Linear actuator

Abstract

The utility model discloses a linear actuator which solves the technical problems that in the prior art, due to the fact that a lead screw is long, machining difficulty is increased, and 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 the lead screw is prevented from shaking.

Description

TECHNICAL FIELD

[0001] The utility model relates to linear actuator technical field especially relates to linear actuator. BACKGROUND

[0002] Linear actuator is widely used in various fields, including medical equipment, home office, solar power generation and so on. Linear actuator in prior art includes shell, actuating unit, screw rod and telescopic assembly, wherein actuating unit includes planetary gear assembly and motor installed in shell, motor drives screw rod to rotate through planetary gear assembly, telescopic assembly is driven by screw rod to make linear telescopic motion;Wherein screw rod extends through one end of shell, and the other end of screw rod is arranged through planetary gear assembly, tail pull component is installed on the other end of shell, and thrust bearing is arranged between tail pull component and the other end of screw rod, so that screw rod load thrust is transmitted to tail pull component through thrust bearing, and tail pull component bears more load thrust. It can be seen that screw rod needs to be arranged through planetary gear assembly in prior art, which will cause the length of screw rod to be lengthened, and thus the processing difficulty of screw rod is increased;In addition, the lengthening of screw rod also cannot guarantee the coaxiality during work, and is easy to produce shaking. SUMMARY

[0003] The utility model provides a linear actuator, which can avoid the need for screw rod to be arranged through the planetary gear assembly, thereby shortening the length of the screw rod, improving the processing convenience of the screw rod and the coaxiality during work, and avoiding shaking.

[0004] To solve the above technical problems, the utility model adopts the following technical scheme:

[0005] Linear actuator, comprising:

[0006] Screw rod;

[0007] Actuating unit, comprising motor and planetary gear assembly, the motor drives the screw rod to rotate reversely through the planetary gear assembly, the planetary gear assembly comprises a sun gear which is in transmission connection with the motor;

[0008] Shell, the planetary gear assembly is accommodated in the shell, the screw rod extends through one end of the shell, and a tail pull component is installed on the other end of the shell;

[0009] The linear actuator further comprises:

[0010] Support seat, comprising support part which axially penetrates the sun gear, the support part is in rotary cooperation with the sun gear, the support part 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 part.

[0011] The linear actuator in the utility model further includes a support seat, the support seat includes a support part axially penetrating the sun gear, the support part is in rotary cooperation with the sun gear, the support part is axially supported between the lead screw and the tail pulling part, and the lead screw load thrust is guided to the tail pulling part through the support part. In this way, the lead screw load thrust can be guided to the tail pulling part through the support part, so as to avoid that the planetary gear assembly bears the load thrust of the lead screw, and further avoid that the planetary gear assembly is damaged or the transmission efficiency is reduced. In addition, the lead screw does not need to penetrate the sun gear through the support part, that is, the lead screw does not need to penetrate the planetary gear assembly, so that the length of the lead screw can be shortened, the machining convenience and coaxiality of the lead screw during work can be improved, and the lead screw can be prevented from shaking.

[0012] In the linear actuator, the support part and the tail pulling part cooperatively define a containing cavity, the linear actuator further includes a transmission rod penetrating the support part and a sensor for detecting the rotation angle of the transmission rod, the transmission rod is in rotary cooperation with the support part, one end of the transmission rod is connected with the lead screw to keep synchronous rotation, and the other end extends into the containing cavity, the sensor includes an input shaft extending into the containing cavity, and the input shaft is in engagement with the transmission rod. In this way, since the rotation of the transmission rod drives the rotation of the input shaft, and the transmission rod and the lead screw rotate synchronously, the rotation angle of the transmission rod can be detected by the sensor through the rotation of the input shaft, and the rotation angle of the lead screw is detected, so that the extension stroke of the telescopic assembly can be detected in real time, and the user can accurately control the stroke of the telescopic assembly. In addition, the containing cavity 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, so that the structure is more compact.

[0013] In the linear actuator, the transmission rod includes a rod body synchronously rotating with the lead screw and a worm sleeve located in the containing cavity, the rod body penetrates the support part and is in rotary cooperation with the support part, the worm sleeve is sleeved outside the rod body and synchronously rotates with the rod body, and the input shaft is connected with a first worm wheel, and the first worm wheel is in engagement with the worm sleeve. In this way, the input shaft and the transmission rod are arranged at an angle of 90 degrees, so that the sensor occupies the radial space of the housing rather than the axial space of the housing, thereby shortening the axial height of the whole machine. In addition, the split structure of the transmission rod can reduce the machining difficulty of the transmission rod.

[0014] In the linear actuator, a positioning seat is installed in the containing cavity, the positioning seat is provided with a matching hole, and the worm sleeve is in rotary cooperation with the matching hole. In this way, the worm sleeve can be radially positioned by the positioning seat, so as to ensure that the worm sleeve, the rod body and the lead screw are coaxially arranged.

[0015] In the linear actuator, the rod body and the screw rod are axially fixedly connected, the rod body and the support are axially movably connected, the rod body and the worm sleeve are axially movably connected, the planetary gear assembly further comprises a planet carrier and a ring gear fixedly connected to the housing in the circumferential direction, the planet carrier is drivingly connected to the screw rod through a coupling, the coupling comprises a driving coupling, a driven coupling and a return spring, the driving coupling is drivingly connected to the planet carrier, the driven coupling is fixedly connected to the screw rod in the circumferential direction and axially fixedly connected to the housing, the driving coupling and the driven coupling are fixedly connected in the circumferential direction and movably connected in the axial direction, and the return spring is arranged on the driven coupling to keep the driven coupling in engagement with the driving coupling. In this way, when the actuating unit drives the inner tube of the telescopic assembly to retract and clamp an object or a human body, the screw rod drives the driven coupling and the transmission rod to move outward to disconnect the driven coupling from the driving coupling, so as to cut off the transmission of the actuating torque, the screw rod stops rotating, the inner tube stops retracting, and the anti-clamping effect is achieved; when the clamped object or human body is removed, the screw rod is reset under the action of the return spring to reconnect the driven coupling and the driving coupling, so that the linear actuator resumes normal operation.

[0016] In the linear actuator, the axial length of the rod body and the worm sleeve is L, the outer periphery of the rod body is provided with a limiting surface, the support is provided with a limiting step, the limiting step abuts against the limiting surface to limit the axial movement stroke of the screw rod when the screw rod moves outward relative to the housing, and the maximum movement stroke L1 of the screw rod when moving outward relative to the housing satisfies L1

[0017] In the linear actuator, a first radial bearing is further arranged between the screw rod and the housing, the return spring is arranged between the first radial bearing and the driven coupling, the axial distance between the driven coupling and the first radial bearing is L2 when the driven coupling and the driving coupling are in engagement, and L2

[0018] In the linear actuator, a brake torsion spring is further arranged outside the planet carrier in the housing, and a brake sleeve is further arranged outside the brake torsion spring and fixedly connected 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 actuating unit drives the screw rod to rotate forward, and the brake torsion spring is configured to expand to contact the brake sleeve to brake the screw rod when the screw rod is reversed under the action of a load. In this way, after the linear actuator drives the load to move to a specified position and the actuating unit stops working, the brake torsion spring can expand to contact the brake sleeve to brake the screw rod in reverse, so as to ensure the accuracy of the position of the load.

[0019] In the linear actuator, a plurality of transmission keys are arranged on the driving shaft in a circumferential direction, the planetary carrier is provided with a plurality of key grooves, the plurality of transmission keys are relatively rotatable engaged in the plurality of key grooves, the driving shaft and the planetary carrier are synchronous rotated after relatively rotating a predetermined angle, the brake torsion spring comprises a first pin connected with the planetary carrier and a second pin connected with the driving shaft, the second pin is driven to rotate to make the brake torsion spring contract when the driving unit drives the screw rod to rotate, the second pin is driven to rotate to make the brake torsion spring expand when the screw rod is reversed under the load, and the first pin is driven to rotate to make the brake torsion spring contract in the process of relatively rotating the driving shaft when the driving unit drives the screw rod to reverse. Thus, the planetary carrier is arranged to drive the brake torsion spring to contract and move away from the brake sleeve to avoid friction resistance when the driving unit drives the screw rod to reverse, and then the driving shaft is synchronous reversed to drive the screw rod to reverse and drive the load to drop, so that the load is not subjected to the friction resistance of the brake sleeve in the whole dropping process, and the power consumption of the motor is reduced.

[0020] In the linear actuator, the linear actuator further comprises a first thrust bearing, the first thrust bearing is axially supported between the support part and one end of the screw rod in the housing, and an axial gap exists between the first thrust bearing and the planetary gear assembly. Thus, the rotation of the screw rod relative to the support part is more smooth, the axial force can be borne by the first thrust bearing, the service life of the first thrust bearing is prolonged, and the sun gear is prevented from bearing the axial force.

[0021] In the linear actuator, the driving unit further comprises a meshed worm and a second worm gear, the second worm gear is sleeved outside the sun gear and synchronous rotated with the sun gear, the support seat further comprises a surrounding plate surrounding the outside of the second worm gear, 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 in transmission connection with the screw rod.

[0022] These features and advantages of the present application will be described in detail in the following specific embodiments and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0023] The present application will be further described below in combination with the drawings.

[0024] Figure 1 It is a structure schematic view of the linear actuator in the embodiment one of the present application.

[0025] Figure 2 It is a top view of the linear actuator in the embodiment one of the present application.

[0026] Figure 3 It is Figure 2 A-A sectional view in the embodiment one of the present application.

[0027] Figure 4 For Figure 3 Partial enlarged view of B in the middle;

[0028] Figure 5 For the explosion schematic view of the linear actuator part structure in the embodiment one of the utility model;

[0029] Figure 6 For the explosion schematic view of the planet carrier, brake torsional spring and shaft coupling in the embodiment one of the utility model;

[0030] Figure 7 For the front view of the linear actuator in the embodiment one of the utility model;

[0031] Figure 8 For Figure 7 Sectional view of C-C in the middle;

[0032] Figure 9 For Figure 8 Partial enlarged view of D in the middle;

[0033] Reference signs:

[0034] 100, screw rod; 110, check ring; 120, shaft shoulder; 200, actuating unit; 210, motor; 220, planetary gear assembly; 221, sun gear; 222, planetary gear; 223, planet carrier; 2230, notch; 22301, first side surface; 2231, transmission sleeve; 2232, key groove; 22321, first groove wall; 22322, second groove wall; 224, ring gear; 230, worm; 240, second worm gear; 300, housing; 310, tail pulling part; 320, first radial bearing; 330, first thrust bearing; 340, brake torsional spring; 341, first pin; 342, second pin; 350, brake sleeve; 360, 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, coaming; 600, transmission rod; 610, rod body; 611, limiting surface; 620, worm sleeve; 700, sensor; 710, input shaft; 711, first worm gear; 800, shaft coupling; 810, driving shaft coupling; 811, transmission key; 812, lug; 813, limiting sheet; 820, driven shaft coupling; 830, return spring;

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

DETAILED DESCRIPTION

[0036] The utility model provides linear actuator, comprising:

[0037] screw rod

[0038] an actuating unit comprising a motor and a planetary gear assembly, the motor driving the screw rod forward and reverse rotation through the planetary gear assembly, the planetary gear assembly comprising a sun gear in driving connection with the motor

[0039] a housing, the planetary gear assembly being housed in the housing, the screw rod extending out of one end of the housing, and a tail pulling component being mounted on the other end of the housing

[0040] the linear actuator further comprises:

[0041] a support seat comprising a support portion axially penetrating the sun gear, the support portion being in rotational cooperation with the sun gear, the support portion being axially supported between the screw rod and the tail pulling component, and the load thrust of the screw rod being guided to the tail pulling component through the support portion

[0042] The linear actuator in the utility model further comprises a support seat, the support seat comprises a support portion axially penetrating the sun gear, the support portion is in rotational cooperation with the sun gear, the support portion is axially supported between the screw rod and the tail pulling component, and the load thrust of the screw rod is guided to the tail pulling component through the support portion. In this way, the load thrust of the screw rod can be guided to the tail pulling component through the support portion, so as to avoid that the planetary gear assembly bears the load thrust of the screw rod, and further avoid that the planetary gear assembly is damaged or the transmission efficiency is reduced. In addition, the support portion penetrates the sun gear, so that the screw rod does not need to penetrate the sun gear and the planetary gear assembly, thereby the length of the screw rod can be shortened. The shortening of the length of the screw rod can improve the machining convenience and coaxiality during work, and avoid shaking.

[0043] The technical solutions of the embodiments of the utility model will be explained and described in combination with the drawings of the embodiments of the utility model. However, the following embodiments are only preferred embodiments of the utility model, not all. Based on the embodiments in the embodiments, other embodiments obtained by the person skilled in the art without creative labor all belong to the protection scope of the utility model. In addition, it should be understood that the words indicating the orientation or position relationship such as "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "vertical", "horizontal", "top", "bottom" and the like in the following description are only based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and cannot be understood as indicating or implying that the device / element must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as a limitation on the utility model.

[0044] Embodiment one

[0045] As Figures 1 to 9As shown, the linear actuator in the embodiment includes a screw rod 100, an actuating unit 200, a housing 300, a telescopic assembly 400 and a support base 500, wherein the actuating unit 200 includes a motor 210 and a planetary gear assembly 220, the motor 210 drives the screw rod 100 to rotate reversely 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 fixedly arranged in the inner tube 410 and is threadedly connected with the screw rod 100, the nut 430 is fixedly arranged in the circumferential direction and axially fixed relative to the inner tube 410, a load is connected to an end of the inner tube 410 which can be extended, and the telescopic assembly 400 can be extended and retracted by driving the inner tube 410 to move axially relative to the outer tube 420 through the screw rod 100 rotating reversely. The motor 210 and the planetary gear assembly 220 in the embodiment are both accommodated in the housing 300, wherein the planetary gear assembly 220 includes a sun gear 221 which is drivingly connected with the motor 210, the screw rod 100 extends through one end of the housing 300, a tail pulling component 310 is mounted to the other end of the housing 300, and the support base 500 includes a support portion 510 which axially penetrates the sun gear 221, the support portion 510 is rotatably matched with the sun gear 221, and the support portion 510 is axially supported between the screw rod 100 and the tail pulling component 310, and the screw rod load thrust F is guided to the tail pulling component 310 through the support portion 510. In this way, most of the screw rod load thrust F can be guided to the tail pulling component 310 through the support portion 510, so as to avoid the planetary gear assembly 220 from bearing the load thrust F of the screw rod, thereby avoiding the planetary gear assembly 220 from being damaged or reducing the transmission efficiency; and the screw rod 100 does not need to penetrate the sun gear 221, i.e. the screw rod 100 does not need to penetrate the planetary gear assembly 220, so that the length of the screw rod 100 can be shortened, the length of the screw rod 100 being shortened can improve the machining convenience and the coaxiality during working of the screw rod 100, and the screw rod 100 can be prevented from shaking.

[0046] Specifically, as Figure 4 and Figure 5As shown, the planetary gear assembly 220 in the embodiment further comprises a sun gear 221, a planet carrier 223 and a ring gear 224, the sun gear 221 is rotatably installed at the center of the planet carrier 223, a plurality of planet gears 222 are rotatably installed on the planet carrier 223, the plurality of planet gears 222 are arranged outside the sun gear 221 and mesh with the sun gear 221, and the ring gear 224 is arranged outside the plurality of planet gears 222 and meshes with the planet gears 222; wherein the ring gear 224 and the housing 300 can be connected by spline, welding or screw, so that the ring gear 224 and the housing 300 are fixed in the circumferential direction, and the planet carrier 223 is drivingly connected with the lead screw 100, so that the power of the motor 210 is input through the sun gear 221, transmitted by the planet gears 222 and output by the planet carrier 223, and the planet carrier 223 drives the lead screw 100 to rotate. By such design, the high-speed rotation of the motor 210 can be reduced to the required low speed by the planetary gear assembly 220 to adapt to the working requirements of the mechanical equipment.

[0047] The support part 510 in the embodiment comprises an upper support part 511 and a lower support part 512, the upper support part 511 extends upward and penetrates the sun gear 221, the top of the lower support part 512 is connected with the upper support part 511, the bottom of the lower support part 512 is supported on the tail pulling part 310, and the lower support part 512 cooperates with the tail pulling part 310 to define the accommodating cavity 001, the linear actuator further comprises a transmission rod 600 and a sensor 700 for detecting the rotation angle of the transmission rod 600, the support part 510 is provided with an axial through hole, and the transmission rod 600 is arranged through the through hole to realize that the transmission rod 600 penetrates the support part 510, the part of the transmission rod 600 cooperating with the upper support part 511 has a circular cross section, the through hole is a circular hole, and the transmission rod 600 is gap-fitted with the through hole to realize that the transmission rod 600 is rotationally fitted with the support part 510. One end of the transmission rod 600 is connected with the lead screw 100 to keep synchronous rotation, and the other end extends into the accommodating cavity 001, the sensor 700 is a rotary encoder or a potentiometer electrically connected with a controller, and comprises an input shaft 710 extending into the accommodating cavity 001, and the input shaft 710 meshes with the transmission rod 600. By such design, since the rotation of the transmission rod 600 drives the input shaft 710 to rotate, and the transmission rod 600 rotates synchronously with the lead screw 100, the rotation angle of the transmission rod 600 can be detected by the input shaft 710, and the rotation angle of the lead screw 100 can be detected, so that the extension stroke of the telescopic assembly 400 can be detected in real time, and the user can accurately control the stroke of the telescopic assembly 400. In addition, the provision of the accommodating cavity 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, so that the structure is more compact.

[0048] The transmission rod 600 in the embodiment comprises a rod body 610 and a worm sleeve 620. The rod body 610 is arranged through the upper support part 511. The upper end of the rod body 610 is connected with the lead screw 100 in a non-circular fitting mode (for example, fitting of spline or non-circular segment and non-circular hole) to keep 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. The worm sleeve 620 is connected with the rod body 610 in a non-circular fitting mode (for example, fitting of spline or non-circular segment and non-circular hole) to keep synchronous rotation. The input shaft 710 is connected with the first worm gear 711. The first worm gear 711 is engaged with the worm sleeve 620. In this way, the input shaft 710 and the transmission rod 600 are arranged at an angle of 90 degrees. The sensor 700 occupies the radial space of the shell 300 instead of the axial space of the shell 300. In this way, the axial height of the whole machine is shortened. Meanwhile, the split arrangement of the transmission rod 600 can also reduce the machining difficulty of the transmission rod 600.

[0049] In order to ensure that the transmission rod 600 and the lead screw 100 are coaxially arranged, the accommodating cavity 001 in the embodiment is provided with a positioning seat 520. The positioning seat 520 is clamped and fixed between the lower support part 512 and the tail pulling part 310. The positioning seat 520 is provided with a matching hole 521. The worm sleeve 620 is rotationally fitted with the matching hole 521. In this way, the worm sleeve 620 is radially positioned by the positioning seat 520 to ensure that the worm sleeve 620, the rod body 610 and the lead screw 100 are coaxially arranged.

[0050] In addition, the linear actuator in the embodiment further comprises a first thrust bearing 330. The first thrust bearing 330 is axially supported between the support part 510 and one end of the lead screw 100 located in the shell 300. 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 planet carrier 223 and the sun gear 221. The upper ends of the upper support part 511 and the sun gear 221 are respectively provided with an upper bearing 360 and a lower bearing 370. There is an axial gap between the outer ring of the first thrust bearing 330 and the upper bearing 360. The inner ring of the first thrust bearing 330 abuts against the upper bearing 360 to transmit the load thrust to the support part 510. In this way, the rotation of the lead screw 100 relative to the support part 510 is smoother. In addition, the axial force can be borne by the first thrust bearing 330 to prolong the service life of the first thrust bearing 330.

[0051] In order to make the linear actuator have the anti-pinch function, the rod body 610 and the screw rod 100 are connected in axial relative fixation in the embodiment, the lower end of the screw rod 100 is provided with a non-circular mounting hole, the rod body 610 is in interference fit with the mounting hole, so as to realize the connection of the rod body 610 and the screw rod 100 in circumferential relative fixation and axial relative fixation; and the rod body 610 and the support part 510, and the rod body 610 and the worm sleeve 620 are connected in axial relative movement, 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 are connected in transmission in the embodiment through the coupling 800, the coupling 800 includes a driving coupling 810, a driven coupling 820 and a reset spring 830, the driving coupling 810 is connected in transmission with the planet carrier 223 through the non-circular fit such as spline, the driven coupling 820 is connected in circumferential relative fixation with the screw rod 100 through the non-circular fit such as spline, and the driven coupling 820 is also connected in axial relative fixation with the screw rod 100, the driving coupling 810 and the driven coupling 820 are connected in circumferential relative fixation and axial relative movement through the non-circular fit such as spline. For example, the outer periphery of the driving coupling 810 is connected with the planet carrier 223 through spline, the driving coupling 810 is sleeved outside the driven coupling 820, and the inner periphery of the driving coupling 810 is connected with the outer periphery of the driven coupling 820 through spline, the driven coupling 820 is provided with a non-circular hole, the screw rod 100 has a non-circular segment matched with the non-circular hole, so as to realize the circumferential relative fixation of the driven coupling 820 and the screw rod 100; in addition, the end of the screw rod 100 is fixedly connected with a check ring 110, the outer diameter of the check ring 110 is greater than the inner diameter of the driven coupling 820 and smaller than the inner diameter of the driving coupling 810, so that the check ring 110 blocks the driven coupling 820 to limit the axial movement of the driven coupling 820; the outer periphery of the screw rod 100 is provided with a shaft shoulder 120, the driven coupling 820 is axially clamped and fixed between the shaft shoulder 120 and the check ring 110, so as to realize the axial relative fixation of the driven coupling 820 and the screw rod 100.

[0053] In order to ensure the rotation smoothness of the lead screw 100 and the coaxial degree with the transmission rod 600, the first radial bearing 320 is further arranged between the lead screw 100 and the shell 300 in the embodiment, the reset spring 830 is arranged between the first radial bearing 320 and the driven coupling 820, and the reset spring 830 acts on the driven coupling 820 to keep the driven coupling 820 in the engagement state with the driving coupling 810. In this way, when the actuating unit 200 drives the inner tube 410 to retract and clamp the object or the human body by driving the lead screw 100, the nut 430 cannot move axially, so that the lead screw 100 is forced to move axially outward relative to the nut 430, the lead screw 100 moves outward to drive the driven coupling 820 and the transmission rod 600 to move outward, so that the driven coupling 820 is disconnected with the driving coupling 810, the transmission of the actuating torque is cut off, the lead screw 100 stops rotating, the inner tube 410 stops retracting, and the anti-clamping effect is realized. When the clamped object or the human body is removed, the lead screw 100 is reset under the action of the reset spring 830 to reconnect the driven coupling 820 and the driving coupling 810, so that the linear actuator resumes normal operation.

[0054] In the normal state, the axial length of the matching part of the rod body 610 and the worm sleeve 620 is L, the outer circumferential side of the rod body 610 is provided with a limiting surface 611, a limiting step 5111 is arranged in the through hole, and the limiting step 5111 is located above the limiting surface 611. When the lead screw 100 moves outward, the limiting step 5111 can limit the axial movement stroke of the lead screw 100 relative to the shell 300 by abutting against the limiting surface 611, wherein the maximum movement stroke L1 of the lead screw 100 relative to the shell 300 when moving outward, that is, the maximum axial distance between the limiting surface 611 and the limiting step 5111 is L1, and L1 < L. In this way, the rod body 610 can be prevented from being separated from the worm sleeve 620 when the lead screw 100 moves outward relative to the shell 300, so that the rod body 610 and the worm sleeve 620 are always kept in transmission connection. Moreover, when the driven coupling 820 and the driving coupling 810 are in the engagement state, the axial distance between the driven coupling 820 and the first radial bearing 320 is L2, and L2 > L1. In this way, the driven coupling 820 can be prevented from colliding with the first radial bearing 320 when the lead screw 100 moves outward relative to the shell 300, so that the service life of the first radial bearing 320 is prolonged.

[0055] It can be understood that in other embodiments of the utility model, if the linear actuator does not have the anti-clamping function, that is, the driven coupling and the driving coupling are connected in the axial relative fixed manner, the rod body and the worm sleeve can be integrally machined and formed to form the transmission rod, and at this time, the transmission rod can be axially fixed relative to the support part.

[0056] Secondly, the actuating unit 200 in the embodiment further comprises a meshed worm 230 and a second worm wheel 240, the second worm wheel 240 is sleeved outside the sun gear 221 and synchronously rotates with the sun gear 221 through interference fit or spline fit, the support seat 500 further comprises a coaming 530 surrounding outside the second worm wheel 240, the coaming 530 is integrally processed and formed or welded with the support part 510, the coaming 530 is connected with the support part 510 and axially supports the annular gear 224 upwards, the top of the annular gear 224 abuts against the stepped surface of the housing 300, so that the axial position of the annular gear 224 is limited, and the worm 230 is arranged radially through the coaming 530 to mesh with the second worm wheel 240.

[0057] Finally, as shown in Figures 4 to 6 、 Figure 8 and Figure 9 , the housing 300 in the embodiment further comprises a brake torsion spring 340 and a brake sleeve 350, the brake torsion spring 340 is sleeved outside the planet carrier 223, the brake sleeve 350 is sleeved outside the brake torsion spring 340 and is fixed circumferentially opposite to the housing 300, that is, the brake sleeve 350 is circumferentially fixed opposite to the annular gear 224 through spline fit or integrally processed and formed, or the brake sleeve 350 is circumferentially fixed opposite to the housing 300 through spline fit or integrally processed or screw connection. The brake torsion spring 340 in the embodiment is configured to contract away from the brake sleeve 350 to release the brake when the actuating unit 200 drives the lead screw 100 to rotate forward, and expand to contact the brake sleeve 350 to brake the lead screw 100 when the lead screw 100 is reversed under load. In this way, 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 to contact the brake sleeve 350 to brake the lead screw 100, so as to ensure the accuracy of the position of the load.

[0058] The plurality of transmission keys 811 are arranged on the outer circumferential side of the driving coupling 810 in a circumferential direction at intervals, the top of the planet carrier 223 is provided with a transmission sleeve 2231 extending upward, the brake torsion spring 340 is sleeved on the outer side of the transmission sleeve 2231, the inner side wall of the transmission sleeve 2231 is uniformly provided with a plurality of protrusions in a circumferential direction at intervals, a key groove 2232 is formed between two adjacent protrusions, the central angle corresponding to the key groove 2232 is greater than the central angle corresponding to the transmission key 811, so that the plurality of transmission keys 811 are relatively rotatably engaged in the plurality of key grooves 2232, and the driving coupling 810 and the planet carrier 223 are synchronously rotated after relatively rotating by a predetermined angle. The spiral direction of the brake torsion spring 340 is the same as the positive rotation direction of the screw rod 100, the brake torsion spring 340 includes a first pin 341 located below and a second pin 342 located above, the transmission sleeve 2231 is provided with a notch 2230 in communication with the key groove 2232, the first pin 341 is arranged through the notch 2230, and the first pin 341 is located below the transmission key 811, so as to realize the connection between the first pin 341 and the planet carrier 223 while avoiding interference with the transmission key 811, and the second pin 342 is connected with the driving coupling 810, that is, the top of the outer circumferential side of the driving coupling 810 is provided with two lugs 812 arranged at intervals, the second pin 342 is inserted between the two lugs 812, so as to realize the connection between the second pin 342 and the driving coupling 810.

[0059] As Figure 8As shown, the keyway 2232 has oppositely arranged first and second slot walls 22321 and 22322, when the telescopic assembly 400 is in the shortest state, the first slot wall 22321 and the transmission key 811 have a first gap 002, and the second slot wall 22322 abuts against the transmission key 811, at this time, the first pin 341 and the first side 22301 of the notch 2230 have a second gap 003, when the motor 210 drives the lead screw 100 to rotate in the positive direction through the planetary gear assembly 220 and the shaft coupling 800, the planet carrier 223 rotates relative to the driving shaft coupling 810 to eliminate the first gap 002 and make the second slot wall 22322 and the transmission key 811 have a third gap, and then the planet carrier 223 drives the driving shaft coupling 810 to rotate in the positive direction synchronously to make the second pin 342 rotate in the positive direction and the brake torsional spring 340 contract, when the lead screw 100 reverses under the action of the load, the driving shaft coupling 810 drives the planet carrier 223 to reverse synchronously, at this time, the second pin 342 is driven to reverse to make the brake torsional spring 340 expand to contact the brake sleeve 350 to realize friction self-locking; when the motor 210 drives the lead screw 100 to reverse through the planetary gear assembly 220 and the shaft coupling 800, the planet carrier 223 rotates relative to the driving shaft coupling 810 to eliminate the third gap between the second slot wall 22322 and the transmission key 811 and make the first slot wall 22321 and the transmission key 811 have a first gap 002, in the process of eliminating the third gap, the first pin 341 is driven to reverse to make the brake torsional spring 340 contract, and then the planet carrier 223 drives the driving shaft coupling 810 to reverse synchronously, that is, when the actuating unit 200 drives the lead screw 100 to reverse, the planet carrier 223 is first driven to drive the brake torsional spring 340 to contract away from the brake sleeve 350 to avoid the contact between the two to generate friction resistance, and then the driving shaft coupling 810 is driven to reverse synchronously to make the lead screw 100 reverse to drive the load to descend, so that the lead screw 100 does not suffer from the friction resistance applied by the brake sleeve during the whole descending process, and the power consumption of the motor 210 is reduced.

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

[0061] It can be understood that in other embodiments of the utility model, the gear ring can also be connected with the lead screw through a shaft coupling, at this time, the planet carrier is fixed circumferentially relative to the shell.

[0062] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited to this, and those skilled in the art should understand that the utility model includes but is not limited to the contents described in the drawings and the above specific implementation. Any modification not deviating from the function and structural principle of the utility model will be included in the scope of claims.

Claims

1. A linear actuator comprising: a screw rod; an actuating unit comprising a motor and a planetary gear assembly, the motor driving the screw rod to rotate in opposite directions through the planetary gear assembly, the planetary gear assembly comprising a sun gear in driving connection with the motor; a housing, the planetary gear assembly being accommodated in the housing, the screw rod extending out of one end of the housing, and a tail pulling component being mounted on the other end of the housing; characterized in that the linear actuator further comprises: a support seat comprising a support portion axially penetrating the sun gear, the support portion being in rotational cooperation with the sun gear, the support portion being axially supported between the screw rod and the tail pulling component, and the load thrust of the screw rod being guided to the tail pulling component through the support portion.

2. The linear actuator of claim 1, wherein, the support portion and the tail pulling component cooperatively defining a receiving cavity, the linear actuator further comprising a transmission rod penetrating the support portion and a sensor for detecting the rotation angle of the transmission rod, the transmission rod being in rotational cooperation with the support portion, one end of the transmission rod being connected with the screw rod to keep synchronous rotation, the other end of the transmission rod extending into the receiving cavity, and the sensor comprising an input shaft extending into the receiving cavity, the input shaft being in engagement with the transmission rod.

3. The linear actuator of claim 2, wherein, the transmission rod comprising a rod body keeping synchronous rotation with the screw rod and a worm sleeve located in the receiving cavity, the rod body penetrating the support portion and being in rotational cooperation with the support portion, the worm sleeve being sleeved outside the rod body and keeping synchronous rotation with the rod body, and the input shaft being connected with a first worm gear, the first worm gear being in engagement with the worm sleeve.

4. The linear actuator of claim 3, wherein, a positioning seat being mounted in the receiving cavity, the positioning seat being provided with a cooperation hole, and the worm sleeve being in rotational cooperation with the cooperation hole.

5. The linear actuator of claim 3, wherein, the rod body and the screw rod being in axial relative fixed connection, the rod body and the support portion, and the rod body and the worm sleeve being in axial relative movable connection, the planetary gear assembly further comprising a planet carrier and a ring gear fixed in the circumferential direction relative to the housing, the planet carrier being in driving connection with the screw rod through a coupling, the coupling comprising a driving coupling, a driven coupling and a reset spring, the driving coupling being in driving connection with the planet carrier, the driven coupling being in circumferential relative fixed and axial relative fixed connection with the screw rod, the driving coupling and the driven coupling being in circumferential relative fixed and axial relative movable connection, and the reset spring acting on the driven coupling to keep the driven coupling in engagement with the driving coupling.

6. The linear actuator of claim 5, wherein, an axial length of the cooperation part of the rod body and the worm sleeve being L, a limiting surface being provided on the outer circumferential side of the rod body, a limiting step being provided in the support portion, the limiting step being in abutment with the limiting surface to limit the axial movement stroke of the screw rod when moving outward relative to the housing, and the maximum movement stroke L1 of the screw rod when moving outward relative to the housing satisfying L1 < L.

7. The linear actuator of claim 6, wherein, a first radial bearing being further provided between the screw rod and the housing, the reset spring being provided between the first radial bearing and the driven coupling, the axial distance between the driven coupling and the first radial bearing being L2 when the driven coupling and the driving coupling are in engagement, and L2 satisfying L2 > L1.

8. The linear actuator of claim 5, wherein, The housing is further provided with a brake torsion spring sleeved outside the planet carrier and a brake sleeve sleeved outside the brake torsion spring and fixed opposite to the housing in the circumferential direction, the brake torsion spring is configured to contract away from the brake sleeve to release the brake when the actuating unit drives the screw rod to rotate forward, and expand to contact the brake sleeve to brake the screw rod when the screw rod is reversed under load.

9. The linear actuator of claim 8, wherein, The plurality of transmission keys are arranged on the driving shaft in the circumferential direction, the planet carrier is provided with a plurality of key grooves, the plurality of transmission keys are relatively rotatable engaged in the plurality of key grooves, so that the driving shaft and the planet carrier are synchronously rotated after relatively rotating by a predetermined angle, the brake torsion spring comprises a first pin connected with the planet carrier and a second pin connected with the driving shaft, the actuating unit drives the second pin to rotate to contract the brake torsion spring when the screw rod is driven to rotate forward, and drives the second pin to rotate to expand the brake torsion spring when the screw rod is reversed under load, the planet carrier drives the first pin to rotate to contract the brake torsion spring when the screw rod is reversed by the actuating unit.

10. The linear actuator of claim 1, wherein, The linear actuator further comprises a first thrust bearing 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 of claim 1, wherein, The actuating unit further comprises an engaged worm and a second worm gear, the second worm gear is sleeved outside the sun gear and synchronously rotates with the sun gear, the support seat further comprises a surrounding plate surrounding the outside of the second worm gear, the ring gear of the planetary gear assembly is axially supported between the surrounding plate and the housing, and the planet carrier of the planetary gear assembly is in transmission connection with the screw rod.

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