CN213185772U - One-way self-locking mechanism of motor and linear actuator - Google Patents

Abstract

The utility model discloses a motor one-way self-locking mechanism and a linear actuator, which belong to the technical field of motor self-locking, the motor one-way self-locking mechanism comprises a one-way bearing, a first friction piece, a second friction piece and an elastic piece, the one-way bearing is sleeved outside a motor shaft, the first friction piece and the outer ring of the one-way bearing are circumferentially limited, the second friction piece is circumferentially limited relative to a motor shell, the elastic piece axially extrudes the first friction piece and the second friction piece, when the motor shaft rotates forwards, the outer ring of the one-way bearing does not rotate, when the motor shaft rotates backwards, the motor shaft, the outer ring of the one-way bearing and the first friction piece synchronously rotate, the first friction piece and the second friction piece are in friction self-locking, one side of the first friction piece, which is opposite to the second friction piece, is provided with a plane retainer with a plurality of rolling pieces, the plane retainer is limited relative to the motor shell, the, the self-locking mechanism has stable and firm self-locking and good self-locking effect.

Description

One-way self-locking mechanism of motor and linear actuator

[ technical field ] A method for producing a semiconductor device

The utility model relates to a motor auto-lock technical field, concretely relates to one-way self-locking mechanism of motor and linear actuator.

[ background of the invention ]

The linear actuator is widely applied to various fields, including electric lifting tables, electric beds, electric sofas and the like, and generally comprises a driving motor, a rotating lead screw and a transmission nut, wherein the driving motor drives the rotating lead screw to rotate, the transmission nut is driven to axially move when the rotating lead screw rotates, and the transmission nut can be connected with a driving object, so that the driving purpose is realized.

For linear actuators, self-locking is an essential function, such as automatic lifting tables, when the drive motor is not running, requiring the linear actuator to have self-locking capability, so as to prevent the lifting table from automatically descending and returning, the self-locking of the existing linear actuator comprises flexible self-locking and rigid self-locking, the flexible self-locking is realized by a braking torsion spring, the braking torsion spring is driven to be tightly held when the rotating screw rod rotates reversely to generate braking force, but the braking self-locking force of the torsion spring is relatively insufficient, the rigid self-locking is mainly concentrated on the motor, and comprises rigid self-locking modes such as worm and gear self-locking, helical gear self-locking and the like, but the existing rigid self-locking mode has the defects of low motor efficiency when the self-locking performance is good and poor self-locking performance when the motor efficiency is low, meanwhile, some multi-chip manufacturing structures are irregular in shape, noise is difficult to control, surface contact friction loss is serious, and the service life is shortened.

[ Utility model ] content

The utility model aims to solve the technical problem that overcome not enough among the prior art, design the steady firm one-way self-locking mechanism of motor of auto-lock.

In order to solve the technical problem, the utility model adopts the following technical scheme:

an one-way self-locking mechanism of a motor comprises a motor shell and a motor shaft, the one-way self-locking mechanism of the motor comprises an one-way bearing, a first friction piece, a second friction piece and an elastic piece, the one-way bearing is sleeved outside the motor shaft, the first friction piece and an outer ring of the one-way bearing are circumferentially limited, the second friction piece is circumferentially limited relative to the motor shell, the elastic piece axially extrudes the first friction piece and the second friction piece, the one-way bearing freely rotates when the motor shaft rotates forwards, the outer ring of the one-way bearing does not rotate, the one-way bearing is locked when the motor shaft rotates backwards, the motor shaft, the outer ring of the one-way bearing and the first friction piece synchronously rotate, the first friction piece and the second friction piece are self-locked through friction, a plane retainer with a plurality of rolling pieces is arranged on one side of the first friction piece back to the second friction piece, the rolling elements are in contact connection with the first friction element on one side of the plane retainer and roll along with the rotation of the first friction element.

The beneficial effect of this scheme of adoption:

adopt motor shaft and one-way bearing to drive the cooperation structure of first friction spare and fixed friction spare in this scheme, utilize the one-way pivoted characteristic of one-way bearing, free rotation in a direction promptly, lock on another direction, consequently design into when the motor shaft corotation in this scheme, one-way bearing free rotation, thereby the free forward rotation of motor shaft, one-way bearing outer lane, first friction spare and second friction spare homogeneous phase are fixed motionless, because one-way bearing free rotation, make one-way self-locking mechanism can not produce any influence to motor normal rotation, avoid producing extra friction and increase heat and produce, transmission efficiency is high, reduce the energy consumption.

When the motor shaft has a tendency of reverse rotation, the one-way bearing is locked and integrated, the one-way bearing and the motor shaft synchronously rotate and drive the first friction piece to rotate, the first friction piece and the second friction piece generate relative motion and are tightly contacted under the axial extrusion of the elastic piece to generate friction force, according to the reaction force, the friction force generates resistance to the rotation of the motor shaft to prevent the motor shaft from continuously rotating to finish self-locking, the axial elastic force generated by the elastic piece is larger, the self-locking effect is better, the matching precision requirement of the self-locking structure on all the parts is lower, the processing difficulty is reduced, the self-locking force generated by the one-way self-locking mechanism is excellent and is rigid self-locking compared with the flexible self-locking generated by a torsion spring structure, the self-locking force is larger, the stability after self-locking is better, but the rigid self-locking generated by a worm gear and a helical, reduce noise and prolong the service life of the motor.

And the one-way self-locking mechanism of this scheme is equipped with the plane holder that is fixed relative to the casing, when the motor shaft reversal drove first friction piece and rotates, first friction piece and rolling piece contact and drive the rolling piece original place and roll, be equivalent to first friction piece rotates on a plurality of rolling pieces, through the roll of rolling piece, make the extrusion force distribution between first friction piece and the second friction piece more even, thereby make the friction atress evenly balanced, the auto-lock is more steady firm, and reduce the local wear of friction piece, further extension one-way self-locking mechanism life.

Preferably, the other side of the plane retainer is provided with a pressing sheet, and the pressing sheet is in contact connection with a plurality of rolling members.

Preferably, the motor shell comprises a shell body and a tailstock, the motor shaft extends out of the tailstock, the second friction piece, the first friction piece, the plane retainer and the pressing piece are sequentially distributed from the tailstock to the outside along the axial direction of the motor shaft, and the elastic piece is abutted to the pressing piece; or the motor shell comprises a shell body and a tailstock, the motor shaft extends out of the tailstock, the pressing sheet, the plane retainer, the first friction piece and the second friction piece are sequentially distributed from the tailstock to the outside along the axial direction of the motor shaft, and the elastic piece is abutted to the second friction piece.

Preferably, the one-way self-locking mechanism comprises at least two first friction pieces, and the two first friction pieces are respectively positioned on two sides of the plane retainer.

Preferably, a matched second friction piece is arranged on one side, opposite to the plane retainer, of each first friction piece, and the elastic piece is abutted to the second friction piece.

Preferably, the elastic element is a helical compression spring, the motor housing comprises a cover, the cover is arranged outside the unidirectional self-locking mechanism, the cover comprises an outer ring, an inner ring is arranged in the outer ring, a channel is formed between the outer ring and the inner ring, and one end of the helical compression spring is accommodated in the channel and sleeved on the outer wall of the inner ring.

Preferably, the elastic part is a helical compression spring or an elastic sheet, the motor shell comprises a shell body and a cover cap which are detachably connected, the cover cap comprises a rear cover, the elastic part is close to the rear cover, and an elastic force adjusting assembly for adjusting the elastic force of the helical compression spring is further arranged on the motor.

Preferably, the elasticity adjusting part comprises an adjusting sheet and an adjusting screw, the adjusting sheet is arranged between the rear cover and the spiral pressure spring, one end of the adjusting screw penetrates through the rear cover to be connected with the adjusting sheet, and the adjusting screw can stretch out and draw back towards the direction of the adjusting sheet relative to the rear cover.

Preferably, the first friction piece is provided with a positioning protrusion, and the outer ring of the one-way bearing is provided with a positioning groove matched with the positioning protrusion.

The utility model discloses an another technical scheme as follows:

a linear actuator comprises an inner tube, an outer tube, a rotary screw rod and a motor, wherein the motor drives the rotary screw rod to rotate, the rotary screw rod drives a transmission nut to axially move when rotating, the transmission nut moves to drive the inner tube and the outer tube to relatively stretch, and the motor is provided with a motor one-way self-locking mechanism in any technical scheme.

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

[ description of the drawings ]

The utility model is further described with the following drawings:

fig. 1 is a schematic view of the three-dimensional structure of the motor of the present invention.

Fig. 2 is an explosion diagram of a motor according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view of a motor according to an embodiment of the present invention.

Fig. 4 is an enlarged view of a portion a in fig. 3.

Fig. 5 is a schematic view of a three-dimensional structure of a cover according to an embodiment of the present invention.

Fig. 6 is a schematic view of a three-dimensional structure of an unidirectional bearing according to an embodiment of the present invention.

Fig. 7 is a schematic perspective view of a first friction member according to an embodiment of the present invention.

Fig. 8 is a schematic perspective view of a planar holder according to an embodiment of the present invention.

Fig. 9 is an explosion diagram of three motors according to the embodiment of the present invention.

Fig. 10 is a schematic view of a three-cover three-dimensional structure according to an embodiment of the present invention.

Reference numerals: a motor shaft 10; a housing body 11; a tailstock 12; a cover 13; an outer ring 131; an inner collar 132; a channel 133; a rear cover 134; a perforation 135; a one-way bearing 101; a first friction member 102; a second friction member 103; an elastic member 104; a flat holder 105; the rolling members 105 a; a tablet 106; an adjusting screw 107; a tab 108 is provided.

[ detailed description ] embodiments

The technical solutions of the embodiments of the present invention are explained and explained below with reference to the drawings of the embodiments of the present invention, but the embodiments described below are only preferred embodiments of the present invention, and not all embodiments. Based on the embodiments in the embodiment, other embodiments obtained by those skilled in the art without any creative work belong to the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and to simplify the description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, unless otherwise specified, "a plurality" means two or more unless explicitly defined otherwise.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the present disclosure, unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may comprise direct contact between the first and second features, or may comprise contact between the first and second features not directly. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The first embodiment is as follows:

as shown in fig. 1 to 8, an application of a unidirectional self-locking mechanism to a motor is shown, the motor includes a motor housing and a motor shaft 10, the unidirectional self-locking mechanism includes a unidirectional bearing 101, a first friction member 102, a second friction member 103 and an elastic member 104, the unidirectional bearing 101 is sleeved outside the motor shaft 10, the first friction member 102 is circumferentially limited with an outer ring of the unidirectional bearing 101, the second friction member 103 is circumferentially limited with respect to the motor housing, the elastic member 104 axially presses the first friction member 102 and the second friction member 103, when the motor shaft 10 rotates forwards, the unidirectional bearing 101 freely rotates, the outer ring of the unidirectional bearing 101 does not rotate, when the motor shaft 10 rotates backwards, the unidirectional bearing 101 is locked, the motor shaft 10, the outer ring of the unidirectional bearing 101 and the first friction member 102 rotate synchronously, the first friction member 102 and the second friction member 103 frictionally and self-lock, one side of the first friction member 102, which faces away from the second friction member 103, is provided with a plane retainer, the plane retainer 105 is limited relative to the motor shell, and a plurality of rolling elements 105a are contacted and connected with the first friction element 102 on one side of the plane retainer 105 and roll along with the rotation of the first friction element 102.

Adopt motor shaft 10 and one-way bearing 101 to drive the cooperation structure of first friction piece 102 and fixed friction piece in this embodiment, utilize the one-way pivoted characteristic of one-way bearing 101, namely free rotation in one direction, lock in another direction, consequently design into in this embodiment when motor shaft 10 corotation, one-way bearing 101 free rotation, motor shaft free rotation, one-way bearing 101 outer lane, first friction piece 102 and second friction piece 103 homogeneous phase are fixed motionless, because one-way bearing 101 free rotation, make one-way self-locking mechanism can not produce any influence to motor normal rotation, avoid producing extra friction and increase heat and produce, transmission efficiency is high, reduce the energy consumption. When the motor shaft 10 has a tendency of reverse rotation, the one-way bearing 101 is locked and locked into a whole, and synchronously rotates with the motor shaft 10, and drives the first friction piece 102 to rotate, the first friction piece 102 and the second friction piece 103 generate relative motion, and are tightly contacted under the axial extrusion of the elastic piece 104 to generate friction force, according to the reaction, the friction force generates resistance to the rotation of the motor shaft 10, the motor shaft 10 is prevented from continuously rotating, and the self-locking is completed, the larger the axial elastic force generated by the elastic piece 104 is, the better the self-locking effect is, the matching precision requirement of the self-locking structure on each part is lower, the processing difficulty is reduced, the self-locking force generated by the one-way self-locking mechanism is excellent, is rigid self-locking compared with the flexible self-locking generated by a torsion spring structure, is larger, the stability after self-locking is better, but is relatively flexible compared with the rigid self, reduce the wearing and tearing between the part, the noise reduction prolongs motor life. And the one-way self-locking mechanism of this embodiment is provided with the plane retainer 105 fixed relative to the housing, when the motor shaft 10 rotates reversely to drive the first friction member 102 to rotate, the first friction member 102 contacts with the rolling members 105a and drives the rolling members 105a to roll in situ, which is equivalent to the first friction member 102 rotating on a plurality of rolling members 105a, and through the rolling of the rolling members 105a, the extrusion force between the first friction member 102 and the second friction member 103 is distributed more uniformly, so that the friction stress is uniform and balanced, the self-locking is more stable and firm, the local wear of the friction members is reduced, and the service life of the one-way self-locking mechanism is further prolonged.

The structure of the one-way bearing 101 in this embodiment may include an inner ring, an outer ring, and a rolling seat, wherein a plurality of rollers, needles, or balls are disposed in the rolling seat, and the shape of the rolling seat enables the rollers, needles, or balls to roll only in one direction, while the other direction generates a large resistance, at this time, the inner ring is sleeved outside the motor shaft 10, is circumferentially positioned with the motor shaft 10, and rotates synchronously with the motor shaft 10.

The structure of the one-way bearing 101 in this embodiment may not include an inner ring, and at this time, the rolling seat is directly sleeved outside the motor shaft 10, and when the motor shaft 10 rotates, the rolling shaft, the needle roller, or the ball is directly driven to roll in a certain direction in the rolling seat.

In order to simplify the structure and reduce the number of parts, as shown in fig. 6 and 7, in the present embodiment, the first friction member 102 and the outer ring of the one-way bearing 101 are fixed relatively in such a manner that the first friction member 102 is provided with a positioning protrusion 102a, and the outer ring of the one-way bearing 101 is provided with a positioning groove 101a engaged with the positioning protrusion 102 a.

The rolling elements 105a in this embodiment are rolling balls, needles or rollers.

As shown in fig. 2, the motor housing includes a housing body 11, a tail seat 12 and a cover 13, the tail seat 12 is disposed at the tail end of the housing body 11, the cover 13 covers the one-way self-locking mechanism, the cover 13 is detachably connected to the housing body 11, in order to facilitate the elastic member 104 to better press the rolling members 105a, so that the first friction member 102 and the second friction member 103 are in closer contact, as shown in fig. 2, 3 and 4, the other side of the planar holder 105 is provided with a pressing sheet 106, the pressing sheet 106 is in contact connection with a plurality of rolling members 105a, as shown in fig. 2, the one-way self-locking mechanism is specifically arranged in a way that the motor shaft extends out of the tail seat 12, the second friction member 103, the first friction member 102, the planar holder 105 and the pressing sheet 106 are sequentially distributed from the tail seat 12 to the axial direction of the motor shaft, the elastic member 104 and the pressing sheet 106 abut against each other end of the elastic member 104 is fixed in the self-locking mechanism, in order to ensure the And the tailstock 12 is internally provided with a limiting part for resisting the second friction piece 103, so that one end of the one-way self-locking mechanism is fixed, and the other end of the one-way self-locking mechanism is extruded, thereby ensuring that all the parts are in close contact with each other and increasing the self-locking force and the stability after self-locking. The elastic element 104 in this embodiment is preferably a helical compression spring, and in order to facilitate circumferential fixation of the elastic element 104, as shown in fig. 5, the cover 13 includes an outer ring 131, an inner ring 132 is disposed in the outer ring 131, a channel 133 is formed between the outer ring 131 and the inner ring 132, one end of the helical compression spring is accommodated in the channel 133 and sleeved on an outer wall of the inner ring 132, one end of the helical compression spring is fixed on the inner ring 132, and the other end of the helical compression spring is free to be axially compressed.

It is understood that the sequence of the components of the one-way self-locking mechanism may be the reverse of the above, that is, the pressing sheet 106, the plane retainer 105, the first friction member 102 and the second friction member 103 are distributed in sequence from the tailstock 12 to the outside along the axial direction of the motor shaft, and the elastic member 104 abuts against the second friction member 103.

Example two:

the difference between the present embodiment and the first embodiment is that the one-way self-locking mechanism includes at least two first friction members 102, the two first friction members 102 are respectively located at two sides of the plane retainer 105, a matching second friction member 103 is disposed at one side of each first friction member 102 opposite to the plane retainer 105, and the elastic member 104 abuts against the second friction member 103.

By adopting the structure, the one-way self-locking mechanism comprises the friction self-locking assembly consisting of the two sets of the first friction pieces 102 and the second friction pieces 103, so that the self-locking effect is better, and the one-way self-locking mechanism is more stable and firm.

Of course, in order to make the pressing force of the elastic member 104 on other components smoother and to facilitate the uniform distribution of the pressing force, a pressing piece 106 may be additionally disposed between the elastic member 104 and the second friction member 103, and at this time, the elastic member 104 abuts against the pressing piece 106.

Example three:

as shown in fig. 9 and 10, the difference between the present embodiment and the first and second embodiments is that the elastic member 104 is a helical compression spring or a spring plate, the cover 13 includes a back cover 134, the elastic member 104 is close to the back cover 134, and an elastic force adjusting assembly for adjusting the elastic force of the helical compression spring is further disposed on the motor, the elastic force adjusting assembly in the present embodiment includes an adjusting plate 108 and an adjusting screw 107, the adjusting plate 108 is disposed between the back cover 134 and the helical compression spring, a through hole 135 for passing a screw is disposed on the back cover 134, one end of the adjusting screw 107 passes through the back cover 134 and is connected with the adjusting plate 108, and the adjusting screw 107 can extend and retract toward the adjusting plate 108 relative to the back cover 134.

By adopting the elastic force adjusting assembly, according to the actual self-locking requirement, the position of the adjusting sheet 108 can be moved by screwing the screw on the rear cover 134, and the deformation and the elastic force of the elastic member 104 can be changed by the adjusting sheet 108, so that the extrusion force between the first friction member 102 and the second friction member 103 can be adjusted, and the friction self-locking force can be controlled finally. The one-way self-locking mechanism in the embodiment can be used for carrying out stepless adjustment on self-locking force, and has the advantages of strong universality and wide application range.

Example four:

a linear actuator comprises an inner tube, an outer tube, a rotary screw rod and a motor, wherein the motor drives the rotary screw rod to rotate, the rotary screw rod drives a transmission nut to axially move when rotating, the transmission nut moves to drive the inner tube and the outer tube to relatively stretch, and the motor is provided with a motor one-way self-locking mechanism in any embodiment.

The above description is only for the embodiments of the present invention, but the scope of the present invention is not limited thereto, and those skilled in the art should understand that the present invention includes but is not limited to the description in the above embodiments and the accompanying drawings. Any modification which does not depart from the functional and structural principles of the invention is intended to be included within the scope of the claims.

Claims (10)

1. An one-way self-locking mechanism of a motor comprises a motor shell and a motor shaft and is characterized by comprising a one-way bearing, a first friction piece, a second friction piece and an elastic piece, wherein the one-way bearing is sleeved outside the motor shaft, the first friction piece is circumferentially limited with an outer ring of the one-way bearing, the second friction piece is circumferentially limited relative to the motor shell, the elastic piece axially extrudes the first friction piece and the second friction piece, the one-way bearing freely rotates when the motor shaft rotates forwards, the outer ring of the one-way bearing does not rotate, the one-way bearing is locked when the motor shaft rotates backwards, the motor shaft, the outer ring of the one-way bearing and the first friction piece synchronously rotate, the first friction piece and the second friction piece are self-locked by friction, one side of the first friction piece, which faces away from the second friction piece, is provided with a plane retainer with a plurality of rolling pieces, the plane retainer is limited relative to the motor shell, and the rolling pieces are in contact connection with the first friction piece on one side of the plane retainer and roll along with the rotation of the first friction piece.

2. The unidirectional motor self-locking mechanism of claim 1, wherein a pressing plate is arranged on the other side of the planar retainer, and the pressing plate is in contact connection with a plurality of rolling members.

3. The unidirectional motor self-locking mechanism of claim 2, wherein the motor housing comprises a housing body and a tailstock, the motor shaft extends out of the tailstock, the second friction member, the first friction member, the planar retainer and the pressing plate are sequentially distributed from the tailstock to the outside along the axial direction of the motor shaft, and the elastic member abuts against the pressing plate; or the motor shell comprises a shell body and a tailstock, the motor shaft extends out of the tailstock, the pressing sheet, the plane retainer, the first friction piece and the second friction piece are sequentially distributed from the tailstock to the outside along the axial direction of the motor shaft, and the elastic piece is abutted to the second friction piece.

4. The unidirectional motor self-locking mechanism of claim 1, comprising at least two first friction members respectively located on both sides of the plane retainer.

5. The unidirectional motor self-locking mechanism of claim 4, wherein a second friction member is arranged on one side of each first friction member opposite to the plane retainer, and the elastic member is abutted against the second friction member.

6. The unidirectional motor self-locking mechanism of claim 1, wherein the elastic member is a helical compression spring, the motor housing comprises a cover cap, the cover cap is outside the unidirectional self-locking mechanism, the cover cap comprises an outer ring, an inner ring is arranged in the outer ring, a channel is formed between the outer ring and the inner ring, and one end of the helical compression spring is accommodated in the channel and sleeved on the outer wall of the inner ring.

7. The unidirectional motor self-locking mechanism of claim 1, wherein the elastic member is a helical compression spring or a spring plate, the motor housing comprises a housing body and a cover cap which are detachably connected, the cover cap comprises a rear cover, the elastic member is close to the rear cover, and the motor is further provided with an elastic force adjusting assembly for adjusting the elastic force of the helical compression spring.

8. The unidirectional motor self-locking mechanism of claim 7, wherein the elastic force adjusting assembly comprises an adjusting sheet and an adjusting screw, the adjusting sheet is arranged between the rear cover and the helical compression spring, one end of the adjusting screw penetrates through the rear cover to be connected with the adjusting sheet, and the adjusting screw can extend and retract towards the adjusting sheet relative to the rear cover.

9. The unidirectional motor self-locking mechanism of claim 1, wherein the first friction member is provided with a positioning protrusion, and the outer ring of the unidirectional bearing is provided with a positioning groove matched with the positioning protrusion.

10. A linear actuator comprises an inner tube, an outer tube, a rotary screw rod and a motor, wherein the motor drives the rotary screw rod to rotate, the rotary screw rod drives a transmission nut to axially move when rotating, and the transmission nut moves to drive the inner tube and the outer tube to relatively extend and retract, and the motor is provided with a motor one-way self-locking mechanism as claimed in any one of claims 1 to 9.

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