Linear actuator

Abstract

A linear actuator comprises: a housing assembly, the housing assembly having a first side and a second side; a motor assembly, the motor assembly comprising a stator and a rotor; a guide assembly having a first rotation limiting portion, the guide assembly comprising an outer sleeve, the outer sleeve being fixedly connected to a first side of the housing assembly; and a lead screw nut assembly having a second rotation limiting portion, at least a part of the lead screw nut assembly being arranged in the housing assembly and the guide assembly, and the lead screw nut assembly comprising a lead screw, a nut in transmission fit with the lead screw, and a push rod accommodating at least a part of the lead screw, wherein the push rod comprises a linear channel, an inner end portion, and an outer end portion. The linear channel allows the lead screw to rotate and move linearly therein, the inner end portion is connected to the nut, and the outer end portion is arranged outside the outer sleeve and connected to a connection assembly. Moreover, under the cooperative constraint between the first rotation limiting portion and the second rotation limiting portion, the rotation of the nut relative to the guide assembly is limited, such that when the lead screw rotates, the nut and the push rod are driven to move linearly.

Description

Linear actuator Technical Field

[0001] This invention relates to a linear actuator, belonging to the field of mechanical automation technology. Background Technology

[0002] In the fields of modern industrial automation and robotics, linear actuators, as devices that convert electrical energy into linear motion, play a crucial role. Linear actuators provide precise linear motion control and are widely used in robotics, automated production lines, precision positioning systems, medical equipment, aerospace, and other fields.

[0003] However, while pursuing high precision and performance, existing linear actuator technologies often face challenges in lightweight design, integration and intelligence, as well as reliability and durability. Furthermore, their overly complex designs lead to higher costs. For example, the linear actuator module of the Optimus humanoid robot uses a reversible planetary roller screw, which provides efficient thrust and torque, but is more expensive than traditional ball screw nuts. Summary of the Invention

[0004] The present invention provides a linear actuator, which aims to solve at least one of the technical problems existing in the prior art.

[0005] The present invention relates, in one aspect, to a linear actuator, comprising: a housing assembly having a first side and a second side; a motor assembly including a stator and a rotor disposed within the housing assembly; a guide assembly having a first rotation limiting portion, the guide assembly including an outer sleeve fixedly connected to the first side of the housing assembly; and a lead screw and nut assembly having a second rotation limiting portion, at least a portion of the lead screw and nut assembly being disposed within the housing assembly and the guide assembly, the lead screw and nut assembly including a lead screw, a nut engaging with the lead screw, and a push rod accommodating at least a portion of the lead screw, the push rod including a linear channel, an inner end, and an outer end, wherein the linear channel allows the lead screw to rotate and move linearly therein, the inner end is connected to the nut, and the outer end is disposed outside the outer sleeve and connected to a connecting assembly, and wherein the rotation of the nut relative to the guide assembly is limited by the cooperation constraint of the first rotation limiting portion and the second rotation limiting portion, such that when the lead screw rotates, it pushes the nut and the push rod to move linearly.

[0006] According to an embodiment of the present invention, the nut includes an internally threaded hole arranged along the axis, and the push rod includes a shoulder; the inner end of the push rod is fixedly connected to the internally threaded hole of the nut by a thread; and the positioning method of the shoulder abutting against the orifice surface of the internally threaded hole allows the axis of the push rod to substantially coincide with the axis of the nut.

[0007] According to an embodiment of the present invention, the guide assembly includes an inner sleeve disposed in and fixed to the outer sleeve, the inner cavity of the inner sleeve being provided with a planar rail as a first rotation limiting part; the nut of the lead screw nut assembly includes a radial section as a second rotation limiting part; during the movement of the nut in the inner cavity, the planar rail is substantially in contact with the radial section to limit the relative rotation between the nut and the inner sleeve.

[0008] According to an embodiment of the present invention, the inner sleeve includes a groove extending along the edge of the planar rail.

[0009] According to an embodiment of the present invention, the hardness of the material of at least the portion of the inner sleeve that contacts the nut is lower than the hardness of the nut.

[0010] According to an embodiment of the present invention, the guide assembly includes a guide plate fixedly connected to the outer sleeve, the guide plate having a non-circular hole as a first rotation limiting part; the inner end of the push rod of the lead screw nut assembly is fixedly connected to the nut, and the outer periphery of the outer end of the push rod is formed as a non-circular shaft as a second rotation limiting part; during the movement of the nut in the outer sleeve, the non-circular shaft continuously passes through the non-circular hole to limit the relative rotation between the nut and the outer sleeve.

[0011] According to an embodiment of the present invention, the guide assembly includes a clamping block that allows the push rod to pass through; the end side of the outer sleeve is provided with a recess for receiving and positioning at least a portion of the guide piece; the clamping block is fixedly connected to the end side of the outer sleeve so that the guide piece between the clamping block and the outer sleeve is fixed in the recess.

[0012] According to an embodiment of the present invention, the hardness of the material of the guide plate is lower than that of the push rod.

[0013] According to an embodiment of the present invention, the lead screw includes a lead rod portion, a guide rod portion, and a first end, wherein the lead rod portion is driven by the nut, the lead rod portion is driven by the rotor of the motor assembly, the guide rod portion and the first end are located inside the housing assembly, and the guide rod portion is located between the lead rod portion and the first end.

[0014] According to an embodiment of the present invention, the motor assembly includes a rotor support with a through hole that allows at least a portion of the lead screw to pass through and be positioned such that the rotor support and the lead screw rotate together. The rotor support includes: a first frame supported by a first bearing; a second frame supported by a second bearing; and an intermediate frame disposed between the first frame and the second frame, the intermediate frame being driven by the rotor of the motor assembly.

[0015] According to an embodiment of the present invention, the through hole of the rotor support includes a square hole portion, and the lead screw includes a square shaft portion disposed between the lead rod portion and the guide rod portion of the lead screw. The square shaft portion cooperates with the square hole portion to drive the lead screw to rotate.

[0016] According to an embodiment of the present invention, the housing assembly includes: a first housing, the first housing including a first cavity and a first inner shoulder, the first cavity accommodating at least a portion of an electrical component; and a second housing, the second housing including a second cavity and a second inner shoulder, the second cavity accommodating a motor assembly, wherein the first inner shoulder and the second inner shoulder position a first bearing between the electrical component and the motor assembly.

[0017] According to an embodiment of the present invention, the electrical component includes: a force sensor connected between the housing assembly and the connecting assembly; a circuit board connected to the force sensor and disposed within the housing assembly; and an encoder connected to the circuit board and associated with the lead screw and nut assembly to output a rotation amount.

[0018] According to an embodiment of the present invention, the encoder includes: an encoding signal receiver, the encoding signal receiver being fixedly connected to the housing assembly via a support; and an encoding signal generator matched with the encoding signal receiver, the encoding signal generator being fixedly connected to the end of the lead screw.

[0019] The linear actuator according to the embodiments of the present invention can achieve lightweight, low-cost manufacturing, easy maintenance and high reliability while maintaining high precision and high output force performance. Attached Figure Description

[0020] Figure 1 is a perspective view of a linear actuator according to an embodiment of the present invention.

[0021] Figure 2 is an exploded view of a linear actuator according to an embodiment of the present invention.

[0022] Figure 3 is a partial cross-sectional perspective view of a linear actuator according to an embodiment of the present invention.

[0023] Figure 4 is a cross-sectional view of the linear actuator cut according to the cutting method shown in Figure 3.

[0024] Figure 5 is a cross-sectional view of the linear actuator at position AA of the section line in Figure 4.

[0025] Figure 6 is a cross-sectional view of the linear actuator at the position of the cutting line BB in Figure 4.

[0026] Figure 7 is an exploded view of the lead screw and nut assembly and its associated parts according to an embodiment of the present invention.

[0027] Figure 8 is a cross-sectional view of the lead screw and nut assembly and its associated parts according to an embodiment of the present invention.

[0028] Figure 9a is a diagram showing the tensile force and stress analysis of the internal thread connection between the nut and the push rod in an embodiment of the present invention.

[0029] Figure 9b is a stress simulation diagram of a push rod connected to a nut via an internal thread according to an embodiment of the present invention.

[0030] Figure 10a is a diagram showing the tensile and stress analysis of the external thread connection between the nut and the push rod in some technical solutions.

[0031] Figure 10b is a stress simulation diagram of a push rod connected to a nut via an external thread in some technical solutions.

[0032] Figure 11 is a schematic diagram of the travel of the lead screw and nut assembly according to an embodiment of the present invention.

[0033] Figure 12 is an exploded view of a partial linear actuator according to another embodiment of the present invention.

[0034] Figure 13 is a partial cross-sectional view of a linear actuator according to another embodiment of the present invention.

[0035] Figure 14 is a perspective view of a linear actuator according to another embodiment of the present invention. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0037] It should be noted that, unless otherwise specified, when a feature is referred to as "fixed" or "connected" to another feature, it can be directly fixed or connected to the other feature, or indirectly fixed or connected to the other feature. Furthermore, the descriptions of "upper," "lower," "left," "right," "top," and "bottom" used in this invention are only relative to the relative positional relationships of the various components of the invention in the accompanying drawings.

[0038] Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The terminology used in this specification is for the purpose of describing particular embodiments only and not for limiting the invention. The term "and / or" as used herein includes any combination of one or more of the associated listed items.

[0039] It should be understood that although the terms first, second, third, etc., may be used in this disclosure to describe various elements, these elements should not be limited to these terms. These terms are only used to distinguish elements of the same type from one another. For example, without departing from the scope of this disclosure, a first element may also be referred to as a second element, and similarly, a second element may also be referred to as a first element.

[0040] Referring to Figures 1 and 12, in some embodiments, the linear actuator according to the present invention includes a housing assembly 100, a motor assembly 200, a guide assembly 300, and a lead screw and nut assembly 400, and may further include a connecting assembly 500 and an electrical assembly 600. The housing assembly 100 has a first side (front side, indicated by arrow F in the figure) and a second side (rear side, indicated by arrow B in the figure) facing away from each other, and the guide assembly 300 is fixedly connected to the front side of the housing assembly 100. The guide assembly 300 provides a first rotation limiting part, and the lead screw and nut assembly 400 provides a second rotation limiting part. The first rotation limiting part and the second rotation limiting part cooperate to ensure that the nut can only move axially within the guide assembly 300 without rotation. This restricts the rotation of the nut relative to the guide assembly 300 under the constraint of the first and second rotation limiting parts, allowing the motor assembly 200 (shown as a dashed outline in Figures 1 and 12) located within the housing assembly 100 to drive the lead screw and nut assembly 400, causing it to move substantially within the guide assembly 300 and output linear motion along the guide assembly 300. The connecting assembly 500 serves as an external connecting assembly 500 for the linear actuator. There can be one or more connecting assemblies 500, one of which is connected to the output end of the lead screw and nut assembly 400, and another connecting assembly 500 is connected to the rear side of the housing assembly. A portion of the electrical components 600 is connected between the connecting assembly 500 and the housing assembly; this portion of the electrical components 600 is used for force sensing. Specifically, the electrical component 600 may include a force sensor 610, a circuit board 620, and an encoder 630. Specifically, the connection component 500 may include an end connector 501 and a spherical bearing 502 disposed within the end connector 501, wherein the end connector 501 is used for connection to the force sensor 610, the housing assembly 100, or the push rod 430, and the spherical bearing 502 is used to provide flexible external connection.

[0041] Referring to Figures 2 to 4, in one embodiment, the housing assembly 100 includes a cylindrical first housing 110 and a second housing 120. The first housing 110 includes a first cavity 111 and a first inner shoulder 112, wherein the first cavity 111 accommodates the circuit board 620 and encoder 630 of the electrical assembly 600. A force sensor 610 connected to the connecting assembly 500 can be implemented as an end cap and fixedly connected to the first housing 110, as shown in Figures 3 and 4. The force sensor 610 can also be fixed in the first cavity 111 of the first housing 110 while maintaining the sensing of push-pull forces on the connecting assembly 500. The second housing 120 includes a second cavity 121 and a second inner shoulder 122, wherein the second cavity 121 is used to accommodate the motor assembly 200. Referring to Figure 4, the first inner shoulder 112 of the first housing 110 and the second inner shoulder 122 of the second housing 120 position a first bearing 701, which also serves as an isolation between the electrical assembly 600 and the motor assembly 200. The motor assembly 200 in the second cavity 121 is generally not directly connected to the electrical assembly 600 in the housing assembly 100. Preferably, the first housing 110 and the second housing 120 respectively include a first wire routing hole 113 leading to the first cavity 111 and a second wire routing hole 123 leading to the second cavity 121. The first wire routing hole 113 is used for leading wires from the circuit board 620 and / or encoder 630, and the second wire routing hole 123 is used for leading wires from the motor assembly 200. It is understood that dividing the housing assembly 100 into two housing parts with bearings as spacers allows for better electromagnetic and thermal isolation by accommodating relatively low-current components (encoding circuits) and relatively high-current components (motor windings) in the two cavities. Furthermore, it is understood that the first bearing 701, positioned at the two inner shoulders of the two housings, is located at the boundary between the two housings, thus facilitating the installation and removal of the first bearing 701.

[0042] Referring again to Figures 2 through 4, in some embodiments, the motor assembly 200 includes a stator 210, a rotor 220, and a rotor support 230. The lead screw and nut assembly 400 includes a lead screw 410, a nut, and a push rod 430.

[0043] Referring to Figures 2 and 5, in one embodiment, the motor stator 210 can be frame-shaped and fixed to the second housing 120, while the motor rotor 220 is disposed in the center of the stator 210 and its inner wall is supported by a rotor bracket 230. Preferably, the stator 210 is composed of coil windings, and the rotor 220 comprises magnets. The rotor bracket 230 has a through hole that allows at least a portion of the lead screw 410 to pass through and be positioned so that the rotor bracket 230 and the lead screw 410 rotate together. In one embodiment, the stator 210 is fixed to the second housing 120 with adhesive, and the rotor 220 is also fixed to the rotor bracket 230 with adhesive.

[0044] Referring to Figures 4 to 8, in one embodiment, the rotor support 230 can be integrally formed, but it may also include a first frame 231, a second frame 232, and an intermediate frame 233 disposed between the first frame 231 and the second frame 232. The lead screw 410 includes a first end 413, a smooth rod portion 412, a lead screw portion 411, and a second end 415, wherein the diameters of the first end 413 and the smooth rod portion 412 are smaller than the diameter of the lead screw portion 411. Referring to Figure 4, the second end 415, located away from the first end 413, has a clamping surface, which can be used for clamping the lead screw 410 during installation, adjustment, maintenance, etc. Preferably, referring to Figures 7 and 8, the linear actuator according to the present invention may also provide an anti-loosening nut 705, such that the second end 415 can be locked with the anti-loosening nut 705 by means of an external thread. The outer diameter of the anti-loosening nut 705 is slightly smaller than the inner diameter of the straight channel 431 and larger than the minimum inner diameter between the screw grooves in the screw section 411. Thus, when the anti-loosening nut 705 is fixed at the second end 415, it blocks the end E of the screw groove, preventing the ball nut 420 from exceeding its stroke and coming off.

[0045] The rotor support 230 has a through hole that extends through the first frame 231, the second frame 232, and the intermediate frame 233. The diameter of the through hole in the first frame 231 is approximately equal to or slightly larger than the diameter of the smooth rod portion 412 of the lead screw 410, but smaller than the diameter of the lead screw portion 411. The diameters of the through holes in the second frame 232 and the intermediate frame 233 are larger than the diameter of the lead screw portion 411. This allows the lead screw 410 to be positioned in the first frame 231 by the smooth rod portion 412 when inserted into the rotor support 230, ensuring that the stepped wall between the lead screw portion 411 and the smooth rod portion 412 is tightly positioned against the end wall between the first frame 231 and the intermediate frame 233. Furthermore, the first end 413 of the lead screw 410 extends out of the first frame 231 after being inserted into the rotor support 230.

[0046] In this embodiment, the first frame 231, the second frame 232, and the intermediate frame 233 all have circumferential outer walls. The outer circumferential wall of the first frame 231 mates with the inner ring of the first bearing 701, and the outer ring of the first bearing 701 mates with the housing assembly 100. Furthermore, the guide rod 412 of the lead screw 410 inserts into the through hole of the first frame 231 with almost no gap. Therefore, the first bearing 701 provides primary support for the rotor support 230 and the lead screw 410, while also allowing them to rotate. Further, a flange nut 704 can be used to screw into the first end 413 through its external thread, fixing the inner ring of the first bearing 701 in the first frame 231 fitted into the rotor support 230, as shown in Figures 3 and 4. Additionally, the outer circumferential wall of the second frame 232 mates with the inner ring of the second bearing 702, and the outer ring of the second bearing 702 mates with the guide assembly 300. Therefore, the second bearing 702 provides secondary support for the rotor support 230. A schematic diagram of the support of the two bearings is shown in the dashed box in Figure 8. Preferably, the first bearing 701, used as the main support, is a double-row angular contact bearing, and the second bearing 702, used as the secondary support, can be a single-row ball bearing. The outer peripheral wall of the intermediate frame 233 is fitted and fastened to the inner ring of the motor rotor 220, so the rotor 220 can drive the intermediate frame 233 to rotate, thereby driving the lead screw 410 to rotate.

[0047] In some embodiments, the rotor support 230 includes a non-circular bore surface feature, and the lead screw 410 includes a non-circular shaft surface feature. The non-circular bore surface feature and the non-circular shaft surface feature cooperate to transmit a larger torque when the rotor support 230 drives the inserted lead screw 410 to rotate. Referring to Figures 5 and 8, in a preferred embodiment, the through hole between the first frame 231 and the intermediate frame 233 of the rotor support 230 is provided with a square hole portion 234, and a square shaft portion 414 is provided between the lead screw portion 411 and the guide rod portion 412 of the lead screw 410. The square shaft portion 414 is inserted into the square hole portion 234, causing the rotor support 230 to drive the lead screw 410 to rotate. It is understood that the diameter of the first frame 231 is smaller than that of the intermediate frame 233; therefore, the frame structure transitioning from the first frame 231 to the intermediate frame 233 extends radially, thereby forming a robust square hole portion 234 to transmit a larger torque.

[0048] Referring back to Figures 2 and 3, in one embodiment, the encoder 630 includes an encoded signal receiver 631 and an encoded signal generator 633. The encoded signal receiver 631 and the encoded signal generator 633 can be read heads and code disks in the form of magnetic, photoelectric, capacitive, or inductive sensors. These read heads and code disks are used to encode and decode signals, thereby achieving accurate position detection or speed measurement. For example, in a magnetic encoder, magnetic stripes are engraved on the code disk, and the read head generates a position signal by detecting changes in these stripes; while in a photoelectric encoder, light-transmitting and light-blocking areas are engraved on the code disk, and the read head generates encoded signals by detecting the on / off state of light, further analyzes and processes these encoded signals, and uses the processed encoded signals to control the speed or position accuracy of the motor assembly 200.

[0049] In some embodiments, the encoded signal receiver 631 can be integrated into the circuit board 620 or be a separate component, fixedly connected to the internal structure of the first housing 110 within the first cavity 111 via a support 632. The encoded signal generator 633 is positioned sufficiently close to the encoded signal receiver 631 so that its movement (rotation) is fully received by the encoded signal receiver 631. As shown in FIG3, the encoded signal generator 633 is threadedly fixed to the first end 413 of the lead screw 410 via a screw 703. In other embodiments, the encoded signal generator 633 may also be connected to a flange nut 704.

[0050] The above embodiments basically describe the arrangement of components and parts in the rear section of the linear actuator. The following embodiments describe in more detail the structure or configuration of the lead screw and nut assembly 400 in the front section of the linear actuator.

[0051] In some embodiments, the linear actuator according to the invention may incorporate a ball-type, T-type, or standard planetary roller-type screw and nut mechanism as part of the screw and nut assembly 400 in a structure or configuration. Some of the embodiments described below are typically exemplified by a ball-type screw and nut.

[0052] Referring to Figures 2 to 8, and especially Figures 7 and 8, in one embodiment, in the lead screw and nut assembly 400, the push rod 430 includes a linear channel 431, an inner end portion 432, a shoulder 433, and an outer end portion 434. The nut in the lead screw and nut assembly 400 can be a ball nut 420, which includes a ball sleeve 421 and an internal threaded hole 422 disposed in the ball sleeve 421. The inner diameter of the internal threaded hole 422 is larger than the diameter of the lead screw 410, and no balls are exposed in the internal threaded hole 422, so that the lead screw 410, which is driven and engaged with the nut, does not interfere when passing through the internal threaded hole 422. In this embodiment, the inner end 432 of the push rod 430 is fixedly connected to the internal threaded hole 422 of the nut via a thread; and the positioning method of the shoulder 433 pressing against the opening surface of the internal threaded hole 422 ensures that the axes of the push rod 430, the nut, and the lead screw 410 are substantially coincident in the longitudinal direction, thereby ensuring that these axes are substantially coincident with the rotation axis of the lead screw 410. In addition, the shoulder 433 can also enhance the connection rigidity between the nut and the push rod 430, while ensuring the axial positioning accuracy of 430.

[0053] It is understood that lead screw nuts require high structural rigidity and precision. If a cylinder or rod is directly integrally formed from the lead screw nut as the linear motion output part of the linear actuator, the cost would be high. Therefore, under the design requirements of high load-volume ratio for linear actuators, in the solution of the present invention, the nut is connected by a separate push rod 430 with an internal thread, which not only makes the overall diameter of the component smaller, but also allows it to withstand larger push-pull loads (such as load forces up to 10KN).

[0054] Figures 9a and 10a are tensile and stress analysis diagrams of the connection between the nut and the push rod 430 via internal and external threads, respectively. In the figures, Fb is the dominant force generated by the nut being driven by the lead screw 410, Ft is the force on the first end 413 of the push rod 430, and St is the stress on the inner end 432 of the push rod 430. Linear actuators generally have two working conditions: push-out and pull-back. In the pull-back condition, the lead screw and nut assembly 400 bears a greater force load. Therefore, the directions of Fb and Ft in the figures correspond to the direction of the force of the linear actuator in the pull-back condition. In the pull-back condition, theoretically, if the internal thread is used for tightening, the stress generated at the connection of the push rod 430 is biased towards deforming the end of the push rod 430 inward (as shown by the direction of St in Figure 9a); while if the external thread is used for tightening, the stress generated at the connection of the push rod 430 is biased towards deforming the end of the push rod 430 outward (as shown by the direction of St in Figure 10a). Given the same wall thickness, inward contraction results in smaller deformation and is less prone to breakage than outward expansion.

[0055] Furthermore, to reduce volume and dynamic mass, the diameter of the push rod 430 can be minimized. When using an external thread fastening method, a stepped rod is formed as shown in Figures 10a and 10b. Referring to Figures 9b and 10b, for two push rods 430 with essentially the same main body diameter, under the same constraint conditions, material (e.g., steel), and tensile load (e.g., 10 kN), a finite element stress simulation comparison using the von Mises criterion is performed. The push rod 430 using the internal thread fastening method exhibits lower overall stress and does not exceed the yield critical value of the push rod 430 material. It is understood that the von Mises criterion (also known as the maximum shear stress theory or equivalent stress criterion) is a criterion used in materials mechanics and materials science to determine whether a material undergoes plastic deformation. It is mainly used to analyze the yielding behavior of isotropic materials (such as metals) under complex stress states. Therefore, in the linear actuator of the present invention, the internal thread connection between the nut and the push rod 430 achieves both a compact structure and meets high load requirements. It is understandable that the weak point of the externally threaded push rods shown in Figures 10a and 10b is mainly the stepped transition. If the externally threaded push rod is not implemented as a stepped push rod, the push-pull force it experiences is the same as that of the internally threaded push rod. However, to consider compactness, the use of internal threads is necessary to ensure both strength and compact size when using a stepped push rod.

[0056] In the above embodiments, the inner end 432 of the lead screw 410, nut, and push rod 430 is disposed in the internal space formed by the housing assembly 100 and the guide assembly 300, while the outer end 434 of the push rod 430 extends out of the guide assembly 300 and is connected to the connecting assembly 500. The lead screw portion 411 of the lead screw 410 can rotate and move linearly in the linear channel 431 of the push rod 430, but does not protrude beyond the outer end 434 of the push rod 430. A small amount of lubricating grease can be placed in the linear channel 431 of the push rod 430 without easily leaking or contaminating, making the lubrication and maintenance of the lead screw 410 simpler.

[0057] Referring to Figures 3, 4, and 6 to 8, in a first embodiment, the guide assembly 300 includes an inner sleeve 310 and an outer sleeve 320. The outer sleeve 320 can be fixedly connected to the front side of the second housing 120. The outer sleeve 320 is in the shape of a stepped cylinder, with a larger diameter closer to the housing assembly 100 and a smaller diameter further away from the housing assembly 100. The inner sleeve 310 is disposed within and fixed to the outer sleeve 320. The inner sleeve 310 can be in the form of a straight cylindrical column to allow linear movement of the nut and push rod 430 of the lead screw nut assembly 400 therein. Preferably, referring to Figures 4 and 8, the inner sleeve 310 has protruding edges 312 at both ends to form a gap cavity 321 between the protruding edges 312 at both ends and the inner sleeve 320. In one embodiment, in order to fix the inner and outer sleeves 310, the inner sleeve 310 coated with adhesive can be inserted into the outer sleeve 320. At this time, the adhesive can be contained and cured in the gap cavity 321, thus making it more secure.

[0058] Referring to Figures 6 to 8, in one embodiment, the inner cavity 311 of the inner sleeve 310 is provided with a planar rail 313 as the first rotation limiting part. Correspondingly, the nut (ball bearing sleeve 421) includes a radial section 423 as the second rotation limiting part. During the movement of the nut in the inner cavity 311, the planar rail 313 is in substantially contact with the radial section 423 to limit the relative rotation between the nut and the inner sleeve 310, but allows the nut to move linearly along the planar rail 313. The planar rail 313 can extend through the inner sleeve 310, as shown by the dotted line in Figure 7. Preferably, the axis of the inner sleeve 310 is substantially coincident with the axis of the lead screw nut assembly 400, and the planar rail 313 includes a pair of parallel planes that are symmetrical with respect to the axis of the inner sleeve 310. Similarly, the nut is also provided with a pair of radial sections 423 that are symmetrical with respect to the axis, and the distance between these radial sections 423 is substantially equal to the distance between the pair of planar rails 313.

[0059] Referring to Figure 6, in a preferred embodiment, the inner sleeve 310 may also be provided with a plurality of grooves 314 extending along the edge of the planar rail 313, the grooves 314 being arranged at the edge of the planar rail 313 surface. Viewed in cross-section in Figure 6, the grooves 314 are hollowed-out slots at the contact corners of the nut and the inner sleeve 310, and can have a rounded cross-sectional profile. This reduces the frictional resistance when the nut moves linearly within the inner sleeve 310, while also reducing machining difficulty and facilitating processing. Furthermore, the grooves 314 can hold lubricating grease, maintaining a long-lasting lubrication effect and reducing wear on the parts. Preferably, the hardness of the material in at least the portion of the inner sleeve 310 that contacts the nut is lower than the hardness of the nut. For example, the inner sleeve 310 is made of copper alloy, while the nut is made of carbon steel. The separation of the inner sleeve 310 and the outer sleeve 320 into two parts also takes into account that the outer sleeve 320 uses a harder steel as a support, while the inner sleeve 310 uses a relatively soft copper alloy material, suitable for lubrication and reducing wear.

[0060] Therefore, referring to Figure 11, under the constraints of the planar rail 313 of the inner sleeve 310 and the radial section 423 of the ball nut 420, when the motor rotor 220 drives the lead screw 410 to rotate clockwise and counterclockwise (as shown in the figure, the rotation direction R), the push rod 430 drives the connecting assembly 500 to push out and pull back in a linear motion S.

[0061] Furthermore, referring back to Figure 4, the outer sleeve 320 has a protruding ring 322 on the side near the second housing 120 for positioning and supporting the second bearing 702. Unlike the first bearing 701, the second bearing 702 is not positioned and supported by the housing assembly 100, which is to facilitate bearing assembly. For example, when the motor rotor 220, rotor bracket 230, guide assembly 300, lead screw nut assembly 400 (including push rod 430), and second bearing 702 are assembled together, and then inserted into the first bearing 701 which has already been positioned by the second housing 120, it is only necessary to position the guide assembly 300 with the second housing 120 using the sleeve shoulder and tighten the screw 703, thus saving the alignment of the second bearing 702 with the first bearing 701.

[0062] Referring now to Figures 12 to 14, in the second embodiment, the guide assembly 300 includes an outer sleeve 320 and a guide piece 330 fixedly connected to the outer sleeve 320. Referring to Figure 13, in one embodiment, the guide assembly 300 may further include a clamping block 340, which allows the push rod 430 to pass through. The outer sleeve 320 has a recess 323 at one end for receiving and positioning the guide piece 330, such that the clamping block 340 is fixedly connected to the end of the outer sleeve 320 to fix the guide piece 330 between the clamping block 340 and the outer sleeve 320 in the recess 323. In other embodiments, the positioning guide piece 330 may be provided with an adhesive groove (not shown), which, after the positioning guide piece 330 is adjusted to a suitable position with the outer sleeve 320 and the adhesive dries, will adhere to the clamping block 340. The guide piece 330 has a non-circular hole as the first rotation restriction portion. The outer periphery of the outer end 434 of the push rod 430 of the lead screw nut assembly 400 is formed as a non-circular shaft to serve as the second rotation limiting part. Since the nut is fixedly connected to the inner end 432 of the push rod 430, during the movement of the nut in the outer sleeve 320, the non-circular shaft of the push rod 430 continuously passes through the non-circular hole to limit the relative rotation between the nut and the outer sleeve 320. Preferably, referring to FIG12, the non-circular hole is a square hole 333, and the non-circular shaft is a square shaft 435, the size of which is substantially equal to or slightly smaller than the size of the square hole 333. Preferably, the hardness of the guide plate 330 is lower than that of the push rod 430. For example, the guide plate 330 is made of copper alloy, while the push rod 430 is made of steel, to improve lubrication and reduce wear.

[0063] Therefore, referring to Figure 14, under the rotational constraint between the guide plate 330 and the push rod 430, when the motor rotor 220 drives the lead screw 410 to rotate clockwise and counterclockwise, the push rod 430 drives the connecting assembly 500 to push out and pull back in linear motion.

[0064] It is understood that the guide component 300 solution in the first embodiment is generally suitable for short-stroke linear actuators. The guide component 300 solution in the second embodiment is generally more suitable for long-stroke linear actuators.

[0065] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A linear actuator, characterized in that, include: A housing assembly (100) having a first side and a second side; A motor assembly (200) comprising a stator (210) and a rotor (220) disposed within the housing assembly (100); A guide assembly (300) having a first rotation limiting portion, the guide assembly (300) including an outer sleeve (320) fixedly connected to a first side of the housing assembly (100); A lead screw and nut assembly (400) having a second rotation limiting portion, at least a portion of which is disposed in the housing assembly (100) and the guide assembly (300), the lead screw and nut assembly (400) including a lead screw (410), a nut that drivesly engages with the lead screw (410), and a push rod (430) accommodating at least a portion of the lead screw (410), the push rod (430) including a linear channel (431), an inner end (432), and an outer end (434), wherein, The linear channel (431) allows the lead screw (410) to rotate and move linearly therein, the inner end (432) is connected to the nut, the outer end (434) is disposed outside the outer sleeve (320) and connected to the connecting assembly (500), and wherein, The rotation of the nut relative to the guide assembly (300) is restricted by the cooperation of the first rotation limiting part and the second rotation limiting part.

2. The linear actuator according to claim 1, wherein: The nut includes an internal threaded hole (422) provided along the axis, and the push rod (430) includes a shoulder (433); The inner end (432) of the push rod (430) is fixedly connected to the inner threaded hole (422) of the nut by means of a thread; and The positioning method, in which the shoulder (433) is pressed against the orifice of the internal threaded hole (422), allows the axis of the push rod (430) to substantially coincide with the axis of the nut.

3. The linear actuator according to claim 1 or 2, wherein: The guide assembly (300) includes an inner sleeve (310) disposed in and fixed to the outer sleeve (320), and the inner cavity (311) of the inner sleeve (310) is provided with a planar rail (313) as the first rotation limiting part; The nut of the lead screw nut assembly (400) includes a radial section (423) as the second rotation limiting part; As the nut moves within the inner cylinder cavity (311), the planar rail (313) comes into substantially contact with the radial tangent (423) to limit the relative rotation between the nut and the inner sleeve (310).

4. The linear actuator according to claim 3, wherein, The inner sleeve (310) includes a groove (314) extending along the edge of the planar rail (313).

5. The linear actuator according to claim 3 or 4, wherein, The hardness of the material in at least the portion of the inner sleeve (310) that contacts the nut is lower than the hardness of the nut.

6. The linear actuator according to claim 1, wherein: The guide assembly (300) includes a guide piece (330) fixedly connected to the outer sleeve (320), the guide piece (330) having a non-circular hole as the first rotation limiting part; The inner end (432) of the push rod (430) of the lead screw nut assembly (400) is fixedly connected to the nut, and the outer periphery of the outer end (434) of the push rod (430) is formed as a non-circular shaft to serve as the second rotation limiting part; As the nut moves within the outer sleeve (320), the non-circular shaft continuously passes through the non-circular hole to restrict the relative rotation between the nut and the outer sleeve (320).

7. The linear actuator according to claim 6, wherein: The guide assembly (300) includes a clamping block (340) that allows the push rod (430) to pass through; The outer sleeve (320) has a recess (323) on its end side for accommodating and positioning at least a portion of the guide piece (330); The clamping block (340) is fixedly connected to the end side of the outer sleeve (320) so that the guide piece (330) between the clamping block (340) and the outer sleeve (320) is fixed in the recess (323).

8. The linear actuator according to claim 6 or 7, wherein, The hardness of the material of the guide plate (330) is lower than that of the push rod (430).

9. The linear actuator according to any one of claims 1 to 8, wherein, The lead screw (410) includes a lead screw section (411), a guide rod section (412), and a first end (413). The lead screw section (411) is driven by the nut. The lead screw section (411) is driven by the rotor (220) of the motor assembly (200). The guide rod section (412) and the first end (413) are located inside the housing assembly (100). The guide rod section (412) is located between the lead screw section (411) and the first end (413).

10. The linear actuator according to any one of claims 1 to 9, wherein, The motor assembly (200) includes a rotor support (230) with a through-hole that allows at least a portion of the lead screw (410) to pass through and be positioned such that the rotor support (230) and the lead screw (410) rotate together, the rotor support (230) comprising: The first frame (231) is supported by the first bearing (701); The second frame (232) is supported by the second bearing (702); An intermediate frame (233) is disposed between the first frame (231) and the second frame (232), and the intermediate frame (233) is driven by the rotor (220) of the motor assembly (200).

11. The linear actuator according to claim 10, wherein, The through hole of the rotor support (230) includes a square hole portion (234), and the lead screw (410) includes a square shaft portion (414) disposed between the lead rod portion (411) and the guide rod portion (412) of the lead screw (410). The square shaft portion (414) cooperates with the square hole portion (234) to make the rotor support (230) drive the lead screw (410) to rotate.

12. The linear actuator according to claim 10, wherein, The housing assembly (100) includes: A first housing (110) includes a first cavity (111) and a first inner shoulder (112), the first cavity (111) accommodating at least a portion of an electrical component (600); The second housing (120) includes a second cavity (121) and a second inner shoulder (122), the second cavity (121) accommodating the motor assembly (200). The first inner shoulder (112) and the second inner shoulder (122) position the first bearing (701) between the electrical assembly (600) and the motor assembly (200).

13. The linear actuator according to claim 12, wherein, The electrical component (600) includes: A force sensor (610) is connected between the housing assembly (100) and the connection assembly (500); A circuit board (620) is connected to the force sensor (610) and disposed within the housing assembly (100); An encoder (630) is connected to the circuit board (620) and associated with the lead screw and nut assembly (400) to output rotation.

14. The linear actuator according to claim 13, wherein, The encoder (630) includes: An encoded signal receiver (631) is fixedly connected to the housing assembly (100) via a support (632); An encoding signal generator (633) is matched with the encoding signal receiver (631), and the encoding signal generator (633) is fixedly connected to the end of the lead screw (410).

15. The linear actuator according to claim 13, wherein, The first housing (110) includes a first wire routing hole (113) that leads to the first cavity (111) for wires from the circuit board (620) and / or the encoder (630); The second housing (120) includes a second wire routing hole (123) that leads to the second cavity (121) for wires to be drawn from the motor assembly (200).

16. The linear actuator according to claim 10, wherein, The inner sleeve (310) has protruding edges (312) at both ends to form a gap cavity (321) between the outer sleeve (320) and the inner sleeve (310) between the protruding edges (312) at both ends.

17. The linear actuator according to claim 16, wherein, The outer wall of the inner sleeve (310) is coated with adhesive. By inserting the inner sleeve (310) into the outer sleeve (320), the adhesive coated on the outer wall of the inner sleeve (310) is contained and cured in the gap cavity (321) to achieve the fixation of the inner and outer sleeves (310).

18. The linear actuator according to claim 16, wherein, The nut is fixedly connected to the inner end (432) of the push rod (430). During the movement of the nut in the outer sleeve (320), the non-circular shaft of the push rod (430) continuously passes through the non-circular hole to limit the relative rotation between the nut and the outer sleeve (320). The non-circular hole is a square hole (333), and the non-circular shaft is a square shaft (435). The size of the square shaft (435) is basically equal to or slightly smaller than the size of the square hole (333).

19. The linear actuator according to claim 11, wherein, The nut in the lead screw and nut assembly (400) is a ball nut (420). The ball nut (420) includes a ball sleeve (421) and an internal threaded hole (422) disposed in the ball sleeve (421). The inner diameter of the internal threaded hole (422) is larger than the diameter of the lead screw (410) so that the lead screw (410) which is in drive engagement with the nut does not interfere when passing through the internal threaded hole (422).

20. The linear actuator according to claim 11, wherein, The diameter of the through hole in the first frame (231) is basically equal to or slightly larger than the diameter of the smooth rod part (412) of the lead screw (410) but smaller than the diameter of the lead screw part (411). The diameter of the through hole in the second frame (232) and the intermediate frame (233) is larger than the diameter of the lead screw part (411).

21. The linear actuator according to claim 13, wherein, The connection assembly (500) includes an end connector (501) and a spherical bearing (502) disposed within the end connector (501), wherein the end connector (501) is used to connect to the force sensor (610), the housing assembly (100) or the push rod (430), and the spherical bearing (502) is used to provide flexible external connection.

22. The linear actuator according to claim 10, wherein, The first frame (231), the second frame (232), and the intermediate frame (233) all have circumferential outer walls. The outer circumferential wall of the first frame (231) mates with the inner ring of the first bearing (701), and the outer ring of the first bearing (701) mates with the housing assembly (100). The smooth rod portion (412) of the lead screw (410) is inserted into the through hole of the first frame (231) so that the first bearing (701) provides the main support for the rotor support (230) and the lead screw (410).

23. The linear actuator according to claim 22 further includes a flange nut (704), which is screwed in through the external thread of the first end (413) to fix the inner ring of the first bearing (701) of the first frame (231) fitted into the rotor support (230), the outer peripheral wall of the second frame (232) mates with the inner ring of the second bearing (702), and the outer ring of the second bearing (702) mates with the guide assembly (300) so that the second bearing (702) provides secondary support to the rotor support (230).

24. The linear actuator according to claim 23, wherein, The first bearing (701) used as the main support is a double-row angular contact bearing; The second bearing (702), which serves as a secondary support, is a single-row ball bearing.

25. The linear actuator according to claim 10, wherein, The rotor support (230) includes a non-circular hole surface feature, and the lead screw (410) includes a non-circular shaft surface feature, wherein the non-circular hole surface feature and the non-circular shaft surface feature cooperate to transmit a larger torque when the rotor support (230) drives the lead screw (410) inserted therein to rotate.

26. The linear actuator according to claim 12, wherein, The housing assembly (100) is divided into a first housing (110) and a second housing (120) with bearings as spacers. The first housing (110) contains current elements with a working current value less than a preset current threshold, and the second housing (120) contains current elements with a working current value greater than the preset current threshold.

27. The linear actuator according to claim 10, wherein, The stator (210) is composed of coil windings, the rotor (220) contains magnets, and the rotor support (230) has a through hole that allows at least a portion of the lead screw (410) to pass through and be positioned so that the rotor support (230) and the lead screw (410) rotate together.

28. The linear actuator according to claim 13, wherein, The encoded signal receiver (631) and the encoded signal generator (633) are read heads and code disks of any form among magnetic, photoelectric, capacitive, and inductive types.

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