JP2013007391A - Misfire diagnostic device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect misfire even when crank angular velocity variation during misfire becomes small due to the effect of resonance of a damping member.SOLUTION: This misfire diagnostic device for an engine includes a device 5 having: a means for measuring time required for a predetermined crank angle variation during a combustion stroke for each cylinder; a means for storing a time measurement value for each ignition; a means for calculating a misfire parameter based on the stored values; a means for performing misfire determination on the basis of the misfire parameter and a misfire determination threshold; and a means for determining whether the misfire parameter is in an operation region affected by the resonance of a damping member. A first measurement section where an amount of increase in the time measurement value due to misfire is large or a second measurement section where an amount of increase in the time measurement value due to misfire is large in an operation region where the misfire parameter in accordance with the time measurement value in the first time measurement section is less than the misfire determination threshold due to the effect of resonance of the damping member even when the misfire occurs is selected in accordance with the operation region, and the misfire determination is performed using the misfire parameter based on the measurement value.

Description

  The present invention relates to a misfire diagnostic apparatus for detecting misfire of an internal combustion engine.

  A misfire diagnostic apparatus for an internal combustion engine includes a magnetic sensor facing a ring gear that rotates synchronously with the engine, and means for measuring an angular velocity of a predetermined crank angle section from a signal of the magnetic sensor, A device for determining misfire is disclosed in Patent Document 1. Specifically, the signal from the magnetic sensor is counted based on the cylinder discrimination signal (POS signal) and the reference position signal (Ref signal) of the crank angle sensor, and based on this count value, it rotates by a predetermined crank angle. The time TINT required is measured. Then, the angular velocity during the combustion stroke is calculated from the time TINT, and it is determined that a misfire has occurred if the fluctuation amount of the angular velocity exceeds a predetermined amount.

JP-A-2-213921

  By the way, in a vehicle that does not use a torque converter, such as a manual transmission-equipped vehicle or a hybrid vehicle, a buffer member may be interposed between the engine output shaft and the clutch in order to reduce a fastening shock.

  In such a vehicle, there is an operation region in which the fluctuation amount of the angular velocity when a misfire occurs is reduced due to the resonance caused by the characteristics of the buffer member.

  Therefore, in the configuration for measuring the rotation time TINT in the predetermined crank angle section as in the device disclosed in Patent Document 1, an accurate misfire diagnosis is performed for the operation region in which the resonance of the buffer member affects as described above. I can't.

  In view of the above, an object of the present invention is to make it possible to reliably detect misfire even in a case where there is an operating region in which the amount of change in angular velocity when misfiring occurs becomes small.

  The engine misfire diagnosis apparatus according to the present invention includes a time measuring unit that measures a time required for a predetermined crank angle section in a combustion stroke for each cylinder by counting signals output for each predetermined crank angle, and for each cylinder. A means for storing a time measurement value (TINT) for each ignition, a misfire parameter calculation means for calculating a misfire parameter based on these stored values, and a case where the misfire parameter exceeds a preset misfire determination threshold. A crank angle section that includes a misfire determination means that determines that misfire has occurred, and an operation area detection means that detects an engine operation area, and in which the time measurement means performs measurement is a crank angle section corresponding to a combustion stroke. A crank angle section in which the amount of increase in time measurement value (TINT) due to misfire is relatively large, and the misfire determination means The misfire is determined using the misfire parameter calculated based on the time measurement value (TINT) measured in the crank angle section in which the increase amount of the time measurement value (TINT) becomes relatively large when misfire occurs. .

  According to the present invention, the misfire determination is performed using the misfire parameter calculated based on the time measurement value measured in the crank angle interval in which the increase amount of the time measurement value when the misfire occurs increases. Even when the operation region is affected by the resonance of the member, misfire can be reliably detected.

It is a system configuration figure of a 1st embodiment. (A)-(d) is a figure for demonstrating the misfire determination method. (A)-(d) is a figure for demonstrating the influence which the resonance of a damper has on misfire determination. It is a flowchart of control for misfire determination of 1st Embodiment. It is a figure for demonstrating the relationship between the misfire parameter when the amount of ignition timing retards is small, and the threshold value for misfire determination. It is a figure for demonstrating the relationship between the misfire parameter when the amount of ignition timing retards is large, and the threshold value for misfire determination. (A)-(d) is a figure for demonstrating the effect of switching a TINT measurement area. It is a flowchart of the control for misfire determination of 2nd Embodiment.

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

  FIG. 1 is an example of a configuration diagram of an engine system to which the present embodiment is applied. Reference numeral 1 denotes an engine, 2 a drive system comprising a clutch and a transmission. Reference numeral 3 denotes a damper interposed between the engine 1 and the drive system 2 in order to reduce the output fluctuation of the engine 1 and the impact at the time of clutch engagement. 4 is a flywheel provided at the end of the crankshaft 1 a, 5 is a control unit (time measurement means, time measurement value storage means, misfire parameter calculation means, and misfire determination means), and 6 is provided on the outer periphery of the flywheel 4. A magnetic pickup 7 disposed opposite to the teeth of the ring gear is a known crank angle sensor serving as an operation region detecting means and an ignition timing detecting means.

  The magnetic pickup 6 includes an iron core and a coil. When the crankshaft 1a rotates, the teeth of the ring gear intermittently generate a magnetic field generated in the iron core of the magnetic pickup 6, so that a magnetic force change occurs in the coil of the magnetic pickup 6, An alternating current is induced. The AC signal that detects this AC current is shaped in the control unit 5 and converted into a rectangular wave ON / OFF pulse (ring gear POS signal) and used as a crank angle signal.

  A known crank angle sensor 7 is provided on a cam shaft (not shown) driven by the crankshaft 1 a, and a Ref signal (reference position signal) from the crank angle sensor 7 is also sent to the control unit 5. The Ref signal is also a rectangular wave pulse signal.

  In the control unit 5, a predetermined number of pulses (pulses obtained by the magnetic pickup 6) from the input of the Ref signal for the first cylinder of the crank angle sensor 7 is counted as a reference per predetermined angle section of the crankshaft 1a. The time required (TINT) is sampled. Then, the angular velocity during the combustion stroke is measured from TINT, and misfire determination is performed based on this angular velocity.

  FIG. 2 is a diagram for explaining a TINT measurement procedure and a misfire determination method. In addition, it shows about the operation area | region which does not have the influence of the damper 3 mentioned later.

  The counter value in FIG. 2 (a) is incremented by 1 each time the ring gear POS signal falls on the basis of when the Ref signal of the first cylinder rises, and is reset when the counter value reaches 15.

  The ring gear has a tooth missing portion. For this reason, when the tooth missing part passes in front of the magnetic pickup 6, the ring gear POS signal interval becomes longer than the others (in FIG. 2, the interval from the counter value 14 to 15). Here, it is assumed that ignition is performed at the timing when the counter value becomes 1.

  In this embodiment, the measurement of TINT starts when the counter value reaches 13, and ends when the counter value reaches 4. TINT is updated every time measurement is completed, as shown in FIG.

  FIG. 2B shows the fluctuation of the pulse width of the POS interval, that is, the ring gear POS signal. The larger the POS interval, the longer the time required for one ring gear tooth to pass.

  Next, an outline of misfire determination will be described. The misfire determination is made based on whether or not the misfire parameter calculated based on the measured TINT exceeds a preset misfire determination threshold. The misfire parameter calculation method will be described later.

  If a misfire occurs due to the ignition at the timing F2 in FIG. 2A, the rotational speed of the crankshaft 1a decreases. Therefore, as shown in FIG. 2B, the third TINT measurement in FIG. 2A is performed. The POS interval in the section increases. That is, as shown in FIGS. 2C and 2D, TINT and misfire parameters increase.

  Here, as shown in FIG. 2D, when the misfire parameter exceeds the misfire determination threshold, it is determined that there is misfire. On the other hand, if the misfire determination threshold is not exceeded, it is determined that there is no misfire.

  The ring gear POS signal fluctuates even when there is no misfire, but this is due to engine rotation fluctuations that occur even during normal operation.

  By the way, when the damper 3 is provided as shown in FIG. 1, the resonance of the damper 3 affects the fluctuation of the ring gear POS signal at the time of misfire, and there is an operation region in which the fluctuation of TINT at the time of misfire becomes small.

  FIGS. 3A to 3D are views corresponding to FIGS. 2A to 2D with respect to the operation region in which the resonance of the damper 3 is affected. As in FIG. 2, if a misfire occurs due to ignition at the ignition timing F2, in the region A in FIG. 3 (b), the variation in the POS interval is smaller than in the case of FIG. 2 (b). In this case, as shown in FIGS. 3C and 3D, the variation in TINT is reduced. Also, in the fourth TINT measurement in the figure, the POS interval is increased due to the influence of the resonance of the damper 3. For this reason, the misfire determination parameter is reduced, and as a result, the misfire parameter does not exceed the misfire determination threshold value despite the misfire. That is, misfire cannot be detected.

  Therefore, the control described below is performed in order to reliably detect misfire even in the operation region affected by the resonance of the damper 3.

  FIG. 4 is a flowchart of misfire detection control. This control is always executed during engine rotation. Whether or not the engine is rotating can be determined by whether or not a ring gear POS signal is input, for example.

  In step S101, it is determined whether or not the engine rotation is within the region affected by the resonance of the damper 3. Whether or not it is affected by the resonance of the damper 3 is determined in advance for each specification of the damper 3 through experiments or the like.

  If it is within the affected range, the process proceeds to step S109; otherwise, the process proceeds to step S102.

  In step S102, TINT is measured in the measurement section A for normal operation. The measurement section A is a measurement section in which accurate misfire detection can be performed if there is no influence of the resonance of the damper 3. For example, the measurement section A has counter values 13 to 4 as shown in FIG.

  In step S103, the misfire parameter MA is calculated based on the measured TINT. As the misfire parameter MA, known misfire parameters, for example, misfire parameters MISA and MISC disclosed in Japanese Patent Laid-Open No. 9-68095 are used.

  In step S104, it is determined whether or not a measurement section to be described later has been switched before a predetermined cycle of the current misfire parameter MA calculation. This is because an accurate misfire parameter cannot be calculated because a step occurs in TINT when the measurement section is switched. Note that how to set the “predetermined cycle” varies depending on the measurement section to be switched, engine characteristics, and the like. Therefore, the size of the TINT step at the time of switching the measurement section is obtained in advance through experiments or the like, and a predetermined number of cycles is set accordingly.

  If the measurement section is switched before a predetermined cycle, the process is terminated. If there is no switching before the predetermined cycle, the process proceeds to step S105.

  In step S105, it is determined whether or not the misfire parameter MA is equal to or greater than a preset misfire determination threshold THA. The misfire determination threshold value THA is set to such a value that the misfire parameter MA in the event of misfire is obtained through experiments or the like and the presence or absence of misfire can be reliably detected based on this.

  When the misfire parameter MA is smaller than the misfire determination threshold THA, the process proceeds to step S108, and it is determined that there is no misfire and the process is terminated. If greater than the misfire determination threshold THA, it is determined in step S106 that misfire has occurred, and in step S107, the misfire counter counts the number of misfires.

  On the other hand, if the engine speed region is affected by the resonance of the damper 3 in step S101, the process proceeds to step S109 to determine whether or not the ignition timing retard amount is within a predetermined range described later. If it is within the predetermined range, the process proceeds to step S110, and if it is outside the predetermined range, the process proceeds to step S102 described above.

  In step S110, the TINT measurement section is switched to measurement section B. In the measurement section B, a section in which an increase in TINT at the time of misfire can be reliably detected in the engine speed region affected by the resonance of the damper 3 is obtained by experiment and set. Here, the counter values in FIG.

  In step S111, the misfire parameter MB is calculated based on the TINT measured in step S110, as in step S103.

  The processes after step S112 are the same as steps S104 to S108. However, a value for the case where TINT is measured in the measurement section B is set as the misfire determination threshold value THB. This is because there is a possibility that misfire cannot be detected with the misfire determination threshold THA because the amount of change in the POS interval at the time of misfire varies depending on the measurement section.

  Here, the determination of the ignition timing retard amount in step S109 will be described. FIGS. 5 and 6 are diagrams showing the relationship between the misfire parameter and the engine speed. FIG. 5 is a diagram when the ignition timing is a reference value, and FIG. 6 is a diagram when the ignition timing retard amount is large. The misfire parameters MA and MB in FIGS. 5 and 6 indicate values when misfire has occurred.

  Here, “the ignition timing retard amount is large” means that the retard amount is relatively within the advance / retard angle range that is variably controlled according to the engine load or the like as in general ignition timing control. The big case.

  As shown in FIG. 5, in the region affected by the resonance of the damper 3, the misfire parameter MA by TINT in the measurement section A when misfire occurs becomes smaller than the misfire determination threshold THA, and misfire is detected. Can not. On the other hand, the misfire parameter MB due to TINT in the measurement section B exceeds the misfire determination threshold value THB in the region affected by the resonance of the damper 3, so that misfire can be detected.

  On the other hand, if the ignition timing retard amount is increased, the peak timing of the combustion pressure is shifted. For this reason, in the region affected by the resonance of the damper 3, as shown in FIG. 6, the misfire parameter MB increases only to approximately the same as the misfire determination threshold value THB, and the misfire cannot be detected. In this case, the misfire parameter MA is also substantially equal to the misfire determination threshold value THA.

  Therefore, an ignition timing retard amount at which misfire cannot be detected even when switching to the measurement section B is obtained by experiments or the like, and a range equal to or smaller than the ignition timing retard amount is set as the “predetermined range” in step S109. When the ignition timing is retarded beyond a predetermined range, switching of the measurement section is not effective, and therefore switching is not executed.

  FIG. 7 is a chart when the above control is executed in the same conditions as in FIG. 3, that is, in the engine speed region affected by the resonance of the damper 3. It is assumed that the ignition timing retard amount is within a predetermined range.

  As for the measurement of TINT, the measurement section A during normal operation has a counter value of 13 to 4, and the measurement section B in the engine speed region affected by the resonance of the damper 3 is advanced from the measurement section A. 10 to 1.

  As in FIG. 3, when a misfire occurs due to ignition at the ignition timing F <b> 2, the variation in the POS interval is larger in the measurement section B at timings t <b> 1 to t <b> 3 than in the measurement section A at timings t <b> 2 to t <b> 4. Further, in the measurement section B at the timing t5 to t7, the variation in the POS interval is smaller than that in the measurement section A at the timing t6 to t8. For this reason, the fluctuation of TINT also increases, and as a result, the misfire parameter MB calculated at timing t7 becomes larger than the misfire determination threshold value THB, so that misfire can be detected. That is, misfire that could not be detected in the measurement section A can be detected by switching to the measurement section B.

  Here, the measurement section B is set to a counter value of 10 to 1. However, the counter value is obtained by experimentally determining a variation characteristic of the POS interval when misfire occurs, and reliably detects misfire based on this. It is set so that it can be done. Therefore, if the fluctuation characteristics of the POS interval are different due to differences in engine specifications, etc., different counter values are set as the measurement section B.

  As described above, in the present embodiment, the following effects can be obtained.

  (1) Means for measuring TINT, which is a time required for a predetermined crank angle section in the combustion stroke, for each cylinder, means for storing this TINT for each ignition, means for calculating a misfire parameter based on these stored values The control unit 5 having means for determining that misfire has occurred when the misfire parameter is equal to or greater than a preset misfire determination threshold value, and a crank angle sensor 7. The angle section is a crank angle section in which the increase amount of TINT due to misfire is relatively large in the crank angle section corresponding to the combustion stroke, and when the misfire occurs in the current operation region, the increase amount of TINT is increased. Since misfire determination is performed using misfire parameters calculated based on TINT measured in a relatively large crank angle section, Even if there is influence of the third resonance can be reliably detect misfiring.

  (2) Since it is determined whether or not misfire has occurred using the misfire determination threshold value corresponding to the crank angle interval for measuring TINT, misfire can be detected even if the TINT measurement interval is changed.

  (3) Either the measurement section A for the engine speed region that is not affected by the resonance of the damper 3 or the measurement section B for the engine speed region that is affected by the resonance of the damper 3 is set according to the engine speed region. Thus, the TINT measurement is performed, so that misfire can be reliably detected over the entire engine speed range.

  (4) When the measurement section is switched, misfire determination is prohibited until a predetermined time elapses from the end of the switching, and therefore it is possible to prevent erroneous determination due to a TINT step caused by the switching.

  (5) When the ignition timing retard amount is greater than or equal to the predetermined amount, determination of whether or not misfire has occurred is prohibited. This is unnecessary in situations where accurate misfire determination cannot be made due to the shift of the peak timing of the combustion pressure. It is possible to prevent misfire determination.

  A second embodiment will be described.

  The present embodiment has the same configuration as the first embodiment, but the control for misfire detection is different. FIG. 8 is a flowchart of misfire detection control executed by the control unit 5 in this embodiment. Note that the control in FIG. 8 is always executed during engine rotation, as in the control in FIG.

  In steps S201 and S202, the TINT measurement is performed in the measurement section A and the misfire parameter MA is calculated in the same manner as in steps S102 and S103 of FIG.

  In steps S203 and S204, TINT measurement is performed in the measurement section B as in steps S110 and S111 of FIG. 4, and the misfire parameter MB is calculated.

  Note that steps S203 to S204 may be performed prior to steps S201 to S202, or these may be performed in parallel.

  In step S205, as in step S101 of FIG. 4, it is determined whether or not the engine speed is within a predetermined range. If it is within the predetermined range, the process proceeds to step S206. If it is outside the predetermined range, the process proceeds to step S210.

  In step S206, as in step S109 of FIG. 4, it is determined whether or not the ignition timing retard amount is within a predetermined range. If it is within the predetermined range, the process proceeds to step S207. If it is outside the predetermined range, the process proceeds to step S210.

  In step S207, it is determined whether or not the misfire parameter MB is equal to or greater than the misfire determination threshold THB as in step S113 of FIG. If the misfire parameter MB is smaller, the process proceeds to step S212, where it is determined that there is no misfire, and the process ends.

  In step S208, it is determined that there is a misfire as in step S106 of FIG. 4, and the process proceeds to step S209.

  In step S209, similarly to step S107 in FIG. 4, the misfire counter counts the number of misfires.

  On the other hand, if it is determined in step S205 that the engine speed is outside the predetermined range, and if it is determined in step S206 that the ignition timing retard amount is outside the predetermined range, the process proceeds to step S210.

  In step S210, as in step S105 of FIG. 4, it is determined whether or not the misfire parameter MA is equal to or greater than the misfire determination threshold THA. If the misfire parameter MA is smaller, it is determined in step S211 that there is no misfire, and the process ends. If the misfire parameter MA is greater than or equal to the misfire determination threshold THA, the process proceeds to step S208.

  As described above, instead of switching the measurement section according to the engine speed region, TINT measurement and misfire parameter calculation are performed for each of the measurement section A and measurement section B, and either measurement is performed according to the engine speed region. Select the interval value and perform misfire determination. As a result, the TINT level difference associated with the switching of the measurement section is eliminated, so that the chance of misfire determination can be prevented from decreasing.

  In the present embodiment, two measurement sections, measurement section A and measurement section B, are provided. However, depending on the vibration characteristics of the damper 3, for example, the measurement section on the retarded side from measurement section A or the measurement section B may be further increased. An advance angle measurement section or the like may be further provided.

  The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

1 Engine 2 Drive System 3 Damper 4 Flywheel 5 Control Unit 6 Magnetic Pickup 7 Crank Angle Sensor

An engine misfire diagnostic apparatus according to the present invention counts a signal output at every predetermined crank angle in an engine misfire diagnostic apparatus applied to a vehicle having a buffer member between an engine output shaft and a drive system. The time measurement means for measuring the time required for a predetermined crank angle section in the combustion stroke for each cylinder, the means for storing the time measurement value (TINT) for each cylinder for each ignition, and the misfire parameter based on these stored values Misfire parameter calculating means for calculating the misfire, misfire determination means for determining that misfire has occurred when the misfire parameter is equal to or greater than a preset misfire determination threshold value , and misfire based on the engine speed and ignition timing. parameter and an operating region determining means for determining whether the engine operating region affected by the resonance of the cushioning member, the time measurement hands In the first measurement section, which is a crank angle section in which the amount of increase in the time measurement value due to misfire is relatively large, or in the time measurement value in the first measurement section due to the resonance of the buffer member, misfire occurs. Even if the misfire parameter does not exceed the misfire determination threshold value, the second measurement section, which is the crank angle section in which the amount of increase in the time measurement value due to misfire becomes relatively large, is set according to the operation area. The misfire determination means uses the misfire parameter calculated based on the time measurement value measured in the selected measurement section of the first measurement section or the second measurement section . Determine misfire.

According to the present invention , either the first measurement section for the engine speed region where the influence of the resonance of the buffer member is not influenced or the second measurement section for the engine speed region where the influence of the resonance of the buffer member is influenced is Since TINT is measured by selecting according to the rotational speed region , misfire can be reliably detected over the entire engine rotational speed region .

Claims (6)

Time measuring means for measuring the time required for a predetermined crank angle section in the combustion stroke for each cylinder by counting a signal output for each predetermined crank angle;
Means for storing the time measurement value for each cylinder for each ignition;
Misfire parameter calculating means for calculating a misfire parameter based on these stored values;
Misfire determination means for determining that misfire has occurred when the misfire parameter is equal to or greater than a preset misfire determination threshold;
An operating region detecting means for detecting an engine operating region;
With
The crank angle section in which the time measuring means performs measurement is a crank angle section in which an increase amount of the time measurement value due to misfire is relatively large in the crank angle section corresponding to the combustion stroke,
The misfire determination means uses the misfire parameter calculated based on the time measurement value measured in a crank angle section in which an increase amount of the time measurement value becomes relatively large when a misfire occurs in a current operation region. An engine misfire diagnostic device that determines misfire.   The engine misfire diagnosis apparatus according to claim 1, wherein the misfire determination means determines whether or not misfire has occurred using a misfire determination threshold value corresponding to a crank angle section in which the time measurement value is measured.   The time measurement means is a first measurement section that is a crank angle section in which an increase amount of the time measurement value caused by misfire in a predetermined operation region is relatively large, or a time measurement value in the first measurement section. Then, any one of the second measurement sections which are crank angle sections in which the increase amount of the time measurement value due to misfire is relatively large in the operation region where the misfire parameter does not exceed the misfire determination threshold even if misfire occurs. The engine misfire diagnosis apparatus according to claim 1 or 2, wherein the time measurement value is measured by selecting the value according to an operation region.   The engine misfire diagnosis apparatus according to claim 3, wherein when the measurement section is switched, the misfire determination is prohibited until a predetermined time elapses from the end of the switching. The time measurement means measures the time measurement value in a plurality of crank angle sections during a combustion stroke,
The misfire parameter calculation means calculates a misfire parameter corresponding to the plurality of time measurement values,
The misfire determination means selects a misfire parameter that becomes larger than the misfire determination threshold when a misfire occurs in the current operation region among a plurality of misfire parameters, and determines whether or not misfire has occurred. The engine misfire diagnostic apparatus according to claim 1 or 2. Means for detecting ignition timing,
The engine misfire diagnosis apparatus according to any one of claims 1 to 5, wherein when the amount of retardation from the basic ignition timing is equal to or larger than a predetermined amount set in advance, the determination as to whether or not misfire has occurred is prohibited.

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