Torque-calculating control system for an internal combustion engine

摘要

A control system for an internal combustion engine, which is capable of directly and properly calculating the most fuel-efficient torque according to operating conditions of the engine without setting or learning in advance operating lines indicative of the most fuel-efficient torques, thereby making it possible to reduce costs and enhance fuel economy. In the control system, when the engine is operated at a predetermined reference rotational speed, a plurality of fuel consumption ratio parameters associated with a plurality of estimated torques are calculated based on a provisional intake air amount-estimated torque relationship which is the relationship between provisional intake air amounts and estimated torques to be obtained when the provisional intake air amounts of intake air are supplied. Further, an estimated torque associated with a minimum value of the fuel consumption ratio parameters is calculated as the most fuel-efficient torque at the reference rotational speed.

主权项

1. A control system for an internal combustion engine, which calculates a most fuel-efficient torque that minimizes a fuel consumption ratio, and controls the engine based on the calculated most fuel-efficient torque, comprising:
air-fuel ratio control means for controlling an air-fuel ratio of a mixture burned in a combustion chamber to a predetermined target air-fuel ratio; most fuel-efficient torque-calculating means for calculating the most fuel-efficient torque generated when the engine is operated at one predetermined reference rotational speed; and a target throttle valve opening means for adjusting a throttle valve opening according to a target intake air amount which depends upon a target torque, wherein the most fuel-efficient torque-calculating means is used to calculate the target torque; wherein said most fuel-efficient torque-calculating means comprises: maximum intake air amount-calculating means for calculating, based on operating conditions of the engine, a maximum amount of intake air that can be drawn into the combustion chamber, as a maximum intake air amount, provisional intake air amount-setting means for setting a plurality of provisional intake air amounts different from each other within a range of an intake air amount, which ranges from 0 to the calculated maximum intake air amount, estimated torque-calculating means for calculating, based on the operating conditions of the engine, estimated torques that are estimated to be output from the engine assuming that the set plurality of provisional intake air amounts of intake air are drawn into the combustion chamber, respectively, as a plurality of estimated torques, provisional intake air amount-estimated torque relationship-setting means for setting a provisional intake air amount-estimated torque relationship, which is a relationship between the plurality of provisional intake air amounts and the plurality of calculated estimated torques, and fuel consumption ratio-calculating means for calculating a plurality of fuel consumption ratios associated with the plurality of estimated torques, respectively, based on the set provisional intake air amount-estimated torque relationship, wherein one of the plurality of estimated torques, associated with a minimum fuel consumption ratio of the plurality of calculated fuel consumption ratios, is calculated as the most fuel-efficient torque at the reference rotational speed.