| 摘要 |
<p>1. A fuel injection system for injecting fuel into a combustion chamber of an internal combustion engine, especially of a diesel engine operable by the direct fuel injection method, the system comprising an injection pump (1) arranged to be driven by the internal combustion engine and fitted with a cam spindle (2), and comprising at least one injection valve (6) associated with the pump (1) and having an axially arranged nozzle needle (22), in which a choke (7) disposed in the valve's fuel inlet (5) is disconnectable by a high-pressure relief valve (8) also disposed in the fuel inlet (5) and arranged to open in the fuel's direction of flow, and in which a reduced value of the pump's (1) maximum feed pressure prevails, at the start of the injection operation, at the nozzle needle (22) and by means of which the needle (22) is lifted, characterized in that the cam spindle (2) is provided with at least one cam (32), the curve of the cam lobe of which is, due to being divided into at least three sections (11, 12, 13), a stepped one thus rendering it possible to obtain the reduced value of the feed pressure, that the first section (11) of the cam lobe is constructed to rise tangent-like to a first value obtainable just when the injection starts, that the subsequent second section (12) is constructed so that this first value of the cam lobe either remains constant or rises only slightly across a constant angular range, that the cam lobe's subsequent third section (13) is constructed to rise tangent-like to the maximum value (31), and in that the gradient of the tangent-like lobe in the first and third sections (11, 13) is substantially the same.</p> |
