497 results about "Limit switch" patented technology

The utility model relates to a mechanical holding relay, which comprises a relay base and an upper cover in buckling connection, a driving motor is arranged in the relay base, and the driving motor is connected with at least two movable contact plates rotating around a shaft through a gear transmission mechanism. One end of the movable contact plate is connected with a conductive sheet arranged on the relay base through a flexible conductive piece, the other end of the movable contact plate is provided with a movable contact, the relay base is also provided with a static sheet, the static sheet is provided with a static contact, and the movable contact is in contact with or separated from the static contact; the beneficial effects are that 1, the driving motor drives the movable contact plate to rotate positively and negatively through the gear transmission mechanism to realize opening and closing of the switch; 2, two stroke limit switches are arranged on the circuit board to control the opening and closing positions, and the control switch can automatically cut off the power supply of the motor after the opening and closing are in place, so that the over-stroke action is avoided;

The application discloses a multifunctional massage bed, which comprises a support, a mounting plate, a massage assembly and a driving mechanism, the mounting plate is arranged below the support, a guide rail is arranged above the support, the massage assembly is movably arranged on the guide rail and can move back and forth along the guide rail to realize massage on a human body, and the driving mechanism comprises a motor, a limit switch, a movable switch and a control panel; the height of different users is set, when the length of the massage assembly exceeds the position of the human body during massage, the motor is stopped or reversed, so that the massage assembly is stopped or reversely moved, the massage assembly can always massage the human body, the massage assembly cannot move away from the human body, the idle running of the massage assembly is avoided, the loss is reduced, the energy is saved, and the cost is saved.

A self-tipping railway car with an automatic unloading detection device, belonging to the field of railway transportation, includes a self-tipping railway car with axle suppression mechanism. The left and right ends of the car's bottom are respectively mounted on the vehicle via a first cylinder and a second cylinder. A solenoid valve is mounted on the vehicle to control the intake and exhaust of the first and second cylinders. A battery box and a power supply box are mounted on the side bolster beams of the vehicle and are electrically connected. A signal transceiver is installed inside the power supply box and is electrically connected to a time relay. The time relay is electrically connected to the solenoid valve, controlling the first stage of the solenoid valve's operation. A first synchronous signal transceiver is installed inside the power supply box, and a second synchronous signal transceiver is installed on the end wall of the self-tipping railway car. A limit switch device detects the opening and closing status of the side doors of the self-tipping railway car. This design solves the problem of automatic unloading of the self-tipping railway car with axle suppression mechanism, eliminating the safety hazard of tipping over during the unloading process.

The utility model discloses a yellow phosphorus filling lifting platform which aims at solving the problems that an existing loading platform is not matched with a tank car, and the operation risk of personnel is large. The platform comprises a filling frame and a lifting platform capable of vertically sliding, the filling frame and the lifting platform are connected through a servo electric cylinder, the filling frame is provided with a guide structure, a guardrail and an anti-collision assembly, and the anti-collision assembly is in control connection with the servo electric cylinder. A connecting beam is arranged on the top of the lifting platform, and servo electric cylinders are arranged on the two sides in pairs and connected through connecting rods. A mounting seat of the filling frame is provided with a limiting bearing and a limiting notch. The anti-collision assembly comprises an anti-collision rod and a limiting switch. The platform can adapt to different tank trucks through the lifting platform and the servo electric cylinder, so that people can get on and off the truck conveniently; the operation safety is improved through a guardrail and a lifting function; a servo electric cylinder, a connecting beam and the like guarantee stable lifting; the anti-collision assembly can prevent equipment from being damaged. The existing problems are effectively solved, and the safety and convenience of yellow phosphorus filling operation are improved.

The utility model provides an angle detection limiting device and a movable arm type tower crane. The angle detection limiting device is applied to the movable arm type tower crane and comprises a detection collision block arranged between a buffer connecting rod and a buffer fixing block, the detection collision block is provided with a first end and a second end, and the first end of the detection collision block is rotationally connected with a buffer of the movable arm type tower crane; the limiting switch is fixed to the buffer fixing block and arranged on the moving path of the detection collision block, so that when the distance between the buffer connecting rod and the buffer fixing block is smaller than a preset distance threshold value, the detection collision block makes contact with the limiting switch and triggers the limiting switch, and the limiting switch is used for controlling a luffing mechanism of the movable arm type tower crane to work. According to the scheme, the structure is simple, installation and manufacturing are convenient, and the reliability of the limiting device can be guaranteed.

The utility model relates to a forklift technical field discloses a forklift anti -collision device, including the vehicle body, the vehicle body left end is provided with two cargo fork, the cargo fork left end all is provided with the approach inductive switch, the cargo fork left end all is fixedly connected with two springs, the spring left end is fixedly connected with the anti -collision inductor, the cargo fork top is provided with the tray, the vehicle body left end is provided with two limit switches, the vehicle body left end corresponding limit switch upper side all hinge connection has the anti -collision board. In the utility model, the anti -collision inductor can induct the object inside 0 5m range before the cargo fork and carry out ranging, and the driver is reminded, when the vehicle body still collides to the front shielding object at a certain speed because of the unexpected situation, the anti -collision inductor will touch the approach inductive switch installed in the cargo fork, and the control system of vehicle body is sent to the electric signal from the approach inductive switch, and emergency brake is carried out immediately, avoids the forklift to continue to go on to the collision body and causes the harm continuously.

The utility model relates to the technical field of positioning electric cylinders, in particular to a miniature electric cylinder with a positioning function and suitable for high and low temperatures, which comprises a machine body, a speed reducer is mounted on the inner wall of a cavity, a driving gear is fixedly connected to the outer wall of the speed reducer, a driven gear is meshed with the outer wall of the driving gear, and a bearing is fixedly connected to the outer wall of the driven gear. The outer wall of the bearing is fixedly connected with a main shaft, the top end of the machine body is fixedly provided with a limiting switch, through the limiting switch at the top end of the machine body, the electric cylinder is provided with a positive limiting switch and a negative limiting switch, the movement range of the electric cylinder can be accurately controlled under the DC5V driving voltage, the rated thrust of the electric cylinder reaches 50N, and the thrust requirement in a common working scene can be met; the rated pushing speed of the electric cylinder is stable 4 mm / s, the stability of linear motion is ensured, the effective stroke is set to be 20 mm, displacement control is more accurate, in addition, the electric cylinder can bear radial force as high as 20 N, and therefore the structural stability and reliability in the running process are ensured.

The present invention provides a limit switch head processing device, comprising a lifting processing table, a suspended top plate assembly located above the lifting processing table, and a hole and groove processing mechanism located on a side surface and / or top surface of a lifting platform. The lifting processing table comprises a positioning platform, an upper surface of the positioning platform is provided with positioning columns adapted to bottom holes and grooves of a workpiece to be machined, and the workpiece to be machined is circumferentially positioned. The lifting processing table further comprises a lifting driving mechanism for driving the positioning platform to rise and fall in the vertical direction. The driving mechanism is a lifting cylinder, and a free end of a piston of the lifting cylinder is fixedly connected to a bottom surface of the positioning platform. The limit switch head processing device in the present invention skillfully uses existing holes and grooves of the workpiece to be machined, and performs accurate positioning by means of the cooperation of the lifting platform and the suspended top plate assembly, thereby preventing deviation from occurring during a clamping process of an existing clamping tool, improving the reliability of positioning, and improving the accuracy of machining.

The utility model relates to the technical field of agricultural automation, and discloses a greenhouse cotton quilt limiter which comprises an equipment box fixed on a rack, and a roller shutter machine is fixedly mounted on the rack; a limiting switch assembly is installed in the equipment box, a supporting shaft is rotationally installed on the outer wall of the equipment box, and the supporting shaft is in direct transmission fit with the limiting switch assembly and is in transmission fit with a rolling pipe of the curtain rolling machine through a transmission mechanism. A controller is installed on the machine frame, and the curtain rolling machine and the limiting switch assembly are both electrically connected with the controller. The limiting switch assembly is installed on the machine frame, meanwhile, the limiting switch assembly is in linkage with rotation of the rolling pipe of the curtain rolling machine through the supporting shaft and the transmission mechanism, finally, the controller controls starting and stopping of the curtain rolling machine, the curtain rolling machine can be effectively prevented from moving out of a greenhouse, and then cotton quilts are prevented from falling off from the greenhouse and the rolling pipe.

The present application relates to a kind of zero return device and numerical control equipment, the numerical control equipment has the zero return device, the zero return device includes zero return combination switch, deceleration block and limit block;Deceleration block, limit block and the position of deceleration switch, extreme speed switch of zero return combination switch are matched, while being partially overlapped in vertical direction, along the parallel arrangement of zero return component operating direction, and deceleration block is located in limit block front end in the direction of facing zero return.The present application, machine tool does not need to consider the position of slide table when zeroing, as long as limit alarm does not appear, it can operate zeroing, machine tool automatically identifies deceleration block, then retreats to find zero point and stops, while setting zero point signal.No additional accessories, such as deceleration switch damage, zeroing failure, machine tool can also normally alarm alarm when pressing limit switch.

This invention discloses a mechanical guide vane master controller, which utilizes a movable wedge-shaped trigger rod to trigger left and right limit switches at the same position, causing each limit switch to output a switching signal. The wedge-shaped trigger rod also moves a travel trigger plate, and magnetic probes at both ends of the travel trigger plate cooperate with corresponding travel sensors to trigger left and right travel sensors to output analog signals. This invention is used for monitoring the travel signals of turbine guide vanes, and can output redundant switching and analog signals, unaffected by weather, location, time, or unit operating conditions, thus offering higher reliability.

This utility model discloses a linear actuator motor with adjustable stroke, relating to the field of motor equipment technology. It includes an actuator box, a lead screw and actuator assembly, a translation adjustment assembly, a limit switch, a screw, and a lead screw nut. In this utility model, the translation adjustment assembly adjusts the position of the limit switch inside the actuator box, thereby adjusting the stroke of the linear actuator motor. The rotation of the screw in the translation adjustment assembly drives the lead screw nut to move linearly along the screw, which in turn drives the limit switch to move linearly along the screw. This allows for position adjustment of the limit switch, and consequently, stroke adjustment of the linear actuator motor. Each rotation of the screw causes the lead screw nut to move the limit switch linearly by one screw pitch. The screw pitch can be selected according to actual needs, effectively ensuring the position adjustment accuracy of the limit switch, and thus ensuring the stroke adjustment accuracy of the linear actuator motor.

The utility model provides a kind of push plate feeding mobile machine with feeding limiting structure, including feeding hopper, the bottom surface of the feeding hopper is fixedly connected with support seat, the side surface of the support seat is fixedly connected with support block, the upper surface of the support block is fixedly installed with electric cylinder, the telescopic end of the electric cylinder is fixedly installed with push plate assembly, the outer surface of the feeding hopper is fixedly connected with two limit slides, involve push plate feeding mobile machine field.The utility model is through the cooperation of limit slide and limit slide, limit switch, when push plate assembly reaches preset position, limit slide triggers limit switch, controller immediately controls electric cylinder to stop, ensure that material can be accurately pushed to feeding station each time, in addition to the feeding confusion problem that easily appears when multiple material stacks, the first flow baffle and second flow baffle of the structure can guide material to move stably upwards in pushing process, ensure the accuracy of feeding sequence.

This utility model relates to the technical field of limit switch protection devices, specifically disclosing a non-shaking elevator limit switch protection device, including a mounting plate. A protective shell is fixedly installed on the top of the mounting plate, and a protection mechanism is set inside the protective shell. The protection mechanism includes a storage shell, which is fixedly installed inside the protective shell at the top of the mounting plate. The storage shell has a storage groove inside, and a first spring is embedded in the top of the inner part of the protective shell. This utility model, through the storage shell, storage groove, first spring, contact plate, and flexible pad, and in conjunction with a fixing plate, rubber block, and locking groove, can initially connect the mounting plate and the protective shell, and can accommodate the switch and provide protection, preventing shaking and collisions. It also avoids using too many components or structures of different materials for protection, improves the overall ease of use, and reduces production costs.

The utility model discloses a desktop type intelligent manufacturing production line belongs to manufacturing production line technical field, and one side of miniature intelligent desktop is equipped with walking axle, and the walking axle is equipped with the folding material taking spare of sliding installation, and the joint of folding material taking spare is equipped with three -axis stepper motor respectively, and the outer end of folding material taking spare is equipped with electromagnet, and the walking axle is equipped with proximity limit switch 5 and proximity limit switch 6, and the outer end of walking axle is equipped with six -station vertical warehouse, and six -station vertical warehouse is equipped with proximity switch, and the stamping assembly station is composed of proximity limit switch 4 and proximity limit switch 3, and one side of walking axle is equipped with stamping assembly station, and stamping assembly station is equipped with proximity limit switch 4, and the oblique below of proximity limit switch 4 is equipped with proximity limit switch, can according to production demand quick adjustment the position of slide platform, improve the efficiency of feeding and discharging, and the application is multifunctional for integrated combination installation, realizes the function of greatly improved applicable range.

The utility model provides an elevator limit switch assembly, which relates to the technical field of elevator accessories, and comprises a pinch plate, a cavity, a cushion layer, a through hole, a housing, a rotating shaft, a baffle plate, a disc-shaped reed and a cross rod, and further comprises a spring which is arranged in the housing and is always in a compressed state, one end of the spring is connected with the cross rod, and the other end of the spring is connected with the rotating shaft. The other end of the spring is connected with the inner top of the housing, a limiting plate is arranged on the outer surface of the housing, the limit switch assembly further comprises a microswitch, the microswitch is arranged at the end, away from the buckle plate, of the transverse rod, and the limit switch assembly can be installed on the inner wall of an elevator shaft, so that the limit switch assembly is not affected by vibration when an elevator works; and meanwhile, lubricating oil cannot enter the contact, so that the stability and reliability of the limit switch assembly are improved, and meanwhile, as the housing can be rotationally adjusted on one side of the buckle plate, whether the limit switch assembly is inverted up and down or not does not need to be worried about when the limit switch assembly is installed, and the convenience of installation is improved.

This utility model discloses a hydraulic forming fixture for EGR pipes, including two positioning seats; a forming punch assembly disposed at one end of the positioning seats; a moving part connected to the end of the positioning seats away from the forming punch assembly, which controls the movement of the forming punch assembly to form the pipe, and limit switches are provided on both sides of the moving part; a limiting mold disposed at the end of the forming punch assembly away from the positioning seats, used to position the pipe to be formed. The hydraulic forming fixture for EGR pipes of this utility model has a simple structure, pre-forming followed by forming, with two forming processes ensuring the forming effect and preventing product cracking; it also effectively improves production efficiency, reduces process costs, and ensures product quality requirements.

The utility model discloses an arm support steering limiting mechanism, an arm support and an ore pass dredging device in the technical field of mining instruments, the limiting mechanism comprises a rotary supporting part used for being connected with a front arm support and providing steering, a pair of limiting switches is arranged at the non-rotating end of the rotary supporting part, a limiting switch triggering piece is arranged on the front arm support, and a limiting switch is arranged on the limiting switch triggering piece. The two limiting switches are located at the two ends of the moving path of the limiting switch triggering piece respectively. The limiting switch triggering piece is arranged on the front arm frame, and the pair of limiting switches is arranged on the rotation path of the limiting switches, so that the angle of the front arm frame does not deviate too much compared with the angle of the rear arm frame in the rotation process of the front arm frame relative to the rear arm frame, and stabilization is facilitated; and the rotary supporting part is controlled to stop rotating through contact of the limiting switch, so that the impact force is reduced, and stable operation of the rotary supporting part is ensured.

The utility model provides a test fixture for a circuit board of a lifting table, which comprises a bottom table, the bottom table is a hollow box body, and a microcomputer controller is connected in the bottom table. The top surface of the bottom table is connected with a circuit board fixing plate through a spring sliding mechanism, and the top surface of the bottom table is connected with a probe. A pressing device is arranged on the upper side of the circuit board fixing plate and connected to the top face of the bottom table. The top surface of the bottom table is connected with a simulation lifting mechanism; and the simulation lifting mechanism is electrically connected with the microcomputer controller. The device detects the functions of the circuit board of the lifting table, simulates the working state of the lifting table, monitors the working current, the working voltage, the remote control module power supply and the signal power supply, verifies the key functions of the limit switch logic, the operation mode switching and the like, ensures that the lifting table stops in time when reaching the limit position, and evaluates the reliability and the safety of the circuit board.

The utility model discloses a pneumatic valve control device based on an air storage tank and an air source amplifier, and relates to the field of pneumatic valve control devices. A traditional pneumatic valve lacks an effective emergency gas supply guarantee mechanism, the valve cannot be closed rapidly, personnel safety and the production environment are greatly threatened, large resistance exists in the gas transmission and control process, and valve opening and closing response is slow. The pneumatic valve comprises an air filtering pressure reducing valve, an electric valve positioner, a first air source amplifier, a second air source amplifier, a pneumatic actuator, a limit switch, an air storage tank, an electromagnetic valve, a first pneumatic valve, a second pneumatic valve and a valve body. According to the device, the air inflow can be adjusted according to system requirements, stability and accuracy of valve action are guaranteed, quick response of the valve action is achieved, when a gas cut-off fault occurs, a standby gas source of the gas storage tank is automatically switched, the valve is driven to be quickly and accurately closed, and safety accidents possibly caused by out-of-control of the valve are effectively prevented.

This utility model relates to the technical field of ice makers and related equipment, and discloses a photoelectric motor stroke controller, including a motor, a stroke controller body, a first housing, a second housing, a PCB board, photoelectric switches S1 and S2, limit switches K1 and K2. This photoelectric motor stroke controller integrates the dual protection functions of photoelectric switch position detection and limit switch stroke limitation, making the system safer and more reliable. It effectively avoids permanent damage to the ice maker caused by motor control system failure. The integrated design of the motor and stroke control facilitates installation, improves overall assembly efficiency, and reduces installation complexity. Using photoelectric switches instead of traditional mechanical switches extends the lifespan of the photoelectric switches, reducing maintenance costs and replacement frequency. The simplified mechanical structure lowers production costs and enhances the product's market competitiveness.

The invention belongs to the field of construction hoists, and provides an anti-hanging cable arm for a construction hoist, which comprises an arm body, a connecting rod device, a cable net sleeve, a force adjusting device, a clamping device and a limit switch, the arm body is of a cavity structure; the connecting rod device is hinged and fixed on the arm body through a shaft or a bolt and can rotate around a hinge point; a cable net sleeve is installed at one end of the connecting rod device, the other end of the connecting rod device is connected with the arm body through a force adjusting device, and when the connecting rod device rotates, the end of the connecting rod device acts to trigger a limiting switch installed on the arm body. The clamping device is installed in the cavity of the arm body and used for clamping a cable arranged in the arm body in a penetrating mode. The device can effectively solve the safety problems of cable snapping, structural deformation, cage outage and the like caused by interference with a building or a scaffold in the cable running process, and the running safety and the operation continuity of the construction hoist are guaranteed.

The utility model relates to the technical field of oil extraction, and discloses an oil extraction gate opening wrench which comprises a main body, a through hole is formed in the top of the main body, a linkage shaft is inserted into the through hole, the surface of the linkage shaft is rotationally connected with a limiting stopper, rectangular grooves are formed in the two sides of the limiting stopper, and the limiting stopper is fixedly connected with the through hole. And an adjusting nut is clamped in the rectangular groove. According to the wrench for opening the gate in oil extraction, through the arrangement of the limiting stopper, the adjusting nut, the adjusting rod and the clamping device, when equipment needs to be used for opening the gate, the equipment is aligned with the gate, the adjusting nut is rotated, the adjusting rod is made to move and pushed out, and after the proper distance is adjusted according to the actual situation, the clamping device is clamped to the gate; and therefore, the equipment can better fix the gate, and the situation that when the equipment is used, the clamping force of the equipment on the gate is possibly insufficient, consequently, the equipment loosens and slides down, and the safety is poor is effectively avoided.

The utility model discloses a combined throttling device and ammonia water absorption refrigeration system, wherein the combined throttling device comprises a stepping motor, a needle valve, a controller and a limit switch, the needle valve is used as a throttling element, and the stepping motor comprises an output shaft used for outputting linear displacement; the output shaft is connected with a valve needle of the needle valve and converts output displacement into linear displacement of the valve needle, the controller is used for controlling the displacement of the output shaft so as to adjust the opening degree of the needle valve, the limiting switch is connected with the controller, and when the needle valve reaches the minimum opening degree and / or the maximum opening degree, the limiting switch is triggered to send an electric signal to the controller. According to the combined throttling device, the valve needle of the needle valve is driven to axially move through accurate displacement output of the stepping motor, accurate adjustment of the sectional area of a fluid channel can be achieved, and therefore the high-accuracy control requirement of a system for refrigerant flow is met.

The utility model belongs to the technical field of high-altitude operation mechanical equipment, and particularly relates to a high-altitude operation machine and an anti-collision device thereof. The anti-collision device comprises a telescopic sleeve assembly, a trigger piece, an elastic reset piece and a limiting switch, the telescopic sleeve assembly comprises a short sleeve and a movable rod which are matched in a telescopic mode in the vertical direction, and the top end of the movable rod stretches out of the short sleeve and stretches out to the position above the working platform; the trigger piece extends out of the movable rod; the limiting switch is installed on the short sleeve and used for being electrically connected with a lifting mechanism of the high-altitude operation machine, the limiting switch is located below the triggering piece, and a contact of the limiting switch can reach the switching position under pressing triggering of the triggering piece so as to send out a work stopping signal aiming at the lifting mechanism. In the process that the lifting mechanism drives the working platform to ascend, the movable rod replaces a contact of the limiting switch to make direct contact with an obstacle, so that the damage risk of the limiting switch is reduced, and the service life of the anti-collision device is prolonged.

This utility model relates to a plate feeding device for a carving machine. The plate lifting mechanism includes a base, a lifting support platform, a limiting plate, and a baffle. The limiting plate has two slidable opening and closing mechanisms on the left and right sides of the base. The lifting support platform is located inside the base between the two limiting plates. The baffle is fixed to the base near the end of the plate conveyor. The top of the limiting plate has a groove, inside which a sliding pressure block and a support block are fitted. Limit switch one and limit switch two are respectively located at the bottom of the groove and on the bottom surface of the support block. The sliding pressure block is located between limit switch one and limit switch two. The top of the limiting plate has an adjustment mechanism to adjust the position of the support block. It limits the plate by using two limiting plates and a baffle, thus preventing the plate from tilting. The lifting support platform is started and stopped by the sliding pressure block contacting limit switch one and limit switch two, requiring no manual control and providing precise control. The height of the support block can be adjusted to accommodate plates of different thicknesses.

A dishwasher includes a tub. The dishwasher further includes a door rotatably coupled with the tub. The door is rotatable between a closed position and an open position. The dishwasher includes a leg coupled with the tub, and a biasing member coupled with the leg. The biasing member is coupled with the door. The biasing member biases the door toward the closed position. The dishwasher further includes a limit switch operably coupled to the biasing member. The dishwasher further includes an actuator assembly coupled with the tub. The actuator assembly includes a housing coupled with the tub, a driving member disposed within the housing, and an actuating member operably coupled with the driving member. The driving member drives the actuating member between a retracted position and an extended position. The actuating member moves the door in the closed position to an unsealed position.

The utility model relates to a platform lift safety linkage device, including one floor magnetic attraction door, second floor magnetic attraction door and lift, one floor magnetic attraction door installs on one floor platform, second floor magnetic attraction door installs on second floor platform, the device still includes lift door, limit switch group and control circuit, lift door installs in second floor magnetic attraction door near lift one side, limit switch group installs respectively on one floor magnetic attraction door, second floor magnetic attraction door and lift door, the proximity sensor group is installed on the lift, control circuit is electrically connected with limit switch group and proximity sensor group, when limit switch group and proximity sensor group trigger, the control circuit is conducted through, the lift rises or falls. Compared with prior art, the utility model has the advantages of high safety and reliability.

The utility model relates to a kind of automatic getting-on and getting-off machine dog unmanned vehicle, comprising: carriage and vehicle body;Carriage is located on vehicle body, and carriage and vehicle body are integrated structure;First laser radar is equipped in the top of vehicle body front end;The lateral wall of carriage is hinged with car side door;Carriage tail is hinged with car tail door, and ladder is installed on car tail door;Machine dog is placed in the carriage.The utility model has the beneficial effect that: ladder is set in car tail door, so that machine dog enters and exits unmanned vehicle, avoids machine dog to skid when entering and exiting unmanned vehicle;The height of each level of ladder and the ground clearance of last level and the walking height of machine dog are matched, to prevent machine dog from climbing and falling;When unmanned vehicle is driving, car tail door is locked in the tail of vehicle by electromagnetic lock;Limit switch is arranged on the tail, and the limit switch is provided with telescopic structure, when the extended part is completely retracted into the limit switch, electromagnetic lock is completely locked;Through electromagnetic lock and limit switch, car tail door is firmly locked in the tail.