Method of detecting abnormality in an internal combustion engine

Claim 1

A method of detecting abnormality in an internal combustion engine having a catalyst system, an evaporative fuel-purging system, a fuel supply system, an air-fuel ratio sensor, an ignition system, and a fuel tank, the method being applied to at least one of said catalyst system, said air-fuel ratio sensor, and said ignition system, for performing detection of abnormality therein according to operating parameters of said engine, the method comprising the steps of: (1) detecting an amount of residual fuel in said fuel tank; (2) comparing said amount of residual fuel with a predetermined value; and (3) inhibiting said abnormality detection when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 2

A method of detecting abnormality in an internal combustion engine having a catalyst system, an evaporative fuel-purging system, a fuel supply system, an air-fuel ratio sensor, an ignition system, and a fuel tank, the method being applied to at least one of said catalyst system, said air-fuel ratio sensor, and said ignition system, for performing detection of abnormality therein according to operating parameters of said engine, the method comprising the steps of: (1) detecting an amount of residual fuel in said fuel tank; (2) comparing said amount of residual fuel with a predetermined value; and (3) inhibiting said abnormality detection when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 3

A method of detecting deterioration of a three-way catalyst of an internal combustion engine having an exhaust passage, said three-way catalyst being arranged in said exhaust passage, a first air-fuel ratio sensor arranged in said exhaust passage at a location upstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, a second air-fuel ratio sensor arranged in said exhaust passage at a location downstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, and a fuel tank, the method comprising the steps of: (1) obtaining a first signal and a second signal based on respective signals output from said first and second air-fuel ratio sensors at least one of when the fuel supply to said engine is increased and when the fuel supply to said engine is interrupted; (2) comparing a waveform of a signal outputted from said first air-fuel ratio sensor with a waveform of a signal output from said second air-fuel ratio sensor, based on said first and second signals while said engine is in a predetermined stable operating condition; (3) determining from a result of said comparison whether or not said three-way catalyst is deteriorated; (4) detecting an amount of residual fuel in said fuel tank; (5) comparing said amount of residual fuel with a predetermined value; and (6) inhibiting execution of said steps (1)-(3) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 4

A method of detecting deterioration of a three-way catalyst of an internal combustion engine having an exhaust passage, said three-way catalyst being arranged in said exhaust passage, a first air-fuel ratio sensor arranged in said exhaust passage at a location upstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, a second air-fuel ratio sensor arranged in said exhaust passage at a location downstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, and a fuel tank, the method comprising the steps of: (1) obtaining a first signal and a second signal based on respective signals output from said first and second air-fuel ratio sensors at least one of when the fuel supply to said engine is increased and when the fuel supply to said engine is interrupted; (2) comparing a waveform of a signal outputted from said first air-fuel ratio sensor with a waveform of a signal output from said second air-fuel ratio sensor, based on said first and second signals while said engine is in a predetermined stable operating condition; (3) determining from a result of said comparison whether or not said three-way catalyst is deteriorated; (4) detecting an amount of residual fuel in said fuel tank; (5) comparing said amount of residual fuel with a predetermined value; and (6) inhibiting execution of said steps (1)-(3) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 5

A method of detecting deterioration of a three-way catalyst of an internal combustion engine having an exhaust passage, said three-way catalyst being arranged in said exhaust passage, a first air-fuel ratio sensor arranged in said exhaust passage at a location upstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, a second air-fuel ratio sensor arranged in said exhaust passage at a location downstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, and a fuel tank, the method comprising the steps of; (1) obtaining a first signal and a second signal based on respective signals output from said first and second air-fuel ratio sensors when the fuel supply to said engine is increased; (2) obtaining a third signal and a fourth signal based on respective signals output from said first and second air-fuel ratio sensors when the fuel supply to said engine is interrupted; (3) comparing a waveform of a signal output from said first air-fuel ratio sensor with a waveform of a signal output from said second air-fuel ratio sensor, based on said first to fourth signals while said engine is in a predetermined stable operating condition; (4) determining from a result of said comparison whether or not said three-way catalyst is deteriorated. (5) detecting an amount of residual fuel in said fuel tank; (6) comparing said amount of residual fuel with a predetermined value; and (7) inhibiting execution of said steps (1)-(4) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 6

A method of detecting deterioration of a three-way catalyst of an internal combustion engine having an exhaust passage, said three-way catalyst being arranged in said exhaust passage, a first air-fuel ratio sensor arranged in said exhaust passage at a location upstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, a second air-fuel ratio sensor arranged in said exhaust passage at a location downstream of said three-way catalyst for detecting the air-fuel ratio of exhaust gases in said exhaust passage, and a fuel tank, the method comprising the steps of; (1) obtaining a first signal and a second signal based on respective signals output from said first and second air-fuel ratio sensors when the fuel supply to said engine is increased; (2) obtaining a third signal and a fourth signal based on respective signals output from said first and second air-fuel ratio sensors when the fuel supply to said engine is interrupted; (3) comparing a waveform of a signal output from said first air-fuel ratio sensor with a waveform of a signal output from said second air-fuel ratio sensor, based on said first to fourth signals while said engine is in a predetermined stable operating condition; (4) determining from a result of said comparison whether or not said three-way catalyst is deteriorated. (5) detecting an amount of residual fuel in said fuel tank; (6) comparing said amount of residual fuel with a predetermined value; and (7) inhibiting execution of said steps (1)-(4) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 7

A method of detecting abnormality in combustion in an internal combustion engine having a crankshaft, and a fuel tank, the method detecting said abnormality based on a change in rotation of said engine, the method comprising the steps of: (1) generating pulses according to rotation of said crankshaft at predetermined angles of said crankshaft; (2) detecting from said pulses angular acceleration of said crankshaft whenever each of said pulses is generated; (3) calculating an average value of the angular acceleration thus detected; (4) determining whether or not abnormality has occurred in combustion of said engine, from a difference between the detected angular acceleration and the calculated average value of the angular acceleration (5) detecting an amount of residual fuel in said fuel tank; (6) comparing said amount of residual fuel with a predetermined value; and (7) inhibiting execution of said steps (1)-(4) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 8

A method of detecting abnormality in combustion in an internal combustion engine having a crankshaft, and a fuel tank, the method detecting said abnormality based on a change in rotation of said engine, the method comprising the steps of: (1) generating pulses according to rotation of said crankshaft at predetermined angles of said crankshaft; (2) detecting from said pulses angular acceleration of said crankshaft whenever each of said pulses is generated; (3) calculating an average value of the angular acceleration thus detected; (4) determining whether or not abnormality has occurred in combustion of said engine, from a difference between the detected angular acceleration and the calculated average value of the angular acceleration (5) detecting an amount of residual fuel in said fuel tank; (6) comparing said amount of residual fuel with a predetermined value; and (7) inhibiting execution of said steps (1)-(4) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 9

A method of detecting abnormality in combustion in an internal combustion engine having a crankshaft, and abnormality based on a change in rotation of said engine, the method comprising the steps of: (1) generating pulses according to rotation of said crankshaft whenever said crankshaft rotates through a first predetermined angle; (2) adding time intervals between said pulses whenever said crankshaft rotates through a second predetermined angle which is greater than said first predetermined angle, to obtain a time; (3) calculating a rotation fluctuation percentage from said time obtained last time and said time obtained at present time; (4) comparing the calculated rotation fluctuation percentage with a predetermined limit value; (5) determining from a result of said comparison whether or not abnormality has occurred in combustion of said engine; (6) detecting an amount of residual fuel in said fuel tank; (7) comparing said amount of residual fuel with a predetermined value; and (8) inhibiting execution of said steps (1)-(5) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 10

A method of detecting abnormality in combustion in an internal combustion engine having a crankshaft, and abnormality based on a change in rotation of said engine, the method comprising the steps of: (1) generating pulses according to rotation of said crankshaft whenever said crankshaft rotates through a first predetermined angle; (2) adding time intervals between said pulses whenever said crankshaft rotates through a second predetermined angle which is greater than said first predetermined angle, to obtain a time; (3) calculating a rotation fluctuation percentage from said time obtained last time and said time obtained at present time; (4) comparing the calculated rotation fluctuation percentage with a predetermined limit value; (5) determining from a result of said comparison whether or not abnormality has occurred in combustion of said engine; (6) detecting an amount of residual fuel in said fuel tank; (7) comparing said amount of residual fuel with a predetermined value; and (8) inhibiting execution of said steps (1)-(5) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 11

A method of detecting deterioration of an exhaust gas component concentration sensor for an internal combustion engine having a fuel tank, said exhaust gas component concentration sensor detecting concentration of a component of exhaust gases emitted from said engine, said engine having control means responsive to an output from said exhaust gas component concentration sensor for controlling an amount of fuel supplied to said engine, the method comprising the steps of: (1) integrating a difference between said output from said exhaust gas component concentration sensor and a predetermined reference value which is outside a range of said output which can be assumed during normal operation of said exhaust gas concentration sensor; (2) comparing a thus obtained integral value with a predetermined deterioration-determining value; (3) determining from a result of said comparison whether or not said exhaust gas component concentration sensor is deteriorated; (4) detecting an amount of residual fuel in said fuel tank; (5) comparing said amount of residual fuel with a predetermined value; and (6) inhibiting execution of said steps (1)-(3) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 12

A method of detecting deterioration of an exhaust gas component concentration sensor for an internal combustion engine having a fuel tank, said exhaust gas component concentration sensor detecting concentration of a component of exhaust gases emitted from said engine, said engine having control means responsive to an output from said exhaust gas component concentration sensor for controlling an amount of fuel supplied to said engine, the method comprising the steps of: (1) integrating a difference between said output from said exhaust gas component concentration sensor and a predetermined reference value which is outside a range of said output which can be assumed during normal operation of said exhaust gas concentration sensor; (2) comparing a thus obtained integral value with a predetermined deterioration-determining value; (3) determining from a result of said comparison whether or not said exhaust gas component concentration sensor is deteriorated; (4) detecting an amount of residual fuel in said fuel tank; (5) comparing said amount of residual fuel with a predetermined value; and (6) inhibiting execution of said steps (1)-(3) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 13

A method of detecting abnormality in a fuel supply system for supplying fuel to an internal combustion engine having at least one exhaust pipe, and an exhaust gas component concentration sensor arranged in each of said at least one exhaust pipe for detecting concentration of a component of exhaust gases emitted from said engine, wherein an amount of fuel supplied to said engine is controlled in a feedback manner based on an air-fuel ratio correction coefficient set in response to an output signal from said exhaust gas component concentration sensor, the method comprising the steps of: (1) calculating an abnormality determination value based on said air-fuel ratio correction coefficient; (2) calculating a learned average value of said air-fuel ratio correction coefficient; (3) renewing said abnormality determination value when said calculated learned average value of said air-fuel ratio correction coefficient falls outside a first predetermined range defined based upon said abnormality determination coefficient; (4) determining that said fuel supply system is abnormal when the renewed value of said abnormality determination value falls outside a second predetermined range defined by predetermined upper and lower limit values. (5) detecting an amount of residual fuel in said fuel tank; (6) comparing said amount of residual fuel with a predetermined value; and (7) inhibiting execution of said steps (1)-(4) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 14

A method of detecting abnormality in a fuel supply system for supplying fuel to an internal combustion engine having at least one exhaust pipe, and an exhaust gas component concentration sensor arranged in each of said at least one exhaust pipe for detecting concentration of a component of exhaust gases emitted from said engine, wherein an amount of fuel supplied to said engine is controlled in a feedback manner based on an air-fuel ratio correction coefficient set in response to an output signal from said exhaust gas component concentration sensor, the method comprising the steps of: (1) calculating an abnormality determination value based on said air-fuel ratio correction coefficient; (2) calculating a learned average value of said air-fuel ratio correction coefficient; (3) renewing said abnormality determination value when said calculated learned average value of said air-fuel ratio correction coefficient falls outside a first predetermined range defined based upon said abnormality determination coefficient; (4) determining that said fuel supply system is abnormal when the renewed value of said abnormality determination value falls outside a second predetermined range defined by predetermined upper and lower limit values. (5) detecting an amount of residual fuel in said fuel tank; (6) comparing said amount of residual fuel with a predetermined value; and (7) inhibiting execution of said steps (1)-(4) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 15

A method of detecting abnormality in an evaporative fuel-purging system for an internal combustion engine having a fuel tank, and an intake passage, said evaporative fuel-purging system having a canister for adsorbing evaporative fuel from said fuel tank, and a purging passage through which said evaporative fuel is purged from said canister into said intake passage, said engine having a sensor for detecting a parameter reflecting an amount of said evaporative fuel purged into said intake passage, the method comprising the steps of: (1) determining whether or not said engine is in a predetermined operating condition after completion of warming-up of said engine; (2) temporarily inhibiting said purging of said evaporative fuel into said intake passage when it is determined that said engine is in said predetermined operating condition; (3) obtaining a first value based on said parameter during said temporary inhibition of said purging of said evaporative fuel; (4) obtaining a second value based on said parameter during execution of said purging of said evaporative fuel carried out after said temporary inhibition of said purging of said evaporative fuel; (5) comparing said first value with said second value; (6) determining whether or not there is abnormality in said evaporative fuel-purging system, based on a result of said comparison. (7) detecting an amount of residual fuel in said fuel tank; (8) comparing said amount of residual fuel with a predetermined value; and (9) inhibiting execution of said steps (1)-(6) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.

Claim 16

A method of detecting abnormality in an evaporative fuel-purging system for an internal combustion engine having a fuel tank, and an intake passage, said evaporative fuel-purging system having a canister for adsorbing evaporative fuel from said fuel tank, and a purging passage through which said evaporative fuel is purged from said canister into said intake passage, said engine having a sensor for detecting a parameter reflecting an amount of said evaporative fuel purged into said intake passage, the method comprising the steps of: (1) determining whether or not said engine is in a predetermined operating condition after completion of warming-up of said engine; (2) temporarily inhibiting said purging of said evaporative fuel into said intake passage when it is determined that said engine is in said predetermined operating condition; (3) obtaining a first value based on said parameter during said temporary inhibition of said purging of said evaporative fuel; (4) obtaining a second value based on said parameter during execution of said purging of said evaporative fuel carried out after said temporary inhibition of said purging of said evaporative fuel; (5) comparing said first value with said second value; (6) determining whether or not there is abnormality in said evaporative fuel-purging system, based on a result of said comparison. (7) detecting an amount of residual fuel in said fuel tank; (8) comparing said amount of residual fuel with a predetermined value; and (9) inhibiting execution of said steps (1)-(6) when, as a result of said comparison, said amount of residual fuel is below said predetermined value.