Diaphragm valve

A diaphragm valve comprising:

• a flow path-side body forming an inflow flow path, an outflow flow path and a valve seat;
• a driving-side body in which a piston for moving a valve body with respect to the valve seat is placed;
• and
• a diaphragm placed on one end side of the piston, in which
• the diaphragm includes a thick portion connected to the piston,
• a membrane portion formed on an outer periphery of the thick portion, and
• a fixed portion formed on an outer periphery of the membrane portion,
• the fixed portion includes a first fixed portion located on a side of the membrane portion, and
• a second fixed portion located on an outer periphery of the first fixed portion,
• a first fixed portion piston-side end surface is formed in the first fixed portion on a side of the piston, a first fixed portion valve body-side end surface is formed in the first fixed portion on a side of the valve body, a second fixed portion piston-side end surface is formed in the second fixed portion on a side of the piston, a second fixed portion valve body-side end surface is formed in the second fixed portion on a side of the valve body, a second fixed portion inner peripheral surface is formed on an inner peripheral side of the second fixed portion, and a second fixed portion outer peripheral surface is formed on an outer peripheral side of the second fixed portion, and
• the fixed portion is mounted on the flow path-side body by a diaphragm-holder, wherein
• the flow path-side body includes a body-side first end surface which brings the first fixed portion valve body-side end surface and the second fixed portion valve body-side end surface into abutment against each other, and
• a body-side ring-shaped projection forming a body-side projection inner peripheral surface against which the second fixed portion outer peripheral surface abuts,
• the diaphragm-holder includes a diaphragm-holder inner peripheral side ring-shaped projection, and a diaphragm-holder outer peripheral side ring-shaped projection located on an outer periphery of the diaphragm-holder inner peripheral side ring-shaped projection,
• a diaphragm-holder abutting surface is formed between the diaphragm-holder inner peripheral side ring-shaped projection and the diaphragm-holder outer peripheral side ring-shaped projection, the diaphragm-holder abutting surface being a single straight surface extending perpendicularly from the diaphragm-holder outer peripheral side inner peripheral surface to the diaphragm-holder inner peripheral side outer peripheral surface,
• a diaphragm-holder inner peripheral side end surface of the diaphragm-holder inner peripheral side ring-shaped projection is abutted against the first fixed portion piston-side end surface,
• a diaphragm-holder inner peripheral side outer peripheral surface of the diaphragm-holder inner peripheral side ring-shaped projection is abutted against the second fixed portion inner peripheral surface,
• a diaphragm-holder outer peripheral side inner peripheral surface of the diaphragm-holder outer peripheral side ring-shaped projection is abutted against a body-side projection outer peripheral surface of the body-side ring-shaped projection, and
• the diaphragm-holder abutting surface, which is the single straight surface extending perpendicularly from the diaphragm-holder outer peripheral side inner peripheral surface to the diaphragm-holder inner peripheral side outer peripheral surface and is surrounded by the diaphragm-holder inner peripheral side ring-shaped projection and the diaphragm-holder outer peripheral side ring-shaped projection, is abutted against the second fixed portion piston-side end surface and a body-side projection end surface of the body-side ring-shaped projection.