JPH0319898B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection amount control method for a diesel engine, and in particular, a method for controlling a fuel injection amount for a diesel engine suitable for controlling the fuel injection amount when the engine is in a high rotation range. Regarding.

Basic fuel injection amount in diesel engine
Q _BASE is uniquely determined by the engine speed and accelerator opening as shown in the map in Figure 1. In addition, the basic fuel injection amount Q _BASE regarding the engine rotation speed when the accelerator opening is constant is the second
As shown in the figure, there is a characteristic that the smaller the accelerator opening, the more rapid the change in the injection amount with respect to the change in engine speed.

Further, the maximum fuel injection amount Q _FULL is determined by the engine rotation speed and intake pressure. Specifically, the injection amount when the intake pressure Pm is 760mmHgabs.
Q′ _FULL (shown in Figure 3) and the intake pressure compensation coefficient K2 (fourth
(shown in the figure).

Incidentally, the maximum fuel injection amount Q _FULL of a diesel engine changes depending on the engine rotation speed, as long as the chamber temperature and exhaust temperature are within limits even when the engine is in a high rotation range. Moreover, when the diesel engine is operated with the maximum fuel injection amount Q _FULL ,
Engine water temperature is 80~100℃, engine oil temperature is 100~
A temperature in the range of 130°C is the optimum operating condition for a diesel engine.

However, conventionally, control has been performed in which the maximum fuel injection amount remains the same even when the engine water temperature becomes high. Therefore, there was a problem that the engine overheated due to the rise in engine oil temperature. In addition, there has been a problem in that the glow plug and the chamber are damaged due to an increase in the temperature of the chamber.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a fuel for a diesel engine that can prevent damage to the engine even when fuel is injected at the maximum fuel injection amount when the engine is at high temperature. An object of the present invention is to provide an injection amount control method.

In order to achieve the above object, the present invention calculates a basic fuel injection amount based on an accelerator opening degree and an engine rotation speed, and calculates a maximum fuel injection amount based on the engine rotation speed and intake pressure. In a diesel engine fuel injection amount control method in which fuel is injected into the diesel engine using the smaller of the calculated fuel injection amount values according to the operating state of the engine, the engine water temperature of the diesel engine is detected. , when the detected engine water temperature exceeds a high temperature set value, a correction calculation is performed to reduce one of the calculated fuel injection amounts by a predetermined value according to the engine water temperature, and based on the corrected fuel injection amount, The present invention is characterized in that the amount of fuel to be injected is selected and the amount of fuel injection is suppressed by the maximum amount of fuel injection.

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

FIG. 5 shows a configuration diagram of a fuel injection pump and a control device suitable for applying the present invention.

The fuel injection pump 1 is composed of a drive control section and a sensor section. The drive control unit includes a drive shaft 1 driven by a diesel engine 10.
1. A gear 12 and a roller 13 provided at the end of the drive shaft 11, a cam plate 14 loosely fitted to the roller 13, and a spill port 50 inside and connected to the cam plate 14 to form a diesel engine. a pump plunger 15 for delivering fuel to the injection nozzles 2 of 10;
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, a linear solenoid 22 that drives a spill ring 21, a coil 23 that constitutes the linear solenoid 22, and the spill ring 21. , a spill ring 21 that is driven by a linear solenoid 21 to adjust the injection amount, and a fuel cut valve (FCV) that controls the supply of fuel to the pump plunger 15.
) 26 (excitation coil 27 and valve 28
), a delivery valve 5 for preventing backflow and dripping of fuel from the pump plunger 15
6 and a regulating valve 29.

The sensor section includes a timer position sensor 18 that electrically detects the position of the timer piston 16, and an electromagnetic pickup sensor 2 that serves as a rotation speed detector that outputs a pulse signal according to the rotation speed of the gear 12.
0, and a spill position sensor 25 that detects the amount of movement of the plunger 20.

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 flange 15. The amount of fuel injected is determined by the position of the spill link. Also, excess fuel in the pump is removed from orifice 3.
0 to the pump 13 side. Also, the linear solenoid 22 and FCY26 in the fuel pump 1
The control is performed by the control device 3, and for this purpose, output signals from various sensors are taken in.
That is, the engine rotational speed signal S _N from the electromagnetic pickup sensor 20 and the output signal S _S from the spill position sensor 25 are taken into the control device 3 .

The control device 3 also receives a detection signal Sa from an intake temperature sensor 5 provided in the intake manifold 4, a detection signal Sp from an intake pressure sensor 6 also provided in the intake manifold 4, and a detection signal Sp from a water temperature sensor that detects engine cooling water temperature. signal Sw, detection signal Sacc of accelerator sensor 9 that detects the amount of depression of accelerator 8;
An ignition signal Ig, which is a signal corresponding to the on/off state of the ignition switch 40, and a starter signal St, which is a signal corresponding to the on/off state of the starter switch 42, are supplied, respectively. The control device 3 can take in detection signals etc. from various sensor groups and control the driving of the fuel injection pump and the diesel engine 10 based on these signals.

FIG. 6 shows a configuration diagram in which the control device of FIG. 5 is configured with a microcomputer.

The control device 3 shown in FIG. 6 has a CPU 61 as its core, and a ROM 6 in which processing programs and monitor programs are stored for executing various processes.
2. Temporarily stores the calculation contents and the output contents of various sensors, and also stores the calculation contents when the power is cut off.
It consists of a RAM 63 with a backup memory that continues to store set values, basic fuel injection amount, etc., input/output ports 64, 65, an A/D converter 66, a multiplexer 67, drive circuits 69, 70, etc. Output ports 64, 65, CPU61,
The RPM 62 and RAM 63 are connected by a bus line 71, respectively. The detection signals of the water temperature sensor 7, intake temperature sensor 5, intake pressure sensor 6, and accelerator sensor 9 are sent to buffer circuits 72, 73, 74, 75.
is supplied to multiplexer 67 via. Further, detection signals from the spill position sensor 25 and the timer position sensor 18 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 sent to the input/output port 64.
is supplied as data. Also, starter signal St,
The ignition signal Ig is supplied to the buffer circuit 78,
79 to the input/output port 65. Further, the detection signal of the electromagnetic pickup sensor 20 is supplied to the CPU 61 via a waveform shaping circuit 80.

The CPU 61 performs various calculations based on signals from the various sensors and outputs drive signals for driving the fuel pump and the like.

That is, when controlling the drive of the FCV 26, a drive signal is supplied to the drive circuit 69. In addition, when driving the linear solenoid 22, the D/A converter 8
4. Supply a drive signal to the drive circuit 70 via the servo amplifier 86. A clock circuit 90 is provided for sending clock pulses to the CPU 61, input/output ports 64, 65, A/D converter 66, and D/A converter 84.

Next, the operation according to the present invention will be explained based on the flow chart shown in FIG.

First, in step 101, the engine rotational speed N is determined based on the detection signal of the electromagnetic pickup sensor 20.
Based on the accelerator opening degree detected by the accelerator sensor 9, the basic fuel injection amount _QBASE is calculated based on the map shown in FIG.
In step 102, the maximum fuel injection amount Q is determined based on the intake pressure Pm detected by the intake pressure sensor 6 and the engine rotational speed N detected by the electromagnetic pickup sensor 20, based on the characteristic diagrams shown in FIGS. 3 and 4. Calculate _FULL and proceed to step 103. In step 103, the engine water temperature THW detected by the water temperature sensor 7 and the set temperature, for example 95
℃, and if the detected engine water temperature THW exceeds the set temperature, the maximum fuel injection amount Q _FULL calculated in step 102 is corrected to be reduced by a predetermined value. Also, the correction amount is (THW−
95)/20 is used, but in this embodiment, the engine rotational speed is further integrated as a correction amount, that is, this correction amount is expressed by the following equation.

(THW-95)/20×(N-3200)/800...(1) The correction amount according to equation (1) above is reduced from the maximum fuel injection amount Q _FULL calculated in step 103, and this value is set as the new maximum. The fuel injection amount Q is set to _FULL and the process moves to step 104.

In step 104, it is determined whether the basic fuel injection amount Q _BASE calculated in step 101 is larger or smaller than the maximum fuel injection amount Q _FULL calculated in step 103. In step 104, Q _BASE >
If Q _FULL , move to step 105 and step 103
The maximum fuel injection amount Q _FULL calculated in is set as the final fuel injection amount Q _FIN and the process moves to step 107. on the other hand,
If Q _BASE <Q _FULL in step 104, the process moves to step 106, where the basic fuel injection amount Q _BASE calculated in step 101 is set as the final fuel injection amount Q _FIN , and the process moves to step 107. In step 107, a spill command voltage V _SPP is calculated based on the final fuel injection amount Q _FIN and the engine speed. The spill command voltage V _SPP in this case is calculated based on the map shown in FIG. Next, the process moves to step 108, where the spill command voltage V _SPP is output to the D/A converter 84 to drive the linear solenoid 22.

FIG. 9 shows a characteristic diagram when the maximum fuel injection amount is suppressed by the process shown in FIG. 7 when the engine water temperature THW=115° C.

In this way, in this embodiment, the maximum fuel injection amount can be suppressed when the engine temperature becomes high, so even if fuel is injected at the maximum fuel injection amount when the engine temperature is high, the engine will not be damaged. can be prevented.

Further, in the above embodiment, when correcting the maximum fuel injection amount, the engine rotation speed was used as a parameter for the correction amount, but the same effect as in the above embodiment can be obtained even if only the engine water temperature is used as the correction amount. . Further, in the embodiment described above, the correction that reduces only the maximum fuel injection amount has been described, but even if the correction is performed to reduce the basic fuel injection amount, the same effect as in the embodiment described above can be obtained.

As explained above, according to the present invention, there is an excellent effect that damage to the engine can be prevented even if fuel is injected at the maximum fuel injection amount when the engine is at high temperature.

[Brief explanation of the drawing]

Figure 1 is a fuel injection amount characteristic diagram based on engine rotation speed and accelerator opening degree, Figure 2 is a fuel injection quantity characteristic diagram when the accelerator opening degree is constant, and Figure 3 is a fuel injection quantity characteristic diagram when the intake pressure is determined. Figure 4 is a diagram showing the relationship between intake pressure correction coefficient and intake pressure, Figure 5 is a configuration diagram of a fuel injection pump and control device to which the present invention is applied, and Figure 6 is shown in Figure 5. An internal configuration diagram of the control device, FIG. 7 is a flowchart for explaining the operation of the present invention, FIG. 8 is a characteristic diagram of the control output value based on the fuel injection amount and engine rotation speed, and FIG. FIG. 3 is a diagram showing the relationship between the maximum fuel injection amount and engine rotation speed for explaining the effect based on the processing of FIG. DESCRIPTION OF SYMBOLS 1... Fuel injection pump, 2... Injection nozzle, 3... Control device, 6... Intake pressure sensor, 7... Water temperature 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 rotation speed, calculate the maximum fuel injection amount based on the engine rotation speed and intake pressure, and calculate the calculated amount according to the operating state of the diesel engine. In a diesel engine fuel injection amount control method in which fuel is injected into the diesel engine using the smaller of the fuel injection amount values, the engine water temperature of the diesel engine is detected, and the detected engine water temperature is set to a high temperature setting value. When the fuel injection amount is exceeded, a correction calculation is performed to reduce one of the calculated fuel injection amounts by a predetermined value according to the engine water temperature, and the fuel amount to be injected is selected based on the corrected fuel injection amount, and the maximum amount of fuel is selected. A method for controlling a fuel injection amount of a diesel engine, the method comprising suppressing the fuel injection amount by a fuel injection amount.