Plug assembly and joint thereof

Abstract

The present application belongs to the field of plug, especially a plug assembly and a connector, the connector comprising a connector body with a contact surface, the contact surface being covered with a soft conductive matrix layer, the Vickers hardness of the soft conductive matrix layer being 8-25HV; hard ceramic particles are embedded on the surface of the soft conductive matrix layer, the particle size of the hard ceramic particles being 5-15μm, the top of the hard ceramic particles protruding from the surface of the soft conductive matrix layer, the protruding height being less than 8μm. By covering the contact surface with a soft conductive matrix layer and setting part of the hard ceramic particles protruding from the surface of the soft conductive matrix layer, the hard ceramic particles can break the oxide layer (mainly copper oxide) on the contact surface of the socket during the process of plugging and unplugging the plug, thereby actively causing the oxide layer to break and exposing the fresh copper matrix, so that the soft conductive matrix layer can directly contact with the copper matrix, thereby establishing a low-resistance and high-stable conductive path, avoiding the problem of continuously increasing contact resistance caused by the oxide layer.

Description

Technical Field

[0001] This invention belongs to the field of plugs, and in particular a plug assembly and its connector. Background Technology

[0002] The conductive substrate of existing DC power plugs and sockets is mostly made of copper. To improve conductivity and corrosion and oxidation resistance, a protective plating layer is usually electroplated on the surface of the copper substrate. The conventional plating structure is a nickel underlayer combined with a tin, silver or gold conductive surface layer.

[0003] With repeated plugging and unplugging, and wear from vibration, a brittle insulating oxide film, such as copper oxide, gradually forms at the contact interface between the plug and socket. This leads to increased contact resistance and heat generation. The high temperature further promotes the oxidation of the copper substrate, creating a vicious cycle. Once oxidation occurs, long-term use can easily lead to faults such as overheating of contacts, ablation, melting of the plastic casing, and even short circuits and fires, seriously affecting the power supply stability and safety of high-current equipment.

[0004] Traditional plating is a passive protective structure that delays the oxidation of the metal substrate by isolating it from air, but cannot actively remove the oxide film, sulfide film and other insulating media that have been generated on the socket contact surface. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a plug assembly and its connector that can actively break the oxide film on the socket contact surface during plugging and unplugging, so that the plug connector can directly contact the copper substrate, avoid the rapid increase of contact resistance, and maintain the stability of contact resistance.

[0006] To solve the above problems, the technical solution adopted by the present invention is: a connector, comprising a connector body having a contact surface. The contact surface is covered with a soft conductive substrate layer, and the Vickers hardness of the soft conductive substrate layer is 8-25HV; Hard ceramic particles are embedded in the surface of the soft conductive substrate layer. The particle size of the hard ceramic particles is 5–15 μm, and the top of the hard ceramic particles protrudes from the surface of the soft conductive substrate layer with a protrusion height of less than 8 μm.

[0007] Furthermore, the Vickers hardness of the soft conductive substrate layer is 15-25 HV.

[0008] Furthermore, the soft conductive substrate layer is a tin-nickel alloy layer, with nickel accounting for 3-5% of the volume.

[0009] Furthermore, the outer wall of the soft conductive substrate layer is provided with multiple annular collection grooves, the width of which is 10-20μm and the depth is 5-15μm.

[0010] Furthermore, the Vickers hardness of the soft conductive substrate layer is 8-15 HV; a shape memory alloy ring is disposed between the soft conductive substrate layer and the contact surface, the shape memory alloy ring having a phase transition temperature of 40-60℃ and a radial expansion of 0.05-0.15mm.

[0011] Furthermore, the soft conductive substrate layer is a pure tin layer.

[0012] Furthermore, the hard ceramic particles are Al2O3.

[0013] A plug assembly includes an insulating housing, within which are disposed a positive terminal and a negative terminal with contact surfaces, wherein the positive terminal is connected to a positive wire and the negative terminal is connected to a negative wire; The contact surfaces of the positive and negative terminals are covered with a soft conductive substrate layer, the Vickers hardness of which is 8-25 HV. Hard ceramic particles are embedded in the surface of the soft conductive substrate layer. The particle size of the hard ceramic particles is 5–15 μm, and the top of the hard ceramic particles protrudes from the surface of the soft conductive substrate layer with a protrusion height of less than 8 μm.

[0014] Furthermore, an insulating positioning sleeve is provided inside the insulating shell. The front end of the insulating positioning sleeve is provided with a first positioning hole, and the rear end is provided with a second positioning hole. The first positioning hole and the second positioning hole are connected, and the diameter of the second positioning hole is larger than the diameter of the first positioning hole. The positive terminal connector includes a connecting section, a limiting boss, and a positioning section arranged sequentially from the front end to the rear end. The connecting section passes through a first positioning hole and slides in engagement with it. The limiting boss and the positioning section are located within a second positioning hole and slide in engagement with it. A limiting block that slides in engagement with the second positioning hole is provided within the second positioning hole. A connecting sleeve is provided on the side of the limiting block facing the positive terminal connector. The end of the positioning section extends into the connecting sleeve and slides in engagement with it. A spring is provided between the limiting block and the limiting boss. The spring is in a compressed state, causing the limiting boss to fit against the bottom of the second positioning hole, and there is a gap between the positioning section and the limiting block. A pre-tightening insulating block that threads into the second positioning hole is provided at the opening of the second positioning hole. A connector is provided on the limiting block, and the connector passes through the pre-tightening insulating block and is connected to the positive terminal wire.

[0015] Furthermore, the gap between the positioning section and the limiting block is 0.4-0.6mm.

[0016] The beneficial effects of this invention are as follows: By covering the contact surface with a soft conductive substrate layer and setting some protruding hard ceramic particles on the surface of the soft conductive substrate layer, the hardness of the hard ceramic particles is much greater than that of the oxide. During the plug insertion and removal process, the hard ceramic particles can scratch the oxide layer (mainly copper oxide) on the socket contact surface, thereby actively causing the oxide layer to crack and exposing the fresh copper substrate. This allows the soft conductive substrate layer to directly contact the copper substrate, thereby establishing a low-resistance, highly stable conductive path and avoiding the problem of the oxide layer causing the contact resistance to continuously increase.

[0017] The protrusion height of the hard ceramic particles is controlled within 8μm, ensuring that the particles can penetrate the oxide layer while stably embedding into the soft conductive substrate layer. Since the hardness of the soft conductive substrate layer is much lower than that of the copper substrate, when the hard ceramic particles contact the copper substrate of the socket under significant pressure, they can further embed into the soft conductive substrate layer, reducing the contact pressure between the particles and the copper substrate, thereby mitigating wear on the copper substrate. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the connector according to Embodiment 1 of the present invention; Figure 2 yes Figure 1 An enlarged schematic diagram of part A in the middle; Figure 3 This is a schematic diagram of the connector according to Embodiment 2 of the present invention; Figure 4 yes Figure 3 Enlarged schematic diagram of part B; Figure 5 This is a schematic diagram of the connector in Embodiment 3; Figure 6 This is a cross-sectional schematic diagram of the plug assembly according to Embodiment 4 of the present invention; Reference numerals: 1—Connector body; 11—Contact surface; 12—Soft conductive substrate layer; 13—Hard ceramic particles; 14—Collection groove; 15—Shape memory alloy ring; 100—Insulating shell; 101—Positive terminal connector; 1011—Connecting section; 1012—Limiting boss; 1013—Positioning section; 102—Negative terminal connector; 103—Positive terminal wire; 104—Negative terminal wire; 105—Limiting block; 106—Spring; 107—Pre-tightening insulating block; 108—Connector head; 109—Connecting sleeve; 110—Insulating positioning sleeve. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0020] Example 1

[0021] This embodiment provides a connector suitable for plug assemblies that are frequently plugged and unplugged.

[0022] like Figure 1 and Figure 2 As shown, it includes a connector body 1 with a contact surface 11. The connector body serves as the positive electrode of the plug assembly and is a solid copper pillar. The contact surface 11 is the outer wall of the solid copper pillar.

[0023] A soft conductive substrate layer 12 is applied to the contact surface 11. The Vickers hardness of the soft conductive substrate layer 12 is 15-25 HV, which is lower than that of the copper substrate. Specifically, the soft conductive substrate layer 12 is a tin-nickel alloy layer with a nickel volume percentage of 3-5%, meeting the hardness requirements. Tin has excellent conductivity, while nickel improves the wear resistance of the soft conductive substrate layer 12. The thickness of the soft conductive substrate layer 12 is 8-15 μm. For scenarios with frequent insertion and removal, a thinner soft conductive substrate layer 12 is beneficial in resisting repeated insertion and removal wear and is less prone to peeling.

[0024] Hard ceramic particles 13, with a particle size of 5–15 μm, are embedded in the surface of the soft conductive substrate layer 12. The hard ceramic particles 13 possess high hardness, capable of scratching the oxide layer on the socket contact surface. The top of the hard ceramic particles 13 protrudes from the surface of the soft conductive substrate layer 12, with a protrusion height of less than 8 μm, ensuring effective scratching of the oxide layer while maintaining stable embedding within the soft conductive substrate layer 12. The volume of the hard ceramic particles 13 is approximately 10%–20% of the total volume of the soft conductive substrate layer 12 and the hard ceramic particles 13. The hard ceramic particles 13 can be made of Al2O3.

[0025] In this embodiment, during the insertion and removal process, the hard ceramic particles 13 can scratch the oxide layer on the socket contact surface, exposing a new copper substrate. The soft conductive substrate layer 12 directly contacts the newly exposed copper substrate, thereby establishing a low-resistance, highly stable conductive path.

[0026] In preparing the connector of this embodiment, the soft conductive substrate layer 12 and the hard ceramic particles 13 can be generated in one step by a composite electroplating process. Specifically, the electroplating solution uses stannous methanesulfonate as the tin source with a concentration of 30-50 g / L; methanesulfonic acid is a conductive salt with a concentration of 80-120 g / L; Al2O3 particles are suspended in the plating solution at an addition amount of 20-40 g / L, with a particle size of 5-15 μm; at the same time, 1-3 g / L of dispersant, such as gelatin and hydroquinone, is added to prevent particle agglomeration; and 10-30 g / L of nickel microparticles are added.

[0027] Before electroplating, the connector body 1 is degreased, pickled, and activated; then, composite electroplating is performed to co-deposit Sn²⁺ ions and suspended Al₂O₃ particles on the surface of the connector body 1. The electroplating parameters are: current density of 1-3 A / dm³. 2The temperature is 25-35℃, and vigorous mechanical stirring is used to maintain the uniform suspension of Al2O3 particles. The electroplating time is 10-30 minutes, adjusted according to the target thickness. Finally, the plated material is cleaned and dried.

[0028] This process enables Al2O3 particles to be uniformly embedded in the soft conductive substrate layer 12, and most of the particles naturally protrude to a height of less than 8μm.

[0029] To prevent scraped-off oxide particles from accumulating in the socket's holes and affecting conductivity during insertion and removal, this invention provides multiple annular collection grooves 14 on the outer wall of the soft conductive substrate layer 12. The collection grooves 14 have a width of 10-20 μm and a depth of 5-15 μm. During insertion and removal, the entire connector moves axially, allowing most of the scraped-off oxide particles to enter the collection grooves 14, reducing the number of oxide particles accumulating in the socket's holes. The oxide particles in the collection grooves 14 can be removed by blowing. The collection grooves 14 can be processed by laser cutting.

[0030] Example 2

[0031] This embodiment provides a connector suitable for plug assemblies that maintain a connection for a long time after insertion and have a low frequency of insertion and removal.

[0032] like Figure 3 and Figure 4 As shown, it includes a connector body 1 with a contact surface 11. The connector body serves as the positive electrode of the plug assembly and is a solid copper pillar. The contact surface 11 is the outer wall of the solid copper pillar.

[0033] The contact surface 11 is covered with a soft conductive substrate layer 12. The Vickers hardness of the soft conductive substrate layer 12 is 8-15 HV, and a pure tin layer can be used.

[0034] Hard ceramic particles 13, which can be Al2O3, are embedded in the surface of the soft conductive substrate layer 12. The particle size of the hard ceramic particles 13 is 5–15 μm, and the top of the hard ceramic particles 13 protrudes from the surface of the soft conductive substrate layer 12 with a protrusion height of less than 8 μm.

[0035] During the insertion process, the connector is inserted into the socket hole, and the hard ceramic particles 13 on the connector contact surface 11 scratch the oxide layer on the socket contact surface, exposing a new copper substrate, so that the soft conductive substrate layer 12 directly contacts the newly exposed copper substrate, thereby establishing a low-resistance and highly stable conductive path.

[0036] After the connection is made, the newly exposed copper substrate will gradually oxidize, leading to a gradual increase in contact resistance and heat generation, especially in high-current (5A-20A) connectors, where the high heat generation and high temperature cause rapid oxidation at the contact point. For plugs that remain connected for extended periods after insertion, to slow down the oxidation of the newly exposed copper substrate, this embodiment includes a shape memory alloy ring 15 between the soft conductive substrate layer 12 and the contact surface 11. The shape memory alloy ring 15 has a phase transition temperature of 40–60°C and a radial expansion of 0.05–0.15 mm. The shape memory alloy ring 15 is an open ring that is in a contracted state at room temperature; when its temperature reaches the phase transition temperature, it deforms. In this embodiment, when the temperature of the shape memory alloy ring 15 reaches the phase transition temperature of 40–60°C, the shape memory alloy ring 15 expands radially, increasing its diameter by 0.05–0.15 mm, and the increase in diameter does not exceed 5% of the diameter of the connector body 1.

[0037] In this embodiment, the soft conductive substrate layer 12 is made of pure tin, which is easily deformed. After the connector and socket are connected and energized, the temperature at the connection point rises. When the current is large, the temperature at the contact point can reach 40–60°C. The shape memory alloy ring 15 expands radially, applying a radial thrust to the soft conductive substrate layer 12, increasing the pressure between the soft conductive substrate layer 12 and the socket contact surface. This pressure causes the soft conductive substrate layer 12 to generate micron-level flow, thereby fully filling the microscopic uneven gaps between the soft conductive substrate layer 12 and the socket contact surface, improving the sealing of the connection, preventing external air, dust, etc. from entering the mating gap, thus effectively alleviating the oxidation of the socket mating surface and keeping the contact resistance stable.

[0038] In this embodiment, the thickness of the soft conductive substrate layer 12 is 20-30 μm. The greater thickness provides more space for plastic deformation, which is beneficial for wrapping the scraped oxide particles and improving the sealing effect of the contact interface.

[0039] The advantage of this embodiment is that it can effectively slow down the oxidation of the newly exposed copper substrate on the socket contact surface. The disadvantage is that the soft conductive substrate layer 12 is relatively soft and easily deformed after insertion and removal. Therefore, it is suitable for application scenarios with low frequency of insertion and removal, long-term connection and large current.

[0040] In this embodiment, the shape memory alloy ring 15 adopts a NiTiCu alloy system, with the following atomic percentages: nickel 44-49%, titanium 42-47%, and copper 5-9%. This material has a narrow phase transition temperature hysteresis, good thermomechanical stability, and can repeatedly expand and contract. Its preparation process is as follows: According to the above atomic percentages, nickel, titanium, and copper raw materials are melted in a vacuum induction furnace and cast into ingots.

[0041] The ingot is homogenized and annealed at a temperature of 850-950℃, then hot-forged or hot-rolled into a plate, and then cold-rolled in multiple passes to a strip with a thickness of 0.15-0.25mm.

[0042] The strip is punched into a C-shaped open ring using a stamping die. The opening width is about 0.5 to 1 mm, which facilitates elastic deformation during assembly. The inner diameter is slightly smaller than the outer diameter of the connector body 1, so that it can hold the connector body 1 tightly.

[0043] The C-ring is heated to above the phase transformation temperature (approximately 100-120℃), then placed into an expanding mold to expand its inner diameter by 0.05-0.15 mm, and held for 5 minutes. It is then cooled to below -10℃ (below the martensitic phase transformation completion temperature) and held for another 5 minutes. This cycle is repeated 5 to 10 times to allow the shape memory alloy to "remember" the expanded shape. After training, the alloy is in a martensitic state at room temperature, and its inner diameter shrinks to a size smaller than the outer diameter of the connector body, resulting in a shape memory alloy ring 15.

[0044] During assembly, the shape memory alloy ring 15 is cooled to a temperature of -30 to -50°C to make it soft and easily deformable. Then, a flaring tool is used to expand it, increasing its inner diameter, and then it is fitted onto the connector body 1. When its temperature returns to room temperature, the hardness of the shape memory alloy ring 15 is restored, and its inner diameter automatically shrinks and clamps tightly onto the connector body 1.

[0045] The forming process of the soft conductive substrate layer 12 and the hard ceramic particles 13 is the same as that in Example 1. The difference is that nickel particles are not added to the electroplating solution used in this example.

[0046] Example 3

[0047] like Figure 5 As shown, it includes a connector body 1 with a contact surface 11. The connector body serves as the negative terminal of the plug assembly and is a hollow copper sleeve. The contact surface 11 is the outer surface of the hollow copper sleeve.

[0048] The contact surface 11 is covered with a soft conductive substrate layer 12, and the Vickers hardness of the soft conductive substrate layer 12 is 8-25HV.

[0049] Hard ceramic particles 13 are embedded in the surface of the soft conductive substrate layer 12. The particle size of the hard ceramic particles 13 is 5–15 μm. The top of the hard ceramic particles 13 protrudes from the surface of the soft conductive substrate layer 12, and the protrusion height is less than 8 μm.

[0050] The soft conductive substrate layer 12 can be the same as in Example 1; or it can be the same as in Example 2, and a shape memory alloy ring 15 is provided.

[0051] Example 4

[0052] This embodiment provides a plug assembly, such as Figure 6 As shown, the device includes an insulating housing 100, within which are disposed a positive terminal connector 101 and a negative terminal connector 102, each having a contact surface 11. The positive terminal connector 101 is connected to a positive wire 103, and the negative terminal connector 102 is connected to a negative wire 104. The positive terminal connector 101 is a copper post, and the negative terminal connector 102 is cylindrical. The positive terminal connector 101 is located inside the negative terminal connector 102, and the two are coaxial. The positive wire 103 and the negative wire 104 are used for connection to a power source.

[0053] The contact surfaces 11 of the positive terminal 101 and the negative terminal 102 are covered with a soft conductive substrate layer 12, the Vickers hardness of which is 8-25 HV.

[0054] Hard ceramic particles 13 are embedded in the surface of the soft conductive substrate layer 12. The particle size of the hard ceramic particles 13 is 5–15 μm. The top of the hard ceramic particles 13 protrudes from the surface of the soft conductive substrate layer 12, and the protrusion height is less than 8 μm.

[0055] In this embodiment, the positive terminal connector 101 can be the same as in Embodiment 1 ( Figure 1 and Figure 2 (as shown) or Example 2 ( Figure 3 and Figure 4 The connector shown is the negative terminal connector 102, which adopts the connector of Embodiment 3 (shown). Figure 5 The plug shown.

[0056] Many devices vibrate during operation, and this vibration is directly transmitted to the positive connector 101 and the negative connector 102, causing them to wobble irregularly and with very small amplitude. This wobble leads to repeated micron-level friction on the socket contact surfaces. This friction grinds the metal plating on the socket contact surfaces into fine powder. This powder quickly oxidizes and accumulates at the contact interface, forming an insulating layer. This process is a typical example of fretting corrosion failure, a significant factor leading to poor connector contact. In particular, since the diameter of the positive connector 101 is smaller than the outer diameter of the negative connector 102, the contact area between the positive connector 101 and the socket is small, resulting in higher contact resistance, making the impact of fretting corrosion especially severe.

[0057] To mitigate fretting corrosion failure and enable automatic cleaning of the connector, the insulating housing 100 in this embodiment is provided with an insulating positioning sleeve 110. The front end of the insulating positioning sleeve 110 is provided with a first positioning hole, and the rear end is provided with a second positioning hole. The first positioning hole and the second positioning hole are connected, and the diameter of the second positioning hole is larger than the diameter of the first positioning hole.

[0058] The positive terminal connector 101 includes a connecting segment 1011, a limiting boss 1012, and a positioning segment 1013 arranged sequentially from the front end to the rear end. The connecting segment 1011, the limiting boss 1012, and the positioning segment 1013 are coaxial. The limiting boss 1012 is a circular boss with a diameter larger than that of the connecting segment 1011 and the positioning segment 1013. The connecting segment 1011 is used to mate with a socket. A soft conductive substrate layer 12 and hard ceramic particles 13 are disposed at the front end of the connecting segment 1011. The connecting segment 1011 passes through a first positioning hole and slides in engagement with the first positioning hole. The limiting boss 1012 and the positioning segment 1013 are located in a second positioning hole and slide in engagement with the second positioning hole. A limiting stop 105 is provided in the second positioning hole and slides in engagement with the second positioning hole. A connecting sleeve 109 is provided on the side of the limiting stop 105 facing the positive terminal connector 101. The end of the positioning segment 1013 extends into the connecting sleeve 109 and slides in engagement with the connecting sleeve 109. A spring 106 is provided between the limiting block 105 and the limiting boss 1012. The spring 106 is in a compressed state and has elastic force, which is transmitted to the limiting boss 1012, causing the limiting boss 1012 to fit against the bottom of the second positioning hole. There is a gap between the positioning section 1013 and the limiting block 105, with a gap width of 0.4-0.6mm. The limiting block 105 and the limiting boss 1012 restrict the axial movement distance of the positive terminal connector 101, so that the positive terminal connector 101 can only move axially by 0.4-0.6mm. The opening of the second positioning hole is provided with a pre-tightening insulating block 107 that is threaded into the second positioning hole; the limiting block 105 is provided with a connector 108, which passes through the pre-tightening insulating block 107 and is connected to the positive terminal wire 103.

[0059] In a stable state (without vibration), the spring 106 is compressed, possessing pre-tension force. This force is transmitted to the limiting boss 1012, which adheres tightly to the bottom of the second positioning hole, keeping the positive connector 101 stable. When vibration is transmitted to the positive connector 101, it can move axially with an amplitude of 0.4-0.6 mm. The spring 106 is further compressed and then reset, pushing the positive connector 101 back to its original position. This process continuously cycles, converting external random vibrations into orderly axial reciprocating motion of the positive connector 101. The axial motion of the positive connector 101 does not rapidly wear down the socket contact surface, thus significantly mitigating fretting corrosion failure. Furthermore, in this invention, the axial motion of the positive connector 101 is beneficial, prompting the hard ceramic particles 13 to continuously scrape away the oxide layer, achieving self-cleaning of the oxide layer.

[0060] In manufacturing this plug assembly, the positive terminal 101, negative terminal 102, insulating positioning sleeve 110, limiting block 105, and pre-tightening insulating block 107 are first manufactured separately, and then assembled: the positioning section 1013 of the positive terminal 101 is passed through the second positioning hole and the first positioning hole in sequence until the limiting boss 1012 fits against the bottom of the second positioning hole; then the spring 106 is installed into the second positioning hole, with the spring 106 located outside the positioning section 1013; next, the limiting block 105 is installed into the second positioning hole, and the connecting sleeve 109 of the limiting block 105 is fitted onto the positioning section. The outer wall of the 1013 is in contact with the positioning section 1013, and the spring 106 is located outside the connecting sleeve 109. Then, the pre-tightening insulating block 107 is inserted into the second positioning hole, and the connector 108 passes through the central through hole of the pre-tightening insulating block 107. When the pre-tightening insulating block 107 contacts the limiting stop 105, the pre-tightening insulating block 107 is rotated to compress the spring 106 and generate a pre-tightening force. When the pre-tightening force of the spring 106 meets the requirements, and the gap width between the positioning section 1013 and the limiting stop 105 is 0.4-0.6mm, the rotation of the pre-tightening insulating block 107 is stopped. After assembly, the negative terminal connector 102 is fitted onto the outer wall of the insulating positioning sleeve 110, and the negative terminal wire 104 is welded to the negative terminal connector 102. The positive terminal connector 101 is welded to the positive terminal wire 103. Finally, the entire assembly is placed into the mold, and the insulating shell 100 is formed by injection molding.

[0061] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A plug assembly, including an insulating housing (100), wherein a positive terminal (101) and a negative terminal (102) having a contact surface (11) are disposed inside the insulating housing (100), the positive terminal (101) is connected to a positive wire (103), and the negative terminal (102) is connected to a negative wire (104). Its features are: The contact surfaces (11) of the positive terminal (101) and the negative terminal (102) are covered with a soft conductive substrate layer (12). Hard ceramic particles (13) are embedded in the surface of the soft conductive substrate layer (12). The particle size of the hard ceramic particles (13) is 5–15 μm. The top of the hard ceramic particles (13) protrudes from the surface of the soft conductive substrate layer (12) with a protrusion height of less than 8 μm. The Vickers hardness of the soft conductive substrate layer (12) is 8-15 HV; a shape memory alloy ring (15) is provided between the soft conductive substrate layer (12) and the contact surface (11), the phase transition temperature of the shape memory alloy ring (15) is 40-60℃, and the radial expansion is 0.05-0.15mm; the radial expansion of the shape memory alloy ring (15) applies a radial thrust to the soft conductive substrate layer (12), increasing the pressure between the soft conductive substrate layer (12) and the socket contact surface. This pressure causes the soft conductive substrate layer (12) to generate micron-level flow, thereby fully filling the micro-uneven gap between the soft conductive substrate layer (12) and the socket contact surface, and improving the sealing performance of the plug-in connection; An insulating positioning sleeve (110) is provided inside the insulating outer shell (100). The front end of the insulating positioning sleeve (110) is provided with a first positioning hole, and the rear end is provided with a second positioning hole. The first positioning hole and the second positioning hole are connected, and the diameter of the second positioning hole is larger than the diameter of the first positioning hole. The positive terminal connector (101) includes a connecting section (1011), a limiting boss (1012), and a positioning section (1013) arranged sequentially from the front end to the rear end. The connecting section (1011) passes through the first positioning hole and slides in cooperation with the first positioning hole. The limiting boss (1012) and the positioning section (1013) are located in the second positioning hole and slide in cooperation with the second positioning hole. A limiting block (105) is provided in the second positioning hole and slides in cooperation with the second positioning hole. A connecting sleeve (109) is provided on the side of the limiting block (105) facing the positive terminal connector (101). The end of the positioning section (1013) extends into the connecting sleeve (109) and slides in cooperation with the connecting sleeve (109). A spring (106) is provided between the limiting block (105) and the limiting boss (1012). The spring (106) is in a compressed state. The limiting boss (1012) fits into the bottom of the second positioning hole, and there is a gap between the positioning section (1013) and the limiting block (105); the opening of the second positioning hole is provided with a pre-tightening insulating block (107) that is threaded into the second positioning hole; the limiting block (105) is provided with a connector (108), which passes through the pre-tightening insulating block (107) and is connected to the positive electrode wire (103); when the vibration is transmitted to the positive electrode connector (101), the positive electrode connector (101) moves axially, the spring (106) is first further compressed, and then reset, pushing the positive electrode connector (101) to reset; the above movement is continuously cycled, converting the external vibration into the axial reciprocating motion of the positive electrode connector (101), alleviating the fretting corrosion failure, and the hard ceramic particles (13) continuously scrape off the oxide layer, realizing the self-cleaning of the oxide layer.

2. The plug assembly as claimed in claim 1, characterized in that: The gap between the positioning section (1013) and the limiting block (105) is 0.4-0.6mm.

3. The plug assembly as claimed in claim 1, characterized in that: The soft conductive substrate layer (12) is a pure tin layer.

4. The plug assembly as claimed in claim 1, characterized in that: The hard ceramic particles (13) are Al2O3.

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