A cavity air inlet flow velocity adjusting device

The invention relates to an air inlet flow velocity adjusting device, in particular to an adjusting device which can change air inlet velocity with the change of cavity air inlet flow in the manufacture of semiconductors. The device can adjust air inlet flow velocity and enables air inlet velocity to decrease along with the increase of air flow quantity. The device comprises an air cylinder air inlet pipe, a pressure adjusting valve, a small hole blocking sheet, an air cylinder, a piston, a spring, a piston rod, a connecting rod, a valve body, a valve plate rod, a valve plate and an air inlet pipe, which form an air cylinder execution part and a valve body part. The increase of air inlet quantity can change the displacement of the piston; the piston rod can make the valve plate rotate via the connecting rod and the valve plate rod, and the rotation of the valve plate can adjust the flow velocity of air inlet. When air in a cavity is discharged or extracted out and the air pressure in the cavity becomes stable