JP2000170579A - Fuel injection control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection control device for a diesel engine for reducing smoke in operating an exhaust throttling means. SOLUTION: An injection pump 20 injects and supplies fuel to the combustion chamber 12 of an on-vehicle diesel engine 10 via a fuel line 18 and a fuel injection nozzle 17. An exhaust throttle valve 32 is arranged in an exhaust passage 25 to fulfil a function as an exhaust brake by operating the valve 32 at the time of the deceleration of a vehicle, to increase the flow passage resistance of exhaust. An ECU 90 calculates reference injection timing in accordance with an engine speed and fuel injection quantity. At the time of the operation of the exhaust brake, the ECU 90 corrects the injection timing of fuel to a spark advance side from reference injection timing based on an engine speed and cooling water temperature at the respective timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a diesel engine for controlling fuel injection timing.

[0002]

2. Description of the Related Art As is well known, in a diesel engine, a fuel injection control for appropriately adjusting a fuel injection amount and a fuel injection timing in accordance with operating conditions such as an engine speed, an accelerator opening, a coolant temperature, an intake air temperature and the like is performed. Is being done.

[0003] In a vehicle equipped with a diesel engine, in particular, a vehicle having a heavy vehicle weight, a heavy load is applied to a brake device. Therefore, an exhaust brake that increases the effect of engine braking is employed. The exhaust brake increases the internal resistance of the engine and decelerates the vehicle by closing an exhaust throttle valve provided in the exhaust passage. The closing of the exhaust throttle valve is performed not only for the purpose of an exhaust brake but also for the purpose of hastening warm-up. That is, the exhaust gas temperature is raised by increasing the engine speed during idling and closing the exhaust throttle valve.

[0004]

However, when the exhaust throttle valve is closed for the above-mentioned purpose, the intake air amount decreases with an increase in internal EGR due to an increase in the flow resistance of the exhaust system. Here, the internal EGR is a phenomenon in which a part of the burned gas in the combustion chamber is returned to the intake passage and mixes with the intake air. In this case, the combustion state changes due to the internal EGR, and the combustion of the fuel becomes insufficient and smoke is generated.

Japanese Patent Application Laid-Open No. 58-158348 discloses a fuel injection timing control for an engine having an exhaust throttle valve. The apparatus disclosed in the publication includes an exhaust particulate purifying device that collects particulates contained in exhaust gas and periodically incinerates the collected exhaust particulates. The exhaust throttle is performed and the fuel injection timing is retarded. Thus, the temperature of the exhaust gas is raised to a temperature required for combustion of the exhaust particulates. In other words, this is a device that causes the "afterburning" phenomenon, does not promote the combustion in the combustion chamber to reduce the exhaust particulates as unburned fuel, and has not studied the measures against smoke.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide a diesel engine fuel injection control device which can reduce the generation of smoke when the exhaust throttle means operates. To provide.

[0007]

According to a first aspect of the present invention, there is provided a fuel injection device for injecting fuel into a vehicle-mounted diesel engine, the fuel being injected by the fuel injection device. In a fuel injection control device for controlling a timing based on a basic injection timing corresponding to an engine speed and a fuel injection amount, exhaust throttle means disposed in an exhaust passage to increase exhaust gas flow path resistance; When the exhaust throttle means is operated at the time of deceleration, a deceleration correction means for advancing the fuel injection timing from the basic injection timing based on the operating conditions of the engine at each time is provided. is there.

According to the above configuration, when the exhaust throttle means is operated at the time of deceleration of the vehicle, the flow of the exhaust gas is blocked and the flow path resistance of the exhaust is increased, thereby performing the function as an exhaust brake. That is, the internal resistance of the engine increases and the effect of the engine brake increases. By the way, during the operation of the exhaust brake, the amount of intake air supplied into the combustion chamber of the engine decreases due to the increase in internal EGR as described above, and the smoke is delayed due to the ignition delay of the injected fuel accompanying the decrease in the amount of intake air. Is more likely to occur.

On the other hand, when the exhaust throttle means is operated when the vehicle is decelerated, that is, when the exhaust brake is operated, the fuel injection timing is advanced from the basic injection timing based on the respective operating conditions. The ignition delay of the fuel is prevented, and the combustion of the injected fuel is promoted. As a result, the combustion of the injected fuel is sufficiently performed, and the generation of smoke is reduced,
Exhaust gas deterioration can be prevented.

According to a second aspect of the present invention, in the fuel injection control device for a diesel engine according to the first aspect,
The gist of the operating conditions is that the engine speed and the temperature of the engine cooling water are used.

According to the above configuration, the fuel injection timing is corrected based on the engine cooling water temperature and the engine speed, and the smoke is reliably reduced. According to a third aspect of the present invention, in the fuel injection control device for a diesel engine according to the first or second aspect, the fuel injection is limited when the engine speed is equal to or higher than a predetermined speed during vehicle deceleration. In the fuel injection control device described above, when the engine speed as the operating condition is equal to or higher than the predetermined speed at the time of vehicle deceleration, the advance correction of the basic injection timing by the deceleration correction means is stopped. Is what you do.

When the engine speed is equal to or higher than a predetermined speed during vehicle deceleration, fuel injection is restricted. For example, when the accelerator operation is released and the engine speed is relatively high, a fuel cut is performed in which the fuel supplied to the engine is set to "0". No timing correction is required. Therefore, when the engine speed is equal to or higher than the predetermined speed during vehicle deceleration, the advance correction of the basic injection timing is stopped.

According to a fourth aspect of the present invention, in the fuel injection control device for a diesel engine according to the first aspect,
When the exhaust throttle means is operated in a vehicle stopped state to promote warming of the engine, a warm-up correction means for changing the injection timing with respect to the basic injection timing based on the warm-up state of the engine at each time. The point is to prepare.

According to the above configuration, when the vehicle is stopped during a cold start, the flow of exhaust gas is prevented by the operation of the exhaust throttle means, so that the exhaust gas temperature rises and the warm-up of the engine is accelerated. At this time, the combustion of the injected fuel is promoted by correcting the injection timing based on the warm-up state of the engine. Accordingly, there is no inconvenience that smoke is generated due to insufficient combustion due to the internal EGR, and it is possible to achieve both promotion of warm-up of the engine due to an increase in exhaust gas temperature and reduction of smoke.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a fuel injection control system for a diesel engine according to the present invention.

FIG. 1 is a schematic configuration diagram of a fuel injection control device for a multi-cylinder diesel engine 10 according to the present embodiment. As shown in FIG. 1, the engine 10 includes a combustion chamber 12
And has a plurality of cylinders. In the intake stroke of the engine 10, when the intake port 13 provided for each cylinder is opened by the intake valve 14, the external air sucked into the intake passage 16 through the air cleaner 15 is released.
Flow into 2. Fuel injection nozzle 1 provided for each cylinder
7 is connected to an inner cam type distribution type fuel injection pump (hereinafter, referred to as “injection pump”) 20 through a fuel line 18.

The fuel injection nozzle 17 has a built-in needle valve (not shown) and a spring for adjusting the valve opening pressure of the needle valve. Then, the valve is opened and fuel is injected and supplied to the combustion chamber 12.

In each cylinder of the engine 10, the air sucked into the combustion chamber 12 is pressurized by the upward movement of the piston 21, and the fuel is injected into the pressurized and high-temperature air to self-ignite. Combustion and explosion of fuel
The piston 21 moves down. The downward movement of the piston 21 causes the crankshaft 22 to rotate, and the engine 10
Is obtained. In the exhaust stroke of the engine 10, when the exhaust port 23 provided for each cylinder is opened by the exhaust valve 24, the exhaust gas generated in the combustion chamber 12 is guided to the exhaust passage 25 and discharged to the outside.

An accelerator sensor 27 disposed near the accelerator pedal 26 detects the amount of depression of the accelerator pedal 26 and outputs a signal corresponding to the amount of depression. Intake passage 1
An intake air temperature sensor 28 provided on the upstream side of 6 detects the temperature (intake air temperature) of the intake air flowing into the intake passage 16 from the air cleaner 15. An intake pressure sensor 29 provided on the downstream side of the intake passage 16 detects an intake pressure in the intake passage 16 and outputs a signal corresponding to the pressure. Water temperature sensor 30 provided on the water jacket of engine 10
Detects the cooling water temperature THW of the engine 10 and outputs a signal corresponding to the detected temperature. In the present embodiment, the cooling water temperature THW is a parameter indicating the warm-up state of the engine 10.

An exhaust throttle valve 32 is provided in the exhaust passage 25 as exhaust throttle means that opens and closes when driven by an actuator 31. Actuator 3 above
1 includes a diaphragm 31c for partitioning and forming a negative pressure chamber 31b in a case 31a, and a rod 31d protruding outside the case 31a and connected to an exhaust throttle valve 32 while being connected to the diaphragm 31c. That rod 3
1d is urged by a coil spring 31e in the case 31a in a direction protruding from the case 31a. Then, in this state, the exhaust throttle valve 32 is closed.

The negative pressure chamber 31b has a negative pressure passage 33 and an electric vacuum regulating valve (E).
A VR pump (VRV) 34 is connected to a vacuum pump 35 driven by the rotation of the crankshaft 22. The EVRV 34 includes an electromagnetic solenoid (not shown). By controlling the driving of the electromagnetic solenoid, the air in the negative pressure chamber 31b is sucked into the vacuum pump 35 through the negative pressure passage 33, and the amount of protrusion of the rod 31d with respect to the case 31a decreases, and the rod 31d is attached to the rod 31d. The exhaust throttle valve 32 is opened. Normally, the engine 1
By the operation of 0, the exhaust throttle valve 32 is fully opened.

A vehicle speed sensor 36 provided near a transmission (not shown) detects the vehicle speed (vehicle speed) based on the rotation of the transmission gear. Next, a specific configuration of the injection pump 20 will be described in detail with reference to FIGS.

As shown in FIG. 2, the injection pump 20 has a drive shaft 40, which is rotatably supported by a housing 41. The shaft 40 is drivingly connected to a crankshaft 22 which is an output shaft of the engine 10, and rotates in synchronization with the rotation of the crankshaft 22.

An annular pulsar 42 is fixed to the outer periphery of the drive shaft 40 so as to be integrally rotatable.
A pickup coil 44 that constitutes the rotation sensor 43 is provided at a position opposite to the pickup coil 44. For details, see Pulsa 42
Has a plurality of projections provided at equal angles on the outer peripheral surface thereof.
The rotation speed of the drive shaft 40 is detected by measuring the passage of each projection accompanying the zero rotation. That is, the engine speed NE is detected.

The fuel feed pump 45 provided in the housing 41 is driven by the rotation of the drive shaft 40. The feed pump 45 supplies fuel from a fuel tank through a fuel passage (not shown) to a fuel gallery 46.
Supply within.

One end of the housing 41 (the right end in FIG. 2)
A cylinder 48 is fixed to the head 47 which is fixed to the, and a distribution shaft 49 is rotatably supported on the cylinder 48. The distribution shaft 49 is connected to the drive shaft 40 and rotates integrally with the drive shaft 40. A cap 50 is inserted into and fixed to the head 47, and the cap 50 is in contact with an end of the distribution shaft 49.

At one end of the distribution shaft 49, a plurality of support holes 53 extending in the radial direction of the shaft 49 are formed. The plungers 54 are slidably supported by inserting a plurality of plungers 54 into the support holes 53. A fuel pressurizing chamber 55 is defined by the inner end surface of each plunger 54 and the inner wall of the support hole 53.

At the outer end side of the plunger 54, holding portions 56 are respectively arranged, and the holding portions 56 rotatably hold rollers 57. An inner cam ring 58 is provided on the outer peripheral side of the roller 57, and a plurality of cam ridges corresponding to the number of cylinders of the engine 10 are formed on an inner peripheral surface of the inner cam ring 58, that is, a cam surface. As the roller 57 moves along the cam surface with the rotation of the distribution shaft 49, the plunger 54 reciprocates in the radial direction of the distribution shaft 49. Then, as the volume of the fuel pressurizing chamber 55 increases or decreases in accordance with the reciprocating motion of the plunger 54, fuel is sucked into the fuel pressurizing chamber 55, and the fuel is pressurized in the same chamber 55.

The rotation angle of the inner cam ring 58 with respect to the distribution shaft 49 is adjusted by a timer device 60 provided on the housing 41. The timer device 60 includes an electromagnetic timer control valve (TCV) 61.
The rotation angle of the inner cam ring 58 is changed by controlling the signal for energizing 61, and the fuel suction timing and the fuel pressurization timing in the fuel pressurization chamber 55 are controlled.

An annular passage 62 is formed inside the cylinder 48 in the entire circumferential direction. In the distribution shaft 49,
A fuel passage 63 having one end opening to the fuel pressurizing chamber 55 is formed. The fuel passage 63 opens to the annular passage 62 in the middle thereof, and the other end opens to the outer peripheral wall of the distribution shaft 49. . The cylinder 48
The head 47 has the same number of communication passages 64 as the number of cylinders of the engine 10 (only one pair of communication passages 64 is shown in FIG. 2).
Is formed, and the communication passage 64 is provided with the delivery valve 6.
It leads to 5. With the rotation of the distribution shaft 49, the opening of the fuel passage 63 selectively matches the opening of each communication passage 64, so that the fuel pressurizing chamber 55 and the delivery valve 65 are in communication with each other through the two passages 63 and 64. Become.

FIG. 3 shows a section taken along line 3-3 in FIG. As shown in FIG. 3, the housing 41 is provided with an electromagnetic spill valve 66 for adjusting the amount of fuel discharged from the injection pump 20 each time, that is, the amount of fuel injected from each fuel injection nozzle 17. ing. The electromagnetic spill valve 66 is a normally open valve, and has a needle valve 67 as a valve body.
An armature 68 fixed to the needle valve 67, a needle body 69 that slidably supports the needle valve 67, and the like are provided.

In a case 70 fixed to the housing 41, a stator 72 having an electromagnetic coil 71 is disposed. A rod 75 of a needle valve 67 is slidably supported in a center hole 73 formed in the stator 72. A disk-shaped armature 68 fixed to a rod 75 is provided above the stator 72.

A portion of the needle valve 67 below the rod 75 is inserted into an insertion hole 81 formed in the case 70. Needle body 69 having a substantially cylindrical shape
Are inserted into support holes 82 formed in the cylinder 48. A peripheral groove 83 is formed in the inner peripheral wall of the needle body 69. The circumferential groove 83 is communicated with the annular passage 62 by spill holes 85 formed in the needle body 69 and the cylinder 48, respectively.

The needle body 69 and the cylinder 4
A spill hole 86 is formed in 8. Needle valve 67
Is provided with a reduced diameter portion 67a, and a communication space 87 is formed by an outer peripheral wall of the reduced diameter portion 67a and an inner peripheral wall of the needle body 69. This communication space 87 has a spill hole 8
6 and always communicates with the fuel gallery 46.

A compression spring 88 is provided in the lower part of the needle body 69, and the needle valve 67 is urged upward by the spring 88.
When the drive signal input to the electromagnetic spill valve 66 (electromagnetic coil 71) is an off signal, that is, when the electromagnetic coil 71 is not energized and the stator 72 is not excited, FIG.
, The needle valve 67 is held at the valve-opening position shown by the urging force of the compression spring 88. This allows
The circumferential groove 83 and the spill hole 86 of the needle body 69 are communicated through the communication space 87, and the electromagnetic spill valve 66 is opened. As a result, the fuel pressurization chamber 55 and the fuel gallery 4
6 is communicated with the fuel passage 63, the annular passage 62, the spill hole 85, the circumferential groove 83, the communication space 87, and the spill hole 86.

On the other hand, when the drive signal input to the electromagnetic spill valve 66 is an ON signal, that is, when the electromagnetic coil 71 is energized and the stator 72 is excited, the armature 68 is connected to the stator 72. The suction causes the needle valve 67 to move downward in the drawing against the urging force of the compression spring 88. Thereby, the peripheral groove 83 and the communication space 87 are shut off by the needle valve 67, and the electromagnetic spill valve 66 is closed. As a result, the fuel pressurization chamber 5
5 and the fuel gallery 46 are cut off.

Here, the fuel injection operation by the injection pump 20 will be described in detail. When the engine 10 is started, the distribution shaft 49 rotates with the rotation of the drive shaft 40. Then, with the rotation of the distribution shaft 49,
As the plunger 54 reciprocates in the radial direction of the shaft 49, the volume of the fuel pressurizing chamber 55 increases and decreases. Here, when the volume of the fuel pressurization chamber 55 increases, if the electromagnetic spill valve 66 is in the open position (an OFF signal is output to the valve 66), the fuel in the fuel gallery 46 will be spilled. The fuel is introduced into the annular passage 62 through the hole 86, the communication space 87, the peripheral groove 83, and the spill hole 85, and is sucked into the fuel pressurizing chamber 55 through the fuel passage 63.

After the fuel sucked into the fuel pressurizing chamber 55 outputs an ON signal to the electromagnetic spill valve 66 to close the valve 66, the volume of the fuel chamber 55 decreases. Pressurized. When the fuel pressure is increased to a predetermined pressure or more, the delivery valve 65 and the fuel injection nozzle 17 are opened. As a result, the fuel in the fuel pressurization chamber 55 passes through the fuel passage 63, the communication passage 64,
The fuel is fed to the fuel injection nozzle 17 through the delivery valve 65 and the fuel line 18 and injected from the nozzle 17 into the corresponding cylinder. The timing of the fuel injection is adjusted by controlling the signal for energizing the TCV 61 and changing the rotation angle of the inner cam ring 58.

As described above, the OFF signal is output to the electromagnetic spill valve 66 at a predetermined timing from the state in which the fuel is being fed from the fuel pressurizing chamber 55 to the fuel injection nozzle 17, so that the valve 66 is turned on. The valve is again opened, and the fuel pressurization chamber 55 and the fuel gallery 46 are communicated. Therefore, a part of the fuel pressurized in the fuel pressurizing chamber 55 overflows (spills) from the chamber 55 into the fuel gallery 46 through the fuel passage 63, the annular passage 62, the spill holes 85, 86 and the like. . As described above, the fuel in the fuel pressurizing chamber 55 is spilled to the fuel gallery 46, so that
The fuel pressure at 5 drops sharply. As a result, since the delivery valve 65 is closed, the fuel injection nozzle 17
Is stopped, and the fuel supply to the cylinder ends.

As shown in FIG. 1, an electronic control unit (ECU) 90 includes a central processing unit (CPU) 91, a read-only memory (ROM) 92, and a random access memory (RA).
M) 93, backup RAM 94, external input circuit 9
5 and an external output circuit 96. The ECU 90 constitutes a logical operation circuit in which these units 91 to 94, an external input circuit 95, an external output circuit 96 and the like are connected by a bus 97. Here, the CPU 91 has an arithmetic control function,
It has the function of a counter. The ROM 92 stores a predetermined control program or the like in advance, and the RAM 93 stores
1 is temporarily stored. Backup RAM 9
3 saves the stored data even after the engine is stopped. The external input circuit 95 is composed of a buffer, a waveform shaping circuit, an A / D converter and the like (all not shown), and the external output circuit 96 is composed of a drive circuit (not shown).

The external input circuit 95 includes the sensors 27 to
The ECU 90 receives signals from the sensors 27 to 30, 36, and 43 via an external input circuit 95. Also, the external output circuit 96 has an EV
The RV 34, the TCV 61, and the electromagnetic spill valve 66 are connected, and the ECU 90 sends the EVRV 3 via an external output circuit 96.
4. A drive signal is output to the TCV 61 and the electromagnetic spill valve 66.

That is, the ECU 90 controls the sensors 27 to 3
Signals from 0, 36, 43, and the like are taken in, and the TCV 61, the electromagnetic spill valve 66, and the like are driven and controlled based on the input signals, thereby executing fuel injection timing control, fuel injection amount control, and the like.

In this embodiment, when a predetermined exhaust brake condition or heater idle-up condition is satisfied, the ECU 90 drives the EVRV 34 to operate the exhaust throttle valve 32 to the valve closing side, thereby operating the exhaust brake. . At this time, the ECU 90 corrects the fuel injection timing.

More specifically, when the driver turns on an exhaust brake switch (not shown) and the vehicle speed is, for example, 1
When the driver releases his / her foot from the accelerator pedal 26 at 7 km / h or more, the exhaust brake condition is satisfied. Then, the exhaust throttle valve 32 is closed from the previously fully opened state, and the internal resistance of the engine 10 increases, so that the effect of the engine brake increases.

When the vehicle is stopped, a warm-up switch (not shown) is turned on by the driver, the engine speed NE is lower than a predetermined speed, and the water temperature THW is lower than a predetermined temperature (for example, 80 ° C.). At this time, the heater idle-up condition is satisfied. Then, the engine speed NE is set to 120
The fuel injection amount is increased to keep the rotation speed constant at 0 rpm, and the exhaust throttle valve 32 is closed from the previously fully opened state, thereby promoting warm-up. In other words, the exhaust gas temperature is raised by preventing the flow of the exhaust gas with the increase of the flow path resistance,
The warm-up time of the engine 10 is reduced.

When the exhaust throttle valve 32 is closed and the exhaust gas flow path resistance increases, internal EGR occurs. Therefore, the amount of intake air supplied into the combustion chamber 12 of the engine 10 decreases. That is, when the exhaust throttle valve 32 is closed, the combustion state of the fuel changes, and smoke is easily generated.

Therefore, in this embodiment, the exhaust throttle valve 3
When the valve 2 is closed, the fuel injection timing is corrected based on the engine speed NE and the coolant temperature at that time,
Reduce the occurrence of smoke.

In this embodiment, the fuel injection means is constituted by the fuel injection nozzle 17, the fuel line 18, and the injection pump 20. Here, of the processing executed by the ECU 90, the processing for calculating the fuel injection amount is described in FIG.
It will be described in detail with reference to FIG. This process is executed at predetermined intervals.

First, in step 100, the ECU 90 reads the detection signals from the sensors 27 to 30, 36, 43, etc., and depresses the accelerator pedal depression amount, intake air temperature, intake air pressure, and cooling water temperature T.
HW, vehicle speed, engine speed NE, etc. are detected. Then, in step 110, the ECU 90 calculates the basic injection amount Qbase using a known map based on the engine speed NE and the accelerator pedal depression amount.

Thereafter, in step 120, the ECU 90 calculates the final injection amount Qfin as in the following equation. Qfin = Qbase + α where α is a correction injection amount including, for example, intake air temperature, intake pressure, water temperature correction, and the like. More specifically, the intake air temperature correction corrects a deviation of the air-fuel ratio caused by a difference in air density. When the intake air temperature is low, the density increases, so that the injection amount is increased. In the intake pressure correction, the injection amount is increased because the air amount increases when the intake pressure is high. In the water temperature correction, the injection amount is increased as the water temperature THW is lower, thereby ensuring the operability of the engine 10 after the cold start.

The ECU 90 calculates the target fuel injection timing Atrg using the final injection amount Qfin calculated as described above. Here, the fuel injection timing calculation process executed by the ECU 90 will be described in detail with reference to FIG. Note that the process of FIG. 5 is executed after calculating the final injection amount Qfin.

In step 200, the ECU 90 calculates the basic injection timing Abase from a two-dimensional map based on the engine speed NE and the final injection amount Qfin. Here, the basic injection timing Abase is set to a more advanced value as the engine speed NE increases and the injection amount Qfin increases.

In step 210, the ECU 90 determines whether or not the intake throttle valve 32 is in a closed state. Specifically, the ECU 90 makes the determination based on the control flag determined in the drive processing (not shown) of the intake throttle valve 32.
The control flag is a flag that is set when the above-described exhaust brake condition or heater idle-up condition is satisfied.

If it is determined that the exhaust throttle valve 32 is in the closed state, the ECU 90 proceeds to step 220 to determine whether the heater idle-up condition is satisfied or the exhaust brake condition is satisfied. Is determined. When the exhaust brake condition is satisfied, EC
U90 proceeds to step 230 to calculate the correction amount Aexb from a two-dimensional map (exhaust brake map) using the engine speed NE and the water temperature THW as parameters as shown in FIG. 6A. In FIG. 6A, when the engine speed is 1200 rpm or less, the correction amount Aexb increases toward the advance side as the water temperature THW increases, and when the engine speed NE is higher than 1200 rpm, the correction amount Aexb increases.
exb = 0 ° CA.

During the operation of the exhaust brake, if the engine speed NE is relatively high, in order to utilize the engine brake, a fuel cut is performed in which the fuel supplied to the combustion chamber 12 of the engine 10 is set to "0". In the rotation range, no smoke is emitted and no correction of the fuel injection timing is required. For this reason, in the present embodiment, the engine speed NE is 120
If it is higher than 0 rpm, the correction amount Aexb = 0 CA. On the other hand, when the engine speed NE decreases and the fuel gradually increases, the ignition delay of the injected fuel becomes a problem, and the fuel injection timing needs to be corrected. That is, the basic injection timing Abase at this time is a value on the retard side because the engine speed NE is low and the fuel injection amount Qfin is small. Therefore, in the present embodiment, the correction amount Aexb is set to the advanced side to promote the combustion of the injected fuel.

When the coolant temperature THW is low, the fuel injection amount Qfin is increased in order to enhance the operability of the engine 10, and the basic injection timing Abase calculated based on the increased fuel injection amount Qfin is the warm injection amount. It is a value on the advance side of the basic injection timing Abase after the engine. That is, as the warm-up of the engine 10 progresses and the temperature of the coolant of the engine 10 increases, the basic injection timing Abase
Is set to the retard side, so that the ignition delay of the fuel during the operation of the exhaust brake is likely to occur. Therefore, in the present embodiment, the value of the correction amount Aexb is set to a larger value on the advance side as the water temperature THW is higher.

If the heater idle-up condition is satisfied, the ECU 90 proceeds to step 240, where a one-dimensional map (a heater idle map) using the water temperature THW as a parameter as shown in FIG. From the correction amount Aexb. Note that, in the present embodiment, the correction amount Aexb at the time of the heater idle-up is as follows:
When the water temperature is 80 ° C. or lower, a predetermined amount toward the retard side is set regardless of the water temperature THW, and when the water temperature is 80 ° C. or higher, 0 ° CA is set.

If it is determined in step 210 that the exhaust throttle valve 32 is not in the closed state, the ECU 9
0 is the correction amount Aexb = 0 ° C. in step 250
After setting to A, the process proceeds to step 260. And EC
U90 calculates the target fuel injection timing Atrg as in the following equation in step 260. Atrg = Abase + Aexb The ECU 90 calculates the fuel injection amount Qf calculated as described above.
TCV6 based on the target fuel injection timing Atrg.
1 and the electromagnetic spill valve 66 are driven and controlled so that a desired amount of fuel is supplied at a desired timing to the combustion chamber 12 of the engine 10.
To be injected.

In the present embodiment, step 230 in FIG.
And 260 correspond to the deceleration correction means.
And 260 correspond to the warm-up correction means. As described above, according to the present embodiment, the following effects can be obtained.

(1) During the operation of the exhaust brake accompanying the closing of the exhaust throttle valve 32, smoke is likely to occur due to the ignition delay of the injected fuel due to the decrease in the intake air amount. However, in the present embodiment, at the time of operation of the exhaust brake, the fuel injection timing is determined based on the current engine speed NE and the engine coolant temperature THW based on the basic injection timing Aba.
Since the angle is advanced from se, the ignition delay of the fuel is prevented, and the combustion of the injected fuel is promoted. As a result, the combustion of the injected fuel is sufficiently performed, the generation of smoke is reduced, and the deterioration of exhaust gas can be prevented.

(2) When the engine speed NE is equal to or higher than the predetermined engine speed (1200 rpm) at the time of vehicle deceleration, a fuel cut is performed in which the fuel supplied to the engine is set to "0". No correction amount Aexb
The correction of the injection timing is not performed with = 0 ° CA. That is, when the engine speed is equal to or higher than 1200 rpm, the advance correction of the basic injection timing Abase is stopped, so that unnecessary correction is eliminated, which is practically preferable.

(3) When the heater is idle-up,
When the water temperature is equal to or lower than 80 ° C., the injection timing is corrected to the retard side, so that the combustion of the injected fuel is accurately performed. Therefore, there is no inconvenience that smoke is generated due to insufficient combustion due to the internal EGR, and it is possible to achieve both promotion of warm-up of the engine 10 due to an increase in exhaust gas temperature and reduction of smoke.

(4) In this embodiment, the higher the water temperature, the larger the correction amount Aexb is set on the advance side. As a result, ignition delay of fuel is properly prevented, and generation of smoke can be reduced.

The present embodiment can be embodied with the following modifications. In the above embodiment, the inner-cam type distribution pump 20 is employed, but the present invention is not limited to this. For example, a face cam type distribution type pump or a row type pump may be employed. Alternatively, a combination of a unit injector and a unit pump may be employed, or a pressure accumulating (common rail) type injection device may be employed.

A structure for controlling the opening degree of the exhaust throttle valve 32,
More specifically, the duty of the voltage application to the electromagnetic solenoid of the EVRV 34 is controlled so that the vacuum pump 35
The exhaust throttle valve 32 is adjusted by adjusting the amount of intake air sucked by the
May be implemented in a configuration that adjusts the opening degree of. In this case, the internal EG generated according to the opening degree of the exhaust throttle valve 32 is generated.
Since the R amount changes, the combustion state of the injected fuel differs. Therefore, a map using the engine speed NE and the water temperature THW as parameters as shown in FIG.
The correction amount Aexb is calculated based on the map by providing a plurality of sheets in accordance with the opening degree of the second. Separately, a correction coefficient corresponding to the opening degree of the exhaust throttle valve 32 is obtained, and the correction coefficient and the correction amount Aex
The injection timing may be corrected using a value multiplied by b.
The opening of the exhaust throttle valve 32 may use a set value calculated by the ECU 90, or may use a detection value of an opening sensor that detects the opening of the exhaust throttle valve 32.

In the above embodiment, the injection timing is corrected based on the control flag set when the exhaust brake condition or the heater idle-up condition is satisfied. However, the present invention is not limited to this. For example, an opening sensor that detects the opening of the exhaust throttle valve 32 may be provided, and the injection timing may be corrected based on the detected opening of the exhaust throttle valve 32. In this case, if the opening degree of the exhaust throttle valve 32 is small, the correction of the basic injection timing is performed, and if the opening degree of the exhaust throttle valve 32 is large, the correction of the basic injection timing is not performed.

In the above embodiment, the correction amount Aexb is obtained using the engine speed NE and the engine coolant temperature THW as operating conditions as parameters, but the present invention is not limited to this. For example, since the fuel injection amount changes depending on the intake air temperature and intake air pressure, the intake air temperature and intake air pressure may be used as the operating conditions. That is, the correction amount Aexb may be obtained using the intake air temperature and the intake air pressure as parameters. Further, for example, in a configuration in which the opening degree of the exhaust throttle valve 32 is adjusted based on a vehicle speed or the like as an operating condition,
Since the internal EGR amount changes according to the opening degree of the exhaust throttle valve 32, the correction amount Aexb may be calculated using the vehicle speed and the like as parameters.

In the process of step 230 shown in FIG. 5, the engine speed NE is increased to a predetermined speed (eg, 120
If the rotation speed is larger than 0 rpm), the flow goes to step 250 to set the correction amount Aexb = 0.
As in the above-described embodiment, the correction amount Aexb may be calculated using a map shown in FIG. 6A using the engine speed NE and the water temperature THW as parameters. By doing so, the processing load performed by the ECU 90 can be reduced.
That is, the processing load can be reduced on the high engine speed NE side where the processing load of the ECU 90 becomes relatively high, which is practically preferable.

In the above embodiment, the engine speed N
Although the basic injection timing Abase is calculated from a two-dimensional map based on E and the final injection amount Qfin, the fuel is calculated based on the basic injection timing Abase calculated using the engine speed NE, accelerator depression amount, cooling water temperature, and the like as parameters. May be corrected. In the case of a diesel engine, the fuel injection amount is obtained from these parameters (engine speed NE, accelerator depression amount, cooling water temperature, etc.), and thus the basic injection timing Aba in this case.
“se” is also a value corresponding to the fuel injection amount.

In the above-described embodiment, the fuel injection timing is corrected even when the exhaust throttle valve 32 is operated to the valve closing side in order to promote warm-up. You may. That is, the present fuel injection control device only needs to correct the fuel injection timing at the time of operating the exhaust brake. Specifically, step 22 shown in FIG.
The processing of steps 0 and 240 is omitted.

In the above embodiment, the exhaust throttle valve 32 as exhaust throttle means is configured to be closed when the engine 10 is stopped. May be used.

Further, technical ideas other than the claims grasped from the above embodiment will be described below together with their effects. 5. The fuel injection control device for a diesel engine according to claim 4, wherein the fuel injection timing is corrected to be advanced as the cooling water temperature increases. 6. As the water temperature THW increases, the ignition delay of the injected fuel is more likely to occur. However, according to this configuration, the fuel injection timing is corrected to the advanced side as the cooling water temperature increases, so that the ignition delay of the injected fuel can be accurately adjusted. Can be prevented.

[0073]

According to the first aspect of the present invention, when the exhaust brake is operated, the fuel injection timing is advanced according to the operating conditions at each time, and the combustion of the injected fuel is promoted. Can be reduced.

According to the second aspect of the present invention, since the fuel injection timing is corrected based on the engine cooling water temperature and the engine speed, the smoke can be reduced accurately. According to the third aspect of the present invention, when the engine speed is equal to or higher than the predetermined speed at the time of vehicle deceleration, smoke is not discharged even if the fuel injection timing is not corrected, and the advance correction of the basic injection timing is stopped. Therefore, unnecessary correction is eliminated, which is preferable in practical use.

According to the fourth aspect of the present invention, the injection timing is corrected when the exhaust throttle means is operated to promote the warm-up of the engine, so that the warm-up of the engine accompanying the rise of the exhaust gas temperature is promoted. And smoke reduction can be achieved at the same time.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a diesel engine according to an embodiment.

FIG. 2 is a sectional view showing a specific configuration example of a fuel injection pump.

FIG. 3 is a sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is a flowchart showing a fuel injection amount calculation process.

FIG. 5 is a flowchart showing a fuel injection timing calculation process.

FIG. 6A is a diagram illustrating a relationship between an engine speed, a water temperature, and a correction amount, and FIG. 6B is a diagram illustrating a relationship between a water temperature and a correction amount.

[Explanation of symbols]

Reference Signs List 10 diesel engine, 12 combustion chamber, 17 fuel injection nozzle constituting combustion injection means, 18 fuel line constituting combustion injection means, 20 injection pump constituting combustion injection means, 32 exhaust discharge means Exhaust throttle valve, 90 ... ECU.

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme coat (reference) F02D 43/00 301 F02D 43/00 301J 301K (72) Inventor Sai Sai Fuji ▼ Kiyoshi 2-1-1 Toyota-cho, Kariya City, Aichi Prefecture Address F-term in Toyota Industries Corporation (reference) 3G060 AB04 AC10 BB09 BB14 BC06 CA01 CA02 CB03 CB05 CC01 CC08 DA01 GA03 GA04 GA07 GA20 3G065 AA01 AA09 CA12 DA02 DA07 EA02 EA03 EA05 GA00 GA09 GA10 GA11 GA06 3 DA10 EA11 EB24 EC02 EC03 FA00 FA13 FA20 FA33 3G301 HA02 JA11 JA26 KA05 KA06 KA07 KA16 KA23 KB00 LB11 LB16 LB19 LC01 MA11 MA18 MA24 NA06 NA08 NB06 NB11 NC02 NE01 NE11 PA07Z PA10Z PB03Z PD00 PE01ZPE08Z

Claims (4)

[Claims] 1. A fuel injection device for injecting fuel into a vehicle-mounted diesel engine, the fuel injection device controlling fuel injection timing by the fuel injection device based on a basic injection timing corresponding to an engine speed and a fuel injection amount. In the control device, exhaust throttle means provided in the exhaust passage to increase the flow path resistance of the exhaust, and when the exhaust throttle means is operated at the time of deceleration of the vehicle, the fuel injection timing is adjusted for each engine. A fuel injection control device for a diesel engine, comprising: deceleration correction means for advancing from the basic injection timing based on operating conditions. 2. The fuel injection control device for a diesel engine according to claim 1, wherein the operating conditions are an engine speed and a temperature of engine cooling water. 3. The fuel injection control device according to claim 1, wherein fuel injection is limited when the engine speed is equal to or higher than a predetermined engine speed when the vehicle is decelerated. When it is over,
3. The fuel injection control device for a diesel engine according to claim 1, wherein the advance correction of the basic injection timing by the deceleration correction unit is stopped. 4. 4. When the exhaust throttle means is operated in a vehicle stopped state in order to promote warming of the engine, a warm-up operation for changing the injection timing with respect to the basic injection timing based on the warm-up state of the engine at each time. 2. The fuel injection control device for a diesel engine according to claim 1, further comprising an on-time correction unit.