JPH084577A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PURPOSE:To detect to which injection valve abnormality not to inject a given amount of fuel occurs by deciding whether or not abnormality occurs to each injection valve through comparison of a fuel pressure lowering amount, estimated by an estimating means, with an actual fuel pressure lowering amount detected by a pressure detecting means. CONSTITUTION:A fuel pressure PA in a pressure accumulating chamber 2 right before an opening command for a corresponding injection valve and a fuel pressure PB right after a closing command are detected by a pressure sensor 11. By subtracting PB from PA, a pressure lowering amount DELTAPn is calculated. From a total sum of a fuel pressure lowering amount in the heat accumulating chamber 2 during steady operation and a correction amount during transient operation, a fuel pressure lowering amount DELTAP' in the pressure accumulating chamber 2 owing to injection of fuel is assumed. It is decided whether or not a pressure lowering amount DELTAPn below an assuming value DELTAP' by a value exceeding a first given amount k1 decided by taking a measurement and calculation error and other allowable amount into consideration. When it is YES, it is decided that abnormality occurs to an injection valve (n) executing the fuel injection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine.

[0002]

2. Description of the Related Art A general fuel injection device for an internal combustion engine has an injection valve provided for each cylinder, a pressure accumulating chamber common to each injection valve, and a fuel in the pressure accumulating chamber maintained at a predetermined pressure. A fuel pump for pumping fuel to the accumulator;
By controlling the opening period of each injection valve, a desired amount of fuel is injected at a predetermined pressure into the intake passage or cylinder of the internal combustion engine by controlling the valve opening period.

In such a fuel injection device, if the flow rate characteristic of the injection valve changes beyond the allowable range, the desired amount of fuel is not injected, so the desired air-fuel ratio is not realized, exhaust emission deterioration and output fluctuation. Is brought about. Such a change in the flow rate characteristic of the injection valve is gradually brought over time, such as deposit adhesion to the injection valve in a cylinder injection internal combustion engine, foreign matter clogging, a valve closing stick of the injection valve, Or, there is a sudden thing like the opening stick of the injection valve, and it is rare for all injection valves to occur at the same time, so there is an abnormality that a desired amount of fuel is not injected in any injection valve. It is necessary to detect whether or not it is occurring and take measures against the corresponding injection valve.

To this end, in Japanese Patent Laid-Open No. 62-186036, a gear type volume flow meter or a hot wire type mass flow meter is installed in each injection valve to monitor the flow rate characteristic of each injection valve. Then, what detects the above-mentioned abnormality of the injection valve is described.

[0005]

The above-mentioned prior art can reliably detect in which injection valve the above-mentioned abnormality has occurred, but since a flow meter is provided for each injection valve, In an internal combustion engine having a large number of cylinders, considerable cost increase is required.

Therefore, an object of the present invention is to provide a fuel injection device for an internal combustion engine capable of reliably detecting in which injection valve an abnormality occurs in which a desired amount of fuel is not injected with almost no increase in cost. Is to provide.

[0007]

A first fuel injection device for an internal combustion engine according to the present invention is an injection valve provided for each cylinder, a pressure accumulating chamber for supplying fuel to each injection valve, Pressure detecting means for detecting the fuel pressure in the pressure accumulating chamber, and pressure-feeding fuel to the pressure accumulating chamber so as to maintain the fuel pressure in the pressure accumulating chamber near a predetermined value based on the fuel pressure detected by the pressure detecting means. The fuel pressure feeding means, the estimating means for estimating the fuel pressure drop amount in the pressure accumulating chamber from immediately before the valve opening command to immediately after the valve closing command at the time of fuel injection of each injection valve, and the estimating means. Determining means for comparing the fuel pressure drop amount and the actual fuel pressure drop amount detected by the pressure detecting means to determine whether or not an abnormality has occurred in each injection valve. Characterizing

A second fuel injection device for an internal combustion engine according to the present invention is the fuel injection device for a first internal combustion engine according to the first fuel injection device, further comprising: In a steady operation of the engine in which fuel injection by the injection valve is not performed, the actual fuel pressure drop amounts of the respective fuel injection valves detected by the pressure detection means are compared with each other to give the maximum fuel pressure drop amount. And a correction means for correcting the valve opening period of each of the injection valves so that the fuel pressure drop amount of each of the other injection valves is made to match the maximum fuel pressure drop amount.

A third fuel injection device for an internal combustion engine according to the present invention is the fuel injection device for a first internal combustion engine described above, wherein the determination means is an actual fuel pressure drop detected by the pressure detection means. When the amount falls below the fuel pressure drop amount estimated by the estimating means to a first predetermined amount or more, it is determined that an abnormality has occurred in the injection valve that has performed this fuel injection.

A fourth fuel injection device for an internal combustion engine according to the present invention is the fuel injection device for a first internal combustion engine described above, wherein the determination means is an actual fuel pressure drop detected by the pressure detection means. When the amount exceeds the fuel pressure drop amount estimated by the estimating means by a second predetermined amount or more, it is determined that an abnormality has occurred in the injection valve that has performed the fuel injection immediately before the fuel injection. And

[0011]

In the first fuel injection device for the internal combustion engine, the estimating means determines the fuel pressure drop amount in the pressure accumulating chamber from immediately before the valve opening command to immediately after the valve closing command at the time of fuel injection of each injection valve based on the engine state. The amount of fuel injected from the pressure accumulating chamber and the fuel in the pressure accumulating chamber are estimated by the estimating unit by comparing the actual fuel pressure change amount detected by the pressure measuring unit with the fuel pressure decrease amount estimated by the estimating unit. The fact that there is a proportional relationship with the pressure drop amount is used to determine whether or not an abnormality has occurred in each injection valve.

The above-mentioned fuel injection device for the second internal combustion engine is
In the first fuel injection device, the correction unit further includes a fuel pressure drop in the pressure accumulating chamber from immediately before the valve opening command to immediately after the valve closing command in the fuel injection of each injection valve detected by the pressure detection unit during the engine steady operation. To compare the amounts with each other and to correct the opening period of each of these injection valves so that the fuel pressure drop amount in each injection valve other than the injection valve that gives the maximum fuel pressure drop amount matches the maximum fuel pressure drop amount. In addition, even if the flow rate characteristics of any injection valve drop over time, the same amount of fuel of the desired amount is injected from all injection valves, and the correction of any of the injection valves exceeds the limit, or all injections are performed. The normal operation of the engine is realized and the occurrence of abnormality of each injection valve is delayed until the flow rate characteristic of the valve falls below the allowable range.

The fuel injection device for the third internal combustion engine described above is
In the fuel injection device for the first internal combustion engine, the actual fuel pressure drop amount detected by the pressure detection means by the determination means is the fuel pressure drop amount estimated by the estimation means.
When the amount is less than the predetermined amount, it is determined that the amount of fuel injected by this fuel injection is less than the desired amount, and it is determined that an abnormality has occurred in the injection valve that has performed this fuel injection.

The above-mentioned fourth fuel injection device for an internal combustion engine is
In the fuel injection device for the first internal combustion engine, when the actual fuel pressure drop amount detected by the pressure detection means by the determination means exceeds the fuel pressure drop amount estimated by the estimation means by the second predetermined amount or more, Assuming that the fuel injection is being performed simultaneously by the other injection valves, it is determined that the fuel injection valve that has performed the fuel injection immediately before this fuel injection has an abnormality that does not close.

[0015]

1 is a schematic diagram showing a fuel injection system for an internal combustion engine according to the present invention. This fuel injection device is for a four-cylinder internal combustion engine. In the figure, 1a to 1d
Is an injection valve provided for each cylinder, and each injection valve 1a ...
1d is connected to the pressure accumulating chamber 2. The pressure accumulating chamber 2 is provided with a pressure sensor 11 for measuring the fuel pressure therein. Reference numeral 3 denotes a fuel pressure feed pump that is driven in synchronization with the engine crankshaft, and has two pressure feed chambers 3a, 3a.
b is the fuel pressure feed passage 4 via the check valves 3c and 3d, respectively.
Is connected to the pressure accumulating chamber 2 by means of which fuel is pressure-fed to the pressure accumulating chamber 2 at every 360 ° crank angle. A fuel tank 5 is connected to the fuel pressure pump 3 by a fuel supply passage 6, and the fuel supply passage 6 is connected to the fuel pump 6.
a and a filter 6b, the downstream side of the filter 6b is communicated with the fuel tank 5 by the return passage 6c, and the fuel purified by the filter 6b is predetermined by the pressure regulator 6d that opens the return passage 6c at a predetermined pressure. The fuel pressure pump 3 is supplied at a pressure.

Reference numeral 10 controls the valve opening timing and period of each of the injection valves 1a to 1d, and also each pressure feeding chamber 3 of the fuel pressure feeding pump 3 so as to maintain the fuel pressure in the pressure accumulating chamber 2 near a predetermined value.
a, 3b is a control device for controlling the fuel pressure feed amount,
Each sensor for grasping the engine operating state, for example, a rotation sensor (not shown) for detecting the engine speed, an air flow meter (not shown) for detecting the intake air amount, a cooling water temperature as the engine temperature A pressure sensor 11 for measuring the fuel pressure in the pressure accumulating chamber 2 is connected in addition to a water temperature sensor (not shown) for detecting.

In addition to the above-mentioned general control, the control device 10 follows the flow chart shown in FIG.
The abnormality in which the desired amount of fuel is not injected in 1d is determined. This flowchart is started before fuel injection into a specific cylinder and repeated before fuel injection into each cylinder. The flowchart will be described below.

First, in step 101, the count value n, which is initially reset to 0, is incremented by 1. Next, in step 102, it is judged whether the count value n is 5 or more, and this judgment is denied. If it is, the count value n is set to 1 in step 103 when it is affirmed, and the routine proceeds to step 104. The count value n is used to determine which injection valve the current flow is, and when n is 1, it is determined that the injection valve is the injection valve of the specific cylinder, and n is 2 or 3. ,
And 4, it is determined that the injection valves are the cylinders of the second, third, and fourth ignition timings from the specific cylinder in order.

In step 104, the rotation sensor detects the engine speed NA immediately before the valve opening command in the fuel injection of the corresponding injection valve, and in step 105, the pressure sensor 11 immediately before the valve opening command in the fuel injection of the corresponding injection valve. The fuel pressure PA in the pressure accumulating chamber 2 is detected, and in step 106, the engine speed NB immediately after the command to close the corresponding injection valve is detected by the rotation sensor.
At 07, the pressure sensor 11 detects the fuel pressure PB in the pressure accumulating chamber 2 immediately after the command to close the corresponding injection valve, and at step 108, PB is subtracted from PA to calculate each fuel pressure drop amount ΔPn. This fuel pressure drop Δ
For Pn, for example, in an engine operating state in which fuel injection and fuel pressure feeding timing by the fuel pressure pump 3 to the pressure accumulating chamber 2 overlap, the fuel pressure in the pressure accumulating chamber 2 may increase after fuel injection. Sometimes it is a negative value.

Next, the routine proceeds to step 109, where it is judged whether or not the fuel quantity increase which is generally carried out with the intention of early warm-up and stable combustion is being carried out at the time of engine start. The routine proceeds to 110, where it is judged whether or not the engine is in idle operation. When the judgment is affirmative, it means that the engine is in a relatively low speed steady operation state, and the routine proceeds to step 111.

In step 111, after the fuel pressure drop amounts ΔP1, ΔP2, ΔP3, and ΔP4 in the accumulator 2 from immediately before the valve opening command to immediately after the valve closing command in the fuel injection of each injection valve are calculated in step 108. , The maximum fuel pressure drop amount ΔPmax among them is determined, and this maximum fuel pressure drop amount ΔPmax is set to each fuel pressure drop amount ΔPn.
The valve opening period increase coefficient an for each injection valve divided by
(This coefficient of the injection valve that gives the maximum fuel pressure drop amount ΔPmax is 1) is calculated. At this time, each fuel pressure drop amount ΔP1, ΔP2, ΔP3, and ΔP4 is determined by each injection valve 1
If the desired fuel injection amount in a to 1d is equal and each fuel injection timing is different from the fuel pressure feeding timing by the fuel pressure feeding pump 3 and is not influenced by it, all the same values are obtained unless the flow rate characteristics of each injection valve drop. The valve opening period increase coefficient an of each injection valve becomes 1.

Next, at step 112, it is judged whether or not the valve opening period increase coefficient an for each injection valve has reached the correction limit value A determined by the fuel injection timing and the like. When affirmative, step 113 is set as the correction limit value and step 1
14, in the normal valve opening period control, the valve opening period τ determined according to the engine operating state is corrected by being multiplied by the valve opening period increasing coefficient an determined for each injection valve. Fuel injection from the next time is performed based on the valve opening period τ '. The valve opening period increase coefficient an for each injection valve is updated every engine idle state in which the fuel amount increase is not executed.

Here, between the fuel pressure drop amount ΔP and the fuel injection amount Q in the pressure accumulating chamber from immediately before to immediately after the fuel injection, Δ
Since there is a relation of P = K * Q / V (the bulk modulus K of the fuel and the high-pressure side fuel storage volume V are constants), the fuel pressure drop amounts ΔP1, ΔP2, ΔP3, and ΔP4 of each injection valve are
It is a value proportional to the fuel injection amount of each injection valve in the predetermined valve opening period in this engine operating state. Therefore, when all of the fuel pressure drop amounts ΔP1, ΔP2, ΔP3, and ΔP4 of each injection valve do not match the same value, at least the injection valve other than the injection valve that gives the maximum value has a time lapse due to adhesion of deposits or the like. Since the flow passage diameter is narrowed and the required amount of fuel is not injected, the valve opening period is corrected to match the fuel injection amount of the injection valve that gives the maximum value.

Of course, one of the valve opening period increase factors a
When n reaches the correction limit, if a deposit adheres to the injection valve and to all of the injection valves beyond the allowable range, a required amount of fuel is not injected in each injection valve, and an abnormality after step 115 described later is generated. The judgment process detects an abnormality of the corresponding injection valve, but each injection valve injects the required amount of fuel at least from the time when a slight deposit is deposited on one injection valve to the above-mentioned state. It is possible to delay the occurrence of abnormality of each injection valve in which the desired air-fuel ratio is not realized.

When the determination in step 109 is affirmative or the determination in step 110 is negative,
That is, when the operating state is other than the idle operation after the fuel amount increase, the routine proceeds to step 115, where the abnormality determination processing of each injection valve is executed. Step 115
At, the values M1 and M2 are determined from the first and second maps shown in FIG. 3, and the sum of the values M1 and M2 is used to estimate the fuel pressure drop amount in the accumulator 2 due to the current fuel injection of the corresponding injection valve. The first map is a two-dimensional map of the engine speed NA immediately before fuel injection and the desired fuel injection amount determined by the current engine operating state, and the value M1 is a steady state in which the engine speed NA is maintained immediately after fuel injection. The amount of fuel pressure drop in the accumulator 2 during operation is shown. From the above-mentioned relationship, the value M1 is set to increase as the fuel injection amount increases and the engine speed NA decreases.

The second map is a two-dimensional map of the engine speed NA immediately before the fuel injection and the engine speed NB immediately after the fuel injection.
The value M2 indicates the amount of correction of M1 during transient operation. The value M2 becomes 0 during the steady operation in which the engine speed NA immediately before the fuel injection and the engine speed NB immediately after the fuel injection are equal, and when the engine speed NA immediately before the fuel injection is higher than the engine speed NB immediately after the fuel injection, the value M2 becomes The larger the difference is, the larger the positive value becomes, and when the engine speed NA immediately before the fuel injection is smaller than the engine speed NB immediately after the fuel injection, the larger the difference is, the smaller the negative value becomes.

The fuel pressure drop amount ΔP 'in the pressure accumulating chamber thus estimated is an accurate value in all engine operating states including transient times such as engine acceleration / deceleration. The fuel pressure drop amount ΔPn actually measured by 11 indicates the estimated value ΔP ′ by the first predetermined amount k.
It is determined whether or not it falls below 1 or more.

The first predetermined value k1 is a value determined in consideration of the measurement and calculation error and the allowable amount of the drop in the flow characteristic of the injection valve, and when the determination in step 116 is affirmative, the routine proceeds to step 117. In the injection valve (n) that has performed this fuel injection, adhesion beyond the allowable range of deposit, clogging of foreign matter, valve closing stick, etc. occur,
It is determined that an abnormality has occurred in which only less than the desired amount of fuel has been injected.

On the other hand, when the determination in step 116 is negative, the routine proceeds to step 118, where it is determined whether the flag F is 1. Initially, this determination is denied and the routine proceeds to step 119, where it is determined whether or not the fuel pressure drop amount ΔPn measured by the pressure sensor 11 exceeds the estimated value ΔP ′ by a second predetermined amount k2 or more. The second predetermined amount k2 is considerably larger than the first predetermined value k1 described above, and when the determination in step 119 is affirmative, the process proceeds to step 120, and fuel injection is simultaneously performed by the other injection valves. As a result, in the injection valve (n-1) that has injected fuel immediately before this fuel injection, a valve opening stick that does not close even if a valve closing command is issued is generated,
It is determined that there is an abnormality that fuel continues to be injected. After that, since the flag F is set to 1 in step 121, once the determination in step 119 is affirmed, the determination in step 118 is affirmed from the next time.

Such a valve opening stick of the injection valve does not occur suddenly when the injection valve is closed, so that
When the determination in step 118 is affirmative, in the injection valve that has performed the fuel injection immediately before this fuel injection,
It can be concluded that the valve opening stick is occurring.

FIG. 4 shows a pressure accumulating chamber 2 formed by a fuel pressure pump.
A fuel pressure feed signal a to each injection valve, a valve opening signal b of each injection valve, a fuel pressure change c in the pressure accumulating chamber 2 when each injection valve is normal,
A time chart of a fuel pressure change d in the accumulator 2 when the injection valve of n = 2 is closed and a fuel pressure change e in the accumulator 2 when the injection valve of n = 2 is opened. Show. As shown in the time chart d, the pressure drop amount from immediately before the valve opening command to immediately after the valve closing command in the fuel injection in the injection valves other than n = 2 is the same as that in the time chart c. The judgment in
Only the injection valve of n = 2 is denied and it is judged that this injection valve is abnormal. Further, as shown in the time chart e, in the injection valve of n = 2 in which the valve opening stick is caused, the fuel pressure drop amount ΔP2 from immediately before the valve opening command to immediately after the valve closing command is calculated in steps 116 and 118. The determination is negative, and it is initially determined to be normal, but in the injection valve of n = 3, the fuel pressure drop amount ΔP3 becomes about twice the normal time, and the determination in step 118 is affirmed, and n =
The second injection valve is judged to be abnormal. Even in the case of the injection valves of n = 1 and 3, the fuel pressure drop amount is about twice as much as that in the normal time. Therefore, in order to prevent misjudgment, after one of the injection valves is judged to be an open valve stick, the step The judgment in 119 is not carried out.

As shown in the time charts a, b and c,
The fuel pressure pump 3 of this embodiment has a fuel pressure feeding end time of 36.
It is set for each 0 ° crank angle, and normally, fuel injection is performed by two injection valves from the end of one pressure feed to the start of the other pressure feed. However, as the engine speed increases, the crank angle range required to inject the same amount of fuel increases, for example, n = 3.
In the latter half of the injection period of the injection valve and the first half of the fuel pressure feeding period by the fuel pressure feeding pump 3, the fuel pressure drop amount in the pressure accumulating chamber due to the fuel injection becomes small, and such a phenomenon is considered in the first map described above. Has been done. In this embodiment, the degree of decrease in the fuel pressure drop amount at this time is n = 2 and n
= 4 injection valves and n = 1 and n = 3 injection valves are substantially equal to each other, but there is a large difference between them, so it is necessary to provide at least two types of first maps.

Such an abnormality determination process for each injection valve can of course be carried out in all engine operating states. However, in this embodiment, each idle valve is opened during idle operation after completion of fuel increase at startup. The valve time increase coefficient an is calculated, and the valve opening time of each injection valve is corrected next time. To prevent the abnormality of each injection valve from being judged before this correction, an abnormality judgment is made during the above-mentioned operation. It is designed not to be implemented.

[0034]

As described above, according to the fuel injection device for an internal combustion engine of the present invention, the fuel pressure drop amount in the pressure accumulating chamber and the fuel injection amount between immediately before the valve opening command and immediately after the valve closing command in the fuel injection are controlled. The estimating means estimates the fuel pressure drop amount in the fuel injection of each injection valve based on the engine state, and the determining means estimates the actual fuel pressure drop amount detected by the pressure detecting means. When the fuel pressure drop amount estimated by the means falls below the first predetermined amount or more, it is determined that the fuel amount injected from this fuel injection is less than the desired amount, and an abnormality occurs in the injection valve that has performed this fuel injection. When the actual fuel pressure drop amount detected by the pressure detection means exceeds the fuel pressure drop amount estimated by the estimation means by the second predetermined amount or more, another fuel injection valve is used to simultaneously inject fuel. Is performed, the pressure detection means generally provided in the pressure accumulating chamber for determining that the injection valve that has injected the fuel immediately before the fuel injection has an abnormality that does not close the valve. Can be used to accurately determine an abnormality in which a desired amount of fuel is not injected in each injection valve, and this abnormality determination does not require an increase in cost.

Further, the correction means is
Injecting fuel other than the injection valve that gives the maximum fuel pressure drop amount by comparing the fuel pressure drop amounts in the pressure accumulating chamber from immediately before the valve opening command to immediately after the valve closing command in the fuel injection of each injection valve detected by the pressure detection means. In order to match the fuel pressure drop in the valve with the maximum fuel pressure drop, in order to correct the opening period of each of these injection valves, unless the flow characteristic of at least one injection valve drops, the other injection valve Even if the flow characteristics of the fuel injection drop with time, the same amount of fuel of the desired amount is injected from all the injection valves, the correction of any of the injection valves exceeds the limit, or the flow characteristics of all the injection valves are allowed. It is possible to delay the occurrence of an abnormality in which the desired amount of fuel is injected until the desired air-fuel ratio is not achieved in each injection valve until it falls below the range.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a fuel injection device for an internal combustion engine according to the present invention.

FIG. 2 is a flowchart for determining abnormality of each injection valve.

3A and 3B are maps used in the flowchart of FIG. 2, where FIG. 3A shows a first map and FIG. 3B shows a second map.

FIG. 4 is a fuel pressure feeding signal to the pressure accumulating chamber by the fuel pressure feeding pump, a valve opening signal of each injection valve, a fuel pressure change in the pressure accumulating chamber when each injection valve is normal, and one injection valve is closed. 7 is a time chart of a fuel pressure change in the pressure accumulating chamber at the time and a fuel pressure change in the pressure accumulating chamber at the time when one injection valve opens the valve.

[Explanation of symbols]

 1a-1d ... Injection valve 2 ... Accumulation chamber 3 ... Fuel pressure pump 5 ... Fuel tank 10 ... Control device 11 ... Pressure sensor

Claims (4)

[Claims] 1. An injection valve provided for each cylinder, a pressure accumulating chamber for supplying fuel to each of the injection valves, pressure detection means for detecting a fuel pressure in the pressure accumulating chamber, and the pressure detection. Fuel pressure feeding means for feeding fuel to the pressure accumulating chamber so as to maintain the fuel pressure in the pressure accumulating chamber near a predetermined value based on the fuel pressure detected by the means, and a valve opening command at the time of fuel injection of each of the injection valves. The estimating means for estimating the fuel pressure drop amount in the pressure accumulating chamber from immediately before to immediately after the valve closing command based on the engine state, the actual fuel pressure drop amount detected by the pressure detecting means, and the estimating means estimated by the estimating means. A fuel injection device for an internal combustion engine, comprising: a determination unit that determines whether or not an abnormality has occurred in each injection valve by comparing the fuel pressure drop amount. 2. The fuel of each of the injection valves detected by the pressure detecting means during engine steady operation in which fuel injection by each of the injection valves is not performed while fuel is being sent by pressure to the accumulator by the fuel pressure sending means. The actual fuel pressure drop amounts at the time of injection are compared with each other, so that the fuel pressure drop amounts of the injection valves other than the injection valve that gives the maximum fuel pressure drop amount are matched with the maximum fuel pressure drop amount. The fuel injection device for an internal combustion engine according to claim 1, further comprising a correction unit that corrects the valve opening period of the above. 3. The fuel injection method according to claim 3, wherein when the actual fuel pressure drop amount detected by the pressure detection unit falls below the fuel pressure drop amount estimated by the estimation unit by a first predetermined amount or more. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein it is determined that an abnormality has occurred in the injection valve that has performed. 4. The fuel injection according to claim 4, wherein when the actual fuel pressure drop amount detected by the pressure detection unit exceeds the fuel pressure drop amount estimated by the estimation unit by a second predetermined amount or more, 2. The fuel injection device for an internal combustion engine according to claim 1, wherein it is determined that an abnormality has occurred in the injection valve that has injected fuel immediately before.