JPH05149176A - Fuel injection amount control device for diesel engine - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the occurrence of smoke and suppress the occurrence of torque shock when the exhaust throttle is released. In the supercharged diesel engine 2, when the operation of the exhaust throttle valve 64 provided in the exhaust pipe 48 is released, the ECU 71 sets the fuel injection amount supplied from the fuel injection pump 1 to the maximum injection amount. Control based on. At this time, the maximum injection amount is first reduced by the ECU 71 by a predetermined amount. After that, the maximum injection amount is changed so that the reduction amount is gradually decreased until a predetermined time elapses. Therefore, the maximum injection amount decreases until a predetermined time elapses, and incomplete combustion of fuel is suppressed. Further, the predetermined time is always a constant value, and there is no excess or deficiency in the weight reduction period.
Further, the fuel injection amount is smoothly increased according to the degree of release of the exhaust throttle valve 64. Therefore, the fuel injection amount does not suddenly increase immediately after the release of the exhaust throttle mechanism is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is suitable for use in, for example, an electronically controlled diesel engine equipped with a fuel injection pump, and shows the amount of fuel injected from the fuel injection pump when the accelerator pedal is depressed from the exhaust throttle operating state. The present invention relates to a fuel injection amount control device for a diesel engine that is controlled.

[0002]

2. Description of the Related Art Conventionally, an exhaust throttle may be operated at the time of starting a diesel engine to promote warming up. However, during the warm-up operation with the exhaust throttle activated in this way, when the accelerator pedal is depressed to increase the amount of fuel from the fuel injection pump in order to increase the engine speed, the exhaust throttle becomes There was a risk that the injection amount would be increased before it was completely opened. As a result, there is a possibility that incomplete combustion of the fuel may be caused and smoke may be generated more frequently.

Therefore, a technique for solving the above-mentioned problems has been proposed, for example, in Japanese Utility Model Laid-Open No. 55-165834. In this technique, an operation delay device is provided between the accelerator pedal and a control lever that controls the injection amount from the fuel injection pump in association with the pedal. When the accelerator pedal is depressed during the operation of the exhaust throttle, the release of the exhaust throttle is immediately started, and the operation delay device delays the fuel injection amount increasing timing until the predetermined accelerator opening degree is reached. With this configuration, the fuel injection amount is increased after the exhaust throttle is released, and the generation of smoke due to the delay in releasing the exhaust throttle is reduced.

[0004]

However, when the operation delay device in the technique of the above-mentioned conventional publication is used, due to its structural reason, the time for delaying the fuel injection according to the depression speed of the accelerator pedal is delayed. It was different. That is, if you slowly depress the accelerator pedal,
The delay time became longer, and when the accelerator pedal was suddenly depressed, the delay time was shortened. Therefore, when the delay time is too long, the fuel injection amount is not increased even though the exhaust throttle has already been released, which causes a problem of impairing drivability. On the other hand, when a sufficient delay time cannot be secured, the injection amount is increased in a state where the exhaust throttle is not released, which causes a problem similar to the conventional one that smoke is increased.

On the other hand, it may be considered that the fuel injection timing is simply delayed by controlling the delay time. However, in this case, when the accelerator depression amount (accelerator opening degree) becomes too large during a certain period of time, the fuel injection amount is rapidly increased after the end of the delay, and the torque shock becomes large.
There was a risk of impairing drivability.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to reduce the generation of smoke and suppress the generation of torque shock when the exhaust throttle is released. Another object of the present invention is to provide a fuel injection amount control device for a diesel engine capable of controlling the fuel injection amount.

[0007]

In order to achieve the above object, in the present invention, as shown in FIG. 1, fuel injection means M2 for injecting fuel into a diesel engine M1.
And an exhaust throttle mechanism M which is provided in the exhaust passage M3 of the diesel engine M1 and is operated to perform exhaust throttle.
4 and an operating state detecting means M5 for detecting an operating state including the rotational speed and the accelerator opening degree of the diesel engine M1;
Exhaust throttle control means M6 for controlling the operation and release of the exhaust throttle mechanism M4 based on the detection result of the operating state detection means M5.
And a maximum injection amount calculation means M7 for calculating a maximum injection amount corresponding to the engine speed based on the detection result of the operating state detection means M5 when the exhaust throttle control means M6 releases the exhaust throttle mechanism M4. In a fuel injection amount control device for a diesel engine, which includes an injection control unit M8 that drives and controls the fuel injection unit M2 based on the calculation result of the maximum injection amount calculation unit M7, the exhaust throttle mechanism M4 is released by the exhaust throttle control unit M6. At this time, the maximum injection amount calculated by the maximum injection amount calculating means M7 is first reduced by a predetermined amount, and then the maximum reduction amount is gradually decreased until a predetermined time elapses. The maximum injection amount changing means M9 for changing the injection amount is provided.

[0008]

According to the above construction, as shown in FIG. 1, the operating state detecting means M5 is operated while the diesel engine M1 is operating.
Detects operating conditions including engine speed and accelerator opening. The exhaust throttle control unit M6 controls the operation and release of the exhaust throttle mechanism M4 provided in the exhaust passage M3 based on the detection result of the operating state detection unit M5.

Then, when the operation of the exhaust throttle mechanism M4 is canceled by the exhaust throttle control means M6, the maximum injection amount calculation means M7 calculates the maximum injection amount corresponding to the engine speed. At this time, the maximum injection amount changing means M9 first reduces the maximum injection amount by a predetermined amount, and then changes the maximum injection amount so that the reduction value gradually decreases until a predetermined time elapses. .. Then, based on the maximum injection amount thus changed, the injection control means M8 drive-controls the fuel injection means M2 to control the fuel injection amount.

Therefore, since the time required from the start of the deactivation of the exhaust throttle mechanism M4 to the completion thereof is constant at a predetermined time, the reduction period of the maximum injection amount is determined without excess or deficiency, and the fuel is incomplete. Combustion is suppressed.

Further, since the reduction value reduced by the predetermined amount by the maximum injection amount changing means M9 is gradually reduced,
The fuel injection amount is increased according to the degree of deactivation of the exhaust throttle mechanism M4. Therefore, the fuel injection amount does not suddenly increase immediately after the release of the exhaust throttle mechanism M4 is completed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a fuel injection amount control device for a diesel engine according to the present invention is embodied in an automobile will be described below in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a fuel injection timing control device for a diesel engine with a supercharger in this embodiment, and FIG. 3 is a sectional view showing the distribution type fuel injection pump 1. A fuel injection pump 1 as a fuel injection means includes a drive pulley 3 drivingly connected to a crankshaft 40 of a diesel engine 2 via a belt or the like. Then, the fuel injection pump 1 is driven by the rotation of the drive pulley 3, and the fuel is pressure-fed to each fuel injection nozzle 4 provided for each cylinder (four cylinders in this case) of the diesel engine 2 to perform fuel injection. ..

In the fuel injection pump 1, the drive pulley 3 is attached to the tip of the drive shaft 5.
Further, a fuel feed pump (developed by 90 degrees in this figure) 6 which is a vane type pump is provided in the middle of the drive shaft 5. Further, a disc-shaped pulsar 7 is attached to the base end side of the drive shaft 5. The diesel engine 2 is attached to the outer peripheral surface of the pulsar 7.
The same number as the number of cylinders, that is, in this case, four cutting teeth are formed at equal angular intervals, and 14 projections (56 in total) are formed at equal angular intervals between each cutting tooth. There is. The base end of the drive shaft 5 is connected to the cam plate 8 via a coupling (not shown).

A roller ring 9 is provided between the pulsar 7 and the cam plate 8, and a plurality of cam rollers 10 facing the cam face 8a of the cam plate 8 are attached along the circumference of the roller ring 9. There is. Cam face 8
The number a is provided in the same number as the number of cylinders of the diesel engine 2. The cam plate 8 is constantly urged and engaged with the cam roller 10 by the spring 11.

A base end of a fuel pressurizing plunger 12 is integrally rotatably attached to the cam plate 8, and the cam plate 8 and the plunger 12 are rotated in association with the rotation of the drive shaft 5. That is, when the rotational force of the drive shaft 5 is transmitted to the cam plate 8 via a coupling (not shown), the cam plate 8 is engaged with the cam roller 10 while rotating, and the same number as the number of cylinders in the left-right direction in the drawing is obtained. Is driven back and forth. In addition, the plunger 12 is reciprocally driven in the same direction while rotating with the reciprocating motion. That is, the plunger 12 is moved forward (lifted) while the cam face 8a of the cam plate 8 rides on the cam roller 10 of the roller ring 9, and vice versa.
2 is reactivated.

The plunger 12 is fitted into a cylinder 14 formed in the pump housing 13, and a high pressure chamber 15 is provided between the tip end surface of the plunger 12 and the bottom surface of the cylinder 14.
Has become. Also, on the outer periphery of the tip end side of the plunger 12,
The same number of intake grooves 16 and distribution ports 17 as the number of cylinders of the diesel engine 2 are formed. Also, those suction grooves 16
And the pump housing 13 corresponding to the distribution port 17.
A distribution passage 18 and a suction port 19 are formed therein.

Then, the drive shaft 5 is rotated to drive the fuel feed pump 6, whereby fuel is supplied from a fuel tank (not shown) into the fuel chamber 21 through the fuel supply port 20. Further, during the suction stroke in which the plunger 12 is returned and the high pressure chamber 15 is depressurized, the suction groove 1
The fuel is introduced from the fuel chamber 21 into the high-pressure chamber 15 by communicating one of the six with the suction port 19. On the other hand, during the compression stroke in which the plunger 12 is moved forward and the high-pressure chamber 15 is pressurized, fuel is pressure-fed and injected from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder.

A spill passage 22 for fuel overflow (spill) is formed in the pump housing 13 to connect the high pressure chamber 15 and the fuel chamber 21. An electromagnetic spill valve 23 for adjusting the fuel spill from the high pressure chamber 15 is provided in the middle of the spill passage 22. The electromagnetic spill valve 23 is a normally open type valve, and the valve body 25 is opened to spill the fuel in the high pressure chamber 15 to the fuel chamber 21 when the coil 24 is not energized (OFF). When the coil 24 is energized (turned on), the valve body 25 is closed and the spill of fuel from the high pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, by controlling the energizing time of the electromagnetic spill valve 23, the valve 23 is controlled to be closed / opened, and spill metering of fuel from the high pressure chamber 15 to the fuel chamber 21 is performed. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the fuel inside the high pressure chamber 15 is depressurized and the fuel injection from the fuel injection nozzle 4 is stopped. That is, even if the plunger 12 moves forward, the fuel pressure in the high-pressure chamber 15 does not rise while the electromagnetic spill valve 23 is open, and fuel injection from the fuel injection nozzle 4 is not performed. Further, the amount of fuel injection from the fuel injection nozzle 4 is controlled by controlling the closing / opening timing of the electromagnetic spill valve 23 during the forward movement of the plunger 12.

Below the pump housing 13, there is provided a timer device (which is expanded 90 degrees in this figure) 26 for controlling the fuel injection timing. The timer device 26 changes the position of the roller ring 9 with respect to the rotation direction of the drive shaft 5 to change the timing at which the cam face 8a engages with the cam roller 10, that is, the reciprocating drive timing of the cam plate 8 and the plunger 12. It is for.

The timer device 26 is hydraulically driven, and includes a timer housing 27, a timer piston 28 fitted in the housing 27, and a timer in a low pressure chamber 29 on one side of the timer housing 27. It is composed of a timer spring 31 and the like for urging the piston 28 against the pressurizing chamber 30 on the other side. The timer piston 28 is connected to the roller ring 9 via the slide pin 32.

In the pressurizing chamber 30 of the timer housing 27,
The fuel pressurized by the fuel feed pump 6 is introduced. Then, the position of the timer piston 28 (hereinafter referred to as "timer piston position") is determined by the equilibrium relationship between the fuel pressure and the urging force of the timer spring 31. Further, by determining the timer piston position, the position of the roller ring 9 is determined, and the reciprocating timing of the plunger 12 via the cam plate 8 is determined.

The timer device 26 is provided with a timer control valve (TCV) 33 in order to adjust the fuel pressure acting as the hydraulic pressure of the timer device 26. That is, the pressurizing chamber 30 and the low pressure chamber 29 of the timer housing 27 are communicated with each other by the communication passage 34, and the TCV 3 is provided in the middle of the communication passage 34.
3 is provided. The TCV 33 is an electromagnetic valve that is opened / closed by a duty-controlled energization signal, and the fuel pressure in the pressurizing chamber 30 is adjusted by the opening / closing control of the TCV 33. Then, by adjusting the fuel pressure, the lift timing of the plunger 12 is controlled,
The fuel injection timing from each fuel injection nozzle 4 is controlled.

A rotation speed sensor 35 composed of an electromagnetic pickup coil is mounted above the roller ring 9 so as to face the outer peripheral surface of the pulsar 7. This rotation speed sensor 35
When the protrusions and the like of the pulsar 7 cross each other, they detect their passage and output a timing signal (engine rotation pulse) corresponding to the engine speed NE. Further, since this rotation speed sensor 35 is integrated with the roller ring 9, it outputs a reference timing signal to the plunger lift at a constant timing regardless of the control operation of the timer device 26.

Next, the diesel engine 2 will be described. In the diesel engine 2, a main combustion chamber 44 corresponding to each cylinder is formed by the cylinder 41, the piston 42, and the cylinder head 43. or,
A sub combustion chamber 45 communicating with each of the main combustion chambers 44 is provided for each cylinder. And each auxiliary combustion chamber 45
Is supplied with fuel injected from each fuel injection nozzle 4. A well-known glow plug 46 as a start-up assist device is attached to each sub-combustion chamber 45.

The diesel engine 2 is provided with an intake pipe 47 and an exhaust pipe 48 as an exhaust passage, and the intake pipe 47 has a turbocharger 4 constituting a supercharger.
9 is provided with a compressor 50, and the exhaust pipe 48 is provided with a turbine 51 of a turbocharger 49.
Further, the exhaust pipe 48 is provided with a waste gate valve 52 for adjusting the supercharging pressure PiM. As is well known, the turbocharger 49 uses the energy of exhaust gas to rotate the turbine 51, and rotates the compressor 50 coaxially with the turbine 51 to pressurize intake air. Due to this action, high-density air is sent to the main combustion chamber 44 to burn a large amount of fuel, and the output of the diesel engine 2 is increased.

The diesel engine 2 has an exhaust pipe 4
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in 8 to the intake port 53 of the intake pipe 47. An exhaust gas recirculation valve (EGR valve) 55 for adjusting the amount of exhaust gas recirculation is provided in the middle of the recirculation pipe 54. The EGR valve 55 is controlled to open / close under the control of a vacuum switching valve (VSV) 56.

Further, in the middle of the intake pipe 47, there is provided a throttle valve 58 which is opened / closed in association with the depression amount of the accelerator pedal 57. Also, the throttle valve 5
A bypass passage 59 is provided in parallel with 8, and a bypass throttle valve 60 is provided in the bypass passage 59. The bypass throttle valve 60 is controlled to be opened / closed by an actuator 63 having a two-stage diaphragm chamber driven by the control of two VSVs 61 and 62. The bypass throttle valve 60 is controlled to open and close according to various operating states. For example, during idle operation, it is controlled to a half-open state to reduce noise and vibrations, during normal operation it is controlled to a fully open state, and when operation is stopped, it is controlled to a fully closed state for a smooth stop.

An exhaust throttle valve 64 for closing the exhaust passage is provided in the middle of the exhaust pipe 48 in order to warm up the diesel engine 2. Further, a diaphragm type exhaust throttle actuator 65 is provided to open and close the exhaust throttle valve 64, and a rod 66 thereof is connected to the exhaust throttle valve 64 via a link 67. The exhaust throttle actuator 65 operates by the introduction of negative pressure, and is connected to the exhaust throttle VSV 69 via a negative pressure passage 68. The exhaust throttle valve 64, the exhaust throttle actuator 65, the exhaust throttle VSV69, and the like constitute an exhaust throttle mechanism. When the exhaust throttle VSV69 is turned on and opened, a vacuum pump (not shown) drives the exhaust throttle actuator. Negative pressure is introduced into 65, the rod 66 contracts, and the exhaust throttle valve 64 is closed. That is, exhaust throttling is performed.

The electromagnetic spill valve 2 provided on the fuel injection pump 1 and the diesel engine 2 as described above.
3, TCV33, glow plug 46 and each VSV56,
Reference numerals 61, 62 and 69 are electrically connected to an electronic control unit (hereinafter simply referred to as “ECU”) 71 that constitutes an exhaust throttle control unit, a maximum injection amount calculation unit, an injection control unit and a maximum injection amount change unit, The ECU 71 controls the drive timings thereof.

As the sensors constituting the operating condition detecting means of the diesel engine 2, the following various sensors are provided in addition to the rotation speed sensor 35. That is, the intake pipe 47
An intake air temperature sensor 72 for detecting the intake air temperature THA is provided near the air cleaner 70 provided at the inlet of the. Further, from the opening / closing position of the throttle valve 58, the accelerator opening ACCP corresponding to the load of the diesel engine 2
An accelerator opening sensor 73 is provided to detect the.
An intake pressure sensor 74 that detects the intake air pressure after supercharging by the turbocharger 49, that is, the supercharging pressure PiM is provided near the intake port 53. Further, a water temperature sensor 75 for detecting the cooling water temperature THW of the diesel engine 2 is provided. Further, a crank angle sensor 76 for detecting a rotation reference position of the crankshaft 40, for example, a rotation position of the crankshaft 40 with respect to a top dead center of a specific cylinder is provided. Furthermore, a transmission (not shown) has a magnet 77a rotated by the rotation of its gear.
A vehicle speed sensor 77 for detecting the vehicle speed (vehicle speed) SP by turning on / off the reed switch 77b is provided.

The above-mentioned sensors 72 to 77 are respectively connected to the ECU 71, and the rotation speed sensor 3 is connected.
5 is connected. Further, the ECU 71 uses the sensors 35,
Based on the detection signals output from 72 to 77, the electromagnetic spill valve 23, the TCV 33, the glow plug 46 and the VSV 5
6, 61, 62, 69 and the like are preferably controlled.

Next, the configuration of the above-mentioned ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 is a central processing unit (CPU) 81, a read-only memory (RO) in which a predetermined control program, maps and the like are stored in advance.
M) 82, a random access memory (RAM) 83 for temporarily storing calculation results of the CPU 81, a backup RAM 84 for storing prestored data, and the like, and a bus 87 for connecting these units, an input port 85, an output port 86, and the like.
It is configured as a logical operation circuit connected by.

At the input port 85, the intake air temperature sensor 72, the accelerator opening sensor 73, the intake air pressure sensor 74 and the water temperature sensor 75 are connected to the buffers 88, 89, 90 and 9, respectively.
1, the multiplexer 93, and the A / D converter 94. Similarly, the rotation speed sensor 35, the crank angle sensor 76, and the vehicle speed sensor 77 described above are connected to the input port 85 via a waveform shaping circuit 95. Then, the CPU 81 reads the detection signals of the sensors 35, 72 to 77, etc., which are input via the input port 85, as input values. Further, each drive circuit 9 is connected to the output port 86.
The electromagnetic spill valve 23, the TCV 33, the glow plug 46, the VSV 56, 61, 62, 69, etc. are connected via 6, 97, 98, 99, 100, 101, 102.

Then, the CPU 81 controls the sensors 35 and 72.
Electromagnetic spill valve 2 based on input values read from ~ 77
3, TCV33, glow plug 46 and VSV56,6
1, 62, 69 etc. are suitably controlled.

Next, the processing operation of the fuel injection amount control executed by the above-mentioned ECU 71 will be described with reference to FIGS. The flow chart shown in FIGS.
1 is a process routine for controlling the fuel injection amount in the fuel injection pump 1 among the processes executed by 1.
It is executed by a regular interrupt every predetermined time. It should be noted that this flowchart describes only the processing at the time of starting the diesel engine 2. Further, at the time of this starting, the operation of the exhaust throttle is started in a separate routine.

When the processing shifts to this routine, first, at step 101, the engine speed N is detected from the detection means such as the rotation speed sensor 35 and the accelerator opening sensor 73.
E, the accelerator opening ACCP, etc. are read respectively, and the exhaust throttle release initialization flag F is read. The exhaust throttle release initialization flag F is processed in a separate routine, and is set to "1" when the operation of the exhaust throttle is started.

Next, at step 102, the basic fuel injection amount QBASE is calculated. This basic injection amount QBA
The SE is calculated based on the engine speed NE, the accelerator opening ACCP, and the like that have been read in advance. That is,
The basic injection amount QBASE is calculated with reference to a predetermined map having the engine speed NE, the accelerator opening ACCP, etc. as parameters. Further, when calculating the basic injection amount QBASE, the cooling water temperature THW, the accelerator opening ACCP, and the engine speed NE are as necessary.
Based on each value such as, the low temperature start increase correction, the acceleration increase correction, the deceleration increase correction, and the like are performed.

Next, at step 103, it is judged whether or not the present state is the idling state based on the accelerator opening ACCP previously read. Then, if the current state is the idling state, the process proceeds to step 104.

In step 104, the idle injection amount QIDLE is calculated. This idle injection amount QIDL
E is calculated based on a predetermined reference value and is appropriately corrected according to the temperature and the like at that time. Then, in the next step 105, the idle injection amount QI
DLE is set as the final injection amount QFIN.

Subsequently, at step 106, an injection amount command value VSSP corresponding to the final injection amount QFIN is obtained. Then, in step 107, the calculated injection amount command value VSSP is output, that is, the basic injection amount Q
The electromagnetic spill valve 23 is drive-controlled based on the injection amount command value VSSP corresponding to BASE, and the subsequent processing is once ended.

On the other hand, if it is determined in step 103 that the current state is not idling, the exhaust throttle VSV 69 is turned off in the next step 108 to turn off the exhaust throttle valve 64.
Open and release the exhaust throttle.

Then, in step 109, it is judged whether or not the exhaust throttle release initialization flag F read in step 101 is "1". Then, when the exhaust throttle release initialization flag F is not "1", it is assumed that the exhaust throttle release has been started, and the routine proceeds to step 113 described later. Further, when the exhaust throttle release initialization flag F is "1", it is assumed that the exhaust throttle release is started, and in step 110, the count value C for counting the predetermined time T is set to "0". Reset to.

Next, at step 111, the exhaust throttle coefficient K is set to an initial value α (where 0 <α <1). That is, the exhaust throttle coefficient K is set to the initial value α at the same time when the release of the exhaust throttle is started, as shown in the preset map of FIG. 7. The exhaust throttling coefficient K is a value that is gradually increased to "1" after the initial value α is set and before the predetermined time T elapses. However, the predetermined time T is theoretically or experimentally obtained in advance as the time from the start of the release of the exhaust throttle to the completion thereof.
Further, at step 112, the exhaust throttle release initialization flag F is reset to "0", and the routine proceeds to the next step 113.

Then, in step 113 after shifting from step 109 or step 112, it is judged whether or not the exhaust throttle coefficient K is "1". Then, when the exhaust throttle coefficient K is "1", it is assumed that the predetermined time T has already passed and the release of the exhaust throttle has been completed, and the routine proceeds to step 116 described later.

If the exhaust throttle coefficient K is not "1", it is determined that the exhaust throttle has not been released because the predetermined time T has not yet elapsed and the routine proceeds to step 114. Then, in step 114, the exhaust throttling coefficient K corresponding to the elapsed time is calculated with reference to the map of FIG. 7 based on the count value C. Further, in step 115, only "1" is added to the count value C of the counter to set it as a new count value C, and the process proceeds to the next step 116.

Then, step 113 or step 11
In step 116 after shifting from 5, the maximum injection amount QFU is determined based on the engine speed NE and the exhaust throttle coefficient K.
Calculate LL. At this time, this maximum injection amount QFULL
Is based on the engine speed NE, as shown in FIG. 8, with the engine speed NE as a parameter, and the full load injection amount QM.
The relationship of AX is obtained by referring to a predetermined map to obtain the full load injection amount QMAX, and multiplying the full load injection amount QMAX by the exhaust throttle coefficient K.

Thereafter, in step 117, it is determined whether the basic injection amount QBASE calculated in the previous step 102 is smaller than the maximum injection amount QFULL calculated in step 116.

If the basic injection amount QBASE is smaller than the maximum injection amount QFULL, then in step 118 the basic injection amount QBASE is set as the final injection amount QFIN. Then, in step 106, the injection amount command value VSSP corresponding to the final injection amount QFIN is obtained.
Then, in step 107, the calculated injection amount command value VSSP is output, that is, the basic injection amount QBAS.
The electromagnetic spill valve 23 is driven and controlled based on the injection amount command value VSSP corresponding to E, and the subsequent processing is once ended.

If the basic injection amount QBASE is larger than the maximum injection amount QFULL in step 117, the maximum injection amount QFULL in step 119.
Is the final injection amount QFIN. Then, step 106
At, the injection amount command value VSSP corresponding to the final injection amount QFIN is obtained. Then, in step 107, the calculated injection amount command value VSSP is output, that is, the injection amount command value VS corresponding to the maximum injection amount QFULL.
The electromagnetic spill valve 23 is drive-controlled based on SP, and the subsequent processing is once ended.

As described above, the fuel injection amount control at the time of starting is executed. As described above, according to the fuel injection amount control device of this embodiment, after the predetermined time T has elapsed, the maximum injection amount QFULL is calculated with reference to the map of FIG. Until the time T elapses, the full-load injection amount QMAX obtained from the map of FIG. 8 is multiplied by the exhaust throttle coefficient K to be calculated. Therefore, the maximum injection amount QFULL becomes smaller than after the elapse of the predetermined time T until the elapse of the predetermined time T from the start of the release of the exhaust throttle, that is, until the release of the exhaust throttle is completed. Therefore, the fuel is not excessively supplied to the diesel engine 2 until the exhaust throttle is completely released, incomplete combustion of the fuel is suppressed, and the generation of smoke can be reduced.

Further, in this embodiment, the predetermined time T is the time from the start of the release of the exhaust throttle until the reduction value of the maximum injection amount QFULL becomes zero, and it is always a constant time. Therefore, the maximum injection amount QFULL There is no excess or deficiency in the period during which the amount is reduced. Therefore, even if there is a difference in the depression speed of the accelerator pedal 57, the driveability is impaired due to a torque shock or the like due to the difference in speed, and the occurrence of smoke due to incomplete combustion is increased. can do.

Further, in this embodiment, at the same time when the release of the exhaust throttle is started, the reduction value obtained by reducing the maximum injection amount QFULL by a predetermined amount is gradually reduced. Accordingly, the fuel injection amount is smoothly increased. Therefore, the fuel injection amount does not suddenly increase immediately after the exhaust throttle release is completed, and it is possible to prevent the occurrence of the torque shock due to the rapid increase in the fuel injection amount.

As described above, in this embodiment, when the exhaust throttle is released, it is possible to reduce the occurrence of smoke and suppress the occurrence of torque shock and the like.
The present invention is not limited to the above embodiment,
A part of the configuration may be modified as appropriate without departing from the spirit of the invention, and the present invention may be implemented as follows.

(1) In the above embodiment, as shown in FIG. 7, the exhaust throttle coefficient K reduced to the initial value α is linearly increased in proportion to the elapsed time at the same time when the exhaust throttle is started. However, the way of increasing the exhaust throttle coefficient K may be curved.

(2) In the above embodiment, the diesel engine 2 having the turbocharger 49 as the supercharger is embodied, but the diesel engine having the supercharger as the supercharger and the supercharger are provided. It can also be embodied in not a diesel engine.

(3) In the above embodiment, the exhaust throttle for promoting warm-up has been described, but it may be embodied in a diesel engine equipped with an exhaust brake using the exhaust throttle released by depressing the accelerator pedal.

[0059]

As described above in detail, according to the present invention, when the operation of the exhaust throttle mechanism is released, the maximum injection amount is first reduced by a predetermined amount, and then a predetermined time elapses. Since the maximum injection amount is changed so as to gradually reduce the reduction amount during the period, it is possible to reduce smoke and suppress torque shock. ..

[Brief description of drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic configuration diagram showing a fuel injection amount control device for a diesel engine with a supercharger in one embodiment embodying the present invention.

FIG. 3 is a sectional view showing a distributed fuel injection pump in one embodiment.

FIG. 4 is a block diagram showing a configuration of an ECU and the like in one embodiment.

FIG. 5 is a flowchart illustrating a processing routine for fuel injection amount control in one embodiment.

FIG. 6 is a flowchart illustrating a continuation of a processing routine for fuel injection amount control in one embodiment.

FIG. 7 is a map showing a relationship of an exhaust throttling coefficient with respect to a count value of a predetermined time in one embodiment.

FIG. 8 is a map showing a relationship between a predetermined full load injection amount and an engine speed in one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump as fuel injection means, 2 ... Diesel engine, 35 ... Rotation speed sensor as operating state detection means, 48 ... Exhaust pipe as exhaust passage, 64 ... Exhaust throttle valve, 65 ... Exhaust throttle actuator, 69 ... Exhaust throttling VSV (64, 65, 69 constitute an exhaust throttling mechanism), 71 ... ECU constituting exhaust throttling control means, maximum injection amount calculation means, injection amount control means and maximum injection amount changing means , 73 ... An accelerator opening sensor as an operating state detecting means.

Claims (1)

[Claims] 1. A fuel injection means for injecting fuel to a diesel engine, an exhaust throttle mechanism provided in the exhaust passage of the diesel engine for operating to throttle the exhaust, a rotational speed of the diesel engine and an accelerator opening. The operating state detecting means for detecting the operating state including the exhaust rate, the exhaust throttle controlling means for controlling the operation and release of the exhaust throttle mechanism based on the detection result of the operating state detecting means, and the exhaust by the exhaust throttle controlling means. A maximum injection amount calculation unit that calculates a maximum injection amount corresponding to an engine speed based on a detection result of the operating state detection unit when the throttle mechanism is released; and a calculation result of the maximum injection amount calculation unit. A fuel injection amount control device for a diesel engine, comprising: When the exhaust throttle mechanism is released by the throttle control unit, the maximum injection amount calculated by the maximum injection amount calculation unit is first reduced by a predetermined amount, and then a predetermined time period elapses. A fuel injection amount control device for a diesel engine, comprising a maximum injection amount changing means for changing the maximum injection amount so as to gradually decrease the amount of decrease.