| 摘要 |
A method for engine retardation with a multi-cylinder combustion engine, which for each cylinder with matching piston has an exhaust valve for control of the connection between a combustion chamber in the cylinder and an exhaust system. Opening of the exhaust valve for engine retardation is achieved by regulation of a clearance in the engine valve mechanism and thereby engaging one or more extra cam ridges on the engine camshaft, which continuously activates the valve mechanism in dependence of the momentary position of the engine crankshaft, using an actively adjustable, hydraulically operated clearance regulating device. For active control of the engine retardation said device is adjusted between different positions by means of a hydraulic fluid pressure lower than a maximum value controlled by a pressure relief valve. The angular position of the camshaft, at which the exhaust valves are being opened by said extra cam ridge or ridges is depending on the momentary clearance in the valve mechanism. The clearance is gradually brought to zero or close to zero while the pressure in the corresponding clearance regulating device is limited to a certain predetermined value. Independently of when in time during the cylinder work cycle the engine retardation is initiated or terminated, the risk of an opening against a, form a stress aspect, too high cylinder pressure is herby eliminated.
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