JPS6255436A - Fuel injection quantity controller for diesel engine - Google Patents

Abstract

PURPOSE:To carry out an optimum quantity of pilot injection corresponding to temperature for reducing combustion noises by controllably increasing and decreasing a pilot injection quantity for ignition within a predetermined time defined on the basis of temperature. CONSTITUTION:The ignition of fuel which is pilot injected is detected by an ignition sensor 55 in an auxiliary combustion chamber 36. Also, an ignition delay reference time is figured out by a map beforehand stored in ROM of ECU 60 on the basis of cooling water temperature detected by a water temperature sensor 54. And on the basis of the presence of detecting signal of the ignition sensor 55 before the passage of the ignition delay reference time are corrected an actual pilot injection current supply time and a main injection starting time to give a drive signal to a fuel controlling valve 21 and alternate repetitively the pilot injection and the main injection. Thus, the pilot injection quantity is decreased when the ignition is detected within the ignition delay reference time and increased when the ignition is not detected.

Description

[Detailed Description of the Invention] Purpose of the Invention [Industrial Field of Application] The present invention relates to a fuel injection control device for a diesel engine, and more specifically to a fuel injection control device for a diesel engine that performs pilot injection prior to main injection of fuel. Regarding equipment.

[Prior Art] Various fuel injection control devices have been developed for the purpose of reducing combustion noise in diesel engines. For example, before injecting a quantity of fuel that is determined according to the operating state of the diesel engine (hereinafter simply referred to as main injection),
Injection of raw fuel q4 (hereinafter simply referred to as pilot injection)
A fuel injection control device that performs this has been proposed. These devices use pilot injection to achieve smooth combustion in a diesel engine, and reduce combustion noise by controlling combustion slowly, particularly during light loads, to prevent diesel knock. In addition, a method has been proposed in which the start of combustion caused by pilot injection is detected by an ignition sensor, and the start timing of main injection is controlled based on the detection result, thereby achieving smooth combustion and preventing diesel knock. There is. In such prior art, the amount of fuel injected during the pilot injection is always set to be a predetermined constant amount.

[Problems to be Solved by the Invention] The conventional fuel injection control device for a diesel engine has the following problems.

That is, (1) When the temperature of the diesel engine is low, the ignitability of the fuel becomes low. However, since the amount of fuel supplied by pilot injection is constant, in the above case,
There has been a problem in that the fuel caused by the pilot injection may not ignite, and the effect of the pilot injection is not produced, making it impossible to reduce combustion noise.

(2) Also, related to the problem in 1) above, when the temperature of the diesel engine is low, the ignition delay becomes longer.
The amount of fuel injected during the pilot injection must be set to be larger than when the temperature is high, as shown in FIG. However, in the conventional device, there was a problem in that the amount of fuel was set constant without consideration for ignition delay.

An object of the present invention is to provide a fuel injection control device for a diesel engine that performs a suitable amount of pilot injection corresponding to the temperature of the diesel engine and the ignition state by pilot injection when performing injection from pylon 1.

Structure of the Invention and Means for Solving the Problems] The present invention adopts the structure shown in FIG. 1 in order to solve the above problems. FIG. 1 is a basic configuration diagram showing the concept of the present invention. That is, as shown in FIG. 1, the present invention provides a diesel engine equipped with a fuel injection means M2 that first injects a predetermined amount of fuel every time it injects fuel into the diesel engine M1, and then performs main injection. A fuel injection control device for an engine includes: temperature detection means M3 for detecting the cooling water temperature and/or intake air temperature of the diesel engine M1; ignition detection means M4 for detecting ignition of the diesel engine M1; Determination means M for determining whether or not the pylon 1 to ignition by injection has been performed within a predetermined time determined based on the temperature detected by the temperature detection means M3.
5. If it is determined that the ignition has occurred within a predetermined time, the injection m of the next pilot injection is decreased; on the other hand, if it is determined that the ignition has not occurred within a predetermined time, the injection m of the next pilot injection is decreased. The gist of the present invention is a fuel injection control device for a diesel engine, characterized in that it is equipped with a correction means M6 for increasing the injection amount of pilot injection.

When injecting fuel, the fuel injection means M2 first performs a pilot injection of a predetermined amount, and after a predetermined period of time has elapsed, performs a main injection. For example, the fuel injection pump may be provided with a spill electromagnetic control valve that communicates with and shuts off the high-pressure chamber and the low-pressure seedlings. Furthermore, instead of the spill electromagnetic control valve, an actuator using a piezoelectric element (for example, PZT, etc.) may be used to perform pilot injection and main injection. When configured in this way, there is an advantage that the response speed is improved.

The temperature detection means M3 detects the cooling water humidity and/or intake air temperature of the diesel engine M1.

For example, the cooling water temperature may be measured by a water temperature sensor provided in the cooling system of the diesel engine M1, or the intake air temperature may be measured by an intake air temperature sensor provided in the intake passage.

The ignition detection means M4 is necessary to detect ignition of the diesel engine M1 due to pilot injection.

For example, a light receiving element (
For example, a phototransistor, etc.) may be provided, and the light emitted by ignition may be detected by a light receiving element. Alternatively, for example, both electrodes of the ion sensor may be disposed in the combustion chamber, and ignition may be detected by detecting ion current due to ionized fuel upon ignition. Furthermore, for example, a configuration may be considered in which a sensor for detecting the pressure within the combustion chamber is provided and ignition is detected by detecting pressure fluctuations due to ignition.

The determining means M5 means that the pilot].
This is to determine whether ignition has occurred due to injection.

The correction means M6 reduces the injection Q=lffl of the next pilot injection when ignition is performed within a predetermined time, and decreases the injection Q=lffl of the next pilot injection when ignition is not performed within a predetermined time. This correction is made to increase the injection amount. The determination means M5 and the correction means M6 are:
For example, both may be configured as discrete control circuits. Also, for example, the well-known CPU and ROM,
It is also possible to use a logic circuit including peripheral circuit elements such as a RAM, and to perform the above control according to a predetermined processing procedure.

[Function] The fuel injection control device for a diesel engine according to the present invention
Each time the injection means M2 injects fuel, it first performs a predetermined amount of pilot injection, and then when performing main injection, the ignition detected by the ignition detection means M4 is detected by the temperature detection means M3.
If the determining means M5 determines that the operation was performed within a predetermined time determined based on the temperature detected by the correcting means M.
6 decreases the predetermined amount of the next pilot injection, while
If the determining means M5 determines that the ignition has not occurred within the predetermined time, the correcting means M6 operates to increase the predetermined amount of the next pilot injection.

Therefore, the fuel injection control device for a diesel engine of the present invention operates so that the injection amount of the pilot injection is adjusted so that ignition determined in relation to the temperature of the diesel engine M1 is always performed at a suitable time.

The technical problems of the present invention are solved by each component of the present invention acting as described above.

[Example] Next, a preferred example of the present invention will be described in detail based on the drawings.

FIG. 2 is a system configuration diagram of a diesel engine equipped with a diesel engine fuel injection control device according to an embodiment of the present invention. Power is transmitted from a four-cycle diesel engine 1 to a Bosch distribution type fuel injection pump 2 via a drive shaft 3 connected to a crankshaft (not shown). The drive shaft 3 includes a vane pump 4 which is a fuel feed pump, and a pulser 5 having a plurality of protrusions at equal intervals on the outer circumferential surface.
, and the coupling 6 are connected. Fuel is supplied from a fuel tank (not shown) through a vane pump 4.
The fuel is sucked in from the fuel supply boat 7 and filled with fuel. The pressure of the fuel is regulated by a control valve 9, and excess fuel is returned to a fuel tank (not shown) via a fuel return port 10.

The coupling 6 is connected to one end of a plunger 12 which is integrally connected to the cam play 1 and the other end of the plunger 12 is fitted into a cylinder 13.

The coupling 6 and the plunger 12 rotate together, and the plunger 12 is supported so as to be able to reciprocate in its axial direction, that is, in the directions indicated by arrows A and B in FIG.

Incidentally, the plunger 12 and the cam plate 11 are urged by a spring 14 in the direction shown by arrow A in the figure.

A roller ring 15 rotatable together with the drive shaft 3 is disposed between the coupling 6 and the cam plate 11. A cam roller 16 is attached to a surface of the roller ring 15 facing the cam plate 11 along a circumference centered on the rotation axis of the roller ring 15. Also,
A projection 11a is provided on the surface of the cam plate 11 facing the roller ring 15. Rotational force is transmitted from the drive shaft 3 to the cam plate 11 via the coupling 6, and the cam plate 11 pressed against the roller ring 15 rotates, thereby causing the plunger 12 to rotate.
It reciprocates in the directions indicated by arrows A and B in FIG. 2 to distribute and force feed fuel as will be described later.

A block 18 is attached to the housing 17 of the fuel injection pump 2 by fitting the cylinder 13 thereto. A fuel passage 19 is provided within the block 18 and communicates with the fuel chamber 8 on the low pressure side within the housing 17 . The fuel passage 19 is communicated or cut off by a fuel cutoff valve 20, which is a solenoid valve. Generally, a fuel control valve 21, which is a solenoid valve for performing pilot injection and main injection, is attached to the block 18. A needle valve 22 is disposed in the fuel control valve 21, and a high pressure chamber 23 is formed by the needle valve 22, the plunger 12, and the cylinder 13 described above. The high pressure chamber 23 includes fuel introduction recesses 24 formed on the outer peripheral surface of the plunger 12 in correspondence with the number of cylinders.
It can communicate with a fuel introduction passage 25 between the fuel cutoff valve 20 and the high pressure chamber 23 via the fuel cutoff valve 20 and the high pressure chamber 23 . A return passage 26 of the fuel control valve 21 is communicated with the fuel introduction passage 25 via a communication passage 27 within the cylinder 13 . In addition, block 18
A delivery valve 28 is disposed therein, and is required to be able to communicate with the high pressure chamber 23 via a fuel supply passage 29 and fuel supply recesses 30 formed on the outer peripheral surface of the plunger 12 in correspondence with the number of cylinders.

The fuel injection pump 2 configured as described above operates as follows. When the drive shaft 3 rotates in synchronization with the rotation of the diesel engine 1, the vane pump 4 is driven.
The fuel whose pressure is regulated by the pressure regulating valve 9 is transferred to the fuel chamber 8 and the fuel passage 1.
9 and the fuel introduction passage 25. Meanwhile, the plunger 12 and the cam plate 11 rotate in synchronization with the rotation of the drive shaft 3. At this time, the protrusion 1 of the cam plate 11
In the process in which 1a rides on the cam roller 16 of the roller ring 15, the plunger 12 shifts to a fuel compression stroke, and in the process in which the protrusion 11a rides down on the cam roller 16, the plunger 12 shifts to a fuel suction stroke.

During the suction stroke of the plunger 12, the fuel cutoff valve 20 is energized and the fuel passage 19 is communicated, so that fuel is introduced into the high pressure chamber 23 via the fuel passage 19, the fuel introduction passage 25, and the fuel introduction recess 24.

On the other hand, during the compression stroke of the plunger 12, the fuel control valve 21
is energized and the needle valve 22 is blocking the through hole 22a, the fuel in the high pressure chamber 23 is compressed and is pumped to the delivery valve 28 via the fuel supply recess 30 and the fuel supply passage 29. . When the power supply to the fuel control valve 21 is stopped, the needle valve 22 moves in the direction shown by arrow B in FIG.
3 communicates with the return passage 26 which is the low pressure side, and the pumping of fuel is completed. In addition, the delivery valve 2 of the fuel injection pump 2
8 is connected to the injection nozzle 32 of each cylinder of the diesel engine 1 via a fuel pipe 31.

The diesel engine 1 includes a cylinder 33 and a piston 34.
A main combustion chamber 35 is formed, and a sub-combustion chamber 36 is connected to the main combustion chamber 35, and the injection nozzle 32 described above injects fuel into the sub-combustion chamber 36. Further, a compressor 39 of a turbocharger 38 is provided in the intake pipe 37 of the diesel engine 1, while a turbine 41 is provided in the exhaust pipe 40. Further, the exhaust pipe 40 is also provided with a waste gate valve 42 that adjusts the supercharging pressure.

As a detector, the pulser 5 of the fuel injection pump 2 mentioned above is used.
a rotational speed sensor 50 consisting of an electromagnetic pickup disposed facing the outer peripheral surface of the diesel engine; an accelerator sensor 51 consisting of a potentiometer that detects the amount of accelerator operation; An air temperature sensor 52, a supercharging pressure sensor 53 disposed in the intake port 37a communicating with the intake pipe 37 and detecting the supercharging pressure, a water temperature sensor 54 disposed in the cylinder block 33a and detecting the cooling water temperature, and the above-mentioned secondary combustion An ignition sensor 55 is provided in the chamber 36 and detects ignition by receiving light emitted from ignition using a phototransistor, and a crank angle sensor 56 is provided close to and facing a signal disk plate provided on a crankshaft (not shown). Detection signals from each of the above sensors are input to an electronic control unit (hereinafter simply referred to as ECU) 60, while the ECU 60 is connected to the fuel cutoff valve 20 described above.
and the diesel engine 1 by driving the fuel control valve 21.
control.

Next, the configuration of the ECU 60 will be explained based on FIG. 3.

The ECU 60 inputs and calculates each signal detected by each sensor described above according to a control program, and also includes a central processing unit (hereinafter simply referred to as CPU) 6 that performs processing for controlling the eight valves described above.
0a, a read-only memory (hereinafter simply referred to as ROM) 60b in which the control program and initial data are stored in advance, and a random memory in which various data input to the ECU 60 and data necessary for arithmetic control are temporarily stored.

The access memory (hereinafter simply referred to as RAM) 60c is backed up by a battery so that various data necessary for controlling the diesel engine 1 from now on can be stored and retained even if the key switch of the diesel engine 1 is turned off by the driver. It is configured as a logic operation circuit centered around a backup random access memory (hereinafter simply referred to as backup RAM) 60d, etc., and a common bus 60d.
It is connected to input port 0f and output port 0g via e, and performs input/output with external devices.

The ECtJ60 also includes the above-mentioned accelerator sensor 51.
, water temperature sensor 54, intake temperature sensor 52, boost pressure sensor 5
3. Buffer 60h for the output signal from the ignition sensor 55;
60i, 60j, and 60 are provided with 6Qm, a multiplexer 60n that selectively outputs the output signal of each sensor to the CPU 60a, an A/D converter 60o that converts an analog signal into a digital signal, and a rotation speed sensor. 50, a waveform shaping circuit 60q for shaping the waveform of the output signal of the crank angle sensor 56 is also provided.

Signals from each of these sensors are input to the CPU 60a via an input port 0f.

Roughly speaking, the ECU 60 includes drive circuits 60r and 60s for the fuel cutoff valve 20 and the fuel control valve 21 described above, and the CPU 6
0a is connected to the drive circuit 60r through the output port 0g,
A control signal is output to 605.

Next, the processing executed by the ECtJ 60 will be explained based on the flowcharts shown in FIGS. 4(A>, (B), (C), and (D)).

The pilot injection ff1EE output process shown in FIG.
It is executed more. In step 100, the water temperature sensor 54
The cooling water temperature TW of the diesel engine 1 is detected. In the subsequent step 110, a process is performed to calculate the pilot injection basic energization time DPS based on the cooling water temperature TW detected in the step 100. here,
There is a relationship as shown in FIG. 5 between the cooling water temperature TW and the pilot injection basic energization time DPS. That is, as the cooling water temperature TW decreases, the pilot injection basic energization time [)PS becomes longer. The ECU 60 stores a map as shown in FIG. 5 in advance in the ROM 60b.
Based on the value of the cooling water temperature TW detected in step 100 above, the pilot injection basic energization time DP is calculated from the above map.
Calculate S. In the subsequent step 120, a process is performed in which the pilot injection basic energization time DPS calculated in the step 110 is set as the pilot injection actual energization time Dp corresponding to the temperature of the diesel engine 1 at that time.

Next, in step 130, it is determined whether an ignition signal has been detected. Detection of the ignition signal is performed by an ignition signal detection process described later. If the ignition signal is detected, the process proceeds to step 140, and the pilot injection actual energization time D
A process of shortening p by ΔDp is performed, and the process returns to step 130 again. On the other hand, if no ignition signal is detected, the process proceeds to step 150, where a process of extending the pilot injection actual energization time Dp by ΔDo is performed, and the process returns to step 130 again.

Next, based on the flowchart shown in FIG. 4(B),
The ignition detection process will be explained. This ignition detection process is executed in conjunction with the start of pilot injection by fuel injection process, which will be described later. First, in step 200, the auxiliary combustion chamber 36
The ignition sensor 55 inside performs a process of detecting ignition of the pilot-injected fuel. Next step 20
In step 5, it is determined whether or not the ignition sensor 55 detects ignition of the pilot-injected fuel.

If ignition is detected, an ignition signal is output from the ignition sensor 55, so the process proceeds to step 210, where an ignition flag is set, and then the process ends.

On the other hand, if ignition is not detected, the ignition sensor 55
Since no ignition signal is output, the process proceeds to step 220. In step 220, it is determined whether the ignition delay reference time τ has elapsed since pilot injection was started.

Here, there is a relationship as shown in FIG. 6 between the ignition delay reference time τ and the cooling water temperature TW. That is, as the cooling water temperature TW decreases, the ignition delay reference time τ becomes longer. E
The CU 60 stores in advance a map as shown in FIG. 6 in the ROM 60b, and calculates the ignition delay reference time τ based on the cooling water temperature TW detected in step 100 from the map. If the ignition delay reference time τ has not yet elapsed since the start of pilot injection, proceed to step 2 above.
Return to 00 and detect ignition signal! The latitude continues. On the other hand, if the ignition delay value 41 hours τ has elapsed, the process proceeds to step 225, where the ignition flag is reset, and then the main ignition detection process is ended. Thereafter, the main ignition detection process is repeatedly executed with the start of the pilot injection of the fuel injection process (e).

Next, the processing for calculating the amount of main voice IFl will be explained based on the flowchart shown in FIG. 4(C). This main injection calculation process is executed when the diesel engine 1 is started. First, in step 300, a process is performed in which the cooling water temperature TW is detected from the water temperature sensor 54, the intake air temperature TA is detected from the intake air temperature sensor 52, and the pressure P is detected from the boost pressure sensor 53. In the following step 310, the basic injection amount QS of the main injection is calculated based on the diesel engine 10 rotational speed Ne detected by the rotational speed sensor 50 and the accelerator opening degree vh detected by the accelerator sensor 51. In subsequent step 320, based on the pressure P detected in step 300, pressure correction processing is performed on the basic injection mQS calculated in step 310, and pressure correction injection ff1QD is calculated. Following step 330
Now, let us consider the intake air temperature TA detected in step 300 above.
Based on this, the intake temperature correction process for the pressure correction injection fftQp calculated in step 320 is performed, and the intake temperature correction injection amount Qpt is calculated. Next, the process proceeds to step 340, and based on the water temperature TW detected in step 300, the intake temperature correction injection mQ calculated in step 330 is performed.
pt water temperature correction processing is performed, and the actual main injection ff1Q is calculated. Note that each of the above correction processes is performed using the ROM.
This is done using the correction data specified in the map stored in 60b. Next, the process proceeds to step 350, where the main injection energization time tn is calculated from the engine rotational speed Ne and the actual main injection ff1Q, and the process proceeds to NEXT, whereupon the present process ends. Thereafter, this process is repeatedly executed at predetermined time intervals.

Next, the fuel injection process will be explained based on the flowchart shown in FIG. 4(D'). This fuel injection process is executed without delay each time the crank angle sensor 56 detects a reference position signal indicating that the piston of the diesel engine 1 is located at the top dead center. First, step 400
Then, it is determined whether or not the pilot injection start time has arrived, and the system waits until the time arrives. This determination is made by inputting an interrupt signal to the CPU 60a when the time set in advance in the register for the conveyor in the output port 0q matches the time counted by the counter. When the pilot injection start time arrives, the process proceeds to step 410, and pilot injection is started. Next, the process proceeds to step 420, and time counting by the timer counter TM is started. The pilot injection is performed by energizing the fuel control valve 21 until the pilot injection actual energization time Dp calculated or corrected in steps 120, 140 to 150 described above has elapsed (step 430). Pilot injection actual energization time [)p
When the time period has elapsed, the energization of the fuel control valve 311 and valve 21 is stopped, and the pilot injection ends (step 440).

Next, the process proceeds to step 445, in which the presence or absence of an ignition signal is determined based on the state of the ignition flag that was set or reset in the ignition detection process described above. If an ignition signal is detected, the process proceeds to step 460, where main injection is started. On the other hand, if no ignition signal is detected, the process proceeds to step 450. In step 450, the above step 4
From 20 onwards, it is determined whether or not the value of the timer counter TM which continues to measure time coincides with the ignition delay reference time τ described above, and the process waits until the value coincides with the ignition delay reference time τ. When the timer counter TM continues counting and reaches the ignition delay reference time τ, the process proceeds to step 460, and main injection is started. The main injection is
Main injection energization time t calculated in step 350 described above
This is done by energizing the fuel control valve 21 until n has elapsed (step 470).

When the main injection energization time tn has elapsed, the energization to the fuel control valve 21 is stopped and the main injection ends (step 480
). After that, real fuel injection! The 1lFl process is repeatedly executed every time the crank angle sensor 56 detects the reference signal.

Next, an example of the control timing of the above process will be explained based on the timing chart shown in FIG. 7.

As described above, after the reference position signal is detected by the crank angle sensor 56, the drive signal for the fuel control valve 21 is turned ON at time T1, which is the pilot injection start time, and the pilot injection is started (step 400,4
10>. This pilot injection is based on the cooling water temperature - [W] Pilot injection time DP calculated from the map based on
The pilot injection is carried out for an actual energization time Do equal to S, and the drive signal is turned off at time T2 and ends (steps 110, 120, 430, 440>).

During this time Dp, the plunger 12 is in a compression stroke, and an amount of fuel corresponding to the plunger lift amount is pilot injected. In this case, ignition of the pilot-injected fuel is not detected at time T3 after the ignition delay reference time τ has elapsed from time T1, which is the pilot injection start time (steps 200.205, 220.225>. Therefore, At the same time T3, the drive signal for the fuel control valve 21 is turned ON, and main injection is started (step 445.
450, 460>. In this case, ignition is caused by the ignition sensor 55
is detected at time T4.

The main injection is performed over the already calculated main injection energization time tn, and at time T5, the drive signal for the fuel control valve 21 is turned OFF, and the main injection ends (step 350
, 470, 480). During this time tn, the plunger 12 is in the compression stroke, and fuel corresponding to the plunger lift 1-ffl is main injected.

゛ Next, when the reference position signal is detected again by the crank angle sensor 56, the drive signal for the fuel control valve 21 is turned ON at time T6, which is the pilot injection start time.
Pilot injection is initiated (steps 400, 410
>. Since the previous pilot injection did not ignite before the ignition delay reference time τ elapsed, the current pilot injection was carried out over a period of time obtained by extending the previous pilot injection actual energization time Dp by the correction time ΔDp, and the current pilot injection was carried out over a period of time - "7". The drive signal is turned OFF and the process ends (step 130.15).
0,430.440>. This time, the ignition of the pilot-injected fuel is detected by the ignition sensor 55 at time T8, which is before the ignition delay reference time τ has elapsed from time T6, which is the pilot injection start time (step 200,
205.210). Therefore, at time T9, which corresponds to the main injection start time T obtained by adding a slight delay time Δτ to the actual main injection time τO from time T6 to time T8 when ignition was detected, the drive signal for the fuel control valve 21 is It is turned ON and main injection is started (steps 445 and 460>. As described above, main injection is performed after the pilot injected fuel q1 is ignited, so smooth combustion is realized. Main injection starts from time T9. At time T10 after the energization time tn has elapsed, the drive signal for the fuel control valve 21 is turned off and the main injection ends (steps 350, 470, 480>).

Next, when the reference position signal is detected by the crank angle sensor 56, pilot injection is started at time T11 (steps 400 and 410>).

Since the previous pilot injection ignited before the ignition delay reference time τ had elapsed, the current pilot injection was performed over a period of time shortened by the correction time ΔDp from the previous pilot injection actual energization time 1), and ended at time T12. (Steps 130, 140, 430, 440>. Ignition due to the pilot injection is detected by the ignition sensor 55 at time T13 before the ignition delay reference time τ has elapsed (Steps 200, 205, 210>. Therefore, the previous Actual main injection timing τ0 up to time T13 when ignition is detected similarly to
Main injection is started at time T14, which is a main injection start time T obtained by adding a slight delay time Δτ to time T11, and ends at time T'15 after time tn has elapsed (steps 445, 460, 470,480
>. Thereafter, as described above, the pilot injection actual energization time Do and the main injection start timing T are corrected based on the presence or absence of the detection signal of the ignition sensor 55 before the ignition delay reference time τ elapses, and the pilot injection and the main injection are alternately performed. This is done repeatedly.

In addition, in this embodiment, the diesel engine 1 provides the diesel engine M1 with the processes (400, 41
0,420,430,440°460.470.480
) corresponds to the fuel injection means M2. Further, the intake temperature sensor 52, the water temperature sensor 154, the ECU 60, and the process (100, 300) executed by the ECU 60 are used as the temperature detection means M3, and the ignition sensor 55, the ECU 60, and the
The process executed by U60 (200> is the ignition detection means M4, the process executed by ECU60, ECU6CU60, and ECtJ60 (140,150>
function as the correction means M5.

As explained above, in this embodiment, the ignition of the pilot injected fuel detected by the ignition sensor 55 is detected by the water temperature sensor 55.
If the ignition delay is detected within the ignition delay reference time τ determined based on the coolant temperature TW detected in step 4, the current main injection is performed approximately at the ignition detection time, and the next pilot injection actual energization time Dp is changed by the correction time ΔDp. On the other hand, if the ignition is not detected even after the ignition delay reference time τ has elapsed, the current main injection is adjusted to the ignition delay reference time τ.
It is configured to carry out the correction after the elapse of time and extend the next pilot injection actual energization time Dp by the correction time ΔDp. Therefore, even when the diesel engine 1 is in a low temperature state, the nozzle for pilot injection is corrected, so the probability that the pilot injected fuel will spontaneously ignite increases, and the reliability of ignition by pilot injection is improved. It becomes possible to maintain a high level regardless of temperature conditions.

In addition, since the start timing of main injection is changed depending on the ignition state of the pilot-injected fuel, smooth combustion is achieved without causing problems such as diesel knock due to sudden combustion, and diesel engine 1 Noise during operation can be reduced.

In general, since the ignition of the pilot injection is directly detected and controlled by the ignition sensor 55, the diesel engine 1
This has the advantage of improving control accuracy because it is not affected by mechanical properties such as the compression ratio inherent in the fuel, or fuel properties such as fuel ignitability such as cetane number, viscosity, and pour point.

In addition, in this example, the pilot injection basic energization time [)P
S and ignition delay reference time τ were calculated from a two-dimensional map that defined the relationship with the cooling water temperature TW, for example, from a two-dimensional map that defined the relationship with the intake air temperature TA, or between the cooling water temperature TW and the intake air temperature. The effects of the present invention can also be obtained even if the calculation is performed based on a three-dimensional map that defines the relationship between the two TAs.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way, and as described in detail above without departing from the gist of the present invention,
In the fuel injection control device for a diesel engine according to the present invention, when the determining means determines that ignition has been detected by the ignition detecting means within a predetermined time determined based on the temperature detected by the temperature detecting means, the correcting means The correction means is configured to reduce the injection amount of the pilot injection, and increase the injection amount of the next pilot injection if it is determined that ignition has not been detected within the predetermined time, so that the diesel engine Since the optimum amount of pilot injection can be performed in accordance with the temperature of the engine, the pilot injection has an excellent effect in that combustion is carried out smoothly and combustion noise can be reduced.

In addition, since the correction means increases or decreases the amount of pilot injection based on the actual ignition detected by the ignition means, factors that determine ignitability, such as the compression ratio of the diesel engine and the characteristics of the fuel (setup There is also an advantage that the injection amount of the pilot injection can be appropriately controlled even with respect to fluctuations in the fuel consumption (e.g., fuel consumption, etc.).

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram showing the concept of the present invention, FIG. 2 is a system configuration diagram of a diesel engine that is an embodiment of the present invention, and FIG. 3 is a block diagram for explaining the configuration of the ECU. Figure 4 (A). (B), (C), (D> go to flowchart 1 showing the process executed in one embodiment of the present invention, and FIG. 5 shows a map defining the relationship between the basic pilot injection energization time and the cooling water temperature. Graph, Figure 6 is a graph showing a map defining the relationship between ignition delay reference time and cooling water temperature, Figure 7 is a timing chart showing control timing of pilot injection and main injection, and Figure 8 is pilot injection Q = lffl. It is a graph showing the relationship between Ml...Diesel engine M2...Fuel injection means M3...Temperature detection means M4...Ignition detection means M5...Judgment means M6...Correction means 1...Diesel engine 2...Fuel injection pump 52...Intake temperature sensor 54...Water temperature sensor 55...Ignition sensor 60...Electronic control unit 60 a-CPU

Claims (1)

[Scope of Claims] 1. A fuel injection control device for a diesel engine, which is equipped with a fuel injection means that first injects a predetermined amount of fuel every time fuel is injected into the diesel engine, and then performs main injection, temperature detection means for detecting cooling water temperature and/or intake air temperature of the diesel engine; ignition detection means for detecting ignition of the diesel engine; and ignition caused by the detected pilot injection is detected by the temperature detection means. a determination means for determining whether or not the ignition has been performed within a predetermined time based on the detected temperature; A fuel injection control device for a diesel engine, comprising: a correction means for increasing the injection amount of the next pilot injection when it is determined that the ignition has not been performed within a predetermined time.