336results about How to "Strong structural stability" patented technology

The invention discloses a waveguide coaxial filter, a design method thereof and a low-temperature receiver. The waveguide coaxial filter comprises a waveguide input port used for inputting an electromagnetic wave signal; the waveguide filtering structure is used for transmitting the electromagnetic wave signal in a waveguide transmission line mode and filtering a frequency spectrum signal with a set frequency in the electromagnetic wave signal; the waveguide coaxial conversion structure is arranged in the output port surface cavity of the waveguide filtering structure and is used for realizing mode conversion and impedance matching of the waveguide transmission line and the coaxial transmission line so as to convert a waveguide transmission line mode signal into a coaxial transmission line mode signal; and the coaxial output port is used for being connected with a coaxial transmission line so as to output a coaxial transmission line mode signal. A waveguide filtering structure and a waveguide coaxial conversion structure are integrally designed, so that the insertion loss performance is optimized on the whole, the size and weight of the device are greatly reduced, interconnection of systems and stability of the system structure are facilitated, and the low-temperature receiving device can be applied to low-temperature receivers in the aerospace field.

The invention discloses a modified positive electrode material and a preparation method and application thereof, and belongs to the technical field of secondary battery raw materials. The modified positive electrode material provided by the invention comprises a layered positive electrode material; the chemical formula of the layered positive electrode material is LiXO2, wherein X is at least one of Ni, Co and Mn; the coating layer is a two-dimensional MOF material which is deposited on the surface of the layered positive electrode material in situ; the molar ratio of X in the layered positive electrode material to a central atom in the two-dimensional MOF material is 1: (0.1-2.0). According to the modified positive electrode material provided by the invention, the high-temperature cycling stability and the high-rate charge-discharge stability of the modified positive electrode material can be effectively improved. The invention also provides a preparation method and application of the modified positive electrode material.

The invention provides a double-hardness rubber-coated heel lift for a heel and a manufacturing process thereof, the double-hardness rubber-coated heel lift comprises an inner-layer support body and an outer-layer soft elastomer, the support body and the soft elastomer are made of the same materials with different hardness, the surface of one end of the support body is provided with a plurality of connecting columns used for being assembled with the heel, and the other end of the support body is connected with the soft elastomer. The soft elastic body wraps the bottom face and the side face of the supporting body through injection molding and is of an integrated structure. The method comprises the following steps: 1, performing injection molding on a rubber-plastic material through a support special mold to form a support; secondly, the supporting body formed through injection molding is placed in a special mold for soft elastomer injection molding, the soft elastomer material is wrapped and penetrates through the supporting body through second-time injection molding to form a product integrated with the supporting body, the heel lift machined through the technology is high in structural stability, the fusion degree of the supporting body and the soft elastomer is high, the delaminating phenomenon is not prone to occurring, and the service life of the heel lift is prolonged. Even if grease or other pollutants enter in the injection molding process, the phenomenon that the heel lift is delaminated cannot be caused.

The invention discloses a double-end Isofix interface connector, and the connector comprises an installation housing which is provided with crocodile mouths at two ends; the lock heads are hinged to the two ends of the mounting shell; the pair of connecting pieces can be respectively linked with the corresponding lock heads; the unlocking operation piece is provided with a pair of operation rods which are used for respectively controlling the connecting pieces corresponding to the unlocking operation piece during unlocking; when the lock head at one end is changed from the unlocking position to the locking position, the connecting piece corresponding to the lock head is linked to abut against the lock head for locking, the lock head at the other end is still located at the unlocking position, and at the moment, the connector is in a using state. When the lock head at the locking position needs to be changed into the unlocking position, the unlocking operation piece is operated to enable the operation rod to control the connecting piece corresponding to the operation rod to be linked with the lock head so as to cancel locking of the lock head, the lock head at the other end is still located at the unlocking position, and at the moment, the connector is in a non-use state. The device is simple in structure, easy to operate, convenient to use and high in overall structural stability and safety.

The invention belongs to the technical field of flood prevention slope protection, and particularly discloses a flood prevention slope protection for hydraulic engineering, which comprises a slope surface, a bottom frame is mounted on the surface of the slope surface, four cage bodies are uniformly mounted on the surface of the bottom frame, gabion cages fixedly sleeve the surfaces of the cage bodies, and a protection mechanism is arranged at the front end of the bottom frame. Control grooves are formed in the two ends of the top of the bottom frame, connecting rod mechanisms are arranged in the control grooves, a lifting mechanism is arranged in an inner cavity of the bottom frame, and a top head is connected to the top of the bottom frame in an inserted mode and matched with the connecting rod mechanisms and the lifting mechanism. Through cooperation of the top head, the connecting rod mechanism and the lifting mechanism, the cage body can be rapidly positioned on the surface of the bottom frame, the overall structure is simple, construction is relatively easy, the requirement for skills of constructors is low, the structural stability is high, good impact resistance and compression resistance are achieved, and large external pressure can be borne.

The utility model relates to the technical field of walking aids, in particular to a wheel type folding walking aid which comprises a folding frame, a handle, a front wheel, a left rear wheel and a right rear wheel. The folding frame comprises left and right upright posts, left and right upright post sliding sleeves and a front wheel connecting rod group; shear fork folding mechanisms are arranged among the left stand column, the left stand column sliding sleeve and the right stand column, among the right stand column sliding sleeve, among the left stand column, the left stand column sliding sleeve and the front wheel connecting rod group, among the right stand column, the right stand column sliding sleeve and the front wheel connecting rod group, among the left stand column, the left stand column sliding sleeve and the left rear wheel, and among the right stand column, the right stand column sliding sleeve and the right rear wheel; locking mechanisms are further arranged between the left stand column and the right stand column and the left stand column sliding sleeve and the right stand column sliding sleeve. The folding and unfolding device is reasonable in structure, convenient to fold and unfold, high in structural stability after being unfolded, stable in walking, small in size after being folded, small in occupied space, in an upright state, stable in placement and free of toppling over, secondary folding or independent disassembly of part of parts is not needed during folding, and great convenience is brought to a user.

The invention discloses a support joint, a middle support and a joint installation method, the support joint comprises a cushion block and a locking piece, one side of the cushion block is attached to a cross beam on the support, and the side, opposite to the cross beam, of the cushion block is of a cambered surface structure; the locking piece penetrates through the cross beam and is matched with the cambered surface structure of the cushion block to form a connecting hole, and the connecting hole allows the main cable to penetrate through and locks the main cable to the cushion block; the cambered surface structure is a partial cylindrical surface structure, and the axis of the cambered surface structure is perpendicular to the length direction of the main cable. The cushion block is used for supporting the main cable and is matched with the locking piece to lock the main cable, the cushion block reduces the corner folding risk of the main cable through the cambered surface structure, meanwhile, the main cable can be closer to the center of the cross beam, the stress of the cross beam is optimized, and the connection stability of the main cable is improved.

The utility model discloses a yarn false twisting device which comprises a false twisting mechanism, and the false twisting mechanism comprises a first false twisting assembly used for twisting yarn and a second false twisting assembly used for reinforcing the yarn. The first false twisting assembly comprises a hollow motor and a first false twister, and the hollow motor is fixedly connected with the first false twister and drives the first false twister to rotate; the second false twisting assembly comprises a hollow spindle and a second false twister, and the hollow spindle is fixedly connected with the second false twister and drives the second false twister to rotate. The yarn false twisting device can effectively and stably carry out false twisting and fixing on yarn, and the efficiency of the spinning process and the quality of products are effectively improved.

The invention discloses an organic conjugated fused ring polymer positive electrode material, and relates to the technical field of batteries. The molecular structural formula of the organic conjugated fused ring polymer positive electrode material is # imgabs0 #. The invention also provides a preparation method of the organic conjugated fused ring polymer positive electrode material and application of the organic conjugated fused ring polymer positive electrode material in a wide-temperature-range aqueous zinc ion battery. The raw materials used in the invention are green and environment-friendly, the price is low, the preparation process is simple, and when the positive electrode material is used as an aqueous zinc ion battery positive electrode material, excellent electrochemical properties such as high magnification, high cycle stability and excellent weather resistance can be realized. Therefore, the method is very suitable for large-scale popularization and application.

The invention belongs to the technical field of OCA optical cement, and discloses optical cement and a preparation method thereof. The optical adhesive is prepared from the following raw materials in parts by weight: 75 to 100 parts of acrylate prepolymer, 15 to 30 parts of diluent, 5 to 8 parts of acrylic acid, 10 to 20 parts of isobornyl methacrylate, 10 to 20 parts of silica sol, 2 to 3 parts of initiator, 0.5 to 3 parts of cross-linking agent and 0.5 to 3 parts of antioxidant. The acrylic resin is formed by polymerizing a hard monomer, a soft monomer and a functional monomer under the action of a photoinitiator. The optical adhesive prepared by the invention has good viscidity, is not easy to remain on a laminated display material, has high elongation and relatively good stripping property, meanwhile, the light transmittance and stability of the optical adhesive are improved by polymerization of the raw materials, and the optical adhesive is high in transparency, low in haze, free of shrinkage during curing and good in weather resistance.

The invention relates to the technical field of basement construction, and particularly discloses a prefabricated modular basement construction device and a construction method.The prefabricated modular basement construction device comprises an enclosure structure, a plurality of supporting column assemblies installed in the enclosure structure and floor assemblies installed on the supporting column assemblies; the enclosure structure comprises a peripheral assembly and a prefabricated inner wall plate which is installed on the peripheral assembly and matched with the peripheral assembly to form a cavity. The supporting column assembly is installed in the cavity. The peripheral assembly comprises a plurality of groups of corner columns which are vertically arranged, a plurality of groups of connecting columns which are arranged between two adjacent groups of corner columns and are vertically arranged, and prefabricated wall protection plates which are arranged between the adjacent connecting columns and / or the corner columns; a pouring cavity used for pouring concrete to form a cast-in-place wall plate is formed in the side, close to the prefabricated inner wall plate, of the prefabricated wall protection plate. The method has excellent effects in the aspects of improving the construction efficiency, enhancing the structural stability, optimizing the waterproof performance, improving the construction quality, improving the resource utilization efficiency and enhancing the design adaptability.

The invention relates to the technical field of ecological restoration and water resource management, in particular to a novel brick material based on corn straw as well as a preparation method and a use method of the novel brick material, and provides the novel brick material based on the corn straw in order to solve the problems of high water loss speed and slow ecological restoration of peat land. Comprising the following raw material components: corn straw powder, corn straw charcoal, calcium bentonite and corn stigma fiber, the corn straw powder, the charcoal, the calcium bentonite and the corn stigma fiber are mixed according to a specific proportion, and the mixture is subjected to compression molding to prepare the brick with good moisture retention performance and ecological compatibility. The method is specially used for water retention and vegetation recovery of the peat land.

This utility model relates to the field of photovoltaic cleaning robot technology, and discloses a cleaning device for a photovoltaic cleaning robot, including a slide table with a slot. Two sliders are slidably connected to the inner side of the slot. Connecting plates are rotatably connected to the lower side of the two sliders respectively. A cleaning roller shell is rotatably connected to the end of the two connecting plates away from the slide table. A cleaning roller is rotatably connected between the two sides of the cleaning roller shell. A cleaning roller lifting mechanism is provided on one side of the slide table to raise or lower the cleaning roller shell. This utility model is started by a second servo motor, which drives the two sliders to move closer or further apart. Through the interaction of the two connecting plates and the cleaning roller shell, the cleaning roller is raised or lowered, thereby adjusting the distance between the cleaning roller and the photovoltaic panel cleaning surface. It has the advantage of strong structural stability.

This utility model discloses a projector mounting bracket, belonging to the field of projector installation technology. It includes a first mounting component comprising a rotating block and a side connecting column, the rotating block and the side connecting column being fixedly connected; a second mounting component, the second mounting component being mounted on the end of the side connecting column and rotating relative to the side connecting column; a third mounting component, the third mounting component being mounted on the end of the second mounting component and rotating relative to the second mounting component; and a fourth mounting component, the fourth mounting component being movably connected to the third mounting component, the fourth mounting component being an L-shaped mounting plate with several mounting holes for mounting a projector. This utility model achieves stable installation of the projector, allows for multi-dimensional orientation adjustment of the projector for convenient use, and features a simple structure and strong structural stability, which helps improve the installation stability of the projector.

The invention provides a positive electrode material of a sodium ion secondary battery, a preparation method of the positive electrode material, the sodium ion secondary battery and electric equipment, and relates to the field of sodium ion batteries. The chemical formula of the positive electrode material of the sodium ion secondary battery provided by the invention is NaaNixFeyMnzM1-x-y-zO2, wherein a is more than or equal to 0.9 and less than or equal to 1.05, x is more than 0 and less than 1.0, y is more than 0 and less than 1.0, z is more than 0 and less than 1.0, 1-x-y-z is more than 0 and less than 1, and the element M is a metal element of which the valence is more than or equal to 2. According to the positive electrode material of the sodium ion secondary battery provided by the invention, the positive electrode active material is doped with the metal element containing the valence of + 2, + 3, + 4, + 5 or + 6 to regulate and control the molar weight of O-ions in lattice oxygen relative to O < 2-> when the positive electrode material of a sodium ion O3 structure is in a full charge state, so that the bonding strength of the doped metal element and oxygen is improved, and the content of high-activity O-free oxygen is reduced; and the sodium-electric O3 structure has relatively high structural stability.

The utility model relates to the technical field of coal mine filling mining, in particular to a fast and movable waste rock blocking wall for filling waste rock behind a support, and mainly solves the technical problems that an existing waste rock blocking wall is poor in structural stability, time-consuming and labor-consuming to build and poor in flexibility. The fast and movable type waste rock blocking wall comprises a bottom plate used for being attached to the ground of a roadway; the wall body assembly comprises a fixed wall body and spliced wall bodies, the bottom of the fixed wall body is hinged to the bottom plate, a hinged shaft is arranged in the width direction of the bottom plate, the number of the spliced wall bodies is at least one, the spliced wall bodies are detachably fixed to the upper portion of the fixed wall body, and the fixed wall body and all the spliced wall bodies form a complete wall body used for blocking waste rock; the supporting assembly comprises a telescopic rod and a locking piece, the telescopic rod is perpendicular to the width direction of the bottom plate, one end of the telescopic rod is hinged to the bottom plate, the other end of the telescopic rod is hinged to the fixed wall, and the locking piece is used for locking the length of the telescopic rod. The device is high in structural stability, easy and rapid to build and high in flexibility.

The utility model discloses a waterproof light guide key structure of an electronic product, which comprises a shell, a PCB (printed circuit board) is arranged in the shell, a key switch and an LED (light-emitting diode) lamp are arranged on the PCB, a key hole corresponding to the position of the key switch is arranged on the side surface of the shell, and the LED lamp is arranged in the key hole. And light guide keys which are clamped and fixed with the inner side of the shell, correspond to the key switches and the LED lamps and are made of silica gel materials are arranged in the key holes in an interference fit manner. According to the utility model, only one key hole is arranged, the good astigmatism of the silica gel material is matched with the structural modeling of the light guide key, the light guide effect of the function indicating lamp with a sense of science and technology is obtained, and the good ductility of the silica gel material is matched with the related structure of the shell, so that the key part is easily assembled, and the waterproof grade of the product can be improved; and in combination with the good buffering performance of the silica gel material, components such as the touch switch cannot be damaged in the falling or transportation vibration process of the product, and the product quality is improved.

The utility model discloses a front edge plate of an assembly type stand, which comprises a first installation part, a second installation part, a first supporting part, an extension part and a second supporting part which are connected, the first installation part is used for being connected with a pedal, the second installation part is used for installing a seat, the first supporting part is perpendicular to the second installation part, and the extension part is perpendicular to the first supporting part. The second supporting part is perpendicular to the extending part and abuts against the bottom of the second mounting part. The first supporting part is provided with a first reinforcing rib; the front edge plate of the assembly type stand has the advantage of being high in structural stability, the first supporting part and the second supporting part are arranged at the bottom of the second installation part for supporting, the reinforcing ribs are arranged on the first supporting part, the risk of deformation of the second installation part is reduced, and the structural stability is enhanced.

The utility model relates to the technical field of oil-immersed transformers, in particular to a transformer oil tank and iron core connecting structure which comprises an oil tank bottom plate and an iron core base located above the oil tank bottom plate, a piston cylinder is fixedly installed on the oil tank bottom plate, a piston cylinder cover is installed at the upper end of the piston cylinder, and a through hole is formed in the middle of the iron core base. A connecting rod is vertically arranged in the through hole, the lower end of the connecting rod penetrates through the piston cylinder cover and extends downwards into the piston cylinder, a horizontally-arranged piston is installed at the lower end of the connecting rod, an elastic piece is arranged between the bottom of the piston and the bottom of the piston cylinder, and a first oil hole and a second oil hole are formed in the side wall of the piston cylinder from top to bottom. The up-and-down movement range of the piston is the distance between the highest point and the lowest point of the hole diameters of the first oil hole and the second oil hole in the vertical direction. According to the device, the elastic piece is adopted for damping, and meanwhile liquid pressure is added for assisting damping, so that the damping effect is good.

The utility model discloses a pentagonal spoke type flexible temperature and pressure dual-mode sensor, and belongs to the field of flexible wearable electronics. The sensor mainly comprises a flexible substrate layer and a flexible packaging layer, wherein the upper surface of the substrate layer is provided with five transversely distributed metal temperature-sensitive films as temperature detection units; a longitudinally distributed metal temperature-sensitive film is used as a pressure detection unit; the flexible substrate layer is provided with a cavity and is in sealed connection with the packaging layer. The uniform distribution of the pentagonal radiation type temperature-sensitive film can effectively disperse the pressure, reduces the measurement error caused by local stress concentration, and is high in structural stability. The temperature-sensitive film is processed and manufactured by adopting the MEMS technology, has the advantages of light weight, low manufacturing cost, simple manufacturing process and the like, and can be widely applied to the fields of wearable electronic equipment and the like.

The present invention aims to provide a low-profile reconfigurable antenna, which belongs to the technical field of reconfigurable antennas. The design main body of the antenna is a dielectric disk loaded with a metal short circuit, a circular radiation patch is arranged on the upper surface of the dielectric disk, four square annular gaps are arranged on the radiation patch, a circular metal ground is arranged on the lower surface of the dielectric disk, a rectangular annular gap is arranged on the metal ground, a PIN diode is loaded on the gap, and the antenna pattern has a reconfigurable characteristic through the conduction and disconnection of the diode. At the same time, the dielectric disk is surrounded by a metal disk cavity, so that the overall structure of the antenna is stable, and the cross-sectional height of the entire antenna is only 0.125λ.

The utility model discloses an integrated fiber end beam splitter for multicore optical fiber, including the sheath and the inside bushing of its multicore optical fiber, and the multicore optical fiber includes a plurality of independent setting fiber cores, and the one end of each fiber core is induced modification and then etches and forms a microlens, and a plurality of microlenses form a microlens array, and each microlens is bonded with a grating of diffraction grating, and the diffraction grating is a two-dimensional plane film structure as a whole, covers the outside of microlens array, and the surface is etched with uniform and regular grating. The utility model discloses only through the end of the plurality of optical fibers is equipped with the microlens, and each microlens is bonded with a grating of diffraction grating, can make each fiber core light beam can enter corresponding microlens and complete collimation and diffract, and then bring the change of light beam phase and then split, and the application structure is simple, does not need additional coupling spare, and the splitting efficiency is high, and the stability is strong, effectively improves production efficiency, and reduces production cost.

The invention provides a positive electrode material and a battery, the positive electrode material is a lithium nickel cobalt oxide composite oxide, the powder conductivity of the positive electrode material is delta S / cm < 2 >, the particle size distribution width of the positive electrode material is Span, in an XRD pattern of the positive electrode material, the half-peak width of a characteristic peak corresponding to a (003) crystal plane of the positive electrode material is FWHM, and the positive electrode material meets the condition that (delta * span) / FWHM is more than 0.001 and less than or equal to 0.5. The positive electrode material provided by the invention has high capacity, strong structural stability and cycling stability.

The utility model discloses a liquid level visualization automatic induction soap dispenser which comprises a liquid soap bottle provided with an inner cavity and an intelligent pump head arranged on the liquid soap bottle. The liquid soap bottle comprises a bottom shell, a bottle body and a liquid level perspective ring connected between the bottom shell and the bottle body. A first limiting groove is annularly formed in an opening of the lower end of the bottle body, and a first limiting ring used for being embedded into the first limiting groove is annularly and upwards arranged at the top of the liquid level perspective ring in an extending mode. A second limiting groove is annularly formed in the top of the bottom shell, and a second limiting ring used for being embedded into the second limiting groove is annularly and downwards arranged at the bottom of the liquid level perspective ring in an extending mode. And the height of the liquid level perspective ring on the liquid soap bottle is less than or equal to 1 / 4 of the height of the liquid soap bottle. According to the liquid soap bottle, the liquid level perspective ring is arranged on the liquid soap bottle, and the height of the liquid level perspective ring on the liquid soap bottle is smaller than or equal to 1 / 4 of the height of the liquid soap bottle, so that a user can visually observe whether liquid soap needs to be supplemented or not without opening a bottle cap, the user can conveniently supplement the liquid soap in time, and normal use is prevented from being influenced by insufficient liquid soap.

The utility model discloses a novel backrest handle for protecting passengers, which belongs to the technical field of automobile seats and comprises a seat backrest, a handle, a handle blanking cap and a self-tapping screw. First holes are formed in two ends of the handle, a strip is arranged on the handle blanking cap, a second hole is formed in the end part of the strip, the handle is fixed on the seat backrest through a self-tapping screw, the self-tapping screw sequentially penetrates through the second hole and the first hole, and the handle blanking cap is in interference fit with the handle; the handle assembly is made of rubber materials, on the basis of meeting the requirements of Fanjin laws and regulations, the handle assembly is easy and convenient to install, soft and comfortable in material, good in manufacturability and capable of meeting the requirements of the GB 13057 standard and relieving injuries to the heads of passengers in the back row, the handle assembly is high in structural stability, the key size is easy to guarantee, and the handle assembly can be applied to follow-up platform type development of passenger car handle assemblies. The passenger car seat is suitable for passenger cars with passengers.

This invention relates to the field of heat insulation sheet technology and discloses a flame-retardant aerogel heat insulation sheet, comprising a heat insulation sheet body. The heat insulation sheet body has, from the outside to the inside along its thickness direction, a surface protective layer, a flame-retardant functional layer, an interface reinforcement layer, a core composite layer, and a bottom protective layer. Each layer is formed into an integrated structure through a gradient composite process. The core composite layer is made of aerogel powder and glass fiber composite. This flame-retardant aerogel heat insulation sheet, through the synergistic design of multiple physical layers, achieves deep composite of aerogel powder and glass fiber. Combined with a functional interface layer, a flame-retardant layer, and an installation adapter structure, it achieves comprehensive performance of "high heat insulation, strong flame retardancy, shatter resistance, and easy assembly," adapting to the heat insulation protection and insertion installation requirements of new energy lithium battery modules, effectively preventing the spread of thermal runaway and improving the safety of lithium battery use.

The present invention relates to a hidden battery type flat forklift beam composite tube, comprising a beam tube, a battery compartment is formed in the tube cavity of the beam tube, and the characteristic is that: flat fork tubes are formed on both side walls of the tube cavity of the beam tube, and the flat fork tubes on both sides include an internal section located in the beam tube and an external section extending outside the beam tube. The hidden battery type flat forklift beam composite tube of the present invention has a scientific and reasonable structural design, can effectively improve the strength of the hidden battery type beam tube, and is easy to install and use, while increasing the service life of the battery control line and improving the safety of battery use.

This invention belongs to the field of lithium metal battery technology, specifically relating to a fluorinated phase-separated polymer ion gel electrolyte, its preparation method and application, and lithium metal batteries. The fluorinated phase-separated polymer ion gel electrolyte provided by this invention comprises a solid phase and a liquid phase; the solid phase is a copolymer of a fluorinated acrylate monomer and a crosslinking agent containing carbon-carbon double bonds; the liquid phase comprises an ionic liquid and a lithium salt dissolved in the ionic liquid. Compared to liquid electrolytes and traditional SPEs, the fluorinated phase-separated polymer ion gel electrolyte provided by this invention has high ionic conductivity, mechanical strength, interfacial stability, and safety. It can effectively suppress the growth of lithium dendrites and adapt to large volume changes, avoiding short circuits and thermal runaway in lithium metal batteries under conditions of overcharging, over-discharging, or mechanical impact.

The utility model relates to a dual -purpose vehicle body structure and electric motor car, including non -cross type vehicle body and middle case, the non -cross type vehicle body includes the frame and with front pedal of detachable connection of frame, the middle case is used for with detachable connection of frame, the middle case sets up in the area of frame for accommodating the leg portion, forms cross type vehicle body, the middle case includes the box and the box cover, be equipped with the storage space in the box, the box cover is used for opening or closing the box, the utility model discloses the detachable connection of middle case realizes cross type and non -cross type vehicle body's flexible switching, can adapt to different riding scene and user preference.