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 power of drive rotation of screw rod is transmitted by drive unit, and the linear telescopic motion of inner tube subassembly is made to relative outer tube by screw rod rotation drive, drive unit includes the transmission wheel of being 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: trigger piece, with outer tube connects to keep circumferential opposite fixed and axial opposite shift, and trigger piece is connected with screw rod to keep circumferential opposite rotation and axial opposite fixed, micro -switch, fixed in outer tube and located in the moving path of trigger piece, and micro -switch includes contact, and when the extension direction of screw rod to inner tube subassembly moves and press the contact of trigger piece movement, to make motor stop operation. In addition, the utility model discloses still adopted above-mentioned linear actuator's shifter.

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 utility model provides a linear actuator and shifter. After the inner tube assembly retracts and encounters an obstacle, the movement of the lead screw triggers a micro switch, which can stop the motor from running, 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, and an inner tube assembly. 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 separate axially from the first transmission part and cutting off the power transmission between the lead screw and the transmission wheel. The tail of the lead screw is provided with an elastic member, which is used to maintain the connection tendency of the first transmission part and the second transmission part. Linear actuators also include: The trigger element is connected to the outer tube to maintain relative circumferential fixation and relative axial movement; the trigger element is connected to the lead screw to maintain relative circumferential rotation and relative axial fixation. A micro switch is fixed inside the outer tube and located in the movement path of the trigger. The micro switch includes a contact. When the lead screw moves in the direction of extension of the inner tube assembly, it drives the trigger to move and press the contact, thereby stopping the motor.

[0007] 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.

[0008] Preferably, the driving coupling is located at the end of the transmission wheel near the inner tube assembly, and the driven coupling is located at the end of the driving coupling away from the transmission wheel. The axial end faces of the driving coupling and the driven coupling are meshed together so that the driving coupling and the driven coupling remain circumferentially fixed and can move axially relative to each other.

[0009] Preferably, one end of the transmission wheel is provided with a guide sleeve surrounding the outside of the driving coupling, and the driven coupling is axially slidingly engaged with the guide sleeve.

[0010] 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.

[0011] Preferably, a spacer ring is sleeved on the outer side of the lead screw, which rotates synchronously and is axially fixed. An annular positioning groove is provided on the outer periphery of the spacer ring. Part of the trigger element is confined in the positioning groove so that the trigger element and the lead screw are axially fixed. The trigger element and the positioning groove are rotatably engaged.

[0012] Preferably, the triggering element includes a trigger ring, a limiting part disposed on the outer periphery of the trigger ring, and a trigger protrusion. The trigger ring is confined within a positioning groove, the trigger protrusion is used to press the contact, and the limiting part cooperates with the inner wall groove of the outer tube to keep the triggering element and the outer tube circumferentially fixed and axially movable.

[0013] Preferably, the outer tube is provided with a switch bar extending axially along the inner tube assembly, and the micro switch is mounted on the switch bar with its contacts facing the inner tube assembly.

[0014] Preferably, the micro switch is a stop switch used to directly or indirectly interrupt the motor current when triggered by a triggering element; or, the micro switch is a signal switch, and a control board electrically connected to the micro switch is provided inside the outer tube, the control board controlling the motor to stop running after the micro switch is triggered.

[0015] Preferably, the inner tube assembly includes an inner tube and a transmission nut, the transmission nut being connected to the inner tube to maintain circumferential and axial relative fixation, the transmission nut being threadedly engaged with a lead screw for transmission, and the linear actuator further including two limit switches that limit the extension and retraction stroke of the inner tube assembly, one of which is located near the transmission wheel and constitutes the micro switch.

[0016] 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.

[0017] 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., 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 from continuing to retract and causing crushing damage to the obstacle, achieving an anti-pinch effect and mechanical protection. In addition, the lead screw moves towards the inner tube assembly... The movement of the extended component causes the trigger component to move and press the contact, thereby stopping the motor and reducing ineffective wear on the motor and transmission unit, extending their service life, and further saving energy. In addition, since the linear actuator has entered a stopped state, it prevents further damage that may be caused by repeated attempts to operate or subsequent operations without removing the obstacle. Furthermore, after the motor stops and the obstacle is removed, the inner tube assembly and the lead screw can be reset under the action of the load and the elastic component to allow the first and second transmission parts to re-engage and enable the lead screw to transmit power to the transmission wheel, allowing the linear actuator to be used normally again.

[0018] 2. 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.

[0019] 3. The driving coupling is located at the end of the drive wheel closest to the inner tube assembly, and the driven coupling is located at the end of the driving coupling away from the drive wheel. The axial end faces of the driving and driven couplings are engaged to keep them circumferentially fixed while allowing axial relative movement. This design simplifies the structure, makes the radial dimensions more compact, and allows for greater torque transmission.

[0020] 4. One end of the transmission wheel is provided with a guide sleeve surrounding the outside of the driving coupling, and the driven coupling is axially slidingly engaged with the guide sleeve. This design allows the guide sleeve to guide the axial movement of the driven coupling, facilitating smooth engagement between the axial end face of the driven coupling and the axial end face of the driving coupling.

[0021] 5. 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 transmission wheel hole section, without the need for other transmission components. This effectively reduces the number of parts, improves assembly efficiency, and reduces manufacturing costs.

[0022] 6. A spacer ring is fitted on the outer side of the lead screw, rotating synchronously and axially fixed. The outer circumference of the spacer ring has an annular positioning groove. Part of the trigger element is confined within the positioning groove to maintain axial relative fixation between the trigger element and the lead screw. The trigger element rotates within the positioning groove. With this design, if the trigger element were directly installed in 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. This protects the structural integrity and strength of the lead screw. Furthermore, 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.

[0023] 7. The trigger element includes a trigger ring, a limiting part located on the outer periphery of the trigger ring, and a trigger protrusion. The trigger ring is confined within a positioning groove, and the trigger protrusion is used to press the contact. The limiting part engages with the inner wall groove of the outer tube to keep the trigger element and the outer tube circumferentially fixed and axially movable. This design improves the installation stability of the trigger element. Furthermore, since the trigger element is completely confined and cannot rotate relative to the outer tube but can rotate relative to the positioning groove (i.e., the lead screw), each axial movement of the lead screw ensures that the trigger protrusion is aligned with the contact of the micro switch, ensuring effective pressing and preventing slippage or missed contact due to rotation, thus avoiding failure to press the contact.

[0024] 8. A switch bar extending axially along the inner tube assembly is provided inside the outer tube. The micro switch is mounted on the switch bar with its contacts facing the inner tube assembly. Since the existing linear actuator already has a switch bar inside the outer tube for mounting the limit switch, the existing switch bar can be used as the mounting carrier for the micro switch, eliminating the need for a separate mounting carrier and thus simplifying the structure of the linear actuator.

[0025] 9. A micro switch is a stop switch used to directly or indirectly interrupt the motor current when triggered by a triggered component. This design allows the motor to stop immediately by interrupting the motor current, with a fast response speed. Alternatively, the micro switch can be a signal switch with a control board electrically connected to the micro switch inside the outer tube. The control board controls the motor to stop after the micro switch is triggered. This design allows for smoother and more controlled shutdown through the control board, reducing secondary risks.

[0026] 10. The inner tube assembly includes an inner tube and a drive nut. The drive nut is connected to the inner tube to maintain circumferential and axial relative fixation. The drive nut engages with the lead screw for transmission. The linear actuator also includes two limit switches that limit the extension and retraction of the inner tube assembly. One of the limit switches is located near the drive wheel and constitutes a micro switch. This design utilizes the existing limit switch near the drive wheel to form a micro switch, eliminating the need for a separate micro switch, thereby reducing the number of parts and further lowering the product's manufacturing cost. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the linear actuator in Embodiment 1 of this utility model; Figure 2 This is a cross-sectional view of the linear actuator in Embodiment 1 of this utility model. Figure 1 ; Figure 3 for Figure 2 A magnified view of part A in the diagram; Figure 4 This is a cross-sectional view of the linear actuator in Embodiment 1 of this utility model. Figure 2 ; Figure 5 This is an exploded view of the linear actuator section of the present invention in Embodiment 1. Figure 6 This is a structural diagram of the transmission wheel and the drive coupling integrally formed in Embodiment 1 of this utility model; Figure 7 This is a cross-sectional view of the transmission wheel and the drive coupling integrally formed in Embodiment 1 of this utility model; Figure 8 This is a schematic diagram of the driven coupling in Embodiment 1 of this utility model; Figure 9This is a schematic diagram of the spacer structure in Embodiment 1 of this utility model; Figure 10 This is a schematic diagram of the trigger element in Embodiment 1 of this utility model; Figure 11 This is a partial structural diagram of the lead screw in Embodiment 1 of this utility model; Figure 12 This is a partial cross-sectional view of the linear actuator in Embodiment 2 of this utility model. Figure 1 ; Figure 13 This is a partial cross-sectional view of the linear actuator in Embodiment 2 of this utility model. Figure 2 ; Figure 14 This is an exploded view of the linear actuator portion of the structure in Embodiment 2 of this utility model; Figure 15 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; 300 is the outer tube; 310 is the first guide groove; 320 is the switch bar; 330 is the control board; 400 is the inner tube assembly; 410 is the inner tube; 420 is the inner tube. Transmission nut; 430, guide ring; 500, transmission unit; 510, worm gear; 520, transmission wheel; 521, first transmission part; 522, guide sleeve; 523, guide hole; 524, clearance hole; 600, elastic component; 700, trigger element; 710, trigger ring; 720, limiting part; 730, trigger protrusion; 800, micro switch; 810, contact; 900, washer; 910, positioning shoulder; 1000, gasket; 1. Base; 2. Crane arm. Detailed Implementation

[0028] 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

[0029] Combination Figures 1 to 11The 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.

[0030] 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 to rotate synchronously with the transmission wheel 520 and to move axially relative to it. 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 hold the first transmission part 521. The connection trend of the first transmission part 521 and the second transmission part 210; the linear actuator also includes a trigger 700 and a micro switch 800. The trigger 700 is connected to the outer tube 300 to maintain relative circumferential fixation and relative axial movement. The trigger 700 is connected to the lead screw 200 to maintain relative circumferential rotation and relative axial fixation. The micro switch 800 is fixed inside the outer tube 300 and located in the movement path of the trigger 700. The micro switch 800 includes a contact 810. When the lead screw 200 moves in the direction of extension of the inner tube assembly 400, it drives the trigger 700 to move and press the contact 810 to stop the motor 100 from running.

[0031] 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 its extension and overcome 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 lead screw 200 moves towards... Moving the inner tube assembly 400 in the direction of its extension will cause the trigger 700 to move and press the contact 810, thereby stopping the motor 100. This reduces the ineffective wear of the motor 100 and the transmission unit 500, extends their service life, and further saves energy. In addition, since the linear actuator has entered the stop state, it prevents further damage that may be caused by repeated attempts to operate or subsequent operations without removing the obstacle. Finally, after the motor 100 stops 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 member 600 so that the first transmission part 521 and the second transmission part 210 can re-engage to enable the lead screw 200 to transmit power to the transmission wheel 520, allowing the linear actuator to be used normally again.

[0032] Specifically, such as Figure 3 , Figures 5 to 7 As shown, in this embodiment, the first transmission unit 521 is a driving coupling, and the second transmission unit 210 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] like Figure 3 , Figure 8 and Figure 11 As shown, the lead screw 200 in this embodiment includes a threaded section 201, 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 and the cylindrical section 203. The threaded section 201 is threadedly engaged with the transmission nut 420. The transmission section 202 is a non-circular section. The driven coupling is provided with a non-circular hole 211 that mates with the transmission section 202. This allows the driven coupling to be circumferentially fixed relative to the transmission section 202, enabling them to 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 is axially fixed relative to the transmission section 202.

[0037] In addition, such as Figure 3 and Figure 5 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 a screw, which is equivalent to the stop plate 230 being provided at the tail end of the lead screw 200. 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. As an elastic component 600, it occupies less space. Coil springs have a high elastic coefficient, compact structure, and small mass, and their stiffness is stable, which can extend their service life when used as an elastic component 600. Rubber springs have the advantages of high internal resistance, simple structure, strong impact resistance, and strong spring return capacity, resulting in good return effect when used as an 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 7 As shown, the transmission wheel 520 includes a guide hole 523 and a clearance hole 524 through which the lead screw 200 passes. The guide hole 523 is located between the clearance hole 524 and the guide sleeve 522, that is, the clearance hole 524 is located at the end of the transmission wheel 520 away from the inner tube assembly 400. The guide hole 523 is adapted to the cylindrical section 203, and the diameter of the clearance hole 524 is larger than the outer diameter of the elastic member 600, so that the end of the clearance hole 524 away from the tail end of the lead screw 200 forms a first stepped surface. 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.

[0038] like Figures 3 to 5 ,as well as Figure 9As shown, in this embodiment, the lead screw 200 is also fitted with an independently machined spacer 220. The spacer 220 includes a small diameter section and a large diameter section. The large diameter section is fitted outside the threaded section 201, while the small diameter section is fixedly fitted to 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 synchronous rotation and axial relative fixation. 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. Part of the trigger 700 is confined in the positioning groove 221 so that the trigger 700 and the lead screw 200 maintain axial relative fixation. The trigger 700 and the positioning groove 221 are rotatably engaged. With this design, if the trigger 700 is directly installed in the circumferential groove of the lead screw 200 and rotates with it, the requirements for the machining accuracy, strength and wear resistance of the lead screw 200 are extremely high. However, in this embodiment, by designing a spacer ring 220, it can be made of a material different from the lead screw material and with stronger wear resistance, thus protecting the structural integrity and strength of the lead screw 200. In addition, the spacer ring 220 can be machined separately, making the manufacturing accuracy easier to control and the cost potentially lower. If it wears out, only the spacer ring 220 needs to be replaced, without having to replace the expensive lead screw 200.

[0039] like Figure 10As shown, the trigger 700 in this embodiment includes a trigger ring 710, a limiting portion 720 disposed on the outer periphery of the trigger ring 710, and a trigger protrusion 730. The trigger ring 710 is confined within the positioning groove 221 and can rotate relative to the positioning groove 221. The trigger protrusion 730 protrudes radially outward from the outer periphery of the trigger ring 710 and is used to press the contact 810. The limiting portion 720 cooperates with the inner wall groove of the outer tube 300 to keep the trigger 700 and the outer tube 300 circumferentially fixed and axially movable. For example, the limiting portion 720 is a limiting portion disposed on the outer periphery of the trigger ring 710. The trigger ring 710 has a protrusion and multiple limiting parts 720 are spaced apart circumferentially along the outer periphery of the trigger ring 710. The limiting parts 720 are inserted into the first guide groove 310 and slide in cooperation with the first guide groove 310. Alternatively, the limiting parts 720 are limiting grooves provided on the outer periphery of the trigger ring 710. Multiple limiting parts 720 are spaced apart circumferentially along the outer periphery of the trigger ring 710. The inner wall of the outer tube is provided with limiting ribs. The limiting ribs and the limiting grooves slide in cooperation axially along the lead screw 200. In this way, the trigger 700 and the outer tube 300 can be kept circumferentially relatively fixed and axially relatively movable. With this design, the trigger 700 is fitted on the outside of the spacer 220, which can improve the installation stability of the trigger 700. In addition, since the trigger 700 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 trigger protrusion 730 is aligned with the contact 810 of the micro switch 800, ensuring effective pressing and avoiding slippage or missing due to rotation, thus preventing the contact 810 from being pressed.

[0040] In order to enable the assembly of the trigger 700 and the spacer 220, the trigger ring 710 in this embodiment is pre-machined with a notch. The trigger ring 710 can be cut by cutting the notch with scissors, and then it is put on the spacer 220 and assembled with the outer tube 300. The outer tube 300 and the limiting part 720 can constrain the two ends of the trigger ring 710 so that the trigger ring 710 can be stably put on the positioning groove 221.

[0041] In addition, such as Figures 3 to 5 As shown, in this embodiment, the outer tube 300 is also provided with a switch strip 320 extending axially along the inner tube assembly 400. The micro switch 800 is mounted on the switch strip 320 with its contact 810 facing the inner tube assembly 400. Since the outer tube of the existing linear actuator already has a switch strip for mounting the limit switch, the existing switch strip can be used as the mounting carrier for the micro switch 800, eliminating the need for a separate mounting carrier and thus simplifying the structure of the linear actuator.

[0042] In this embodiment, the micro switch 800 is a signal switch. The outer tube 300 is equipped with a control board 330 that is electrically connected to the micro switch 800. After the micro switch 800 is triggered, the control board 330 controls the motor 100 to stop running. With this design, the control board 330 can achieve a smoother and more controlled shutdown, reducing secondary risks.

[0043] 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.

[0044] It is understood that in other embodiments of this invention, when the linear actuator further includes two limit switches that limit the extension and retraction of the inner tube assembly, one of the limit switches is located near the drive wheel, and this limit switch constitutes a micro switch. This design eliminates the need for a separate micro switch by utilizing the existing limit switch near the drive wheel, thereby reducing the number of components and further lowering the manufacturing cost of the product.

[0045] It is understood that in other embodiments of this utility model, the micro switch is a stop switch, used to directly or indirectly interrupt the motor current when triggered by the triggered element; with this design, the motor can be controlled to stop running immediately by interrupting the motor current, and the response speed is fast. It is understood that in other embodiments of this utility model, the spacer ring and the lead screw are integrally formed; and / or, the spacer ring and the driven coupling are integrally formed. Example 2

[0046] like Figures 12 to 14 As shown, compared with Embodiment 1, the difference in this embodiment is that: 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, while the lead screw 200 has a transmission section 202, which constitutes the second transmission part. The transmission hole and the transmission section 202 cooperate to enable the lead screw 200 and the transmission wheel 520 to rotate synchronously and move axially relative to each other. With this design, by changing the shape of a section of the lead screw 200 and the shape of a section of the hole in the transmission wheel 520, synchronous rotation and axial relative movement of the two can be achieved without setting up other transmission components. This effectively reduces the number of parts, improves assembly efficiency, and reduces manufacturing costs.

[0047] Furthermore, the lead screw 200 in this embodiment also includes a non-circular segment 204 disposed between the transmission section 202 and the threaded section 201. A gasket 900 is sleeved on the outer side of the non-circular segment 204. The gasket 900 has a non-circular hole that matches the non-circular segment 204. The inner wall of the non-circular hole has a raised rib, which is interference-fitted with the non-circular segment 204. This allows the gasket 900 and the non-circular segment 204 to maintain a circumferentially and axially fixed connection. A spacer 220 is sleeved on the outer side of the gasket 900. In this embodiment, the gasket 900 and the threaded section... The 201 clamp holds a washer 1000. A locating shoulder 910 is provided at the end of the sleeve 900 away from the washer 1000. A portion of the spacer 220 is positioned between the washer 1000 and the locating shoulder 910, thus axially fixing the spacer 220 relative to the sleeve 900. This, in turn, axially fixes the spacer 220 relative to the lead screw 200. The spacer 220 and the sleeve 900 are connected by a spline or non-circular joint, allowing them to be circumferentially fixed, ensuring synchronous rotation between the spacer 220 and the lead screw 200. During assembly, the washer 1000 is first fitted onto the non-circular section 204 and abutted against the threaded section 201. Then, the spacer 220 and sleeve 900 are assembled and fitted onto the non-circular section 204, with the sleeve 900 abutting against the washer 1000.

[0048] The other structures of Embodiment 2 are the same as those of Embodiment 1, and will not be described in detail here. Example 3

[0049] Combination Figure 15 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.

[0050] 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, and an inner tube assembly. 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 tail of the lead screw is provided with an elastic member to maintain the connection tendency of the first and second transmission parts. The linear actuator is characterized by further comprising: The trigger element is connected to the outer tube to maintain relative circumferential fixation and relative axial movement; the trigger element is connected to the lead screw to maintain relative circumferential rotation and relative axial fixation. A micro switch is fixed inside the outer tube and located in the movement path of the trigger. The micro switch includes a contact. When the lead screw moves in the direction of extension of the inner tube assembly, it drives the trigger to move and press the contact, thereby stopping the motor.

2. The linear actuator as claimed in claim 1, characterized in that, 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.

3. The linear actuator as described in claim 2, characterized in that, The driving coupling is located at the end of the transmission wheel near the inner tube assembly, and the driven coupling is located at the end of the driving coupling away from the transmission wheel. The axial end faces of the driving coupling and the driven coupling are meshed to keep the driving coupling and the driven coupling circumferentially fixed and axially movable.

4. The linear actuator as described in claim 3, characterized in that, One end of the transmission wheel is provided with a guide sleeve that surrounds the outside of the driving coupling, and the driven coupling is axially slidingly engaged with the guide sleeve.

5. 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.

6. 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 periphery of the spacer ring is provided with an annular positioning groove. Part of the trigger element is confined in the positioning groove so that the trigger element and the lead screw are axially fixed. The trigger element and the positioning groove are rotatably engaged.

7. The linear actuator as claimed in claim 6, characterized in that, The triggering element includes a trigger ring, a limiting part located on the outer periphery of the trigger ring, and a trigger protrusion. The trigger ring is confined within a positioning groove, and the trigger protrusion is used to press the contact. The limiting part cooperates with the inner wall groove of the outer tube to keep the triggering element and the outer tube circumferentially fixed and axially movable.

8. The linear actuator as claimed in claim 1, characterized in that, The outer tube is provided with a switch bar extending axially along the inner tube assembly, and the micro switch is mounted on the switch bar with its contacts facing the inner tube assembly.

9. The linear actuator as claimed in claim 1, characterized in that, The micro switch is a stop switch used to directly or indirectly interrupt the motor current when triggered by a triggering element; or, the micro switch is a signal switch, and a control board electrically connected to the micro switch is provided inside the outer tube, the control board controlling the motor to stop running after the micro switch is triggered.

10. The linear actuator as claimed in claim 9, characterized in that, The inner tube assembly includes an inner tube and a drive nut. The drive nut is connected to the inner tube to maintain relative circumferential and relative axial fixation. The drive nut is threadedly engaged with a lead screw for transmission. The linear actuator also includes two limit switches that limit the extension and retraction of the inner tube assembly. One of the limit switches is located near the drive wheel and constitutes the micro switch.

11. 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 10, 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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