JP5867311B2 - Abnormality diagnosis device - Google Patents

Description

  The present invention relates to an abnormality diagnosing device for diagnosing an abnormality in a fuel property or a fuel injection valve.

  In recent years, the development of an internal combustion engine that assumes the use of a mixed fuel in which alcohol is mixed with gasoline has been advanced. In this type of internal combustion engine, when a mixed fuel having an alcohol concentration exceeding a specified value is used, it is desirable to perform fail-safe control such as limiting the output of the internal combustion engine. For this reason, Patent Documents 1 and 2 disclose that a sensor for detecting the alcohol concentration is provided and an abnormality (proper property) of the mixed fuel is detected by the sensor.

  Further, even in cases other than such a mixed fuel, the supplied fuel may be defective in properties, so a sensor for detecting the properties of the fuel is provided, the property failure is detected by the sensor, and fail-safe control is performed. It is hoped that.

Japanese Patent Application Laid-Open No. 2001-179559 Japanese Patent Laid-Open No. 2010-190075

  However, since the above-described sensor (property sensor) is expensive, a method for detecting a defective property without using a sensor has been desired. Even if a property sensor is provided, a failure of the property sensor can be detected if a property defect can be detected without using the sensor.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an abnormality diagnosing apparatus that can determine fuel property failure without using a property sensor. Another object of the present invention is to provide an abnormality diagnosing device that can determine the abnormality occurrence location of a fuel injection valve.

The invention for achieving the above object is characterized by the following points. That is, a leakage quantity of fuel occurring in the fuel injection valve of an internal combustion engine, a static leakage quantity estimation means for estimating the static leakage quantity generated during injection stop the fuel injection valve is not injected actuated fuel injection a leakage quantity of fuel occurring within the valve, fuel and dynamic leakage quantity estimation means for estimating the dynamic leakage quantity caused by the injection operation of the injection valve, the estimated static leakage quantity and dynamic leakage quantity the basis, the fuel is determined whether a property poor, and the abnormality cause determination means for performing at least one of the determination of the abnormality occurrence location fuel injection valve, the pressure of fuel supplied to the fuel injection valves The fuel pressure sensor that detects the pressure and the amount of time that the pressure naturally drops in a predetermined time in the injection stop state, or the time that the pressure naturally drops by the predetermined amount Time acquisition means and jet An operation time acquisition means for acquiring, as an operation drop value, a drop amount in which the pressure drops in a predetermined time or a drop time required for the pressure to drop by a predetermined amount in a state in which the pressure drops with operation; The static leak amount estimation means estimates the static leak amount based on the stop descent value, and the dynamic leak amount estimation means estimates the dynamic leak amount based on the difference between the descent value during operation and the descent value during stop The stop-time acquisition means and the operation-time acquisition means start the measurement of the stop-time drop value and the start-time drop value on condition that the pressure is equal to or higher than the predetermined pressure. It is characterized by being set to a value that exceeds the quantity .

  Here, in the case of poor properties where the viscosity of the fuel becomes an unspecified value exceeding the assumption, both the static leak amount and the dynamic leak amount should be abnormal values. For example, if the viscosity is high, both the leakage amounts are reduced, and if the viscosity is low, both the leakage amounts are increased. On the other hand, if the static leak amount is an abnormal value and the dynamic leak amount is a normal value, an abnormality has occurred in the static leak portion of the fuel injection valve, and the dynamic leak portion and the fuel properties are normal. It is. Conversely, if the static leak amount is a normal value and the dynamic leak amount is an abnormal value, an abnormality has occurred in the portion of the fuel injection valve where the dynamic leak occurs, and the static leak portion and the fuel properties are normal. is there.

  Focusing on these points, in the above invention, at least one of the determination of whether or not the fuel has poor properties and the determination of the location where the fuel injection valve has failed is performed based on the static leak amount and the dynamic leak amount. Thus, it is possible to determine the fuel property failure or the fuel injection valve abnormality occurrence location without using a property sensor.

The figure which shows the outline | summary of the fuel-injection system with which the abnormality diagnosis apparatus which is one Embodiment of this invention is applied. The graph which shows transition in which rail pressure falls with a static leak. The graph which shows transition in which rail pressure falls with single shot micro injection. A map showing the relationship between rail pressure drop time and drop, and fuel consumption. The flowchart which shows the process sequence of property defect determination and abnormality occurrence location determination. FIG. 6 is a flowchart showing a subroutine for estimating the amount of static leak in FIG. 5. The time chart which shows the one aspect | mode of a rail pressure change. FIG. 6 is a flowchart showing a processing procedure for estimating a dynamic leak amount, which is the subroutine processing of FIG. 5. FIG. The figure which shows the relationship between the amount of dynamic leaks and the amount of static leaks, and rail pressure.

  Hereinafter, an embodiment of an abnormality diagnosis apparatus according to the present invention will be described with reference to the drawings.

  A fuel injection valve 10 shown in FIG. 1 injects fuel to be used for combustion of an internal combustion engine, and is controlled by an electronic control unit (ECU 11) to inject high-pressure fuel supplied from an accumulator vessel 12. In the example of FIG. 1, a multi-cylinder internal combustion engine is assumed, and high-pressure fuel is distributed from a pressure accumulating vessel 12 to a fuel injection valve 10 provided in each cylinder.

  The fuel injection valve 10 includes a body 20, a needle 30, a piston 40, a control valve 50, an electromagnetic coil 60, and the like described below. The body 20 has an injection hole 21 for injecting fuel, a high-pressure passage 22 for guiding the high-pressure fuel supplied from the pressure accumulating vessel 12 to the injection hole 21, and a fuel tank (not shown) that leaks fuel inside the body 20. ) Is formed.

  The needle 30 is slidably disposed in the high pressure passage 22. When the needle 30 is lifted down and seated on the seat surface 22a of the body 20, the high pressure passage 22 is closed and fuel injection from the injection hole 21 is stopped. On the other hand, when the needle 30 is lifted up and separated from the seat surface 22 a, the high-pressure passage 22 is opened and fuel is injected from the injection hole 21. The elastic force of the spring 31 and the operating force of the piston 40 are applied to the needle 30 as the valve closing force in the valve closing direction (downward in FIG. 1), and the fuel pressure in the fuel reservoir 22b of the high pressure passage 22 is applied. Is provided as the valve opening force in the valve opening direction (upward in FIG. 1).

  The piston 40 is slidably disposed inside the body 20. The fuel pressure (back pressure) in the back pressure chamber 24 formed inside the body 20 is applied to the piston 40 in a direction (downward in FIG. 1) to close the needle 30, and this back pressure is described above. Acting force of the piston 40 is obtained. The high pressure fuel in the high pressure passage 22 flows into the back pressure chamber 24 through the inflow orifice 24a. The high pressure fuel in the back pressure chamber 24 flows out to the low pressure passage 23 through the outflow orifice 24b.

  The control valve 50 is a valve body that opens and closes the outflow orifice 24 b. When the ECU 11 energizes the electromagnetic coil 60 to generate an electromagnetic force, the control valve 50 is attracted by the electromagnetic force and resists the elastic force of the spring 51. Then, the control valve 50 opens the outflow orifice 24b. On the other hand, when the ECU 11 turns off the energization of the electromagnetic coil 60, the control valve 50 closes the outflow orifice 24b by the elastic force of the spring 51.

  Next, the operation of the fuel injection valve 10 will be described.

  When the ECU 11 energizes the electromagnetic coil 60, the control valve 50 opens and the fuel in the back pressure chamber 24 flows out (dynamic leak) from the outflow orifice 24b. Then, the back pressure gradually decreases and the piston operating force decreases. When the valve closing force (spring elastic force + piston operating force) of the needle 30 becomes smaller than the valve opening force, the needle 30 starts to lift up and fuel injection from the injection hole 21 is started.

  On the other hand, when the ECU 11 turns off the electromagnetic coil 60, the control valve 50 closes and the outflow (dynamic leak) from the outflow orifice 24b stops. Then, the back pressure gradually increases, and the piston operating force increases. When the valve closing force (spring elastic force + piston operating force) of the needle 30 becomes larger than the valve opening force, the needle 30 starts to lift down, and fuel injection from the injection hole 21 is stopped.

  The injection is not stopped when the needle 30 starts to lift down, and the injection is also performed during the period from when the needle 30 starts to lift down until the needle 30 is seated on the seat surface 22a (valve closing operation period). Fuel will continue to be injected from the hole 21. The injection amount during such a valve closing operation period is regarded as the amount of dynamic leak from the seat surface 22a during the valve closing operation. Alternatively, the period from when the energization of the electromagnetic coil 60 is switched from energization on to the energization off until the needle 30 is seated on the seat surface 22a is defined as the valve closing operation period, and the injection amount during this valve closing operation period is regarded as the dynamic leak amount. May be.

  In short, a leak from the seat surface 22a and a leak from the outflow orifice 24b during the valve closing operation period are assumed as main dynamic leaks occurring inside the fuel injection valve 10. Further, the high pressure fuel in the back pressure chamber 24 leaks to the low pressure passage 23 through the sliding surface 20 a on which the piston 40 slides in the body 20. Similarly, the high-pressure fuel in the fuel reservoir 22 b leaks to the low-pressure passage 23 through the sliding surface 20 b on which the needle 30 slides in the body 20. These leaks from the sliding surfaces 20 a and 20 b always occur regardless of the operating state of the fuel injection valve 10, and are assumed as main static leaks that occur inside the fuel injection valve 10.

The fuel pressure (rail pressure) in the pressure accumulator 12, that is, the pressure of the fuel supplied to the fuel injection valve 10 decreases with fuel injection from the injection hole 21, and the amount of decrease in rail pressure increases as the injection amount increases. Become more. Similarly, the rail pressure decreases with the above-described static leak and dynamic leak, and the amount of decrease in rail pressure increases as the amount of leak increases.
Focusing on this point, in this embodiment, the rail pressure is detected by the rail pressure sensor 13 (fuel pressure sensor) provided in the pressure accumulating vessel 12, and based on the transition of the rail pressure drop caused by the leak, The ECU 11 estimates the leak amount and the dynamic leak amount.

  FIG. 2 is a graph showing a transition in which the rail pressure decreases due to a static leak, and the injection cut control is performed so as to stop the fuel injection from the fuel injection valve 10 due to the deceleration operation of the internal combustion engine. It is a transition of rail pressure in the period (deceleration no injection period) in which FIG. 3 is a graph showing a transition in which a small amount of fuel that cannot be detected by a vehicle occupant is injected once during deceleration-less injection, and the rail pressure decreases with the single micro-injection. However, this drop in rail pressure includes the amount of drop due to dynamic leak and static leak. In addition, before the time ta when the rail pressure starts to drop and after the time tb when the rail pressure ends, the high pressure fuel is pumped from the fuel pump (not shown) to the pressure accumulating vessel 12, and thus the rail pressure drops. Absent.

  The ECU 11 measures the drop amount ΔPa and the drop time ΔTa of the rail pressure during the deceleration no-injection period ta to tb. In the example of FIG. 2, the time required for the pressure to drop by a predetermined amount (fall amount ΔPa) (fall time ΔTa) is measured. In addition, the rail pressure drop amount ΔPb and the drop time ΔTb are measured in the period ta to tb after the single micro injection is started. In the example of FIG. 3, the amount of decrease ΔPb that occurs during the elapse of a predetermined time (decrease time ΔTb) from the time point tc when the minute injection starts is measured.

  Furthermore, the ECU 11 calculates the fuel consumption amount Qa when the fuel injection valve 10 is not in injection, using the map shown in FIG. 4, based on the measured decrease amount ΔPa and the decrease time ΔTa. The map of FIG. 4 may be created based on the test results measured in advance, or may be created based on the numerical analysis results. Similarly, based on the measured drop amount ΔPb and the drop time ΔTb at the time of micro injection, the fuel consumption amount Qb at the time of micro injection is calculated using the map shown in FIG. Note that the consumption amounts Qa and Qb increase as the drop amounts ΔPa and ΔPb increase and the drop times ΔTa and ΔTb increase. Further, the calculated consumption amounts Qa and Qb may be corrected according to the rail pressure and the fuel temperature at the start of measurement.

  As described above, the consumption amount Qb at the time of minute injection includes the injection amount, the dynamic leak amount, and the static leak amount. On the other hand, the consumption Qa at the time of non-injection includes only the static leak amount. Focusing on this point, the ECU 11 regards the consumption amount Qa when there is no injection as the static leak amount. Further, the amount of dynamic leak is estimated based on the difference between the amount of consumption Qb during micro-injection (the drop value during operation) and the amount of consumption Qa during non-injection (the drop value during stop). Specifically, a value obtained by subtracting the non-injection consumption amount Qa and the minute injection amount from the consumption amount Qb at the time of minute injection is regarded as a dynamic leak amount.

  Further, the ECU 11 determines whether or not the fuel is defective in properties and determines where the abnormality has occurred in the fuel injection valve 10 based on the dynamic leak amount and the static leak amount estimated as described above. Hereinafter, the determination procedure executed by the microcomputer of the ECU 11 will be described with reference to FIG.

  First, in step S10 of FIG. 5, it is determined whether or not the internal combustion engine is in an initial state. Specifically, when the operating time of the internal combustion engine is less than a predetermined time or the total travel distance of the vehicle is less than a predetermined distance, it is determined that the initial state is set. If it is determined that the current state is not the initial state (S10: NO), the above-described estimation of the static leak amount is performed on the condition that the vehicle has traveled a predetermined distance from the previous estimation of the static leak amount and the dynamic leak amount (S11: YES). Implemented in S12 (static leak amount estimating means).

  In the subsequent step S13, abnormality determination is performed as to whether or not the estimated value of the static leak amount is within a normal range. If it is determined that there is an abnormality (S13: YES), the static leak abnormality flag is set to ON in the subsequent step S14. Next, the above-described estimation of the dynamic leak amount is performed in step S15 (dynamic leak amount estimation means). In the subsequent step S16, an abnormality determination is made as to whether or not the estimated value of the amount of dynamic leak is within the normal range. If it is determined that there is an abnormality (S16: YES), the dynamic leak abnormality flag is set to ON in the subsequent step S17.

  Next, in steps S18 to S20, the combination of the static leak abnormality flag and the dynamic leak abnormality flag is determined. Then, according to the determination result, the presence / absence of the fuel property defect and the abnormality occurrence location of the fuel injection valve 10 are determined in steps S21 to S24. Steps S18 to S23 are “abnormal cause determination means”, steps S18, S19, and S21 are “fuel property determination means”, steps S18, S19, and S22 are “static leak abnormality determination means”, and steps S18, S20, and S23 are This corresponds to “dynamic leak abnormality determination means”.

  Specifically, when both the static leak abnormality flag and the dynamic leak abnormality flag are on (S18: YES, S19: YES), it is determined in step S21 that the fuel has poor properties. When the static leak abnormality flag is on and the dynamic leak abnormality flag is off (S18: YES, S19: NO), in step S22, a portion (sliding surface 20a, 20b) is determined to be an abnormality occurrence location. When the static leak abnormality flag is off and the dynamic leak abnormality flag is on (S18: NO, S20: YES), in step S23, the portion of the fuel injection valve 10 that causes dynamic leakage (outflow orifice 24b, seat) It is determined that the surface 22a) is an abnormality occurrence location.

  For example, if the wear of the sliding surfaces 20a and 20b progresses significantly beyond the assumption, the amount of static leakage increases beyond the normal range. In addition, when foreign matter is bitten or adhered to the sliding surfaces 20a and 20b, the amount of static leakage is reduced beyond the normal range. Similarly, when the wear of the outflow orifice 24b and the seat surface 22a proceeds remarkably beyond the assumption, the amount of dynamic leakage increases beyond the normal range. Further, if foreign matter is bitten or adhered to the outflow orifice 24b and the sheet surface 22a, the amount of dynamic leakage decreases beyond the normal range.

  When both the static leak abnormality flag and the dynamic leak abnormality flag are off (S18: NO, S20: NO), in step S24, both the dynamic leak portion and the static leak portion are normal, and the fuel property is also A normal judgment is made that it is normal.

  Next, the subroutine processing in step S12 shown in FIG. 5 will be described with reference to FIGS. First, in step S30 in FIG. 6, the system waits until a time point ta (see FIG. 7) at which no deceleration is injected. When the vehicle is in the state of no deceleration deceleration (S30: YES), in the subsequent step S31, it waits until the time t1 when a predetermined delay time elapses. At this time, when the rail pressure (actual Pc) is not equal to or higher than the predetermined pressure (start Pc) (S32: NO), the process stands by again until the next deceleration no injection. If actual Pc ≧ start Pc (S32: YES), the process waits until time t2 when actual Pc = start Pc. When actual Pc = start Pc (S33: YES), in the subsequent step S34, the measurement of the descent time ΔTa described above is started.

  Thereafter, when the actual Pc drops to a predetermined pressure (end Pc) (S35: YES), the measurement of the descent time ΔTa is finished at the time t3 when the actual Pc = end Pc, and the measured time, that is, the start Pc ends. The descent time ΔTa required up to Pc is stored (S36). However, as indicated by the dotted line in FIG. 7, when the upper limit time has not elapsed until the end Pc has elapsed since the start of measurement (S37: YES), the measurement is forced at time t4 when the upper limit time is reached. And the pressure drop amount ΔPa generated from the time t2 to the time t4 of the measurement start is stored (S38). Note that the above steps S34 to S38 correspond to "stop time acquisition means".

  In the subsequent step S39, these measured values ΔTa and ΔPa (the descent value at stop) are corrected based on the fuel temperature. That is, since the map shown in FIG. 4 changes according to the fuel temperature, the temperature change is corrected. In the subsequent step S40, the fuel consumption amount Qa (that is, the static leak amount) is calculated based on the measured values ΔTa and ΔPa after temperature correction using the map of FIG. From the above, the amount of static leak is estimated.

  Next, the subroutine processing in step S15 shown in FIG. 5 will be described with reference to FIG. First, in step S50 of FIG. 8, when measuring the drop time ΔTb and the drop amount ΔPb for each of the fuel injection valves 10 of each cylinder, it is determined whether or not the current measurement is the first cylinder. If it is the first cylinder (S50: YES), it waits until it becomes the state of no deceleration deceleration in the following step S51. If it is in the state of no deceleration deceleration injection (S51: YES), in the following step S52, it is determined whether or not a single injection condition exemplified below is satisfied.

  That is, a predetermined delay time has elapsed since the deceleration-no-injection state, the rail pressure (actual Pc) is a predetermined pressure (start Pc), and the operating state of the internal combustion engine is greatly affected by the single injection. A single injection condition is that there is no state (for example, the EGR amount is less than a predetermined value and the vehicle speed is less than a predetermined value).

  If the single injection condition is satisfied (S52: YES), single injection is performed in which a predetermined minute amount of fuel is injected once from the fuel injection valve 10 corresponding to the cylinder determined in step S50 ( S53). In step S54, the above-described measurement of the drop time ΔTb is started.

  Thereafter, when the actual Pc drops to a predetermined pressure (end Pc) (S55: YES), the measurement of the descent time ΔTb is ended when the actual Pc = end Pc, and the measured time, that is, from the start Pc to the end Pc. The descent time ΔTb required until this time is stored (S56). However, if the upper limit time has not elapsed until the end Pc has elapsed since the start of measurement (S57: YES), the measurement is forcibly terminated when the upper limit time is reached, and the measurement is forcibly terminated. The pressure drop amount ΔPb generated until then is stored (S58). The above steps S54 to S58 correspond to “operation time acquisition means”.

  In the subsequent step S59, these measured values ΔTb and ΔPb (actuation drop values) are corrected based on the fuel temperature. In the subsequent step S60, the fuel consumption Qb is calculated based on the measured values ΔTb and ΔPb after temperature correction, using the map of FIG. Then, the previously calculated consumption amount Qa at the time of stoppage and the single injection amount (a minute amount) are subtracted from the consumption amount Qb at the time of operation calculated this time. The value obtained by this subtraction corresponds to the estimated value of the dynamic leak amount.

  As described above, according to the present embodiment, the amount of static leak and the amount of dynamic leak can be accurately estimated by the processes of FIGS. Then, when both of the estimated leak amounts are abnormal values, it is determined that the fuel property is poor (S21). Therefore, it is possible to accurately diagnose a fuel property defect without requiring an alcohol concentration sensor or the like that directly detects the fuel property.

  Further, if the estimated static leak amount is an abnormal value and the dynamic leak amount is a normal value, it is determined that the portion (sliding surfaces 20a, 20b) of the fuel injection valve 10 where static leak occurs is an abnormality occurrence location ( S22). On the contrary, if the estimated static leak amount is a normal value and the dynamic leak amount is an abnormal value, it is determined that the portion of the fuel injection valve 10 that dynamically leaks (outflow orifice 24b, seat surface 22a) is an abnormality occurrence location. (S23). Therefore, since the location where the fuel injection valve 10 is abnormal can be diagnosed, it is possible to urge the operator who repairs the fuel injection valve 10 to avoid replacing parts where no abnormality has occurred.

  In addition, the content of fail-safe control, such as limiting the output of the internal combustion engine, can be changed according to the presence or absence of fuel property failure and the location of the abnormality, making it easy to implement fail-safe control suitable for abnormal conditions it can.

  Furthermore, according to this embodiment, the effects listed below are also exhibited.

  (1) In the injection stop state, the amount of decrease ΔPa in which the fuel pressure naturally drops in a predetermined time, or the amount of time ΔTa required for the fuel pressure to naturally drop by a predetermined amount, is measured as a stop-time drop value.

  Since the drop values ΔPa and ΔTa at the time of stop and the static leak amount are highly correlated, according to the present embodiment for estimating the static leak amount based on the measured stop drop values ΔPa and ΔTa, the static leak amount is highly accurate. Can be estimated. In addition, since the measurement is performed at the time of no deceleration injection, the correlation can be further increased, and the estimation accuracy can be improved.

  (2) In the state in which the fuel pressure is lowered due to the occurrence of dynamic leak from the outflow orifice 24b and the seat surface 22a due to the injection operation, the amount of decrease ΔPb in which the fuel pressure drops in a predetermined time, or the fuel pressure Is measured as the descent value during operation.

  Since these operating drop values ΔPb, ΔTb and fuel consumption Qb (static leak amount + dynamic leak + injection amount) are highly correlated, the fuel consumption amount Qb is estimated based on the measured stop drop values ΔPb, ΔTb. According to the present embodiment, the fuel consumption Qb can be estimated with high accuracy. Furthermore, since the value (subtracted value) obtained by subtracting the static leak amount Qb and the minute injection amount from the fuel consumption amount Qb calculated in this way is estimated as the dynamic leak amount, the dynamic leak amount can be determined with high accuracy. Can be estimated. In addition, when the injection is stopped, a predetermined amount (a minute amount) of fuel is injected, and the operating drop values ΔPb and ΔTb are measured during the period in which the pressure drops with the injection, so that the correlation can be further enhanced. The accuracy of the estimation can be improved.

  (3) Here, as shown in FIG. 9, the lower the rail pressure at the time of the leak, the smaller the static leak amount and the dynamic leak amount, but the ratio of the static leak amount to the total amount of both leak amounts becomes smaller. Therefore, if the amount of dynamic leak is estimated by the difference between the drop values ΔPa, ΔTa, ΔPb, and ΔTb measured when the rail pressure is low (difference between the consumption amounts Qa and Qb), the estimation accuracy deteriorates.

  In view of this point, in the present embodiment, the stop time acquisition means S34 to S38 and the operation time acquisition means S54 to S58 are based on the condition that the pressure is equal to or higher than a predetermined pressure, and the stop time drop values ΔPa and ΔTa and the operation time drop. Measurement of values ΔPb and ΔTb is started. Therefore, the above-described deterioration in estimation accuracy can be avoided. For example, if the predetermined pressure is set to a value (100 MPa in the example of FIG. 9) at which the amount of static leak is equal to or greater than the amount of dynamic leak, the above-described deterioration in estimation accuracy can be sufficiently avoided.

  (4) When the stop time acquisition means S34 to S38 and the operation time acquisition means S54 to S58 measure the stop time drop values ΔPa and ΔTa and the operation drop values ΔPb and ΔTb, the rail pressure drop amount reaches the limit amount. At this point, the measurement is terminated, and the time ΔTa and ΔTb required for the pressure drop by the limit amount are set as the drop value at stop and the drop value at operation. Note that the limit amount corresponds to the difference amount between the start Pc and the end Pc in the examples of FIGS. 6 and 8, and corresponds to ΔPa in the example of FIG.

  Here, when the viscosity of the fuel is abnormally low, the static leak amount and the dynamic leak amount are abnormally increased, so that the rail pressure rapidly decreases in a short time. In this case, if an attempt is made to measure the pressure drop amounts ΔPa and ΔPb that have occurred from the start of measurement until the predetermined time has elapsed, the diagnosis will wait until the pressure drops more than necessary, and the diagnosis of fuel property abnormality is delayed. , Fail-safe control starts slowly.

  In view of this point, in the present embodiment, as described above, the measurement is terminated when the rail pressure drop amount reaches the limit amount, and the times ΔTa and ΔTb required for the pressure drop by the limit amount are reduced at the stop time. Value and operating drop value for diagnosis. Therefore, it is possible to avoid waiting for diagnosis until the pressure drops more than necessary, to quickly obtain a diagnosis result of fuel property abnormality, and to suppress the start of fail-safe control from being delayed.

  (5) When the stop time acquisition means S34 to S38 and the operation time acquisition means S54 to S58 measure the stop time drop values ΔPa and ΔTa and the operation time drop values ΔPb and ΔTb, the measurement time reaches the time limit. The measurement is terminated, and the pressure drop amounts ΔPa and ΔPb generated during the time limit are set as a drop value at stop and a drop value at operation. The time limit corresponds to upper limit times t2 to t4 in the examples of FIGS.

  Here, when the viscosity of the fuel is abnormally high, the static leak amount and the dynamic leak amount are abnormally reduced, so that the rail pressure decreasing speed is abnormally slow. In this case, if it is attempted to measure the time ΔTa required for the pressure to drop by a predetermined amount, the measurement time becomes longer than necessary, the diagnosis of the fuel property abnormality is delayed, and the start of fail-safe control is delayed.

  In this embodiment in view of this point, as described above, the measurement is terminated when the measurement time reaches the time limit, and the pressure drop amounts ΔPa and ΔPb generated during the time limit are determined as the drop value during stop and the drop value during operation. Used for diagnosis. Therefore, it is possible to avoid an unnecessarily long measurement time, to quickly obtain a diagnosis result of fuel property abnormality, and to suppress the start of fail-safe control from being delayed.

  (6) Here, in the initial state of the internal combustion engine, since the aging deterioration rate such as wear in each part of the fuel injection valve 10 is fast, it is desirable to increase the diagnosis frequency of the abnormality occurrence part. In the above embodiment in view of this point, as shown in steps S10 and S11 of FIG. 5, when the internal combustion engine is not in the initial state, diagnosis is performed every time the vehicle travels a predetermined distance, whereas in the initial state. Diagnosis is performed even if the vehicle is not traveling a predetermined distance. In the example of FIG. 5, the diagnosis is performed every time a trigger for executing the process of FIG. 5 occurs. Therefore, the diagnosis frequency in the initial state is increased, and it can be quickly detected that an abnormality has occurred.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  In the above embodiment, the acquired values by the stop time acquisition means and the operation time acquisition means are the pressure drop amounts ΔPa and ΔPb or the drop times ΔTa and ΔTb, but the slope of the pressure drop may be the acquired value.

  In the initial state of the internal combustion engine, the aging deterioration rate of the fuel injection valve 10 is fast as described above. In view of this point, the amount of static leak depends on the travel distance of the vehicle, the operation time of the internal combustion engine, etc. Further, the upper limit value and the lower limit value of the normal range may be variably set as threshold values used in the dynamic leak amount abnormality determination (S13, S16).

  In the above embodiment, both the determination of the abnormality occurrence point and the fuel property determination are performed based on the estimated values of the static leak amount and the dynamic leak amount, but either one of the determinations may be abolished.

  In the above embodiment, the sensor 13 installed in the pressure accumulating vessel 12 is used to detect the pressure used to determine the location of the abnormality and the fuel property determination (pressure of fuel supplied to the fuel injection valve 10). The installation position of the sensor 13 is not limited to the pressure accumulating vessel 12, and for example, a fuel pressure sensor installed in the fuel injection valve 10 or a fuel pressure installed in a high-pressure pipe that supplies fuel from the pressure accumulating vessel 12 to the fuel injection valve 10. It may be a sensor.

  S12 ... Static leak amount estimating means, S15 ... Dynamic leak amount estimating means, S18, S19, S22 ... Static leak abnormality determining means (abnormal cause determining means), S18, S20, S23 ... Dynamic leak abnormality determining means (abnormal cause determining means) ), S18, S19, S21... Fuel property determining means (abnormal cause determining means).

Claims (7)

Static leak amount estimation means (S12) for estimating the amount of fuel leak occurring inside the fuel injection valve (10) of the internal combustion engine, which is generated when the fuel injection valve is not in an injection operation and is stopped when the injection is stopped; ,
Dynamic leak amount estimation means (S15) for estimating the amount of fuel leak occurring inside the fuel injection valve, which is caused by the injection operation of the fuel injection valve;
Based on the estimated amount of static leak and the amount of dynamic leak, an abnormality cause determination means (S18, which performs at least one of determination of whether or not the fuel has poor properties and determination of an abnormality occurrence location of the fuel injection valve) S19, S20, S21, S22, S23),
A fuel pressure sensor (13) for detecting the pressure of fuel supplied to the fuel injection valve;
In the state where the injection is stopped, the amount of decrease (ΔPa) in which the pressure naturally decreases in a predetermined time, or the amount of time in which the pressure naturally decreases by a predetermined amount (ΔTa) is acquired as a decrease value at the time of stop. Stop time acquisition means (S34 to S38),
In a state in which the pressure is lowered due to the injection operation, a drop amount (ΔPb) in which the pressure drops in a predetermined time or a drop time (ΔTb) required for the pressure to drop by a predetermined amount is An operation time acquisition means (S54 to S58) for acquiring a drop value;
With
The static leak amount estimation means estimates the static leak amount based on the descent value at the time of stop,
The dynamic leak amount estimating means estimates the dynamic leak amount based on a difference between the operating drop value and the stop drop value,
The stop time acquisition means and the operation time acquisition means start measuring the stop time drop value and the operation drop value on condition that the pressure is equal to or higher than a predetermined pressure,
The abnormality diagnosis apparatus , wherein the predetermined pressure is set to a value at which the amount of static leak is equal to or greater than the amount of dynamic leak . The abnormality cause determination means includes
Fuel property determination means (S18, S19, S21) for determining that the fuel is defective in property when both the static leak amount and the dynamic leak amount are abnormal values exceeding the normal range. The abnormality diagnosis apparatus according to claim 1. The abnormality cause determination means includes
When the static leak amount is an abnormal value exceeding the normal range and the dynamic leak amount is a normal value within the normal range, the portion where the static leak occurs in the fuel injection valve is an abnormality occurrence location. The abnormality diagnosis apparatus according to claim 1 or 2, further comprising a static leak abnormality determination unit (S18, S19, S22). The abnormality cause determination means includes
When the dynamic leak amount is an abnormal value exceeding the normal range and the static leak amount is a normal value within the normal range, a portion where the dynamic leak occurs in the fuel injection valve is an abnormality occurrence location. The abnormality diagnosis apparatus according to any one of claims 1 to 3, further comprising dynamic leak abnormality determination means (S18, S20, S23) for determining The operation time acquisition means injects a predetermined amount of fuel when the injection is stopped, and acquires the operation decrease value during a period in which the pressure is reduced due to the injection . 5. The abnormality diagnosis device according to any one of 4 above. The stop time acquisition means and the operation time acquisition means, when measuring the stop time drop value and the operation drop value, terminate the measurement when the pressure drop amount reaches a limit amount, The abnormality diagnosis device according to any one of claims 1 to 5, wherein a time required for the pressure drop by an amount is set as the drop value at the time of stop and the drop value at the time of operation . When the stop time acquisition means and the operation time acquisition means measure the stop time drop value and the operation time drop value, the measurement time ends when the measurement time reaches the time limit, and occurs at the time limit. abnormality diagnosis apparatus according to any one of claims 1 to 6 a pressure drop, characterized in that said stop drop values and the operating time of descent value.

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