the Lorentz force even more. The spring 508 can be selected so that the spring 508 responds to the trigger current. Consider an example in which the open circuit is characterized as 2500 amperes or less and the short circuit is characterized as 4000 amperes or more. In such an example, the spring force of spring 508 should always exceed the Lorentz force when the current in the electromechanical switch is less than the trigger current (e.g., 2500 amps), and the Lorentz force should always exceed the spring force when the current in the electromechanical switch is greater than the short circuit current (e.g., 4000 amps). Between these current levels, spring 508 should collapse.

[0038] To explain further, Figure 6 A diagram showing a front view of another example dynamically adjustable yoke assembly 600 for an electromechanical switch device is presented. The example yoke assembly 600 includes a ferromagnetic upper yoke 602, a ferromagnetic lower yoke 604, and a movable contact 606 coupled to or otherwise connected to the lower yoke 604. The biased position of the upper yoke 602 is supported on a platform 610 of a support structure, housing, body or other fixed component by a collapsible biasing member that supports the biased position of the upper yoke 602 below the trigger current (i.e., during normal operation or circuit breaking operation) and facilitates the upper yoke 602 to assume different positions at or above the trigger current (i.e., during short circuit operation).

[0039] exist Figure 6In an example of, these collapsible biasing members are implemented as a disconnect structure 608. In one example, the disconnect structure 608 is a support structure that folds, crushes, bends, or otherwise collapses in the presence of a force applied to the disconnect structure 608, thereby allowing the upper yoke 602 to have an additional degree of movement. In one example, during a short circuit, a firework ignites and pushes a portion of the upper yoke through a notched plastic disconnect feature. The disconnect structure 608 supports the upper yoke 602 in a first position at a normal current level, where the Lorentz force acts to keep the movable contact in a closed state. In this first position, the functional gap 612 between the upper yoke 602 and the lower yoke 604 can be relatively large to facilitate rapid disconnection. When the current exceeds a threshold, the disconnect structure 608 is generated under an increased Lorentz force, thereby reducing the functional gap 612 between the upper yoke 602 and the lower yoke 604, and even more increasing the Lorentz force. The disconnect structure 608 can be selected so that the disconnect structure 608 responds to a trigger current. Consider an example where the open circuit is characterized as 2500 amps or less and the short circuit is characterized as 4000 amps or more. In such an example, when the current in the electromechanical switch is less than the trigger current (e.g., 2500 amps), the resistance of the open structure 608 should always exceed the Lorentz force, and when the current in the electromechanical switch is greater than the short circuit current (e.g., 4000 amps), the Lorentz force should always exceed the resistance of the open structure 608. Between these current levels, the open structure 608 should collapse.

[0040] To explain further, Fig. 7A A cross-sectional block diagram of another exemplary dynamically adjustable yoke assembly 700 for an electromechanical switch device is shown. The example assembly 700 includes a ferromagnetic upper yoke 702, a ferromagnetic lower yoke 704, and a movable contact 706 coupled to the lower yoke 704 or otherwise connected thereto. The assembly 700 further includes a yoke spring 708, which supports the upper yoke 702 on a platform of a support member, a housing, a body or other static structure (not shown). In the actuated position, a plunger shaft 714 extending through the body member 712 in conjunction with the contact spring 710 holds the movable contact 706 in contact with one or more terminals (not shown) in a closed position. The movable contact 706 is free to move within a guide member 716 disposed on the body member 712. In the normal operating range or the circuit breaking range (e.g., less than 2500 amperes), a relatively large functional gap 718 is maintained. Figure 7B shows that during a short circuit Fig. 7A The dynamically adjustable yoke assembly 700. Figure 7B , the yoke spring 708 has collapsed, allowing the upper yoke 702 to move downward toward the lower yoke 704 , thereby reducing the functional gap 718 and increasing the Lorentz force 720 between the yokes 702 , 704 .

[0041] For further explanation, see Figure 8 to Figure 1 1 , an example electromechanical switching device 800 utilizing a dynamically adjustable yoke assembly for an electromechanical switching device is described. Figure 8 A diagram is presented showing a cross-sectional view of an example electromechanical switching device 800 utilizing a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure. Figure 8 The view of shows the electromechanical switching device 800 when the switch is open (eg, when the switch is off or in a non-actuated state during a circuit breaking condition). Fig. 9 A diagram is presented showing another cross-sectional view of an example electromechanical switching device 800 utilizing a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure. Fig. 9 The view relative to Figure 8 The view is rotated 90 degrees. Fig.10 A diagram is presented showing an exploded view of an example electromechanical switching device 800 utilizing a dynamically adjustable yoke assembly in accordance with at least one embodiment of the present disclosure.

[0042] The example electromechanical switch device 800 includes a body 802 having a mounting platform 804 and a cylindrical base 806. The base 806 at least partially accommodates a contact spring 808 and a plunger shaft 810, which holds a movable contact 814 in a closed position when the electromechanical switch device 800 is actuated and the switch is turned on. The electromechanical switch device 800 also includes a ferromagnetic lower yoke 812. In some examples, the lower yoke 812 is coupled to the movable contact 814 (e.g., by a rivet). In other examples, the lower yoke 812 is not coupled to the movable contact 814 and moves independently of the movable contact 814. In either case, the lower yoke 812 is connected to the movable contact 814 to provide additional force to hold the movable contact 814 in a closed position when the electromechanical switch device 800 is actuated. The lower yoke 812 includes a hole through which the plunger shaft 810 passes. The movable contact 814 is constructed of a conductive material (e.g., copper) and is configured to contact one or more terminals 826 of the electromechanical switch device 800. The movable contact 814 includes a hole that receives the plunger shaft 810. The electromechanical switch device 800 may include a contact ring 818 that secures the shaft 810 to the movable contact 814.

[0043] The electromechanical switch device 800 also includes a support member 816 for positioning the various components of the electromechanical switch device 800. For example, the lower yoke 812 and the movable contact 814 are free to move within the support member 816 through holes in the sides of the support member 816. The support member 816 includes two receptacles 828 for stabilizing one or more collapsible biasing members. Figure 8The ferromagnetic upper yoke 822 is positioned and stabilized on the support member 816 by the spring 820. Figure 8 The middle spring is depicted as a collapsible biasing member, but at least some embodiments are not limited thereto and may include other types of collapsible biasing members as discussed above. In some examples, a yoke spring 820 is attached to the upper yoke 822. The yoke spring 820 allows freedom up and down along the axis defined by the plunger shaft 810. The current in the movable contact 814 causes an anti-suspension Lorentz force between the yokes 812, 822, causing the yokes 812, 822 to clamp the movable contact 814, thereby providing additional force together with the contact spring 808 and the plunger shaft 810 to maintain the movable contact 814 in a closed position when the electromechanical switch device 800 is actuated. During a short circuit condition, when the current exceeds the selected trigger current, the Lorentz force between the yokes 812, 822 overcomes the spring force of the coil spring 820, causing the coil spring 820 to collapse. That is, the spring force of the spring 820 can be selected according to the desired trigger current so that a Lorentz force is generated between the yokes 812, 822 at or above the trigger current, which will overcome the spring force and collapse the spring. The collapse of the yoke spring 820 allows the upper yoke 822 to approach the lower yoke 812, thereby reducing the functional gap between the yokes 812, 822. The reduced functional gap allows an even stronger Lorentz force, thereby increasing the force applied by the yokes 812, 822 to maintain the closed position of the movable contact 814 during a short circuit.

[0044] The electromechanical switch device 800 also includes a housing 824 that can be connected to the body 802 to create a chamber for the yokes 812, 822, the yoke spring 820 and the support member 816 and the movable contact 814. The housing 824 includes one or more terminal contacts 826 for connecting to an external current source. The example electromechanical switch device 800 also includes a return spring 830 that is arranged between a plunger base 832 connected to the plunger shaft 810 and a return spring stop 834. The return spring 830 provides a biasing force on the plunger base 832 to push the plunger base 832 and the plunger shaft 810 in a direction away from the terminal contact 826, which in turn drives the movable contact 814 out of contact with the terminal contact 826. Fig. 9 In the position shown, the movable contact 814 is sufficiently removed from the terminal contact 826 to prevent arcing.

[0045] For further explanation, see FIG. 11A to FIG. 11C , describes an example operation of an example electromechanical switch device 800 utilizing a dynamically adjustable yoke assembly according to at least one embodiment of the present disclosure. Figure 8 resemblance, Fig.11AA cross-sectional view of an example electromechanical switch device 800 is shown when the switch is open (e.g., when the switch is off or in a non-actuated state during a circuit breaking condition). In this position, the functional gap 840 between the upper yoke 822 and the lower yoke 812 is at the mechanical maximum of the switch device 800.

[0046] Fig. 11B A cross-sectional view of an example electromechanical switching device 800 is shown when the switch is closed and operating under normal (ie, non-fault) current conditions. Fig. 11B In the embodiment of the present invention, the electromechanical switch device 800 is in an actuated state, so that the plunger shaft 810 and the contact spring 808 keep the movable contact 814 in contact with the terminal contact 826 to allow current to flow between the terminal contacts 826 through the movable contact 814. In the actuated state, the lower yoke 812 is also moved toward the upper yoke 822 by the actuation of the plunger shaft 810, thereby reducing the functional gap 840 to a predetermined distance for the normal operating mode. The movable contact 814 prevents the lower yoke 812 from moving closer to the upper yoke 822 than the predetermined distance due to its abutment with the terminal contact 826. Therefore, when the switch is in the closed state, the position of the lower yoke 812 is stationary. At this predetermined distance, the anti-suspension force is sufficient to clamp the lower yoke 812 against the terminal contact 826 to clamp the movable contact 814, while still allowing the contacts 814, 826 to be quickly separated during circuit breaking. The predetermined distance for the normal operating mode may be characterized as a minimum distance between the upper yoke 822 and the lower yoke 812 without movement of the upper yoke 822 .

[0047] Fig. 11B The example of illustrates an electromechanical switching device 800 in operation before reaching a first trigger current, wherein the trigger current is the current at which the yoke spring 820 in the electromechanical switching device 800 begins to collapse. Consider an example in which the trigger current is selected to be 2500 amperes, and in which the yoke spring 820 is selected to have a spring force that can withstand the Lorentz force between the upper yoke 822 and the lower yoke 812, while the current in the switching device 800 is below 2500 amperes. When the current in the switching device 800 reaches 2500 amperes, the Lorentz force that counteracts the spring force causes the yoke spring 820 to begin to collapse.

[0048] Fig. 11CA cross-sectional view of an example electromechanical switch device 800 is shown when the switch is closed and operating in a short circuit condition. After the trigger current is reached, the collapse of the yoke spring 820 allows the upper yoke 822 to be pulled toward the lower yoke 812, thereby reducing the distance of the functional gap 840. As the current in the switch increases above the trigger current, the Lorentz force also increases and counteracts the spring force of the yoke spring 820, causing the upper yoke 822 to be pulled away from the housing 824 and toward the lower yoke 812, further reducing the functional gap 840. Continuing with the above example, consider that the electromechanical switch device 800 is configured to respond to a short circuit condition in which the current in the switch device 800 is 4000 amperes or greater. At 4000 amperes and above, the Lorentz force between the upper yoke 822 and the lower yoke 812 exceeds the opposing spring force of the yoke spring 820 and causes the yoke spring 820 to completely collapse (i.e., be completely compressed), thereby further reducing the functional gap to the minimum possible functional gap of the switch device 800. Further reduction in the functional gap further increases the Lorentz force between the upper yoke 822 and the lower yoke 812, thereby increasing the force applied by the lower yoke 812 to the movable contact 814 to hold the movable contact 814 against the terminal contact 826 during the short circuit state.

[0049] To explain further, Fig.12 A diagram of an upper isometric view of a switch device 900 utilizing a dynamically adjustable yoke assembly according to at least one embodiment of the present disclosure is shown. The switch device 900 includes a body 902 and a support member 916 disposed on the body 902 within a housing 924. A movable contact 914 disposed within an internal cavity of the support member 916 moves within the support member 916 so that when the switch device 900 is closed, the movable contact 914 is placed in contact with one or more terminal contacts 926. The support member 916 includes one or more receptacles 928 for seating one or more collapsible biasing members (not shown).

[0050] To explain further, Fig.13 An illustration of an upper isometric view of a dynamically adjustable yoke assembly 1300 according to at least one embodiment of the present disclosure is shown. The yoke assembly 1300 includes a generally U-shaped ferromagnetic upper yoke 1304 having a base 1310 and two arms 1312 extending perpendicular to the base 1310. The base 1310 includes two tab portions 1314 extending from either end through the arms 1312, wherein the tab portions 1314 are configured to engage a collapsible biasing member (not shown). The yoke assembly 1300 also includes a ferromagnetic lower yoke 1302 that interfaces with contacts 1306. The contacts 1306 are mounted between the arms 1312 of the upper yoke 1304.

[0051] To explain further, Fig.14A diagram showing an upper isometric view of a magnetic upper yoke 1400 of a dynamically adjustable yoke assembly according to at least one embodiment of the present disclosure is shown. The ferromagnetic upper yoke 1400 is generally U-shaped having a base 1410 and two arms 1412 extending perpendicularly to the base 1410. The base 1410 includes two tab portions 1314 extending from both ends through the arms 1412, wherein the tab portions 1414 are configured for engaging a collapsible biasing member (not shown).

[0052] To explain further, Fig.15 An example graph curve 1500 is shown, which plots sample Lorentz force and sample spring force as a function of the functional gap distance between the yokes of a dynamically adjustable yoke assembly according to at least one embodiment of the present disclosure. The y-axis represents the Lorentz force between the upper yoke and the lower yoke measured in Newtons. The x-axis represents the distance of the functional gap between the upper yoke and the lower yoke. Curve 1502 shows the Lorentz force at 2500 amperes (e.g., an open circuit condition), while curve 1504 shows the Lorentz force at 4000 amperes (e.g., a short circuit condition). Curve 1506 shows the spring force of the yoke spring of the dynamically adjustable yoke assembly. As can be seen in this example, when the current in the electromechanical switching device is less than 2500A (during an open circuit), the spring force of the yoke spring should always exceed the Lorentz force, and when the current in the electromechanical switching device is greater than 4000A (during a short circuit), the Lorentz force should always exceed the spring force. Between 2500 amperes and 4000 amperes, the yoke spring should begin to collapse.

[0053] To explain further, Fig.16 An example graph 1600 is shown that plots sample yoke force as a function of current in an electromechanical switch utilizing a dynamically adjustable magnetic yoke assembly in accordance with at least one embodiment of the present disclosure. Lower yoke forces are required for current interruption (e.g., when less than a short circuit current), while higher yoke forces are required for short circuit protection (e.g., when at or above a short circuit current). Fig.16 In the example of , 4000 amperes is selected as the short circuit current. In a switchgear using a static functional gap, as represented by curve 1602, it can be seen that the yoke force responds differently to a current interruption condition than it responds to a short circuit condition. In a switchgear utilizing a dynamically adjusted functional gap according to the present disclosure, as represented by curve 1604, it can be seen that by reducing the functional gap between the yokes of the yoke assembly, the yoke force increases dramatically in response to a short circuit condition.

[0054] To explain further, Fig.17 A flow chart is shown of an example method of manufacturing a dynamically adjustable yoke assembly for an electromechanical switch device according to some embodiments of the present disclosure. Fig.17The method includes mounting 1702 a magnetic upper yoke on one or more collapsible biasing members above a movable contact 506, 814. In some examples, mounting 1702 the magnetic upper yoke is performed by mounting the magnetic upper yoke 502, 822 on one or more yoke springs 508, 820. In other examples, mounting 1702 the magnetic upper yoke 502, 822 is performed by mounting the magnetic upper yoke 602 on one or more breakaway structures 608. In some examples, the collapsible biasing members are disposed on a support member 816. In some examples, the movable contact 506, 814 moves within an internal cavity of the support member. Fig.17 The method also includes mounting 1704 a lower yoke 504, 604, 812 below the movable contact 506, 814. In some examples, the movable contact 506, 814 is located on or coupled to the lower yoke 504, 604, 812. In some examples, the lower yoke moves with the movable contact within the internal cavity of the support member 816.

[0055] The advantages and features of the present disclosure can be further described by the following statements:

[0056] 1. An electromechanical switching device having a dynamically adjustable magnetic yoke assembly, the switching device comprising: a movable contact; one or more magnetic upper yokes, which are arranged above the movable contact; a magnetic lower yoke, which is arranged below the movable contact; and one or more collapsible biasing members, which support the upper yoke.

[0057] 2. A switching device according to statement 1, wherein the one or more collapsible biasing members comprises one or more springs.

[0058] 3. A switching device according to statement 1 or 2, wherein one or more collapsible biasing members include one or more break-away structures.

[0059] 4. The switch device according to any one of statements 1 to 3 further comprises: a support member having one or more cavities to accommodate one or more collapsible biasing members, wherein one or more magnetic upper yokes are mounted on the one or more collapsible biasing members.

[0060] 5. The switching device according to any one of statements 1 to 4 further comprises: a dynamically adjustable functional gap between one or more magnetic upper yokes and a magnetic lower yoke, wherein the distance of the functional gap varies according to the current in the switching device.

[0061] 6. A switching device according to any one of statements 1 to 5, wherein, when the switching device is in an actuated state and the current in the switching device is lower than a first level, the dynamically adjustable functional gap has a first distance; wherein, when the switching device is in an actuated state and the current in the switching device is at a second level or higher than the second level, the dynamically adjustable functional gap has a second distance; wherein the first distance is greater than the second distance; and wherein the second level is greater than the first level.

[0062] 7. A switching device according to any of statements 1 to 6, wherein the second level indicates a short circuit.

[0063] 8. A switching device according to any one of statements 1 to 7, wherein one or more collapsible biasing members provide a biasing force to one or more magnetic upper yokes in a direction away from the magnetic lower yoke and in a direction opposite to the attractive magnetic force generated between one or more magnetic upper yokes and the magnetic lower yoke.

[0064] 9. A switching device according to any one of statements 1 to 8, wherein one or more collapsible biasing members are selected to provide a biasing force so that the attractive magnetic force generated between one or more magnetic upper yokes and the magnetic lower yoke at a predetermined current level is greater than the biasing force.

[0065] 10. A switching device according to any one of statements 1 to 9, wherein, when the current in the switching device is at or above a predetermined current level, one or more collapsible biasing members collapse in response to an attractive magnetic force generated between one or more magnetic upper yokes and a magnetic lower yoke.

[0066] 11. A switching device according to any one of statements 1 to 10, wherein one or more of the magnetic upper yokes comprises a U-shaped yoke and the magnetic lower yoke comprises a flat yoke.

[0067] 12. A switching device according to any one of statements 1 to 11, wherein one or more magnetic upper yokes include one or more tabs engaged with one or more collapsible biasing members.

[0068] 13. A switching device according to any one of statements 1 to 12, further comprising a plurality of terminals.

[0069] 14. A switching device according to any one of statements 1 to 13, wherein the movable contact contacts a plurality of terminals when the switching device is in an actuated state.

[0070] 15. A method of manufacturing an electromechanical switching device having a dynamically adjustable yoke assembly, the method comprising: mounting one or more magnetic upper yokes on one or more collapsible biasing members above a movable contact; and mounting a magnetic lower yoke below the movable contact.

[0071] 16. The method of statement 15, wherein the one or more collapsible biasing members comprise one or more springs.

[0072] 17. A method according to statement 15 or 16, wherein one or more collapsible biasing members include one or more break-away structures.

[0073] 18. A method according to any of statements 15 to 17, wherein one or more collapsible biasing members are disposed in a support member; and wherein the movable contact is configured to move within an internal cavity of the support member.

[0074] 19. A method according to any one of statements 15 to 18, wherein one or more collapsible biasing members provide a biasing force to one or more magnetic upper yokes in a direction away from the magnetic lower yoke and in a direction opposite to the attractive magnetic force generated between one or more magnetic upper yokes and the magnetic lower yoke.

[0075] 20. A method according to any one of statements 15 to 19, wherein one or more collapsible biasing members are selected to provide a biasing force such that an attractive magnetic force generated between one or more magnetic upper yokes and a magnetic lower yoke at a predetermined current level is greater than the biasing force.

[0076] In view of the above, the reader will appreciate that, unlike conventional electromechanical switchgear, embodiments according to the present disclosure utilize a dynamic functional gap that changes in response to an applied current. This allows the yoke to be optimized, resulting in a design that can exceed the short-circuit performance of conventional static designs without significant tradeoffs with other performance features. During current interruption, the functional gap is large and the forces generated are small, thereby limiting the effect of the ferromagnetic yoke on the current interruption performance. During a short circuit, the functional gap collapses to a very small size, greatly increasing the forces generated and providing the desired short-circuit withstand performance.

[0077] It will be understood from the foregoing description that modifications and changes may be made in different embodiments of the present disclosure without departing from the true spirit of the present disclosure. The description in this specification is for illustrative purposes only and should not be interpreted as limiting. The scope of the present disclosure is limited only by the language of the appended claims.

Claims

1. An electromechanical switch device having a dynamically adjustable yoke assembly, the switch device comprising: Movable contacts; one or more magnetic upper yokes disposed above the movable contacts; a magnetic lower yoke disposed below the movable contact; as well as One or more collapsible biasing members supporting the one or more magnetic upper yokes.

2. The switch device according to claim 1, wherein: The one or more collapsible biasing members include one or more springs.

3. The switch device according to claim 1, wherein: The one or more collapsible biasing members include one or more break-away structures.

4. The switch device according to claim 1, further comprising: A support member having one or more cavities to house the one or more collapsible biasing members, wherein the one or more magnetic upper yokes are mounted on the one or more collapsible biasing members.

5. The switch device according to claim 1, further comprising: A dynamically adjustable functional gap is between the one or more magnetic upper yokes and the magnetic lower yoke, wherein the distance of the functional gap varies depending on the current in the switching device.

6. The switch device according to claim 5, wherein: When the switching device is in an actuated state and the current in the switching device is lower than a first level, the dynamically adjustable functional gap has a first distance; wherein, when the switching device is in an actuated state and the current in the switching device is at a second level or higher than the second level, the dynamically adjustable functional gap has a second distance; wherein the first distance is greater than the second distance; and wherein the second level is greater than the first level.

7. The switch device according to claim 6, wherein: The second level indicates a short circuit.

8. The switch device according to claim 1, wherein: The one or more collapsible biasing members provide a biasing force to the one or more magnetic upper yokes in a direction away from the magnetic lower yoke and in a direction opposite to an attractive magnetic force generated between the one or more magnetic upper yokes and the magnetic lower yoke.

9. The switch device according to claim 8, wherein: The one or more collapsible biasing members are selected to provide the biasing force such that the attractive magnetic force generated between the one or more magnetic upper yokes and the magnetic lower yoke at a predetermined current level is greater than the biasing force.

10. The switch device according to claim 9, wherein: When the current in the switching device is at or above the predetermined current level, the one or more collapsible biasing members collapse in response to the attractive magnetic force generated between the one or more magnetic upper yokes and the magnetic lower yoke.

11. The switch device according to claim 1, wherein: The one or more magnetic upper yokes include a U-shaped yoke, and the magnetic lower yoke includes a flat yoke.

12. The switch device according to claim 11, wherein: The magnetic upper yoke includes one or more tabs engaged with the one or more collapsible biasing members.

13. The switch device of claim 1, further comprising a plurality of terminals.

14. The switch device according to claim 13, wherein: When the switch device is in an actuated state, the movable contacts contact the plurality of terminals.

15. A method of manufacturing an electromechanical switch device having a dynamically adjustable yoke assembly, the method comprising: mounting one or more magnetic upper yokes on the one or more collapsible biasing members above the movable contacts; as well as A magnetic lower yoke is mounted below the movable contact.

16. The method according to claim 15, wherein: The one or more collapsible biasing members include one or more springs.

17. The method according to claim 15, wherein: The one or more collapsible biasing members include one or more break-away structures.

18. The method according to claim 15, wherein: The one or more collapsible biasing members are disposed in a support member; and wherein the movable contact is configured to move within an internal cavity of the support member.

19. The method according to claim 18, wherein: The one or more collapsible biasing members provide a biasing force to the one or more magnetic upper yokes in a direction away from the magnetic lower yoke and in a direction opposite to an attractive magnetic force generated between the one or more magnetic upper yokes and the magnetic lower yoke.

20. The method according to claim 19, wherein: The one or more collapsible biasing members are selected to provide the biasing force such that the attractive magnetic force generated between the one or more magnetic upper yokes and the magnetic lower yoke is greater than the biasing force at a predetermined current level.

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