JP2001227389A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an injection valve drive circuit from heating in the fuel injection. SOLUTION: In a multiple cylinder diesed engine, injection are provided with solenoids L1-Ln respectively. A microcomputer 10 calculates the energization times and energization start timings of solenoids L1-Ln based on the engine operation state. A drive circuit 20 is provided with transistors Tr1-Trn provided in series to the solenoids L1-Ln, a peak current feed circuit feeding the peak current to the solenoids L1-Ln in turning on the transistors Tr1-Trn, and a hold current feed circuit feeding the hold current smaller than the peak current to the solenoids L1-Ln after feeding the peak current. The microcomputer 10 judges whether a pilot injection is implemented in addition to the main injection and when judged to implement only the main combustion, the microcomputer restricts the feeding of the peak current by the peak current feed circuit.

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 Conventionally, an electromagnetic unit injector having an electromagnetic solenoid has been used as a fuel injection valve for injecting fuel into each cylinder of an internal combustion engine. When the electromagnetic solenoid is energized, the injector is opened and the fuel is opened. An injection is performed.

Further, as a drive circuit for driving such an injector, a booster circuit for boosting a power supply voltage and previously generating a high voltage for high-speed valve opening and a constant current (hold current) for holding the valve open are passed. Some include a constant current circuit. In this drive circuit, when driving the injector,
At the beginning of driving, a large current (peak current) flows to the electromagnetic solenoid by the high voltage generated by the booster circuit, and the injector of the corresponding cylinder is opened promptly. A constant current (hold current) is passed to maintain the valve-open state of the injector of the corresponding cylinder.

[0004]

However, in the above prior art, since a large current (peak current) flows at the beginning of driving of the injector, the amount of heat generated by various elements in the drive circuit increases. In particular, when the engine speed increases, the number of injections increases, so that the amount of heat generated increases. Specifically, a coil element constituting the booster circuit, a capacitor as a peak current supply source, and other switching elements generate heat. Therefore, as an anti-heat measure, it is required to use an expensive element having high heat resistance or to provide a heat radiation structure. As a result, the cost for realizing the injector drive circuit rises.

In recent years, for the purpose of reducing noise and exhaust emissions, a technique for injecting a main injection and a pilot injection preceding the main injection and continuously performing the two fuel injections has been put into practical use. When the fuel injection is performed in multiple stages, the amount of heat generation further increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a fuel injection control apparatus for an internal combustion engine capable of preventing heat generation of an injection valve drive circuit during fuel injection. It is to provide.

[0007]

As a basic operation of the present fuel injection control device, when the switching element is turned on by the control means, first, a peak current is supplied to the electromagnetic solenoid by a peak current supply circuit, and the fuel injection is performed. Open the valve promptly. Then, a hold current smaller than the peak current is supplied to the electromagnetic solenoid by the hold current supply circuit, and the open state of the fuel injection valve is maintained. By the operation of such a drive circuit, the valve opening operation of the fuel injection valve is controlled in accordance with the power supply time and power supply start timing of the electromagnetic solenoid calculated based on the operation state of the internal combustion engine.

[0010] In particular, according to the first aspect of the present invention, it is determined based on the operating state of the internal combustion engine whether to perform pilot injection preceding the main injection in addition to the main injection (determining means), and determine that only the main injection is to be performed. Then, the supply of the peak current by the peak current supply circuit is limited (peak current limiting means).

In short, in a fuel injection control device that requires pilot injection and main injection, when pilot injection is prohibited and only main injection is performed, there is a time margin before the start of the main injection. Therefore, at the time of the main injection, it is not necessary to drive the fuel injection valve at high speed with emphasis on responsiveness. Therefore, the supply of a large peak current, which is essential for the high-speed response of the fuel injection valve, is limited, and the amount of heat generated due to the supply of the peak current is suppressed. In other words, by limiting the peak current as described above, it is possible to avoid such a disadvantage that a large current repeatedly flows for each fuel injection and the amount of heat generated by the injection valve drive circuit increases. As a result, it is possible to prevent the injection valve drive circuit from generating heat during fuel injection.
Further, an additional configuration for heat control is not required.

According to the second aspect of the present invention, when the peak current is limited by the peak current limiting means, the energizing time of the electromagnetic solenoid calculated by the control means is increased by a predetermined time, and the electromagnetic solenoid is increased. (A control amount correction means). In this case, the energization time of the electromagnetic solenoid is increased, and the energization start timing of the electromagnetic solenoid is advanced, and the period of the hold current supply is lengthened accordingly. Even if the responsiveness of the injection valve is somewhat reduced, there is no inconvenience that the fuel injection amount is reduced carelessly or the start of fuel injection is delayed. As a result, as described above, in addition to being able to prevent heat generation of the injection valve drive circuit during fuel injection,
Appropriate fuel injection control can be performed.

According to the third aspect of the present invention, the determining means determines whether or not the rotation speed of the internal combustion engine is in a predetermined high rotation range, and determines that the engine rotation speed is in a predetermined high rotation range. The peak current limiting means limits the supply of the peak current. In particular, in this case, the peak current is limited in the high rotation range, so that the effect of reducing the amount of generated heat is more remarkably obtained.

Further, in the invention according to claim 4, the peak current supply circuit includes a power storage element as a peak current supply source, and the peak current limiting means sets a target power storage amount of the power storage element low. This limits the supply of peak current. In this case, since the amount of charge stored in the storage element is reduced, an effect of reducing the amount of heat generated in the storage element can be obtained in addition to the effect of reducing the amount of heat directly related to the reduction of the peak current.

More specifically, in the invention of claim 4,
As described in claim 5, the booster circuit boosts the onboard power supply and stores the power in the power storage element. Further, the switching unit turns on / off the switch circuit so that the charged amount of the storage element becomes the target charged amount set by the peak current limiting unit. Thereby, the amount of charge of the storage element can be adjusted as desired.

According to the present invention, the control amount correction means increases the correction time for advancing the energization start timing of the electromagnetic solenoid as the engine speed increases. Thus, even if the engine speed changes, an optimum correction time can be set each time, and as a result, highly accurate fuel injection control can be performed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection control device according to the present embodiment is embodied as a common rail type fuel injection control system for a vehicle diesel engine. As an outline, high pressure fuel is accumulated in a common rail. Then, the stored high-pressure fuel is injected and supplied to the engine with the ON operation of the electromagnetically driven unit injector. Hereinafter, this will be described in detail with reference to the drawings.

FIG. 1 is an electrical configuration diagram showing an outline of a fuel injection control system. The multi-cylinder diesel engine has n cylinders # 1, # 2,... #N, and each of the n injectors to be controlled includes an electromagnetic solenoid L1, L2,. By controlling the energizing time and energizing timing of the electromagnetic solenoids L1 to Ln, the cylinders # 1 to # 1 of the diesel engine are controlled.
The fuel injection amount and fuel injection timing for #n are controlled.

The fuel injection control system includes a CPU, an RO,
The microcomputer 10 mainly includes a well-known microcomputer (hereinafter, referred to as a microcomputer) 10 including an M, a RAM, and the like. The microcomputer 10 performs various processes for fuel injection control according to a preset control program. That is, the microcomputer 10 captures detection values of various sensors such as the engine speed NE and the accelerator opening ACC as engine operation information, and based on these sensor detection values, a pulse for optimally controlling the fuel injection amount and the injection timing. To generate an injection signal. Then, the injection signal is output to the drive circuit 20, and the energization of the electromagnetic solenoids L1 to Ln in each cylinder is individually controlled.

In particular, in the apparatus of the present embodiment, the main injection and the pilot injection preceding the main injection are performed as the injection requirements. Actually, the main injection pulse and the pilot injection pulse are individually set. After that, the respective injection pulses are synthesized and used as an injection signal of each cylinder, and the electromagnetic signals L1 to Ln are energized by the injection signal.

The drive circuit 20 is provided with a booster circuit 21 including a transformer 21a and a transistor 21b. One end of a primary winding of the transformer 21a is connected to a battery power supply + B, and the other end is connected to a transistor 21b. It is connected. The secondary winding of the transformer 21a is connected to a pilot injection capacitor 23 via a diode 22 and a main injection capacitor 25 via a switch 40 and a diode 24.
The voltage value of these capacitors 23 and 25 when fully charged is 118 volts. Therefore, when the transistor 10b is turned on / off at a high speed by the microcomputer 10 while the switch 40 is on, the high voltage generated on the secondary side of the transformer 21a causes the pilot injection and the main injection through the diodes 22 and 24 to occur. Capacitor 23,
25 are each charged. Further, when the switch 40 is switched from ON to OFF during the step-up operation by the step-up circuit 21, the supply of energy from the step-up circuit 21 to the capacitor 25 is interrupted, and the charge amount of the main injection capacitor 25 is adjusted. .

The charge voltage of the pilot injection capacitor 23 is detected by a voltage dividing circuit composed of resistors 26 and 27, and the detected voltage is taken into a voltage monitoring circuit 41. Then, the output of the voltage monitoring circuit 41 is taken into the microcomputer 10. That is, the voltage monitoring circuit 41 monitors the charge voltage of the capacitor 23, and when the charge voltage reaches a predetermined voltage value (corresponding to the charge completion voltage), outputs a determination signal indicating that to the microcomputer 10.
Specifically, the voltage monitoring circuit 41 sets the threshold voltage for voltage monitoring to 90 volts, and outputs a determination signal to the microcomputer 10 when the charge voltage of the capacitor 23 reaches 90 volts. The microcomputer 10 includes a voltage monitoring circuit 4
The charge state of the capacitor 23 is determined based on the determination signal from 1, and the operation of the booster circuit 21 is controlled based on the determination.

The charge voltage of the main injection capacitor 25 is detected by a voltage dividing circuit composed of resistors 28 and 29, and the detected voltage is taken into a voltage monitoring circuit 42. Then, the output of the voltage monitoring circuit 42 is taken into the microcomputer 10. The voltage monitoring circuit 42 has a configuration similar to that of the voltage monitoring circuit 41 on the pilot injection side, monitors the charge voltage of the capacitor 25, and sets this charge voltage to a predetermined voltage value (corresponding to a charge completion voltage). Is reached, a determination signal indicating that fact is output to the microcomputer 10. However, the voltage monitoring circuit 41 on the pilot injection side sets the threshold voltage for voltage monitoring to 90 volts, while the voltage monitoring circuit 42 on the main injection side sets the threshold voltage to 118 volts.

Electromagnetic solenoids L1 to Ln are connected to the high side of capacitor 23 via transistor 31 and diode 32, and electromagnetic solenoids L1 to Ln are connected to the high side of capacitor 25 via transistor 33 and diode 34. It is connected. In such a configuration, the microcomputer 10 temporarily turns on the transistor 31 at the timing when the injection pulse for pilot injection is inverted from L level to H level, and the capacitor 23
Is supplied to any of the electromagnetic solenoids L1 to Ln through the diode 32. In addition, the microcomputer 1
0 indicates that the injection pulse for the main injection is changed from L level to H level.
The transistor 33 is temporarily turned on at the timing of inversion to the level, and the charge voltage of the capacitor 25 is supplied to any one of the electromagnetic solenoids L1 to Ln through the diode 34.

The transistors Tr1, Tr2,... Trn are connected in series to the low side of each of the electromagnetic solenoids L1 to Ln, and an H-level injection signal (pilot or main injection pulse) is supplied from the microcomputer 10. As a result, these transistors Tr1 to Trn
Is turned ON, and the electromagnetic solenoids L1 to Ln of the cylinders corresponding to the transistors Tr1 to Trn are energized.

A constant current circuit 35 is connected to the high side of each of the electromagnetic solenoids L1 to Ln. The constant current circuit 35 receives a power supply from the battery power supply + B, generates a constant current (hold current), and supplies the hold current through the diode 36 to the electromagnetic solenoids L1 to Ln whose current paths are conducted. The constant current circuit 35
Is a well-known device provided with a switching element connected in series to a battery power supply + B. In short, the switching device detects a current flowing through the electromagnetic solenoids L1 to Ln and sets the detected value to a predetermined value. ON / OF element
F to supply the hold current.

The two-stage injection requirements such as the pilot injection and the main injection determine whether or not the injection is to be performed according to the engine operating conditions at each time. Generally, the engine is in a relatively low rotation state. At the time, both the pilot injection and the main injection are performed, while only the main injection is performed when the engine is in a relatively high rotation state. That is, when the engine is running at a low speed, pilot injection is required to improve ignitability, prevent noise, and suppress the generation of particulates (fine particles) and NOx.

In this embodiment, the microcomputer 10 corresponds to the control means, and includes the booster circuit 21, the capacitors 23 and
5 corresponds to a peak current supply circuit, and the constant current circuit 35 corresponds to a hold current supply circuit.

FIG. 2 is a time chart showing how the pilot injection and the main injection are performed continuously at the time of low engine speed. In FIG. 2, as the injection signal corresponding to the combustion cylinder at that time, the injection pulse for pilot injection becomes H level during the period from time t1 to t2. As a result, at the beginning of the pilot injection, the transistor 3
1 is temporarily turned on, the charge voltage of the capacitor 23 is discharged, and a peak current flows through the electromagnetic solenoid.
At this time, the charge voltage of the capacitor 23 is 118
Volts and the discharge causes a 12 amp peak current to flow.

Thereafter, a hold current (about 2 amps) is supplied from the constant current circuit 35 to the electromagnetic solenoid. In short, at the beginning of the injection, the valve opening response of the injector is accelerated by the supply of the peak current, and thereafter, the valve opening state of the injector is maintained by the supply of the constant current. Note that the injector is in the open state during a period from immediately after time t1 to time t2.

After the end of the pilot injection, the boosting circuit 21
Is turned on / off until the threshold voltage (90 volts) in the voltage monitoring circuit 41 is reached.
The capacitor 23 is charged (period t2 to t3).

In the period from time t4 to time t5, the injection pulse for main injection is at the H level as the injection signal.
At the beginning of the main injection, the transistor 33 is temporarily turned on, the charge voltage of the capacitor 25 is discharged, and a peak current flows through the electromagnetic solenoid. At this time, similarly to the pilot injection, a peak current of 12 amps flows with the discharge of the capacitor 25. After that, a hold current is supplied from the constant current circuit 35 to the electromagnetic solenoid. Also in this case, at the beginning of the injection, the valve opening response of the injector is accelerated by the supply of the peak current,
Thereafter, the supply of the constant current keeps the injector open.

After the end of the main injection, the transistor 21b in the booster circuit 21 is turned on / off again, and the capacitor 25 is charged until the voltage reaches the threshold voltage (118 volts) in the voltage monitor circuit 42 (t5). To t6). The switch 40 provided on the charging path of the capacitor 25 is turned on until the charging voltage reaches 118 volts. At this time, the capacitor 23 is simultaneously charged from 90 volts to 118 volts.

As described above, the pilot injection and the main injection are performed continuously at the time of low engine rotation. In this case, these two injection requirements must be performed at a relatively short time interval, and the injector needs to be performed at a relatively short time interval. High-speed response is essential. A relatively large peak current is required for high-speed response of the injector.

On the other hand, when the engine is running at high speed, pilot injection is not an essential requirement and only main injection is performed. Therefore, there is no need to consider the time interval between the pilot injection and the main injection, and the main injection does not require a high current for ensuring responsiveness. Incidentally, for example, in the state of NE = 2000 rpm, the time interval between the pilot injection and the main injection is about 1 ms, and the time interval between the main injections before and after only the main injection is about 5 ms.

Therefore, in the apparatus according to the present embodiment, the supply of the peak current during the main injection is limited at the time of high engine rotation in which the pilot injection is prohibited. In other words, in order to reduce the peak current at the beginning of the main injection from the current level of about 12 amps to half, the minimum operating range (about 6
Ampere), and the time for the constant current control is prolonged by an amount corresponding to the decrease in the valve opening response of the injector. Actually, the energization time of the electromagnetic solenoids L1 to Ln is increased by a predetermined time, and the energization start timing is corrected to an earlier time by a predetermined time. By such correction of the energization start timing, the energy required for opening the injector can be secured, and even if the responsiveness of the injector to open becomes slow, the valve opening time of the injector remains unchanged, and a desired amount of fuel can be injected and supplied to the engine.

FIG. 3 is a time chart showing a state where only the main injection is performed at the time of high engine speed. In FIG. 3, the injection signal is originally set at the time t12 to t13 so that the injection timing is set in the period from the time t12 to t13.
The injection pulse for the main injection becomes the H level during the period of t13. The injection start timing (energization start timing) is advanced by the injection pulse correction time T1, and the times t11 to t13 are set.
In the period, the injection pulse for main injection is set to the H level.

At time t11, the transistor 33 is temporarily turned on, the charge voltage of the capacitor 25 is discharged, and a peak current flows through the electromagnetic solenoid. At this time, the charge voltage of the capacitor 25 is previously limited to 90 volts, and the peak current is about 6 amps.
After that, a hold current (about 2 amps) is supplied from the constant current circuit 35 to the electromagnetic solenoid. In this case, the injector opens for the time T2 in the figure.

In short, the valve opening timing of the injector is delayed by the amount by which the peak current is halved and the valve opening responsiveness of the injector at the time of the main injection becomes slow. However, the injection pulse is advanced earlier by the injection pulse correction time T1. The valve opening timing is controlled at the same valve opening timing (immediately after time t12) as when a peak current of 12 amps was originally passed.

After the end of the main injection, as in FIG.
The transistor 21b in the booster circuit 21 is turned ON / OFF, but the ON time of the switch 40 provided on the charging path of the capacitor 25 is regulated by the charging time T3. Therefore, when the charging of the capacitor 25 reaches the charging voltage of 90 volts, it is forcibly stopped (period t13 to t14). As a result, similarly, in the subsequent main injection,
A peak current of about 6 amps flows.

Next, the processing procedure of the fuel injection control performed as described above will be described with reference to the flowchart of FIG. This process is executed by the microcomputer 10 for each fuel injection of each cylinder (for every 180 ° CA in the case of a four-cylinder engine).

Referring to FIG. 4, first, at step 101,
The engine operation state such as the engine speed NE and the accelerator opening ACC is read, and in a subsequent step 102, a fuel injection amount Q is calculated based on the NE and ACC at each time using a characteristic map (not shown).

Thereafter, in step 103, it is determined whether or not the engine speed NE at that time is higher than a predetermined high speed region (2000 rpm in the present embodiment). In the present embodiment, a diesel engine for a large vehicle such as a truck or an industrial vehicle is to be controlled, and its entire rotation speed range is 0 to about 3000 rpm. However, the setting may be arbitrarily set for each engine model.

If NE <2000 rpm, the routine proceeds to step 104 in order to implement the two-stage injection requirements of pilot injection and main injection. That is, in step 104,
Based on the calculated fuel injection amount Q, an injection amount during pilot injection and an injection amount during main injection are calculated,
The injection timing of each injection is calculated. In the following step 105, an injection pulse of each injection requirement is generated and output to the drive circuit 20 based on the calculated pilot injection amount, main injection amount, and injection timing, and then the process is temporarily terminated.

On the other hand, if NE ≧ 2000 rpm and it is determined that the engine is in the high speed range, step 106 is performed to inhibit the pilot injection and execute only the main injection.
Proceed to. That is, in step 106, the calculated fuel injection amount Q is directly used as the injection amount for the main injection, and the injection timing of the main injection is calculated.

In step 107, the injection timing of the main injection is corrected to the advanced side. Specifically, the injection pulse correction time T1 is calculated according to the engine speed NE at each time using the relationship of FIG. In FIG. 5, NE ≧ 200
A relationship is set such that the injection pulse correction time T1 increases as the NE increases in the rotation range of 0 rpm. Then, the injection start timing is corrected to the advanced side by subtracting the injection pulse correction time T1 from the injection timing (injection start time) calculated in step 106. The injection end time is not changed.

In step 108, an injection pulse for the main injection is generated based on the calculated injection amount and injection timing of the main injection, and the injection pulse is output to the drive circuit 20 as an injection signal.

Thereafter, in step 109, the charging time T3 of the capacitor 25 is set so as to lower the charging voltage of the capacitor 25 from 118 volts at the normal time. Actually, the charge time T3 and the charge voltage have the relationship shown in FIG.
Shortening from .mu.s to 1.5 .mu.s reduces the charge voltage from 118 volts to 90 volts. In this step 109, the relationship in FIG. 7 corresponding to the relationship in FIG.
Is larger, the charging time T3 is set shorter. Then, after setting the charging time T3, the present process ends.

In this embodiment, step 1 in FIG.
03 corresponds to the determining means described in the claims, step 109 corresponds to the peak current limiting means and the switching means, and step 107 corresponds to the control amount correcting means.

According to the embodiment described above, the following effects can be obtained. (A) It is determined whether or not to perform pilot injection in addition to main injection, and when it is determined that only main injection is to be performed, the supply of peak current is limited. Inconveniences such as an increase in the calorific value of 20 are avoided. Actually, the heat generation of several watts is suppressed in comparison with the conventional heat generation of 20 watts. As a result, heat generation of the drive circuit 20 at the time of fuel injection can be prevented. Further, an additional configuration for heat countermeasures is not required, and there is no inconvenience such as an increase in cost due to heat countermeasures. Further, by limiting the peak current, electric noise superimposed on the GND line and the signal line can be reduced, and the reliability of various electric noise tests can be expected to be improved.

(B) When the peak current is limited, the energization time of the electromagnetic solenoids L1 to Ln is increased and the energization start time is advanced, and the hold current supply period is lengthened accordingly. Even if the responsiveness of the injector is somewhat reduced due to the restriction, the inconvenience that the fuel injection amount is inadvertently reduced or the start of the fuel injection is delayed does not occur. As a result, it is possible to prevent heat generation of the drive circuit 20 at the time of fuel injection as described above, and to perform appropriate fuel injection control.

(C) The engine speed NE is determined, and
Since the supply of the peak current is limited when E is determined to be in the predetermined high rotation range, the effect of reducing the amount of generated heat is more remarkably obtained.

(D) The supply of the peak current is limited by setting the charge voltage (target charge amount) of the capacitor 25 on the main injection side low. In this case, the charge voltage of the capacitor 25 is reduced, and the effect of reducing the amount of heat generated by the capacitor 25 is obtained.

(E) The higher the engine speed NE, the earlier the injection start timing is corrected (relationship in FIG. 5). Thus, even when the engine speed NE changes, the optimum fuel injection timing can be set each time, and as a result, highly accurate fuel injection control can be performed.

The present invention can be embodied in the following forms other than the above. In the above embodiment, the charge voltage of the capacitor 25 is adjusted by switching the switch 40 provided on the charge path of the capacitor 25, but the configuration is changed. For example, the switch 40 is eliminated, and the ON / OFF period (switching period) of the transistor 21b in the booster circuit 21 is changed to adjust the charge voltage of the capacitor 25. Even with such a configuration, the charge voltage of the capacitor 25 can be properly managed. In this case, the booster circuit 2
Since the + B step-up period by 1 (switching period of the transistor 21b) coincides with the capacitor charging period, the substantial + B step-up period can be shortened, and the amount of heat generated by the step-up circuit 21 can be reduced.

In the above-described embodiment, the charge voltage of the capacitor 25 is reduced (118 V → 90 V) in the high engine speed region where the pilot injection is prohibited, thereby restricting the supply of the peak current. . For example, the current supply path between the capacitor 25 and the electromagnetic solenoids L1 to Ln is cut off when a predetermined minute time has elapsed after the start of injection (after the start of energization), thereby limiting the supply of the peak current. The peak current is directly monitored, and the supply of the peak current is stopped when the monitored peak current reaches a predetermined value (for example, 6 amps), thereby limiting the supply of the peak current. Such a configuration may be used. However, in this case, although the effect of suppressing heat generation by reducing the peak current is obtained,
Since the charge voltage of the capacitor 25 remains high, the effect of reducing heat generation in the capacitor 25 is small.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a fuel injection control system according to an embodiment of the invention.

FIG. 2 is a time chart showing a state in which pilot injection and main injection are continuously performed at a low engine speed.

FIG. 3 is a time chart showing a state in which only main injection is performed at the time of high engine speed.

FIG. 4 is a flowchart showing a control procedure of fuel injection.

FIG. 5 is a diagram for setting an injection pulse correction time.

FIG. 6 is a diagram showing a relationship between a charge time and a charge voltage.

FIG. 7 is a diagram for setting a charge time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Microcomputer as a control means, 20 ... Drive circuit (injection valve drive circuit), 21 ... Boost circuit, 23, 25 ... Capacitor (storage element), 35 ... Constant current circuit, 40 ... Switch (switch circuit), L1- Ln: electromagnetic solenoid, Tr
1 to Trn: transistors (switching elements).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 51/00 F02M 51/00 A FF Term (Reference) 3G066 AA07 AC09 BA41 CC05U CE22 CE29 DA01 DA04 DA09 DB13 DC09 3G301 HA02 HA26 JA14 KA25 LC10 MA11 MA18 MA23 MA26 MA27 NA08 NE11 NE17 NE23 PE01Z PG02Z

Claims (6)

[Claims] 1. A fuel injection valve that opens by energizing an electromagnetic solenoid to inject fuel into an internal combustion engine and a switching element provided in series with the electromagnetic solenoid to open / close a fuel injection valve. An injection valve drive circuit for closing a valve or a valve, and control means for calculating an energization time and an energization start time of the electromagnetic solenoid based on an operation state of the internal combustion engine, and driving the switching element according to the calculation result. An injection valve drive circuit, a peak current supply circuit that supplies a peak current to the electromagnetic solenoid when the switching element is turned on, and a hold current supply circuit that supplies a hold current smaller than the peak current to the electromagnetic solenoid after the supply of the peak current. In the fuel injection control device for an internal combustion engine equipped with Determining means for determining whether to perform one pilot injection; and peak current limiting means for limiting supply of peak current by the peak current supply circuit when the determining means determines that only main injection is to be performed. A fuel injection control device for an internal combustion engine, comprising: 2. When the peak current is limited by the peak current limiting means, the power supply time of the electromagnetic solenoid calculated by the control means is increased by a predetermined time, and the power supply start time of the electromagnetic solenoid is advanced by a predetermined time. 2. The fuel injection control device for an internal combustion engine according to claim 1, further comprising a control amount correction unit that corrects the control amount. 3. A fuel injection control device for prohibiting the execution of pilot injection in a predetermined high rotation range, wherein said determination means determines whether or not the rotation speed of the internal combustion engine is in a predetermined high rotation range. 3. The fuel injection control device for an internal combustion engine according to claim 1, wherein the peak current limiting means limits the supply of the peak current when it is determined that the rotation speed is in a predetermined high rotation range. 4. The peak current supply circuit includes a power storage element as a peak current supply source, and the peak current limiting means limits the supply of the peak current by setting a low target power storage amount of the power storage element. The fuel injection control device for an internal combustion engine according to claim 1. 5. The fuel injection control device according to claim 4, wherein a booster circuit for boosting a vehicle-mounted power supply and storing the boosted power in the storage element; a switch circuit provided between the booster circuit and the storage element; Switching means for turning on / off the switch circuit so that the amount of charge of the storage element becomes the target amount of charge set by the peak current limiting means. 6. The fuel injection control device for an internal combustion engine according to claim 2, wherein the control amount correction means increases the correction time for advancing the energization start timing of the electromagnetic solenoid as the engine speed increases.