Linear actuator and robot hand

Abstract

The utility model discloses a linear actuator and manipulator relates to robot technical field, wherein, linear actuator includes casing and two drive mechanisms, and each drive mechanism contains the drive shaft who is movable along the first direction and is worn in the one end of casing, rotary motor and transmission mechanism. Transmission mechanism includes silk 1 rod transmission structure, including the screw rod of rotatable installation in casing and the drive nut of screwing with it, and drive nut connects drive shaft to realize linear motion. The actuator is equipped with the limiting structure between drive shaft and casing still, and limiting structure is close to output end setting, directly bears lateral force and bending moment of eccentric load generation, provides independent linear guide for drive shaft and restricts its radial displacement, to resist external overturning moment, make the movement track of drive shaft be restricted, and external load avoids the additional bending stress of screw rod and drive nut bearing, reduces the partial contact pressure of screw pair and the risk of partial load engagement, reduces motion jam.

Description

Technical Field

[0001] This utility model relates to the field of robotics technology, and in particular to a linear actuator and a robotic arm. Background Technology

[0002] In biomimetic robotic hands, linear actuators drive cranks via linkages, hinges, and other mechanisms. Often, eccentric loads generate overturning moments, causing the lead screw nut, linear bearings, and other moving parts to bear combined loads of axial, radial forces, and bending moments. Over long-term operation, this can easily lead to asymmetric wear and stress concentration, resulting in decreased motion accuracy, sluggish response, and a significantly shortened service life.

[0003] The current lack of assessment of overturning moment during the design phase leads to redundant design and failure risks, making it difficult to achieve a balance between performance and reliability, and hindering the development of bionic robotic arms towards high precision and long lifespan. Therefore, there is an urgent need to develop a compact and highly integrated linear actuator that can effectively integrate multiple drive axes to meet multi-degree-of-freedom drive requirements while significantly improving its ability to resist overturning moments. Utility Model Content

[0004] The main purpose of this invention is to propose a linear actuator and a robotic arm, which aims to reduce the influence of overturning forces on existing linear actuators and reduce the constraints on the high precision and high reliability of robotic arms.

[0005] To achieve the above objectives, the linear actuator proposed in this utility model includes:

[0006] case;

[0007] Two drive mechanisms, each drive mechanism comprising:

[0008] A drive shaft passes through one end of the housing in the first direction and is movably disposed along the first direction;

[0009] A rotary electric motor having a rotating shaft; and,

[0010] A transmission mechanism is provided to drive the rotating shaft and the drive shaft. The transmission mechanism includes a lead screw transmission structure, which includes a lead screw rotatably installed in the housing and a drive nut threadedly engaged with the lead screw. The drive nut is connected to the drive shaft to drive the drive shaft to move.

[0011] The linear actuator further includes a limiting structure located between the drive shaft and the housing. The limiting structure provides independent linear guidance for the drive shaft and constrains its radial displacement to resist the overturning torque applied to the linear actuator.

[0012] In one embodiment, each of the limiting structures includes a linear guide support structure, the linear guide support structure comprising:

[0013] A guide portion, extending along the first direction, is fixedly installed within the housing; and,

[0014] A support portion is slidably mounted on the guide portion along the first direction, and the support portion is fixedly connected to the corresponding drive shaft.

[0015] In one embodiment, the drive shaft has a guide hole extending along the first direction at one end located inside the housing;

[0016] One end of the lead screw is provided with a bearing structure, the inner ring of the bearing structure cooperates with the lead screw, and the outer ring of the bearing structure is fixedly installed in the housing;

[0017] The other end of the lead screw is sleeved in the guide hole and is movably disposed relative to the circumference of the drive shaft and the first direction.

[0018] In one embodiment, each of the lead screws is a ball screw, a planetary roller screw, or a trapezoidal screw.

[0019] In one embodiment, the drive shafts of the two drive mechanisms are arranged side by side in the second direction, the two limiting structures are arranged at intervals in the second direction, and the rotary motors of the two drive mechanisms are arranged side by side in the third direction.

[0020] The first direction, the second direction, and the third direction are all mutually perpendicular:

[0021] The two transmission mechanisms are arranged in a centrally symmetrical manner with respect to an axis that passes through the midpoint of the line connecting the two rotary motor axes and is parallel to the rotary motor axes; and / or,

[0022] The midpoint of the line connecting the two rotating motor axes coincides with the midpoint of the line connecting the two drive shaft axes.

[0023] In one embodiment, the output forces of the drive shafts of the two drive mechanisms are set differently.

[0024] In one embodiment, each of the transmission mechanisms further includes a reduction transmission structure, wherein the transmission ratio of the reduction transmission structure and / or the lead of the lead screw are set differently between the two drive mechanisms to achieve a difference in the output force of the drive shaft.

[0025] In one embodiment, each of the transmission mechanisms further includes a reduction transmission structure, which includes an input gear, an output gear, and a transmission gear. The input gear is coaxially arranged with the output shaft of the rotary motor, and the output gear is coaxially connected with the lead screw.

[0026] The transmission gear has a first tooth portion and a second tooth portion, the first tooth portion meshing with the input gear, the second tooth portion meshing with the output gear, and the diameter of the first tooth portion of the transmission gear is larger than the diameter of its second tooth portion.

[0027] In one embodiment, the output axis of the rotary motor of each drive mechanism is aligned with the rotation axis of the transmission gear in a second direction.

[0028] In one embodiment, each of the rotary motors is a coreless motor, an axial flux motor, or a torque motor.

[0029] This utility model also proposes a robotic arm, which includes a linear actuator, the linear actuator comprising:

[0030] case;

[0031] Two drive mechanisms, each drive mechanism comprising:

[0032] A drive shaft passes through one end of the housing in the first direction and is movably disposed along the first direction;

[0033] A rotary electric motor having a rotating shaft; and,

[0034] A transmission mechanism is provided to drive the rotating shaft and the drive shaft. The transmission mechanism includes a lead screw transmission structure, which includes a lead screw rotatably installed in the housing and a drive nut threadedly engaged with the lead screw. The drive nut is connected to the drive shaft to drive the drive shaft to move.

[0035] The linear actuator further includes a limiting structure located between the drive shaft and the housing. The limiting structure provides independent linear guidance for the drive shaft and constrains its radial displacement to resist the overturning torque applied to the linear actuator.

[0036] The technical solution provided by this utility model has at least the following advantages:

[0037] By setting an independent limiting structure between the drive shaft and the housing, the external lateral force and overturning moment on the drive shaft are absorbed and constrained in advance, thereby preventing the load from being transmitted to the lead screw and drive nut, reducing the additional bending stress and local contact pressure of the threaded pair, and reducing the risk of jamming. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0039] Figure 1 A schematic diagram of the structure of an embodiment of the linear actuator provided by this utility model;

[0040] Figures 2 to 4 for Figure 1 A partial structural diagram of a linear actuator;

[0041] Figure 5 for Figure 1 A cross-sectional schematic diagram of a linear actuator;

[0042] Figure 6 This is a bottom view of the drive unit in a linear actuator.

[0043] Explanation of icon numbers:

[0044] 100. Linear actuator; 10. Housing; 20. Drive mechanism; 21. Drive shaft; 21a. Guide hole; 22. Rotary motor; 23. Transmission mechanism; 231. Lead screw transmission structure; 2311. Lead screw; 2312. Drive nut; 232. Reduction transmission structure; 2321. Input gear; 2322. Output gear; 2323. Transmission gear; 23231. First tooth; 23232. Second tooth; 30. Limiting structure; 31. Guide part; 32. Support part; 4. Bearing structure.

[0045] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0046] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0047] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0048] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0049] This invention proposes a linear actuator, aiming to reduce the influence of overturning force on existing linear actuators, which restricts the high precision and high reliability performance of robotic arms.

[0050] Please see Figures 1 to 3 In one embodiment of this utility model, the linear actuator 100 includes a housing 10 and two drive mechanisms 20. Each drive mechanism 20 includes a drive shaft 21, a rotary motor 22, and a transmission mechanism 23. The drive shaft 21 passes through one end of the housing 10 in a first direction and is movably arranged along the first direction. The rotary motor 22 has a rotating shaft. The transmission mechanism 23 drivesly connects the rotating shaft and the drive shaft 21. The transmission mechanism 23 includes a lead screw transmission structure 231, which includes a... A lead screw 2311 and a drive nut 2312 threadedly engaged with the lead screw 2311 are rotatably installed inside the housing 10. The drive nut 2312 is connected to the drive shaft 21 to drive the drive shaft 21 to move. The linear actuator 100 also includes a limiting structure 30, which is located between the drive shaft 21 and the housing 10. The limiting structure 30 provides independent linear guidance for the drive shaft 21 and constrains its radial displacement to resist the overturning torque applied to the linear actuator 100.

[0051] Understandably, the housing 10 serves as an integral support structure for mounting various functional components. Two drive mechanisms 20 are arranged symmetrically or side-by-side within the housing 10. The drive shaft 21 of each drive mechanism 20 passes through one end of the housing 10 in a first direction and performs linear reciprocating motion along that direction. The output end of the drive shaft 21 can be hinged to the first and second cranks of the bionic robotic hand to drive different finger joints to achieve flexion and extension movements. A rotary motor 22 provides power output, and its rotation shaft is coupled to the drive shaft 21 through a transmission mechanism 23. The transmission mechanism 23 includes a lead screw transmission structure 231, with the lead screw 2311 rotatably mounted within the housing 10. A drive nut 2312 is threadedly engaged with the lead screw 2311 and fixedly connected to the drive shaft 21, converting the rotational motion into linear motion of the drive shaft 21.

[0052] A limiting structure 30 is disposed between the drive shaft 21 and the housing 10, independent of the lead screw transmission structure 231, to provide precise linear guidance for the drive shaft 21 and constrain its displacement in the radial plane. This structure can take the form of a linear bearing, sliding guide sleeve, ball bearing guide post, or guide slider, and is mounted on the housing 10 and slides in contact with the outer periphery of the drive shaft 21. The guide path extends along a first direction, ensuring the linearity of the drive shaft 21's movement trajectory.

[0053] When an external eccentric load is applied to the output end of the drive shaft 21, the line of action of the force deviates from the axis of the first direction, forming a radial component perpendicular to the axis and a torque component rotating around a certain fulcrum of the axis, i.e., overturning moment. The overturning force can be transmitted inward along the drive shaft 21 to the threaded engagement area between the drive nut 2312 and the lead screw 2311. Since the lead screw 2311 is mainly designed to withstand axial thrust and torque, its slender structure is prone to elastic deformation when subjected to additional bending moment, leading to localized contact and stress concentration on the thread flanks, which in turn causes motion stagnation, increased wear, and even seizing.

[0054] The limiting structure 30 is rigidly connected to the housing 10 and is independent of the lead screw 2311 transmission system, serving as the radial load-bearing path for the drive shaft 21. When an eccentric load is applied, the radial component of the force is directly borne by the guide surface or rolling element of the limiting structure 30 and transmitted to the external mounting base through the housing 10. Simultaneously, the overturning moment generates a reaction couple at the limiting structure 30, with its lever arm based on the support point of the limiting structure 30, effectively counteracting the external bending moment. Because the limiting structure 30 is located near the output end of the drive shaft 21, away from the internal lead screw 2311 and drive nut 2312, most of the lateral loads are isolated before entering the transmission system, thus preventing the bending moment and radial force from being transmitted to the drive nut 2312 and lead screw 2311, ensuring that the threaded pair is in an ideal working state where axial force is dominant.

[0055] By setting an independent limiting structure 30 between the drive shaft 21 and the housing 10, the external lateral force and overturning moment on the drive shaft 21 are absorbed and constrained in advance, thereby preventing the load from being transmitted to the lead screw 2311 and the drive nut 2312, reducing the additional bending stress and local contact pressure of the threaded pair, and reducing the risk of jamming.

[0056] Specifically, please refer to Figures 3 to 5 In this embodiment, each of the limiting structures 30 includes a linear guide support structure, which includes a guide portion 31 and a support portion 32. The guide portion 31 extends along the first direction and is fixedly installed inside the housing 10. The support portion 32 is slidably installed on the guide portion 31 along the first direction, and the support portion 32 is fixedly connected to the corresponding drive shaft 21.

[0057] The linear guide support structure includes a linear guide pair, a splined bushing, or a sliding bearing. The guide portion 31 extends along the first direction and serves as a motion reference. It is fixed inside the housing 10 by interference fit, screw fastening, or pressure cap to ensure that it does not shift or loosen when subjected to radial loads.

[0058] The guide section 31 can adopt a precision guide rail, guide shaft, slide groove, or rib structure with high dimensional accuracy. Its cross-sectional shape can be rectangular, circular, V-shaped, or dovetail-shaped, and the specific form is determined according to the load-bearing characteristics and spatial layout. The support section 32 is slidably mounted on the guide section 31 to form a sliding or rolling engagement with it.

[0059] The support portion 32 is rigidly connected to the drive shaft 21 and moves synchronously with the drive shaft 21. The support portion 32 can be a linear bearing, slider, sleeve, or integrated ball / roller guide assembly, and its inner surface forms a low-friction kinematic pair with the outer periphery of the guide portion 31. High-precision guidance is achieved for rolling fits through preload or clearance adjustment, while sliding fits can use self-lubricating materials or surface treatment processes to reduce the wear rate.

[0060] It should also be noted that the fit tolerance and preload between the guide part 31 and the support part 32 can be adjusted according to the actual working conditions to balance motion flexibility and structural rigidity. This specification does not limit the specific implementation of the linear guide support structure, as long as it can provide independent guidance for the drive shaft 21 and constrain radial displacement, it falls within the scope of protection of this solution.

[0061] By setting a linear guide support structure consisting of a guide part 31 and a support part 32, the movement of the drive shaft 21 is precisely limited in the first direction. The external radial force and overturning moment are directly borne and transmitted to the housing 10 by this structure, thereby effectively isolating the transmission of lateral loads to the internal lead screw 2311 and drive nut 2312, and avoiding local contact, jamming or premature wear of the threaded pair due to the superposition of bending stress.

[0062] Specifically, please refer to Figure 5 In this embodiment, the drive shaft 21 has a guide hole 21a extending in a first direction at one end inside the housing 10. This hole is a through hole or a blind hole with a smooth inner wall surface, used to accommodate the free end of the lead screw 2311. One end of the lead screw 2311 is rotatably mounted on the housing 10 via a bearing structure 4. The inner ring of the bearing structure 4 engages with the outer circumference of the lead screw 2311, and the outer ring is fixed in the mounting seat of the housing 10 to form a fixed support end.

[0063] It should be noted that the bearing can be a deep groove ball bearing, an angular contact ball bearing, or a combination bearing, with the specific type selected based on the load direction and rotational accuracy requirements. The other end of the lead screw 2311 extends into the guide hole 21a of the drive shaft 21, maintaining axial and circumferential clearances between it and the guide hole 21a to form a floating connection.

[0064] With this configuration, the free end of the lead screw 2311 can have a small displacement in the axial direction and a slight floating in the circumferential direction to accommodate assembly errors or thermal expansion, while not transmitting torque.

[0065] Because the drive shaft 21 obtains precise linear guidance through the limiting structure 30, its motion trajectory is stable and its axial position is effectively constrained. Under these conditions, the rotation axis of the lead screw 2311 is jointly determined by the bearing structure 4 at the fixed end and the guide path of the drive shaft 21. The bearing structure 4 can radially position the proximal end of the lead screw 2311, and the guide hole 21a of the drive shaft 21 provides guidance for the distal end of the lead screw 2311; the two constitute a dual-redundant positioning system. When an external overturning moment acts on the drive shaft 21, the limiting structure 30 bears the main lateral load, preventing the drive shaft 21 from deflecting, thereby maintaining the axial stability of the guide hole 21a and indirectly ensuring the positional accuracy of the distal end of the lead screw 2311.

[0066] With one end of the lead screw 2311 fixed and the other end floating in the guide hole 21a of the drive shaft 21, and in combination with the bearing structure 4 and the limiting structure 30, the lead screw 2311 has good dynamic coaxiality during operation, which can reduce the eccentric meshing with the drive nut 2312, reduce the additional stress and uneven friction of the threaded pair, and improve the resistance to overturning moment.

[0067] It is understood that multiple bearing structures 4 can be provided, and these multiple bearing structures 4 can be distributed along the axial direction of the lead screw 2311 to form multi-point support, further improving the support stiffness and bending resistance. This specification does not limit the specific type and installation method of the bearing structure 4, as long as it can achieve the rotational support and radial limiting of the lead screw 2311, it is within the protection scope of this solution.

[0068] In this embodiment, please refer to Figure 1 and Figure 6 The drive shafts 21 of the two drive mechanisms 20 are arranged side by side in the second direction, and the two limiting structures 30 are correspondingly installed on the drive shafts 21 and are spaced apart in the second direction. The rotary motors 22 of the two drive mechanisms 20 are arranged side by side in the third direction, and their output axes extend along the third direction, are parallel to each other and maintain an appropriate distance to adapt to the internal spatial layout of the housing 10.

[0069] Specifically, the rotary motors 22 of the two drive mechanisms 20 are arranged side by side in the third direction, with their output axes extending along the third direction, parallel to each other and maintaining an appropriate distance to accommodate the internal installation space and heat dissipation requirements of the housing 10. The rotary motor 22 can be a rotary motor 22 with its axis arranged along the third direction, so that the motor can be laterally embedded into the housing 10 during assembly, reducing the overall length along the first direction and making the structure compact.

[0070] The first direction is the linear motion direction of the drive shaft 21, the second direction is the distribution direction of the drive shaft 21 and the limiting structure 30, and the third direction is the arrangement direction of the rotary motor 22. These three directions are mutually perpendicular, forming a three-dimensional orthogonal coordinate system. This decouples the telescopic motion direction of the drive shaft 21, the arrangement direction of the rotary motor 22, and the lateral arrangement direction between the two drive mechanisms 20, facilitating functional zoning and structural optimization within a compact space.

[0071] Based on this, the two transmission mechanisms 23 are arranged in a centrally symmetrical manner with the axis passing through the midpoint of the axes of the two rotary motors 22 and parallel to the axes of the rotary motors 22 as the axis of symmetry. This axis of symmetry is located inside the housing 10, passes through the midpoint of the line connecting the geometric centers of the two rotary motors 22, and is parallel to the axes of the rotary motors 22, so that the mass distribution and inertia characteristics of the transmission systems on the left and right sides are basically the same, avoiding dynamic imbalance or torque fluctuation caused by asymmetry.

[0072] Meanwhile, the center of the line connecting the axes of the two rotary motors 22 coincides with the center of the line connecting the axes of the two drive shafts 21 in the first direction. This arrangement ensures that when the drive shafts 21 output thrust or pull, the lines of action of their forces converge at the same central point in space. When the linear actuator 100 is subjected to external off-center loads or undergoes acceleration or deceleration, the inertial force and reaction force form a balanced force system around this center, thereby avoiding the generation of a net overturning moment around the center and improving the mechanical balance and motion stability of the linear actuator 100 under complex working conditions.

[0073] The centrally symmetrical and overlapping arrangement of the two drive mechanisms 20 ensures that the thrust generated during operation is symmetrically distributed about the system's center point. The reaction force, inertial force, and resultant force of the transmission system and external load are all balanced around this center, and the line of action of the resultant force passes through the overall geometric center to avoid generating additional eccentric torque. Even under dynamic start-stop or load fluctuation conditions, the drive forces on both sides can remain synchronized and balanced, thereby reducing vibration and local stress concentration in the housing 10.

[0074] By symmetrically arranging the drive shafts 21, limiting structure 30, and rotary motor 22 of the two drive mechanisms 20 in three mutually perpendicular directions and coinciding with the center, the resultant force of the driving force is located at the geometric center of the system, which can achieve torque self-balancing and uniform load distribution.

[0075] It should be noted that, to meet the different degrees of freedom of the bionic robotic hand in terms of driving torque, the output forces of the drive shafts 21 of the two drive mechanisms 20 are set differently in this embodiment. Specifically, in practical applications, the drive shafts 21 of the two drive mechanisms 20 are connected by a hinge to the first crank and the second crank corresponding to the fingers of the robotic hand to realize the flexion and extension movements of the finger joints. Due to structural space limitations, the lengths of the two cranks are often inconsistent. According to the torque balance principle, the output torque is equal to the product of the driving force and the lever arm length (T = F × L). When the crank lengths are unequal, the driving force needs to be differentiated in order to obtain the same joint output torque.

[0076] Specifically, the drive shaft 21 connected to the shorter crank needs to provide greater output force to compensate for its smaller lever arm, thereby ensuring that it matches the torque output of the longer crank end and achieving consistency and coordination of motion performance. Therefore, by configuring drive mechanisms 20 with different rated thrusts or adjusted by different transmission ratios, the output forces of the two drive shafts 21 can differ, which can meet the differentiated requirements of different degrees of freedom for driving torque.

[0077] Further, please refer to Figure 2 and Figure 4 In this embodiment, each of the transmission mechanisms 23 further includes a reduction transmission structure 232, the transmission ratio of the reduction transmission structure 232 and / or the lead of the lead screw 2311 are set differently between the two drive mechanisms 20, so as to achieve different output force settings for the drive shaft 21.

[0078] Specifically, the two reduction transmission structures 232 include a first reduction transmission structure 232 and a second reduction transmission structure 232. Let the transmission ratios of the first and second reduction transmission structures 232 be i1 and i2, respectively, with a ratio M = i1 / i2; the leads of the lead screws 2311 be L1 and L2, respectively, with a ratio N = L1 / L2; and the output forces of the two drive mechanisms 20 be F1 and F2, respectively, with a ratio K = F1 / F2. According to the mechanical conversion relationship, under the same motor input torque condition, the linear output force is directly proportional to the reduction ratio and inversely proportional to the lead. According to the mechanical relationship, the linear output force F satisfies the following condition with respect to the input torque T and the lead L: F∝T / L. Therefore, under the same torque, the smaller the lead, the greater the output force; the two are inversely proportional.

[0079] The final output force of the drive mechanism 20 is determined by both the transmission ratio and the lead. Let the output torque of the motor be T0, then the torque at the end of the lead screw 2311 after reduction is: T0×i1 for the first drive mechanism 20, and T0×i2 for the second drive mechanism 20.

[0080] The first drive mechanism 20 corresponds to a linear output force F1∝(T0×i1) / L1, and the second drive mechanism 20 corresponds to a linear output force F2∝(T0×i2) / L2. The ratio of their linear output forces is K=F1 / F2=(i1 / i2)×(L2 / L1). Substituting M=i1 / i2 and N=L1 / L2, we get L2 / L1=1 / N, therefore K=M×(1 / N). This quantitative relationship provides a design basis for achieving precise output matching. By adjusting the combination of M and N, the two drive mechanisms 20 can output the required proportional linear force under different load conditions.

[0081] For example, when M=2 and N=0.5, K=4, meaning the output force of the first drive mechanism 20 is four times that of the second drive mechanism 20. By adjusting the combination of M and N, the two drive mechanisms 20 can be adapted to torque requirements under different crank lengths or load conditions.

[0082] By establishing a quantitative relationship between reduction ratio, lead and output force, the predictable and controllable design of multi-path drive output force is realized, thereby improving the adaptability of the linear actuator 100 to multi-degree-of-freedom differentiated loads in the bionic manipulator.

[0083] Specifically, please refer to Figure 4In this embodiment, each of the transmission mechanisms 23 further includes a reduction transmission structure 232, which includes an input gear 2321, an output gear 2322, and a transmission gear 2323. The input gear 2321 is coaxially arranged with the output shaft of the rotary motor 22, and the output gear 2322 is coaxially connected with the lead screw 2311. The transmission gear 2323 has a first tooth portion 23231 and a second tooth portion 23232. The first tooth portion 23231 meshes with the input gear 2321, and the second tooth portion 23232 meshes with the output gear 2322. The diameter of the first tooth portion 23231 of the transmission gear 2323 is larger than the diameter of its second tooth portion 23232.

[0084] Understandably, the rotating shaft of the rotary motor 22 is connected to the input gear 2321. The input gear 2321 meshes with the first tooth 23231 of the transmission gear 2323. The diameter of the first tooth 23231 is larger than that of the second tooth 23232. The second tooth 23232 then meshes with the output gear 2322. The output gear 2322 is coaxially fixed with the lead screw 2311. This gear set constitutes a composite transmission link in a multi-stage reduction, where the transmission gear 2323 acts as an intermediate transition component. Its first tooth 23231 receives the high-speed, low-torque power from the input gear 2321 and transmits the power to the smaller-diameter second tooth 23232 through its own rotation, thereby creating a transmission effect of reduced speed and increased torque at the output gear 2322.

[0085] It should be noted that the first tooth 23231 and the second tooth 23232 of the transmission gear 2323 can be an integral structure, adopting a coaxial double-diameter gear design. The material can be alloy steel, engineering plastics or powder metallurgy products, and the tooth profile can be involute, modified tooth or equal height tooth, to adapt to different load and noise requirements.

[0086] The module and number of teeth of the input gear 2321 and the output gear 2322 can be matched and designed according to the required transmission ratio, so that the overall reduction ratio is jointly determined by the meshing ratio of the first tooth section 23231 with the input gear 2321 and the meshing ratio of the second tooth section 23232 with the output gear 2322. This specification does not limit the specific number of teeth, module, or arrangement of the gears; the specific configuration can be determined based on the output torque, speed, and structure of the housing 10. The embodiments in this specification do not limit this.

[0087] By setting a transmission gear 2323 with large and small double teeth, a high speed ratio reduction path is formed between the input gear 2321 and the output gear 2322, so as to have higher output torque at the same motor speed. This can improve the driving force output capability of the actuator under small volume conditions, meet the working conditions of high load and low speed stable operation, and is especially suitable for bionic joints or precision operation equipment with limited space but requiring high thrust output.

[0088] Furthermore, to address the issue that the multi-drive linear actuator 100 suffers from redundant layout and loose structure in three-dimensional space, resulting in excessive overall size and uneven mass distribution, making it difficult to adapt to the installation requirements of highly integrated electromechanical systems, please refer to [link to relevant documentation]. Figure 6 In this embodiment, the output axis of the rotary motor 22 of each drive mechanism 20 and the rotation axis of the transmission gear 2323 are aligned in a second direction, i.e., they are located in the same plane in this direction. This arrangement ensures that the rotary motor 22 and the transmission gear 2323 have no additional offset in the second direction, reducing the width requirement of the housing 10 in this direction. This aligned arrangement also brings the meshing point of the first tooth 23231 of the input gear 2321 and the transmission gear 2323 closer to the center region of the system, thereby shortening the force transmission path and improving transmission stiffness.

[0089] Specifically, in this embodiment, each of the rotary motors 22 is a hollow cup motor, an axial flux motor, or a torque motor.

[0090] High-response motors feature low rotor inertia and rapid dynamic response, making them suitable for applications requiring frequent starts and stops and high-frequency position adjustments. High-power-density motors provide high output power in a smaller size, which is beneficial for improving the integration and load capacity of actuators. Direct-drive torque motors employ a flat design, providing high torque output without a reduction gear, simplifying the transmission chain and improving control accuracy and efficiency. The selection of the rotary motor type 22 can be matched to the specific requirements of the linear actuator 100 for speed, torque, size, and control performance; this specification does not limit this selection in the embodiments.

[0091] By employing high-response, high-power-density, or direct-drive torque motors, the power performance and control dynamics of the drive mechanism 20 can be improved, achieving fast, precise, and high-load linear motion output while maintaining a compact structure, thus meeting the stringent requirements of bionic robotic hands for dexterity and real-time performance.

[0092] The present invention also proposes a robotic hand, which includes robotic fingers and a linear actuator 100. The specific structure of the linear actuator 100 is as described in the above embodiments. Since the robotic hand adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.

[0093] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A linear actuator (100), characterized in that, include: Shell (10); Two drive mechanisms (20), each drive mechanism (20) comprising: A drive shaft (21) is inserted through one end of the housing (10) in the first direction and is movably disposed along the first direction; Rotary motor (22), having a rotating shaft; and, The transmission mechanism (23) is used to drive the rotating shaft and the drive shaft (21). The transmission mechanism (23) includes a lead screw transmission structure (231). The lead screw transmission structure (231) includes a lead screw (2311) rotatably installed in the housing (10) and a drive nut (2312) threadedly engaged with the lead screw (2311). The drive nut (2312) is connected to the drive shaft (21) to drive the drive shaft (21) to move. The linear actuator (100) further includes a limiting structure (30), which is located between the drive shaft (21) and the housing (10) to provide independent linear guidance for the drive shaft (21) and constrain its radial displacement to resist the overturning torque applied to the linear actuator (100).

2. The linear actuator (100) as claimed in claim 1, characterized in that, Each of the aforementioned limiting structures (30) includes a linear guide support structure, the linear guide support structure comprising: A guide portion (31) is provided extending along the first direction and is fixedly installed inside the housing (10); and, A support portion (32) is slidably mounted on the guide portion (31) along the first direction, and the support portion (32) is fixedly connected to the corresponding drive shaft (21).

3. The linear actuator (100) as described in claim 2, characterized in that, The linear guide support structure includes a linear guide pair, a splined bushing, or a sliding bearing.

4. The linear actuator (100) as claimed in claim 1, characterized in that, The drive shaft (21) has a guide hole (21a) extending along the first direction at one end inside the housing (10); One end of the lead screw (2311) is provided with a bearing structure (4), the inner ring of the bearing structure (4) is engaged with the lead screw (2311), and the outer ring of the bearing structure (4) is fixedly installed in the housing (10). The other end of the lead screw (2311) is fitted into the guide hole (21a) and is movably disposed relative to the circumference of the drive shaft (21) and the first direction.

5. The linear actuator (100) as claimed in claim 1, characterized in that, The lead screw (2311) is a ball screw, a planetary roller screw, or a trapezoidal screw.

6. The linear actuator (100) as claimed in claim 1, characterized in that, The drive shafts (21) of the two drive mechanisms (20) are arranged side by side in the second direction, the two limiting structures (30) are arranged at intervals in the second direction, and the rotary motors (22) of the two drive mechanisms (20) are arranged side by side in the third direction. The first direction, the second direction, and the third direction are all mutually perpendicular: The two transmission mechanisms (23) are arranged in a centrally symmetrical manner with respect to an axis that passes through the midpoint of the line connecting the axes of the two rotary motors (22) and is parallel to the axis of the rotary motor (22); and / or, The midpoint of the line connecting the axes of the two rotary motors (22) coincides with the midpoint of the line connecting the axes of the two drive shafts (21).

7. The linear actuator (100) as claimed in claim 1, characterized in that, The output force difference of the drive shafts (21) of the two drive mechanisms (20) is set.

8. The linear actuator (100) as claimed in claim 7, characterized in that, Each of the transmission mechanisms (23) further includes a reduction transmission structure (232), the transmission ratio of which and / or the lead of which is the lead screw (2311) are set differently between the two drive mechanisms (20) to achieve a difference in the output force of the drive shaft (21).

9. The linear actuator (100) as claimed in claim 1, characterized in that, Each of the transmission mechanisms (23) further includes a reduction transmission structure (232), which includes an input gear (2321), an output gear (2322), and a transmission gear (2323). The input gear (2321) is coaxially arranged with the output shaft of the rotary motor (22), and the output gear (2322) is coaxially connected with the lead screw (2311). The transmission gear (2323) has a first tooth (23231) and a second tooth (23232), the first tooth (23231) meshes with the input gear (2321), the second tooth (23232) meshes with the output gear (2322), and the diameter of the first tooth (23231) of the transmission gear (2323) is larger than the diameter of its second tooth (23232).

10. The linear actuator (100) as claimed in claim 9, characterized in that, The output axis of the rotary motor (22) of each drive mechanism (20) is aligned with the rotation axis of the transmission gear (2323) in the second direction.

11. The linear actuator (100) as claimed in claim 1, characterized in that, Each of the rotary motors (22) is a coreless motor, an axial flux motor, or a torque motor.

12. A robotic arm, characterized in that, Includes the linear actuator (100) as described in any one of claims 1 to 11.

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