JP6984433B2 - Fuel injection valve abnormality judgment device - Google Patents

Description

The present invention relates to a fuel injection valve abnormality determination device capable of determining whether or not a fuel injection valve needs to be replaced in a fuel injection system including a plurality of fuel injection valves.

Patent Document 1 discloses a technique for determining an abnormality of a fuel injection valve from a change in fuel pressure (fuel pressure waveform) caused by injection. Since the fuel pressure waveform correlates with the injection rate waveform (injection state), a predetermined parameter for specifying the injection state is calculated from the fuel pressure waveform. By comparing each of the calculated parameters with a predetermined threshold value, it is determined whether or not there is an abnormality in the fuel injection valve. When it is determined that the fuel injection valve has an abnormality, measures such as replacement of the fuel injection valve are carried out in order to eliminate the cause of the abnormality in the fuel injection valve.

Japanese Unexamined Patent Publication No. 2013-256922

In the fuel injection valve, the injection state may deviate due to the accumulation of the deposit in the injection hole, and accordingly, the injection amount deviates from the required injection amount according to the operation period of the internal combustion engine (hereinafter referred to as the injection deviation amount). ) May increase monotonically. In this case, for the fuel injection valve of each cylinder of the internal combustion engine, the fuel injection valve is replaced based on the fact that the injection deviation amount becomes larger than the threshold value which is the replacement index of the fuel injection valve. Further, in general, when the injection deviation amount becomes larger than the threshold value, all the fuel injection valves are replaced at once, or only the corresponding fuel injection valves are replaced.

However, when all the fuel injection valves are replaced at once, there is a problem that the fuel injection valves that do not need to be replaced are replaced unnecessarily. Further, when only the corresponding fuel injection valve is replaced, it will be necessary to replace other fuel injection valves in the near future, which causes a problem that the replacement of the fuel injection valve becomes frequent. There is a need for technology that can appropriately determine the request for replacement of the fuel injection valve. It should be noted that such a problem is not limited to the accumulation of the deposit in the injection hole, but is a common problem to the abnormality of the fuel injection valve in which the injection deviation amount simply increases according to the operation period of the internal combustion engine.

An object of the present invention is to provide a fuel injection valve abnormality determination device capable of appropriately determining a fuel injection valve replacement request.

The abnormality determination device for a fuel injection valve of the present invention is applied to a fuel injection system including a plurality of fuel injection valves for injecting fuel into an internal combustion engine, and the actual injection amount at the time of performing fuel injection is determined for each fuel injection valve. The actual injection amount calculation unit to be calculated, the deviation amount calculation unit for calculating the difference between the actual injection amount and the required injection amount or the correlation value thereof as the injection deviation amount, and the fuel injection valve for each fuel injection valve. The first determination unit for determining that the fuel injection valve should be replaced based on the fact that the injection deviation amount is larger than the first threshold value, and the first determination unit for any one of the plurality of fuel injection valves. When it is determined to replace the fuel injection valve other than the fuel injection valve, if the injection deviation amount is larger than the second threshold value smaller than the first threshold value, the fuel injection valve is to be replaced. Is provided, and if the injection deviation amount is smaller than the second threshold value, a second determination unit for determining that the fuel injection valve is not replaced is provided.

In the fuel injection valve, a deviation in the fuel injection amount may occur due to the accumulation of deposits in the injection holes, and it is considered that the injection deviation amount, which is the deviation amount, increases monotonically according to the operating period of the internal combustion engine. Therefore, when the injection deviation amount of a certain fuel injection valve is larger than the first threshold value, the injection deviation amount of another fuel injection valve may also increase to near the first threshold value. In this case, if only the fuel injection valve whose injection deviation amount is larger than the first threshold value is replaced, it will be necessary to replace other fuel injection valves in the near future, and the replacement of the fuel injection valve may become frequent. There is. On the other hand, since there are individual differences in the increase in the injection deviation amount for each fuel injection valve, even if the injection deviation amount of one fuel injection valve is larger than the first threshold value, the injection deviation amount of another fuel injection valve is the second. It may not have increased to near one threshold. In this case, if all the fuel injection valves are replaced, other fuel injection valves may be replaced unnecessarily.

In this respect, when the injection deviation amount of a certain fuel injection valve is larger than the first threshold value and it is determined to replace the fuel injection valve, the injection deviation amount of another fuel injection valve is larger than the first threshold value. If it is larger than the small second threshold value, it is determined that the fuel injection valve is to be replaced. As a result, the fuel injection valves whose injection deviation amount has increased to near the first threshold value can be replaced collectively, and the replacement frequency of the fuel injection valve can be suppressed. Further, if the injection deviation amount of the other fuel injection valve is smaller than the second threshold value, it is determined that the fuel injection valve is not replaced. As a result, it is possible to prevent the fuel injection valve whose injection deviation amount has not increased to near the first threshold value from being replaced unnecessarily. This makes it possible to appropriately determine whether or not the fuel injection valve needs to be replaced.

The schematic diagram which shows the structure of a fuel injection system. A time chart showing the drive signal, injection rate, and pressure waveform. The flowchart which shows the procedure of the abnormality detection processing of 1st Embodiment. Schematic diagram illustrating a learning map. The flowchart which shows the procedure of exchange determination processing of 1st Embodiment. A table showing the judgment results of the abnormality judgment processing. A graph showing the judgment result of the abnormality judgment processing. A graph showing the secular change of the injection correction time. The flowchart which shows the procedure of the abnormality determination processing of 2nd Embodiment.

(First Embodiment)
Hereinafter, each embodiment of the fuel injection valve abnormality determination device (hereinafter, simply referred to as an abnormality determination device) according to the present invention will be described with reference to the drawings. The abnormality determination device described below is mounted on a vehicle engine (internal combustion engine), and high-pressure fuel is injected into the engine for a plurality of cylinders # 1 to # 4 to perform compression self-ignition combustion. It assumes a diesel engine.

FIG. 1 includes a plurality of fuel injection valves 10 mounted on the cylinders # 1 to # 4 of the engine, a fuel pressure sensor 20 mounted on each fuel injection valve 10, an ECU 30 which is an abnormality determination device, and the like. It is a schematic diagram which shows the fuel injection system 100. The fuel injection system 100 is mounted on a vehicle engine.

The fuel injection system 100 is a common rail type fuel injection system, in which the fuel in the fuel tank 40 is pumped up by the fuel pump 41, pumped to the common rail 42 and stored in a high pressure state, and is stored in a high pressure state from the orifice 42a of the common rail 42 to the fuel pipe. It is distributed and supplied to the fuel injection valves 10 of each cylinder # 1 to # 4 via 42b. The plurality of fuel injection valves 10 sequentially inject fuel in a preset order. Since the plunger pump is used for the fuel pump 41, the fuel is pumped in synchronization with the reciprocating motion of the plunger.

The fuel injection valve 10 includes a body 11, a needle-shaped valve body 12, an actuator 13, and the like described below. The body 11 forms a high-pressure passage 11a inside and also forms a jet hole 11b for injecting fuel. The valve body 12 is housed in the body 11 and opens and closes the injection hole 11b.

A back pressure chamber 11c for applying back pressure to the valve body 12 is formed in the body 11, and the high pressure passage 11a and the low pressure passage 11d are connected to the back pressure chamber 11c. The communication state between the high-pressure passage 11a and the low-pressure passage 11d and the back pressure chamber 11c is switched by the control valve 14, and the actuator 13 such as an electromagnetic coil or a piezo element is energized to push the control valve 14 downward in FIG. Then, the back pressure chamber 11c communicates with the low pressure passage 11d, and the fuel pressure P in the back pressure chamber 11c decreases. As a result, the back pressure applied to the valve body 12 is reduced, and the valve body 12 is lifted up (valve opening drive). As a result, the seat surface 12a of the valve body 12 is separated from the seat surface 11e of the body 11, and fuel is injected into the engine from the injection hole 11b.

On the other hand, when the power supply to the actuator 13 is turned off and the control valve 14 is driven upward in FIG. 1, the back pressure chamber 11c communicates with the high pressure passage 11a and the fuel pressure P in the back pressure chamber 11c rises. As a result, the back pressure applied to the valve body 12 rises, and the valve body 12 is lifted down (valve closed drive). As a result, the seat surface 12a of the valve body 12 is seated on the seat surface 11e of the body 11, and the fuel injection from the injection hole 11b is stopped.

Therefore, the ECU 30 controls the energization of the actuator 13, so that the opening / closing drive of the valve body 12 is controlled. As a result, the high-pressure fuel supplied from the common rail 42 to the high-pressure passage 11a is injected from the injection hole 11b in response to the opening / closing drive of the valve body 12.

The fuel pressure sensor 20 is mounted on each fuel injection valve 10 and detects the pressure of the fuel supplied to the fuel injection valve 10. The fuel pressure sensor 20 includes a stem 21 (distortion body) and a fuel pressure sensor element 22 described below. The stem 21 is attached to the body 11, and the diaphragm portion 21a formed in the stem 21 is elastically deformed under the pressure of the high-pressure fuel flowing through the high-pressure passage 11a. The fuel pressure sensor element 22 is attached to the diaphragm portion 21a, and outputs a pressure detection signal to the ECU 30 according to the amount of elastic deformation generated in the diaphragm portion 21a.

The ECU 30 calculates, for example, the required injection amount Qk and the injection time TQ as the required injection state based on the operation amount of the accelerator pedal, the engine load, the engine rotation speed, and the like. The injection time TQ is a time indicating the length of the on-time (that is, the energization time) of the drive signal Sm (see FIG. 2A) output as an injection pulse. For example, the ECU 30 stores an injection state map in which the optimum injection state corresponding to the engine load and the engine rotation speed is stored. The ECU 30 calculates the required injection state with reference to the injection state map based on the current engine load and engine rotation speed. The ECU 30 controls the drive of the fuel injection valve 10 by generating a drive signal Sm that realizes the required injection amount Qk corresponding to the calculated required injection state and outputting the drive signal Sm to the fuel injection valve 10.

Further, as shown in FIG. 2, the ECU 30 detects a change in the fuel pressure P as a pressure waveform Pw based on the detected value of the fuel pressure sensor 20, and the fuel injection rate is based on the amount of fuel pressure drop caused by the injection. Calculate the waveform Qw. The pressure drop amount means the pressure drop amount from the predetermined required fuel pressure Ptg. The ECU 30 calculates the actual injection amount Qr from the calculated injection rate waveform Qw.

By the way, in the fuel injection valve 10, a difference (deviation) ΔQ may occur between the required injection amount Qk and the actual injection amount Qr due to the accumulation of a deposit in the injection hole 11b, and injection is performed in order to correct the difference ΔQ. The injection correction time ΔTQ, which is the correction value of the time TQ, is calculated. In this case, the injection time TQ calculated based on the required injection amount Qk is corrected by the injection correction time ΔTQ, and the drive signal Sm is set based on the corrected injection time TQ. When the calculated injection correction time ΔTQ becomes larger than the predetermined first threshold value Le1, it is determined that the corresponding fuel injection valve 10 has an abnormality, and it is determined that the fuel injection valve 10 is to be replaced. Will be done. In the present embodiment, the injection correction time ΔTQ corresponds to the “correlation value” and the “injection deviation amount”.

The injection correction time ΔTQ is considered to increase monotonically according to the operating period of the engine. Therefore, when it is determined that one of the plurality of fuel injection valves 10 provided in the engine has an abnormality, the injection correction time ΔTQ of the other fuel injection valves 10 also increases to near the first threshold value Le1. Is expected. In this case, if only the fuel injection valve 10 determined to have an abnormality is replaced, it will be necessary to replace another fuel injection valve 10 in the near future, and the replacement of the fuel injection valve 10 may become frequent. There is.

On the other hand, since there are individual differences in the increase in the injection correction time ΔTQ for each fuel injection valve 10, even if it is determined that one of the plurality of fuel injection valves 10 has an abnormality, another fuel injection is performed. The injection correction time ΔTQ of the valve 10 may not increase to near the first threshold Le1. In this case, if all the fuel injection valves 10 are replaced, the fuel injection valves 10 are replaced unnecessarily.

The ECU 30 of the present embodiment carries out an abnormality determination process in order to solve the above problem. In the abnormality determination process, when it is determined that any one of the plurality of fuel injection valves 10 is to be replaced, the injection correction time ΔTQ of the fuel injection valves 10 other than the fuel injection valve 10 is larger than that of the first threshold Le1. If it is larger than the small second threshold Le2, it is determined that the fuel injection valve 10 is to be replaced, and if the injection correction time ΔTQ is smaller than the second threshold Le2, it is determined that the fuel injection valve 10 is not replaced. It is a process. This makes it possible to appropriately determine whether or not the fuel injection valve 10 needs to be replaced.

The abnormality determination process includes an abnormality detection process and a replacement determination process. Hereinafter, the abnormality detection process and the exchange determination process will be described in this order.

First, the abnormality detection process will be described. The abnormality detection process is a process for detecting an abnormality in the fuel injection valve 10 that triggers the replacement determination process. The abnormality detection process is repeatedly performed by the ECU 30 while the engine is being driven.

FIG. 3 is a flowchart showing the procedure of abnormality detection processing. When the abnormality detection process is started, first, in step S10, it is determined whether the engine is in operation. When the IG switch of the vehicle equipped with the engine is turned on, it is determined that the engine is running. If a negative determination is made in step S10, the abnormality detection process ends.

If affirmative determination is made in step S10, it is determined in step S12 whether the fuel pressure P of each fuel injection valve 10 is in a stable state at a predetermined required fuel pressure Ptg for each fuel injection valve 10. The predetermined required fuel pressure Ptg is the fuel pressure P corresponding to the required injection state, and the stable state means that the fuel pressure P is within a predetermined range centered on the required fuel pressure Ptg for a certain period of time. Means. When it is determined that any one of the plurality of fuel injection valves 10 is not in a stable state, a negative determination is made. If a negative determination is made in step S12, the abnormality detection process ends.

On the other hand, when it is determined that all of the plurality of fuel injection valves 10 are in a stable state, an affirmative determination is made. If affirmative determination is made in step S12, the pressure waveform Pw detected by the fuel pressure sensor 20 at the time of fuel injection by the fuel injection valve 10 is acquired in step S14.

In step S16, the actual injection amount Qr is calculated for each fuel injection valve 10. As shown in FIG. 2, the injection rate waveform Qw is calculated from the pressure waveform Pw detected by the fuel pressure sensor 20, and the calculated injection rate waveform Qw is integrated over the fluctuation period of the injection rate waveform Qw to obtain the actual injection amount. Calculate Qr. The injection rate waveform Qw can be calculated according to a known method. In the present embodiment, the process of step S16 corresponds to the "actual injection amount calculation unit".

In step S18, the difference ΔQ is calculated for each fuel injection valve 10. In the following step S20, the injection correction time ΔTQ is calculated for each fuel injection valve 10. In the present embodiment, the process of step S18 corresponds to the “deviation amount calculation unit”. The injection correction time ΔTQ is described below by using, for example, the previous injection correction time ΔTQp which is the injection correction time ΔTQ calculated in the previous abnormality detection process and the deviation time ΔTZ corresponding to the difference ΔQ calculated in step S18. It can be calculated as follows.
ΔTQ = (n-1) / n × ΔTQp + ΔTZ (n: natural number) ... (Equation 1)
In the fuel injection system 100, feedback control is performed so that the required injection amount Qk and the actual injection amount Qr match, and the injection correction time ΔTQ calculated in step S20 is the required injection amount Qk and the actual injection. It is used as a correction amount for feedback control to match the quantity Qr.

In step S22, the injection correction time ΔTQ calculated in step S20 is stored in the internal EEPROM (registered trademark) or the like for each fuel injection valve 10. The injection correction time ΔTQ is stored in association with the required injection amount Qk and the fuel pressure P (for example, the required fuel pressure Ptg) in the injection in which the injection correction time ΔTQ is calculated. In the present embodiment, the process of step S22 corresponds to the "storage unit".

A learning map is used to store the injection correction time ΔTQ. As shown in FIG. 4, in the learning map, the storage area of the injection correction time ΔTQ is divided into a plurality of areas corresponding to the required injection amount Qk, and is divided into a plurality of areas corresponding to the fuel pressure P. Has been done. The injection correction time ΔTQ is stored for each of a plurality of regions defined by the required injection amount Qk and the fuel pressure P.

In step S24, it is determined for each fuel injection valve 10 whether the injection correction time ΔTQ calculated in step S20 is larger than the predetermined first threshold value Le1. The predetermined first threshold value Le1 is determined based on the maximum injection time TQmax that allows normal operation of the engine. Negative determination is made when the injection correction time ΔTQ is smaller than the first threshold value Le1 for all of the plurality of fuel injection valves 10. If a negative determination is made in step S24, the abnormality detection process ends.

On the other hand, for any of the plurality of fuel injection valves 10, affirmative determination is made when the injection correction time ΔTQ is larger than the first threshold value Le1. If an affirmative determination is made in step S24, the MIL (Malfunction Indicator Lump) is turned on in step S26, and the abnormality detection process is terminated. As a result, the vehicle is brought into a service station such as a repair shop by the user, and the replacement determination process is performed at the service station.

FIG. 5 is a flowchart showing the procedure of the exchange determination process. The replacement determination process is a process for determining the fuel injection valve 10 to be replaced (hereinafter, simply referred to as a replacement target) due to the occurrence of an abnormality in the fuel injection valve 10. The exchange determination process is performed by the ECU 30 that receives an instruction from a dedicated control device (not shown) at the service station. The replacement determination process is performed in a state where the vehicle is stopped and the engine is operated, that is, in an idle state.

When the replacement determination process is started, first, in step S40, the fuel pressure P of each fuel injection valve 10 is set to a predetermined first required fuel pressure Ptg1. The predetermined first required fuel pressure Ptg1 is the fuel pressure P when the vehicle is idling, and is, for example, 30 MPa. In the following step S42, for each fuel injection valve 10, it is determined whether the fuel pressure P of each fuel injection valve 10 is in a stable state at the first required fuel pressure Ptg1. When it is determined that any one of the plurality of fuel injection valves 10 is not in a stable state, a negative determination is made. If a negative determination is made in step S42, it is determined that the first abnormality has occurred in step S44, and the exchange determination process is terminated.

Here, the first abnormality is an abnormality in which the fuel pressure P of the fuel injection valve 10 does not pulsate or the fuel pressure P of the fuel injection valve 10 does not rise sufficiently due to, for example, a dent or a crack in the fuel pipe 42b. When the first abnormality has occurred, the fuel injection valve 10 cannot perform normal injection even if the fuel injection valve 10 does not have an abnormality. In this case, after the cause of the first abnormality is removed, the abnormality determination process is performed again, and the abnormality of the fuel injection valve 10 is determined.

On the other hand, when it is determined that all of the plurality of fuel injection valves 10 are in a stable state, an affirmative determination is made. If affirmative determination is made in step S42, the pressure waveform Pw detected by the fuel pressure sensor 20 at the time of fuel injection by the fuel injection valve 10 is acquired in step S46.

In step S48, it is determined for each fuel injection valve 10 whether the pressure waveform Pw detected by the fuel pressure sensor 20 includes the injection waveform. Specifically, it is determined whether the falling waveform Wd and the rising waveform Wu (see FIG. 2) corresponding to the drive signal Sm of the fuel injection valve 10 are observed in the pressure waveform Pw. As shown by the broken line F1 in FIG. 2C, a negative determination is made when the pressure waveform Pw does not include the injection waveform for any one of the plurality of fuel injection valves 10. If a negative determination is made in step S48, it is determined that a second abnormality has occurred in step S50, and the exchange determination process is terminated. In the present embodiment, the process of step S48 corresponds to the “waveform determination unit”.

Here, the second abnormality is a sudden abnormality such as disconnection of the signal line connecting the ECU 30 and the fuel injection valve 10 or mixing of foreign matter into the fuel injection valve 10. When the second abnormality has occurred, the fuel injection valve 10 cannot inject. In this case, after the cause of the second abnormality is removed, the abnormality determination process is performed again, and the abnormality of the other fuel injection valve 10 is determined.

On the other hand, as shown by the solid line F2 in FIG. 2C, a positive determination is made when the pressure waveform Pw includes the injection waveform for all of the plurality of fuel injection valves 10. If affirmative determination is made in step S48, the fuel pressure P of each fuel injection valve 10 is set to a predetermined second required fuel pressure Ptg2 in step S52. The predetermined second required fuel pressure Ptg2 is the fuel pressure P in the predetermined high-speed running state, and is, for example, 170 MPa. The predetermined high-speed running state means a state in which the vehicle speed is equal to or higher than the predetermined speed (for example, 80 km / h).

In the following steps S54 to 58, fuel is injected from the fuel injection valve 10, and it is determined whether the pressure waveform Pw associated with the injection includes the injection waveform. The processes of steps S54 to 58 are substantially the same as the processes of steps S42, 46, and 48 described above, and duplicate description will be omitted. In steps S48 and S58, the process proceeds to step S60 on condition that the pressure waveform Pw includes the injection waveform for all of the plurality of fuel injection valves 10, and it is determined whether or not the fuel injection valve 10 needs to be replaced.

In step S60, the representative value ΔTQr of the injection correction time ΔTQ is selected for each fuel injection valve 10. The representative value ΔTQr is selected from the injection correction times ΔTQ stored in a plurality of areas in the learning map. Specifically, among the plurality of injection correction times ΔTQ stored for each area, the largest injection correction time ΔTQmax is selected as the representative value ΔTQr.

In step S62, for each fuel injection valve 10, it is determined whether the representative value ΔTQr selected in step S60 is larger than the first threshold value Le1. A negative determination is made when the representative value ΔTQr is smaller than the first threshold value Le1 for all of the plurality of fuel injection valves 10. If a negative determination is made in step S62, the exchange determination process ends.

On the other hand, when the representative value ΔTQr is larger than the first threshold value Le1 for any one of the plurality of fuel injection valves 10, a positive determination is made. If affirmative determination is made in step S62, the process proceeds to step S63, and the fuel injection valve 10 whose representative value ΔTQr is determined to be larger than the first threshold value Le1 in step S62 is determined to be a replacement target. That is, it is determined that the fuel injection valve 10 is to be replaced based on the fact that the representative value ΔTQr is larger than the first threshold value Le1. In the present embodiment, the process of step S62 corresponds to the "first determination unit".

In a subsequent step S64, a fuel injection valve (hereinafter referred to as a non-abnormal fuel injection valve) 10 other than the fuel injection valve 10 determined in step S62 to have a representative value ΔTQr larger than the first threshold value Le1 is selected in step S60. It is determined whether the representative value ΔTQr is larger than the predetermined second threshold value Le2. The predetermined second threshold value Le2 is a period smaller than the first threshold value Le1, and the representative value ΔTQr is the first threshold value when the vehicle is used for a predetermined period (for example, half a year or a period in which the vehicle travels 10,000 km). It is a period that is expected to be larger than Le1.

In step S64, it is determined whether the representative value ΔTQr is larger than the second threshold value Le2 for each non-abnormal fuel injection valve 10, and based on this determination, it is determined whether to replace each non-abnormal fuel injection valve 10. Judgment (S66, S68). Specifically, if an affirmative determination is made in step S64, the non-abnormal fuel injection valve 10 determined in step S64 that the representative value ΔTQr is larger than the second threshold value Le2 is determined to be a replacement target, and a replacement determination is made. End the process. That is, if the representative value ΔTQr is larger than the second threshold value Le2, it is determined that the fuel injection valve 10 is to be replaced.

On the other hand, if a negative determination is made in step S64, the non-abnormal fuel injection valve 10 determined in step S68 that the representative value ΔTQr is smaller than the second threshold value Le2 is replaced with the fuel injection valve 10 (hereinafter, non-replacement target). It is determined that it is an exchange target), and the exchange determination process is terminated. That is, if the representative value ΔTQr is smaller than the second threshold value Le2, it is determined that the fuel injection valve 10 is not replaced. In the present embodiment, the processes of steps S66 and S68 correspond to the "second determination unit".

Subsequently, FIG. 6 shows an example of the determination result of the abnormality determination process. FIG. 6 shows the determination results in the two cases shown in (a) and (b). In FIG. 6, the representative value ΔTQr corresponding to the fuel injection valves 10 of the cylinders # 1 to # 4 is shown as “◯” when the representative value ΔTQr is larger than the threshold values Le1 and Le2, and smaller than the threshold values Le1 and Le2. "X" is shown, and those that are not the judgment target are shown as "-". Further, in FIG. 6, those in which the fuel injection valves 10 of the cylinders # 1 to # 4 are determined to be replacement targets are indicated by "○", and those determined to be non-replacement targets are indicated by "x". Has been done.

FIG. 6A shows a determination result when there is not much difference in the increase speed of the injection correction time ΔTQ of the fuel injection valves 10 of each cylinder # 1 to # 4. In this case, as shown in FIG. 7A, the representative value ΔTQr corresponding to the cylinder # 1 is larger than the first threshold value Le1, and the representative value ΔTQr corresponding to the cylinders # 2 to # 4 is larger than the first threshold value Le1. It is slightly smaller and larger than the second threshold value Le2 (see timing t in FIG. 8).

As shown in FIG. 8, the injection correction time ΔTQ increases monotonically with the operating period of the engine. Therefore, in the case shown in FIG. 6A, when only the fuel injection valve 10 of the cylinder # 1 is replaced, as shown by the broken line in FIG. 7A, when the vehicle is used for a predetermined period of time, The representative value ΔTQr corresponding to the cylinders # 2 to # 4 becomes larger than the first threshold value Le1, and it becomes necessary to replace the fuel injection valve 10 of the cylinders # 2 to # 4. That is, the replacement of the fuel injection valve 10 becomes frequent.

According to the present embodiment, in the case shown in FIG. 6A, all of the fuel injection valves 10 of the cylinders # 1 to # 4 are determined to be replaced, so that the fuel injection valves 10 are frequently replaced. Is suppressed.

FIG. 6B shows a determination result when there is a difference in the increase speed of the injection correction time ΔTQ of the fuel injection valves 10 of the cylinders # 1 to # 4. In this case, as shown in FIG. 7B, the representative value ΔTQr corresponding to the cylinder # 1 is larger than the first threshold value Le1, and the representative value ΔTQr corresponding to the cylinders # 2 to # 4 is larger than the second threshold value Le2. small.

Therefore, as shown by the broken line in FIG. 7B, the representative value ΔTQr corresponding to the cylinders # 2 to # 4 does not become larger than the first threshold value Le1 even when the vehicle is used for a predetermined period. Therefore, in the case shown in FIG. 6B, if all the fuel injection valves 10 of the cylinders # 1 to # 4 are replaced, the fuel injection valves 10 of the cylinders # 2 to # 4 can still be used. Instead, it will be replaced in vain.

According to the present embodiment, in the case shown in FIG. 6B, only the fuel injection valve 10 of the cylinder # 1 is determined to be replaced, so that the fuel injection valve 10 is suppressed from being replaced unnecessarily. ..

According to the present embodiment described above, the following effects are obtained.

In the present embodiment, when the injection correction time ΔTQ of a certain fuel injection valve 10 is larger than the first threshold value Le1 and it is determined that the fuel injection valve 10 is to be replaced, the injection correction of the non-abnormal fuel injection valve 10 is performed. If the time ΔTQ is larger than the second threshold Le2, it is determined that the non-abnormal fuel injection valve 10 is to be replaced (see FIG. 6A). As a result, the fuel injection valves 10 whose injection correction time ΔTQ has increased to near the first threshold value Le1 can be replaced together, and the replacement frequency of the fuel injection valve 10 can be suppressed. Further, if the injection correction time ΔTQ of the non-abnormal fuel injection valve 10 is smaller than the second threshold value Le2, it is determined that the non-abnormal fuel injection valve 10 is not replaced (see FIG. 6B). As a result, it is possible to prevent the fuel injection valve 10 whose injection correction time ΔTQ has not increased to near the first threshold value Le1 from being replaced unnecessarily. This makes it possible to appropriately determine whether or not the fuel injection valve 10 needs to be replaced.

Here, the injection correction time ΔTQ differs depending on the required injection amount Qk and the fuel pressure P. In the present embodiment, the injection correction time ΔTQ is stored for each of a plurality of regions defined by the required injection amount Qk and the fuel pressure P. Therefore, it is possible to appropriately determine whether or not the fuel injection valve 10 needs to be replaced based on the injection correction time ΔTQ corresponding to the required injection amount Qk and the fuel pressure P.

In particular, in the present embodiment, the largest injection correction time ΔTQ among the injection correction times ΔTQ stored in the plurality of regions is selected as the representative value ΔTQr, and the fuel injection valve 10 is replaced based on this representative value ΔTQr. Judge the necessity. Therefore, it is possible to accurately determine whether or not the fuel injection valve 10 needs to be replaced based on the largest injection correction time ΔTQ.

The injection correction time ΔTQ is calculated from the actual injection amount Qr. Therefore, when the fuel injection valve 10 has an opening abnormality or a closing abnormality due to foreign matter mixing or the like, fuel cannot be injected from the fuel injection valve 10, so that the actual injection amount Qr cannot be calculated. The injection correction time ΔTQ cannot be calculated.

In the present embodiment, it is determined whether or not the fuel injection valve 10 needs to be replaced on condition that it is determined that an injection waveform such as a falling waveform Wn or a falling waveform Wd is observed in the pressure waveform Pw.

It is also possible that the difference ΔQ between the required injection amount Qk and the actual injection amount Qr is caused by factors other than clogging of the injection hole 11b due to the accumulation of the deposit in the injection hole 11b. In this case, if the cause is other than the clogging of the injection hole 11b, it is considered that the pressure waveform Pw associated with the fuel injection may not be observed correctly.

In this regard, in the present embodiment, it is determined that the condition for determining whether or not the fuel injection valve 10 needs to be replaced is that an injection waveform such as a falling waveform Wn or a falling waveform Wd is observed in the pressure waveform Pw. And said. As a result, it is possible to accurately determine whether or not the fuel injection valve 10 needs to be replaced in a situation where the difference ΔQ is generated due to the clogging of the injection hole 11b.

(Second Embodiment)
Next, the fuel injection system 100 according to the second embodiment will be described with reference to FIG. The fuel injection system 100 according to the second embodiment has a different abnormality determination process from the fuel injection system 100 according to the first embodiment. Hereinafter, the abnormality determination process of the second embodiment will be described.

As shown in FIG. 9, the difference between the abnormality determination process of the second embodiment and the abnormality determination process of the first embodiment is that the abnormality determination process is not divided into the abnormality detection process and the exchange determination process, and is one. It is a point that it is a continuous process and a point that the first abnormality and the second abnormality are not determined. In FIG. 9, the same contents as those described in FIGS. 3 and 5 above will be omitted.

The abnormality detection process is repeatedly performed by the ECU 30 while the engine is being driven. In the abnormality detection process, when the MIL is turned on in step S26, the process proceeds to step S60 to determine whether or not the fuel injection valve 10 needs to be replaced. When the vehicle is brought into the service station by the user due to the lighting of the MIL, the dedicated control device at the service station reads the determination result of the abnormality determination process from the ECU 30 and identifies the exchange target.

As described above, in the present embodiment, it is possible to determine the exchange target before the vehicle is brought to the service station by the user. This makes it possible to determine at an early stage whether or not the fuel injection valve 10 needs to be replaced.

The present invention is not limited to the description of the above embodiment, and may be implemented as follows.

An example is shown in which the actual injection amount Qr is calculated from the injection rate waveform Qw, but the present invention is not limited to this. For example, the actual injection amount Qr may be calculated from the engine rotation speed (instantaneous rotation speed) accompanying the increase / decrease in the cylinder volume caused by the combustion of each of the cylinders # 1 to # 4.

An example is shown in which the injection correction time ΔTQ is a correction value of the injection time TQ that correlates with the difference ΔQ between the required injection amount Qk and the actual injection amount Qr, but the present invention is not limited to this. The injection correction time ΔTQ may be the difference ΔQ itself or may be a correction value of the fuel pressure P that correlates with the difference ΔQ.

Determining whether the representative value ΔTQr is larger than the first threshold value Le1 for each fuel injection valve 10 is not limited to comparing each of the representative values ΔTQr in each fuel injection valve 10 with the first threshold value Le1. For example, the largest representative value ΔTQr may be selected from a plurality of representative values ΔTQr selected for each fuel injection valve 10, and the largest representative value ΔTQr may be compared with the first threshold value Le1. As a result, the processing load of the abnormality determination process can be reduced as compared with the case where each of the representative values ΔTQr in each fuel injection valve 10 is compared with the first threshold value Le1.

An example is shown in which the learning map is divided into a plurality of regions defined by the required injection amount Qk and the fuel pressure P, but the learning map is not limited to this. The learning map may be divided into a plurality of regions defined by one of the required injection amount Qk and the fuel pressure P.

An example is shown in which the representative value ΔTQr is the largest injection correction time ΔTQ among a plurality of injection correction times ΔTQ stored for each of a plurality of regions defined by the required injection amount Qk and the fuel pressure P. Not limited. The representative value ΔTQr may be an average value of a plurality of injection correction times ΔTQ stored for each of the plurality of regions, or may be an intermediate value.

Further, the representative value ΔTQr may be the largest injection correction time ΔTQ among the plurality of injection correction times ΔTQ stored in a predetermined specific region among the plurality of regions. The predetermined specific process is an area frequently used by the user in a vehicle, for example, a high-speed traveling state. As a result, it is possible to accurately determine whether or not the fuel injection valve 10 needs to be replaced based on the injection correction time ΔTQ in a specific region that is frequently used by the user.

An example is shown in which the exchange determination process is performed by the ECU 30 that receives an instruction from a dedicated control device in the service station, but the present invention is not limited to this. For example, the exchange determination process may be performed by a dedicated control device in the service station. In this case, the combination of the ECU 30 and the dedicated control device in the service station corresponds to the abnormality determination device.

ΔTQ ... Injection correction time, 10 ... Fuel injection valve, 100 ... Fuel injection system, Le1 ... First threshold value, Le2 ... Second threshold value, Qk ... Required injection amount, Qr ... Actual injection amount.

Claims (4)

It is applied to a fuel injection system (100) provided with a plurality of fuel injection valves (10) for injecting fuel into an internal combustion engine.
For each fuel injection valve, an actual injection amount calculation unit (S16) for calculating an actual injection amount (Qr) at the time of fuel injection, and
For each fuel injection valve, a deviation amount calculation unit (S20) that calculates the difference between the actual injection amount and the required injection amount (Qk) or a correlation value thereof as an injection deviation amount (ΔTQ).
For each fuel injection valve, a first determination unit (S63) for determining that the fuel injection valve should be replaced based on the fact that the injection deviation amount is larger than the first threshold value (Le1).
When it is determined by the first determination unit that any one of the plurality of fuel injection valves should be replaced, the injection deviation amount of the fuel injection valves other than the fuel injection valve is smaller than the first threshold value. If it is larger than the second threshold value (Le2), it is determined that the fuel injection valve is to be replaced, and if the injection deviation amount is smaller than the second threshold value, it is determined that the fuel injection valve is not replaced. 2 Judgment unit (S66, S68) and
A fuel injection valve abnormality determination device. A storage unit (for each fuel injection valve) that stores the injection deviation amount calculated by the deviation amount calculation unit in the corresponding region among a plurality of regions defined by at least one of the required injection amount and the fuel pressure. Equipped with S22)
The fuel injection valve according to claim 1, wherein the first determination unit and the second determination unit determine whether or not the fuel injection valve needs to be replaced based on the injection deviation amount stored by the storage unit. Abnormality determination device. The first determination unit and the second determination unit indicate whether or not the fuel injection valve needs to be replaced based on the largest injection deviation amount (ΔTQr) among the injection deviation amounts stored in the plurality of regions. The abnormality determination device for the fuel injection valve according to claim 2. The fuel injection system is provided for each fuel injection valve and includes a fuel pressure sensor (20) for detecting the fuel pressure supplied to each fuel injection valve.
The pressure waveform (Pw) of the fuel pressure detected by the fuel pressure sensor is acquired for each fuel injection valve, and the rising waveform and the falling waveform corresponding to the drive signal of the fuel injection valve are observed in the pressure waveform. It is equipped with a waveform determination unit (S48, S58) that determines whether the fuel is fueled.
The first determination unit and the second determination unit determine that the fall waveform and the fall waveform corresponding to the drive signal are observed by the waveform determination unit for all of the plurality of fuel injection valves. The abnormality determination device for a fuel injection valve according to any one of claims 1 to 3, wherein the fuel injection valve needs to be replaced on the condition that the fuel injection valve needs to be replaced.

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