Flow rate control valve

A flow rate control valve, comprising:

• a valve housing;
• and
• a valve body to be driven by a drive source,
• wherein the flow rate control valve is configured to control a flow rate of a fluid flowing through a through-flow passage in a direction opposite a closing direction of the valve body, by moving the valve body from a control region to a closing region,
• the valve housing has a large diameter hole and a small diameter hole which communicates with the large diameter hole in an axial direction,
• the through-flow passage is defined by the valve body, the large diameter hole and the small diameter hole,
• a valve seat is provided at a border between the large diameter hole and the small diameter hole,
• the valve body includes a contact portion which is brought into contact with and separated from the valve seat, and a corner portion which is provided at an edge of an outer peripheral surface of the valve body,
• the contact portion of the valve body and the valve seat cooperatively form a closing portion,
• an inner peripheral surface of the large diameter hole and the corner portion of the valve body cooperatively from a throttle portion,
• the closing region is a stroke range of the valve body in which an opening area of the throttle portion is larger than an opening area of the closing portion,
• the control region is a stroke range of the valve body in which the opening area of the throttle portion is smaller than the opening area of the closing portion,
• the valve body has an effective pressure-receiving area where a pressure of the fluid acts on the valve body, the effective pressure-receiving area being switched, in accordance with a movement of the valve body in the axial direction, between a control regional effective pressure-receiving area that exists when the valve body is positioned in the control region and a closing regional effective pressure-receiving area that exists when the valve body is positioned in the closing region, and
• the closing regional effective pressure-receiving area is smaller than the control regional effective pressure-receiving area.