Floating flap gate

A floating flap gate to prevent water from overflowing into underground spaces, with ease in raising or lowering the door body when water level changes. The floating flap gate comprises a door body with a forward end which swings upwards or downwards in a same direction following a rise or a drop in water level, wherein an opposite end serves as a fulcrum. A rod is attached to the forward end of the door body. One end of a wire rope is attached to the rod, and the other end is attached to a counterweight via fixed pulleys. The fixed pulleys are arranged so that the counterweight is at its lowest point when the angle of inclination of the door body with respect to a horizontal plane reaches within a range from 10° to 80° during raising or lowering of the door body.

TECHNICAL FIELD

The present invention relates to a floating flap gate which is disposed at an opening in a seawall to prevent a rising water from flowing into living spaces or underground spaces at a time of rising water, by raising a door body to block the opening.

BACKGROUND ART

A floating flap gate exists which is disposed at an opening of a seawall and blocks the opening at the time of a rising water to prevent the rising water from flowing into living spaces or underground spaces, by raising a door body, using a buoyancy of the water which is trying to flow in (e.g., Patent Reference 1).

However, the floating flap gate disclosed in Patent Reference 1 has a problem in that if a speed of the inflowing water is high, the rising action of a door body1is delayed, resulting in an overflow of water into living spaces or underground spaces (seeFIG. 11 (a).)

In addition, when the water level drops, the door body1stays at a rising state up to a water level which is about ⅓ the height of the door body1, and subsequently exhibits a hazardous behavior such as suddenly falling (seeFIG. 11(b).)

In order to prevent the problem of overflow during the initial influx of water, there was proposed a floating flap gate with a rope having a counterweight attached to one end, and with the other end connected to the door body via a pulley (e.g., Patent Reference 2).

The floating flap gate disclosed in Patent Reference 2 solves the problem of the delayed rising action of the door body during the initial influx of water by compensating for an insufficient buoyancy of the floating flap gate by using the weight of a counterweight.

However, the floating flap gate disclosed in Patent Reference 2 does not readily lower when the water level drops, because weight of the counterweight continually operates in a direction which assists in the operation of raising the door body.

Patent Reference 1: Japanese Patent Application Kokai Publication No. 2001-214425

Patent Reference 2: Japanese Patent Application Kokai Publication No. 2003-253912

SUMMARY OF THE INVENTION

Problems to be Solved by the Invention

The problem which the present invention aims to solve is that it becomes difficult to lower the door body when the water level drops, if a device is installed to continually assist in the operation of raising the door body, so as to solve the problem of a floating flap gate in which the operation of raising the door body is delayed when water starts flowing in, resulting an overflow into living spaces or underground spaces.

Means for Solving this Problem

The present invention was devised with the aim of eliminating the overflow into living spaces or into underground spaces when the raising operation of the door body is delayed when water first starts to flow in, and eliminating difficulty in lowering the door body when the water level drops, and thus eliminating hazardous behavior such as sudden falling of the door body.

The floating flap gate according to the present invention is a floating flap gate which is disposed at an opening or at an access way, so as to block the opening or the access way when water flows in, and comprises a door body with a forward end which is able to swing upwards, in a direction in which the water flows in and within a plane in a height direction, around a base end thereof serving as a fulcrum.

One end of a rope is attached to the forward end of the door body, and the other end of the rope is attached to a counterweight or a spring via at least a fixed pulley, so that the counterweight is at its lowest point or the spring reaches its natural length when the angle of inclination of the door body with respect to a horizontal plane reaches within a range from 10° to 80° during raising or lowering of the door body.

According to the present invention, the door body is assisted in rising by being drawn in an upward direction by the counterweight or by the spring, until the angle of inclination of the door body with respect to a horizontal plane reaches within a range from 10° to 80° during raising of the door body. Further, if the angle of inclination of the door body with respect to a horizontal plane exceeds the range of 10° to 80°, the counterweight or spring causes resistance, thereby reducing the raising speed of the door body.

On the other hand, when lowering the door body, until the angle of inclination of the door body with respect to a horizontal plane reaches within a range from 10° to 80°, the door body is assisted in following a downward trajectory which follows the water level as it drops, by being drawn in a downward direction by the counterweight or by the spring. In addition, when the angle of inclination of the door body with respect to a horizontal plane is below the range of 10° to 80°, the counterweight or spring causes resistance, thereby reducing the lowering speed of the door body.

Advantageous Effects of the Invention

According to the present invention, the predetermined angle of inclination of the door body with respect to a horizontal plane while raising or lowering the door body serves as a point of bifurcation for assisting in raising and lowering the door body and, causing resistance to raising or lowering the door body, thus making it possible to prevent water from overflowing at the time of the initial influx, and also making it possible to prevent the door from suddenly falling before lowering of the door body is completed. In addition, it becomes possible to mitigate the shock which occurs when raising of the door body is completed, and the ability of the door body to follow the water level improves at the initial stage of lowering of the door body.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

According to the present invention, the object of preventing an overflow of water, during a beginning of water inflow, into living spaces and underground spaces, preventing difficulties in lower the door body when the water level has dropped, and preventing the door body from suddenly falling, is achieved by assisting in raising and lowering the door body, and by causing resistance to raising or lowering the door body, by having the predetermined angle of inclination of the door body with respect to a horizontal plane serve as a point of bifurcation while raising and lowering the door body.

EXAMPLE

An example of the present invention is described in detail below usingFIG. 1toFIG. 10.

FIG. 1is a schematic structural drawing of the floating flap gate according to the present invention.

InFIG. 1, Reference Numeral11is a floating flap gate according to the present invention which is disposed on a channel surface rs at an opening in a seawall, for example. When a water w tries to flow from an ocean (or from a river) into a living space or an underground space, the floating flap gate11uses the pressure of the water w to swing a forward end12bof a door body12upwards around a base end12aas a fulcrum, to block the opening in a water-tight manner.

If there is a wide opening to be blocked by the door body12of the floating flap gate11, then a plurality of door bodies12may be linked width-wise at the opening, and the spaces between the various door bodies12are joined together with water-tight rubber. In addition, water-tight rubber is provided on the sides corresponding to door bumpers of the door bodies12on both sides, which are provided at the opening of the seawall.

The floating flap gate11shown inFIG. 1has, for example, a rod13attached across the entire width-wise direction of the forward end of the door body12, which functions to support the load resulting from the water pressure, and to attach one end of a wire rope14.

The other end of the wire rope14is attached to a counterweight20via a first fixed pulley16which is disposed at a door bumper15at the top of the forward end of the door body12during lowering, and via a second fixed pulley17disposed in a position at the same height as the first fixed pulley16on the base end side of the door body12. Therefore, the weight of the counterweight20operates on the door body12.

In the present example of the invention, because the angle of inclination θ of the door body12is 90° when raising of the door body is completed, the position at which the first fixed pulley16is set is such that the counterweight20reaches its lowest point when the angle of inclination θ is 45° with respect to a horizontal plane when the door body12swings upwards (seeFIG. 2 (b)), for example. As a result of investigations conducted by the inventors, there was found to be no problem if the angle of inclination θ ranges from 10° to 80°.

The floating flap gate11of the present invention which has the above-described configuration exhibits the functions described below when raising and lowering the door body12.

When Raising the Door Body12

When water first starts flowing in, the counterweight20drops, pulling the door body12upwards, thereby assisting the door body12to rise (seeFIG. 2(a)). When the angle of inclination θ of the door body12with respect to a horizontal plane reaches 45°, the door body12and the wire rope14line up (seeFIG. 2 (b)) and the counterweight20reaches the position of the lowermost end. When the angle of inclination θ of the door body12with respect to a horizontal plane exceeds 45°, the counterweight20rises due to the upwardly swinging action of the door body12, so that the counterweight20causes resistance, thereby decelerating the rising of the door body12, thus mitigating the shock when raising of the door body12is completed (seeFIG. 2 (c)).

When Lowering the Door Body12

At the initial stage of lowering the door body12, the counterweight20drops, pulling the door body12downward so that it follows the water level as it drops (seeFIG. 2 (d)). Further, when the angle of inclination θ of the door body12with respect to a horizontal plane reaches 45°, the door body12and the wire rope14line up (seeFIG. 2 (b)) and the counterweight20reaches the position of the lowermost end. When the angle of inclination θ of the door body12with respect to a horizontal plane is less than 45°, the counterweight20rises due to the lowering of the door body12, so that the counterweight20causes resistance, thereby decelerating the lowering of the door body12, thus mitigating the shock when lowering of the door body12is completed (seeFIG. 2 (e)).

FIG. 3shows the relationship between the angle of inclination θ of the door body12and the swinging force of the door body12in the direction of rising due to the counterweight20in the floating flap gate11according to the present invention.

The floating flap gate11according to the present invention makes it possible to implement a variety of functions such as assisting in raising the door body12, mitigating shock, and imparting a trajectory that follows the water level, as described above, by utilizing a raising/lowering mechanism which has the counterweight20.

As shown inFIG. 4, the floating flap gate11according to the present invention may have a movable pulley18arranged behind the second fixed pulley17, and while the counterweight20is attached to the movable pulley18, the other end of the wire rope14may be secured to a securing member19disposed at the door bumper15via the movable pulley18.

As shown inFIG. 5, the floating flap gate11according to the present invention may have a compression pressure coil spring22attached, instead of the counterweight20. A tension coil spring may be attached, although it is not shown in the drawing. Reference Numeral23inFIG. 5is a third fixed pulley which is disposed between the movable pulley18and the securing member19. The compression coil spring22or the tension coil spring may come in direct contact with the other end of the wire rope14as shown inFIG. 1andFIG. 2, instead of having the movable pulley18disposed between them, as shown inFIG. 5.

If the compression coil spring22is used, in the case of a flap gate having a door body12with an angle of inclination θ of 90° when raising of the door body12is completed, the spring reaches its natural length as shown inFIG. 6(a) when the angle of inclination θ of the door body12is 45°, and, as shown inFIG. 6 (c), the swinging force of the door body in the direction of rising is set to reach a minimum by means of the spring. Further, when the angle of inclination θ of the door body12is 0° and 90°, the spring is compressed as shown inFIG. 6 (b), and the swinging force of the door body in the direction of rising is set to reach a maximum by means of the spring, as shown inFIG. 6 (c).

On the other hand, if a tension coil spring24is used, the spring reaches its natural length as shown inFIG. 7 (a)when the angle of inclination θ is 45°, and when the angle of inclination θ is 0° and 90°, the spring becomes extended, as shown inFIG. 7 (b).

The compression coil spring22or the tension coil spring24is not limited to the linear coil spring as shown inFIG. 6orFIG. 7. A spring which has non-linear properties such as a taper coil spring, a conical coil spring, a cylindrical coil spring, a barrel-shaped spring, or an irregular pitch coil spring may be used.

As shown inFIG. 8, a combination coil spring25formed from a large-diameter and short-length first compression spring25a, a medium-diameter and medium-length second compression spring25b, and a small-diameter and long-length third compression spring25carranged sequentially from the central axis, may be used to produce a tensile force which is non-linear.

When the combination coil spring25shown inFIG. 8is used, and the angle of inclination θ of the door body12is 0°, the three compression springs25a-25care all in a state of compression. Further, from the initial stage of rising to the early stage of rising of the door body12, when the angle of inclination of the door body12is about 10-30°, the three compression springs25a-25ceach start to expand, and when the early stage of rising is reached, the first compression spring25areturns to its original state.

Next, from the early stage of rising to the intermediate stage of rising when the angle of inclination θ of the door body12is 45°, the second compression spring25band the third compression spring25csuccessively return to their original state, and the three compression springs25a-25call return to their natural length.

From the intermediate stage of rising to the completion of rising when the angle of inclination θ of the door body12is 90°, the third compression spring25c, the second compression spring25b, and the first compression spring25asuccessively contract, and when raising of the door body12is completed, the three compression springs25a-25care all in a compressed state.

When lowering the door body, the state is the reverse of that for when raising the door body.

FIG. 9shows the relationship between the angle of inclination θ of the door body12and the swinging force of the door body in the direction of rising due to the non-linear combination coil spring25.

FIG. 1,FIG. 2,FIG. 4, andFIG. 5show examples in which a single rod13is attached across the entire width of the door body12, but inFIG. 10, the rod13may be attached only to both sides of the door body12.

The present invention is not limited to the above-described example, and the preferred embodiment may, of course, be advantageously modified within the scope of the technical ideas recited in the claims.

For example, the wire rope14was used in the above example, but a polyamide-series, polyester-series, polyethylene-series, polypropylene-series, aramid-series, polyarylate-series, or ultra-high density synthetic fiber rope may be used.

FIG. 1,FIG. 2,FIG. 4, andFIG. 5show a floating flap gate in which the door body12is a single floating body, but floating body connection-type flap gate may be used, in which a plurality of floating bodies are connected in a direction of height.

The movable pulley18, the counterweight20, and the springs22,24, and25may be attached at a position on the outside of the door bumper15, but the weight of the counterweight20, the number of fixed pulleys16,17and movable pulleys18, and the characteristics of the springs22,24,25may, of course, be set at the most appropriate values depending on the size of the door body12.

Moreover, instead of attaching the rod13, a hanging piece may be attached to the forward end of the door body12, and one end of the wire rope14may be attached to the hanging piece.

EXPLANATION OF THE REFERENCE NUMERALS

22Compression coil spring

24Tension coil spring

25Combined coil spring