Patent ID: 8622073
Filing Date: 2014-01-07
Classification: H01L,Y10T

Abstract:
1. An apparatus for controlling a flow rate of a liquid, comprising: a plurality of flow rate control units installed in parallel; and a controller configured to control the plurality of flow rate control units so that a total flow rate of liquids that flows on the plurality of flow rate control units becomes a required value of a total flow rate to be implemented by the plurality of flow rate control units, wherein the plurality of flow rate control units include at least a first flow rate control unit and a second flow rate control unit, the first flow rate control unit includes a first flow rate control valve with a first controlled flow rate range, the second flow rate control unit includes a second flow rate control valve with a second controlled flow rate range, the first controlled flow rate range is smaller than the second controlled flow rate range, and an overlapped range is present between the first controlled flow rate range and the second controlled flow rate range, the controller is configured to control the first and second flow rate control units to allow the liquid to flow on either one or both of the first and second flow rate control units depending on variation of the required total flow rate, the controller is configured to control the first and second flow rate control units to increase the flow rate at one of the first and second flow rate control units while maintaining the flow rate at the other of the first and second flow rate control units during the course of increasing the total flow rate of the liquid that flows on the first and second flow rate control units, and while increasing the total flow rate of the first and second flow rate control units from a first state in which the liquid only flows on the first flow rate control unit, when the flow rate of the first flow rate control unit, that corresponds to the total flow rate at the first state increases up to a first value within the overlapped range, the controller is configured to control the first and second flow rate control units so that the first state is changed to a second state in which the liquid flows both on the first and second flow rate control units, and in this case, the flow rate of the first flow rate control unit decreases and the liquid starts to flow onto the second flow rate control unit so as not to change the total flow rate of the first and second flow rate control units.