Patent Description:
Linear actuator, also known as electric push rod, is widely used in furniture, medical equipment, solar power generation and other fields. Its main structure includes a drive motor, a drive worm, a worm wheel, a screw and a nut. Its working principle is that the drive motor drives the drive worm to rotate, the drive worm meshes with the worm gear to drive the worm gear to rotate, the worm gear rotates to drive the screw to rotate, and the screw rotates to drive the nut to move axially. The nut is generally connected with an inner tube, thereby achieving the telescopic movement of the inner tube.

Combined with the application environment of the linear actuator, when the linear actuator encounters the fault of the drive motor, or when the power is cut off or when the power needs to be cut off, a clutch means will be added to the linear actuator. The clutch means is mainly used to cut off the power between the drive motor and the rotating screw, so that the reverse push can be achieved by manually driving the rotating screw to rotate.

For clutch means, most of them accomplish motive docking by pivoting one of the two components to move axially. If the two components are acted by axial force, it will inevitably affect the difficulty of pivoting, resulting in unsmooth clutch means, poor operation experience and even possible damage to the clutch means. <CIT> relates to an actuator with a quick-release mechanism allow quick adjustments on the medical beds such that the precious time for medical treatments can be significantly saved. The actuator comprises a transmission mechanism with a worm gear member, a quick-release mechanism with a clutch gear and a position detection mechanism. By using the position detection mechanism, the engagement position or disengagement position of the protruding keys of the worm gear member and the key slots of the clutch gear can be determined to avoid loss or error.

The technical problem to be solved by the present invention is that the present invention overcomes the deficiency of the prior art and provides a linear actuator with smooth clutching, so that the clutch means has better smoothness when being driven.

To solve the above technical problem, the present invention adopts a linear actuator as described in claim <NUM>. Advantageous embodiments are described in the dependent claims.

The present invention has the advantages that:
the linear actuator in the present invention is provided with a clutch means, which is mainly implemented by driving the axial movement of the coupling gear sleeve, so that it is optimal for the coupling gear sleeve to be subjected to forces from the driving member only, avoiding or reducing axial forces from other components as much as possible. In the whole linear actuator, the axial force of other components mainly comes from the rotating screw, the rotating screw pushes the target to be pushed through the drive nut, and the target to be pushed may naturally react the bearing capacity to the rotating screw. If the rotating screw transmits the axial force to the coupling gear sleeve of the clutch means, the resistance may increase when the user needs to toggle the coupling gear sleeve, and the clutch means will be easily damaged after long-term use.

For this reason, in this embodiment, the axial limiting sleeve is sleeved outside the rotating screw, and the axial limiting sleeve itself is axially limited to the rotating screw. Secondly, the axial limiting sleeve is also axially limited with the housing. With this installation method, the axial force on the rotating screw can be transmitted to the housing through the axial limiting sleeve, while the axial force is not transmitted between the coupling gear sleeve and the axial limiting sleeve, therefore, the coupling gear sleeve will not be subjected to the axial force from the rotating screw, and the user will save labor when using the driving member to toggle the coupling gear sleeve, and at the same time, the strength requirement of the coupling gear sleeve itself is also reduced, which is also beneficial to prolonging the service life of the clutch means.

Preferably, the first friction sleeve and the second friction sleeve are axially arranged side by side, and outer end faces of the first friction sleeve and the second friction sleeve abut against each other.

Preferably, the second friction sleeve is sleeved outside the first friction sleeve, and an outer end face of the first friction sleeve abuts against an inner end face of the second friction sleeve.

Preferably, the second friction sleeve is provided with a bearing, the housing is provided with a bearing groove for mounting the bearing, and the bearing is axially limited with the housing.

Preferably, the first friction sleeve is sleeved at an end portion of the rotating screw, and the housing includes a tail puller at the end portion, and the tail puller is axially limited with the second friction sleeve.

Preferably, a spline sleeve is arranged between the rotating screw and the coupling gear sleeve, and the spline sleeve is axially limited with the first friction sleeve, and the axial limiting sleeve includes the spline sleeve, the first friction sleeve and the second friction sleeve.

Preferably, a tapered roller bearing is arranged between the second friction sleeve and the tail puller.

Preferably, the linear actuator further includes a hand-pulling release assembly, the hand-pulling release assembly further includes a pull rod and a swing link, the pull rod being axially movable relative to the rotating screw, the swing link being rotationally connected with the pull rod, and when the pull rod is pulled, the swing link swings to axially push the coupling gear sleeve.

These features and advantages of the present invention will be disclosed in detail in the following detailed description of the embodiment and the drawings.

The present invention is further explained below with reference to the accompanying drawings:.

The technical solutions of the embodiments of the present invention are explained and illustrated below in conjunction with the accompanying drawings of the embodiments of the present invention, but the following embodiments are only preferred embodiments, not all of them. Based on the embodiments in the implementations, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of the present invention.

In the following description, the appearance of terms such as "inner", "outer", "upper", "lower", and "left" and "right" indicating orientation or positional relationship is based on the orientation or positional relationship shown in the drawings only for convenience of description of embodiments and simplification of description, it is not intended to indicate or imply that the devices or elements referred to must have a particular orientation, be constructed or operate in a particular orientation, and therefore, should not be construed as limitations to the present invention.

As shown in <FIG>, the embodiment is a linear actuator. Linear actuators are also commonly called linear actuators or electric push rods. The linear actuator includes a housing, an outer tube <NUM>, an inner tube <NUM>, a drive motor <NUM>, a gearing assembly, a rotating screw <NUM> and a drive nut <NUM>. The drive motor <NUM> drives the rotating screw <NUM> to rotate through the gearing assembly. The rotating screw <NUM> rotates to drive the drive nut <NUM> to move axially along the rotating screw <NUM>, and the drive nut <NUM> is fixedly connected with the inner tube <NUM>. When the drive nut <NUM> moves axially, it drives the inner tube <NUM> to move axially relative to the outer tube <NUM> and the housing, and an outer end of the inner tube <NUM> is connected to the target to be driven. The linear actuator in this embodiment further includes:.

A clutch means is arranged between the gearing assembly and the rotating screw <NUM> for connecting or cutting off the power connection between the gearing assembly and the rotating screw <NUM>.

The specific structure of the clutch means in the embodiment is as follows: the clutch means includes a coupling gear sleeve <NUM>, the coupling gear sleeve <NUM> itself is fitted with the rotating screw <NUM> through a flat position. That is, in a circumferential direction, the coupling gear sleeve <NUM> and the rotating screw <NUM> rotate synchronously, but the coupling gear sleeve <NUM> is axially movable along the rotating screw <NUM> in the axial direction. The coupling tooth sleeve <NUM> has a plurality of tooth-shaped parts in a direction of the drive worm22, an end face of the worm wheel <NUM> is provided with a tooth space matched with the coupling gear sleeve <NUM> for transmission. When the coupling tooth sleeve <NUM> is close to the worm wheel <NUM>, the tooth-shaped parts are inserted into the tooth space, and the coupling tooth sleeve <NUM> and the worm wheel <NUM> rotate synchronously. When the coupling tooth sleeve <NUM> is far away from the worm wheel <NUM>, the tooth-shaped parts are separated from the tooth space, and the coupling tooth sleeve <NUM> is separated from the worm wheel <NUM>, that is, the rotating screw <NUM> will be in a state of no power connection. Referring to <FIG>, the coupling gear sleeve <NUM> is inserted into the worm wheel <NUM>.

In this embodiment, the rotating screw <NUM> is sleeved with an axial limiting sleeve, the axial limiting sleeve and the housing are abutted axially, and the axial limiting sleeve and the rotating screw <NUM> maintain alignment in an axial direction, when the rotating screw <NUM> is subjected to an axial load, the rotating screw <NUM> transmits axial force to the housing through the axial limiting sleeve, and the axial force is not transmitted between the coupling gear sleeve <NUM> and the axial limiting sleeve in the axial direction.

The axial limiting sleeve is sleeved outside the rotating screw <NUM>, and the axial limiting sleeve itself is axially limited to the rotating screw. Secondly, the axial limiting sleeve is also axially limited with the housing. With this installation method, the axial force on the rotating screw can be transmitted to the housing through the axial limiting sleeve, while the axial force is not transmitted between the coupling gear sleeve <NUM> and the axial limiting sleeve, therefore, the coupling gear sleeve <NUM> will not be subjected to the axial force from the rotating screw, and the user will save labor when using the driving member to toggle the coupling gear sleeve <NUM>, and at the same time, the strength requirement of the coupling gear sleeve <NUM> itself is also reduced, which is also beneficial to prolonging the service life of the clutch means.

In this embodiment, the linear actuator further includes a self-locking device, which generates frictional resistance to the rotating screw <NUM> when the rotating screw <NUM> rotates reversely. The structure of the self-locking device in this embodiment is as follows: the self-locking device includes a first friction sleeve <NUM>, a second friction sleeve <NUM>, a release torsion spring <NUM>, a self-locking torsion spring <NUM>, the first friction sleeve <NUM> and the second friction sleeve <NUM> are respectively sleeved on the rotating screw <NUM>, the first friction sleeve <NUM> and the rotating screw <NUM> are positioned in a flat position, that is, in the circumferential direction, the first friction sleeve <NUM> and the rotating screw <NUM> rotate synchronously, while the second friction sleeve <NUM> rotates freely relative to the rotating screw <NUM>, and in the axial direction, axial end faces of the first friction sleeve <NUM> and the second friction sleeve <NUM> abut against each other. Meanwhile, the release torsion spring <NUM> is sleeved on the second friction sleeve <NUM>, and the release torsion spring <NUM> clasps the second friction sleeve <NUM> at all times in the initial state. The first friction sleeve <NUM> is sleeved with the self-locking torsion spring <NUM>.

Referring to <FIG>, when the inner tube <NUM> of the linear actuator extends to a predetermined position and has a tendency to retract, the rotating screw <NUM> is subjected to axial force, after that, the axial force is transmitted to the first friction sleeve <NUM>, and the first friction sleeve <NUM> in turn transmits the axial force to the second friction sleeve <NUM>. The second friction sleeve <NUM> is sleeved with a second bearing <NUM>, and the second bearing <NUM> is axially limited with a limiting step <NUM> on the housing, so the axial force is directly transmitted to the housing through the second bearing <NUM> on the second friction sleeve <NUM>.

Therefore, based on the self-locking device in this embodiment, the first friction sleeve <NUM>, the second friction sleeve <NUM> and the second bearing <NUM> in the self-locking device are naturally formed into an axial limiting sleeve, and the rotating screw <NUM> directly transmits the axial force to the housing through the axial limiting sleeve. Since the entire clutch means is positioned at a rear end of the limiting step <NUM> of the housing, the clutch means itself is not affected by the axial force during the whole transmission process of the axial force. In such an environment, the user can save more effort when toggling the coupling gear sleeve <NUM> in the clutch means. Also, since the clutch means is not subjected to the axial force from the rotating screw <NUM>, the service life of the clutch means can be greatly prolonged. Alternatively, it should be noted that if there is no self-locking device in the linear actuator, an additional structure similar to a shaft sleeve can be added to the rotating screw <NUM> as the axial limiting sleeve.

The first friction sleeve <NUM> preferably includes a front shaft sleeve <NUM> and a rear shaft sleeve <NUM> in this embodiment, and the front shaft sleeve <NUM> and the rear shaft sleeve <NUM> are abutted by a thrust bearing in the axial middle. In other embodiments, the first friction sleeve <NUM> may be in the form of an integral shaft sleeve.

In terms of the hand-pulling release assembly, the hand-pulling release assembly includes a first driving member and a second driving member, the first driving member is connected with the clutch means, the second driving member is used for connecting the self-locking device, the hand-pulling 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 member drives the clutch means to disconnect the power connection, and the second driving member drives the release torsion spring <NUM> to release.

The linear actuator in this embodiment is provided with both the clutch means and the self-locking device, making the linear actuator more comprehensive in function, and the clutch means combined with the self-locking device also has an advantage that since the power is disconnected by the clutch means, the rotating screw <NUM> is almost in a completely free rotating state, which easily leads to too fast retraction speed of the linear actuator. However, the self-locking device can just provide a certain resistance to prevent the rotating screw <NUM> from rotating too fast, thus avoiding too fast retraction speed of the drive nut <NUM>.

Secondly, the self-locking device in this embodiment is also provided with a release torsion spring <NUM>, that is, the self-locking device itself can be unlocked. When the release torsion spring <NUM> is released, the self-locking device is in an unlocked state. At this time, the self-locking device has little resistance to the rotating screw <NUM> regardless of the forward rotation or reverse rotation of the linear actuator. This situation can make the linear actuator in a fast release state, that is, it can be quickly retracted.

Finally, the linear actuator in this embodiment is provided with a hand-pulling release assembly. The hand-pulling release assembly includes a first driving member and a second driving member, the first driving member and the second driving member are respectively used for driving the clutch means and the self-locking device, when the linear actuator needs to be released quickly, an operator operates the hand-pulling release assembly to make it in a completely released state, which can make the clutch means in a disconnected state and the self-locking device in an unlocked state at the same time. A user can control two devices only by operating one hand-pulling release assembly, and such an operation is very convenient.

In this embodiment, the first driving member is mainly used for pivoting the coupling gear sleeve <NUM> to move axially. At the same time, in order to make the clutch means reset after the first driving member is pivoted, the clutch means in this embodiment also includes a return spring <NUM> which generates axial reset force to the coupling gear sleeve <NUM>. The end portion of the rotating screw <NUM> is provided with a limiting end <NUM>. The return spring <NUM> is sleeved on the rotating screw <NUM>, and both ends of the return spring are limited between the finite end <NUM> and the coupling gear sleeve <NUM>.

The housing in this embodiment includes an upper casing <NUM> and a lower casing <NUM>, and a first bearing <NUM> is arranged between the coupling gear sleeve <NUM> and the casing to reduce the friction resistance when the coupling gear sleeve <NUM> rotates.

The structure of the first driving member of this embodiment is as follows: the first driving member includes a swing link <NUM> rotationally mounted on the housing, the hand-pulling release assembly also includes a pull rod <NUM> axially movable with respect to the rotating screw <NUM>, the swing link <NUM> is connected with the pull rod <NUM>. During specific installation, an upper end of the swing link <NUM> is rotationally connected with the pull rod <NUM>, the swing link <NUM> is rotationally connected to the upper casing <NUM>, and a lower end of the swing link <NUM> is connected with a shift block <NUM>, which is relatively fixed with the coupling gear sleeve <NUM>. Specifically, in this embodiment, the shift block <NUM> is connected with the first bearing <NUM> on the coupling gear sleeve <NUM>. When the pull rod <NUM> is pulled, the swing link <NUM> swings, and the corresponding shift block <NUM> pushes the coupling gear sleeve <NUM> to move axially.

When the inner tube <NUM> in the linear actuator is normally extended, the drive motor <NUM> drives the rotating screw <NUM> to rotate forward through the clutch means, and when the inner tube <NUM> is extended to a predetermined position, the drive motor <NUM> stops. At this position, when the inner tube <NUM> has a retract tend, the axial end faces of the first friction sleeve <NUM> and the second friction sleeve <NUM> abut against each other. Since the self-locking torsion spring <NUM> has a clasping resistance effect on the first friction sleeve <NUM>, and the second friction sleeve <NUM> is also clasped by the release torsion spring <NUM> in a normal state, when the end faces of the first friction sleeve <NUM> and the second friction sleeve <NUM> are abutted against each other, friction resistance is generated therebetween, and the friction resistance generates resistance to the rotating screw <NUM> to prevent its reversal, so as to achieve the self-locking force.

When the linear actuator needs to retract normally, the drive motor <NUM> drives the rotating screw <NUM> to rotate in a reverse direction through the clutch means. At this time, a rotating torque of the rotating screw <NUM> will overcome the self-locking force provided by the self-locking device, and the rotating screw <NUM> will continue to reverse, so that the drive nut <NUM> drives the inner tube <NUM> to retract.

When the linear actuator is extended to a predetermined position, and need to retract quickly, this embodiment can unlock the self-locking device, to achieve the purpose of rapid release, the unlocking in this embodiment is mainly realized by the second driving member, the specific structure is as follows: as shown in <FIG>, the second driving member includes a push block <NUM>, the push block <NUM> is provided with a guide surface <NUM>, the release torsion spring <NUM> includes a pin <NUM> extending radially, , the pin <NUM> in this embodiment extends out of a top of the housing, the guide surface <NUM> is provided on a side surface of the push block <NUM>, the push block <NUM> is fixedly connected to a pull rod <NUM>. That is, the self-locking device and the clutch means in this embodiment share the same pull rod <NUM>, as the pull rod <NUM> is pulled, the guide surface <NUM> on the push block <NUM> is in contact with the pin <NUM>, such that the release torsion spring <NUM> is expanded outwardly, as the release torsion spring <NUM> is expanded outwardly, the resistance between the release torsion spring <NUM> and the second friction sleeve <NUM> is correspondingly reduced. In this state, when the end faces of the first friction sleeve <NUM> and the second friction sleeve <NUM> are abutted against each other, the second friction sleeve <NUM> rotates synchronously with the first friction sleeve <NUM>, therefore, the first friction sleeve <NUM> does not generate resistance to the rotating screw <NUM>, so that the purpose of no resistance to the rotating screw <NUM> is achieved. If the clutch means is disconnected and the self-locking device is unlocked at the same time, the rotating screw <NUM> is basically in a free idling state in this state, the drive nut <NUM> can be quickly retracted.

In addition, in this embodiment, the guide surface <NUM> is used to gradually push the release torsion spring <NUM>, with this release method, the self-locking force can be gradually reduced, so that the self-locking force will not disappear immediately, thereby achieving the purpose of stepless adjustment.

In order to better optimize the operation of the clutch means and the self-locking device, in this embodiment, the operation sequence of the clutch means and the self-locking device is optimized. As shown in <FIG>, the pull rod <NUM> is provided with an oblong hole for adjustment, the push block <NUM> is fixed to the oblong hole by a fastening screw, the oblong hole is designed primarily for adjusting the initial position of the push block <NUM>. There are two purposes for setting the initial position, one is to make up for some actual assembly errors, so that the push block <NUM> can more precisely abut the release torsion spring <NUM>, the second is that, as described herein, the operation sequence between the clutch means and the self-locking device can be adjusted. As shown in <FIG>, in the initial state, the guide surface <NUM> of the push block <NUM> needs to be moved a certain stroke before it comes into contact with the pin <NUM> of the release torsion spring <NUM>, this stroke can be understood as an idle stroke of the push block <NUM>. During this idle stroke, the clutch means is in normal operation, the purpose of this configuration is that the coupling tooth sleeve <NUM> will be pivoted first, at the same time, when reset, the self-locking device first self-locks, and then the clutch means carries out power connection. Advantageously, when the self-locking device generates self-locking force, the rotating speed of the rotating screw <NUM> will be reduced, so that the coupling tooth sleeve <NUM> and the worm wheel <NUM> will not be damaged when the coupling tooth sleeve <NUM> is engaged with the worm wheel <NUM>, and the service life can be greatly prolonged.

In addition, in order to enable users to better perceive the release amplitude, in this embodiment, the pull rod <NUM> is provided with toothed bars <NUM>, and the housing is provided with movable latches <NUM>, which is connected with a spring. When the pull rod <NUM> is pulled, the movable latches <NUM> are clamped into the toothed bars <NUM> one by one, and the pulling stroke of the pull rod <NUM> can be sensed by using the movable latches <NUM> at the position of the toothed bars <NUM>.

It should be noted that the structure of the self-locking device and the clutch means is not limited to the structure shown in this embodiment, in the case of the self-locking device, the self-locking device may include only a single third friction sleeve, the third friction sleeve rotates synchronously with the rotating screw, the release torsion spring is sleeved on the third friction sleeve. In the initial state, the release torsion spring clasps the third friction sleeve to generate resistance to the rotating screw, which is equivalent to the release torsion spring being 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. In the case of the clutch means, the clutch means can be implemented by a combination of other spline sleeves and splines. Embodiment II below also shows different embodiments of the self-locking device and the clutch means.

As shown in <FIG>, in order to further increase the release function of the linear actuator, the linear actuator in the present embodiment has a front puller <NUM> connected to an end portion of the inner tube <NUM>, and a hand-rotating release device <NUM> is connected between the front puller <NUM> and the end portion of the inner tube <NUM>. The power connection between the front puller <NUM> and the inner tube <NUM> can be cut off by the hand-rotating release device <NUM>.

Specifically, the hand-rotating release device <NUM> includes a knob sleeve <NUM>, a connecting sleeve seat <NUM> and a hand-rotating release torsion spring <NUM>, the connecting sleeve seat <NUM> is fixedly connected with the inner pipe <NUM>, the front puller <NUM> is fitted with the connecting sleeve seat <NUM>, and the hand-rotating release torsion spring <NUM> is provided between the connecting sleeve seat <NUM> and the front puller <NUM>. Specifically, the hand-rotating release torsion spring <NUM> is sleeved outside the front puller <NUM>, and the hand-rotating release torsion spring <NUM> also has a corresponding pin <NUM>, the pin <NUM> penetrates through a gap in the connecting sleeve seat <NUM> and abuts against the knob sleeve <NUM>, and the knob sleeve <NUM> is used to pivot the hand-rotating release torsion spring <NUM> to contract radially or expand radially when rotated, thereby controlling the frictional resistance of the hand-rotating release torsion spring <NUM> to the front puller <NUM>.

As shown in <FIG>, the operation principle of this embodiment is similar to that of the embodiment I, mainly in that the specific structures of the self-locking device, the clutch means, the first driving member and the second driving member are different.

Regarding the self-locking device of the embodiment, in the embodiment I, the first friction sleeve <NUM> and the second friction sleeve <NUM> are axially arranged side by side, outer end faces of the first friction sleeve <NUM> and the second friction sleeve <NUM> are abutted against each other. In this embodiment, the second friction sleeve <NUM> is sleeved outside the first friction sleeve <NUM>, the outer end face of the first friction sleeve <NUM> abuts against the inner end face of the second friction sleeve <NUM>. For the installation between the first friction sleeve <NUM> and the rotating screw <NUM> as in embodiment I, the first friction sleeve <NUM> rotates synchronously with the rotating screw <NUM>, and the self-locking torsion spring <NUM> is also sleeved outside of the first friction sleeve <NUM>, while the release torsion spring <NUM> is sleeved outside of the second friction sleeve <NUM>. The working principle is similar to that of embodiment I, that is, the self-locking force of the self-locking torsion spring <NUM> mainly comes from the end friction force of the first friction sleeve <NUM> and the second friction sleeve <NUM>.

The first friction sleeve <NUM> in this embodiment is similar in structure in embodiment I and also includes a front shaft sleeve <NUM> and a rear shaft sleeve <NUM>, a thrust bearing is arranged between the front shaft sleeve <NUM> and the rear shaft sleeve <NUM>, the self-locking torsion spring <NUM> is sleeved outside the front shaft sleeve <NUM> and the rear shaft sleeve <NUM> at the same time, and the rear shaft sleeve <NUM> abuts against an inner end face of the second friction sleeve <NUM>.

The advantage of this self-locking device is that the installation space is smaller, mainly the axial space is smaller, which is beneficial to reduce the volume of the whole linear actuator.

Regarding the clutch means of this embodiment, the clutch means in the embodiment also includes a spline sleeve <NUM>, the spline sleeve <NUM> is positioned between the rotating screw <NUM> and the coupling gear sleeve <NUM>, the spline sleeve <NUM> rotates synchronously with the rotating screw <NUM>, and torque transmission is mainly implemented by the flat position between the spline sleeve <NUM> and the rotating screw <NUM>, while the coupling gear sleeve <NUM> and the worm wheel <NUM> always keep synchronous rotation, and the first driving member mainly drives the clutch between the coupling gear sleeve <NUM> and the spline sleeve <NUM>.

The first driving member in this embodiment is slightly different from the embodiment I in that a shift block <NUM> is used, and the shift block <NUM> is rotationally connected with the pull rod <NUM>. When the pull rod <NUM> is pulled, the shift block <NUM> pivots the axial movement of the coupling gear sleeve <NUM>.

The second driving member in this embodiment is directly integrated with the pull rod <NUM> as shown in <FIG>. The pull rod <NUM> is provided with a guide surface <NUM>.

In addition, compared with the embodiment I, the hand-rotating release device <NUM> is eliminated in this embodiment.

The clutch means in this embodiment is the same as that in the embodiment I, the coupling gear sleeve itself is not subjected to the axial force from the rotating screw <NUM>, and the axial force in this embodiment is transmitted as follows:.

when the inner tube <NUM> of the linear actuator extends to a predetermined position and has a tendency to retract, the rotating screw <NUM> is subjected to axial force, the spline sleeve <NUM> abuts against the shoulder position of the rotating screw <NUM>, therefore, the axial force of rotating screw <NUM> is transmitted to the spline sleeve <NUM> at the first time, an end face of the spline sleeve <NUM> abuts against the end face of the first friction sleeve <NUM>. That is, the spline sleeve <NUM> and the first friction sleeve <NUM> are axially limited, therefore, the axial force is transmitted to the first friction sleeve <NUM>, and a tail end face of the first friction sleeve <NUM> abuts against the inner end face of the second friction sleeve <NUM>, so the axial force is transmitted to the second friction sleeve <NUM>, and a tapered roller bearing <NUM> is arranged between the tail end face of the second friction sleeve <NUM> and the tail puller <NUM>, so the axial force is finally transmitted to the tail puller <NUM> through the tapered roller bearing <NUM>.

In this embodiment, the spline sleeve <NUM>, the first friction sleeve <NUM> and the second friction sleeve <NUM> together constitute an axial limiting sleeve, the rotating screw <NUM> transmits the axial force to the tail puller <NUM> through the axial limiting sleeve. From the whole axial force transmission process, the coupling gear sleeve in this embodiment will not be acted by the axial force all the time, so the first driving member is also very labor-saving when pivoting the coupling gear sleeve.

Claim 1:
A linear actuator comprising a housing , a drive worm (<NUM>), a rotating screw (<NUM>) and a drive nut (<NUM>), the worm wheel (<NUM>) driving the rotating screw (<NUM>) to rotate, the rotating screw (<NUM>) rotating to drive the drive nut (<NUM>) to move axially along the rotating screw (<NUM>), a clutch means being arranged between the drive worm (<NUM>) and the rotating screw (<NUM>), wherein the clutch means comprises a coupling gear sleeve (<NUM>) axially movable relative to the rotating screw (<NUM>), the rotating screw (<NUM>) is sleeved with an axial limiting sleeve, the axial limiting sleeve and the housing are abutted axially, and the axial limiting sleeve and the rotating screw (<NUM>) maintain alignment in an axial direction, , characterized in that the axial limiting sleeve comprises a first friction sleeve (<NUM>) and a second friction sleeve (<NUM>), wherein the first friction sleeve (<NUM>) and the second friction sleeve (<NUM>) are abutted axially, a self-locking torsion spring (<NUM>) is sleeved outside the first friction sleeve (<NUM>), and the second friction sleeve (<NUM>) is sleeved with a release torsion spring (<NUM>) when the rotating screw (<NUM>) is subjected to an axial load, the rotating screw (<NUM>) transmits an axial force to the housing through the axial limiting sleeve, and the axial force is not transmitted between the coupling gear sleeve (<NUM>) and the axial limiting sleeve in the axial direction.