| 摘要 |
A fuel injection pump includes a barrel mounted in a barrel mounting hole in a pump body. The barrel has a cylinder hole and a valve mounting hole which are coaxial with the barrel. The inner peripheral surface of the cylinder hole and the inner peripheral surface of said valve mounting hole are interconnected by an annular shoulder surface. A plunger is slidably received in the cylinder hole, and a delivery valve is mounted in the valve mounting hole. The delivery valve includes a valve seat, and a valve holder which is tightly threaded into the valve mounting hole, so that the valve seat is firmly held between the valve holder and the shoulder surface of the barrel. One end face of said valve seat is held in direct contact with the barrel shoulder surface under a high pressure. In order to achieve a good contact between the two to provide a good seal therebetween, the hardness of the barrel shoulder surface is not more than HV400; however, the inner peripheral surface of the cylinder hole with which the plunger is in sliding contact has a hardness of not less than HV750.
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