JPH11210530A - Fuel injection controller for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten an excitation duration to a solenoid coil so as to suppress heat generation in the solenoid coil by providing a flyback energy collection function for flyback energy generated when excitation to the solenoid coil of a discharge quantity control valve in a supply pump is shut off and impressing this energy to an injector at the predetermined timing. SOLUTION: According to valve closing of a PCV (discharge quantity control valve) 15 of a supply pump 1, fuel pressurized by a rising action of a plunger 9 is fed to a common rail 25, and a valve closing timing of the PCV 15 is regulated by means of an ECU 41, so that a fuel discharge quantity is controlled. High pressure fuel inside the common rail 25 is jetted to respective cylinders from injectors 29-32. In this process, flyback energy generated when excitation to a solenoid coil 19 in the PCV 15 is shut off is accumulated in a first condenser, while flyback energy generated when a fuel force feeding stroke term is finished is accumulated in a second condenser in addition to the energy accumulated in the first condenser, and this accumulated energy is used for driving the injectors.

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 apparatus for an internal combustion engine called a common rail type, which injects high pressure fuel stored in a common rail from an injector mounted on each cylinder of the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, as a prior art document relating to a fuel injection control device for an internal combustion engine, there is Japanese Patent Application Laid-Open No. Hei 8-210170.
The one disclosed in Japanese Patent Application Publication No. HEI 10-203 (1995) is known. This discloses a technique in which a common rail fuel injection control device for a diesel engine drives an injector using flyback energy (flyback current) generated when power supply to an electromagnetic coil is cut off. It is equipped with a diesel engine, a supply pump, and a common rail, and has a normally open electromagnetic pressure control valve (Pressure Control Valve: hereafter referred to as P
Flyback energy generated at the time of driving (CV) is stored in a capacitor, and this energy is used when the electromagnetic coil of the injector is energized.

That is, in recent years, in order to improve the performance of an internal combustion engine, there has been an increasing demand for driving an injector at a high voltage and a large current to instantaneously open a valve and perform fuel injection. In this case, the injector driving voltage is 100 [V: Volts] or more, and a drive current of about 8 [A: ampere] is required. Therefore, PC
Flyback energy generated when the power supply to the V electromagnetic coil is cut off is accumulated as energy for driving the injector and discharged when the injector is driven. Also, instead of accumulating the energy required to drive the injector by energizing the dedicated charging coil, using a PCV electromagnetic coil instead of the dedicated coil reduces the number of parts and reduces cost. it can.

More specifically, flyback energy (magnetic energy) defined by the coil inductance L, the current, and the like is generated when the power supply to the electromagnetic coil is cut off, and this energy is stored in the charging capacitor. As a result, energy of 100 V or more can be stored in the capacitor. The injector is driven at the timing specified by the engine speed, battery voltage, etc.
When the injector is driven, energy of 100 V or more stored in the charging capacitor in advance is discharged to the injector side.

[0005]

By the way, during the fuel pumping process from the supply pump to the common rail, the PC
If a saturation current is continuously supplied to the electromagnetic coil of the PCV as the PCV conduction current to maintain the V-valve closed state, the electromagnetic coil may generate heat and wasteful power consumption may occur.

Accordingly, the present invention has been made to solve such a problem, and an internal combustion engine having a function of recovering flyback energy generated when power supply to a solenoid coil of a PCV (discharge amount control valve) of a supply pump is cut off. It is an object of the present invention to provide a fuel injection control device for an internal combustion engine that can reduce a period of energizing an electromagnetic coil of a PCV during a fuel pumping stroke period and suppress heat generation of the electromagnetic coil.

[0007]

According to the fuel injection control device for an internal combustion engine of the present invention, when the supply pump PCV is closed by the coil energizing means, the fuel discharge amount control means controls the fuel supply from the supply pump to the common rail. The discharge amount is controlled, and the high-pressure fuel stored in the common rail is injected and supplied from the injector to each cylinder of the internal combustion engine by the injector driving means. Here, flyback energy generated at the time of the first interruption of energization of the electromagnetic coil of the PCV by the energization interruption means may affect the fuel injection amount from the injector, and is therefore separated from the drive system of the injector. And stored by the first energy storage means. The flyback energy generated at the end of the second pressure supply to the electromagnetic coil of the PCV by the power supply cut-off means at the end of the fuel supply stroke period of the fuel by the PCV is the flyback energy stored by the first energy storage means. At the same time, it is stored by the second energy storage means. That is, the PCV is energized to the electromagnetic coil at the beginning of the fuel feeding stroke period, and once closed, the valve is kept closed even if energization is not continued. The first flyback energy generated at this time is temporarily stored separately from the driving source of the injector so as not to affect the driving of the injector. Then, at the end of the fuel pumping stroke period, the PCV energizing current to the electromagnetic coil of the PCV is re-energized so as to become a saturation current, and cut off at the end of the fuel pumping stroke period. Since the fuel injection by the injector has been completed, the second flyback energy generated at this time is accumulated together with the first flyback energy so as to be the next drive source of the injector. As a result, it is not necessary to maintain the power supply to the electromagnetic coil of the PCV throughout the fuel pumping stroke, and the amount of heat (power consumption) in the electromagnetic coil of the PCV is reduced. In addition, the flyback energy generated in the electromagnetic coil of the PCV is efficiently recovered each time, so that the durability of the PCV itself against heat (temperature) is greatly improved.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a schematic diagram showing a four-cylinder diesel engine to which an internal combustion engine fuel injection control device according to an embodiment of the present invention is applied, and FIG. It is sectional drawing which shows a detailed structure. In addition,
FIG. 2A is a sectional view showing a cam shape fixed vertically to the drive shaft of the supply pump, and FIG. 2B is a right side view of FIG. 2A parallel to the drive shaft of the supply pump. It is sectional drawing.

1 and 2, reference numeral 1 denotes a one-cylinder type supply pump (high-pressure pump). The supply pump 1 is provided with a drive shaft 2, and the drive shaft 2 is provided for a diesel engine (internal combustion engine) 3. It is connected to the crankshaft 4. A substantially elliptical cam 5 is fixed to the drive shaft 2. A cylinder 7 is provided in the supply pump 1, and a plunger 9 that slides while contacting the cam surface of the cam 5 is inserted into the cylinder 7. For this reason, the plunger 9 moves downward in the drawing with the rotation of the cam 5, and the plunger chamber (pressurizing chamber) 11 in the cylinder 7 is fed into the fuel tank 14 via the feed pump (low-pressure pump) 13. Is inhaled. In addition, as shown in FIG. 2B, the feed pump 13 is built in the supply pump 1 main body,
The fuel in the fuel tank 14 is supplied to the plunger chamber 11 by the movement of the vane accompanying the drive of the drive shaft 2.

A PCV (normally open type electromagnetic discharge amount control valve) 15 is disposed above the cylinder 7.
The PCV 15 opens and closes a fuel supply passage from the feed pump 13. That is, the PCV 15 is the valve 1
7, spring 18 and electromagnetic coil (solenoid coil)
When the electromagnetic coil 19 is energized, the valve element 17 is moved against the urging force of the spring 18 and closed from the previously opened state. And PCV1
When the plunger 9 is raised in the valve closed state of 5, the pressurizing operation (pressure feeding operation) of the fuel in the plunger chamber 11 is performed. The amount of fuel discharged from the supply pump 1 is adjusted by adjusting the valve closing timing of the PCV 15 during this pressurizing operation.

The plunger chamber 1 of the supply pump 1
Reference numeral 1 is connected to a high-pressure accumulating pipe common to each cylinder, a so-called common rail 25, via a fuel supply pipe 23. A check valve 26 is disposed at an end of the fuel supply pipe 23 on the supply pump 1 side. The check valve 26 allows fuel to pass from the supply pump 1 side to the common rail 25 side. The passage of fuel from the side to the supply pump 1 side is prevented. In addition, injectors (fuel injection valves) 29, 30, 31, 32 of each cylinder of the diesel engine 3 are connected to the common rail 25 via a branch pipe 28. The injectors 29, 30, 31, and 32 are provided with three-way solenoid valves 33, 34, 35, and 36, respectively, and these three-way solenoid valves 33, 34, 35, and 36 are controlled to be on / off. High-pressure fuel from the common rail 25 is injected into each cylinder from injection ports of injectors 29, 30, 31, and 32. The three-way solenoid valves 33, 3
The fuel passage on the leak side for returning fuel from the fuel tanks 4, 35, 36 to the fuel tank 14 is not shown.

Reference numeral 41 denotes an ECU (Electronic Control Unit).
The ECU 41 includes a microcomputer 42 and a drive circuit 43. The microcomputer 42 includes a crank angle sensor 44, a cylinder determination sensor 45, an accelerator opening sensor 46, and the like.
, And information such as the accelerator opening from an accelerator pedal (not shown). Here, as shown in FIG. 2, the cylinder discriminating sensor 45 has a gear 45a fixed to the drive shaft 2 of the supply pump 1, and generates a pulse signal when the gear 45a passes along with the rotation of the drive shaft 2. Generated. And the microcomputer 4
2, the drive circuit 43 is driven so as to obtain the optimal fuel injection timing and fuel injection amount determined according to the operating state of the internal combustion engine determined by these input signals, and each of the injectors 29, 30, 31, 32 Three-way solenoid valve 33, 3
4, 35 and 36 are controlled.

That is, the microcomputer 42 calculates the fuel injection timing and the fuel injection amount according to the engine speed and the accelerator opening as the operating state of the diesel engine 3, and the three-way electromagnetic of the injectors 29, 30, 31, and 32 is calculated. The valves 33, 34, 35 and 36 are controlled to open and close, and the common rail 2
5 is injected into each cylinder of the diesel engine 3.
Here, at the time of fuel injection in each cylinder of the diesel engine 3 of the present embodiment, main injection and pilot injection preceding the main injection are performed from the injectors 29, 30, 31, and 32. For this reason, as will be described later, the microcomputer 42 uses the injector 42 as the injector drive signal (injection pulse) for the injectors 29, 30, 31, 32 as the injector drive current (P) corresponding to the injector supply current (P). Is generated.

The microcomputer 42 is connected to the electromagnetic coil 19 of the PCV 15 via a drive circuit 43, and the PCV 15 is opened and closed by turning the electromagnetic coil 19 on and off. Then, a common rail pressure signal detected by a common rail pressure sensor 47 provided on the common rail 25 is input to the microcomputer 42, and the common rail pressure becomes an optimum value set according to the engine speed, the accelerator opening, and the like. Yo PCV
15 is controlled, and the amount of fuel discharged from the supply pump 1 is adjusted. In other words, the cam 5 of the supply pump 1 is rotated by the start of the diesel engine 3, and the plunger 9 is reciprocated with this rotation, so that the fuel from the feed pump 13 is supplied to the supply pump 1 and the high-pressure fuel is supplied to the fuel supply pipe. The fuel is supplied to the common rail 25 through 23, and the high-pressure fuel is stored in the common rail 25. Therefore, the microcomputer 42 controls the amount of fuel discharged from the supply pump 1 so that the common rail pressure by the common rail pressure sensor 47 becomes an optimum value set in accordance with the engine speed, the accelerator opening, and the like.

Next, the electrical configuration of the ECU 41 comprising the microcomputer 42 and the drive circuit 43 will be described with reference to FIG.
This will be described with reference to FIG.

The ECU 41 includes a microcomputer 42 for performing fuel injection control and the like and a P
A MOS field-effect transistor (MOSFET: hereinafter, referred to as a “MOS transistor”) 51 as a PCV driving switching element for driving the electromagnetic coil 19 of the CV 15, 1 when the MOS transistor 51 is on / off controlled An auxiliary capacitor 72 for charging and accumulating the second flyback energy via the charging switching element 71 and the second flyback energy when the MOS transistor 51 is controlled to be on / off are PCV-
The main injection capacitor 53 and the pilot injection capacitor 54 charge and accumulate via the capacitor connection switching element 52 and simultaneously charge and accumulate the flyback energy accumulated in the auxiliary capacitor 72 via the discharge switching element 73. The switching element 55 for separating main injection voltage or the switching element 56 for separating pilot injection voltage is appropriately driven using the flyback energy stored in the condenser 53 and the pilot injection condenser 54, and the injectors 29, 30, 31, 32 are operated. Three-way solenoid valves 33, 34, 3
MOS transistors 57 as switching devices for driving injectors for driving the coils 5 and 36,
58, 59, 60 and the like.

The electromagnetic coil 19 of the PCV 15 and the MOS transistor 51 are connected in series to the battery power supply + B terminal. The auxiliary capacitor 7 is connected to the electromagnetic coil 19 of the PCV 15 via the charging switching element 71.
2 are connected in series. PCV15 electromagnetic coil 1
9 and the MOS transistor 51 have a connection point a
A main injection capacitor 53 and a pilot injection capacitor 54 are connected in parallel via a CV-capacitor connection switching element 52 and a diode. The auxiliary switching capacitor 72 is connected to the discharge switching element 7.
3 and the main injection capacitor 53 via the diode
And a pilot injection capacitor 54 are connected in series. The three-way solenoid valves 33, 33 of the injectors 29, 30, 31, 32 are connected to the main injection capacitor 53 via a switching element 55 for separating the main injection voltage.
34, 35, and 36 coils are connected in parallel. Similarly, the three-way solenoid valves 33, 3 of the injectors 29, 30, 31, 32 are connected to the pilot injection capacitor 54 via the switching element 56 for separating the pilot injection voltage.
4, 35, 36 coils are connected in parallel. MOS transistors 57, 58, 59, and 60 are connected in series to the coils of the three-way solenoid valves 33, 34, 35, and 36, respectively. In addition, injectors 29 and 3
0, 31, 32 three-way solenoid valves 33, 34, 35, 36
Is connected to a constant current circuit 63.

The microcomputer 42 has the above-mentioned MO.
The gates of the S-transistors 51, 57, 58, 59, 60 and the bases of the switching elements 52, 55, 56, 71, 73 are connected to each other.
Are turned on / off by the control. Where MO
When the S transistor 51 is turned on by the PCV drive signal from the microcomputer 42, the electromagnetic coil 1
9, and the PCV 15 is closed. Where MOS
The transistor 51 is turned on / off, and the electromagnetic coil 1
Among the flyback energies generated when the power supply to the power supply 9 is cut off, the first flyback energy is supplied to the auxiliary capacitor 72 via the charging switching element 71 which is turned on at a predetermined timing by a charging signal from the microcomputer 42. Stored. The second flyback energy is stored in the main injection capacitor 53 and the pilot injection capacitor 54 via the PCV-capacitor connection switching element 52 which is turned on at a predetermined timing by the PCV-capacitor connection signal. At the same time, the first flyback energy accumulated in the auxiliary capacitor 72 via the discharge switching element 73 which is simultaneously turned on by the discharge signal from the microcomputer 42 is also used as the main injection capacitor 5.
3 and the pilot injection capacitor 54.
As a result, the main injection condenser 53 stores energy for the main injection of the injectors 29, 30, 31, 32, and the pilot injection condenser 54 stores the energy for the pilot injection of the injectors 29, 30, 31, 32. Energy is stored.

Further, each of the MOS transistors 57, 58,
59 and 60 are turned on by the INJ1 drive signal corresponding to the injector 29, the INJ2 drive signal corresponding to the injector 30, the INJ3 drive signal corresponding to the injector 31, and the INJ4 drive signal corresponding to the injector 32 from the microcomputer 42. And the energy stored in one of the main injection condenser 53 and the pilot injection condenser 54 is supplied to the three-way solenoid valves 33, 34, 35, 36 and the injectors 29,
Fuel is injected from 30, 31, and 32. At this time, one of the main injection voltage disconnecting switching element 55 and the pilot injection voltage disconnecting switching element 56 is turned on by the main disconnection signal or the pilot disconnection signal from the microcomputer 42, so that the main injection capacitor 53 is turned on. Alternatively, one of the pilot injection capacitors 54 is selected.

That is, from the state in which energy is stored in the main injection capacitor 53 and the pilot injection capacitor 54, during the pilot injection, the main injection voltage disconnecting switching element 55 is turned off and the pilot The pilot injection voltage disconnecting switching element 56 is turned on by the disconnection signal. As a result, the capacitor voltage from the pilot injection condenser 54 is supplied to any one of the three-way solenoid valves 33, 34, 35, 36 in a state where the main injection voltage is disconnected, and the fuel is supplied from the injectors 29, 30, 31, 32, Pilot injection is performed. Subsequently, at the time of the main injection, the switching element 5 for disconnecting the pilot injection voltage is used.
When the switch 6 is off, the main injection voltage disconnecting switching element 55 is turned on by a main disconnection signal from the microcomputer 42. As a result, any one of the three-way solenoid valves 33,
The capacitor voltage from the main injection capacitor 53 is supplied to the injectors 34, 35, and 36, and the injectors 29, 30, 3
Main injection of fuel is performed from 1 and 32.

It is preferable that the capacitance value C of the auxiliary capacitor 72 be lower than the total capacitance value of the main injection capacitor 53 and the pilot injection capacitor 54. Because, from the relation of Q = (1/2) · C · V ² ,
By setting the auxiliary capacitor voltage V to a voltage relatively higher than the main capacitor voltage value or the pilot capacitor voltage value, when the discharge switching element 73 is turned on, the auxiliary capacitor 72 causes the main injection capacitor 53 and the pilot injection This is because the charge Q is more efficiently transferred to the capacitor 54.

Next, a description will be given with reference to the timing chart of FIG. 4 showing the transition state of each signal in the fuel injection control for the diesel engine configured as described above.

FIG. 4 shows N from the crank angle sensor 44.
E (engine speed) signal, cam lift of supply pump 1, PCV drive signal for MOS transistor 51 driving electromagnetic coil 19 of PCV 15, PCV energizing current of electromagnetic coil 19 of PCV 15, pilot capacitor voltage of pilot injection capacitor 54, Main capacitor voltage of main injection capacitor 53, auxiliary capacitor voltage of auxiliary capacitor 72, PCV-capacitor connection signal for PCV-capacitor connection switching element 52, charge signal for charging switching element 71, discharge signal for discharge switching element 73 , A pilot disconnection signal for the pilot injection voltage disconnection switching element 56, a main disconnection signal for the main injection voltage disconnection switching element 55, the injectors 29, 30, 31 32 each three-way solenoid valve of 33,3
Injectors (INJ1, INJ1,
J2, INJ3, INJ4) drive signal, injector 2
9, 30, 31, any of the three-way solenoid valves 33, 3
4, 35, and 36 injector currents 1, 2 are shown. Note that the diesel engine in this embodiment is a four-cylinder engine, and the cycle of the pulse numbers “0” to “0” corresponding to the NE signal shown in FIG. 4 is 180 ° CA (Crank Angle). One pulse is 15 ° CA.

In FIG. 4, during the fuel suction stroke of the supply pump 1 accompanying the cam lift (up and down movement of the plunger 9) due to the rotation of the cam 5 fixed to the drive shaft 2, the PCV 15 disposed on the supply pump 1 Is opened, and fuel is sucked into the plunger chamber 11 from the fuel tank 14. Supply pump 1 with cam lift
Is a fuel feeding stroke period, and the PCV 15 is changed from the previously opened state to the closed state, so that the cam 5 pushes up the plunger 9 so that the fuel in the plunger chamber 11 reaches a desired fuel pressure (fuel pressure). By being raised, it is in a pumping state.

At this time, the control of the fuel pressure and the fuel injection amount is executed by the microcomputer 42. At this time, it is determined at which timing in the fuel pumping stroke period of the cam 5 the PCV 15 is closed. You. When high pressure is required in the common rail 25, the valve closing operation is performed relatively early, and when low pressure is required, the valve closing operation is performed relatively late. And
When the fuel pressure in the common rail 25 is increased to a desired level, the three-way solenoid valves 33, 34, 35, and 36 are driven to open the injectors 29, 30, 31, and 32, and after fuel is injected, the PCV 15 is opened. The valve state is set. Or later,
This operation is sequentially repeated.

In the microcomputer 42, the supply pump 1 comprising a suction stroke period and a pressure feeding stroke period
The operation state of the diesel engine 3 is determined using the reference rotation angle signal. That is, the NE signal from the crank angle sensor 44 shown in FIG. 1 is used as the reference rotation angle signal of the crankshaft 4 of the diesel engine 3, and the signal from the cylinder discrimination sensor 45 (the cylinder discrimination signal) The number of pulses based on the NE signal is counted, and the start of PCV pumping, the end of pumping, the start of fuel injection, etc. are determined based on the pulse number corresponding to the NE signal.

In the microcomputer 42,
MOS transistor 51, P for closing valve of PCV15
CV15 electromagnetic coil 19 and main injection capacitor 5
3 and P connecting pilot injection capacitor 54
Switching element 52 for CV-capacitor connection, switching element 55 for separating main injection voltage of main injection capacitor 53, switching element 56 for separating pilot injection voltage of pilot injection capacitor 54, and fuel injection by injectors 29, 30, 31, 32. For driving each of the MOS transistors 57, 58, 59, 60 is calculated based on the engine speed, the battery power supply voltage, and the like. The microcomputer 42
At a predetermined timing in the fuel intake stroke period and the fuel supply stroke period defined by the NE signal shown in FIG.
When the OS transistor 51 is turned on, the PCV
During the period when the drive signal is turned on at the first and second timings, the PCV 15 is closed. At this time, PC
Magnetic energy by pulse driving is generated in the electromagnetic coil 19 of V15.

The magnetic energy Q [J: Joule] is
Inductance L of electromagnetic coil 19 and conduction peak current I
Is calculated by the following equation (1) from the driving pulse frequency f.

[0030]

Q = (１ ／) · L · I ² · f (1) The magnetic energy Q is called flyback energy of the coil. The start time and the on-time (pulse width) of the pumping drive pulse are defined by the fuel injection control system. The injector drive pulse specification is defined by the corresponding diesel engine fuel injection system (number of cylinders / maximum rotational speed). When the injector is driven, the MOS transistors 57, 58, 59, 60 are synchronized with the fuel injection timing.
Is driven. At this time, for example, as shown by the injector conduction current 1, the pilot injection charging energy of 100 [V] or more from the pilot injection capacitor 54 and the main injection charging energy of 100 [V] or more from the main injection capacitor 53 are generated. The corresponding injector 29,
30, 31, 32. At this time, the three-way solenoid valves 33, 33 of the injectors 29, 30, 31, 32
A current of about 8 [A] flows through 34, 35, and 36, the valve is opened, and fuel is injected. Injectors 29, 30, 3
After the three-way solenoid valves 33, 34, 35, and 36 are driven at a high voltage, a constant current flows from the constant current circuit 63 shown in FIG. The valve state is maintained.

Next, the EC used in the fuel injection control device for the internal combustion engine according to one embodiment of the present invention will be described.
A description will be given with reference to the above-described timing chart of FIG. 4 based on the flowchart of FIG. 5 showing the main processing procedure of the fuel injection control in the microcomputer 42 in the U41. Note that this main routine is NE (engine speed).
The program is repeatedly executed by the microcomputer 42 in the ECU 41 every predetermined time corresponding to the signal.

In FIG. 5, at step S101, NE
It is determined whether the pulse number corresponding to the signal is “1” (see FIG. 4). The determination condition of step S101 is satisfied,
That is, when the pulse number corresponding to the NE signal is "1", the process proceeds to step S102, and the target fuel injection amount, the target fuel injection timing, and the target common rail pressure corresponding to the operation state at this time are calculated. On the other hand, when the determination condition of step S101 is not satisfied, that is, when the pulse number corresponding to the NE signal is not “1”, the processing of step S102 is skipped. Next, the process proceeds to step S103, and other processes other than the process related to the internal combustion engine, for example, A
/ T (automatic transmission) and the like are executed, and this routine ends.

Next, the EC used in the fuel injection control device for the internal combustion engine according to one embodiment of the present invention will be described.
A description will be given with reference to the above-described timing chart of FIG. 4 based on the flowchart of FIG. 6 showing the NE interruption processing procedure of the fuel injection control in the microcomputer 42 in the U41. The NE interruption routine is repeatedly executed by the microcomputer 42 in the ECU 41 for each predetermined pulse number based on the NE (engine speed) signal.

In FIG. 6, at step S201, NE
It is determined whether the pulse number corresponding to the signal is the PCV calculation timing of “8” (see FIG. 4). Step S2
When the determination condition of 01 is satisfied, that is, when the pulse number corresponding to the NE signal is the PCV calculation timing of "8", the process proceeds to step S202, and the battery power supply voltage is checked (detected). Next, the process proceeds to step S203.
The start timing of the PCV drive signal to the electromagnetic coil 19 of the PCV 15 in the first PCV energization 1 and the second PCV energization 2 and their pulse widths are calculated. Here, the start timing of PCV energization 1 and PCV energization 2 is calculated based on a target common rail pressure, a target fuel injection amount, and the like.
Those pulse widths are calculated based on the battery power supply voltage and the like. On the other hand, the determination condition of step S201 is not satisfied,
That is, the PCV whose pulse number corresponding to the NE signal is “8”
If it is not the calculation timing, steps S202 and S203 are skipped.

Next, the flow shifts to step S204, where it is determined whether or not the pulse number corresponding to the NE signal is the injector calculation timing of "10" (see FIG. 4). If the determination condition of step S204 is satisfied, that is, if the pulse number corresponding to the NE signal is the injector calculation timing of “10”, the process proceeds to step S205, and the three-way solenoid valves 33, 34 of the injectors 29, 30, 31, 32 are moved. ,
The start timing and the pulse width of pilot energization for pilot injection by the injector drive signal for 35 and 36, and the start timing and pulse width of main energization for main injection are calculated. On the other hand, if the determination condition in step S204 is not satisfied, that is, if the pulse number corresponding to the NE signal is not the injector calculation timing of “10”, step S205 is skipped.

Next, the process proceeds to step S206, where the PCV
It is determined whether it is time to start the first PCV energization 1 of the PCV drive signal for the 15 electromagnetic coils 19. The determination condition in step S206 is satisfied, that is, the first PCV of the PCV drive signal for the electromagnetic coil 19 of the PCV 15
If it is the time to start the energization 1, the process proceeds to step S207, where the MOS transistor 51 is turned on, and the PCV
The electromagnetic coil 19 of the PCV 15 is driven by the pulse width of the energization 1. At this time, the PCV energizing current to the electromagnetic coil 19 of the PCV 15 transitions as shown in FIG.
That is, in the first drive of the electromagnetic coil 19 of the PCV 15, the PCV 15 is completely closed after a predetermined time.
Considering the predetermined time, the PCV conduction current is set to the predetermined current value I.
The MOS transistor 51 is turned on only during the period until it reaches 1, so that the electromagnetic coil 19 of the PCV 15 is energized. Since the valve closing time of the PCV 15 changes according to the fluctuation of the battery power supply voltage, the microcomputer 42 previously stores the PCV 15 with respect to the battery power supply voltage.
Is stored. Therefore, the microcomputer 42 monitors the battery power supply voltage, and supplies the PCV 15 with the PCV current for the valve closing time at that time. When the PCV 15 is closed and the first energization cutoff timing is reached, the supply of the PCV energization current is stopped. At this point, flyback energy is generated in the electromagnetic coil 19 of the PCV 15.

Next, in step S208, the path to the auxiliary capacitor 72 is connected by the ON operation of the charging switching element 71 by the charging signal, and the flyback energy generated by the electromagnetic coil 19 of the PCV 15 is transferred to the auxiliary capacitor 72. And recovered as an auxiliary capacitor voltage (see FIG. 4). Note that this time is within the fuel pumping stroke period and is likely to overlap the fuel injection timing from the injectors 29, 30, 31, 32, and the flyback energy is reduced by the three-way solenoid valves of the injectors 29, 30, 31, 32. When the fuel flows to the sides 33, 34, 35, and 36, the fuel injection amount is delicately changed.
In addition, it is not efficiently collected by the pilot injection condenser 54. For this reason, flyback energy generated when the PCV energizing current to the electromagnetic coil 19 of the PCV 15 is cut off for the first time is reduced by the OFF operation of the PCV-capacitor connection switching element 52 and the discharge switching element 73, and the main injection capacitor 53. In a state where the path to the pilot injection capacitor 54 is cut off, the charging switching element 71 connected in series to the electromagnetic coil 19 of the PCV 15 is turned on to charge the auxiliary capacitor 72. On the other hand, step S
When the determination condition of 206 is not satisfied, that is, when it is not the start time of the first PCV energization 1 of the PCV drive signal for the electromagnetic coil 19 of the PCV 15, steps S207 and S208 are skipped.

Next, the flow shifts to step S209, where the three-way solenoid valves 33, 3 of the injectors 29, 30, 31, 32 are set.
It is determined which of 4, 35 and 36 is the pilot injection start timing. When the determination condition of step S209 is satisfied, that is, when it is the pilot injection start timing for any of the three-way solenoid valves 33, 34, 35, and 36 of the injectors 29, 30, 31, and 32, the process proceeds to step S210 and the injector drive signal One of the three-way solenoid valves 33, 34, 35, 36 of the injectors 29, 30, 31, 32 is driven by the pulse width of the pilot current.
At this time, the injector energizing currents 1, 2 corresponding to any one of the pilot injections of the three-way solenoid valves 33, 34, 35, 36 of the injectors 29, 30, 31, 32 transition as shown by (P) in FIG. Is done.

That is, when the pilot injection timing comes, the switching element 56 for disconnecting the pilot injection voltage is turned on, and the three-way solenoid valves 33, 34, 34 of the pilot injection capacitor 54 and the injectors 29, 30, 31, 32 are turned on.
The paths between 35 and 36 are connected. At the same time, MOS
One of the transistors 57, 58, 59, and 60 is turned on, and the three-way solenoid valves 33, 34, and 34 of the injectors 29, 30, 31, and 32 are supplied from the pilot injection capacitor 54.
A high voltage is applied to any of 35 and 36, and the injector is instantly opened. After a lapse of a predetermined time, the switching element 56 for disconnecting the pilot injection voltage is turned off, and the path is cut off. Then, any one of the MOS transistors 57, 58, 59, and 60 is turned on by the pulse width of the pilot current, and the constant current circuit 63 controls the injector at a constant current to maintain the valve open state for a predetermined time. On the other hand, if the determination condition in step S209 is not satisfied, that is, if it is not the time to start the pilot energization of the injector drive signal to any of the three-way solenoid valves 33, 34, 35, 36 of the injectors 29, 30, 31, 32, step S210. Is skipped.

Then, the process goes to step S211 to control the three-way solenoid valves 33, 3 of the injectors 29, 30, 31, 32.
It is determined which of 4, 35 and 36 is the main injection start timing. When the determination condition of step S211 is satisfied, that is, when it is the main injection start timing for any of the three-way solenoid valves 33, 34, 35, and 36 of the injectors 29, 30, 31, and 32, the process proceeds to step S212 and the injector drive signal Three-way solenoid valve 3 for injectors 29, 30, 31, 32 depending on the pulse width of main current
One of 3, 34, 35 and 36 is driven. At this time, the injector energizing currents 1, 2 corresponding to the main injection of any of the three-way solenoid valves 33, 34, 35, 36 of the injectors 29, 30, 31, 32 transition as shown by (M) in FIG. Is done.

That is, when the main injection timing comes, the switching element 55 for separating the main injection voltage is turned on, and the main injection capacitor 53 and the injector 29,
30, 31, 32 three-way solenoid valves 33, 34, 35, 36
Is connected. At the same time, any one of the MOS transistors 57, 58, 59, 60 is turned on, and the injectors 29, 3
A high voltage is applied to any of the three-way solenoid valves 33, 34, 35, 36 of 0, 31, 32, and their injectors are instantly opened. After a certain period of time, the main injection voltage disconnecting switching element 55 is turned off, and the path is cut off. Then, any one of the MOS transistors 57, 58, 59, 60 is turned on by the pulse width of the main current, and
The injector is controlled at a constant current by the constant current circuit 63, and the valve open state is maintained for a predetermined time. On the other hand, step S
The determination condition of 211 is not satisfied, that is, the injector 2
9, 30, 31, 32 three-way solenoid valves 33, 34, 35,
If it is not the time to start the main energization of the injector drive signal for any one of Steps 36, Step S212 is skipped.

Next, the processing shifts to step S213, where the PCV
It is determined whether it is time to start the second PCV energization 2 of the PCV drive signal for the 15 electromagnetic coils 19. The determination condition of step S213 is satisfied, that is, the second PCV of the PCV drive signal for the electromagnetic coil 19 of the PCV 15
If it is the time to start the energization 2, the process proceeds to step S214, where the MOS transistor 51 is turned on, and the PCV
The electromagnetic coil 19 of the PCV 15 is driven by the pulse width of the energization 2. At this time, the PCV energizing current to the electromagnetic coil 19 of the PCV 15 transitions as shown in FIG.
On the other hand, the determination condition of step S213 is not satisfied, that is,
If it is not the start time of the second PCV energization 2 of the PCV drive signal to the electromagnetic coil 19 of the PCV 15, step S214 is skipped.

Then, the flow shifts to step S215, where it is determined whether or not the pulse number corresponding to the NE signal is "6" and it is at the top dead center of the cam of the cam lift. If the determination condition of step S215 is satisfied, that is, if it is the top dead center of the cam, step S215
The flow shifts to 216, where the pressure lift stroke period of the cam lift is over, so that the driving of the electromagnetic coil 19 of the PCV 15 by the pulse width of the PCV energization 2 is forcibly stopped. at this point,
Flyback energy is generated in the electromagnetic coil 19 of the PCV 15. This second PCV15 electromagnetic coil 1
9, the flyback energy by the driving of Step 9
08 and the flyback energy collected in the main injection condenser 53 and the pilot injection condenser 54 together with the auxiliary condenser 72 minutes, and this routine ends. On the other hand, when the determination condition of step S215 is not satisfied, that is, when the cam is not at the top dead center of the cam lift, this routine ends.

Here, recovery of flyback energy to the main injection capacitor 53 and the pilot injection capacitor 54 by the auxiliary capacitor 72 minutes and the second drive of the electromagnetic coil 19 of the PCV 15 will be described. In the second drive of the electromagnetic coil 19 of the PCV 15, the MOS transistor 51 is turned on so that the PCV conduction current reaches the saturation current value Imax at the top dead center of the cam of the cam lift.
The energization of the electromagnetic coil 19 of the PCV 15 is executed. Immediately before the second stop of the PCV energization, the PCV-capacitor connection switching element 52 is turned on, the charging switching element 71 is turned off, and the discharge switching element 73 is turned on. Then, PCV
In addition to the connection of the paths between the electromagnetic coil 19 and the main injection capacitor 53 and the pilot injection capacitor 54, the auxiliary capacitor 72 and the main injection capacitor 5
3 and the path to the pilot injection capacitor 54 are also connected. Here, the flyback energy generated when the PCV energizing current to the electromagnetic coil 19 of the PCV 15 is cut off at this time is the injectors 29, 30, 3
Since the pilot injection and the main injection to the three-way solenoid valves 33, 34, 35, 36 of 1, 32 have been completed, P
Through the CV-capacitor connection switching element 52, the diode and the main injection capacitor 53 and the pilot injection capacitor 54 are efficiently collected. At the same time, the flyback energy recovered by the auxiliary capacitor 72 in step S208 is also recovered by the main injection capacitor 53 and the pilot injection capacitor 54 via the discharge switching element 73 and the diode.

As described above, the fuel injection control device for an internal combustion engine according to the present embodiment is driven by the diesel engine 3 and sucks and feeds fuel by the reciprocating motion of the plunger 9. Common rail 25 for storing high-pressure fuel, injectors 29, 30, 31, 32 mounted on each cylinder of the diesel engine 3 and supplied with high-pressure fuel in the common rail 25, and a PCV ( Discharge rate control valve) 15
To close the PCV 15 by energizing the electromagnetic coil 19 of the EC
Microcomputer 42 and drive circuit 43 in U41
The amount of fuel discharged from the supply pump 1 to the common rail 25 is controlled in accordance with the closing of the PCV 15 by the coil energizing means during the fuel pumping stroke of the supply pump 1 by the coil energizing means achieved by the MOS transistor 51 and the like. And a ECU for intermittently interrupting at least twice the energization of the electromagnetic coil 19 by the coil energizing means during a fuel pumping process by the supply pump 1. The microcomputer 42 and the drive circuit 43 in the ECU 41 accumulate the flyback energy generated when the current supply to the electromagnetic coil 19 is cut off for the first time by the microcomputer 42. Switching element 71, auxiliary capacitor A first energy storage means to be achieved by support 72 such as an electromagnetic coil 1 by the energizing interrupting means
The flyback energy generated at the time of the second energization cutoff for the fuel cell 9 and the flyback energy accumulated by the first energy accumulating means are used as injectors 29, 30, 3
Achieved by the microcomputer 42 in the ECU 41 and the PCV-capacitor connection switching element 52, the discharge switching element 73, the main injection capacitor 53, the pilot injection capacitor 54, and the like of the drive circuit 43, which are stored as the drive sources of the drive circuits 1 and 32. And the injectors 29, 30, 3 using the flyback energy stored by the second energy storage means at a fuel injection timing corresponding to the operating state of the diesel engine 3.
The microcomputer 42 in the ECU 41 that drives the three-way solenoid valves 33, 34, 35, and 36 to supply a predetermined amount of fuel injection to each cylinder of the diesel engine 3 and the main injection voltage disconnection switching of the drive circuit 43. Element 5
5. Switching element 56 for separating pilot injection voltage
And the like.

Accordingly, the microcomputer 42 in the ECU 41 for achieving the fuel discharge amount control means drives the drive circuit 43 for achieving the coil energizing means from the supply pump 1.
PCV controlled to close by MOS transistor 51 etc.
The high-pressure fuel stored in the common rail 25 via the fuel injector 15 is opened and closed by the three-way solenoid valves 33, 34, 35, and 36 in the microcomputer 42 and the drive circuit 43 in the ECU 41 that achieves injector drive means. The fuel is supplied to each cylinder of the diesel engine 3 from 29, 30, 31, and 32. Here, the flyback energy generated when the first energization of the electromagnetic coil 19 of the PCV 15 is interrupted is in the middle of the fuel pumping stroke period and coincides with the drive timing of the injectors 29, 30, 31, 32 when the fuel injection amount is increased. EC that achieves the power cutoff means and the first energy storage means
Microcomputer 42 and drive circuit 43 in U41
And stored by the charging switching element 71, the auxiliary capacitor 72, and the like. The flyback energy generated when the power supply to the electromagnetic coil 19 of the PCV 15 is cut off for the second time is at the end of the fuel pressure supply stroke period of the PCV 15 in which the injectors 29, 30, 31, and 32 finish driving. Injectors 29, 30, 31, 32
A microcomputer 42 in the ECU 41 and a PCV-capacitor connection switching element 52, a discharging switching element 73, and a main injection capacitor of the ECU 41 and the drive circuit 43 that achieve the power supply cutoff means and the second energy storage means so as to serve as a drive source for the 53, and stored by a pilot injection capacitor 54 and the like.

That is, the PCV 15 is energized to the electromagnetic coil 19 at the beginning of the fuel pressure feeding stroke period, and once closed, the energized state is maintained even if the energization is not continued. This first flyback energy is charged so as not to affect the driving of the injectors 29, 30, 31, 32. Then, at the end of the fuel pumping stroke period, the PCV supply current to the electromagnetic coil 19 of the PCV 15 is re-energized so as to become a saturation current, and is cut off at the end of the fuel pumping stroke period. The second flyback energy is generated by the injectors 29, 30, 31, 32
Injector 2 has completed the fuel injection by the
It is stored together with the first flyback energy so as to be the next drive source for 9, 30, 31, 32. As a result, it is not necessary to maintain the power supply to the electromagnetic coil 19 of the PCV 15 throughout the fuel pumping stroke.
Of the electromagnetic coil 19 (power consumption) is reduced. In addition, the flyback energy generated in the electromagnetic coil 19 of the PCV 15 is efficiently recovered each time, so that the durability of the PCV 15 itself against heat (temperature) is greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a four-cylinder diesel engine to which a fuel injection control device for an internal combustion engine according to an embodiment of the present invention is applied.

FIG. 2 is a sectional view showing a detailed configuration of the supply pump of FIG.

FIG. 3 is an ECU used in a fuel injection control device for an internal combustion engine according to one embodiment of the present invention.
FIG. 3 is a circuit diagram showing an electrical configuration of the embodiment.

FIG. 4 is a timing chart showing a transition state of each signal in fuel injection control for a diesel engine by a fuel injection control device for an internal combustion engine according to one example of an embodiment of the present invention.

FIG. 5 is an ECU used in a fuel injection control device for an internal combustion engine according to one embodiment of the embodiment of the present invention;
4 is a flowchart showing a main processing procedure of fuel injection control in a microcomputer in the apparatus.

FIG. 6 is an ECU used in a fuel injection control device for an internal combustion engine according to an embodiment of the present invention.
NE of Fuel Injection Control in the Microcomputer in the House
It is a flowchart which shows an interruption processing procedure.

[Explanation of symbols]

Reference Signs List 1 supply pump 3 diesel engine (internal combustion engine) 9 plunger 15 PCV (discharge amount control valve) 19 electromagnetic coil 25 common rail 29, 30, 31, 32 injector (fuel injection valve) 33, 34, 35, 36 three-way solenoid valve 41 ECU (Electronic control unit) 42 Microcomputer 43 Drive circuit 51 MOS transistor (PCV drive switching element) 52 PCV-capacitor connection switching element 53 Main injection capacitor 54 Pilot injection capacitor 55 Switching element for separating main injection voltage 56 Pilot injection Switching element for voltage disconnection 57, 58, 59, 60 MOS transistor (switching element for driving injector) 71 Switching element for charging 72 Auxiliary capacitor 73 Switch for discharging Ring element

Continued on the front page (72) Inventor Kazutoshi Nishimura 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Denso Co., Ltd. (72) Inventor Mikio Kumano 1-1-1, Showa-cho, Kariya-shi, Aichi pref.

Claims (1)

[Claims] 1. A supply pump driven by an internal combustion engine to suck and pressure fuel by reciprocating a plunger, a common rail for storing high-pressure fuel pressure-fed from the supply pump, and mounted on each cylinder of the internal combustion engine. An injector to which high-pressure fuel in the common rail is supplied; coil energizing means for energizing an electromagnetic coil of a discharge amount control valve disposed in the supply pump to close the discharge amount control valve; Fuel discharge amount control means for controlling the amount of fuel discharged from the supply pump to the common rail in accordance with the closing of the discharge amount control valve by the coil energizing means during the fuel pumping stroke of fuel, An energization interruption intermittently interrupting the energization of the electromagnetic coil by the coil energizing means twice during the pumping stroke period. Means, first energy storage means for accumulating flyback energy generated at the time of the first energization interruption to the electromagnetic coil by the energization interruption means, and occurrence at the second energization interruption to the electromagnetic coil by the energization interruption means A second energy storage means for storing the flyback energy to be stored and the flyback energy stored by the first energy storage means as a driving source of the injector; and a fuel injection timing corresponding to an operation state of the internal combustion engine. Injector driving means for driving the injector with the flyback energy accumulated by the second energy accumulating means and supplying a predetermined fuel injection amount to each cylinder of the internal combustion engine. Fuel injection control device.