Electromechanical switching device assembly with a plunger tube bypass

Abstract

This disclosure presents apparatuses and systems that include an electromechanical switching device assembly with a plunger tube bypass. In a particular embodiment, an electromechanical switching device is disclosed that includes a pair of static contacts and a movable contact movable between an open position, spaced from the static contacts, and a closed position electrically coupling the static contacts. The device also includes a plunger operatively coupled to drive the movable contact and a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter. In addition, the device also includes a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube. In this embodiment, the confronting surfaces of the static core and the plunger form a direct ferromagnetic flux path that magnetically bypasses the plunger tube.

Description

ELECTROMECHANICAL SWITCHING DEVICE ASSEMBLY WITH A PLUNGER TUBE BYPASSFIELD OF THE TECHNOLOGY

[0001] The subject disclosure relates to apparatus, systems, and devices that include an electromechanical switching device assembly with a plunger tube bypass.BACKGROUND

[0002] Electromechanical switching devices, such as contactors and relays, are crucial components within electrical systems, tasked with efficiently managing the flow of electrical current over specified durations. These devices incorporate a dynamic assembly responsible for the opening and closing of electrical circuits. At the heart of their functionality are magnetic circuits, which guide and harness the electromagnetic fields generated by the device's coils. This magnetic field drives the actuation of the switching device.

[0003] Existing designs position the static core, plunger, and associated ferromagnetic members so that comparatively large air gaps are present in the magnetic circuit. These gaps raise magnetic reluctance and promote fringing flux, which reduces the net force available to move or hold the contacts. The weaker actuation force can increase contact resistance, limit switching capacity, and degrade thermal and shock performance.SUMMARY

[0004] The following summary is meant to help one skilled in the art understand the various presently disclosed combinations of features. It is not meant to unduly limit the scope of any pending or future claims relating to the disclosure.

[0005] This disclosure presents apparatuses and systems that include an electromechanical switching device assembly with a plunger tube bypass. In a particular embodiment, an electromechanical switching device apparatus is disclosed that includes a movable contact for opening and closing connections with static contacts. In this example, the electromechanical switching device apparatus also includes a plunger coupled to the movable contact and an angled plunger tube that surrounds the plunger. The apparatus also includes a lower static core that is partially inserted into a lower opening of the angled plunger tube. In this embodiment, there is a direct pathway between the plunger and the lower static core, which contrasts with prior designs in which the plunger and lower static core / coil yoke are separated by the plunger tube. Bypassing the plunger tube establishes a direct flux path between the plunger and the lower static core / coil yoke, eliminating intervening air gaps, lowering magnetic reluctance, and suppressing fringing flux. The resulting higher flux density yieldsgreater coil force, thereby improving the performance and reliability of the electromechanical switching device.

[0006] In a particular embodiment, an electromechanical switching device is disclosed that includes a pair of static contacts and a movable contact configured to translate between an open position in which the movable contact is spaced from the pair of static contacts and a closed position in which the movable contact electrically bridges the pair of static contacts. The device also includes a plunger operatively coupled to drive the movable contact and a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter. In addition, the device also includes a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube. In this embodiment, the confronting surfaces of the static core and the plunger form a direct ferromagnetic flux path that magnetically bypasses the plunger tube.

[0007] In another embodiment, a method of operating an electromechanical switching device is disclosed that includes providing the electromechanical switching device. In this example, the electromechanical switching device includes a pair of static contacts, a movable contact configured to bridge the static contacts, and a plunger operatively coupled to drive the movable contact. The electromechanical switching device also includes a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter. In this embodiment, the electromechanical switching device includes a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube. The confronting surfaces of the static core and the plunger form a direct ferromagnetic flux path that magnetically bypasses the plunger tube. The electromechanical switching device also includes a return spring biasing the plunger away from the lower static core and a coil disposed coaxially about the plunger tube. The method also includes energizing the coil with a control current to establish magnetic flux that passes through the lower static core and traverses the air gap along the direct flux path to the plunger, thereby magnetically drawing the plunger toward the lower static core and driving the movable contact into electrical engagement with the static contacts to close a power circuit. In addition, the method also includes de-energizing the coil, whereby the magnetic flux collapses and a return spring biases the plunger away from the lower static core, retracting the movable contact from the static contacts to open the power circuit.

[0008] The foregoing and other objects, features and advantages of the invention will be apparent from the follow ing more particular descriptions of exemplary embodiments of theinvention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts of exemplary embodiments of the invention.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] One or more aspects of the present disclosure are discussed below with reference to the accompanying Figures. It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components may be included in one functional block or element.

[0010] Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. For purposes of clarity, however, not every component may be labeled in every drawing. The Figures are provided for the purposes of illustration and explanation and are not intended to be limiting. In the Figures:

[0011] FIG. 1 is a diagram illustrating a cross-sectional view of an electromechanical switching device with a known actuator assembly design.

[0012] FIG. 2 is a diagram illustrating a cross-sectional view of an electromechanical switching device assembly with a plunger tube bypass in accordance with at least one embodiment of the present disclosure.

[0013] FIG. 3A is a diagram illustrating flux plot outlining, shortly before close, a magnetic circuit in an electromechanical switching device assembly with a plunger tube bypass in accordance with at least one assembly process embodiment of the present disclosure.

[0014] FIG. 3B is a diagram illustrating flux plot outlining, shortly after close, a magnetic circuit in an electromechanical switching device assembly with a plunger tube bypass in accordance with at least one assembly process embodiment of the present disclosure.

[0015] FIG. 4 is a diagram illustrating a side-by-side comparison of the electromechanical switching device of FIG. 1 and the electromechanical switching device assembly of FIG. 2.

[0016] FIG. 5 is a diagram illustrating a method of operating an electromechanical switching device.DETAILED DESCRIPTION

[0017] In the following detailed description, various combinations of embodied features are disclosed in order to provide one skilled in the art an understanding of the aspects and implementations of the present disclosure. It will be understood by those of ordinary skill in the art that those may be practiced without some of the specific details that are set forth. In some instances, w ell-known methods, procedures, components and structures may not bedescribed in detail so as not to obscure the details of the implementations of the present disclosure. The following detailed description is not meant to unduly limit any present or future claim scope in this or subsequent related applications. This disclosure may use different names, or different numerical identifiers, to describe the same feature or partially the same part. Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. For purposes of clarity, however, not every component may be labeled in every drawing.

[0018] The terminology used herein for the purpose of describing particular examples is not intended to be limiting for further examples. Whenever a singular form such as “a”, “an” and “the” is used and using only a single element is neither explicitly nor implicitly defined as being mandatory, further examples may also use plural elements to implement the same functionality. Likewise, when a functionality is subsequently described as being implemented using multiple elements, further examples may implement the same functionality using a single element or processing entity . It will be further understood that the terms “comprises”, “comprising”, “includes” and / or “including”, when used, specify the presence of the stated features, integers, steps, operations, processes, acts, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, processes, acts, elements, components and / or any group thereof.

[0019] It will be understood that when an element is referred to as being “connected” or “coupled” to another element, the elements may be directly connected or coupled or via one or more intervening elements. If two elements A and B are combined using an “or”, this is to be understood to disclose all possible combinations, i.e., only A, only B, as well as A and B. An alternative wording for the same combinations is “at least one of A and B”. The same applies for combinations of more than two elements.

[0020] Accordingly, while further examples are capable of various modifications and alternative forms, some particular examples thereof are shown in the figures and will subsequently be described in detail. However, this detailed description does not limit further examples to the particular forms described. Further examples may cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0021] This disclosure details a novel, high-efficiency electromechanical switching device assembly (“contactor actuator”). The disclosed switching device includes a plunger tube with an opening that allows for a smaller clearance between the plunger and lower static core / coil yoke. This design reduces the air gaps between the ferromagnetic components in the actuator by providing a direct pathway between the coil yoke / static core and plunger. This is done bygiving the plunger tube an opening or “by -bass’' for the coil yoke / static core. By decreasing the clearance or “air gap” between the plunger and lower static core, the design increases the efficiency of the magnetic circuit, which drives the plunger’s motion, allowing for more magnetic force from the same coil and power. In a particular embodiment, this increase in efficiency allows for an increase in mechanical shock performance by using a stiffer return spring and using the same coil and power. Similarly, one iteration of the design reduces plunger mass which also increases mechanical shock performance without having to change the spring, coil, or coil power. Alternatively, increased actuator efficiency allows the new design to meet the performance of current designs, but with reduced coil pow er and reduced coil windings in the new design, which allows for cost savings in the coil.

[0022] For further explanation, FIG. 1 sets forth a diagram illustrating a cross-sectional view of an electromechanical switching device 100 with a known actuator design. The switching device 100 includes an upper coil yoke 108 and a low er coil yoke 196 that surround a coil assembly 193 that includes a plunger tube 194 and a coil enclosure 195. A lower static core 190 is positioned between the plunger tube 194 and the coil enclosure 195. The coil enclosure 195 surrounds a coil 166 and the plunger tube 194 surrounds a plunger assembly having a plunger 101 coupled to a plunger shaft 102. The upper coil yoke 108 is coupled to upper static core 103 and a plunger spring 104 is coupled between the upper static core 103 and the plunger 101. The switching device 100 also includes fixed contacts 122, 124 and a movable contact 120. The movable contact 120 is configured to create or break the connection between the fixed contacts 122, 124 in response to movement of the plunger assembly.

[0023] In the open state, the movable contact 120 is not in contact with the fixed contacts 122, 124. such that no current flows between the fixed contacts 122, 124. In this open state, the plunger spring 104 is configured to apply a pre-load force on the plunger 101 to prevent the plunger assembly from moving to a closed state. In the closed state, the movable contact 120 is in contact with the fixed contacts 122, 124 such that current flow s between the fixed contacts 122. 124 through the movable contact 120.

[0024] The coil consists of windings of conductive material such as copper or aluminum. When the coil 166 is connected to a low- voltage power source and current flows through the windings a strong magnetic field is generated that flows through the magnetic circuit pathways of the electromechanical switching device assembly. This magnetic field is guided and amplified by the coil yoke and static core(s) which are made of ferromagnetic materials such as low-carbon steel. This path that the magnetic field travels on is known as themagnetic circuit. The magnetic field is guided to the plunger 101, which resides within the enclosed plunger tube 194, and magnetizes it. The magnetized plunger 101 is then attracted by a magnetic force to the upper static core 103. The magnetic field forces the plunger 101 with upper direction. When enough magnetic force is generated, the plunger 101 will overcome any retaining spring forces (pre-load force from the plunger spring 104) and begin to move thus closing the gap between the coil yoke / upper static core. The plunger 101 and the plunger shaft 102 drive the movable contact 120 toward the fixed contacts 122. 124 until the movable contact 120 is in a closed position in which contact is established between the movable contact 120 and the fixed contacts 122, 124, thus transitioning the switching device assembly 100 from the open state to the closed state. When the movable contact touches the stationary contacts, the high-voltage circuit is completed. During this operation, the movement of the plunger 101 towards the fixed contacts 122, 124 compresses the plunger spring 104.

[0025] When the coil 166 is disconnected from the low-voltage power source, the ferromagnetic components lose their magnetization and the magnetic force on the plunger decreases. The retaining spring (also known as the return spring) returns the plunger to its original position. That is, when the coil 166 is de-energized, the plunger 101 is driven downward from the force of the energy stored in the compressed plunger spring 104, and the plunger assembly pulls the movable contact 120 downward until the movable contact 120 is in an open position, thus breaking contact between the movable contact 120 and the fixed contacts 122, 124. In this example, the plunger spring 104 provides sufficient force load that prevents all movable parts from moving. The high holding force is needed to achieve high shock resistance in the open state.

[0026] For further explanation, FIG. 2 sets forth a diagram illustrating a cross-sectional view of an electromechanical switching device assembly 200 with a plunger tube bypass in accordance with at least one embodiment of the present disclosure. Only the low er (actuating) portion of the complete device is depicted; the upper power-contact portion is omitted for clarity. This actuator is responsible for translating coil energy into linear motion of the movable contact assembly that opens and closes a high-voltage circuit.

[0027] A ferromagnetic coil yoke 208 surrounds a coil 266. The coil, in turn, is disposed coaxially around and encircles a plunger tube 294 that houses a ferromagnetic plunger 201 and a pre-loaded return spring 204 extending betw een the plunger and the yoke. Above the plunger, a movable-contact carrier 220 (shown in outline) is mechanically coupled to theplunger and ultimately supports the movable contact (not shown), which mates with two stationary contacts (not shown) located in the upper assembly.

[0028] Plunger tube 294 departs from prior practice by incorporating a lateral (lower) opening 281 sized to receive a lower static core 290. The static core projects through the tube wall until its confronting surface 282 lies only a small, well-controlled air gap 284 from the confronting surface 283 of plunger 201. In a particular embodiment, the air gap 284 is smaller than the wall thickness 285 of the plunger tube 294. In a particular embodiment, the opening of the plunger tube is sealed to the lower static cored by a circumferential braze or weld, forming a continuous hermetic joint. Because the tube wall no longer separates these two ferromagnetic members, the confronting surfaces 282, 283 of the static core and the plunger form a direct ferromagnetic flux path that magnetically bypasses the plunger tube, markedly reducing reluctance and fringing.

[0029] In the open state, the movable contact is not in contact with the fixed contacts, such that no current flows between the fixed contacts. In this open state, the return spring 204 is configured to apply a pre-load force on the plunger 201 to prevent the plunger assembly from moving to a closed state. In the closed state, the movable contact is in contact with the fixed contacts such that current flows between the fixed contacts through the movable contact.

[0030] The coil 266 consists of windings of conductive material such as copper or aluminum. When the coil 266 is connected to a low-voltage power source (not pictured) and current flows through the windings a strong magnetic field is generated that flows through the magnetic circuit pathways of the electromechanical switching device assembly. This magnetic field is guided and amplified by the coil yoke and static core(s) which are made of ferromagnetic materials such as low-carbon steel. The coil yoke is magnetically coupled to the lower static core. This path that the magnetic field travels on is known as the magnetic circuit. The magnetic field is guided to the plunger and magnetizes it. The magnetized plunger is then attracted by a magnetic force to a portion of the coil yoke. The magnetic field forces the plunger 201 with upper direction. When enough magnetic force is generated, the plunger will overcome any retaining spring forces (pre-load force from the return spring 204) and begin to move thus closing the gap between the plunger and upper coil yoke. The plunger 201 drives the movable contact carrier 220 towards the fixed contacts until the movable contact is in a closed position in which contact is established between the movable contact and the fixed contacts, thus transitioning the switching device assembly 200 from the open state to the closed state. When the movable contact touches the stationary contacts, thehigh-voltage circuit is completed. During this operation, the movement of the plunger 201 towards the fixed contacts compresses the return spring 204.

[0031] When the coil 266 is disconnected from the low-voltage power source, the ferromagnetic components lose their magnetization and the magnetic force on the plunger 201 decreases. The return spring 204 returns the plunger to its original position. That is, when the coil 266 is de-energized, the plunger 201 is driven downward from the force of the energy stored in the compressed return spring 204, and the plunger assembly pulls the movable contact carrier 220 dow w ard until the movable contact is in an open position, thus breaking contact between the movable contact and the fixed contacts. In this example, the return spring 204 provides sufficient force load that prevents all movable parts from moving. The high holding force is needed to achieve high shock resistance in the open state.

[0032] Plunger tube 294 and the adjacent turns of coil 266 define a frustoconical transition section that starts immediately above the bypass aperture and merges with the tube’s main cylindrical body. The transition section is formed by an angled segment 286 of the plunger tube, a complementary angled surface 288 on plunger 201, and a complementary angled surface 296 of the coil. At its widest plane perpendicular to plunger travel, angled segment 286 has an inner diameter greater than the inner diameter 291 of opening 281. By allowing the coil’s inner winding diameter to taper toward the reduced gap between plunger 201 and lower static core 290, the design preserves tight magnetic coupling along the entire flux path while keeping the actuator’s outer diameter and mounting interfaces unchanged. The taper therefore permits the same pull-in force with fewer coil ampere-turns — or, for a given coil, provides additional force margin.

[0033] In certain embodiments the stack formed by lower static core 290 and coil yoke 208 is axially extended relative to legacy designs. In a particular embodiment, the lower static core has an axial length 293 greater than an axial length 295 of the plunger 201. The additional ferromagnetic mass stores more magnetic energy and allow s the plunger to be shortened by an equivalent amount, trimming plunger mass while maintaining the same stroke. A lighter plunger reduces inertial loading when the device is subjected to shock or vibration, resulting in more stable contact engagement and reduced risk of bounce during high-G events.

[0034] To streamline assembly, plunger 201 may be machined or formed with an integral attachment feature — for example, a circumferential groove, an upset collar, or a shallow^ recess. Movable-contact carrier 220 can then be secured to this feature by one of several production-oriented methods: a resilient snap-fit that eliminates secondary hardware, a localized braze or weld that ensures permanent metallurgical bonding, or an orbital-formingoperation that flares the plunger end to lock the carrier in place. Each technique supports high repeatability and short cycle times on automated lines.

[0035] Conventional contactors house the plunger entirely within an unbroken tube wall, compelling magnetic flux to cross two air gaps and a non-magnetic sleeve before reaching the plunger. The bypass architecture depicted in FIG. 2 eliminates the sleeve from the primary flux path, thereby shortening the magnetic circuit, lowering its reluctance, and greatly reducing fringing. The resulting efficiency gains translate into faster actuation, lower steadystate coil heating, and improved electrical endurance, all while preserving the external dimensions and connection scheme familiar to existing installations.

[0036] For further explanation, FIG. 3 A sets forth a diagram illustrating, shortly before contact closure, a flux plot of the magnetic circuit within the plunger-tube-bypass actuator. The figure shows one half of a two-dimensional cross-section; symmetry about the vertical axis allows the entire electromagnetic behavior to be inferred from this single slice. Contours of constant magnetic vector potential — often called flux lines — cluster tightly between the confronting faces of lower static core 290 and plunger 201, confirming that the bypass aperture routes the dominant share of flux through this single, narrow air gap. Only a few lines fringe into the non-magnetic plunger-tube wall, indicating that the wall now carries negligible flux and, therefore, contributes little reluctance to the circuit.

[0037] FIG. 3B captures the actuator state immediately after the plunger has completed its stroke and the movable contact has seated against the stationary contacts. With the working air gap essentially eliminated, the flux path becomes even more compact and the contour density inside core 290 and plunger 201 intensifies. The plot shows localized saturation near the plunger nose while the elongated core body remains below its saturation threshold, preserving additional holding-force margin against coil-current or temperature variations. This concentrated field distribution demonstrates how the bypass architecture sustains a high magnetic-pressure region exactly where mechanical force is required.

[0038] By comparison, a legacy actuator that fully encloses the plunger inside an uninterrupted tube exhibits broader flux dispersion and two reluctance peaks: one across the tube wall and another across a larger plunger-to-core gap. The bypass geometry in FIGs. 3A and 3B collapses those two barriers into a single, shorter gap, yielding steeper contour gradients and a markedly lower overall reluctance. The visual evidence corroborates the earlier analytical discussion: the shortened magnetic path translates a greater fraction of the coil’s ampere-turns into useful mechanical work, enabling faster actuation, reduced coil losses, and improved contact endurance relative to fully sleeved designs.

[0039] For further explanation, Figure 4 provides a split-view comparison: the left half recreates the legacy actuator of Figure 1, while the right half shows the bypass actuator of Figure 2. In the legacy configuration the plunger is completely surrounded by a continuous plunger tube. Magnetic flux must cross two non-trivial gaps — first from the lower static core into the non-magnetic tube wall, and then from the tube wall into the plunger — represented by the compound clearance 402. Those successive air gaps, together with the interposed sleeve, lengthen the magnetic path and raise circuit reluctance.

[0040] The bypass architecture on the right removes the sleeve from the primary flux path by allowing the lower static core 290 to project directly through a lateral aperture in plunger tube 294. The working air gap is reduced to the single, much smaller clearance 404, and the fringing present in the legacy design largely disappears. Above the aperture, the plunger tube and the surrounding turns of coil 266 taper inward along angled segment 406, enabling the coil’s inner winding diameter to follow the reduced plunger-to-core spacing. This tighter fit improves magnetic coupling without increasing the overall diameter of the actuator.

[0041] The ferromagnetic stack in the bypass design is also axially longer than in the legacy unit, which permits a shorter plunger for the same stroke length. Lower plunger mass diminishes inertial forces during shock or vibration and helps the movable contacts remain fully seated. At the same time, the extended static core offers additional magnetic volume, reducing the likelihood of saturation under high coil current.

[0042] Electromagnetically, the shorter flux path and improved coupling mean that the bypass actuator achieves the required pull-in force with less current or, conversely, supplies more force for identical coil ratings. Faster closure shortens arcing duration and mitigates contact erosion; lower steady-state current reduces heat rise, easing thermal stress on insulation. Because fewer conductor turns are needed to reach specification, coil winding time and copper consumption fall, yielding material and production savings.

[0043] The bypass architecture converts a larger share of electrical input into useful mechanical work, resulting in an actuator that closes more quickly, holds more securely, dissipates less power, and withstands higher mechanical shock than the fully sleeved design of Figure 1. These improvements directly enhance service life, switching capacity, and operating efficiency for the end user.

[0044] For further explanation, FIG. 5 sets forth a diagram illustrating a method of operating an electromechanical switching device. The method of FIG. 5 includes providing 502 the electromechanical switching device. Providing 502 the electromechanical switching device may be carried out by fabricating and assembling all constituent parts — coil, plunger, plungertube, static core, contacts, and housing — on a production line and delivering the finished unit to an end user. The step may alternatively be satisfied by procuring a fully assembled device from a third-party supplier and installing it into the target electrical system in place of a conventional contactor or relay. In another implementation, an existing switching device can be disassembled, retrofitted with the disclosed plunger-tube-bypass actuator module, and reassembled, thereby providing the improved device without producing an entirely new unit.

[0045] In a particular embodiment, the electromechanical switching device includes a pair of static contacts, a movable contact configured to bridge the static contacts, and a plunger operatively coupled to drive the movable contact. The electromechanical switching device also includes a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter. In this embodiment, the electromechanical switching device includes a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube. The confronting surfaces of the static core and the plunger form a direct ferromagnetic flux path that magnetically bypasses the plunger tube. The electromechanical switching device also includes a return spring biasing the plunger away from the lower static core and a coil disposed coaxially about the plunger tube.

[0046] The method also includes energizing 504 the coil with a control current to establish magnetic flux that passes through the lower static core and traverses the air gap along the direct flux path to the plunger, thereby magnetically drawing the plunger toward the lower static core and driving the movable contact into electrical engagement with the static contacts to close a power circuit. Energizing 504 is carried out by applying a low-voltage control current to coil 266 so that ampere-tums build around plunger tube 294. The resulting magnetic field is guided by coil yoke 208 into lower static core 290 and then crosses the reduced air gap directly to plunger 201 along the bypass path shown in FIG. 2. This concentrated flux produces an attractive force that exceeds the preload of return spring 204 and any sliding friction within the tube. Plunger 201 is therefore draw n upward toward coil yoke 208, simultaneously compressing spring 204. The upward motion is transmitted through movable-contact carrier 220, bringing the movable contact into firm electrical engagement with the static contacts and completing the power circuit. Once the current is regulated at its holding value, the magnetic flux remains steady, maintaining the plunger in its attracted position and the contacts in the closed state until de-energization is commanded.

[0047] Energizing the coil through the plunger-tube bypass of FIG. 2 removes the thick sleeve that separates the plunger from the static core in legacy contactors. With the principalair gap drastically reduced, the magnetic circuit exhibits lower reluctance and higher flux density, so a given coil current produces substantially more attractive force. This stronger actuation delivers faster closing, which limits arcing and contact erosion, while also ensuring reliable pull-in even under elevated temperatures or low-voltage conditions. The added force margin allows the use of stiffer return springs, enhancing shock and vibration resilience, and permits downsizing the coil to reduce copper usage, steady-state heating, and overall cost. Collectively, these benefits improve switching capacity, service life, and energy efficiency compared with fully sleeved prior designs.

[0048] The method also includes de-energizing 506 the coil, whereby the magnetic flux collapses and a return spring biases the plunger away from the lower static core, retracting the movable contact from the static contacts to open the power circuit. De-energizing 506 coil 266 may be carried out by opening the control circuit that delivers low-voltage power to the coil terminals, thereby interrupting current flow. With current removed, the magnetic field linking lower static core 290 and plunger 201 collapses along the flux path shown in FIG. 2. As flux density falls, the residual attractive force between the confronting ferromagnetic faces becomes weaker than the preload applied by return spring 204. Spring 204 then expands, propelling plunger 201 downward within plunger tube 294 and rapidly widening the air gap between the plunger and lower static core. This downward motion is transmitted through movable-contact carrier 220, withdrawing the movable contact from the unseen static contacts and breaking the power circuit. Once the contacts are open, coil 266 remains unenergized until the control circuit again reconnects the low-voltage source to repeat the operating cycle.

[0049] During de-energization the bypass architecture lets magnetic flux collapse quickly because the reduced air gaps allows for better magnetic diffusion . The return spring therefore overcomes the waning attraction almost instantaneously, snapping the plunger away from the static core and providing a crisp, full-stroke opening of the contacts. Faster, more decisive separation shortens the arcing interval, limits contact pitting, and restores dielectric isolation sooner, which improves service life and safety. The predictable release also permits tighter coordination with upstream protection and lets the control circuit drop coil power as soon as conduction ceases, lowering energy consumption and heat rise compared with legacy designs that linger in a partially magnetized state.

[0050] The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, apparatuses, and methods, according to various embodiments of the present invention. In this regard, eachblock in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved.

[0051] Advantages and features of the present disclosure can be further described by the following statements:

[0052] 1. An electromechanical switching device comprising: a pair of static contacts; a movable contact configured to translate between an open position in which the movable contact is spaced from the pair of static contacts and a closed position in which the movable contact electrically bridges the pair of static contacts; a plunger operatively coupled to drive the movable contact; a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter; and a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube, the confronting surfaces of the static core and the plunger forming a direct ferromagnetic flux path that magnetically bypasses the plunger tube.

[0053] 2. The electromechanical switching device of statement 1 wherein the plunger tube further includes an angled segment located above the lower opening, the angled segment having a second inner diameter greater than the first inner diameter to enhance magnetic coupling with a coil surrounding the plunger tube.

[0054] 3. The electromechanical switching device of statement 1 or 2, further comprising a coil disposed coaxially around the plunger tube.

[0055] 4. The electromechanical switching device of any of statements 1-3, further comprising a coil yoke surrounding the coil and magnetically coupled to the lower static core.

[0056] 5. The electromechanical switching device of any of statements 1-4, further comprising a return spring compressed between the plunger and the coil yoke and biasing the movable contact toward the open position.

[0057] 6. The electromechanical switching device of any of statements 1-5, wherein the lower opening is sealed to the lower static core by a circumferential braze.

[0058] 7. The electromechanical switching device of any of statements 1-6, wherein the braze forms a continuous hermetic joint.

[0059] 8. The electromechanical switching device of any of statements 1-5, wherein the lower opening is sealed to the lower static core by a weld.

[0060] 9. The electromechanical switching device of any of statements 1-8, further comprising a movable contact carrier located between the plunger and the movable contact.

[0061] 10. The electromechanical switching device of any of statements 1-9, wherein the movable contact carrier is attached to the plunger by a snap-fit coupling.

[0062] 11. The electromechanical switching device of any of statements 1-9, wherein the movable contact carrier is attached to the plunger by orbital forming of an end portion of the plunger.

[0063] 12. The electromechanical switching device of any of statements 1-9, wherein the movable contact carrier is attached to the plunger by welding.

[0064] 13. The electromechanical switching device of any of statements 1-12, wherein the lower static core has an axial length greater than an axial length of the plunger tube.

[0065] 14. A method of operating an electromechanical switching device, the method comprising: providing the electromechanical switching device, the electromechanical switching device including: a pair of static contacts; a movable contact configured to bridge the static contacts; a plunger operatively coupled to drive the movable contact; a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter; a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube, the confronting surfaces of the static core and the plunger forming a direct ferromagnetic flux path that magnetically bypasses the plunger tube; a return spring biasing the plunger away from the lower static core; and a coil disposed coaxially about the plunger tube; energizing the coil with a control current to establish magnetic flux that passes through the lower static core and traverses the air gap along the direct flux path to the plunger, thereby magnetically drawing the plunger toward the lower static core and driving the movable contact into electrical engagement with the static contacts to close a power circuit; and de-energizing the coil, whereby the magnetic flux collapses and a return spring biases the plunger away from the lower static core, retracting the movable contact from the static contacts to open the power circuit.

[0066] 15. The method of statement 14, wherein the plunger tube further includes an angled segment located above the lower opening, the angled segment having a second inner diameter greater than the first inner diameter to enhance magnetic coupling with a surrounding coil.

[0067] 16. The method of statement 14 or 15, wherein the electromechanical switching device further includes a coil yoke surrounding the coil and magnetically coupled to the lower static core.

[0068] 17. The method of any of statements 14-16, wherein the electromechanical switching device further includes a movable contact carrier located between the plunger and the movable contact.

[0069] 18. The method of any of statements 14-17, wherein the movable contact carrier is attached to the plunger by snap-fit coupling.

[0070] 19. The method of any of statements 14-17, wherein the movable contact carrier is attached to the plunger by orbital forming of an end portion of the plunger.

[0071] 20. The method of any of statements 14-19, wherein the lower static core has an axial length greater than an axial length of the plunger tube.

[0072] It will be understood from the foregoing description that modifications and changes may be made in various embodiments of the present disclosure without departing from its true spirit. The descriptions in this specification are for purposes of illustration only and are not to be construed in a limiting sense. The scope of the present disclosure is limited only by the language of the following claims.

Claims

CLAIMSWhat is claimed is:

1. An electromechanical switching device comprising: a pair of static contacts; a movable contact configured to translate between an open position in which the movable contact is spaced from the pair of static contacts and a closed position in which the movable contact electrically bridges the pair of static contacts; a plunger operatively coupled to drive the movable contact; a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter; and a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube, the confronting surfaces of the static core and the plunger forming a direct ferromagnetic flux path that magnetically bypasses the plunger tube.

2. The electromechanical switching device of claim 1 wherein the plunger tube further includes an angled segment located above the lower opening, the angled segment having a second inner diameter greater than the first inner diameter to enhance magnetic coupling with a coil surrounding the plunger tube.

3. The electromechanical switching device of claim 1, further comprising a coil disposed coaxially around the plunger tube.

4. The electromechanical switching device of claim 3, further comprising a coil yoke surrounding the coil and magnetically coupled to the lower static core.

5. The electromechanical switching device of claim 4, further comprising a return spring compressed between the plunger and the coil yoke and biasing the movable contact toward the open position.

6. The electromechanical switching device of claim 1, wherein the lower opening is sealed to the lower static core by a circumferential braze.

7. The electromechanical switching device of claim 6, wherein the braze forms a continuous hermetic joint.

8. The electromechanical switching device of claim 1, wherein the lower opening is sealed to the low er static core by a w eld.

9. The electromechanical switching device of claim 1, further comprising a movable contact carrier located between the plunger and the movable contact.

10. The electromechanical switching device of claim 9, wherein the movable contact earner is attached to the plunger by a snap-fit coupling.

11. The electromechanical switching device of claim 9, wherein the movable contact carrier is attached to the plunger by orbital forming of an end portion of the plunger.

12. The electromechanical switching device of claim 9, wherein the movable contact carrier is attached to the plunger by welding.

13. The electromechanical switching device of claim 1, wherein the lower static core has an axial length greater than an axial length of the plunger tube.

14. A method of operating an electromechanical switching device, the method comprising: providing the electromechanical switching device, the electromechanical switching device including: a pair of static contacts; a movable contact configured to bridge the static contacts; a plunger operatively coupled to drive the movable contact; a plunger tube surrounding the plunger and terminating in a lower opening having a first inner diameter; a ferromagnetic lower static core projecting into the lower opening and confronting the plunger across an air gap smaller than a wall thickness of the plunger tube, the confronting surfaces of the static core and the plunger forming a direct ferromagnetic flux path that magnetically bypasses the plunger tube; a return spring biasing the plunger away from the low er static core; and a coil disposed coaxially about the plunger tube; energizing the coil with a control current to establish magnetic flux that passes through the lower static core and traverses the air gap along the direct flux path to the plunger, thereby magnetically drawing the plunger toward the lower static core and driving the movable contact into electrical engagement with the static contacts to close a power circuit; and de-energizing the coil, whereby the magnetic flux collapses and a return spring biases the plunger away from the low er static core, retracting the movable contact from the static contacts to open the power circuit.

15. The method of claim 14, wherein the plunger tube further includes an angled segment located above the lower opening, the angled segment having a second inner diametergreater than the first inner diameter to enhance magnetic coupling with a surrounding coil.

16. The method of claim 14, wherein the electromechanical switching device further includes a coil yoke surrounding the coil and magnetically coupled to the lower static core.

17. The method of claim 14, wherein the electromechanical switching device further includes a movable contact carrier located between the plunger and the movable contact.

18. The method of claim 18, wherein the movable contact carrier is attached to the plunger by snap-fit coupling.

19. The method of claim 18, wherein the movable contact carrier is attached to the plunger by orbital forming of an end portion of the plunger.

20. The method of claim 14, wherein the lower static core has an axial length greater than an axial length of the plunger tube.

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