Abstract: An improved expansion valve is provided, which has a simple configuration and with which noise can be reduced. An expansion valve includes a valve main body having a valve chamber and a valve seat, a valve body configured to prevent passage of a fluid by being seated on the valve seat and allow passage of the fluid by separating from the valve seat, a coil spring configured to urge the valve body toward the valve seat, and an actuation rod configured to press the valve body toward a direction separating from the valve seat against an urging force applied from the coil spring, wherein the valve chamber includes a cylindrical inner wall being connected to the valve seat, the valve body includes a contact portion configured to be seated on the valve seat and a body portion having a tubular shape facing the inner wall, and the body portion includes connecting surfaces that are slidably in contact with the inner wall and plane surfaces that have a gap provided between the inner wall.

Abstract: A diaphragm includes a flange and a protrusion provided to protrude to one side of the flange, wherein the protrusion has at least two annular curved portions provided annularly on a ceiling portion having a flat surface-like shape and an outer side in a radial direction of the ceiling portion, in a state where pressure on an outer wall side of the protrusion and pressure on an inner wall side of the protrusion are the same, the at least two annular curved portions are each formed to be curved in a cross-section of the diaphragm obtained by cutting the diaphragm by a virtual plane including a center line of the diaphragm, the centers of curvature of the curved portions being arranged at different positions on a side opposite to a protruding direction of the protrusion, and the diaphragm is formed of a sheet metal.

Abstract: A diaphragm includes a flange and a protrusion provided to protrude to one side of the flange, wherein the protrusion has at least two annular curved portions provided annularly on a ceiling portion having a flat surface-like shape and an outer side in a radial direction of the ceiling portion, in a state where pressure on an outer wall side of the protrusion and pressure on an inner wall side of the protrusion are the same, the at least two annular curved portions are each formed to be curved in a cross-section of the diaphragm obtained by cutting the diaphragm by a virtual plane including a center line of the diaphragm, the centers of curvature of the curved portions being arranged at different positions on a side opposite to a protruding direction of the protrusion, and the diaphragm is formed of a sheet metal.