Air-fuel ratio control apparatus for an internal combustion engine

Claim 2

An air-fuel ratio control apparatus for an internal combustion engine adapted to measure an intake air quantity and an engine revolution number to thereby calculate a basic fuel injection quantity based on said measured intake air quantity and said engine revolution number and to output an instruction signal to inject an amount of fuel to a cylinder, which comprises a pressure detecting means to detect an inner pressure of cylinder, a crank angle detecting means to detect a crank angle of the engine, and a control device which is adapted to receive the output signals of said pressure detecting means and said crank angle detecting means so as to obtain the maximum value of a rate of pressure increase in an ignition cycle of the engine or the mean value of the maximum values in a predetermined number of cycles of the engine, and to control a fuel injection quantity in response to the thus obtained maximum value or the mean value.

Claim 3

The air-fuel ratio control apparatus according to claim 1, wherein said control device effects a feed-back control of an air-fuel ratio by the maximum value of a rate of pressure increase or the mean value of the maximum values in a predetermined number of cycles.

Claim 4

The air-fuel ratio control apparatus according to claim 1, wherein a rate of pressure increase per a unit crank angle in an ignition cycle or a rate of pressure increase per unit time is used in order to obtain said maximum value.

Claim 5

The air-fuel ratio control apparatus according to claim 2, wherein said control device is adapted to stop said feed-back control of an air-fuel ratio when said maximum value of a rate of pressure increase or the mean value of the maximum values in a predetermined number of ignition cycles is out of a predetermined range.

Claim 6

An air-fuel ratio control apparatus for an internal combustion engine adapted to measure an intake air quantity and an engine revolution number to thereby calculate a basic fuel injection quantity based on said measured intake air quantity and said engine revolution number and to output an instruction signal to inject an amount of fuel to a cylinder, which comprises a pressure detecting means to detect an inner pressure of cylinder, a crank angle detecting means to detect a crank angle of the engine, an exhaust gas temperature detecting means to detect a temperature of exhaust gas and a control device which is adapted to receive the output signals of said pressure detecting means, said crank angle detecting means and said exhaust gas temperature detecting means, to calculate a state quantity based on the signals of said inner pressure of cylinder in an ignition cycle, and to control a fuel injection quantity by using said state quantity and a value of exhaust gas temperature T e obtained by the output of said exhaust gas temperature detecting means.

Claim 7

An air-fuel ratio control apparatus for an internal combustion engine adapted to measure an intake air quantity and an engine revolution number to thereby calculate a basic fuel injection quantity based on said measured intake air quantity and said engine revolution number and to output an instruction signal to inject an amount of fuel to a cylinder, which comprises a pressure detecting means to detect an inner pressure of cylinder, a crank angle detecting means to detect a crank angle of the engine, an exhaust gas temperature detecting means to detect a temperature of exhaust gas and a control device which is adapted to receive the output signals of said pressure detecting means, said crank angle detecting means and said exhaust gas temperature detecting means, to calculate a state quantity based on the signals of said inner pressure of cylinder in an ignition cycle, and to control a fuel injection quantity by using said state quantity and a value of exhaust gas temperature T e obtained by the output of said exhaust gas temperature detecting means.

Claim 8

The air-fuel ratio control apparatus according to claim 5, wherein the maximum value P max of an inner pressure of cylinder in an ignition cycle, a graphically represented effective average pressure P i or a calorific value Q is calculated to obtain a mean value T eb in a predetermined period, and said feed-back control of air-fuel ratio is effected on the basis of said state quantity, said exhaust gas temperature T e and said mean value T eb in predetermined period.

Claim 9

The air-fuel ratio control apparatus according to claim 6, wherein said predetermined period used for obtaining the mean value of the maximum inner pressure of cylinder P maxb is a predetermined number of cycles or a predetermined time, and said predetermined period for said graphically represented effective average pressure P i or said calorific value Q is a predetermined number of cycles.

Claim 10

The air-fuel ratio control apparatus according to claim 7, wherein said predetermined number of cycles or said predetermined time is changed depending on an operating point of the engine.