Valve device

A valve device comprising:

• a valve having a ball surface having a convex spherical shape protruding outward in a radial direction with a center corresponding to a rotation axis, and a first opening opened in the ball surface to allow fluid to pass through;
• and
• a seat having an annular shape and opposing to be in sliding contact with the ball surface, the seat being pressed against the ball surface, the seat having a second opening being able to communicate with the first opening, wherein the valve is made to move both-way in a rotational direction to perform at least open and close operation,
• a clearance is defined by the seat and the valve to make an area in which the seat and the valve are in sliding contact at a valve open time when the first opening and the second opening overlap with each other smaller than an area in which the seat and the valve are in sliding contact at a valve closed time when the ball surface and the second opening overlap with each other,
• the seat is in sliding contact with the valve at the valve open time,
• the ball surface has first and second ridge parts protruding outward in the radial direction along a periphery of the first opening, and
• the first and second ridge parts are separated along a direction along the rotation axis and extend in in a circumferential direction around the rotation axis of the valve.

A valve device comprising:

• a valve having a ball surface having a convex spherical shape protruding outward in a radial direction with a center corresponding to a predetermined rotation axis, and a first opening opened in the ball surface to allow fluid to pass through;
• and
• a seat having an annular shape and opposing to be in sliding contact with the ball surface, the seat being pressed against the ball surface, the seat having a second opening being able to communicate with the first opening, wherein the valve is made to move both-way in a rotational direction to perform at least open and close operation;
• a clearance is defined by the seat and the valve to make an area in which the seat and the valve are in sliding contact at a valve open time when the first opening and the second opening overlap with each other to be smaller than an area in which the seat and the valve are in sliding contact at a valve closed time when the ball surface and the second opening overlap with each other;
• the seat is in sliding contact with the valve at the valve open time;
• the ball surface has a ridge part protruding outward in the radial direction;
• the clearance is defined by the ridge part and a seal surface of the seat in sliding contact with the ball surface at the valve closed time;
• the clearance is formed along an outer periphery of the first opening;
• the ridge part has a chamfering part on a side away from the first opening;
• and
• the chamfering part has a taper shape inclined to gradually increase a thickness of the ridge part outward in the radial direction as approaching a top surface of the ridge part.