A linear actuator that is easy to operate

Abstract

The application discloses a linear actuator, and belongs to the technical field of linear transmission, which comprises a driving motor, a transmission assembly, a rotating screw rod, a transmission nut, a clutch device, a self-locking device and a hand-pulling release assembly, the clutch device is arranged between the transmission assembly and the rotating screw rod, the self-locking device is used for generating friction resistance on the rotating screw rod when the rotating screw rod reverses, the self-locking device comprises a release torsional spring, the hand-pulling release assembly comprises a first driving member and a second driving member, the first driving member is connected with the clutch device, the second driving member is used for connecting the self-locking device, the hand-pulling release assembly comprises an initial state and a completely released state, in the process from the initial state to the completely released state, the first driving member drives the clutch device to disconnect power connection, and the second driving member drives the release torsional spring to loosen. The application has the advantages that the hand-pulling release assembly can control two devices, and operation is more convenient.

Description

[Technical Field]

[0001] This invention relates to a linear actuator that is easy to operate, belonging to the field of linear transmission technology. [Background Technology]

[0002] Linear actuators, also known as electric linear actuators, are widely used in furniture, medical equipment, solar power generation, and other fields. Their main structure includes a drive motor, a transmission worm, a worm wheel, a lead screw, and a nut. The working principle is that the drive motor drives the transmission worm to rotate, the transmission worm meshes with the worm wheel, thereby driving the worm wheel to rotate, the worm wheel rotates, the lead screw rotates, and the lead screw rotates, thereby driving the nut to move axially. The nut is generally connected to an inner tube, thereby realizing the extension and retraction of the inner tube.

[0003] Considering the application environment of linear actuators, when encountering drive motor failure, power outage, or other situations requiring power disconnection, a clutch device is added to the linear actuator. This clutch device is mainly used to disconnect the power between the drive motor and the rotating screw, so that reverse drive can be achieved by manually driving the rotating screw. For example, CN201621013870.3 discloses a scheme to add a clutch device to a linear actuator.

[0004] In addition, in order to generate resistance when the linear actuator retracts, a self-locking device is usually provided on the linear actuator. This type of self-locking device usually includes a friction sleeve and a self-locking torsion spring fitted outside the friction sleeve. When the friction sleeve reverses with the rotating screw, the self-locking torsion spring will retract radially to hold the friction sleeve tightly, thereby generating self-locking resistance on the rotating screw. This type of self-locking device has been widely disclosed in linear actuators.

[0005] Currently available linear actuators typically only have a clutch or a self-locking device. Even if both a clutch and a self-locking device are present, the drive components that drive these two devices are usually separate. This means that if the operator needs to control both the clutch and the self-locking device at the same time, they need to operate each device independently, which makes the operation quite complicated. [Summary of the Invention]

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a linear actuator that is easy to operate, so that the hand-pull release component can control two devices, making operation more convenient.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A user-friendly linear actuator includes a drive motor, a transmission assembly, a rotating lead screw, and a transmission nut. The drive motor drives the rotating lead screw to rotate via the transmission assembly, and the rotation of the lead screw causes the transmission nut to move axially along the rotating lead screw. The linear actuator further includes:

[0009] A clutch device is located between the transmission assembly and the rotating lead screw, and is used to connect or disconnect the power connection between the transmission assembly and the rotating lead screw.

[0010] The self-locking device generates frictional resistance to the rotating lead screw when the rotating lead screw reverses, and the self-locking device includes a release torsion spring for unlocking the self-locking device;

[0011] A pull-release assembly includes a first driving component and a second driving component. The first driving component is connected to a clutch device, and the second driving component is used to connect to the self-locking device. The pull-release assembly includes an initial state and a fully released state. During the process from the initial state to the fully released state, the first driving component drives the clutch device to disconnect the power connection, and the second driving component drives the release torsion spring to release.

[0012] The beneficial effects of using the present invention are as follows:

[0013] The linear actuator in this invention incorporates both a clutch and a self-locking device, making its functionality more comprehensive. Furthermore, the combination of the clutch and the self-locking device offers an advantage: after the clutch disconnects the power, the rotating screw is almost completely free to rotate, which can easily lead to excessively fast retraction speed of the linear actuator. The self-locking device, on the other hand, provides a certain amount of resistance to prevent excessively fast retraction.

[0014] Secondly, the self-locking device in this invention also has a release torsion spring, meaning that the self-locking device itself can also be unlocked. When the release torsion spring is released, the self-locking device is in the unlocked state. At this time, the linear actuator rotates in either the forward or reverse direction, and the self-locking device generates almost no resistance. This situation allows the linear actuator to be in a rapid release state, that is, it can retract quickly.

[0015] Finally, the linear actuator of the present invention is provided with a manual release assembly, which includes a first driving component and a second driving component. The first driving component and the second driving component are used to drive the clutch device and the self-locking device, respectively. When the linear actuator needs to be released quickly, the operator operates the manual release assembly to put it in a fully released state, which can put the clutch device in a disengaged state and the self-locking device in an unlocked state. The user only needs to operate one manual release assembly to control two devices, which is very convenient to operate.

[0016] Preferably, the transmission assembly includes a transmission worm and a transmission worm wheel, the transmission worm is connected to a drive motor, the transmission worm wheel is mounted on the outside of the rotating lead screw, and the clutch device is located between the transmission worm wheel and the rotating lead screw.

[0017] Preferably, the clutch device includes a coupling gear sleeve, the transmission worm gear is provided with a tooth groove that matches and drives the coupling gear sleeve, and the coupling gear sleeve is fitted on the rotating lead screw and can move axially relative to the rotating lead screw.

[0018] Preferably, the clutch device further includes a return spring that generates an axial return force on the coupling sleeve.

[0019] Preferably, the linear actuator further includes a housing, the first drive member includes a rocker arm rotatably mounted on the housing, and the hand-pull release assembly further includes a pull rod axially movably disposed relative to the rotating lead screw. The rocker arm is connected to the pull rod, and when the pull rod is pulled, the rocker arm swings to axially push the clutch device.

[0020] Preferably, the self-locking device includes a first friction sleeve and a second friction sleeve, which are respectively fitted onto a rotating lead screw, with their axial end faces abutting each other. The first friction sleeve rotates synchronously with the rotating lead screw, while the second friction sleeve rotates freely relative to the rotating lead screw. A self-locking torsion spring is fitted onto the first friction sleeve, and the release torsion spring is fitted onto the second friction sleeve. Alternatively, the self-locking device includes a third friction sleeve, which rotates synchronously with the rotating lead screw, and the release torsion spring is fitted onto the third friction sleeve.

[0021] Preferably, the second driving component includes a push block with a guide surface, the release torsion spring includes a radially extending pin, and the hand-pull release assembly includes a pull rod axially movable relative to the rotating screw. The pull rod is connected to the push block, and when the pull rod is pulled, the guide surface on the push block abuts against the pin to cause the release torsion spring to expand outward.

[0022] Preferably, during the process of the hand-pulled release assembly returning from the fully released state to the initial state, the second drive member first disengages from the release torsion spring on the self-locking device to generate a self-locking force, and after the release torsion spring returns to its original position, the first drive member disengages from the clutch device accordingly.

[0023] Preferably, the linear actuator includes an outer tube and an inner tube that extends and retracts relative to the outer tube, with a front pull head connected to the end of the inner tube, and a hand-rotating release device connected between the front pull head and the end of the inner tube.

[0024] Preferably, the hand-rotating release device includes a knob sleeve, a connecting sleeve, and a hand-rotating release torsion spring. The connecting sleeve is fixedly connected to the inner tube, the front pull head is fitted onto the connecting sleeve, and the hand-rotating release torsion spring is disposed between the connecting sleeve and the front pull head. The knob sleeve is used to turn the hand-rotating release torsion spring to radially contract or radially expand.

[0025] These features and advantages of the present invention will be disclosed in detail in the following specific embodiments and accompanying drawings. [Attached Image Description]

[0026] The invention will be further described below with reference to the accompanying drawings:

[0027] Figure 1 This is an overall schematic diagram of the linear actuator of Embodiment 1 of the present invention. Figure 1 ;

[0028] Figure 2 This is an overall schematic diagram of the linear actuator of Embodiment 1 of the present invention. Figure 2 ;

[0029] Figure 3 This is an exploded view of the linear actuator in Embodiment 1 of the present invention;

[0030] Figure 4 This is a partially enlarged schematic diagram of the linear actuator in Embodiment 1 of the present invention;

[0031] Figure 5 This is an exploded view of the internal components in the linear actuator of Embodiment 1 of the present invention;

[0032] Figure 6 This is an exploded schematic diagram of the hand-rotating release device in the linear actuator of Embodiment 1 of the present invention;

[0033] Figure 7 This is a cross-sectional schematic diagram of the manual release device of the linear actuator in Embodiment 1 of the present invention;

[0034] Figure 8 This is a schematic diagram of the linear actuator of Embodiment 2 of the present invention;

[0035] Figure 9 This is a partial cross-sectional schematic diagram of the linear actuator of Embodiment 2 of the present invention;

[0036] Figure 10 This is a partially enlarged cross-sectional view of the linear actuator of Embodiment 2 of the present invention;

[0037] Figure 11 This is an exploded view of the internal components in the linear actuator of Embodiment 2 of the present invention.

Detailed Implementation Methods

[0038] The technical solutions of the embodiments of the present invention will be explained and described below with reference to the accompanying drawings. However, the following embodiments are only preferred embodiments of the present invention and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments in the implementation methods without creative effort are all within the protection scope of the present invention.

[0039] In the following description, terms such as “inner,” “outer,” “upper,” “lower,” “left,” and “right” that indicate orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings and are used only for the convenience of describing embodiments and simplifying the description, and are not intended to indicate or imply that the device or element 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.

[0040] Example 1:

[0041] like Figures 1 to 7 As shown, this embodiment is a linear actuator, also commonly referred to as a linear driver or electric actuator. The linear actuator includes a housing, an outer tube 13, an inner tube 14, a drive motor 15, a transmission assembly, a rotating lead screw 20, and a transmission nut 21. The drive motor 15 drives the rotating lead screw 20 to rotate via the transmission assembly. The rotation of the rotating lead screw 20 causes the transmission nut 21 to move axially along the rotating lead screw 20. The transmission nut 21 is fixedly connected to the inner tube 14. When the transmission nut 21 moves axially, it causes the inner tube 14 to move axially relative to the outer tube 13 and the housing. The outer end of the inner tube 14 is connected to the object to be driven. The linear actuator in this embodiment also includes:

[0042] A clutch device is located between the transmission assembly and the rotating lead screw 20, and is used to connect or disconnect the power connection between the transmission assembly and the rotating lead screw 20.

[0043] The self-locking device generates frictional resistance to the rotating lead screw 20 when the rotating lead screw 20 reverses. The self-locking device includes a release torsion spring 40 for unlocking the self-locking device.

[0044] A pull-release assembly includes a first driving component and a second driving component. The first driving component is connected to a clutch device, and the second driving component is used to connect to the self-locking device. The pull-release assembly includes an initial state and a fully released state. During the process from the initial state to the fully released state, the first driving component drives the clutch device to disconnect the power connection, and the second driving component drives the release torsion spring 40 to release.

[0045] The linear actuator in this embodiment is equipped with both a clutch device and a self-locking device, making the linear actuator more comprehensive in function. Moreover, the combination of the clutch device and the self-locking device has an advantage: after the clutch device disconnects the power, the rotating screw 20 is almost in a state of complete free rotation, which can easily lead to the linear actuator retracting too quickly. The self-locking device can provide a certain resistance to prevent the rotating screw 20 from rotating too quickly, thereby avoiding the transmission nut 21 from retracting too quickly.

[0046] Secondly, in this embodiment, the self-locking device also has a release torsion spring 40, meaning that the self-locking device itself can also be unlocked. When the release torsion spring 40 is released, the self-locking device is in the unlocked state. At this time, whether the linear actuator rotates in the forward or reverse direction, the self-locking device produces almost no resistance to the rotating screw 20. This situation allows the linear actuator to be in a rapid release state, that is, it can retract quickly.

[0047] Finally, the linear actuator in this embodiment is equipped with a manual release assembly, which includes a first driving component and a second driving component. The first driving component and the second driving component are used to drive the clutch device and the self-locking device, respectively. When the linear actuator needs to be released quickly, the operator operates the manual release assembly to put it in a fully released state, which can put the clutch device in a disengaged state and the self-locking device in an unlocked state. The user only needs to operate one manual release assembly to control two devices, which is very convenient to operate.

[0048] The specific structure of this embodiment is as follows:

[0049] In this embodiment, the transmission assembly includes a transmission worm 151 and a transmission worm wheel 22. The transmission worm 151 is connected to the drive motor 15. The transmission worm wheel 22 is mounted on the outside of the rotating lead screw 20 and is coaxial with the rotating lead screw 20. The clutch device is located between the transmission worm wheel 22 and the rotating lead screw 20. In this embodiment, the clutch device is mainly used to disconnect the power connection between the transmission worm wheel 22 and the rotating lead screw 20.

[0050] The specific structure of the clutch device in this embodiment is as follows: The clutch device includes a coupling sleeve 31, which is fitted onto the rotating lead screw 20 via a flat section. That is, in the circumferential direction, the coupling sleeve 31 and the rotating lead screw 20 rotate synchronously. However, in the axial direction, the coupling sleeve 31 can move axially along the rotating lead screw 20. The coupling sleeve 31 has multiple teeth facing the transmission worm gear 22. The end face of the transmission worm gear 22 is provided with tooth grooves that match and drive the coupling sleeve 31. When the coupling sleeve 31 approaches the transmission worm gear 22, the teeth are inserted into the tooth grooves, and the coupling sleeve 31 and the transmission worm gear 22 rotate synchronously. When the coupling sleeve 31 moves away from the transmission worm gear 22, the teeth disengage from the tooth grooves, and the coupling sleeve 31 separates from the transmission worm gear 22, meaning the rotating lead screw 20 is in a state of no-power engagement. (Reference) Figure 4 In the middle, the coupling sleeve 31 is inserted into the transmission worm gear 22.

[0051] In this embodiment, the first driving component is mainly used to move the coupling sleeve 31 axially. In order to allow the clutch device to reset after the first driving component has moved, the clutch device in this embodiment also includes a reset spring 32 that generates an axial reset force on the coupling sleeve 31. The end of the rotating screw 20 is provided with a limiting end 201. The reset spring 32 is sleeved on the rotating screw 20, and its two ends are limited between the limiting end 201 and the coupling sleeve 31.

[0052] The linear actuator described in this embodiment also includes a housing, which includes an upper housing 11 and a lower housing 12. A first bearing 33 is provided between the coupling sleeve 31 and the housing to reduce the frictional resistance when the coupling sleeve 31 rotates.

[0053] The structure of the first driving component in this embodiment is as follows: The first driving component includes a rocker arm 51 rotatably mounted on the outer shell. The hand-pulled release assembly also includes a pull rod 52 axially movable relative to the rotating lead screw 20. The rocker arm 51 is connected to the pull rod 52. Specifically, during installation, the upper end of the rocker arm 51 is rotatably connected to the pull rod 52, and the middle of the rocker arm 51 is rotatably connected to the upper shell 11. The lower end of the rocker arm 51 is connected to a lever 53, which is relatively fixed to the coupling gear sleeve 31. Specifically, in this embodiment, the lever 53 is connected to the first bearing 33 on the coupling gear sleeve 31. When the pull rod 52 is pulled, the rocker arm 51 swings, and the corresponding lever 53 pushes the coupling gear sleeve 31 to move axially.

[0054] The self-locking device in this embodiment comprises a first friction sleeve 41 and a second friction sleeve 42, which are respectively fitted onto a rotating lead screw 20. The first friction sleeve 41 and the rotating lead screw 20 are positioned by a flat joint, meaning that in the circumferential direction, the first friction sleeve 41 and the rotating lead screw 20 rotate synchronously, while the second friction sleeve 42 rotates freely relative to the rotating lead screw 20. In the axial direction, the axial end faces of the first friction sleeve 41 and the second friction sleeve 42 abut against each other. Simultaneously, a release torsion spring 40 is fitted onto the second friction sleeve 42, and in the initial state, the release torsion spring 40 holds the second friction sleeve 42 tightly. A self-locking torsion spring 43 is fitted onto the first friction sleeve 41.

[0055] In this embodiment, the first friction sleeve 41 preferably includes a front axle sleeve 411 and a rear axle sleeve 412. The front axle sleeve 411 and the rear axle sleeve 412 are connected by a thrust bearing in the axial middle. In other embodiments, the first friction sleeve 41 can be in the form of an integral axle sleeve.

[0056] When the inner tube 14 of the linear actuator extends normally, the drive motor 15 drives the rotating screw 20 to rotate in the forward direction through the clutch device. When the inner tube 14 extends to the predetermined position, the drive motor 15 stops. At this position, when the inner tube 14 tends to retract, the axial end faces of the first friction sleeve 41 and the second friction sleeve 42 abut against each other. Since the self-locking torsion spring 43 has a clamping resistance on the first friction sleeve 41, and the second friction sleeve 42 is also clamped by the released torsion spring 40 in the normal state, when the end faces of the first friction sleeve 41 and the second friction sleeve 42 abut against each other, frictional resistance is generated between them. This frictional resistance generates resistance on the rotating screw 20 to prevent it from reversing, thus completing the self-locking force.

[0057] When the linear actuator needs to retract normally, the drive motor 15 drives the rotating screw 20 to rotate in the opposite direction through the clutch device. At this time, the rotational torque of the rotating screw 20 will overcome the self-locking force provided by the self-locking device, and the rotating screw 20 will continue to reverse, thereby causing the transmission nut 21 to drive the inner tube 14 to retract.

[0058] When the linear actuator needs to retract quickly after extending to a predetermined position, this embodiment can unlock the self-locking device to achieve rapid release. In this embodiment, unlocking is mainly achieved through the second driving component, with the specific structure as follows: (This can be combined with...) Figures 2 to 4As shown, the second driving component includes a push block 54, which has a guide surface 541. The release torsion spring 40 includes a radially extending pin 401. In this embodiment, the pin 401 extends out of the top of the housing. The guide surface 541 is located on the side of the push block 54. The push block 54 is fixedly connected to the pull rod 52. That is, in this embodiment, the self-locking device and the clutch device share a pull rod 52. When the pull rod 52 is pulled, the guide surface 541 on the push block 54 abuts against the pin 401, causing the release torsion spring 40 to expand outward. When the screw expands outward, the resistance between the release torsion spring 40 and the second friction sleeve 42 will decrease accordingly. In this state, when the end faces of the first friction sleeve 41 and the second friction sleeve 42 abut against each other, the second friction sleeve 42 will rotate synchronously with the first friction sleeve 41. Thus, the first friction sleeve 41 will not generate resistance to the rotating screw 20, thereby achieving the purpose of rotating the screw 20 without resistance. If the clutch device is disconnected at this time, and the self-locking device is also unlocked, the rotating screw 20 is basically in a free-spinning state in this state, which allows the transmission nut 21 to retract quickly.

[0059] In addition, in this embodiment, the guide surface 541 is used to gradually push and release the torsion spring 40. This release method can achieve the purpose of gradually reducing the self-locking force, so that the self-locking force will not disappear immediately, thus creating a stepless adjustment.

[0060] To better optimize the operation of the clutch and self-locking mechanisms, this embodiment optimizes the operating sequence of the clutch and self-locking mechanisms, such as... Figure 2 As shown, the pull rod 52 has an adjustable oblong hole, and the push block 54 is fixed to the oblong hole by a fastening screw. The oblong hole is designed mainly to adjust the initial position of the push block 54. Setting the initial position serves two purposes: firstly, to compensate for some actual assembly errors so that the push block 54 can more precisely abut against the release torsion spring 40; secondly, as mentioned in this article, to adjust the operating sequence between the clutch and the clutch mechanism. Figure 2 As shown, in the initial state, the guide surface 541 of the push block 54 needs to move a certain distance before it contacts the pin 401 of the release torsion spring 40. This distance can be understood as the idle travel of the push block 54. During this idle travel, the clutch device operates normally. The purpose of this is that the coupling sleeve 31 will be moved first. At the same time, during the reset, the self-locking device locks itself first, and then the clutch device engages the power. The advantage of this is that when the self-locking device generates the self-locking force, the rotation speed of the screw 20 will decrease, so that the coupling sleeve 31 will not be damaged when it engages with the transmission worm gear 22, which can greatly extend the service life.

[0061] In addition, in order to enable users to better perceive the magnitude of the release range, in this embodiment, the pull rod 52 is provided with a toothed strip 521, and the outer shell is provided with a movable locking tooth 522. The movable locking tooth 522 is connected to a spring. When the pull rod 52 is pulled, the movable locking tooth 522 engages with the toothed strip 521 one by one. The position of the movable locking tooth 522 on the toothed strip 521 can be used to sense the pulling stroke of the pull rod 52.

[0062] It should be noted that the structure of the self-locking device and the clutch device is not limited to the structure shown in this embodiment. Taking the self-locking device as an example, the self-locking device may only include a single third friction sleeve, which rotates synchronously with the rotating lead screw. The release torsion spring is fitted onto the third friction sleeve. In the initial state, the release torsion spring holds the third friction sleeve to generate resistance to the rotating lead screw, which is equivalent to the release torsion spring acting as a self-locking torsion spring. When the release torsion spring is pushed by the push block, the resistance of the release torsion spring to the third friction sleeve disappears. Taking the clutch device as an example, the clutch device may be implemented by other combinations of spline sleeve 34 and splines. Embodiment 2 below also shows different implementation methods of the self-locking device and the clutch device.

[0063] like Figures 6 to 7 As shown, to further enhance the release function of the linear actuator, in this embodiment, the linear actuator has a front pull head 16 connected to the end of the inner tube 14, and a hand-rotating release device 17 is connected between the front pull head 16 and the end of the inner tube 14. The power connection between the front pull head 16 and the inner tube 14 can be severed using the hand-rotating release device 17.

[0064] Specifically, the hand-rotating release device 17 includes a knob sleeve 171, a connecting sleeve 172, and a hand-rotating release torsion spring 173. The connecting sleeve 172 is fixedly connected to the inner tube 14. The front pull head 16 is fitted onto the connecting sleeve 172. The hand-rotating release torsion spring 173 is located between the connecting sleeve 172 and the front pull head 16. Specifically, the hand-rotating release torsion spring 173 is fitted onto the outside of the front pull head 16. The hand-rotating release torsion spring 173 also has corresponding pins 1731. The pins 401 protrude from the notch on the connecting sleeve 172 and abut against the knob sleeve 171. When the knob sleeve 171 is rotated, it is used to cause the hand-rotating release torsion spring 173 to contract radially or expand radially, thereby controlling the frictional resistance of the hand-rotating release torsion spring 173 against the front pull head 16.

[0065] Furthermore, the installation structure of the clutch device has also been optimized in this embodiment, as shown in the reference. Figure 4As shown, when the inner tube 14 of the linear actuator extends to the predetermined position and tends to retract, the rotating screw 20 will be subjected to axial force. After the rotating screw 20 is subjected to axial force, it will transmit the axial force to the first friction sleeve 41. The first friction sleeve 41 will then transmit the axial force to the second friction sleeve 42. The second friction sleeve 42 is fitted with a second bearing 44. At the same time, the second bearing 44 is axially limited by the limiting step 111 on the outer shell. Therefore, the axial force is directly transmitted to the outer shell through the second bearing 44 on the second friction sleeve 42.

[0066] Therefore, in this embodiment, the first friction sleeve 41, the second friction sleeve 42, and the second bearing 44 essentially constitute an axial limiting assembly. The rotating lead screw 20 transmits the axial force directly to the outer casing through this axial limiting assembly. Since the entire clutch device is located at the rear end of the limiting step 111 of the outer casing, the clutch device itself is not subjected to axial force during the entire axial force transmission process. Under such conditions, the user will need to exert less effort when using the first driving component to actuate the coupling sleeve in the clutch device. At the same time, since the clutch device is not subjected to axial force from the rotating lead screw 20, the service life of the clutch device can be greatly improved.

[0067] Example 2:

[0068] like Figures 8 to 11 As shown, the operating principle of this embodiment is similar to that of Embodiment 1, with the main difference being in the specific structure of the self-locking device, the clutch device, the first driving component, and the second driving component.

[0069] The self-locking device in this embodiment: In embodiment one, the first friction sleeve 41 and the second friction sleeve 42 are arranged axially side by side, and the outer end faces of the first friction sleeve 41 and the second friction sleeve 42 abut against each other. In this embodiment, the second friction sleeve 42 is fitted outside the first friction sleeve 41, and the outer end face of the first friction sleeve 41 abuts against the inner end face of the second friction sleeve 42. The installation between the first friction sleeve 41 and the rotating screw 20 is the same as in embodiment one. The first friction sleeve 41 still rotates synchronously with the rotating screw 20. At the same time, a self-locking torsion spring 43 is also fitted outside the first friction sleeve 41, and the release torsion spring 40 is still fitted outside the second friction sleeve 42. The working principle is similar to that in embodiment one, that is, the self-locking force of the self-locking torsion spring 43 mainly comes from the end face friction of the first friction sleeve 41 and the second friction sleeve 42.

[0070] In this embodiment, the first friction sleeve 41 has a similar structure to that in Embodiment 1, and also includes a front axle sleeve 411 and a rear axle sleeve 412. A thrust bearing is provided between the front axle sleeve 411 and the rear axle sleeve 412. A self-locking torsion spring 43 is simultaneously sleeved on the outside of the front axle sleeve 411 and the rear axle sleeve 412. The rear axle sleeve 412 abuts against the inner end face of the second friction sleeve 42.

[0071] The advantage of this self-locking device is that it requires less installation space, mainly in the axial space, which helps to reduce the overall size of the linear actuator.

[0072] The clutch device in this embodiment further includes a spline sleeve 34, which is located between the rotating lead screw 20 and the coupling gear sleeve 31. The spline sleeve 34 and the rotating lead screw 20 rotate synchronously. The torque transmission is mainly achieved by the flatness between the spline sleeve 34 and the rotating lead screw 20. The coupling gear sleeve 31 and the transmission worm gear 22 always maintain synchronous rotation. The first driving component mainly drives the coupling gear sleeve 31 and the spline sleeve 34 to engage and disengage.

[0073] In this embodiment, the first driving component is slightly different from that in Embodiment 1. It adopts a toggle block 55, which is rotatably connected to the pull rod 52. When the pull rod 52 is pulled, the toggle block 55 actuates the axial movement of the coupling sleeve 31.

[0074] In this embodiment, the second driving component is directly integrated with the pull rod 52, as can be seen in [reference]. Figure 8 As shown, a guide surface 541 is provided on the pull rod 52.

[0075] Furthermore, compared to Embodiment 1, this embodiment omits the hand-rotating release device 17.

[0076] The clutch device in this embodiment is the same as in embodiment one. The coupling gear sleeve itself is not subjected to axial force from the rotating lead screw 20. The axial force transmission in this embodiment is as follows:

[0077] When the inner tube 14 of the linear actuator extends to the predetermined position and tends to retract, the rotating screw 20 will be subjected to axial force. The spline sleeve 34 abuts against the shoulder of the rotating screw 20, so the axial force of the rotating screw 20 is transmitted to the spline sleeve 34 immediately. The end face of the spline sleeve 34 abuts against the end face of the first friction sleeve 41, that is, the spline sleeve 34 and the first friction sleeve 41 are axially limited, so the axial force is transmitted to the first friction sleeve 41. The tail end face of the first friction sleeve 41 abuts against the inner end face of the second friction sleeve 42, so the axial force is transmitted to the second friction sleeve 42. A tapered roller bearing 23 is provided between the tail end face of the second friction sleeve 42 and the tail pull head 10, so the axial force is finally transmitted to the tail pull head 10 through the tapered roller bearing 23.

[0078] In this embodiment, the spline sleeve 34, the first friction sleeve 41, and the second friction sleeve 42 together constitute an axial limiting kit. The rotating lead screw 20 transmits axial force to the tail pull head 10 through the axial limiting kit. From the perspective of the entire axial force transmission process, the coupling gear sleeve in this embodiment will never be subjected to axial force. Therefore, the first driving component is also very effortless when moving the coupling gear sleeve.

[0079] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that the present invention includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of the present invention will be included within the scope of the claims.

Claims

1. A linear actuator comprising a drive motor, a transmission assembly, a rotary screw and a transmission nut, the drive motor driving the rotary screw to rotate via the transmission assembly, the rotary screw rotating to cause the transmission nut to move axially along the rotary screw, characterised in that, The linear actuator further comprises: A clutch device is arranged between the transmission assembly and the rotating screw rod, and is used to connect or cut off the power connection between the transmission assembly and the rotating screw rod; A self-locking device generates a frictional resistance to the rotating screw rod when the rotating screw rod is reversed, and the self-locking device comprises a release torsion spring used to unlock the self-locking device; The hand-pulling release assembly comprises a first driving member and a second driving member, the first driving member is connected with the clutch device, and the second driving member is used to connect the self-locking device, the hand-pulling release assembly comprises an initial state and a completely released state, and in the process from the initial state to the completely released state, the first driving member drives the clutch device to cut off the power connection, and the second driving member drives the release torsion spring to be loosened; The self-locking device comprises a first friction sleeve and a second friction sleeve, the first friction sleeve and the second friction sleeve are sleeved on the rotating screw rod respectively, and the axial end faces of the first friction sleeve and the second friction sleeve abut against each other, the first friction sleeve rotates synchronously with the rotating screw rod, the second friction sleeve rotates freely relative to the rotating screw rod, the self-locking torsion spring is sleeved on the first friction sleeve, and the release torsion spring is sleeved on the second friction sleeve; or the self-locking device comprises a third friction sleeve, the third friction sleeve rotates synchronously with the rotating screw rod, and the release torsion spring is sleeved on the third friction sleeve; In the process that the hand-pulling release assembly is returned to the initial state from the completely released state, the second driving member is first disengaged from the release torsion spring on the self-locking device to generate a self-locking force, the first driving member is correspondingly disengaged from the clutch device after the release torsion spring is returned, and the linear actuator comprises an outer tube and an inner tube which is telescopic relative to the outer tube.

2. The linear actuator of claim 1, wherein, The transmission assembly comprises a transmission worm and a transmission worm wheel, the transmission worm is connected with the driving motor, the transmission worm wheel is sleeved outside the rotating screw rod, and the clutch device is arranged between the transmission worm wheel and the rotating screw rod.

3. The linear actuator of claim 2, wherein, The clutch device comprises a shaft coupling tooth sleeve, the transmission worm wheel is provided with a tooth groove which is matched with the shaft coupling tooth sleeve for transmission, the shaft coupling tooth sleeve is sleeved on the rotating screw rod and can move axially relative to the rotating screw rod.

4. The linear actuator of claim 3, wherein, The clutch device further comprises a reset spring which generates an axial reset force to the shaft coupling tooth sleeve.

5. The linear actuator of claim 1, wherein, The linear actuator further comprises a shell, the first driving member comprises a swing rod which is rotatably installed on the shell, the hand-pulling release assembly further comprises a pull rod which is arranged to be axially movable relative to the rotating screw rod, the swing rod is connected with the pull rod, and when the pull rod is pulled, the swing rod swings to axially push the clutch device.

6. The linear actuator of claim 1, wherein, The second driving member comprises a push block which is provided with a guide surface, the release torsion spring comprises a radially extending pin, the hand-pulling release assembly comprises a pull rod which is arranged to be axially movable relative to the rotating screw rod, the pull rod is connected with the push block, the pull rod is pulled, the guide surface on the push block abuts against the pin to make the release torsion spring expand outward.

7. The linear actuator of claim 1, wherein, An end portion of the inner tube is connected with a front pull head, and a hand-rotating release device is connected between the end portion of the inner tube and the front pull head.

8. The linear actuator of claim 7, wherein, The hand-rotating release device comprises a knob sleeve, a connecting sleeve base and a hand-rotating release torsion spring, the connecting sleeve base is fixedly connected with the inner tube, the front pull head is sleeved with the connecting sleeve base, the hand-rotating release torsion spring is arranged between the connecting sleeve base and the front pull head, and the knob sleeve is used for driving the hand-rotating release torsion spring to contract or expand radially.

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