PURPOSE: To dissipate beforehand danger of a diaphragm breaking when a feed pressure is lowered.
CONSTITUTION: A pump body 1 is provided with diaphragm 5 which is located between a chamber 8 for fluid to be fed with a pressure and a working oil chamber 9. When a plunger 11 is raised through rotation of a cam 16, a reset port 12 is first closed, working oil in the working oil chamber 9 is pressurized at a following raising stroke, and fluid to be fed with a pressure in the chamber 8 is indirectly pressurized through the diaphragm 5. The fluid to be fed with a pressure pressurized up to a feed pressure with the aid of a low pressure feed pump 22 is sucked in the chamber 8 from a tank 21. When a feed pressure is abnormally lowered, the abnormal reduction is transmitted to a forced feed stop valve 25 through a sensing pipe 37 to move a diaphragm 27 to the left. A poppet valve 33 is opened and the working oil is released in a cam chamber 19 through a drain pipe 35 after the passage of it through a relief pipe 34. This constitution prevents the occurrence of deformation of the diaphragm 5 and the occurrence of breakage thereof.
ITO TOSHIHIKO
SAKAKIBARA YASUYUKI
WATANABE KAZUHIDE
