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DI07-23 CHANGED BY EFFECTIVE DATE AFFECTED VIN FUEL SYSTEM DI ENG SM - 2004.9 <Pressurize> Principle of operation • During the filling phase, the rollers are kept in contact with the cam by means of coil springs mounted on either side of each shoe. The transfer pressure is sufficient to open the inlet valve and to move the pumping plungers apart. • When the diametrically opposite rollers simultaneously encounter the leading edge of the cam, the plungers are pushed towards each other. • As soon as the pressure becomes higher than the transfer pressure, the inlet valve closes. When the pressure becomes higher than the pressure inside the rail, the delivery valve opens. Consequently, the fuel is pumped under • During the input phase, transfer pressure pushes back the inlet valve. Fuel enters the body of the pumping element. The valve closes as soon as the pressure in the pumping element becomes higher than the transfer pressure. • During the input phase, the ball of the delivery valve is subject to the rail pressure on its outer face and to the transfer pressure on its inner face. Thus the ball rests on its seat, ensuring the pressure tightness of the body of the pumping This high pressure pump generates the driving torque with low peak torque to maintain the stress to driving components. <Fuel input> Roller Plunger |