| 摘要 |
PURPOSE:To satisfy the cut-off of fuel injection, by arranging, around a main needle valve, an auxiliary needle valve provided with an oil sump and a spring, an oil passage branched off from a fuel introduction passage and led to the oil sump in the auxiliary needle valve, a check valve disposed in the oil passage and a restrictor disposed in parallel with the check valve. CONSTITUTION:When pressure in an oil sump 101 exceeds a valve opening pressure P0 due to pressure wave from a fuel injection pump, a main needle valve 3 is lifted so that a check valve 10 is opened to make a restrictor ineffective and pressure in the oil sump becomes also the valve opening pressure P0. As a result, an auxiliary needle valve 13 is also lifted simultaneously with the main needle valve 3, thereby fuel is injected from an injection port 8. After the completion of a discharge by the fuel injection pump, the main needle valve 3 is seated. During this stage, the check valve is still opened so that a decrease in the volume of the oil sump 101 is absorbed by the volume of the auxiliary needle valve. On the auxiliary needle valve side the check valve 10 is closed by a spring 11 dut to pressure drop, and therefore, fuel is subjected to restriction by the restrictor 12. Therefore, by suitably selecting a restricting value, the rate of pressure drop may be controlled so that the auxiliary needle valve 13 is lowered after the main needle valve 3 is seated. Accordingly, the portion of fuel of volume variation upon descent of the auxiliary needle valve 13 is not injected through the injection port 8 so that the cut-off of fuel injection is made satisfactory. |
