A precharged DC contactor and its usage method

Abstract

The present invention discloses a pre-charged DC contactor and a method for using the same, and relates to the technical field of contactors. The pre-charged DC contactor comprises: a base, on which a static contact piece is arranged; a magnetic circuit assembly, a core rod is arranged at the center of the magnetic circuit assembly, and the core rod penetrates the base; a main contact piece assembly, which is sleeved and arranged on the upper end of the core rod; an auxiliary contact piece assembly, which is sleeved and arranged on the upper end of the core rod, and a through cavity is arranged on the top surface of the auxiliary contact piece assembly; and an elastic piece, wherein the two ends of the elastic piece abut against the auxiliary contact piece assembly. The above-mentioned pre-charged DC contactor solves the technical problem that the existing contactor directly connects to the load, and the anti-melting contact material used increases the contact resistance after connecting the capacitive load for multiple times. The auxiliary contact piece assembly is first connected to the capacitive load to solve the influence of the capacitive load, and then the main contact piece assembly is contacted with the static contact piece to connect to the main circuit, so as not to affect the contact resistance of the main contact piece assembly after connecting to the main circuit, and to increase the stability of the contact resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of contactors, and particularly relates to a pre-charge DC contactor and a usage method thereof. Background Art

[0002] At present, in the DC market, when battery packs, frequency converters, energy storage, electric control, hydraulic power units, etc. are connected, due to the influence of the nature of the subsequent load, short-time large-current capacitive loads often occur.

[0003] The anti-fusing contact materials used in existing contactors have an increased contact resistance after multiple connections of capacitive loads, and abnormal heating is likely to occur. On the other hand, the existing technology uses a scheme of connecting a pre-charge resistor to solve the influence of such capacitive loads. This design requires timing design in the circuit, with a relatively high design cost, and the product of this scheme has a large volume and it is difficult to achieve miniaturization. Therefore, a pre-charge DC contactor and a usage method thereof for solving the above problems are proposed. Summary of the Invention

[0004] The purpose of the present invention is to provide a pre-charge DC contactor and a usage method thereof, which solve the technical problem that the existing contactor directly connects the load, and the anti-fusing contact material used has an increased contact resistance after multiple connections of capacitive loads, resulting in abnormal heating of the contactor.

[0005] To achieve the above purpose, the present invention provides a pre-charge DC contactor, including:

[0006] A base on which a static contact piece is provided;

[0007] A magnetic circuit assembly is arranged below the base, a core rod is provided at the center of the magnetic circuit assembly, and the core rod penetrates through the base;

[0008] A main contact piece assembly is sleeved on the upper end of the core rod;

[0009] A secondary contact piece assembly is sleeved on the upper end of the core rod, and the secondary contact assembly is located below the main contact piece assembly. A through cavity is provided on the top surface of the secondary contact piece assembly for passing through the main contact piece assembly;

[0010] An elastic piece is provided on the top surface of the main contact piece assembly, and both ends of the elastic piece abut against the secondary contact piece assembly.

[0011] Preferably, the secondary contact piece assembly includes: a secondary contact piece and first contacts provided on the bottom surfaces of both ends of the secondary contact piece; the primary contact piece assembly includes: a primary contact piece and second contacts provided on the bottom surfaces of both ends of the primary contact piece. The first contacts and the second contacts are both located directly above the static contact piece, and both the first contacts and the second contacts can abut against the static contact piece.

[0012] Preferably, a limiting member is sleeved and connected to the outer peripheral side surface of the core rod, and the top surface of the limiting member can abut against the bottom surface of the secondary contact piece assembly.

[0013] Preferably, two limiting frame groups are symmetrically arranged on the top surface of the base. Each limiting frame group includes two symmetrically arranged vertical rods. The inner side surfaces of the vertical rods abut against the outer side surface of the secondary contact piece. A limiting channel is provided between the two vertical rods, and both ends of the limiting member are located in the limiting channel.

[0014] Preferably, the elastic piece is integrally arc-shaped, and two support feet are respectively provided at both ends of the elastic piece, and the support feet abut against the top surface of the secondary contact piece assembly.

[0015] Preferably, two flanges are symmetrically arranged at the edge of the top surface of the secondary contact piece, and the flanges abut against both side surfaces of the elastic piece.

[0016] Preferably, a limiting groove is provided between the two support feet at the same end of the elastic piece, and the inner side surface of the limiting groove abuts against the side surface of the primary contact piece assembly.

[0017] Preferably, an elastic member is provided at the upper end of the core rod. The elastic member includes: an upper isolation washer and a lower isolation washer sleeved and arranged in sequence from top to bottom. A support spring is provided between the upper isolation washer and the lower isolation washer, and the bottom surface of the lower isolation washer abuts against the top surface of the elastic piece.

[0018] Preferably, annular limiting grooves are provided on the bottom surface of the upper isolation washer and the top surface of the lower isolation washer, and the annular limiting grooves are clamped and connected to the support spring.

[0019] Correspondingly, the technical solution of the present invention also provides a method for pre-charging a DC contactor, which is applied to the pre-charging DC contactor described in any one of the above, and includes:

[0020] Controlling the magnetic circuit assembly to drive the core rod to move downward relative to the base. The core rod drives the secondary contact piece assembly and the primary contact piece assembly to move downward synchronously until the secondary contact piece assembly contacts the static contact piece, and the secondary contact piece assembly connects the capacitive load;

[0021] Control the magnetic circuit component to drive the core rod to continue moving downward relative to the base. The secondary contact piece component remains in contact with the static contact piece. The core rod drives the primary contact piece component to continue moving downward. The primary contact piece component passes through the through cavity until the primary contact piece component contacts the static contact piece, and the contact is closed.

[0022] Compared with the above background technology, a pre-charged DC contactor provided by the present invention has the following beneficial effects:

[0023] (1) In the present invention, a primary contact piece component and a secondary contact piece component are arranged at the upper end of the core rod. First, the secondary contact piece component contacts the static contact piece to connect the capacitive load, and then the primary contact piece component contacts the static contact piece to connect to the main circuit, enabling the secondary contact piece component to connect the capacitive load first, solving the influence of the capacitive load, so as not to affect the contact resistance after the primary contact piece component is connected to the main circuit, increasing the stability of the contact resistance, and effectively preventing the contactor from abnormally heating. The usage method of the pre-charged DC contactor adopted in the present invention also has the above beneficial effects.

[0024] (2) In the present invention, both ends of the elastic piece abut against the secondary contact piece component, so that there is a certain height difference between the secondary contact piece component and the primary contact piece component in the longitudinal direction, and the secondary contact piece component can float up and down relative to the primary contact piece component, thereby realizing the control of the connection sequence of the primary contact piece component and the secondary contact piece component, effectively reducing the circuit design cost of the contactor and having better stability. On the other hand, through the through cavity provided on the top surface of the secondary contact piece component, the primary contact piece component can pass through the through cavity, so that the primary contact piece component and the secondary contact piece component have a certain overlapping height in the longitudinal height, to improve the space utilization rate of the overall contactor in the longitudinal height, reduce the overall volume of the contactor, and meet the miniaturization design requirements of the contactor. The usage method of the pre-charged DC contactor adopted in the present invention also has the above beneficial effects. Description of the Drawings

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0026] Figure 1 It is a three-dimensional structure diagram of the pre-charged DC contactor provided by the embodiment of the present invention;

[0027] Figure 2 It is a cross-sectional schematic diagram of the base and the magnetic circuit component provided by the embodiment of the present invention;

[0028] Figure 3 This is an exploded view of the precharged DC contactor after hiding the base and magnetic circuit assembly provided by the embodiments of the present invention.

[0029] Specifically, 1 - base; 101 - static contact piece; 2 - magnetic circuit assembly; 201 - return spring; 3 - core rod; 301 - annular limiting part; 4 - main contact piece assembly; 401 - main contact piece; 402 - second contact; 5 - auxiliary contact piece assembly; 501 - auxiliary contact piece; 502 - flanging; 503 - first contact; 504 - through cavity; 6 - elastic piece; 601 - support leg; 602 - limiting groove; 7 - limiting member; 701 - mating part; 702 - connecting part; 8 - limiting frame group; 9 - elastic member; 901 - upper isolation washer; 902 - lower isolation washer; 903 - support spring. Specific embodiments

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] In order to enable those skilled in the art of this technology to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0032] As Figure 1 、 Figure 2 and Figure 3 shown, to achieve the above object, the present invention provides a precharged DC contactor, including: a base 1 and a main contact piece assembly 4 and an auxiliary contact piece assembly 5 arranged on the base 1.

[0033] Among them, a static contact piece 101 is arranged on the base 1. Specifically, two notches are symmetrically arranged on the top surface of the base 1, and one static contact piece 101 is installed in each notch.

[0034] A magnetic circuit assembly 2 is arranged below the base 1. A core rod 3 is arranged at the central part of the magnetic circuit assembly 2. The core rod 3 penetrates through the base 1. Among them, the magnetic circuit assembly 2 is slidably connected to the core rod 3, and the magnetic circuit assembly 2 can provide electromagnetic suction to the core rod 3 to drive the core rod 3 to move downward relative to the base 1.

[0035] It should be noted that an annular limiting portion 301 is integrally provided in the middle of the core rod 3. The bottom surface of the annular limiting portion 301 is connected to the return spring 201, and the bottom end of the return spring 201 is connected to the magnetic circuit assembly 2. In the initial state, the electromagnetic suction force provided by the magnetic circuit assembly 2 is equal to the elastic force of the return spring 201. At this time, the core rod 3 remains stationary relative to the base 1. When the electromagnetic suction force provided by the magnetic circuit assembly 2 is less than the elastic force of the return spring 201, the core rod 3 moves upward relative to the base 1 under the pushing action of the return spring 201 until the electromagnetic suction force provided by the magnetic circuit assembly 2 is equal to the elastic force of the return spring 201. When the electromagnetic suction force provided by the magnetic circuit assembly 2 is greater than the elastic force of the return spring 201, the core rod 3 moves downward relative to the base 1 under the attraction of the electromagnetic suction force to overcome the force of the return spring 201 until the electromagnetic suction force provided by the magnetic circuit assembly 2 is equal to the elastic force of the return spring 201.

[0036] A secondary contact piece assembly 5 is slidably arranged below the primary contact piece assembly 4. A through cavity 504 is provided on the top surface of the secondary contact piece assembly 5 for passing through the primary contact piece assembly 4. By providing the through cavity 504 on the top surface of the secondary contact piece assembly 5, the primary contact piece assembly 4 and the secondary contact piece assembly 5 have a certain overlapping height in the longitudinal height, so as to improve the space utilization rate of the overall contactor in the longitudinal height, the integration degree of the contactor in the longitudinal direction is better, and at the same time, the increase in the lateral volume of the contactor caused by the increase in the number of contacts is avoided, thereby effectively controlling the overall volume of the contactor and meeting the requirements of the miniaturized design of the contactor.

[0037] Moreover, the horizontal projection plane of the through cavity 504 coincides with that of the primary contact piece assembly 4, and the inner side surface of the through cavity 504 can be slidably fitted with the circumferential side surface of the primary contact piece assembly 4. Thus, the through cavity 504 can be used to limit the primary contact piece assembly 4 to prevent the primary contact piece assembly 4 from rotating relative to the static contact piece 101, further improving the stability when the primary contact piece assembly 4 contacts the static contact piece 101, and then improving the stability after the primary contact piece assembly 4 is connected to the main circuit.

[0038] In addition, an elastic sheet 6 is provided on the top surface of the main contact piece assembly 4. The two end portions of the elastic sheet 6 abut against the secondary contact piece assembly 5. By abutting the two end portions of the elastic sheet 6 against the secondary contact piece assembly 5, it is ensured that the secondary contact piece assembly 5 can float up and down relative to the main contact piece assembly 4. When the secondary contact piece assembly 5 is not in contact with the static contact piece 101, the secondary contact piece assembly 5 is in a position state away from the main contact piece assembly 4, so as to ensure that the secondary contact piece assembly 5 first connects the capacitive load, and then the main contact piece assembly 4 contacts the static contact piece 101 to access the main circuit, so that the secondary contact piece assembly 5 first connects the capacitive load, solves the influence of the capacitive load, and does not affect the contact resistance after the main contact piece assembly 4 accesses the main circuit, increasing the stability of the contact resistance. When the secondary contact piece assembly 5 contacts the static contact piece 101 and the main contact piece assembly 4 gradually approaches the static contact piece 101, the secondary contact piece assembly 5 can always remain in contact with the static contact piece 101, thereby ensuring the stability when the secondary contact piece assembly 5 connects the capacitive load.

[0039] Furthermore, by abutting the two end portions of the elastic sheet 6 against the secondary contact piece assembly 5, there is a certain height difference between the main contact piece assembly 4 and the secondary contact piece assembly 5 in the longitudinal direction, and the secondary contact piece assembly 5 can float up and down relative to the main contact piece assembly 4, thereby realizing the on-time sequence control of the main contact piece assembly 4 and the secondary contact piece assembly 5, effectively reducing the circuit design cost of the contactor and having better stability.

[0040] During use, when the contact needs to be closed, the control magnetic circuit assembly 2 drives the core rod 3 to move downward relative to the base 1. The core rod 3 drives the secondary contact piece assembly 5 and the main contact piece assembly 4 to move downward synchronously until the secondary contact piece assembly 5 contacts the static contact piece 101, and the secondary contact piece assembly 5 connects the capacitive load; the control magnetic circuit assembly 2 drives the core rod 3 to continue to move downward relative to the base 1. The secondary contact piece assembly 5 remains in contact with the static contact piece 101, and the core rod 3 drives the main contact piece assembly 4 to continue to move downward. The main contact piece assembly 4 passes through the through cavity 504 until the main contact piece assembly 4 contacts the static contact piece 101, and the main contact piece assembly 4 accesses the main circuit, and the contact is closed.

[0041] It should be noted that in cases where the influence on the device when connecting the capacitive load is small and the duration is very short, such as battery packs, hydraulic power units, electronic controls, etc., the secondary contact piece assembly 5 is directly used to connect the capacitive load. In cases where the influence on the device when connecting the capacitive load is large and the duration is very long, such as frequency converters and energy storage devices, the method of connecting the capacitive load after connecting a resistor with a certain resistance value in series in the secondary contact piece assembly 5 can be adopted to control the pre-charge current and reduce the influence of the capacitive load on the device.

[0042] In one embodiment of the present invention, the secondary contact assembly includes: a secondary contact piece 501 and first contacts 503 provided on the bottom surfaces of both ends of the secondary contact piece 501. The primary contact assembly includes: a primary contact piece 401 and second contacts 402 provided on the bottom surfaces of both ends of the primary contact piece 401. The first contacts 503 and the second contacts 402 are both located directly above the static contact piece 101. The first contacts 503 abut against the static contact piece 101 to connect the secondary contact piece 501 to the capacitive load, and the second contacts 402 abut against the static contact piece 101 to connect the primary contact piece 401 to the main circuit. Even if the first contacts 503 are ablated by the capacitive load, it does not affect the contact between the second contacts 402 and the static contact piece 101. It should be noted that there is a certain height difference between the second contacts 402 and the first contacts 503 in the longitudinal direction.

[0043] In one embodiment of the present invention, a limiting member 7 is sleeved and connected to the outer peripheral side surface of the core rod 3. The top surface of the limiting member 7 can abut against the bottom surface of the secondary contact assembly. Specifically, the limiting member 7 is fixedly connected to the core rod 3 and is used to support the secondary contact piece assembly 5. When the core rod 3 is in an upper position relative to the base 1, the limiting member 7 can limit the secondary contact piece assembly 5 to move away from the static contact piece 101 to ensure the normal contact and disconnection between the first contacts 503 and the static contact piece 101.

[0044] In addition, two limiting frame groups 8 are symmetrically arranged on the top surface of the base 1. Each limiting frame group 8 includes two symmetrically arranged vertical rods. The inner side surfaces of the vertical rods abut against the outer side surfaces of the secondary contact piece 501 to limit the secondary contact piece 501 so that it cannot rotate relative to the core rod 3 with the axis of the core rod 3 as the axis, thereby ensuring that the first contacts 503 can be accurately docked with the static contact piece 101. A limiting channel is provided between the two vertical rods, and the limiting channel is kept in line with the axis direction of the core rod 3. The two end portions of the limiting member 7 are located in the limiting channel. During the process of the core rod 3 driving the limiting member 7 to move upward, it can limit the two end portions of the limiting member 7 to always be in the limiting channel, thereby preventing the limiting member 7 from rotating.

[0045] In one embodiment of the present invention, the limiting member 7 includes: a mating portion 701 and a connecting portion 702. The mating portion 701 is strip-shaped, and the two end portions of the mating portion 701 are located in the limiting channel. The connecting portion 702 is a bushing. A first through hole is provided on the top surface of the primary contact piece 401, a second through hole is provided on the top surface of the elastic piece 6, and a third through hole is provided on the top surface of the secondary contact piece 501. The bushing passes through the third through hole, the second through hole, and the first through hole in sequence from bottom to top to fix the primary contact piece, the secondary contact piece 501, and the elastic piece 6. It should be noted that the primary contact piece, the secondary contact piece 501, and the elastic piece 6 can move up and down relative to the bushing along the axis direction of the core rod 3.

[0046] In one embodiment of the present invention, the elastic sheet 6 is integrally arc-shaped, and the concave surface of the elastic sheet 6 faces the base 1. Specifically, the top surface of the middle part of the elastic sheet 6 is set as a plane, and the top surface of the elastic sheet 6 fits against the bottom surface of the main contact piece 401 to ensure that the elastic sheet 6 can be stably fixed to the bottom surface of the main contact piece 401. The two end portions of the elastic sheet 6 elastically abut against the sub-contact piece assembly 5. Among them, two legs 601 are symmetrically arranged at the two end portions of the elastic sheet 6, and the legs 601 extend towards the direction close to the sub-contact piece 501, and the legs 601 abut against the top surface of the sub-contact assembly. Preferably, the end of the leg 601 close to the sub-contact piece 501 is flanged to ensure that the leg 601 can stably hold the sub-contact piece assembly 5.

[0047] In one embodiment of the present invention, two folding edges 502 are symmetrically arranged at the edge of the top surface of the sub-contact piece 501. The folding edges 502 are integrally arranged with the sub-contact piece 501 and extend upwards from the sub-contact piece 501. The folding edges 502 abut against the two side surfaces of the elastic sheet 6, so that the elastic sheet 6 cannot rotate relative to the sub-contact piece 501, thereby improving the docking accuracy when the sub-contact piece 501 contacts the static contact piece 101.

[0048] In addition, a limiting groove 602 is arranged between the two legs 601 at the same end of the elastic sheet 6. The limiting groove 602 is integrally U-shaped, and the inner side surface of the limiting groove 602 abuts against the side surface of the main contact piece assembly 4. The main contact piece 401 can be limited through the limiting groove 602 to prevent the main contact piece 401 from rotating relative to the elastic sheet 6, so that the main contact piece 401, the elastic sheet 6 and the sub-contact piece 501 all remain relatively stationary on the horizontal projection plane relative to the static contact piece 101, thereby improving the docking accuracy when the main contact piece 401 contacts the static contact piece 101.

[0049] In one embodiment of the present invention, an elastic member 9 is arranged at the upper end of the core rod 3. The upper end of the core rod 3 is provided with an elastic member 9, and the main contact piece assembly 4 is sleeved on the upper end of the core rod 3. The main contact piece assembly 4 is located below the elastic member 9. It should be noted that the elastic member 9 itself has a certain elastic telescopic function to ensure that when the main contact piece assembly 4 contacts the static contact piece 101, the elastic member 9 can provide a certain elastic pressure to the main contact piece assembly 4, improving the stability when the main contact piece assembly 4 contacts the static contact piece 101.

[0050] Specifically, the elastic member 9 includes an upper isolation washer 901 and a lower isolation washer 902 sleeved on each other from top to bottom. A support spring 903 is arranged between the upper isolation washer 901 and the lower isolation washer 902. The bottom surface of the lower isolation washer 902 abuts against the top surface of the elastic sheet 6. Among them, the elastic member 9 as a whole serves as the first elastic part, mainly providing elastic pressure for the main contact piece assembly 4. The elastic sheet 6 serves as the second elastic part, mainly providing elastic pressure for the auxiliary contact piece assembly 5, ensuring that both the first contact 503 and the second contact 402 can stably contact the static contact piece 101, enabling the main contact piece assembly 4 to well connect the main circuit and the auxiliary contact piece assembly 5 to well connect the capacitive load.

[0051] In addition, annular limiting grooves 602 are arranged on the bottom surface of the upper isolation washer 901 and the top surface of the lower isolation washer 902. The support spring 903 is clamped and connected through the annular limiting grooves 602 to form stable limitation for the support spring 903, enabling the upper isolation washer 901, the lower isolation washer 902 and the support spring 903 to be stably connected and ensuring the overall stability of the elastic member 9.

[0052] The usage method of the pre-charged DC contactor adopted in the present invention specifically includes the following steps: In the initial state, neither the first contact 503 nor the second contact 402 contacts the static contact piece 101. When the contacts need to be closed, the control magnetic circuit assembly 2 drives the core rod 3 to move downward relative to the base 1. The core rod 3 drives the auxiliary contact piece 501 and the main contact piece 401 to move downward synchronously until the first contact 503 on the auxiliary contact piece 501 contacts the static contact piece 101, and the auxiliary contact piece assembly 5 connects the capacitive load to solve the influence of the capacitive load. The control magnetic circuit assembly 2 continues to drive the core rod 3 to move downward relative to the base 1. The first contact 503 on the auxiliary contact piece 501 remains in contact with the static contact piece 101, and the core rod 3 drives the main contact piece 401 to continue moving downward. The main contact piece 401 passes through the through cavity 504 until the second contact 402 on the main contact piece 401 contacts the static contact piece 101, and the main contact piece assembly 4 is connected to the main circuit.

[0053] In summary, first, the auxiliary contact piece assembly 5 contacts the static contact piece 101, and the auxiliary contact piece assembly 5 first connects the capacitive load to solve the influence of the capacitive load. Then, the main contact piece assembly 4 contacts the static contact piece 101 to be connected to the main circuit, so as not to affect the contact resistance after the main contact piece assembly 4 is connected to the main circuit, increase the stability of the contact resistance, and prevent the contactor from being prone to abnormal heating.

[0054] It should be noted that in this specification, relational terms such as first and second are only used to distinguish one entity from several other entities, and do not necessarily require or imply any actual relationship or order between these entities.

[0055] In this article, specific examples are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principles of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A pre-charged DC contactor, characterized in that: include: A base, on which a static contact piece is arranged; A magnetic circuit assembly is disposed below the base, a core rod is disposed at the center of the magnetic circuit assembly, and the core rod penetrates the base; A main contact piece assembly, sleeved and arranged on the upper end of the core rod; A secondary contact piece assembly is sleeved on the upper end of the core rod, and the secondary contact piece assembly is located below the primary contact piece assembly, and a through cavity is arranged on the top surface of the secondary contact piece assembly, and the through cavity is used to pass through the primary contact piece assembly; The elastic sheet is arranged on the top surface of the main contact sheet assembly, and the two ends of the elastic sheet abut against the auxiliary contact sheet assembly.

2. A pre-charged DC contactor according to claim 1, characterized in that: The auxiliary contact piece assembly includes: an auxiliary contact piece and a first contact point arranged on the bottom surface of both ends of the auxiliary contact piece, and the main contact piece assembly includes: a main contact piece and a second contact point arranged on the bottom surface of both ends of the main contact piece, the first contact point and the second contact point are both located directly above the static contact piece, and the first contact point and the second contact point can both abut against the static contact piece.

3. A pre-charged DC contactor according to claim 2, characterized in that: The outer peripheral side surface of the core rod is sleeve-connected with a limiting piece, and the top surface of the limiting piece can abut against the bottom surface of the auxiliary contact piece assembly.

4. A pre-charged DC contactor according to claim 3, characterized in that: Two limit frame groups are symmetrically arranged on the top surface of the base, each of the limit frame groups includes two symmetrically arranged vertical poles, the inner side surfaces of the vertical poles abut against the outer side surfaces of the auxiliary contact pieces, a limit channel is arranged between the two vertical poles, and the two end portions of the limit member are located in the limit channel.

5. A pre-charged DC contactor according to claim 2, characterized in that: The elastic sheet is in an arc shape as a whole, and two legs are respectively arranged at two ends of the elastic sheet, and the legs abut against the top surface of the auxiliary contact sheet assembly.

6. A pre-charged DC contactor according to claim 5, characterized in that: Two folded edges are symmetrically arranged at the edge of the top surface of the auxiliary contact piece, and the folded edges abut against two side surfaces of the elastic piece.

7. A pre-charged DC contactor according to claim 6, characterized in that: A limiting groove is arranged between the two supporting legs at the same end of the elastic sheet, and the inner side surface of the limiting groove abuts against the side surface of the main contact sheet assembly.

8. A pre-charged DC contactor according to any one of claims 1 to 7, characterized in that: An elastic component is arranged at the upper end of the core rod, and the elastic component comprises: an upper isolation washer and a lower isolation washer which are sequentially sleeved from top to bottom, a supporting spring is arranged between the upper isolation washer and the lower isolation washer, and the bottom surface of the lower isolation washer abuts against the top surface of the elastic sheet.

9. A pre-charged DC contactor according to claim 8, characterized in that: The bottom surface of the upper isolation gasket and the top surface of the lower isolation gasket are both provided with an annular limiting groove, and the annular limiting groove is clamped and connected to the supporting spring.

10. A method for using a pre-charged DC contactor, applied to the pre-charged DC contactor according to any one of claims 1 to 9, characterized in that: The method for using the pre-charged DC contactor includes: Controlling the magnetic circuit assembly to drive the core rod to move downward relative to the base, the core rod drives the auxiliary contact piece assembly and the main contact piece assembly to move downward synchronously until the auxiliary contact piece assembly contacts the static contact piece, and the auxiliary contact piece assembly connects the capacitive load; The magnetic circuit assembly is controlled to drive the core rod to continue to move downward relative to the base, the auxiliary contact piece assembly maintains contact with the static contact piece, and the core rod drives the main contact piece assembly to continue to move downward, and the main contact piece assembly passes through the through cavity until the main contact piece assembly contacts the static contact piece and the contact is closed.

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