DC plug

Abstract

This invention belongs to the field of plugs, specifically a DC plug, comprising an insulating post containing a cylindrical positive plug and a tubular negative plug. The positive and negative plugs extend from the insulating post at their insertion ends. An annular positioning groove is provided on the outer wall of the insertion end of the insulating post. An elastic locking ring with a notch is provided within the positioning groove. At least three spherical movable balls are provided on the outer circumferential surface of the elastic locking ring, and these movable balls slide within the outer circumferential surface of the elastic locking ring, with a portion of the movable balls located outside the positioning groove. The positive plug slides axially with the insulating post, and the positive plug is connected to a wave spring with preload. During insertion and removal, the movable balls roll due to friction, resulting in rolling friction, which is lower than traditional sliding friction. This reduces wear and solves the problems of easy wear and loosening in existing interference fits, while also reducing insertion and removal resistance.

Description

Technical Field

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

[0002] DC power plugs are commonly used power connectors, with one end connected to the device and the other end connected to the power cord. A typical DC power plug usually consists of a cylindrical insulating post containing a ring-shaped negative plug and a cylindrical positive plug. The positive plug is located inside the negative plug and is coaxial with it. The positive plug is soldered to the positive wire of the power cord, and the negative plug is soldered to the negative wire. This type of DC power plug is usually secured by a spring-loaded retainer. However, in applications such as vehicle chargers, drone ground stations, industrial control equipment, and power tools, continuous vibration and impact occur, leading to the following problems with traditional DC power plugs: 1. The negative and positive plugs rely on the elasticity of the elastic element to provide contact pressure. When the equipment is subjected to radial vibration acceleration, a small displacement will occur between the plug and the socket. The small displacement causes the positive pressure on the contact interface to drop to zero instantly, forming a contact interruption at the nanosecond to millisecond level, causing the equipment to lose power instantly and resulting in equipment failure.

[0003] 2. Traditional plugs rely solely on the interference friction of the metal contacts to provide locking force. Under continuous axial vibration, fluctuations in friction cause the plug to gradually pull out of the socket, resulting in poor contact or power outage. To address this issue of vibration-induced loosening, existing technologies typically increase the interference fit between the plug and socket, leading to heavy insertion and extraction forces, a poor user experience, high frictional resistance during insertion and extraction, rapid wear, accelerated metal fatigue, and reduced lifespan. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a DC plug that improves the stability after plugging in, while reducing wear during plugging and unplugging and ensuring service life.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: a DC plug, including an insulating post, in which a cylindrical positive plug and a cylindrical negative plug are disposed, and the positive plug and the negative plug extend out of the insulating post at the insertion end of the insulating post. The outer wall of the insertion end of the insulating post is provided with an annular positioning groove. An elastic locking ring with a notch is provided in the positioning groove. At least three spherical movable balls are provided on the outer circumferential surface of the elastic locking ring. The movable balls slide in cooperation with the outer circumferential surface of the elastic locking ring, and the movable balls are located outside the positioning groove. The positive plug and the insulating post slide in an axial direction, and the positive plug is connected to a wave spring with preload.

[0006] Furthermore, the positive plug includes a pre-embedded section and an adaptive movable section. The adaptive movable section is located outside the insulating post and is connected to the pre-embedded section via a universal ball joint.

[0007] Furthermore, the pre-embedded section is provided with an installation hole, the universal ball joint is located in the installation hole, and a thermal expansion mechanism is provided between the universal ball joint and the bottom of the installation hole. A limit block is provided at the opening of the installation hole, and the inner wall of the limit block can fit against the outer wall of the universal ball joint. The universal ball joint is connected to the adaptive movable section through a connecting column that passes through the limit block. The diameter of the connecting column is smaller than the diameter of the adaptive movable section. Before the thermal expansion mechanism expands, the end face of the adaptive movable section fits against the end face of the limit block. When the thermal expansion mechanism expands, it pushes the universal ball joint to move, causing the end face of the adaptive movable section to detach from the end face of the limit block.

[0008] Furthermore, the thermal expansion mechanism is an elastic air bladder, and the interior of the elastic air bladder is filled with a low-boiling-point liquid.

[0009] Furthermore, the low-boiling-point liquid is perfluoropentane, and the elastic gasbag is also filled with an inert gas.

[0010] Furthermore, the insulating post is provided with a coaxial first plastic sleeve and a second plastic sleeve. The inner diameter of the second plastic sleeve is larger than that of the first plastic sleeve. A wave spring is provided inside the second plastic sleeve. A limiting post for pressing the wave spring is provided at the port of the second plastic sleeve away from the first plastic sleeve. The positive plug passes through the first plastic sleeve and is fixedly connected to the wave spring. The wave spring is connected to a connector that passes through the limiting post.

[0011] Furthermore, the movable ball is made of silicon nitride ceramic or GCr15 bearing steel, and the surface of the movable ball is coated with diamond-like carbon or tungsten disulfide coating.

[0012] Furthermore, the elastic locking ring is made of beryllium bronze C17200.

[0013] Furthermore, the outer circumferential surface of the elastic locking ring is provided with a spherical limiting groove, and the movable ball is located in the spherical limiting groove.

[0014] The beneficial effects of this invention are as follows: 1. By providing an elastic locking ring with a notch on the outer wall of the insertion end of the insulating post, the elastic locking ring can contract and deform under radial pressure. During the insertion process with the socket, the movable ball contacts the inner wall of the socket and is squeezed by the inner wall of the socket. The squeezing force is transmitted to the elastic locking ring, causing the elastic locking ring to contract and deform, reducing its diameter, thereby clamping the insulating post and providing radial clamping force to keep the insulating post stable. In addition, since the movable ball is spherical, it rolls when subjected to friction during insertion and removal. The friction force is rolling friction, which is smaller than traditional sliding friction, thus reducing wear and solving the problem of easy wear and loosening of existing interference fits, while reducing insertion and removal resistance. It can be seen that this invention achieves increased locking force while reducing insertion and removal resistance and wear. In addition, the elastic locking ring also has the function of reducing radial vibration.

[0015] 2. The wave spring can provide axial preload to ensure that the axial contact pressure between the positive plug and the socket is always greater than zero. When the entire DC plug vibrates axially, the positive plug will always be in stable contact with the socket under the action of the wave spring, avoiding contact interruption and power interruption caused by vibration and impact. Attached Figure Description

[0016] Figure 1 This is a cross-sectional schematic diagram of the present invention; Figure 2 This is a schematic diagram of the positive terminal plug; Figure 3 This is a cross-sectional schematic diagram of the location of the elastic locking ring; Reference numerals: 1—Insulating post; 2—Positive plug; 21—Embedded section; 22—Adaptive movable section; 23—Universal ball joint; 24—Mounting hole; 25—Thermal expansion mechanism; 26—Limiting block; 27—Connecting post; 3—Negative plug; 4—Positioning groove; 5—Notch; 6—Elastic locking ring; 7—Moving ball; 8—Wave spring; 11—First plastic sleeve; 12—Second plastic sleeve; 13—Limiting post; 14—Connecting head. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] The DC plug of this invention is suitable for scenarios with frequent vibration, such as... Figure 1 , Figure 2 and Figure 3As shown, the device includes an insulating post 1, within which are a cylindrical positive plug 2 and a cylindrical negative plug 3. The positive plug 2 and negative plug 3 extend beyond the insulating post 1 at their insertion ends. The insulating post 1 is made of insulating material, while the positive plug 2 and negative plug 3 are made of conductive metal. The positive plug 2 is located inside the negative plug 3, and there is a gap between them. The insulating post 1 partially fills the space between the positive plug 2 and negative plug 3, separating them. One end of the positive plug 2 and negative plug 3 is a terminal for connecting to a power cord, and the other end is a insertion end for mating with a socket. The insertion end extends outside the insulating post 1 for connection to the socket.

[0019] The outer wall of the insertion end of the insulating post 1 is provided with an annular positioning groove 4. The positioning groove 4 is circular, and an elastic locking ring 6 with a notch 5 is provided inside the positioning groove 4. The elastic locking ring 6 is adapted to the shape of the positioning groove 4, is made of elastic material, and can be repeatedly deformed and reset. When the elastic locking ring 6 is subjected to radial pressure, it can contract or expand, generating elastic force and decreasing or increasing its diameter. At least three spherical movable balls 7 are provided on the outer circumferential surface of the elastic locking ring 6. The movable balls 7 slide in contact with the outer circumferential surface of the elastic locking ring 6, allowing the movable balls 7 to rotate, and part of the movable balls 7 is located outside the positioning groove 4.

[0020] During insertion, the positive plug 2 and negative plug 3 extend into the socket. The movable ball 7 contacts the socket wall and is squeezed by the socket wall. The pressure is transmitted to the elastic locking ring 6, causing the elastic locking ring 6 to contract and deform inward. The elastic locking ring 6 clamps the insulating post 1. This clamping force acts as the holding force of the DC plug, keeping the DC plug stable. During insertion and removal, the movable ball 7 is in direct contact with the socket wall. Under the action of friction, the movable ball 7 rolls relative to the socket wall, converting traditional sliding friction into rolling friction, reducing friction, slowing down wear, and solving the problem of easy wear and loosening of existing interference fits. At the same time, it reduces the axial push and pull force required for insertion and removal, making insertion and removal easier.

[0021] The positive plug 2 and the insulating post 1 slide in the axial direction, and the positive plug 2 is connected to a preloaded wave spring 8. The wave spring 8 is small in size and occupies little space after installation. After insertion, the wave spring 8 applies an axial preload to the positive plug 2, ensuring that the axial contact pressure between the positive plug 2 and the socket is always greater than zero. When the entire DC plug vibrates axially, the positive plug 2 remains in stable contact with the socket under the elastic force of the wave spring 8, avoiding momentary contact interruption and power outage caused by vibration and impact. Before insertion, the wave spring 8 is only subjected to the pre-compression force during assembly and has an initial preload; during insertion, axial pressure is generated between the positive plug 2 and the socket, and the pressure is transmitted to the wave spring 8, causing the wave spring 8 to be further compressed, increasing the preload.

[0022] Because the diameter of the positive plug 2 is smaller than that of the negative plug 3, after insertion, the contact area between the negative plug 3 and the socket is larger, while the contact area between the positive plug 2 and the socket is smaller, resulting in poorer rigidity. Under vibration, the entire DC plug exhibits slight swaying. The negative plug 3 is more stable overall, with its position remaining almost unchanged, while the positive plug 2 continuously experiences micro-friction, contact point changes, and localized load concentration, making it more prone to deformation, wear, and poor contact. To address these issues, in this invention, the positive plug 2 includes a pre-embedded section 21 and an adaptive movable section 22. The adaptive movable section 22 is located outside the insulating post 1 and is connected to the pre-embedded section 21 via a universal ball joint 23. The adaptive movable section 22 is used for direct connection to the socket, while the pre-embedded section 21 is located inside the insulating post 1. Since the adaptive movable section 22 is connected to the pre-embedded section 21 through the universal ball joint 23, the universal ball joint 23 can rotate, allowing the adaptive movable section 22 to rotate in any direction relative to the pre-embedded section 21 within a certain angle range. When the DC plug vibrates at high frequency, the adaptive movable section 22 can swing adaptively, avoiding micro-friction of the adaptive movable section 22, greatly reducing the wear of the contact part between the adaptive movable section 22 and the socket, and improving the service life and the stability of contact conductivity.

[0023] During insertion, to ensure that the adaptive movable segment 22 quickly aligns with the socket and is smoothly inserted, the position of the adaptive movable segment 22 should ideally remain stable. After insertion, it should then be in a state where it can swing slightly. To achieve this function, in this invention, the pre-embedded segment 21 is provided with a mounting hole 24, the universal ball joint 23 is located inside the mounting hole 24, and a thermal expansion mechanism 25 is provided between the universal ball joint 23 and the bottom of the mounting hole 24. The opening of the mounting hole 24 is provided with a limiting block 26, which has a spherical inner wall and a through hole coaxial with the pre-embedded segment 21. The inner wall of the limiting block 26 can fit against the outer wall of the universal ball joint 23. The universal ball joint 23 is connected to the adaptive movable segment 22 through a connecting post 27 that passes through the limiting block 26. The diameter of the connecting post 27 is smaller than the diameter of the adaptive movable segment 22, and the diameter of the connecting post 27 is smaller than the diameter of the through hole on the limiting block 26. Before expansion, the end face of the adaptive movable segment 22 of the thermal expansion mechanism 25 is in contact with the end face of the limiting block 26. When the thermal expansion mechanism 25 expands, it pushes the universal ball head 23 to move, causing the end face of the adaptive movable segment 22 to disengage from the end face of the limiting block 26. Before insertion, the thermal expansion mechanism 25 is in an unexpanded state, applying a pulling force to the universal ball head 23 and the adaptive movable segment 22, causing the end face of the adaptive movable segment 22 to be in contact with the end face of the limiting block 26. The end face contact can limit the adaptive movable segment 22, keeping the adaptive movable segment 22 and the embedded segment 21 in a rigid coaxial state, without swinging or shifting, which is conducive to the rapid alignment and insertion of the adaptive movable segment 22 into the socket. After the connection is completed, the embedded section 21 and the adaptive movable section 22 are energized and heat up. As the temperature rises, the heat is gradually transferred to the thermal expansion mechanism 25. The thermal expansion mechanism 25 gradually expands after its temperature rises, thereby pushing the universal ball joint 23 and the adaptive movable section 22 to move axially relative to the embedded section 21. This causes the end face of the adaptive movable section 22 to disengage from the end face of the limiting block 26. At this time, the adaptive movable section 22 can swing slightly in any direction. With the above structure, before the thermal expansion mechanism 25 expands, the elastic deformation of the wave spring 8 is small, and the preload is small. When the thermal expansion mechanism 25 expands, the front end of the adaptive movable section 22 is already engaged with the socket, and the adaptive movable section 22 can no longer move axially away from the embedded section 21. The thrust of the thermal expansion mechanism 25 is transmitted from one end to the adaptive movable section 22 and from the other end to the embedded section 21, which can push the embedded section 21 to move axially, causing the embedded section 21 to further compress the wave spring 8. The elastic force of the wave spring 8 increases, and the preload increases. When the DC plug is unplugged from the socket, the thermal expansion mechanism 25 gradually cools and contracts, causing the end face of the adaptive movable section 22 to re-fit against the end face of the limiting block 26, and the adaptive movable section 22 remains fixed.

[0024] In this invention, the thermal expansion mechanism 25 is an elastic airbag filled with a low-boiling-point liquid. The specific low-boiling-point liquid can be determined based on the ambient temperature of the operating environment. In high-temperature environments, a liquid with a relatively high boiling point is used; in low-temperature environments, a liquid with a lower boiling point is used. During normal indoor operation, the low-boiling-point liquid is perfluoropentane, specifically perfluoron-pentane, which has a boiling point of approximately 29°C, slightly higher than room temperature, and vaporizes immediately upon energization. Furthermore, the elastic airbag is also filled with an inert gas, such as nitrogen, to act as a buffer, preventing the airbag from shrinking too much after contraction and increasing internal pressure after expansion. The elastic airbag is typically quite flexible, and a spring can be installed externally to support it, ensuring stable reset after the adaptive movable section 22 is pulled out.

[0025] To facilitate the manufacture of this DC plug, a coaxial first plastic sleeve 11 and a second plastic sleeve 12 are provided inside the insulating post 1. The first plastic sleeve 11 and the second plastic sleeve 12 are made of existing rigid plastic materials, while the insulating post 1 is made of a plastic material with lower hardness. For example, the first plastic sleeve 11 and the second plastic sleeve 12 can be made of PBT (polybutylene terephthalate) plastic, and the insulating post 1 can be made of POM (polyoxymethylene). The inner diameter of the second plastic sleeve 12 is larger than the inner diameter of the first plastic sleeve 11, and the first plastic sleeve 11 and the second plastic sleeve 12 are integrally formed. A wave spring 8 is disposed inside the second plastic sleeve 12, and a limiting post 13 is provided at the port of the second plastic sleeve 12 away from the first plastic sleeve 11. The limiting post 13 is also made of plastic and can be threaded into the second plastic sleeve 12. The positive plug 2 passes through the first plastic sleeve 11 and is fixedly connected to the wave spring 8; the wave spring 8 is connected to a connector 14 that passes through the limiting post 13.

[0026] The manufacturing process is as follows: Manufacture a positive plug 2, a negative plug 3, an elastic locking ring 6, a limiting post 13, a connector 14, and an integrally molded first plastic sleeve 11 and a second plastic sleeve 12; Weld the terminal of the positive plug 2 to one end of the wave spring 8, and then weld the limiting post 13 to the other end of the wave spring 8. Pass the positive plug 2 through the second plastic sleeve 12 and insert it into the first plastic sleeve 11. Install the entire wave spring 8 into the second plastic sleeve 12. Install the limiting post 13 into the port of the second plastic sleeve 12 so that the limiting post 13 contacts the wave spring 8 and pre-compresses the wave spring 8. At the same time, the connector 14 passes through the limiting post 13. Solder connector 14 to the positive terminal of the power cord, place negative plug 3 outside the second plastic sleeve 12, and solder the terminal of negative plug 3 to the negative terminal of the power cord. The positive plug 2 and the negative plug 3 are installed into the mold. The mold is used for positioning so that the negative plug 3 and the positive plug 2 are coaxial. Then, the insulating column 1 with the positioning groove 4 on the outer wall is formed by injection molding. The insulating column 1 completely wraps the first plastic sleeve 11, the second plastic sleeve 12 and the negative plug 3, and also wraps part of the power line to complete the insulation encapsulation. After the elastic locking ring 6 is opened, it is fitted onto the outer wall of the insulating column 1. Then, the elastic locking ring 6 is pushed to move axially. When the elastic locking ring 6 moves to the positioning groove 4, it automatically retracts and enters the positioning groove 4.

[0027] The above manufacturing processes are all conventional processes with low production difficulty, and can achieve axial pre-tightening of the positive plug 2.

[0028] In this invention, the movable ball 7 is made of silicon nitride ceramic or GCr15 bearing steel, which has high hardness and strength, and a long service life. Furthermore, the surface of the movable ball 7 is coated with a diamond-like carbon or tungsten disulfide coating, which reduces friction. The elastic locking ring 6 is made of beryllium bronze C17200, which has good elasticity, fatigue resistance, and can accurately reset after multiple deformations.

[0029] The elastic locking ring 6 has a spherical limiting groove on its outer circumferential surface. The movable ball 7 is located in the spherical limiting groove and can roll in any direction within it, but cannot disengage from the groove. To facilitate the manufacture of the elastic locking ring 6 with the movable ball 7 on its outer circumferential surface, the elastic locking ring 6 can be divided into two equal halves along its radial section. During assembly, the movable ball 7 is first inserted into one half of the spherical limiting groove, and then the two halves are joined together. Spot welding can be used to connect the two halves into one piece.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the 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 DC plug, comprising an insulating post (1), wherein a cylindrical positive plug (2) and a cylindrical negative plug (3) are disposed within the insulating post (1), the positive plug (2) and the negative plug (3) extending out of the insulating post (1) at their insertion ends; characterized in that: The outer wall of the insertion end of the insulating post (1) is provided with an annular positioning groove (4). An elastic locking ring (6) with a notch (5) is provided in the positioning groove (4). At least three spherical movable balls (7) are provided on the outer circumferential surface of the elastic locking ring (6). The movable balls (7) slide with the outer circumferential surface of the elastic locking ring (6), and part of the movable balls (7) is located outside the positioning groove (4). The positive plug (2) and the insulating post (1) slide in the axial direction, and the positive plug (2) is connected to a wave spring (8) with preload.

2. The DC plug of claim 1, wherein: The positive plug (2) includes a pre-embedded section (21) and an adaptive active section (22). The adaptive active section (22) is located outside the insulating post (1) and is connected to the pre-embedded section (21) through a universal ball joint (23).

3. The DC plug of claim 2, wherein: The pre-embedded section (21) is provided with an installation hole (24). The universal ball head (23) is located inside the installation hole (24), and a thermal expansion mechanism (25) is provided between the universal ball head (23) and the bottom of the installation hole (24). A limit block (26) is provided at the opening of the installation hole (24). The inner wall of the limit block (26) can fit against the outer wall of the universal ball head (23). The universal ball head (23) is connected to the adaptive movable section (22) through a connecting column (27) that passes through the limit block (26). The diameter of the connecting column (27) is smaller than the diameter of the adaptive movable section (22). Before the thermal expansion mechanism (25) expands, the end face of the adaptive movable section (22) fits against the end face of the limit block (26). When the thermal expansion mechanism (25) expands, it pushes the universal ball head (23) to move, so that the end face of the adaptive movable section (22) is separated from the end face of the limit block (26).

4. The DC plug of claim 3, wherein: The thermal expansion mechanism (25) is an elastic air bladder, which is filled with a low-boiling-point liquid.

5. The DC plug of claim 4, wherein: The low-boiling-point liquid is perfluoropentane, and the elastic gasbag is also filled with inert gas.

6. The DC plug as described in claim 1, characterized in that: The insulating post (1) is provided with a coaxial first plastic sleeve (11) and a second plastic sleeve (12). The inner diameter of the second plastic sleeve (12) is larger than the inner diameter of the first plastic sleeve (11). The wave spring (8) is provided inside the second plastic sleeve (12). The port of the second plastic sleeve (12) away from the first plastic sleeve (11) is provided with a limiting post (13) to press the wave spring (8). The positive plug (2) passes through the first plastic sleeve (11) and is fixedly connected to the wave spring (8). The wave spring (8) is connected to a connector (14) that passes through the limiting post (13).

7. The DC plug as described in claim 1, characterized in that: The movable ball (7) is made of silicon nitride ceramic or GCr15 bearing steel, and the surface of the movable ball (7) is coated with diamond-like carbon or tungsten disulfide coating.

8. The DC plug as described in claim 1, characterized in that: The elastic locking ring (6) is made of beryllium bronze C17200.

9. The DC plug as described in claim 1, characterized in that: The outer circumferential surface of the elastic locking ring (6) is provided with a spherical limiting groove, and the movable ball (7) is located in the spherical limiting groove.

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