Abstract: An inlet valve arrangement for a pump head of a fuel pump for use in a common rail fuel injection system comprises an inlet valve member moveable between open and closed positions to control the flow from a source of low-pressure fuel to a pumping chamber of the fuel pump. The inlet valve member is arranged to open in response to the pressure difference between the fluid pressure of fuel on an inlet side of the inlet valve member and the fluid pressure in the pumping chamber exceeding a threshold value. The inlet valve arrangement comprises means for selectively applying a closing force on the inlet valve member to bias it toward the closed position, such that, in use, the application of the closing force by said means acts to increase the threshold value of the pressure difference at which the inlet valve member opens.

Abstract: An inlet valve arrangement for a pump head of a fuel pump for use in a common rail fuel injection system comprises an inlet valve member moveable between open and closed positions to control the flow from a source of low-pressure fuel to a pumping chamber of the fuel pump. The inlet valve member is arranged to open in response to the pressure difference between the fluid pressure of fuel on an inlet side of the inlet valve member and the fluid pressure in the pumping chamber exceeding a threshold value. The inlet valve arrangement comprises means for selectively applying a closing force on the inlet valve member to bias it toward the closed position, such that, in use, the application of the closing force by said means acts to increase the threshold value of the pressure difference at which the inlet valve member opens.

Abstract: A gas-injection valve for injecting gaseous fuel into the combustion chamber of an internal combustion engine, comprising a valve housing and, disposed therein, a longitudinally displaceable piston having connected thereto a poppet valve for controlling an injection port, which poppet valve opens in the direction of gas flow, said piston separating a gas space from an operating space adapted to be pressurized by having hydraulic control fluid fed thereto by a pressure pump, and the gas pressure within the gas space alone being sufficient to move the poppet valve to and to hold it in its closed position when the operating space is depressurized.