| 摘要 |
PURPOSE: To reduce injection rate during light load operation and reduce noise, hydrocarbon and nitrogen oxide emissions by effectively limiting opening of a poppet valve during light load engine operation by means of an actuating piston. CONSTITUTION: Fuel injection pressure acts on an upper surface 53 of an actuating piston 46, force is transferred to a stem 30 and a poppet valve 22 is moved countering a spring 34. Fuel flows to upper and lower orifices 58, 60 through passages 42, 54, 56. The area of the actuating piston 46 and the characteristics of a spring 34 move the poppet valve 22 sufficiently to expose the orifice 58 in response to the injection pressure during light load engine operation. During light load operation, only the lower orifice 58 is used and fuel injection rate is reduced so that noise, hydrocarbon and nitrogen oxide emissions can be reduced. During heavy load operation, the poppet valve 22 is moved in response to a high injection pressure until a shoulder 64 collides with a stop member 38 to expose the orifices 58, 60 below the lower end portion 28 for delivering the fuel necessary for operation.
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