ac93ca6a_goya_Shi___Patent_applications__Description
[Patent application number] 20140182716 [Published] 07-03-2014 [Description] 
FLOW CONTROL VALVES - An embodiment of a flow control valve includes a housing and a valve member. The valve member is movable in an axial direction within the housing, so that a flow rate of a fluid flowing within the housing changes in response to a position of the valve member within a control range in the axial direction. A spring device biases the valve member in the axial direction, so that the valve member moves in the axial direction against a biasing force of the spring device according to a difference in pressure on an upstream side and a downstream side of the valve member. The spring device includes a spring constant that changes according to the position of the valve member in the axial direction within the control range.
Yamada, Nagoya-Shi - Patent applications