Method and arrangement for regulating crankshaft rotational speed

A method for shift gears associated with an internal combustion engine, said method comprising:

• regulating the rotational speed of a crankshaft included in an internal combustion engine during a gear changing process of a gearbox connected to the internal combustion engine, the internal combustion engine comprising a compressor mounted in connection with an air inlet of the internal combustion engine, a transmission having a variable gear ratio arranged between the crankshaft and a driving shaft arranged in connection with the compressor, and a control unit arranged to control the gear ratio between the crankshaft and the compressor;
• receiving a gear changing command to the control unit;
• identifying that a gear change from a higher to a lower gear is to be performed;
• and
• generating another control signal from the control unit which controls the gear ratio between the crankshaft and the compressor so that the gear ratio between these components is reduced and wherein a moment of inertia is transferred from the compressor to the crankshaft resulting in an acceleration of the crankshaft.

A gear changing process for a gearbox arranged at an internal combustion engine, the internal combustion engine comprising a crankshaft, a compressor mounted in connection with the air inlet of the internal combustion engine, a transmission having a variable gear ratio located between the crankshaft and a driving shaft arranged in connection with the compressor, and a control means which is arranged to control the gear ratio between the crankshaft and the compressor, the gear changing process comprising:

• receiving a gear changing command to the control means;
• disengaging clutch means which connects the internal combustion engine to the gearbox;
• identifying which one of a gear change from a higher to a lower gear, or from a lower to a higher gear is to be performed;
• generating another control signal from said control means which controls the gear ratio between crankshaft and compressor so that the gear ratio between these components is reduced in the case that a gear change from a higher to a lower gear is to be performed, and wherein moment of inertia is transferred from compressor to crankshaft resulting in an acceleration of the crankshaft;
• generating another control signal from said control means which controls the gear ratio between crankshaft and compressor so that the gear ratio between these components increased in the case that a gear change from a lower to a higher gear is to be performed, and wherein moment of inertia is transferred from crankshaft to compressor resulting in a retardation of the crankshaft;
• waiting until the crankshaft-rotational speed has been adapted to selected gear;
• shifting into a new desired gear;
• and
• connecting the engine and the gearbox.

An arrangement for regulating the rotational speed of a crankshaft included in an internal combustion engine during a gear changing process of a gearbox connected to the internal combustion engine, said arrangement comprising:

• a compressor mounted in connection with the air inlet of the internal combustion engine;
• a transmission having a variable gear ratio located between the crankshaft and a driving shaft arranged in connection with the compressor;
• and
• a control means arranged to control the gear ratio between the crankshaft and the compressor, the control means being arranged to control the gear ratio between the crankshaft and the compressor so that the gear ratio between these components is reduced when changing from a higher to a lower gear and wherein moment of inertia is transferred from the compressor to the crankshaft resulting in an acceleration of the crankshaft.