A PLC-based seismometer automatic north-seeking protection system

Abstract

The invention discloses a PLC-based seismometer automatic north-seeking protection system, including a circular box cover, a box cover locking mechanism, a box body, a centering drive mechanism, a control box, a bottom plate, a disc, a rotating drive mechanism, a seismometer, a laser rangefinder, and a rangefinder block. The seismometer automatic north-seeking protection system controls the laser rangefinder and the rotating drive motor through a PLC controller, and can remotely realize the automatic north-seeking function of the seismometer without the need for on-site manual calibration, saving time and effort; if the seismometer deviates from the center of the disc after a strong earthquake, the PLC controller promptly controls the centering drive mechanism and the rotating drive mechanism to perform centering and returning north-seeking, preventing the seismometer from leaning against the wall and affecting earthquake observation; the interior of the box body is relatively compact, and because the circular box cover can be opened for operation, the seismometer can also be maintained after experiencing a strong earthquake, without the risk of overturning and damage.

Description

Technical Field

[0001] The invention relates to a seismometer protection system, in particular to a PLC-based seismometer automatic north-seeking protection system. Background Art

[0002] When earthquake observation encounters strong local earthquakes or moderate earthquakes, seismometers often suffer serious damage or even fall to the ground. For example, in the epicenter of the 2008 Wenchuan earthquake, almost all earthquake observation equipment was paralyzed. Even if it remains standing, the azimuth will be generated due to the rotation of the seismometer. At present, most seismometer protection uses a protective cover that simply covers the seismometer, which only has a certain insulation effect and a single function. Existing seismometer protection does not have the function of remote monitoring of the seismometer azimuth and automatic north search. Summary of the invention

[0003] Purpose of the invention: To provide a PLC-based seismometer automatic north-seeking protection system, which can realize the automatic north-seeking function of the seismometer after the seismometer experiences an azimuth deviation caused by a local strong earthquake or a moderately strong earthquake.

[0004] Technical solution: The present invention creates the PLC-based seismometer automatic north-seeking protection system, which includes a circular box cover, a box cover locking mechanism, a box body, a centering drive mechanism, a control box, a bottom plate, a disc, a rotating drive mechanism, a seismometer, a laser rangefinder and a rangefinder block;

[0005] The box body is a circular cylindrical structure, and the vertical cover is arranged on the bottom plate; a circular window is arranged on the top of the box body; a circular boss is arranged on the lower side of the circular box cover; a box cover locking mechanism is installed on the upper side of the circular box cover, which is used to snap the circular box cover to the top of the box body, and the circular boss is embedded in the circular window; a circular groove is arranged on the upper side of the bottom plate; a disc is rotatably installed in the circular groove, and the lower side of the disc is close to the bottom of the circular groove; a laser rangefinder is arranged on the side of the seismometer; a rotation drive mechanism is installed at the edge of the bottom plate, which is used to drive the disc to rotate; the seismometer is placed on the disc The center of the side surface; the centering drive mechanism is suspended at the center of the circular boss, and is used to center the seismometer to the center of the disc; the distance measuring block is arranged at the due north position on the inner side surface of the box body, and a positioning hole pointing to the due north direction is provided on the distance measuring block, which is used for the laser rangefinder to inject the laser; the control box is installed on the outer side surface of the box body; a PLC controller and a wireless communication module are arranged in the control box; the PLC controller is electrically connected to the wireless communication module, the laser rangefinder and the seismometer respectively; the box cover locking mechanism, the centering drive mechanism and the rotation drive mechanism are all driven by the PLC controller.

[0006] Further, the rotary drive mechanism includes a rotary drive motor, a rotary drive worm, a rotary drive worm wheel and a motor mounting seat;

[0007] One side of the motor mounting seat is fixed on the edge of the base plate, and the other side extends to the top of the circular groove; the rotary drive worm is rotatably mounted on the motor mounting seat, and the output shaft end of the rotary drive motor is connected to the end of the rotary drive worm; a gear shaft is vertically rotatably mounted on the suspended side of the motor mounting seat; the rotary drive worm wheel is mounted on the upper end of the gear shaft and meshes with the rotary drive worm; a disc drive gear is mounted on the lower end of the gear shaft; gear teeth meshing with the disc drive gear are arranged on the circumferential side of the disc; a rotary drive circuit electrically connected to the PLC controller is arranged in the control box, the rotary drive circuit is electrically connected to the rotary drive motor, and the PLC controller drives the rotary drive motor to rotate forward and reverse through the rotary drive circuit.

[0008] Furthermore, the box cover locking mechanism includes a box cover control box, two telescopic rods, two limit seats, a lock motor worm gear, a lock motor gear, a lock motor, a lock motor worm and two guide strips;

[0009] The box cover control box is installed at the center of the upper side of the circular box cover, and a gripping groove 2 is provided on the front and rear sides of the box cover control box 1; the lock motor worm is rotatably installed on the lower side of the inside of the box cover control box, and the end of the lock motor output shaft is connected to the end of the lock motor worm; the lock motor worm wheel and the lock motor gear are coaxially rotatably installed in the box cover control box; the lock motor worm wheel is meshed with the lock motor worm; one end of the two telescopic rods passes through the left and right sides of the box cover control box respectively and then extends into the inside of the box cover control box; the extension ends of the two telescopic rods are provided with drive racks meshing with the lock motor gear; the two guide strips are transversely Fixed on the front and rear inner sides of the box cover control box; a guide groove that slides with the guide strip is provided on the extension end of the telescopic rod; two lock seats for locking the ends of the two telescopic rods are provided at the edge of the upper end of the box body; a lock hole is provided on the opposite sides of the two lock seats; two limit seats are fixed on the upper side of the circular box cover; the other ends of the two telescopic rods respectively penetrate the two limit seats and extend into the lock holes on the corresponding sides; a box cover locking drive circuit electrically connected to the PLC controller is provided in the control box, and the box cover locking drive circuit is electrically connected to the lock motor, and the PLC controller drives the lock motor to rotate through the locking drive circuit. A wiring hole is provided on the side of the box body near the control box, and the cable for electrically connecting the PLC controller with the internal mechanism of the box body passes through.

[0010] Furthermore, the box cover locking mechanism also includes an RFID card reader; the RFID card reader is installed on the outer side of the control box and is electrically connected to the PLC controller.

[0011] Furthermore, strip-shaped holes are opened on the sides of the two telescopic rods; a positioning pin penetrating the strip-shaped hole is installed on the limit seat, and the positioning pin is slidably matched with the strip-shaped hole.

[0012] Further, the centering drive mechanism includes a centering motor, four connecting suspension rods, a cross-shaped suspension arm, four screw rods and four centering push rods;

[0013] The central motor is installed at the center of the circular boss, and the output shaft of the central motor is vertically downward; the cross-shaped suspension arm is suspended below the circular boss through four connecting suspension rods, and the four ends of the cross-shaped suspension arm are at the same height; a round hole is provided at the center of the cross-shaped suspension arm, and long holes are vertically provided on the four suspension arms of the cross-shaped suspension arm; the screw rod is rotatably installed in the long hole, and one end of the screw rod extends into the round hole; a driven bevel gear is installed on the extending end of each of the four screw rods; a synchronous gear is installed at the lower end of the output shaft of the central motor. An active bevel gear meshing with four driven bevel gears; a threaded hole is arranged at the upper end of each of the four center push rods; the four center push rods are respectively installed on the four lead screws by threaded engagement through the threaded holes; slide grooves are arranged on the two long side surfaces of the long strip hole; a slider slidably installed in the slide groove is arranged at the upper end of each of the four center push rods; a centering drive circuit electrically connected to the PLC controller is arranged in the control box, the centering drive circuit is electrically connected to the centering motor, and the PLC controller drives the centering motor to rotate through the centering drive circuit.

[0014] Furthermore, a short shaft is vertically installed at the center of the circular groove; a bearing mounting hole is provided on the lower side of the disc; a bearing is fitted in the bearing mounting hole; and the inner ring of the bearing is installed with an interference fit with the upper half of the short shaft.

[0015] Furthermore, a mounting flange is provided on the lower edge of the outer side surface of the box body.

[0016] Furthermore, rubber pads are provided on the clamping surfaces at the lower ends of the four center push rods.

[0017] Furthermore, a heat-insulating layer is respectively arranged on the inner side surface of the box body and on the circular boss.

[0018] Compared with the prior art, the invention has the following beneficial effects: the laser rangefinder and the rotary drive motor are comprehensively controlled by the PLC controller, so that the automatic north-seeking function of the seismometer can be realized remotely, without the need for on-site manual calibration, thus saving time and effort; if the seismometer deviates from the center of the disk after a strong earthquake, the PLC controller promptly controls the centering drive mechanism and the rotary drive mechanism to perform centering and north-seeking, thus preventing the seismometer from leaning against the wall and affecting earthquake observation; the interior of the box is relatively compact, and because the circular box cover can be opened for operation, the seismometer can also be maintained after a strong earthquake without the risk of overturning and damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Internal structure diagram created for the present invention;

[0020] Figure 2A top view of the cross-shaped boom created by the present invention;

[0021] Figure 3 The internal structure diagram of the box cover control box created by the present invention;

[0022] Figure 4 Schematic diagram of the circuit structure created by the present invention. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below with reference to the accompanying drawings, but the protection scope of the present invention is not limited to the embodiments.

[0024] like Figure 1-4 As shown, the PLC-based seismometer automatic north-seeking protection system disclosed in the invention comprises: a circular box cover 9, a box cover locking mechanism, a box body 10, a centering drive mechanism, a control box 23, a bottom plate 37, a disk 35, a rotation drive mechanism, a seismometer 34, a laser rangefinder 31 and a rangefinder block 22;

[0025] The box body 10 is a circular cylindrical structure, and the vertical cover is arranged on the bottom plate 37; a circular window 12 is arranged on the top of the box body 10; the lower side of the circular box cover 9 is arranged as a circular boss; the box cover locking mechanism is installed on the upper side of the circular box cover 9, which is used to snap the circular box cover 9 to the top of the box body 10, and the circular boss is embedded in the circular window 12; a circular groove 36 is arranged on the upper side of the bottom plate 37; the disc 35 is rotatably installed in the circular groove 36, and the lower side of the disc 35 is close to the bottom of the circular groove 36; the laser rangefinder 31 is arranged on the side of the seismometer 34; the rotation drive mechanism is installed at the edge of the bottom plate 37, which is used to drive the disc 35 to rotate; the seismometer 34 is placed The housing 10 is provided with a centering drive mechanism, which is suspended at the center of the circular boss and is used to center the seismometer 34 to the center of the disc 35. The distance measuring block 22 is arranged at the due north position on the inner side of the housing 10, and a positioning hole 21 pointing to the due north direction is provided on the distance measuring block 22 for the laser rangefinder 31 to inject the laser. The control box 23 is installed on the outer side of the housing 10. A PLC controller and a wireless communication module are arranged in the control box 23. The PLC controller is electrically connected to the wireless communication module, the laser rangefinder 31 and the seismometer 34 respectively. The cover locking mechanism, the centering drive mechanism and the rotation drive mechanism are all driven by the PLC controller.

[0026] The lower side of the disk 35 is closely attached to the bottom of the circular groove 36, so that the seismic waves can be reliably collected; the PLC controller is used to control the rotary drive mechanism to drive the disk 35 to rotate, and the disk 35 drives the laser rangefinder 31 to find the north. According to the measurement result of the laser rangefinder 31, it is judged whether the ranging laser is accurately shot into the alignment hole 21, so that the automatic north-finding function of the seismometer can be remotely realized; by setting the alignment holes 21 with different apertures, the north-pointing accuracy of the seismometer 34 can be set. When the laser spot emitted by the laser rangefinder 31 completely falls on the bottom of the alignment hole 21, the seismometer 34 accurately points to the north, and the alignment hole 21 is set to the bottom of the alignment hole 21. The aperture of hole 21 can be set according to the size of the laser spot emitted by the laser rangefinder 31; the PLC controller is used to control the centering drive mechanism, so that the seismometer can be automatically centered after the rotation north-seeking fails, so as to perform rotation north-seeking again; the wireless communication module electrically connected to the PLC controller is used to output the data of the seismometer 34 to the remote control center; in actual use, the aperture of the alignment hole 21 is set to be within the range of 2~5mm according to the accuracy requirement of north-seeking, so that the ranging laser of the laser rangefinder 31 can have a high degree of parallelism with the opening direction of the alignment hole 21.

[0027] Further, the rotary drive mechanism includes a rotary drive motor 26, a rotary drive worm 27, a rotary drive worm wheel 30 and a motor mounting seat 28;

[0028] One side of the motor mounting seat 28 is fixed on the edge of the base plate 37, and the other side extends to the top of the circular groove 36; the rotary drive worm 27 is rotatably mounted on the motor mounting seat 28, and the output shaft end of the rotary drive motor 26 is connected to the end of the rotary drive worm 27; a gear shaft 51 is vertically rotatably mounted on the suspended side of the motor mounting seat 28; the rotary drive worm wheel 30 is mounted on the upper end of the gear shaft 51 and meshes with the rotary drive worm 27; a disc drive gear 29 is mounted on the lower end of the gear shaft 51; gear teeth meshing with the disc drive gear 29 are arranged on the circumferential side of the disc 35; a rotary drive circuit electrically connected to the PLC controller is arranged in the control box 23, and the rotary drive circuit is electrically connected to the rotary drive motor 26, and the PLC controller drives the rotary drive motor 26 to rotate forward and reverse through the rotary drive circuit.

[0029] The meshing transmission of the rotary driving worm wheel 30 and the rotary driving worm 27 is utilized to drive the disc driving gear 29 and the gear teeth on the circumferential side of the disc 35 to move, thereby rotating the disc 35. The meshing cooperation between the rotary driving worm wheel 30 and the rotary driving worm 27 has a good positioning effect and rotation adjustment accuracy.

[0030] Furthermore, the box cover locking mechanism includes a box cover control box 1, two telescopic rods 3, two limit seats 4, a lock motor worm gear 48, a lock motor gear 41, a lock motor 44, a lock motor worm 43 and two guide strips 46;

[0031] The box cover control box 1 is installed at the center of the upper side of the circular box cover 9, and a gripping groove 2 is provided on the front and rear sides of the box cover control box 1; the lock motor worm 43 is rotatably installed on the lower side inside the box cover control box 1, and the end of the output shaft of the lock motor 44 is connected to the end of the lock motor worm 43; the lock motor worm wheel 48 and the lock motor gear 41 are coaxially rotatably installed in the box cover control box 1; the lock motor worm wheel 48 is meshed with the lock motor worm 43; one end of the two telescopic rods 3 respectively penetrates the left and right sides of the box cover control box 1 and then extends into the interior of the box cover control box 1; the extending ends of the two telescopic rods 3 are provided with a driving rack 47 meshing with the lock motor gear 41; the two guide bars 46 are It is laterally fixed on the front and rear inner sides of the box cover control box 1; a guide groove 45 that slides with the guide strip 46 is provided on the extending end of the telescopic rod 3; two locking seats 6 for locking the ends of the two telescopic rods 3 are provided at the edge of the upper end of the box body 10; a locking hole 8 is provided on the opposite sides of the two locking seats 6; two limit seats 4 are fixed on the upper side of the circular box cover 9; the other ends of the two telescopic rods 3 respectively penetrate the two limit seats 4 and then extend into the locking holes 8 on the corresponding sides; a box cover locking drive circuit electrically connected to the PLC controller is provided in the control box 23, and the box cover locking drive circuit is electrically connected to the lock motor 44, and the PLC controller drives the lock motor 44 to rotate through the locking drive circuit.

[0032] By utilizing the meshing transmission of the lock motor worm wheel 48 and the lock motor worm 43, the lock motor gear 41 and the drive rack 47 are driven to move, so that the telescopic rod 3 can be telescoped in a small range, thereby cooperating with the two lock seats 6 to achieve locking and unlocking; the limit seat 4 can be used to guide and prevent the telescopic rod 3 from tilting, thereby ensuring the reliability after locking; the sliding cooperation between the guide bar 46 and the guide groove 45 can ensure the stability of the inner end of the telescopic rod 3, so that the lock motor gear 41 and the drive rack 47 are stably meshed; the gripping groove 2 can be used to facilitate the operator to grip after unlocking, so as to quickly open the circular box cover 9.

[0033] Furthermore, the box cover locking mechanism also includes an RFID card reader 24; the RFID card reader 24 is installed on the outer side of the control box 23. By using the RFID card reader 24 to read the operator card information, it can be realized that only the specific operator is allowed to open the box cover locking mechanism.

[0034] Furthermore, the centering drive mechanism includes a centering motor 13, four connecting suspension rods 14, a cross-shaped suspension arm 15, four screw rods 16 and four centering push rods 18;

[0035] The centering motor 13 is installed at the center of the circular boss, and the output shaft of the centering motor 13 is vertically downward; the cross-shaped suspension arm 15 is suspended below the circular boss through four connecting suspension rods 14, and the four ends of the cross-shaped suspension arm 15 are at the same height; a circular hole 49 is provided at the center of the cross-shaped suspension arm 15, and long holes 52 are vertically provided on the four suspension arms of the cross-shaped suspension arm 15; the screw rod 16 is rotatably installed in the long hole 52, and one end of the screw rod 16 extends into the circular hole 49; a driven bevel gear 39 is installed on the extending end of the four screw rods 16; a A driving bevel gear 40 meshing with four driven bevel gears 39 at the same time; a threaded hole is provided at the upper end of each of the four centering push rods 18; the four centering push rods 18 are respectively installed on the four lead screws 16 by threaded engagement through the threaded holes; a slide groove 38 is provided on the two long side surfaces of the long hole 52; a slider 17 slidably installed in the slide groove 38 is provided at the upper end of each of the four centering push rods 18; a centering drive circuit electrically connected to the PLC controller is provided in the control box 23, the centering drive circuit is electrically connected to the centering motor 13, and the PLC controller drives the centering motor 13 to rotate through the centering drive circuit.

[0036] By utilizing the threaded transmission between the four screw rods 16 and the four centering push rods 18, the four centering push rods 18 are driven to move horizontally simultaneously along the four screw rods 16, thereby realizing simultaneous centering of the centering drive mechanism in four directions, so that after a strong earthquake displacement, the seismometer 34 can be promptly centered and returned to the center of the disk 35 to ensure the accuracy of north-seeking; the cooperation between the slider 17 and the slide groove 38 can enhance the stability of the movement of the centering push rod 18; the active bevel gear 40 is simultaneously engaged with the four driven bevel gears 39 to ensure the synchronization of the drive and meet the requirements of precise centering.

[0037] Furthermore, a short shaft 32 is vertically installed at the center of the circular groove 36; a bearing installation hole 53 is provided on the lower side of the disc 35; a bearing 33 is installed in the bearing installation hole 53; the inner ring of the bearing 33 is installed in cooperation with the upper part of the short shaft 32. By using the short shaft 32 and the bearing 33, the friction force is reduced when the disc 35 rotates, and the operation is smoother.

[0038] Furthermore, a mounting flange 20 is provided at the lower edge of the outer side of the box body 10. The mounting flange 20 is used to securely mount the box body 10 on the ground.

[0039] Furthermore, rubber pads 19 are provided on the clamping surfaces at the lower ends of the four center push rods 18. The rubber pads 19 are used for elastic buffering to prevent the seismometer 34 from being damaged due to excessive clamping force of the center drive mechanism.

[0040] Furthermore, a heat-insulating layer 11 is provided on the inner side surface of the box body 10 and on the circular boss. The heat-insulating layer 11 is used to keep the seismometer 34 warm.

[0041] Furthermore, the sides of the two telescopic rods 3 are provided with strip holes 5, and the limiting seat 4 is provided with a positioning pin 7 penetrating the strip hole 5, and the positioning pin 7 is slidably matched with the strip hole 5. The sliding match between the positioning pin 7 and the strip hole 5 further limits the movement range of the two telescopic rods 3.

[0042] In the PLC-based seismometer automatic north-seeking protection system provided by the utility model: the PLC controller adopts the existing PLC controller module, such as the Panasonic FPX control module or the Siemens CPU control module, for driving and controlling the box cover locking mechanism, the centering drive mechanism and the rotation drive mechanism; the rotation drive motor 26, the centering motor 13 and the lock motor 44 all adopt the existing stepper motor; the rotation drive circuit, the centering drive circuit and the box cover locking drive circuit all adopt the corresponding stepper motor drive circuit; the wireless communication module adopts the existing wireless communication module, such as the WiFi communication module or the Zigbee wireless communication module, for transmitting the data of the seismometer 34 to the remote control center and receiving the control instructions issued by the remote control center; the RFID card reader 24 adopts the existing RFID card reader for identifying the staff identity card information.

[0043] The utility model provides a PLC-based seismometer automatic north-seeking protection system. When in use, the PLC controller controls the rotating drive mechanism to rotate the disc 35 to drive the seismometer 34 to rotate, so that the laser spot of the laser rangefinder 31 on the seismometer 34 completely falls into the bottom of the alignment hole 21 on the distance measuring block 22, thereby realizing the remote automatic north-seeking function of the seismometer. When judging whether the laser spot falls into the bottom, it is only necessary to judge whether the measurement data of the laser rangefinder 31 has a sudden change, that is, whether the changed value is the hole depth of the alignment hole 21. If so, it indicates that the north-seeking alignment is successful.

[0044] When returning to the center, after a strong earthquake, the seismometer 34 may deviate from the center to a large extent, and may not succeed after rotating to find the north. If the north search fails after two 360° rotations, the center adjustment is started, and the PLC controller controls the centering drive mechanism to make the output shaft of the centering motor 13 move to drive the four screw rods 16 to rotate, so that the four centering push rods 18 move toward the center at the same time, thereby realizing the simultaneous return of the seismometer 34 in four directions;

[0045] If the circular box cover 9 needs to be opened, the operator's card information must be read by the RFID card reader 24 to determine whether the operator is allowed to open the box cover locking mechanism; if allowed, the operator can control the box cover locking mechanism to open through the PLC controller; after the box cover locking mechanism is opened, the circular box cover 9 and the centering drive mechanism can be taken out from the circular window 12;

[0046] After each seismic wave is detected, the PLC controller automatically controls the centering drive mechanism to center the seismometer 34, and the PLC controller controls the rotating drive mechanism to find the north again; in addition, the control personnel can also issue instructions to the PLC controller through the remote control center to control the centering drive mechanism to center and the rotating drive mechanism to find the north.

[0047] As mentioned above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be interpreted as limiting the invention itself. Various changes can be made to it in form and detail without departing from the spirit and scope of the invention defined in the appended claims.

Claims

1. A PLC-based seismometer automatic north-seeking protection system, characterized by: It comprises a circular box cover (9), a box cover locking mechanism, a box body (10), a centering drive mechanism, a control box (23), a bottom plate (37), a disk (35), a rotation drive mechanism, a seismometer (34), a laser rangefinder (31) and a rangefinder block (22); The box body (10) is a circular cylindrical structure, and the vertical cover is arranged on the bottom plate (37); a circular window (12) is arranged on the top of the box body (10); the lower side of the circular box cover (9) is arranged as a circular boss; a box cover locking mechanism is installed on the upper side of the circular box cover (9) for buckling the circular box cover (9) to the top of the box body (10), and the circular boss is embedded in the circular window (12); a circular groove (36) is arranged on the upper side of the bottom plate (37); a circular disc (35) is rotatably installed in the circular groove (36), and the lower side of the circular disc (35) is closely attached to the bottom of the circular groove (36); a laser rangefinder (31) is arranged on the side of the seismometer (34); a rotation drive mechanism is installed at the edge of the bottom plate (37) for driving the circular disc (35) to rotate; The seismometer (34) is placed at the center of the upper side of the disk (35); the centering drive mechanism is suspended at the center of the circular boss and is used to center the seismometer (34) to the center of the disk (35); the distance measuring block (22) is arranged at the due north position of the inner side of the box body (10), and a positioning hole (21) pointing to the due north direction is provided on the distance measuring block (22) for the laser of the laser rangefinder (31) to be injected; the control box (23) is installed on the outer side of the box body (10); a PLC controller and a wireless communication module are provided in the control box (23); the PLC controller is electrically connected to the wireless communication module, the laser rangefinder (31) and the seismometer (34) respectively; the box cover locking mechanism, the centering drive mechanism and the rotation drive mechanism are all driven and controlled by the PLC controller; The rotary drive mechanism comprises a rotary drive motor (26), a rotary drive worm (27), a rotary drive worm wheel (30) and a motor mounting seat (28); One side of the motor mounting seat (28) is fixed to the edge of the bottom plate (37), and the other side extends to the top of the circular groove (36); the rotary drive worm (27) is rotatably mounted on the motor mounting seat (28), and the end of the output shaft of the rotary drive motor (26) is connected to the end of the rotary drive worm (27); a gear shaft (51) is vertically rotatably mounted on the suspended side of the motor mounting seat (28); the rotary drive worm wheel (30) is mounted on the upper end of the gear shaft (51) and meshes with the rotary drive worm (27); a disc drive gear (29) is mounted on the lower end of the gear shaft (51); gear teeth meshing with the disc drive gear (29) are arranged on the circumferential side of the disc (35); a rotary drive circuit electrically connected to the PLC controller is arranged in the control box (23), the rotary drive circuit is electrically connected to the rotary drive motor (26), and the PLC controller drives the rotary drive motor (26) to rotate forward and reverse through the rotary drive circuit; The box cover locking mechanism comprises a box cover control box (1), two telescopic rods (3), two limit seats (4), a lock motor worm wheel (48), a lock motor gear (41), a lock motor (44), a lock motor worm (43) and two guide strips (46); The box cover control box (1) is mounted at the center of the upper side of the circular box cover (9); the lock motor worm (43) is rotatably mounted on the lower side of the box cover control box (1), and the end of the output shaft of the lock motor (44) is connected to the end of the lock motor worm (43); the lock motor worm wheel (48) and the lock motor gear (41) are coaxially rotatably mounted in the box cover control box (1); the lock motor worm wheel (48) and the lock motor worm (43) are meshed; one end of the two telescopic rods (3) respectively penetrates the left and right sides of the box cover control box (1) and then extends into the inside of the box cover control box (1); the extension ends of the two telescopic rods (3) are both provided with a driving rack (47) meshed with the lock motor gear (41); the two guide bars (46) are both transversely fixed to the box cover control box ( 1); a guide groove (45) slidably matched with the guide strip (46) is provided on the extension end of the telescopic rod (3); two lock seats (6) for locking the ends of the two telescopic rods (3) are provided at the edge of the upper end of the box body (10); a lock hole (8) is provided on the opposite sides of the two lock seats (6); two limit seats (4) are fixed on the upper side of the circular box cover (9); the other ends of the two telescopic rods (3) respectively penetrate the two limit seats (4) and then extend into the lock holes (8) on the corresponding sides; a box cover locking drive circuit electrically connected to the PLC controller is provided in the control box (23); the box cover locking drive circuit is electrically connected to the lock motor (44), and the PLC controller drives the lock motor (44) to rotate through the locking drive circuit; The centering drive mechanism comprises a centering motor (13), four connecting suspension rods (14), a cross-shaped suspension arm (15), four screw rods (16) and four centering push rods (18); The centering motor (13) is installed at the center of the circular boss, and the output shaft of the centering motor (13) is vertically downward; the cross-shaped suspension arm (15) is suspended below the circular boss through four connecting suspension rods (14), and the four ends of the cross-shaped suspension arm (15) are at the same height; a circular hole (49) is provided at the center of the cross-shaped suspension arm (15), and long holes (52) are vertically provided on the four suspension arms of the cross-shaped suspension arm (15); the screw rod (16) is rotatably installed in the long hole (52), and one end of the screw rod (16) extends into the circular hole (49); a driven bevel gear (39) is installed on the extending end of each of the four screw rods (16); a gear (39) is installed at the lower end of the output shaft of the centering motor (13); a gear (49) is installed at the lower end of the output shaft of the centering motor (13); a gear (59) is installed at the lower end of the output shaft of the centering motor (13); a gear (59) is installed at the lower end of the output shaft of the centering motor (13); a gear (39) is installed at the lower end of the output shaft of the centering motor (13); a gear (49) is installed at the lower end of the output shaft of the centering motor (13); a gear (3 ... A driving bevel gear (40) is provided which meshes with four driven bevel gears (39) at the same time; a threaded hole is provided at the upper end of each of the four centering push rods (18); the four centering push rods (18) are respectively installed on the four screw rods (16) by threaded engagement through the threaded holes; a slide groove (38) is provided on the two long side surfaces of the long strip hole (52); a slider (17) is provided at the upper end of each of the four centering push rods (18) and is slidably installed in the slide groove (38); a centering drive circuit electrically connected to a PLC controller is provided in the control box (23); the centering drive circuit is electrically connected to a centering motor (13); the PLC controller drives the centering motor (13) to rotate through the centering drive circuit.

2. The PLC-based seismometer automatic north-seeking protection system according to claim 1 is characterized in that: The box cover locking mechanism also includes an RFID card reader (24); the RFID card reader (24) is installed on the outer side of the control box (23) and is electrically connected to the PLC controller.

3. The PLC-based seismometer automatic north-seeking protection system according to claim 1 is characterized in that: The sides of the two telescopic rods (3) are both provided with strip-shaped holes (5); a positioning pin (7) penetrating the strip-shaped hole (5) is installed on the limiting seat (4), and the positioning pin (7) is slidably matched with the strip-shaped hole (5).

4. The PLC-based seismometer automatic north-seeking protection system according to claim 1 is characterized by: A short shaft (32) is vertically mounted at the center of the circular groove (36); a bearing mounting hole (53) is provided on the lower side of the disc (35); a bearing (33) is mounted in the bearing mounting hole (53); and the inner ring of the bearing (33) is mounted in cooperation with the upper part of the short shaft (32).

5. The PLC-based seismometer automatic north-seeking protection system according to claim 1 is characterized in that: A mounting flange (20) is provided at the lower edge of the outer side surface of the box body (10).

6. The PLC-based seismometer automatic north-seeking protection system according to claim 1 is characterized by: Rubber pads (19) are provided on the clamping surfaces at the lower ends of the four center push rods (18).

7. The PLC-based seismometer automatic north-seeking protection system according to claim 1 is characterized by: A heat-insulating layer (11) is provided on the inner side surface of the box body (10) and on the circular boss.

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