Flowing-down rainwater filtration device and rainwater storage device using the same

A flowing-down rainwater filtration device (20) interposed between an upper vertical pipe (21a) and a lower vertical pipe (21b) coaxial with the upper vertical pipe (21a) for filtrating rainwater flowing down through the upper vertical pipe (21a) and guiding the rainwater to the lower vertical pipe (21b), comprising:

• a housing (22) attached to a lower part of the upper vertical pipe (21a) and an upper part of the lower vertical pipe (21b) from above and below and having a rainwater flow chamber (23) interposed between the upper vertical pipe (21a) and the lower vertical pipe (21b) and a valve chamber (24) adjacent to the rainwater flow chamber (23);
• an upper rainwater hole (23a) formed at an upper part of the rainwater flow chamber (23) for having the rainwater flow chamber (23) communicate with the upper vertical pipe (21a) so as to have the rainwater flowing down through the upper vertical pipe (21a) flow into the rainwater flow chamber (23) ;
• a lower rainwater hole (23b) formed at a lower part of the rainwater flow chamber (23) for having the rainwater flow chamber (23) communicate with the lower vertical pipe (21b) so as to have the rainwater flowing into the rainwater flow chamber (23) flow down to the lower vertical pipe (21b);
• 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 (23b) 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 (24b) 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).