Air shutter and installation method thereof

The present invention relates to an air shutter installed at a doorway where temperature differential exists between outside and inside thereof to interrupt outside air from flowing into a room and cold air inside the room from flowing out, particularly an insect-proof/dust-proof air shutter installed at a doorway of a sanitarily controlled room such as in a food factory, which can effectively prevent intrusion of foreign matter such as dust, particularly can catch intruded insects.

An air curtain for preventing intrusion of outside air through the doorway of a thermal insulation door of a building is known from Japanese Patent Publication No. 37-12183. According to the invention, air spouts from both right and left sides horizontally to interrupt infiltration of outside air and exfiltration of inside air through the doorway. However, as the two airflows collide to each other in the central region of the doorway opening, the amount of airflow is larger as compared with a case of an air curtain formed by an air stream spouting only from one side, resulting in increased power consumption.

As one of means to prevent intrusion of foreign matter such as insects, dust, etc. through the doorway opening of a sanitarily controlled space in a food factory and so on, a system of forming an air curtain to cover the doorway as an air wall was proposed and has been put to practical use. There are known as systems of forming an air curtain such as a downward spouting system in which air is spouted from the top of the opening downward, a vertical circulation system in which air is spouted from the top of the opening downward and sucked into the pit provided on the floor to be returned to the top of the opening through an air duct, a lateral flow system in which air is spouted horizontally from a lateral side of the opening toward the other lateral side thereof, a lateral circulation system in which air is spouted horizontally from a lateral side of the opening toward the other lateral side thereof where the air is sucked in to be returned through an air duct to the lateral side from which the air was spouted, a lateral countercurrent circulation system in which air is spouted horizontally from both of lateral sides of the opening toward the other lateral sides of the opening respectively where the air is sucked in to be returned to the lateral sides where the air was spouted respectively, a lateral countercurrent system in which air is spouted horizontally from both lateral sides of the opening toward the central zone of the doorway opening leaning toward outside of the opening, etc.

For example, in Japanese Patent No. 2920759 (patent literature 1) is disclosed an air curtain producing system of lateral countercurrent type. In the system, air discharge openings are provided at each of the side walls facing each other across the doorway opening such that air is spouted horizontally from each of the discharge openings leaning with a proper angle respectively toward outside of the doorway so that two air streams spouting from each of the discharge openings collide against each other with a certain crossing angle and join together in the range of the doorway opening, wherein the air streams are different in velocity such that the one is relatively high and the other is relatively low, thereby suppressing occurrence of turbulence at the confluence of both the air streams, occurrence of eddies due to pulsation of air stream, and occurrence of infiltration of outside air and intrusion of insects rising on the infiltration air.

In Japanese Laid-Open Patent Application No. 2006-57928 (patent literature 2) is disclosed an air shutter unit, in which an entrance space is formed at the doorway of a room by both side walls, a ceiling part, and a floor part, and the entrance space is intercepted by an air curtain or curtains formed by air streams flowing laterally across the entrance space, wherein two air curtains are formed by two air streams flowing laterally across the entrance space in two separate planes in opposite directions to each other, each of the air stream circulating from the one to the other air stream. With this air shutter unit, the air streams are allowed to circulate in separate planes so that the air streams do not collide with each other and occurrence of turbulence in the doorway opening is prevented as much as possible, with the result that the effect of preventing intrusion of insects is increased.

It is supposed that the lateral countercurrent system and lateral countercurrent circulation system are superior in foreign matter interrupting effect among systems mentioned above.

However, there are problems as follows:

In the lateral countercurrent circulation system, an air shutter of portal construction provided with fans therein is installed at the doorway, air is spouted from the right and left side so that air streams collide with each other at the central zone of the doorway opening, and the rebounded air stream is sucked into the right and left gatepost of the portal construction to be circulated. However, it is difficult to suck in the air streams rebounded from the central part because of small suction opening area, and the air streams disturb air near the doorway openings, intrusion of insects tends to occur.

In the lateral countercurrent system, an air shutter of portal construction provided with fans therein is installed at the doorway, air is spouted from the right and left side so that air streams collide with each other at the central zone of the doorway opening, and air to be spouted is sucked through the suction openings of the gateposts, each of the suction openings being provided on a face different from the face on which each of the discharge opening is provided. In this case, also the air streams disturb air near the openings, and intrusion of insects tends to occur.

In the system disclosed in the patent literature 1, air is spouted horizontally from discharge openings at velocities different to each other leaning with a proper angle respectively toward outside of the doorway so that two air streams spouting from each of the discharge openings collide against each other with a certain crossing angle and join together in the range of the doorway opening, and air to be spouted is sucked through the suction openings of the gateposts, each of the suction openings being provided on a face different from the face on which each of the discharge opening is provided.

However, actually it is difficult to bring the air stream of lower velocity into integration with the air stream of higher velocity, turbulence occurs at the confluence region, and intrusion of insects tends to occur.

In the system disclosed in the patent literature 2, air stream is circulated laterally across the doorway opening without colliding with each other, so turbulence does not occur, however, further improvement in effect of preventing insect intrusion is demanded. Particularly, to positively remove insects intruded when the air shutter is operated is not taught in any of prior arts, and it has been demanded to provide an air shutter capable of interrupting foreign matter and positively removing intruded insects.

The present invention aims in light of the problems of the prior art to provide an insect/dust-proof air shutter capable of preventing intrusion of foreign matter such as insects and dust credibly and further capable of catching intruded insects.

To solve the problems, the present invention proposes an air shutter, especially suitable for use as an insect/dust-proof air shutter, for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, in which two air streams flowing in two planes in the passage space laterally crossing the passage space in opposite directions to one another are formed, and the air streams reverse their flow directions horizontally by 180° at each of both side end wall parts of the passage space so that the air streams circulate from one to the other air stream, thereby forming double air films crossing laterally in the passage space.

Further, the invention proposes an air shutter, especially suitable for use as an insect/dust-proof air shutter, for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, in which a discharge opening and a suction opening are provided horizontally proximate to one another at each of side end wall parts forming the passage space such that the suction opening of one of the side end wall parts faces the discharge opening of the other side end wall part across the passage space, and an air passage is provided in each of the side end wall parts such that air sucked in through each of the suction openings is reversed in its flow direction horizontally by 180° to be blown out from each of the discharge openings, thereby the air streams circulate from one to the other air stream with each of the air streams flowing in opposite direction to one another, thereby forming double air films crossing laterally in the passage space.

According to the invention, double air films are formed separately in the depth direction of the passage space, so air streams forming the air films do not interfere with each other and turbulence does not occur, and the function of interrupting intrusion of foreign matter can be stably maintained. Further, as the double air films are formed by air streams flowing in directions opposite to one another, even if one of the air films is broken by personnel or things passing through the passage space, the inside space can be intercepted from the outside space reliably. Further, as the air streams are reversed in flow direction by 180° horizontally in each of the side casings, a large area of air passage for introducing the sucked air stream to the fans provided in the side casings can be secured in each of the side casings, pressure loss in the suction side of the fans is reduced, and uniform distribution of velocity of blowing out air stream in vertical direction is attained.

Further, the air shutter is applied particularly suitably for the purpose of interrupting intrusion of insect by providing an insect net in the air passage of each of the side casings. By this, insects blown about by the air stream and sucked in through the suction openings can be positively trapped by the insect nets just behind the suction openings. Further, by providing the insect net, it can be prevented that insects sucked in the casing are crashed and scattered in the casing.

The invention proposes an air shutter, especially suitable for use as an insect/dust-proof air shutter, for producing an air stream or streams flowing laterally across a passage space through which an inside space of a room is communicated to an outside space in order to intercept the inside space of the room from the outside space, in which a discharge opening and a suction opening are provided vertically proximate to one another at each of side end wall parts forming the passage space such that the suction opening of one of the side end wall parts faces the discharge opening of the other side end wall part across the passage space, and an air passage is provided in each of the side end wall parts such that air sucked in through each of the suction openings is reversed in its flow direction vertically by 180° to be blown out from each of the discharge openings, thereby the air streams circulate from one to the other air stream with each of the air streams flowing in opposite direction to one another, and thus a single air film consisting of two air streams flowing in opposite direction to one another is formed crossing laterally in the passage space, and in which an insect net is provided in said air passage.