JPH08177583A - Solenoid valve driving device - Google Patents

Abstract

PURPOSE: To obtain the second valve opening action onward correctly taking account of the generation of residual magnetic flux in a continuous valve opening action mode of putting a valve in opening action continuously plural times, and reduce energy consumption. CONSTITUTION: A fuel injection valve is opened by applying a current to a driving solenoid 30 so as to inject high pressure fuel. An ECU 4 sets either a normal injection mode of performing only main injection or a pilot injection mode of performing also pilot injection prior to main injection, according to the operating state of a diesel engine. The ECU sets lower voltage in the pilot injection mode than in the normal injection mode, as the voltage applied to the driving solenoid 30 of the fuel injection valve 3. At the time of the normal injection mode, the ECU 4 applies a current once to the driving solenoid 30 to perform main injection, and at the time of the pilot injection mode, the ECU 4 applies a current twice to the driving solenoid 30 to perform pilot injection and main injection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid valve drive device, and is suitable for a fuel injection control device for a diesel engine, for example, which performs parrot injection prior to main injection.

[0002]

2. Description of the Related Art A common rail type is known as an electronically controlled fuel injection device for a diesel engine (for example, Japanese Patent Laid-Open No. 2-108847). this is,
The high-pressure fuel is stored in the common rail, and the drive solenoid provided in the fuel injection valve is energized to lift the needle valve and inject the high-pressure fuel in the common rail from the fuel injection valve.

[0003]

The object of the invention is to be Solved However, the to perform and carry out a pilot injection prior to the main injection in order to reduce the noise measures and NO _x, the power supply for the main injection after the power supply for the Parrot injection . At this time, a residual magnetic flux is generated in the solenoid during energization for parrot injection, and an excessive amount of current occurs during energization for main injection, resulting in a deviation on the increasing side with respect to the target fuel injection amount.

Therefore, an object of the present invention is to accurately perform the second and subsequent valve opening operations in consideration of the generation of residual magnetic flux in the continuous valve opening operation mode in which the valve opening operation is continuously performed a plurality of times. At the same time, it is to provide an electromagnetic valve drive device capable of reducing energy consumption.

[0005]

According to the invention described in claim 1, a solenoid valve which is opened by energizing a drive solenoid, and a single opening operation mode in which only one opening operation is performed are continuous. Mode setting means for setting one of the continuous valve opening operation modes for performing the valve opening operation a plurality of times, and driving the solenoid valve with a voltage lower than that in the single-shot valve opening operation mode in the continuous valve opening operation mode by the mode setting means. In the single-valve opening operation mode by the solenoid applied voltage changing means set as the applied voltage to the solenoid and the mode setting means, the drive solenoid is energized once to perform the valve opening operation once, and the continuous valve opening is performed. The gist of the solenoid valve drive device is to include an energization control unit that energizes the drive solenoid a plurality of times to perform a continuous plurality of valve opening operations in the operation mode.

A second aspect of the present invention is the fuel injection control device for an internal combustion engine according to the first aspect, wherein the solenoid valve is a fuel for injecting high pressure fuel when the valve is open. It is used for an injection valve, and the mode setting means has either a normal injection mode in which only main injection is performed according to the operating state of the internal combustion engine, or a pilot injection mode in which pilot injection is also performed prior to main injection. In the pilot injection mode, the solenoid applied voltage changing means sets a voltage lower than that in the normal injection mode as the applied voltage to the drive solenoid of the fuel injection valve, and the energization control means sets the normal injection mode. In the mode, the drive solenoid is energized once to perform main injection, and in the pilot injection mode, the drive solenoid is energized twice. The electromagnetic valve driving device is intended to perform the pilot injection and main injection as its gist.

According to a third aspect of the present invention, the solenoid applied voltage changing means in the second aspect of the invention comprises an energization period for pilot injection, an energization suspension period between pilot injection and main injection, Thus, the gist is an electromagnetic valve drive device that determines the voltage applied to the drive solenoid in the pilot injection mode.

[0008]

According to the first aspect of the present invention, the mode setting means has a single valve opening operation mode in which only one valve opening operation is performed and a continuous valve opening operation mode in which a plurality of consecutive valve opening operations are performed. Set either of. The solenoid applied voltage changing means sets, in the continuous valve opening operation mode by the mode setting means, a voltage lower than that in the single-shot valve opening operation mode as an applied voltage to the drive solenoid of the solenoid valve. The energization control means energizes the drive solenoid once to perform one valve opening operation in the single-valve opening operation mode by the mode setting means, and continuously energizes the drive solenoid multiple times in the continuous valve opening operation mode. The valve is opened multiple times.

In the continuous valve-opening operation mode, a residual magnetic flux is generated in the drive solenoid due to the energization for the first valve opening, and the current tends to become excessive during the energization for the second valve opening. In the continuous valve opening operation mode, a voltage lower than that in the single-shot valve opening operation mode is applied to the drive solenoid of the solenoid valve, so that excess current due to residual magnetic flux is suppressed. Further, the applied voltage can be lowered, and the energy consumption can be reduced.

According to the second aspect of the invention, the mode setting means has a normal injection mode in which only the main injection is performed according to the operating state of the internal combustion engine, and a pilot injection mode in which the pilot injection is also performed prior to the main injection. Set either of. The solenoid applied voltage changing means sets a voltage lower than that in the normal injection mode in the pilot injection mode by the mode setting means as an applied voltage to the drive solenoid of the fuel injection valve. The energization control means energizes the drive solenoid once for main injection in the normal injection mode by the mode setting means, and energizes the drive solenoid twice for pilot injection and main injection in the pilot injection mode.

[0011] Here, a residual magnetic flux is generated in the drive solenoid due to energization for pilot injection in the pilot injection mode, and an attempt is made to cause an excessive current during energization for the main injection, but in the pilot injection mode, normal injection is performed. Since a voltage lower than that of the mode is applied to the drive solenoid of the fuel injection valve, excess current due to residual magnetic flux is suppressed. Further, the applied voltage can be lowered, and the energy consumption can be reduced.

According to the invention of claim 3, claim 2
In addition to the operation of the invention described in (1), the solenoid applied voltage changing means is configured to apply the voltage applied to the drive solenoid in the pilot injection mode by the energization period for pilot injection and the energization suspension period between pilot injection and main injection. To decide. Therefore, the applied voltage is adjusted more accurately in consideration of the residual magnetic flux.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a fuel injection control device for a diesel engine will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a fuel injection control device for a diesel engine. A fuel injection control device for a diesel engine includes a pump 1 for pressurizing fuel and a pump 1
Common rail 2 for storing high-pressure fuel pressurized at 1, and fuel injection valve 3 for injecting high-pressure fuel from common rail 2
And an electronic control unit (hereinafter referred to as ECU) 4 and E
It is composed of an electromagnetic valve drive circuit 5 which opens and closes the fuel injection valve 3 in response to a command from the CU 4.

A drive shaft 7 of the pump 1 is rotatably supported in a housing 6, and the drive shaft 7 is drivingly connected to an output shaft of a diesel engine. A cam 8 is eccentrically fixed to the drive shaft 7, and a piston 9 is attached to the cam surface (outer peripheral surface) of the cam 8.
Are contacted by the spring 10. Piston 9 is cylinder 1
It is slidably supported in 1 and slides up and down by the rotation of the cam 8 accompanying the rotation of the drive shaft 7. At this time,
The fuel is introduced from the fuel tank 12 into the cylinder 11 by the downward movement of the piston 9, and the fuel in the cylinder 11 is pressurized by the upward movement of the piston 9, and the pressurized fuel flows through the check valve 13. It is supplied to the common rail 2 via. Also, E
The CU 4 is a pressure sensor 14 provided on the common rail 2.
The fuel pressure in the common rail 2 is kept constant by monitoring the fuel pressure in the common rail 2 and controlling the opening / closing of the solenoid valve 15 provided in the pump 1 to spill the pressurized fuel toward the tank 12 side. It is like this.

The fuel injection valve 3 comprises a fuel injection valve body 16 and a three-way solenoid valve 17, and high-pressure fuel from the common rail 2 is supplied to the fuel injection valve body 16 and the three-way solenoid valve 17. The fuel injection valve body 16 has a fuel chamber 18
A needle valve 19 is arranged inside, and the needle valve 19 is connected to a piston 20 and is biased by a spring 21 in a direction to close the injection port. The three-way solenoid valve 17 includes a housing 22, and an outer valve 23 is vertically slidably supported in an inner hole 22a of the housing 22. The housing 22 has a first port (fuel intake port) 24, a second port 25,
A drain port 26 is provided. The first port (fuel intake port) 24 is the common rail 2 and the second port 2
5 is connected to the upper space of the piston 20, and the drain port 26 is connected to the drain tank 27. The outer valve 23 has a port 28 corresponding to the first port 24.
And a port 29 corresponding to the second port 25.

A drive solenoid 30 is provided above the housing 22. When the drive solenoid 30 is in the non-energized state, the outer valve 23 is urged downward by the spring 31 so that the first port 24 of the housing 22 and the port 28 of the outer valve 23 communicate with each other and the second port 25 of the housing 22 and the outer valve 23. Communicates with the port 29. Therefore, the high-pressure fuel from the common rail 2 is applied to the upper surface of the piston 20 through the ports 24, 28, 29, 25 and the inner hole 23a of the outer valve 23, and this pressure pushes the needle valve 19 downward to open the injection port. close.

When the drive solenoid 30 is energized, the outer valve 23 is suctioned up and the port 24 is closed so that the port 25 and the port 26 communicate with each other, so that the pressure applied to the piston 20 passes through the port 25 and the port 26 and the drain tank 2
It leaks to the 7 side (low pressure side). Therefore, the needle valve 19
Rises by the high pressure fuel in the fuel chamber 18 and opens the injection port to inject the fuel.

When the drive solenoid 30 is not energized, the outer valve 23 has a downward force F F = πPc (D1 ² -D2 ² ) / 4 + Fs, where Pc is the common rail pressure D1 is the diameter D2 of the inner hole 23a of the outer valve 23. Since the urging force of the spring 31 acts on the diameter Fs of the port 25, the port 25 and the port 26 communicate with each other to inject the high-pressure fuel in the common rail 2 by absorbing only the downward force F of the outer valve 23. Not only energy is required, but also the operation of sucking the outer valve 23 must be performed at high speed, so that the port 24 and the port 26
However, the fuel leaks to the drain tank 27. Furthermore, the suction operation of the outer valve 23 must be performed at an extremely high speed in order to precisely control the injection start timing. Therefore, the higher the common rail pressure Pc is, the larger the suction energy of the three-way solenoid valve 17 is required.

Therefore, in order to quickly operate the three-way solenoid valve 17 against the fuel pressure that reaches a maximum of 150 MPa, the solenoid valve drive circuit 5 causes the high voltage exceeding the battery voltage (for example, 12 volts) which is the on-vehicle power supply voltage. A voltage is generated and discharged when the drive solenoid 30 of the three-way solenoid valve 17 is energized to supply a high voltage to the three-way solenoid valve 17. Due to the sudden rising current that accompanies the supply of such a high voltage, the magnetic flux rapidly increases, enabling a high response even under a high fuel pressure.

FIG. 2 shows a specific structure of the solenoid valve drive circuit 5. A primary coil 33a of a transformer 33 and a transistor Tr1 are connected in series to the battery terminal 32. The secondary coil 33b of the transformer 33, the diode 34, and the capacitor 35 are connected in series. At the connection point a between the diode 34 and the capacitor 35, the diode 36 and the drive solenoid 30 of the three-way solenoid valve 17 are connected.
And the transistor Tr2 are connected in series. The connection point b between the capacitor 35 and the diode 36 is grounded via two resistors 37 and 38 connected in series. A connection point c between the resistors 37 and 38 is connected to one input terminal of the comparator 39. The other input terminal of the comparator 39 is connected to the ECU 4. Further, the output terminal of the comparator 39 is connected to the ECU 4.

The base terminal of the transistor Tr1 is E
It is connected to CU4,
A charge pulse is output to the base terminal. This char
The transistor Tr1 is turned on / off by the dipulse.
When the transistor Tr1 is turned on, one of the transformers 33 is
The primary current I is applied to the secondary coil 33a._C1As the tiger flows
The secondary side coil of the transformer 33 is turned off by turning off the transistor Tr1.
Secondary current I _C2Flows, the voltage is applied to the capacitor 35.
Is stored. ON / OFF operation of this transistor Tr1
Accumulated in the capacitor 35 by repeating the work
The voltage boosts. This capacitor voltage is
The pressure is divided at 38. The comparator 39 is the capacitor 3
The divided voltage of 5 and the boost completion command value voltage from the ECU 4
Comparing, the divided voltage of the capacitor 35 is
When the pressure becomes high, the output terminal is changed from the previous H level to the L level.
To This L level signal causes the ECU 4 to transition.
Stop the output of the charge pulse to the transistor Tr1
End the operation (on / off operation of transistor Tr1)
It

In this way, the battery voltage is boosted to a predetermined voltage by the transformer 33 and the capacitor 35. The base terminal of the transistor Tr2 is connected to the ECU 4, and when the fuel injection valve 3 is opened, a drive pulse from the ECU 4 turns on the transistor Tr2 to energize the drive solenoid 30. At this time, since the applied voltage is boosted higher than the battery voltage, it is possible to realize a high voltage responsiveness even under a high fuel pressure by passing a large current through the drive solenoid 30. That is, the valve opening operation is promptly performed by the current from the capacitor 35 at the time of valve opening.

A constant current circuit 40 is attached to the battery terminal 32.
Is connected, and the constant current generated by the constant current circuit 40 is supplied to the drive solenoid 30 via the diode 41. During the valve opening operation of the fuel injection valve 3, the valve open state is maintained by the constant current from the constant current circuit 40.

As shown in FIG. 1, the ECU 4 comprises a microcomputer, an input / output interface, a drive circuit, etc., and inputs an accelerator opening signal, an engine speed signal, a water temperature signal, etc., and the operating state of the diesel engine by them. To detect. The ECU 4 drives and controls the transistor Tr2 according to the operating state of the diesel engine to control the fuel injection amount and the fuel injection timing. That is, as shown in FIG. 3A, the fuel injection amount and the fuel injection timing are controlled by adjusting the injection start timing Tm1 and the injection end timing Tm1 from the reference position. In contrast to the normal injection mode in which only such main injection is performed, in this system, pilot injection prior to main injection is performed (pilot injection mode). That is, as shown in FIG. 3B, the pilot fuel injection amount / fuel injection is adjusted by adjusting the pilot injection start timing Tp1 and the pilot injection end timing Tp2, and the main injection start timing Tm1 and the main injection end timing Tm2. Timing and main fuel injection amount
Control the fuel injection timing.

Here, the period from the pilot injection end timing Tp2 to the main injection start timing Tm1 is the energization suspension period T _I.
(= Tm1-Tp2), that is, an energization suspension period between the pilot injection and the main injection. The period from the pilot injection start timing Tp1 to the pilot injection end timing Tp2 is the pilot injection period Tp (= Tp2-Tp1), that is, the energization period for pilot injection.

The map shown in FIG. 4 is stored in the memory of the ECU 4. This map uses the energization suspension period T _I and the pilot injection period Tp as factors, and the energization suspension period T
Boosting completion voltage Vth according to _I and pilot injection period Tp
Is to determine.

That is, the power in the pilot injection mode is
Remains due to energization of the drive solenoid 30 at the time of ilot injection
Magnetic flux is generated. Therefore, as shown in FIG.
When the drive solenoid 30 for
The current flowing through the solenoid 30 is normally injected by the residual magnetic flux.
Current I in mode_NORCurrent I increased compared to₁(=
I_NOR+ Α). As a result, the injection in the main injection
The amount also increases by the amount shown by the hatched area in Fig. 3.
U Due to this increase in injection amount, noise or NO_X
Will increase. Therefore, the increase of this fuel (in Fig. 3
Eliminate the deviation Δt2) of the nozzle lift start timing
Therefore, the energizing current I in the normal injection mode_NORFrom the pilot
Drive solenoid 30 by residual magnetic flux in injection mode
Current I obtained by subtracting the current increase α₂To shed
Boosted voltage V required for main injection ₂Figure 4 is to decide
It is a map shown. More specifically, as shown in FIG.
The magnitude of the residual magnetic flux depends on the energization suspension period T_IAnd pilot injection
It is determined by the period Tp. That is, the energization suspension period T_IBut
The shorter the shorter the residual magnetic flux, the shorter the pilot injection period Tp.
It is known that the longer the length, the larger the residual magnetic flux. There
Then, the energization suspension period T_IAnd pilot injection period Tp
As an actuator, determine the voltage applied to the drive solenoid 30
I am trying to do it.

For example, in FIG. 4, the energization suspension period is T
_{When Ia} and the pilot injection period are T _Pa , Vtha is set as the boosting completion voltage. Further, as shown in FIG. 4, the boost completion voltage in the normal injection mode is the maximum value of the boost completion voltage in the pilot injection mode. That is, in the pilot injection mode, a voltage lower than that in the normal injection mode is set as the voltage applied to the drive solenoid 30.

In the present embodiment, the ECU 4 comprises a mode setting means, a solenoid applied voltage changing means, and an energization control means. Next, the operation of the fuel injection control device for the diesel engine configured as described above will be described.

FIG. 6 is a flowchart showing the contents of processing executed by the ECU 4. In step 100, the ECU 4 detects the load state of the engine with the accelerator opening sensor and detects the engine speed with the cam angle sensor. Then, in step 101, the ECU 4 determines whether or not pilot injection is necessary according to the operating state of the engine. More specifically, it is determined whether or not pilot injection is necessary using a map based on the engine load state by the accelerator opening sensor and the engine speed by the cam angle sensor.

When the ECU 4 determines in step 101 that pilot injection is not necessary, it sets the normal injection mode and executes the following processing. First, the ECU 4 calculates the injection timing and injection amount in step 102. That is, the injection start timing Tm1 and the injection end timing Tm2 are obtained. Then, in step 103, the ECU 4 sets the boost completion voltage Vth, which is a fixed value, as the comparison value of the comparator 39 in the solenoid valve drive circuit 5.

As a result, the voltage applied to the predetermined drive solenoid 30 is set by the boosting operation of the solenoid valve drive circuit 5. When the ECU 4 determines in step 104 that the injection start timing Tm1 has been reached based on the signal from the cylinder sensor, it outputs a drive pulse to the transistor Tr2 of the solenoid valve drive circuit 5 shown in FIG. The transistor Tr2 is turned on to start energizing the drive solenoid 30 of the three-way solenoid valve 17. On this occasion,
A current flows from the capacitor 35 of FIG. 2 to the drive solenoid 30, the nozzle lift operation of the fuel injection valve 3 is performed, and the fuel injection valve 3 opens. Further, after the valve is opened, a constant current flows from the constant current circuit 40 of FIG. 2 to the drive solenoid 30, and the open state is maintained by the constant current.

Further, when the ECU 4 similarly determines in step 106 that the injection end timing Tm2 has come, step 1
At 07, the output of the drive pulse to the transistor Tr2 of the solenoid valve drive circuit 5 is finished (the level is lowered) to turn off the transistor Tr2, and the energization of the drive solenoid 30 of the three-way solenoid valve 17 is finished. As a result, the fuel injection valve 3 is closed.

As described above, in the normal injection mode, the drive solenoid 30 is energized once to perform the main injection.
On the other hand, when the ECU 4 determines in step 101 that the pilot injection is necessary, the ECU 4 sets the pilot injection mode and executes the following processing.

First, in step 108, the ECU 4 calculates the pilot injection timing and injection amount, and the main injection timing and injection amount. That is, the pilot injection start timing Tp1
Also, the pilot injection end timing Tp2, the main injection start timing Tm1 and the main injection end timing Tm2 are obtained.

Then, in step 109, the ECU 4 obtains an energization suspension period T _I determined by the pilot injection end timing Tp2 and the main injection start timing Tm1, and a pilot injection period Tp determined by the pilot injection start timing Tp1 and the pilot injection end timing Tp2. Furthermore, the ECU 4
Calculates the boosting completion voltage Vth from the map shown in FIG. 4 from the energization suspension period T _I and the pilot injection period Tp, and sets this value as the comparison value of the comparator 39 in the solenoid valve drive circuit 5.

As a result, the voltage applied to the predetermined drive solenoid 30 is set by the boosting operation of the solenoid valve drive circuit 5. When the ECU 4 determines in step 110 that the pilot injection start timing Tp1 has been reached based on the signal from the cylinder sensor, it outputs a drive pulse to the transistor Tr2 of the solenoid valve drive circuit 5 shown in FIG. Then, the transistor Tr2 is turned on to start energizing the drive solenoid 30 of the three-way solenoid valve 17. At this time, a current flows from the condenser 35 of FIG. 2 to the drive solenoid 30, the nozzle lift operation of the fuel injection valve 3 is performed, and the fuel injection valve 3 opens. Further, after the valve is opened, a constant current flows from the constant current circuit 40 of FIG. 2 to the drive solenoid 30, and the open state is maintained by the constant current.

Further, when the ECU 4 similarly determines in step 112 that the pilot injection end timing Tp2 has come, in step 113 the output of the drive pulse to the transistor Tr2 of the electromagnetic valve drive circuit 5 is ended (the level is lowered). ) The transistor Tr2 is turned off and the three-way solenoid valve 17
The energization of the drive solenoid 30 is terminated. as a result,
The fuel injection valve 3 closes. In this way, pilot injection is performed.

Thereafter, when the ECU 4 determines in step 104 that the main injection start timing Tm1 has been reached, step 10
At 5, the energization of the drive solenoid 30 of the three-way solenoid valve 17 is started. Further, when the ECU 4 similarly determines in step 106 that the main injection end timing Tm2 has been reached, step 10
At 7, the energization of the drive solenoid 30 of the three-way solenoid valve 17 is terminated. The main injection is performed in the processing of steps 104 to 107.

In this way, in the pilot injection mode, the drive solenoid 30 is energized twice to perform pilot injection and main injection. In this main injection, a predetermined voltage value lower than the applied voltage in the normal injection mode is set as the applied voltage to the drive solenoid 30,
The drive solenoid 30 has a current I flowing in the normal injection mode.
_The current flows after subtracting the current increase due to the residual magnetic flux from _NOR . Therefore, the current flowing through the drive solenoid 30 during the main injection in the pilot injection mode is always a constant value, and the time Δt3 (shown in FIG. 3) from the injection start timing to the start of the nozzle lift of the fuel injection valve 3 is always constant. be able to. As a result, suitable fuel injection control can be realized.

As described above, in this embodiment, the ECU 4 operates as shown in FIG.
By the process of step 101, either the normal injection mode or the pilot injection mode is set according to the operation state of the diesel engine, and in the normal injection mode, a fixed value is set to the drive solenoid 30 of the fuel injection valve 3 by the process of step 103. In the pilot injection mode, the voltage lower than that in the normal injection mode is set as the voltage applied to the drive solenoid 30 of the fuel injection valve 3 in the pilot injection mode. Therefore, the main injection after the pilot injection can be accurately performed in consideration of the generation of the residual magnetic flux.

Further, by lowering the voltage applied to the solenoid in the pilot injection mode, it is possible to reduce the energy consumption of the solenoid valve drive circuit (boosting circuit) 5 without deteriorating the response of the solenoid valve. Further, it is preferable for the ECU 4 to lower the voltage of the solenoid valve drive circuit (step-up circuit) 5 because the heat generation of the solenoid valve drive circuit (step-up circuit) 5 can be reduced.

Further, the ECU 4 executes step 109 in FIG.
In the above process, the voltage applied to the drive solenoid 30 in the pilot injection mode is determined by the pilot injection period Tp and the energization suspension period T _I using the map of FIG. Therefore, the applied voltage can be adjusted more accurately in consideration of the residual magnetic flux.

As another aspect of the present invention, in addition to the fuel injection control device for the diesel engine, a single-shot valve opening operation mode in which only one valve opening operation is performed and a plurality of consecutive valve opening operations are performed. While switching the continuous valve opening operation mode, the drive solenoid is energized once to perform one valve opening operation in the single-shot valve opening mode, and the drive solenoid is energized multiple times in the continuous valve opening operation mode to continuously It can be embodied in a device that performs the valve opening operation described above a plurality of times.

[0046]

As described in detail above, according to the invention described in claim 1, in the continuous valve opening operation mode in which the valve opening operation is continuously performed a plurality of times, the second and subsequent times are taken into consideration in consideration of the generation of residual magnetic flux. The valve opening operation can be accurately performed, and an excellent effect of reducing energy consumption can be achieved.

According to the second aspect of the present invention, the main injection after the pilot injection can be accurately performed in consideration of the generation of the residual magnetic flux, and the energy consumption can be reduced.

According to the invention of claim 3, claim 2
In addition to the effect of the invention described in (1), the applied voltage can be adjusted more accurately in consideration of the residual magnetic flux.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a fuel injection control device for a diesel engine.

FIG. 2 is a configuration diagram of an electromagnetic drive circuit.

FIG. 3 is a timing chart.

FIG. 4 is a map for determining an applied voltage value.

FIG. 5 is a characteristic diagram showing residual magnetic flux.

FIG. 6 is a flowchart for explaining the operation.

[Explanation of symbols]

3 ... Fuel injection valve, 4 ... Mode setting means, solenoid applied voltage changing means, ECU as energization control means, 17 ... Three-way solenoid valve, 30 ... Drive solenoid

Claims (3)

[Claims] 1. A solenoid valve which is opened by energizing a drive solenoid, a single-shot opening operation mode in which only one opening operation is performed, and a continuous opening operation mode in which a plurality of consecutive valve opening operations are performed. And a solenoid applied voltage changing means for setting a voltage lower than that in the single-shot valve opening operation mode in the continuous valve opening operation mode by the mode setting means as the voltage applied to the drive solenoid of the solenoid valve. And, in the single-valve opening operation mode by the mode setting means,
An energization control unit that energizes the drive solenoid once to perform a single valve opening operation, and energizes the drive solenoid a plurality of times to perform a plurality of consecutive valve opening operations in a continuous valve opening operation mode. An electromagnetic valve drive device comprising: 2. A fuel injection control device for an internal combustion engine, wherein the solenoid valve is used for a fuel injection valve that injects high-pressure fuel when the valve is open, and the mode setting means includes: A normal injection mode in which only main injection is performed according to the operating state of the internal combustion engine, and one of the pilot injection modes in which pilot injection is also performed prior to main injection is set, and the solenoid applied voltage changing means is In the pilot injection mode, a voltage lower than that in the normal injection mode is set as an applied voltage to the drive solenoid of the fuel injection valve, and the energization control means energizes the drive solenoid once in the normal injection mode. While making the main injection,
2. The solenoid valve drive system according to claim 1, wherein in the pilot injection mode, the drive solenoid is energized twice to perform pilot injection and main injection. 3. The solenoid applied voltage changing means determines an applied voltage to the drive solenoid in the pilot injection mode based on an energization period for pilot injection and an energization suspension period between pilot injection and main injection. The electromagnetic valve drive device according to claim 2, wherein