Linear actuator

Abstract

The invention discloses a linear actuator which solves the technical problems that in the prior art, due to the fact that a lead screw is long, the machining difficulty is increased, and the coaxiality cannot be guaranteed. The actuating unit comprises a motor and a planet wheel assembly, the motor drives the lead screw to rotate forwards and backwards through the planet wheel assembly, and the planet wheel assembly comprises a sun wheel in transmission connection with the motor; the planet wheel assembly is contained in the shell, the lead screw extends out of one end of the shell, and a tail pulling component is installed at the other end of the shell. And the supporting seat comprises a supporting part axially penetrating through the sun gear, the supporting part is in running fit with the sun gear, the supporting part is axially supported between the lead screw and the tail pulling component, and the lead screw loads thrust to be guided to the tail pulling component through the supporting part. According to the linear actuator, the lead screw does not need to penetrate through the planet wheel assembly, so that the length of the lead screw is shortened, the machining convenience of the lead screw and the coaxiality of the lead screw during working are improved, and shaking of the lead screw is avoided.

Description

[Technical field]

[0001] The present invention relates to the technical field of linear actuators, and in particular to linear actuators. [Background technology]

[0002] Linear actuators are widely used in various fields, including medical equipment, home office, solar power generation, etc. The linear actuator in the prior art includes a housing, an actuating unit, a screw and a telescopic assembly, wherein the actuating unit includes a planetary gear assembly and a motor installed in the housing, the motor drives the screw to rotate through the planetary gear assembly, and the telescopic assembly is driven by the screw to perform linear telescopic movement; wherein the screw extends through one end of the housing, and the other end of the screw passes through the planetary gear assembly, and a tail pull component is installed at the other end of the housing, and a thrust bearing is provided between the tail pull component and the other end of the screw, thereby allowing the screw load thrust to be transmitted to the tail pull component through the thrust bearing, so that the tail pull component bears more load thrust. It can be seen from this that the screw in the prior art needs to pass through the planetary gear assembly, which will cause the length of the screw to be lengthened, thereby increasing the difficulty of processing the screw; in addition, the lengthening of the screw cannot guarantee the coaxiality during operation, and it is easy to cause shaking. [Summary of the invention]

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a linear actuator that does not require a screw rod to pass through the planetary gear assembly, thereby shortening the length of the screw rod, thereby improving the processing convenience of the screw rod and the coaxiality during operation, and avoiding shaking.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] Linear actuators, including:

[0006] Screw rod;

[0007] The actuating unit comprises a motor and a planetary gear assembly, wherein the motor drives the screw rod to rotate forward and reversely through the planetary gear assembly, and the planetary gear assembly comprises a sun gear drivingly connected to the motor;

[0008] A housing, wherein the planetary gear assembly is accommodated in the housing, the screw rod extends out through one end of the housing, and a tail pull component is installed at the other end of the housing;

[0009] The linear actuator further comprises:

[0010] The support seat comprises a support portion axially penetrating the sun gear, the support portion rotatably cooperates with the sun gear, the support portion is axially supported between the screw rod and the tail pull component, and the screw rod load thrust is guided to the tail pull component through the support portion.

[0011] The linear actuator in the present invention also includes a support seat, which includes a support portion that axially penetrates the sun gear, the support portion is rotatably matched with the sun gear, the support portion is axially supported between the screw and the tail pull component, and the screw load thrust is guided to the tail pull component through the support portion. In this way, the screw load thrust can be guided to the tail pull component through the support portion to avoid the planetary gear assembly from bearing the screw load thrust, thereby avoiding damage to the planetary gear assembly or reducing the transmission efficiency; and the support portion can penetrate the sun gear so that the screw does not need to penetrate the sun gear setting, that is, the screw does not need to penetrate the planetary gear assembly, thereby achieving the purpose of shortening the screw length. The shortening of the screw length can improve the processing convenience of the screw and the coaxiality during operation, and avoid its shaking.

[0012] In the above linear actuator, the support part cooperates with the tail pull component to define a receiving chamber, and the linear actuator also includes a transmission rod penetrating the support part and a sensor for detecting the rotation angle of the transmission rod, the transmission rod is rotationally matched with the support part, one end of the transmission rod is connected to the screw rod to maintain synchronous rotation, and the other end extends into the receiving chamber, and the sensor includes an input shaft extending into the receiving chamber, and the input shaft is meshed with the transmission rod. With such a design, since the rotation of the transmission rod drives the input shaft to rotate, and the transmission rod and the screw rod rotate synchronously, the rotation angle of the transmission rod can be detected by the sensor through the rotation of the input shaft, and then the rotation angle of the screw rod can be detected, so that the telescopic stroke of the telescopic assembly can be detected in real time, which is convenient for users to accurately control the stroke of the telescopic assembly; in addition, the setting of the receiving chamber not only provides space for the installation of the input shaft, but also avoids the interference of the input shaft with the planetary gear assembly, making the structure more compact.

[0013] In the above linear actuator, the transmission rod includes a rod body that keeps synchronous rotation with the lead screw and a worm sleeve located in the accommodating cavity, the rod body penetrates the support part and rotates with the support part, the worm sleeve is sleeved on the outside of the rod body and keeps synchronous rotation with the rod body, and the input shaft is connected with a first worm gear, which is meshed with the worm sleeve. With such a design, the input shaft and the transmission rod can be arranged at 90 degrees, so that the sensor occupies the radial space of the housing instead of the axial space of the housing, thereby shortening the axial height of the whole machine; at the same time, the split arrangement of the transmission rod can also reduce the difficulty of processing the transmission rod.

[0014] In the above linear actuator, a positioning seat is installed in the accommodating cavity, the positioning seat is provided with a matching hole, and the worm sleeve is rotationally matched with the matching hole. With such a design, the positioning seat can be used to radially position the worm sleeve to ensure that the worm sleeve, the rod body and the lead screw are coaxially arranged.

[0015] In the above-mentioned linear actuator, the rod body and the screw rod form an axially relatively fixed connection, the rod body and the support part, and the rod body and the worm sleeve all form an axially relatively movable connection, the planetary gear assembly also includes a planetary carrier and a gear ring fixed circumferentially relative to the housing, the planetary carrier and the screw rod are connected by a coupling, the coupling includes a driving coupling, a driven coupling and a reset spring, the driving coupling is connected to the planetary carrier, the driven coupling and the screw rod form a circumferentially relatively fixed and axially relatively fixed connection, the driving coupling and the driven coupling form a circumferentially relatively fixed and axially relatively movable connection, and the reset spring acts on the driven coupling to keep it engaged with the driving coupling. With such a design, when the actuating unit drives the lead screw to retract the inner tube of the telescopic assembly and clamps an object or a person, the lead screw will drive the driven coupling and the transmission rod to move outward to disconnect the driven coupling from the active coupling, thereby cutting off the transmission of the actuating torque. The lead screw stops rotating and the inner tube stops retracting, thereby achieving an anti-pinch effect. When the clamped object or person is removed, the lead screw is reset under the action of the reset spring to reconnect the driven coupling and the active coupling, thereby allowing the linear actuator to resume normal operation.

[0016] In the above linear actuator, the axial length of the mating part of the rod body and the worm sleeve is L, a limiting surface is provided on the outer peripheral side of the rod body, and a limiting step is provided in the support portion, and the limiting step and the limiting surface abut against each other to limit the axial movement stroke of the screw rod when it moves outward relative to the housing, and the maximum movement stroke L1 of the screw rod when it moves outward relative to the housing satisfies L1<L. Such a design can prevent the rod body from being separated from the worm sleeve when the screw rod moves outward relative to the housing, thereby ensuring that the rod body and the worm sleeve always maintain a transmission connection.

[0017] In the above linear actuator, a first radial bearing is further provided between the screw and the housing, the return spring is provided between the first radial bearing and the driven coupling, the driven coupling and the driving coupling are in an engaged state, and the axial distance between the driven coupling and the first radial bearing is L2, satisfying L2>L1. Such a design can prevent the driven coupling from colliding with the first radial bearing when the screw moves outward relative to the housing, thereby extending the service life of the first radial bearing.

[0018] In the above linear actuator, the housing is further provided with a brake torsion spring sleeved on the outside of the planet carrier and a brake sleeve sleeved on the outside of the brake torsion spring and fixed relative to the housing in the circumferential direction. The brake torsion spring is configured to contract and move away from the brake sleeve to release the brake when the actuator unit drives the lead screw to rotate forward, and to expand outward and contact with the brake sleeve to apply reverse braking to the lead screw when the lead screw is reversed under the action of the load. With such a design, after the linear actuator drives the load to move to the specified position and the actuator unit stops working, the brake torsion spring can expand outward and contact with the brake sleeve to apply reverse braking to the lead screw, so as to ensure the accuracy of the load position.

[0019] In the above linear actuator, a plurality of transmission keys are arranged circumferentially at intervals on the active coupling, and a plurality of key slots are provided on the planet carrier. The plurality of transmission keys can be relatively rotatably engaged in the plurality of key slots, so that the active coupling and the planet carrier generate synchronous rotation after relative rotation at a predetermined angle. The brake torsion spring includes a first pin connected to the planet carrier and a second pin connected to the active coupling. When the actuating unit drives the screw to rotate forward, the second pin is driven to rotate to shrink the brake torsion spring. When the screw is reversed under the action of the load, the second pin is driven to rotate to expand the brake torsion spring. When the actuating unit drives the screw to reverse, the planet carrier drives the first pin to rotate in the process of rotating relative to the active coupling to shrink the brake torsion spring. With such a design, when the actuating unit drives the screw to reverse, the planet carrier can first drive the brake torsion spring to shrink away from the brake sleeve to avoid friction resistance caused by contact between the two, and then the active coupling is driven to reverse synchronously to make the screw reverse and drive the load to descend. Therefore, the friction resistance applied by the brake sleeve will not be applied during the entire descending process, thereby reducing the power consumption of the motor.

[0020] In the above linear actuator, the linear actuator further comprises a first thrust bearing, the first thrust bearing is axially supported between the support portion and one end of the screw rod located in the housing, and there is an axial gap between the first thrust bearing and the planetary gear assembly. Such a design can make the screw rod rotate more smoothly relative to the support portion; in addition, the first thrust bearing can also be used to bear the axial force, thereby extending the service life of the first thrust bearing, and finally, it can also prevent the sun gear from bearing the axial force.

[0021] In the above-mentioned linear actuator, the actuating unit also includes a meshing worm and a second worm wheel, the second worm wheel is sleeved on the outside of the sun wheel and rotates synchronously with the sun wheel, the support seat also includes a surrounding plate surrounding the outside of the second worm wheel, the ring gear of the planetary gear assembly is axially supported between the surrounding plate and the housing, and the planetary carrier of the planetary gear assembly is connected to the screw transmission.

[0022] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and drawings.

Brief Description of the Drawings

[0023] The present invention will be further described below in conjunction with the accompanying drawings:

[0024] Figure 1 Schematic diagram of the structure of the linear actuator in Embodiment 1 of the present invention;

[0025] Figure 2 is a top view of the linear actuator in the first embodiment of the present invention;

[0026] Figure 3 for Figure 2 Sectional view of AA in the middle;

[0027] Figure 4 for Figure 3 A partial enlarged schematic diagram of B in the middle;

[0028] Figure 5 It is an exploded schematic diagram of a partial structure of a linear actuator in Embodiment 1 of the present invention;

[0029] Figure 6 It is an exploded schematic diagram of the planet carrier, the brake torsion spring and the coupling in the first embodiment of the present invention;

[0030] Figure 7 It is a front view of the linear actuator in the first embodiment of the present invention;

[0031] Figure 8 for Figure 7 Cross-sectional view of CC;

[0032] Fig. 9 for Figure 8 A partial enlarged schematic diagram of D in the middle;

[0033] Reference numerals:

[0034] 100, screw rod; 110, retaining ring; 120, shoulder; 200, actuating unit; 210, motor; 220, planetary gear assembly; 221, sun gear; 222, planetary gear; 223, planetary carrier; 2230, notch; 22301, first side surface; 2231, transmission sleeve; 2232, keyway; 22321, first groove wall; 22322, second groove wall; 224, gear ring; 230, worm; 240, second worm gear; 300, housing; 310, tail pull component; 320, first radial bearing; 330, first thrust bearing; 340, brake torsion spring; 341, first pin; 342, second pin; 350, brake sleeve; 36 0, upper bearing; 370, lower bearing; 400, telescopic assembly; 410, inner tube; 420, outer tube; 430, nut; 500, support seat; 510, support part; 511, upper support part; 5111, limiting step; 512, lower support part; 520, positioning seat; 521, matching hole; 530, enclosure; 600, transmission rod; 610, rod body; 611, limiting surface; 620, worm sleeve; 700, sensor; 710, input shaft; 711, first worm gear; 800, coupling; 810, active coupling; 811, transmission key; 812, lug; 813, limiting piece; 820, driven coupling; 830, reset spring;

[0035] 001, accommodating cavity; 002, first gap; 003, second gap. [Specific implementation method]

[0036] The present invention provides a linear actuator, comprising:

[0037] Screw rod;

[0038] The actuating unit comprises a motor and a planetary gear assembly, wherein the motor drives the screw rod to rotate forward and reversely through the planetary gear assembly, and the planetary gear assembly comprises a sun gear drivingly connected to the motor;

[0039] A housing, wherein the planetary gear assembly is accommodated in the housing, the screw rod extends out through one end of the housing, and a tail pull component is installed at the other end of the housing;

[0040] The linear actuator further comprises:

[0041] The support seat comprises a support portion axially penetrating the sun gear, the support portion rotatably cooperates with the sun gear, the support portion is axially supported between the screw rod and the tail pull component, and the screw rod load thrust is guided to the tail pull component through the support portion.

[0042] The linear actuator in the present invention also includes a support seat, which includes a support portion that axially penetrates the sun gear, the support portion is rotatably matched with the sun gear, the support portion is axially supported between the screw and the tail pull component, and the screw load thrust is guided to the tail pull component through the support portion. In this way, the screw load thrust can be guided to the tail pull component through the support portion to avoid the planetary gear assembly from bearing the screw load thrust, thereby avoiding damage to the planetary gear assembly or reducing the transmission efficiency; and the support portion can penetrate the sun gear so that the screw does not need to penetrate the sun gear setting, that is, the screw does not need to penetrate the planetary gear assembly, thereby achieving the purpose of shortening the screw length. The shortening of the screw length can improve the processing convenience of the screw and the coaxiality during operation, and avoid its shaking.

[0043] The technical solutions of the embodiments of the present invention are explained and illustrated below in conjunction with the drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments of the present invention, not all of them. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work all belong to the protection scope of the present invention. In addition, it should be understood that the following words indicating orientation or position relationship such as "up", "down", "left", "right", "longitudinal", "lateral", "inside", "outside", "vertical", "horizontal", "top", "bottom", etc. are only based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0044] Embodiment 1

[0045] like Figures 1 to 9As shown, the linear actuator in this embodiment includes a screw 100, an actuating unit 200, a housing 300, a telescopic assembly 400 and a support seat 500, wherein the actuating unit 200 includes a motor 210 and a planetary gear assembly 220, the motor 210 drives the screw 100 to rotate forward and reverse through the planetary gear assembly 220, the telescopic assembly 400 includes an inner tube 410, an outer tube 420 and a nut 430, the nut 430 is fixed in the inner tube 410 and is threadedly connected to the screw 100, the nut 430 is circumferentially and axially fixed relative to the inner tube 410, the load is connected to the extendable end of the inner tube 410, and the forward and reverse rotation of the screw 100 can realize driving the inner tube 410 to move axially relative to the outer tube 420 to enable the telescopic assembly 400 to telescope. The motor 210 and the planetary gear assembly 220 in this embodiment are both accommodated in the housing 300, wherein the planetary gear assembly 220 includes a sun gear 221 transmission-connected to the motor 210, the screw rod 100 extends out through one end of the housing 300, and a tail pull component 310 is installed at the other end of the housing 300, and the support seat 500 includes a support portion 510 axially penetrating the sun gear 221, the support portion 510 is rotationally matched with the sun gear 221, and the support portion 510 is axially supported between the screw rod 100 and the tail pull component 310, and the screw rod load thrust F is guided to the tail pull component 310 through the support portion 510. In this way, most of the screw load thrust F can be guided to the tail pull component 310 through the support part 510 to prevent the planetary gear assembly 220 from bearing the screw load thrust F, thereby preventing the planetary gear assembly 220 from being damaged or reducing the transmission efficiency; and the support part 510 can penetrate the sun gear 221 so that the screw 100 does not need to penetrate the sun gear 221, that is, the screw 100 does not need to penetrate the planetary gear assembly 220, thereby achieving the purpose of shortening the length of the screw 100. The shortening of the length of the screw 100 can improve the processing convenience and coaxiality of the screw 100 during operation, and avoid its shaking.

[0046] Specifically, Figure 4 and Figure 5As shown, the planetary gear assembly 220 in this embodiment also includes a planetary gear 222, a planetary carrier 223 and a ring gear 224, the sun gear 221 is rotatably mounted at the center of the planetary carrier 223, a plurality of planetary gears 222 are rotatably mounted on the planetary carrier 223, a plurality of planetary gears 222 surround the outside of the sun gear 221 and mesh with the sun gear 221, and the ring gear 224 surrounds the outside of the plurality of planetary gears 222 and meshes with the planetary gears 222; wherein, the ring gear 224 and the housing 300 can be splined or welded or screwed so that the ring gear 224 and the housing 300 are relatively fixed in the circumferential direction, and the planetary carrier 223 is connected to the screw 100 in a transmission manner, so that the power of the motor 210 is input through the sun gear 221, and then output by the planetary carrier 223 after being transmitted by the planetary gear 222, and the planetary carrier 223 drives the screw 100 to rotate. With such a design, the high-speed rotation of the motor 210 can be reduced to the required low speed through the planetary gear assembly 220 to meet the working requirements of the mechanical equipment.

[0047] The support portion 510 in this embodiment includes an upper support portion 511 and a lower support portion 512. The upper support portion 511 extends upward and passes through the sun gear 221. The top of the lower support portion 512 is connected to the upper support portion 511. The bottom of the lower support portion 512 is supported on the tail pull component 310, and the lower support portion 512 cooperates with the tail pull component 310 to define a accommodating cavity 001. The linear actuator also includes a transmission rod 600 and a sensor 700 for detecting the rotation angle of the transmission rod 600. The support portion 510 is provided with an axially penetrating through hole. The transmission rod 600 is arranged to pass through the through hole to realize that the transmission rod 600 passes through the support portion 510. The cross-section of the portion of the transmission rod 600 that cooperates with the upper support portion 511 is circular, and the through hole is a circular hole. The transmission rod 600 is clearance-matched with the through hole so that the transmission rod 600 and the support portion 510 can rotate and cooperate. One end of the transmission rod 600 is connected to the screw rod 100 to keep synchronous rotation, and the other end extends into the accommodating chamber 001. The sensor 700 is a rotary encoder or potentiometer electrically connected to the controller, which includes an input shaft 710 extending into the accommodating chamber 001, and the input shaft 710 is meshed with the transmission rod 600. In this design, since the rotation of the transmission rod 600 drives the input shaft 710 to rotate, and the transmission rod 600 and the screw rod 100 rotate synchronously, the rotation of the input shaft 710 can be used to detect the rotation angle of the transmission rod 600, and then detect the rotation angle of the screw rod 100, so that the telescopic stroke of the telescopic assembly 400 can be detected in real time, which is convenient for users to accurately control the stroke of the telescopic assembly 400; in addition, the setting of the accommodating chamber 001 not only provides space for the installation of the input shaft 710 of the sensor 700, but also avoids the interference of the input shaft 710 with the planetary gear assembly 220, making the structure more compact.

[0048] The transmission rod 600 in this embodiment includes a rod body 610 and a worm sleeve 620, the rod body 610 is arranged to pass through the upper support portion 511, the upper end of the rod body 610 is connected to the lead screw 100 by a non-circular matching manner (for example, a spline or a non-circular segment and a non-circular hole) to maintain synchronous rotation, the lower end of the rod body 610 extends into the accommodating cavity 001, the worm sleeve 620 is located in the accommodating cavity 001 and is sleeved on the lower end of the rod body 610, wherein the worm sleeve 620 is connected to the rod body 610 by a non-circular matching manner (for example, a spline or a non-circular segment and a non-circular hole) to maintain synchronous rotation, and the input shaft 710 is connected to a first worm gear 711, and the first worm gear 711 is meshed with the worm sleeve 620. With this design, the input shaft 710 and the transmission rod 600 can be set at 90 degrees, so that the sensor 700 occupies the radial space of the shell 300 rather than the axial space of the shell 300, thereby shortening the axial height of the whole machine; at the same time, the split setting of the transmission rod 600 can also reduce the difficulty of processing the transmission rod 600.

[0049] In order to ensure that the transmission rod 600 and the screw 100 are coaxially arranged, a positioning seat 520 is installed in the accommodating cavity 001 in this embodiment. The positioning seat 520 is clamped and fixed between the lower support portion 512 and the tail pull component 310. The positioning seat 520 is provided with a matching hole 521, and the worm sleeve 620 is rotatably matched with the matching hole 521. With such a design, the positioning seat 520 can be used to radially position the worm sleeve 620 to ensure that the worm sleeve 620, the rod body 610 and the screw 100 are coaxially arranged.

[0050] In addition, the linear actuator in this embodiment further includes a first thrust bearing 330, which is axially supported between the support portion 510 and one end of the screw rod 100 located in the housing 300, and there is an axial gap between the first thrust bearing 330 and the planetary gear assembly 220, that is, there is an axial gap between the first thrust bearing 330 and the planetary carrier 223 and the sun gear 221, and an upper bearing 360 and a lower bearing 370 are respectively provided between the two ends of the upper support portion 511 and the sun gear 221, wherein there is an axial gap between the first thrust bearing 330 and the outer ring of the upper bearing 360, and the first thrust bearing 330 and the inner ring of the upper bearing 360 are against each other to transfer the load thrust to the support portion 510. Such a design can make the screw rod 100 rotate more smoothly relative to the support portion 510; in addition, the first thrust bearing 330 can also be used to withstand the axial force, thereby extending the service life of the first thrust bearing 330.

[0051] In order to make the linear actuator have an anti-pinch function, in this embodiment, the rod body 610 and the screw rod 100 form an axially relatively fixed connection, and the lower end of the screw rod 100 is provided with a non-circular mounting hole. The rod body 610 and the mounting hole are interference fit to achieve a circumferentially relatively fixed and axially relatively fixed connection between the rod body 610 and the screw rod 100; and the rod body 610 and the support part 510, as well as the rod body 610 and the worm sleeve 620, all form an axially relatively movable connection, that is, the rod body 610 can move axially relative to the support part 510 and the worm sleeve 620.

[0052] The planet carrier 223 and the screw rod 100 in this embodiment are connected in transmission via a coupling 800. The coupling 800 includes a driving coupling 810, a driven coupling 820 and a reset spring 830. The driving coupling 810 and the planet carrier 223 are connected in transmission via a non-circular matching method such as a spline. The driven coupling 820 and the screw rod 100 are connected in a circumferentially relatively fixed manner via a non-circular matching method such as a spline, and the driven coupling 820 and the screw rod 100 are also connected in an axially relatively fixed manner. The driving coupling 810 and the driven coupling 820 are connected in a circumferentially relatively fixed manner and in an axially relatively movable manner via a non-circular matching method such as a spline. For example, the outer circumference of the active coupling 810 is splined with the planet carrier 223, the active coupling 810 is sleeved on the outside of the driven coupling 820, and the inner circumference of the active coupling 810 is splined with the outer circumference of the driven coupling 820, the driven coupling 820 is provided with a non-circular hole, and the screw 100 has a non-circular section that matches the non-circular hole, so that the driven coupling 820 and the screw 100 are relatively fixed in the circumferential direction; in addition, the end of the screw 100 is fixed A retaining ring 110 is fixedly connected, and the outer diameter of the retaining ring 110 is larger than the inner diameter of the driven coupling 820 and smaller than the inner diameter of the driving coupling 810, so that the retaining ring 110 blocks the driven coupling 820 to limit its lower position in the axial direction; a shoulder 120 is provided on the outer peripheral side of the screw rod 100, and the driven coupling 820 is axially clamped and fixed between the shoulder 120 and the retaining ring 110, so as to realize the axially relatively fixed connection between the driven coupling 820 and the screw rod 100.

[0053] In order to ensure the smooth rotation of the screw rod 100 and its coaxiality with the transmission rod 600, in this embodiment, a first radial bearing 320 is further provided between the screw rod 100 and the housing 300, and a return spring 830 is provided between the first radial bearing 320 and the driven coupling 820. The return spring 830 acts on the driven coupling 820 to keep it engaged with the active coupling 810. With such a design, when the actuating unit 200 drives the lead screw 100 to retract the inner tube 410 and thereby clamps an object or a human body, since the nut 430 cannot move axially, the lead screw 100 is forced to move axially outward relative to the nut 430. The outward movement of the lead screw 100 drives the driven coupling 820 and the transmission rod 600 to move outward, thereby disconnecting the driven coupling 820 from the active coupling 810 to cut off the transmission of the actuating torque, and the lead screw 100 stops rotating and the inner tube 410 stops retracting, thereby achieving an anti-pinch effect. When the clamped object or human body is removed, the lead screw 100 is reset under the action of the reset spring 830, so that the driven coupling 820 and the active coupling 810 are reconnected, thereby allowing the linear actuator to resume normal operation.

[0054] Under normal conditions, the axial length of the mating portion of the rod body 610 and the worm sleeve 620 is L, a limiting surface 611 is provided on the outer peripheral side of the rod body 610, and a limiting step 5111 is provided in the through hole, and the limiting step 5111 is located above the limiting surface 611. When the screw rod 100 moves outward, the limiting step 5111 and the limiting surface 611 abut against each other to limit the axial movement stroke of the screw rod 100 when it moves outward relative to the housing 300, wherein the maximum movement stroke L1 when the screw rod 100 moves outward relative to the housing 300, that is, the maximum axial distance between the limiting surface 611 and the limiting step 5111 is L1, satisfying L1<L. Such a design can prevent the rod body 610 from being separated from the worm sleeve 620 when the screw rod 100 moves outward relative to the housing 300, thereby ensuring that the rod body 610 and the worm sleeve 620 always maintain a transmission connection. Furthermore, when the driven coupling 820 and the driving coupling 810 are in the engaged state, the axial distance between the driven coupling 820 and the first radial bearing 320 is L2, satisfying L2>L1. This design can prevent the driven coupling 820 from colliding with the first radial bearing 320 when the screw rod 100 moves outward relative to the housing 300, thereby extending the service life of the first radial bearing 320.

[0055] It can be understood that in other embodiments of the present invention, if the linear actuator does not have an anti-pinch function, that is, when the driven coupling and the active coupling form an axially relatively fixed connection, the rod body and the worm sleeve can be integrally processed to form a transmission rod, and the transmission rod can be axially fixed relative to the support part.

[0056] Secondly, the actuating unit 200 in this embodiment also includes a meshing worm 230 and a second worm wheel 240. The second worm wheel 240 is sleeved on the outside of the sun gear 221 and realizes synchronous rotation with the sun gear 221 through interference fit or spline fit. The support seat 500 also includes a surrounding plate 530 surrounding the outside of the second worm wheel 240. The surrounding plate 530 and the support part 510 are integrally processed or welded. The surrounding plate 530 is connected to the support part 510 and axially supports the ring gear 224 upward. The top of the ring gear 224 is against the step surface of the shell 300, so that the axial limitation of the ring gear 224 can be achieved. The worm 230 radially penetrates the surrounding plate 530 to engage with the second worm wheel 240.

[0057] Finally, if Figures 4 to 6 , Figure 8 and Fig. 9 As shown, the housing 300 in this embodiment is further provided with a brake torsion spring 340 and a brake sleeve 350. The brake torsion spring 340 is sleeved on the outside of the planet carrier 223, and the brake sleeve 350 is sleeved on the outside of the brake torsion spring 340 and is relatively fixed to the housing 300 in the circumferential direction, that is, the brake sleeve 350 and the gear ring 224 can be relatively fixed to the circumferential direction by spline matching or integral processing; or the brake sleeve 350 and the housing 300 are relatively fixed to the circumferential direction by spline matching or integral processing or screw connection. The brake torsion spring 340 in this embodiment is configured to shrink and move away from the brake sleeve 350 to release the brake when the actuator unit 200 drives the screw rod 100 to rotate forward, and expand outward and contact with the brake sleeve 350 when the screw rod 100 is reversed under the action of load to implement reverse braking on the screw rod 100. With such a design, after the linear actuator drives the load to move to a specified position and the actuating unit 200 stops working, the brake torsion spring 340 can expand outward to contact the brake sleeve 350 to implement reverse braking on the screw rod 100 to ensure the accuracy of the load position.

[0058] A plurality of transmission keys 811 are circumferentially spaced apart on the outer circumferential side of the active coupling 810, a transmission sleeve 2231 extending upward is provided on the top of the planet carrier 223, a brake torsion spring 340 is sleeved on the outside of the transmission sleeve 2231, a plurality of protrusions are evenly spaced apart on the inner wall of the transmission sleeve 2231, a keyway 2232 is formed between two adjacent protrusions, a central angle corresponding to the keyway 2232 is greater than a central angle corresponding to the transmission key 811, so that the plurality of transmission keys 811 can be relatively rotatably engaged in the plurality of keyways 2232, so that the active coupling 810 and the planet carrier 223 can generate synchronous rotation after relative rotation at a predetermined angle. The spiral direction of the brake torsion spring 340 is the same as the forward rotation direction of the lead screw 100. The brake torsion spring 340 includes a first pin 341 located at the bottom and a second pin 342 located at the top. The transmission sleeve 2231 is provided with a notch 2230 connected to the key slot 2232. The first pin 341 is arranged to pass through the notch 2230, and the first pin 341 is located below the transmission key 811 to achieve the connection between the first pin 341 and the planetary carrier 223 while avoiding interference with the transmission key 811, and the second pin 342 is connected to the active coupling 810, that is, two spaced-apart lugs 812 are provided on the top of the outer peripheral side of the active coupling 810, and the second pin 342 is inserted between the two lugs 812 to achieve the connection between the second pin 342 and the active coupling 810.

[0059] like Figure 8As shown, the key slot 2232 has a first slot wall 22321 and a second slot wall 22322 that are arranged opposite to each other. When the telescopic assembly 400 is in the shortest state, there is a first gap 002 between the first slot wall 22321 and the transmission key 811, and the second slot wall 22322 abuts against the transmission key 811. At this time, there is a second gap 003 between the first pin 341 and the first side surface 22301 of the notch 2230. The motor 210 drives the screw rod 100 through the planetary gear assembly 220 and the coupling 800. When rotating forward, the planet carrier 223 first rotates relative to the active coupling 810 to eliminate the first gap 002 and form a third gap between the second groove wall 22322 and the transmission key 811. Then, the planet carrier 223 drives the active coupling 810 to rotate forward synchronously to rotate the second pin 342 forward and thus contract the brake torsion spring 340. When the screw rod 100 is reversed under the load, the active coupling 810 drives the planet carrier 223 to reverse synchronously, and at this time, the second pin 342 is driven to reverse to expand the brake torsion spring 340. Contact with the brake sleeve 350 realizes friction self-locking; when the motor 210 drives the screw rod 100 to reverse through the planetary gear assembly 220 and the coupling 800, the planetary carrier 223 first rotates relative to the active coupling 810 to eliminate the third gap between the second groove wall 22322 and the transmission key 811 and to create a first gap 002 between the first groove wall 22321 and the transmission key 811. In the process of the planetary carrier 223 rotating relative to the active coupling 810 to eliminate the third gap, the first pin 341 is driven to reverse to shrink the brake torsion spring 340, and then the planetary carrier 223 drives the active coupling 810 to reverse synchronously. That is, when the actuating unit 200 drives the screw rod 100 to reverse, the planetary carrier 223 first drives the brake torsion spring 340 to shrink away from the brake sleeve 350 to avoid friction resistance caused by contact between the two, and then the active coupling 810 is driven to reverse synchronously to make the screw rod 100 reverse and drive the load to descend. Therefore, the friction resistance applied by the brake sleeve will not be applied during the entire descent process, thereby reducing the power consumption of the motor 210.

[0060] In order to axially limit the braking torsion spring 340 , one of the lugs 812 in this embodiment is provided with a limiting piece 813 extending radially outward, and the braking torsion spring 340 is axially limited between the limiting piece 813 and the planet carrier 223 .

[0061] It is understandable that in other embodiments of the present invention, the ring gear may also be connected to the screw through a coupling, and in this case the planet carrier is circumferentially fixed relative to the housing.

[0062] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes but is not limited to the contents described in the drawings and the above specific embodiments. Any modification that does not deviate from the functional and structural principles of the present invention will be included in the scope of the claims.

Claims

1. Linear actuator, including: Screw rod; The actuating unit comprises a motor and a planetary gear assembly, wherein the motor drives the screw rod to rotate forward and reversely through the planetary gear assembly, and the planetary gear assembly comprises a sun gear drivingly connected to the motor; A housing, wherein the planetary gear assembly is accommodated in the housing, the screw rod extends out through one end of the housing, and a tail pull component is installed at the other end of the housing; Characterized in that the linear actuator also includes: The support seat comprises a support portion axially penetrating the sun gear, the support portion rotatably cooperates with the sun gear, the support portion is axially supported between the screw rod and the tail pull component, and the screw rod load thrust is guided to the tail pull component through the support portion.

2. The linear actuator according to claim 1, characterized in that The support portion cooperates with the tail pull component to define a accommodating cavity. The linear actuator also includes a transmission rod passing through the support portion and a sensor for detecting the rotation angle of the transmission rod. The transmission rod is rotationally coordinated with the support portion. One end of the transmission rod is connected to the screw rod to maintain synchronous rotation, and the other end extends into the accommodating cavity. The sensor includes an input shaft extending into the accommodating cavity, and the input shaft is meshed with the transmission rod.

3. The linear actuator according to claim 2, characterized in that The transmission rod includes a rod body that rotates synchronously with the lead screw and a worm sleeve located in the accommodating cavity, the rod body passes through the supporting part and rotates with the supporting part, the worm sleeve is arranged on the outside of the rod body and rotates synchronously with the rod body, and the input shaft is connected to a first worm wheel, which is meshed with the worm sleeve.

4. The linear actuator according to claim 3, characterized in that A positioning seat is installed in the accommodating cavity, the positioning seat is provided with a matching hole, and the worm sleeve is rotationally matched with the matching hole.

5. The linear actuator according to claim 3, characterized in that The rod body and the screw rod form an axially relatively fixed connection, the rod body and the support part, and the rod body and the worm sleeve all form an axially relatively movable connection, the planetary gear assembly also includes a planet carrier and a gear ring fixed circumferentially relative to the housing, the planet carrier and the screw rod are connected by a coupling, the coupling includes a driving coupling, a driven coupling and a reset spring, the driving coupling is connected to the planet carrier, the driven coupling and the screw rod form a circumferentially relatively fixed and axially relatively fixed connection, the driving coupling and the driven coupling form a circumferentially relatively fixed and axially relatively movable connection, and the reset spring acts on the driven coupling to keep it engaged with the driving coupling.

6. The linear actuator according to claim 5, characterized in that The axial length of the mating part of the rod body and the worm sleeve is L, a limiting surface is provided on the outer peripheral side of the rod body, and a limiting step is provided in the support portion. The limiting step and the limiting surface are abutted against each other to limit the axial movement stroke of the screw rod when it moves outward relative to the housing. The maximum movement stroke L1 of the screw rod when it moves outward relative to the housing satisfies L1<L.

7. The linear actuator according to claim 6, characterized in that A first radial bearing is also provided between the screw rod and the housing, and the reset spring is provided between the first radial bearing and the driven coupling. When the driven coupling and the driving coupling are in an engaged state, the axial distance between the driven coupling and the first radial bearing is L2, satisfying L2>L1.

8. The linear actuator according to claim 5, characterized in that The housing is also provided with a brake torsion spring sleeved on the outside of the planetary carrier and a brake sleeve sleeved on the outside of the brake torsion spring and fixed relative to the circumference of the housing. The brake torsion spring is constructed to contract and move away from the brake sleeve to release the brake when the actuator unit drives the screw rod to rotate forward, and to expand outward and contact the brake sleeve to apply reverse braking to the screw rod when the screw rod is reversed under the action of a load.

9. The linear actuator according to claim 8, characterized in that The active coupling is provided with a plurality of transmission keys at intervals in the circumferential direction, the planet carrier is provided with a plurality of key slots, the plurality of transmission keys can be relatively rotatably engaged in the plurality of key slots, so that the active coupling and the planet carrier generate synchronous rotation after relative rotation by a predetermined angle, the brake torsion spring comprises a first pin connected to the planet carrier and a second pin connected to the active coupling, the actuating unit drives the second pin to rotate when the lead screw rotates forward to contract the brake torsion spring, and drives the second pin to rotate when the lead screw is reversed under the action of a load to expand the brake torsion spring, and when the actuating unit drives the lead screw to reverse, the planet carrier drives the first pin to rotate during the relative rotation process of the active coupling to contract the brake torsion spring.

10. The linear actuator according to claim 1, characterized in that The linear actuator further includes a first thrust bearing, which is axially supported between the support portion and one end of the screw rod located in the housing, and an axial gap exists between the first thrust bearing and the planetary gear assembly.

11. The linear actuator according to claim 1, characterized in that The actuating unit also includes a meshing worm and a second worm wheel, wherein the second worm wheel is sleeved on the outside of the sun wheel and rotates synchronously with the sun wheel, and the support seat also includes a surrounding plate surrounding the outside of the second worm wheel, the ring gear of the planetary gear assembly is axially supported between the surrounding plate and the housing, and the planetary carrier of the planetary gear assembly is connected to the screw transmission.

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