JP2888123B2 - Fuel injection control device for internal combustion engine - Google Patents

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 an internal combustion engine, and more particularly to a fuel injection control device for an internal combustion engine that controls opening and closing of an electromagnetic spill valve based on an output signal of a rotation sensor.

[0002]

2. Description of the Related Art Conventionally, as one of fuel injection devices,
Some include a power generation type (so-called electromagnetic pickup type) rotation sensor that outputs a rotation signal at a predetermined crank angle in accordance with engine rotation. Since this type of rotation sensor is based on the principle of detecting a change in magnetic flux, there is a disadvantage that the electromotive force of a detection coil in the sensor is reduced at low speed rotation. Therefore, for example, when the engine is started at a low temperature or when the battery voltage is low, the rotation becomes extremely low, the rotation signal from the rotation sensor cannot be detected, and the fuel injection control according to the rotation signal is not executed, and the engine cannot be started. There may be a problem.

Therefore, as a countermeasure, Japanese Patent Application Laid-Open
As disclosed in Japanese Patent Application Laid-Open No. 1-258951, when fuel injection control is performed using an electromagnetic spill valve, the electromagnetic spill valve is always turned on at the time of starting, regardless of the rotation signal, and the fuel is always injected. Then, a method for solving the problem has been proposed.

[0004]

However, in the above-described conventional control method, since the electromagnetic spill valve is always closed at the time of starting to perform the maximum injection of the fuel pump capacity, the fuel injection amount may be excessive. Almost.

As described above, when the fuel injection amount becomes excessive,
There is a problem that the smoke at the start is increased and the pump driving torque is also excessively large, so that the cranking speed is reduced, and in the worst case, the engine is stalled.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and, among the fluctuating engine speeds, the engine speed in an undetectable region is determined based on the speed signal in the engine speed detectable region even at the time of starting. An object of the present invention is to provide a fuel injection control device for an internal combustion engine that estimates and performs electromagnetic spill valve control based on the estimated engine speed to prevent generation of smoke at the time of starting and a decrease in cranking speed. I do.

[0007]

FIG. 1 is a diagram illustrating the principle of the present invention.

As shown in FIG. 1, in order to solve the above-mentioned problem, according to the present invention, a rotation sensor (A2) for outputting a rotation signal at every predetermined crank angle according to the rotation of an internal combustion engine (A1).
Operating state detecting means (A3) for detecting various operating states of the internal combustion engine (A1), and fuel injection for calculating a fuel injection amount to the internal combustion engine (A1) according to the detected operating state The opening / closing control of the electromagnetic spill valve (A5) is performed based on the fuel injection amount calculated by the fuel injection amount calculating means (A4) and the rotation signal output from the rotation sensor (A2). In a fuel injection control device for an internal combustion engine including a fuel injection control means (A6) for executing fuel injection, a start time detection means (A7) for detecting a start time of the internal combustion engine, and a rotation fluctuation of the internal combustion engine. When the internal combustion engine is determined to be starting by the rotation fluctuation detecting means (A10) and the starting time detecting means (A7), the rotation fluctuation detecting means (A10) detects the rotation fluctuation signal detected by the rotation fluctuation detecting means (A10). A fluctuation cycle calculating means (A8) for calculating a rotation fluctuation cycle of the internal combustion engine; Electromagnetic spill valve control means (A9) for controlling the opening and closing of the electromagnetic spill valve (A5) based on the rotation fluctuation cycle of the internal combustion engine calculated by the fluctuation cycle calculation means (A8). It is a feature.

[0009]

In the fuel injection control device for an internal combustion engine having the above-described configuration, when the internal combustion engine (A1) is determined to be at the time of starting by the starting detection means (A7), the variable cycle calculating means (A8) rotates. The rotation fluctuation cycle of the internal combustion engine is calculated based on the rotation fluctuation signal of the internal combustion engine detected by the fluctuation detecting means (A10). Since the rotation fluctuation of the internal combustion engine also affects the operation of the other components constituting the internal combustion engine, the rotation fluctuation detecting means (A10) for detecting the rotation fluctuation of the internal combustion engine is a detection means other than the rotation sensor (A2). Means can be used. The electromagnetic spill valve control means (A9) controls opening and closing of the electromagnetic spill valve (A5) based on the rotation fluctuation cycle of the internal combustion engine detected by the rotation fluctuation detection means (A10).

That is, in the fuel injection control device according to the present invention, the electromagnetic spill valve (A5) is not always closed at the time of starting, but rather is controlled by the rotation fluctuation cycle of the internal combustion engine detected by the rotation fluctuation detecting means (A10). Based on this, the engine rotation state in the region where the rotation sensor (A2) cannot be detected is estimated, and the opening and closing control of the electromagnetic spill valve (A5) is performed.

Therefore, even at the time of starting, the fuel injection control can be performed in a state close to a state where the engine speed is stable (a state other than at the time of starting).
Compared with the conventional fuel injection control in which (A5) is normally closed, the fuel injection amount can be reduced, the smoke can be reduced, and the cranking torque can be prevented from lowering.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic diagram showing a fuel injection control device for a supercharged diesel engine in this embodiment, and FIG. 3 is a sectional view showing the distribution type fuel injection pump 1. As shown in FIG. The fuel injection pump 1 includes a drive pulley 3 which is drivingly connected to a crankshaft 40 of the diesel engine 2 via a belt or the like. And the drive pulley 3
The fuel injection pump 1 is driven by the rotation of, 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 a tip of a drive shaft 5.
In the middle of the drive shaft 5, there is provided a fuel feed pump (developed by 90 degrees in this figure) 6 composed of a vane type pump.

Further, a disk-shaped pulsar 7 is mounted on the base end side of the drive shaft 5. On the outer peripheral surface of the pulsar 7, the same number as the number of cylinders of the diesel engine 2, that is, in this case, four cutting teeth are formed at equal angular intervals. Projections (teeth) are formed at equal angular intervals every 75 degrees. 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 mounted along the circumference of the roller ring 9. I have. Cam face 8
a is provided as many as the number of cylinders of the diesel engine 2. The cam plate 8 is always urged and engaged with the cam roller 10 by the spring 11.

The base end of the fuel pressurizing plunger 12 is attached to the cam plate 8 so as to be integrally rotatable, so that 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 rotates and engages with the cam roller 10 to reciprocate in the left-right direction by the same number as the number of cylinders. Driven. Further, the plunger 12 is driven to reciprocate in the same direction while rotating with the reciprocation.

That is, the cam face 8 of the cam plate 8
The plunger 12 is moved forward (lift) while a is riding on the cam roller 10 of the roller ring 9, and conversely, the plunger 12 is moved back while the cam face 8 a rides down 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 of the plunger 12 and the bottom of the cylinder 14.
It has become. Also, on the outer periphery of the tip 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. In addition, these suction grooves 16
And the pump housing 13 corresponding to the distribution port 17.
Is formed with a distribution passage 18 and a suction port 19.

When the drive shaft 5 is rotated to drive the fuel feed pump 6, 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
The fuel is introduced from the fuel chamber 21 to the high-pressure chamber 15 when one of the ports 6 communicates 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 from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder and injected.

The pump housing 13 is provided with a spill passage 22 for fuel spill that connects the high-pressure chamber 15 and the fuel chamber 21. In the middle of the spill passage 22, there is provided an electromagnetic spill valve 23 as an overflow regulating valve for adjusting the fuel spill from the high-pressure chamber 15. The electromagnetic spill valve 23 is a normally-open type valve. When the coil 24 is not energized (off), the valve body 25 is opened and the high-pressure chamber 1 is opened.
The fuel in 5 is spilled into the fuel chamber 21. Also, coil 2
By energizing (turning on) 4, the valve body 25 is closed, and spilling of fuel from the high-pressure chamber 15 to the fuel chamber 21 is stopped.

Therefore, 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 adjusted. Then, by opening the electromagnetic spill valve 23 during the compression stroke of the plunger 12, the fuel in the high-pressure chamber 15 is reduced in pressure, and the fuel injection from the fuel injection nozzle 4 is stopped. That is, even when 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 the fuel injection from the fuel injection nozzle 4 is not performed. Further, during the forward movement of the plunger 12, by controlling the timing of closing and opening the electromagnetic spill valve 23, the amount of fuel injected from the fuel injection nozzle 4 is controlled.

Below the pump housing 13, there is provided a timer device (expanded at 90 degrees in this figure) 26 for adjusting 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, thereby changing 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 driven by hydraulic pressure. A timer housing 27, a timer piston 28 fitted in the housing 27, and a timer A timer spring 31 for urging the piston 28 toward the other pressurizing chamber 30 is provided. The timer piston 28 is connected to the roller ring 9 via a slide pin 32.

In the pressurizing chamber 30 of the timer housing 27,
The fuel pressurized by the fuel feed pump 6 is introduced. The position of the timer piston 28 is determined by the balance between the fuel pressure and the urging force of the timer spring 31. Further, the position of the roller ring 9 is determined by determining the position of the timer piston 28, and the plunger 1 is moved through the cam plate 8.
2 is determined.

To adjust the fuel pressure of the timer device 26, that is, the control oil pressure, the timer device 26 is provided with a timing control valve 33. That is, the pressurizing chamber 30 and the low-pressure chamber 29 of the timer housing 27
The 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 in the pressurizing chamber 30 is adjusted by controlling the opening and closing of the timing control valve 33. Then, the lift timing of the plunger 12 is controlled by the fuel pressure adjustment, and the fuel injection timing from each fuel injection nozzle 4 is adjusted.

On the upper part of the roller ring 9, a rotation speed sensor 35 as an engine rotation detecting means comprising an electromagnetic pickup coil is mounted so as to face the outer peripheral surface of the pulser 7. The rotation speed sensor 35 detects a change in magnetic flux that changes when a projection or the like of the pulsar 7 crosses, and detects a timing signal corresponding to the engine rotation speed NE, that is, an engine rotation pulse as a rotation angle signal for each predetermined crank angle. Is output. Further, since the rotation speed sensor 35 is integrated with the roller ring 9, the rotation speed sensor 35 outputs a reference timing signal to the plunger lift at a constant timing regardless of the control operation of the timer device 26. Since the rotation speed sensor 35 is of an electromagnetic pickup type, the electromotive force of the detection coil in the sensor becomes small at low rotation,
As described above, the engine rotation pulse cannot be output.

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,
Each of the main combustion chambers 44 is connected to an auxiliary fuel chamber 45 which is also provided for each cylinder. Then, the fuel injected from each fuel injection nozzle 4 is supplied to each sub combustion chamber 45. A well-known glow plug 46 as a start-up assist device is attached to each sub-combustion chamber 45.

A starter motor 37 can be connected to the crankshaft 40. The starter motor 37 is driven at the time of starting and is connected to the crankshaft 40 so that the crankshaft 40 is forcibly driven by the motor torque. It is configured to bias the rotation. In addition, the connection between the klang shaft 40 and the starter motor 37 is released except at the time of starting, so that the rotation load of the klang shaft 40 is prevented from being increased by the starter motor 37. The starter motor 37 is configured to start using a battery 38 as a power source by operating an ignition switch 78. The ignition switch 78 is operated even when the diesel engine 2 is stopped.

The diesel engine 2 has an intake pipe 4
7 and an exhaust pipe 50 are provided, respectively.
Is provided with a compressor 49 of a turbocharger 48 constituting a turbocharger, and an exhaust pipe 50 is provided with a turbocharger 4.
Eight turbines 51 are provided. The exhaust pipe 50 is provided with a waste gate valve 52 for adjusting the supercharging pressure PIM.

As is well known, this turbocharger 48
Rotates the turbine 51 using the energy of the exhaust gas, and rotates the compressor 49 on the same axis as the turbine 51 to increase the pressure of the intake air. As a result, a high-density air-fuel mixture is sent into the main combustion chamber 44 to burn a large amount of fuel, thereby increasing the output of the diesel engine 2.

The diesel engine 2 is provided with a recirculation pipe 54 for recirculating a part of the exhaust gas in the exhaust pipe 50 to the suction 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.
Is provided. The opening and closing of the EGR valve 55 is controlled by the control of a vacuum switching valve (VSV) 56.

Further, a throttle valve 58 is provided in the middle of the intake pipe 47 so as to open and close in accordance with the amount of depression of an accelerator pedal 57. Also, its 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 has two VSVs.
Opening / closing is controlled by an actuator 63 having a two-stage diaphragm chamber driven by the control of 61 and 62. The opening and closing of the bypass throttle valve 60 is controlled in accordance with various operation states. For example, it is controlled to a half-open state during idle operation to reduce noise and vibration, to a fully opened state during normal operation, and to a fully closed state during smooth operation to stop smoothly.

The electromagnetic spill valve 2 provided on the fuel injection pump 1 and the diesel engine 2 as described above
3. The timing control valve 33, the glow plug 46, and each of the VSVs 56, 61, 62 are electrically connected to an electronic control unit (hereinafter simply referred to as "ECU") 71, and their drive timing is controlled by the ECU 71. .

As sensors for detecting the operating state, in addition to the rotation speed sensor 35, the following various sensors are provided. That is, the intake pipe 47 is provided with an intake air temperature sensor 72 for detecting an intake air temperature THA near the air cleaner 64. Further, an accelerator opening sensor 73 for detecting the accelerator opening ACCP corresponding to the load of the diesel engine 2 from the open / close position of the throttle valve 58 is provided. An intake pressure sensor 74 for detecting the intake air pressure after supercharging by the turbocharger 48, that is, the supercharging pressure PIM is provided near the intake port 53. Further, a battery voltage sensor 39 for detecting a battery voltage (B) is connected to the battery 38 so that a change in the battery voltage (B) can be detected.

Further, the cooling water temperature T of the diesel engine 2
Water temperature sensor 75 for detecting HW, diesel engine 2
A crank angle sensor 76 for detecting a rotational position of the crankshaft 40 with respect to a rotational reference position of the crankshaft 40 (for example, a top dead center of a specific cylinder), a magnet 77a provided in a transmission (not shown) and rotated by rotation of a gear in the transmission. A vehicle speed sensor 77 for detecting the vehicle speed (vehicle speed) SP by turning on / off the reed switch 77b is provided.

The ECU 71 is connected to the above-described sensors 72 to 77, the rotation speed sensor 35, and the battery voltage sensor 39, respectively. Also, the ECU 71 controls each sensor 3
5,39,72-77,
Electromagnetic spill valve 23, timing control valve 3
3. The glow plug 46 and the VSVs 56, 61, 62 are suitably controlled.

Next, the configuration of the ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 has a central processing unit (CPU) 81, a read-only memory (RO) storing a predetermined control program, a map, and the like in advance.
M) 82, a random access memory (RAM) 83 for temporarily storing the operation results of the CPU 81, a backup RAM 84 for storing pre-stored data, a clock 92 for generating a predetermined clock signal, etc. And an output port 86 and the like via a bus 87.

The input port 85 includes the above-described battery voltage sensor 39, intake air temperature sensor 72, accelerator angle sensor 73, intake pressure sensor 74, and water temperature sensor 75, buffers 80, 88 to 91, a multiplexer 93, and an A / D.
It is connected via a converter 94. Similarly, the input port 85 is connected to the rotation speed sensor 35, the crank angle sensor 76, and the vehicle speed sensor 77 via a waveform shaping circuit 95. In addition, the ignition switch 78
Are also connected to the input port 85.

The CPU 81 reads, as input values, detection signals of the sensors 35, 39, 72 to 77, etc., which are input through the input port 85. Further, the output port 86 is connected to the electromagnetic spill valve 23 via each of the driving circuits 96 to 101,
Timing control valve 33, glow plug 46
And VSVs 56, 61, 62, etc. are connected.

Then, the CPUI 81 controls the sensors 35, 3
The electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, the VSVs 56, 61, 62, etc. are suitably controlled based on the input values read from 9, 72 to 77.

The above-mentioned operating state detecting means (A3), fuel injection amount calculating means (A4), fuel injection control means (A6), fluctuation cycle calculating means (A8), and electromagnetic spill valve control means (A9) are implemented by the ECU 71. It is configured as a software program to execute.

Next, a fuel injection control process executed by the ECU 71 will be described with reference to FIGS. In the present embodiment, a four-cylinder diesel engine 2 is described as an example. However, in the following description, for convenience of explanation, fuel injection control in one of four cylinders will be described as an example. Will be explained.

The flowchart shown in FIG.
3 shows a fuel injection control process which is a feature of the present invention and is executed by the following. FIG. 6 is a timing chart showing the battery voltage (B), the engine speed (NE), the engine rotation pulse, the drive signal (shown as SPV in the figure) of the electromagnetic spill valve, and the time, respectively.

First, the basic principle of this embodiment will be described with reference to FIG. As described above, at the time of starting, the engine speed is low (for example, 150 rpm or less), and the engine speed fluctuates with TDC (top dead center) as the minimum speed as shown in FIG. 6B. The rotation speed NE _LIM indicated by a dashed line in FIG. 6B indicates a limit at which the rotation speed sensor 35 can detect the engine rotation. That is, when the engine rotation speed is higher than the detection limit rotation speed NE _LIM , the rotation speed sensor 35 can output an engine rotation pulse as shown in FIG. _{When the} engine speed is lower than _LIM , the speed sensor 35 cannot output an engine speed pulse.

On the other hand, paying attention to the fluctuation state of the battery voltage B shown in FIG. 6A, the fluctuation of the battery voltage B is substantially the same as the fluctuation of the engine speed shown in FIG. 6B. In detail, the battery voltage fluctuation is slightly advanced compared to the engine speed fluctuation, but the amount of advance is very small, so that the fluctuation of the battery voltage B is synchronized with the fluctuation of the engine speed. Can be considered to be.

The reason why the fluctuation of the battery voltage B is synchronized with the fluctuation of the engine speed is as follows. That is, when the ignition switch 78 is operated at the time of starting, the starter motor 37 is driven by the battery 38 as a power source and the crankshaft 40 is rotated, but the rotational load of the crankshaft 40 is the cycle (intake, compression) of the diesel engine 2. , Explosion and exhaust processes)
The engine speed (that is, the speed of the crankshaft 40) fluctuates according to the rotational load.

The crankshaft 40 is connected to the starter motor 3
7, the starter motor 37 increases the power consumption to generate a strong rotation torque when the turn end load is large, thereby decreasing the voltage of the battery 38.

Further, since a voltmeter for measuring the voltage B of the battery 38 can generally detect from 0 volt (V), even if the battery voltage B fluctuates, the fluctuation can be reliably detected.

Therefore, in a state where the rotational load increases and the engine speed decreases, the starter motor 37 attempts to generate a strong rotational torque and the battery voltage B decreases, while the rotational load is reduced and the engine speed decreases. Is increased, the driving torque of the starter motor 37 is reduced, and the power consumption is reduced.
Increases. For the reasons described above, the fluctuation of the battery voltage B is synchronized with the fluctuation of the engine speed.

In the present embodiment, attention is paid to the fact that the fluctuation of the battery voltage B is synchronized with the fluctuation of the engine speed as described above, and the fluctuation of the engine speed is estimated from the fluctuation of the battery voltage B. By controlling the opening and closing of the spill valve 23, the fuel injection control is performed in a state close to a state where the engine speed is stable (a state other than the state at the time of starting) even at the time of starting. Things.

Subsequently, based on the basic principle described above, the ECU
FIG. 5 shows the fuel injection amount control process executed by
This will be described with reference to FIG. The fuel injection amount control process shown in the figure is a routine process that is repeatedly executed at predetermined time intervals (for example, every 4 ms) after the engine is started.

When the fuel injection amount control process shown in the figure is started, first, a start-time determination is made in steps 10 to 14 (steps are abbreviated as S in the figure). The starting time in the present embodiment refers to a so-called cranking state, in which the cooling water temperature (THW) is equal to or lower than a predetermined temperature (0 ° C. in the present embodiment).

In step 10, it is determined whether or not the ignition switch 78 is ON (closed). If an affirmative determination is made in step 10, step 12
At step 14, the cooling water temperature THW is read from the water temperature sensor 45, and it is determined whether the cooling water temperature THW read at step 14 is equal to or lower than a predetermined temperature (0 ° C.).

In step 10, the ignition switch 78
Is determined to be OFF (open), it means that the diesel engine 2 is stopped or is not at the time of starting. If it is determined in step 14 that the cooling water temperature THW is equal to or higher than the predetermined temperature, the engine speed is high because the diesel engine 2 is still warm immediately after starting.

Therefore, if a negative determination is made in step 10 or if a negative determination is made in step 14,
Since it is not necessary to perform the start-time fuel injection amount control processing after step 16, the processing is terminated without performing the processing after step 16.

If it is determined in steps 10 to 14 that the diesel engine 2 has started, the process proceeds to step 16. In step 16, the battery voltage B is calculated based on the signal supplied from the battery voltage sensor 39. At this time, the signal supplied from the battery voltage sensor 39 connected to the battery 38 is subjected to a smoothing process for removing noise (for example, using a low-pass filter or the like). This allows
The reliability of the calculated battery voltage B is improved.

As described above, the battery voltage sensor 39 has a wide detection range, and can reliably detect a low voltage. Therefore, even when the engine speed is low and the battery voltage B is accordingly low, the battery voltage B can be reliably detected.

In the following step 18, it is determined based on the battery voltage B obtained in step 16 whether or not the battery voltage B obtained in the current calculation is the minimum value. This minimum determination of the battery voltage B is performed, for example, by calculating the rate of change between the battery voltage B in the previously executed routine processing and the currently obtained battery voltage B for each of the repeatedly executed routine processing. It can be determined from the change state.

If an affirmative determination is made in step 18, that is, if it is determined that the battery voltage B obtained this time is the minimum value, the process proceeds to step 20, where the current battery voltage B is set to the minimum battery voltage. It is stored as the voltage value _Bmin . In step 22, a time when the battery voltage B has reached the minimum battery voltage value _Bmin (this time is referred to as a minimum time _Tmin ) is calculated and stored. The calculation of the minimum time T _min is performed by the CPU 81 based on a clock signal output from a clock 92 built in the ECU 71.

In the following step 24, the electromagnetic spill valve 23
Closing time T _CL is computed for closing the. This valve closing time T
The calculation of _CL is obtained by the following equation.

T _CL = T _min + k · ΔT where T _min : minimum time k: temperature correction coefficient ΔT: conversion time When the electromagnetic spill valve 23 is closed at times other than the start (normal time), generally the TDC is closed. It is configured to be performed when a predetermined time elapses thereafter. TDC is a point at which the engine speed becomes the lowest, and since the fluctuation of the battery voltage B is synchronized with the fluctuation of the engine speed as described above, the time when the minimum battery voltage value B _min is reached, that is, the minimum time T _min
Can be considered as TDC.

Therefore, in the present embodiment, the TD
Minimum time T that can be considered as C _minMore time
The electromagnetic spill valve 23 is closed at the time of passing.
Was. The predetermined time is the above-described valve closing time T._CL(See Figure 6)
See).

The valve closing time T _CL is equal to the cooling water temperature THW.
The higher the cooling water temperature THW, the higher the valve closing time T _CL
Can be lengthened. That is, in the state where the cooling water temperature THW is high, the fuel injection amount may be small unlike at the time of start (at the time of cold), and since the electromagnetic spill valve 23 is opened at a fixed time in the present embodiment as described later. , Cooling water temperature TH
In the case of an engine state where W is high and the fuel injection amount can be reduced, the valve closing time _{TCL is set} to be long.

Specifically, as shown in the equation, the value obtained by adding the time obtained by k · ΔT to the minimum time T _min is defined as the valve closing time T _CL . Here, k is a temperature correction coefficient, which is obtained from a temperature correction map stored in the ROM 81 in advance. FIG. 7 shows a temperature correction map stored in the ROM 81. As shown in the figure, the temperature correction coefficient k is set to increase as the cooling water temperature THW increases. ΔT is a conversion time, and is a value calculated in step 36 described later. The conversion time ΔT is calculated by 1 ° AC (crank angle) calculated based on the fluctuation of the battery voltage B synchronized with the engine speed.
Per hour. The method of calculating the conversion time ΔT will be described in detail in step 36.

[0067] When the valve closing time T _CL is calculated in step 24, the process proceeds to step 26, the current is equal to or a valve closing time T _CL is determined. If it is determined in step 26 that the current time is the valve closing time T _CL , EC
U71 opens the electromagnetic spill valve 23 in step 28. When the electromagnetic spill valve 23 is closed, the fuel compressed by the fuel injection pump 1 is supplied to the diesel engine 2.
And fuel is injected from the fuel injection nozzle 4 into the combustion chambers 44 and 45.

On the other hand, at step 26, the current valve closing time T _CL
If not, the process proceeds to step 30 without opening the electromagnetic spill valve 23, bypassing the process of step 28.

In step 18 described above, the reading is performed.
Judgment that the value of the inserted battery voltage B is not the minimum value
When the valve is closed, when the valve is closed in steps 20 to 28,
Interval T _CLAnd the electromagnetic spill valve 23 is closed.
The process proceeds to step 30 without any further processing.

In step 30, it is determined whether or not the battery voltage B obtained based on the battery voltage B read in step 16 in the current routine processing is the maximum value. The maximum determination of the battery voltage B is performed, for example, in the same manner as the minimum determination in step 18, for example, for each repeatedly performed routine process, the battery voltage B in the previously executed routine and the battery voltage B obtained this time
Can be determined from the change state of the change rate.

If an affirmative determination is made in step 30, that is, if it is determined that the battery voltage B obtained this time is the maximum value, the process proceeds to step 32, where the current battery voltage B value is set to the maximum battery voltage. It is stored as the voltage value _Bmax . In step S22, a time when the battery voltage B reaches the maximum battery voltage value _Bmax (this time is referred to as a maximum time _Tmax ) is calculated and stored. The calculation of the maximum time _Tmax is also performed by the CPU 81 based on the clock signal output from the clock 92 built in the ECU 71.

In the following step 36, the conversion time ΔT is calculated. The conversion time ΔT is a time per 1 ° AC calculated based on the fluctuation of the battery voltage B synchronized with the engine speed as described above. The conversion time ΔT, which is the time per 1 ° AC, is obtained by calculating the minimum time T _min obtained in step 22 and the maximum time T obtained in step 34.
It is calculated based on _max . That is, since the battery voltage fluctuation and the engine speed fluctuation are synchronized, the time at which the minimum battery voltage value B _min corresponds to the time at which TDC occurs, and the time at which the maximum battery voltage value B _max occurs and the engine speed The time when the number is maximum corresponds. Further, in the present embodiment, the 4-cylinder diesel engine 2 is taken as an example, so that the crank angle serving as the TDC and the crank angle providing the maximum engine speed are separated by 90 ° CA.

Therefore, in order to obtain the conversion time ΔT, which is the time per 1 ° AC, the difference between the minimum time T _min , which is the TDC time, and the maximum time T _max , which is the time when the engine speed is maximum, is obtained. And the difference time is divided by 90 °. Therefore, the conversion time ΔT can be obtained by the following equation.

ΔT = (T _max −T _min ) / 90 ° The conversion time ΔT calculated in this way is the minimum time T _min obtained from the battery voltage B corresponding to the current engine rotation state of the diesel engine 2. , Maximum time T
_{Since the} calculation is performed based on _max , the accuracy is very high even at the time of starting.

[0075] As described above, the conversion time ΔT computed in step 36, it is used in the calculation process of the closing time T _CL in step 24 in the stored next routine processing RAM83 of ECU 71. As described above, since the accuracy of the conversion time ΔT calculated in step 36 is high, the valve closing time T calculated in step 24 is high.
The accuracy of _CL can also be improved.

In the following step 38, the electromagnetic spill valve 23
Is opened. By this process, the fuel supply from the fuel injection pump 1 to the combustion chambers 44 and 45 is stopped. That is, in the present embodiment, when the battery voltage B reaches the maximum battery voltage value _Bmax , in other words, when it is estimated that the engine speed has reached the maximum based on the battery voltage fluctuation, the combustion from the fuel injection pump 1 starts. The fuel supply to the chambers 44 and 45 is stopped.

On the other hand, if it is determined in step 30 that the battery voltage B obtained in the current routine is not the maximum value, the process proceeds to step 16.
Then, the processing after step 16 is repeatedly performed.

By performing the above series of processing, the fuel injection is made to correspond to the engine state of the diesel engine 2 as compared with the conventional configuration in which the electromagnetic spill valve is always turned on (closed state) at the time of starting. Injection can be performed intermittently, so that the fuel injection amount and smoke can be reduced, and the cranking torque can be prevented from lowering.

By the way, when an inner cam type fuel injection pump which can pressurize fuel at a higher pressure is used instead of the so-called face cam type fuel injection pump 1 used in this embodiment, the fuel pressure rises. As a result, it is necessary to perform on / off control of the electromagnetic spill valve 23 with higher accuracy.

This is because the amount of fuel injected from the fuel injection nozzle 4 per unit time increases due to the increase in the fuel pressure, and the on / off timing of the electromagnetic spill valve 23 is slightly shifted from the predetermined timing. This is due to the fact that the amount of fuel injected greatly differs from the calculated predetermined injection amount. Therefore, if the electromagnetic spill valve 23 is always in the ON state at the time of starting, the degree of excessive fuel supply becomes extremely large due to the high fuel pressure, and the generation of smoke and the reduction of the cranking rotational speed become a serious problem.

On the other hand, the fuel injection amount control device according to the present invention can intermittently inject the fuel injection amount at the time of starting according to the engine state, and even if a fuel injection pump having a high fuel pressure is employed. Fuel injection amount control at the time of starting can be reliably performed.

In the above-described embodiment, an example has been described in which a battery voltage that fluctuates in synchronization with engine rotation fluctuation is used as a means for estimating engine rotation fluctuation. However, examples of the engine detection amount that changes in synchronization with or in correlation with engine rotation fluctuation include an intake pipe pressure, a combustion pressure, and a back pressure. Accordingly, the diesel engine 2 is provided with an intake pipe pressure sensor, a combustion pressure sensor, a back pressure sensor, and the like, and estimates engine rotation fluctuations based on signals output from these sensors, and performs fuel injection control at startup based on the values. It is good also as a structure which performs.

[0083]

As described above, according to the present invention, fuel injection control can be performed in a state close to a state where the engine speed is stable even at the time of starting, and reduction of smoke can be achieved. It has features such as being able to prevent a decrease in cranking torque.

[Brief description of the drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a schematic configuration diagram illustrating a fuel injection amount control device for a supercharged diesel engine according to an embodiment of the present invention.

FIG. 3 is an enlarged sectional view showing a fuel injection pump according to an embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of an ECU according to an embodiment of the present invention.

FIG. 5 is a flowchart showing a fuel injection control process executed by the ECU.

FIG. 6 is a timing chart for explaining the control principle of the present embodiment.

FIG. 7 is a diagram showing a map used when obtaining a temperature correction coefficient k.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel injection pump 2 Diesel engine 4 Fuel injection nozzle 6 Fuel feed pump 7 Pulser 8 Cam plate 9 Roller ring 10 Cam roller 12 Fuel pressurizing plunger 21 Combustion chamber 22 Spill passage 23 Electromagnetic spill valve 26 Timer device 35 Speed sensor 37 Starter motor Reference Signs List 38 Battery 39 Battery voltage sensor 40 Crankshaft 41 Cylinder 42 Piston 48 Turbocharger 57 Accelerator pedal 58 Throttle valve 71 ECU 73 Accelerator opening sensor 76 Crank angle sensor 81 CPU 82 ROM 83 RAM

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F02D 41/06 380 F02D 41/40

Claims (1)

(57) [Claims] 1. An operating state detecting means for detecting various operating states of an internal combustion engine, comprising: a rotation sensor for outputting a rotation signal at every predetermined crank angle in accordance with the rotation of the internal combustion engine; A fuel injection amount calculating means for calculating a fuel injection amount to the internal combustion engine in accordance with the fuel injection amount calculated by the fuel injection amount calculating means and a rotation signal output from the rotation sensor. A fuel injection control apparatus for an internal combustion engine, comprising: a fuel injection control means for performing opening / closing control and executing fuel injection; a start time detection means for detecting a start time of the internal combustion engine; A rotational fluctuation detecting means; and a rotational fluctuation signal of the internal combustion engine based on a rotational fluctuation signal detected by the rotational fluctuation detecting means when the internal combustion engine is determined to be in a starting state by the starting time detecting means. A variable cycle calculating means for calculating a cycle; and an electromagnetic spill valve control means for controlling opening and closing of the electromagnetic spill valve based on a rotation variable cycle of the internal combustion engine calculated by the variable cycle calculating means. A fuel injection control device for an internal combustion engine.