41results about How to "Avoid repairs" patented technology

The invention relates to the technical field of non-destructive testing, and particularly discloses an aero-engine blade non-destructive flaw detection method for a miniature unmanned aerial vehicle, which comprises the following steps: acquiring stress data of a blade in a use process in real time by using an MEMS sensor, analyzing the data, and identifying a stress concentration area; carrying out real-time monitoring on crack data of the stress concentration area, extracting crack propagation fluctuation characteristics by utilizing a wavelet transform algorithm, and calculating a crack propagation fluctuation index; fatigue strength data of the material is monitored, fatigue failure characteristics are extracted, and a fatigue failure index is generated through a support vector machine algorithm; comprehensively analyzing the crack propagation fluctuation index and the fatigue failure index, and judging whether the blade is in a healthy state or not; and finally, based on the blade health state, determining whether to carry out further detection or maintenance.

The invention discloses a wind power blade unmanned aerial vehicle inspection method and device, and belongs to the technical field of wind driven generators, and the wind power blade unmanned aerial vehicle inspection method comprises the steps: carrying out the unmanned aerial vehicle inspection of the front surface of a wind power blade to form first inspection information, and carrying out the unmanned aerial vehicle inspection of the back surface of the wind power blade to form second inspection information, the first inspection information comprises a first track point data set and a blade front image set, and the second inspection information comprises a second track point data set and a blade back image set; according to the first inspection information and the second inspection information, in combination with a wind power blade defect judgment condition, obtaining a wind power blade unmanned aerial vehicle inspection result; according to the wind power blade unmanned aerial vehicle inspection result, whether an unmanned aerial vehicle re-inspection mode is started is judged, if yes, the unmanned aerial vehicle re-inspection mode is started, and the wind power blade unmanned aerial vehicle inspection result is updated; and if not, the re-inspection mode is not started. The method can reduce the influence on the wind power plant operation and power generation efficiency, and improves the accuracy of the wind power blade unmanned aerial vehicle inspection result.

The invention discloses a water turbine guide vane position fault judgment method and system, and belongs to the technical field of water turbine operation state real-time monitoring and fault analysis, and the method comprises the steps: collecting water turbine guide vane position data, environmental parameters and micro-vibration signals in real time through a non-intrusive mode, and eliminating noise and abnormal values; constructing a health model of a guide vane position, inputting the health model into a comparison module, and identifying a deviation from a real-time model constructed by real-time data; and fault judgment and fault simulation and prediction are carried out on the guide vane according to the deviation result, and a correction scheme is called according to the prediction result. According to the method, the real-time monitoring and fault judgment capability of the position of the guide vane of the water turbine is improved, the safety and the high efficiency of equipment are ensured, a solid data foundation is provided for continuously optimizing a maintenance strategy by establishing a long-acting monitoring and recording mechanism, the water turbine industry is promoted to develop towards a more intelligent and automatic direction, and the development period is shortened. The overall operation efficiency is further improved; and the service life of equipment is prolonged.

The invention discloses an optical proximity correction method and device, a computer readable storage medium and electronic equipment. The optical proximity correction method comprises the following steps: acquiring a to-be-corrected layout; correcting the to-be-corrected layout to obtain a preliminary corrected layout; obtaining a hot spot to be repaired according to the preliminary correction layout; dividing a first area, wherein the hot spot to be repaired is located in the first area; according to the first area, repairing the to-be-repaired hot spot to obtain a to-be-checked layout; checking the to-be-checked layout after the to-be-checked layout is corrected; and obtaining the tape-out layout according to the corrected checking result. After obtaining the preliminary correction layout and the hot spot to be repaired, dividing a first region; and repairing the hot spot to be repaired according to the first area. Only the layout of the first region with the to-be-repaired hot spot is repaired, so that the repair of patterns in other regions in the layout is avoided, and the repair efficiency and the repair speed can be effectively improved.

The utility model relates to autonomous operation equipment, and aims to solve the technical problem that self-moving equipment and a working module are difficult to combine when the autonomous operation equipment in the prior art has an assembly error or a hook body deforms. The autonomous operation device comprises: a self-moving device provided with a first hook body; the working module is provided with a shell provided with a communicating hole, a hook lock assembly is installed in the shell and provided with a guide sleeve installed in the communicating hole, a first movable gap is formed between the outer wall of the guide sleeve and the inner wall of the communicating hole, and the gap enables the guide sleeve to adaptively move in the radial direction of the communicating hole under the action of external force. The guide sleeve can slightly move in the radial direction of the communicating hole, so that the first hook body can be smoothly inserted into and connected to the hook lock assembly. The assembly error can be compensated through the tiny adjustment, reworking and adjustment caused by the assembly error are reduced, and therefore the assembly efficiency is improved.

This invention relates to the field of medical device technology, specifically to a fixation brace for postoperative repair of lateral collateral ligament injury of the ankle joint. It includes a bionic support shell conforming to the dorsum of the foot, ankle, and heel. The bionic support shell comprises a dorsum segment, an ankle segment, and a heel segment conforming to the dorsum of the foot, ankle, and heel. The bionic support shell is equipped with a multi-dimensional fit and fixation mechanism and an adaptive rehabilitation adjustment mechanism. The multi-dimensional fit and fixation mechanism is electrically connected to a control module, which is also electrically connected to the adaptive rehabilitation adjustment mechanism. The multi-dimensional fit and fixation mechanism includes an arch support component, a circumferential tightening component, and a heel limiting component. The control module is used to adjust the fixation force of the multi-dimensional fit and fixation mechanism, simultaneously and in conjunction with adjusting the range of motion limits of the adaptive rehabilitation adjustment mechanism. This invention achieves precise multi-point fit and fixation of the ankle joint, with precisely adjustable fixation force.

The utility model discloses a drainage system for a basement post-cast strip. The drainage system comprises a retaining wall located at the position of the basement post-cast strip. The space between the basement post-cast strip and the retaining wall is filled with a gravel layer, a thin film with a certain thickness is laid on the gravel layer, non-woven fabric is additionally arranged on the thin film to form a hydrophobic layer, the hydrophobic layer covers the post-cast strip, anti-crack steel bars and a terrace layer are arranged on the gravel layer and the hydrophobic layer, and a water diversion pipe is embedded in the terrace layer to be connected with a water collecting well. According to the basement post-cast strip drainage system, it can be guaranteed that water seepage does not occur at the post-cast strip, drainage can be conducted on the post-cast strip, basement moisture and water accumulation caused by improper construction are effectively prevented, and maintenance caused by improper construction is avoided.

The utility model discloses a high-yield potato seeding device and relates to the technical field of potato seeding. According to the discharging box, the left face and the right face of the discharging box are both fixedly connected with fixing groove blocks, the upper sides of the inner walls of the two fixing groove blocks are both fixedly connected with motors, the output ends of the two motors are both fixedly connected with threaded rods, and the rod walls of the two threaded rods are both in threaded connection with threaded sleeves; and limiting grooves are formed in the opposite sides of the inner walls of the two fixing groove blocks correspondingly, limiting blocks are slidably connected to the inner walls of the two limiting grooves correspondingly, base plates are fixedly connected to the bottom faces of the two threaded sleeves correspondingly, cavities are formed in the two base plates correspondingly, and fixing structures are arranged on one sides of the lower sides of the inner walls of the two cavities correspondingly. According to the potato seeding device, the tractor is prevented from toppling when being separated from the seeding machine, so that the seeding machine is prevented from being damaged, the maintenance of the seeding machine is avoided, and the use effect of the potato seeding device is improved.

The utility model relates to the technical field of tunnel engineering seepage prevention, in particular to a tunnel bentonite seepage prevention structure. The anti-seepage structure comprises an open-cut tunnel anti-seepage structure and a new Austrian composite tunnel anti-seepage structure, the open-cut tunnel anti-seepage structure comprises an open-cut tunnel inverted arch bottom plate anti-seepage structure, an open-cut tunnel vertical wall anti-seepage structure and an open-cut tunnel vault anti-seepage structure. The novel Austrian-method composite tunnel anti-seepage structure comprises a novel Austrian-method tunnel inverted arch bottom plate anti-seepage structure, a novel Austrian-method tunnel vertical wall anti-seepage structure and a novel Austrian-method tunnel vault anti-seepage structure. According to the technical scheme, the problems that in the prior art, a waterproof roll or a waterproof plate cannot be tightly bonded with a base layer, large-area water mixing is caused, and water seepage, drainage, maintenance and management costs are increased are solved.

The utility model discloses a gun needle of a nail gun, the nail gun comprises a nail gun body and the gun needle, the disclosed gun needle comprises a first gun needle section (100) and a second gun needle section (200), and the first gun needle section (100) and the second gun needle section (200) are sequentially distributed in the direction away from the nail gun body (300). The first end part of the first gun needle section (100) is used for being detachably connected with the nail gun body (300), the first end part of the second gun needle section (200) is detachably connected with the second end part of the first gun needle section (100), and the second end part of the second gun needle section (200) is a working end of the gun needle. According to the scheme, the problem that the gun pin related to the related technology is high in part maintenance or replacement cost can be solved. The utility model further discloses the nail gun.

The utility model discloses a positioning tool for electromechanical maintenance, which comprises an operating platform, a sliding chute is arranged at the top of the operating platform, a fixed plate is welded at the top of the operating platform, a sliding plate is arranged in an inner cavity of the sliding chute, two symmetrical limiting rods are welded at the top of the operating platform, and the sliding plate is arranged in the sliding chute. And the front face and the back face of the sliding plate are each rotationally connected with two sets of limiting wheels, the limiting wheels are attached to the surfaces of the limiting rods, and an inner cavity of the sliding groove is rotationally connected with a first threaded rod. The rotating handle is rotated to enable the sliding plate to reach a proper position, the motor is placed between the fixing plate and the sliding plate, the rotating block is started to enable the clamping block to clamp and fix the motor, the second motor is started to enable the clamping block to drive the motor to rotate to reach a proper position, and then the motor can be rotationally positioned through the positioning device. The situation that a user needs to maintain the motor while holding the motor is avoided, and the purpose of improving the motor maintenance efficiency is achieved.

The utility model relates to the technical field of production and processing equipment, and provides a crushing device for preparing a hard carbon negative electrode material, which comprises a support frame, the inner surface of the support frame is fixedly provided with a shell, the inner surface of the shell is movably embedded with a plurality of rotating shafts I, the outer surfaces of the plurality of rotating shafts I are all rotatably connected with belt pulleys I, and the belt pulleys I are rotatably connected with belt pulleys II; the outer surfaces of the multiple first belt wheels are in transmission connection with two first transmission belts, a motor is fixedly installed on the outer surface of one first rotating shaft, a supporting plate is fixedly connected to the bottom of the motor, and square blocks are arranged on the outer surfaces of the multiple first rotating shafts. Compared with the prior art, the vibration screening device has the advantages that the vibration screening device is simple in structure, maintenance cost is reduced, working intensity of maintainers is reduced, products on the screening block are vibrated, the situation that the products are too large is avoided, product quality is improved, and follow-up material grading and mixing uniformity and performance and quality consistency of final products are not affected.

The present invention belongs to the technical field of inspection equipment, and specifically is an intelligent inspection equipment for electric power equipment with a protective structure, comprising a trolley box, wherein energy-renewing mechanisms are arranged on the front and rear sides of the trolley box, an anti-collision mechanism is arranged on the left end inside the trolley box, a retracting and extending mechanism is arranged in the middle of the interior of the trolley box, a lifting mechanism is arranged under the retracting and extending mechanism, a linkage mechanism is arranged between the anti-collision mechanism and the retracting and extending mechanism, a driving mechanism is arranged on the right end inside the trolley box, a moving mechanism is arranged at the bottom of the trolley box, and the driving mechanism is connected to the moving mechanism. The present invention protects an inspection robot together through the anti-collision mechanism, the retracting and extending mechanism and the linkage mechanism therebetween, and the energy-renewing mechanism provides additional power for the inspection robot to recharge the robot.

The utility model relates to the probe structure field of mine ultrasonic detector relates to a kind of probe structure of mine ultrasonic surrounding rock fissure detector, including measuring rod, detector probe and acoustic lens mounting frame and probe installation component, the threaded portion on the measuring rod is equipped with detector probe, in the utility model, the limiting hole thread of guide rod is passed through with buckle bolt, so that guide rod and protective frame are screwed together by buckle bolt thread, acoustic lens protective shell can be on guide rod by sliding sleeve, sliding, acoustic lens protective shell can be slidably protected on detector probe and acoustic lens mounting frame, canvas connecting cover can be protected at the connecting place of detector probe and acoustic lens mounting frame, can dustproof and insulation protection is carried out to detector probe and acoustic lens mounting frame, canvas connecting cover and acoustic lens protective shell play anti-aging or joint wear to mine probe sealant, extend the service life of mine probe, avoid probe maintenance in mine.

The invention provides a valve control method and device, an engine and a vehicle, and belongs to the technical field of vehicles, when it is monitored that an air inlet bypass valve is stuck and lagged and cannot give an alarm immediately, the air inlet bypass valve is controlled to conduct self-cleaning, oil stains and foreign matter attached to the air inlet bypass valve are cleaned through self-cleaning, accidental foreign matter is avoided, and the service life of the air inlet bypass valve is prolonged. And fault misjudgment caused by oil gas coking and the like after pressure is avoided. If self-cleaning fails, a fault code is reported, an alarm prompt is not directly given according to the fault code, fault judgment contingency is avoided by determining the continuous period number of clamping stagnation of the air inlet bypass valve, the fault judgment accuracy is improved, and only when the continuous period number is larger than or equal to the preset safety frequency, the fault code is reported. According to the method, the fault of the air inlet bypass valve can be determined, alarm prompt is given, contingency of single judgment is avoided through continuous fault judgment, alarm prompt when the air inlet bypass valve is intact is avoided, the use cost is saved, and the use experience is improved.

The invention provides a temperature correction method, device and equipment for a non-uniform temperature field of a containment and a medium, and the optimization method comprises the steps: collecting the data of a monitoring point in each region, and obtaining a training data set; dividing each region along the thickness direction to generate a plurality of sub-regions with the same thickness, and obtaining a to-be-inverted parameter of each sub-region; inputting the to-be-inverted parameters of each sub-region and the plurality of temperature deviation data into a finite element model, and generating strain calculation data of each sub-region under the temperature deviation data; calculating inversion parameters of all the sub-regions; and optimizing the finite element model according to the inversion parameters. Through the temperature correction method, device and equipment for the non-uniform temperature field of the containment and the medium provided by the invention, the analysis precision of the containment structure under a complex temperature condition can be improved.

The invention discloses an equipment management system and method based on a digital twin technology. According to the invention, the digital twinborn model is constructed to provide a highly realistic virtual copy for the system, and the copy can reflect the state and behavior of actual equipment in real time. Through parameter definition, structural modeling and behavioral modeling of the model design sub-module, the system can create an accurate equipment model, and the model not only contains physical characteristics of equipment, but also can simulate the performance of the equipment under different working conditions. According to the model, the system can perform various simulation experiments and analysis without directly intervening actual equipment, so that the test and verification cost is greatly reduced. Meanwhile, the environmental adaptability evaluation of the model simulation sub-module can predict the performance of the equipment in different working environments, and helps an enterprise to identify potential problems before equipment deployment, thereby avoiding expensive field adjustment and maintenance.

The present invention discloses a fault analysis method and system for a vehicle domain controller, which relates to the field of vehicle technology, including obtaining vehicle domain controller information, obtaining control interaction system information based on the vehicle domain controller information and the function analysis of the vehicle domain controller, and judging whether the vehicle domain controller fails according to the control interaction system operation information and control instruction information. The present invention analyzes the vehicle domain controller through the control instruction difference index, identifies the vehicle domain controller failure problem in time, ensures the safety of the vehicle and the reliability of driving, analyzes the vehicle domain controller failure through the vehicle domain controller sensing difference coefficient and the vehicle stability influence index, improves the efficiency of vehicle domain controller failure analysis, more accurately locates the root cause of the problem, avoids unnecessary replacement or maintenance, thereby saving maintenance costs, shortening the maintenance cycle, and improving maintenance efficiency.

The present invention discloses a method and system for dynamic risk assessment of historical buildings, and relates to the technical field of risk assessment of historical buildings. The method for dynamic risk assessment of historical buildings obtains the three-dimensional coordinates, real-time image data and internal property data of the historical buildings, and comprehensively analyzes the surface and internal data of each time period to obtain the surface change risk assessment index and the internal change risk assessment index, and analyzes the comprehensive change risk assessment index. If the index exceeds the preset interval, the abnormal surface is identified. The present invention can achieve comprehensive and continuous monitoring by collecting and analyzing the dynamic data of the surface and internal structure of the historical buildings. Compared with traditional static inspections or single inspections, dynamic monitoring can more timely capture the slight changes of the building in different time periods, especially some hidden damages that are difficult to directly observe. Through this dynamic monitoring method, potential risks can be discovered in advance.

This invention provides a method for improving interlayer defects in pultruded main beams of wind turbine blades and the resulting pultruded main beam. The method includes an improved process (1): when laying the pultruded main beam, the side guards of the tensioning fixture are removed first, and then it is hoisted and laid. The method of this invention for improving interlayer defects in pultruded main beams of wind turbine blades significantly reduces the number of interlayer defects in the blade pultruded main beam by optimizing the layout of the guiding auxiliary materials and optimizing the timing and method of injection. At the same time, it does not cause significant changes or other problems to the injection whitening quality defects, injection resin dosage, total injection time, blade mass distance, production efficiency, etc.

The present invention discloses a tool and vulcanization method for integral vulcanization of lining rubber materials of large-scale equipment in nuclear power plants, wherein the tool comprises a split steel plate, a supporting element, an end sealing cover plate I and an end sealing cover plate II. The method comprises: step one, sandblasting and surface treatment; step two, cleaning the sandblasted surface; step three, applying adhesive; step four, laying the semi-finished lining product; step five, loading the split steel plate and the end sealing cover plate I; step six, installing the supporting element; step seven, installing the end sealing cover plate II; step eight, transferring the equipment into a drying room, connecting the high-temperature air pipe of the drying room with the inner cavity of the pipe body; step nine, treating the equipment at 170°C; step ten, disassembling the supporting element; step eleven, trimming the rubber edge, and completing the integral compounding of the rubber lining and the inner wall of the equipment. The rubber-lined equipment obtained by the method of the present invention meets the 60-year life requirement of the nuclear power plant, can greatly reduce the maintenance cost of the nuclear power plant, and reduce the risk brought by equipment replacement.

The present invention discloses a method and system for predicting the gradual change information of frozen soil foundation of highway in long-term operation, and relates to the technical field of frozen soil treatment of highway. In step S1 of the method, the foundation meltwater condition coefficient Rsx is generated by integrating multi-source data, thereby realizing the assessment of the risk of foundation meltwater. Step S2 forms the frozen soil state coefficient ZTx through multi-dimensional collection of freezing and thawing data sets, and clarifies the seasonal frozen soil area and the non-seasonal frozen soil area. Step S3 corrects the frozen soil state coefficient by using the vegetation coverage rate ZbF and the terrain elevation value Gc obtained by remote sensing technology. Step S4 realizes the real-time monitoring and differential treatment of the foundation state by establishing a frozen soil feature library and a frozen soil foundation gradual change treatment plan library; Step S5 collects the annual average sunlight exposure time Gz of the corresponding frozen soil area that has been allocated; the frozen soil prediction and treatment model predicts and analyzes the matching gradual change treatment plan, and optimizes the treatment plan to improve the long-term operation and maintenance of the frozen soil foundation.

The present invention relates to the field of spacecraft control technology, and in particular to a spacecraft system and a control method thereof, the system comprising: a microwave electric propulsion module, a charging module, a data acquisition module and a power supply determination module; judging whether the operation of a single microwave electric propulsion meets the preset standard according to the actual operating parameters of the main power supply module collected, and determining the reason for not meeting the standard, judging whether it is necessary to use a backup power supply module according to the reason for not meeting the standard, and detecting whether the operation of the backup power supply module meets the standard when determining to switch the backup power supply module for power supply, and determining the corresponding optimization method when the backup power supply module does not meet the standard. The present invention can timely discover problems and take corresponding measures, including switching to the backup power supply module or making optimization suggestions, through real-time monitoring and fault diagnosis of the operating parameters of the power supply module, thereby improving the self-repair ability of the system, reducing the need for external intervention, and improving reliability and controllability.

The utility model discloses a barrier gate with a detachable gate, which comprises stand columns and servo motors, the servo motors are fixed at the top ends of the stand columns, and the number of the stand columns and the number of the servo motors are both two; and one end of the servo motor is connected with a connecting rod, the connecting rod extends into the stand column, the outer portion of the connecting rod is sleeved with a sleeve block, and a fixing block is fixed to the outer portion of the sleeve block. The fixing block and the connecting block are vertically aligned, the limiting hole and the fixing hole are aligned, then the positioning rod is inserted into the limiting hole and the fixing hole, the protruding block and the groove are connected in a clamped mode, and even if the positioning rod preliminarily fixes the fixing block and the connecting block, the fixing block and the connecting block are not fixed. And external threads are in threaded connection with internal threads on a limiting barrel, so that the limiting barrel and the bottom of a positioning rod are conveniently fixed, namely, the positioning rod is clamped in a fixing block and a connecting block, and then the anti-collision mechanism and the sleeve block are fixedly mounted.

This invention discloses a repair device and method for manhole threaded holes. The repair device includes: an adapter plate; a repair tool holder including a frame, a drive motor, and a spindle, the spindle being connected to the repair tool; a first support plate on the end of the frame near the spindle, the first support plate being connected to a first slide rail via a first slider; a second slide rail on the first support plate, the second slide rail being perpendicular to the first slide rail, the second slide rail being connected to a second support plate via a second slider; the second support plate being perpendicular to the first support plate; a third slide rail on the second support plate, the drive motor being connected to the third slide rail via a third slider; and an auxiliary tilting carriage including a frame and a tilting bracket mounted on the frame, the tilting bracket being connected to the side of the frame near the drive motor, the tilting bracket being used to keep the repair tool holder perpendicular to the adapter plate. This device can directly process and repair threaded holes at different positions on the outer edge of the manhole, improving repair efficiency and accuracy.

The embodiment of the invention discloses a storage node fault migration method and device based on a double-controller architecture, electronic equipment and a storage medium, and the method comprises the steps that storage resources are divided into a plurality of storage partitions, two storage nodes are configured on each storage partition, and in each storage partition, each storage node is configured with one storage node; different storage service object marks are configured according to the storage resources controlled by the two storage nodes, and the storage service management file is configured to the two storage nodes; a high-availability system is established between two storage nodes which are opposite end nodes, and when one storage node breaks down, a normal storage node takes over a storage resource controlled by the faulted storage node and starts a storage service of the taken-over storage resource; and when the faulty storage node is recovered, the normal storage node stops the storage service of the storage resources taken over by the normal storage node, and the recovered storage node takes over the storage resources managed and controlled by the node and starts the storage service for taking over the storage resources.

The utility model relates to the technical field of blades, and discloses a blade capable of effectively reducing wind resistance, which comprises a plurality of rotating blades, a fixing plate is in threaded connection with the interior of each rotating blade, a connection stabilizing shell is fixedly connected with the top end of each fixing plate, and an insertion stabilizing shell is slidably connected with the interior of each connection stabilizing shell. A connecting pushing cylinder is fixedly connected to the interior of the inserting stabilizing shell, a pushing piece is fixedly connected to the interior of the connecting pushing cylinder, and auxiliary positioning assemblies are fixedly connected to the left bottom end and the right bottom end of the pushing piece correspondingly and used for auxiliary positioning of the pushing piece; the top end of the insertion stabilizing shell is fixedly connected with an auxiliary blade. According to the utility model, errors and errors in the assembling process are reduced through simple and clear mounting and positioning, so that the auxiliary blade is ensured to be correctly mounted at a designed position, and subsequent repair and adjustment are avoided.

The utility model discloses a kind of split energy-absorbing box in the field of energy-absorbing box, including upper connecting plate, first energy-absorbing rib, second energy-absorbing rib, third energy-absorbing rib, fourth energy-absorbing rib and lower connecting plate, upper connecting plate and lower connecting plate are parallel structure, first energy-absorbing rib and second energy-absorbing rib are perpendicular structure, second energy-absorbing rib and third energy-absorbing rib are perpendicular structure, third energy-absorbing rib and fourth energy-absorbing rib are perpendicular structure, the both sides of upper connecting plate are respectively provided with upper connecting lug and upper connecting groove, the both sides of lower connecting plate are respectively provided with lower connecting lug and lower connecting groove, when multiple energy-absorbing box monomers are combined into energy-absorbing box whole according to the length of use, upper connecting groove and upper connecting lug are pasted, lower connecting lug and lower connecting groove are pasted, the monomer of the utility model has no cavity structure, it is convenient for processing, cost is lower, the length of energy-absorbing box can be freely combined according to the size of vehicle, convenient to use.