JPH07253041A - Fuel injection control device - Google Patents

Abstract

(57) [Summary] [Purpose] To prevent the fuel oil pressure from rising and exceeding the operating limit pressure of the fuel injection valve due to the rise in fuel oil temperature after the engine is stopped. [Structure] Fuel is supplied from a high-pressure pump 5 to a delivery pipe 3, and fuel is injected into each cylinder of an internal combustion engine by a fuel injection valve 1. The engine control circuit 20 estimates the maximum ultimate pressure of the fuel oil in the delivery pipe after the fuel injection is stopped based on the engine cooling water temperature and the outside air temperature, and when the estimated pressure exceeds the operating limit pressure of the fuel injection valve. Reduces the pressure in the delivery pipe by injecting fuel from the fuel injection valve into the cylinder when the engine is stopped.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In an internal combustion engine having a fuel injection device that injects pressurized fuel from a fuel injection valve and supplies it to each cylinder, bubbles are generated in the fuel system due to a rise in fuel oil temperature after the engine is stopped. Problems may occur that make restarting the engine difficult. That is, after the internal combustion engine is stopped, the fuel injection from the fuel injection valve is stopped, so that the flow in the fuel passage for supplying the fuel to the fuel injection valve is stopped and the fuel is retained. The fuel oil staying in the fuel passage thus rises in temperature due to the heat of the engine and the exhaust system, and when it reaches a certain temperature or higher, it vaporizes in the fuel passage and the fuel injection valve to form bubbles of fuel oil vapor. Will occur. However, when air bubbles are present in the fuel passage or the fuel injection valve when the engine is restarted, the fuel injection valve cannot inject the amount of fuel required for starting, and restarting becomes difficult. The problem of occurs. Particularly, in a vehicle engine or the like, after the engine is stopped (after the vehicle is stopped), the vehicle running wind is eliminated, so that the temperature rise in the engine room becomes large and vapor lock is likely to occur.

In order to prevent this vapor lock from occurring, for example, in the device disclosed in Japanese Patent Laid-Open No. 59-46360, a return pipe for returning excess fuel from the fuel passage to the fuel tank is provided so that the fuel pump can be operated even after the engine is stopped. By supplying the fuel to the fuel passage from the above and circulating it from the return pipe to the fuel tank, the bubbles generated in the fuel passage are discharged into the fuel tank.

Further, for example, in the device disclosed in Japanese Utility Model Laid-Open No. 62-119474, means for increasing the fuel pressure in the fuel passage when the engine is stopped is provided, and the pressure in the fuel passage after the engine is stopped is higher than the fuel vapor pressure. The pressure is raised to a pressure to prevent vaporization of the fuel in the fuel passage, thereby preventing the generation of bubbles.

[0005]

However, when the fuel in the fuel passage is circulated in the tank after the engine is stopped as in the device described in JP-A-59-46360, the engine is stopped after the engine is stopped. Since the fuel heated in the fuel passage flows into the tank, the temperature of the fuel in the tank rises, and the evaporation of the fuel in the tank causes a problem of increasing EVAPORATIVE EMISSION. Further, in this device, it is necessary to provide a return pipe that connects the fuel passage and the fuel tank in order to prevent generation of bubbles, and it is necessary to continue the operation of the fuel supply pump for a certain period even after the engine is stopped. However, there is a problem that the device becomes complicated.

On the other hand, in the device disclosed in Japanese Utility Model Laid-Open No. 62-119474, there is no need to provide a return pipe or the like as described above, and there is no problem such as an increase in evaporative emission, but the pressure in the fuel passage is increased. May cause problems. That is, as described above, after the engine is stopped, the temperature of the fuel oil in the fuel passage increases due to the heat of the engine and the exhaust system. Therefore, thermal expansion occurs in the fuel oil in the fuel passage. However, after the fuel injection is stopped, the outlet of the fuel passage is closed and the internal volume of the passage does not change. Therefore, the thermal expansion of the fuel oil in the passage increases the fuel oil pressure. Further, if the fuel oil pressure when the engine is stopped is high, the fuel oil pressure reached by thermal expansion is also high. Therefore, if the pressure in the fuel passage is increased when the engine is stopped as in the device of Japanese Utility Model Laid-Open No. 62-119474, the fuel oil pressure after the engine is stopped may become extremely high.

Generally, as the fuel injection valve, an internal open valve is used in which the valve element operates in a direction opposed to the internal fuel oil pressure when the valve is opened. However, when the engine is restarted in the state where the fuel oil pressure in the fuel passage is high after the engine is stopped as described above, the fuel oil pressure inside the valve acts on the valve body due to the driving force of the valve body. In some cases, the force will be greater. When such a state occurs, fuel cannot be injected from the fuel injection valve, and the engine cannot start.

In the above description, the fuel oil pressure is increased after the engine is stopped to prevent vapor lock. For example, in an engine equipped with an in-cylinder fuel injection valve for injecting fuel directly into a cylinder, a high pressure Since the fuel is injected into the cylinder, the fuel injection pressure is usually set to a relatively high pressure, and the pressure in the fuel passage is high during normal operation. Therefore, even if the fuel oil is not boosted when the engine is stopped, the fuel oil pressure increase after the engine is stopped may cause the above-described problem that the engine cannot be restarted.

If a so-called externally open valve of the type in which the valve body is closed in the direction against the internal pressure is used instead of the internally open valve, the above problem of inability to start does not occur, but with the externally open valve, on the contrary, the engine does not work. If the force in the valve opening direction acting on the valve body from the fuel oil becomes larger than the force in the valve closing direction due to the increase in fuel oil pressure after the stop, there arises a problem that the fuel injection valve suddenly opens naturally. If the outer valve is rapidly opened under high pressure in this way, a large pressure fluctuation occurs in the fuel passage due to the water hammer, and in extreme cases, components of the fuel system may be damaged.

On the other hand, if the return passage communicating with the fuel tank is provided in the fuel passage and the surplus fuel is discharged into the tank when the pressure in the fuel passage increases, as in the above-mentioned Japanese Patent Laid-Open No. 62-119474. Although it is possible to prevent the problem, in this case, as described above, there arises a problem that the device becomes complicated and the evaporative emission increases. Also, by increasing the size of the drive solenoid for the internal injection type fuel injection valve to increase the operating pressure limit of the fuel injection valve and increasing the biasing force of the closing spring of the external opening type fuel injection valve, Although it is possible to increase the valve opening pressure, it is not preferable because the fuel injection valve becomes large and the product cost increases.

In view of the above problems, it is an object of the present invention to provide a means for easily solving the above problems caused by an increase in fuel oil pressure accompanying a temperature increase after engine stop.

[0012]

According to the present invention as set forth in claim 1, a fuel passage for supplying pressurized fuel and a fuel injection valve for injecting the fuel in the fuel passage into a cylinder of an internal combustion engine. And a control means for controlling the fuel injection operation of the fuel injection valve, in a fuel injection control device for an internal combustion engine, based on an engine operating state when the engine is stopped, the inside of the fuel passage due to a temperature increase after the engine is stopped. The estimation means for estimating the maximum reached value of the fuel pressure, the control means, if the estimated maximum reached value of the pressure is a predetermined value or more, fuel injection from the fuel injection valve immediately after the engine is stopped. Is provided to reduce the pressure in the fuel passage.

According to the present invention as defined in claim 2,
2. The fuel injection system according to claim 1, wherein when the fuel injection is performed from the fuel injection valve when the engine is stopped, the control unit also ignites a cylinder to which fuel is supplied by the fuel injection valve that performs the fuel injection. A controller is provided. Further, according to the invention of claim 3, in claim 1, when the control means performs fuel injection from the fuel injection valve when the engine is stopped, both the intake valve and the exhaust valve are closed. There is provided a fuel injection valve control device in which fuel injection is performed only from the fuel injection valve of the cylinder that is valved.

[0014]

According to the present invention as set forth in claim 1, the maximum reached value of the fuel oil pressure estimated by the estimating means is the limit pressure at which the fuel injection valve of the internal opening type becomes inoperable or the maximum opening value of the external opening type. When the fuel injection valve is at a predetermined pressure or higher such as the limit pressure at which it will open naturally, the control means continues fuel injection even after the engine is stopped and lowers the fuel oil pressure in the fuel passage. Even if the fuel oil pressure rises, the fuel oil pressure does not reach the above limit pressure, and problems such as inoperability of the fuel injection valve and spontaneous valve opening do not occur.

According to the second aspect of the present invention, when the fuel injection is continued in the first aspect, the cylinder to which the fuel is supplied is also ignited. Therefore, the injected fuel burns in the combustion chamber and is normally Therefore, the evaporated fuel is prevented from being released to the outside. Further, in the present invention as set forth in claim 3, when the fuel injection is continued in claim 1, the fuel injection is performed only in the cylinder in which both the intake valve and the exhaust valve are closed. The fuel remains in the cylinder and burns at the next engine start. Therefore, the injected fuel is not released to the atmosphere as evaporated fuel,
Furthermore, at the time of restart, there is a cylinder in which the fuel surely exists in the combustion chamber, so that the engine can be started well.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a schematic configuration diagram of a fuel injection system of an internal combustion engine to which the present invention is applied. In FIG. 1, 1 is a fuel injection valve for directly injecting fuel into each cylinder of an internal combustion engine, 3
Is a delivery pipe for supplying pressurized fuel to the fuel injection valve 1,
Reference numeral 5 is a high-pressure diaphragm pump for sending fuel under pressure to the delivery pipe 3, 7 is a fuel tank, and 9 is a fuel feed pump.

During operation of the engine, the fuel in the tank 7 is boosted by the feed pump 9, passes through the filter 11 to remove foreign matters, and is pressurized by the pressure regulator 13 at a constant pressure (primary pressure, for example, about 0.3 MPa). After the pressure is adjusted to 1, it is supplied to the high-pressure diaphragm pump 5.
Further, the fuel discharged from the high pressure diaphragm pump 5 is supplied to the delivery pipe 3 through the check valve 15 and the high pressure pipe 17, and is injected from the delivery pipe 3 into each cylinder of the internal combustion engine through the fuel injection valve 1. To be done.

Reference numeral 20 in FIG. 1 denotes an engine control circuit (ECU) for controlling the engine. The ECU 20 is composed of a read-only memory (ROM), a random access memory (RAM), a microprocessor (CPU), and a digital computer having a known configuration in which input / output ports are connected by a bidirectional bus. The ECU 20 controls the stroke of the high-pressure diaphragm pump 5 to control the fuel oil pressure (secondary pressure) in the delivery pipe 3 according to the engine load, the number of revolutions, etc., and also opens the fuel injection valve 1. It controls the valve time to control the amount of fuel supplied to the cylinder, controls the ignition timing of the engine, and performs basic control of the engine. Further, in the present embodiment, the estimating means for estimating the maximum ultimate pressure of the fuel oil in the delivery pipe 3 after the engine is stopped, and the delivery pipe 3 by continuing the fuel injection after the engine is stopped, from the engine operating state when the engine is stopped. It functions as a control means for reducing the internal pressure.

Due to the above control, a voltage signal corresponding to the fuel pressure in the delivery pipe 3 is supplied from the fuel pressure sensor 31 provided in the delivery pipe 3 to the input port of the ECU 20, and the engine cooling water is supplied from the cooling water temperature sensor 33. A voltage signal corresponding to the temperature is input via the AD converter 34, and an air flow meter 35 provided in the engine intake passage
Similarly, signals corresponding to the intake air temperature and the engine intake air amount are similarly input via the AD converter 34. Further, at the input port of the ECU 20, two signals, a Ne pulse signal and a G pulse signal, which will be described later, are generated from a crank angle sensor 37 provided in a distributor (not shown) of the engine in accordance with the crank rotation angle. It has been entered.

The output port of the ECU 20 is connected to the fuel injection valve 1 via a drive circuit 40 to control the operation of each fuel injection valve 1 and also to drive the high pressure diaphragm pump 5 via the drive circuit 40. It is connected to a capacity control device and controls the discharge amount of the pump 5. The output port of the ECU 20 is connected to an ignition plug (not shown) of the engine via an ignition circuit 41 to control ignition of each cylinder.

In this embodiment, the ECU 20 determines the secondary fuel oil pressure in the delivery pipe 3 to be 5 during normal operation.
The pressure is controlled to about MPa. Therefore, when the operation is stopped (fuel injection is stopped), the fuel oil pressure in the delivery pipe 3 is about 5 MPa. When the operation of the engine is stopped in this state, the temperature of the fuel oil in the delivery pipe 3 rises due to the heat of the engine itself and the exhaust system, and the thermal expansion of the fuel oil causes the fuel oil pressure in the delivery pipe 3 to rise. To do.

FIG. 2 is a diagram for explaining the temporal change of the fuel oil pressure in the delivery pipe 3 after the engine is stopped. As shown in FIG. 2, after the engine is stopped, the fuel pressure in the delivery pipe 3 increases with time, and reaches a maximum value after a certain period of time. After that, the pressure inside the delivery pipe decreases as the engine cools. However, as described above, the fuel injection valve has an operating limit pressure (in the case of an internal opening valve) and a natural valve opening pressure (in the case of an external opening valve). For example, in the present embodiment, an internally open type fuel injection valve is used,
The operating limit pressure is about 7 MPa. For this reason, if the fuel pressure rises after the engine is stopped and a period (for example, section A in FIG. 2) that exceeds this operating limit pressure occurs, fuel injection cannot be performed within this period and the engine cannot be restarted. .

In this embodiment, when the engine is stopped, the maximum ultimate pressure in the delivery pipe 3 after the engine is stopped is estimated based on the engine cooling water temperature and the outside air temperature (engine intake temperature), and this estimated maximum When the pressure exceeds the operating limit pressure of the fuel injection valve, that is, when there is a period in which the engine cannot be restarted after the engine is stopped, fuel injection is performed immediately after the engine is stopped, as shown by the dotted line in FIG. The pressure reduction control is performed to reduce the pressure in the delivery pipe 3 to such an extent that the restart impossible period does not occur after the engine is stopped.

FIG. 3 shows the maximum ultimate pressure P _MAX of the fuel oil in the delivery pipe 3 after the engine is stopped and the engine cooling water temperature TH.
It is a figure which shows the relationship between W and outside temperature (intake air temperature) TATM. Figure 3 shows that the pressure inside the delivery pipe 3 before the engine is stopped is 5M.
The maximum ultimate pressure in the case of Pa is shown. As shown in FIG. 3, the maximum ultimate pressure P _MAX after the engine is stopped increases as the engine cooling water temperature THW at the time of stop is higher and the outside air temperature TATM is higher, and the cooling water temperature THW is equal to or higher than a certain limit value Te, and In the range where the outside air temperature TATM is above a certain limit value Ta (hatched portion in FIG. 3), the operating limit pressure (7M
Pa) will be exceeded.

In the present embodiment, when the cooling water temperature THW and the outside air temperature TATM are within the above ranges, a predetermined amount of fuel is injected from the fuel injection valve after the engine is stopped to lower the fuel oil pressure in the delivery pipe 3. However, the amount of fuel injected at the time of stop is set to the minimum amount necessary and sufficient to prevent the engine restart impossible period from occurring based on the cooling water temperature THW and the outside air temperature TATM. .

FIG. 4 is a diagram showing the relationship between the fuel injection amount when the engine is stopped, the cooling water temperature THW and the outside air temperature TATM. As shown in FIG. 4, the fuel injection amount TAU _RE for depressurization is set larger as the cooling water temperature THW is higher and the outside air temperature TATM is higher, corresponding to the maximum ultimate pressure in FIG. As a result, when the engine is stopped, the pressure in the delivery pipe 3 is significantly reduced as the maximum reached pressure of the fuel oil after the engine is stopped is higher. Therefore, the maximum reached pressure after the engine is stopped becomes the operation limit pressure of the fuel injection amount. It will not be exceeded, and it will be prevented that a restart impossible period will occur after the engine is stopped.

FIG. 5 is a flow chart showing the pressure reducing control operation. This routine is executed by the ECU 20 only once when the engine operation is stopped (when the ignition switch is turned off). When the ignition switch is turned off in FIG. 5, in step 501, E
Power off of CU20 is delayed and ignition is off
After that, the processing of step 503 and the subsequent steps can be executed.

Next, at step 503, the engine cooling water temperature THW is read from the sensor 33, and it is judged if the read THW is larger than the above-mentioned limit value Te or not. At step 505, it is judged from the intake air temperature sensor of the air flow meter 35. The outside temperature TATM is read and this T
It is determined whether ATM is larger than the above-mentioned limit value Ta.

If either of steps 503 and 505 is not established, the routine proceeds to step 515, where E
After turning off the power of the CU 20, the routine ends.
That is, as described with reference to FIG. 3, the maximum reached fuel oil pressure P _MAX after the engine is stopped exceeds the operating limit pressure of the fuel injection valve because both the cooling water temperature THW and the outside air temperature TATM exceed the above limit values. This is the case. Therefore, step 50
When either one of 3 and 505 is not established, the restart impossible period does not occur even if fuel injection for depressurization is not performed, so the routine is ended without executing steps 507 to 513.

If both steps 503 and 505 are satisfied, the routine proceeds to step 507, where the fuel injection amount TAU _RE for pressure reduction is calculated from the relationship of FIG. 4 based on the cooling water temperature THW and the outside air temperature TATM. Is determined. In the present embodiment, the relationship of FIG. 4 is stored in advance in the ROM of the ECU 20 in the form of a numerical map, and in step 507, the fuel injection amount TAU _RE for pressure reduction is read from this map.

Next, at step 509, the cylinder to which fuel injection for pressure reduction is to be performed is determined. This determination method will be described later. Further, after the above determination, in step 511, the fuel injection valve of the cylinder determined above is driven through the drive circuit 40, and fuel injection of the amount of TAU _RE is performed.
Further, following the above, as shown in FIG. 5 and step 513, if a discharge voltage is applied to the spark plug of the cylinder that has injected the fuel to burn the injected fuel, the injected fuel is evaporated fuel. Can be completely prevented from being released into the atmosphere.

After executing the above pressure reduction control, step 515
Then, the power supply of the ECU 20 is turned off, and this routine ends. In this embodiment, after the engine is stopped, the fuel injection for reducing the pressure is performed only when the fuel oil pressure exceeds the operating limit pressure of the fuel injection valve. The frequency of being done is relatively low.

Next, the determination of the fuel injection cylinder in step 509 will be described. The fuel injection for reducing the pressure may be performed to the cylinder that is to be next fuel-injected when the engine is stopped when the fuel-injection control during the engine operation is continued as it is. Depending on the timing, the intake valve or the exhaust valve of this cylinder may be opened, and the injected fuel evaporates after the engine is stopped and is discharged from the intake valve or the exhaust valve to the outside of the cylinder.
May be released into the atmosphere from the intake or exhaust passages. Therefore, when fuel injection is to be performed in the cylinder for which fuel injection is scheduled to be performed next, it is preferable to ignite and burn the injected fuel as shown in step 513 of FIG. 5 together with the fuel injection.

In step 509, if the fuel injection is performed in the cylinder in which both the intake valve and the exhaust valve are closed when the engine is stopped, the injected fuel remains in the cylinder and the evaporated fuel is evaporated. Are prevented from being released into the atmosphere. In the embodiment described below, Ne is selected in step 509.
A cylinder in which both the intake valve and the exhaust valve are closed based on the two crank rotation angle pulse signals of the signal and the G signal,
That is, the cylinder in the vicinity of the top dead center of the compression stroke is discriminated and the fuel is injected into that cylinder.

Here, the Ne signal and the G signal are such that the protrusions (teeth) provided around the rotor that rotates at a speed of half the crankshaft provided in the engine distributor are arranged close to the rotor. It is a pulse signal generated every time the electromagnetic pickup position is passed, and an arbitrary pulse signal can be generated by setting the shape of the teeth on the outer circumference of each rotor.

FIG. 6 shows N in the case of a 4-cycle 4-cylinder engine.
An example of the relationship between the e signal, the G signal, and the crank rotation angle is shown. In the example of FIG. 6, teeth for generating a rotation pulse are provided every 5 ° (every 10 ° in crank rotation angle) around the rotor for the Ne signal, and further, in the fourth cylinder and the first cylinder. At the position corresponding to the compression top dead center (the position corresponding to the rotation of the crank angle of 360 °), a toothless portion corresponding to two teeth is provided for cylinder discrimination. Therefore, the Ne signal is composed of a pulse signal for each crank rotation angle of 10 ° and a toothless signal for two rotations per rotation (crank rotation angle of 720 °) (see FIG. 6).
reference).

Further, as shown in FIG. 6, the G signal has a waveform in which a low level signal and a high level signal are combined, and a combination of the Ne signal and the G signal is used for each cylinder by the following method. The compression top dead center can be determined. That is, in FIG. 6, when the missing tooth signal of the Ne signal is input, it means that the fourth or first cylinder is in the vicinity of the compression top dead center, and if the G signal is low level. If the first cylinder (FIG. 6) is at a high level, it is determined that the fourth cylinder (FIG. 6) is near the compression top dead center.

When the missing tooth signal of the Ne signal is not input, the number of Ne pulses input until the G signal changes from the low level to the high level is greater than 2 and 4
If the following (2 <Ne ≦ 4) (FIG. 6), then the third
If the number of Ne pulses input to the cylinder is 2 or less before the G signal changes from the low level to the high level (FIG. 6,), the second cylinder is in the vicinity of the compression top dead center. Is determined.

In this case, in step 509 of FIG. 5, the cylinder in the vicinity of the compression top dead center when the engine is stopped is discriminated from the Ne signal and the G signal as described above, and fuel is injected into this cylinder for decompression. . As a result, the injected fuel remains in the cylinder even after the engine is stopped and is not released to the atmosphere. Therefore, the release of unburned fuel to the atmosphere is prevented without ignition by the spark plug. Further, when the engine is restarted, the fuel is surely present in the cylinder, so that the engine can be easily restarted.

In the embodiment of FIG. 5, it is determined whether or not fuel injection for pressure reduction is necessary based on the engine cooling water temperature THW and the outside air temperature TATM after the ignition switch is turned off. FIG. 5, steps 503, 50
5) Alternatively, another routine that is executed at regular time intervals during engine operation may be used to constantly determine whether or not fuel injection for depressurizing when the engine is stopped is necessary based on THW and TATM. In this case, if fuel injection for pressure reduction is not required, the power of the ECU 20 is turned off at the same time as the ignition switch is turned off, and the power off of the ECU 20 is delayed only when fuel injection is required. It suffices to execute steps 507 to 515.

Further, in the embodiment of FIG. 5, the cooling water temperature TH
The limit values Te and Ta of W and the outside air temperature TATM are constant values. However, when the fuel pressure in the delivery pipe 3 is high when the engine is stopped, the limit values Te and Ta are low. Therefore, the relationship corresponding to FIG. 3 is previously obtained by changing the value of the fuel oil pressure when the engine is stopped by an experiment or the like. The limit values Te and Ta may be obtained according to the pressure in the delivery pipe 3 detected by the fuel pressure sensor 31 when the engine is stopped.

[0042]

According to the present invention as set forth in claim 1, after stopping the engine by a simple method without enlarging the drive solenoid and the return spring of the fuel injection valve or providing the return passage for returning the fuel oil to the tank. It is possible to solve the problem due to the increase in fuel pressure. Further, according to the present invention described in claim 2, in addition to the effect of claim 1, it is possible to prevent the unburned fuel from being released to the atmosphere by further burning the injected fuel. The effect of preventing deterioration of emission is obtained.

Further, according to the present invention as set forth in claim 3, the fuel injection after the engine is stopped is performed only in the cylinder in which both the intake valve and the exhaust valve are closed. In addition to the effect of 1, the effect of preventing deterioration of evaporative emission and facilitating engine restart can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating an example of the present invention.

FIG. 2 is a diagram illustrating a rise in fuel oil pressure after the engine is stopped.

FIG. 3 is a diagram showing the maximum ultimate pressure of fuel oil after the engine is stopped.

FIG. 4 is a diagram showing setting of a fuel injection amount when the engine is stopped.

FIG. 5 is an example of a flowchart showing pressure reduction control of the embodiment of FIG.

FIG. 6 is a diagram illustrating a method of discriminating a cylinder that performs fuel injection after the engine is stopped.

[Explanation of symbols]

 1 ... Fuel injection valve 3 ... Delivery pipe 5 ... High pressure diaphragm pump 7 ... Fuel tank 9 ... Feed pump 20 ... Engine control circuit (ECU)

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Claims (3)

[Claims] 1. A fuel passage to which pressurized fuel is supplied, a fuel injection valve for injecting fuel in the fuel passage into a cylinder of an internal combustion engine, and control means for controlling a fuel injection operation of the fuel injection valve. In a fuel injection control device for an internal combustion engine, comprising: an estimating means for estimating a maximum reached value of the fuel pressure in the fuel passage due to a temperature rise after the engine is stopped, based on the engine operating state when the engine is stopped, When the estimated maximum pressure reached value is equal to or higher than a predetermined value, the control means lowers the pressure in the fuel passage by injecting fuel from the fuel injection valve immediately after the engine is stopped. Injection control device for internal combustion engine. 2. The control means also ignites a cylinder to which fuel is supplied by a fuel injection valve for injecting fuel when fuel is injected from the fuel injection valve when the engine is stopped. The fuel injection control device described. 3. The control means, when performing fuel injection from the fuel injection valve when the engine is stopped, injects fuel only from a fuel injection valve of a cylinder in which both an intake valve and an exhaust valve are closed. The fuel injection valve control device according to claim 1, wherein