CN112449940A

CN112449940A - Three-dimensional vegetable greenhouse who plants

Info

Publication number: CN112449940A
Application number: CN202011379970.9A
Authority: CN
Inventors: 付娟娟
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-11-30
Filing date: 2020-11-30
Publication date: 2021-03-09

Abstract

The invention provides a vegetable greenhouse for three-dimensional planting, which belongs to the technical field of vegetable greenhouses and comprises a vegetable greenhouse for three-dimensional planting, wherein the vegetable greenhouse comprises a first U-shaped portal frame and a second U-shaped portal frame, a support plate is fixedly connected between the first U-shaped portal frame and the second U-shaped portal frame, the lower end of the support plate is fixedly connected with a plurality of uniformly distributed U-shaped frameworks, U-shaped chutes are respectively formed in the upper ends of the first U-shaped portal frame and the second U-shaped portal frame, a group of sliding mechanisms are respectively arranged on the upper sides of the first U-shaped portal frame and the second U-shaped portal frame, each group of sliding mechanisms comprises a first plastic film, a first telescopic rod, a second telescopic rod, two first sliding blocks, two second gears and two supports, the two supports are respectively fixed at the upper ends of the first U-shaped portal frame and the second U-shaped portal frame, the device controls the first plastic film and the second plastic film to be opened and, the agricultural productivity is improved, the manpower is saved, and the film covering and film drawing become simpler and more convenient.

Description

Three-dimensional vegetable greenhouse who plants

Technical Field

The invention belongs to the technical field of vegetable greenhouses, and particularly relates to a three-dimensional vegetable greenhouse.

Background

A vegetable greenhouse is a frame-coated structure having excellent heat-insulating properties, which has appeared to allow people to eat out-of-season vegetables. The common vegetable greenhouse uses a bamboo structure or a steel structure framework, and one or more layers of heat-insulating plastic films are covered on the framework, so that a greenhouse space is formed. The outer film can well prevent the loss of carbon dioxide generated by the growth of the vegetables inside, so that the greenhouse has a good heat preservation effect.

In prior art, the long-term confined environment leads to in the big-arch shelter that air humidity is too big, carbon dioxide in the air reduces, harmful gas can increase in the big-arch shelter, is unfavorable for the growth of vegetables, and vegetables need absorb carbon dioxide and carry out photosynthesis, need ventilate to reduce air humidity and carry out the air exchange with the external world usually, reduce the content of harmful gas in the canopy. The plastic film is covered by manpower in the greenhouse, and is opened by manpower during ventilation, so that time and labor are wasted, the agricultural productivity is not improved, and the manpower resource is greatly wasted.

Disclosure of Invention

The invention aims to provide a three-dimensional planting vegetable greenhouse, and aims to solve the problems that in the prior art, the greenhouse needs manpower to cover a plastic film, and the plastic film needs to be opened manually during ventilation, so that time and labor are wasted, the agricultural productivity is not improved, and the manpower resource is greatly wasted.

In order to achieve the purpose, the invention provides the following technical scheme:

a vegetable greenhouse for three-dimensional planting comprises a first U-shaped portal frame and a second U-shaped portal frame, wherein a support plate is fixedly connected between the first U-shaped portal frame and the second U-shaped portal frame, the lower end of the support plate is fixedly connected with a plurality of uniformly distributed U-shaped frameworks, U-shaped chutes are formed in the upper ends of the first U-shaped portal frame and the second U-shaped portal frame, a group of sliding mechanisms are arranged on the upper sides of the first U-shaped portal frame and the second U-shaped portal frame, each group of sliding mechanisms comprises a first plastic film, a first telescopic rod, a second telescopic rod, two first sliding blocks, two second gears and two supports, the two supports are respectively fixed at the upper ends of the first U-shaped portal frame and the second U-shaped portal frame, the first telescopic rod is rotatably connected between the two supports, the first plastic film is wrapped on the circumferential surface of the first telescopic rod, and the other end of the first plastic film is fixedly connected with the second telescopic rod, two first slider sliding connection is in two U type spouts respectively, second telescopic link fixed connection is between two first sliders, two the equal fixed connection of second gear is in the circumference surface of first telescopic link, two first motors of upper end fixedly connected with of extension board, two the equal fixedly connected with third gear of output of first motor, and two third gears mesh between respectively and a plurality of second gears.

As a preferred scheme of the present invention, a set of lifting mechanisms is disposed on both left and right sides of the first U-shaped gantry and the second U-shaped gantry, each set of lifting mechanisms includes a sliding chute, a second sliding block, a rotating rod, a third motor, a belt and a roller, the sliding chute is disposed on the right end of the first U-shaped gantry, the second sliding block is slidably connected in the sliding chute, the third motor is fixedly connected to the left inner wall of the sliding chute, the rotating rod is fixedly connected to an output end of the third motor, the roller is fixedly connected to the right inner wall of the sliding chute, the lower end of the belt is fixedly connected to the upper end of the second sliding block, the other end of the belt is fixedly connected to the rotating rod, the belt is drivingly connected to the circumferential surface of the roller, a fifth telescopic rod is fixedly connected between the two second sliding blocks located on the same side, and fixed blocks are fixedly connected to both left and right ends of the first, lie in two with one side all rotate between the fixed block and be connected with the fourth telescopic link, two the circumference surface of fourth telescopic link has all wrapped up the second plastic film, and the other end fixed connection of second plastic film is in the circumference surface of third telescopic link.

As a preferred scheme of the present invention, the lower ends of the first U-shaped gantry and the second U-shaped gantry are fixedly connected with two telescopic pipes, the inner walls of the two telescopic pipes are both fixedly connected with a second motor, the output ends of the two second motors both movably penetrate the far ends of the two telescopic pipes and extend outward, and the output ends of the two second motors are both fixedly connected with a first gear.

As a preferable aspect of the present invention, a temperature sensor is fixedly connected to a lower end of the support plate.

As a preferable scheme of the present invention, the left and right ends of the first U-shaped gantry are both fixedly connected with a pressure sensor.

As a preferable aspect of the present invention, a PLC controller is fixedly connected to a front end of the first U-shaped gantry.

As a preferable scheme of the present invention, two fifth telescopic rods are fixedly connected between the adjacent ends of the first U-shaped gantry and the second U-shaped gantry, and both the fifth telescopic rods slidably penetrate through the circumferential surfaces of the plurality of U-shaped frameworks.

Compared with the prior art, the invention has the beneficial effects that:

1. when the cover film is needed in the scheme, the first motor is started, the output end of the first motor drives the third gear to rotate, the third gear drives the two second gears to rotate, the first plastic film wrapped on the first telescopic rod is separated from the circumferential surface of the first telescopic rod when the two second gears rotate, the two first sliding blocks slide downwards along the U-shaped sliding groove, the second telescopic rod drives the lower end of the first plastic film to move downwards, when the first sliding blocks reach the pressure sensor, the PLC controller controls the first motor to stop running, the third motor is started, the third motor rotates, the belt pulls the second sliding blocks to slide upwards in the sliding groove, the second plastic film rotates to be separated from the surface of the fourth telescopic rod, the PLC controller controls the third motor to stop when the third telescopic rod reaches the pressure sensor, and at the moment, the first plastic film and the second plastic film completely cover the Roc framework, when the second plastic film is required to be pulled open for ventilation, the third motor is started, the second sliding block slides downwards, the second plastic film is wrapped on the circumferential surface of the fourth telescopic rod again, the second sliding block cannot move continuously until the bottom of the sliding groove slides to the bottom of the sliding groove, the third motor is stopped, the second plastic film is opened at the moment, the device automatically covers the first plastic film and the second plastic film through machinery, time and labor are saved, agricultural productivity is improved, manpower is saved, and film covering and film pulling are enabled to be simpler and more convenient.

2. Start two second motors in this scheme, two second motors drive two first gear revolve, two first gears drive first U type portal and move forward, flexible pipe, the fifth telescopic link, the fourth telescopic link, the third telescopic link, the second telescopic link, extension board and first telescopic link become tensile state by the contraction state, until can't continue when moving, close two second motors, whole big-arch shelter is opened this moment, this device is through flexible, can open the big-arch shelter automatically, do not need a root installation skeleton, let the installation become more simply laborsaving.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 is a first perspective view of the present invention;

FIG. 2 is a second perspective view of the present invention;

FIG. 3 is an enlarged view at A in a second perspective of the present invention;

FIG. 4 is a third perspective view of the present invention;

in the figure: 1. a first U-shaped gantry; 2. a U-shaped framework; 3. a telescopic pipe; 4. a first plastic film; 5. a first telescopic rod; 6. a first slider; 7. a second plastic film; 8. a first gear; 9. a second gear; 10. a third gear; 11. a first motor; 12. a support plate; 13. a support; 14. a U-shaped chute; 15. a pressure sensor; 16. a fifth telescopic rod; 17. a temperature sensor; 18. a second telescopic rod; 19. a third telescopic rod; 20. a fourth telescopic rod; 21. a second motor; 22. a PLC controller; 23. a chute; 24. a roller; 25. a third motor; 26. rotating the rod; 27. a belt; 28. a second slider; 29. a second U-shaped portal; 30. and (5) fixing blocks.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

Referring to fig. 1-4, the present invention provides the following technical solutions:

a vegetable greenhouse for three-dimensional planting comprises a first U-shaped portal 1 and a second U-shaped portal 29, a support plate 12 is fixedly connected between the first U-shaped portal 1 and the second U-shaped portal 29, a plurality of evenly distributed U-shaped frameworks 2 are fixedly connected at the lower end of the support plate 12, U-shaped chutes 14 are respectively formed at the upper ends of the first U-shaped portal 1 and the second U-shaped portal 29, a group of sliding mechanisms are respectively arranged at the upper sides of the first U-shaped portal 1 and the second U-shaped portal 29, each group of sliding mechanisms comprises a first plastic film 4, a first telescopic rod 5, a second telescopic rod 18, two first sliders 6, two second gears 9 and two supports 13, the two supports 13 are respectively fixed at the upper ends of the first U-shaped portal 1 and the second U-shaped portal 29, the first telescopic rod 5 is rotatably connected between the two supports 13, the first plastic film 4 is wrapped on the circumferential surface of the first telescopic rod 5, and fixed connection between the other end of first plastic film 4 and second telescopic link 18, two first sliders 6 are sliding connection respectively in two U type spouts 14, second telescopic link 18 fixed connection is between two first sliders 6, the equal fixed connection of two second gears 9 is in the circumferential surface of first telescopic link 5, the upper end fixedly connected with two first motors 11 of extension board 12, the equal fixedly connected with third gear 10 of output of two first motors 11, and two third gears 10 mesh respectively with between a plurality of second gears 9.

In the embodiment of the invention, a first U-shaped portal frame 1 and a second U-shaped portal frame 29 are used for positioning the whole vegetable greenhouse door, a plurality of U-shaped frameworks 2 are arranged between the first U-shaped portal frame 1 and the second U-shaped portal frame 29 and are used for supporting plastic films, a support plate 12 is fixed between the first U-shaped portal frame 1 and the second U-shaped portal frame 29 and is used for supporting a first telescopic rod 5, a telescopic pipe 3 is composed of pipes with different sizes, the telescopic pipe 3 can be extended to drive the plurality of U-shaped frameworks 2 to move, the first U-shaped portal frame 1, the second U-shaped portal frame 29, two telescopic pipes 3 and the plurality of U-shaped frameworks 2 form an integral framework of the greenhouse, a first plastic film 4 and a second plastic film 7 are covered on the surfaces of the plurality of U-shaped frameworks 2 to form the greenhouse, after the integral framework is built, a cover film is covered, when the cover film is needed, a PLC 22 is used for starting a first motor 11, the output end of the first motor 11, thereby driving the two second gears 9 to rotate, the two second gears 9 rotate to enable the first plastic film 4 wrapped on the circumferential surface of the first telescopic rod 5, the U-shaped chute 14 drives the other end of the first plastic film 4 to move downwards due to gravity, the two first sliding blocks 6 slide downwards along the U-shaped chute 14, the two first sliding blocks 6 limit the second telescopic rod 18 to slide on the surfaces of the first U-shaped gantry 1 and the second U-shaped gantry 29, when the first sliding block 6 contacts with the pressure sensor 15, the pressure sensor 15 transmits a signal to the PLC 22, the PLC 22 controls the first motor 11 to stop running, at the moment, the upper film is covered, the belt 27 is shortened while the third motor 25 is started, the belt 27 pulls the second sliding block 28 to slide, one end of the second plastic film 7 leaves the surface of the fourth telescopic rod 20 along with the third telescopic rod 19, the third telescopic rod 19 moves upward along with the second slider 28, when the third telescopic rod 19 reaches the pressure sensor 15, the PLC controller 22 controls the third motor 25 to stop, at this time, the first plastic film 4 and the second plastic film 7 completely cover the frame of the greenhouse, and the first motor 11, the second motor 21 and the third motor 25 may select different models according to actual requirements, for example, the model is selected to be YY5034, and the first motor 11, the second motor 21 and the third motor 25 are electrically connected to an external power supply. This device can cover and open first plastic film 4 and second plastic film 7 through mechanical automation, and labour saving and time saving has improved agricultural productivity, lets the epiphragma become more simple and convenient with drawing the membrane.

Referring to fig. 2 and 3, a set of lifting mechanisms is respectively disposed on the left and right sides of the first U-shaped gantry 1 and the second U-shaped gantry 29, each set of lifting mechanisms includes a sliding groove 23, a second sliding block 28, a rotating rod 26, a third motor 25, a belt 27 and a roller 24, the sliding groove 23 is disposed at the right end of the first U-shaped gantry 1, the second sliding block 28 is slidably connected in the sliding groove 23, the third motor 25 is fixedly connected to the left inner wall of the sliding groove 23, the rotating rod 26 is fixedly connected to the output end of the third motor 25, the roller 24 is fixedly connected to the right inner wall of the sliding groove 23, the lower end of the belt 27 is fixedly connected to the upper end of the second sliding block 28, the other end of the belt 27 is fixedly connected to the rotating rod 26, the belt 27 is drivingly connected to the circumferential surface of the roller 24, a fifth telescopic rod 16 is fixedly connected between the two second sliding blocks 28 located on the same side, fixed blocks 30 are fixedly connected to the left, all rotate between two fixed blocks 30 that lie in same side and be connected with fourth telescopic link 20, the circumferential surface of two fourth telescopic links 20 has all wrapped up second plastic film 7, and the other end fixed connection of second plastic film 7 is in the circumferential surface of third telescopic link 19.

In this embodiment: when the vegetable greenhouse needs to be opened and ventilated, the third motor 25 is started, the second slider 28 slides downwards in the sliding groove 23, the second slider 28 drives the third telescopic rod 19 to slide downwards, the fourth telescopic rod 20 rotates on the two fixing blocks 30 to wrap the second plastic film 7 on the circumferential surface of the fourth telescopic rod 20 again, until the second slider 28 slides to a needed position, the third motor 25 is stopped, the upper side and the left and right sides of the vegetable greenhouse are provided with films, when the vegetable greenhouse is ventilated in the greenhouse, only the second plastic film 7 needs to be opened, the device can control the distance of the third telescopic rod 19 to move to control the size of the second plastic film 7, the size of the ventilation opening is selectively set, and the use environment of the greenhouse is increased.

Referring to fig. 2, the lower ends of the first U-shaped gantry 1 and the second U-shaped gantry 29 are fixedly connected with two telescopic pipes 3, the inner walls of the two telescopic pipes 3 are fixedly connected with second motors 21, the output ends of the two second motors 21 movably penetrate through the far ends of the two telescopic pipes 3 and extend outwards, and the output ends of the two second motors 21 are fixedly connected with first gears 8.

In this embodiment: the telescopic pipe 3, the fifth telescopic rod 16, the fourth telescopic rod 20, the third telescopic rod 19, the second telescopic rod 18, the support plate 12 and the first telescopic rod 5 can be contracted to fold and expand the whole greenhouse, when the vegetable greenhouse needs to be opened and installed, the framework is directly placed on the ground, the two second motors 21 are started, the two second motors 21 drive the two first gears 8 to rotate, the two first gears 8 drive the first U-shaped portal frame 1 to move forwards on the ground, the telescopic pipe 3, the fifth telescopic rod 16, the fourth telescopic rod 20, the third telescopic rod 19, the second telescopic rod 18, the support plate 12 and the first telescopic rod 5 are changed from a contracted state to a stretched state until the framework cannot move continuously, the two second motors 21 are closed, the whole greenhouse is opened at the moment, the framework of the greenhouse in the device is integrated, the greenhouse can be automatically opened through expansion and does not need one installation framework, the installation becomes simpler and more labor-saving.

Specifically referring to fig. 4, a temperature sensor 17 is fixedly connected to the lower end of the support plate 12.

In this embodiment: signal connection between temperature-sensing ware 17 and the PLC controller 22, when the high temperature in the canopy, PLC controller 22 can control third motor 25 and start, opens second plastic film 7 by oneself and ventilates, and temperature-sensing ware 17 and external power source electric connection, this device let the vegetable greenhouse more intelligent, operate simplyr.

Referring to fig. 1, pressure sensors 15 are fixedly connected to both left and right ends of the first U-shaped gantry 1.

In this embodiment: signal connection between two pressure sensors 15 and the PLC controller 22, when first slider 6 contacted pressure sensors 15, PLC controller 22 can control first motor 11 stall, and two pressure sensors 15 all with external power source electric connection, this device do not the manpower can automatic stop first motor 11.

Specifically referring to fig. 4, a PLC controller 22 is fixedly connected to the front end of the first U-shaped gantry 1.

In this embodiment: two pressure sensors 15 and temperature-sensing ware 17 all with PLC controller 22 between signal connection, two pressure sensors 15, temperature-sensing ware 17, first motor 11, two second motors 21 and PLC controller 22 all with external power source electric connection, this device can replace the interior operation of manual control canopy.

Specifically referring to fig. 4, two fifth telescopic rods 16 are fixedly connected between the adjacent ends of the first U-shaped gantry 1 and the second U-shaped gantry 29, and the two fifth telescopic rods 16 both slide through the circumferential surfaces of the U-shaped frameworks 2.

In this embodiment: two fifth telescopic links 16 can restrict a plurality of U type skeletons 2 and can not rock, and this device can let the skeleton of vegetable greenhouse more stable.

The working principle and the using process of the invention are as follows: firstly, placing a framework of the vegetable greenhouse on the ground, starting two second motors 21, driving two first gears 8 to rotate by the two second motors 21, driving a first U-shaped portal 1 to move forwards on the ground by the two first gears 8, gradually opening the framework of the vegetable greenhouse along with the movement of the two first gears 8 until the framework cannot move continuously, closing the two second motors 21, starting a first motor 11, driving a third gear 10 to rotate by an output end of the first motor 11, driving two second gears 9 to rotate by the third gear 10, when the second gear 9 rotates, due to gravity, a second telescopic rod 18 slides downwards along a U-shaped chute 14 through two first sliding blocks 6, a first plastic film 4 gradually covers the framework along with the movement of the second telescopic rod 18, and when the first sliding block 6 reaches a pressure sensor 15, a PLC 22 controls the first motor 11 to stop running, the third motor 25 is started, the third motor 25 rotates, the belt 27 pulls the second slide block 28 to slide upwards in the slide groove 23, the second plastic film 7 rotates away from the surface of the fourth telescopic rod 20, and as the third telescopic rod 19 moves upwards, when the third telescopic rod 19 reaches the pressure sensor 15, the PLC controller 22 controls the third motor 25 to stop, at this time, the first plastic film 4 and the second plastic film 7 completely cover the frame of the dac, when the temperature in the shed reaches a certain value, the temperature sensor 17 transmits a signal to the PLC controller 22, the PLC controller 22 controls the first motor 11 and the third motor 25 to reversely operate, the second plastic film 7 and the first plastic film 4 can be opened for ventilation, the device controls the first plastic film 4 and the second plastic film 7 to be opened and covered through the PLC 22, the agricultural productivity is improved, the manpower is saved, and the film covering and film drawing become simpler and more convenient.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a vegetable greenhouse of stereoscopic planting which characterized in that: the device comprises a first U-shaped portal (1) and a second U-shaped portal (29), wherein a support plate (12) is fixedly connected between the first U-shaped portal (1) and the second U-shaped portal (29), the lower end of the support plate (12) is fixedly connected with a plurality of uniformly distributed U-shaped frameworks (2), U-shaped chutes (14) are formed in the upper ends of the first U-shaped portal (1) and the second U-shaped portal (29), a group of sliding mechanisms are arranged on the upper sides of the first U-shaped portal (1) and the second U-shaped portal (29), each group of sliding mechanisms comprises a first plastic film (4), a first telescopic rod (5), a second telescopic rod (18), two first sliding blocks (6), two second gears (9) and two supports (13), the two supports (13) are respectively fixed at the upper ends of the first U-shaped portal (1) and the second U-shaped portal (29), first telescopic link (5) rotate to be connected between two supports (13), first plastic film (4) parcel is on the circumferential surface of first telescopic link (5), and fixed connection between the other end of first plastic film (4) and second telescopic link (18), two first slider (6) sliding connection respectively in two U type spouts (14), second telescopic link (18) fixed connection is between two first sliders (6), two the equal fixed connection of second gear (9) is in the circumferential surface of first telescopic link (5), two first motor (11) of upper end fixedly connected with of extension board (12), two the equal fixedly connected with third gear (10) of output of first motor (11), and two third gear (10) mesh mutually between respectively and a plurality of second gear (9).

2. The vegetable greenhouse of claim 1, wherein the vegetable greenhouse comprises: the left and right sides of first U type portal (1) and second U type portal (29) all is provided with a set of mechanism that rises, and every group mechanism that rises all includes spout (23), second slider (28), dwang (26), third motor (25), belt (27) and gyro wheel (24), the right-hand member of first U type portal (1) is seted up in spout (23), second slider (28) sliding connection is in spout (23), third motor (25) fixed connection is in the left inner wall of spout (23), dwang (26) fixed connection is in the output of third motor (25), gyro wheel (24) fixed connection is in the right inner wall of spout (23), the lower extreme fixed connection of belt (27) is in the upper end of second slider (28), fixed connection between the other end of belt (27) and dwang (26), and belt (27) transmission connection is in the circumference surface of gyro wheel (24), lie in two with one side equal fixedly connected with fifth telescopic link (16) between second slider (28), equal fixedly connected with fixed block (30) in both ends about first U type portal (1) and second U type portal (29), lie in two with one side all rotate between fixed block (30) and be connected with fourth telescopic link (20), two the circumferential surface of fourth telescopic link (20) has all wrapped up second plastic film (7), and the other end fixed connection of second plastic film (7) is in the circumferential surface of third telescopic link (19).

3. The vegetable greenhouse of claim 2, wherein the vegetable greenhouse comprises: two flexible pipe (3) of lower extreme fixedly connected with of first U type portal (1) and second U type portal (29), two equal fixedly connected with second motor (21) between the inner wall of flexible pipe (3), two the equal activity of output of second motor (21) runs through keeping away from the end and outwards extending mutually of two flexible pipe (3), two the equal fixedly connected with first gear (8) of output of second motor (21).

4. The vegetable greenhouse of claim 3, wherein the vegetable greenhouse comprises: the lower end of the support plate (12) is fixedly connected with a temperature sensor (17).

5. The vegetable greenhouse of claim 4, wherein the vegetable greenhouse comprises: the left end and the right end of the first U-shaped gantry (1) are fixedly connected with pressure sensors (15).

6. The vegetable greenhouse of claim 5, wherein the vegetable greenhouse comprises: the front end of the first U-shaped gantry (1) is fixedly connected with a PLC (programmable logic controller) (22).

7. The vegetable greenhouse of claim 6, wherein the vegetable greenhouse comprises: the first U-shaped gantry (1) and the second U-shaped gantry (29) are close to two fifth telescopic rods (16) fixedly connected between the ends, and the two fifth telescopic rods (16) penetrate through the circumferential surfaces of the U-shaped frameworks (2) in a sliding mode.