Linear joint and humanoid robot

Abstract

According to the linear joint and the humanoid robot, the requirement for the external space can be reduced, so that the outer diameter size of the linear joint can be reduced, the size and weight of a motor can be reduced as much as possible while the performance of the motor is guaranteed through a slender motor stator, the overall size of the joint is further controlled, and the joint is more compact. And the linear joint is more compact and light. The device comprises a motor assembly, a ball screw pair, a push rod assembly and a joint shell. The motor assembly and the ball screw pair are both arranged in the joint shell, a lead screw rod in the ball screw pair is placed in a cavity of rotor back iron of the motor assembly, an internal circulation type lead screw nut is placed on the lead screw rod, and the internal circulation type lead screw nut and the rotor back iron are connected to form a rolling body. The lead screw is connected with the push rod assembly. The rotor back iron is used for driving the lead screw nut to rotate, the rotation movement of the lead screw nut drives the lead screw rod to move axially, and the lead screw rod is used for driving the push rod assembly to move linearly.

Description

Technical Field

[0001] This application relates to the field of intelligent mechanical technology, and in particular to a linear joint and humanoid robot. Background Technology

[0002] In recent years, with the rapid development of humanoid robots, the types of joint actuators used in humanoid robots have been increasing. Among these, motor-driven joints are the most common. According to the motion mode of the output end, electrically driven joints can be divided into rotary joints and linear joints. Compared with rotary joints, linear joints can convert the rotational motion of the motor into the linear motion of the push rod, and have higher efficiency and stronger impact resistance. They are more suitable for parts of humanoid robots that require explosive motion, such as arms and legs.

[0003] Currently, some linear joint solutions employ planetary roller screw pairs for their telescopic mechanisms, while others use frameless torque motors, a common feature of traditional rotary joints. While both solutions have their advantages, the planetary roller screw approach, though offering higher load-bearing capacity, is more complex, more difficult to manufacture, and less efficient. Conversely, the frameless motors of traditional rotary joints typically have a large outer diameter. This results in significant drawbacks for existing linear joints, including larger joint diameters and greater weight. Consequently, when used in humanoid robots to control wrists and ankles, the large outer diameter makes it difficult to conceal the joint within the robot's shell and increases the risk of interference with other components, leading to poor overall flexibility and maneuverability.

[0004] Therefore, both of the linear joints described above have certain drawbacks, which are not conducive to the rapid development and practical application of humanoid robots. Utility Model Content

[0005] This application provides a linear joint and a humanoid robot to solve the above-mentioned technical problems.

[0006] This application provides a first aspect of a linear joint, including: a motor assembly, a ball screw pair, a push rod assembly, a joint housing, and connecting components;

[0007] Both the motor assembly and the ball screw pair are disposed in the joint housing;

[0008] The ball screw in the ball screw assembly is placed in the cavity of the rotor back iron of the motor assembly. An internal circulation ball screw nut is placed on the ball screw, and the internal circulation ball screw nut is connected to the rotor back iron to form a rolling element.

[0009] The lead screw is connected to the push rod assembly, the push rod assembly is connected to the connecting component, and the connecting component is used to connect to external equipment;

[0010] The rotor back iron is used to drive the lead screw nut to rotate, the rotation of the lead screw nut drives the lead screw to move axially, and the lead screw drives the push rod assembly to move linearly.

[0011] Optionally, the motor assembly includes a motor stator, a rotor back iron, and motor magnets;

[0012] The motor stator is disposed inside the motor housing within the joint housing and is fixedly connected to the inside of the motor housing.

[0013] The rotor back iron is disposed inside the motor stator, and the rotor back iron is provided with an internal cavity for placing the lead screw.

[0014] The motor magnet is disposed between the motor stator and the rotor back iron, and the motor magnet is connected to the outer surface of the rotor back iron.

[0015] Optionally, the inner circulation screw nut on the ball screw assembly is coaxially connected with the rotor back iron to form the rolling element, and the screw nut and the rotor back iron are fixed by glue or interference fit.

[0016] Optionally, a pair of double-row angular contact ball bearings are installed at the positioning end of the rolling element. The inner ring of the double-row angular contact ball bearing is fixed to the outer surface of the lead screw nut. The outer ring of the double-row angular contact ball bearing is provided with external threads. The double-row angular contact ball bearing is connected to a lock nut through the external threads. The lock nut is used to pre-tighten the inner ring of the double-row angular contact ball bearing.

[0017] Optionally, a thin deep groove ball bearing is installed at the floating end of the rolling element, the inner ring of the thin deep groove ball bearing is fixed to the outer end of the rotor back iron shaft, and the outer ring of the thin deep groove ball bearing is connected to a wave spring.

[0018] Optionally, the push rod assembly is a ball spline pair, which includes a push rod and a spline sleeve. The push rod is provided with a groove, which is axially arranged. The spline sleeve is connected to the groove through a steel ball so that the push rod can move linearly.

[0019] The spline sleeve is installed on the concentric inner circle of the front end cover in the joint housing. The front end cover is provided with a concentric boss, and the front end cover is connected to the inner circle of the motor housing through the concentric boss.

[0020] Optionally, the upper end of the push rod is provided with a concentric blind hole, the lower part of the concentric blind hole is provided with an internal thread, the lower end of the lead screw is provided with an external screw with a diameter smaller than the outer circle of the lead screw and a positioning plane, and the external screw is provided with a smooth rod part.

[0021] Optionally, the lead screw is provided with an upper limit plate and a lower limit plate at both ends. The upper limit plate is fixed to the rear end face of the lead screw by screws, and the lower limit plate is embedded in the smooth part of the lead screw and fixed to the positioning plane of the lead screw by a fixing push rod.

[0022] Optionally, the linear joint further includes an encoder assembly disposed at one end of the rolling element, the encoder assembly being used to convert the angular displacement of the rolling element into an electrical signal.

[0023] Optionally, the linear joint further includes a tension / compression sensor, which is electrically connected to the motor driver. One end of the tension / compression sensor is connected to the rear end cover in the joint housing via an external thread, and the rear end cover is connected to the motor housing via screws.

[0024] Optionally, the linear joint further includes a rod end bearing, which is connected and fixed to the push rod and the tension / compression sensor respectively.

[0025] The second aspect of this application provides a humanoid robot, which is equipped with linear joints as described in the first aspect and any one of the first aspects.

[0026] As can be seen from the above technical solutions, this application has the following advantages:

[0027] 1. As a transmission mechanism, the ball screw pair can convert the rotational motion of the motor into linear motion. It features high precision, high efficiency and high rigidity. When used with a spline shaft, it ensures that the push rod will not rotate during linear motion, thus maintaining the stability and positioning accuracy of the push rod, enabling the linear joint to achieve extension and retraction movements efficiently and accurately.

[0028] 2. The direct connection between the lead screw nut and the inner ring of the fixed end rolling bearing enhances the rigidity of the transmission system, reduces deformation and vibration during transmission, and makes the transmission system more stable due to the greater distance between the lead screw nut and the floating end bearing, thus reducing errors caused by bearing floating.

[0029] 3. This application can reduce the need for external space, thereby helping to reduce the outer diameter of the linear joint. The slender motor stator can also minimize the size and weight of the motor while ensuring motor performance, further controlling the overall size of the joint and making the linear joint more compact and lightweight.

[0030] 4. The separate design of the push rod and the lead screw allows for independent manufacturing and optimization of the push rod and the lead screw, improving manufacturing flexibility and efficiency. Furthermore, the push rod and the joint housing are made of lightweight metal materials, which significantly reduces the weight of the joint, making the linear joint lighter, easier to install, and easier to move. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of an overall mechanism of a linear joint provided in this application;

[0032] Figure 2 This is a cross-sectional view of a linear joint provided in this application;

[0033] Figure 3 This is a schematic diagram of the separate structures of the ball screw pair and the ball spline pair provided in this application. Detailed Implementation

[0034] In this application, the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and other terms indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to describe the relative positional relationship between the components or parts and do not specifically limit the specific installation orientation of each component or part.

[0035] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0036] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0037] Furthermore, the structures, proportions, sizes, etc., drawn in the accompanying drawings of this application are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modification to the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application.

[0038] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] Please see Figures 1 to 3 This application provides a first aspect of a linear joint, comprising: a motor assembly 10, a ball screw assembly 20, a push rod assembly 30, a joint housing 70, and a connecting component; the motor assembly 10 and the ball screw assembly 20 are both disposed in the joint housing 70; the lead screw 21 in the ball screw assembly 20 is placed in the cavity of the rotor back iron 12 of the motor assembly 10, and an internal circulation lead screw nut 22 is placed on the lead screw 21, the internal circulation lead screw nut 22 being connected to the rotor back iron 12 to form a rolling element; the lead screw 21 is connected to the push rod assembly 30, the push rod assembly 30 is connected to the connecting component, and the connecting component is used to connect to an external device; the rotor back iron 12 is used to drive the lead screw nut 22 to rotate, the rotational motion of the lead screw nut 22 drives the lead screw 21 to move axially, and the lead screw 21 is used to drive the push rod assembly 30 to perform linear motion.

[0040] First, let me introduce the functions and roles of each component in this application:

[0041] Motor assembly 10: As the power source of the entire linear joint, it provides rotational power. The rotor in the motor assembly 10 generates rotational torque after being energized. The rotational torque is the basis for driving the movement of the entire linear joint. The rotor back iron 12, as part of the rotor, not only supports the rotor structure, but also provides a cavity for receiving the internal circulation screw nut 22 and screw screw 21 in the ball screw pair 20.

[0042] Ball screw assembly 20: Converts the rotary motion of the motor into linear motion. The lead screw 21, as the moving part of the ball screw assembly 20, has helical grooves machined on its surface to engage with the balls in the internally circulating lead screw nut 22, thus achieving the conversion from rotary motion to linear motion. The internally circulating lead screw nut 22 contains balls that circulate and roll within the nut, reducing friction and wear and improving transmission efficiency. The nut is connected to the rotor back iron 12, forming a rolling element that rotates with the rotor.

[0043] The push rod assembly 30 transmits linear motion to achieve the extension or retraction of the joint. The push rod assembly 30 is connected to the lead screw 21. When the lead screw 21 moves axially, the push rod assembly 30 also moves accordingly, thereby realizing the extension or retraction function of the linear joint.

[0044] Joint housing 70: Used to support and protect the internal components of the joint. Joint housing 70 provides mounting space for motor assembly 10, ball screw assembly 20, and push rod assembly 30, and protects these components from interference and damage from the external environment. At the same time, the housing also plays a role in fixing and positioning, ensuring the stability and reliability of the joint during operation.

[0045] Working principle of linear joints:

[0046] When the motor assembly 10 is powered on, the rotor generates rotational torque. This torque is transmitted to the internal circulation screw nut 22 through the rotor back iron 12. The internal circulation screw nut 22 starts to rotate under the drive of the rotor. The balls inside it cooperate with the helical groove of the screw nut 21 to convert the rotational motion into the axial movement of the screw nut 21. During the axial movement, the screw nut 21 transmits the motion to the push rod assembly 30. The push rod assembly 30 then performs linear motion to realize the extension or retraction of the joint.

[0047] Therefore, it can be seen that the linear joint of this application is powered by the motor assembly 10, the ball screw pair 20 converts the rotational motion into linear motion, the push rod assembly 30 transmits the linear motion, and the joint housing 70 supports and protects the internal components, thus achieving efficient, stable, and reliable linear motion output. Furthermore, it reduces the need for external space, thereby helping to reduce the outer diameter of the linear joint. The slender motor stator 11, while ensuring motor performance, also minimizes the motor's size and weight, further controlling the overall size of the joint, making the linear joint more compact and lightweight.

[0048] Optionally, the motor assembly 10 includes a motor stator 11, a rotor back iron 12, and a motor magnet 13; the motor stator 11 is disposed inside the motor housing 71 in the joint housing 70 and is fixedly connected to the inside of the motor housing 71; the rotor back iron 12 is disposed inside the motor stator 11 and has an internal cavity for placing the lead screw 21; the motor magnet 13 is disposed between the motor stator 11 and the rotor back iron 12 and is connected to the outer surface of the rotor back iron 12.

[0049] In this embodiment, the motor stator 11 is an elongated stator that is fixed inside the motor housing 71. It can be securely connected to the motor housing 71 by adhesive or other fixing methods. No specific limitation is made here, and it can be set according to the actual situation.

[0050] The motor stator 11 is the stationary part of the motor assembly 10. When energized, the windings generate a magnetic field, which interacts with the magnetic fields generated by the rotor back iron 12 and the motor magnet 13, thereby generating rotational torque. The rotor back iron 12 is located inside the motor stator 11, and an internal cavity is provided on the rotor back cavity. The internal cavity is used to house the lead screw 21 and provides space for the axial extension and retraction of the lead screw.

[0051] The motor magnet 13 is disposed between the motor stator 11 and the rotor back iron 12. The motor magnet 13 is fixed to the outer surface of the rotor back iron 12 with glue. The motor magnet 13 can be single-segment or multi-segment. No specific limitation is made in this application. It can be set according to the actual situation. The motor magnet 13 can provide a permanent magnet field, which interacts with the magnetic field generated by the stator winding to generate a rotational torque.

[0052] The slender dimensions of the motor assembly 10 make full use of the axial space of the linear joint, reduce the radial dimension of the linear joint, and increase the contact area between the motor stator 11 and the motor housing 71, which is beneficial for the rapid heat dissipation of the motor.

[0053] Specifically, in practical applications, when the motor assembly 10 is energized, the windings in the motor stator 11 generate a rotating magnetic field. This rotating magnetic field interacts with the permanent magnet magnetic field formed by the motor magnet 13 and the rotor back iron 12, generating a magnetic torque. Under the action of the magnetic torque, the rotor back iron 12 begins to rotate. Since the rotor back iron 12 is connected to the internal circulation type lead screw nut 22, the rotation of the rotor back iron 12 will drive the lead screw nut 22 to rotate. The rotational motion of the lead screw nut 22 is converted into the axial movement of the lead screw nut 21 through the cooperation of the ball bearings and the lead screw 21. Finally, the axial movement of the lead screw nut 21 is transmitted to the push rod assembly 30 to realize the extension or retraction of the linear joint.

[0054] Optionally, the internal circulation screw nut 22 on the ball screw assembly 20 is coaxially connected with the rotor back iron 12 to form the rolling element, and the screw nut 22 and the rotor back iron 12 are fixed by glue or interference fit.

[0055] In this embodiment, coaxial connection means that the central axis of the internal circulation screw nut 22 is completely coincident with the central axis of the rotor back iron 12. Through coaxial connection, it can be ensured that the rotational torque will not generate eccentric force during transmission, thereby reducing vibration and improving the smoothness and accuracy of transmission.

[0056] The internal circulation screw nut 22 is bonded to the rotor back iron 12 with glue, which ensures a firm connection between the two. The glue connection is simple and convenient to operate and can maintain good coaxiality.

[0057] Alternatively, it can be fixed by interference connection. Interference connection is a way to achieve a tight connection by interfering with the fit between parts. To achieve interference connection between the lead screw nut 22 and the rotor back iron 12, the outer diameter of the internal circulation lead screw nut 22 must be larger than the inner diameter of the rotor back iron 12. The two can be tightly joined together by press fitting. The advantages of interference connection are high connection strength and good impact and vibration resistance.

[0058] Optionally, a pair of double-row angular contact ball bearings 5 ​​are installed at the positioning end of the rolling element. The inner ring of the double-row angular contact ball bearing 5 is fixed to the outer surface of the lead screw nut 22. The outer ring of the double-row angular contact ball bearing 5 is provided with external threads. The double-row angular contact ball bearing 5 is connected to the locking nut 51 through the external threads. The locking nut 51 is used to pre-tighten the inner ring of the double-row angular contact ball bearing 5.

[0059] In the embodiments of this application, the double-row angular contact ball bearing 5 is a bearing capable of withstanding combined radial and axial loads, capable of simultaneously withstanding axial forces from two directions, and possessing high rigidity and precision.

[0060] In the linear joint of this application, the double-row angular contact ball bearing 5 is installed at the positioning end of the rolling element. Its function is to support and position the lead screw nut 22, and at the same time bear the radial and axial loads transmitted by the lead screw nut 22, so as to ensure the stability and accuracy of the rolling element during rotation.

[0061] The inner ring of the double-row angular contact ball bearing 5 is fixed to the outer surface of the lead screw nut 22, which ensures a tight connection between the inner ring of the double-row angular contact ball bearing 5 and the lead screw nut 22, so that the double-row angular contact ball bearing 5 can accurately transmit the rotational motion of the lead screw nut 22.

[0062] The outer ring of the double-row angular contact ball bearing 5 is provided with external threads. The external threads are provided to cooperate with the lock nut 51, so that the lock nut 51 can be tightened on the outer ring of the bearing to achieve preload on the inner ring of the bearing.

[0063] Therefore, in the linear joint of this application, by installing a pair of double-row angular contact ball bearings 5 ​​at the positioning end of the rolling element and pre-tightening the inner ring of the bearing by locking nut 51, the rigidity and stability of the linear joint can be effectively improved, ensuring the accuracy and reliability of the rolling element during rotation.

[0064] Optionally, a thin deep groove ball bearing 6 is installed at the floating end of the rolling element. The inner ring of the thin deep groove ball bearing 6 is fixed to the outer end of the rotor back iron 12 shaft. The outer ring of the thin deep groove ball bearing 6 is connected to the wave spring 61.

[0065] In this embodiment, the thin deep groove ball bearing 6 is installed at the floating end of the rolling element, which serves to support and position it, and can withstand radial and a certain degree of axial load, ensuring the stability and accuracy of the rolling element during operation.

[0066] The inner ring of the thin deep groove ball bearing 6 is fixed to the outer end of the rotor back iron 12 shaft, which means that when the rotor back iron 12 rotates, it will drive the inner ring of the bearing to rotate together, and then transmit the motion to the outer ring through the bearing.

[0067] The outer ring of the thin deep groove ball bearing 6 is not directly fixed to the joint housing 70 or other fixed parts, but is connected to the wave spring 61. By connecting to the wave spring 61, the concentricity of the rolling elements and the motor stator 11 can be better guaranteed, and the radial runout of the rotor back iron 12 shaft extension end can be reduced.

[0068] Optionally, the push rod assembly 30 is a ball spline pair, which includes a push rod 31 and a spline sleeve 32. The push rod 31 is provided with a groove 313, which is axially arranged. The spline sleeve 32 is connected to the groove 313 through a steel ball to enable the push rod 31 to perform linear movement. The spline sleeve 32 is installed at the concentric inner circle of the front end cover 72 in the joint housing 70. The front end cover 72 is provided with a concentric boss 721, and the front end cover 72 is connected to the inner circle of the motor housing 71 through the concentric boss 721.

[0069] In this embodiment, the push rod 31 is the main moving part of the ball spline pair. Its surface is provided with a groove 313 along the axial direction. The groove 313 cooperates with the steel ball of the spline sleeve 32, so that the push rod 31 can make linear motion. Moreover, because it is rolling friction, the frictional force generated by the relative motion is very small. The torque of the push rod 31 can be transmitted by fixing the spline sleeve 32, thereby achieving the purpose of preventing the push rod 31 from rotating.

[0070] The spline sleeve 32 is fitted onto the push rod 31, and a steel ball is installed inside the spline sleeve 32. The steel ball rolls between the groove 313 of the spline sleeve 32 and the push rod 31, which reduces friction and ensures the accuracy and stability of the transmission. The groove 313 on the push rod 31 is axially oriented, and the rolling contact between the steel ball on the spline sleeve 32 and the groove 313 of the push rod 31 greatly reduces frictional resistance and improves transmission efficiency. Furthermore, the steel ball can withstand certain radial and axial loads, enhancing the load-bearing capacity of the push rod assembly 30.

[0071] The spline sleeve 32 can be installed on the concentric inner circle of the front cover 72 in the joint housing 70. A concentric boss 721 is provided on the front cover 72. The concentric boss 721 is used to fit and connect with the inner circle of the motor housing 71. Through the fitting and connection between the concentric boss 721 and the inner circle of the motor housing 71, the front cover 72 is firmly fixed on the motor housing 71, thereby ensuring the stable installation and accurate positioning of the spline sleeve 32.

[0072] Setting the push rod assembly 30 as a ball spline pair not only achieves efficient transmission of linear motion but also improves the accuracy and stability of the transmission. Meanwhile, the spline sleeve 32, through the fitting connection between the front end cover 72 and the motor housing 71, ensures the stable installation and accurate positioning of the entire push rod assembly 30 within the joint housing 70.

[0073] Optionally, the upper end of the push rod 31 is provided with a concentric blind hole 311, the lower part of the concentric blind hole 311 is provided with an internal thread 312, the lower end of the lead screw 21 is provided with an external screw 211 with a diameter smaller than the outer circle of the lead screw and a positioning plane 213, and the external screw 211 is provided with a smooth rod portion 212.

[0074] In this embodiment, the upper end of the push rod 31 is provided with a concentric blind hole 311, which is concentric with the axis of the push rod 31 to ensure alignment and stability during connection. The concentric blind hole 311 is used to accommodate the lower end of the lead screw 21, providing space for the connection between the two. An internal thread 312 is provided in the lower part of the concentric blind hole 311. The internal thread 312 in the concentric blind hole 311 cooperates with the external screw 211 at the lower end of the lead screw 21. By rotating the lead screw 21, it can be firmly fixed on the push rod 31, realizing the connection between the push rod 31 and the lead screw 21.

[0075] An external screw 211 with a diameter smaller than the outer circle of the lead screw 21 is provided at the lower end of the lead screw 21. The external screw 211 is used to cooperate with the internal thread 312 in the concentric blind hole 311 of the push rod 31. A positioning plane 213 is provided below the external screw 211. The positioning plane 213 is used to ensure the correct positional relationship between the lead screw 21 and the push rod 31 during connection and to prevent relative rotation or offset.

[0076] The push rod 31 is provided with a locking flat part 314, and the end face of the ball screw is provided with a cross groove 214. The two work together to ensure that the threaded connection reaches the required locking torque. The push rod 31 is made of light alloy material to reduce weight.

[0077] Specifically, during connection, first insert the lower end of the lead screw 21 into the concentric blind hole 311 of the push rod 31, ensuring that the positioning plane 213 is aligned with the corresponding part of the push rod 31. Then rotate the lead screw 21 so that the thread on the outer screw 211 engages with the internal thread 312 in the concentric blind hole 311 of the push rod 31, gradually tightening the connection between the two. Through the threaded connection and the engagement of the positioning plane 213, a stable connection and reliable transmission between the push rod 31 and the lead screw 21 can be ensured.

[0078] Optionally, the two ends of the lead screw 21 are provided with an upper limit plate 23 and a lower limit plate 24. The upper limit plate 23 is fixed to the rear end face of the lead screw 21 by screws 25, and the lower limit plate 24 is embedded in the smooth rod portion 212 of the lead screw 21 and fixed to the positioning plane 213 of the lead screw 21 by a fixing push rod 31.

[0079] In this embodiment, the upper limit plate 23 is installed on the rear end face of the lead screw 21. This fixing method ensures the stability of the upper limit plate 23 and prevents it from loosening or falling off during the movement of the lead screw 21. When the lead screw 21 moves downward, the upper limit plate 23 can contact the upper end face of the lead screw nut 22, thereby blocking the further downward movement of the lead screw 21 and preventing the lead screw 21 from disengaging from the lead screw nut 22.

[0080] The lower limit plate 24 is a hollow disc-shaped block, embedded in the smooth part 212 of the lead screw, and fixed to the positioning plane 213 of the lead screw 21 by the fixing push rod 31. When the ball screw moves upward, the lower limit plate 24 can contact the lower end face of the lead screw nut 22, thereby blocking the further upward movement of the lead screw 21 and preventing the lead screw from disengaging from the lead screw nut 22.

[0081] It should be noted that in specific applications, the lower limit plate 24 can also be replaced by a shaft elastic retaining ring.

[0082] Optionally, the linear joint further includes an encoder assembly 40, which is disposed at one end of the rolling element and is used to convert the angular displacement of the rolling element into an electrical signal.

[0083] In this embodiment, to accurately control the extension and retraction of the push rod 31, the linear joint further includes an encoder assembly 40. The encoder assembly 40 is disposed at one end of the rolling element and is used to convert the angular displacement of the rolling element into an electrical signal and feed it back to the motor driver. The motor driver can output control commands to the motor according to the current angle of the rolling element to adjust and correct the output angle of the shaft. In specific applications, the encoder can be a photoelectric encoder, a magnetoelectric encoder, etc.

[0084] Preferably, in this embodiment of the application, the encoder is a magnetic encoder, with a concentric step provided at the shaft extension end of the rotor back iron 12. The magnet 41 is concentrically fixed to the adapter 42 by glue, and the adapter 42 is concentrically fixed to the concentric step of the rotor back iron 12 by glue to ensure the concentricity of the magnet 41 and the rolling element. The encoder stationary disk 43 is installed on the mounting plane of the motor housing 71.

[0085] Therefore, by introducing the encoder assembly 40 into the linear joint, accurate measurement and conversion of the rolling element angular displacement can be achieved, providing support for the precise positioning, closed-loop control and condition monitoring of the linear joint, thereby making the linear joint more performant.

[0086] Optionally, the linear joint further includes a tension / compression sensor 8, which is electrically connected to the motor driver. One end of the tension / compression sensor 8 is connected to the rear end cover 73 in the joint housing 70 via an external thread. The rear end cover 73 is connected to the motor housing 71 via screws 25.

[0087] In this embodiment of the application, in order to accurately control the extension and retraction of the push rod 31, the linear joint also includes a tension and compression sensor 8. Both ends of the tension and compression sensor 8 are provided with external threads. One end of the sensor is connected to the rear end cover 73, which is fixed to the motor housing 71 by screws 25, thereby connecting to the fixed end of the linear joint. The sensor is used to detect the axial force borne by the linear joint. The tension and compression sensor 8 is also electrically connected to the motor driver.

[0088] By integrating the tension and compression sensor 8 into the linear joint, and connecting the rear end cover 73 to the motor housing 71 via external thread and screw 25, forces in both directions on the joint can be detected, enabling real-time monitoring and control of the pressure.

[0089] Optionally, the linear joint further includes a rod end bearing 90, which is connected and fixed to the push rod 31 and the tension / compression sensor 8, respectively.

[0090] In this embodiment, the telescopic end and the fixed end of the linear joint are also provided with rod end bearings 90. The rod end bearings 90 integrate an integral connecting rod 91 and a joint bearing 92. The connecting rod 91 is provided with an internal thread 312. The telescopic end of the linear joint is fixedly connected to the end of the push rod 31 by an external thread, and the fixed end of the linear joint is fixedly connected to the tension and compression sensor 8 by an external thread.

[0091] In particular, the locking depth and fixing angle of the rod end bearing 90 can be adjusted at the telescopic end of the linear joint by using a thin external hexagonal nut 93. When the rod end bearings 90 are used in pairs, they can ensure that the telescopic end and the fixed end of the linear joint form a hinge, thereby minimizing the bending moment that the linear joint may bear, which could cause the push rod 31 to bend.

[0092] The second aspect of this application provides a humanoid robot, which is equipped with linear joints as described in the first aspect and any one of the first aspects.

[0093] It should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A linear joint, characterized in that, include: Motor assembly, ball screw pair, push rod assembly, joint housing and connecting parts; Both the motor assembly and the ball screw pair are disposed in the joint housing; The ball screw in the ball screw assembly is placed in the cavity of the rotor back iron of the motor assembly. An internal circulation ball screw nut is placed on the ball screw, and the internal circulation ball screw nut is connected to the rotor back iron to form a rolling element. The lead screw is connected to the push rod assembly, the push rod assembly is connected to the connecting component, and the connecting component is used to connect to external equipment; The rotor back iron is used to drive the lead screw nut to rotate, the rotation of the lead screw nut drives the lead screw to move axially, and the lead screw drives the push rod assembly to move linearly.

2. The linear joint according to claim 1, characterized in that, The motor assembly includes a motor stator, a rotor back iron, and motor magnets; The motor stator is disposed inside the motor housing within the joint housing and is fixedly connected to the inside of the motor housing. The rotor back iron is disposed inside the motor stator, and the rotor back iron is provided with an internal cavity for placing the lead screw. The motor magnet is disposed between the motor stator and the rotor back iron, and the motor magnet is connected to the outer surface of the rotor back iron.

3. The linear joint according to claim 2, characterized in that, The inner circulation screw nut on the ball screw assembly is coaxially connected to the rotor back iron to form the rolling element. The screw nut and the rotor back iron are fixed by glue or interference fit.

4. The linear joint according to claim 3, characterized in that, The locating end of the rolling element is equipped with a pair of double-row angular contact ball bearings. The inner ring of the double-row angular contact ball bearing is fixed to the outer surface of the lead screw nut. The outer ring of the double-row angular contact ball bearing is provided with external threads. The double-row angular contact ball bearing is connected to the lock nut through the external threads. The lock nut is used to pre-tighten the inner ring of the double-row angular contact ball bearing.

5. The linear joint according to claim 3, characterized in that, The floating end of the rolling element is equipped with a thin deep groove ball bearing. The inner ring of the thin deep groove ball bearing is fixed to the outer extension end of the rotor back iron shaft. The outer ring of the thin deep groove ball bearing is connected to a wave spring.

6. The linear joint according to claim 2, characterized in that, The push rod assembly is a ball spline pair, which includes a push rod and a spline sleeve. The push rod has a groove that is axially oriented. The spline sleeve is connected to the groove through a steel ball so that the push rod can move linearly. The spline sleeve is installed on the concentric inner circle of the front end cover in the joint housing. The front end cover is provided with a concentric boss, and the front end cover is connected to the inner circle of the motor housing through the concentric boss.

7. The linear joint according to claim 6, characterized in that, The upper end of the push rod is provided with a concentric blind hole, the lower part of the concentric blind hole is provided with an internal thread, the lower end of the lead screw is provided with an external screw with a diameter smaller than the outer circle of the lead screw and a positioning plane, and the external screw is provided with a smooth rod part.

8. The linear joint according to claim 7, characterized in that, The lead screw is provided with an upper limit plate and a lower limit plate at both ends. The upper limit plate is fixed to the rear end face of the lead screw by screws. The lower limit plate is embedded in the smooth part of the lead screw and is fixed to the positioning plane of the lead screw by a fixing push rod.

9. The linear joint according to claim 3, characterized in that, The linear joint also includes an encoder assembly disposed at one end of the rolling element, the encoder assembly being used to convert the angular displacement of the rolling element into an electrical signal.

10. The linear joint according to claim 6, characterized in that, The linear joint also includes a tension / compression sensor, which is electrically connected to the motor driver. One end of the tension / compression sensor is connected to the rear end cover in the joint housing via an external thread, and the rear end cover is connected to the motor housing via screws.

11. The linear joint according to claim 10, characterized in that, The linear joint also includes a rod end bearing, which is connected and fixed to the push rod and the tension / compression sensor respectively.

12. A humanoid robot, characterized in that, The humanoid robot is equipped with linear joints as described in any one of claims 1 to 11.

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