JP7006344B2 - Control device - Google Patents

Description

The present invention relates to a control device applied to a fuel injection device that injects fuel into a cylinder of an engine.

Conventionally, there is a control device applied to a fuel injection device that detects an abnormality of a fuel leak in a fuel injection valve (for example, Patent Document 1).

The types of fuel leak include dynamic leak and static leak, and the control device described in Patent Document 1 focuses on the abnormality of the static leak and detects the abnormality. The dynamic leak is a fuel leak that goes out to the fuel pipe on the low pressure side of the fuel injection valve when the fuel is injected by the fuel injection valve (injector). On the other hand, a static leak is a fuel leak that constantly exits from a gap such as a sliding portion of the fuel injection valve to the fuel pipe on the low pressure side regardless of the fuel injection by the fuel injection valve.

In the control device described in Patent Document 1, after the engine is stopped, the residual pressure drop tendency in the common rail is detected, and the residual pressure drop tendency is compared with the determination criteria to determine whether or not there is an abnormality in static leakage. Is judged.

Japanese Unexamined Patent Publication No. 2010-216279

By the way, in Patent Document 1, the determination standard is constant regardless of the state of the fuel injection valve, although the temperature may be corrected. However, there are individual differences in the fuel injection valve, and the amount of static leakage may differ depending on the individual differences. Therefore, even if there is a sign of abnormality in the amount of static leakage, it may not be possible to properly determine it.

For example, if the amount of static leakage increases sharply, it can be said that there is a sign of abnormality. However, depending on individual differences, the amount of static leakage in the initial state (appropriate state) may be large or small. Therefore, when the amount of static leakage in the initial state is small, unlike the case where the amount of static leakage is large, even if the amount of static leakage suddenly increases, it may be below the judgment standard and the sign of abnormality may not be appropriately determined.

The present invention has been made in view of the above circumstances, and a main object thereof is to provide a control device for appropriately detecting a leak abnormality regardless of individual differences in fuel injection valves.

The first means for solving the above problems is a fuel pump that increases the pressure of the fuel in the fuel tank and discharges the fuel, a common rail that stores the fuel discharged from the fuel pump, and the fuel stored in the common rail into the cylinder of the engine. In a control device applied to a fuel injection device including a fuel injection valve for injecting fuel and a fuel pressure sensor for detecting fuel pressure in the common rail, fuel injection is stopped and from the fuel pump. A leak amount calculation unit that calculates a static leak amount, which is a fuel leak amount from the fuel injection valve in a stationary state in which fuel is not discharged, based on a fuel pressure detection value by the fuel pressure sensor, and a history of the static leak amount. A storage unit that stores fuel, a threshold setting unit that sets an abnormality determination threshold based on the history of the static leak amount stored by the storage unit, and the static leak amount and the abnormality determination calculated by the leak amount calculation unit. It is provided with an abnormality determination unit for determining the presence or absence of an abnormality based on the result of comparison with a threshold value.

According to the above configuration, an abnormality determination threshold value is set according to the past history of the static leakage amount, and the abnormality determination threshold value is compared with the current static leakage amount calculated by the leak amount calculation unit to determine an abnormality. do. As a result, even if there are individual differences in the fuel injection valve, the abnormality determination threshold is set according to the past history of the static leakage amount, so that the abnormality determination threshold is set to reflect the individual differences in the fuel injection valve. The Rukoto. For example, when the amount of static leakage is large due to individual differences, the abnormality determination threshold is also large, and when the amount of static leakage is small due to individual differences, the abnormality determination threshold is also small. Therefore, even when a sign of abnormality such as a sudden increase in the amount of static leakage occurs, the sign can be determined in advance without being affected by individual differences. That is, it is possible to appropriately detect a leak abnormality in the fuel injection valve.

In the second means, the storage unit stores an initial history indicating the static leak amount when the fuel injection valve is in the initial state as the history of the static leak amount, and the threshold setting unit stores the initial history. The abnormality determination threshold value is set with reference to.

Individual differences in the fuel injection valve are reflected in the amount of static leakage in the initial state. Therefore, by setting the abnormality determination threshold value according to the initial history when the fuel injection valve is in the initial state, it is possible to determine the sign of abnormality without being affected by individual differences.

The third means includes a deterioration amount specifying unit that specifies the deterioration leak amount based on the deterioration over time of the fuel injection valve based on the initial history, and the threshold value setting unit is the deterioration specified by the deterioration amount specifying unit. The abnormality determination threshold is set based on the leak amount and the initial history.

It is known that the amount of static leakage of a fuel injection valve increases as it deteriorates over time. Therefore, when determining the abnormality, it is necessary to consider the increase in the amount of static leakage due to deterioration over time. By the way, it is empirically known that there are individual differences in the amount of deterioration leak due to deterioration over time, and that the amount of deterioration leak can be predicted based on the amount of static leakage in the initial state.

Therefore, a deterioration amount specifying unit that specifies the deterioration leak amount according to the initial history is provided, and the threshold value setting unit sets an abnormality determination threshold value based on the deterioration leak amount and the initial history specified by the deterioration amount specifying unit. I decided. As a result, even if there are individual differences in the fuel injection valve, it is possible to determine an abnormality by appropriately considering the increase in the amount of static leakage due to deterioration over time.

In the fourth means, the storage unit stores a plurality of static leak amounts in time series as a history of the static leak amount, and the threshold setting unit is based on the plurality of static leak amounts stored in time series. , The abnormality determination threshold value is set.

From a plurality of static leak amounts stored in time series, it is possible to predict the tendency of how the static leak amount changes. And if it is the amount of static leakage detected from the same fuel injection valve, it is not necessary to consider individual differences. That is, since individual differences are reflected in the past history, the threshold setting unit sets the abnormality determination threshold based on the tendency that can be grasped from the plurality of static leak amounts stored in the time series, thereby making the individual differences. Regardless, the abnormality can be appropriately determined. That is, even when a sign of abnormality occurs such that the amount of static leakage suddenly increases, the sign of abnormality can be appropriately determined without being affected by individual differences.

In the fifth means, the abnormality determination threshold value is set based on a plurality of static leak amounts stored in time series after a predetermined period of time has elapsed from the start of use of the fuel injection valve, and the predetermined period is set. , The period from the start of use of the fuel injection valve until the static leakage amount increases and then converges is defined.

The amount of static leakage of the fuel injection valve tends to increase after the start of use until the initial wear of the sliding member of the fuel injection valve is completed. On the other hand, the amount of static leakage converges within a predetermined range after the initial wear is completed. Therefore, if the tendency is predicted based on the history before the initial wear is completed, erroneous determination is likely to occur. Therefore, it was decided to set the abnormality determination threshold value based on the history after the static leakage amount has converged, that is, after the initial wear is completed. As a result, even when the static leakage amount suddenly increases due to the initial wear, it is possible to prevent erroneous determination that an abnormality has occurred.

The sixth means includes a temperature sensor that detects the fuel temperature in the common rail, and the leak amount calculation unit corrects the static leak amount based on the fuel temperature detected by the temperature sensor.

The amount of static leakage changes depending on the difference in fuel temperature. Therefore, the leak amount calculation unit decides to correct the static leak amount based on the fuel temperature. As a result, the abnormality can be appropriately determined.

In the seventh means, the leak amount calculation unit acquires the tendency of decrease in fuel pressure when the fuel pressure detected by the fuel pressure sensor is within a predetermined pressure range, and the static leak is based on the tendency of decrease in fuel pressure. The amount is calculated, and the leak amount calculation unit corrects the static leak amount based on the fuel pressure detected immediately after the transition to the stationary state.

When the fuel pressure immediately after the transition to the rest state is high, the fuel pressure tends to decrease as compared with the case where the fuel pressure is low. Therefore, when calculating the static leakage amount based on the decreasing tendency of the fuel pressure, an error may occur due to the difference in the fuel pressure. Therefore, the leak amount calculation unit decides to correct the static leak amount based on the fuel pressure detected immediately after the transition to the stationary state. As a result, the abnormality can be appropriately determined.

Schematic block diagram of the fuel injection system. Conventionally, the figure which shows the state of the static leakage amount at the time of an abnormality. The figure which shows the change of the fuel pressure in a rest state. The figure which shows the change of the static leakage amount with aging deterioration. The figure which shows the relationship between the initial history and the amount of static leakage. A flowchart showing the flow of abnormality determination processing. The figure which shows the change of the static leakage amount with aging deterioration. The flowchart which shows the flow of abnormality determination processing in 2nd Embodiment.

(First Embodiment)
Hereinafter, the control device applied to the fuel injection device according to the present invention will be described with reference to the drawings. The fuel injection device is, for example, a common rail type fuel injection system that injects fuel into a 4-cylinder diesel engine, and its operation is controlled by a control device. FIG. 1 is a block diagram showing an outline of a fuel injection system. In FIG. 1, the fuel injection system includes a fuel tank 10, a fuel pump 11, a common rail 20, a fuel pressure sensor 21, an injector 23 as a fuel injection valve, a pressure limiter 30, and an ECU 50. ing.

The fuel pump 11 is connected to the fuel tank 10 through a fuel pipe 12 provided with a fuel filter 13. The fuel pump 11 sucks the low-pressure fuel before pressurization pumped from the fuel tank 10 into a fuel pressurizing chamber (not shown). Then, as the plunger reciprocates in synchronization with the engine rotation, the high-pressure fuel that has been increased in pressure is discharged (pressure-fed) in the fuel pressurizing chamber. For example, the fuel pump 11 is a mechanical pump that is driven as the engine rotates and repeatedly sucks and discharges fuel. An electromagnetically driven suction metering valve (SCV) 14 is provided in the fuel suction portion of the fuel pump 11.

The suction metering valve 14 is provided on the suction side of the fuel pump 11, and adjusts the amount of fuel sucked by the fuel pump 11 in the suction step by controlling the current. For example, as the current control, the duty ratio control of the current with respect to the suction metering valve 14 is performed. By controlling the fuel intake amount by the suction adjustment valve 14, the fuel discharge amount from the fuel pump 11 is adjusted.

For example, when a normally open valve held in the open state (fully open state) of the electromagnetic solenoid is used as the suction metering valve 14, the opening area of the fuel suction passage is increased by increasing the indicated current value to the electromagnetic solenoid. When it is reduced, the fuel intake amount of the fuel pump 11 is reduced, and as a result, the fuel discharge amount by the fuel pump 11 is reduced. It is also possible to use a solenoid valve that is a normally closed valve for the suction metering valve 14.

Further, a common rail 20 is connected to the fuel pump 11 via a fuel discharge pipe 18. The high-pressure fuel discharged from the fuel pump 11 is sequentially fed to the common rail 20 through the fuel discharge pipe 18, whereby the fuel in the common rail 20 is held (accumulated) in a high-pressure state.

The common rail 20 is provided with a rail pressure sensor (hereinafter referred to as a fuel pressure sensor 21) for detecting the fuel pressure Pc in the common rail 20. In FIG. 1, the fuel pressure sensor 21 is provided on the fuel outlet side of the fuel pump 11 in the common rail 20, but the fuel pressure sensor 21 is provided on the path from the fuel outlet of the fuel pump 11 to the injection port of the injector 23 described later. Can be done.

The common rail 20 is provided with a temperature sensor 22 that detects the fuel temperature in the fuel tank 10. The temperature sensor 22 is not limited to the fuel tank 10, and may be provided at any location in the fuel pump 11 or the common rail 20.

The injector 23 is a well-known electromagnetically driven injection valve provided with a nozzle needle for opening and closing the injection hole, and is provided for each cylinder of the engine. High-pressure fuel is supplied to the injector 23 from the common rail 20 through the high-pressure fuel pipe 24, and fuel is injected and supplied into each cylinder of the engine by driving the injector 23. However, a part of the high-pressure fuel supplied to the injector 23 is returned to the fuel tank 10 through the return pipe 25 due to a leak. The amount of fuel returned to the fuel tank 10 due to a leak is called a fuel leak amount. Further, as the injector 23, it is also possible to use a piezo-driven injector instead of the electromagnetically driven injector.

Further, the common rail 20 is provided with a normally closed pressure limiter 30 as a pressure release valve. The pressure limiter 30 basically has a mechanical check valve (check valve) structure, and when the rail pressure, which is the fuel pressure in the common rail, rises excessively and exceeds the valve opening pressure of the pressure limiter 30. Open the valve. When the pressure limiter 30 opens, the high-pressure fuel is returned to the fuel tank 10 through the return pipe 25, and the rail pressure is reduced. As a result, damage to high-pressure parts such as high-pressure piping and common rail 20 is suppressed.

The ECU 50 is an electronic control device including a well-known microcomputer including a CPU, ROM, RAM, flash memory, and the like. The ECU 50 has signals from various sensors such as a fuel pressure sensor 21, a rotation speed sensor 56 for detecting the rotation speed of the engine, an accelerator sensor 57 for detecting the accelerator operation amount, and a water temperature sensor 58 for detecting the temperature of the engine cooling water. Is taken in to detect the engine operating state. Then, the operating state of the engine is controlled by executing the control program or the like stored in the ROM or the like.

Specifically, the ECU 50 performs feedback control of the common rail pressure. That is, the ECU 50 calculates the target fuel pressure of the common rail pressure based on the engine operating state. The target fuel pressure is set to a relatively low value when the engine is in a low load state such as when the engine is idle, and to a relatively high value when the engine is in a high load state such as when the engine is in a full load state. Then, the drive current for driving the suction metering valve 14 is feedback-controlled based on the deviation between the detected value of the fuel pressure Pc and the target fuel pressure so that the detected value of the fuel pressure Pc by the fuel pressure sensor 21 matches the target fuel pressure.

Further, the ECU 50 controls the energization of the injector 23 based on the engine operating state. That is, the fuel injection amount, that is, the indicated injection amount is set according to the operating state of the engine, and the energization time of the injector 23 based on the indicated injection amount is calculated based on the fuel pressure Pc detected by the fuel pressure sensor 21. Control is performed to drive the injector 23 according to the energization time.

As described above, the fuel discharge amount and the fuel injection amount are obtained based on the detected values of the fuel pressure Pc. However, as described above, a fuel leak occurs in the injector 23. The types of fuel leaks include dynamic leaks and static leaks, and if the amount of both leaks is large, it adversely affects fuel injection control. Further, if the amount of leakage is large, it is necessary to increase the fuel pressure Pc by utilizing the engine output, so that the fuel consumption is also deteriorated. Therefore, it is necessary to determine whether or not the leak amount is normal.

The dynamic leak is a fuel leak that goes out to the return pipe 25 at the time of fuel injection by the injector 23. On the other hand, the static leak is a fuel leak that constantly exits from the gap of the sliding portion of the injector 23 to the return pipe 25 regardless of the fuel injection by the injector 23.

By the way, as shown in FIG. 2, when the static leak amount SL suddenly increases, it can be said that there is a sign of abnormality. However, there are individual differences in the injector 23, and the static leak amount SL in an appropriate state (state in which there is no abnormality) may differ depending on the individual differences. That is, depending on individual differences, there are cases where the static leak amount SL in the proper state is large (indicated by a solid line in FIG. 2) and cases where it is small (indicated by a broken line in FIG. 2). Therefore, when the static leak amount SL in the proper state is small, unlike the case where the static leak amount SL is large, even if the static leak amount SL suddenly increases, it may be below the threshold value and the sign of abnormality may not be appropriately determined. In FIG. 2, the threshold value is shown by a alternate long and short dash line.

Therefore, in the present embodiment, the ECU 50 is provided with the following functions so that the abnormality can be appropriately determined regardless of the individual difference of the injector 23. The functions thereof will be described in detail below.

The ECU 50 includes a leak amount calculation unit 51 for calculating the static leak amount SL, a storage unit 52 for storing the history of the static leak amount SL, a threshold value setting unit 53 for setting the abnormality determination threshold value Th, and an abnormality in the static leak amount SL. It has a function as an abnormality determination unit 54 for determining the presence or absence of. Various functions of these functions are realized by executing a program stored in the storage device 55 (for example, a storage memory) included in the ECU 50. The various functions may be realized by electronic circuits that are hardware, or at least a part of them may be realized by software, that is, processing executed on a computer.

The ECU 50 as the leak amount calculation unit 51 is a static leak amount SL which is a fuel leak amount from the injector 23 in a stationary state in which fuel injection is stopped and fuel is not discharged from the fuel pump 11. Is calculated based on the detected value of the fuel pressure Pc by the fuel pressure sensor 21.

The stationary state is, for example, a case where the fuel injection amount (or the indicated injection amount) is zero (or near zero), and the fuel discharge amount (or fuel intake amount) is zero (or near zero). That is. That is, a state in which fuel injection control is not performed and fuel discharge control is not performed from the fuel pump 11 corresponds to a stationary state.

The method of calculating the static leak amount SL will be specifically described. The ECU 50 acquires the fuel pressure Pc detected from the fuel pressure sensor 21 in the above-mentioned rest state. Then, when the fuel pressure Pc detected by the fuel pressure sensor 21 is within a predetermined pressure range, the ECU 50 acquires a decreasing tendency (inclination) of the fuel pressure Pc, and based on the decreasing tendency of the fuel pressure Pc, the static leakage amount SL Is calculated.

For example, the ECU 50 measures the time from when the detected fuel pressure Pc becomes a predetermined first pressure value Pc1 or less until it becomes a predetermined second pressure value Pc2 (<first pressure value Pc1). Then, the ECU 50 obtains a decreasing tendency (dPc / dt) of the fuel pressure Pc by dividing the value obtained by subtracting the second pressure value Pc2 from the first pressure value Pc1 by the measurement time T (see formula (1)). ).
dPc / dt = (Pc1-Pc2) / T ... (1)

Then, the ECU 50 obtains the static leakage amount SL by multiplying the decreasing tendency of the fuel pressure Pc (dPc / dt) by the rail volume V and dividing the multiplied value by the bulk modulus K (formula (formula (formula)). 2)). The rail volume V is the sum of the capacity in the common rail 20, the capacity in the fuel discharge pipe 18, and the volume in the injector 23. Further, the bulk modulus K is predetermined depending on the type of fuel. The rail volume V and the bulk modulus K are stored in the storage device 55 in advance.
SL = (dPc / dt) × V / K ... (2)

By the way, since the viscosity of the fuel changes depending on the difference in the fuel temperature, the static leakage amount SL increases or decreases depending on the difference in the fuel temperature. That is, when the fuel temperature is high, the static leak amount SL tends to be large, and when the fuel temperature is low, the static leak amount SL tends to be small.

Therefore, the ECU 50 corrects the static leakage amount SL based on the fuel temperature detected by the temperature sensor 22. Specifically, the ECU 50 corrects the calculated static leak amount SL based on the fuel temperature, and calculates (estimates) the static leak amount SL at a predetermined reference temperature.

For example, the ECU 50 corrects the static leak amount SL to be lower when the detected fuel temperature is higher than the reference temperature, and increases the static leak amount SL when the fuel temperature is lower than the reference temperature. Correct to do. As the correction method, the temperature correction value may be increased or decreased according to the fuel temperature, or the temperature correction value may be multiplied. The temperature correction value may be configured to be calculated by map calculation with the fuel temperature as an argument.

Similarly, the static leak amount SL increases or decreases depending on the difference in the fuel pressure Pc immediately after the transition to the stationary state (time point T0 in FIG. 3). For example, as shown in FIG. 3, when the fuel pressure Pc immediately after the transition to the rest state is high (indicated by a solid line) and low (indicated by a broken line), the fuel pressure Pc is more likely to decrease. That is, in FIG. 3, the measurement time T2 when the fuel pressure Pc immediately after the transition to the rest state is high is shorter than the measurement time T1 when the fuel pressure Pc is low.

Therefore, the ECU 50 corrects the static leakage amount SL based on the fuel pressure Pc detected immediately after the transition to the stationary state. Specifically, the ECU 50 corrects the calculated static leak amount SL based on the fuel pressure Pc detected immediately after the transition to the stationary state, and calculates (estimates) the static leak amount SL at a predetermined reference fuel pressure. )do.

For example, the ECU 50 corrects the static leakage amount SL to be low when the fuel pressure Pc detected immediately after the transition to the stationary state is higher than the reference fuel pressure, and when the fuel pressure Pc immediately after the transition to the stationary state is low, the ECU 50 is static. Correct to increase the leak amount SL. As a correction method, the fuel pressure correction value may be increased or decreased according to the detected fuel pressure Pc, or the fuel pressure correction value may be multiplied. The fuel correction value may be configured to be calculated by a map calculation with the fuel pressure Pc detected immediately after the transition to the stationary state as an argument.

The ECU 50 as the storage unit 52 stores the calculated static leakage amount SL as a history in the storage device 55. At that time, the cumulative usage time AT after the injector 23 is started to be used is also stored (associated). The cumulative usage time AT is measured by the ECU 50 and stored in the storage device 55 while the injector 23 is in use. The period in which the injector 23 is in use is, for example, a period in which the ignition switch is on or a period in which the engine is in operation.

In the first embodiment, if the ECU 50 stores at least the initial history SL1 indicating the static leak amount SL when the injector 23 is in the initial state as the history of the static leak amount SL, the subsequent static leak amount. It is not necessary to memorize SL. The initial state is a state in which the cumulative usage time AT is within a predetermined time, for example, a state in which the cumulative usage time AT is about zero to 24 hours. The state until the initial wear of the sliding members and the like constituting the injector 23 is completed may be set as the initial state. Further, it is desirable that the initial history SL1 is the first stored history of the static leak amount SL of the injector 23 in the initial state.

The ECU 50 as the threshold value setting unit 53 sets the abnormality determination threshold value Th based on the history of the static leakage amount SL stored in the storage device 55. By the way, there are individual differences in the injector 23, and the static leakage amount SL may differ even in the initial state. Therefore, if the abnormality determination threshold value Th is made uniform, the abnormality may not be appropriately determined. Therefore, the ECU 50 sets the abnormality determination threshold value Th with reference to the initial history SL1.

Further, as shown in FIG. 4, the static leakage amount SL of the injector 23 increases as the injector 23 deteriorates with time. That is, the static leak amount SL increases according to the cumulative usage time AT. Therefore, when setting the abnormality determination threshold value Th, it is necessary to consider the deterioration leak amount DL, which is the increase in the static leak amount SL due to the deterioration over time. In FIG. 4, the deterioration leak amount DL is an increase in the static leak amount SL from the initial history SL1 shown by the broken line.

By the way, it is empirically known that there are individual differences in the deterioration leak amount DL. It is also empirically known that the deterioration leak amount DL can be predicted based on the static leak amount SL (that is, the initial history SL1) in the initial state. Specifically, as shown in FIG. 5, the deterioration leak amount DL changes according to the initial history SL1.

Therefore, the ECU 50 acquires a matching map (map data) capable of specifying the deterioration leak amount DL by experiments or the like, using the cumulative usage time AT of the injector 23 and the initial history SL1 as arguments, and stores it in the storage device 55. There is. Based on the conformity map stored in the storage device 55, the ECU 50 specifies the deterioration leak amount DL with the cumulative usage time AT and the initial history SL1 as arguments by map calculation. Therefore, the ECU 50 has a function as a deterioration amount specifying unit 59.

Then, the ECU 50 sets the abnormality determination threshold value Th by adding up the initial history SL1, the deterioration leak amount DL, and the predetermined value M1 as a margin. The predetermined value M1 is a predetermined constant value, but may be changed depending on the state of the fuel. For example, it may be changed depending on the fuel temperature or the fuel pressure Pc detected immediately after the transition to the stationary state.

The ECU 50 as the abnormality determination unit 54 determines the presence or absence of an abnormality based on the result of comparison between the static leak amount SL calculated by the leak amount calculation unit 51 and the abnormality determination threshold value Th set by the threshold value setting unit 53. do. That is, when the static leak amount SL is larger than the abnormality determination threshold value Th, the ECU 50 determines that the static leak amount SL has an abnormality (or a sign of an abnormality).

Next, the flow of the abnormality determination process will be described with reference to FIG. The abnormality determination process is executed by the ECU 50 at predetermined intervals.

First, the ECU 50 determines whether or not the fuel injection is stopped and the fuel is not discharged from the fuel pump 11 in a stationary state (step S101). If it is not in a stationary state (step S101: NO), the ECU 50 ends the abnormality determination process.

When in the stationary state (step S101: YES), the ECU 50 acquires the fuel pressure Pc (step S102). Then, the ECU 50 acquires a decreasing tendency of the fuel pressure Pc in a predetermined pressure range (Pc2 ≦ Pc ≦ Pc1) based on the acquired fuel pressure Pc (step S103). Specifically, the ECU 50 acquires a decreasing tendency (dPc / dt) of the fuel pressure Pc by dividing the value obtained by subtracting the second pressure value Pc2 from the first pressure value Pc1 by the measurement time T.

Then, the ECU 50 calculates the static leakage amount SL based on the acquired downward tendency of the fuel pressure Pc (dPc / dt), the rail volume V, and the bulk modulus K (step S104). Further, the ECU 50 corrects the static leak amount SL calculated in step S104 based on the fuel temperature detected by the temperature sensor 22, and acquires the static leak amount SL at the reference temperature (step S105).

Further, the ECU 50 corrects the static leak amount SL calculated in step S105 based on the fuel pressure Pc detected immediately after the transition to the stationary state, and acquires the static leak amount SL at the reference pressure (step S106).

Next, the ECU 50 determines whether or not the injector 23 is in the initial state (step S107). Specifically, the ECU 50 acquires the cumulative usage time AT from the storage device 55, and determines whether or not the acquired cumulative usage time AT is zero to 24 hours.

If this determination result is affirmative, the ECU 50 determines whether or not the initial history SL1 is already stored (step S108). If this determination result is negative, the ECU 50 stores the static leak amount SL acquired in step S106 as the initial history SL1 (step S109). Then, the ECU 50 ends the abnormality determination process.

On the other hand, if the determination result in step S107 is negative, or if the determination result in step S108 is affirmative, the ECU 50 acquires the initial history SL1 from the storage device 55 (step S110). Then, the ECU 50 specifies the deterioration leak amount DL based on the cumulative usage time AT and the initial history SL1 (step S111). That is, the ECU 50 specifies the deterioration leak amount DL by using the cumulative usage time AT and the initial history SL1 as arguments by map calculation.

Further, the ECU 50 sets the abnormality determination threshold value Th based on the initial history SL1 and the deterioration leak amount DL (step S112). Specifically, the ECU 50 sets the abnormality determination threshold value Th by adding up the initial history SL1, the deterioration leak amount DL, and the predetermined value M1 as a margin.

After that, the ECU 50 determines whether or not the static leak amount SL acquired in step S106 is larger than the abnormality determination threshold value Th (step S113). If this determination result is affirmative, the ECU 50 determines that the static leak amount SL is abnormal (or has a sign of abnormality), and performs a process corresponding to the abnormality (step S114). Specifically, a notification such as turning on a warning lamp is performed. On the other hand, if the determination result in step S113 is negative, the ECU 50 considers that there is no abnormality and ends the abnormality determination process.

According to the present embodiment described in detail above, the following excellent effects can be obtained.

The ECU 50 sets the abnormality determination threshold value Th based on the past history (initial history SL1) of the static leakage amount SL stored in the storage device 55. Then, the ECU 50 compares the abnormality determination threshold value Th with the current static leak amount SL calculated in step S106, and determines the abnormality. As a result, even if there is an individual difference in the injector 23, the abnormality determination threshold Th is set based on the past history of the static leak amount SL (initial history SL1). Therefore, the individual difference of the injector 23 is set in the abnormality determination threshold Th. It will be reflected and set. For example, when the static leak amount SL in the proper state is large due to individual differences, the abnormality determination threshold Th is also large, and when the static leak amount SL in the proper state is small due to individual differences, the abnormality determination threshold Th is also small. Therefore, even when a sign of abnormality such as a sudden increase in the static leak amount SL occurs, the sign can be determined in advance without being affected by individual differences. That is, the leak abnormality of the injector 23 can be appropriately detected.

The individual difference in the injector 23 is also reflected (included) in the static leak amount SL in the initial state. Therefore, the ECU 50 stores the initial history SL1 indicating the static leak amount SL when the injector 23 is in the initial state as the history of the static leak amount SL, and sets the abnormality determination threshold value Th with reference to the initial history SL1. I decided. As a result, the signs of abnormality can be appropriately determined without being affected by individual differences.

It is known that the static leakage amount SL increases as the injector 23 deteriorates over time. Therefore, in order to properly determine the abnormality, it is necessary to consider the deterioration leak amount DL, which is the increase in the static leak amount SL due to the deterioration over time. By the way, there are individual differences in the deterioration leak amount DL. More specifically, the deterioration leak amount DL differs depending on the static leak amount SL in the initial state. Therefore, the ECU 50 specifies the deterioration leak amount DL based on the initial history SL1, and sets the abnormality determination threshold value Th based on the specified deterioration leak amount DL and the initial history SL1. As a result, even if there are individual differences in the injector 23, the abnormality can be determined by appropriately considering the deterioration leak amount DL.

Based on the fuel temperature, the ECU 50 corrects the static leak amount SL to acquire the static leak amount SL at the reference temperature. As a result, even if there is a change in the static leakage amount SL based on the difference in fuel temperature, the change can be corrected and an abnormality can be appropriately determined.

The ECU 50 decides to correct the static leakage amount SL based on the fuel pressure Pc detected immediately after the transition to the stationary state. As a result, even if there is a change in the static leak amount SL based on the difference in the fuel pressure Pc immediately after the transition to the stationary state, the change can be corrected and an abnormality can be appropriately determined.

(Second Embodiment)
In the second embodiment, the method of setting the abnormality determination threshold value Th is different from that of the first embodiment. The part different from the first embodiment will be mainly described. In the following, the parts that are the same or equal to each other in each embodiment are designated by the same reference numerals, and the description thereof will be referred to for the portions having the same reference numerals.

In the second embodiment, the ECU 50 as the storage unit 52 stores a plurality of static leak amount SLs in chronological order with the static leak amount SL as a history. Specifically, each time the static leak amount SL is calculated, the ECU 50 stores it in the storage device 55 as a history. At that time, the cumulative usage time AT after the injector 23 is started to be used is also stored.

In the second embodiment, the ECU 50 as the threshold value setting unit 53 sets the abnormality determination threshold value Th based on the plurality of static leak amount SLs stored in the storage device 55 in time series.

More specifically, it is possible to predict to some extent what kind of static leak amount SL will be in the future based on a plurality of static leak amount SL stored in time series. For example, if a plurality of static leak amount SLs stored in a time series are substantially constant, it is considered that a similar static leak amount SL is calculated as long as a leak abnormality does not occur.

Therefore, the ECU 50 grasps the tendency of the static leak amount SL based on the plurality of static leak amount SL stored in the time series. For example, the ECU 50 acquires the average of a plurality of static leak amount SLs stored in time series as a tendency of the static leak amount SL. It is desirable that the plurality of static leak amount SLs include the latest static leak amount SL and are continuous static leak amount SLs in chronological order.

Then, the ECU 50 sets the abnormality determination threshold value Th based on the acquired tendency of the static leak amount SL. For example, the ECU 50 sets the abnormality determination threshold value Th by adding a predetermined value M2 as a margin to the average value of a plurality of static leak amounts SL stored in time series.

Since this abnormality determination threshold value Th is set based on the past history detected from the same injector 23, the individual difference of the injector 23 is reflected. The predetermined value M2 is a predetermined constant value, but may be changed depending on the state of the fuel. For example, it may be changed depending on the fuel temperature or the fuel pressure Pc detected immediately after the transition to the rest state.

By the way, as shown in FIG. 7, the static leak amount SL has a tendency to increase from the start of use of the injector 23 until a predetermined period elapses, and then converge within a predetermined range after the elapse of a predetermined period. This tendency of change exists regardless of individual differences in any of the injectors 23. It is considered that the rapid increase in the static leakage amount SL until the predetermined period elapses is due to the initial wear of the sliding member of the injector 23 and the like. When the abnormality determination threshold value Th is set based on the static leak amount SL acquired in such a rapidly increasing period, an error is found as compared with the case where the abnormality determination threshold Th is set based on the static leak amount SL acquired in the converging period. It tends to grow.

Therefore, in the second embodiment, the ECU 50 decides to set the abnormality determination threshold value Th based on a plurality of static leak amounts stored in time series after the lapse of a predetermined period from the start of use of the injector 23. .. That is, the ECU 50 decides to set the abnormality determination threshold value Th based on the static leak amount stored after the lapse of a predetermined period and the plurality of static leak amounts stored in the time series.

The predetermined period is defined as a period until the amount of static leakage increases after the injector 23 starts to be used and then converges, and whether or not the predetermined period has elapsed can be determined by any method described below. You just have to judge.

For example, the ECU 50 may determine that a predetermined period has elapsed when one or more static leakage amounts SL are present within a predetermined range. Alternatively, when the average value of the plurality of static leak amounts SL is within a predetermined range, the ECU 50 may determine that the predetermined period has elapsed.

Further, there is an individual difference in the static leak amount SL after convergence (after the completion of the initial wear), and the individual difference is reflected in the initial history SL1. Therefore, for example, the ECU 50 determines that the predetermined period has elapsed when one or a plurality of static leak amounts SL exist within a predetermined range set by referring to the conformity map or the like according to the initial history SL1. You may. Alternatively, when the average value of the plurality of static leak amounts SL is within a predetermined range set according to the initial history SL1, the ECU 50 may determine that the predetermined period has elapsed.

Further, for example, the ECU 50 elapses a predetermined period if the difference between the minimum value and the maximum value among a plurality of static leak amount SLs including the latest static leak amount SL is within a predetermined range. It may be determined that it has been done.

Further, for example, the ECU 50 may determine whether or not the predetermined period has elapsed based on whether or not the cumulative usage time AT from the start of use of the injector 23 has elapsed. The predetermined time may be a predetermined time. Alternatively, considering that there are individual differences in the time until the initial wear is completed, the time set with reference to the conformity map or the like based on the initial history SL1 may be set as a predetermined time.

Further, for example, the ECU 50 may determine whether or not a predetermined period has elapsed based on the slope of the approximate line calculated from the plurality of static leak amounts SL. That is, it may be determined depending on whether or not the slope of the approximate line is a predetermined slope. When calculating the approximate line, the ECU 50 may calculate the straight line passing through the position closest to the plurality of static leakage amounts SL by using a well-known linear interpolation calculation such as the least squares method.

The 1 or static leak amount SL used when determining whether or not a predetermined period has elapsed is the latest static leak amount SL or a plurality of continuous static leak amounts SL including the latest static leak amount SL. It is desirable that the leak amount is SL. Further, in the present embodiment, the leak abnormality is not determined before the lapse of a predetermined period.

Next, the flow of the abnormality determination process in the second embodiment will be described with reference to FIG. The abnormality determination process is executed by the ECU 50 at predetermined intervals. Since steps S101 to S106 are the same as those in the first embodiment, the description thereof will be omitted.

After the process of step S106, the ECU 50 stores the static leak amount SL calculated in step S106 in the storage device 55 as a history (step S201). At that time, the cumulative usage time AT after the injector 23 is started to be used is also stored (associated).

Next, the ECU 50 determines whether or not a predetermined predetermined period has elapsed since the injector 23 started to be used (step S202).

If the determination result in step S202 is negative, the abnormality determination process ends. On the other hand, when the determination result in step S202 is affirmative, the ECU 50 sets the abnormality determination threshold value Th based on the history of the plurality of static leakage amounts SL acquired in time series after the lapse of a predetermined period (step S203).

In step S203, the ECU 50 first calculates the average value of a plurality (for example, three) static leak amount SLs continuously stored in time series among the static leak amount SLs acquired after the lapse of a predetermined period. .. Then, the ECU 50 adds a predetermined value M2 as a margin to the average value to set the abnormality determination threshold value Th. It is desirable that the plurality of static leak amount SLs are a plurality of continuous static leak amount SLs including the latest static leak amount SL. In this embodiment, three static leak amount SLs calculated one to three cycles before are adopted.

After that, the ECU 50 determines whether or not the static leak amount SL acquired in step S106 is larger than the abnormality determination threshold value Th (step S204).

If this determination result is affirmative, the ECU 50 determines that it is abnormal (or has a sign of abnormality), and performs a process corresponding to the abnormality (step S205). Specifically, a notification such as turning on a warning lamp is performed. On the other hand, if the determination result in step S205 is negative, the ECU 50 considers that there is no abnormality and ends the abnormality determination process.

According to the present embodiment described in detail above, the following excellent effects can be obtained.

From a plurality of static leak amount SLs stored in a time series, it is possible to recognize (or predict) a change tendency as to how the static leak amount SL changes. If the static leakage amount SL is detected from the same injector 23, it is not necessary to consider individual differences. That is, since the individual difference is reflected in the past history, the ECU 50 sets the abnormality determination threshold value Th based on the change tendency that can be grasped from the plurality of static leak amounts SL, so that the abnormality can be detected regardless of the individual difference. It can be judged appropriately. That is, even when a sign of abnormality occurs such that the static leak amount SL suddenly increases, the sign of abnormality can be appropriately determined without being affected by individual differences.

The static leakage amount SL of the injector 23 tends to increase after the start of use until the initial wear of the sliding member of the injector 23 is completed. On the other hand, the static leakage amount SL converges within a predetermined range after the initial wear is completed. Therefore, if the change tendency is predicted based on the history before the end of the initial wear, erroneous determination is likely to occur. Therefore, it was decided to set the abnormality determination threshold value Th based on the history after the static leak amount SL has converged, that is, after the initial wear is completed. Specifically, the ECU 50 determines whether or not a predetermined predetermined period has elapsed since the injector 23 started to be used, and if the predetermined period has elapsed, the abnormality determination threshold value Th is set based on the history thereafter. I decided to set it. As a result, even when the static leakage amount SL suddenly increases due to the initial wear, it is possible to prevent erroneous determination that an abnormality has occurred.

(Other embodiments)
The present invention is not limited to the above embodiment, and may be implemented as follows, for example. In the following, the parts that are the same or equal to each other in each embodiment are designated by the same reference numerals, and the description thereof will be referred to for the portions having the same reference numerals.

-In the above embodiment, the static leak amount SL is corrected based on the fuel state (fuel temperature or fuel pressure Pc), but it may not be performed. That is, it is not necessary to correct the static leakage amount SL based on the fuel temperature. Similarly, in the above embodiment, it is not necessary to correct the static leakage amount SL based on the fuel pressure Pc immediately after the transition to the rest state.

-In the second embodiment, when the abnormality determination threshold value Th is set, it is set based on the average value of a plurality of static leak amount SLs, but based on the approximate line specified from the plurality of static leak amount SLs or its slope. It may be set. That is, the current static leak amount SL is predicted based on the approximate line specified from the plurality of static leak amount SLs stored in the time series or its slope, and the predicted static leak amount SL is set to the predetermined value M2 as a margin. In addition, the abnormality determination threshold Th may be set. When calculating the approximate line, the ECU 50 may calculate the straight line passing through the position closest to the plurality of static leakage amounts SL by using a well-known linear interpolation calculation such as the least squares method.

-In the second embodiment, the abnormality determination is performed after a predetermined period of time has elapsed from the start of use of the injector 23, but the abnormality determination may be performed even before the predetermined period has elapsed. That is, the process of step S202 may be omitted. In this case, in step S203, the ECU 50 may set the abnormality determination threshold value Th based on the history of the plurality of static leak amounts SL stored in time series. At that time, it is desirable that the history of a plurality of continuous static leak amount SLs including the latest static leak amount SL is included.

By the way, as described in the second embodiment, there is a possibility that the static leak amount SL rapidly increases due to the initial wear before the predetermined period elapses from the start of use of the injector 23. Therefore, before the lapse of the predetermined period, it is desirable to increase the static leak amount SL referred to for setting the abnormality determination threshold value Th as compared with the case after the lapse of the predetermined period. For example, if the abnormality determination threshold value Th is set based on the history of three static leak amount SLs after a predetermined period has elapsed, the abnormality determination threshold value Th is set based on the history of four or more static leak amount SLs. Is desirable. By doing so, the tendency of the static leak amount SL can be grasped more accurately, and erroneous determination based on the rapid increase in the static leak amount SL due to the initial wear can be suppressed.

-In the second embodiment, when the abnormality is determined before the predetermined period elapses after the injector 23 is started to be used, the abnormality set based on the initial history SL1 is performed as in the first embodiment. Abnormality determination may be performed using the determination threshold value Th. That is, the first embodiment and the second embodiment may be combined.

Specifically, when the determination result of step S202 is negative, the ECU 50 performs the processes after step S107 in the first embodiment, and when the determination result in step S202 is affirmative, the process after step S203 in the second embodiment. It suffices to carry out the process of. By doing so, it is possible to suppress erroneous determination based on the rapid increase in the static leakage amount SL due to the initial wear.

-In the second embodiment, it is not necessary to store the calculated static leak amount SL as a history before the predetermined period elapses. It suffices if the history is stored at least after the lapse of a predetermined period.

-In the above embodiment, when an abnormality is determined consecutively a plurality of times, it may be determined that there is a leak abnormality.

-In the second embodiment, even when the static leak amount SL is slightly changed as compared with the first embodiment, the abnormality can be determined. For example, even if an abnormal fuel is used, that fact can be detected. Therefore, if the abnormality is determined once or a plurality of times in succession and then the abnormality is no longer determined, the ECU 50 may determine that the abnormal fuel has been used and notify that fact.

10 ... fuel tank, 11 ... fuel pump, 20 ... common rail, 21 ... fuel pressure sensor, 23 ... injector, 50 ... ECU, 51 ... leak amount calculation unit, 52 ... storage unit, 53 ... threshold setting unit, 54 ... abnormality determination unit ..

Claims (7)

A fuel pump (11) that increases the pressure of the fuel in the fuel tank (10) and discharges it,
A common rail (20) that stores the fuel discharged from the fuel pump, and
A fuel injection valve (23) that injects the fuel stored in the common rail into the cylinder of the engine, and
It is applied to a fuel injection device including a fuel pressure sensor (21) for detecting the fuel pressure in the common rail.
The fuel pressure sensor detects the static leak amount, which is the amount of fuel leak from the fuel injection valve in the stationary state where the fuel injection is stopped and the fuel is not discharged from the fuel pump. The leak amount calculation unit (51) calculated based on the value, and
A storage unit (52) that stores the history of the static leak amount,
A threshold setting unit (53) that sets an abnormality determination threshold value based on the history of the static leak amount stored by the storage unit, and
An abnormality determination unit (54) for determining the presence or absence of an abnormality based on the result of comparison between the static leak amount calculated by the leak amount calculation unit and the abnormality determination threshold value.
(50). The storage unit stores, as the history of the static leak amount, an initial history indicating the static leak amount when the fuel injection valve is in the initial state.
The control device according to claim 1, wherein the threshold value setting unit sets the abnormality determination threshold value based on the initial history. A deterioration amount specifying unit (56) for specifying a deterioration leak amount based on the deterioration over time of the fuel injection valve based on the initial history is provided.
The control device according to claim 2, wherein the threshold value setting unit sets the abnormality determination threshold value based on the deterioration leak amount specified by the deterioration amount specifying unit and the initial history. The storage unit stores a plurality of static leak amounts in chronological order as a history of the static leak amount.
The control device according to any one of claims 1 to 3, wherein the threshold value setting unit sets the abnormality determination threshold value based on a plurality of static leak amounts stored in time series. The abnormality determination threshold value is set based on a plurality of static leak amounts stored in time series after a predetermined period of time has elapsed from the start of use of the fuel injection valve.
The control device according to claim 4, wherein the predetermined period is defined as a period in which the static leakage amount increases after the start of use of the fuel injection valve and then converges. A temperature sensor (22) for detecting the fuel temperature in the common rail is provided.
The control device according to any one of claims 1 to 5, wherein the leak amount calculation unit corrects the static leak amount based on the fuel temperature detected by the temperature sensor. The leak amount calculation unit acquires the tendency of decrease in fuel pressure when the fuel pressure detected by the fuel pressure sensor is within a predetermined pressure range, and calculates the amount of static leak based on the tendency of decrease in fuel pressure. can be,
The control device according to any one of claims 1 to 6, wherein the leak amount calculation unit corrects the static leak amount based on the fuel pressure detected immediately after the transition to the stationary state.

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