37results about How to "Stable ventilation" patented technology

The invention discloses a white tea cutting medium. The white tea cutting medium is prepared from modified vermiculite, modified bentonite, river sand, low moor peat, bark of Melia azedarach L. and a solution of tea-oil tree fruits. Matter of different ingredients is matched according to the growth characteristics of tea, and the prepared medium is excellent in comprehensive physical and chemical property, can be repeatedly used and can increase the survival rate of cutting slips and improve the growth vigor of seedlings. The bred cutting slips can be easily taken out, the risk of root system damage is lowered, planting in the later period is facilitated, and high use value is achieved.

The invention discloses a railway vehicle and a railway vehicle ventilating device. The railway vehicle ventilating device comprises an air inlet cylinder, a first air opening and a second air openingare formed in the side faces of the air inlet cylinder, a top air opening is formed in the top of the air inlet cylinder, an air outlet is formed in the bottom of the air inlet cylinder, the first air opening and the second air opening are oppositely formed, and in a free state, the top air opening, the first air opening, the second air opening and the air outlet communicate; a first flow-guidingplate, a second flow-guiding plate and a connecting rod hinged between the first flow-guiding plate and the second flow-guiding plate are arranged in the air inlet cylinder, the top of the first flow-guiding plate is hinged to the position, on the upper part of the first air opening, of the air inlet cylinder, the top of the second flow-guiding plate is hinged to the position, on the upper part of the second air opening, of the air inlet cylinder, the first flow-guiding plate and the second flow-guiding plate constitute a trapezoidal connecting rod structure through the connecting rod, the upper end of the trapezoidal connecting rod structure is a large-diameter end, and the second flow-guiding plate can swing to the state of sealing the second air opening. According to the railway vehicle ventilating device, the angle between each flow-guiding plate and the corresponding air opening is adjusted according to the change of the vehicle speed, and the ventilating quantity can be ensuredduring high-speed operation of the vehicle.

A dust collection unit 20 that ventilates a main unit 10 during blasting work and a ventilation unit 30 that ventilates a main unit during a painting step are provided by a blasting chamber. A side wall 11 of the main unit is provided with an entrance 11a and an opening-and-closing member 11b that opens / closes the entrance, the dust collection unit is provided so as to project from a roof panel 15 to a floor panel 16 at a position closer to an other side wall 12 that is opposed to this side wall so as to partition the interior of the main unit, and a working space 10a and a ventilation duct 10b are defined in the main unit. A roof panel 15 above a working space has air suction holes 17 formed therein, and an intake opening 22 that communicates between the dust collection unit and the ventilation duct is provided. The side wall is provided with an opening 12a that communicates between the ventilation unit and the ventilation duct, and during the blasting process, ventilation is conducted with the dust collection unit with the entrance closed, and during painting, ventilation is conducted with the ventilation unit with the entrance opened.

The invention discloses an air inlet device automatically blocking passive airflow and an air conditioner host and belongs to the field of ventilation equipment. The air inlet device automatically blocking the passive airflow comprises a frame (1) and a plurality of vanes (2) which are fixed into the frame (1), wherein the multiple vanes (2) are arranged in parallel, and the windward sides of thevanes (2) are inwards-concaved arc-shaped faces. The air conditioner host comprises a host shell (5), the host shell (5) is provided with an air inlet, and the multiple vanes (2) are arranged at the position of the air inlet. According to the air inlet device automatically blocking the passive airflow, the vanes (2) are manufactured into acceleration arc-shaped faces or V-shaped faces, the direction of wind is changed on the surfaces of the vanes and advances in an arc acceleration manner, and turbulent flow is formed between every two adjacent vanes; external cold air cannot directly blow fins without active inlet air suction force when an air conditioner is not turned on, and the defrosting speed is accelerated; and when a draught fan is started, the external air flow enters the host under the action of draught fan suction force, and therefore active air inlet is achieved. The air inlet device automatically blocking the passive airflow can be applied to all fields needing stable ventilation.

The invention discloses a ceramic grinding body ball mill. The ceramic grinding body ball mill comprises a charge device, a discharge device, a cement mill and a transmission device, wherein a bin separating plate is arranged in the cement mill for separating an inner cavity of the cement mill into a first bin body close to the charge device and a second bin body close to the discharge device; ceramic grinding bodies of different grades are separately arranged in the first bin body and the second bin body; the bin separating plate comprises a charge grid plate, a discharge grid plate, a plurality of lifting plates and a central circular material-passing cone; a sorting bin is formed between the charge grid plate and the discharge grid plate; the central circular material-passing cone extends into the second bin body from the inner part of the sorting bin; and one end of each lifting plate is connected with the central circular material-passing cone, and the other end of each lifting plate is spaced with a barrel body of the cement mill. The ceramic grinding body ball mill adopts a ceramic grinding body, can reduce weight of the ball mill, and reduces energy consumption of the ballmill; andthe central circular material-passing cone is arranged, so that an empty material region is not formed after materials in the cement mill pass through the bin separating plate, and the materials are easily dispersed uniformly, and therefore, grinding efficiency is improved, and ventilation of the system tends to be stable.

The invention relates to the field of grain warehousing equipment, in particular to a granary having good ventilation effect. The granary comprises a granary body, the top of the granary body is connected with a transverse plate, a driving mechanism is mounted on the transverse plate, an output end of the driving mechanism is connected with a gear-rack mechanism, the other end of the gear-rack mechanism is connected with a lifting rod, the other end of the lifting rod is connected with an air blower, a ventilation pipe is mounted in the granary body, a plurality of ventilation holes are formedin the ventilation pipe, and the air blower and the lifting rod are arranged in the ventilation pipe in a sleeved manner. The granary can fully ventilate grain, so that the problem of grain rotting caused by obstructed ventilation of existing granaries is solved.

The invention relates to a drainage system (10), in particular for a water trap of a fuel or oil filter comprising a filter housing element (12) with a drain hole (14) for fluidly connecting an inside(18) of the housing element (12) with an outside (20) of the housing element, a drain plug (26), and a sealing ring (28) seated on the drain plug (26) for a fluid-tight closure of the drain hole. Thedrain plug is provided with a drain channel (46) and a ventilation channel (56). The sealing ring sealingly abuts against the housing element (12) in an axial and a radial direction when the drain plug (26) is positioned in its closing position; upon an axial movement of the drain plug (26) from the said closing position into a drainage position, a radially inward edge portion (70) of the sealingring (28) is dislodged from its axially sealing abutment against the filter housing (12) by the drain plug (26) while a sealing abutment of an outer edge portion (66) of the sealing ring (28) againstthe housing element (12) and a sealing abutment of a radially inward edge portion (70) of the sealing ring (28) against the drain plug (26) is maintained such that the drain hole is fluidly connectedboth to the inlet opening (48) of the drain channel (46) and the second orifice (60) of the ventilation channel (56).

The invention relates to a trachea cannula device for the respiratory medicine department. The trachea cannula device for the respiratory medicine department comprises a handheld plate, the handheld plate is provided with a sleeving structure used for being inserted into a human organ so as to facilitate ventilation of a patient, and the sleeving structure is connected with the handheld plate through a driving mechanism. The tracheal intubation device for the respiratory medicine further comprises an inflation ring which is arranged on the sleeving structure and used for preventing air leakage, and the inflation ring is connected with an air supply assembly used for inflating the inflation ring. When the device is used, the posture of a patient is adjusted, a medical worker inserts the device into the mouth of the patient through a handheld plate, and a driving mechanism works; then the sleeving structure is driven to move, so that good ventilation of a patient in the operation period is guaranteed; in the movement process of the sleeving structure, the power mechanism is triggered to move and drives the air supply assembly to move, and therefore the air supply assembly inflates the air inflation ring, and the stable ventilation state is kept.

The invention provides a cigarette with a visible explosion bead and air permeability, which comprises a filter tip, a cigarette and tipping paper, wherein the tipping paper is used for tipping the filter tip and the cigarette, the cigarette consists of tobacco shreds wrapped by cigarette paper, the filter tip consists of a filter element wrapped by transparent paper, the filter element comprisestwo filter element assemblies and a hollow section which is positioned between the two filter element assemblies and contains the explosive bead, the outer layer of the transparent paper wraps the tipping paper, a part of the tipping paper, positioned in the hollow section, is hollowed out to form a transparent window, the tipping paper is provided with a plurality of air holes in a surrounding manner at the joint of the filter tip and the cigarette or at the part covering the cigarette, and the air holes are formed by punching the tipping paper inwards until the tipping paper penetrates through the cigarette paper and is communicated with the tobacco shreds. According to the invention, the air holes are arranged on the part of the tipping paper covering the cigarette, the part avoids thetransparent paper part of the filter element, and the punching process is easy to achieve, so that the punching on the cigarette with the explosive bead is conveniently achieved, and the tar content is effectively reduced.

The invention relates to an automated greenhouse used for producing agricultural products. The automated greenhouse comprises a base, a main body and a sweeping mechanism; an air guide mechanism and two ventilation mechanisms are arranged in the main body, the air guide mechanism comprises a rotary shaft, a speed adjusting assembly, two blades, two casing pipes and two suspension rods, and the speed adjusting assembly comprises a translation unit, a connecting block, a first motor, a driving block and a turntable; the sweeping mechanism comprises a sweeping frame, two movable assemblies and several sweeping assemblies; each sweeping assembly comprises a swinging rod, a steering unit, a connecting plate, a spring, a sweeping plate and two orienting rods. According to the automated greenhouse used for producing the agricultural products, through the sweeping mechanism, accumulated snow on the main body can be swept away, so that the good light transmittance of the main body is restored,and photosynthesis is facilitated; moreover, according to the flow rate of external air, the air guide mechanism automatically adjusts the rotary speed of the blades, so that stable ventilation insidethe main body is kept, carbon dioxide is supplemented while moisture is conveniently discharged, the growth of plants is promoted, and the practicability of the automated greenhouse is improved.

The invention provides a roadway tunneling construction method for a coal mine overpass air bridge, and relates to the technical field of mine roadway tunneling. The method comprises the following steps that A, a foundation trench is excavated in an upper roadway according to an overpass position calibrated by mine geodesic survey; B, transverse I-shaped steel is laid at the bottom of the foundation trench, and a first longitude and latitude net is laid above the I-shaped steel; C, longitudinal I-shaped steel is laid above the first longitude and latitude net, and the transverse I-shaped steeland the longitudinal I-shaped steel are welded and fixed through anchor rods; D, a second longitude and latitude net is laid above the longitudinal I-shaped steel, and the two layers of longitude andlatitude nets are fixedly connected through iron wires and anchor rods; E, after concrete is poured into the foundation trench to manufacture an upper roadway false bottom, a lower roadway is tunneled; F, a steel plate is laid above an I-shaped steel frame shed of the lower roadway after the lower roadway is tunneled and passes through the overpass position; and G, the two side faces of the lowerroadway are subjected to side face expansion, wall building is carried out, and concrete is poured to manufacture a lower roadway false roof. The method simplifies the air bridge tunneling construction procedure, also can effectively prevent air escape branches, and roadway support is safer and more stable.

The invention belongs to the technical field of optical lens production, and discloses a fully-automatic cleaning, hardening and drying system and method. The system comprise a feeding section, a saponification section, a cleaning section, a dehydration and cooling section, a first strengthening section, a pre-drying and cooling section, a second strengthening section and the like. According to the invention, products can be recognized through code scanning, a machining process is automatically selected, and the products of different types and sizes can be continuously and automatically machined in the system. Electric energy loss can be reduced, and the utilization rate of electric energy is improved. Intelligent detection and control, such as heating, ultrasonic treatment, water circulation and drying, are set; the system is started only when a product needs to be machined, and the system is stopped in idle time, so an electricity saving function can be achieved; and water consumption can be reduced, the flow of internal circulation is employed for flushing products at a flushing station, and a small amount of fresh water can be supplemented only when products are being machined.Besides, an overflow mode is adopted for washing water, fresh water is only supplemented in a rear section, and water in the rear section overflows to a front section in sequence, so the water consumption of the cleaning section is greatly reduced.

The invention relates to a withdrawal working face flexible shield type reserved return air passage and a manufacturing method thereof. The passage includes several I-beams, wire ropes, U-shaped clamps and anchor nets and is located at an entrance of the withdrawal passage between a working face and a coal wall, supports are laid on the coal wall, an upper end of each I-beam is fixed on the support of the coal wall, a lower end of each I-beam is fixed on the ground of the withdrawal passage, each of the I-beams forms an acute angle with the coal wall, the I-beams are respectively parallel to each other, an outer side of each I-beam is connected with multiple wire ropes, one end of each of the wire ropes is connected with the outermost I-beam, the wire ropes pass through each of the I-beams, the connection portion of each wire rope and each I-beam is fixed through one U-shaped clamp, the other end of each of the wire ropes is fixed on a corresponding anchor rod of the coal wall, the steel wire ropes are parallel to each other and parallel to the ground of the withdrawal passage, a layer of anchor nets is laid on the steel wire ropes and the I-beams, and the anchor nets are fixed onthe wire ropes and the I-beams through wires.

A partition type ventilator comprises an axial flow impeller, a motor driving the axial flow impeller, and a shell surrounding the axial flow impeller and installed at external wall holes and further comprises a control device for the motor. The control device comprises a switch, a detection circuit and a control circuit, wherein the switch is used for controlling the mode of connecting a motor winding to a power supply, the detection circuit is used for measuring the winding voltage when the motor winding is disconnected from the power supply, and the control circuit is used for driving the switch according to the measurement result of the winding voltage and prescribed process. The partition type ventilator installed on an external wall can adapt to the impact of outdoor wind better when ventilating air toward the outdoor. Compared with a conventional partition type ventilator, the partition type ventilator has the advantages of being more energy-saving and more stable in ventilation.

The invention provides a lift decorative ceiling device. The lift decorative ceiling device comprises a front top core and a back top core and can move back and forth along a front support and a backsupport under the action of air, and the front top core and the back top core can move oppositely or away from each other to change the distance between two ventilating frames to allow a ventilating port between the two ventilating frames to become large or small; and the sections of the front support and the back supports are concaved, one surface of each frame is open to form a groove to accommodate and connect the front end of the front top core, the front support and the back support are pushed by a micro cylinder, a cylinder end of the micro cylinder is fixed to the bottom surface of thegroove, the micro cylinder is horizontally arranged, and a cylinder piston rod end of the micro cylinder is connected with one end of the front top core.

The invention discloses a method for constructing a high-yield tree shape of central leading branches of citrus fruit trees, including a method for constructing a tree shape of a juvenile tree and a method for constructing a tree shape of an adult tree. The adult tree of the year adopts the method of artificial intervention; the construction method of the tree form of the juvenile tree is to guide the growth of the branches of the juvenile tree. Through directional cultivation of central guide branches, artificially manufacture main trunk branches, upright branches or central branches, increase the thickness of fruiting branches, cultivate more powerful branches, enhance the bearing capacity of fruiting branches, and increase their ability to bear force. Supports can be reduced. In the past, some tree-shaped structures often paid too much attention to the purpose of the economic characteristics of the results. Some fruit trees have slender fruiting branches and rely on external force support in the later stage of fruiting.

The invention provides a detachable and washable diatomite microporous water aerator. A disc-shaped upper casing and a lower casing are buckled to form a cavity, flanges are arranged on the outer edges of the upper casing and the lower casing, flange holes are formed in the circumference of the flanges, the flanges of the upper casing and the lower casing are fixed and integrally combined throughfastening screws, a sealing gasket is placed between the flanges, and a gas connecting pipe is assembled in the middle of the upper casing through an upper lock nut and a lower lock nut. The upper casing and the lower casing are made of diatomite ceramic. The water aerator is made by combining the upper and lower casings, so that both the upper casing and the lower casing can realize ventilation and aeration, and the upper and lower casings can be dismounted through the fastening screws for inside and outside cleaning to keep stable ventilation capacity. The diatomite ceramic has micropores, so that the diatomite ceramic has good breathability and fine bubbles, the contact area of air and water is large, bubbles are stable, and the dissolved oxygen content is high. The diatomite microporous water aerator is suitable to be used for aquaculture.

The invention discloses a high-lift lock integrated plane valve. A positive side, a negative side and a bottom edge of the plane valve are closed by steel plates, and when the valve is opened, the negative side of the valve and a lintel form a fixed gap; the plane valve adopts a variable section, in other words, the structure of the positive side of the valve is thick in the middle and thin on two sides, and the two sides incline inwards to form acute angles with a vertical plane; and the bottom edge of the plane valve adopts an acute edge and trends to the upstream to form an acute angle with a horizontal plane. The structure of a valve body is beneficial for smoothness of natural ventilation of the lintel and stability of ventilation volume, cavitation of a valve groove is avoided, deformation of the valve is reduced, the plane valve is far away from a water current excitation frequency domain, valve opening force and pulsation thereof are remarkably reduced, and the bottom edge is less prone to separatory cavitation.

A method for controlling a rotational speed of a fan ( F ) includes using a control unit (1) to start a motor (2) according to an initial duty cycle value ( D ). In a first constant speed step ( S1 ), the duty cycle value ( D ) is changed to make a motor rotational speed ( R ) equal to a first target rotational speed ( R1 ). When the duty cycle value ( D ) and a first target duty cycle value ( D1 ) satisfy a first relational expression, the motor rotational speed ( R ) is compared with a second target rotational speed ( R2 ), and the duty cycle value ( D ) is changed to make the motor rotational speed ( R ) equal to the second target rotational speed ( R2 ). When the duty cycle value ( D ) and a second target duty cycle value ( D2 ) satisfy a second relational expression, the first constant speed step ( S1 ) is performed. A fan ( F ) is also disclosed.

The invention discloses a rail vehicle and a ventilation device for a rail vehicle. The ventilation device includes an air inlet tube, the side of the air inlet tube is provided with a first air port and a second air port, the top is provided with a top air port and the bottom is provided with an air outlet, and the first The air outlet and the second air outlet are set opposite to each other. In the free state, the top air outlet, the first air outlet, the second air outlet and the air outlet are connected; The connecting rod between the baffle and the second baffle, the top of the first baffle is hinged on the air inlet cylinder at the position above the first air outlet, the top of the second baffle is hinged on the air inlet cylinder and located at the first At the position above the second air outlet, the first air guide plate and the second air guide plate form a trapezoidal connecting rod structure through the connecting rod and the upper end is a large diameter end, and the second air guide plate can swing to the state of sealing the second air outlet. In the ventilation device, the angle between the deflector and the corresponding air outlet is automatically adjusted according to the change of the vehicle speed, and the ventilation volume can be ensured when the vehicle is running at high speed.

The invention discloses a fan and a rotational speed control method thereof, and aims to solve the problem that in the prior art, the rotation speed of a fan is controlled based on the calculation ofwork current of a motor. A method for controlling a rotational speed of a fan includes using a control unit to start a motor according to an initial duty cycle value. In a first constant speed step, the duty cycle value is changed to make a motor rotational speed equal to a first target rotational speed. When the duty cycle value and a first target duty cycle value satisfy a first relational expression, the motor rotational speed is compared with a second target rotational speed, and the duty cycle value is changed to make the motor rotational speed equal to the second target rotational speed.When the duty cycle value and a second target duty cycle value satisfy a second relational expression, the first constant speed step is performed. The rotational speed control method can be applied to a fan.

The invention discloses a low-wind-resistance internally concealed dust explosion passive explosion-proof device. The low-wind-resistance internally concealed dust explosion passive explosion-proof device comprises a shell body, an explosion-proof turning plate, and a power assisting mechanism, wherein a first pipe end and a second pipe end are arranged at the two ends of the shell body; the explosion-proof turning plate is arranged inside the shell body; and the power assisting mechanism comprises a fixing piece, a sliding rod, a limiting assembly and a power assisting assembly, the fixing piece is fixed inside the shell body, the sliding rod and the fixing piece form a sliding pair, the sliding rod is connected with the explosive-proof turning plate, the limiting assembly and the power assisting assembly are both connected with the fixing piece, the power assisting assembly comprises a guide rod connected with the sliding rod, the limiting assembly is used for limiting movement of the sliding rod and the guide rod, and the limiting assembly acts so as to enable the sliding rod to be coupled with explosive shock waves under the action of the power assisting assembly to push the explosive-proof turning plate to close the first pipe end. The low-wind-resistance internally concealed dust explosion passive explosion-proof device relates to the technical field of explosion proof for dust explosion, when dust explosion occurs, the device effectively improves the closing speed of the explosion suppression turning plate on the basis of keeping passive action execution stability, and can realize complete isolation of a dust explosion propagation process.

The invention discloses a lithium battery explosion-proof protection plate, and relates to the technical field of lithium battery carrying. The lithium battery protection plate comprises a protection plate shell, a dust-proof contact explosion air inlet structure, a guide dust-proof explosion ventilation structure, a fire explosion-proof structure, a protection carrying plate and a lithium battery main body, wherein one end of the protection plate shell is fixedly connected with the dust-proof contact explosion air inlet structure. Through the matched design of the dustproof contact explosion air inlet structure and the matched dustproof explosion air exchange structure, stable air exchange of the lithium battery in the plate body can be conveniently completed through the device, overheat explosion is avoided, meanwhile, dust friction explosion caused by following entry of dust is avoided, explosion-proof protection of the lithium battery is conducted from the source, and the service life of the lithium battery is prolonged. And through the design of a fire explosion-proof structure, the device can automatically extinguish sandy soil after sensing that the lithium battery is on fire, and continuous combustion and subsequent high-heat detonation are avoided by eradicating external air.

The invention discloses a convenient-to-adjust ventilation device for tunnel construction, including a bearing plate, wherein a sleeve is detachably connected to the upper end of the bearing plate, four first notches are equidistantly formed in the inner side wall the circumference of the sleeve, a first moving plate is arranged on each of the four first notches, two fixing frames are fixed between the four first moving plates, and one of the fixing frames is provided with a power mechanism on one side. By adopting a mechanical structure, the use of electrical components is reduced and the possibility that the device cannot operate normally due to damage of the electrical components is reduced, thereby making the whole device firmer and more reliable, adapting well to different harsh environments, ensuring operation performance normally, enabling ventilation to the tunnel conveniently and stably, making the fixed bracket by welding in the past become an adjustable bracket, being convenient for the staff to install and disassemble the sleeve, improving the efficiency of installation and disassembly, and facilitating the overall handling and transportation.

The present invention belongs to the field of agricultural engineering technology, and is especially one kind of winding and unwinding device for top film and shading and insulating layer of greenhouse. The winding and unwinding device consists of motor, reducing gear box, vertical reversing gear boxes, rocker rod, gimbals and film winding rod. The rocker rod has one end connected through the upper gimbals to the upper reversing gear box and the other end connected through the lower gimbals to the lower reversing gear box; the upper reversing gear box is connected to the film winding rod while the lower reversing gear box to the output of the reducing gear box; and the greenhouse covering has one side fixed to the film hanging rod and the other side wound onto the film winding rod for being wound. The present invention can wind and unwind greenhouse covering flexibly.

The invention discloses an electrostatic dust collection double-layer sheet ventilation curtain wall structure. The electrostatic dust collection double-layer sheet ventilation curtain wall structure comprises positive plates on the two sides, a curtain wall inner layer sheet and an curtain wall outer layer sheet, wherein a ventilation opening is formed in the lower portion of the outer layer sheet, a corona wire with barbs serving as a negative electrode is arranged in a cavity between the inner layer sheet and the outer layer sheet, a row of shutter dust collection plates driven by a lower shaft are further arranged in the cavity, a dust collection groove is formed in the lower portion of the curtain wall, a junction box and a fan box with a fan inside are arranged on the upper portion of the curtain wall, ventilation openings are formed in the lower bottom face, making contact with the cavity, of the fan box and the side, facing the indoor space, of the fan box, and a rectifier for converting alternating current into direct current and a current sensor for detecting current changes of the shutter dust collection plates are arranged inside the junction box. According to the electrostatic dust collection double-layer sheet ventilation curtain wall, a common shutter sun shield is replaced with the shutter dust collection plates with the dust collection effect, the charging area and the dust collection area are arranged in the cavity, fresh air entering a room is cleaned through electrostatic dust collection, the energy-saving advantage and the sun-shading and ventilation effects of a traditional double-layer sheet ventilation curtain wall are achieved, the fresh air purification effect is further achieved, the structure is simple, the energy consumption is low, and the application range is wide.

The invention provides a coal mine man-riding tunnel smoke removal device which comprises a shell. An air inlet pipe is fixed to the left end of the shell, a fixing cover is fixed to the upper end ofthe shell, an air outlet pipe is fixed to the upper end of the fixing cover, and an adjusting device is fixed to the upper end of the air outlet pipe. According to the coal mine man-riding tunnel smoke removal device, the size of a rubber ring can be changed through a pushing plate, the rubber ring can be adjusted according to the size of an object, airflow waste caused by the large diameter of the rubber ring is reduced, meanwhile, friction between the pushing plate and an outer ring can guarantee stability of the pushing plate, and the size of the rubber ring is not changed under the actionof airflow.