78results about How to "Improve quietness" patented technology

The invention provides a manipulator, a mechanical arm and cleaning equipment, and relates to the technical field of cleaning. The manipulator comprises a connecting part, a first flange and a plurality of clamping arms. The connecting part can comprise a shell and a driving device arranged in the shell. The first flange is rotationally connected with the connecting part, and the driving device is in transmission connection with the first flange and used for driving the first flange to rotate. The multiple clamping arms are arranged on the outer side of the first flange at intervals, one end of each clamping arm is rotationally connected with the first flange, an opening is formed in the end, away from the first flange, of each clamping arm, the driving device is in transmission connection with each clamping arm, and the driving device is used for driving the multiple clamping arms to be close to or away from each other so that the opening can be opened or closed. The rotation axis of the first flange is perpendicular to the plane where the opening is located. According to the mechanical arm, clamping and rotating actions can be achieved, the mechanical arm can enter some narrow spaces, the application scene is wide, and the problem that in the related technology, the application scene of a mechanical arm is limited can be solved.

The utility model discloses an electrical cabinet mounting base, which belongs to the technical field of electrical cabinets, and comprises a bottom frame plate and an electrical cabinet body located at the top of the bottom frame plate, the bottom of the bottom frame plate is provided with a supporting assembly, the interior of the bottom frame plate is provided with a limiting assembly, and the electrical cabinet body is detachably mounted on the bottom frame plate through the limiting assembly. According to the electrical cabinet mounting base, through cooperative use of square steel, sleeves, threaded rods and placing plates, bottom frame plates are adjusted to be in a horizontal state, meanwhile, the heights of the left and right adjacent bottom frame plates can be adjusted to be consistent, and through cooperative use of first movable blocks, telescopic rods, second movable blocks and springs, the bottom frame plates are buffered and supported, so that the mounting efficiency is improved. Vibration and noise transmission generated during operation of electrical equipment in the electrical cabinet body are reduced, the comfort and quietness of a working environment are improved, meanwhile, displacement of the electrical cabinet body when the electrical cabinet body is subjected to external impact is reduced, and potential safety hazards caused by overturning and collision of the electrical cabinet body are reduced.

The invention relates to the technical field of vacuum pumps, and discloses a non-contact vacuum pump driving method and device based on centrifugation and magnetic force transfer, the non-contact vacuum pump driving device comprises a motor, a bottom shell and a pump body, and the output end of the motor is connected with a shaft rod of the pump body through a connecting base; the moving frame is located in the bottom shell and connected with the spring; the outer sides of the magnetic ring and the connecting base are connected with a magnetic assembly, when the motor is not driven, the spring enables the moving frame to be located at the initial position, when the motor is driven, the magnetic assembly is opened under centrifugal force and gets close to the magnetic ring, the magnetic ring is driven by magnetic force to enable the moving frame to move, and at the moment, the sealing cover connected with the moving frame blocks the pressure relief opening of the bottom shell. The motor drives the connecting seat to rotate to generate centrifugal force to enable the magnet to be close to the magnetic ring, the magnetic force of the magnet is utilized to extrude the magnetic ring to achieve transmission and operation without mechanical contact, collision and abrasion between mechanical parts are reduced, then vibration and noise are reduced, the reliability of equipment is improved, the service life of the equipment is prolonged, and operation stability and quietness are improved.

The utility model discloses a casing and a motor, the casing comprises an inner casing, an outer casing and a first damping structure, the outer casing is sleeved outside the inner casing, the first damping structure is arranged between the inner casing and the outer casing, and the inner casing and the outer casing are arranged at an interval and are connected through the first damping structure. According to the technical scheme of the utility model, the technical problem of poor vibration and noise reduction effect of the existing motor vibration reduction mode is solved.

The invention discloses a self-repairing mute tire and a preparation method thereof, and relates to the technical field of tires, the self-repairing mute tire comprises a tire body, and a self-repairing rubber layer and a mute material which are sequentially attached to the inner wall of the tire body from inside to outside; the self-repairing adhesive layer is prepared from the following components: epichlorohydrin rubber, acrylate rubber, a rosinyl phenyl phosphine oxide isoxazolyl functional polymer, 4, 4-chloroformyl phenyl ether, a catalyst, 2, 2-bis [4-(4-aminophenoxy) phenyl]-1, 1, 1, 3, 3, 3-hexafluoropropane, trithiocyanuric acid, a filler, an accelerant TMTD (Tetramethylthiuram Disulfide) and an auxiliary agent; the rosinyl phenyl phosphine oxide isoxazolyl functional polymer comprises structural units introduced through a condensation polymerization reaction of the following monomers: glycerol triabietate, bis (4-carboxyl phenyl) phenyl phosphine oxide and 3, 5-isoxazoledicarboxylic acid. The tire is remarkable in self-repairing effect, good in mute performance, sufficient in performance stability and long in service life.

This utility model belongs to the field of drainage pipe technology, specifically relating to a PVC sewage drainage pipe with a noise reduction structure. It includes a floor slab layer, a shock-absorbing layer fixedly connected to the inner wall of the floor slab layer, a heat insulation layer fixedly connected to the inner wall of the shock-absorbing layer, reinforcing ribs fixedly connected to the inner wall of the heat insulation layer, a thermal insulation layer fixedly connected to the inner wall of the thermal insulation layer, an inner pipe fixedly connected to the inner wall of the thermal insulation layer, and multiple protruding rods fixedly connected to the inner wall of the inner pipe. A protective device for the drainage pipe is provided on the top of the floor slab layer. The protective device includes two protective plates, the bottoms of which are both located on the top of the floor slab layer. This utility model solves the problem that the noise reduction design of the device sacrifices the overall rigidity of the pipe material. While a softer material layer can effectively absorb sound energy, it has weak resistance to instantaneous external forces, making it prone to dents, cracks, or even breakage. This invention enhances rigidity and improves resistance.

The utility model discloses an air conditioner installation noise reduction assembly which comprises four noise reduction assemblies installed at the four corners of the bottom of an air conditioner unit body, and each noise reduction assembly comprises a bottom plate, a connecting plate fixed to the surface of the top of the bottom plate and connected with the side wall of the air conditioner unit body and a protruding plate fixed to the other side of the surface of the top of the bottom plate. A round hole for a bolt to penetrate through is formed in the convex plate; five damping and buffering assemblies are arranged in the bottom of the bottom plate, each damping and buffering assembly comprises a circular plate making contact with the ground and a rubber column fixed to the surface of the top of the circular plate, and a rubber ring arranged on the outer circle of the rubber column in a sleeving mode is fixed to the surface of the top of the circular plate. Through the design and structural layout of the components such as the bottom plate, the connecting plate and the convex plate, vibration conduction at the bottom of the unit is effectively isolated, and meanwhile, the damping buffer component is adopted to absorb and reduce noise generated by vibration, so that the noise reduction effect is achieved.

The utility model discloses a kind of anti-slip wire reinforcing rib square tubes with stretch hole structure, it is related to square tube field, including square tube body, the surface of square tube body is equipped with stretch hole at equal intervals, and square tube body surface is provided with wide hole, and square tube body inside is provided with support mechanism, and support mechanism provides support force for square tube, the surface of square tube body is provided with protection mechanism, and protection mechanism protects square tube body. The anti-slip wire reinforcing rib square tube with stretch hole structure, the surface of square tube body is equipped with stretch hole with the diameter of 4.5mm at equal intervals, the interval between adjacent stretch hole is multiple of 12.5mm, to effectively prevent the phenomenon of slippage;Meanwhile, the surface of square tube body is also arranged wide diameter hole with the diameter of 9.5mm at equal intervals, the interval of adjacent wide hole is multiple of 200mm, by the setting of such stretch hole structure, further enhance the effect of anti-slip.

The utility model relates to the technical field of efficient heat insulation and sound insulation composite wall boards, and discloses an efficient heat insulation and sound insulation composite wall board which comprises a connecting assembly, an outer board body assembly, a heat insulation and sound insulation assembly, a main machine body and an anti-seismic assembly. The heat and sound insulation assemblies are installed on the upper inner wall and the lower inner wall of the outer plate body assembly, the main machine body is installed between the heat and sound insulation assemblies, the anti-seismic assembly is installed in the main machine body, the anti-seismic assembly is arranged, riveting between wallboards and structural columns and beams is facilitated, the overall performance is stable, the net load of a building can be reduced, the structural safety coefficient of the building can be improved, and effective seismic prevention is achieved. The danger of collapse is avoided, the durability and long-term stability of the structure are improved, and the maintenance and repair cost is reduced; and the heat insulation and sound insulation assembly is arranged, so that sound transmission can be reduced, and the indoor quietness is improved.

The utility model relates to the technical field of composite doors and windows, in particular to a composite door and window with a noise reduction function, which comprises a composite door and window, a fixing frame is fixedly connected to the front side of the composite door and window, a noise reduction plate is slidably connected to the inner side of the fixing frame, and a plurality of threaded grooves are formed in the bottom of the noise reduction plate. According to the utility model, through the arrangement of the fixing frame, the noise reduction plate, the threaded groove, the mounting plates, the mounting holes, the mounting bolts, the handle, the fixing plate, the insertion grooves, the sliding grooves and the plug pins, when noise is generated outside, the wooden sound absorption plate and the polyurethane foam layer can absorb the noise outside; the hollow rubber bag can provide support for the polyurethane foam layer and further absorb noise, the polyester fiber sound insulation plate can isolate the noise, and the design of the noise reduction plate and the connecting component thereof can reduce vibration transmission so as to reduce the noise, so that the indoor quietness is improved.

The draught fan assembly comprises a mounting base, a draught fan and a connecting piece, the connecting piece is provided with a positioning structure, and the positioning structure is used for being matched with the mounting base and the draught fan so as to fix the draught fan and the mounting base to each other; and the connecting piece is made of an elastic material. According to the fan assembly, the connecting piece for connecting the fan and the mounting base is made of the elastic material, so that a flexible buffer structure is formed between the fan and the mounting base, vibration energy transmitted to the mounting base by the fan is attenuated, the influence of fan vibration on the mounting base is reduced, and the running quietness of the fan assembly is improved.

The invention discloses massage equipment with multiple valves and multiple air bags. The massage equipment comprises a massage control system and a mattress, the massage control system comprises a user instruction module, a signal receiving module, a control module and an execution module. The user instruction module is used for generating a control instruction in response to user operation; the signal receiving module is connected with the user instruction module to receive the control instruction; the control module is connected with the signal receiving module and generates a control signal according to the control instruction; the execution module comprises an air pump, a control air path and a plurality of massage air bag groups; the air pump is connected with the control module and executes on-off operation after receiving the control signal; the control air path is connected with the control module and the plurality of massage air bag groups, and is switched on and off after receiving the control signal so as to inflate or deflate the plurality of massage air bag groups; and the plurality of massage air bag groups are respectively arranged in the mattress and above the position, corresponding to the bed head, of the mattress. The device has the functions of multi-mode massage, low-noise operation and thermal therapy.

The utility model relates to an independent front-back damping device for an automobile seat, which comprises a mounting base and a damping mechanism, sliding rails are respectively arranged on the left side and the right side of the mounting base, and the damping mechanism is arranged between the two sliding rails; the shock absorption mechanism comprises a spring shock absorption support, a spring assembly, a damping shock absorption support and a damping assembly, and the spring shock absorption support and the damping shock absorption support are arranged on the left side and the right side of the mounting base correspondingly and are close to the corresponding sliding rails. The spring shock absorption support and the damping shock absorption support are fixedly connected through connecting shafts arranged on the front side and the rear side, the spring assembly is arranged on the spring shock absorption support, and the damping assembly is arranged on the damping shock absorption support. The independent module mechanism can effectively absorb vibration impact generated by road bumping, front-back acceleration generated during uphill and downhill vibration impact and the like, and provides smoothness and comfort for the seat.

The present invention discloses a fan assembly with a noise reduction function, comprising a fan housing, a fan arranged in the fan housing, and an air duct having an air inlet and an air outlet and connected to the fan housing; at least two layers of silencing substrates are arranged in the air duct, which are spaced from each other and extend along the wind direction in the air duct, and the silencing substrate has a plurality of groups of silencing units continuously arranged along its extension direction, and a control mechanism is provided to control the protrusion degree of at least part of the silencing units relative to the silencing substrate, so that the silencing substrate is in a silencing state, and a plurality of groups of silencing units constitute a waveform structure that offsets noise sound waves. The present invention also discloses an integrated stove having the fan assembly, and a noise reduction control method based on the fan assembly. The beneficial effect of the present invention is that the waveform structure formed by the silencing substrate offsets the noise waveform, thereby achieving the effect of noise regulation.

This application discloses an exhaust assembly and a vehicle for a fuel cell vehicle. The exhaust assembly includes an exhaust pipe, a muffler, and a damping pipe. The exhaust pipe is adapted to be installed on the vehicle body. One end of the exhaust pipe has an outlet end, and the other end has an inlet end. A muffler section is formed in the exhaust pipe. The muffler is disposed on the exhaust pipe and on the outer periphery of the muffler section, communicating with the internal cavity of the muffler section. The damping pipe is connected to the exhaust pipe and is disposed near the inlet end of the exhaust pipe, and / or at the junction of the exhaust pipe and the muffler section. At least a portion of the damping pipe is constructed as a flexible element or a flexible unit covering the exhaust pipe is disposed inside the damping pipe, which can improve the muffler and vibration reduction capabilities and reduce vehicle noise.

This utility model relates to the field of aerodynamic drive equipment technology, and in particular to an ultra-quiet air compressor, including an air tank and a compressor unit. The compressor unit is fixed in the space formed by the sealing cover and the top of the air tank. An air intake channel is provided in the middle of the air tank, penetrating the air tank and extending to the inner end of the sealed space. The air storage chamber of the air tank and the air intake channel are relatively sealed. The compressor unit is completely sealed in the sealed space, and the noise generated by the compressor unit is completely contained within the sealed space, significantly reducing the noise outside the sealed space. The air drawn in by the compressor unit first enters the sealed space from the bottom of the air tank through the air intake channel, and then the compressor unit draws the air from the sealed space into the air tank. This air extraction process not only improves the heat dissipation of the compressor unit, allowing cool air to enter the sealed space from the bottom through the air intake channel, but also effectively solves the problem of noise leakage, resulting in lower overall noise and better quietness.

The utility model relates to the technical field of stage lamp equipment, in particular to an immersed efficient radiating stage lamp, which comprises a bottom case, a support arm pivoted on the bottom case and a lamp holder pivoted on the support arm, and further comprises a radiating mounting box and an electronic element used for mounting a switching power supply of the stage lamp, which are positioned in the bottom case, the dielectric cooling liquid is stored in the heat dissipation mounting box and absorbs working heat of the stage lamp power supply by soaking electronic elements of the stage lamp power supply; the cooling module is positioned outside the heat dissipation mounting box; the circulating heat absorption pipe is internally provided with a circulating flowing refrigerant; the refrigerant in the circulating heat absorption pipe absorbs heat of the dielectric cooling liquid and transmits the heat to the cooling module. According to the immersed phase-change cooling switching power supply and the stage lamp, the heat dissipation efficiency of the switching power supply can be effectively improved, the heat dissipation requirement of the high-power switching power supply of the stage lamp can be met, and the mute effect is good.

The air conditioner comprises an air inlet cavity and an air outlet cavity, the air inlet cavity comprises an air inlet, the air outlet cavity comprises a first air outlet, the air inlet and the first air outlet are located on the same side (for example, the lower side) of the air conditioner, and the first air outlet is located at a position of the air outlet cavity away from the air inlet cavity, and a heat exchanger is arranged in the air outlet cavity; in the arrangement direction of the air inlet cavity and the air outlet cavity, the distance between the first edge of the heat exchanger and the second edge of the air inlet cavity is recorded as a first size, the size of the air outlet cavity is recorded as a second size, the ratio of the first size to the second size is greater than or equal to 0.10 and less than or equal to 0.20, and the ratio of the size of the first air outlet to the second size is greater than or equal to 0.20 and less than or equal to 0.32, so that the relationship among the first size, the second size and the size of the first air outlet can be better balanced, thereby realizing a more reasonable space layout, making the size of the heat exchanger more optimal, and better improving the heat exchange effect of the entire air conditioner.

The invention relates to a mechanical arm and a medical trolley. Comprising a first arc-shaped joint which is provided with a first arc-shaped track and a first central axis perpendicular to the plane where the first arc-shaped track is located; the first arc-shaped joint comprises a first arc-shaped arm and a second arc-shaped arm, and the second arc-shaped arm and the first arc-shaped arm are movably connected along a first arc-shaped track; and the second arc-shaped joint is provided with a second arc-shaped track and a second central axis perpendicular to the plane where the second arc-shaped track is located, the second central axis and the first central axis intersect at the virtual motion center, and the second arc-shaped joint is movably connected with the second arc-shaped arm along the second arc-shaped track. The motion center can be kept unchanged, the control stability of the motion center can be improved, and the control error of the motion center is reduced.

The utility model discloses a lightweight concrete building wall which comprises a concrete wall body, and a composite mechanism is positioned and installed in the concrete wall body. The composite mechanism comprises a positioning connecting groove, an inserting positioning groove, a positioning frame, a connecting frame, a positioning triangular groove, a connecting fixing frame, a flexible sealing gasket, a triangular positioning clamping block, a heat preservation layer, a sound insulation layer, a fireproof layer and a waterproof layer. According to the lightweight concrete building wall, through the arranged composite mechanism, the positioning frame is inserted into the inner side of the insertion positioning groove, and the connecting frame at the upper end of the positioning frame and the inner wall of the positioning connecting groove are fixed through bolts; the connecting fixing frame is positioned on the inner side of the positioning frame through clamping of the triangular positioning clamping blocks, and the heat preservation layer, the sound insulation layer, the fireproof layer and the waterproof layer are arranged on the inner side of the connecting fixing frame, so that the performance in all aspects can be enhanced, the overall stability and firmness of the wall body can be improved, and the risk that the wall body cracks and falls off is reduced.

The utility model discloses a human body self-adaptive seat controller, which comprises an upper shell and a lower shell, a PCB (Printed Circuit Board) is arranged between the upper shell and the lower shell, the PCB is provided with an MCU (Microprogrammed Control Unit) core module, an electromagnetic valve group, a communication module and a driving circuit, and the human body self-adaptive seat controller further comprises a noise reduction structure; the communication module and the driving circuit are respectively connected with the MCU core module, and the electromagnetic valve group is connected with the driving circuit; the MCU core module is configured to execute a preset program to output a control instruction for controlling the human body self-adaptive seat; the noise reduction structure comprises an air valve noise reduction cushion arranged between the upper shell and the PCB and a contact vibration blocking pad arranged on the outer side of the upper shell. The human body self-adaptive seat controller has a series of advantages of low noise, high integration level, high reliability, self-adaptive adjustment and the like.

The utility model provides a kind of drive axle half shaft connecting frame structure convenient to install, it is related to drive axle half shaft connecting frame structure technical field, including connecting frame main body, the side of connecting frame main body is equipped with first connector, it is equipped with locating bolt in the side of first connector, the inside of first connector is equipped with angle regulator, the side of angle regulator is equipped with fastening bolt, the side of angle regulator is equipped with elastic buffer pad, the side of angle regulator is equipped with fastening bolt, after installing elastic buffer pad, absorption vibration, reduce transmission noise, the two sides of connecting frame main body are respectively equipped with first connector, second connector, third connector, fourth connector, and all with the two sides of connecting frame main body are connected using thread, so when there is slight manufacturing or installation deviation between drive axle and half shaft, angle regulator can be compensated and corrected, ensure the reliability of connection, prolong the service life of half shaft and connector.

The application provides an air outlet structure and a vehicle. The air outlet structure comprises a shell, a damper, a button, a connecting assembly and a buffer assembly. An air outlet channel is formed in the shell. The damper is rotatably arranged in the air outlet channel. The button is slidably mounted on the shell. The connecting assembly connects the damper and the button. The button is provided with a rack. The buffer assembly comprises a damping gear. The damping gear is engaged with the rack. The air outlet structure and the vehicle can improve the operation feeling and reduce abnormal sound.

The invention belongs to the technical field of magnetic suspension synchronous motors, and particularly relates to a magnetic suspension permanent magnet synchronous motor heat dissipation structure which comprises a shell, a stator part, a rotor part, a front end cover plate, a rear end cover plate, an air inlet and an air outlet, the front end cover plate and the rear end cover plate are connected to the two sides of the shell in the length direction respectively, the air inlet is formed in the rear end cover plate, and the air outlet is formed in the rear end cover plate. The rear end cover plate is provided with a first heat dissipation hole and a second heat dissipation hole, the second heat dissipation hole is connected with a heat dissipation channel, the heat dissipation channel is arranged in the shell, the position, close to the front end cover plate, of the heat dissipation channel is connected with a front end air outlet hole, the air outlet is formed in the shell, and the air outlet is connected with a one-way valve. Compared with the prior art, the heat dissipation area of the shell can be increased, internal cold air circulation is smoother, the heat dissipation efficiency is improved, and the size of the motor is reduced through the built-in heat dissipation channel.

The embodiment of the utility model relates to the technical field of vehicles, and discloses a windscreen wiper shaft assembly and a vehicle, the vehicle is provided with a ventilation cover plate, the ventilation cover plate is provided with a mounting hole, and the windscreen wiper shaft assembly is rotatably arranged in the mounting hole in a penetrating mode and comprises a windscreen wiper shaft, a windscreen wiper shaft and a windscreen wiper shaft, the windscreen wiper shaft is sleeved with the sealing structure, the sealing structure is arranged between the windscreen wiper shaft and the hole wall of the mounting hole, and the sealing structure and the windscreen wiper shaft are connected and rotate synchronously. According to the windscreen wiper shaft assembly, a gap can be prevented from being generated between the sealing structure and the windscreen wiper shaft, water is prevented from flowing to the motor from the gap between the sealing structure and the windscreen wiper shaft along the windscreen wiper shaft, and the sealing performance and the waterproof performance are improved. Meanwhile, noise generated when airflow from the air inlet grille passes through a gap between the sealing structure and the windscreen wiper shaft can be avoided, noise generated when the sealing structure and the windscreen wiper shaft rub each other can be avoided, and quietness is improved.

The embodiment of the present invention relates to the technical field of nuclear power systems, and provides a nuclear power generation system and a nuclear power device. The nuclear power generation system includes a reactor, a hydrogen production reactor and a fuel cell; the reactor is connected to the hydrogen production reactor through a cooling medium circulation pipeline, and a circulation pump is installed on the cooling medium circulation pipeline, so that a cooling medium closed circulation system is formed between the reactor and the hydrogen production reactor; the hydrogen output end of the hydrogen production reactor is connected to the hydrogen inlet of the fuel cell, the oxygen output end of the hydrogen production reactor is connected to the oxygen inlet of the fuel cell, and the power supply terminal of the fuel cell is used to be electrically connected to the input end of the power consumption mechanism. The nuclear power generation system provided by the embodiment of the present invention changes the traditional energy conversion form of nuclear energy to mechanical energy, cancels the main noise source equipment such as steam turbine units or steam turbine generator units, reduces the operating noise of the nuclear power system, and improves the quietness and comfort of nuclear-powered ships.

The utility model provides a kind of shock-absorbing base for automobile air conditioner electromagnetic clutch, including air conditioner compressor, mounting bracket, shock-absorbing base, electromagnetic clutch, driving belt and clutch shock-absorbing seat, wherein: mounting bracket is fixedly installed in the outside of air conditioner compressor, and mounting bracket is fixedly installed in the inside of vehicle body, and the surface of air conditioner compressor is fixedly installed in the shock-absorbing base;The electromagnetic clutch is installed in the front end of air conditioner compressor, and driving belt is engaged in the outside of electromagnetic clutch, and the shock-absorbing seat of clutch is fixedly installed above shock-absorbing base;The utility model shock-absorbing base and the setting of clutch shock-absorbing seat can play better shock-absorbing capacity, and can be targeted to the shock-absorbing of multiple positions.

The present invention relates to the technical field of metal-based composite materials, and in particular to a production process of an environmentally friendly sound-proof composite material, comprising the following components: PE polymer material, metal sheet, bio-based polyester fiber, phase change material microcapsule, nano-silicate, conductive filler, cross-linking agent, plasticizer, adhesive. The present invention provides an environmentally friendly, high-performance, multifunctional sound-proof composite material. Biodegradable materials are selected to save energy and reduce emissions, and the composite material has excellent soundproofing, strength, durability, smooth surface, high hardness, good soundproofing effect, and is also anti-corrosion, anti-aging, heat-resistant, and fire-resistant. The surface meets food-grade standards and is widely used, with broad application prospects and significant social and economic benefits.

The invention discloses a milk mixing device capable of rapidly cooling, which comprises a shell and a placing bin, and also comprises an annular shell which is sleeved outside the placing bin and is communicated with the placing bin through a plurality of air outlets; the fan is mounted in the shell, and an air outlet communicates with the annular shell through an air duct; the dust filtering unit is detachably installed at the bottom of the shell and connected with an air inlet of the fan, dust in airflow is filtered through the cylindrical filter element, in daily use, the airflow enters the fan after being filtered through the cylindrical filter element, dust is prevented from being attached to fan blades of the fan, and noise caused by the fact that balance is affected when the fan rotates is prevented; and bacteria and microorganisms in dust which is bred on the fan blades and accumulated on the fan blades may threaten the health of the baby.