KR102534251B1 - CDA operation mode misfire diagnostic methods and devices, CDA engine vehicles with misfire diagnostic devices - Google Patents

Abstract

Disclosed is a method and apparatus for diagnosing misfire for each CDA operation mode of a CDA (Cylinder Deactivation) engine using segment time required for rotation of a crankshaft at a certain angle. A misfire diagnosis method for each CDA driving mode according to the present invention includes the steps of determining whether a vehicle state satisfies a condition for learning segment time for each CDA driving mode to be recorded as a learning value, and satisfying the segment time learning condition. Step of measuring the segment time for each CDA driving mode and storing the measured value for each CDA driving mode as a learning value, determining whether the vehicle condition satisfies the conditions for diagnosing misfire, and meeting the condition for diagnosing misfire , determining whether CDA operation has been entered, measuring segment time in the current CDA operation mode upon entering CDA operation, correcting the segment time value by reflecting the learning value for each CDA operation mode, and correcting the segment time value It is a gist to include a step of diagnosing misfire by comparing the value with a misfire diagnosis threshold set for each CDA driving mode.

Description

CDA operation mode misfire diagnostic methods and devices, CDA engine vehicles with misfire diagnostic devices}

The present invention relates to a method and apparatus for diagnosing an engine misfire, and more particularly, to a CDA operation mode (cylinder deactivation) engine using a segment time required for a crankshaft to rotate at a certain angle. For example, in an 8-cylinder CDA engine, a misfire diagnosis method and apparatus for each CDA operation mode for diagnosing or detecting a misfire for each 8-cylinder (electric cylinder) driving mode, 6-cylinder driving mode, and 4-cylinder driving mode, and misfire diagnosis for each CDA driving mode It relates to a CDA engine vehicle comprising the device.

A CDA (Cylinder-Deactivation) engine, that is, a deactivation cylinder engine, has been developed due to the recent trend of favoring high-fuel-efficiency vehicles and environmental issues due to excessive emission of exhaust gas. A CDA engine refers to an engine that can generate power with only the rest of the cylinders excluding the idle cylinders by stopping some of the cylinders according to the driving situation during braking or driving.

In such a CDA engine, fuel supply is cut off to the idle cylinder during CDA operation, and power loss due to friction is greatly reduced because the idle cylinder does not participate in power transmission. Therefore, there is a considerable level of fuel economy gain effect. Furthermore, as the deactivation cylinder is selectively controlled according to the required torque through continuous control of the deactivation cylinder of the engine, there is an advantage in terms of engine efficiency.

On the other hand, a phenomenon in which fuel injected from an engine using fossil fuel is discharged to the outside without burning is called a misfire. When an engine misfire occurs, unburned fuel is discharged as it is, which adversely affects air pollution, and the unburned fuel burns in the catalyst (catalyst configured in the after-treatment device for reducing exhaust gas pollutants) and damages the catalyst. can make it

Accordingly, in the case of automobiles, air pollution or catalyst damage is prevented by diagnosing misfire by mounting a misfire detection logic in the ECU. One of several methods for detecting a misfire is an engine roughness method. This is a method of diagnosing or detecting a misfiring by extracting segment time (the time required for the crankshaft to rotate at a certain angle) with a crank angle sensor.

The engine roughness method using the variability of the engine speed satisfies the misfire detection area condition stipulated by CARB (California Air Quality Management Agency), and in terms of accuracy of misfire detection, another known method (ion current generated in the spark plug circuit) It has the advantage of being higher than the method of detecting misfire by measuring the current) and the method of detecting misfire by directly measuring the combustion pressure of the cylinder.

For this reason, the engine roughness method is generally adopted for detecting a misfire of the engine, and CDA engine vehicles also generally adopt the misfire detection logic of the engine roughness method. Due to its characteristics, CDA engines have different combustion characteristics for each idle cylinder mode. Therefore, since the criteria for misfire detection are also different, it is advantageous to apply different criteria for each driving mode.

Nevertheless, conventionally, misfire is detected by uniformly applying a preset misfire detection criterion according to an electric cylinder driving mode without applying a different misfire detection criterion for each CDA driving mode. Accordingly, there is a problem in that accuracy of misfire detection in the CDA operation mode is lowered, and excessive emission of harmful exhaust gases and serious catalyst damage are caused due to unnecessary cancellation of the CDA operation mode due to false detection and non-detection.

Japanese Laid-open Patent No. 2018-197503 (published on December 13, 2018)

The technical problem to be solved by the present invention is to increase CDA operation time by reducing false fire detection in CDA (Cylinder Deactivation, idle cylinder) operation, and diagnose misfire for each CDA operation mode that can reduce harmful exhaust gas emissions through accurate misfire detection. It is intended to provide a CDA engine vehicle including a method and apparatus, and a misfire diagnosis device for each CDA driving mode.

According to one aspect of the present invention as a means of solving the problem,

As a method of diagnosing misfiring for each CDA operation mode of a CDA (Cylinder Deactivation) engine using segment time required for a crankshaft to rotate at a certain angle,

a) determining whether the vehicle state satisfies a condition for learning segment time for each CDA driving mode to be recorded as a learning value;

b) measuring the segment time for each CDA driving mode when the segment time learning condition is met and storing the measured value as a learning value for each CDA driving mode;

c) determining whether the condition of the vehicle satisfies conditions capable of diagnosing a misfire;

d) if misfire diagnosis conditions are met, determining whether CDA operation has been entered;

e) measuring segment time in the current CDA driving mode upon entering CDA driving;

f) correcting the segment time value measured in step e) by reflecting the learning value for each CDA driving mode; and

g) diagnosing misfire by comparing the corrected segment time value with a misfire diagnosis threshold set for each CDA driving mode;

Preferably, in the step a), it is possible to determine whether the segment time learning condition is satisfied based on whether or not the vehicle is driving on a rough road, whether the active cylinder is normally burning, and whether or not noise is generated in the output of the crank angle sensor.

In the step b), the segment time measurement value for each CDA driving mode may be stored as a learning value for each CDA driving mode together with engine speed (rpm) and load information at the time of measurement.

In addition, in the step c), whether it is a driving region in which positive torque is generated, whether the load variation of the engine is less than a certain level, whether the engine speed change rate is less than a certain level, whether driving on a rough road, and whether the fuel injector is broken It is possible to determine whether the misfire diagnosis conditions are satisfied by using some or all of the information.

In addition, in the step g), the current CDA driving mode and the segment segment in the step e) in the map data in which the misfiring diagnosis threshold is stored for each CDA driving mode for two factors, the engine speed (rpm) and the load. The misfire diagnosis threshold corresponding to the engine speed (rpm) and load conditions at the time of time measurement is read, and the misfire diagnosis threshold value read is compared with the corrected segment time value to detect a misfire. can be diagnosed.

Here, if the corrected segment time value exceeds the read misfire diagnosis threshold, it can be diagnosed that a misfire has occurred in the active cylinder during CDA operation.

The misfire diagnosis method for each CDA driving mode according to an aspect of the present invention also includes,

h) if misfire is diagnosed during the CDA operation in step g), forcibly terminating the CDA operation; may further include.

According to another aspect of the present invention as a means of solving the problem,

A crank angle sensor disposed around a target wheel of a crankshaft;

A controller for diagnosing misfiring for each CDA operation mode of the CDA engine using the segment time derived from the output of the crank angle sensor and performing predetermined control according to the diagnosis result;

The controller,

A learning storage unit that measures the segment time for each CDA driving mode and stores the measured value for each CDA driving mode as a learning value when the vehicle condition meets the condition for learning the segment time for each CDA driving mode. and,

A segment time correction unit that measures the segment time in the current CDA driving mode and corrects it by reflecting the learning value for each CDA driving mode to the measured value when the vehicle condition satisfies the conditions for diagnosing a misfire and enters CDA driving. ,

Provided is a misfire diagnosis device for each CDA driving mode comprising a misfire diagnosis unit that diagnoses misfire by comparing the corrected segment time value with a misfire diagnosis threshold read from a data storage unit.

Here, the learning storage unit may store the segment time measurement value for each CDA driving mode as a learning value for each CDA driving mode together with engine speed (rpm) and load information at the time of measurement.

In addition, the misfire diagnosis unit reads the misfire diagnosis threshold corresponding to the current CDA driving mode and the engine speed (rpm) at the time of measuring the segment time for misfire diagnosis and the load condition from the data storage unit. misfiring may be diagnosed by comparing the read misfire diagnosis threshold with the corrected segment time value.

Preferably, when the corrected segment time value exceeds the read misfire diagnosis threshold, the misfire diagnosis unit may diagnose that a misfire has occurred in an active cylinder during CDA operation.

In addition, the controller may further include a CDA operation termination signal generator for generating and outputting a signal for forcibly ending the CDA operation when it is diagnosed that a misfire has occurred during the CDA operation by the misfire diagnosis unit.

According to another aspect of the present invention as a means of solving the problem,

Provided is a CDA engine vehicle including a misfiring diagnosis device for each CDA driving mode according to another aspect of the present invention.

According to an embodiment of the present invention, upon entering CDA driving, misfire diagnosis by applying a misfire diagnosis threshold for each CDA driving mode can be used to diagnose misfire, thereby increasing the accuracy of diagnosis. As a result, it is possible to increase CDA operation time by reducing false fire detection during CDA operation, and prevent or minimize excessive emission of harmful exhaust gases and damage to the catalyst due to non-detection of misfire.

1 is a schematic diagram of an engine misfire diagnosis apparatus according to an embodiment of the present invention.
2 is a control flow chart showing a misfire diagnosis process for each CDA driving mode;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

In describing the present invention, terms used in the following specification are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

In addition, the terms "include" or "having" in this specification are intended to designate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, but one or more other It should be understood that the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof is not precluded.

In addition, "... unit" described in the specification means a unit that processes at least one function or operation, which may be implemented as hardware, software, or a combination of hardware and software.

In the description with reference to the accompanying drawings, the same reference numerals will be assigned to the same components, and duplicate descriptions of the same components will be omitted. In addition, in the description of the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

Hereinafter, the meaning of the main terms used in describing the embodiments of the present invention will be briefly reviewed.

Among the terms used in describing the embodiments of the present invention, "segment time" refers to the time required for the engine crankshaft to rotate at a certain angle according to the piston action of the cylinder in the explosion stroke, the crankshaft It can be derived from a signal output by recognizing teeth formed at equal intervals on the main surface of a set of target wheels by a crank angle sensor.

In addition, "CDA (Cylinder Deactivation) operation" refers to an engine operating state in which some cylinders among all cylinders are selectively disabled according to driving conditions and output is generated with only some other cylinders.

In addition, the "inactive cylinder" means a cylinder whose fuel supply is cut off according to the CDA operation, and the "active cylinder" means the opposite of the "inactive cylinder", and fuel is supplied normally except for the inactive cylinder during CDA operation, so that combustion refers to the passage that takes place
In addition, "by CDA (Cylinder Deactivation) operation mode" is a classification of operation modes according to the number of cylinders in which fuel supply is cut off, that is, "active cylinders" in which fuel is normally supplied and combustion is performed except for the "inactive cylinders" described above. For example, in an 8-cylinder CDA engine, the 8-cylinder driving mode means an engine operating state in which all cylinders are active, and the 6-cylinder driving mode means that only 6 of the 8 cylinders are active. It means the engine operating state in the active cylinder state. The 4-cylinder driving mode means an engine operation state in which only 4 out of 8 cylinders are active cylinders.
The misfiring diagnosis device according to the present invention is applied to a CDA engine set so that some of all cylinders are at rest according to driving conditions and output is output only with other partial cylinders, and the segment in the corresponding driving mode according to the CDA driving mode. It is characterized by improving diagnosis accuracy by measuring the time and diagnosing misfire by comparing it with the misfire judgment standard set according to the driving mode.

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Referring to FIG. 1 , the configuration of a misfire diagnosis apparatus for each CDA driving mode according to an embodiment of the present invention will be described in detail.

1 is a schematic diagram of a misfire diagnosis apparatus for each CDA driving mode according to an embodiment of the present invention.

Referring to FIG. 1 , an apparatus for diagnosing a misfire for each CDA driving mode according to an embodiment of the present invention includes a crank angle sensor 10 and a controller 20 . The controller 20 may be an ECU, and the crank angle sensor 10 is disposed around the target wheel 40 on the engine crankshaft 30 to obtain a tooth signal necessary for calculating the engine speed according to the rotation of the target wheel 40 ( tooth time signal).

A plurality of teeth are formed on the outer circumferential surface of the target wheel 40 to measure the angular velocity of the crankshaft 30, and when the target wheel 40 rotates, the crank angle sensor 20 The controller 20 calculates the angular velocity of the engine crankshaft 30 using the tooth detection time information. Then, the engine speed is calculated from the calculated angular speed.

The controller 20 controls the engine speed by controlling the energized state of the fuel injector 60 and the ignition coil 50 according to the driver's request for acceleration or deceleration through an accelerator operation (not shown). In addition, a segment time (time required for the crankshaft to rotate at a certain angle) is derived from the tooth signal of the crank angle sensor 10, and a misfiring of the CDA engine is diagnosed using the derived segment time.

Misfire refers to a phenomenon in which fuel injected into an engine cylinder is discharged to the outside without burning. When a misfire occurs, the periodicity of the tooth signal is damaged as an energy source that accelerates the engine speed is not generated in the explosion (combustion expansion) stroke. More specifically, the segment time becomes longer compared to normal combustion.

Misfire occurs as fuel not burned in the explosion stroke -> combustion pressure not generated -> piston speed reduced -> crankshaft rotational momentum reduced, resulting in a decrease in engine speed. In other words, when a misfire occurs, the segment time is longer compared to normal combustion because the energy source to drive the engine is not generated. Therefore, by analyzing the segment time, it is possible to accurately diagnose whether or not there is a misfire.

An object of the present invention is to diagnose/detect a misfire occurring in a CDA engine by using the change characteristics of segment time that appear differently in case of a misfire. More specifically, upon entering the CDA driving mode, misfiring is diagnosed/detected by comparing the segment time measured in the corresponding driving mode with a misfiring criterion previously recorded in a data storage device such as a memory for each CDA driving mode.

To this end, the controller 20 applied to the present invention compares the segment time measured in the CDA driving mode with the misfire determination criterion for each CDA driving mode upon entering the CDA driving mode, and performs a series of processes to finally diagnose misfire based on the comparison result. It includes two or more processors that operate according to programs programmed to perform step by step.

Two or more processors included in the controller 20 may be largely composed of a learning storage unit 22, a segment time unit 24, a misfire diagnosis unit 26, and a CDA operation termination signal generator 28. .

The learning storage unit 22 measures the segment time for each CDA driving mode and stores the measured value for each CDA driving mode as a learning value when the vehicle state satisfies the condition for learning the segment time for each CDA driving mode. there is. More specifically, the segment time measurement value for each CDA driving mode may be stored as a learning value for each CDA driving mode together with engine speed (rpm) and load information at the time of measurement.

Preferably, in consideration of the deviation of the segment time according to engine combustion characteristics, the segment time is measured several times in the corresponding CDA operation mode during CDA operation in a state where the learning condition is established, and the average value of the measured segment time is calculated. It can be stored as the learning value of the corresponding CDA operation mode along with the average value of the engine speed and load at the time of measurement.

In determining whether the vehicle is in a vehicle state in which the segment time can be learned, information such as whether or not driving on a rough road, whether or not an active cylinder is normally operated, and whether noise is generated in an output of a crank angle sensor may be used. Preferably, it can be determined that the learning condition is satisfied when the active cylinder is in a normal combustion state and there is no output noise, when the vehicle is not driving on a rough road (because road impact may affect the segment time during driving on a rough road).

Whether or not driving on a rough road can be determined using the detection value of an acceleration sensor installed in the right place of the vehicle or the wheel acceleration value generated from the ABS sensor signal. can be identified through In addition, whether or not noise is generated can be known through comparison with normal signal values stored in dedicated map data.

The segment time correction unit 24 corrects the segment time for each CDA driving mode, which is a measured value for diagnosing a misfire, using the learning value (the average value of the segment time during normal combustion for each CDA driving mode). Preferably, when the vehicle condition satisfies the condition capable of diagnosing a misfire and the CDA driving is entered, the segment time is measured and the measured value is corrected by reflecting the learning value corresponding to the current CDA driving mode.

In a multi-cylinder engine, air enters through a single inlet and is supplied to each cylinder through a manifold line that is branched into multiple lines. this may be different. In other words, even under the same driving conditions, the segment time may vary slightly due to a difference in engine torque.

Therefore, if a misfire is diagnosed using the segment time measured in the CDA operation mode as it is without considering the deviation of the segment time due to the combustion characteristics of the multi-cylinder engine as described above, an erroneous detection (even though a misfire has not occurred) diagnosing as having occurred) or undetected (diagnosing as normal combustion even though a misfire has occurred) may occur.

In the present invention, in order to prevent or minimize the occurrence of such errors in advance, deviation correction is performed on the segment time measured in the misfire diagnosis mode by reflecting the above-described learning value, and the segment time value by reflecting the learning value for each CDA operation mode. In correcting , a correction method using a correction map generally used in the field of automobile control may be considered.
For example, a method of utilizing a correction map in which correction values for each difference between the learning value and the measured value corresponding to the segment time value are converted into data may be considered.

In determining whether the vehicle state is in a state in which a misfire can be diagnosed, whether it is a driving area in which positive torque is generated, whether the engine load variation is less than a certain level, and whether the engine speed change rate is less than a certain level Whether or not the misfire diagnosis conditions are met can be determined by using some or all of , rough road driving, and fuel injector failure.

Preferably, it is a driving region in which positive (+) torque is generated (an operating region in which the engine drives the wheels), the engine load variation amount and the engine speed change rate are less than the respective set values, and the driving is not on a rough road. , If the fuel injector is not out of order (a state in which fuel can be supplied normally), it may be determined that the vehicle condition satisfies a state condition capable of diagnosing a misfire.

The segment time value corrected through the segment time correction unit 24 is provided to the misfire diagnosis unit 26, and the misfire diagnosis unit 26 inputs the corrected segment time value from the segment time correction unit 24. The misfiring diagnosis threshold corresponding to the current CDA operation mode and the engine speed (rpm) at the time of segment time correction and the load condition are read from the data storage unit.

For example, if an 8-cylinder CDA engine is operated in the 6-cylinder CDA operation mode, the misfiring diagnosis threshold value corresponding to the engine speed (rpm) and load conditions at the time of 6-cylinder CDA operation mode and segment time correction ) is read from the data storage unit.

The misfire diagnosis unit 26 compares the read misfire diagnosis threshold with the corrected segment time value to diagnose misfire. Preferably, when the corrected segment time value exceeds the read misfire diagnosis threshold, it is possible to diagnose that a misfire has occurred in at least one active cylinder during CDA operation.

On the other hand, when the misfire diagnosis unit 26 diagnoses that a misfire has occurred during CDA operation through the above-described series of processing processes, the CDA operation end signal generating unit 28 causes exhaust gas to be generated due to a misfire caused by continuous CDA operation. It plays the role of generating and outputting a signal to forcibly terminate CDA operation to prevent problems such as excessive emission or serious catalyst damage from occurring.

Hereinafter, a series of misfire diagnosis processes for each CDA operation mode performed by the misfire diagnosis apparatus for each CDA operation mode according to an embodiment of the present invention will be described with reference to the control flow chart of FIG. 2 . For convenience of description, the components shown in FIG. 1 will be described with reference to corresponding reference numerals.

2 is a control flowchart for explaining a misfire diagnosis process for each CDA driving mode according to an embodiment of the present invention.

Referring to FIG. 2 , in the misfire diagnosis method for each CDA driving mode according to an embodiment of the present invention, determining whether a vehicle state satisfies a condition capable of learning a segment time for each CDA driving mode to be recorded as a learning value (S100). ) starting from In step S100 , it is possible to determine whether the segment time learning condition is satisfied based on whether the vehicle is driving on a rough road, whether the active cylinder is normally burning, and whether noise is generated in the output of the crank angle sensor.

In step S100, preferably, it is determined that the learning condition is established when the driving is not on a rough road (because road impact may affect the segment time during driving on a rough road), the active cylinder is in a normal combustion state, and there is no output noise. . Conversely, if even one of the learning conditions mentioned is not satisfied, the process is switched to the judgment start stage as the learning condition is not met.

Here, whether or not driving on a rough road can be determined using a detection value of an acceleration sensor installed in the right place of the vehicle or a wheel acceleration value generated from an ABS sensor signal, and whether or not the active cylinder is normally burning can be determined by a fuel injector and ignition switch failure signal of the active cylinder. It can be determined by whether or not it occurs. In addition, whether or not noise is generated can be known through comparison with normal signal values stored in dedicated map data.

As a result of the determination through step S100, if the current vehicle state satisfies the segment time learning condition, the step of measuring the segment time for each CDA driving mode and storing the measured value for each CDA driving mode as a learning value (S200) is continuously performed do. In step S200, the segment time measurement value for each CDA driving mode may be stored as a learning value for each CDA driving mode together with engine speed and load information at the time of measurement.

A series of learning in steps S100 to S200 may be performed each time the above-mentioned learning condition is satisfied, or may be performed when the above-mentioned learning condition is satisfied when the setting period arrives, and the previous learning under the same condition as the previous learning. If a new learning value different from the value is derived, the new learning value may be automatically updated as a learning value of the corresponding CDA driving mode and stored.

When a series of learning is completed through steps S100 to S200, it is determined whether the condition of the vehicle satisfies a condition capable of diagnosing a misfire (S300). In step S300, misfire is determined by using some or all of whether it is a driving area in which positive (+) torque is generated, whether the load variation of the engine and the engine speed shift rate are below a certain level, whether driving on a rough road, and whether a fuel injector is broken. It can be judged whether the diagnostic conditions are met.

Preferably, it is a driving region in which positive (+) torque is generated (an operating region in which the engine drives the wheels), the engine load variation amount and the engine speed change rate are less than the respective set values, and the driving is not on a rough road. , If the fuel injector is not out of order (a state in which fuel can be supplied normally), it may be determined that the vehicle condition satisfies a state condition capable of diagnosing a misfire.

As a result of the determination through step S300, if the current state of the vehicle satisfies the misfire diagnosis condition, it is determined whether or not CDA driving has been entered (S400). At this time, it can be known from the fuel supply signal applied to the fuel injector whether or not the CDA operation has been entered. This is because the fuel supply signal is not applied to the fuel injector of the cylinder selected as the stop target when the CDA operation is entered.

When entering the CDA operation is confirmed through step S400, the segment time is measured in the current CDA operation mode (S500). Then, the segment time value measured in step S500 is corrected (S600) by reflecting the learning value for each CDA driving mode learned in step S200, and then the corrected segment time value and the misfire diagnosis threshold set for each CDA driving mode are calculated. It is compared to diagnose misfire (S700).

In step S700, preferably, the engine speed and load condition at the time of measuring the segment time through the current CDA operation mode and step S500 are determined from map data storing misfiring diagnosis reference values for each CDA operation mode for two factors, engine speed and load. It is possible to diagnose a misfire by reading a corresponding misfire diagnosis reference value and comparing the read misfire diagnosis reference value with the corrected segment time value.

Specifically, in step S700, if the segment time value corrected through step S600 exceeds the read misfire diagnosis reference value, it is diagnosed that misfire has occurred in the active cylinder during CDA operation, and if misfire is diagnosed in the active cylinder during CDA operation, the current The process ends by executing control (S800) for forcibly ending the CDA operation being performed.

Although CDA engines have different combustion characteristics for each idle cylinder mode due to their characteristics, misfire detection standards are also different. In the past, misfire detection standards set in advance according to electric cylinder operation modes were uniformly applied without applying different misfire detection standards for each CDA operation mode. By applying misfire to detect misfire, the accuracy of misfire detection in CDA operation mode is reduced, and unnecessary CDA operation mode release due to false detection and excessive emission of harmful exhaust gases and serious catalyst damage due to non-detection are caused.

On the other hand, according to the misfire diagnosis apparatus and method for each CDA driving mode according to the embodiment of the present invention, when entering CDA driving, a misfire diagnosis threshold for each CDA driving mode is applied to diagnose misfire, thereby increasing the accuracy of diagnosis. As a result, it is possible to increase CDA operation time by reducing false fire detection during CDA operation, and prevent or minimize excessive emission of harmful exhaust gases and damage to the catalyst due to non-detection of misfire.

In the above detailed description of the present invention, only special embodiments have been described accordingly. However, it should be understood that the present invention is not limited to the particular forms mentioned in the detailed description, but rather it is understood to include all modifications, equivalents and substitutes within the spirit and scope of the present invention as defined by the appended claims. It should be.

10: crank angle sensor
20: Controller
22: learning storage unit
24: segment time corrector
26: misfire diagnosis unit
28: CDA operation end signal generating unit
30: crankshaft
40: target wheel
50: ignition coil
60: fuel injector

Claims (13)

As a method of diagnosing misfiring for each CDA operation mode of a CDA (Cylinder Deactivation) engine using segment time required for a crankshaft to rotate at a certain angle,
a) determining whether the vehicle state satisfies a condition for learning segment time for each CDA driving mode to be recorded as a learning value;
b) measuring the segment time for each CDA driving mode when the segment time learning condition is met and storing the measured value as a learning value for each CDA driving mode;
c) determining whether the condition of the vehicle satisfies conditions capable of diagnosing a misfire;
d) if misfire diagnosis conditions are satisfied, determining whether CDA operation has been entered;
e) measuring segment time in the current CDA driving mode upon entering CDA driving;
f) correcting the segment time value measured in step e) by reflecting the learning value for each CDA driving mode; and
g) diagnosing misfire by comparing the corrected segment time value with a misfire diagnosis threshold set for each CDA driving mode;
According to claim 1,
In step a),
A misfire diagnosis method for each CDA driving mode that determines whether the segment time learning condition is satisfied based on rough road driving, normal combustion of the active cylinder, and whether or not noise is generated in the output of each crank sensor.
According to claim 1,
In step b),
A misfire diagnosis method for each CDA operation mode that stores the segment time measurement value for each CDA operation mode as a learning value for each CDA operation mode along with engine speed (rpm) and load information at the time of measurement.
According to claim 1,
In step c),
Use some or all of whether the driving area generates positive (+) torque, whether the engine load variation is less than a certain level, whether the engine speed change rate is less than a certain level, whether driving on a rough road, and whether the fuel injector is broken A misfire diagnosis method for each CDA operation mode that determines whether misfire diagnosis conditions are satisfied by
According to claim 1,
In step g),
In the map data that stores misfiring diagnosis thresholds for each CDA operation mode for two factors, engine speed (rpm) and load (load), the current CDA operation mode and the engine at the time of measuring the segment time in step e) above. CDA operation mode that reads the misfire diagnosis threshold corresponding to the rpm and load conditions and compares the read misfire diagnosis threshold with the corrected segment time value to diagnose misfire Star Misfire Diagnosis Method.
According to claim 5,
A misfire diagnosis method for each CDA driving mode of diagnosing that a misfire has occurred in an active cylinder during CDA operation when the corrected segment time value exceeds the read misfire diagnosis threshold.
According to claim 1,
h) if misfire is diagnosed during CDA operation in step g), forcibly terminating CDA operation;
A crank angle sensor 10 disposed around a target wheel 40 of a crankshaft 30; and
A controller 20 for diagnosing misfiring for each CDA driving mode of the CDA engine using a segment time derived from the output of the crank angle sensor 10 and performing predetermined control according to the diagnosis result; includes,
The controller 20,
A learning storage unit that measures the segment time for each CDA driving mode and stores the measured value for each CDA driving mode as a learning value when the vehicle condition meets the condition for learning the segment time for each CDA driving mode. (22) and
Segment time correction unit that measures the segment time in the current CDA driving mode and corrects it by reflecting the learning value for each CDA driving mode to the measured value when the vehicle condition satisfies the conditions for diagnosing a misfire and enters CDA driving ( 24) and,
A misfire diagnosis device for each CDA driving mode comprising a misfire diagnosis unit 26 that diagnoses misfire by comparing the corrected segment time value with a misfire diagnosis threshold read from the data storage unit.
According to claim 8,
The learning storage unit 22,
A misfiring diagnosis device for each CDA operation mode that stores the segment time measurement value for each CDA operation mode as a learning value for each CDA operation mode along with engine speed (rpm) and load information at the time of measurement.
According to claim 8,
The misfire diagnosis unit 26,
The misfire diagnosis threshold corresponding to the current CDA operation mode and the engine speed (rpm) at the time of measuring the segment time for misfire diagnosis and the load condition is read from the data storage unit, and misfire diagnosis is read. A misfire diagnosis device for each CDA driving mode that diagnoses misfire by comparing a threshold with the corrected segment time value.
According to claim 10,
The misfire diagnosis unit 26,
A misfire diagnosis device for each CDA operation mode that diagnoses that a misfire has occurred in an active cylinder during CDA operation when the corrected segment time value exceeds the read misfire diagnosis threshold.
According to claim 8,
The controller 20,
When it is diagnosed by the misfire diagnosis unit 26 that a misfire has occurred during CDA operation, a CDA operation end signal generating unit 28 for generating and outputting a signal for forcibly ending CDA operation is provided for each CDA operation mode. Misfire diagnosis device.
A CDA engine vehicle comprising the misfire diagnosis device for each CDA driving mode according to any one of claims 8 to 12.

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