JPH04362250A - Fuel injection amount controller of diesel engine - Google Patents

Abstract

PURPOSE:To prevent increase of smoke due to unnecessary increase of a fuel injection amount while maintaining engine failure prevention function. CONSTITUTION:Fuel injection into a diesel engine 2 is controlled by computing the required amount of fuel injection which corresponds to the operation condition of the diesel engine 2 with ECU71 and driving and controlling a fuel injection pump 1. When the number of revolutions of engine is smaller than the predetermined small number of revolutions, the result of computation of the amount of fuel injection with ECU71 is compensated by the increased amount. When the result of detection of a car speed sensor 77 is higher than the predetermined low car speed, compensation of the increased amount of fuel injection with ECU71 is restricted (inhibited). Thus, engine breakdown is prevented by the compensation of the increased amount of fuel injection when the diesel engine 2 rotates at a low speed. Also, when car speed is higher than the predetermined low car speed, the compensation of the increased amount is restricted and unnecessary incerase of the amount of fuel injection is not done, even if the number of revolutions of the diesel engine 2 becomes small.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine applied to, for example, an automobile, and more particularly to a fuel injection amount control device for a diesel engine that controls the number of idle revolutions.

0002

BACKGROUND OF THE INVENTION Various proposals have been made regarding fuel injection amount control for electronically controlled diesel engines. A method is disclosed. That is, in the technique disclosed in this publication, when the engine speed becomes higher than a predetermined idle speed, the idle stability is improved by reducing the fuel injection amount. Furthermore, when the engine speed falls below a predetermined idle speed, the fuel injection amount is rapidly increased to prevent engine stalling. Regarding engine stall prevention, the most severe condition is when the power steering is turned off near the idle speed, as the engine load increases rapidly.
Considering the prevention of est in that case, a considerably large increase in weight is required.

0003

[Problem to be Solved by the Invention] However, when the technology of the above-mentioned prior publication is applied to a manual transmission vehicle, by decelerating by braking etc. in a high gear state, the problem arises due to the relationship between vehicle speed and gear ratio. The engine speed may drop below the idle speed. Therefore, as mentioned above, by setting a large fuel increase characteristic to prevent engine stalling assuming that the power steering is stationary, there is a risk that an excessive amount of fuel will be injected even though there is little possibility of engine stalling. . That is, during high gear deceleration, the engine speed drops rapidly and, unless the driver operates the transmission to shift to the low gear side, the fuel injection amount will be rapidly increased. As a result, there was a risk that smoke would increase rapidly. Alternatively, since the fuel injection amount varies greatly with respect to the engine speed, there is a risk that the vehicle surge that occurs slightly when driving in a high gear at a certain vehicle speed may be aggravated.

This invention was made in view of the above-mentioned circumstances, and its purpose is to prevent an increase in smoke due to an unnecessary increase in the amount of fuel injection while maintaining the function of preventing engine stalling. An object of the present invention is to provide a fuel injection amount control device for a diesel engine.

[0005]

[Means for Solving the Problems] 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;
Operating state detection means M3 for detecting the operating state including the rotational speed of the diesel engine M1, and the operating state detection means M
an injection amount calculation means M4 which calculates the amount of fuel to be injected into the diesel engine M1 based on the detection result of step 3; and a fuel injection means M based on the calculation result of the injection amount calculation means M4.
When the detection result of the rotation speed by the injection control means M5 that drives and controls the engine 2 and the operating state detection means M3 is lower than a predetermined low rotation speed, the calculation result of the fuel injection amount by the injection amount calculation means M4 is corrected to increase the amount. A fuel injection amount control device for a diesel engine including a low rotation increase correction means M6,
The vehicle speed detecting means M7 detects the vehicle speed, and the correction limiting means M8 limits the increase correction by the low rotation increase correcting means M6 when the detection result of the vehicle speed detecting means M7 is higher than a predetermined low vehicle speed. There is.

[0006]

[Operation] According to the above structure, as shown in FIG. 1, when the diesel engine M1 is operating, the operating state detecting means M3
detects the operating state including the rotation speed of the diesel engine M1. Also, based on the detection result, the injection amount calculation means M
4 calculates the amount of fuel to be injected into the diesel engine M1. Further, based on the calculation result, the injection control means M5 drives and controls the fuel injection means M2.

When the rotational speed detection result by the operating state detection means M3 is lower than a predetermined low rotational speed, the low rotational increase correction means M6 increases the fuel injection amount calculation result by the injection amount calculation means M4. Diesel engine M1
is suppressed from falling below a predetermined low rotational speed. On the other hand, the vehicle speed detection means M7 detects the vehicle speed while the diesel engine M1 is operating, and if the detection result is higher than a predetermined low vehicle speed, the correction restriction means M8 causes the low rotational speed increase correction means M6 to perform an increase correction. Restrict.

Therefore, for example, when the vehicle speed is higher than a predetermined low speed at which the power steering is not switched, even if the rotation speed of the diesel engine M1 is lower than the predetermined low rotation speed. Since the possibility of engine stalling is low, the amount increase correction by the low rotation amount increase correction means M6 is limited, and unnecessary increases in the fuel injection amount will not be performed. In addition, when the power steering is switched off and the load suddenly increases, the number of revolutions of the diesel engine M1 becomes lower than a predetermined low number of revolutions, so that the amount of fuel injection can be increased appropriately. Ru.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the fuel injection amount control device for a diesel engine according to the present invention is applied to an automobile will be described in detail below with reference to the drawings. FIG. 2 is a schematic configuration diagram showing a fuel injection amount control device for a supercharged diesel engine in this embodiment, and FIG. 3 is a sectional view showing a distribution type fuel injection pump 1 constituting the fuel injection means. The fuel injection pump 1 is connected to the crankshaft 40 of the diesel engine 2.
A drive pulley 3 is connected to the drive pulley 3 via a belt or the like. The fuel injection pump 1 is driven by the rotation of the drive pulley 3, and fuel is force-fed to each fuel injection nozzle 4 provided for each cylinder (four cylinders in this case) of the diesel engine 2, thereby injecting the fuel. .

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

A roller ring 9 is provided between the pulser 7 and the cam plate 8, and a plurality of cam rollers 10 are mounted along the circumference of the roller ring 9 to face the cam face 8a of the cam plate 8. There is. cam face 8
The number a is the same as the number of cylinders of the diesel engine 2. Further, the cam plate 8 is always urged into engagement with the cam roller 10 by a spring 11.

The base end of a fuel pressurizing plunger 12 is attached to the cam plate 8 so as to be able to rotate together with the cam plate 8, and the cam plate 8 and the plunger 12 are rotated in conjunction with the rotation of the drive shaft 5. That is, the rotational force of the drive shaft 5 is transmitted to the cam plate 8 via the coupling, so that the cam plate 8 engages with the cam roller 10 while rotating, and reciprocates in the left and right directions in the figure by the same number of cylinders. Driven. Further, along with this reciprocating movement, the plunger 12 is rotated and reciprocated in the same direction. In other words,
The plunger 12 is moved forward (lifted) in the process where the cam face 8a of the cam plate 8 rides on the cam roller 10 of the roller ring 9, and conversely, the plunger 12 is moved back in the process where the cam face 8a rides down on the cam roller 10.

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

When the drive shaft 5 is rotated and the fuel feed pump 6 is driven, fuel is supplied from a fuel tank (not shown) into the fuel chamber 21 through the fuel supply port 20. Also, during the suction stroke in which the plunger 12 is moved back and the high pressure chamber 15 is depressurized, the suction groove 1
6 communicates with the suction port 19, fuel is introduced from the fuel chamber 21 into the high pressure chamber 15. 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 from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder and is injected.

A spill passage 22 is formed in the pump housing 13 for communicating fuel overflow (spill) between the high pressure chamber 15 and the fuel chamber 21 . An electromagnetic spill valve 23 serving as a spill adjustment valve for adjusting fuel spill from the high pressure chamber 15 is provided in the middle of the spill passage 22 . This electromagnetic spill valve 23 is a normally open type valve, and when the coil 24 is not energized (off), the valve body 25 is opened and the fuel in the high pressure chamber 15 is spilled into the fuel chamber 21 . Further, when the coil 24 is energized (turned on), the valve body 25 is closed and spilling of fuel from the high pressure chamber 15 to the fuel chamber 21 is stopped.

Accordingly, by controlling the energization time of the electromagnetic spill valve 23, the valve 23 is controlled to close and open, and the spill amount of fuel from the high pressure chamber 15 to the fuel chamber 21 is controlled. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the pressure of the fuel in the high pressure chamber 15 is reduced, and 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 increase while the electromagnetic spill valve 23 is open, and fuel injection from the fuel injection nozzle 4 is not performed. Further, while the plunger 12 is moving forward, the amount of fuel injected from the fuel injection nozzle 4 is controlled by controlling the timing of closing and opening of the electromagnetic spill valve 23.

A timer device 26 (expanded 90 degrees in this figure) is provided on the lower side of the pump housing 13 for adjusting the fuel injection timing. This timer device 26 changes the timing at which the cam face 8a engages with the cam roller 10, that is, the timing at which the cam plate 8 and the plunger 12 are driven back and forth by changing the position of the roller ring 9 with respect to the rotational direction of the drive shaft 5. It is for.

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

The pressurizing chamber 30 of the timer housing 27 includes:
Pressurized fuel is introduced by a fuel feed pump 6. The position of the timer piston 28 is determined by the balance between the fuel pressure and the biasing force of the timer spring 31. Furthermore, by determining the position of the timer piston 28, the position of the roller ring 9 is determined, and the plunger 1 is moved through the cam plate 8.
2 reciprocating timing is determined.

A timing control valve 33 is provided in the timer device 26 in order to adjust the fuel pressure, ie, the control oil pressure, of the timer device 26. That is, the pressurizing chamber 30 and the low pressure chamber 29 of the timer housing 27 are connected to the communication passage 34.
A timing control valve 33 is provided in the middle of the communication passage 34. The timing control valve 33 is an electromagnetic valve whose opening and closing are controlled by a duty-controlled energization signal, and the fuel pressure within the pressurizing chamber 30 is adjusted by opening and closing the timing control valve 33. By adjusting the fuel pressure, the lift timing of the plunger 12 is controlled, and the timing of fuel injection from each fuel injection nozzle 4 is adjusted.

A rotation speed sensor 35 consisting of an electromagnetic pickup coil is attached to the upper part of the roller ring 9 so as to face the outer peripheral surface of the pulser 7. This rotation speed sensor 35
detects the passage of protrusions and the like of the pulser 7 and outputs a timing signal (engine rotation pulse) corresponding to the engine rotation speed NE. Furthermore, since the 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 explained. In this diesel engine 2, a main combustion chamber 44 corresponding to each cylinder is formed by a cylinder 41, a piston 42, and a cylinder head 43, respectively. or,
Each of the main combustion chambers 44 is connected to a sub-combustion chamber 45 corresponding to each cylinder. Then, fuel injected from each fuel injection nozzle 4 is supplied to each sub-combustion chamber 45 . Further, a well-known glow plug 46 as a starting aid device is attached to each sub-combustion chamber 45.

The diesel engine 2 is provided with an intake pipe 47 and an exhaust pipe 50, the intake pipe 47 is provided with a copresor 49 of a turbocharger 48 constituting a supercharger, and the exhaust pipe 50 is provided with a turbocharger 49. 48
A turbine 51 is provided. Further, the exhaust pipe 50 is provided with a waste gate valve 5 for adjusting the supercharging pressure PiM.
2 is provided. As is well known, the turbocharger 48 uses the energy of exhaust gas to rotate the turbine 51 and rotates the compressor 49 coaxially therewith to increase the pressure of intake air. This allows a high-density air-fuel mixture to be sent into the main combustion chamber 44 to combust a large amount of fuel, thereby increasing the output of the diesel engine 2.

The diesel engine 2 also has an exhaust pipe 5.
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in the exhaust gas into the intake port 53 of the intake pipe 47. In the middle of the recirculation pipe 54, there is an exhaust gas recirculation valve (EGR valve) 55 that adjusts the amount of recirculation of the exhaust gas.
is provided. This EGR valve 55 is controlled to open and close by controlling a vacuum switching valve (VSV) 56.

Further, a throttle valve 58 is provided in the middle of the intake pipe 47 and is opened and closed in conjunction with the amount of depression of the accelerator pedal 57. Also, the throttle valve 5
A bypass passage 59 is provided in parallel to 8, and a bypass throttle valve 60 is provided in the bypass passage 59. This bypass throttle valve 60 is controlled to open and close by an actuator 63 having a two-stage diaphragm chamber driven by the control of two VSVs 61 and 62. This bypass throttle valve 60 is controlled to open and close depending on various operating conditions. For example, during idling operation, it is controlled to a half-open state to reduce noise and vibration, etc., during normal operation, it is controlled to a fully open state, and when the operation is stopped, it is controlled to a fully closed state to ensure a smooth stop.

[0026] As described above, the electromagnetic spill valve 23 provided in the fuel injection pump 1 and the diesel engine 2
, timing control valve 33, glow plug 4
6 and each VSV 56, 61, 62 are injection amount calculation means,
An electronic control unit (hereinafter simply referred to as "ECU") 7 that constitutes the injection control means, the low-speed increase correction means, and the correction restriction means.
1, and their drive timings are controlled by the same ECU 71.

In addition to the rotational speed sensor 35, the following various sensors are provided as sensors constituting the operating state detection means. That is, an intake air temperature sensor 7 is installed in the intake pipe 47 to detect the intake air temperature THA near the air cleaner 64.
2 is provided. Further, an accelerator opening sensor 73 is provided that detects an accelerator opening ACCP corresponding to the load of the diesel engine 2 from the opening/closing position of the throttle valve 58. An intake pressure sensor 74 is provided near the intake port 53 to detect the intake air pressure after supercharging by the turbocharger 48, that is, the supercharging pressure PiM. Furthermore, the cooling water temperature TH of the diesel engine 2
A water temperature sensor 75 for detecting W is provided. Further, the rotation reference position of the crankshaft 40 of the diesel engine 2,
For example, a crank angle sensor 76 is provided to detect the rotational position of the crankshaft 40 with respect to the top dead center of a specific cylinder. In addition, the transmission (not shown) includes a vehicle speed sensor 77 as a vehicle speed detection means that turns on and off a reed switch 77b using a magnet 77a rotated by the rotation of the gear to detect the vehicle speed SP.
is provided.

The ECU 71 is connected to the above-mentioned sensors 72 to 77, as well as the rotational speed sensor 35. In addition, the ECU 71 has each sensor 35
, 72 to 77, the electromagnetic spill valve 23, timing control valve 33, glow plug 46, VSV 56, 61, 62, etc. are suitably controlled.

Next, the configuration of the ECU 71 mentioned above will be explained with reference to the block diagram shown in FIG. The ECU 71 includes a central processing unit (CPU) 81 and a read-only memory (ROM) that stores predetermined control programs, maps, etc.
82, a random access memory (RAM) 83 for temporarily storing calculation results etc. of the CPU 81, a backup RAM 84 for storing pre-stored data, etc., and each of these parts and an input port 85, an output port 86, etc. are connected by a bus 87. It is configured as a logic operation circuit.

The input port 85 has the aforementioned intake temperature sensor 72, accelerator opening sensor 73, intake pressure sensor 74, and water temperature sensor 75 connected to each buffer 88, 89, 90, 9.
1, connected via a multiplexer 93 and an A/D converter 94. Similarly, the aforementioned rotation speed sensor 35, crank angle sensor 76, and vehicle speed sensor 77 are connected to the input port 85 via a waveform shaping circuit 95. Then, the CPU 81 reads detection signals from the sensors 35, 72 to 77, etc. inputted through the input port 85 as input values. Further, each drive circuit 96 is connected to the output port 86.
, 97, 98, 99, 100, 101, the electromagnetic spill valve 23, timing control valve 33, glow plug 46, VSV 56, 61, 62, etc. are connected.

[0031]The CPU 81 then controls each sensor 35, 72.
Based on the input value read from ~77, the electromagnetic spill valve 2
3. Suitably controls the timing control valve 33, glow plug 46, VSV 56, 61, 62, etc. Next, the processing operation of the fuel injection amount control executed by the ECU 71 described above will be described with reference to FIGS. 5 to 11.

The flowchart shown in FIG. 5 is a main routine for controlling the fuel injection amount in the fuel injection pump 1 among the various processes executed by the ECU 71, and is executed at regular interruptions every predetermined time. When the process moves to this routine, first in step 101, the rotation speed sensor 35, the accelerator opening sensor 73, and the water temperature sensor 75 are detected.
Based on the detected values of the vehicle speed sensor 77, the engine speed NE, accelerator opening ACCP, cooling water temperature THW, and vehicle speed SP are read.

Subsequently, in step 102, a corrected accelerator opening degree ACCPA is calculated from the accelerator opening degree ACCP and the cooling water temperature THW. This corrected accelerator opening ACCPA is determined by the pseudo accelerator opening ACSTA at startup determined according to the cooling water temperature THW and the accelerator opening A.
It is determined by comparison with CCP etc. Next, in step 103, the previously read engine speed NE
The final injection amount QFIN is calculated based on the corrected accelerator opening degree ACCPA, etc. This final injection amount QFIN is determined according to the following calculation formula (1). In addition, "C" in the formula
1, C2, C3'' are constants.

QFIN=C1+C2×ACCPA×C3
×NE...(1) Subsequently, in step 104,
It is determined whether the vehicle is a manual transmission (M/T) vehicle. This determination as an M/T vehicle is made based on an M/T flag set in advance in the backup RAM 84 in the ECU 71 to indicate that the vehicle is an M/T vehicle.

Here, if the vehicle is not an M/T vehicle, that is, if it is an automatic transmission (A/T) vehicle, in step 105, a low rotation increase amount for the A/T is determined based on the engine rotation speed NE read earlier. Correction coefficient KA
VT is calculated and the process moves to step 109. This low rotation increase correction coefficient KAVT is determined by referring to a predetermined map as shown in FIG. As is clear from this map, the low rotation increase correction coefficient KAVT for A/T
It can be seen that as the engine speed NE becomes less than 650 rpm, the value gradually increases. The value of the low rotation increase correction coefficient KAVT in this map is set in consideration of the load on the torque converter of the A/T vehicle.

On the other hand, if it is determined in step 104 that the vehicle is an M/T vehicle, in step 106 the previously read vehicle speed SP is set to "15 km/h" as a predetermined low vehicle speed.
Determine whether it is higher than. Here, the vehicle speed SP is “1”.
If the speed is higher than 5km/h, it is assumed that there is no risk of stalling due to low rotation of the diesel engine 2.
In step 107, in order to prohibit the increase correction at low rotation, the low rotation increase correction coefficient KAVT is uniquely set to "1.
0'', and the process moves to step 109.

Furthermore, in step 106, when the vehicle speed SP is not higher than "15 km/h" and the vehicle is running at low speed or stopped, an increase correction is made at low revolutions in order to prevent stalling due to low revolutions of the diesel engine 2. In order to execute this, in step 108, a low rotation increase correction coefficient KAVT for M/T is calculated, and the process proceeds to step 109. This low rotation increase correction coefficient KAVT is determined by referring to a predetermined map as shown in FIG. As is clear from this map, it can be seen that the low rotation increase correction coefficient KAVT for M/T increases rapidly when the engine rotation speed NE falls below "750 rpm." The value of the low rotation increase correction coefficient KAVT in this map is set in consideration of the power steering load in M/T vehicles.

[0038] Then, step 105, step 107
Alternatively, moving from step 108, in step 109, based on the final injection amount QFIN obtained earlier,
Spill timing pulse number CANGLa and remainder angle θREM
Calculate each a. These spill period pulse numbers CA
NGLa and the remainder angle θREMa are calculated using the following formula (2
).

QFIN=11.25×CANGLa+θ
REMa...(2) Therefore, as shown in the time chart of FIG. 8, the final injection amount QFIN is divided by "11.25" which corresponds to the angle of one engine rotation pulse.
The quotient is determined as the spill timing pulse number CANGLa,
The remainder is determined and set as the remainder angle θREMa. Here, the number of spill timing pulses CANGLa corresponds to the number of rotation pulses corresponding to the spill timing at which the electromagnetic spill valve 23 should be turned off to end fuel injection, that is, the fuel should be spilled (in FIG. 8, it is "4"). be). or,
The remainder angle θREMa is the number of pulses at the relevant spill period CAN
This is a value that indicates a more precise spill timing in GLa in terms of angle.

Then, in step 110, the result of multiplying the remainder angle θREMa by the low rotation increase correction coefficient KVAT is set as the final remainder angle θREM. Therefore, the final surplus angle θREM is the low rotation increase correction coefficient KV
It becomes a value that reflects the AT, and when a low-speed increase is required, it becomes a value commensurate with the increase, and when a low-speed increase is prohibited, the remainder angle θREMa remains the same value.

Subsequently, in step 111, the spill time TSPONa at the spill timing pulse number CANGLa is calculated from the final remainder angle θREM and the spill pulse time TS1125. That is, the final remainder angle θR
EM is converted into time. This spill time TSPO
Na is calculated according to the following calculation formula (3). T.S.
PONa=(θREM/11.25)×TS1125
...(3) Here, the spill time pulse time TS1125 is the spill time pulse number CANGLa in the previous control cycle.
This corresponds to one pulse time TNINT in , and is determined according to a separate flowchart shown in FIG. The flowchart in FIG. 9 is an NE interrupt routine, which is executed by an interrupt for each pulse input of the engine speed NE. That is, in step 210, one pulse time TNINT corresponding to the number of spill timing pulses CANGLa in the previous control cycle is calculated. Then, in step 220, the pulse time TNINT
is set as the spill pulse time TS1125, and the subsequent processing is temporarily terminated.

Returning again to the main routine shown in FIG.
In step 112, in consideration of the calculation processing speed of the ECU 71, in order to prevent delays due to multiple interrupts,
It is determined whether the spill time TSPONa is smaller than a predetermined value of "100 μs". Here, spill time TSPO
If Na is smaller than the predetermined "100 μs", in step 113, as shown in FIG. 10, the result of adding the spill time pulse time TS1125 to the spill time TSPONa is set as the final spill time TSPON. Further, in the same step 113, the result of subtracting "1" from the spill timing pulse number CANGLa is set as the final spill timing pulse number CANGL. Then, in step 114, the electromagnetic spill valve 23 is turned off based on the set final spill timing pulse number CANGL and final spill time TSPON, and the fuel injection pump 1
Controls the end timing of fuel injection, that is, the amount of fuel injection from
The subsequent processing is temporarily terminated.

On the other hand, if the spill time TSPONa is equal to or greater than the predetermined "100 μs" in step 112, then in step 115, as shown in FIG.
Spill time TSPONa is the final spill time TS
Set as PON. Further, in the same step 114, the spill timing pulse number CANGLa is directly set as the final spill timing pulse number CANGL. Then, in step 114, based on the set final spill timing pulse number CANGL and final spill time TSPON, the electromagnetic spill valve 23 is turned off to determine the end timing of fuel injection from the fuel injection pump 1, that is, the fuel injection amount. control and temporarily end the subsequent processing.

The amount of fuel injected from the fuel injection pump 1 to the diesel engine 2 is controlled by the processing by the ECU 71 as described above. Therefore, according to the fuel injection amount control device of this embodiment, the low rotation increase correction coefficient KV for A/T
An AT is provided to increase and correct the fuel injection amount. Therefore, when the present invention is implemented in an A/T vehicle equipped with a torque converter, it is possible to appropriately perform increase correction when the diesel engine 2 is rotating at low speeds, taking into consideration the load on the torque converter. As a result, for example, when the engine speed NE becomes lower than a predetermined idle speed during idling operation, the fuel injection amount is increased to prevent engine stalling. In other words, idle rotation speed control is performed.

Further, according to the fuel injection amount control device of this embodiment, a low rotation increase correction coefficient KVAT for M/T is provided to increase the fuel injection amount, and the vehicle speed S
When P is higher than "15 km/h", increasing correction of the fuel injection amount is prohibited and limited. Therefore,
For example, in the case of a manual transmission vehicle equipped with power steering, when the power steering is switched off and the load increases rapidly, if the engine speed NE becomes lower than 750 rpm, the fuel The injection amount is increased appropriately. As a result, est can be prevented.

On the other hand, in an M/T vehicle, when the vehicle speed SP is "15km" where the power steering is not switched on and off,
/h”, the engine speed NE
Even if the engine speed is lower than 750 rpm, since there is little possibility of engine stalling, the increase correction of the fuel injection amount is prohibited, so the fuel injection amount will not be increased unnecessarily. For example, in a M/T vehicle, deceleration is performed by the brake etc. in a high gear state, and the vehicle speed SP is "15 km/h".
If the engine speed NE is lower than the idle speed range of 750 rpm while the engine speed is higher than 750 rpm, the increase correction of the fuel injection amount is prohibited. Therefore, it is possible to prevent the fuel injection amount from being suddenly increased even though the possibility of engine stalling is low, thereby preventing a sudden increase in smoke. In other words, according to the fuel injection amount control device of this embodiment, in a M/T vehicle, it is possible to maintain the engine stall prevention function at low rotation speeds, taking into consideration the power steering's fixed switching, etc. When the vehicle is traveling at a certain speed SP, it is possible to prevent an increase in smoke caused by an unnecessary increase in the amount of fuel injection.

Furthermore, according to the fuel injection amount control device of this embodiment, the fuel injection amount is not suddenly increased during the deceleration operation of the M/T vehicle as described above, so that the fuel injection amount relative to the engine speed NE is Changes in the injection amount are suppressed, and the slight surge that occurs when driving in high gear can be suppressed. It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be implemented as follows by changing a part of the structure as appropriate without departing from the spirit of the invention.

(1) In the above embodiment, in order to increase the fuel injection amount, the low rotation increase correction coefficient KAVT is determined according to the engine rotation speed NE, and that value is multiplied by the separately determined remainder angle θREM. However, the method of processing the increase correction can be changed as appropriate, for example by multiplying the final injection amount QFIN. (2) In the above embodiment, the vehicle speed S
When P is higher than the predetermined low vehicle speed of "15 km/h", the low rotation increase correction coefficient KAVT is set to "1.0" to prohibit the increase correction of the fuel injection amount.
The reference vehicle speed SP can also be changed as appropriate.

(3) In the above embodiment, the vehicle speed SP is “15
km/h", the low rotation increase correction coefficient KA
Although the VT is set to "1.0" and the increase correction of the fuel injection amount is prohibited, the increase correction value may be suppressed to an extremely small value instead of being prohibited. (4) In the above embodiment, the diesel engine 2 is equipped with the turbocharger 48 as a supercharger, but
It can also be embodied in a diesel engine equipped with a supercharger as a supercharger or a diesel engine without a supercharger.

[0050]

As described in detail above, according to the present invention, the diesel engine is configured to increase the fuel injection amount when the detected number of revolutions of the diesel engine is lower than a predetermined low number of revolutions. In the fuel injection amount control device, the increase correction of the fuel injection amount is limited when the vehicle speed is higher than a predetermined low vehicle speed, so while maintaining the engine stall prevention function at low rotation speeds of the diesel engine, the vehicle At low revolutions when the vehicle speed is higher than a predetermined low speed, it is possible to prevent unnecessary increase corrections to the fuel injection amount, which has the excellent effect of preventing a sudden increase in smoke. do.

[Brief explanation of the drawing]

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

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

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

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

FIG. 5 is a flowchart illustrating a main routine for fuel injection amount control executed by an ECU in one embodiment.

FIG. 6: A/A vs. engine speed in one embodiment.
It is a figure which shows the map which predetermined the low rotation increase correction coefficient for T.

[Figure 7] M/ versus engine speed in one embodiment
It is a figure which shows the map which predetermined the low rotation increase correction coefficient for T.

FIG. 8 is a time chart illustrating the correspondence between engine rotation pulses and electromagnetic spill valve operation, the number of spill timing pulses, the remainder angle, etc. according to the final injection amount in one embodiment.

FIG. 9 is a flowchart illustrating an NE interrupt routine for determining a spill pulse time, which is executed by the ECU in one embodiment.

FIG. 10 is a time chart illustrating the correspondence between the engine rotation pulse and the electromagnetic spill valve operation, the final spill timing pulse number, the final spill time, etc. when the spill time is smaller than 100 μs in one embodiment.

FIG. 11 is a time chart illustrating the correspondence between the engine rotation pulse and the operation of the electromagnetic spill valve, the final spill timing pulse number, the final spill time, etc. when the spill time is 100 μs or more in one embodiment.

[Explanation of symbols]

1...Fuel injection pump, 2...Diesel engine, 35...
Rotation speed sensor, 73...Accelerator opening sensor, 75...Water temperature sensor (35, 73, 75 constitute driving state detection means), 71...Injection amount calculation means, injection control means, low rotation increase correction means, and ECU 7 constituting the correction limiting means
7...Vehicle speed sensor as vehicle speed detection means.

Claims (1)

[Claims] 1. A fuel injection means for injecting fuel into a diesel engine; an operating state detecting means for detecting an operating state including the number of revolutions of the diesel engine; injection amount calculation means for calculating the amount of fuel to be injected;
injection control means for driving and controlling the fuel injection means based on the calculation results of the injection amount calculation means; and when the rotation speed detected by the operating state detection means is lower than a predetermined low rotation speed, the injection amount calculation is performed. A fuel injection amount control device for a diesel engine, comprising: a low-rpm increase correction means for increasing the calculation result of the fuel injection amount by the means; a vehicle speed detection means for detecting a vehicle speed; 1. A fuel injection amount control device for a diesel engine, comprising: correction limiting means for limiting increase correction by the low rotational speed increase correction means when the vehicle speed is higher than a low vehicle speed.