Operating apparatus for lean burn internal combustion engine

Claim 2

An engine operating apparatus for an internal combustion engine supplied with a lean air-fuel mixture, said apparatus comprising: a first lean sensor means in contact with exhaust gas from the engine for directly detecting an actual air-fuel ratio of the engine so as to obtain continuously varying signals indicating the detected air-fuel ratio; a second sensor means for detecting at least one engine operating parameter, so as to obtain signals indicating the detected engine operating parameters; a first calculating means for calculating the air-fuel ratio by using the signals from the operating parameter detecting means; a second calculating means for calculating a basic ignition timing using signals from the operating parameter detecting means; a third calculating means for calculating a difference between the air-fuel ratio calculated by the first calculating means and the air-fuel ratio actually and directly detected by the air-fuel ratio detecting means; a fourth calculating means for calculating a correction value of ignition timing corresponding to the difference; and a means for generating ignition of the engine at an ignition timing which is the sum of the basic ignition timing and the correction value.

Claim 3

An apparatus according to claim 1, wherein said third calculating means comprises: a means for storing data of ignition timing with respect to various air-fuel ratios and a means for calculating, at the detected operating conditions of the engine, a difference of the air-fuel ratio as calculated by the first calculating means from the air-fuel ratio as detected by the second sensor means.

Claim 4

An apparatus according to claim 2, wherein said storing means comprising a means for storing a single relationship between the air-fuel ratio and the ignition timing which is common to all engine operating conditions.

Claim 5

An apparatus according to claim 1, wherein said first sensor means comprises a so-called lean sensor for detecting an air-fuel ratio larger than a theoretical air-fuel ratio.

Claim 6

An apparatus according to claim 1, wherein said second sensor means comprises a first sensor for detection of an engine rotational speed and a second sensor for detection of an intake air pressure.

Claim 7

In an operating apparatus of an internal combustion engine supplied with a lean air-fuel mixture, said engine being provided with means for controlling the amount of fuel supplied to the engine in response to a present air-fuel ratio determined at each operating condition of the engine, the improvement wherein said engine is not provided with means responsive to said present air-fuel ratio for effecting a feedback control of the amount of fuel to be supplied to the engine, and wherein said engine is provided with a system for controlling the ignition timing, said ignition timing control system comprising: a first lean sensor means for directly detecting an actual air-fuel ratio of the engine so as to obtain continuously varying signals indicating the present air-fuel ratio; a second sensor means for detecting at least one engine operating parameter so as to obtain signals indicating the detected engine operating parameters; a first calculating means for calculating the theoretical air-fuel ratio by using the signals from the operating parameter detecting means; a second calculating means for calculating a basic ignition timing using signals from the operating parameter detecting means; a third calculating means for calculating a difference between the theoretical air-fuel ratio calculated by the first calculating means and the present air-fuel ratio actually and directly detected by the air-fuel ratio detecting means; a fourth calculating means for calculating a correction value of ignition timing corresponding to the difference; and a means for generating ignition of the engine at an ignition timing which is the sum of the basic ignition timing and the correction value.

Claim 8

In an operating apparatus of an internal combustion engine supplied with a lean air-fuel mixture, said engine being provided with means for controlling the amount of fuel supplied to the engine in response to a present air-fuel ratio determined at each operating condition of the engine, the improvement wherein said engine is not provided with means responsive to said present air-fuel ratio for effecting a feedback control of the amount of fuel to be supplied to the engine, and wherein said engine is provided with a system for controlling the ignition timing, said ignition timing control system comprising: a first lean sensor means for directly detecting an actual air-fuel ratio of the engine so as to obtain continuously varying signals indicating the present air-fuel ratio; a second sensor means for detecting at least one engine operating parameter so as to obtain signals indicating the detected engine operating parameters; a first calculating means for calculating the theoretical air-fuel ratio by using the signals from the operating parameter detecting means; a second calculating means for calculating a basic ignition timing using signals from the operating parameter detecting means; a third calculating means for calculating a difference between the theoretical air-fuel ratio calculated by the first calculating means and the present air-fuel ratio actually and directly detected by the air-fuel ratio detecting means; a fourth calculating means for calculating a correction value of ignition timing corresponding to the difference; and a means for generating ignition of the engine at an ignition timing which is the sum of the basic ignition timing and the correction value.