In the CHECK VALVES having a valve seat member and the valve member, the valve seat member is provided with first and second conical seats. The second conical seat is positioned upstream the first conical seat. An angle of the second conical seat to an axis of the valve member is more acute than that of the first conical seat. Since the Check Valves has the second conical seat, contact pressure applied to the first conical seat is uniformly dispersed and, thus, the first conical seat is less worn out. Further, the second conical seat prevents the valve member from cutting into and sticking to the valve seat member, even if the wear has been progressed. Accordingly, an operation of the check valve is stable for a longer period of time.

Conventionally, there has been proposed a check valve that permits fluid to flow only in one direction in a fluid passage. The check valve is used, for example, in a fuel injection pump for an internal combustion engine (hereinafter called merely an engine). As one of the fuel injection pumps for the engine, is known a star-shaped pump in which a plurality of plungers arranged radially around a cam pressurize fuel sucked into fuel pressure chambers each provided f or each of the plungers. The fuel pressurized in the respective fuel pressure chambers are gathered into a pressure fuel delivery passage provided in a pump housing and, then, supplied therefrom to a common rail.

A low pressure fuel passage, through which fuel is sucked into the fuel pressure chamber, is provided with a low pressure check valve and a high pressure fuel passage, through which fuel pressurized by the plunger is delivered, is provided with a high pressure Check Valves. In particular, in the fuel injection pump in which amount of fuel to be sucked is regulated, higher accuracy of valve opening pressure of the low pressure check valve is required so that the valve opening pressure is less fluctuated in addition to ensuring fluid tight sealing. A valve member of the low pressure check valve is formed generally in conical shape.

Further, it is a recent tendency that higher load is applied to the valve member, since higher fuel injection pressure is required to reduce emission. To this end, face pressure of seat contact between a seat of a valve seat member and a valve of the valve member tends to be greater so that the seat of the valve seat member is more rapidly worn. As the wear is progressed, a step is formed in the seat. At this time, the valve is prone to cut or cling into the step due to pressure applied to the fuel pressure chamber. Accordingly, the valve member sticks to the step so that the fuel cannot be sucked.

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