JP2001164977A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control device for an engine to perform fuel injection from an injector, whereby it is practicable to minimize the influence of a drop of source voltage associated with fuel injection upon the drive of an auxiliary unit. SOLUTION: Duty signal to drive the actuator for an auxiliary unit has a period Ta consisting of the On-duty T1 and Off-duty T2, and if Ta becomes identical to the fuel injection period Ti as shown in (A), a drop of source voltage associated with fuel injection is overlapped on all On-duty T1 to cause the duty ratio to drop, and it is not possible to drive the auxiliary unit properly. Therefore, the probability of such drop of source voltage overlapping the On- duty T1 is decreased by dislocating the period Ta' of duty signal with respect to the fuel injection period Ti as shown in (B), and it is possible to suppress the drop of the duty ratio to the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for driving an injector for injecting fuel into a combustion chamber of an engine and an actuator for driving an auxiliary device of an intake and exhaust system of the engine with a common power supply. .

[0002]

2. Description of the Related Art As a fuel supply device for a diesel engine, a fuel supply device using a common rail type injector is known. In this fuel tank, fuel in a fuel tank is accumulated on a common rail by a high-pressure pump, and the fuel in the common rail is injected at a high pressure into a combustion chamber of an engine via an electromagnetic injector.

[0003] Such a common rail type injector,
Japanese Patent Application Laid-Open No. H11-153056 discloses a diesel engine provided with a supercharger for supercharging intake air and an exhaust gas recirculation device for recirculating a part of exhaust gas to an intake system.

[0004]

However, if the power source for driving the injector and the power source for driving the auxiliary devices such as the supercharger and the exhaust gas recirculation device are shared, the following problems occur. That is, since the injector is driven at a high voltage, a load may be applied to the power supply and the power supply voltage may decrease in the same cycle as the fuel injection cycle. Therefore, when the fuel injection cycle matches the cycle of the duty signal for driving the auxiliary machine, the period during which the power supply voltage is reduced overlaps with the entire on-duty period of the duty signal, and the duty ratio substantially decreases. There was a possibility that it would affect the driving of auxiliary equipment.

The present invention has been made in view of the above circumstances, and has as its object to minimize the influence of a decrease in power supply voltage due to fuel injection from an injector on the driving of auxiliary machines.

[0006]

According to the first aspect of the present invention, there is provided an injector for injecting fuel into a combustion chamber of an engine and an auxiliary device for an intake and exhaust system of the engine. An engine control device comprising: an actuator to be driven; injector driving means for driving the injector at a high voltage; actuator driving means for driving the actuator by pulse width control; and a common power supply for supplying power to the injector and the actuator. In addition, there is proposed an engine control device, wherein the actuator driving means makes a cycle of a pulse signal for driving the actuator different from a driving cycle of the injector by the injector driving means.

According to the above configuration, when the injector is driven at a high voltage, even if the power supply voltage drops in the same cycle as the injector drive cycle, the cycle of the pulse signal for driving the actuator is equal to the drive cycle of the injector. Because of the difference, it is avoided that the decrease in the power supply voltage affects all on-duties of the pulse signal. As a result, it is possible to minimize the decrease in the duty ratio due to the decrease in the power supply voltage, and to accurately drive the auxiliary equipment of the intake and exhaust system of the engine.

According to the invention described in claim 2,
In addition to the configuration of claim 1, the actuator driving unit sets N as a natural number of 2 or more, and sets the cycle of the pulse signal to a cycle N times the drive cycle of the injector or 1 cycle.
There is proposed an engine control device characterized in that the period is different from / N times the period.

According to the above configuration, when N is a natural number of 2 or more, the period of the pulse signal is different from the period N times or 1 / N times the driving period of the injector. The influence on the on-duty of the signal can be further reduced, and the decrease in the duty ratio due to the decrease in the power supply voltage can be more effectively suppressed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 6 show an embodiment of the present invention. FIG. 1 is a diagram showing a configuration of a fuel injection system of a diesel engine, FIG. 2 is a diagram showing an injector drive circuit, and FIG. A diagram showing the relationship between the cycle and the cycle of the duty signal,
FIG. 4 is a diagram showing the relationship between the engine speed and the cycle (when the cycle of the duty signal is a constant value), and FIG. 5 is a diagram showing the relationship between the engine speed and the cycle (when the cycle of the duty signal is a variable value). FIG. 6 is a diagram showing a relationship between a half cycle of the fuel injection cycle and a cycle of the duty signal.

As shown in FIG. 1, the four-cylinder diesel engine E includes four injectors 11 for injecting fuel into four combustion chambers. The fuel in the fuel tank 12 is supplied to the high-pressure pump 14 by the low-pressure pump 13, and the fuel pressurized by the high-pressure pump 14 is supplied to the common rail 15 to accumulate the pressure. The common rail 15 and the four injectors 11 are connected via four fuel supply pipes 16.

An electronic control unit U for controlling the operation of the electromagnetic valves 11a of the injectors 11, the operation of the high-pressure pump 14, and the operation of the actuator 18 for driving the auxiliary equipment 17 of the intake and exhaust system of the engine E includes: Common rail pressure Pc
r, a common rail pressure detecting means Sa for detecting r, an accelerator opening detecting means Sb for detecting an accelerator opening θap,
An engine speed detecting means Sc for detecting the engine speed Ne is connected. The auxiliary device 17 of the intake and exhaust system is, for example, E
GR valves, valuable geometry turbines, swirl control valves, and the like. A common power supply 19 is used for the injectors 11 and the actuators 18 of the auxiliary machines 17.
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Thus, the electronic control unit U includes the engine E
, The target pressure is calculated based on the accelerator opening θap detected by the accelerator opening detecting means Sb and the engine speed Ne detected by the engine speed detecting means Sc, and detected by the common rail pressure detecting means Sa. The operation of the high-pressure pump 14 is feedback-controlled so that the common rail pressure Pcr matches the target pressure.

The electronic control unit U includes an injector driving means M1 and an auxiliary equipment driving means M2. The injector driving means M1 calculates a target fuel injection amount based on the operating state of the engine E, and outputs the target fuel injection amount. Based on the amount, the solenoid valves 11a of the injectors 11 are energized at a predetermined timing for a predetermined time to perform fuel injection. In the four-cycle, four-cylinder engine E of the present embodiment, each injector 11 performs one fuel injection for every two rotations of the crankshaft. Therefore, the number of fuel injections in the four injectors 11 is quadrupled, and the engine E As a whole, two fuel injections are performed per rotation of the crankshaft. The accessory driving means M2 is provided with the actuator 1 of the accessory 17.
8 is PWM-controlled, and the cycle of the duty signal is changed to compensate for the effect of the voltage drop of the power supply 19.

Next, a drive circuit of the solenoid valve 11a of the injector 11 provided in the electronic control unit U will be described with reference to FIG.

The injector driving circuit provided in the injector driving means M 1 has a charging coil 22 and a first transistor 23 connected in series between a power supply 19 and a grounding section 21, and a constant voltage between the power supply 19 and the grounding section 24. A current circuit 25, a first diode 26, an injector solenoid 27, and a second transistor 28 are connected in series. Further, the downstream side of the charging coil 22 and the upstream side of the injector solenoid 27 are connected to the second diode 29 and the third diode 29.
A diode 30 is connected between the two diodes 29, 30 and a grounding portion 31 is connected via a capacitor 32.

The first transistor 23 has a collector terminal connected to the charging coil 22 and an emitter terminal connected to the ground 21.
And the voltage of the base terminal is controlled by the electronic control unit U. The second transistor 28 has a collector terminal connected to the injector solenoid 27, an emitter terminal connected to the ground 24, and a voltage at the base terminal controlled by the electronic control unit U. An on / off signal is input to the base terminal of the first transistor 23 so that the voltage charged in the capacitor 32 becomes constant.
The injector 11 is connected to the base terminal of the transistor 28.
Is input.

When the first transistor 23 is turned on, current flows from the power source 19 through the charging coil 22 to the arrow a.
When the first transistor 23 is turned off, a current flows in the direction of the arrow b due to the inductance of the charging coil 22 to charge the capacitor 32. When the second transistor 28 is turned on in a state where the capacitor 32 is charged in this way and the fuel injection is ready, the capacitor 32 is instantaneously discharged, and the exciting current in the direction of arrow c flows through the injector solenoid 27. At the same time, a constant current in the direction of arrow d flows from the constant current circuit 25 to the injector solenoid 27, so that the solenoid valve 11a of the injector 11 opens and the fuel stored in the common rail 15 is injected into the combustion chamber.

When the first transistor 23 is turned on to charge the discharged capacitor 32, the power supply 19
Since a large current flows through the charging coil 22 from the
Voltage temporarily drops. At this time, as shown in FIG. 1, a line L1 for supplying power to the injector driving means M1 of the electronic control unit U and a line L2 for supplying power to the accessory driving means M2 of the electronic control unit U are connected to a common power supply 19. Therefore, the voltage applied to the actuator 18 is temporarily reduced in synchronization with the turning on of the first transistor 23. This voltage drop is caused by the injectors 11.
Since the fuel injection occurs once each time the fuel injection is performed, the fuel injection occurs twice per rotation of the crankshaft in the engine E of this embodiment.

The actuator 18 of the accessory 17 is subjected to PWM control by the accessory drive means M2, and FIG. 3 shows a waveform of a duty signal for driving the actuator 18. As is apparent from FIG. 3, the duty signal is obtained by alternately arranging the on-duty T1 and the off-duty T2, and the cycle thereof is Ta (= T1 + T2). As shown in FIG. 3A, when the cycle Ta of the duty signal matches the fuel injection cycle Ti of the injectors 11 (that is, the charging cycle of the capacitor 32), the fuel injection cycle Ti
In some cases, the voltage drop of the power supply 19 occurring in the same cycle as that of the power supply 19 overlaps with the period of all the on-duties T1 of the duty signal. In such a case, the duty ratio is substantially reduced, and it is not possible to drive the accessory 17 accurately.

FIG. 4 shows the relationship between the fuel injection cycle Ti and the duty signal cycle Ta with respect to the engine speed Ne. Since the number of times of fuel injection and the fuel injection cycle Ti are inversely proportional, the relationship between the engine speed Ne and the fuel injection cycle Ti is also inversely proportional, and the fuel injection cycle Ti decreases as the engine speed Ne increases. . This is the fuel injection period Ti1 when the engine speed Ne is Ne1, and when the period Ta of the duty signal for driving the actuator 18 of the accessory 17 matches this fuel injection period Ti1, FIG.
The state shown in (A) occurs, and the duty ratio decreases.

Accordingly, the fuel injection cycle Ti is calculated in accordance with each engine speed Ne, and the cycle Ta of the duty signal is changed so as not to coincide with the fuel injection cycle Ti. Can prevent the occurrence of the worst case shown in FIG.

FIG. 3 (B) shows the duty signal periods Ta to T at the same engine speed Ne as in FIG. 3 (A).
The case where the length is shortened to a 'is shown. In this case, FIG.
And the duty ratio T1 '/ Ta' in FIG. 3B is set to be the same. As is apparent from a comparison between the two, in the case of FIG. 3A, the voltage drop of the power supply 19 overlaps during the period of all the on-duty T1, whereas in the case of FIG. The voltage drop of the power supply 19 overlaps only during the on-duty T1 'of the unit. From the above, it can be seen that by shifting the cycle Ta of the duty signal in the increasing or decreasing direction with respect to the fuel injection cycle Ti, it is possible to reduce the decrease in the duty ratio due to the decrease in the voltage of the power supply 19.

FIG. 5 shows the specific method. That is,
In FIG. 4, the cycle Ta of the duty signal is constant with respect to the change in the engine speed Ne, whereas in FIG. 5, the cycle Ta 'of the duty signal is variable. Then, at the engine speed Ne1 where the fuel injection cycle Ti1 and the cycle Ta 'of the duty signal match,
The cycle Ta 'of the duty signal is changed discontinuously. As a result, even if the engine speed Ne increases or decreases near Ne1, the duty signal cycle Ta 'is smaller or larger than the fuel injection cycle Ti1.
2 and the duty cycle T
It is possible to prevent the state of FIG. 3A in which a coincides with the fuel injection period Ti1 from continuing.

Thus, the influence of the voltage drop of the power supply 19 due to the fuel injection on the driving of the auxiliary equipment 17 in the intake / exhaust system is minimized, and the auxiliary equipment 19 is accurately driven to reduce the output of the engine E, Generation of smoke, deterioration of emission, and the like can be prevented.

The case where the cycle Ta of the duty signal coincides with the fuel injection cycle Ti has been described so far.
When the cycle Ta of the duty signal coincides with the cycle of 、, １ ／ times, that is, when N is a natural number of 2 or more, the cycle T of the duty signal is 1 / N times the cycle of the fuel injection Ti.
The above problem also occurs when a coincides.

FIG. 6 (A) shows 1/1 of the fuel injection period Ti.
The case where the double cycle 1/2 × Ti coincides with the cycle Ta of the duty signal is shown. Also in this case, every time a voltage drop of the power supply 19 occurs due to the fuel injection, the voltage drop may always affect the on-duty T1 of the duty signal. On the other hand, as shown in FIG. 6B, by shifting the cycle Ta of the duty signal with respect to the cycle 1/2 × Ti which is １ ／ times the fuel injection cycle Ti, the voltage drop causes the duty signal to turn on. The influence on the duty T1 can be reduced, and the decrease in the duty ratio can be minimized.

As described above, in FIG.
The cycle of 1/2 × Ti is the cycle Ta of the duty signal.
Has been described (when N = 2),
Similar effects can be obtained when N = 3 or more.
When the cycle of twice, three times, four times,... Of the fuel injection cycle Ti matches the cycle Ta of the duty signal, that is, N is set to 2
Even when the cycle Ta of the duty signal coincides with the cycle N times the fuel injection cycle Ti as a natural number as described above, the same effect is achieved by shifting the cycle Ta of the duty signal with respect to the cycle N times. can do.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the diesel engine E
However, the present invention can also be applied to a fuel direct injection type gasoline engine.

[0032]

As described above, according to the present invention, when the injector is driven at a high voltage, the cycle of the pulse signal for driving the actuator is reduced even if the power supply voltage is reduced in the same cycle as the injector drive cycle. Since it is different from the driving cycle of the injector, it is possible to prevent the decrease in the power supply voltage from affecting the on-duty of all the pulse signals. As a result, it is possible to minimize the decrease in the duty ratio due to the decrease in the power supply voltage, and to accurately drive the auxiliary equipment of the intake and exhaust system of the engine.

According to the second aspect of the present invention,
When N is a natural number of 2 or more, the cycle of the pulse signal is different from the cycle of N times or 1 / N times the drive cycle of the injector. Therefore, it is possible to more effectively suppress the decrease in the duty ratio due to the decrease in the power supply voltage.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a fuel injection system of a diesel engine.

FIG. 2 is a diagram showing an injector drive circuit;

FIG. 3 is a diagram showing a relationship between a fuel injection cycle and a cycle of a duty signal.

FIG. 4 is a diagram showing a relationship between an engine speed and a cycle (when the cycle of a duty signal is a constant value);

FIG. 5 is a diagram showing the relationship between the engine speed and the cycle (when the cycle of the duty signal is a variable value);

FIG. 6 is a diagram showing a relationship between a half cycle of a fuel injection cycle and a cycle of a duty signal.

[Explanation of symbols]

 Reference Signs List 11 injector 17 intake and exhaust system auxiliary equipment 18 actuator 19 power supply E engine M1 injector driving means M2 actuator driving means Ta pulse signal cycle Ti injector drive cycle

Continuation of the front page (72) Inventor Hiroshi Kobayashi 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (reference) 3G066 AA02 AA07 BA23 BA24 BA28 CB12 CC05U CD26 CE22 CE29 DA00 DC00 DC04 DC05 DC09 DC18 3G301 HA02 HA04 JA21 JA24 JB02 JB09 LB04 LB11 LC01 LC10 ND41 PB00Z PB08Z PE01Z PE03Z PF03Z PG01B PG01Z

Claims (2)

[Claims] An injector (11) for injecting fuel into a combustion chamber of an engine (E), an actuator (18) for driving an auxiliary device (17) of an intake / exhaust system of the engine (E), and an injector (11). Drive means (M1) for driving the actuator at a high voltage, actuator drive means (M2) for driving the actuator (18) by pulse width control, and a common power supply (19) for supplying power to the injector (11) and the actuator (18). ), Wherein the actuator driving means (M2) determines the cycle (Ta) of the pulse signal for driving the actuator (18) by the injector driving means (M1).
And a driving cycle (Ti) of the engine. 2. The actuator driving means (M2)
Sets the cycle (Ta) of the pulse signal to a drive cycle (T) of the injector (11), where N is a natural number of 2 or more.
The engine control device according to claim 1, wherein the period is different from the period of N times or 1 / N times of i).