Patent ID: 7775232

Claim:
A flowing-down rainwater filtration device ( 20 ) interposed between an upper vertical pipe ( 21 a ) and a lower vertical pipe ( 21 b ) coaxial with the upper vertical pipe ( 21 a ) for filtrating rainwater flowing down through the upper vertical pipe ( 21 a ) and guiding the rainwater to the lower vertical pipe ( 21 b ), comprising: a housing ( 22 ) attached to a lower part of the upper vertical pipe ( 21 a ) and an upper part of the lower vertical pipe ( 21 b ) from above and below and having a rainwater flow chamber ( 23 ) interposed between the upper vertical pipe ( 21 a ) and the lower vertical pipe ( 21 b ) and a valve chamber ( 24 ) adjacent to the rainwater flow chamber ( 23 ); an upper rainwater hole ( 23 a ) formed at an upper part of the rainwater flow chamber ( 23 ) for having the rainwater flow chamber ( 23 ) communicate with the upper vertical pipe ( 21 a ) so as to have the rainwater flowing down through the upper vertical pipe ( 21 a ) flow into the rainwater flow chamber ( 23 ) ; a lower rainwater hole ( 23 b ) formed at a lower part of the rainwater flow chamber ( 23 ) for having the rainwater flow chamber ( 23 ) communicate with the lower vertical pipe ( 21 b ) so as to have the rainwater flowing into the rainwater flow chamber ( 23 ) flow down to the lower vertical pipe ( 21 b ); a ball valve ( 29 ) with a specific gravity less than 1 and accommodated in the housing ( 22 ) movably between the rainwater flow chamber ( 23 ) and the valve chamber ( 24 ) for blocking the lower rainwater hole ( 23 b ) when the rainwater in the rainwater flow chamber ( 23 ) is less than a predetermined amount and the ball valve is disposed in the rainwater flow chamber ( 23 ); a storage chamber ( 27 ) communicating with the valve chamber ( 24 ) and provided at a lower part of the housing ( 22 ), for storing the rainwater having reached the valve chamber ( 24 ) from the rainwater flow chamber ( 23 ); a valve-seat opening portion ( 24 b ) formed at an upper part of the housing ( 22 ) opposed to the storage chamber ( 27 ) so as to open the valve chamber ( 24 ) and being capable of sealing the valve chamber ( 24 ) by being blocked with the ball valve ( 29 ) when the rainwater in the rainwater flow chamber ( 23 ) is not less than the predetermined amount and the ball valve ( 29 ) is disposed in the valve chamber ( 24 ); an upper guiding member ( 31 ) provided at the rainwater flow chamber ( 23 ) and for guiding the ball valve ( 29 ) rising in the rainwater flow chamber ( 23 ) from the rainwater flow chamber ( 23 ) to the valve chamber ( 24 ); and a lower guiding member ( 32 ) provided at the valve chamber ( 24 ) and for guiding the ball valve ( 29 ) lowering in the valve chamber ( 24 ) from the valve chamber ( 24 ) to the rainwater flow chamber ( 23 ).