JPH08254149A - Control device for fuel injection quantity of diesel engine - Google Patents

Abstract

PURPOSE: To facilitate the accurate control of fuel injection quantity by detecting the pressure of fuel pressurized through a plunger when abnormality occurs in a rotary angle pulse generating means, and controlling the valve opening of an electromagnetic spill valve and on the variation of the detected fuel pressure. CONSTITUTION: A fuel injection pump 1 supplys fuel from a fuel supply port 20 to a fuel chamber 21 by driving a fuel feed pump 6 through a driving shaft 5. A plunger 1 is driven forward to pressurize a high pressure chamber 15 for pressure-feeding the fuel from a distributing passage 18 to a fuel injection nozzle. In addition, an electromagnetic spill valve 23 for adjusting the fuel spilling from the high pressure chamber 15 is provided in a spill passage 22, and moreover a rotary angle sensor 35 is attached to the upper part of a roller ring 9 opposite to the outer periphery of a pulser 7. In this case, a fuel pressure detecting sensor 79 is arranged in the spill passage 22, and when abnormality occurs in the rotary angle sensor 35, the valve opening time of the spill valve 23 is set based on a fuel. pressure detection signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection amount control device for a diesel engine, and more particularly to a fuel injection amount control device for a diesel engine which controls a fuel injection amount using an electromagnetic spill valve.

[0002]

2. Description of the Related Art In recent years, a fuel injection amount control device for controlling a fuel injection amount by incorporating an electromagnetic spill valve configured as an electromagnetic valve into a fuel injection pump of a diesel engine and electronically controlling the electromagnetic spill valve has been proposed. It has been put to practical use.
The electromagnetic spill valve is arranged in a spill passage that allows the fuel pressurized by the plunger to communicate with the low-pressure fuel chamber.

When the electromagnetic spill valve is closed (ON), the spill port is closed, the fuel pressurized by the plunger is pumped to the diesel engine for fuel injection, and the electromagnetic spill valve is opened. When turned off, the spill port is opened and the fuel pressurized by the plunger flows into the low pressure fuel chamber, so that the fuel pressure feeding to the diesel engine is stopped and the fuel injection is stopped.

Further, the fuel injection pump has a pulsar which rotates in synchronization with the output shaft of the diesel engine, and a rotation angle sensor which generates a rotation angle pulse at a predetermined rotation angle with the rotation of this pulse. . The fuel injection amount control device configured as a microcomputer is configured to control the opening timing and closing timing of the electromagnetic spill valve based on the rotation angle pulse generated by the rotation angle sensor.

Therefore, the fuel injection amount control device can input the rotation angle pulse output from the rotation angle sensor due to, for example, disconnection of the wiring connecting the rotation angle sensor and the fuel injection amount control device. When it disappears (hereinafter, this state is referred to as a rotation angle pulse fail state), control of the valve opening timing and valve closing timing of the electromagnetic spill valve becomes impossible, and the diesel engine cannot be operated properly.

As a method for solving the above problems, for example, a fuel injection amount control device disclosed in Japanese Patent Laid-Open No. 60-228734 has been proposed. The fuel injection amount control device disclosed in the publication has a TDC sensor that detects the TDC (top dead center) position separately from the rotation angle sensor. When the rotation angle pulse fails, the rotation angle pulse is replaced with the rotation angle pulse. Thus, the valve opening timing and valve closing timing of the electromagnetic spill valve are controlled based on the TDC signal output from the TDC sensor. With this configuration, it is possible to prevent the electromagnetic spill valve from being completely uncontrollable in the rotation angle pulse fail state.

[0007]

However, the TDC signal output from the TDC sensor is 1 at 360 ° CA, for example.
It is configured to be output at a rate of times. Therefore, in the fuel injection amount control device disclosed in the above publication, the reference position that serves as a reference for opening and closing the electromagnetic spill valve in the rotation angle pulse fail state is every 360 ° CA. On the other hand, in the case of a 4-cylinder diesel engine, fuel injection is 180
It is performed for each CA (hereinafter, referred to as one cycle period), and it is necessary to set the valve opening timing and the valve closing timing of the electromagnetic spill valve for each one cycle period.

Therefore, in the configuration in which the opening / closing control of the electromagnetic spill valve is performed based on the TDC signal which is output only once at 360 ° CA, the time between the previous TDC signal output and the current TDC signal output is long and the accuracy is high. There is a problem that a high fuel injection amount control cannot be performed.

The present invention has been made in view of the above points, and when an abnormality occurs in the rotation angle pulse generating means, the fuel pressure of the fuel pressurized by the plunger is detected by the fuel pressure detecting means. By controlling the opening of the electromagnetic spill valve based on this change in fuel pressure, it is possible to perform highly accurate fuel injection amount control even when there is an abnormality in the rotation angle pulse generation means. An object is to provide a fuel injection amount control device for an engine.

[0010]

In order to solve the above problems, according to the present invention, a rotation angle pulse is generated for generating a rotation angle pulse at a predetermined rotation angle using a pulser that rotates in synchronization with an output shaft of a diesel engine. A fuel injection amount control device for a diesel engine, which has a means and which controls at least a fuel injection end timing based on the rotation angle pulse, in a fuel injection amount control device for a diesel engine, comprising a plunger disposed in the fuel injection pump. Fuel pressure detecting means for detecting a fuel pressure in a fuel path formed between the electromagnetic spill valve, abnormality detecting means for detecting an abnormality of the rotation angle pulse generating means, and the rotation angle by the abnormality detecting means. When it is detected that an abnormality has occurred in the pulse generating means, the spill valve opening time is set based on the fuel pressure signal output by the fuel pressure detecting means. Serial in which characterized in that a and abnormality control means for performing opening control of the electromagnetic spill valve.

[0011]

In the fuel injection amount control device for a diesel engine configured as described above, when the rotation angle pulse generating means becomes unable to output the rotation angle pulse due to disconnection or the like (rotation angle pulse fail state), the abnormality detecting means operates. The occurrence of this abnormality is detected.

Further, when the abnormality detecting means determines that the rotation angle pulse fail condition has occurred, the abnormality controlling means determines the fuel pressure feeding start time from the fuel pressure change detected by the fuel pressure detecting means, and this fuel pressure feeding The opening control of the electromagnetic spill valve is performed based on the spill valve opening time set based on the start time. That is, in the rotation angle pulse fail state,
The valve opening control of the electromagnetic spill valve is performed based on the fuel pressure detected by the fuel pressure detection means.

Further, the fuel pressure detecting means is constructed so as to detect the fuel pressure in the fuel path formed between the plunger arranged in the fuel injection pump and the electromagnetic spill valve.
Therefore, the fuel pressure signal output from the fuel pressure detection means is
The signal reflects the fuel pressurization state of the actual plunger.

Further, the plunger is driven by a cam provided on the drive shaft of the fuel injection pump, and therefore the cam lift state of the plunger (that is, the fuel pressurization state by the plunger) is the rotational state of the fuel injection pump. It reflects. Further, the pressurization of the fuel by the plunger is performed in each cycle of the diesel engine, and therefore, for example, in the case of a 4-cylinder diesel engine, 180 ° C.
It is output every A.

The abnormal time control means sets the spill valve opening time based on the fuel pressure signal which reflects the rotational state of the fuel injection pump as described above and which is periodically generated in each cycle of the diesel engine. Controls the opening of the electromagnetic spill valve.
Therefore, it is possible to perform highly accurate fuel injection amount control that reflects the engine state even in the rotation angle pulse fail state.

[0016]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a fuel injection amount control device of a diesel engine with a supercharger in the present embodiment, and FIG. 2 is an enlarged sectional view of a distribution type fuel injection pump 1.

The fuel injection pump 1 is a diesel engine 2
The drive pulley 3 is drivingly connected to the crankshaft 40 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.
A fuel feed pump (developed by 90 degrees in this figure) 6 formed of 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. On the outer peripheral surface of the pulsar 7, as many cutting teeth as the number of cylinders of the diesel engine 2, that is, four cutting teeth in this embodiment, are formed at equal angular intervals,
In addition, the crank angle between each incisor is 7.5 °, for example.
Protrusions (teeth) are formed at equal angular intervals for each CA. 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 roller ring 9 is provided between the pulsar 7 and the cam plate 8, and a plurality of cam rollers 10 are mounted along the circumference of the roller ring 9 so as to face the cam face 8a of the cam plate 8. 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 the coupling, the cam plate 8 rotates and engages with the cam roller 10 to reciprocate in the left-right direction in the figure by the same number as the number of cylinders. Driven. Also, the plunger 12 is reciprocally driven in the same direction while rotating with the reciprocating motion.

That is, the cam face 8 of the cam plate 8
The plunger 12 is moved forward (lifted) when a rides on the cam roller 10 of the roller ring 9, and conversely, the plunger 12 is moved back when the cam face 8a rides 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 end surface of the plunger 12 and the bottom surface of the cylinder 14. Further, suction grooves 16 and distribution ports 17 as many as the number of cylinders of the diesel engine 2 are formed on the outer periphery of the tip end side of the plunger 12. A distribution passage 18 and a suction port 19 are formed in the pump housing 13 so as to correspond to the suction groove 16 and the distribution port 17.

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 to 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, the fuel is pressure-fed and injected from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder.

In the pump housing 13, a spill passage 22 (fuel passage) for fuel overflow (spill) that connects the high pressure chamber 15 and the fuel chamber 21 is formed. An electromagnetic spill valve 23 as an overflow adjusting valve for adjusting the 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 in the non-energized state (SPV off), the valve body 25 is opened and the fuel in the high pressure chamber 15 is filled with fuel.
Be spilled. In addition, the coil 24 is energized (SPV o
n), the valve body 25 is closed and the high pressure chamber 1
The fuel spill from 5 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 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, during the forward movement of the plunger 12, by controlling the closing / opening timing of the electromagnetic spill valve 23, the fuel injection amount from the fuel injection nozzle 4 is controlled.

Below the pump housing 13 is provided a timer device (developed 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 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 driven by hydraulic pressure, and has 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. The position of the timer piston 28 is determined by the equilibrium relationship 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 position of the roller 1 is determined via the cam plate 8.
2 reciprocating timing is determined.

In order 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 communicate with each other through the communication passage 34.
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 is controlled by a duty-controlled energization signal, and the fuel pressure in the pressurizing chamber 30 is adjusted by the opening and closing control of the timing control valve 33. 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 angle sensor 35 as an engine rotation detecting means composed of an electromagnetic pickup coil is attached so as to face the outer peripheral surface of the pulsar 7. The rotation angle sensor 35 detects a change in magnetic flux that changes when a protrusion of the pulsar 7 or the like crosses, and outputs a timing signal corresponding to the engine speed NE, that is, an engine rotation pulse as a rotation angle signal for each predetermined crank angle. Is output. Further, since the rotation angle 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,
Each of the main combustion chambers 44 is connected to an auxiliary fuel chamber 45 that is also provided corresponding to each cylinder. Then, the fuel injected from each fuel injection nozzle 4 is supplied to each auxiliary combustion chamber 45. Further, a well-known glow plug 46 as a starting assisting 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 compressor 49 of a turbocharger 48 constituting a supercharger, and the exhaust pipe 50 is provided with a turbocharger. Forty eight turbines 51 are provided. Also, the exhaust pipe 50 has
Wastegate valve 52 for adjusting supercharging pressure PIM
Is provided.

As is well known, this turbocharger 48
Uses the energy of the exhaust gas to rotate the turbine 51, and to rotate the compressor 49 on the same axis to increase the pressure of the intake air. As a result, a dense air-fuel mixture 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.

Further, the diesel engine 2 has an exhaust pipe 5
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in 0 to the intake port 53 of the intake pipe 47. An exhaust gas recirculation valve (EGR valve) 55 for adjusting the recirculation amount of exhaust gas is provided in the middle of the recirculation pipe 54. The EGR valve 55 is opened / closed by controlling a vacuum switching valve (VSV) 56.

Further, in the middle of the intake pipe 47, an intake throttle valve 58 which is opened / closed in association with the depression amount of the accelerator pedal 57.
Is provided. Further, a bypass passage 59 is provided in parallel with the intake throttle valve 58, and a bypass throttle valve 60 is provided in the bypass passage 59.

This bypass throttle valve 60 has two VSVs.
Opening and closing are controlled by an actuator 63 having a two-stage diaphragm chamber driven by the control of 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.

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

As a sensor for detecting the operating state, the following various sensors are provided in addition to the rotation angle sensor 35. That is, the intake pipe 47 is provided with an intake air temperature sensor 72 for detecting the intake air temperature THA near the air cleaner 64. Further, an accelerator opening sensor 73 for detecting an accelerator opening ACCP corresponding to the load of the diesel engine 2 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.

The cooling water temperature T of the diesel engine 2
A water temperature sensor 75 that detects HW and an ignition switch 78 that is operated when starting and stopping the diesel engine 2 are provided. Further, a crank angle sensor 76 for detecting a rotation reference position of the crankshaft 40 of the diesel engine 2, for example, a rotation position of the crankshaft 40 with respect to a top dead center of a specific cylinder is provided. Further, the transmission (not shown) is provided with a vehicle speed sensor 77 for detecting the vehicle speed (vehicle speed) SP by turning on / off the reed switch 77b by a magnet 77a rotated by the rotation of the gear.

Further, the spill passage 22 is provided with a fuel pressure detecting sensor 79 which serves as fuel pressure detecting means. The disposition position of the fuel pressure detection sensor 79 in the spill passage 22 is selected between the plunger 12 and the electromagnetic spill valve 23. That is, it is arranged in a substantial fuel pressurizing chamber until it is pressurized by the plunger 12 and distributed to the distribution passage 18. Further, the fuel pressure detection sensor 79 is, for example, a piezoelectric conversion element such as a piezoelectric element, and the spill passage 2
The fuel pressure in 2 is detected to generate a fuel pressure signal.

As described above, since the fuel pressure detection sensor 79 is arranged between the plunger 12 of the spill passage 22 and the electromagnetic spill valve 23, that is, in the substantial fuel pressurizing chamber in the pump, the plunger 12 is provided. When the fuel is pressurized by the cam plate 8 to pressurize the fuel in the high pressure chamber 15, this fuel pressure is detected by the fuel pressure detection sensor 79. Further, by providing the sensor in the fuel pressurizing chamber system in the pump, only one sensor is required, and the cost can be reduced as compared with the case where one sensor is provided in each fuel pipe of each cylinder.

Each sensor and switch 35, 72 described above
To 79 are connected to the ECU 71, respectively. EC
U71 is each sensor and switch 35, 72-7 described above.
The electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, the VSVs 56, 61, 62 and the like are suitably controlled on the basis of the signal output from 9.

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 the calculation result of the CPU 81, a backup RAM 84 for storing prestored data, a clock 92 for generating a predetermined clock signal, and the like, and these units and the input port 85. And the output port 86 and the like are connected by a bus 87 as a logical operation circuit.

At the input port 85, the intake air temperature sensor 72, the accelerator angle sensor 73, the intake air pressure sensor 74, and the water temperature sensor 75 are connected to the buffers 88, 89, 90, 9 respectively.
1, the multiplexer 93, and the A / D converter 94. Similarly, in the input port 85, the rotation angle sensor 35, the crank angle sensor 76, the vehicle speed sensor 77, and the fuel pressure detection sensor 79 described above, and the waveform shaping circuit 95.
Connected through. The ignition switch 78 is also connected to the input port 85.

Then, the CPU 81 controls the sensors and switches 35, 72 to 79 input through the input port 85.
The detection signal such as is read as an input value. In addition, the output port 86 is provided with each drive circuit 96, 97, 98, 99, 100,
Via the electromagnetic spill valve 23, the timing control valve 33, the glow plug 46 and the VSV 56, 6
1, 62 and the like are connected.

Then, the CPU 81, based on the input values read from the respective sensors and the switches 35, 72 to 79, the electromagnetic spill valve 23, the timing control valve 33,
The glow plug 46 and the VSVs 56, 61, 62 and the like are preferably controlled. Next, the fuel injection amount control process executed by the ECU 71 described above will be described with reference to FIGS. 4 to 9. 4 to 7 are flowcharts showing the fuel injection amount control processing, and FIG. 8 shows the engine rotation pulse output from the rotation angle sensor 35, the drive signal of the electromagnetic spill valve 23 (indicated by SPV in the drawings), and fuel pressure detection. 6 is a timing chart showing an output signal of the sensor 79 and a cam diagram of a pump cam lift, respectively.

First, the basic principle of this embodiment will be described with reference to FIG. A condition in which an abnormality such as a wire breakage has not occurred in the wiring connecting the rotation angle sensor 35 and the ECU 71, and therefore an engine rotation pulse signal (hereinafter referred to as NE signal) generated by the rotation angle sensor 35 can be supplied to the ECU 71 (hereinafter In the normal state), the ECU 71 is configured to control the opening timing and the closing timing of the electromagnetic spill valve 23 based on the NE signal generated by the rotation angle sensor 35 (hereinafter, the ECU 71 executes in the normal state). Control processing is called normal processing).

However, if an abnormality such as disconnection occurs at the time indicated by the arrow in FIG. 8A, the NE signal is not input to the ECU 71 after the abnormality occurs as shown in FIG. Based on electromagnetic spill valve 2
It becomes impossible to perform the valve opening timing and the valve closing timing of 3.

Here, pay attention to the fuel pressure signal output by the fuel pressure detection sensor 79 shown in FIG. 8C and the pump cam lift shown in FIG. 8D. As described above, since the fuel pressure detection sensor 79 is disposed between the plunger 12 of the spill passage 22 and the electromagnetic spill valve 23, the fuel pressure of the fuel pressurized in the high pressure chamber 15 by the plunger 12 is It can be detected by the fuel pressure detection sensor 79.
That is, the fuel pressure signal output from the fuel pressure detection sensor 79 is a signal reflecting the actual fuel pressurization state by the plunger 12.

Further, the plunger 12 is the fuel injection pump 1
Is driven by a cam plate 8 provided on the drive shaft 5, and therefore the cam lift state of the plunger 12 (that is, the fuel pressurization state by the plunger 12) reflects the rotation state of the drive shaft 5. This point can also be understood from the fact that the output timing of the fuel pressure detection sensor 79 shown in FIG. 8C and the timing when the pump cam lift amount rises shown in FIG. 8D are synchronized.

As is clear from the above description, the fuel pressure signal output from the fuel pressure detection sensor 79 is a signal reflecting the rotation state of the drive shaft 5. Therefore, by performing the valve opening / closing control of the electromagnetic spill valve 23 based on the fuel pressure signal output from the fuel pressure detection sensor 79, highly accurate fuel injection reflecting the engine state even in the rotation angle pulse fail state. It is possible to control the quantity.

In this embodiment, the fuel pressure detection sensor 7
The valve opening timing and valve closing timing of the electromagnetic spill valve 23 are set with reference to the rising timing of the fuel pressure signal output from 9. Further, since the pressurization of the fuel by the plunger 12 is carried out for each cycle of the diesel engine 2, in the case of the present embodiment, it is outputted every 180 ° CA. Therefore, the fuel pressure signal output from the fuel pressure detection sensor 79 is also output every 180 ° CA. Therefore, the fuel pressure signal, which serves as a reference for setting the valve opening timing and valve closing timing of the electromagnetic spill valve 23, is output for each relatively short crank angle, so that the influence of engine speed fluctuation is influenced by the valve opening timing of the electromagnetic spill valve 23. Also, it is possible to suppress the influence on the setting of the valve closing timing, which also makes it possible to perform the fuel injection amount control with high accuracy.

Next, based on the above-mentioned basic principle, the ECU
Regarding the fuel injection amount control processing executed by 71 in FIG.
It will be described with reference to FIGS. First, the flowchart shown in FIG. 4 will be described. The process shown in the figure is an interrupt process (NE interrupt process) each time the rotation angle sensor 35 outputs a NE pulse.

When the fuel injection amount control process shown in the figure is started, first in step 100, the ECU 71 determines the NE pulse interval T based on the NE signal generated by the rotation angle sensor 35.
Computes NINT and NE interrupt counter CNIR
Increment Q. Here, the NE pulse interval T
NINT is an interval (time) from the time when the previous NE pulse is input to the time when the current NE pulse is input, and the NE interrupt counter CNIRQ is detected by the rotation angle sensor 35 after detecting the missing tooth. This shows the number of NE pulses (the NE interrupt counter CNIRQ is cleared by the input of the missing tooth).

In step 100, the NE fail counter CNEF is cleared (CNEF = 0). The NE fail counter CNEF is a counter that is automatically incremented every predetermined time (for example, every 4 ms). As shown in step 100, since the NE fail counter CNEF is cleared each time the NE signal is generated, the NE fail counter CNEF can be defined as the elapsed time after the NE signal is input.

In the following step 102, it is determined whether or not the rotation angle sensor 35 is abnormal (that is, whether or not the rotation angle pulse is in a fail state) by determining whether or not the missing tooth is normally determined. judge. As described above, the pulsar 7 is provided with the number of missing teeth corresponding to the number of cylinders, and a predetermined number (7.5 ° CA) is provided between the adjacent missing teeth.
21 teeth when formed at intervals). Therefore, in the normal state, 21 NE pulses (CNIRQ) are output from the rotation angle sensor 35 in one cycle.
= 0-20) is output. However, when an abnormality such as disconnection occurs in the rotation angle sensor 35, the rotation angle sensor 3
From 5, the NE pulse is no longer output.

Therefore, in step 102, step 1
It is determined whether or not the NE pulse interval TNINT calculated by 00 is a predetermined time, and whether or not the value of the NE interrupt counter CNIRQ in the routine process before inputting the missing tooth is CNIRQ = 20.

That is, in the rotation angle pulse fail state, so-called pulse omission may occur between the omissions even if the omission of teeth is detected. When the omission of pulses occurs, the NE pulse interval TNINT is It becomes longer than a predetermined time, and the value of the final NE interrupt counter CNIRQ in one cycle becomes less than 20 (because the missing pulse portion is not counted). Therefore, the NE pulse interval TN
From the values of the INT and NE interrupt counters CNIRQ, it is possible to determine whether or not an abnormality has occurred in the rotation angle sensor 35.

In step 102, the rotation angle sensor 35
When it is determined that the abnormality has occurred in step 104, the process proceeds to step 104, and the fail flag XFNE indicating that the abnormality has occurred in the rotation angle sensor 35 (rotation angle pulse fail state) is set (XFNE = ON), and the process ends.

On the other hand, if it is determined in step 102 that no abnormality has occurred in the rotation angle sensor 35, the process proceeds to step 106 to open / close the electromagnetic spill valve 23 based on the NE pulse output from the rotation angle sensor 35. A normal process for controlling is executed, and the NE interrupt process shown in FIG.

Next, the flowchart shown in FIG. 5 will be described. The process shown in the figure is a main routine of the fuel injection amount control process. When the fuel injection amount control process shown in the figure is started, first, at step 200, it is judged if the engine state is the cranking state. Specifically, it is determined whether the start signal output from the ignition switch 78 is input.

Then, in step 200, the start signal of the ignition switch 78 is turned on (STA ON).
If the NE fail counter CNEF described in step 100 of FIG. 4 is 2 sec or more, it is determined whether the NE fail counter CNEF is 2 seconds or more.

As described above, the NE fail counter C
Since the NEF is a counter that is cleared by the input of the NE pulse, when the value of the NE fail counter CNEF is large (that is, when the NE fail counter CNEF is not cleared within a predetermined time), an abnormality occurs in the rotation angle sensor 35. It is determined that the pulse is not input (rotation angle pulse fail state), and the fail flag XFN is determined in step 206.
E is set (XFNE = ON), and the process is step 20.
Proceed to 8. If it is determined in step 202 that the NE fail counter CNEF is less than 2 seconds, the process proceeds to step 208 without performing the process of step 206.

On the other hand, in step 200, the start signal of the ignition switch 78 is turned off (STA OFF).
If it is determined to be N, the process proceeds to step 204, where N
It is determined whether the E-fail counter CNEF is 0.1 sec or more. And the NE fail counter CNE
When the value of F is 0.1 sec or more, the rotation angle sensor 35
When it is determined that the NE pulse is not input (rotation angle pulse fail state) due to an abnormality occurring in step 206, step 206
Set the fail flag XFNE (XFNE = O
N) and the process proceeds to step 208. If it is determined in step 204 that the NE fail counter CNEF is less than 0.1 sec, the process proceeds to step 208 without performing the process of step 206.

In the above steps 200 to 206, the time for judging the rotation angle pulse fail state is changed depending on whether the engine state is the cranking state or not. The reason is that the engine state is the cranking state. Indicates that the output interval of the NE pulse becomes long due to the slow rotation of the drive shaft 5, and the rotation of the drive shaft 5 is faster than that during cranking when the engine state is not in the cranking state (when the engine is operating). Therefore N
This is because the E pulse output interval becomes shorter.

Incidentally, step 10 shown in FIG. 4 described above.
2 and step 104, step 200 shown in FIG.
~ Step 206 constitutes an abnormality detecting means. In step 208, it is determined whether the fail flag XFNE set in steps 104 and 206 is set, that is, whether the rotation angle sensor 35 has an abnormality. Then, if it is determined in step 208 that the rotation angle sensor 35 is abnormal and the current engine state is the rotation angle pulse fail state, the process proceeds to step 210.

In step 210, the spill valve opening time TS for opening the electromagnetic spill valve 23 is determined by the fail processing engine speed NESUB calculated in step 300 of FIG. 6 described later and the accelerator opening ACCPF.
Calculate PNEF1. Here, the engine speed NESUB for fail processing is the engine calculated based on the time between the rising time of the previous fuel pressure signal output from the fuel pressure detection sensor 79 and the rising time of this fuel pressure signal. It is the number of rotations. Also, the spill valve opening time T
SPNFF1 can be obtained from a two-dimensional map having the engine speed NESUB for fail processing and the accelerator opening ACCPF shown in FIG. 9 as parameters. still,
Spill valve opening time TSPN obtained in step 210
EF1 is the time from the rising time of the fuel pressure signal to the time of opening the electromagnetic spill valve 23.

When the spill valve opening time TSPNF1 is obtained in step 210 as described above, and the fail flag XFNE is not set in step 208 (that is, the rotation angle pulse fail state is not established).
If it is determined, the fuel injection amount control process shown in FIG. 5 ends.

Next, the flowchart shown in FIG. 6 will be described. The process shown in the figure is a process interrupted when the fuel pressure signal generated by the fuel pressure detection sensor 79 rises. When the fuel injection amount control process shown in the figure is started, first, at step 300, the fail processing engine speed NESUB is calculated. As described above, the engine speed NESUB for fail processing is the time between the rising time of the previous fuel pressure signal output from the fuel pressure detection sensor 79 and the rising time of this fuel pressure signal (FIG. 8). Is denoted by T). As described above, since the fuel pressure signal is output once in one cycle, this time T is approximately equal to the time required for one cycle, and therefore the engine speed can be estimated from the time T.

In the following step 302, it is judged whether or not the fail flag XFNE is set (that is, whether or not the rotation angle pulse is in a fail state). If it is determined in step 302 that the current rotation angle pulse is in a fail state, the process proceeds to step 304, and the spill valve opening time TSPNFE1 calculated in step 210 of the process shown in FIG. 5 elapses. After waiting for, the electromagnetic spill valve 23 is opened (SPV off). As a result, fuel injection is stopped.

As described above, the spill valve opening time TSP
NEF1 is the time from the rising time of the fuel pressure signal to the time of opening the electromagnetic spill valve 23. Further, the processing of FIG. 6 is interrupted when the fuel pressure signal rises. Therefore, the electromagnetic spill valve 23 is opened (SPV of off after waiting for elapse of the spill valve opening time TSPNF1).
By performing f), it is possible to perform fuel injection of an amount extremely close to the target fuel injection amount. When the processing of step 304 ends, or when it is determined in step 302 that the current rotation angle pulse is not in a fail state, the process shown in FIG.
The fuel injection amount control process shown in is ended.

Next, the flowchart shown in FIG. 7 will be described. The process shown in the figure is performed by the electromagnetic spill valve 23.
Is a process that is interrupted when the valve is opened (SPV off) or when the electromagnetic spill valve 23 is closed (SPV on). When the fuel injection amount control process shown in the figure is started, first, at step 400, it is judged if it is the time to open the electromagnetic spill valve 23 (SPV off). Then, when it is determined in step 400 that the current time is to open the electromagnetic spill valve 23 (SPVoff), the process proceeds to step 402, and FIG.
The spill valve opening time TSPNF2 for closing the electromagnetic spill valve 23 (SPV on) based on the fail processing engine speed NESUB calculated in step 300 shown in FIG.
Is calculated.

Generally, the electromagnetic spill valve 23 is closed (SPV
The electromagnetic spill valve 23 is closed (SPV o) because it may be turned on before the fuel is pumped by the cam.
The timing of n) may be less accurate than the timing of opening the electromagnetic spill valve 23. For this reason, in this embodiment, the timing for closing the electromagnetic spill valve 23 (SPV on) is determined by a one-dimensional map (not shown) using the fail processing engine speed NESUB as a parameter.

When the spill valve opening time TSP NEF2 is obtained in step 402, the process proceeds to step 404.
And the electromagnetic spill valve 23 is closed (SPV on) after waiting for the spill valve opening time TSPNF2 to elapse.
As a result, fuel injection is started.

Incidentally, steps 208 and 21 shown in FIG.
0 and the processing shown in FIGS. 6 and 7 constitute an abnormal time control means. As described above, according to the present embodiment, based on the fuel pressure signal that reflects the rotational state of the fuel injection pump 1 and that is periodically generated in each cycle of the diesel engine 2, the spill valve opening time TSPNF1 and the spill valve are set. Valve closing time T
Since the SPNEF 2 is set to control the electromagnetic spill valve 23, it is possible to perform highly accurate fuel injection amount control that reflects the engine state even in the rotation angle pulse fail state.

In the above embodiment, the electromagnetic spill valve 23 is controlled based on the fuel pressure signal output from the fuel pressure detection sensor 79 in the rotation angle pulse fail state. However, even if a lift sensor capable of detecting the lift state of the plunger 12 is provided in place of the fuel pressure detection sensor 79 and the electromagnetic spill valve 23 is controlled based on the output of this lift sensor, the same configuration as in the above-described embodiment is obtained. The effect can be realized.

It is also conceivable to use a nozzle lift sensor instead of the fuel pressure detection sensor 79 for the lift state of the nozzle provided in the fuel injection nozzle. However, in this configuration, the nozzle lift sensor must be provided in all the cylinders, which increases the cost. Further, since the injection pipe arranged between the fuel injection pump 1 and the engine 2 is long, the rise of the signal output by the nozzle lift sensor is delayed with respect to the rise timing of the fuel pressure, and the accuracy is high. It becomes impossible to control. Therefore, it seems that the structure using the fuel pressure detection sensor 79 as in the present embodiment is more advantageous than the structure using the nozzle lift sensor.

[0081]

As described above, according to the present invention, there is a feature that the fuel injection amount control can be performed with high accuracy even when an abnormality occurs in the rotation angle pulse generating means.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a fuel injection amount control device for an over-payment diesel engine that is an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a fuel injection pump in one embodiment of the present invention.

FIG. 3 is a block diagram showing a configuration of an ECU in one embodiment of the present invention.

FIG. 4 is a fuel injection control process (N
It is a flow chart which shows E interruption processing.

FIG. 5 is a flowchart showing a fuel injection control process (main routine) executed by the ECU.

FIG. 6 is a flowchart showing a fuel injection control process (fuel pressure signal rising interrupt process) executed by the ECU.

FIG. 7 is a flowchart showing a fuel injection control process (electromagnetic spill valve opening and closing interrupt process) executed by an ECU.

FIG. 8 is a timing chart for explaining the control principle of the present embodiment.

FIG. 9 is a diagram showing a map used when determining a spill valve opening time TSPNFF1.

[Explanation of symbols]

 1 Fuel Injection Pump 2 Diesel Engine 4 Fuel Injection Nozzle 6 Fuel Feed Pump 7 Pulsar 8 Cam Plate 9 Roller Ring 10 Cam Roller 12 Fuel Pressurizing Plunger 21 Combustion Chamber 22 Spiral Channel 23 Electromagnetic Spill Valve 26 Timer Device 35 Rotation Angle Sensor 40 Crankshaft 41 cylinder 42 piston 48 turbocharger 57 accelerator pedal 58 intake throttle valve 71 ECU 73 accelerator opening sensor 76 crank angle sensor 79 fuel pressure detection sensor 81 CPU 82 ROM 83 RAM

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location F02M 41/12 310 F02M 41/12 310Z 350 350A

Claims (1)

[Claims] 1. A rotation angle pulse generating means for generating a rotation angle pulse for each predetermined rotation angle using a pulser rotating in synchronization with an output shaft of a diesel engine, and at least fuel injection termination based on the rotation angle pulse. In a fuel injection amount control device for a diesel engine equipped with an electromagnetic spill valve fuel injection pump for controlling the timing, in a fuel path formed between the plunger arranged in the fuel injection pump and the electromagnetic spill valve, Fuel pressure detection means for detecting fuel pressure, abnormality detection means for detecting abnormality of the rotation angle pulse generation means, and when the abnormality detection means detects that abnormality has occurred in the rotation angle pulse generation means An abnormal condition control means for setting a spill valve opening time based on a fuel pressure signal output from the fuel pressure detection means and performing valve opening control of the electromagnetic spill valve. A fuel injection amount control device for a diesel engine, comprising: