US 11,598,258 B2Granted

Misfire determination apparatus and method for internal combustion engine

AssigneeToyota Jidosha Kabushiki Kaisha

InventorHitoki Sugimoto

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Abstract

A CPU determines that misfires are occurring in a cylinder subject to determination of whether misfires are occurring when a value obtained by subtracting a rotation fluctuation amount ΔT30[n−2] from a rotation fluctuation amount ΔT30[n] is greater than or equal to a determination threshold. The rotation fluctuation amount ΔT30[n] is subject to the misfire determination. The rotation fluctuation amount ΔT30[n−2] is 360° CA earlier than the rotation fluctuation amount ΔT30[n]. When stopping fuel supply to a cylinder #1 and determining whether misfires are occurring in cylinder #4, the CPU determines whether misfires are occurring after executing a correcting process that corrects the determination threshold to a second determination threshold Δth2, which is less than a first determination threshold Δth1.

Claims5

Dependent claims

A misfire determination apparatus for an internal combustion engine, the internal combustion engine being a multi-cylinder internal combustion engine having a catalyst that is provided in an exhaust system and purifies exhaust gas, the misfire determination apparatus being configured to execute:

a single-cylinder fuel cut-off process that executes a single-cylinder fuel cut-off control that stops fuel supply to a fuel cut-off cylinder and performs fuel supply to other remaining combustion cylinders;
an instantaneous speed calculating process that calculates an instantaneous speed variable, the instantaneous speed variable being an index value of a rotation speed of a crankshaft;
a rotation fluctuation amount calculating process that calculates a rotation fluctuation amount, the rotation fluctuation amount being an amount of change of the instantaneous speed variable;
a fluctuation amount difference value calculating process that calculates a fluctuation amount difference value obtained by subtracting, from a first rotation fluctuation amount, a second rotation fluctuation amount, the first rotation fluctuation amount being the rotation fluctuation amount of a determination cylinder, which is subject to misfire detection, and the second rotation fluctuation amount being the rotation fluctuation amount of a reference cylinder, the reference cylinder reaching an expansion stroke at a point in time that is earlier than an expansion stroke of the determination cylinder by 360° crank angle multiplied by an integer;
a misfire determining process that determines that a misfire has occurred in the determination cylinder when a misfire condition is satisfied based on a magnitude relationship between the fluctuation amount difference value and a determination threshold;
and
a correcting process that performs, if the reference cylinder is the fuel cut-off cylinder when the misfire determining process is executed, a correction for reducing an influence of a fact that the reference cylinder is the fuel cut-off cylinder on a result of a misfire determination, wherein
the instantaneous speed variable is time required by a crank angle to rotate a specified angle,
the misfire determining process determines that a misfire has occurred in the determination cylinder when the fluctuation amount difference value is greater than or equal to the determination threshold,
the determination threshold in a case in which the reference cylinder is the combustion cylinder is defined as a first determination threshold,
the correcting process corrects the determination threshold in a case in which the reference cylinder is the fuel cut-off cylinder to a second determination threshold, which is less than the first determination threshold, and
the determination threshold in the misfire determining process is increased as the rotation speed of the crankshaft decreases.

9 more elements

a single-cylinder fuel cut-off process that executes a single-cylinder fuel cut-off control that stops fuel supply to a fuel cut-off cylinder and performs fuel supply to other remaining combustion cylinders;
an instantaneous speed calculating process that calculates an instantaneous speed variable, the instantaneous speed variable being an index value of a rotation speed of a crankshaft;
a rotation fluctuation amount calculating process that calculates a rotation fluctuation amount, the rotation fluctuation amount being an amount of change of the instantaneous speed variable;
a fluctuation amount difference value calculating process that calculates a fluctuation amount difference value obtained by subtracting, from a first rotation fluctuation amount, a second rotation fluctuation amount, the first rotation fluctuation amount being the rotation fluctuation amount of a determination cylinder, which is subject to misfire detection, and the second rotation fluctuation amount being the rotation fluctuation amount of a reference cylinder, the reference cylinder reaching an expansion stroke at a point in time that is earlier than an expansion stroke of the determination cylinder by 360° crank angle multiplied by an integer;
a misfire determining process that determines that a misfire has occurred in the determination cylinder when a misfire condition is satisfied based on a magnitude relationship between the fluctuation amount difference value and a determination threshold;
and
a correcting process that performs, if the reference cylinder is the fuel cut-off cylinder when the misfire determining process is executed, a correction for reducing an influence of a fact that the reference cylinder is the fuel cut-off cylinder on a result of a misfire determination,
wherein the correcting process corrects the second rotation fluctuation amount in a case in which the reference cylinder is the fuel cut-off cylinder to a value equivalent to the second rotation fluctuation amount in a case in which the reference cylinder is the combustion cylinder.

5 more elements

a single-cylinder fuel cut-off process that executes a single-cylinder fuel cut-off control that stops fuel supply to a fuel cut-off cylinder and performs fuel supply to other remaining combustion cylinders;
an instantaneous speed calculating process that calculates an instantaneous speed variable, the instantaneous speed variable being an index value of a rotation speed of a crankshaft;
a rotation fluctuation amount calculating process that calculates a rotation fluctuation amount, the rotation fluctuation amount being an amount of change of the instantaneous speed variable;
a fluctuation amount difference value calculating process that calculates a fluctuation amount difference value obtained by subtracting, from a first rotation fluctuation amount, a second rotation fluctuation amount, the first rotation fluctuation amount being the rotation fluctuation amount of a determination cylinder, which is subject to misfire detection, and the second rotation fluctuation amount being the rotation fluctuation amount of a reference cylinder, the reference cylinder reaching an expansion stroke at a point in time that is earlier than an expansion stroke of the determination cylinder by 360° crank angle multiplied by an integer;
a misfire determining process that determines that a misfire has occurred in the determination cylinder when a misfire condition is satisfied based on a magnitude relationship between the fluctuation amount difference value and a determination threshold;
and
a correcting process that performs, if the reference cylinder is the fuel cut-off cylinder when the misfire determining process is executed, a correction for reducing an influence of a fact that the reference cylinder is the fuel cut-off cylinder on a result of a misfire determination,
wherein the misfire determining process does not perform the misfire determination when the determination cylinder is the fuel cut-off cylinder.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/475,292Filed 14 Sep 2021
Priority: JP JP2020-16065325 Sep 2020
Published: US 2022/0099528 A131 Mar 2022
Granted: 7 Mar 2023
Term ends: Not estimatedThe source records don’t support an estimate.

Classification17 codes

F02B 75/18
Engines characterised by number of cylinders, e.g. single-cylinder engines: multi-cylinder engines
F02D 41/1498
With detection of the mechanical response of the engine: measuring engine roughness
F02D 41/0087
Controlling each cylinder individually: selective cylinder activation, i.e. partial cylinder operation
F02D 41/009
Electrical control of supply of combustible mixture or its constituents: using means for generating position or synchronisation signals