79 results about "Reverse airflow" patented technology

The invention relates to the technical field of air conditioners, and provides a cleaning method and device for an air conditioner indoor unit. Judging whether the dust accumulation parameter reaches a preset cleaning condition or not; under the condition that the dust accumulation parameter reaches the preset cleaning condition, the indoor fan is controlled to operate reversely, so that first reverse airflow flowing from the air outlet to the air inlet is generated and used for purging the filter screen; and the air inlet is controlled to be closed, the indoor fan is controlled again to operate reversely to generate second reverse airflow, and the second reverse airflow is used for discharging the dust falling into the heat exchanger through the condensate water pipeline. Whether the filter screen meets the preset cleaning condition or not is judged by monitoring the dust accumulation parameters of the filter screen in real time, when the preset cleaning condition is met, reverse blowing is conducted on the filter screen, then the air inlet is closed, and dust deposited on the heat exchanger is discharged outdoors through the condensate water pipeline by means of the indoor fan again. Therefore, on-demand cleaning based on the actual dust accumulation condition is achieved, and the cleaning efficiency is improved.

The present application relates to the technical field of stamping die, and discloses a non-woven fabric reinforced plastic pad stamping die, which comprises an upper die unit, a lower die unit and a blockage prevention system; the lower die unit comprises a lower die main body, the lower die main body is sequentially provided with a punching station and a blanking station along the feeding direction of the material belt, and the lower die main body is provided with a blanking channel which is in communication with the lower part of the punching station and the blanking station respectively; the blockage prevention system comprises a blowing execution module which is correspondingly arranged in the blanking channel, a gas supply module which is used for providing a gas source for the blowing execution module and a control module. The blockage prevention system is provided, the blowing unit and the posture sensing unit which are arranged in a high-low staggered manner work cooperatively, the accurate positioning and directional blowing of the jammed material are realized, only the downward thrust is applied from the upper part of the material, the reverse airflow is completely avoided, the success rate of breaking the jam is high, and long-time continuous unmanned production can be realized.

The invention relates to the related technical field of health information monitoring, and discloses integrated health information monitoring equipment and a use method thereof, the equipment comprises a monitor body, and the monitor body is internally provided with an air inlet end, a processing assembly, a condenser, a sensor, a fan and an air outlet end in sequence. The treatment assembly comprises a shell, a cavity unit capable of rotating in the circumferential direction is arranged in the shell, a baffling channel is formed in the cavity unit, and a filtering assembly with a filtering state and a cleaning state is arranged on the baffling channel. The filtering assembly comprises a first arc-shaped filtering plate forming a rough filtering unit and a second arc-shaped filtering plate forming a fine filtering unit. The cavity unit is driven by the driving assembly to rotate, so that the filtering assembly is switched between the filtering station and the cleaning station; the filter resistance change is detected through the differential pressure detector, and when the filter assembly is located at the cleaning station, the cleaning assembly applies reverse airflow to the filter assembly for cleaning.

A bracket is arranged in the middle of the interior of a cabinet body, the interior of the cabinet body is divided into a horizontal cavity and a vertical cavity through the bracket, a first vertical plate, a second vertical plate and a transverse plate are arranged in the horizontal cavity, and a ventilation channel is formed in the side, away from the second vertical plate, of the bracket in a penetrating mode in the vertical direction; the cabinet body is provided with a main supporting plate located in the vertical cavity, the cabinet body is provided with an evaporator located at the bottom end in the horizontal cavity and located below the transverse plate, the two sides of the evaporator are each provided with two sets of fans through fan bases, the two sets of fans are staggered, one set of fans faces the second vertical plate, and the other set of fans faces the second vertical plate. According to the utility model, the structure is reasonable, the two groups of fans are arranged in a staggered manner and do not influence each other, the stability of energy consumption improvement caused by reverse blowing is greatly reduced, and the two groups of fans respectively blow to the horizontal cavity and the vertical cavity, so that the energy consumption rate is reduced.

The embodiment of the utility model provides a single-tower VPSA (Vacuum Pressure Swing Adsorption) oxygen generation device adopting a positive and negative pressure all-in-one machine, which comprises an oxygen generation tower body used for loading a filler and performing pressure swing adsorption operation, a filter arranged at a gas inlet of the oxygen generation tower body to filter impurities in gas entering the oxygen generation tower body, and a positive and negative pressure all-in-one machine, wherein the filter is provided with a rotatable flushing rod and a back flushing gas channel, reverse airflow generated in a positive pressure state is used for instantly flushing a filtering layer, a filtering material layer is arranged in the filter to intercept particles, a slag discharging pipe is arranged at the position, located at the lowest end of the filtering material layer, of the filter, and the slag discharging pipe is used for discharging slag. The slag discharge pipe is also provided with a control valve for controlling the on-off of the slag discharge pipe; the positive and negative pressure all-in-one machine is used for alternately applying vacuum extraction and pressurized filling; and the positive and negative pressure all-in-one machine is connected with the oxygen production tower body through a special connecting pipe. Through the scheme of the embodiment of the invention, unsmooth airflow caused by impurity accumulation can be reduced.

The utility model relates to the technical field of plastic processing, in particular to a self-cleaning plastic screw extruder, which comprises a screw extrusion barrel for producing plastic products, a forward and reverse rotation servo motor is mounted at one end of the screw extrusion barrel, and a feed hopper and a self-cleaning reverse blowing machine are mounted at the top of the screw extrusion barrel. According to the utility model, the self-cleaning blowback machine is arranged, and the air outlet connecting air pipe of the self-cleaning blowback machine is in interference insertion fit with the blowback air hole in the top of the screw extrusion barrel, so that during cleaning, the self-cleaning blowback machine can provide reverse airflow to the inside of the screw extrusion barrel, residual plastic on the inner wall of the screw extrusion barrel and a screw is effectively removed, and blockage is avoided; due to the design of the replaceable extrusion head at one end part of the screw extrusion barrel, a user can easily replace extrusion heads with different specifications or functions according to production requirements, and the flexibility and applicability of equipment are improved; in addition, a forward and reverse rotation servo motor is installed, so that the screw rod can work in a reverse rotation mode, and the self-cleaning effect of the equipment is enhanced.

The utility model relates to the technical field of air windows, and discloses a mining air window which comprises a window frame, a rotating door movably connected in the window frame in a sleeved mode, a PLC fixedly installed on one side of the window frame, and a door closing assembly arranged on one side of the window frame and used for closing the rotating door. Through mutual cooperative use of the window frame, the revolving door, the limiting frame, the moving plate, the push-pull electromagnet and the limiting groove, the effect of closing the revolving door is achieved, when reverse airflow (such as gas outburst shock waves) occurs, the revolving door can be quickly pushed to be closed through external force, the situation that the revolving door is difficult to respond quickly due to blockage and the like is avoided, and the service life of the revolving door is prolonged. Meanwhile, under the normal condition, the electromagnetic lock switch is controlled by collecting the air pressure difference between the windward side and the leeward side, a user does not need to manually open the rotating door, ventilation is conducted in time, use is convenient, and practicability is achieved.

This invention relates to the field of automated packaging and surface coating equipment, specifically to an integrated processing device and method for uniform spraying and curing of cosmetic bottle surfaces. It comprises core components such as a multi-axis robotic arm, a coaxial annular atomizing nozzle, a Coanda effect flow guide, a high-frequency ultrasonic transducer, and ultraviolet light-emitting diodes. The device utilizes the atomizing nozzle to generate a pneumatic vector field to transport the coating material, and uses the Coanda effect flow guide to change the direction of the rebounding airflow, forming a centripetal constraint on the main jet. Its core is the high integration of spraying, ultrasonic, and ultraviolet curing components into a single actuator head, enabling wet film spreading and curing to be completed collaboratively in adjacent spaces. This invention effectively reduces the disturbance of the uncured wet film by the reverse airflow, improves the deposition stability at complex contours, and avoids spatial position deviations caused by traditional segmented processing and separate transport.

The present invention provides a portable ventilator suitable for cardiopulmonary resuscitation (CPR) and a control method thereof. According to the present invention, the number of external chest compressions in a CPR process can be automatically recognized on the basis of reverse airflow, and a compression period and a relaxation period can be determined. The portable ventilator has an automatic 30:2 ventilation mode suitable for non-intubated patients and a variable-volume ventilation mode suitable for patients with advanced airways. The present invention can improve the efficiency of first aid and avoid barotrauma, is suitable for the first aid during CPR, and can achieve precise flow control.

The invention provides a powder electrostatic measurement system, and belongs to the technical field of material electrostatic experiments, the powder electrostatic measurement system comprises a system rack, the system rack is provided with a raw material supply module, an airflow driving module, an experiment pipeline module, a flow monitoring module, an electrostatic measurement module and a powder collection module; the raw material supply module comprises a quantitative discharging mechanism and a powder scattering mechanism. The airflow driving module comprises an air compressor and a powder conveying fan; the flow monitoring module comprises a flow meter, an anti-blocking tee joint and a pulse blower device; the pulse blower device is used for regularly outputting reverse airflow to prevent powder from being accumulated and blocked at a sampling port of the flow meter; the electrostatic measurement module comprises a Faraday cup and an electrostatic charge measurement device; the powder collecting module comprises two powder collecting cylinders which are arranged in series; the problem that influences of different pipeline materials and different section shapes on electrostatic characteristics of powder in an actual industrial scene are difficult to simulate can be solved.

The utility model relates to tempering protection device technical field, especially a kind of preheating burner tempering protection device for gasification device, including preheating burner, first guide ring, second guide surface, connecting sleeve, sealing disc, drainage portion, slide bar and limit sleeve, preheating burner is equipped with 90 ° bending structure in its export end, first guide ring is fixedly installed in preheating burner inner wall, and its bottom surface is equipped with first guide surface.The utility model wherein preheating burner is equipped with 90 ° bending structure in its export end, changes the axial ejection direction of traditional straight-through structure, forces flame to flow along bending path, makes high-temperature gas away from operating area, when tempering occurs, flame blocked by fire-retardant net, reverse airflow pushes sealing disc, drives sealing disc to close first guide ring, forms physical block, reduces flame from preheating burner and avoids preheating burner open end directly towards patrol channel and operator work area to cause direct burn threat.

The invention relates to the technical field of flue gas treatment equipment, and provides a dust removal device for a blast furnace flue gas treatment system, which comprises a box body and a filter bag frame arranged in the box body, and further comprises a driving mechanism and a rapping frame, the rapping frame is arranged in the box body, sleeves which are in one-to-one correspondence and sleeve the lower part of the filter bag frame are arranged in the rapping frame, and first sliding rods are symmetrically arranged on two sides of the rapping frame. According to the invention, the defects in the prior art are overcome, the design is reasonable, the structure is compact, a dust layer with relatively strong adhesive force on the surface of the filter bag can be effectively destroyed and stripped through periodic mechanical rapping in a dust cleaning mode of combining mechanical rapping and pulse blowing, and favorable conditions are created for subsequent blowing; the pulse blowing can provide strong instant reverse airflow, go deep into the filter bag and remove loose fine dust after vibration, the pulse blowing and the filter bag act synergistically, the overall dust removal efficiency and thoroughness are remarkably improved, and the device is particularly suitable for the working condition of dust which is complex in component and possibly viscous in blast furnace flue gas.

The invention relates to an air quality sensor. A housing has a flow channel for guiding air to be measured through the housing; at least part of the first sensor is inserted into the flowing channel, the flowing channel comprises a measuring channel and a bypass channel, and the first sensor is configured to be used for detecting forward airflow flowing in from the first opening and flowing out from the second opening and reverse airflow flowing in from the second opening and flowing out from the first opening. According to the scheme, reverse airflow can be detected, the influence of pulsating airflow is reduced, and the measurement precision is improved.

The utility model provides a kind of refrigeration equipment, which comprises: a cabinet;Evaporative bin;Evaporator;Air supply air duct;First fan, first fan is located in air supply air duct, and is located at air inlet;First fan is configured to: first fan can extract air in evaporative bin through air inlet, and is transported to refrigeration chamber through air supply air duct, air outlet;Second fan, second fan is located at air inlet;Second fan is configured to: second fan can extract air in air supply air duct and is transported to evaporative bin through air inlet.According to the refrigeration equipment provided by the utility model, when the refrigeration equipment is in defrosting mode, the reverse airflow formed by the second fan blocks the hot air in the evaporative bin from flowing into the air supply air duct, thereby preventing the hot air from entering the refrigeration chamber through the air supply air duct, and reducing the temperature change in the refrigeration chamber during defrosting, thereby avoiding affecting the refrigeration effect of the refrigeration chamber.

The utility model relates to filter cartridge dust collecting technical field, and disclose a kind of high-efficiency filter cartridge dust collecting device, including outer machine component, the bottom end of outer machine component is provided with unloading assembly, the side wall of unloading assembly is provided with air inlet, the inside lower end of outer machine component is penetrated with flow guide cover, filter assembly, the bottom of flow guide cover is set to the top end of unloading assembly, flow guide cover is set to the bottom end of filter assembly, the upper end left side of outer machine component is provided with air outlet. The filter screen of filter assembly is set in double-layer folding page inner layer, greatly increase the filtration area, can more fully intercept dust, improve filtration efficiency and purification effect, in the aspect of dust cleaning, pulse blowing component bottom end surrounds and is inclined on the outside wall of filter assembly top, when spray valve opens, the compressed air that spray pipe sprays can be with high-efficiency angle and direction impact filter cartridge surface, produce instantaneous reverse airflow, make filter cartridge swell shrink deformation.

The application discloses an oil fume extractor, which comprises a fan system and an air outlet cover arranged at an air outlet of the fan system, the fan system comprises a volute and an impeller arranged in the volute, the volute comprises a volute tongue, and the air outlet cover comprises an outlet, and the outlet throat area of the volute is smaller than the area of the outlet of the air outlet cover, wherein the outlet throat area of the volute is the cross-sectional area of the volute passing through the starting end of the volute tongue, and the cross section is parallel to the axis of the impeller. Compared with the prior art, the outlet throat area of the volute is small, the reverse airflow is less, and the noise reduction of the user working condition is facilitated.

The utility model discloses an atomization device which comprises a liquid storage bin, an atomization core and an air outlet assembly, the liquid storage bin is configured to store an atomization matrix, and an atomization channel is formed in the liquid storage bin in a penetrating mode; the atomizing core is arranged in the atomizing channel, and the atomizing core is configured to receive and atomize the atomizing matrix to generate aerosol; the air outlet assembly comprises a one-way valve, the one-way valve is provided with an air inlet end and an air outlet end, the air inlet end communicates with the atomization channel, and the one-way valve is configured to only allow the fluid medium to flow in the direction from the air inlet end to the air outlet end. Through the arrangement of the one-way valve, it can be ensured that the fluid medium can be output in the direction from the air inlet end to the air outlet end, reverse airflow is prevented from entering the atomization channel, and then condensate is prevented from flowing back under the action of the reverse airflow.

A portable fume collection system is provided for capturing fumes, dust and gaseous and particulate matter created during welding and other applications. The portable fume collection system includes a downdraft table component and a fume capture arm component. The portable fume collection system includes a frame with an interior housing a motor and a fan for generating reverse airflow at the downdraft table component and the fume capture arm component.

The present application relates to carbon dioxide detection technology field, specifically to a kind of petrochemical combustion carbon dioxide content detection equipment, including non-dispersive infrared gas analyzer, the non-dispersive infrared gas analyzer outside is shell, the non-dispersive infrared gas analyzer is provided with gas inlet, exhaust port, the gas inlet is inserted with sampling tube, one end of the sampling tube is sampling head, the inside of the sampling head is provided with the backflow prevention structure of gas, when potential backflow occurs, reverse airflow attempts to enter from the small mouth end of fairing, at this time, the flow resistance of intercepting groove is substantially increased, due to the existence of intercepting groove, reverse airflow needs to overcome greater resistance to pass through, and the gas of backflow bounces back after impacting the baffle at one end of fairing, realize the blocking when gas backflow, the design of conical fairing also shrinks the passage of backflow gas, further improve the resistance, therefore effectively inhibit the reverse flow of gas to prevent its backflow.

The utility model discloses an electronic cigarette with a rifling one-way air valve, which comprises an electronic cigarette main body, an air sensing part, a power supply assembly, an oil storage cavity used for storing tobacco tar, a ventilation and smoke exhaust part corresponding to the oil storage cavity, a one-way air valve arranged in the ventilation and smoke exhaust part, and a plurality of riflings arranged in the one-way air valve. The air sensing part is provided with an airflow switch capable of starting the power supply assembly to electrify the heating core after ventilation, and the electronic cigarette main body is provided with an air inlet communicated with the ventilation smoke discharging part and the air sensing part. According to the electronic cigarette, air resistance can be reduced through the rifling in the process that smoke is exhausted from the ventilation and smoke exhaust part during smoking, explosive power and taste saturation of the smoke can be higher, and when reverse airflow enters the ventilation and smoke exhaust part, the one-way air valve can be automatically closed to block the ventilation and smoke exhaust part. The airflow is prevented from entering the air sensing part and abnormally starting the airflow switch, so that the power supply assembly electrifies the heating core to heat the tobacco tar.

The invention belongs to the technical field of low-voltage switch equipment, and particularly discloses low-voltage complete switch equipment which comprises a low-voltage cabinet body, a top groove is formed in the top of the low-voltage cabinet body, a rainwater collecting device is arranged in the top groove, and a control box is arranged in the middle of the interior of the low-voltage cabinet body. A filter screen plate is arranged on the inner wall of one side of the low-voltage cabinet body, and a shutter air bellow is arranged on the inner wall of the other side of the low-voltage cabinet body. When it rains, the rainwater collecting device triggers the switching assembly to work, the rotating direction of the transmission shaft is changed, then airflow is blown outwards from the interior of a filter screen cover, and the rainwater collecting device is used for collecting rainwater; dust on the filter screen cover can be cleaned through reverse flowing of airflow, meanwhile, when the rainwater collecting device triggers the switching assembly to work, collected rainwater can be guided into a strip-shaped water spraying pipe on the cleaning assembly so that the rainwater can be sprayed to the filter screen cover, and the filter screen cover can be further cleaned in cooperation with the airflow blowing in the reverse direction.

A jet nebulizer and a method for generating aerosols within it are described. The nebulizer consists of an internal conical structure with a concave conical surface. An initial aerosol flow is guided along this surface and then reversed, directed toward the nebulizer outlet. Both flows, the initial and the reverse, form a vortex within the nebulizer, resulting in a higher-quality aerosol. Furthermore, the nebulizer is designed to operate at an angle of up to 90 degrees.

The utility model discloses a turbine air intake's air cleaner relates to air cleaner technical field. The utility model discloses a shell and reverse blow self -cleaning subassembly, the both sides between shell inner chamber are installed with filter core board, the top fixedly connected with seal cover of shell, the left side of shell and seal cover right side are connected with air inlet pipe and exhaust pipe respectively, the surface of exhaust pipe is installed with first check valve. The utility model discloses a reverse blow self -cleaning subassembly, utilizes motor drive cam rotation, periodic extrusion push rod, and reciprocating motion is pushed to the piston in the air chamber, and the pulse airflow of compressed air generates, and this compressed air is discharged through the delivery pipe, forms the impact of reverse airflow, effectively blows off the dust layer of filter core board windward area gathering, solves the problem that dust is continuously accumulated and is jammed filter core board pore because of turbine supercharger big air intake, keeps the air permeability of filter material, reduces the air intake resistance, and guarantees turbine supercharging efficiency.

The invention relates to the technical field of medical care and rehabilitation medicine, and discloses a method for establishing reverse airflow to assist sound production through a subglottic suction tube, and the method comprises the following steps: executing airway cleaning, keeping a tracheotomy cannula air bag full, and blocking a tracheal gap by using the air bag; constructing a reverse air supply passage for connecting an external air source and the subglottic suction tube; gas supply equipment is started, and the gas flow is adjusted through a progressive strategy; on-off of a gas path is controlled according to sound production requirements, so that gas is ejected from the subglottic suction tube and is limited by blocking of the air bag to form upward reverse airflow to impact the vocal cord. The air bag is used as a physical barrier to reconstruct subglottic positive pressure, vocal cord vibration is effectively driven to recover the speech function of a patient on the premise that a tracheotomy ventilation mode is not changed and the risk of aspiration by mistake is not increased, the problem that the tracheotomy patient cannot make a sound for a long time is solved, and meanwhile recovery of physiological reflex of the upper respiratory tract is promoted through fluid stimulation.

A method of clearing a swirl generator of a vortex tube for an aircraft enclosure inerting system. The vortex tube has an inlet chamber and a vortex chamber which can receive air from the inlet chamber via flow paths in the swirl generator. The method comprises operating the vortex tube in a foreign matter clearance mode in which a reversed flow of gas is passed from the vortex chamber into the inlet chamber through the flow paths and dislodges accumulated foreign matter therefrom. Dislodged foreign matter is then exhausted from the vortex tube then the vortex tube is operated in a normal mode of operation.

This application provides a fresh air device and control method, relating to the field of fresh air device technology. The fresh air device includes a main body and multiple air ducts. The main body has a first air inlet and a first air outlet. The multiple air ducts include an air inlet duct, an air outlet duct, and a bypass duct. The air inlet duct and the air outlet duct are installed on the main body. When the fresh air device is in fresh air mode, the air inlet duct is connected to the first air outlet through the main body to form an air inlet flow path, and the air outlet duct is connected to the first air inlet through the main body to form an air outlet flow path. The bypass duct has its inlet end connected to the air outlet duct and its outlet end connected to the air inlet duct. When the fresh air device is in self-cleaning mode, the first air inlet is connected to the air inlet duct sequentially through the air outlet duct and the bypass duct to form a self-cleaning flow path. This allows the reverse airflow to blow dirt out from the inlet end of the air inlet duct, achieving automated cleaning of the air inlet duct.

The utility model relates to the technical field of dust collectors, and particularly discloses a cleaning device, which comprises a self-cleaning mechanism used for switching the cleaning device from a normal working state to a self-cleaning state when being operated by a user; the air flow forwards passes through the filter in the normal working state, and at least part of the air flow reversely impacts the filter in the self-cleaning state; the motor is used for generating negative pressure to form airflow; the dust cup is used for collecting dirt; the filter is positioned in the dust cup; the cleaning device further comprises an inlet blocking piece and a dust outlet blocking piece, wherein the inlet blocking piece is arranged at the dust inlet; in a normal working state, the dust inlet is opened by the inlet plugging piece; and in the self-cleaning state, the dust inlet is sealed by the inlet plugging piece. In the self-cleaning state, the dust inlet is closed by the inlet blocking piece, the situation that dust in the dust cup carried by reverse airflow is sprayed out of the dust inlet can be effectively prevented, the dust spraying phenomenon is avoided, and the user experience is improved.

The panel includes a planar body having a first side and a second side, with a plurality of air passages extending between them. Each air passage has larger opening on the first side and a smaller opening on the second side, forming a narrowing geometry. This geometry is configured to induce a directional pressure differential and / or a directional acoustic impedance, enabling greater airflow or sound propagation from one side to the other while limiting reverse airflow or sound propagation. The panel may be integrated with air cooling or accelerating modules. In some embodiments, the panel forms part of a closed-loop air circulation system. The panel may be made of concrete, stone, metal, ceramic, or phase change materials, and is suitable for thermal and acoustic regulation.

The utility model discloses a cleaning device which comprises a shell, a motor, a filter, a gulp valve, a shielding part, a self-cleaning valve and a driving mechanism. The shell is provided with an air supply port, a filtering port and a self-cleaning port; the driving mechanism synchronously drives the gulp valve, the shielding part and the self-cleaning valve to move in the same direction, and switching between the dust suction state and the self-cleaning state is achieved. In a dust suction state, the gulp valve and the self-cleaning valve are closed, the shielding part opens the filtering opening, and dust-containing airflow sequentially flows through the filter, the filtering opening and the gas supplementing channel to enter the motor; in the self-cleaning state, the gulp valve and the self-cleaning valve are opened, the shielding part closes the filtering opening, and external air enters the motor through the gas supplementing channel to form reverse airflow which impacts the surface of the filter through the self-cleaning opening. Multiple valves are linked in a single direction and share an air supply channel to reduce the size of an air channel, and meanwhile a complex transmission structure is omitted. The self-cleaning dust collector is compact in structure and low in cost, the dust collection efficiency and the self-cleaning concentration ratio are remarkably improved, and the problems that a traditional self-cleaning dust collector is bloated in structure and poor in switching stability are solved.

To suppress leakage of ink from a waste ink container.SOLUTION: An inkjet recording apparatus includes a recording head, a waste ink container, and a suction mechanism, wherein the waste ink container includes a receiving port configured to receive ink ejected from the recording head, a suction port connected to the suction mechanism, and a suction air passage configured to allow the receiving port and the suction port to communicate with each other, and the suction air passage includes a reverse-direction air passage configured to guide a suction air flow in a direction away from the suction port, and a forward-direction air passage configured to guide the suction air flow in a direction approaching the suction port.SELECTED DRAWING: Figure 12