Patent ID: 8333216

Claim:
A blow-off valve for a turbo blower comprising: (a) a body part including a cylinder part, a valve-guide plate mounted on the cylinder part, and a head part mounted on the valve-guide plate for covering the valve-guide plate, wherein the cylinder part includes a blow-connection opening connected with a blow opening of a turbo blower and a blow-off opening connected with the blow-connection opening to blow off air emitted from the turbo blower through the blow-connection opening; (b) a disk valve having a blow-pressure disk located between the blow-connection opening and the blow-off opening in the cylinder part, a blow-pressure opposing disk located between the valve-guide plate and the head part, and a stem which penetrates the valve-guide plate and couples the blow-pressure disk and the blow-pressure opposing disk, wherein an internal space of the cylinder part between the blow-pressure disk and the blow-connection opening forms blow-pressure supply space and an internal space between the head part and the blow-pressure opposing disk forms blow-pressure opposing space, and a pressure applying area of the blow-pressure disk is smaller than a pressure applying area of the blow-pressure opposing disk; and (c) a three-way valve provided in the body part having a port connected with the blow-pressure supply space, a port connected with the blow-pressure opposing space and a port connected with an external atmosphere external to the body part, the three-way valve shutting off the port connected with the blow-pressure supply space to connect the blow-pressure opposing space and the external atmosphere at early operation stage of the turbo blower so that the blow-pressure disk of the disk valve moves to open the connection of the blow-connection opening and the blow-off opening and shutting off the port connected with the external atmosphere to connect the blow-pressure supply space and the blow-pressure opposing space so that the blow-pressure disk of the disk valve moves to close the connection of the blow-connection opening and the blow-off opening wherein the three-way valve is mounted on the head part and a ring is mounted on the lower surface of the head part, an area formed inside the ring being larger than the pressure applying area of the blow-pressure disk; wherein the port of the three way valve connected with the blow-pressure opposing space is directly attached to a center portion of the head part and the ring further comprises a two layer arrangement centered on the center portion of the head part and in axial alignment with the port of the three way valve connected with the blow-pressure opposing space so as to provide the pressure applying area to the inside of the ring when the blow-pressure disk moves to close the connection of the blow-connection opening and the blow-off opening.