To make it possible to stop the water filling into a cylinder even when there occurs failure of a solenoid valve for switching an operation of a main valve which opens or closes a passage between a water pressure source unit and an injection valve.
A first solenoid valve 11 opens or closes an introduction passage 17 for introducing working fluid to a back pressure chamber 23. A second solenoid valve 12 opens or closes a discharge passage 18 for discharging the working fluid from the back pressure chamber 23. A limiter cylinder 14 is arranged between the main valve 10 and the water pressure source unit 2 and it has a piston 29 and a pressure chamber 30 and a water supply chamber 31 which are separated by the piston 29. The pressure chamber 30 is connected to the water pressure source unit 2. The water supply chamber 31 is connected to the water pressure source unit 2 via a third solenoid valve 13 and also connected to a water pressure source unit side port 24, and is provided with a spring 33 for energizing the piston 29 toward the pressure chamber 30.
TSURU NOBUYUKI
KUBOYAMA YUTAKA
Makoto Suhara