Method and apparatus for detecting misfired cylinder of internal combustion engine

Claim 1

A method for detecting a misfired cylinder based on crank angular velocity of an internal combustion engine, comprising the steps of: detecting crank angular velocity of said engine; detecting a misfired cylinder based on said crank angle velocity; detecting a fully-closed state of a throttle valve disposed in an air suction system of said engine; and inhibiting detection of said misfired cylinder at least under a condition when said throttle valve disposed in said air suction system of said engine is detected to have said fully-closed state.

Claim 2

A method for detecting a misfired cylinder based on crank angular velocity of an internal combustion engine, comprising the steps of: detecting crank angular velocity of said engine; detecting a misfired cylinder based on said crank angle velocity; detecting a fully-closed state of a throttle valve disposed in an air suction system of said engine; and inhibiting detection of said misfired cylinder at least under a condition when said throttle valve disposed in said air suction system of said engine is detected to have said fully-closed state.

Claim 4

A method for inhibiting detection of a misfired cylinder of an internal combustion engine by calculating a misfire discriminating valve approximately corresponding to a change in mean effective pressure based on a revolution period of said engine and comparing said misfire discriminating valve with a predetermined slice level of said misfire discriminating valve, said method comprising the steps of: acquiring in advance a positive/negative inversion pattern of said misfire discriminating value at a time of occurrence of a misfire and inhibiting detection of said misfired cylinder when an actual misfire discriminating value does not change according to said positive/negative inversion pattern.

Claim 5

A method for inhibiting detection of a misfired cylinder of an internal combustion engine by calculating a misfire discriminating valve approximately corresponding to a change in mean effective pressure based on a revolution period of said engine and comparing said misfire discriminating valve with a predetermined slice level of said misfire discriminating valve, said method comprising the steps of: acquiring in advance a positive/negative inversion pattern of said misfire discriminating value at a time of occurrence of a misfire and inhibiting detection of said misfired cylinder when an actual misfire discriminating value does not change according to said positive/negative inversion pattern.

Claim 8

A method for detecting a misfired cylinder of an internal combustion engine having an even number of cylinders, comprising the steps of: computing a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on a revolution period of said engine while setting a slice level of said misfire discriminating value for detection of said misfired cylinder according to said misfire discriminating value; and detecting a cylinder corresponding to a misfire discriminating value of one engine turn before from a first inversion of said misfire discriminating value from negative to positive, when misfire discriminating values corresponding to half of said cylinders in a consecutive ignition order are negative, misfire discriminating values corresponding to a remaining second half of said cylinders are positive, at least one of said misfire discriminating values which are negative equal to or less than a negative slice level of said misfire discriminating value, and at least one of said misfire discriminating values which are positive exceeds a positive slice level of said misfire discriminating value.

Claim 9

A method for detecting a misfired cylinder of an internal combustion engine having an even number of cylinders, comprising the steps of: computing a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on a revolution period of said engine while setting a slice level of said misfire discriminating value for detection of said misfired cylinder according to said misfire discriminating value; and detecting a cylinder corresponding to a misfire discriminating value of one engine turn before from a first inversion of said misfire discriminating value from negative to positive, when misfire discriminating values corresponding to half of said cylinders in a consecutive ignition order are negative, misfire discriminating values corresponding to a remaining second half of said cylinders are positive, at least one of said misfire discriminating values which are negative equal to or less than a negative slice level of said misfire discriminating value, and at least one of said misfire discriminating values which are positive exceeds a positive slice level of said misfire discriminating value.

Claim 10

A method for detecting a misfired cylinder of an internal combustion engine, comprising the steps of: calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on a period within a predetermined crank angle range of said engine; detecting a maximum amplitude of said misfire discriminating value while compensating said misfire discriminating value in a direction to reduce a level difference between misfire discriminating value originating from an engine operational condition based on operational conditions of said engine including at least revolution speed of said engine and engine load of said engine; setting a slice level of said misfire discriminating value within said maximum amplitude when an amplitude of a compensated misfire discriminating value is equal to or greater than a predetermined value, and setting said slice level outside said maximum amplitude when said amplitude of said compensated misfire discriminating value is lless than said predetermined value; and comparing said slice level as set with said misfire discriminating value to thereby detect said misfired cylinder.

Claim 11

A method for detecting a misfired cylinder of an internal combustion engine, comprising the steps of: calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on a period within a predetermined crank angle range of said engine; detecting a maximum amplitude of said misfire discriminating value while compensating said misfire discriminating value in a direction to reduce a level difference between misfire discriminating value originating from an engine operational condition based on operational conditions of said engine including at least revolution speed of said engine and engine load of said engine; setting a slice level of said misfire discriminating value within said maximum amplitude when an amplitude of a compensated misfire discriminating value is equal to or greater than a predetermined value, and setting said slice level outside said maximum amplitude when said amplitude of said compensated misfire discriminating value is lless than said predetermined value; and comparing said slice level as set with said misfire discriminating value to thereby detect said misfired cylinder.

Claim 14

An apparatus for detecting a misfired cylinder of an internal combustion engine, comprising: angular velocity detecting means for detecting a crank angular velocity of said engine; misfired cylinder detecting means for detecting said misfired cylinder based on said crank angular velocity; fully-closed state detecting means for detecting a fully-closed state of a throttle valve disposed in an air suction system of said engine; and misfire detection inhibiting means for inhibiting said misfired cylinder detecting means from detecting said misfired cylinder at least under a condition when said fully-closed state of said throttle value has been detected.

Claim 15

An apparatus for detecting a misfired cylinder of an internal combustion engine, comprising: angular velocity detecting means for detecting a crank angular velocity of said engine; misfired cylinder detecting means for detecting said misfired cylinder based on said crank angular velocity; fully-closed state detecting means for detecting a fully-closed state of a throttle valve disposed in an air suction system of said engine; and misfire detection inhibiting means for inhibiting said misfired cylinder detecting means from detecting said misfired cylinder at least under a condition when said fully-closed state of said throttle value has been detected.

Claim 17

An apparatus for inhibiting detection of a misfired cylinder of an internal combustion engine, comprising: period measuring means for measuring a revolution period of said engine; misfire discriminating value calculating means for calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on said revolution period; misfired cylinder detecting means for detecting a misfired cylinder by comparing said calculated misfire discriminating value with a predetermined slice level of said misfire discriminating value; and misfire detection inhibiting means for inhibiting said misfired cylinder detecting means from detecting said misfired cylinder when an actual misfire discriminating value does not change along a preacquired positive/negative inversion pattern of said misfire discriminating value at a time of occurrence of a misfire.

Claim 18

An apparatus for inhibiting detection of a misfired cylinder of an internal combustion engine, comprising: period measuring means for measuring a revolution period of said engine; misfire discriminating value calculating means for calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on said revolution period; misfired cylinder detecting means for detecting a misfired cylinder by comparing said calculated misfire discriminating value with a predetermined slice level of said misfire discriminating value; and misfire detection inhibiting means for inhibiting said misfired cylinder detecting means from detecting said misfired cylinder when an actual misfire discriminating value does not change along a preacquired positive/negative inversion pattern of said misfire discriminating value at a time of occurrence of a misfire.

Claim 21

An apparatus for detecting a misfired cylinder of an internal combustion engine comprising: period measuring means for measuring a revolution period of said internal combustion engine having an even number of cylinders; misfire discriminating value calculating means for calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on said revolution period; operational condition detecting means for detecting an engine operational condition; slice level setting means for setting a slice level of said misfire discriminating value for detection of a misfired cylinder by said misfire discriminating value based on said engine operational condition; and misfired cylinder detecting means for detecting a cylinder corresponding to a misfire discriminating value of one engine turn before from a first inversion of a misfire discriminating values from negative to positive, when misfire discriminating values corresponding to half of said cylinders in a consecutive ignition order are negative, misfire discriminating values corresponding to a remaining second half of said cylinders are positive, at least one of said consecutive negative misfire discriminating values is equal to or less than a negative value of said slice level, and at least one of said consecutive positive misfire discriminating values exceeds a postive value of said slice level.

Claim 22

An apparatus for detecting a misfired cylinder of an internal combustion engine comprising: period measuring means for measuring a revolution period of said internal combustion engine having an even number of cylinders; misfire discriminating value calculating means for calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on said revolution period; operational condition detecting means for detecting an engine operational condition; slice level setting means for setting a slice level of said misfire discriminating value for detection of a misfired cylinder by said misfire discriminating value based on said engine operational condition; and misfired cylinder detecting means for detecting a cylinder corresponding to a misfire discriminating value of one engine turn before from a first inversion of a misfire discriminating values from negative to positive, when misfire discriminating values corresponding to half of said cylinders in a consecutive ignition order are negative, misfire discriminating values corresponding to a remaining second half of said cylinders are positive, at least one of said consecutive negative misfire discriminating values is equal to or less than a negative value of said slice level, and at least one of said consecutive positive misfire discriminating values exceeds a postive value of said slice level.

Claim 23

An apparatus for detecting a misfired cylinder of an internal combustion engine, comprising: period measuring means for measuring a period within a predetermined crank angle range of said engine; misfire discriminating value calculating means for calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on said measured period; maximum amplitude detecting means for detecting a maximum amplitude of said misfire discriminating value; operational condition detecting means for detecting operational conditions of said engine including at least revolution speed of said engine and an engine load of said engine; discriminating value compensating means for compensating said misfire discriminating value in a direction to reduce a level difference between misfire discriminating values originating from an engine operational condition based on said detected operational conditions of said engine; slice level setting means for setting a slice level of said misfire discriminating value within said maximum amplitude detected by said maximum amplitude detecting means when an amplitude of said compensated detecting means when an amplitude of said compensated misfire discriminating value is equal to or greater than a predetermined value, and setting said slice level outside said maximum amplitude when said amplitude of said compensated misfire discriminating value is less than said predetermined value; and misfired cylinder detecting means for comparing said set slice level with said misfire discriminating value calculated by said misfire discriminating value calculating means to thereby detect a misfired cylinder.

Claim 24

An apparatus for detecting a misfired cylinder of an internal combustion engine, comprising: period measuring means for measuring a period within a predetermined crank angle range of said engine; misfire discriminating value calculating means for calculating a misfire discriminating value approximately corresponding to an amount of a change in mean effective pressure based on said measured period; maximum amplitude detecting means for detecting a maximum amplitude of said misfire discriminating value; operational condition detecting means for detecting operational conditions of said engine including at least revolution speed of said engine and an engine load of said engine; discriminating value compensating means for compensating said misfire discriminating value in a direction to reduce a level difference between misfire discriminating values originating from an engine operational condition based on said detected operational conditions of said engine; slice level setting means for setting a slice level of said misfire discriminating value within said maximum amplitude detected by said maximum amplitude detecting means when an amplitude of said compensated detecting means when an amplitude of said compensated misfire discriminating value is equal to or greater than a predetermined value, and setting said slice level outside said maximum amplitude when said amplitude of said compensated misfire discriminating value is less than said predetermined value; and misfired cylinder detecting means for comparing said set slice level with said misfire discriminating value calculated by said misfire discriminating value calculating means to thereby detect a misfired cylinder.