Patent ID: 8534311

Claim:
A vacuum valve including a valve element accommodated in a valve housing with an aperture, a shaft having an end portion connected to the valve element by attaching a surface of a wall formed on the valve element and a surface of a wall formed on the shaft to each other and fastening the surfaces of the walls to each other with a bolt, and a valve element driving unit that drives the shaft thereby causing the valve element to open and close the aperture, wherein: a column-shaped cartridge heater is accommodated in a circular heater bore formed in the shaft so as to extend in an axial direction thereof, and a heating portion provided at an end portion of the cartridge heater is located at a joint portion in which the surfaces of the walls of the shaft and the valve element are attached to each other; and at the joint portion, a heat receiving groove and a pressurizing portion each communicating with the heater bore are provided at corresponding positions between the surface of the wall of the valve element and the surface of the wall of the shaft located so as to oppose and to contact each other; the heat receiving groove is formed on the wall of the valve element and includes an arcuate groove portion of the same radius as the heating portion of the cartridge heater; and the pressurizing portion is formed on the wall of the shaft; and the heating portion is pressed by the pressurizing portion to come into plane-to-plane contact with an inner circumferential surface of the arcuate groove portion of the heat receiving groove, upon fastening the valve element and the shaft to each other with the bolt, with the heating portion located between the heat receiving groove and the pressurizing portion.