JPH0361019B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection amount control method, and more particularly to a diesel engine fuel injection amount control method suitable for controlling the fuel injection amount of a diesel engine.

When controlling the fuel injection amount in a diesel engine equipped with an electronically controlled fuel injection pump, the first
As shown in the figure, the basic fuel injection amount Q _BASE is calculated based on the accelerator opening degree and engine speed, and as shown in Figure 2, when the intake pressure exceeds a predetermined pressure, for example 760 mmHg _ABS , Corrected injection amount according to pressure increase = Basic fuel injection amount
Q _BASE , and when the intake pressure is below a predetermined pressure, the corrected injection amount Q〓 corresponding to the decrease in intake pressure is subtracted from the basic fuel injection amount Q _BASE , and as shown in Figure 3, the corrected injection amount Q Conventionally, the maximum fuel injection amount Q _FULL is calculated from the basic fuel injection amount and the engine speed, and fuel is injected into the diesel engine using the calculated maximum fuel injection amount Q _FULL .

By controlling the fuel injection amount in this way, even when the air pressure decreases as when driving at high altitudes, the correction amount corresponding to the decrease in intake pressure is subtracted from the basic fuel injection amount, and the maximum fuel injection amount Q _FULL is subtracted, it is possible to prevent white smoke from being generated.

However, in the conventional electronically controlled fuel injection system, control is performed to always reduce the maximum fuel injection amount when the vehicle is traveling at high altitude. Therefore, when a vehicle equipped with a diesel engine to which the conventional method is applied drives at high altitudes, the engine's driving force decreases as the maximum fuel injection amount decreases, making it difficult to overcome protrusions on the road. I had the inconvenience of not being able to do that.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to provide a fuel injection amount control method for a diesel engine that can temporarily compensate for a decrease in engine driving force during high-altitude driving. There is a particular thing.

In order to achieve the above object, the present invention calculates the basic fuel injection amount based on the accelerator opening degree and the engine rotation speed, and when the intake pressure exceeds a predetermined pressure, adjusts the correction injection amount according to the increase in the intake pressure. When the intake pressure is below a predetermined pressure, the corrected injection amount corresponding to the decrease in intake pressure is subtracted from the basic fuel injection amount, and the maximum injection amount is calculated from either of the corrected basic fuel injection amounts and the engine rotation speed. In a diesel engine fuel injection amount control method that injects fuel into the diesel engine using the calculated maximum fuel injection amount, the time when the accelerator opening exceeds the predetermined opening when the intake pressure is below a predetermined pressure. When this continues for a predetermined period of time, the basic fuel injection amount is corrected by adding a correction injection amount determined as an increased fuel injection amount during pressure reduction to the calculated basic fuel injection amount.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings.

FIG. 4 shows the configuration of a preferred fuel injection pump and control device to which the present invention is applied.

The fuel injection pump 1 includes a drive control section and a sensor section. The drive control unit includes a drive shaft 11 driven by a diesel engine 10, a gear 12 and a roller 13 provided at the end of the drive shaft 11, a cam plate 14 loosely connected to the roller 13, and an internal Pump plunger 1 having a spill port 50 and coupled to the cam plate 14 for delivering fuel to the injection nozzle 2 of the diesel engine 10
5. A fuel pump 17 that sends fuel to the injection nozzle 2 and the timer piston 16, a timing control valve 19 that determines advance angle adjustment, and a spill ring 21.
a linear solenoid 22 that drives the linear solenoid 22, a plunger 24 that drives the coil 23 and the spill ring 21 that constitute the linear solenoid 22, a spill ring 21 that is driven by the linear solenoid 21 to adjust the fuel injection amount, and a pump plunger 15 that Fuel cut valve 2 that controls supply
6 (consisting of excitation coil 27 and valve 28),
It is comprised of a delivery valve 56 and a regulating valve 29 for preventing backflow and dripping of fuel from the pump plunger 15.

The cam plate 14 rotates and reciprocates together with the pump plunger 15. This reciprocating motion is caused by the cam plate 14 riding on the roller 13, which is rotatable but fixed in the axial direction of the shaft. The fuel is distributed by rotating the pump plunger 15. The amount of fuel injected at this time is determined by the position of the spill ring 21. Further, excess fuel in the pump is returned to the pump 13 via the orifice 30.
Further, the linear solenoid 22 and fuel cut valve 26 in the fuel pump 1 are controlled by the control device 3. Therefore, output signals from various sensors are taken into the control device 3.

The sensor section includes a timer position sensor 18 that electrically detects the position of the timer piston 16, an electromagnetic pickup sensor 20 that outputs a pulse signal according to the rotational speed of the gear 12 and constitutes a rotational speed detector, and a sensor that detects the movement of the pump plunger 15. It is composed of a position sensor 25 that detects the amount.

The engine rotational speed N _E from the electromagnetic pickup sensor 20 and the output signal S _S from the spill position sensor 25 are supplied to the control device 3 .

Further, the control device 3 is supplied with a detection signal S _P from an intake pressure sensor 6 provided in the intake manifold 4 and a detection signal A _CCP from an accelerator sensor 9 that detects the amount of depression of the accelerator 8, that is, the accelerator opening degree. ing.

The control device 3 can receive detection signals from each of the sensor groups and control the driving of the fuel injection pump 1 and the diesel engine 10 based on these signals.

FIG. 5 shows a configuration in which the control device shown in FIG. 4 is implemented by a microcomputer.

The control device 3 shown in FIG. 5 has a CPU 61 as its core, and stores processing programs and monitor programs for executing various processes.
ROM 62, RAM 63, which temporarily stores calculation contents and output contents of various sensors, etc., and continues to remember calculation contents, set values, basic fuel injection amount, etc. even when the power is cut off, input/output port 64, A/D
Converter 66, multiplexer 67, drive circuit 6
It is composed of 9, 70, etc., and has 6 input/output ports.
4. A CPU 61, a ROM 62, and a RAM 63 are each connected by a bus line 71.

This control device 3 receives detection signals from the intake pressure sensor 6 and the accelerator sensor 9 through buffer circuits 74 and 75.
is supplied to multiplexer 67 via.
Also, spill position sensor 25 and timer position sensor 18
The respective detection signals are supplied to the multiplexer 67 via sensor signal detection circuits 76 and 77. The sensor output supplied to the multiplexer 67 is converted into a digital signal by the A/D converter 66 and supplied to the input/output port 64 as data. Further, a detection signal from the electromagnetic pickup sensor 20 is supplied to the CPU 61 via a waveform shaping circuit 80.

The CPU 61 can perform various calculations based on signals from the various sensors and output drive signals for driving the fuel pump 1 and the like.

That is, when driving the linear solenoid 22, a drive signal is supplied to the drive circuit 70 via the D/A converter 84 and the servo amplifier 86. In addition,
CPU61, input/output port 64, A/D converter 6
6. A clock circuit 90 is provided for sending clock pulses to the D/A converter 84.

In addition, the RAM 63 stores data values of the basic fuel injection amount Q _BASE , the corrected injection amount Q〓, and the maximum fuel injection amount Q _FULL corresponding to the characteristic diagrams shown in FIGS. 1 to 3. The data value of the corrected injection amount Q〓 determined as the increased fuel correction amount at the time of pressure reduction as shown in FIG. 6 is stored.

The device to which the present invention is applied has the above configuration, and its operation will be explained next.

FIG. 7 shows a flowchart for explaining the operation of the apparatus shown in FIG. 4.

First, in step 100, the engine rotational speed N _E is determined by the detection signal of the electromagnetic pickup sensor and the accelerator opening degree is determined by the detection signal of the accelerator sensor 9.
The basic fuel injection amount Q _BASE is calculated based on A _CCP and the process moves to step 102. In step 102, the corrected injection amount Q shown in FIG. 2 is calculated based on the detection signal of the intake pressure sensor 6, and the process moves to step 104. In step 104, the calculated value in step 100 is
The corrected basic fuel injection amount Q is calculated by adding Q _BASE and Q〓 calculated in step 102, and the process moves to step 106.

In step 106, the detection output of the accelerator sensor 9 determines that the accelerator opening A _CCP is a predetermined opening.
A Determine whether _{the CCPO} has been exceeded. step
If the result in step 106 is YES, the process moves to step 108, where the count value of clock 90 is incremented by +1, and the process moves to step 110.

In step 110, the count value C accumulated by the clock 90 is set to a set value in order to determine whether the time when the accelerator opening A _CCP exceeds the predetermined opening A _CCPO continues for a predetermined period of time. Determine whether or not C0 has been exceeded. YES on step 110
If it is determined that this is the case, the process moves to step 114. In step 114, the corrected injection amount Q shown in FIG. 6 is calculated based on the detection signal of the intake pressure sensor 6. Immediately, the intake pressure reaches a predetermined pressure, e.g. 760 mm.
When Hg _ABS is exceeded, a value is calculated that makes the corrected injection amount Q〓 0, and when the intake pressure is below low pressure, a value of the corrected injection amount Q〓, which is determined as the increased fuel injection amount during pressure reduction, is calculated. Ru.

On the other hand, if the determination at step 106 is NO, the process moves to step 116, where the count value C is set to 0 in order to reset the clock 90. Furthermore, if it is determined NO in step 110,
The process moves to step 118, where the value of the corrected injection amount Q〓 is set to 0, and the process moves to step 120.

In step 120, the corrected injection amount Q≦ calculated in step 114 or step 118 is added to the injection amount Q calculated in step 104 to calculate the final fuel injection amount _QFIN , and the process moves to step 122. step
In step 122, the spill command voltage V _SPP is calculated based on the final fuel injection amount Q _FIN and the engine rotational speed N _E , and the process moves to step 124. In step 124, the spill command voltage V _SPP is output to the D/A converter 84 to drive the linear solenoid 22. When the linear solenoid 22 is driven, as shown in FIG. 9, the fuel injection amount corresponding to the value of the spill command voltage V _SPP , that is, the maximum fuel injection amount, is injected from the injection nozzle 2.

As described above, in this embodiment, when the intake pressure is below a predetermined pressure and the time when the accelerator opening exceeds the predetermined opening continues for a predetermined period of time, the maximum fuel injection amount is increased. This can temporarily compensate for the decrease in engine driving force.

FIG. 8 shows a flowchart for explaining the operation of another embodiment of the present invention.

In the case of this embodiment, it is determined whether the count value C counted by the clock 90 between step 110 and step 114 of the flowchart shown in FIG. 7 has become equal to or less than another set value C1. A processing step 112 is provided for carrying out the processing, and the other processing is the same as that in FIG. In addition, the set value C0
<The relationship is C1.

That is, in the case of this embodiment, only when the count value C counted as the time during which the accelerator opening exceeds the predetermined opening exceeds the set value C0 and is below the set value C1, the increase fuel correction amount at the time of pressure reduction is determined. The corrected injection amount Q〓 is added to the basic fuel injection amount. Therefore, in this example,
When the intake pressure is below a predetermined pressure, the increase in the maximum fuel injection amount, which is performed when the accelerator opening exceeds the predetermined opening for a predetermined period of time, does not continue for more than the predetermined period of time, so white smoke is generated. can be prevented.

As explained above, according to the present invention, when the intake pressure is below the predetermined pressure and the time when the accelerator opening exceeds the predetermined opening continues for a predetermined period of time, the increased fuel injection amount at the time of pressure reduction is The basic fuel injection amount is corrected by the predetermined correction injection amount and the maximum fuel injection amount is increased, which has the excellent effect of temporarily compensating for the decrease in engine driving force when driving at high altitudes. .

[Brief explanation of drawings]

Figure 1 is a basic fuel injection amount characteristic diagram based on engine rotation speed and accelerator opening, Figure 2 is a diagram showing the relationship between intake pressure and corrected injection amount, and Figure 3 is a diagram showing the relationship between engine rotation speed and maximum fuel injection amount. FIG. 4 is a diagram showing the relationship between the fuel injection pump and the control device to which the present invention is applied, FIG. 5 is an internal configuration diagram of the control device shown in FIG. 4, and FIG. A diagram showing the relationship between corrected injection amount and intake pressure, FIG. 7 is a flowchart for explaining the operation of the device shown in FIG. 4, and FIG. 8 is a diagram explaining other operations of the device shown in FIG. 4. The flowchart for this purpose, FIG. 9, is a characteristic diagram of the spill voltage command value based on the fuel injection amount and engine rotational speed. DESCRIPTION OF SYMBOLS 1... Fuel injection pump, 2... Injection nozzle, 3... Control device, 6... Intake pressure sensor, 20... Electromagnetic pickup sensor, 22...
linear solenoid.

Claims (1)

[Claims] 1 Calculate the basic fuel injection amount based on the accelerator opening degree and engine speed, and when the intake pressure exceeds a predetermined pressure, add the correction injection amount according to the increase in intake pressure to the basic fuel injection amount, and calculate the intake pressure. When the pressure is below a predetermined pressure, the corrected injection amount corresponding to the decrease in intake pressure is subtracted from the basic fuel injection amount, and the maximum fuel injection amount is calculated from one of the corrected basic fuel injection amounts and the engine rotation speed. In a diesel engine fuel injection amount control method in which fuel is injected into the diesel engine using a maximum fuel injection amount, when the intake pressure is below a predetermined pressure, the time when the accelerator opening exceeds the predetermined opening continues for a predetermined time. A fuel injection amount control method for a diesel engine, characterized in that when the fuel injection amount is increased during depressurization, the basic fuel injection amount is corrected by adding a correction injection amount determined as an increased fuel injection amount at the time of pressure reduction to the calculated basic fuel injection amount. .