| 摘要 |
PURPOSE:To enlarge a leak orifice area and improve the cut of injection by a method wherein a valve opening force, due to high fuel pressure acting on the head of a valve body, is balanced by the same fuel pressure acting on the back of the valve body. CONSTITUTION:Fuel, pressurized by a fuel pump, is supplied to a pressure chamber through a path 8a and a solenoid valve 40. When a plunger is descended by the rotation of a cam and begins the pressurizing, the fuel pressure is released to the path 8a through the valve chamber 52 of the solenoid valve 40 and arrives at a back pressure chamber 72 through a pressure balance path 73. The fuel pressure at the upstream of the seat section of the head of valve body 43 is set so as to be substantially equal to the same pressure of the back pressure chamber 72 and the pressure receiving area of the valve body 43 is also set so as to be substantially equal in the head section and the back section thereof. Accordingly, the valve body 43 is not affected by the fuel pressure and is separated from the valve seat thereof by a spring 51. According to this constitution, the small electromagnetic force of the solenoid valve may be enough even if the diameter of the seat is enlarged comparatively and the leak orifice area is enlarged by the increase of the diameter of the seat, therefore, the cut of injection may be improved. |
