Method for determining the engine torque delivered by a multi-cylinder engine

A method for determining the engine torque delivered by a multi-cylinder engine, comprising at least one cylinder fitted with a cylinder pressure sensor and at least one cylinder not fitted with a cylinder pressure sensor, said engine comprising a crankshaft driven by pistons moving in the cylinders, and means of determining the velocity of the crankshaft, wherein the method comprises the following steps:

• Step 1:
• determining the angular velocity of the crankshaft over an angular window (Segref) comprising the combustion in a current engine cycle of a first cylinder fitted with a cylinder pressure sensor,
• Step 2:
• measuring the cylinder pressure over said angular window (Segref) in said current engine cycle of the first cylinder,
• Step 3:
• calculating the value of the indicated engine torque (TQIref) in said angular window in said current engine cycle of the first cylinder, based on said measured cylinder pressure,
• Step 4:
• determining a current transfer function for the learning of the engine torque, so as to estimate the indicated engine torque (TQImdl(cyl)) in at least a second cylinder not fitted with a cylinder pressure sensor, following said first cylinder in the direction of rotation of the crankshaft, from the product of:
• the indicated engine torque (TQIref) calculated over said angular window (Segref) in said current engine cycle of the first cylinder, and
• a ratio between:
• the angular velocity (ncyl(i)) of the crankshaft over an angular window (Segn+1) comprising the combustion in a current engine cycle of the second cylinder, following said current engine cycle of the first cylinder, and
• the angular velocity (nref(i)) of the crankshaft over said angular window (Segref) comprising the combustion in said current engine cycle of the first cylinder;
• Step 5:
• applying said current transfer function for learning of the engine torque to each engine cycle of a cylinder not fitted with a cylinder pressure sensor, following said first cylinder, until the next engine cycle of a cylinder fitted with a cylinder pressure sensor;
• Step 6:
• updating said current transfer function for learning of the engine torque, reiterating the preceding steps until determining a new current transfer function for learning of the engine torque, during said next engine cycle of a cylinder fitted with a cylinder pressure sensor.