Liquid metal electrical slip ring for a robot joint

Abstract

The utility model discloses a kind of liquid metal electric slip rings for robot joint, it includes: stator assembly;Rotor assembly, the rotor assembly can rotate relative to the stator assembly;The rotor assembly is cooperated with the stator assembly to form at least one annular liquid metal cavity;At least one stator electrode, the stator electrode is located on the surface of the stator assembly and is located in the annular liquid metal cavity;At least one rotor electrode, the rotor electrode is located on the surface of the rotor assembly and is located in the annular liquid metal cavity;Assembly component, the assembly component is cooperated with the stator assembly, the rotor assembly to be combined together respectively.From to form annular liquid metal cavity for liquid metal flow and realize electric signal transmission by electrode.

Description

Technical Field

[0001] This utility model relates to an electric slip ring, specifically a liquid metal electric slip ring for robot joints, and more particularly to a liquid metal electric slip ring (conductive slip ring) that enables infinite rotation of robot joints. Background Technology

[0002] With the increasing application of robotics in fields such as industrial automation, aerospace, and precision medicine, the requirements for the degrees of freedom of robot joints are becoming increasingly stringent. Traditional robot joints are limited by the problem of wire entanglement, and their rotation angle is usually restricted to within 360°, making it impossible to achieve true infinite rotation. This severely restricts the robot's workspace and mobility.

[0003] In recent years, although non-contact energy and data transmission technologies (such as inductive coupling, radio frequency communication, and optical communication) have been proposed, these technologies typically suffer from problems such as low power density, system complexity, high cost, and susceptibility to electromagnetic interference. They also struggle to simultaneously, efficiently, and stably transmit high-power electrical energy and various weak electrical signals within a single joint. Therefore, existing technologies lack a joint conductivity solution that can simultaneously satisfy requirements of unlimited rotation, low contact resistance, high transmission stability, long lifespan, maintenance-free operation, and compatibility with mixed power and signal transmission. This has become a key technological bottleneck restricting the development of advanced robotics towards higher degrees of freedom and reliability.

[0004] Chinese utility model patent application number 202221215182.0 discloses a liquid metal conductive slip ring, comprising: a housing; a fixed conductive shaft embedded at one end of the housing; and a movable conductive shaft rotatably embedded at the other end of the housing, with the two opposite end faces of the movable conductive shaft and the fixed conductive shaft fitting together to form a cavity; the cavity is used to contain liquid metal; the fixed conductive shaft or the movable conductive shaft has an injection hole communicating with the cavity, and a sealing structure is provided at the injection hole. The liquid metal conductive slip ring provided by this patent, through the fitting between the opposite faces of the fixed conductive shaft and the movable conductive shaft to form a cavity for containing liquid metal, uses liquid metal as the conductive working medium, exhibiting strong current carrying capacity and good stability, and is suitable for applications involving corrosive liquids and large current transmission, such as anodic oxidation electrochemical feeding electrodes, electroplating, and electrolysis; the sealing structure in the injection hole ensures the injection of liquid metal without leakage. The fixed conductive shaft of this liquid metal conductive slip ring is usually connected to a wire, so that the wire passes directly through the joint shaft. Although its structure is simple, when the joint rotates beyond a certain angle (usually less than 360°), the wire will become entangled or twisted and broken, which severely limits the rotation angle of the joint and makes it impossible to achieve infinite rotation (i.e., rotation without angle limit), and there are obvious safety hazards. Summary of the Invention

[0005] Based on the above, this utility model provides a liquid metal slip ring for robot joints, which can fundamentally solve the problem of wire entanglement and achieve infinite continuous rotation of the joint.

[0006] To achieve the above objectives, this utility model provides a liquid metal slip ring for robot joints, comprising: Stator assembly; A rotor assembly that is rotatable relative to the stator assembly; the rotor assembly and the stator assembly cooperate to form at least one annular liquid metal channel; At least one stator electrode, the stator electrode being located on the surface of the stator assembly and within the annular liquid metal cavity; At least one rotor electrode, the rotor electrode being located on the surface of the rotor assembly and within the annular liquid metal cavity; Assembly components, which respectively cooperate with the stator assembly and the rotor assembly to assemble them together.

[0007] Optimally, each of the stator electrodes has a first electrode lead extending through the stator assembly, and each of the rotor electrodes has a second electrode lead extending through the rotor assembly.

[0008] Furthermore, the rotor assembly cooperates with the stator assembly to form multiple annular liquid metal channels that are spaced apart and coaxial; the number of stator electrodes and the number of rotor electrodes are the same as the number of annular liquid metal channels, so that the stator electrodes and the rotor electrodes are arranged one-to-one in the annular liquid metal channels.

[0009] Furthermore, the stator electrode and the rotor electrode are independently arranged in a ring shape.

[0010] Optimally, the stator assembly includes a stator body, a mounting body formed on the circumferential surface of the stator body, and a first through hole opened at the center of the stator body. The mounting body has a plurality of mounting holes. Optimally, at least the portion of the first through hole near the rotor assembly is provided with an internal thread, and the circumferential surface of the stator body is provided with an external thread located on one side of the mounting body.

[0011] Furthermore, the rotor assembly includes a rotor body, a second through hole opened at the center of the rotor body, and at least one annular groove opened on any surface of the rotor body and facing the stator body; when there are multiple annular grooves, a convex ring is formed between two adjacent annular grooves, and the annular grooves cooperate with the stator body to form the annular liquid metal cavity.

[0012] Furthermore, each of the convex rings has a first receiving groove on its end face, and the rotor body also has a second receiving groove located on the outer ring of the annular groove and a third receiving groove located on the inner ring of the annular groove. Ideally, the stator assembly and the rotor assembly are sealed by a sealing ring, the sealing ring comprising a plurality of first sealing rings disposed in each of the first receiving grooves and the third receiving grooves and in contact with the stator body, and a second sealing ring disposed in the second receiving grooves and in contact with the stator body.

[0013] Furthermore, the assembly includes an outer sealing cover detachably fitted onto the stator body and abutting against the rotor body, and an inner sealing cover detachably installed in the first through hole and the second through hole and abutting against the rotor body. Ideally, a first ring of sliding balls is provided at the contact point between the outer sealing cover and the rotor body, and a second ring of sliding balls is provided at the contact point between the inner sealing cover and the rotor body.

[0014] Furthermore, a first external thread located on one side of the mounting body is provided on the circumferential surface of the stator body. The outer sealing cover includes a first ring sleeve that mates with the stator body, a first internal thread formed on the inner wall of the first ring sleeve and mates with the first external thread, and a retaining ring formed on the outer end face of the first ring sleeve and in contact with the outer end face of the rotor body.

[0015] Furthermore, at least the portion of the first through hole near the rotor body is provided with a second internal thread. The inner sealing cover includes a second ring sleeve inserted into the first through hole and the second through hole, a second external thread formed on the circumferential surface of the second ring sleeve and cooperating with the second internal thread, and a convex ring formed on the outer end face of the second ring sleeve and in contact with the outer end face of the rotor body. The second ring sleeve has a third through hole.

[0016] This invention relates to a liquid metal slip ring for robot joints. By coordinating stator assemblies, rotor assemblies, stator electrodes, and rotor electrodes, an annular liquid metal channel is formed for the flow of liquid metal, and electrical signals are transmitted through electrodes. Because signal transmission is achieved indirectly through the liquid metal medium, there are no wire connections, eliminating the possibility of wire entanglement and allowing for unlimited rotation. In short, this invention uses liquid metal as the transmission medium, avoiding direct friction between metals, resulting in virtually no mechanical wear and no wear particles. The electrodes on both sides maintain stable contact and have low internal resistance. These advantages ensure a long service life and low maintenance costs.

[0017] The liquid metal used is preferably a low-viscosity, high-conductivity, low-toxicity, or non-toxic low-melting-point liquid metal. During filling, the volume of the liquid metal should occupy 80% to 95% of the total cavity volume to ensure the continuity of electrical connections and allow space for thermal expansion. Since the cavity contains liquid metal, its sealing performance is crucial. Therefore, sealing rings are installed between each cavity, and sealing caps are also installed on the outer and inner sides of the rotor. A constant pressure is applied to the sliding rotor assembly to ensure the sealing rings are tightly attached to the surface of the sliding stator assembly, jointly ensuring the cavity's sealing performance. (The transmission medium is liquid, eliminating mechanical wear between solids and greatly extending service life; the theoretical lifespan depends only on the aging time of the seals and materials; the sealing structure prevents leakage, allowing the system to operate stably for long periods in harsh environments without frequent maintenance; the liquid metal has excellent contact with the electrodes, with extremely low and stable contact resistance, reducing energy loss and signal transmission noise and jitter; it can simultaneously transmit high-power current and weak signals, meeting the combined requirements of robot joints for synchronous transmission of power and sensing signals.)

[0018] To achieve high-speed rotation of the slip ring rotor assembly, it is necessary to ensure low friction between the contact surfaces of the slip ring rotor assembly and the slip ring stator assembly, as well as between the slip ring rotor assembly and the inner and outer glands. Therefore, the sealing ring material must be strictly controlled, and ball bearings should be used between the inner and outer glands and the slip ring rotor to reduce the coefficient of friction, providing the necessary conditions for high-speed rotation of the slip ring rotor assembly.

[0019] To ensure stable electrical signal transmission, the internal electrodes are designed as a continuous circular ring. Combined with the cavity being filled with 80%-95% liquid metal, this allows the electrodes to smoothly transmit electrical signals through the liquid metal regardless of their orientation during rotation. The continuous circular ring design also ensures that the internal liquid metal does not experience strong fluctuations during high-speed rotation. Both of these factors work together to ensure stable electrical signal transmission. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the liquid metal slip ring for robot joints according to this utility model; Figure 2 for Figure 1 Exploded view; Figure 3 for Figure 1 Cross-sectional view; Figure 4 This is a schematic diagram of the stator assembly in the liquid metal slip ring for robot joints of this utility model; Figure 5 This is a schematic diagram of the rotor assembly in the liquid metal slip ring for robot joints of this utility model. Detailed Implementation

[0021] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings.

[0022] like Figures 1 to 3 The liquid metal slip ring for robot joints shown mainly includes a stator assembly 1, a stator electrode 3, a rotor assembly 7, a rotor electrode 8, and an assembly assembly.

[0023] The stator assembly 1 is made of high-strength insulating plastic, and its structure preferably includes a stator body 11, a mounting body 12 formed on the circumferential surface of the stator body 11 (the thickness of the mounting body 12 is less than the thickness of the stator body 11, and the forming method is usually one-piece molding or welding, or other conventional methods), and a first through hole 14 opened at the center of the stator body 11 (the axis of the first through hole 14 coincides with the axis of the stator body 11); the mounting body 12 has a plurality of mounting holes 121 for mounting the stator assembly 1 on other structures (such as robot joints, etc.) using conventional fasteners. Figure 4 (As shown). Specifically, the first through hole 14 has an internal thread 141 at least near the rotor assembly 7, and the stator body 11 has an external thread 13 on the circumferential surface located on the side of the mounting body 12 (the side near the rotor assembly 7).

[0024] The rotor assembly 7 can rotate relative to the stator assembly 1, but the rotor assembly 7 cooperates with the stator assembly 1 to form at least one annular liquid metal cavity (the annular liquid metal cavity is filled with liquid metal, preferably a low-viscosity, high-conductivity, low-toxicity or non-toxic low-melting-point liquid metal; the volume of the liquid metal should occupy 80%-95% of the total cavity volume during filling, which ensures the continuity of electrical connection and reserves space for thermal expansion). The rotor assembly 7 is also made of high-strength insulating plastic; preferably, the rotor assembly 7 cooperates with the stator assembly 1 to form multiple annular liquid metal cavities that are spaced apart and coaxial (the specific number of annular liquid metal cavities can be conventionally selected according to the actual application scenario and / or the size of the slip ring, such as 5 to 20 cavities, and 8 cavities are selected in this embodiment). The stator electrode 3 and the rotor electrode 8 described below achieve electrical signal transmission through the liquid metal medium inside. Since the signal transmission is indirectly achieved through the liquid metal medium, there is no wire connection and no wire entanglement will occur, thus enabling infinite rotation.

[0025] There is at least one stator electrode 3, located on the surface of the stator assembly 1 and within the annular liquid metal cavity (i.e., the stator electrode 3 is typically mounted on the surface of the stator assembly 1, indicating that part of the function of the stator assembly 1 is as a mounting carrier for the stator electrode 3). There is also at least one rotor electrode 8, located on the surface of the rotor assembly 7 and within the annular liquid metal cavity (i.e., the rotor electrode 8 is typically mounted on the surface of the rotor assembly 7, indicating that part of the function of the rotor assembly 7 is as a mounting carrier for the rotor electrode 8). The number of stator electrodes 3 and rotor electrodes 8 is the same as the number of annular liquid metal cavities, ensuring a one-to-one correspondence between the stator electrodes 3 and rotor electrodes 8 within the annular liquid metal cavities. Each stator electrode 3 is made of a highly conductive material (such as gold-plated copper or silver) and is used to connect to an externally fixed power supply or signal source; each slip ring rotor-side electrode is also made of a highly conductive material (such as gold-plated copper or silver) and is used to connect to a rotor-side fixed power supply or signal source.

[0026] In this embodiment, each stator electrode 3 has a first electrode lead-out 31 penetrating the stator assembly 1, and each rotor electrode 8 has a second electrode lead-out 81 penetrating the rotor assembly 7. The stator electrode 3 and rotor electrode 8 are independently arranged in a ring shape (i.e., a continuous ring shape), which is beneficial to ensure the stability of electrical signal transmission. Combined with the cavity being filled with 80%-95% liquid metal, both electrodes can smoothly transmit electrical signals through the liquid metal regardless of their posture during rotation. The continuous ring shape of the electrodes ensures that the internal liquid metal will not fluctuate strongly during high-speed rotation. The above two factors work together to ensure stable transmission of electrical signals. In addition, using liquid metal as the transmission medium avoids direct friction between metals, resulting in almost no mechanical wear and no wear particles. The electrodes on both sides have stable contact and low internal resistance. These advantages ensure its long service life and low maintenance cost.

[0027] The assembly components are respectively matched with stator assembly 1 and rotor assembly 7 to combine them together, ensuring the overall connection strength of the liquid metal slip rings for the robot joints.

[0028] In this embodiment, the rotor assembly 7 includes a rotor body 71, a second through hole 70 opened at the center of the rotor body 71 (the axis of the second through hole 70 coincides with the axis of the rotor body 71), and at least one annular groove 72 opened on any surface of the rotor body 71 (the surface facing the stator body) and facing the stator body 11. When there are multiple annular grooves 72, a convex ring 73 is formed between two adjacent annular grooves 72. The annular grooves 72 cooperate with the stator body 11 to form the aforementioned annular liquid metal cavity (therefore, the number of annular grooves 72 is consistent with the number of annular liquid metal cavities), such as... Figure 5 As shown.

[0029] Each convex ring 73 has a first receiving groove 731 on its end face, and the rotor body 71 also has a second receiving groove 74 located on the outer ring of the annular groove 72 and a third receiving groove 711 located on the inner ring of the annular groove 72 (thus, multiple annular grooves 72 are located between the second receiving groove 74 and the third receiving groove 711; the number between the second receiving groove 74 and the third receiving groove 711 is usually one, but can also be set to multiple conventionally selected ones according to the sealing requirements).

[0030] Since liquid metal is present in the cavity (i.e., the annular liquid metal channel), its sealing performance is crucial. Therefore, a sealing ring is provided between each channel. The assembly assembly applies a constant pressure to the rotor assembly 7 to ensure that the sealing ring is tightly attached to the surface of the stator assembly 1, thus ensuring the cavity's sealing performance. Specifically, the stator assembly 1 and the rotor assembly 7 are sealed by sealing rings. The sealing rings include a plurality of first sealing rings 6 (the first sealing ring 6 is an inner sealing ring, and the size can be conventional (such as 1 mm, etc.). It is also a dynamic seal and is mainly made of friction-resistant and low friction coefficient materials (such as special fluororubber, polyimide). Its core function is to prevent liquid metal leakage while allowing the rotor assembly 7 to rotate smoothly) and a second sealing ring 2 (the second sealing ring 2 is an outer sealing ring, and the size can be conventional (such as 2 mm, etc., which is usually thicker than the aforementioned first sealing ring 6). It is a dynamic seal and is mainly made of friction-resistant and low friction coefficient materials (such as special fluororubber, polyimide). Its core function is to prevent liquid metal leakage while allowing the rotor assembly 7 to rotate smoothly) and a second sealing ring 2 (the second sealing ring 2 is an outer sealing ring, and the size can be conventional (such as 2 mm, etc., which is usually thicker than the aforementioned first sealing ring 6). It is also a dynamic seal and is mainly made of friction-resistant and low friction coefficient materials (such as special fluororubber, polyimide). Its core function is to prevent liquid metal leakage while allowing the rotor assembly 7 to rotate smoothly) and a second sealing ring 2 (the second sealing ring 2 is an outer sealing ring, and the size can be conventional (such as 2 mm, etc., which is usually thicker than the aforementioned first sealing ring 6).

[0031] In this embodiment, the assembly includes an outer sealing cover 4 detachably fitted onto the stator body 11 and abutting against the rotor body 71, and an inner sealing cover 10 detachably installed in the first through hole 14 and the second through hole 70 and abutting against the rotor body 71. A first sliding ball 5 is provided at the contact point between the outer sealing cover 4 and the rotor body 71, and a second sliding ball 9 is provided at the contact point between the inner sealing cover 10 and the rotor body 71. That is, the first sliding ball 5 is installed between the rotor assembly 7 and the outer sealing cover 4, and its main function is to reduce the friction between the rotor assembly 7 and the outer sealing cover 4; the second sliding ball 9 is installed between the rotor assembly 7 and the inner sealing cover 10, and its main function is to reduce the friction between the rotor assembly 7 and the inner sealing cover 10, thereby ensuring the smooth performance of the rotor assembly 7 during high-speed rotation.

[0032] The stator body 11 has a first external thread 13 on its circumferential surface located on one side of the mounting body 12. The outer sealing cover 4 includes a first ring 41 that mates with the stator body 11, a first internal thread 43 formed on the inner wall of the first ring 41 that mates with the first external thread 13, and a retaining ring 42 formed on the outer end face of the first ring 41 that contacts the outer end face of the rotor body 71. The first through hole 14 has a second internal thread 141 at least near the rotor body 71. The inner sealing cover 10 includes a second ring 101 inserted into the first through hole 14 and the second through hole 70, a second external thread 103 formed on the circumferential surface of the second ring 101 that mates with the second internal thread 141, and a convex ring 102 formed on the outer end face of the second ring 101 that contacts the outer end face of the rotor body 71. The second ring 101 has a third through hole 104. The outer sealing cover 4 is locked to the stator assembly 1 by threads, which firmly restricts the rotor assembly 7 inside it. Together with the sealing ring, it ensures the sealing of the liquid metal cavity. The inner sealing cover 10 is locked to the stator assembly 1 by threads and slip ring, which firmly restricts the rotor assembly 7. Together with the sealing ring, it ensures the sealing of the liquid metal cavity.

[0033] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They should not be construed as limiting the scope of protection of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be included within the scope of protection of this utility model.

Claims

1. A liquid metal slip ring for robot joints, characterized in that, It includes: Stator assembly (1); Rotor assembly (7), which is rotatable relative to stator assembly (1); The rotor assembly (7) cooperates with the stator assembly (1) to form at least one annular liquid metal channel; At least one stator electrode (3) is located on the surface of the stator assembly (1) and within the annular liquid metal cavity; At least one rotor electrode (8) is located on the surface of the rotor assembly (7) and within the annular liquid metal cavity; Assembly components, which are respectively engaged with the stator assembly (1) and the rotor assembly (7) to assemble them together.

2. The liquid metal slip ring for robot joints according to claim 1, characterized in that: Each of the stator electrodes (3) has a first electrode lead (31) through the stator assembly (1), and each of the rotor electrodes (8) has a second electrode lead (81) through the rotor assembly (7).

3. The liquid metal slip ring for robot joints according to claim 1 or 2, characterized in that: The rotor assembly (7) cooperates with the stator assembly (1) to form multiple annular liquid metal channels that are spaced apart and coaxial; the number of stator electrodes (3) and the number of rotor electrodes (8) are the same as the number of annular liquid metal channels, so that the stator electrodes (3) and the rotor electrodes (8) are arranged in the annular liquid metal channels in a one-to-one correspondence.

4. The liquid metal slip ring for robot joints according to claim 1 or 2, characterized in that: The stator electrode (3) and the rotor electrode (8) are independently arranged in a ring shape.

5. The liquid metal slip ring for robot joints according to claim 1, characterized in that: The stator assembly (1) includes a stator body (11), a mounting body (12) formed on the periphery of the stator body (11), and a first through hole (14) opened at the center of the stator body (11). The mounting body (12) has a plurality of mounting holes (121). The first through hole (14) has an internal thread (141) at least near the rotor assembly (7), and the stator body (11) has an external thread (13) on the circumferential surface located on one side of the mounting body (12).

6. The liquid metal slip ring for robot joints according to claim 5, characterized in that: The rotor assembly (7) includes a rotor body (71), a second through hole (70) opened at the center of the rotor body (71), and at least one annular groove (72) opened on any surface of the rotor body (71) and facing the stator body (11); when there are multiple annular grooves (72), a convex ring (73) is formed between two adjacent annular grooves (72), and the annular grooves (72) cooperate with the stator body (11) to form the annular liquid metal cavity.

7. The liquid metal slip ring for robot joints according to claim 6, characterized in that: Each of the convex ring bodies (73) has a first receiving groove (731) on its end face, and the rotor body (71) also has a second receiving groove (74) located on the outer ring of the annular groove (72) and a third receiving groove (711) located on the inner ring of the annular groove (72). The stator assembly (1) and the rotor assembly (7) are sealed by a sealing ring, which includes a plurality of first sealing rings (6) disposed in each of the first receiving grooves (731) and the third receiving grooves (711) and in contact with the stator body (11), and a second sealing ring (2) disposed in the second receiving groove (74) and in contact with the stator body (11).

8. The liquid metal slip ring for robot joints according to claim 6, characterized in that: The assembly includes an outer sealing cover (4) that is detachably fitted onto the stator body (11) and abuts against the rotor body (71), and an inner sealing cover (10) that is detachably installed in the first through hole (14) and the second through hole (70) and abuts against the rotor body (71). A first sliding ball (5) is provided at the contact point between the outer sealing cover (4) and the rotor body (71), and a second sliding ball (9) is provided at the contact point between the inner sealing cover (10) and the rotor body (71).

9. The liquid metal slip ring for robot joints according to claim 8, characterized in that: The stator body (11) has a first external thread (13) on its circumferential surface located on one side of the mounting body (12). The outer sealing cover (4) includes a first ring (41) that cooperates with the stator body (11), a first internal thread (43) formed on the inner wall of the first ring (41) and cooperating with the first external thread (13), and a retaining ring (42) formed on the outer end face of the first ring (41) and in contact with the outer end face of the rotor body (71).

10. The liquid metal slip ring for robot joints according to claim 8, characterized in that: The first through hole (14) has a second internal thread (141) at least in the portion near the rotor body (71). The inner sealing cap (10) includes a second ring (101) inserted into the first through hole (14) and the second through hole (70), a second external thread (103) formed on the circumferential surface of the second ring (101) and cooperating with the second internal thread (141), and a convex ring (102) formed on the outer end face of the second ring (101) and in contact with the outer end face of the rotor body (71). The second ring (101) has a third through hole (104).

Images