Linear actuator and displacer

Abstract

The utility model discloses linear actuator, including motor, drive unit, screw rod, outer tube and inner tube subassembly, and the inner tube subassembly is driven by screw rod rotation and is linear telescopic motion relative to outer tube, drive unit is including the transmission wheel that is equipped with first transmission part, and screw rod axial penetration transmission wheel and is equipped with second transmission part, and first transmission part and second transmission part cooperate to make screw rod and transmission wheel synchronous rotation and can axial opposite shift, still include permanent magnet, and the axial sliding of along screw rod is installed on outer tube and is relative to the fixed circumference of outer tube, and permanent magnet is connected with screw rod and keeps the relative rotation of circumference and axial opposite fixed, magnetic induction element, fixed in outer tube and is connected with control unit, and when screw rod moves to the direction of inner tube subassembly extension, drives permanent magnet to move and triggers magnetic induction element to produce induction signal, and control unit controls motor to stop operation according to induction signal. In addition, the utility model discloses still adopts the shifter of above-mentioned linear actuator.

Description

Technical Field

[0001] This utility model relates to the field of linear drive technology, and in particular to linear actuators and shifters. Background Technology

[0002] Linear actuators are currently widely used in various fields, including medical equipment, home and office applications, and solar power generation. A typical linear actuator structure includes a motor, a transmission unit, a lead screw, an outer tube, and an inner tube assembly. The inner tube assembly consists of an inner tube and a transmission nut. The motor drives the lead screw to rotate via the transmission unit. The rotation of the lead screw drives the transmission nut to move relative to the outer tube, causing the inner tube assembly to perform linear extension and retraction. This, in turn, drives an object connected to the inner tube assembly to move linearly, achieving the actuation purpose. To control the extension and retraction stroke of the inner tube assembly, two limit switches electrically connected to the control unit are installed inside the outer tube. These two limit switches are spaced apart along the radial side of the inner tube in the direction of extension and retraction. When the inner tube assembly moves linearly along the lead screw axis, the transmission nut triggers one of the limit switches. The triggered limit switch transmits a signal to the control unit, which then controls the motor to stop rotating based on the signal, thereby limiting the extension and retraction stroke of the inner tube assembly or determining its position.

[0003] If the inner tube assembly encounters an obstacle during retraction without triggering the two limit switches, it will be unable to continue moving. Since the motor is still driving the lead screw to rotate, the current will rise sharply, far exceeding the normal operating current, indicating that the motor is burning out or the transmission unit is failing under the huge torque. In addition, forcibly retracting the inner tube assembly by driving it with the motor will also put enormous pressure on the obstacle (such as a person or object), which will lead to damage to the obstacle, the inner tube, and the outer tube.

[0004] To address the aforementioned technical problems, a linear actuator is disclosed in the prior art, comprising: a motor; a transmission wheel driven to rotate by the motor; a lead screw driven to rotate by the transmission wheel; and a tubular telescopic component driven by the rotational motion of the lead screw to perform linear telescopic motion. The transmission wheel includes a transmission hole, and the lead screw includes a transmission section, which engages with the transmission hole and maintains circumferential synchronous rotation while allowing axial relative movement. This allows the lead screw to move towards the extension direction of the tubular telescopic component when subjected to axial tensile load, thereby axially separating the transmission section and the transmission hole and cutting off the power transmission between the transmission wheel and the lead screw. An elastic component acts on the lead screw to maintain its force state towards the retraction direction of the tubular telescopic component. This design, when the tubular telescopic component retracts and encounters an obstacle, forces the lead screw to move in the direction of the extension of the tubular telescopic component, causing the transmission section and transmission hole to separate axially. This cuts off the power transmission between the motor and the lead screw, allowing the transmission wheel to idle under the motor's drive. The lead screw then prevents the tubular telescopic component from moving, avoiding further retraction that could crush or damage obstacles (such as people or objects), and also preventing damage to the motor. However, because the linear actuator lacks a mechanism to detect obstacles, the motor remains idle, resulting in ineffective wear of the motor and transmission wheel, as well as wasted electrical energy. Utility Model Content

[0005] To address the technical problem in the prior art where the inner tube assembly retracts and encounters an obstacle, causing the lead screw to move axially and cut off the power input, but the motor continues to run, this invention provides a linear actuator and shifter. After the inner tube assembly retracts and encounters an obstacle, the movement of the lead screw triggers a magnetic induction element to stop the motor, thereby reducing ineffective wear on the motor and transmission unit and saving energy.

[0006] To achieve the above-mentioned technical objectives, the linear actuator provided by this utility model includes: a motor, a transmission unit, a lead screw, an outer tube, an inner tube assembly, and an elastic component. The lead screw is driven to rotate by the power transmitted by the transmission unit, and the inner tube assembly is driven by the rotation of the lead screw to perform linear extension and retraction relative to the outer tube. The transmission unit includes a transmission wheel with a first transmission part, the lead screw axially passes through the transmission wheel and has a second transmission part, the first transmission part and the second transmission part cooperate to make the lead screw and the transmission wheel rotate synchronously and move axially relative to each other, so that after the inner tube assembly retracts and encounters resistance, the lead screw is allowed to move in the direction of extension of the inner tube assembly, thereby causing the second transmission part to axially separate from the first transmission part and cutting off the power transmission between the lead screw and the transmission wheel; the elastic component is used to maintain the connection tendency of the first transmission part and the second transmission part. Linear actuators also include: The permanent magnet is slidably mounted on the outer tube along the axis of the lead screw and is circumferentially fixed relative to the outer tube. The permanent magnet is connected to the lead screw and maintains relative circumferential rotation and relative axial fixation. A magnetic induction element is fixed inside the outer tube and connected to the control unit. When the lead screw moves in the direction of the extension of the inner tube assembly, it drives the permanent magnet to move and triggers the magnetic induction element to generate an induction signal. The control unit controls the motor to stop running according to the induction signal.

[0007] Preferably, the lead screw is fitted with a spacer ring that rotates synchronously and is axially fixed. The outer periphery of the spacer ring is provided with an annular positioning groove. An installation ring is rotatably fitted in the positioning groove. The installation ring is axially slidably mounted on the outer tube and is circumferentially fixed relative to the outer tube. The permanent magnet is disposed on the installation ring.

[0008] Preferably, the outer circumferential side of the mounting ring is provided with a limiting part, which cooperates with the inner wall groove of the outer tube to keep the mounting ring and the outer tube circumferentially fixed and axially movable.

[0009] Preferably, the magnetic sensing element is a reed switch or a Hall sensor.

[0010] Preferably, the linear actuator further includes a switch bar extending along the screw axis inside the outer tube and two limit switches mounted on the switch bar for limiting the extension and retraction of the inner tube assembly. The control unit is located on the switch bar and electrically connected to the two limit switches.

[0011] Preferably, the control unit includes a first circuit board and a second circuit board disposed on opposite sides of the switch bar and electrically connected thereto. The second circuit board is disposed on the side of the switch bar facing the inner tube assembly. The Hall sensor is disposed on the second circuit board. The first circuit board is electrically connected to two limit switches.

[0012] Preferably, the first transmission part is a transmission hole through which the lead screw passes axially, the lead screw has a transmission section, the transmission section constitutes the second transmission part, and the transmission hole cooperates with the transmission section to enable the lead screw and the transmission wheel to rotate synchronously and move axially relative to each other.

[0013] Preferably, the first transmission part is a driving coupling and the second transmission part is a driven coupling. When the driving coupling and the driven coupling are connected, they remain relatively fixed in the circumferential direction and can move relatively in the axial direction.

[0014] Preferably, the end of the transmission wheel away from the inner tube assembly is provided with a clearance hole for the lead screw to pass through, the tail end of the lead screw is provided with a stop plate, the end of the clearance hole away from the tail end of the lead screw is provided with a first stepped surface, and the elastic component is sleeved on the outside of the lead screw and pressed between the first stepped surface and the stop plate.

[0015] In addition, this utility model also provides a shifter, including a base and a boom rotatably connected to the base. The shifter also includes the linear actuator described in any of the above technical solutions. One end of the linear actuator is hinged to the base, and the inner tube assembly is hinged to the boom. The telescopic movement of the inner tube assembly drives the boom to rise and fall.

[0016] By adopting the above technical solution, this utility model has the following advantages: 1. During the use of the linear actuator of this utility model, if the inner tube assembly encounters resistance (i.e., encounters an obstacle) during retraction, the inner tube assembly cannot continue to move, and the motor continues to drive the lead screw to rotate through the transmission unit. Therefore, the motor will drive the lead screw to move relative to the inner tube assembly in the direction of the inner tube assembly's extension, overcoming the force of the elastic component. This allows the first and second transmission parts to separate axially, cutting off the power transmission between the transmission wheel and the lead screw. At this time, the motor and transmission wheel enter an idle state, meaning they will not drive the inner tube assembly to continue retracting. This avoids the inner tube assembly continuing to retract and causing crushing damage to the obstacle, achieving an anti-pinch effect and mechanical protection. In addition, the movement of the lead screw in the direction of the inner tube assembly's extension will drive the permanent magnet to move, triggering the magnetic induction element to generate an induction signal. The control unit controls the motor to stop based on the induction signal. This reduces ineffective wear on the motor and transmission unit, extending their service life and further saving energy. Furthermore, since the linear actuator is in a stopped state, it prevents further damage that could occur from repeated attempts to operate or subsequent operations without removing obstacles. Additionally, after the motor stops and the obstacle is removed, the inner tube assembly and lead screw can reset under load and elastic components, allowing the first and second transmission parts to re-engage and transmit power between the lead screw and the transmission wheel, enabling the linear actuator to function normally again. Finally, the triggering method using a permanent magnet to trigger the magnetic induction element is non-contact, with no physical contact or mechanical wear parts. Moreover, because the speed at which the magnetic field change is sensed is in the microsecond range, the response speed is extremely fast.

[0017] 2. A spacer ring is fitted on the outer side of the lead screw, rotating synchronously and axially fixed. An annular positioning groove is provided on the outer circumference of the spacer ring, and a mounting ring is rotatably fitted within the positioning groove. The mounting ring is axially slidably mounted on the outer tube and circumferentially fixed relative to the outer tube. The permanent magnet is mounted on the mounting ring. This design allows the mounting ring to serve as a mounting carrier for the permanent magnet, facilitating its installation. It also ensures the connection between the permanent magnet and the lead screw, maintaining circumferential rotation and axial fixation. Furthermore, if the mounting ring were directly mounted on the circumferential groove of the lead screw and rotated with it, the requirements for the lead screw's machining accuracy, strength, and wear resistance would be extremely high. This solution, by designing a spacer ring, allows for the use of a different material than the lead screw, resulting in higher wear resistance and protecting the structural integrity and strength of the lead screw. Additionally, the spacer ring can be machined separately, making manufacturing precision easier to control and potentially lowering costs. If wear occurs, only the spacer ring needs to be replaced, eliminating the need to replace the expensive lead screw.

[0018] 3. A limiting part is provided on the outer circumference of the mounting ring. The limiting part cooperates with the groove on the inner wall of the outer tube to keep the mounting ring and the outer tube circumferentially fixed and axially movable. With this design, by limiting the mounting ring to be circumferentially fixed relative to the outer tube and allowing it to move axially relative to the outer tube, the permanent magnet can be slidably mounted on the outer tube along the axis of the lead screw and fixed circumferentially relative to the outer tube. Finally, since the permanent magnet is completely restricted and cannot rotate relative to the outer tube but can rotate relative to the positioning groove (i.e., the lead screw), every axial movement of the lead screw will ensure that the permanent magnet triggers the magnetic induction element, avoiding slippage or missed triggering of the magnetic induction element due to rotation.

[0019] 4. The linear actuator also includes a switch bar extending axially along the lead screw inside the outer tube, and two limit switches mounted on the switch bar to limit the extension and retraction of the inner tube assembly. The control unit is located on the switch bar and electrically connected to the two limit switches. By using the existing control unit electrically connected to the magnetic induction element, there is no need to set up a separate control unit, thereby simplifying the structure of the linear actuator.

[0020] 5. The control unit includes a first circuit board and a second circuit board, which are located on opposite sides of the switch bar and electrically connected. The second circuit board is located on the side of the switch bar facing the inner tube assembly. The Hall sensor is mounted on the second circuit board. The first circuit board is electrically connected to two limit switches. Because the power required to drive the load is high, a MOSFET is needed when the required current exceeds the capacity of the Hall sensor. However, due to the size limitations of the existing first circuit board, it is impossible to add more electrical components. Therefore, by adding a second circuit board to mount the Hall sensor, the installation requirements of the Hall sensor can be met.

[0021] 6. The first transmission part is a transmission hole through which the lead screw passes axially. The lead screw has a transmission section, which constitutes the second transmission part. The transmission hole and the transmission section cooperate to enable the lead screw and the transmission wheel to rotate synchronously and move axially relative to each other. With this design, synchronous rotation and axial relative movement of the two can be achieved by changing the shape of the lead screw section and the shape of the hole section of the transmission wheel, without the need for other transmission components. This effectively reduces the number of parts, improves assembly efficiency, and reduces manufacturing costs.

[0022] 7. The first transmission unit is a driving coupling, and the second transmission unit is a driven coupling. When the driving coupling and the driven coupling are connected, they remain circumferentially fixed but can move axially relative to each other. This design improves the stability of power transmission when the driving coupling and the driven coupling are connected, and also allows the driving coupling and the driven coupling to easily separate axially when encountering resistance, making the axial separation action very sensitive. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the linear actuator in Embodiment 1 of this utility model; Figure 2 This is a perspective sectional view of the linear actuator in Embodiment 1 of this utility model; Figure 3 for Figure 2 The front view; Figure 4 for Figure 3 A magnified view of part A in the diagram; Figure 5 for Figure 3 Sectional view of BB; Figure 6 This is a partial exploded view of the linear actuator in Embodiment 1 of this utility model; Figure 7 This is a schematic diagram of the transmission wheel in Embodiment 1 of this utility model; Figure 8 This is a cross-sectional view of the transmission wheel in Embodiment 1 of this utility model; Figure 9 This is a schematic diagram of the gasket structure in Embodiment 1 of this utility model; Figure 10 This is a schematic diagram of the spacer structure in Embodiment 1 of this utility model; Figure 11 This is a schematic diagram of the mounting ring in Embodiment 1 of this utility model; Figure 12 This is a partial structural diagram of the lead screw in Embodiment 1 of this utility model; Figure 13 This is a schematic diagram of the control unit in Embodiment 1 of this utility model; Figure 14This is a structural diagram of the transmission wheel and the drive coupling integrally formed in Embodiment 2 of this utility model; Figure 15 This is an exploded view of the linear actuator portion of the structure in Embodiment 2 of this utility model; Figure 16 This is a cross-sectional view of the transmission wheel and the drive coupling integrally formed in Embodiment 2 of this utility model; Figure 17 This is a schematic diagram of the driven coupling in Embodiment 2 of this utility model; Figure 18 This is a schematic diagram of the spacer structure in Embodiment 2 of this utility model; Figure 19 This is a partial structural diagram of the lead screw in Embodiment 2 of this utility model; Figure 20 This is a partial structural cross-sectional view of the linear actuator in Embodiment 2 of this utility model; Figure 21 This is a schematic diagram of the shifter in Embodiment 3 of this utility model; In the diagram, 100 is the motor; 200 is the lead screw; 201 is the threaded section; 202 is the transmission section; 203 is the cylindrical section; 204 is the non-circular section; 210 is the second transmission part; 211 is the non-circular hole; 212 is the second rib; 220 is the spacer; 221 is the positioning groove; 230 is the stop plate; 240 is the washer; 241 is the positioning shoulder; 242 is the rib; 250 is the washer; 260 is the mounting ring; 261 is the limiting part; 262 is the radial protrusion; 300 is the outer tube; 31 is the outer tube. 0. First guide groove; 320. Switch bar; 330. Limit switch; 400. Inner tube assembly; 410. Inner tube; 420. Transmission nut; 430. Guide ring; 500. Transmission unit; 510. Worm gear; 520. Transmission wheel; 521. First transmission part; 522. Guide sleeve; 524. Clearance hole; 600. Elastic component; 700. Permanent magnet; 800. Magnetic induction element; 900. Control unit; 910. First circuit board; 920. Second circuit board; 1. Base; 2. Crane arm. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the terms "upper," "lower," "left," "right," "longitudinal," "lateral," "inner," "outer," "vertical," "horizontal," "top," and "bottom," etc., which indicate orientation or positional relationship, are based solely on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing the present invention and simplifying the description. They do not indicate or imply that the device / component referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Example 1

[0025] Combination Figures 1 to 13 The linear actuator provided in this embodiment includes a motor 100, a lead screw 200, an outer tube 300, an inner tube assembly 400, and a transmission unit 500. The output shaft of the motor 100 is connected to the transmission unit 500. The lead screw 200 is driven to rotate by the power transmitted by the transmission unit 500. The inner tube assembly 400 includes an inner tube 410 and a transmission nut 420. The transmission nut 420 is installed at one end of the inner tube 410 near the transmission unit 500. A guide ring 430 is rotatably sleeved on the outer side of the transmission nut 420. The guide ring 430 is axially fixed relative to the transmission nut 420. One end of the transmission nut 420 is inserted into the inner tube 410 and threadedly connected to the inner tube 410. The other end is provided with a shoulder that abuts against the end of the inner tube 410. This allows the transmission nut 420 to be connected to the inner tube 410 and... The guide ring 430 is circumferentially and axially fixed. The outer circumferential side of the guide ring 430 is provided with first ribs extending axially along the lead screw 200. The inner wall of the outer tube 300 is provided with a first guide groove 310 that matches the first ribs. The first guide groove 310 allows the first ribs to move axially. In this way, the inner tube assembly 400 and the outer tube 300 are connected in a circumferentially relative rotation and axially relative sliding connection through the cooperation of the first guide groove 310 and the first ribs. The transmission nut 420 is threadedly engaged with the lead screw 200 for transmission. When the inner tube assembly 400 is connected to a load, the inner tube assembly 400 cannot rotate because the load cannot rotate. That is, the transmission nut 420 will not rotate. In this way, the inner tube assembly 400 is driven by the rotation of the lead screw 200 to make linear telescopic movements relative to the outer tube 300. The transmission unit 500 includes a worm gear 510 and a transmission wheel 520. The output shaft of the motor 100 is a worm that meshes with the worm gear 510. The worm gear 510 is sleeved on the outside of the transmission wheel 520 and is connected to the transmission wheel 520 through a spline structure, a flat fit, or a non-circular fit so that the two rotate synchronously.

[0026] In this embodiment, the transmission wheel 520 is provided with a first transmission part 521, and the lead screw 200 axially passes through the transmission wheel 520 and is provided with a second transmission part 210. The first transmission part 521 and the second transmission part 210 cooperate to enable the lead screw 200 and the transmission wheel 520 to rotate synchronously and move axially relative to each other. This allows the lead screw 200 to move in the direction of extension of the inner tube assembly after the inner tube assembly 400 retracts and encounters resistance, thereby causing the second transmission part 210 to axially separate from the first transmission part 521 and cutting off the power transmission between the lead screw 200 and the transmission wheel 520. The tail of the lead screw 200 is provided with an elastic member 600, which is used to retain the first transmission part 521 and the transmission wheel 520. The second transmission unit 210 is connected to the linear actuator, which also includes a permanent magnet 700 and a magnetic induction element 800. The permanent magnet 700 is slidably mounted on the outer tube 300 along the axial direction of the lead screw 200 and is circumferentially fixed relative to the outer tube 300. The permanent magnet 700 is connected to the lead screw 200 and maintains relative circumferential rotation and relative axial fixation. The magnetic induction element 800 is fixed inside the outer tube 300 and connected to the control unit 900. When the lead screw 200 moves in the direction of extension of the inner tube assembly 400, it drives the permanent magnet 700 to move and triggers the magnetic induction element 800 to generate an induction signal. The control unit 900 controls the motor 100 to stop operating according to the induction signal.

[0027] In the linear actuator of this embodiment, if the inner tube assembly 400 encounters resistance (i.e., encounters an obstacle) during retraction, the inner tube assembly 400 cannot continue to move, and the motor 100 still drives the lead screw 200 to rotate through the transmission unit 500. Therefore, the motor 100 will drive the lead screw 200 to move relative to the inner tube assembly 400 in the direction of the inner tube assembly 400's extension, overcoming the force of the elastic member 600. This allows the first transmission part 521 and the second transmission part 210 to separate axially, cutting off the power transmission between the transmission wheel 520 and the lead screw 200. At this time, the motor 100 and the transmission wheel 520 enter an idle state, meaning they will not drive the inner tube assembly 400 to continue retracting. This avoids the inner tube assembly 400 from continuing to retract and causing crushing damage to the obstacle, achieving an anti-pinch effect and mechanical protection. In addition, the movement of the lead screw 200 in the direction of the inner tube assembly 400's extension will drive the permanent magnet 700 to move, triggering the magnetic induction element 800 to generate an induction signal. The control unit 900 then... The inductive signal controls the motor 100 to stop operating, thereby reducing the ineffective wear of the motor 100 and the transmission unit 500, extending their service life, and further saving energy. Furthermore, since the linear actuator has entered a stopped state, it prevents further damage that could be caused by repeated attempts to operate or subsequent operations before the obstacle is removed. Finally, after the motor 100 stops operating and the obstacle is removed, the inner tube assembly 400 and the lead screw 200 can be reset under the action of the load and the elastic component 600, allowing the first transmission part 521 and the second transmission part 210 to re-engage, enabling the lead screw 200 to transmit power to the transmission wheel 520, allowing the linear actuator to be used normally again. Finally, the triggering method of using a permanent magnet 700 to trigger the magnetic induction element 800 to generate an inductive signal is a non-contact triggering method, with no physical contact and no mechanically worn parts. Moreover, since the speed at which the magnetic field change is sensed is in the microsecond range, the response speed is extremely fast.

[0028] Specifically, such as Figures 4 to 7 As shown, the first transmission part 521 is a transmission hole through which the lead screw 200 passes axially. The transmission hole is a non-circular hole, such as... Figure 12As shown, the lead screw 200 includes a threaded section 201, a non-circular section 204, a transmission section 202, and a cylindrical section 203 arranged sequentially along the axial direction. The outer diameter of the threaded section 201 is larger than the outer diameters of the transmission section 202, the cylindrical section 203, and the non-circular section 204. The threaded section 201 is threadedly engaged with the transmission nut 420. The radial cross-sections of the transmission section 202 and the non-circular section 204 are both non-circular. For example, the radial cross-section of the transmission section 202 is D-shaped, waist-shaped, or polygonal. The radial cross-section of the transmission section 202 is adapted to the shape of the transmission hole so that the transmission section 202 constitutes the second transmission part 210. In this way, the lead screw 200 and the transmission wheel 520 can rotate synchronously and move axially relative to each other by cooperating with the transmission hole and the transmission section 202. With this design, synchronous rotation and axial relative movement of the lead screw 200 and the transmission wheel 520 can be achieved by changing the shape of some sections of the lead screw 200 and the shape of some hole sections of the transmission wheel 520, without the need for other transmission components. This effectively reduces the number of parts, improves assembly efficiency, and reduces manufacturing costs.

[0029] In addition, such as Figure 4 and Figure 6 As shown, in this embodiment, the end of the cylindrical segment 203 facing away from the transmission segment 202 is connected to a stop plate 230 by screws. The elastic component 600 is one of a disc spring, a coil spring, or a rubber spring. Disc springs have the advantages of high stiffness and strong shock absorption capacity, and can withstand large loads with small deformation, making them suitable for applications with limited axial space requirements, thus occupying less space as the elastic component 600. Coil springs have a high elastic coefficient, compact structure, and small mass, and their stiffness is stable, extending their service life as the elastic component 600. Rubber springs have the advantages of high internal resistance, simple structure, strong impact resistance, and strong spring return capacity, providing good return effect when used as the elastic component 600. Of course, the elastic component 600 can also be any combination of two or three of the disc spring, coil spring, and rubber spring. Figure 8 As shown, the transmission wheel 520 also includes a clearance hole 524 through which the lead screw 200 passes. The clearance hole 524 is located at one end of the transmission wheel 520 away from the inner tube assembly 400. The diameter of the clearance hole 524 is larger than the diameter of the transmission hole and the two are connected, so that the end of the clearance hole 524 away from the tail end of the lead screw 200 forms a first stepped surface. In addition, the diameter of the clearance hole 524 is larger than the outer diameter of the elastic member 600. The elastic member 600 is sleeved on the outside of the cylindrical section 203 and pressed between the first stepped surface and the stop plate 230, and applies a force to the stop plate 230 in the direction away from the first stepped surface to maintain the connection tendency of the first transmission part 521 and the second transmission part 210.

[0030] like Figure 4 , Figure 5 , Figure 6 , Figures 9 to 12As shown, a sleeve 240 is fitted on the outer side of the non-circular segment 204. The sleeve 240 has a non-circular hole that matches the non-circular segment 204. The inner wall of the non-circular hole has a rib 242, which is interference-fitted with the non-circular segment 204. This allows the sleeve 240 and the non-circular segment 204 to maintain a circumferentially and axially fixed connection. A spacer 220 is fitted on the outer side of the sleeve 240. In this embodiment, a washer 250 is clamped between the sleeve 240 and the threaded segment 201. The sleeve 240 is located away from the gasket. One end of the washer 250 is provided with a locating shoulder 241. A portion of the spacer 220 is defined between the washer 250 and the locating shoulder 241, so that the spacer 220 and the bushing 240 are axially fixed relative to each other, thereby keeping the spacer 220 and the lead screw 200 axially fixed relative to each other. The spacer 220 and the bushing 240 adopt spline fit, flat fit, or non-circular fit, etc., so that the spacer 220 and the bushing 240 are circumferentially fixed relative to each other, so that the spacer 220 and the lead screw 200 rotate synchronously. During assembly, the washer 250 is first fitted onto the non-circular section 204 and made to abut against the threaded section 201. Then, the spacer 220 and the bushing 240 are assembled and fitted onto the non-circular section 204, so that the bushing 240 abuts against the washer 250.

[0031] In addition, an annular positioning groove 221 is provided on the outer periphery of the spacer 220, and an installation ring 260 is rotatably sleeved in the positioning groove 221. The installation ring 260 is axially slidably mounted on the outer tube 300 and circumferentially fixed relative to the outer tube 300. The permanent magnet 700 is disposed on the installation ring 260. This design allows the mounting ring 260 to serve as a mounting carrier for the permanent magnet 700, facilitating its installation. It also enables the permanent magnet 700 to connect with the lead screw 200, maintaining circumferential rotation and axial fixation. Furthermore, if the mounting ring 260 were directly installed in the circumferential groove of the lead screw and rotated with it, the requirements for the lead screw 200's machining accuracy, strength, and wear resistance would be extremely high. This embodiment, by designing a spacer ring 220, can be made of a material different from the lead screw material and with stronger wear resistance, protecting the structural integrity and strength of the lead screw 200. Additionally, the spacer ring 220 can be machined separately, making manufacturing precision easier to control and potentially lowering costs. If wear occurs, only the spacer ring 220 needs to be replaced, without needing to replace the expensive lead screw 200.

[0032] like Figure 11As shown, the outer periphery of the mounting ring 260 is provided with a limiting part 261 and a radial protrusion 262. The permanent magnet 700 is installed in the radial protrusion 262. The limiting part 261 cooperates with the inner wall groove of the outer tube 300 so that the mounting ring 260 and the outer tube 300 are circumferentially fixed and axially movable. For example, the limiting part 261 is a limiting protrusion provided on the outer periphery of the mounting ring 260, and multiple limiting parts 261 are arranged circumferentially along the outer periphery of the mounting ring 260. The limiting part 261 is inserted into the first guide groove 310 and slides in cooperation with the first guide groove 310; or, the limiting part 261 is a limiting groove provided on the outer periphery of the mounting ring 260, and multiple limiting parts 261 are arranged circumferentially along the outer periphery of the mounting ring 260. The inner wall of the outer tube 300 is provided with a limiting rib, and the limiting rib and the limiting groove slide in cooperation along the axial direction of the lead screw 200. In this way, the mounting ring 260 and the outer tube 300 can be kept circumferentially relatively fixed and axially relatively movable. Since the mounting ring 260 is completely restricted and cannot rotate relative to the outer tube 300 but can rotate relative to the positioning groove 221 (i.e., the lead screw), each axial movement of the lead screw 200 will ensure that the permanent magnet 700 triggers the magnetic induction element 800, thus avoiding slippage or missing due to rotation and failure to trigger the magnetic induction element 800.

[0033] In order to enable the assembly of the mounting ring 260 and the spacer 220, the mounting ring 260 in this embodiment is pre-processed with a notch. The mounting ring 260 can be cut by cutting the notch, and then it is put on the spacer 220 and assembled with the outer tube 300. The outer tube 300 and the limiting part 261 can constrain the two ends of the mounting ring 260 so that the mounting ring 260 can be stably put into the positioning groove 221.

[0034] Furthermore, the linear actuator in this embodiment also includes a switch bar 320 extending axially along the lead screw 200 within the outer tube 300, and two limit switches 330 mounted on the switch bar 320 to limit the extension and retraction of the inner tube assembly 400. A control unit 900 is disposed on the switch bar 320 and electrically connected to the two limit switches 330. By utilizing the existing control unit 900 and electrically connecting it to the magnetic induction element 800, no separate control unit is required, thereby simplifying the structure of the linear actuator.

[0035] Better, such as Figure 4 and Figure 13As shown, the control unit 900 includes a first circuit board 910 and a second circuit board 920 disposed on opposite sides of the switch bar 320 and electrically connected. The second circuit board 920 is located on the side of the switch bar 320 facing the inner tube assembly 400. The first circuit board 910 and the second circuit board 920 are electrically connected through a pin passing through the switch bar 320. The magnetic induction element 800 is a Hall sensor, which is disposed on the second circuit board 920. The first circuit board 910 is electrically connected to two limit switches 330. Since the power required to drive the load is high, a MOSFET is required when the required current exceeds the capacity of the Hall sensor. However, due to the size limitation of the existing first circuit board 910, more electrical components cannot be added. Therefore, by adding the second circuit board 920 to install the Hall sensor, the installation requirements of the Hall sensor can be met. Once the lead screw 200 moves axially, the Hall sensor will switch from a high-level signal to a low-level signal or vice versa according to the change in the magnetic field. The control unit 900 can determine the resistance encountered during retraction based on the change in the level signal, thereby controlling the motor 100 to stop operating.

[0036] It is understood that in other embodiments of this utility model, the magnetic induction element may also be a reed switch. When the lead screw moves in the direction of extending from the inner tube assembly and causes the second transmission part to separate axially from the first transmission part, the permanent magnet will trigger the reed switch to switch it from the off state to the on state or from the on state to the off state. Thus, the control unit controls the motor to stop running according to the change in the state of the reed switch.

[0037] It is understood that in other embodiments of this utility model, the spacer ring and the lead screw are integrally formed. Example 2

[0038] like Figures 14 to 20 As shown, compared with Embodiment 1, the difference in this embodiment is that the first transmission part 521 is a driving coupling, and the second transmission part 210 is a driven coupling. When the driving coupling and the driven coupling are connected, they remain circumferentially relatively fixed but can move axially relative to each other. This design not only improves the stability of power transmission when the driving coupling and the driven coupling are connected, but also allows the driving coupling and the driven coupling to easily separate axially when encountering resistance, making the axial separation action very sensitive.

[0039] In this embodiment, both the driving and driven couplings are axial jaw clutches with helical teeth on their axial end faces. The driving coupling is located at the end of the transmission wheel 520 near the inner tube assembly 400, and the driven coupling is located at the end of the driving coupling away from the transmission wheel 520. The opposing axial end faces of the driving and driven couplings are connected by helical tooth meshing, so that the driving and driven couplings remain circumferentially fixed and can move relative to each other axially. This design makes the structure simpler, the radial dimensions more compact, and the transmitted torque greater.

[0040] Furthermore, in this embodiment, one end of the transmission wheel 520 is provided with a guide sleeve 522 surrounding the outside of the driving coupling. When the driven coupling meshes with the driving coupling, at least part of the driven coupling is located within the guide sleeve 522, and the driven coupling and the guide sleeve 522 are axially slidingly engaged. This design allows the guide sleeve 522 to guide the axial movement of the driven coupling, facilitating smooth meshing of the axial end face of the driven coupling with the axial end face of the driving coupling.

[0041] Preferably, in this embodiment, the active coupling, guide sleeve 522 and transmission wheel 520 are integrally machined to reduce assembly steps and improve assembly efficiency.

[0042] In this embodiment, the lead screw 200 includes a threaded section 201, a transmission section 202, and a cylindrical section 203 arranged sequentially along the axial direction. The driven coupling is provided with a non-circular hole 211 that mates with the transmission section 202, so that the driven coupling can be circumferentially fixed relative to the transmission section 202 and the two can rotate synchronously. In addition, the inner wall of the non-circular hole 211 is provided with a second rib 212 extending axially along the non-circular hole 211. The second rib 212 is interference-fitted with the transmission section 202 so that the driven coupling and the transmission section 202 are axially fixed.

[0043] In this embodiment, the spacer 220 includes a small-diameter section and a large-diameter section. The large-diameter section is sleeved on the outside of the threaded section 201, while the small-diameter section is fixedly sleeved on the driven coupling at the end away from the driving coupling by an interference fit. This achieves circumferential and axial relative fixation of the spacer 220 relative to the driven coupling. Since the driven coupling and the lead screw 200 maintain circumferential and axial relative fixation, the spacer 220 and the lead screw 200 can maintain a synchronous rotational and axially fixed connection. The outer circumference of the spacer 220 is provided with an annular positioning groove 221. The positioning groove 221 is located on the outer circumference of the large-diameter section. The mounting ring 260 is confined within the positioning groove 221 so that the mounting ring 260 and the lead screw 200 maintain axial relative fixation. The mounting ring 260 and the positioning groove 221 are rotatably engaged.

[0044] It is understood that in other embodiments of this utility model, the driving coupling may also be sleeved on the outside of the driven coupling, and the inner side of the driving coupling and the outer side of the driven coupling are engaged by a spline structure to achieve circumferential relative fixation and axial relative movement between the two.

[0045] The other structures of Embodiment 2 are the same as those of Embodiment 1, and will not be described in detail here. Example 3

[0046] Combination Figure 21 As shown, this embodiment also discloses a shifter, including a base 1 and a boom 2. The boom 2 is rotatably connected to the base 1. It also includes a linear actuator as in Embodiment 1 or 2. The housing at one end of the linear actuator is hinged to the base 1, and the inner tube assembly 400 of the linear actuator is hinged to the boom 2 so as to drive the boom 2 to rise and fall through the telescopic movement of the inner tube assembly 400.

[0047] In addition to the preferred embodiments described above, there are other embodiments of this utility model. Those skilled in the art can make various changes and modifications based on this utility model. As long as they do not depart from the spirit of this utility model, they should all fall within the scope defined in the claims of this utility model.

Claims

1. A linear actuator, including: The system comprises a motor, a transmission unit, a lead screw, an outer tube, an inner tube assembly, and an elastic component. The lead screw is driven to rotate by power transmitted from the transmission unit, and the inner tube assembly is driven by the rotation of the lead screw to perform linear telescopic motion relative to the outer tube. The transmission unit includes a transmission wheel with a first transmission part, and the lead screw axially passes through the transmission wheel and has a second transmission part. The first and second transmission parts cooperate to allow the lead screw and the transmission wheel to rotate synchronously and move axially relative to each other. This allows the lead screw to move in the direction of extension of the inner tube assembly after the inner tube assembly retracts and encounters resistance, thereby axially separating the second transmission part from the first transmission part and cutting off the power transmission between the lead screw and the transmission wheel. The elastic component is used to maintain the connection trend between the first transmission part and the second transmission part; The linear actuator is characterized by further comprising: The permanent magnet is slidably mounted on the outer tube along the axis of the lead screw and is circumferentially fixed relative to the outer tube. The permanent magnet is connected to the lead screw and maintains relative circumferential rotation and relative axial fixation. A magnetic induction element is fixed inside the outer tube and connected to the control unit. When the lead screw moves in the direction of the extension of the inner tube assembly, it drives the permanent magnet to move and triggers the magnetic induction element to generate an induction signal. The control unit controls the motor to stop running according to the induction signal.

2. The linear actuator as claimed in claim 1, characterized in that, The lead screw is fitted with a spacer ring that rotates synchronously and is axially fixed. The outer circumference of the spacer ring is provided with an annular positioning groove. An installation ring is rotatably fitted in the positioning groove. The installation ring is axially slidably mounted on the outer tube and is circumferentially fixed relative to the outer tube. The permanent magnet is located on the installation ring.

3. The linear actuator as described in claim 2, characterized in that, The mounting ring has a limiting part on its outer circumference. The limiting part cooperates with the groove on the inner wall of the outer tube to keep the mounting ring and the outer tube circumferentially fixed and axially movable.

4. The linear actuator as claimed in claim 1, characterized in that, The magnetic sensing element is a reed switch or a Hall sensor.

5. The linear actuator as claimed in claim 4, characterized in that, The linear actuator also includes a switch bar extending along the screw axis inside the outer tube and two limit switches mounted on the switch bar to limit the extension and retraction of the inner tube assembly. The control unit is located on the switch bar and is electrically connected to the two limit switches.

6. The linear actuator as claimed in claim 5, characterized in that, The control unit includes a first circuit board and a second circuit board disposed on opposite sides of the switch bar and electrically connected thereto. The second circuit board is disposed on the side of the switch bar facing the inner tube assembly. The Hall sensor is disposed on the second circuit board. The first circuit board is electrically connected to two limit switches.

7. The linear actuator as claimed in claim 1, characterized in that, The first transmission part is a transmission hole through which the lead screw passes axially. The lead screw has a transmission section, which constitutes the second transmission part. The transmission hole and the transmission section cooperate to enable the lead screw and the transmission wheel to rotate synchronously and move axially relative to each other.

8. The linear actuator as claimed in claim 1, characterized in that, The first transmission unit is a driving coupling, and the second transmission unit is a driven coupling. When the driving coupling and the driven coupling are connected, they remain relatively fixed in the circumferential direction and can move relatively in the axial direction.

9. The linear actuator as claimed in claim 1, characterized in that, The transmission wheel is provided with a clearance hole at the end away from the inner tube assembly for the lead screw to pass through. The tail end of the lead screw is provided with a stop plate. The end of the clearance hole away from the tail end of the lead screw is provided with a first stepped surface. The elastic component is sleeved on the outside of the lead screw and pressed between the first stepped surface and the stop plate.

10. A shifter, comprising a base and a boom rotatably connected to the base, characterized in that, The shifter further includes a linear actuator as described in any one of claims 1 to 9, one end of the linear actuator being hinged to the base, the inner tube assembly being hinged to the boom, and the telescopic movement of the inner tube assembly driving the boom to rise and fall.

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