CN210105513U

CN210105513U - Intelligent lock and switch structure thereof

Info

Publication number: CN210105513U
Application number: CN201920584633.XU
Authority: CN
Inventors: 刘向农
Original assignee: Shenzhen Hengnuo Iot Technology Co Ltd
Current assignee: Shenzhen Hengnuo Iot Technology Co Ltd
Priority date: 2019-04-25
Filing date: 2019-04-25
Publication date: 2020-02-21
Anticipated expiration: 2029-04-25

Abstract

The utility model discloses an intelligent lock and a switch structure thereof in the technical field of intelligent locks, wherein the intelligent lock comprises a shell and the switch structure; in the switch structure, be equipped with on the mounting panel and rotate the groove, the separation and reunion gear box is on the separation and reunion axle, and the separation and reunion axle box rotates the inslot and rotates along rotating the groove, and separation and reunion gear is connected with the drive gear meshing, and when the separation and reunion axle rotated the left and right sides that rotates the groove, separation and reunion gear was connected with excessive gear meshing, and excessive gear carries out the open/close lock through the drive lock body of fixed lock knob subassembly. The utility model can be accurately controlled in the closing operation, and the intelligent lock is not easy to damage; the whole structure has few parts and compact connection, saves the space occupied by the driving part, and is convenient for the assembly and the switch operation of the intelligent lock.

Description

Intelligent lock and switch structure thereof

Technical Field

The utility model relates to an intelligence lock technical field, specific theory relates to an intelligence lock and switch structure thereof.

Background

Along with the improvement of the living standard of people, the application of the intelligent lock is more and more popularized, and the existing intelligent lock realizes various lock opening and closing modes such as key passwords, fingerprint identification, remote control and the like. The intelligent lock is different from a traditional key mechanical unlocking mode, a specific driving device needs to be assembled inside the intelligent lock, and the door lock is driven to be opened and closed through the driving device. Traditional drive arrangement is mostly separation and reunion actuating mechanism, and the process of opening and shutting through clutch realizes being connected and breaking off between drive arrangement and the lock, and then realizes the electric switch lock.

In current intelligent lock, clutch mostly is the foraminiferous worm gear device of motor and carries out the separation and reunion operation, and the worm gear device is difficult for accurate control at the drive in-process, and the excessive rotation of worm gear can lead to clutch to damage, influences whole clutch and even the life of whole intelligent lock, and its rotation is not in place then can not play the function of switch lock control. In addition, the overall structure of the worm gear and worm device is complex and large in size, the installation space of the lock body and the driving assembly of the lock body in the door lock is limited, and the large intelligent lock is inconvenient to install and use.

The above-mentioned drawbacks are worth solving.

Disclosure of Invention

In order to overcome the deficiencies of the prior art, the utility model provides an intelligence lock and switch structure thereof.

The utility model discloses technical scheme as follows:

on one hand, the switch structure of the intelligent lock comprises a switch component and a PCB board, wherein the PCB board is connected with a power supply, and the switch structure is characterized in that the switch component comprises a support plate, a transmission component and a fixed lock knob component for driving a lock body to rotate, the support plate is provided with a circular arc-shaped rotating groove,

the transmission assembly comprises a motor, a clutch arm and a transition gear, the clutch arm comprises a clutch gear, a clutch transmission arm and a clutch shaft, the clutch gear is sleeved on the clutch shaft, the clutch shaft is sleeved in the rotating groove, the clutch gear is meshed with a transmission gear, the transmission gear is connected with the motor through a transmission shaft, the motor sequentially drives the transmission gear and the clutch gear to rotate, and then the clutch gear drives the clutch shaft to rotate along the rotating groove;

when the clutch shaft rotates to the left side and the right side of the rotating groove, the clutch gear is meshed with the transition gear, and the transition gear drives the lock body to open/close the lock through the fixed lock knob assembly.

According to above-mentioned scheme the utility model discloses, a serial communication port, the separation and reunion arm still includes the spring, the spring housing is in on the separation and reunion axle, its upper end with separation and reunion gear fixed connection.

According to above scheme the utility model discloses, a serial communication port, be equipped with MCU, first inductive switch and second inductive switch on the PCB board: the first inductive switch is connected with the MCU, and when the clutch arm rotates to the first inductive switch, an inductive shifting block of the first inductive switch is contacted with a clutch arm counting tooth on the clutch transmission arm; the second inductive switch is connected with the MCU, a plurality of transition gear counting teeth are arranged on the transition gear, and the transition gear rotates to enable the second inductive switch to be in contact with the transition gear counting teeth.

According to the above scheme the utility model discloses, a serial communication port, be equipped with the stopper on the mounting panel, the stopper is located rotate between two ends about the groove, just the stopper is located drive gear with between the excessive gear, the separation and reunion arm rotates during the both ends of rotating about the groove, the separation and reunion drive arm with stopper spacing connection.

According to above scheme the utility model discloses, its characterized in that, the upside of mounting panel is equipped with the closing cap, the PCB board is fixed the closing cap upside.

According to above-mentioned scheme the utility model discloses, a serial communication port, the fixed lock knob subassembly includes drive gear, drive shaft and knob, drive gear with excessive gear engagement connects, drive gear passes through the drive shaft with the knob is connected, the knob with lock body fixed connection.

Furthermore, the side of drive shaft is equipped with spacing side cut, the drive shaft pass through spacing side cut with drive gear is spacing to be connected.

Furthermore, the top end of the driving shaft is fixedly connected with the knob handle.

Furthermore, the knob handle is fixed on the knob fixing plate, the lower end of the knob fixing plate is fixedly connected with the knob transmission plate, a flat limiting hole is formed in the knob transmission plate, and a limiting strip corresponding to the limiting hole is arranged at the top end of the driving shaft.

Furthermore, a buffer pad is arranged between the knob fixing plate and the knob transmission plate.

Furthermore, the fixed lock knob component also comprises a rotating shaft upper piece, a rotating shaft middle piece and a rotating shaft lower cover, the top end of the driving shaft is fixedly connected with the rotating shaft upper piece, the rotating shaft upper piece is provided with two strip-shaped upper piece sliding holes, the rotating shaft lower cover is provided with two strip-shaped lower cover sliding holes,

two middle piece upper sliding points are arranged on the upper side of the middle piece of the rotating shaft, and the middle piece upper sliding points are sleeved in the upper piece sliding holes and slide along the upper piece sliding holes; two middle piece lower sliding points are arranged on the lower side of the middle piece of the rotating shaft, and the middle piece lower sliding points are sleeved in the lower cover sliding holes and slide along the lower cover sliding holes.

Furthermore, the connecting line of the sliding points on the two middle pieces is perpendicular to the connecting line of the sliding points on the two middle pieces.

Furthermore, a limiting strip at the top end of the driving shaft is in limiting connection with an upper piece middle hole in the center of the upper piece of the rotating shaft.

Furthermore, the lower cover of the rotating shaft is in limit connection with the knob fixing cover, and the knob is sleeved on the inner side of the knob fixing cover through a soft rubber sleeve.

In another aspect, the intelligent lock is characterized by comprising a shell and the switch structure of the intelligent lock.

According to above scheme the utility model discloses, a serial communication port, the shell includes face-piece, limit shell, first drain pan and second drain pan, the limit shell cover is in the periphery of face-piece, first drain pan cover is in the outside of fixed lock knob subassembly, the second drain pan cover is in the motor with the outside of transmission shaft.

Furthermore, a fixed bottom plate is arranged at the bottom of the second bottom shell, and a fixed bottom frame is arranged at the lower end of the fixed bottom plate.

Furthermore, a key is arranged on the face shell, the lower end of the key is in contact connection with the key board, and the lower end of the key board is in contact connection with a key component on the PCB.

According to the above scheme the utility model discloses, its beneficial effect lies in:

the utility model realizes the clutch process of the driving part and the switch lock control part through the rotation of the clutch arm, the clutch arm can be connected only when being shifted to the end, and the middle part is in a disconnection state, the on-off operation can be accurately controlled, the accuracy of the switch lock operation is ensured, the intelligent lock is not easy to damage, and the service life of the intelligent lock is ensured;

the clutch process can be realized only by mutually matching the transmission gear, the clutch gear, the transition gear and the driving gear in the operation process of the switch lock, the whole structure has fewer parts and compact connection, the space occupied by the driving part is saved, and the assembly and the switch operation of the intelligent lock are convenient;

the utility model realizes the detection of the clutch position through the first inductive switch and the second inductive switch, and ensures that the control of the clutch arm is more accurate; the utility model discloses a control process is simple, the reaction is sensitive, and the control process of the switch lock of being convenient for realizes.

Drawings

Fig. 1 is the structure schematic diagram of the intelligent lock of the present invention.

Fig. 2 is an exploded view of the intelligent lock of the present invention.

Fig. 3 is an exploded view of the middle intelligent lock of the present invention.

Fig. 4 is a schematic diagram of the switch assembly with the cover removed according to the present invention.

Fig. 5 is a bottom view of the clutch arm of the present invention.

Fig. 6 is a side view of the clutch arm of the present invention.

Fig. 7 to 9 are connection structure diagrams of the clutch arm in different positions according to the present invention.

Fig. 10 is an exploded view of the knob assembly of the present invention.

Fig. 11 is an enlarged view of a portion of the box in fig. 10.

Fig. 12 is a top view of the knob assembly of the present invention.

Fig. 13 is a bottom view of the knob assembly of the middle fixing lock of the present invention.

Fig. 14 is a flow chart of the present invention.

In the figure, 110, a face-piece; 120. a side shell; 130. a first bottom case; 140. a second bottom case; 141. fixing the bottom plate; 142. fixing the underframe;

200. a switch assembly; 210. sealing the cover; 220. a mounting plate; 221. a rotating groove; 222. a limiting block;

231. a drive shaft; 2311. a transmission gear; 232. a clutch arm; 2321. a clutch gear; 2322. a clutch transmission arm; 2323. a clutch shaft; 2324. a spring; 2325. the clutch arm counts the tooth; 233. a transition gear; 2331. transition gear count teeth;

2411. a knob handle; 2412. a knob fixing plate; 2413. a cushion pad; 2414. a knob transmission plate; 242. a drive shaft; 2421. a limiting strip; 2422. limiting and trimming; 243. a drive gear; 244. the rotating shaft is mounted; 2441. a hole is arranged in the upper sheet; 2442. a slide hole of the upper plate; 245. a rotating shaft middle plate; 2451. sliding points on the middle piece; 2452. a middle piece lower sliding point; 246. a lower cover of the rotating shaft; 2461. a lower cover slide hole; 247. a knob fixing cover; 248. a soft rubber sleeve; 249. a knob;

300. a PCB board; 310. a key sheet; 311. pressing a key; 321. a first inductive switch; 322. and a second inductive switch.

Detailed Description

The invention is further described with reference to the following figures and embodiments:

as shown in fig. 1, 2 and 3, the intelligent lock comprises a housing and a switch structure of the intelligent lock, wherein the switch structure of the intelligent lock comprises a clutch driving part and a door lock control part (i.e. a fixed lock knob assembly).

The outer case includes a face case 110, a side case 120, a first bottom case 130, and a second bottom case 140. The front shell 110 is provided with a key 311, the lower end of the key 311 is in contact connection with the key board 310, the lower end of the key board 310 is in contact connection with a key component on the PCB 300, and the key 311 is pressed to sequentially drive the key board 310 and the key component, thereby realizing the key control of the door lock. The side case 120 is fitted over the outer periphery of the face case 110, the first bottom case 130 is fitted over the outer side of the fixed lock knob assembly, and the second bottom case 140 is fitted over the outer side of the clutch driving part (the motor and the driving shaft in the clutch driving part).

The bottom of the second bottom case 140 is provided with a fixing bottom plate 141, the lower end of the fixing bottom plate 141 is provided with a fixing bottom frame 142, a battery pack is arranged in a space enclosed by the fixing bottom plate 141 and the second bottom case 140, and the battery pack supplies power for the switch structure of the intelligent lock.

As shown in fig. 2, 3 and 4, the switch structure of the smart lock includes a switch assembly 200 and a PCB 300, wherein the switch assembly 200 includes a bracket plate 220, a transmission assembly and a fixed lock knob assembly for driving a lock body to rotate.

The PCB 300 is connected to a power source (i.e., a battery pack), and the PCB 300 is fixed between the face case 110 and the switch assembly 200, thereby fixing the PCB 300. Preferably, the upper side of the bracket board 220 is provided with a cover 210, and the PCB 300 is fixed on the upper side of the cover 210.

The transmission assembly comprises a motor, a clutch arm 232 and a transition gear 233, the motor is connected with the transmission gear 2311 through the transmission gear 231, and the clutch arm 232 comprises a clutch gear 2321, a clutch transmission arm 2322 and a clutch shaft 2323. The support plate 220 is provided with a limit block 222 and a circular arc-shaped rotating groove 221, the limit block 222 is positioned between the left end and the right end of the rotating groove 221, the limit block 222 is positioned between the transmission gear 2311 and the transition gear 233, and when the clutch arm 232 rotates to the left end and the right end of the rotating groove 221, the clutch transmission arm 2322 is in limit connection with the limit block 222. Due to the limiting function of the limiting block 222, the clutch transmission arm 2322 is prevented from rotating too much due to continuous movement after moving to the end, and the purpose of protecting the clutch arm 232 is achieved.

As shown in fig. 3 and 4, the PCB 300 is provided with an MCU, a first inductive switch 321 and a second inductive switch 322, wherein:

the first inductive switch 321 is connected with the MCU, and when the clutch arm 232 rotates to the first inductive switch 321, the inductive shifting block of the first inductive switch 321 contacts the clutch arm counting rack 2325 on the clutch transmission arm 2322, so as to detect the "off" state of the clutch arm 232 during the movement process;

the second inductive switch 322 is connected with the MCU, the transition gear 233 is provided with a plurality of transition gear counting teeth 2331, the transition gear 233 rotates to make the second inductive switch 322 contact with the transition gear counting teeth 2331, the detection of the "on" state during the movement of the clutch arm 232 is realized, and the number of rotation turns of the fixed lock knob assembly is detected to achieve the detection of the on/off lock state.

As shown in fig. 5 and 6, the clutch gear 2321 is fitted over the clutch shaft 2323, the clutch shaft 2323 is fitted in the rotation groove 221, and the clutch gear 2321 is engaged with the transmission gear 2311. The motor in turn drives the transmission gear 2311 and the clutch gear 2321 to rotate, and the clutch gear 2321 drives the clutch shaft 2323 to rotate along the rotation slot 221.

The clutch arm 232 further includes a spring 2324, the spring 2324 is sleeved on the clutch shaft 2323, and the upper end thereof is fixedly connected with the clutch gear 2321. The rotation of the clutch arm 232 is controlled by the elastic force of the spring 2324 as the friction force of the clutch gear 2321, so that the operation process of the clutch arm 232 is smoother, and the controllability of the movement distance is enhanced.

When the clutch shaft 2323 rotates to the left and right sides of the rotation groove 221, the clutch gear 2321 is engaged with the transition gear 233, and the transition gear 233 drives the lock body to open/close the lock through the fixed lock knob assembly. In fig. 7, the motor drives the clutch arm 232 to rotate to the left at P1, which drives the transition gear 233 to rotate, thereby controlling the door lock to open/close.

As shown in fig. 7 to 9, the principle of the process of opening/closing the lock by the clutch arm 232 is as follows:

in fig. 7, when the lock is turned on/off, the second inductive switch 322 detects no switching signal, and the motor rotates in the reverse direction until the clutch transmission arm 2322 contacts the first inductive switch 321, and the motor stops, thereby separating the clutch arm 232;

in fig. 8, after the lock is opened/closed, the motor drives the clutch arm 232 to rotate to the right/left direction to P2, the clutch arm counting tooth 2325 contacts the first inductive switch 321, the motor stops working, and the clutch arm 232 is separated, and the lock is opened and closed;

in fig. 9, the motor drives the clutch arm 232 to rotate to the right at P3, which drives the transition gear 233 to rotate to the right, thereby controlling the door lock to open/close.

As shown in fig. 3, 10 and 11, the fixed lock knob assembly includes a driving gear 243, a driving shaft 242 and a knob 249, wherein the driving gear 243 is engaged with the transition gear 233, the driving gear 243 is connected with the knob 249 via the driving shaft 242, and the knob 249 is fixedly connected with the lock body. In the process of connecting the driving gear 243 and the driving shaft 242, the side surface of the driving shaft 242 is provided with a limiting trimming 2422, and the driving shaft 242 is in limiting connection with the driving gear 243 through the limiting trimming 2422, so that synchronous rotation of the driving gear and the driving gear is realized.

Preferably, the top end of the driving shaft 242 is fixedly connected with the knob handle 2411, so that manual unlocking control is realized, and the unlocking mode is more diversified. In this embodiment, the knob handle 2411 is fixed on the knob fixing plate 2412, the lower end of the knob fixing plate 2412 is fixedly connected with the knob transmission plate 2414, the knob transmission plate 2414 is provided with a flat limiting hole, the top end of the driving shaft 242 is provided with a limiting strip 2421 corresponding to the limiting hole, and the driving shaft 242 and the knob rotating plate are synchronously rotated by matching the limiting strip 2421 with the limiting hole, so that the knob handle 2411 is synchronously rotated. A buffer pad 2413 is arranged between the knob fixing plate 2412 and the knob transmission plate 2414, so that abrasion caused by rigid connection between the knob fixing plate 2412 and the knob transmission plate 2414 is avoided.

As shown in fig. 10 and 11, the fixed lock knob assembly further includes a shaft upper plate 244, a shaft middle plate 245, and a shaft lower cover 246.

The top end of the driving shaft 242 is fixedly connected to the rotating shaft upper plate 244, and preferably, the limiting bar 2421 at the top end of the driving shaft 242 is in limiting connection with the upper plate middle hole 2441 at the center of the rotating shaft upper plate 244, so that the driving shaft 242 and the rotating shaft upper plate 244 rotate synchronously.

The upper plate 244 of the rotating shaft is provided with two elongated upper plate sliding holes 2442, and the lower cover 246 of the rotating shaft is provided with two elongated lower cover sliding holes 2461. Two middle piece upper sliding points 2451 are arranged on the upper side of the rotating shaft middle piece 245, and the middle piece upper sliding points 2451 are sleeved in the upper piece sliding holes 2442 and slide along the upper piece sliding holes 2442; two middle piece lower sliding points 2452 are arranged on the lower side of the rotating shaft middle piece 245, and the middle piece lower sliding points 2452 are sleeved in the lower cover sliding holes 2461 and slide along the lower cover sliding holes 2461. The synchronous rotation of the upper rotating shaft 244, the middle rotating hand 245 and the lower rotating shaft cover 246 is realized through the limit rotation of the upper rotating shaft 244 and the middle rotating shaft 245 and the limit rotation of the middle rotating shaft 245 and the lower rotating shaft cover 246.

The rotating shaft lower cover 246 is in limit connection with the knob fixing cover 247, the knob 249 is sleeved on the inner side of the knob fixing cover 247 through the soft rubber sleeve 248, and the rotating operation of the rotating shaft lower cover 246 for controlling the knob 249 is realized through the limit of the rotating shaft lower cover 246 and the knob fixing cover 247, the fixing of the knob fixing cover 247 and the soft rubber sleeve 248 and the fixing of the soft rubber sleeve 248 and the knob 249.

In this embodiment, the inside of the silica gel cover 248 is provided with a wavy soft rubber edge, and the wavy silica gel cover can be adapted to various lock knobs with different shapes and sizes when being installed.

As shown in fig. 12 and 13, in the present embodiment, the line connecting the two middle piece upper sliding points 2451 is perpendicular to the line connecting the two middle piece lower sliding points 2452. When rotating, the middle piece 245/lower cover 246 can move in four directions, i.e. front, back, left and right, so that the driving shaft 242 and the knob 249 can be normally rotated to unlock even if they are not concentric.

As shown in fig. 14, the utility model discloses a realization process of well intelligence lock, including following step:

1. the user performs an open/close lock operation.

The unlocking operation of the user comprises locking/unlocking modes such as pressing down/keying, scanning the two-dimensional code, remote wireless control, biological fingerprint and the like.

2. And the MCU on the PCB reads the initial state of the second inductive switch, sets the timing time of the first timer and the second timer, and controls the motor to rotate forwards or backwards. The timing time of the first timer is greater than that of the second timer, the timing time of the first timer is 10s, and the timing time of the second timer is 800 ms.

The step also comprises a lighting process, and the lamp is turned off after 800 ms.

3. And detecting whether the state of the second inductive switch is changed within the timing time (namely 800 ms) of the second timer, if so, entering the next step, and if not, entering the step 6.

4. An action of opening/closing the lock is performed.

5. And (4) detecting whether the state of the second inductive switch is changed within a fixed time, detecting whether the timing time (10 s) of the first timer is up, entering the next step if the second inductive switch is not changed within the fixed time or the timing time of the first timer is up, and returning to the step (4) if the second inductive switch is changed within the fixed time or the timing time of the first timer is not up.

The fixed time is less than the timing time of the second timer, and the fixed time in this embodiment is 500 ms.

6. The motor rotates in the reverse direction and the third timer is started.

Preferably, the timing time of the third timer is less than the timing time of the first timer and greater than the timing time of the second timer. In this embodiment, the timing time of the third timer is 1 s.

7. The clutch action of the lock is executed.

8. And detecting whether the first inductive switch is changed or not, detecting whether the timing time of the third timer is reached or not, if the first inductive switch is changed or the timing time of the third timer is reached, ending the locking and unlocking process, and if the first inductive switch is not changed or the timing time of the third timer is not reached, returning to the step 7.

The utility model discloses in the realization in-process of switch lock, mutually supporting of three timer to through the state that detects first inductive switch and second inductive switch respectively, realize the detection to switch lock process, the control of switch lock is more accurate, also can realize the protection to intelligent lock simultaneously.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are considered to be within the scope of the invention as defined by the following claims.

The above exemplary description of the present invention is made in conjunction with the accompanying drawings, and it is obvious that the present invention is not limited by the above manner, and various improvements made by the method concept and technical solution of the present invention or by directly applying the concept and technical solution of the present invention to other occasions without improvement are all within the protection scope of the present invention.

Claims

1. A switch structure of an intelligent lock comprises a switch component and a PCB board, wherein the PCB board is connected with a power supply, and the switch structure is characterized in that the switch component comprises a bracket board, a transmission component and a fixed lock knob component for driving a lock body to rotate, the bracket board is provided with a circular arc-shaped rotating groove,

2. The switch structure of claim 1, wherein the clutch arm further comprises a spring, the spring is sleeved on the clutch shaft, and the upper end of the spring is fixedly connected with the clutch gear.

3. The switch structure of claim 1, wherein the PCB board is provided with an MCU, a first inductive switch and a second inductive switch:

the first inductive switch is connected with the MCU, and when the clutch arm rotates to the first inductive switch, an inductive shifting block of the first inductive switch is contacted with a clutch arm counting tooth on the clutch transmission arm;

the second inductive switch is connected with the MCU, a plurality of transition gear counting teeth are arranged on the transition gear, and the transition gear rotates to enable the second inductive switch to be in contact with the transition gear counting teeth.

4. The switch structure of an intelligent lock according to claim 1, wherein a limiting block is arranged on the support plate, the limiting block is positioned between the left end and the right end of the rotating groove, the limiting block is positioned between the transmission gear and the transition gear, and when the clutch arm rotates to the left end and the right end of the rotating groove, the clutch transmission arm is in limiting connection with the limiting block.

5. The switch structure of claim 1, wherein the fixed lock knob assembly comprises a driving gear, a driving shaft and a knob, the driving gear is engaged with the transition gear, the driving gear is connected with the knob through the driving shaft, and the knob is fixedly connected with the lock body.

6. The switch structure of an intelligent lock according to claim 5, wherein the fixed lock knob assembly further comprises an upper rotating shaft piece, a middle rotating shaft piece and a lower rotating shaft cover, the top end of the driving shaft is fixedly connected with the upper rotating shaft piece, the upper rotating shaft piece is provided with two elongated upper piece sliding holes, the lower rotating shaft cover is provided with two elongated lower cover sliding holes,

7. The switch structure of claim 6, wherein a line connecting the sliding points on the two middle plates is perpendicular to a line connecting the sliding points on the two middle plates.

8. An intelligent lock, characterized in that it comprises a housing and a switch structure of the intelligent lock according to any one of claims 1 to 7.

9. The smart lock of claim 8 wherein the housing includes a face shell, a side shell, a first bottom shell, and a second bottom shell, the side shell fitting around a periphery of the face shell, the first bottom shell fitting around an outside of the stationary lock knob assembly, the second bottom shell fitting around an outside of the motor and the drive shaft.

10. The intelligent lock according to claim 9, wherein a fixed bottom plate is arranged at the bottom of the second bottom shell, and a fixed bottom frame is arranged at the lower end of the fixed bottom plate.