JPH0245020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection amount control method for a diesel engine, and more particularly to a fuel injection amount control method for a diesel engine that performs optimal fuel injection depending on the temperature state of the diesel engine.

In the conventional fuel injection amount control method in which diesel engine fuel injection is electronically controlled,
The fuel injection amount is determined according to a fuel injection pattern as shown in FIG. 5, which will be described later. In other words, if you do not press the accelerator when starting, the accelerator opening is 0%.
It is controlled by the fuel injection amount pattern. However, the conventional injection amount pattern that is determined according to the actual accelerator opening has the drawback that when starting at a low temperature and the engine speed is low, the amount of fuel injection becomes insufficient and the startability of the engine deteriorates. On the other hand, when the engine is restarted after it has completely warmed up, the amount of fuel injected is too large, resulting in smoke. Furthermore, in the conventional injection amount pattern, the fuel injection amount decreases too quickly as the engine speed increases, which has the disadvantage of causing engine stall, especially at low temperatures.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel injection amount control method for a diesel engine that has excellent cold startability and restartability.

In order to achieve the above object, the features of the present invention are as follows:
A diesel engine that electronically controls the amount of fuel injection that is supplied to the diesel engine installed in a vehicle in a spray state via a fuel control valve using a fuel injection amount pattern that is determined using the accelerator opening and engine speed as parameters. In the engine fuel injection amount control method, the accelerator opening is set as a function of the engine water temperature so that the opening increases when the engine is cold, decreases when the engine warms up, and reaches zero at a predetermined temperature. Separately from the accelerator opening,
The fuel injection amount is controlled using the larger accelerator opening of the two accelerator openings.

Since the accelerator opening degree for control is determined as a function of the engine water temperature, the accelerator is depressed in accordance with the engine water temperature at that time. Therefore, the fuel injection amount can be continuously and finely controlled by using injection patterns corresponding to various accelerator opening degrees depending on the engine warm-up state at that time. In other words, the controlled accelerator opening amount increases fuel injection when the engine is cold and decreases the fuel injection amount when the engine is warmed up, making it easy to start the engine without pressing the accelerator even when the engine is cold. This also makes it possible to suppress the generation of smoke even when the engine is restarted after it has been warmed up.

Also, after the engine starts, the fuel injection amount is mainly controlled by the actual accelerator opening, but when the accelerator is depressed a little, the controlled accelerator opening is generally larger than the actual accelerator opening, so
At this stage, the fuel injection amount is controlled by the accelerator opening degree. Next, when the accelerator is further depressed, the actual accelerator opening becomes larger than the controlled accelerator opening, so at this stage the fuel injection amount is controlled by the actual accelerator opening. In this case, the transition from control based on the accelerator opening degree to actual control based on the accelerator opening degree is performed continuously, and the engine rotation can be smoothly increased.

When the engine is completely warmed up and exceeds a predetermined temperature, the controlled accelerator opening becomes zero, so in this state, the fuel injection amount is controlled only by the actual accelerator opening.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel injection amount control method for a diesel engine according to the present invention will be described below with reference to the drawings.

FIG. 1 shows a fuel injection pump and a control device suitable for applying the present invention.

The fuel injection pump 1 includes a drive shaft 11 driven by an engine, a gear 12 and a roller 13 provided at the end of the drive shaft,
A cam plate 1 loosely connected to the roller 13
4. Pump plunger 15 coupled to the plate 14 for delivering fuel to the injection nozzle 2 of the engine, fuel pump 17 for delivering fuel to the injection nozzle 2 and timer piston 16, and timer piston 16; Fuel leakage from the timer position sensor 18 that electrically detects, the timing control valve 19 that determines the advance angle adjustment, the electromagnetic pickup sensor 20 that outputs a pulse signal according to the rotational speed of the gear 12, and the spill port 50 of the pump plunger 15. A spill ring 21 that controls the amount, a linear solenoid 22 that drives the spill ring 21, a coil 23 that constitutes the linear solenoid 22, a plunger 24 that drives the spill ring 21, and a spill position that detects the amount of movement of the plunger 24. sensor 2
5. The FCV 26 (composed of an excitation coil 27 and a valve 28) controls the supply of fuel to the pump/plunger 15 and the cut, and the fuel brought to high pressure by the pump/plunger 15 is smoothly injected from the injection nozzle 2. It consists of a delivery valve 56 and a regulating valve 29 that are adjusted as follows.

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 1. Injection timing is given by rotation of the pump plunger 15. The injection amount is determined by the position of the spill ring 21 that controls the amount of fuel leaking from the spill port 50 of the pump plunger 15. Excess fuel in the pump is removed from orifice 3.
0 to the pump 17 side. In addition, the linear solenoid 22 in the fuel pump 1 and the FCV
26 is controlled by the control device 3, which receives output signals from various sensors. That is, the engine rotation speed signal S _N from the electromagnetic pickup sensor 20 and the spill position sensor 25
These are the pump side information and the engine side information of the output signal Ss.

Note that the timer position sensor 18 is used for timing control and is not related to the present invention, so a description thereof will be omitted. Engine side information includes the output signal Sa of the intake air temperature sensor 5 provided in the intake manifold 4, the output signal Sp of the intake pressure sensor 6 also provided in the intake manifold 4, the output signal Sw of the water temperature sensor 7 that measures the engine cooling water temperature, and There is an output signal _SACC of the accelerator sensor 9 that detects the amount of depression of the accelerator 8, and some of this information is also used for air-fuel ratio control.

FIG. 2 is a detailed block diagram of the control device 3 of FIG. 1.

With a central processing unit (CPU) 31 as the core, a read-only memory (ROM) 32 stores processing programs and monitor programs for executing various processes, and temporarily stores calculation contents and output contents of each sensor. a random access memory (RAM) 33 having a backup memory that stores calculation contents, set values, etc. even when the power is turned off, and first and second input/output circuits 34;
35 is connected to the CPU 31 via the bus line 36, and the CPU 31 and input/output circuits 34, 35
A so-called microcomputer is configured, having a clock 37 which is connected to the computer, etc. and serves as a timing reference for information processing.

The output devices connected to and controlled by the CPU 31 are the timing control valve 19, the linear solenoid 22, and the FCV 26. The timing control valve 19 and the FCV 26 are driven via drive circuits 38 and 39, respectively, and
is driven via a D/A converter 40, a servo amplifier 41, and further via a drive circuit 42. The clock 37 is connected to the D/A converter 40, and the spill position sensor signal 65 is input to the servo amplifier 41.

The input/output circuit 34 is for receiving sensor output. intake temperature sensor 5, intake pressure sensor 6,
The outputs of the water temperature sensor 7 and the accelerator sensor 9 are taken out via buffers 43, 44, 45, and 46.
After sequentially or selecting one of these outputs using a multiplexer (MPX) 47, the A/D converter 4
After converting the data into a digital signal at step 8, the data is output to the bus line 36. Note that a clock 37 is connected to the A/D converter 48. Further, the output of the sensor drive circuit 49 is input to the spill position sensor 25, the detection output of the spill position sensor 25 is input to the multiplexer 47 via the sensor signal detection circuit 50, and the timer position sensor 18 is input to the sensor drive circuit 49. 51 is input, and the detection output of this timer position sensor 18 is input to the sensor signal detection circuit 5.
2 to the multiplexer 47. These detection signals are sequentially selected by the multiplexer 47 and output to the bus line 36 through the A/D converter 48 and the input/output port 34.

On the other hand, the input/output circuit 35 has a torque converter signal 5.
3. An air conditioner signal 54 and a starter signal 55 are input via buffers 56, 57, and 58, respectively. Further, a rotation speed detector 59 is provided to detect the rotation speed of the engine, and its output signal is input into the CPU 31 whose waveform is shaped by a waveform shaping circuit 60 and the fail detection circuit 61 . The output signal of this fail detection circuit 61 is input to the drive circuit 39. In addition, the positive B power supply 62 is connected to the
3. Drive circuit 3 through power supply abnormality detection circuit 64
9, 42 and the fail detection circuit 61.

FIG. 3 shows a flowchart of processing performed by the control device 3 shown in FIG. 1 in order to realize an embodiment of the fuel injection amount control method for a diesel engine according to the present invention.

First, in step 101 it is determined whether 50 msec has elapsed, and if it has elapsed, in step 102 it is determined whether or not it is time to start the engine. In the case of starting, the engine rotational speed N _E is determined in step 103.
It is determined whether the rpm is below 800 rpm, and if it is below 800 rpm, the accelerator opening is controlled in step 105.
ACCP ₀ is calculated using the following formula.

ACCP ₀ = K ₁ (40℃−THW) ...(1) However, THW represents the water temperature and K ₁ represents a constant. This equation (1) is as shown in FIG. 4, and the value of ACCP ₀ increases as the engine water temperature decreases.

If it is determined in step 102 that the engine is not starting, or if in step 103 the engine speed N _E is greater than 800 rpm, ACCP ₀ is set to decrease in step 104. That is, it is performed by the calculation ACCP ₀ =ACCP ₀ -K. However, K is a constant.

New in step 104 and step 105
After ACCP ₀ is determined or step 101
If it is determined that 50 milliseconds have not elapsed, step 106 determines whether ACCP ₀ is positive or negative, and if it is negative, step 107 sets ACCP ₀ to 0% and the process proceeds to step 108. At step 106
If ACCP ₀ is determined to be positive, the process immediately proceeds to step 108 and ACCP ₀ is stored in the RAM 33. That is, ACCP ₀ is calculated and stored in steps 101 to 107.

Next, in step 109, the accelerator opening degree for control is determined.
A comparison is made between ACCP ₀ and the actual accelerator opening ACCP. If ACCP<ACCP ₀ , the program changes ACCP ₀ to ACCP in step 110 and proceeds to the next step 111. If ACCP>ACCP ₀ , the program proceeds to the next step 111 using the actual accelerator opening degree ACCP. In addition, the actual accelerator opening
Engine rotation speed N _E with ACCP as a parameter
The pattern of fuel injection amount for each is determined as shown in FIG. However, the solid line in the figure shows a normal fuel injection amount pattern, and the broken line shows a fuel injection amount pattern when performing parallel movement control in the rotation axis direction, which will be described later.

In step 111, NF(P) is calculated as the amount of movement of the injection amount pattern shown in FIG. 5 in the rotation axis direction according to the engine water temperature, air conditioner, torque converter, and other engine conditions and load conditions. This method of controlling the injection amount pattern by moving it in the direction of the rotation axis is used to perform fast idle control, air conditioner idle up, and other controls, and is already a well-known method. In addition, Figure 6 shows the rotational axis direction movement amount NF (P) with respect to engine water temperature.
The characteristic diagram is shown. In step 112, the value obtained by subtracting the aforementioned NF(P) from the engine rotational speed N _E is set as N _E '. Next, in step 113, the basic injection amount Q _BASE is calculated from the fuel injection amount map showing the relationship between N _E ' and the accelerator opening degree ACCP shown in FIG. However, here, in step 113,
ACCP ₀ determined in steps 101 to 110 may be used as the ACCP.
This is the feature of this embodiment. That is, for example, when the engine is started and the rotational speed is low, the accelerator opening degree ACCP ₀ is used for control purposes, and the opening degree is larger and the injection amount is larger than when the engine is completely warmed up (ACCP ₀ =0%).

Next, in step 114, it is determined whether Q _BASE is greater than or equal to the set value. If Q _BASE is less than the set value (maximum injection amount), the final injection amount Q _FIN = Q _BASE , and the upper limit of Q _BASE is the maximum injection amount.
In step 115, the final injection amount shown in FIG.
Spill position command voltage V _SPP is calculated from the map of Q _FIN and engine rotation speed N _E. This V _SPP is output to the drive circuit 42 and the spill position is changed by the linear solenoid 22 to control the amount of fuel injected.

According to this embodiment, when the engine is started and the engine speed N _E is 800 rpm or less, the accelerator opening degree ACCP ₀ is used for control as shown in FIG. By controlling the amount of fuel injection, the amount of fuel injected to the engine will not be insufficient even when the engine is cold and the rotational speed is low, even if the accelerator is not pressed during startup, improving engine startability. It is effective, and there is no need to step on the accelerator, so it has the effect of simplifying the operation. In addition, even when restarting the engine after it has completely warmed up, the fuel injection amount is controlled by using the accelerator opening ACCP ₀ , which is a control that reduces the opening when the engine temperature is high. It has the effect of reducing smoke without being too much. Furthermore, when the engine speed N _E increases, the accelerator opening is controlled to decrease by subtracting a constant from the controlled accelerator opening, which has a large opening when the temperature is low.
Since the fuel injection amount decreases slowly at low temperatures, this has the effect of preventing engine stall at low temperatures.

As detailed above, according to the present invention, by providing a controlled accelerator opening degree separately from the actual accelerator opening degree, startability is improved when the engine is cold, and smoke is generated when restarting after warming up the engine. can be controlled. In this case, since the accelerator opening degree for control is determined as a function of the engine water temperature, the fuel injection amount can be continuously and finely controlled according to the engine warm-up state at that time.

In addition, since the control based on the accelerator opening is continuous and the control based on the actual accelerator opening is continuous, the engine speed can be increased smoothly and good drivability can be ensured. Become.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a fuel injection pump and peripheral devices to which the present invention is applied, and FIG. 2 is a control device 3 of FIG. 1.
3 is a flowchart of the process performed by the control device 3 in order to realize an embodiment of the fuel injection amount control method for a diesel engine according to the present invention. FIG. A characteristic diagram of the opening ACCP ₀ , Fig. 5 is a fuel injection amount pattern diagram showing the relationship between the fuel injection amount and the engine rotation speed, and Fig. 6 is a characteristic diagram of the rotational axis direction movement amount NF (P) with respect to the engine water temperature. Figure 7 is a basic injection quantity Q _BASE map diagram determined by the relationship between engine speed N _E ′ and accelerator opening ACCP.
Figure 8 shows engine speed N _E and final injection amount Q _FIN
Spill position command voltage determined by the relationship with
V _SPP map. 1...Fuel injection pump, 3...Control device, 5...
... Intake temperature sensor, 6 ... Intake pressure sensor, 7 ... Water temperature sensor, 9 ... Accelerator sensor, 18 ... Timer position sensor, 19 ... Timing control valve, 2
1... Spill ring, 22... Linear solenoid, 23... Coil, 24... Plunger, 25
... Spill position sensor, 26 ... Fuel control valve (FCV), 27 ... Excitation coil, 28 ... Valve,
31... Central processing unit (CPU), 32... Read only memory (ROM), 33... Random access memory (RAM), 34, 35...
...Input/output circuit, 36...Bus line, 38,3
9, 42...drive circuit, 40...D/A converter,
41... Servo amplifier, 43-46, 56-5
8, 63... Buffer, 47... Multiplexer (MPX), 48... A/D converter, 51... Vehicle speed sensor, 59... Rotation speed detector, 60... Waveform shaping circuit, 61... Fail detection circuit.

Claims (1)

[Claims] 1. A fuel injection amount pattern in which the amount of fuel injection supplied in a spray state to a diesel engine mounted on a vehicle via a fuel control valve is determined using an accelerator opening degree and an engine rotation speed as parameters. In a diesel engine fuel injection amount control method that is controlled electronically by Fuel injection amount control for a diesel engine, characterized in that the upper accelerator opening is provided separately from the actual accelerator opening, and the fuel injection amount is controlled using the larger accelerator opening of both the accelerator openings. Method.