Push rod assembly and high-voltage direct current contactor

Abstract

The push rod assembly comprises a push rod, a push plate and two retainers, the push plate is arranged on the push rod, the two retainers are arranged on the push plate and located on the two sides of an auxiliary contact assembly respectively, the auxiliary contact assembly comprises a conducting piece and a partition part, and the conducting piece is arranged on the partition part. The blocking part is used for separating the two retainers, and the conducting sheet is arranged on the blocking part; the push rod assembly provided by the utility model adopts the layout of the two groups of main contacts, the two retainers are respectively used for fixing the movable contact assembly, and the two groups of main contacts can be ensured to be mutually independent through the layout that the auxiliary contact assembly is arranged in the middle and the two retainers and the movable contact assembly are respectively arranged at two sides, so that the breaking reliability and the thermal management performance of the whole equipment are improved; and the design is also provided with an auxiliary contact assembly, so that the opening and closing conditions of the movable contact piece and the static contact can be monitored in real time, and the safety of the equipment is further guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of contactor technology, and in particular to a push rod assembly and a high-voltage DC contactor. Background Technology

[0002] High-voltage DC contactors, as electrical devices for long-distance connection and disconnection of DC circuits, feature large control capacity, suitability for frequent operation, and remote intelligent control. They play a vital role in power systems and are widely used in solar energy systems, urban rail transit, subways, charging piles, energy storage battery packs, uninterruptible power supplies, and the communications industry. High-voltage DC contactors can withstand voltages of several thousand volts or even higher without breakdown or flashover, and can carry or disconnect currents of several hundred to several thousand amperes. The contact components are specially designed to ensure long lifespan and reliability under frequent operation and extreme working conditions. Furthermore, high-voltage DC contactors are small in size and light in weight, facilitating transportation, installation, and maintenance, reducing downtime and maintenance costs, thereby ensuring safe, efficient, and reliable power transmission.

[0003] The push rod assembly in a high-voltage DC contactor is a key component connecting the electromagnetic system and the contact system. Its main function is to drive the push rod through electromagnetic force after the coil is energized, thereby causing the contacts to close and open, realizing the connection and disconnection of the circuit. The push rod assembly typically consists of a push rod, a cage, and auxiliary contact components, which need to withstand frequent mechanical operations and the high temperatures generated by electric arcs.

[0004] In high-voltage DC contactors, the actuator assembly not only transmits the force generated by the electromagnetic system to ensure accurate contact closure and opening, but also operates in high-voltage and high-current environments. Therefore, its structure and materials must be able to withstand arc erosion and long-term thermal stress. Furthermore, the design of the actuator assembly should also consider reducing friction and wear to improve the contactor's mechanical and electrical life.

[0005] In related technologies, the push rod assembly in a high-voltage DC contactor cannot simultaneously control the opening and closing of two sets of contacts while also providing auxiliary contact functionality. Utility Model Content

[0006] The main purpose of this invention is to propose a push rod assembly and a high-voltage DC contactor, which aims to provide a push rod assembly with two sets of main contact layouts and auxiliary contact function.

[0007] To achieve the above objectives, the present invention proposes a push rod assembly, including a push rod, a push plate, and two retainers. The push plate is disposed on the push rod, and an auxiliary contact assembly is provided on the side of the push plate facing away from the push rod. The two retainers are disposed on the push plate and are respectively located on both sides of the auxiliary contact assembly. The auxiliary contact assembly includes a conductive piece and a partition, the partition being used to separate the two retainers, and the conductive piece being disposed on the partition.

[0008] In one embodiment, the retainer and the push plate together enclose a receiving space for accommodating the moving contact assembly;

[0009] The retainer and the push plate are respectively provided with two inner sidewalls with locking protrusions. The locking protrusions are located in the receiving space and are used to cooperate with the moving contact assembly for limiting.

[0010] In one embodiment, the retainer has a limiting boss on the side facing away from the auxiliary contact assembly. The limiting boss includes a first bent portion and a second bent portion connected to each other, and both the first bent portion and the second bent portion are integrally formed with the retainer.

[0011] In one embodiment, one end of the push rod is provided with a spline shaft, and the spline shaft and the push plate are integrally formed with rubber coating.

[0012] In one embodiment, the end of the push rod away from the spline shaft is provided with an external thread, which is used to screw and fix it to the iron core;

[0013] The push rod has a circumferential anti-rotation straight surface at one end near the external thread, which is used to prevent the push rod from rotating.

[0014] In one embodiment, the auxiliary contact assembly further includes an insulating sleeve fitted over the partition portion, with a portion of the partition portion extending out of the push plate;

[0015] The two ends of the partition are respectively provided with insulating ribs facing the push plate, and the partition, the insulating ribs and the push plate are all integrally formed structures.

[0016] In one embodiment, the partition further includes a bracket located between the two retainers, and the conductive piece is disposed on the bracket.

[0017] This utility model also proposes a high-voltage DC contactor, comprising:

[0018] The housing has a cavity, and a stationary contact and an auxiliary contact are provided inside the housing;

[0019] As described above, in the push rod assembly, a portion of the push rod extends out of the housing, and the push plate and both retainers are disposed within the receiving cavity; and

[0020] A moving contact assembly, comprising an elastic element and a moving contact piece, wherein the elastic element is disposed on the push plate and located within the retainer, and a magnetic plate is provided at one end of the elastic element away from the push plate, and the moving contact piece is disposed on the magnetic plate.

[0021] In one embodiment, the push plate has a limiting ring groove facing the retainer, and one end of the elastic member is disposed in the limiting ring groove.

[0022] In one embodiment, the high-voltage DC contactor further includes a drive mechanism, which is a magnetic device. The magnetic device includes a coil and an iron core. The coil is sleeved on the iron core, and the end of the push rod away from the moving contact piece is screwed to the iron core.

[0023] The present invention proposes a push rod assembly and a high-voltage DC contactor. The push rod assembly includes a push rod, a push plate, and two retainers. The push plate is located on the push rod, and an auxiliary contact assembly is located on the side of the push plate facing away from the push rod. The two retainers are located on the push plate and on both sides of the auxiliary contact assembly. The auxiliary contact assembly includes a conductive piece and an insulating sleeve, with the insulating sleeve fitted onto the conductive piece. This design adopts a layout of two sets of main contacts. The two retainers are used to fix the moving contact assembly. By centering the auxiliary contact assembly and separating the two retainers and the moving contact assembly on both sides, the two sets of main contacts can be ensured to be independent of each other and not affected by each other, thereby improving the overall disconnection reliability and thermal management performance of the equipment.

[0024] Furthermore, this design also incorporates auxiliary contact components, which can monitor the opening and closing status of the moving contact piece and the stationary contact in real time, further ensuring the safety of the equipment. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 A schematic diagram of a structure of an embodiment of the push rod assembly provided by this utility model;

[0027] Figure 2 for Figure 1 Schematic diagram of the mid-support structure;

[0028] Figure 3 for Figure 1 Schematic diagram of the middle cage;

[0029] Figure 4 for Figure 1 Schematic diagram of the middle push rod;

[0030] Figure 5 A schematic diagram of the internal structure of the high-voltage DC contactor provided by this utility model.

[0031] Explanation of icon numbers:

[0032] 100. Push rod assembly; 1. Push rod; 11. Splined shaft; 12. External thread; 13. Anti-rotation straight surface; 2. Push plate; 21. Limiting ring groove; 3. Cage; 31. Snap-fit ​​protrusion; 32. Limiting boss; 321. First bend; 322. Second bend; 4. Auxiliary contact assembly; 41. Conductive piece; 42. Partition; 43. Bracket; 44. Insulating rib; 5. Insulating sleeve; 200. Moving contact assembly; 210. Elastic element; 220. Moving contact piece; 230. Magnetic plate; 300. Auxiliary contact; 400. Drive mechanism.

[0033] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0035] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0036] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0037] This invention proposes a push rod assembly, which aims to provide a push rod assembly with two sets of main contacts and auxiliary contact function. Figures 1 to 5 This is a schematic diagram of one embodiment of the push rod assembly of this utility model.

[0038] Please refer to Figures 1 to 5 This utility model proposes a push rod assembly 100, including a push rod 1, a push plate 2 and two retainers 3. The push plate 2 is disposed on the push rod 1, and an auxiliary contact assembly 4 is provided on the side of the push plate 2 facing away from the push rod 1. The two retainers 3 are disposed on the push plate 2 and are respectively located on both sides of the auxiliary contact assembly 4. The auxiliary contact assembly 4 includes a conductive piece 41 and a partition 42. The partition 42 is used to separate the two retainers 3, and the conductive piece 41 is disposed on the partition 42.

[0039] The present invention proposes a push rod assembly 100 and a high-voltage DC contactor. The push rod assembly 100 includes a push rod 1, a push plate 2, and two retainers 3. The push plate 2 is disposed on the push rod 1, and an auxiliary contact assembly 4 is disposed on the side of the push plate 2 facing away from the push rod 1. The two retainers 3 are disposed on the push plate 2 and are respectively located on both sides of the auxiliary contact assembly 4. The auxiliary contact assembly 4 includes a conductive piece 41 and an insulating sleeve 5. The insulating sleeve 5 is sleeved on the conductive piece 41. This design adopts a layout of two sets of main contacts. The two retainers 3 are used to fix the moving contact assembly 200. By centering the auxiliary contact assembly 4 and distributing the two retainers 3 and the moving contact assembly 200 on both sides, the two sets of main contacts can be ensured to be independent of each other and not affected by each other, thereby improving the overall disconnection reliability and thermal management performance of the equipment.

[0040] In addition, this design also includes an auxiliary contact component 4, which can monitor the opening and closing status of the moving contact piece 220 and the stationary contact in real time, further ensuring the safety of the equipment.

[0041] In the contactor, the cage 3 primarily serves to support, fix, and limit the movement of the moving contact assembly 200. The cage 3 ensures that these critical components maintain the correct position and alignment during contactor operation, withstand the forces generated by mechanical operation, and transmit force when the contacts close and open. Furthermore, the cage 3 helps dissipate heat generated during contactor operation, maintaining the stability and durability of the equipment, which is crucial to the overall mechanical strength and electrical performance of the contactor. The push rod assembly 100 proposed in this case is equipped with two cages 3, and the entire contactor device adopts a two-set main contact layout, thus providing higher reliability and safety. This design allows the contactor to continue operating while one set of contacts is maintained or damaged, thereby ensuring continuous system operation. The two cages 3 enhance structural stability, ensuring precise alignment and stable contact of the contacts under high current and high voltage, reducing arcing and wear caused by poor contact. In addition, this design helps dissipate heat generated by arcing, improving the contactor's thermal management capabilities, extending contact life, and reducing maintenance costs.

[0042] During installation, a space is left between the retainer 3 and the push plate 2 to accommodate the moving contact assembly 200. The moving contact assembly 200 typically includes an elastic element 210, a moving contact piece 220, and a magnetic guide plate 230. For details, please refer to further documentation. Figure 5 One end of the elastic element 210 abuts against the push plate 2, and the other end abuts against the magnetic guide plate 230. The moving contact piece 220 is disposed on the magnetic guide plate 230. When the contactor is turned on or off, the elastic element 210 will continue to sway under the action of inertia, which will affect the stability of the system. In view of this, the retainer 3 is provided with locking protrusions 31 on both sides facing the magnetic guide plate 230. For details, please refer to further reference. Figure 3 In this embodiment, two spaced-apart snap-fit ​​protrusions 31 are provided on each side. The width of the magnetic plate 230 is slightly larger than the width between the snap-fit ​​protrusions 31 on both sides, thereby ensuring that the two sides of the magnetic plate 230 will abut and rub against the snap-fit ​​protrusions 31 on both sides, thus stopping its shaking under force. The presence of the snap-fit ​​protrusions 31 can greatly improve the overall stability of the system. It should be noted that the snap-fit ​​protrusions 31 can be fixed to the retainer 3 by snap-fitting or can be designed by integral molding. This utility model does not limit this. In one embodiment of this utility model, the snap-fit ​​protrusions 31 and the retainer 3 are integrally coated with glue to ensure that they have excellent insulation performance.

[0043] Considering that the push rod assembly 100 will move within the housing, a limiting boss 32 is provided on the side of the retainer 3 facing away from the auxiliary contact assembly 4 to limit and guide the push rod assembly 100. The limiting boss 32 includes a first bend 321 and a second bend 322 connected to each other. For details, please refer to further reading. Figure 3The limiting boss 32 protrudes between the top and bottom plates of the retainer 3. When the push rod assembly 100 tilts or rotates within the receiving cavity, the limiting boss 32 abuts against the cavity wall. Two limiting protrusions (not shown in the figure) are provided within the receiving cavity to match the limiting boss 32, thus limiting further tilting or rotation of the push rod assembly 100 and ensuring normal connection or disconnection of the contactor. The limiting boss 32 prevents other parts of the push rod assembly 100 from contacting or rubbing against the cavity wall, reducing the coefficient of friction between the push rod assembly 100 and the cavity wall, decreasing the amount of dust generated by friction within the receiving cavity, reducing the content of contaminants within the receiving cavity, and ensuring the cleanliness of the receiving cavity, thereby guaranteeing the reliability of the contactor's mechanical and electrical life. The partition ribs and limiting bosses 32 play a certain guiding role in the installation of the push rod assembly 100. At the same time, the partition ribs divide the space of the receiving cavity into multiple areas, which can, to a certain extent, prevent the dust generated by the arc burning of the contacts on both sides.

[0044] Understandably, the limiting boss 32 is integrally formed by the first bending part 321 and the second bending part 322. The bending protrusion has a certain elasticity so that the push rod assembly 100 can spring back to the center position after rotation. The side wall is provided with a through hole, and the two bending protrusions are located on both sides of the through hole. The through hole reduces the material used in the production of the cage 3 and also realizes the lightweight of the cage 3.

[0045] In one embodiment of this utility model, the push rod 1 is directly fixed to one side of the push plate 2 by overmolding. Overmolding is a manufacturing method that uses injection molding technology to coat a soft material (such as thermoplastic elastomer TPE) onto the surface or interior of a hard material (such as plastic or metal). Overmolding not only improves the insulation performance of the product but also enhances its functionality and durability. Since the push rod 1 is cylindrical, it is prone to rotation around its central axis under applied torque. Since the push rod 1 also acts as a transmission component, it is prone to relative rotation with the push plate 2. Therefore, this invention provides a splined shaft 11 at one end of the push rod 1. For details, please refer to further details. Figure 4 Firstly, the spline shaft 11 ensures more accurate and direct force transmission, thereby improving the contactor's operating sensitivity and reliability. Secondly, the spline shaft 11 can distribute the torque generated by the load, reduce wear, and extend the service life of the components. In addition, the spline structure can also provide a certain self-locking function, which can reduce the reliance on external locking devices in some cases and prevent the push rod 1 from rotating relative to the push plate 2.

[0046] The push rod 1 serves as a crucial transmission component between the drive system and the contact system. Its other end is connected to a movable iron core, around which a coil (not shown in the diagram) is positioned. When the coil is energized, it generates a magnetic field that drives the iron core up and down, thereby moving the push rod 1. This drives the moving contact piece 220 towards the stationary contact and closes with it, thus connecting the circuit. When the coil is de-energized, the magnetic field disappears, and the moving contact piece 220 returns to its initial position under the force of a spring, disconnecting from the stationary contact and cutting off the circuit. This drive method offers fast response, simple control, and allows for adjustment of the contactor's closing force by adjusting the coil current, ensuring reliable electrical connections in high-voltage DC systems. To prevent relative movement between the iron core and the push rod 1, the end of the push rod 1 furthest from the splined shaft 11 is provided with an external thread 12. For details, please refer to further documentation. Figure 4 The iron core is fixed by screwing the external thread 12 to the iron core. In addition, the push rod 1 has an anti-rotation straight surface 13 circumferentially formed at one end near the external thread 12. The iron core has a mounting groove to be filled. During installation, the anti-rotation straight surface 13 is inserted into the mounting groove, and then glue is filled into the mounting groove. After the glue cures, the anti-rotation straight surface 13 will cooperate with the cured glue block to prevent it from rotating relative to the iron core.

[0047] As electrical and mechanical life tests proceed, dust and particulate matter inside the contactor housing will gradually increase. This dust and particulate matter, upon falling onto the contact surface, will affect contact conductivity. While the main contacts will have the dust and particles burned off under high voltage and current, the auxiliary contacts 300, due to their lower current and voltage, cannot burn off the dust and particles, thus affecting the functionality of the auxiliary contact 300 assembly. To address this issue, the auxiliary contact assembly 4 also includes an insulating sleeve 5, which is fitted onto the partition portion 42. The insulating sleeve 5 effectively isolates the auxiliary contact assembly 4 from the internal cavity of the housing, thereby preventing dust and particulate matter from affecting contact conductivity after falling onto the auxiliary contact surface.

[0048] To achieve better insulation, a portion of the partition 42 extends beyond the push plate 2. For details, please refer to further details. Figure 2 The partition 42 has insulating ribs 44 at both ends facing the push plate 2. The partition 42, insulating ribs 44, and push plate 2 are all integrally formed structures. The presence of insulating ribs 44 extends the insulation distance between the two sets of main contacts, thereby enhancing safety and reliability. By increasing the insulation distance, current leakage or short circuits can be prevented more effectively. In addition, the integrally formed structure helps reduce assembly costs and improve production efficiency, while also enhancing the overall structural stability and durability of the contactor.

[0049] This utility model also proposes a high-voltage DC contactor, which includes a housing, a push rod assembly 100, and a moving contact assembly 200. The housing forms a receiving cavity, and a stationary contact and an auxiliary contact 300 are provided inside the housing. Part of the push rod 1 extends out of the housing. The push plate 2 and two retainers 3 are both provided in the receiving cavity. The moving contact assembly 200 includes an elastic element 210 and a moving contact piece 220. The elastic element 210 is provided in the push plate 2 and located in the retainer 3. A magnetic plate 230 is provided at the end of the elastic element 210 away from the push plate 2, and the moving contact piece 220 is provided in the magnetic plate 230. The specific structure of the push rod assembly 100 is as described in the above embodiments. Since this high-voltage DC contactor adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0050] For mounting the conductive piece 41, the push plate 2 has a bracket 43 on the side facing the auxiliary contact 300. For details, please refer to further documentation. Figure 5 The bracket 43 is located between the two elastic elements 210 and inside the insulating sleeve 5. The conductive piece 41 is located on the bracket 43. The bracket 43 can further shorten the distance between the conductive piece 41 and the auxiliary contact 300, thereby ensuring that the conductive piece 41 can abut against the auxiliary contact 300 during the upward movement of the push plate 2.

[0051] In one embodiment of this utility model, the push plate 2 is provided with a limiting ring groove 21 facing the retainer 3, and one end of the elastic element 210 is provided in the limiting ring groove 21. The elastic element 210 is generally a spring. The limiting ring groove 21 can play a good limiting installation effect on the spring and prevent the spring from being forced to bounce outwards.

[0052] In this utility model, the drive mechanism 400 can be a magnetic device, a cylinder, or other pneumatic, hydraulic, or other driving methods. This utility model does not limit this. In one embodiment, the drive mechanism 400 is a magnetic device, which includes an iron core. A coil is provided around the iron core. When the coil is energized, it generates a magnetic field that drives the iron core to move up and down, thereby moving the push rod 1 and driving the moving contact piece 220 to move towards and close with the stationary contact, thus connecting the circuit. When the coil is de-energized, the magnetic field disappears, and the moving contact piece 220 returns to its initial position under the action of the spring force, disconnecting from the stationary contact and cutting off the circuit. This driving method has a fast response speed, is simple to control, and the closing force of the contactor can be controlled by adjusting the coil current, ensuring a reliable electrical connection in a high-voltage DC system.

[0053] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A push rod assembly, characterized in that, It includes a push rod, a push plate, and two retainers. The push plate is disposed on the push rod, and an auxiliary contact assembly is provided on the side of the push plate facing away from the push rod. The two retainers are disposed on the push plate and are respectively located on both sides of the auxiliary contact assembly. The auxiliary contact assembly includes a conductive piece and a partition. The partition is used to separate the two retainers, and the conductive piece is disposed on the partition.

2. The push rod assembly as claimed in claim 1, characterized in that, The retainer and the push plate together enclose a receiving space, which is used to accommodate the moving contact assembly; The retainer and the push plate are respectively provided with two inner sidewalls with locking protrusions. The locking protrusions are located in the receiving space and are used to cooperate with the moving contact assembly for limiting.

3. The push rod assembly as described in claim 2, characterized in that, The retainer has a limiting boss on the side facing away from the auxiliary contact assembly. The limiting boss includes a first bent portion and a second bent portion connected to each other. Both the first bent portion and the second bent portion are integrally formed with the retainer.

4. The push rod assembly as described in any one of claims 1 to 3, characterized in that, One end of the push rod is provided with a spline shaft, and the spline shaft and the push plate are integrally formed with rubber coating.

5. The push rod assembly as described in any one of claims 1 to 3, characterized in that, The push rod has an external thread at the end away from the spline shaft, and the external thread is used to screw and fix it to the iron core; The push rod has a circumferential anti-rotation straight surface at one end near the external thread, which is used to prevent the push rod from rotating.

6. The push rod assembly as described in any one of claims 1 to 3, characterized in that, The auxiliary contact assembly also includes an insulating sleeve, which is fitted onto the partition portion, and a portion of the partition portion extends out of the push plate; The two ends of the partition are respectively provided with insulating ribs facing the push plate, and the partition, the insulating ribs and the push plate are all integrally formed structures.

7. The push rod assembly as claimed in claim 6, characterized in that, The partition also includes a bracket, which is located between the two retainers, and the conductive piece is disposed on the bracket.

8. A high-voltage DC contactor, characterized in that, include: The housing has a cavity, and a stationary contact and an auxiliary contact are provided inside the housing; The push rod assembly as described in any one of claims 1 to 7, wherein a portion of the push rod extends out of the housing, and the push plate and both retainers are disposed within the receiving cavity; as well as A moving contact assembly, comprising an elastic element and a moving contact piece, wherein the elastic element is disposed on the push plate and located within the retainer, and a magnetic plate is provided at one end of the elastic element away from the push plate, and the moving contact piece is disposed on the magnetic plate.

9. The high-voltage DC contactor as described in claim 8, characterized in that, The push plate has a limiting ring groove facing the retainer, and one end of the elastic element is located in the limiting ring groove.

10. The high-voltage DC contactor as described in claim 8, characterized in that, The high-voltage DC contactor also includes a drive mechanism, which is a magnetic device. The magnetic device includes a coil and an iron core. The coil is sleeved on the iron core, and the end of the push rod away from the moving contact piece is screwed to the iron core.

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