Anti-interference gradienter for constructional engineering

Abstract

The invention provides an anti-interference gradienter for constructional engineering, which belongs to the technical field of measuring instruments and comprises a gradienter body, a tripod and an anti-interference mechanism arranged on the tripod. The tripod comprises a supporting ring and a supporting rod hinged to the supporting ring. The number of the supporting rods is at least three. The supporting rods are evenly distributed in the circumferential direction of the supporting ring. The anti-interference mechanism is arranged on the tripod; the anti-interference mechanism comprises a stabilizing ring, a stabilizing disc and a balancing weight. The stabilizing ring is rotationally connected to the supporting ring. The stabilizing ring is horizontally arranged, and a rotating shaft of the stabilizing ring is arranged along the diameter of the stabilizing ring. The stabilizing disc is rotationally connected into the stabilizing ring; the stabilizing disc is horizontally arranged, and the rotating shaft of the stabilizing ring is arranged along the diameter of the stabilizing disc. The stabilizing ring is rotationally connected with the supporting ring, the stabilizing disc is also rotationally connected with the stabilizing ring, and vibration transmitted to the stabilizing disc is weakened. And under the action of the balancing weight, the stabilizing disc can quickly return to the horizontal state, so that the anti-interference capability of the gradienter is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of measuring instruments, and more specifically, relates to an anti-interference level meter for construction engineering. Background Art

[0002] Levels play a vital role in construction projects, and are mainly used to ensure the horizontal accuracy of buildings or structures. Levels are usually used at construction sites, which are usually complex and generate a lot of vibration on the ground during the construction process. When working, the level usually needs to be placed on a bracket. Existing levels have weak anti-interference capabilities and cannot avoid vibration interference. Summary of the invention

[0003] The purpose of the present invention is to provide an anti-interference level for construction engineering, aiming to solve the problem that the existing level has poor ability to resist vibration interference during operation.

[0004] To achieve the above object, the technical solution adopted by the present invention is: to provide an anti-interference level meter for construction engineering, comprising:

[0005] Level body;

[0006] A tripod, comprising a support ring and support rods hinged on the support ring; at least three support rods are provided; the support rods are evenly distributed along the circumference of the support ring; and

[0007] The anti-interference mechanism is arranged on the tripod; the anti-interference mechanism comprises:

[0008] A stabilizing ring is rotatably connected to the supporting ring; the stabilizing ring is horizontally arranged, and the rotating axis of the stabilizing ring is arranged along the diameter of the stabilizing ring;

[0009] A stabilizing disk is rotatably connected in the stabilizing ring; the stabilizing disk is horizontally arranged, and the rotating shaft of the stabilizing ring is arranged along the diameter of the stabilizing disk; the stabilizing disk, the stabilizing ring and the supporting ring are coaxially arranged; the level body is arranged on the stabilizing disk; and

[0010] A counterweight block is arranged on the lower side of the stabilizing plate; the center of gravity of the counterweight block coincides with the axis of the stabilizing plate.

[0011] In a possible implementation, two first rotating shafts are provided on the outer surface of the stabilizing ring; the two first rotating shafts are respectively arranged at both ends of a diameter of the stabilizing ring; and two first mounting holes are opened on the inner wall of the support ring, the two first mounting holes respectively correspond to the two first rotating shafts, and the two first rotating shafts are respectively arranged in the two first mounting holes.

[0012] In a possible implementation, two second rotating shafts are provided on the side of the stabilizing disk, and the two second rotating shafts are respectively arranged at both ends of a diameter of the stabilizing disk; two second mounting holes are opened on the inner wall of the stabilizing ring, and the two second mounting holes correspond to the two second rotating shafts respectively, and the two second rotating shafts are respectively arranged in the two second mounting holes; the second rotating shaft is not colinear with the first rotating shaft.

[0013] In a possible implementation manner, the first rotation axis is perpendicular to the second rotation axis.

[0014] In a possible implementation, it also includes a locking bolt arranged on the support ring; a threaded hole is opened on the support ring, and a through hole is opened on the stabilizing ring; the locking bolt is arranged in the threaded hole, can pass through the through hole and abut against the side of the stabilizing disk.

[0015] In a possible implementation manner, the locking bolt is staggered with the first rotating shaft and the second rotating shaft.

[0016] In a possible implementation, a mounting groove is provided inside the counterweight block; a motor and a turntable are provided in the mounting groove; a power output shaft of the motor is connected to a rotating shaft of the turntable, and the rotating shaft of the turntable coincides with the center of gravity of the counterweight block.

[0017] In a possible implementation, the support rod includes:

[0018] A top rod, the top of which is hinged on the support rod;

[0019] a bottom rod slidably connected to the top rod; and

[0020] A vibration reduction assembly is arranged between the top rod and the bottom rod.

[0021] In a possible implementation, a slide groove is provided at the bottom of the top rod, the top of the bottom rod is inserted into the slide groove, and the vibration reduction assembly is arranged in the slide groove.

[0022] In a possible implementation, a protective cover is provided at the junction of the top rod and the bottom rod, and the protective cover is slidably matched with the top rod or the bottom rod.

[0023] The beneficial effect of the anti-interference level for construction engineering provided by the present invention is that: compared with the prior art, the anti-interference level for construction engineering provided by the present invention, when working, the level body is fixed on the stable disk. Under the action of the counterweight, the center line of the stable disk is located below the support rod and the stable ring, so that the stable disk is in a horizontal state. When the vibration on the ground is transmitted to the anti-interference mechanism through the tripod, the vibration is weakened because the stable ring and the support ring are rotationally connected and the two are non-rigidly connected. At the same time, since the stable disk and the stable ring are also rotationally connected, the vibration transmitted to the stable disk is further weakened. Under the action of the counterweight, the stable disk is kept in a horizontal state, reducing the influence of small vibrations, thereby improving the anti-interference ability of the level when working. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 A schematic diagram of the structure of an anti-interference level meter for construction engineering provided by an embodiment of the present invention;

[0026] Figure 2 A schematic diagram of the structure of an anti-interference mechanism provided by an embodiment of the present invention;

[0027] Figure 3 A schematic structural diagram of a support rod provided in an embodiment of the present invention.

[0028] Description of reference numerals:

[0029] 1. Level body; 2. Tripod; 21. Support ring; 211. First mounting hole; 212. Threaded hole; 22. Support rod; 221. Top rod; 222. Bottom rod; 3. Stabilizing ring; 31. First rotating shaft; 32. Second mounting hole; 33. Through hole; 4. Stabilizing disk; 41. Second rotating shaft; 5. Counterweight; 51. Mounting slot; 6. Locking bolt; 7. Motor; 8. Turntable; 9. Vibration reduction assembly; 10. Protective cover. DETAILED DESCRIPTION

[0030] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0031] Reference Figure 1 and Figure 3Now, the anti-interference level meter for construction engineering provided by the present invention is described. Figure 1 The invention discloses an anti-interference level for construction engineering, comprising a level body 1, a tripod 2 and an anti-interference mechanism arranged on the tripod 2.

[0032] The tripod includes a support ring 21 and a support rod 22 hinged on the support ring 21; at least three support rods 22 are provided; and the support rods 22 are evenly distributed along the circumference of the support ring 21. The anti-interference mechanism is provided on the tripod; the anti-interference mechanism includes: a stabilizing ring 3, a stabilizing plate 4 and a counterweight 5.

[0033] The stabilizing ring 3 is rotatably connected to the supporting ring 21; the stabilizing ring 3 is arranged horizontally, and the rotating shaft of the stabilizing ring 3 is arranged along the diameter of the stabilizing ring 3. The stabilizing disk 4 is rotatably connected to the stabilizing ring 3; the stabilizing disk 4 is arranged horizontally, and the rotating shaft of the stabilizing ring 3 is arranged along the diameter of the stabilizing disk 4; the stabilizing disk 4, the stabilizing ring 3 and the supporting ring 21 are arranged coaxially; the level body 1 is arranged on the stabilizing disk 4. The counterweight block 5 is arranged on the lower side of the stabilizing disk 4; the center of gravity of the counterweight block 5 coincides with the axis of the stabilizing disk 4.

[0034] Compared with the prior art, the anti-interference level for construction engineering provided by the present invention has the following characteristics: during operation, the level body 1 is fixed on the stabilizing plate 4. Under the action of the counterweight 5, the center line of the stabilizing plate 4 is located below the support rod 22 and the stabilizing ring 3, so that the stabilizing plate 4 is in a horizontal state. When the vibration on the ground is transmitted to the anti-interference mechanism through the tripod 2, the vibration is weakened because the stabilizing ring 3 and the support ring 21 are rotatably connected and the two are non-rigidly connected. At the same time, since the stabilizing plate 4 and the stabilizing ring 3 are also rotatably connected, the vibration transmitted to the stabilizing plate 4 is further weakened. Under the action of the counterweight 5, the stabilizing plate 4 is kept in a horizontal state, reducing the influence of small vibrations. Even if vibrations are transmitted to the stabilizing plate 4, under the action of the counterweight 5, the stabilizing plate 4 can quickly return to a horizontal state, thereby improving the anti-interference ability of the level when working.

[0035] In a possible implementation, two first rotating shafts 31 are provided on the outer surface of the stabilizing ring 3; the two first rotating shafts 31 are respectively arranged at the two ends of a diameter of the stabilizing ring 3; two first mounting holes 211 are opened on the inner wall of the supporting ring 21, the two first mounting holes 211 respectively correspond to the two first rotating shafts 31, and the two first rotating shafts 31 are respectively arranged in the two first mounting holes 211.

[0036] In a possible implementation, two second rotating shafts 41 are provided on the side of the stabilizing disk 4, and the two second rotating shafts 41 are respectively arranged at both ends of a diameter of the stabilizing disk 4; two second mounting holes 32 are opened on the inner wall of the stabilizing ring 3, and the two second mounting holes 32 respectively correspond to the two second rotating shafts 41, and the two second rotating shafts 41 are respectively arranged in the two second mounting holes 32; the second rotating shaft 41 is not colinear with the first rotating shaft 31.

[0037] In a possible implementation, the first rotation axis 31 is perpendicular to the second rotation axis 41 .

[0038] In a preferred embodiment, a threaded hole 212 is provided on the outer side of the stabilizing ring 3, and the first rotating shaft 31 is threadedly installed in the threaded hole 212. A bearing is installed inside the first installation hole 211, and the first rotating shaft 31 is installed in the bearing. Under the action of the first rotating shaft 31 and the bearing, the stabilizing ring 3 can rotate freely around the first rotating shaft 31.

[0039] A threaded hole 212 is provided on the side of the stabilizing plate 4, and the second rotating shaft 41 is threadedly installed in the threaded hole 212. A bearing is installed in the second installation hole 32, and the second rotating shaft 41 is installed in the bearing. Under the action of the second rotating shaft 41 and the bearing, the stabilizing plate 4 can rotate freely around the second rotating shaft 41. At the same time, the first rotating shaft 31 and the second rotating shaft 41 are perpendicular to each other. The first rotating shaft 31 is arranged in the upper part of the stabilizing ring 3, so that the center of gravity of the stabilizing ring 3 is located directly below the first rotating shaft 31. After the stabilizing ring 3 is stabilized, the stabilizing ring 3 is stabilized in a horizontal state.

[0040] In a preferred embodiment, a threaded hole 212 is provided on the outer side of the stabilizing ring 3, and the first rotating shaft 31 is threadedly installed in the threaded hole 212. The first rotating shaft 31 is installed in the first mounting hole 211, and the first rotating shaft 31 and the first mounting hole 211 are clearance-matched, and lubricating grease is added between the first rotating shaft 31 and the first mounting hole 211. Under the action of the lubricating grease, the stabilizing ring 3 can rotate freely around the first rotating shaft 31.

[0041] A threaded hole 212 is provided on the side of the stabilizing disk 4, and the second rotating shaft 41 is threadedly installed in the threaded hole 212. The second rotating shaft 41 is installed in the second mounting hole 32, and the second rotating shaft 41 and the second mounting hole 32 are clearance-matched, and lubricating grease is added between the second mounting hole 32 and the second rotating shaft 41. Under the action of the lubricating grease, the stabilizing disk 4 can rotate freely around the second rotating shaft 41. At the same time, the first rotating shaft 31 and the second rotating shaft 41 are perpendicular to each other. The first rotating shaft 31 is arranged in the upper half of the stabilizing ring 3, so that the center of gravity of the stabilizing ring 3 is located directly below the first rotating shaft 31. After the stabilizing ring 3 is stabilized, the stabilizing ring 3 is stabilized in a horizontal state.

[0042] In a possible implementation, it also includes a locking bolt 6 arranged on the support ring 21; a threaded hole 212 is opened on the support ring 21, and a through hole 33 is opened on the stabilizing ring 3; the locking bolt 6 is arranged in the threaded hole 212, can pass through the through hole 33 and abut against the side of the stabilizing disk 4.

[0043] In a possible implementation, the locking bolt 6 is staggered with the first rotating shaft 31 and the second rotating shaft 41 .

[0044] The locking bolt 6 is threadedly matched with the threaded hole 212. When the locking bolt 6 rotates in the threaded hole 212, it can slide in the through hole 33. When the locking bolt 6 passes through the through hole 33 and abuts against the side of the stabilizing disk 4, the position of the stabilizing ring 3 and the stabilizing disk 4 is locked and cannot rotate freely. When the locking bolt 6 is out of contact with the stabilizing disk 4 and is pulled out from the through hole 33. At this time, the stabilizing ring 3 and the stabilizing disk 4 are unlocked and can rotate freely. When the level is not working, the level body 1 is removed from the stabilizing disk 4, and the tripod 2 and the anti-interference mechanism are retracted. At this time, rotate the locking bolt 6 so that the locking bolt 6 passes through the through hole 33 and abuts against the side of the stabilizing disk 4, locks the position of the stabilizing ring 3 and the stabilizing disk 4, and prevents the stabilizing ring 3 and the stabilizing disk 4 from rotating. When the level is working, first set up the tripod 2, install the level body 1 on the stabilizing plate 4, then rotate the locking bolt 6 to make the locking bolt 6 break contact with the side of the stabilizing plate 4, and make the locking bolt 6 leave the through hole 33 to unlock the stabilizing plate 4 and the stabilizing ring 3.

[0045] Reference Figure 2 In a possible implementation, a mounting groove 51 is provided inside the counterweight block 5; a motor 7 and a turntable 8 are provided in the mounting groove 51; a power output shaft of the motor 7 is connected to a rotating shaft of the turntable 8, and the rotating shaft of the turntable 8 coincides with the center of gravity of the counterweight block 5.

[0046] When the level body 1 is working, the motor 7 is started, and the motor 7 drives the turntable 8 to rotate. The stability of the turntable 8 when rotating at high speed is used to improve the stability of the counterweight 5 and the stabilizing plate 4. When the vibration on the ground is transmitted to the support ring 21, due to the rotational fit between the stabilizing ring 3 and the support ring 21, and the center of gravity of the support ring 21 is located directly below the first rotating shaft 31, only part of the vibration is transmitted to the stabilizing ring 3 through the support ring 21, and at the same time, it is ensured that the stabilizing ring 3 can be stabilized on the horizontal plane. When part of the vibration is transmitted to the stabilizing plate 4, due to the rotational fit between the stabilizing plate 4 and the stabilizing ring 3, the vibration is weakened again and then transmitted to the stabilizing plate 4. When the stabilizing plate 4 is disturbed by vibration, the high-speed rotating turntable 8 can improve the stability of the stabilizing plate 4.

[0047] Reference Figure 3 In a possible implementation, the support rod 22 includes:

[0048] A top rod 221, the top of which is hinged on the support rod 22;

[0049] A bottom rod 222 is slidably connected to the top rod 221; and

[0050] The vibration reduction assembly 9 is arranged between the top rod 221 and the bottom rod 222 .

[0051] In a possible implementation, a slide groove is provided at the bottom of the top rod 221, the top of the bottom rod 222 is inserted into the slide groove, and the vibration reduction assembly 9 is arranged in the slide groove.

[0052] In a possible implementation, a protective cover 10 is provided at the junction of the top rod 221 and the bottom rod 222 , and the protective cover 10 is slidably matched with the top rod 221 or the bottom rod 222 .

[0053] In a preferred embodiment, the diameter of the bottom rod 222 is the same as that of the top rod 221. A plug rod is provided at the top of the bottom rod 222. The plug rod has the same diameter as that of the chute. The plug rod is inserted into the chute and slides in the chute. The bottom rod 222 is slidably matched with the top rod 221 through the plug rod. The vibration reduction assembly 9 is provided at the top of the chute. The top of the vibration reduction assembly 9 contacts the top inner wall of the chute, and the bottom of the vibration reduction assembly 9 contacts the top of the plug rod.

[0054] The vibration reduction component 9 is an airbag filled with high-pressure air. The airbag has good elasticity. When the airbag is impacted, it can deform and absorb the impact force to weaken the vibration. When the vibration on the ground is transmitted to the top rod 221 through the bottom rod 222, the bottom rod 222 contacts the airbag, and the airbag is deformed by the impact of the insertion rod. When the airbag is impacted by the vibration peak, the pressure inside it increases, absorbing the energy of the vibration and weakening the vibration peak transmitted to the top rod 221. When the airbag is impacted by the trough, the airbag releases the pressure inside it, reducing the vibration trough of the top rod 221 and improving the stability of the top rod 221 and the stabilizing ring 3.

[0055] In a preferred embodiment, the diameter of the bottom rod 222 is the same as that of the top rod 221. A plug rod is provided at the top of the bottom rod 222. The plug rod has the same diameter as that of the chute. The plug rod is inserted into the chute and slides in the chute. The bottom rod 222 is slidably matched with the top rod 221 through the plug rod. The vibration reduction assembly 9 is provided at the top of the chute. The top of the vibration reduction assembly 9 contacts the top inner wall of the chute, and the bottom of the vibration reduction assembly 9 contacts the top of the plug rod.

[0056] The vibration reduction component 9 is a spring filled with high-pressure air. The spring has good elasticity. When the spring is impacted, it can deform and absorb the impact force to weaken the vibration. When the vibration on the ground is transmitted to the top rod 221 through the bottom rod 222, the bottom rod 222 contacts the spring. The spring is deformed by the impact of the plug rod, and its elastic potential energy increases, absorbing the energy of the vibration and weakening the vibration transmitted to the top rod 221. When the spring is impacted by the vibration peak, its elastic potential energy increases, absorbing the energy of the vibration and weakening the vibration peak transmitted to the top rod 221. When the spring is impacted by the trough, the spring releases its elastic potential energy, reduces the vibration trough of the top rod 221, and improves the stability of the top rod 221 and the stabilizing ring 3.

[0057] In a preferred embodiment, the diameter of the bottom rod 222 is the same as that of the top rod 221. A plug rod is provided at the top of the bottom rod 222. The plug rod has the same diameter as that of the chute. The plug rod is inserted into the chute and slides in the chute. The bottom rod 222 is slidably matched with the top rod 221 through the plug rod. The vibration reduction assembly 9 is provided at the top of the chute. The top of the vibration reduction assembly 9 contacts the top inner wall of the chute, and the bottom of the vibration reduction assembly 9 contacts the top of the plug rod.

[0058] The vibration reduction component 9 is a rubber shock-absorbing pad, which is filled with high-pressure air. The rubber shock-absorbing pad has good elasticity. When the rubber shock-absorbing pad is impacted, it can deform and absorb the impact force to weaken the vibration. When the vibration on the ground is transmitted to the top rod 221 through the bottom rod 222, the bottom rod 222 contacts the rubber shock-absorbing pad. The rubber shock-absorbing pad is deformed by the impact of the plug rod, and its elastic potential energy increases, absorbing the energy of the vibration and weakening the vibration transmitted to the top rod 221. When the rubber shock-absorbing pad is impacted by the vibration peak, its elastic potential energy increases, absorbing the energy of the vibration and weakening the vibration peak transmitted to the top rod 221. When the rubber shock-absorbing pad is impacted by the trough, the rubber shock-absorbing pad releases its stored elastic potential energy, reduces the vibration trough of the top rod 221, and improves the stability of the top rod 221 and the stabilizing ring 3.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Anti-interference level gauge for construction engineering, characterized in that: include: Level body (1); A tripod, comprising a support ring (21) and support rods (22) hinged to the support ring (21); at least three support rods (22) are provided; and the support rods (22) are evenly distributed along the circumference of the support ring (21); and The anti-interference mechanism is arranged on the tripod; the anti-interference mechanism comprises: A stabilizing ring (3) rotatably connected to the supporting ring (21); The stabilizing ring (3) is arranged horizontally, and the rotation axis of the stabilizing ring (3) is arranged along the diameter of the stabilizing ring (3); a stabilizing disk (4) rotatably connected to the stabilizing ring (3); the stabilizing disk (4) is arranged horizontally, and the rotation axis of the stabilizing ring (3) is arranged along the diameter of the stabilizing disk (4); the stabilizing disk (4), the stabilizing ring (3) and the supporting ring (21) are arranged coaxially; and the level body (1) is arranged on the stabilizing disk (4); and A counterweight block (5) is arranged on the lower side of the stabilizing plate (4); the center of gravity of the counterweight block (5) coincides with the axis of the stabilizing plate (4).

2. The anti-interference level meter for construction engineering as claimed in claim 1, characterized in that: Two first rotating shafts (31) are provided on the outer side surface of the stabilizing ring (3); the two first rotating shafts (31) are respectively arranged at two ends of a diameter of the stabilizing ring (3); two first mounting holes (211) are provided on the inner wall of the supporting ring (21); the two first mounting holes (211) respectively correspond to the two first rotating shafts (31), and the two first rotating shafts (31) are respectively arranged in the two first mounting holes (211).

3. The anti-interference level meter for construction engineering as claimed in claim 2, characterized in that: Two second rotating shafts (41) are provided on the side surface of the stabilizing disk (4), and the two second rotating shafts (41) are respectively arranged at two ends of a diameter of the stabilizing disk (4); two second mounting holes (32) are opened on the inner wall of the stabilizing ring (3), and the two second mounting holes (32) correspond to the two second rotating shafts (41) respectively, and the two second rotating shafts (41) are respectively arranged in the two second mounting holes (32); the second rotating shaft (41) and the first rotating shaft (31) are not colinear.

4. The anti-interference level meter for construction engineering as claimed in claim 3, characterized in that: The first rotating shaft (31) is perpendicular to the second rotating shaft (41).

5. The anti-interference level meter for construction engineering as claimed in claim 3, characterized in that: It also includes a locking bolt (6) arranged on the support ring (21); a threaded hole (212) is provided on the support ring (21), and a through hole (33) is provided on the stabilizing ring (3); the locking bolt (6) is arranged in the threaded hole (212), can pass through the through hole (33) and abut against the side surface of the stabilizing disk (4).

6. The anti-interference level meter for construction engineering as claimed in claim 5, characterized in that: The locking bolt (6) is staggered with the first rotating shaft (31) and the second rotating shaft (41).

7. The anti-interference level meter for construction engineering as claimed in claim 1, characterized in that: The counterweight (5) is provided with a mounting groove (51) inside; a motor (7) and a turntable (8) are provided in the mounting groove (51); a power output shaft of the motor (7) is connected to a rotating shaft of the turntable (8), and the rotating shaft of the turntable (8) coincides with the center of gravity of the counterweight (5).

8. The anti-interference level meter for construction engineering as claimed in claim 1, characterized in that: The support rod (22) comprises: A top rod (221), the top of which is hinged on the support rod (22); A bottom rod (222) slidably connected to the top rod (221); and A vibration reduction assembly (9) is arranged between the top rod (221) and the bottom rod (222).

9. The anti-interference level meter for construction engineering as claimed in claim 8, characterized in that: A slide groove is provided at the bottom of the top rod (221), the top of the bottom rod (222) is inserted into the slide groove, and the vibration reduction assembly (9) is arranged in the slide groove.

10. The anti-interference level meter for construction engineering as claimed in claim 8, characterized in that: A protective cover (10) is provided at the junction of the top rod (221) and the bottom rod (222), and the protective cover (10) is slidably matched with the top rod (221) or the bottom rod (222).

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