| 摘要 |
PURPOSE:To prevent stock liquid from solidifying in a mixing head during low pressure circulation by a method wherein a low pressure circulating flow path is provided in the mixing head so as to give the mixing head itself low pressure circulating function. CONSTITUTION:When a control piston 23 takes a first position, a low pressure admission flow path 27 and a low pressure return flow path 28 are connected through low pressure circulating grooves 24 with each other so as to flow stock liquid from a stock liquid inlet 31 through a low pressure circulating flow path to a stock liquid return port 32 in order to prevent the stock liquid from solidifying. When the control piston 23 takes a second position, injection nozzles 26 and a high pressure return flow path 29 are connected through a high pressure circulating grooves 25 with each other and at the same time the low pressure circulating flow path is closed so as to flow stock liquid from the inlet 31 through the high pressure return flow path to the return port 32. When the control piston 23 takes a third position, a plurality of the injection nozzles 26 are open in a stock liquid injection chamber 22 and at the same time both the low pressure and high pressure circulating flow paths are closed, resulting in injecting stock liquid, which enters from the inlet 31, outside. |
