CN211733713U

CN211733713U - Multi-stage telescopic device

Info

Publication number: CN211733713U
Application number: CN202020287834.6U
Authority: CN
Inventors: 陈警; 付卓; 张津瑞; 赵思宇; 杨泽宇; 孙墨林
Original assignee: Changsha University
Current assignee: Changsha University
Priority date: 2020-03-10
Filing date: 2020-03-10
Publication date: 2020-10-23
Anticipated expiration: 2030-03-10

Abstract

The utility model provides a multistage telescoping device, include: the base comprises a sleeve, a screw rod arranged in the sleeve and a driving mechanism for driving the screw rod to rotate; the primary telescopic mechanism comprises a primary telescopic rod, a primary driving wheel and a primary thimble, the primary telescopic rod is slidably sleeved in the sleeve, the primary driving wheel is sleeved outside the screw and meshed with the screw, and the primary thimble is connected with the primary telescopic rod and used for locking or releasing the primary driving wheel; the second-stage telescopic mechanism comprises a second-stage telescopic rod, a second-stage driving wheel and a second-stage ejector pin, the second-stage telescopic rod is slidably sleeved in the first-stage telescopic rod, the second-stage driving wheel is sleeved outside the screw rod and meshed with the screw rod, and the second-stage ejector pin is connected with the second-stage telescopic rod and used for locking or releasing the second-stage driving wheel. The utility model discloses need not extra design hydro-cylinder and oil circuit return circuit, the greasy dirt pollution can not appear, and need not to design the control method of bi-motor separately and need not to increase circuit or singlechip etc. has the advantage of simple structure and easy preparation.

Description

Multi-stage telescopic device

Technical Field

The utility model relates to an engineering machine tool technical field, in particular to multistage telescoping device.

Background

The telescopic device is widely applied to engineering, and can be used in a great number of engineering machines. However, in practical applications, a common telescopic device usually can only extend one section, the ratio of the extension length to the length in the contracted state, i.e. the telescopic ratio is less than 2, and the extension amount is greatly limited under the condition of limited original length, so that the expected transmission or working effect cannot be realized. If a two-stage telescopic device is adopted, the telescopic proportion can be enlarged to 2.5 or 2.8, and the extension length is effectively increased under the condition of certain original length.

However, the existing two-stage telescopic device is usually realized by adopting a hydraulic or dual-motor driving mode, if the hydraulic driving mode is adopted, an oil cylinder needs to be additionally designed, an oil circuit needs to be designed, meanwhile, the sealing problem and the occupied space of the telescopic device need to be considered, the structure is complex, the manufacture is inconvenient, the work burden of a designer is increased, and under the condition that the acting object is a carton type object, if the sealing performance of the telescopic device is poor, hydraulic oil leakage easily causes the object to be polluted by oil stains; if a dual-motor driving mode is adopted, a dual-motor control method needs to be additionally designed, a circuit or a single chip microcomputer needs to be added, and the problems of complex structure, inconvenience in manufacturing and heavy design burden exist.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a multistage telescoping device aims at solving the complicated and inconvenient problem of preparation of telescoping device structure among the prior art.

In order to achieve the above object, the utility model provides a multistage telescoping device, multistage telescoping device includes:

the base comprises a sleeve, a screw rod rotationally mounted in the sleeve and a driving mechanism for driving the screw rod to rotate;

the primary telescopic mechanism comprises a primary telescopic rod, a primary driving wheel and a primary thimble, the primary telescopic rod is slidably sleeved in the sleeve, the primary telescopic rod axially limits the primary driving wheel, the primary driving wheel is sleeved outside the screw and meshed with the screw, the primary thimble is connected with the primary telescopic rod, and the primary thimble is used for locking or releasing the primary driving wheel so as to match the primary driving wheel to drive the primary telescopic rod to extend out of a first initial position to a first limit position relative to the sleeve or retract to the first initial position from the first limit position;

second grade telescopic machanism, second grade telescopic machanism includes second grade telescopic link, second grade drive wheel and second grade thimble, second grade telescopic link slip cap is located in the one-level telescopic link, the second grade telescopic link is right the second grade drive wheel carries out the axial spacing, second grade drive wheel cover is located outside the screw rod and with the screw rod meshing, the second grade thimble with the second grade telescopic link is connected, the second grade thimble is used for locking or release the second grade drive wheel, with the cooperation the drive of second grade drive wheel the second grade telescopic link is relative the one-level telescopic link stretches out to second extreme position or follows from the second extreme position retract to the second extreme position the second initial position.

Preferably, the secondary driving wheel is provided with a secondary jack, the secondary thimble comprises a secondary movable rod, a secondary inserted rod and a secondary driving piece, the secondary inserted rod and the secondary driving piece are respectively connected with the secondary movable rod, and the secondary movable rod is in sliding fit with the secondary telescopic rod; when the secondary telescopic rod is located at the second initial position, the secondary driving piece can drive the secondary movable rod to drive the secondary insertion rod to be inserted into the secondary insertion hole and lock the secondary driving wheel, or when the secondary telescopic rod extends to the second limit position, the secondary insertion rod is separated from the secondary insertion hole and releases the secondary driving wheel; when the secondary telescopic rod is located at the second limit position, the secondary driving wheel is disengaged from the screw rod.

Preferably, the secondary telescopic rod comprises a secondary mounting seat and a secondary rod body connected with the secondary mounting seat, the secondary driving wheel is mounted in the secondary mounting seat, and the secondary mounting seat axially limits the secondary driving wheel; the second grade movable rod slides and wears to locate the second grade mount pad, the second grade inserted bar is connected the second grade movable rod is kept away from the one end of second grade pole body, the second grade driving piece is the second spring, the first end of second spring with the second grade mount pad is connected, the second end of second spring pass through the second connecting block with keep away from on the second grade movable rod the one end of second grade inserted bar is connected.

Preferably, a second step surface is formed at the joint of the secondary rod body and the secondary mounting seat, a second connecting surface is formed in the secondary mounting seat, the first end of the second spring is connected with the second connecting surface, and a second abutting surface is arranged on the primary telescopic rod close to the free end; when the secondary expansion link is located at the second initial position, the second connecting block extends out of the second step surface and enables the secondary insertion rod to be inserted into the secondary insertion hole; when the second-stage telescopic rod extends to the second limit position, the second abutting surface abuts against the second step surface and pushes the second connecting block to enable the second-stage movable rod to drive the second-stage inserted rod to be separated from the second-stage jack.

Preferably, the primary driving wheel is provided with a primary jack, the primary thimble comprises a primary movable rod, a primary inserted rod and a primary driving piece, the primary inserted rod and the primary driving piece are respectively connected with the primary movable rod, and the primary movable rod is in sliding fit with the primary telescopic rod; when the primary telescopic rod is located at the first initial position, the primary inserted link is separated from the primary jack and releases the primary driving wheel, or when the secondary telescopic rod extends to the second limit position, the primary driving piece can drive the primary movable rod to drive the primary inserted link to be inserted into the primary jack and lock the primary driving wheel; when the primary telescopic rod is located at the first limit position, the primary driving wheel and the screw rod are kept in a meshed state.

Preferably, the primary telescopic rod comprises a primary mounting seat and a primary rod body connected with the primary mounting seat, the primary driving wheel is mounted in the primary mounting seat, and the primary mounting seat axially limits the primary driving wheel; the secondary telescopic rod is sleeved in the primary rod body in a sliding manner; the one-level movable rod slides and wears to locate the one-level mount pad, the one-level inserted bar is connected the one-level movable rod is close to the one end of one-level pole body, the one-level driving piece is first spring, the first end of first spring with the one-level mount pad is connected, the second end of first spring through first connecting block with keep away from on the one-level movable rod the one end of one-level inserted bar is connected.

Preferably, a first step surface is formed at the joint of the primary rod body and the primary mounting seat, an action surface is formed on one side of the primary mounting seat, which is far away from the first step surface, and the first connecting block extends out of the action surface; a first connecting surface is formed in the primary mounting seat, a first end of the first spring is connected with the first connecting surface, and a first abutting surface is arranged on one side, facing the primary mounting seat, of the inner surface of the sleeve; when the primary telescopic rod is located at the first initial position, the first abutting surface abuts against the action surface and pushes the first connecting block to drive the primary inserted link to be separated from the primary jack;

the multistage telescoping device still includes link gear, the second grade telescopic link stretch out to when the second extreme position, through the link gear pulling is in the first initial position the one-level telescopic link begins to stretch out, the one-level telescopic link drives the one-level drive wheel removes so that the one-level inserted bar inserts the one-level jack.

Preferably, the linkage mechanism includes:

the pull rod is connected with the inner wall of the primary rod body in a sliding mode, and a first pull hook and a second pull hook are formed at two ends of the pull rod respectively;

the first drag hook is arranged at the first end of the hinged rod, the primary movable rod is abutted against the second end of the hinged rod, and the position, between the first end and the second end, on the hinged rod is hinged with the primary rod body through a hinged shaft;

when the second-stage telescopic rod extends to the second limit position, the second drag hook is hooked on the second-stage telescopic rod and drives the pull rod to move along the extending direction of the second-stage telescopic rod through the second-stage telescopic rod, so that the second end of the hinged rod rotates around the hinged shaft and simultaneously pulls the first-stage telescopic rod at the first initial position to extend, and the first-stage inserted rod is inserted into the first-stage jack;

when the first-stage telescopic rod retracts to the first initial position, the first abutting surface pushes the first connecting block, so that the first-stage movable rod pushes the second end of the hinged rod to rotate reversely around the hinged shaft, the second-stage telescopic rod at the second limit position is pulled through the pull rod to move in the retracting direction of the first-stage telescopic rod, and the second-stage driving wheel is meshed with the screw rod again.

Preferably, the multi-stage telescopic device further comprises a locking mechanism, the locking mechanism comprises an insertion block, a compression spring and a sliding block, one end of the insertion block, which is far away from the second-stage telescopic rod, is connected with the first-stage telescopic rod through the compression spring, the outer wall of the second-stage telescopic rod is provided with a locking jack matched with the insertion block, a first inclined plane is formed on one side, facing the sliding block, of the insertion block, the sliding block is in sliding fit with the first-stage telescopic rod, one end, which is far away from the second-stage telescopic rod, of the sliding block extends out of the outer wall of the first-stage telescopic rod, and a second inclined plane in sliding fit with the first inclined plane is formed on one side;

when the secondary telescopic rod extends to the second limit position, the compression spring drives the insertion block to be inserted into the locking insertion hole, so that the secondary telescopic rod and the primary telescopic rod are locked;

when the first-stage telescopic rod retracts to the first initial position, the sleeve pushes the sliding block to slide towards the extending direction of the first-stage telescopic rod, so that the inserting block is separated from the locking jack through the sliding fit of the second inclined surface and the first inclined surface, and the second-stage telescopic rod and the first-stage telescopic rod are unlocked.

Preferably, the driving mechanism comprises a driving motor and two bevel gears which are meshed with each other, wherein one bevel gear is fixedly sleeved on the screw rod, and the other bevel gear is connected with the driving motor.

The multi-stage expansion device of the utility model realizes the two-time continuous and orderly expansion of the multi-stage expansion device by adopting the screw transmission mode of the screw rod meshed with the first-stage driving wheel and the second-stage driving wheel, compared with the mode of adopting hydraulic drive or double-motor drive in the prior art, the multi-stage expansion device of the utility model does not need to additionally design an oil cylinder and an oil circuit loop, does not need to consider the sealing problem, does not have the oil pollution problem, good reliability, convenient maintenance, no need of additionally designing a control method of double motors, no need of adding circuits or singlechips and the like, simple structure and easy manufacture, reduces the design burden, moreover, the extension process of the multi-stage extension device of the utility model is carried out in the sleeve, the occupied volume is small, the weight of the multi-stage telescopic device is reduced, the cost is saved, and the advantages are more obvious under the condition that the number of telescopic stages is more. Additionally, the utility model discloses a screw rod and device adopt screw rod and one-level drive wheel and the spiral transmission mode of second grade drive wheel meshing, and it belongs to the cooperation of relatively accurate mechanical transmission, and the flexible length of accurate control one-level telescopic link and second grade telescopic link is come to the number of turns of rotation of accessible screw rod, and then can accurate control whole multistage telescoping device's flexible stroke, excellent in use effect.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the structures shown in the drawings without creative efforts.

Fig. 1 is a schematic perspective view of the multi-stage telescopic device of the present invention before extending out;

fig. 2 is a schematic perspective view of the structure of the non-extended front portion of the multi-stage telescopic device of the present invention at a viewing angle;

fig. 3 is a schematic perspective view of the structure of the non-extended front portion of the multi-stage telescopic device of the present invention at another viewing angle;

fig. 4 is a schematic perspective view of the multi-stage telescopic device of the present invention when the two-stage telescopic rod extends to the second limit position;

fig. 5 is a schematic perspective view of a part of the structure of the multi-stage telescopic device at a viewing angle when the two-stage telescopic rod extends to the second limit position;

fig. 6 is a schematic perspective view of a portion of the multi-stage telescopic device at another viewing angle when the two-stage telescopic rod extends to the second limit position;

fig. 7 is a schematic perspective view of the multi-stage telescopic device of the present invention when the one-stage telescopic rod extends to the first limit position;

fig. 8 is a schematic perspective view of a part of the structure of the multi-stage telescopic device at a viewing angle when the one-stage telescopic rod extends to the first limit position;

fig. 9 is a schematic perspective view of a part of the structure of the multi-stage telescopic device at another viewing angle when the one-stage telescopic rod extends to the first limit position;

fig. 10 is a schematic cross-sectional view of the multi-stage retractor device of the present invention before being extended;

fig. 11 is a schematic partial cross-sectional view of the multi-stage telescopic device of the present invention when the first-stage telescopic rod and the second-stage telescopic rod are locked together;

fig. 12 is an exploded view of the locking mechanism of the multi-stage telescopic device of the present invention.

The reference numbers illustrate:

10. a primary telescoping mechanism; 11. a first-stage telescopic rod; 111. a primary mount; 1111. acting surface; 1112. a first connection face; 112. a primary lever body; 1121. a friction ring; 1122. a slide hole; 12. a primary driving wheel; 113. a second abutting surface; 114. a first step surface; 121. a first-stage jack; 13. a first-stage thimble; 131. a primary movable rod; 132. a first-stage inserted link; 133. a primary drive member; 134. a first connection block; 20. a secondary telescoping mechanism; 21. a secondary telescopic rod; 211. a secondary mounting base; 2111. a second connection face; 212. a secondary lever body; 2121. locking the jack; 213. a second step surface; 22. a secondary driving wheel; 221. a secondary jack; 23. a second-stage thimble; 231. a secondary movable rod; 232. a second-stage inserted link; 233. a secondary drive member; 234. a second connecting block; 30. a base; 31. a sleeve; 311. a first abutting surface; 32. a screw; 33. a drive mechanism; 331. a bevel gear; 40. a linkage mechanism; 41. a pull rod; 411. a first draw hook; 412. a second draw hook; 42. a hinged lever; 50. a locking mechanism; 51. inserting a block; 511. a first inclined surface; 52. a compression spring; 53. a slider; 531. a second inclined surface.

The objects, features and advantages of the present invention will be further described with reference to the accompanying drawings.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that all the directional indicators (such as upper, lower, left, right, front and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the motion situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

In addition, the descriptions related to "first", "second", etc. in the present invention are for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicit ly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions in the embodiments may be combined with each other, but it must be based on the realization of those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should not be considered to exist, and is not within the protection scope of the present invention.

The present invention is described in the directions of "front" and "rear" with reference to the direction shown in fig. 10, and is only used to explain the relative positional relationship between the components in the posture shown in fig. 10, and if the specific posture is changed, the directional indication is also changed accordingly.

As shown in fig. 1 to 10, the present invention provides a multi-stage telescopic device, which comprises a base 30, a first stage telescopic mechanism 10 and a second stage telescopic mechanism 20, wherein the base 30 comprises a sleeve 31, a screw rod 32 and a driving mechanism 33, the screw rod 32 is rotatably installed in the sleeve 31, and the driving mechanism 33 is used for driving the screw rod 32 to rotate; one-level telescopic machanism 10 includes one-level telescopic link 11, one-level drive wheel 12 and one-

level thimble

13, and 11 sliding sleeve of one-level telescopic link are located in sleeve 31, and one-level telescopic link 11 carries out the axial spacing to one-level drive wheel 12 to prevent 12 axial drunkenness of one-level drive wheel. The primary driving wheel 12 is sleeved outside the screw rod 32 and meshed with the screw rod 32, the primary ejector pin 13 is connected with the primary telescopic rod 11, and the primary ejector pin 13 is used for locking or releasing the primary driving wheel 12 so as to cooperate with the primary driving wheel 12 to drive the primary telescopic rod 11 to extend out of a first initial position to a first limit position or retract to the first initial position from the first limit position relative to the sleeve 31; the second-stage telescopic mechanism 20 comprises a second-stage telescopic rod 21, a second-stage driving wheel 22 and a second-stage ejector pin 23, the second-stage telescopic rod 21 is slidably sleeved in the first-stage telescopic rod 11, and the second-stage telescopic rod 21 axially limits the second-stage driving wheel 22 to prevent the second-stage driving wheel 22 from axially moving. The secondary driving wheel 22 is sleeved outside the screw rod 32 and meshed with the screw rod 32, the secondary ejector pin 23 is connected with the secondary telescopic rod 21, and the secondary ejector pin 23 is used for locking or releasing the secondary driving wheel 22 so as to cooperate with the secondary driving wheel 22 to drive the secondary telescopic rod 21 to extend out of the second initial position to the second limit position or retract from the second limit position to the second initial position relative to the primary telescopic rod 11.

It should be noted that, the first initial position of this embodiment refers to a position where the free end of the one-stage telescopic rod 11 does not slide relative to the sleeve 31, and the free end thereof is close to the free end of the sleeve 31, and the first extreme position is an extreme position where the free end of the one-stage telescopic rod 11 slides and extends away from the sleeve 31; the second initial position is a position where the free end of the secondary telescopic rod 21 does not slide relative to the primary telescopic rod 11 and is close to the free end of the primary telescopic rod 11, and the second limit position is a limit position where the free end of the secondary telescopic rod 21 slides and extends away from the primary telescopic rod 11. As shown in fig. 10, the extending direction of the first telescopic rod 11 and the second telescopic rod 21 is a forward direction, and the retracting direction of the first telescopic rod 11 and the second telescopic rod 21 is a backward direction.

When the multi-stage telescopic device of the embodiment needs to be extended, the driving mechanism 33 drives the screw rod 32 to rotate, the first-stage thimble 13 releases the first-stage driving wheel 12, the first-stage driving wheel 12 rotates along with the rotation of the screw rod 32 and is temporarily in an idle running state, and the first-stage telescopic rod 11 does not extend or retract relative to the sleeve 31 and is kept at a first initial position; and the second-stage thimble 23 locks the second-stage driving wheel 22, and the second-stage driving wheel 22 moves forward along with the rotation of the screw rod 32, so as to drive the second-stage telescopic rod 21 to slide forward relative to the first-stage telescopic rod 11 and extend out, so that the second-stage telescopic rod 21 extends out from the second initial position to the second limit position, and the first extension of the multi-stage telescopic device is realized, at this time, the second-stage thimble 23 releases the second-stage driving wheel 22, and the second-stage driving wheel 22 is in a temporary. Then, the first-stage thimble 13 locks the first-stage driving wheel 12, and the first-stage driving wheel 12 moves forward along with the rotation of the screw 32, so as to drive the first-stage telescopic rod 11 to slide forward and extend relative to the sleeve 31, so that the first-stage telescopic rod 11 extends from the first initial position to the first limit position, and the second extension of the multi-stage telescopic device is realized. Understandably, because the second-stage telescopic rod 21 is sleeved on the first-stage telescopic rod 11, in the process of extending the first-stage telescopic rod 11, the second-stage telescopic rod 21 can be driven to continuously move forwards, and the two continuous and orderly extending processes of the multistage telescopic device are ensured.

When the multistage telescoping device of this embodiment needs to retract, actuating mechanism 33 drive screw rod 32 antiport, one-level drive wheel 12 is locked to one-level thimble 13, one-level drive wheel 12 moves backward along with the antiport of screw rod 32, and then drive the retraction of sliding backward of one-level telescopic link 11 relative sleeve 31, make one-level telescopic link 11 retract to first initial position from first extreme position, realize the first time retraction of multistage telescoping device, at this moment, one-level thimble 13 releases one-level drive wheel 12, one-level drive wheel 12 gets back to idle running state again. Then, the secondary thimble 23 locks the secondary driving wheel 22, the secondary driving wheel 22 moves backwards along with the reverse rotation of the screw rod 32, and further drives the secondary telescopic rod 21 to slide backwards and retract relative to the primary telescopic rod 11, so that the secondary telescopic rod 21 retracts from the second limit position to the second initial position, and the secondary retraction of the multi-stage telescopic device is realized. Understandably, because the second-stage telescopic rod 21 is sleeved on the first-stage telescopic rod 11, in the retraction process of the first-stage telescopic rod 11, the second-stage telescopic rod 21 can be driven to move backwards at the same time, and the two continuous and orderly retraction processes of the multistage telescopic device are ensured.

In the present embodiment, the multi-stage expansion device may be a two-stage expansion device, a three-stage expansion device, a four-stage expansion device, or the like, and the two-stage expansion device is taken as an example in the present embodiment. For example, in the three-stage telescopic device, a three-stage telescopic rod can be added on the basis of the two-stage telescopic device, the three-stage telescopic rod can be slidably sleeved in the two-stage telescopic rod 21, and the assembling mode between the three-stage telescopic rod and the two-stage telescopic rod 21 is similar to the assembling mode and the telescopic mode between the two-stage telescopic rod 21 and the one-stage telescopic rod 11, and the details are not repeated herein. For another example, the four-stage telescopic device may be added with a four-stage telescopic rod on the basis of the three-stage telescopic device, the four-stage telescopic rod is slidably sleeved in the three-stage telescopic rod, and the assembling manner between the four-stage telescopic rod and the three-stage telescopic rod is similar to the assembling and telescopic manner between the two-stage telescopic rod 21 and the one-stage telescopic rod 11 and between the three-stage telescopic rod and the two-stage telescopic rod 21, which is not described herein again.

Compared with the prior art which adopts a hydraulic drive or dual-motor drive mode, the multistage telescoping device of the embodiment does not need to additionally design an oil cylinder and an oil circuit loop, does not need to consider the sealing problem, and does not have the oil pollution problem, good reliability, convenient maintenance, no need of additionally designing a control method of double motors, no need of adding circuits or singlechips and the like, simple structure and easy manufacture, reduces the design burden, moreover, the extension and contraction processes of the multi-stage extension and contraction device of the embodiment are all carried out in the sleeve 31, the occupied volume is small, the weight of the multi-stage telescopic device is reduced, the cost is saved, and the advantages are more obvious under the condition that the number of telescopic stages is more. In addition, this embodiment adopts screw rod 32 and device to adopt screw rod 32 and the spiral transmission mode of one-level drive wheel 12 and the meshing of second grade drive wheel 22, and it belongs to the mechanical transmission cooperation of relative accurate, and the flexible length of one-level telescopic link 11 and second grade telescopic link 21 is accurately controlled to the number of turns of rotation of accessible screw rod 32, and then can accurately control whole multistage telescoping device's flexible stroke, excellent in use effect.

In this embodiment, the secondary driving wheel 22 is provided with a secondary jack 221, the secondary thimble 23 includes a secondary movable rod 231, a secondary insertion rod 232 and a secondary driving member 233, which are respectively connected with the secondary movable rod 231, and the secondary movable rod 231 is in sliding fit with the secondary telescopic rod 21; when the secondary expansion link 21 is at the second initial position, the secondary driving member 233 can drive the secondary movable rod 231 to drive the secondary insertion rod 232 to be inserted into the secondary insertion hole 221 and lock the secondary driving wheel 22, or when the secondary expansion link 21 extends to the second limit position, the secondary insertion rod 232 is separated from the secondary insertion hole 221 and releases the secondary driving wheel 22; when the secondary telescopic rod 21 is at the second limit position, the secondary driving wheel 22 is disengaged from the screw 32. It should be noted that the second initial position of the two-stage telescopic rod 21 refers to both the initial position before the two-stage telescopic rod 21 starts to extend and the position where the two-stage telescopic rod 21 is fully retracted.

The secondary driving wheel 22 of the present embodiment can use a ratchet wheel in the prior art, and can also use a nut or a nut-like wheel in the prior art which can be engaged with the screw 32, and the secondary driving wheel 22 of the present embodiment is illustrated as a ratchet wheel. The number of the secondary insertion holes 221 is multiple, and the multiple secondary insertion holes 221 are uniformly arranged along the circumferential direction of the secondary driving wheel 22 at intervals, so that the secondary insertion rod 232 can be conveniently inserted into any one secondary insertion hole 221 to lock the secondary driving wheel 22 in the rotating process of the secondary driving wheel 22. Specifically, when the secondary expansion link 21 is at the second initial position, the secondary driving member 233 drives the secondary movable rod 231 to drive the secondary insertion rod 232 to be inserted into any one of the secondary insertion holes 221, so as to lock the secondary driving wheel 22, until the secondary driving wheel 22 drives the secondary expansion link 21 to extend to the second initial position, the secondary driving member 233 drives the secondary movable rod 231 to drive the secondary insertion rod 232 to disengage from the secondary insertion hole 221, so as to release the secondary driving wheel 22, the secondary expansion link 21 stops extending, the secondary driving wheel 22 is in an idle running state, and the secondary driving wheel 22 is disengaged from the screw 32 at this time, so that the secondary expansion link 21 is not restrained by the screw 32 in the subsequent expansion process of the primary expansion link 11, and thus expands and contracts along with the expansion and contraction of.

As shown in fig. 1 to 10, in this embodiment, the secondary telescopic rod 21 includes a secondary mounting seat 211 and a secondary rod body 212, the secondary rod body 212 is connected to the secondary mounting seat 211, the secondary driving wheel 22 is mounted in the secondary mounting seat 211, and the secondary mounting seat 211 axially limits the secondary driving wheel 22 to prevent the secondary driving wheel 22 from axially moving; the second grade movable rod 231 slides and wears to locate second grade mount pad 211, and second grade inserted bar 232 is connected in the one end that second grade movable rod 231 kept away from second grade pole body 212, and second grade driving piece 233 is the second spring, and the first end and the second grade mount pad 211 of second spring are connected, and the second end of second spring is passed through second connecting block 234 and is connected with the one end of keeping away from second grade inserted bar 232 on second grade movable rod 231.

Specifically, a second step surface 213 is formed at the joint of the secondary rod body 212 and the secondary mounting seat 211, a second connection surface 2111 is formed in the secondary mounting seat 211, a first end of the second spring is connected with the second connection surface 2111, and a second abutting surface 113 is arranged on the primary telescopic rod 11 near the free end; when the secondary expansion link 21 is in the second initial position, the second connecting block 234 extends out of the second step surface 213 and the secondary insertion link 232 is inserted into the secondary insertion hole 221; when the secondary expansion link 21 extends to the second limit position, the second abutting surface 113 abuts against the second step surface 213 and pushes the second connecting block 234, so that the secondary movable rod 231 drives the secondary insertion rod 232 to disengage from the secondary insertion hole 221.

In this embodiment, the second-stage insertion rod 232 is connected to the rear end of the second-stage movable rod 231, and the front end of the second-stage movable rod 231 is connected to the second connection block 234. The second spring is a compression spring, the rear end of the compression spring is connected to the second connecting block 234, and the front end of the compression spring is connected to the second connecting surface 2111. When the secondary expansion link 21 is at the second initial position, due to the elastic force of the compression spring, the second connecting block 234 connected with the secondary movable rod 231 extends forwards to the second step surface 213, and the secondary inserted rod 232 is inserted into the secondary insertion hole 221, so as to lock the secondary driving wheel 22 until the secondary driving wheel 22 drives the secondary expansion link 21 to extend to the second limit position, when the secondary expansion link 21 extends to the second limit position, the second abutting surface 113 abuts against the second step surface 213 on the front side thereof, the second abutting surface 113 pushes the second connecting block 234 to move backwards, and further the secondary movable rod 231 is driven to slide backwards relative to the secondary mounting seat 211, so that the secondary inserted rod 232 is separated from the secondary insertion hole 221, so as to release the secondary driving wheel 22, and the secondary expansion link 21 stops extending. The structural design of each part of the second-stage telescopic mechanism 20 of the embodiment is reasonable and ingenious, and the first extension process of the multi-stage telescopic device is convenient to realize. Alternatively, in other embodiments, the secondary movable rod 231 may be a relatively small electric telescopic rod to drive the secondary insertion rod 232 to move to lock or release the secondary driving wheel 22.

In this embodiment, the primary driving wheel 12 is provided with a primary jack 121, the primary thimble 13 includes a primary movable rod 131, a primary inserted rod 132 and a primary driving member 133 respectively connected to the primary movable rod 131, and the primary movable rod 131 is in sliding fit with the primary telescopic rod 11; when the primary telescopic rod 11 is at the first initial position, the primary inserted link 132 is disengaged from the primary insertion hole 121 and releases the primary driving wheel 12, or when the secondary telescopic rod 21 extends to the second limit position, the primary driving member 133 can drive the primary movable rod 131 to drive the primary inserted link 132 to be inserted into the primary insertion hole 121 and lock the primary driving wheel 12; when the primary telescopic rod 11 is at the first limit position, the primary driving wheel 12 and the screw 32 are kept in a meshed state. It should be noted that the first initial position of the first telescopic rod 11 refers to both the initial position before the first telescopic rod 11 starts to extend and the position where the first telescopic rod 11 is fully retracted.

The primary driving wheel 12 of the present embodiment may be a ratchet wheel as in the prior art, or a nut-like wheel as in the prior art which can engage with the screw 32, and the primary driving wheel 12 of the present embodiment is illustrated as a ratchet wheel. The number of the first-stage insertion holes 121 is multiple, and the multiple first-stage insertion holes 121 are uniformly arranged along the circumferential direction of the first-stage driving wheel 12 at intervals, so that the first-stage insertion rods 132 can be inserted into any one of the first-stage insertion holes 121 to lock the first-stage driving wheel 12 in the rotating process of the first-stage driving wheel 12. Specifically, when one-level telescopic link 11 is in first initial position, one-level driving piece 133 drives one-level movable rod 131 and drives one-level inserted bar 132 and break away from one-level jack 121, thereby release one-level drive wheel 12, one-level drive wheel 12 is in temporary idle running state, one-level telescopic link 11 does not stretch out and draw back for sleeve 31, keep at first initial position, until second telescopic link 21 stretches out to the second extreme position when, one-level driving piece 133 drives one-level movable rod 131 and drives one-level inserted bar 132 and insert in arbitrary one-level jack 121, in order to lock one-level drive wheel 12, until one-level drive wheel 12 drive second telescopic link 21 stretches out to first extreme position, guarantee that one-level telescopic link 11 and second telescopic link 21 stretch out. When the first-stage telescopic rod 11 is at the first limit position, the first-stage driving wheel 12 and the screw 32 are kept in a meshed state, so that the normal extending process and the subsequent retracting process of the first-stage telescopic rod 11 are ensured.

As shown in fig. 1 to 10, in the present embodiment, the first-stage telescopic rod 11 includes a first-stage mounting seat 111 and a first-stage rod body 112, the first-stage rod body 112 is connected to the first-stage mounting seat 111, the first-stage driving wheel 12 is mounted in the first-stage mounting seat 111, and the first-stage mounting seat 111 axially limits the first-stage driving wheel 12 to prevent the first-stage driving wheel 12 from axially moving. In the secondary telescopic rod 21 slip cap located first grade pole body 112, one-level movable rod 131 slides and wears to locate one-level mount pad 111, one-level inserted bar 132 is connected in one-level movable rod 131 one end that is close to one-level pole body 112, one-level driving piece 133 is first spring, the first end and the one-level mount pad 111 of first spring are connected, the second end of first spring is connected through the one end of keeping away from one-level inserted bar 132 on first connecting block 134 and the one-level movable rod 131.

Specifically, a first step surface 114 is formed at the joint of the primary lever body 112 and the primary mounting seat 111, an action surface 1111 is formed on one side of the primary mounting seat 111, which is away from the first step surface 114, and the first connecting block 134 extends out of the action surface 1111; a first connection surface 1112 is formed in the primary mounting seat 111, a first end of the first spring is connected with the first connection surface 1112, and a first abutting surface 311 is arranged on one side, facing the primary mounting seat 111, of the inner surface of the sleeve 31; when the primary telescopic rod 11 is at the first initial position, the first abutting surface 311 abuts against the action surface 1111 and pushes the first connecting block 134 to drive the primary inserting rod 132 to disengage from the primary inserting hole 121; the multi-stage telescopic device of the embodiment further includes a linkage mechanism 40, when the two-stage telescopic rod 21 extends to the second limit position, the one-stage telescopic rod 11 at the first initial position is pulled by the linkage mechanism 40 to start to extend, and the one-stage telescopic rod 11 drives the one-stage driving wheel 12 to move so that the one-stage insertion rod 132 is inserted into the one-stage insertion hole 121.

In this embodiment, the first-stage insertion rod 132 is connected to the front end of the first-stage movable rod 131, and the rear end of the first-stage movable rod 131 is connected to the first connecting block 134. The first spring is a compression spring, the front end of the compression spring is connected to the first connection surface 1112, and the rear end of the compression spring is connected to the first connection block 134. When the first-stage telescopic rod 11 is at the first initial position, because the first abutting surface 311 abuts against the action surface 1111, the first connecting block 134 is pushed forward, the first connecting block 134 drives the first-stage insertion rod 132 to move forward, so as to drive the first-stage movable rod 131 and the first-stage insertion rod 132 to move forward and separate from the first-stage insertion hole 121, so as to release the first-stage driving wheel 12, the first-stage driving wheel 12 is in a temporary idle running state, until the second-stage telescopic rod 21 extends to the second limit position, that is, when the second-stage telescopic rod 21 extends completely, the second-stage telescopic rod 21 pulls the first-stage telescopic rod 11 at the first initial position to extend forward through the linkage mechanism 40, the first-stage telescopic rod 11 drives the first-stage driving wheel 12 to move forward in the process of moving forward of the first-stage telescopic rod 11, the action surface 1111 is separated from the first abutting surface 311, the first connecting block 134 extends out of the action surface 1111 again under the action of the first spring, and causes, so as to lock the primary driving wheel 12 until the primary driving wheel 12 drives the primary telescopic rod 11 to extend to the first limit position. The structural design of each part of the one-level telescopic mechanism 10 of the embodiment is reasonable and ingenious, and the second extension process of the multi-level telescopic device is convenient to realize. Alternatively, in other embodiments, the primary movable rod 131 may also be a relatively small electric telescopic rod to drive the primary insertion rod 132 to move to lock or release the primary driving wheel 12.

In a preferred embodiment, the linkage mechanism 40 includes a pull rod 41 and a hinge rod 42, wherein the pull rod 41 is slidably connected to the inner wall of the primary rod body 112, and a first hook 411 and a second hook 412 are respectively formed at two ends of the pull rod 41; the first drag hook 411 is hooked at the first end of the hinge rod 42, the first-stage movable rod 131 abuts against the second end of the hinge rod 42, and the position, between the first end and the second end, on the hinge rod 42 is hinged to the first-stage rod body 112 through a hinge shaft. When the secondary telescopic rod 21 extends to the second limit position, the second draw hook 412 is hooked on the secondary telescopic rod 21 and drives the pull rod 41 to move along the extending direction of the secondary telescopic rod 21 through the secondary telescopic rod 21, so that the second end of the hinge rod 42 rotates around the hinge shaft and simultaneously pulls the primary telescopic rod 11 at the first initial position to extend for a certain distance, and the pre-compressed first spring drives the primary mounting seat 111 to be far away from the first connecting block 134, so that the primary movable rod 131 pulls the primary insertion rod 132 to be inserted into the primary insertion hole 121; when the primary telescopic rod 11 is retracted to the first initial position, the first abutting surface 311 pushes the first connecting block 134, so that the primary movable rod 131 pushes the second end of the hinge rod 42 to rotate reversely around the hinge shaft, and the secondary telescopic rod 21 at the second limit position is pulled by the pull rod 41 to move along the retraction direction of the primary telescopic rod 11, so that the secondary driving wheel 22 is reengaged with the screw rod 32.

The rear end of the pull rod 41 forms a first draw hook 411, the first draw hook 411 is hooked on the upper end of the hinge rod 42, the first-stage movable rod 131 is abutted to the lower end of the hinge rod 42, and the middle position of the hinge rod 42 is hinged to the first-stage rod body 112 through a hinge shaft. The length of the pull rod 41 of this embodiment is set according to the actual use condition, and specifically, the distance between the first hook 411 and the second hook 412 is slightly smaller than the distance between the hinge shaft and the second step surface 213 when the distance is at the second limit position. When the secondary telescopic rod 21 extends to the second limit position, the second step surface 213 of the secondary telescopic rod 21 abuts against the second draw hook 412, so that the second draw hook 412 is hooked on the second step surface 213, and further the draw rod 41 is pulled to move forward by the forward pulling force of the secondary telescopic rod 21, the upper end of the hinge rod 42 is pulled to move forward in the pulling forward process, so that the lower end of the hinge rod 42 pushes the first-stage movable rod 131 backward, at this time, because the first connecting block 134 and the first abutting surface 311 abut against each other, the first-stage movable rod 131 cannot move backward, the hinge shaft moves forward under the reaction condition, and further the first-stage telescopic rod 11 at the first initial position is pulled to extend forward, so as to drive the first-stage driving wheel 12 to move forward relative to the first-stage movable rod 131, so that the first-stage insertion rod 132 is inserted into any one of the first-stage insertion holes 121, the first-stage driving wheel 12 is locked, and the first-stage, the two continuous and orderly extension processes of the multistage telescoping device are realized.

When the first-stage telescopic rod 11 retracts from the first limit position to the first initial position, the first-stage inserted rod 132 is kept in a state of locking the first-stage driving wheel 12, until the first-stage telescopic rod 11 retracts to the first initial position, the action surface 1111 of the first-stage telescopic rod 11 abuts against the first abutting surface 311 of the sleeve 31, the first abutting surface 311 pushes the first-stage movable rod 131 to move forward, the lower end of the hinged rod 42 is driven to move forward in the process of moving forward the first-stage movable rod 131, the upper end of the hinged rod 42 moves backward, the pull rod 41 is pulled to move backward by the first pull hook 411, the second pull hook 412 pulls the second-stage telescopic rod 21 to move backward by the second step surface 213, in the process of moving backward the second-stage telescopic rod 21, the second-stage driving wheel 22 is reengaged with the screw rod 32, the second step surface 213 is separated from the second abutting surface 113, and the second-stage inserted rod 232 is reinserted into any one of the second-, so as to lock the secondary driving wheel 22, and further retract the secondary expansion link 21 to the second initial position under the reverse rotation of the screw rod 32, i.e. completely retract the secondary expansion link 21, thereby realizing two continuous and sequential retraction processes of the multi-stage expansion device.

As shown in fig. 1 to 12, in this embodiment, the multi-stage telescopic device further includes a locking mechanism 50, the locking mechanism 50 includes an insertion block 51, a compression spring 52 and a sliding block 53, one end of the insertion block 51 away from the second-stage telescopic rod 21 is connected to the first-stage telescopic rod 11 through the compression spring 52, a locking insertion hole 2121 matched with the insertion block 51 is formed in an outer wall of the second-stage telescopic rod 21, a first inclined surface 511 is formed on one side of the insertion block 51 facing the sliding block 53, the sliding block 53 is in sliding fit with the first-stage telescopic rod 11, specifically, a friction ring 1121 is disposed at a free end of the first-stage rod body 112 of the first-stage telescopic rod 11, the friction ring 1121 is sleeved outside the second-stage rod body 212, the sliding block 53 is slidably mounted on the friction ring 1121, and. One end of the sliding block 53, which is far away from the secondary telescopic rod 21, extends out of the outer wall of the primary telescopic rod 11, and a second inclined surface 531 which is in sliding fit with the first inclined surface 511 is formed on one surface, which faces the inserting block 51, of the sliding block 53; when the secondary telescopic rod 21 extends to the second limit position, the compression spring 52 drives the plug block 51 to be inserted into the locking jack 2121, so that the secondary telescopic rod 21 is locked with the primary telescopic rod 11; when the first telescopic rod 11 retracts to the first initial position, the sleeve 31 pushes the sliding block 53 to slide in the direction in which the first telescopic rod 21 extends, so that the insertion block 51 is disengaged from the locking insertion hole 2121 through the sliding fit of the second inclined surface 531 and the first inclined surface 511, so as to unlock the second telescopic rod 21 and the first telescopic rod 11.

Specifically, as shown in fig. 2, 3, 10 to 12, a locking insertion hole 2121 is formed at a position of the secondary lever body 212 of the secondary telescopic lever 21 close to the secondary mounting seat 211, the insertion block 51 is arranged at a position on the primary lever body 112 close to the free end, a first inclined surface 511 is formed at the rear side of the insertion block 51, the first inclined surface 511 is inclined downward from the rear to the front, a second inclined surface 531 is formed at the front side of the sliding block 53, and the second inclined surface 531 is inclined downward from the rear to the front so as to match with the first inclined surface 511. When second grade telescopic link 21 stretches out to the second extreme position, second grade mount pad 211 slides to the position that is close to the free end of one-level pole body 112, and locking jack 2121 corresponds with the position of inserted block 51, inserted block 51 inserts locking jack 2121 under compression spring 52's elastic force, thereby with the locking of one-level telescopic link 11 and second grade telescopic link 21, both guarantee that follow-up one-level telescopic link 11 drives second grade telescopic link 21 and one-level telescopic link 11 synchronous flexible at flexible in-process, can guarantee again that under the effect of outside force that receives backward as second grade telescopic link 21, can keep the lock state with one-level telescopic link 11, guarantee multistage telescoping device's structural stability. When the first-stage telescopic rod 11 retracts to the first initial position, the free end face of the sleeve 31 abuts against the upper end of the sliding block 53 and pushes the sliding block 53 to move forwards, in the process that the sliding block 53 moves forwards, the second inclined face 531 on the sliding block 53 is in sliding fit with the first inclined face 511 on the inserting block 51, and due to the inclined characteristics of the first inclined face 511 and the second inclined face 531, the inserting block 51 can be lifted in the process that the sliding block 53 moves forwards, so that the inserting block 51 is separated from the locking insertion hole 2121, the second-stage telescopic rod 21 is unlocked with the first-stage telescopic rod 11, and the normal retracting process of the subsequent second-stage telescopic rod 21 is ensured.

In this embodiment, the driving mechanism 33 includes a driving motor (not shown) and two bevel gears 331 engaged with each other, wherein one bevel gear 331 is fixedly sleeved on the screw rod 32, and the other bevel gear 331 is connected to the driving motor. The driving motor drives the bevel gear 331 connected with the driving motor to rotate, and then drives the bevel gear 331 sleeved on the screw rod 32 to rotate, so that motive power is provided for the screw rod 32, the rotation or reverse rotation of the screw rod 32 is realized, and the telescopic process of the multi-stage telescopic device is further realized. In order to save the occupied space, the driving mechanism 33 of the present embodiment may be installed in the base 30. This embodiment is through single driving motor as original power to adopt pure mechanical structure's mode to design multistage telescoping device, simple structure and convenient preparation, this multistage telescoping device's concertina ratio can reach more than 2.5, satisfies multiple application scene and operation requirement.

The overall working process of the multistage telescoping device of the embodiment is as follows: when the multi-stage telescopic device needs to be extended, the driving motor drives the screw rod 32 to rotate through the two bevel gears 331, the first-stage thimble 13 releases the first-stage driving wheel 12, the first-stage driving wheel 12 is in an idle running state, and the first-stage telescopic rod 11 does not extend or retract relative to the sleeve 31 and is kept at a first initial position; the secondary ejector pin 23 locks the secondary driving wheel 22, the secondary driving wheel 22 drives the secondary expansion link 21 to slide forward relative to the primary expansion link 11 from the second initial position to the second limit position along with the rotation of the screw 32, the second abutting surface 113 abuts against the second step surface 213 and pushes the second connecting block 234 so that the secondary movable rod 231 drives the secondary insertion rod 232 to disengage from the secondary insertion hole 221, and the secondary ejector pin 23 releases the secondary driving wheel 22. At this time, the locking mechanism 50 locks the two-stage telescopic rod 21 and the one-stage telescopic rod 11, meanwhile, the second step surface 213 on the two-stage telescopic rod 21 pulls the pull rod 41, the one-stage telescopic rod 11 is pulled by the pull rod 41, the action surface 1111 is separated from the first abutting surface 311, the first connecting block 134 stretches out of the action surface 1111 again under the action of the first spring, and the one-stage movable rod 131 drives the one-stage insertion rod 132 to be inserted into any one of the one-stage insertion holes 121, so that the one-stage ejector pin 13 locks the one-stage driving wheel 12, and the one-stage driving wheel 12 drives the one-stage telescopic rod 11 to slide forward relative to the sleeve 31 along with the rotation of the. It can be understood that, due to the locking action of the locking mechanism 50, the two-stage telescopic rod 21 continues to extend relative to the sleeve 31 as the one-stage telescopic rod 11 extends, so as to realize two continuous and sequential extending processes of the multi-stage telescopic device, after the multi-stage telescopic device is completely extended, the two-stage driving wheel 22 of the two-stage telescopic rod 21 is disengaged from the screw rod 32, while the one-stage driving wheel 12 of the one-stage telescopic rod 11 is kept engaged with the screw rod 32, and the one-stage thimble 13 keeps locking the one-stage driving wheel 12.

When the multi-stage telescopic device needs to be retracted, the driving motor drives the screw rod 32 to rotate reversely through the two bevel gears 331, and the first-stage driving wheel 12 drives the first-stage telescopic rod 11 to retract from the first limit position to the first initial position relative to the sleeve 31 along with the reverse rotation of the screw rod 32, and understandably, due to the locking action of the locking mechanism 50, the second-stage telescopic rod 21 retracts relative to the sleeve 31 along with the retraction of the first-stage telescopic rod 11. When the first-stage telescopic rod 11 retracts to the first initial position, the first abutting surface 311 abuts against the acting surface 1111 and pushes the first connecting block 134 to drive the first-stage inserting rod 132 to disengage from the first-stage inserting hole 121, the first-stage ejector pin 13 releases the first-stage driving wheel 12, the first-stage driving wheel 12 returns to the idle state again, and at this time, the locking mechanism 50 unlocks the second-stage telescopic rod 21 and the first-stage telescopic rod 11. Meanwhile, the first-stage thimble 13 on the first-stage telescopic rod 11 reversely pulls the pull rod 41, the second-stage telescopic rod 21 is pulled to move backwards through the pull rod 41, so that the second-stage driving wheel 22 moves backwards and is re-engaged with the screw rod 32, the second step surface 213 is separated from the second abutting surface 113, due to the elastic force of the second spring, the second connecting block 234 connected with the second-stage movable rod 231 extends forwards out of the second step surface 213, the second-stage inserted rod 232 is inserted into the second-stage jack 221, the second-stage thimble 23 re-locks the second-stage driving wheel 22, the second-stage driving wheel 22 rotates along with the screw rod 32 reversely, and the second-stage telescopic rod 21 is driven to retract to the second initial position from the second initial position relative to the first-stage telescopic rod 11, so that two continuous and orderly retracting processes of the.

The above only be the preferred embodiment of the utility model discloses a not consequently restriction the utility model discloses a patent range, all are in the utility model discloses a conceive, utilize the equivalent structure transform of what the content was done in the description and the attached drawing, or direct/indirect application all is included in other relevant technical field the utility model discloses a patent protection within range.

Claims

1. A multi-stage telescopic device, characterized in that it comprises:

2. The multi-stage telescopic device according to claim 1, wherein the secondary driving wheel is provided with a secondary jack, the secondary ejector pin comprises a secondary movable rod, a secondary jack rod and a secondary driving member, the secondary jack rod and the secondary driving member are respectively connected with the secondary movable rod, and the secondary movable rod is in sliding fit with the secondary telescopic rod; when the secondary telescopic rod is located at the second initial position, the secondary driving piece can drive the secondary movable rod to drive the secondary insertion rod to be inserted into the secondary insertion hole and lock the secondary driving wheel, or when the secondary telescopic rod extends to the second limit position, the secondary insertion rod is separated from the secondary insertion hole and releases the secondary driving wheel; when the secondary telescopic rod is located at the second limit position, the secondary driving wheel is disengaged from the screw rod.

3. The multi-stage telescopic device according to claim 2, wherein the secondary telescopic rod comprises a secondary mounting seat and a secondary rod body connected with the secondary mounting seat, the secondary driving wheel is mounted in the secondary mounting seat, and the secondary mounting seat axially limits the secondary driving wheel; the second grade movable rod slides and wears to locate the second grade mount pad, the second grade inserted bar is connected the second grade movable rod is kept away from the one end of second grade pole body, the second grade driving piece is the second spring, the first end of second spring with the second grade mount pad is connected, the second end of second spring pass through the second connecting block with keep away from on the second grade movable rod the one end of second grade inserted bar is connected.

4. The multi-stage telescopic device according to claim 3, wherein a second step surface is formed at the joint of the secondary rod body and the secondary mounting seat, a second connecting surface is formed in the secondary mounting seat, the first end of the second spring is connected with the second connecting surface, and a second abutting surface is arranged on the primary telescopic rod at a position close to the free end; when the secondary expansion link is located at the second initial position, the second connecting block extends out of the second step surface and enables the secondary insertion rod to be inserted into the secondary insertion hole; when the second-stage telescopic rod extends to the second limit position, the second abutting surface abuts against the second step surface and pushes the second connecting block to enable the second-stage movable rod to drive the second-stage inserted rod to be separated from the second-stage jack.

5. The multi-stage telescopic device according to claim 2, wherein the first-stage driving wheel is provided with a first-stage jack, the first-stage ejector pin comprises a first-stage movable rod, a first-stage jack rod and a first-stage driving piece, the first-stage jack rod and the first-stage driving piece are respectively connected with the first-stage movable rod, and the first-stage movable rod is in sliding fit with the first-stage telescopic rod; when the primary telescopic rod is located at the first initial position, the primary inserted link is separated from the primary jack and releases the primary driving wheel, or when the secondary telescopic rod extends to the second limit position, the primary driving piece can drive the primary movable rod to drive the primary inserted link to be inserted into the primary jack and lock the primary driving wheel; when the primary telescopic rod is located at the first limit position, the primary driving wheel and the screw rod are kept in a meshed state.

6. The multi-stage telescopic device according to claim 5, wherein the one-stage telescopic rod comprises a one-stage mounting seat and a one-stage rod body connected with the one-stage mounting seat, the one-stage driving wheel is mounted in the one-stage mounting seat, and the one-stage mounting seat axially limits the one-stage driving wheel; the secondary telescopic rod is sleeved in the primary rod body in a sliding manner; the one-level movable rod slides and wears to locate the one-level mount pad, the one-level inserted bar is connected the one-level movable rod is close to the one end of one-level pole body, the one-level driving piece is first spring, the first end of first spring with the one-level mount pad is connected, the second end of first spring through first connecting block with keep away from on the one-level movable rod the one end of one-level inserted bar is connected.

7. The multi-stage telescopic device according to claim 6, wherein a joint of the primary rod body and the primary mounting seat forms a first step surface, a side of the primary mounting seat, which is away from the first step surface, forms an action surface, and the first connecting block extends out of the action surface; a first connecting surface is formed in the primary mounting seat, a first end of the first spring is connected with the first connecting surface, and a first abutting surface is arranged on one side, facing the primary mounting seat, of the inner surface of the sleeve; when the primary telescopic rod is located at the first initial position, the first abutting surface abuts against the action surface and pushes the first connecting block to drive the primary inserted link to be separated from the primary jack;

8. The multi-stage telescoping device of claim 7, wherein the linkage comprises:

9. The multi-stage telescopic device according to any one of claims 1 to 8, further comprising a locking mechanism, wherein the locking mechanism comprises an insertion block, a compression spring and a sliding block, one end of the insertion block, which is away from the second-stage telescopic rod, is connected with the first-stage telescopic rod through the compression spring, the outer wall of the second-stage telescopic rod is provided with a locking jack matched with the insertion block, one side of the insertion block, which faces the sliding block, is formed with a first inclined surface, the sliding block is in sliding fit with the first-stage telescopic rod, one end of the sliding block, which is away from the second-stage telescopic rod, extends out of the outer wall of the first-stage telescopic rod, and one side of the sliding block, which faces the insertion block, is formed with a second inclined surface in sliding fit with the;

10. The multi-stage telescopic device according to any one of claims 1 to 8, wherein the driving mechanism comprises a driving motor and two bevel gears engaged with each other, wherein one of the bevel gears is fixedly sleeved on the screw rod, and the other bevel gear is connected with the driving motor.