A DC contactor

Abstract

A DC contactor includes an insulating base and a ceramic cover. A coil frame is housed within the insulating base, and a coil is wound around the coil frame. A movable iron core is located in the center of the coil frame, and a push rod is mounted on the movable iron core. The push rod passes through a through hole and extends to above an end cover. A stationary contact assembly is embedded in the ceramic cover. An insulating ring seat is mounted on the top of the push rod. A connecting post is fixedly embedded on the upper surface of the insulating ring seat. An outer cylinder is located above the connecting post, and a sliding sleeve is fitted onto the outer surface of the outer cylinder. A moving contact is located on the outer side of the sliding sleeve, and an annular step is formed on the outer side of the sliding sleeve. The moving contact is fixedly mounted on the annular step and has a disc-shaped structure. The upper surface of the moving contact contacts and engages with the stationary contact assembly. A return spring is located between the lower surface of the sliding sleeve and the upper surface of the insulating ring seat. This invention overcomes the shortcomings of the prior art, enabling the moving contact to rotate slightly when energized, achieving self-adjustment of the contact surface and uniform wear, greatly improving electrical life and contact reliability.

Description

Technical Field

[0001] This utility model relates to the field of contactor technology, specifically to a DC contactor. Background Technology

[0002] A DC contactor generally consists of an iron core, coil, armature, and contact springs. Existing DC contactors typically include an insulating base, ceramic cover, electromagnetic system (including coil, iron core, and push rod), and contact system (including stationary and moving contacts). Its working principle is as follows: when the coil is energized, it generates a magnetic field, driving the moving iron core and push rod to move linearly, pushing the moving contact to contact the stationary contact, thus completing the circuit. When the coil is de-energized, the force of the return spring separates the moving contact from the stationary contact, thus breaking the circuit.

[0003] However, in practical applications, especially in high-current, high-voltage DC environments, the existing contactor structure has revealed the following technical defects:

[0004] 1. Contact Erosion and Poor Contact Issues: The lack of a zero-crossing point for the direct current makes it difficult to extinguish the arc, resulting in a strong arc during breaking, severely eroding the contact surface. Simultaneously, repeated collisions between the moving and stationary contacts during closing cause mechanical wear. Most existing moving contacts are fixedly installed, and their contact surface with the stationary contact remains essentially unchanged with each closure. After prolonged operation, the contact surface is prone to developing uneven pits or oxide layers due to arc erosion and mechanical wear, leading to a reduced effective contact area, increased contact resistance, and localized overheating. This further exacerbates oxidation and erosion, creating a vicious cycle that ultimately leads to contact failure, severely impacting the contactor's electrical life and operational reliability.

[0005] 2. Complexity of structure and assembly: In order to ensure reliable connection and limiting of the moving contact, some existing structures use threaded fastening or multi-part crimping, which makes the assembly process cumbersome, resulting in low production efficiency and the risk of loosening under long-term vibration environment, and making maintenance and replacement inconvenient. Utility Model Content

[0006] To address the shortcomings of existing technologies, this utility model provides a DC contactor that overcomes these deficiencies. Its reasonable design allows the moving contact to rotate slightly when energized, enabling self-adjustment and uniform wear of the contact surface, thus greatly improving electrical life and contact reliability.

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A DC contactor includes an insulating base and a ceramic cover. A coil frame is fixedly installed inside the insulating base, and a coil is wound on the coil frame. A movable iron core is located in the middle of the coil frame, and a push rod is fixedly installed in the middle of the movable iron core. An end cover is fixedly installed on the upper surface of the insulating base. The end cover has a through hole in the middle, and the push rod passes through the through hole and extends above the end cover. The bottom of the ceramic cover is fixedly connected to the upper surface of the end cover via a sealing ring. A stationary contact assembly is fixedly embedded in the upper surface of the ceramic cover.

[0009] An insulating ring seat is fixedly installed on the top of the push rod. A connecting post is fixedly embedded on the upper surface of the insulating ring seat. An outer cylinder is integrally provided above the connecting post. A sliding sleeve is sleeved on the outer surface of the outer cylinder. A moving contact is provided on the outer side of the sliding sleeve. An annular step is opened on the outer side of the sliding sleeve. The moving contact is fixedly installed on the annular step. The moving contact has a disc-shaped structure. The upper surface of the moving contact is in contact with the stationary contact assembly. A return spring is provided between the lower surface of the sliding sleeve and the upper surface of the insulating ring seat.

[0010] Preferably, a hollow locking post is provided on the upper surface of the outer cylinder, and a pressure plate is sleeved on the outer side of the hollow locking post. The lower surface of the pressure plate is in contact with the upper surface of the moving contact. A locking piece extends outward from the hollow locking post, and the locking piece abuts against the upper surface of the pressure plate.

[0011] Preferably, the insulating ring seat includes a circular seat body, an annular boss is provided on the outer edge of the upper surface of the circular seat body, an annular groove is provided in the annular boss, and the lower end of the return spring is installed in the annular groove; a supporting cylinder is provided in the middle of the upper surface of the circular seat body, the diameter of the supporting cylinder is the same as the diameter of the outer cylinder, and the supporting cylinder and the outer cylinder are coaxially arranged, the sliding sleeve is slidably sleeved on the outside of the supporting cylinder and the outer cylinder, and the connecting column is fixedly embedded in the inside of the supporting cylinder.

[0012] Preferably, a guide sleeve is embedded in the through hole, and the inner wall of the guide sleeve slides in fit with the outer surface of the push rod.

[0013] Preferably, an annular limiting step is provided above the through hole, and an outwardly turned annular flange is provided on the upper end face of the guide sleeve, the annular flange being engaged within the annular limiting step.

[0014] Preferably, an auxiliary contact piece is fixedly embedded on the side of the insulating ring seat, and an auxiliary stationary contact is fixedly embedded on the ceramic cover, wherein the auxiliary contact piece and the auxiliary stationary contact are in active contact.

[0015] Preferably, the inner wall of the ceramic cover is provided with an arc-shaped partition, and an auxiliary contact cavity is formed between the arc-shaped partition and the inner wall of the ceramic cover. The lower end of the auxiliary stationary contact passes through the upper surface of the ceramic cover and extends into the auxiliary contact cavity. A clearance notch is opened in the middle of the arc-shaped partition, and the clearance notch corresponds to the movement trajectory of the push rod. The auxiliary contact piece moves up and down along the clearance notch.

[0016] This invention provides a DC contactor with the following advantages: By allowing the moving contact to self-rotate slightly under electromagnetic force, the contact point or contact area between the moving and stationary contact assemblies is slightly different each time the contact is closed. This completely changes the traditional fixed-position contact working mode of contactors. It allows the entire upper surface of the moving contact to be used alternately and wear evenly during long-term operation, resulting in a more uniform contact pressure distribution and further reducing contact resistance and temperature rise. This effectively avoids long-term exposure of the fixed area to arc erosion and mechanical impact. It effectively prevents problems such as increased contact resistance and overheating welding caused by severe localized erosion or oxidation, thus significantly improving the electrical life and switching reliability of the main contacts, especially suitable for DC applications with frequent operation and high loads. By setting an insulating ring seat, the electrical connection between the moving contact and other metal transmission components such as the push rod is effectively isolated, preventing current from flowing along abnormal paths. This effectively isolates the moving contact from direct contact with other metal components, fundamentally eliminating the risk of short circuits or leakage due to insulation failure, and significantly improving the electrical safety performance of the product. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this utility model or the prior art, the accompanying drawings used in the description of this utility model or the prior art will be briefly introduced below.

[0018] Figure 1 A schematic diagram of the structure of this utility model;

[0019] Figure 2 A schematic diagram of the cross-sectional structure of this utility model;

[0020] Figure 3 A schematic diagram of the cross-sectional structure of the insulating ring seat, moving contact, guide sleeve and push rod in this utility model;

[0021] Figure 4 A schematic diagram of the connection structure of the insulating ring seat, the moving contact and the push rod in this utility model;

[0022] Figure 5 Schematic diagram of the cross-sectional structure of the guide sleeve and end cap in this utility model;

[0023] Figure 6 A schematic diagram of the structure of the ceramic cover in this utility model;

[0024] Explanation of the labels in the diagram:

[0025] 1. Insulating base; 2. Ceramic cover; 3. Coil frame; 4. Coil; 5. Movable iron core; 6. Push rod; 7. End cap; 8. Through hole; 9. Sealing ring; 10. Stationary contact assembly; 11. Insulating ring seat; 12. Connecting post; 13. Outer cylinder; 14. Sliding sleeve; 15. Moving contact; 16. Annular step; 17. Return spring; 18. Hollow locking post; 19. Pressure plate; 21. Annular limiting step; 22. Annular flange; 23. Auxiliary contact piece; 24. Auxiliary stationary contact; 25. Arc-shaped partition; 26. Relief notch; 27. Guide sleeve; 111. Circular seat; 112. Annular boss; 113. Annular groove; 114. Support cylinder. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0027] Example 1, as Figure 1-6 As shown, a DC contactor includes an insulating base 1 and a ceramic cover 2. A coil frame 3 is fixedly installed inside the insulating base 1, and a coil 4 is wound on the coil frame 3. A movable iron core 5 is provided in the middle of the coil frame 3, and a push rod 6 is fixedly installed in the middle of the movable iron core 5. An end cover 7 is fixedly installed on the upper surface of the insulating base 1. A through hole 8 is provided in the middle of the end cover 7. The push rod 6 passes through the through hole 8 and extends above the end cover 7. The bottom of the ceramic cover 2 is fixedly connected to the upper surface of the end cover 7 through a sealing ring 9. A stationary contact assembly 10 is fixedly embedded in the upper surface of the ceramic cover 2.

[0028] An insulating ring seat 11 is fixedly installed on the top of the push rod 6. A connecting post 12 is fixedly embedded on the upper surface of the insulating ring seat 11. An outer cylinder 13 is integrally provided above the connecting post 12. A sliding sleeve 14 is sleeved on the outer surface of the outer cylinder 13. A moving contact 15 is provided on the outer side of the sliding sleeve 14. An annular step 16 is opened on the outer side of the sliding sleeve 14. The moving contact 15 is fixedly installed on the annular step 16. The moving contact 15 has a disc-shaped structure. The upper surface of the moving contact 15 is in contact with the stationary contact assembly 10. A return spring 17 is provided between the lower surface of the sliding sleeve 14 and the upper surface of the insulating ring seat 11.

[0029] Working principle:

[0030] When coil 4 is energized, it generates an excitation magnetic field. This magnetic field magnetizes the movable iron core 5, which, under the influence of electromagnetic attraction, overcomes the preload of the return spring 17, causing the push rod 6 to move upward in a straight line. The upward movement of the push rod 6 is transmitted to the entire moving contact assembly through the insulating ring seat 11 and connecting post 12 at its top. The upward movement of the moving contact assembly eventually brings the upper surface of the moving contact 15 into contact with the stationary contact assembly 10 fixed inside the ceramic cover 2, thus opening the main circuit.

[0031] Under the influence of electromagnetic attraction, the moving contact 15 collides and is pressed against the stationary contact assembly 10. Since the moving contact 15 is fitted onto the outer cylinder 13 via a sliding sleeve 14 below it, the two are not rigidly fixed but have a relative rotatable clearance. Therefore, during contact, due to manufacturing tolerances, assembly errors, and slight deformation or wear after long-term use, there will inevitably be a very small angle between the plane of the moving contact 15 and the plane of the stationary contact assembly 10. Thus, when these two planes contact at this small angle, they do not fully contact simultaneously, but one side contacts first. The side that contacts first is initially subjected to the reaction force (N) of the stationary contact, and the point of application of this force is off-center from the central axis of the moving contact system. A force (N) off-center directly generates a torque (M) that causes the object to rotate. Due to the relative rotatable clearance between the moving contact 15 and the outer cylinder 13, this torque (M) causes the moving contact 15 to rotate slightly around the outer cylinder 13, thereby adjusting the orientation of its contact surface. Furthermore, when the moving contact 15 rapidly approaches the stationary contact assembly 10, it is situated within a changing magnetic field (coil magnetic field and arc magnetic field). According to Faraday's law of electromagnetic induction, this changing magnetic field induces eddy currents within the moving contact. These eddy currents, themselves situated within the magnetic field, are subject to the Lorentz force. The distribution of the entire eddy current field is highly complex, but the resultant force is unlikely to be a force passing precisely through the center of the circle. This electromagnetic force, not passing through the center, also contributes an additional rotational torque. Therefore, under the combined action of electromagnetic attraction and eddy current effect, the moving contact 15 is not only subjected to an attractive force along the central axis but also superimposed with a torque that causes it to rotate around the outer cylinder 13. Due to the fit clearance between the sliding sleeve 14 and the outer cylinder 13, the moving contact 15 undergoes a slight rotation around the axis of the outer cylinder 13 under the influence of this torque.

[0032] Therefore, the moving contact 15 can undergo adaptive, minute self-rotation under electromagnetic force, making the contact point or contact area between the moving contact 15 and the stationary contact assembly 10 slightly different each time it closes. This completely changes the traditional fixed-position contact working mode of contactors. It allows the entire upper surface of the moving contact 15 to be used alternately and wear evenly during long-term operation, resulting in a more uniform contact pressure distribution and further reducing contact resistance and temperature rise. This effectively avoids the fixed area from being subjected to long-term arc erosion and mechanical impact. Thus, it effectively prevents problems such as increased contact resistance and overheating welding caused by severe localized ablation or oxidation, significantly improving the electrical life and switching reliability of the main contacts, making it particularly suitable for DC applications with frequent operation and high loads.

[0033] When coil 4 is de-energized, the excitation magnetic field disappears rapidly, and the electromagnetic attraction force on the movable iron core 5 also disappears. At this time, the compressed return spring 17 releases its stored elastic potential energy, and its restoring force acts downward on the sliding sleeve 14 and the insulating ring seat 11, pushing the entire moving contact assembly, as well as the movable iron core 5 and the push rod 6, to move rapidly downward, causing the moving contact 15 to quickly separate from the stationary contact assembly 10, forcibly extinguishing the arc, and the main circuit is broken.

[0034] In addition, in this embodiment, by setting an insulating ring seat 11, the electrical connection between the push rod 6 and other metal transmission components and the moving contact 15 is effectively isolated, preventing current from flowing in abnormal paths. This effectively isolates the moving contact 15 from direct contact with other metal components, fundamentally eliminating the risk of short circuit or leakage due to insulation failure, and greatly improving the electrical safety performance of the product.

[0035] In Example 2, as a further preferred embodiment of Example 1, a hollow locking post 18 is provided on the upper surface of the outer cylinder 13. A pressure plate 19 is sleeved on the outer side of the hollow locking post 18, and the lower surface of the pressure plate 19 contacts the upper surface of the moving contact 15. A locking piece extends outward from the hollow locking post 18, and the locking piece abuts against the upper surface of the pressure plate 19. Through the cooperation of the hollow locking post 18 and its locking piece with the pressure plate 19, a highly efficient anti-movement limiting structure is formed. During assembly, the components are simply inserted sequentially, and then the hollow locking post 18 is pushed outward so that the locking piece naturally flips outward to complete the fixation. This process does not require thread tightening, riveting, or special tools, simplifying the assembly process, reducing the difficulty of operation and dependence on worker skills, and improving production efficiency. The locking plate and the upper surface of the pressure plate 19 form a limiting fit, which effectively ensures that the sliding sleeve 14 and the moving contact 15 will not fall off the outer cylinder 13 when subjected to vibration and impact, while not excessively restricting their degree of freedom of micro-rotation, thus achieving the functional requirements while ensuring structural reliability.

[0036] In embodiment three, as a further preferred embodiment one, the insulating ring seat 11 includes a circular seat body 111. An annular boss 112 is provided on the outer edge of the upper surface of the circular seat body 111, and an annular groove 113 is provided within the annular boss 112. The lower end of the return spring 17 is installed within the annular groove 113. A supporting cylinder 114 is provided in the middle of the upper surface of the circular seat body 111. The diameter of the supporting cylinder 114 is the same as the diameter of the outer cylinder 13, and the supporting cylinder 114 and the outer cylinder 13 are coaxially arranged. A sliding sleeve 14 is slidably sleeved on the outside of the supporting cylinder 114 and the outer cylinder 13. A connecting post 12 is fixedly embedded inside the supporting cylinder 114. By providing the annular groove 113 at a position corresponding to the lower end of the return spring 17, a physically enclosed limiting space is provided for the return spring 17. This effectively ensures that the lower end of the return spring 17 is precisely limited within the annular groove 113, so that the return spring 17 maintains a vertical posture throughout the entire compression and release process. This ensures that the generated restoring force always acts along the axial direction of the push rod 6, avoiding problems such as friction, jamming, or incomplete reset caused by the component force generated by the spring tilt. This guarantees that the moving contact 15 can quickly, accurately, and forcefully return to the initial breaking position, improving the contactor's operational reliability and mechanical life. By setting the support cylinder 114 and the outer cylinder 13 as a coaxial structure, the sliding sleeve 14 is guided by the support cylinder 114 in the initial stage of the moving contact assembly's movement; at the end of the movement, it smoothly transitions to being guided by the outer cylinder 13. This seamless long-stroke guidance effectively prevents the sliding sleeve 14 from tilting, shaking, or jamming during movement due to excessive cantilever length. This effectively ensures that the moving contact 15 can approach the stationary contact assembly 10 with extremely high alignment, ensuring uniform pressure distribution during contact and significantly improving contact stability and conductivity. Meanwhile, since the coaxiality of the supporting cylinder 114 and the outer cylinder 13 can be guaranteed during the parts processing, during assembly, as long as the sliding sleeve 14 is fitted in, its coaxiality with the upper and lower guide parts is naturally guaranteed, without the need for additional cumbersome adjustments, thus improving production efficiency and product consistency.

[0037] In Embodiment Four, as a further preferred embodiment of Embodiment One, a guide sleeve 27 is embedded within the through hole 8, with the inner wall of the guide sleeve 27 slidingly engaging with the outer surface of the push rod 6. By engaging the push rod 6 with the guide sleeve 21 within the through hole 8, and by having the supporting cylinder 113 and the outer cylinder 13 jointly guide the sliding sleeve 14, precise dual guidance is provided for the entire transmission system. This significantly reduces the risk of swaying and jamming of moving parts during operation, ensuring that the movement trajectory of the moving contact 15 remains perpendicular to the stationary contact assembly 10, guaranteeing the accuracy and consistency of the breaking and closing actions. Furthermore, the guide sleeve 21 can be independently manufactured using materials with excellent wear resistance and self-lubricating properties (such as powder metallurgy copper-based alloys, engineering plastics POM, or PTFE). This effectively reduces the coefficient of friction between the push rod 6 and the guide sleeve 21, thereby significantly reducing wear and extending service life. Meanwhile, the high-precision sliding fit between the guide sleeve 21 and the push rod 6 provides precise radial constraint and guidance for the up and down movement of the push rod 6, effectively preventing radial swaying or tilting of the push rod during movement; thus further ensuring that the push rod 6 can maintain stable axial movement during high-speed operation.

[0038] In Example 5, as a further preferred embodiment of Example 4, an annular limiting step 21 is provided above the through hole 8, and an outwardly turned annular flange 22 is provided on the upper end face of the guide sleeve 27. The annular flange 22 is engaged within the annular limiting step 21. Through the cooperation of the annular flange 22 and the annular limiting step 21, an axial mechanical interlocking structure is formed, which effectively prevents the guide sleeve 27 from loosening or shifting in the vertical direction under the repeated up-and-down movement impact and vibration environment of the push rod 6. This ensures that the guide sleeve 27 will not loosen due to vibration throughout the entire product life cycle, greatly improving the reliability of the product in harsh environments.

[0039] In Example Six, as a further preferred embodiment of Example Four, an auxiliary contact piece 23 is fixedly embedded in the side of the insulating ring seat 11, and an auxiliary stationary contact 24 is fixedly embedded in the ceramic cover 2. The auxiliary contact piece 23 and the auxiliary stationary contact 24 cooperate and make contact. By fixing the auxiliary contact piece 23 to the insulating ring seat 11, the auxiliary contact piece 23 and the auxiliary stationary contact 24 simultaneously complete the corresponding opening or closing action when the main contact opens or closes, thereby realizing the linkage control of the main and auxiliary contacts. Furthermore, by directly setting the auxiliary contact piece 23 on the side of the insulating ring seat 11, the longitudinal space traversed by the movement of the insulating ring seat 11 itself is fully utilized without occupying additional lateral or longitudinal space, making the product structure more compact.

[0040] In addition, in this embodiment, an arc-shaped partition 25 is provided on the inner wall of the ceramic cover 2. An auxiliary contact cavity is formed between the arc-shaped partition 25 and the inner wall of the ceramic cover 2. The lower end of the auxiliary stationary contact 24 passes through the upper surface of the ceramic cover 2 and extends into the auxiliary contact cavity. A clearance notch 26 is opened in the middle of the arc-shaped partition 25. The clearance notch 26 corresponds to the movement trajectory of the push rod 6. The auxiliary contact piece 23 moves up and down along the clearance notch 26. The auxiliary contact cavity formed by the arc-shaped partition 25 and the inner wall of the ceramic cover 2 establishes a physical barrier between the main circuit and the auxiliary circuit, thereby protecting the movement areas of the auxiliary stationary contact 24 and the auxiliary contact piece 23 in a relatively independent and sealed space. This effectively prevents the metal vapor, arc plasma and carbonized contaminants generated by the main contact 15 when interrupting a large current from entering the auxiliary contact cavity. This fundamentally avoids the problems of increased contact resistance, unstable signal or even complete failure of the auxiliary contact due to surface contamination, ensuring the long-term accuracy and extremely high reliability of the status feedback signal. Furthermore, a clearance notch 26 is created in the middle of the arc-shaped partition 25, providing a guide channel that perfectly corresponds to the movement trajectory of the push rod 6. This ensures that the auxiliary contact piece 23, fixed to the side of the insulating ring seat 11, can move smoothly up and down along a predetermined path without obstruction, completing the connection and disconnection with the auxiliary stationary contact 24. Additionally, as part of the insulating ceramic material, the smooth arc-shaped surface of the arc-shaped partition 25 effectively divides and improves the electric field distribution within the cavity, avoiding electric field concentration points. This arc-shaped partition 25 structure increases the creepage distance between the main circuit and the auxiliary circuit, preventing surface flashover that may occur under high voltage, further enhancing the electrical insulation strength and the product's withstand voltage capability.

[0041] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A DC contactor, comprising an insulating base (1) and a ceramic cover (2), wherein a coil frame (3) is fixedly installed inside the insulating base (1), a coil (4) is wound on the coil frame (3), a movable iron core (5) is provided in the middle of the coil frame (3), a push rod (6) is fixedly installed in the middle of the movable iron core (5), an end cover (7) is fixedly installed on the upper surface of the insulating base (1), a through hole (8) is provided in the middle of the end cover (7), the push rod (6) passes through the through hole (8) and extends to the top of the end cover (7), the bottom of the ceramic cover (2) is fixedly connected to the upper surface of the end cover (7) through a sealing ring (9), and a stationary contact assembly (10) is fixedly embedded in the upper surface of the ceramic cover (2). Its features are: An insulating ring seat (11) is fixedly installed on the top of the push rod (6). A connecting post (12) is fixedly embedded on the upper surface of the insulating ring seat (11). An outer cylinder (13) is integrally provided above the connecting post (12). A sliding sleeve (14) is sleeved on the outer surface of the outer cylinder (13). A moving contact (15) is provided on the outer side of the sliding sleeve (14). An annular step (16) is opened on the outer side of the sliding sleeve (14). The moving contact (15) is fixedly installed on the annular step (16). The moving contact (15) has a disc-shaped structure. The upper surface of the moving contact (15) is in contact with the stationary contact assembly (10). A return spring (17) is provided between the lower surface of the sliding sleeve (14) and the upper surface of the insulating ring seat (11).

2. A DC contactor according to claim 1, characterized in that: A hollow locking post (18) is provided on the upper surface of the outer cylinder (13). A pressure plate (19) is sleeved on the outer side of the hollow locking post (18). The lower surface of the pressure plate (19) is in contact with the upper surface of the moving contact (15). A locking piece extends outward from the hollow locking post (18) and abuts against the upper surface of the pressure plate (19).

3. A DC contactor according to claim 1, characterized in that: The insulating ring seat (11) includes a circular seat body (111), an annular boss (112) is provided on the outer edge of the upper surface of the circular seat body (111), an annular groove (113) is provided in the annular boss (112), and the lower end of the reset spring (17) is installed in the annular groove (113); a supporting cylinder (114) is provided in the middle of the upper surface of the circular seat body (111), the diameter of the supporting cylinder (114) is the same as the diameter of the outer cylinder (13), and the supporting cylinder (114) and the outer cylinder (13) are coaxially arranged, the sliding sleeve (14) is slidably sleeved on the outside of the supporting cylinder (114) and the outer cylinder (13), and the connecting column (12) is fixedly embedded in the supporting cylinder (114).

4. A DC contactor according to claim 1, characterized in that: The through hole (8) is fitted with a guide sleeve (27), and the inner wall of the guide sleeve (27) slides with the outer surface of the push rod (6).

5. A DC contactor according to claim 4, characterized in that: An annular limiting step (21) is provided above the through hole (8), and an outwardly turned annular flange (22) is provided on the upper end face of the guide sleeve (27). The annular flange (22) is engaged in the annular limiting step (21).

6. A DC contactor according to claim 1, characterized in that: An auxiliary contact piece (23) is fixedly embedded on the side of the insulating ring seat (11), and an auxiliary stationary contact (24) is fixedly embedded on the ceramic cover (2). The auxiliary contact piece (23) and the auxiliary stationary contact (24) cooperate to make contact.

7. A DC contactor according to claim 6, characterized in that: The inner wall of the ceramic cover (2) is provided with an arc-shaped partition (25). An auxiliary contact cavity is formed between the arc-shaped partition (25) and the inner wall of the ceramic cover (2). The lower end of the auxiliary stationary contact (24) passes through the upper surface of the ceramic cover (2) and extends into the auxiliary contact cavity. A clearance notch (26) is opened in the middle of the arc-shaped partition (25). The clearance notch (26) corresponds to the movement trajectory of the push rod (6). The auxiliary contact piece (23) moves up and down along the clearance notch (26).

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