JP3195479B2 - Fuel injection control system for diesel 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 amount control device for a diesel engine, and more particularly to a fuel injection amount control device for a diesel engine which controls the fuel injection amount by controlling the driving of a spill valve.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection pump of an electronically controlled diesel engine, a spill port is controlled by, for example, an electromagnetic spill valve or the like so that a fuel injection amount obtained according to a lift of a plunger thereof becomes a target value. I am trying to open it. Thus, the fuel from the plunger high-pressure chamber overflows (spills) into the combustion chamber, and the end of fuel pumping (that is, the end of fuel injection) is controlled to obtain a required fuel injection amount.

[0003] In such an electromagnetic spill valve, a target spill angle is usually converted into a time by a signal synchronized with the lift of the plunger and input at a constant pump rotation angle, for example, an engine rotation pulse and an average engine rotation speed. The target spill position is determined based on the target spill position, and on / off control of the electromagnetic spill valve is performed based on the target spill position.

For example, in the technique disclosed in Japanese Patent Application Laid-Open No. 62-267547, an electromagnetic spill is performed at a target spill position corresponding to the injection end timing in order to obtain a fuel injection amount determined according to the current operation state. The spill port is opened by opening the valve. Here, in order to determine the target spill position, the pulse count number from a reference position of the engine rotation pulse to the target spill position is calculated based on the engine rotation pulse obtained at every constant crank angle, and the pulse count for one pulse is calculated. Find the remainder angle. The remaining angle is time-converted based on the required time for one pulse including the previous spill position (spill-time pulse time).

[0005]

However, according to the above-mentioned prior art, when the rotation fluctuation of the engine is large, the difference in the spill pulse time becomes large. For example, if the instantaneous rotational speed around the current target spill position is lower than the previous instantaneous rotational speed around the spill position, the current spill pulse time is longer than the previous spill pulse time. Become.

Therefore, when the surplus angle is converted into time based on the previous spill pulse time obtained in such a state where the rotation fluctuation is large, the time conversion error becomes very large, and the fuel injection amount becomes large. Control accuracy may be degraded. In addition, due to the deterioration of the accuracy of the fuel injection amount control, there is a possibility that the rotation of the engine is further induced to lower the output.

The present invention has been made in view of the above points, and the spill pulse time, which is a reference when converting the surplus angle into time, is set to the pulse time immediately before the engine rotation pulse including the current spill position or 180 degrees. Provided is a fuel injection amount control device for a diesel engine, which performs an operation based on a pulse time before the previous one or a pulse time before the previous one 720, thereby improving the accuracy of the fuel injection amount control without being affected by engine rotation fluctuation. The purpose is to.

[0008]

FIG. 1 is a diagram illustrating the principle of the present invention. As shown in the figure, the present invention is characterized by taking the following means in order to solve the above problems.

According to the first aspect of the present invention, a diesel engine
A fuel injection pump (A3) that pressurizes fuel by a driving force generated by (A1), and pressure-feeds the pressurized fuel to a diesel engine (A1) while controlling a fuel injection amount by a spill valve (A2);
A spill position calculating means (A4) for calculating a valve opening timing of the spill valve (A2) corresponding to at least a fuel injection end timing based on a fuel injection amount determined according to an operation state of the diesel engine (A1); Based on the engine rotation detecting means (A5) which outputs an engine rotation pulse at every constant crank angle of the diesel engine (A1) and the engine rotation pulse output from the engine rotation detecting means (A5) at every constant crank angle, A count number from the reference position to the spill position of the engine rotation pulse and a remainder angle calculation means (A6) for calculating a remainder angle less than one pulse, and a pulse time for one engine rotation pulse. Based on the pulse time calculating means (A7) and the pulse time of the engine rotation pulse sandwiching the spill position calculated by the pulse time calculating means (A7), The remainder angle time conversion means a remainder angle is calculated by the calculation means (A6) for calculating a time-converted odd angle time (A8), the pulse time calculating means (A
Pulse time storage means (A9) for storing the pulse time calculated by (7), the count number from the reference position to the spill position calculated by the surplus angle calculation means (A6), and the surplus angle time conversion means ( A8) a spill valve control means (A10) for controlling the drive of the spill valve (A2) at a time timing determined based on the remaining angle time calculated by (A8). ), the above path
This time stored in the
At least one more than the engine rotation pulse including
Surplus angle based on the pulse time of the previous engine rotation pulse
While calculating the time, the pulse time storage means (A9)
Engine times including the spill position that is stored this time
720 degrees before crank angle
Cylinder fixed based on the pulse time of the engine rotation pulse
Compensate for engine speed fluctuations caused by machine errors
Calculate the same cylinder correction amount, which is the correction value to correct, and calculate the remainder
The angle time is corrected by the same cylinder correction amount.
It is characterized by the following.

[0010]

[0011]

In the fuel injection amount control device for a diesel engine configured as described above, since the pulse time calculation means (A7) and the pulse time storage means (A9) are provided, the calculation is performed by the pulse time calculation means (A7). The stored pulse time can be stored in the pulse time storage means (A9).

For this reason, the surplus angle time conversion means (A8)
Is the current time stored in the pulse time storage means (A9).
Less than the engine rotation pulse including the spill position
Based on the pulse time of the previous engine rotation pulse.
Calculation of the angle time, and pulse time storage means (A
The engine containing the spill position found this time stored in 9)
720 degrees before crank rotation pulse
Based on the pulse time of the engine rotation pulse at
Engine rotation fluctuations caused by cylinder-specific equipment errors
The same cylinder correction amount, which is a correction value for correcting
Becomes possible. Then, the obtained extra angle time is the same
By correcting with the cylinder correction amount, variations between cylinders
Key is suppressed, and the remaining angular time after correction
The effect of fluctuation is eliminated, and the actual extra angle time
It will be a close value. Therefore, the accuracy of the fuel injection amount is improved.
be able to.

The above-described engine rotation fluctuation does not suddenly occur from a certain engine rotation pulse but gradually occurs depending on the engine state. Therefore, the pulse time of the engine rotation pulse including the spill position obtained this time (pulse time at the time of spill) is very similar to the pulse time of the engine rotation pulse immediately before the pulse at the time of the spill, and the influence of the engine rotation fluctuation is almost eliminated. It is time not to receive.

[0014]

[0015]

[0016]

[0017]

[0018]

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 amount control device for a supercharged diesel engine according to this embodiment. FIG. 3 is a sectional view showing the distribution type fuel injection pump 1. 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. The fuel injection pump 1 is driven by the rotation of the drive pulley 3, and the fuel is injected under pressure 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 pulser 7 is attached to the base end side of the drive shaft 5. The outer surface of the pulsar 7 has a diesel engine 2
In this case, four incisors are formed at equal angular intervals, that is, in this case, four incisors are formed at equal angular intervals between the incisors at every 3.75 degrees as a clamp angle. 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 (four in this embodiment). The cam plate 8 is always urged and engaged with the cam roller 10 by the spring 11.

A base end of a fuel pressurizing plunger 12 is attached to the cam plate 8 so as to be integrally rotatable. 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 plunger 12 is moved forward (lift) while 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 while the cam face 8a rides down the cam roller 10.

The plunger 12 is inserted 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.

Then, 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 process 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 step in which the plunger 12 moves forward and the high-pressure chamber 15 is pressurized, the fuel is pressure-fed from the distribution passage 18 to the fuel injection nozzle 4 for 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 fuel chamber 12. 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 process 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, a timer device (developed at 90 degrees in this figure) 26 for adjusting the fuel injection timing is provided. 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, and includes a timer housing 27, a timer piston 28 inserted in the housing 27, and a timer piston 28 in a low pressure chamber 29 on one side of the timer housing 27. And a timer spring 31 for urging the pressure to the other pressure chamber 30. 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 composed of an electromagnetic pickup coil is attached to face the outer peripheral surface of the pulser 7. The rotation speed sensor 35 detects the passage of a projection or the like of the pulsar 7 when the projection or the like crosses, and detects the engine rotation speed NE.
, That is, an engine rotation pulse as a rotation angle signal for each predetermined crank angle (every 3.75 ° CA in this embodiment). Further, since the rotation speed sensor 35 is integrated with the roller ring 9,
Regardless of the control operation of the timer device 26, a timing signal serving as a reference is output at a pair of timings to the plunger lift.

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 a sub-combustion chamber 45 provided correspondingly for each cylinder. Then, the 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 start-up assist device is attached to each sub-combustion chamber 45.

The diesel engine 2 is provided with an intake pipe 47 and an exhaust pipe 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. 48
Turbine 51 is provided. The exhaust pipe 50 is provided with a waste gate valve 52 for adjusting the supercharging pressure PiM. As is well known, the turbocharger 48 uses the energy of the exhaust gas to rotate the turbine 51, and rotates the compressor 49 on the same axis 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 has an exhaust pipe 5
A recirculation pipe 54 is provided for recirculating a part of the exhaust gas in the cylinder 0 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. 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 opening and closing of the bypass throttle valve 60 is controlled by an actuator 63 having a two-stage diaphragm chamber driven by control of two VSVs 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 the respective VSVs 56, 61, and 62 are electronic control units that constitute spill position calculation means, surplus angle calculation means, surplus angle time conversion means, pulse time storage means, and spill valve control means. The ECU 71 controls the driving timing of the ECU 71.

As sensors for detecting the operation 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 water temperature sensor 75 for detecting the cooling water temperature THW of the diesel engine 2 is provided. Further, a crank angle sensor 76 for detecting a rotation reference position of the crankshaft 40 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, a transmission (not shown) is provided with a vehicle speed sensor 77 for detecting a vehicle speed (vehicle speed) SP by turning on / off a reed switch 77b by a magnet 77a rotated by rotation of the gear.

The ECU 71 is connected to the above-mentioned sensors 72 to 77, respectively,
5 is connected. In addition, the ECU 71 controls each sensor 35,
The electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, and the VSVs 56, 61, 62 are suitably controlled based on the signals output from 72 to 77.

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 is provided with the above-described intake air temperature sensor 72, accelerator opening sensor 73, intake air pressure sensor 74, and water temperature sensor 75 in the buffers 88, 89, 90, and 9 respectively.
1, are connected via a multiplexer 93 and an A / D 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. Then, the CPU 81 reads, as input values, detection signals of the sensors 35, 72 to 77, etc., which are input through the input port 85. Each drive circuit 9 is connected to the output port 86.
The electromagnetic spill valve 23, the timing control valve 33, the glow plug 46, the VSVs 56, 61, 62 and the like are connected via 6, 97, 98, 99, 100, 101.

The CPU 81 controls the sensors 35 and 72
Based on the input value read from ~ 77, the electromagnetic spill valve 2
3. The timing control valve 33, the glow plug 46, and the VSVs 56, 61, 62 are suitably controlled.

Next, the fuel injection amount control operation executed by the ECU 71 will be described with reference to FIGS. The flowcharts shown in FIGS.
1 shows a fuel injection time calculation process executed by the routine shown in FIG. The fuel injection time calculation process is performed by the rotation speed sensor 3
5 is executed as an NE interrupt routine interrupted by the rising edge of the engine rotation pulse of the engine rotation speed NE input from step 5.

When the fuel injection time calculation process shown in the figure is started, first, in step 10 (step is abbreviated as S in the figure), the engine speed obtained based on the engine speed pulse output from the speed sensor 35 is first detected. N
The fuel injection amount SPV is obtained based on E, the accelerator opening Accp obtained from the accelerator opening sensor 73, and the like.
In the following step 12, an injection start position ANGSPS (ie, a position at which the electromagnetic spill valve 23 is turned on) at which fuel injection is started based on the fuel injection amount SPV obtained at step 10, and an injection opening end position ANG at which fuel injection ends.
SPE (ie spill position to turn off electromagnetic spill valve 23)
Is calculated. FIG. 7 shows the positions of the injection start position ANGSPS and the spill position ANGSPE. FIG. 7 is a diagram showing an example of the correlation between the engine rotation pulse and the spill valve operation.

In step 12, the injection start position ANG
When the SPS and the spill position ANGSPE are obtained, in step 14, the pulse number CA during spill is calculated based on these values.
NGLa and the remainder angle θREM are calculated.

Here, the pulse number CANGLa at the time of spill is defined as follows from the reference position to the spill position A as shown in FIG.
The number of pulses up to one pulse before the engine rotation pulse including the NGSPE (the fourth pulse corresponds to this in the present embodiment; this pulse is hereinafter referred to as a spill pulse). The remainder angle θREM refers to the crank angle from the rising position of the spill pulse to the spill position ANGSPE. Further, in the present embodiment, the reference position is a pulse output from a projection (teeth) formed next to the incisor formation position in accordance with the rotation of the pulsar 7 among the engine rotation pulses output from the rotation speed sensor 35. (In this embodiment, the rising position of the 0th pulse is used as the reference position).

Now, from the reference position to the spill position ANGSP
Assuming that the crank angle up to E (hereinafter, this crank angle is referred to as a spill opening angle) is ANGSPV, the spill opening angle ANGSPV is equal to the spill pulse number C.
The angle is expressed by the following equation using ANGLa, a residual angle θREM, and a crank angle per engine rotation pulse (3.75 ° CA).

ANGSPV = 3.75 × CANGLa + θREM In the following step 16, the pulse time TNINT (n−1) one pulse before (previous time) before the spill pulse is calculated. Since this pulse time TNINT (n-1) is the pulse width time of the engine rotation pulse (third pulse) immediately before the engine rotation pulse (fourth pulse) started by the current routine processing, the CPU 81 determines 4 pulses preceding the pulse time by the rising time T _4U subtracting process the rising time T _4U third pulse TNINT
(N-1) is calculated.

The pulse time TN calculated in step 16
INT (n-1) is stored in the RAM 83 in step 18.
And stored. As described above, this routine processing is executed every time an engine rotation pulse is generated. Therefore,
Each time an engine rotation pulse is generated, the pulse time TNINT (n-1) one time before the engine rotation pulse is sequentially stored in the RAM 83. Therefore, the pulse time TNINT for all the engine rotation pulses is stored in the RAM8.
3 is stored.

In the following step 20, a basic remainder angle time TθREM0 is calculated. Here, the basic remainder angle time TθREM0 is obtained by converting the above-mentioned remainder angle θREM into time. This basic remainder angle time TθREM
0 is the pulse time of the spill pulse TNINT (n)
If the spill time is known, it can be expressed by the following equation.

TθREM0 = {θREM × TNINT (n)} / 3.75 However, the actual spill pulse time TNINT (n)
Cannot be obtained unless the next engine rotation pulse (fifth pulse) after the spill pulse is generated. Also, the spill position ANGS at the end of the fuel injection
Since the PE exists before the generation of the fifth pulse, it is necessary to calculate the basic remainder angle time TθREMO before the generation of the fifth pulse. That is, it is necessary to calculate before the actual spill time pulse time TNINT (n) is determined.

Therefore, the spill pulse time TNI required in the calculation of the basic remainder angle time TθREMO
NT (n) needs to be estimated in some way. Therefore, in this embodiment, the engine rotation pulse (third pulse) immediately before the spill pulse (fourth pulse) is used.
That the basic remainder angle time TθREM0 is calculated based on the pulse time TNINT (n−1)
The feature of. Basic remainder angle time Tθ in this embodiment
The operation formula of REMO is described below.

TθREM0 = {θREM × TNINT (n−1)} / 3.75 Here, instead of the actual spill time pulse TNINT (n), the engine one time before the spill time pulse (fourth pulse) is used. Using TNINT (n-1) which is the pulse time of the rotation pulse (third pulse), the basic remainder angle time TθR
The reason for calculating EM0 will be described.

The above-described engine rotation fluctuation does not suddenly occur from a certain engine rotation pulse, but gradually occurs depending on the engine state. This will be described with reference to FIG. When the engine rotation fluctuation occurs, the pulse time TNINT of the engine rotation pulse also changes. As described above, since the spill time pulse is generated substantially near the bottom dead center (BDC) position, the pulse time TNINT of the engine rotation pulse becomes longer near the spill position. For this reason, as shown in FIG.
Spill pulse time TNI with respect to NINT (n-4)
NT (n) is longer, and its time change gradually increases toward the spill pulse.

Therefore, if the basic remainder angle time TθREM0 is calculated based on the pulse time TNINT (n−4) of the 0th pulse separated from the spill pulse, the pulse time TNINT (n−4) of the 0th pulse Since the spill pulse time TNINT (n) is significantly different from the actual value, the basic remainder angle time TθREM0 calculated based on the pulse time TNINT (n−4) is different from the actual value, and the accuracy is reduced. Would.

On the other hand, the pulse time TNINT (n−n−3) of the third pulse immediately before the spill-time pulse (fourth pulse).
1) is a time approximating the spill pulse time TNINT (n). For this reason, the pulse time TNINT (n−n) of the engine rotation pulse immediately before the spill time pulse is used.
By calculating the basic remainder angle time TθREM0 using 1), it is possible to prevent the influence of engine rotation fluctuation from being reflected on the basic remainder angle time TθREM0, and to obtain the basic remainder angle time TθREM0 with high accuracy. It is possible to improve the accuracy of the fuel injection amount control.

When the basic remainder angle time TθREM0 is calculated in step 20 as described above, the process proceeds to step 22 in FIG.

In step 22, the pulse time TN sequentially stored in the RAM 83 by the processing in step 18
Of INT, 720 ° C for this spill pulse
The pulse time TNINT (n-192) before A is read.

As described above, the diesel engine 2 according to the present embodiment is a four-cylinder four-stroke engine, in which the intake, compression, explosion, and exhaust processes are performed by rotating the crankshaft 40 by 720 ° CA. Have been. Accordingly, as shown in FIG. 8, the pulse time TNINT (n-192) 720 ° CA before the current spill pulse is the spill pulse time of the previous spill pulse in the same cylinder (hereinafter referred to as the last spill pulse). Time pulse time).

In step 22, the previous spill pulse time T
When NINT (n-192) is obtained, the process proceeds to step 2.
4 and the previous spill pulse time TNINT (n
-192), the same cylinder correction amount ΔTθSPVX0 is calculated. Here, the same cylinder correction amount ΔTθSPVX0 is
This is a correction value for reflecting the engine rotation fluctuation generated due to the machine error unique to each cylinder to the extra angle time TθREM.

A specific same cylinder correction amount ΔTθSPVX0
Is calculated in advance by storing in the ROM 82 the spill-time pulse time TNINT0 (called true spill-time pulse time) in a state where there is no device error calculated by calculation as a binary map with the engine speed NE. The current engine speed NE of the diesel engine 2 is obtained from the output of the speed sensor 35, and the true spill pulse time TN
First, INT0 is obtained. Then, based on the obtained true spill pulse time TNINT0, the same cylinder correction amount ΔTθSPVX0 is calculated by the following equation.

ΔTθSPVX0 = TNINT (n−192) −TNINT0 The same cylinder correction amount ΔTθSPV obtained in this manner.
X0 is reflected in the basic remainder angle time TθREMO calculated in step 20 in the processing of step 30 described later.

As is well known, in an engine having a plurality of cylinders, each cylinder has a device error, which affects the engine rotation fluctuation. Therefore, the pulse time (TNINT (n−n
192) and TNINT (n-1)), by correcting the basic remainder angle time TθREM0, it is possible to offset the above-described device error for each cylinder.

Therefore, the same cylinder correction amount ΔTθSPVX0
Is reflected in the basic remainder angle time TθREM0, the variation of the basic remainder angle time TθREM0 between the cylinders can be eliminated, and the basic remainder angle time Tθ
The accuracy of REMO can be improved, and the accuracy of fuel injection amount control can be improved.

In the following step 26, step 1
In the pulse time TNINT sequentially stored in the RAM 83 by the processing of No. 8, 180
Read the pulse time TNINT (n-48) before CA.

As is well known, the rotation of the engine fluctuates with the engine cycle, and has the highest speed in the explosion process and tends to decrease in other processes. Therefore,
When calculating the basic remainder angle time TθREMO, the basic remainder angle time TθREMO is calculated based on the pulse time TNINT of the engine rotation pulse in a region where the engine rotation variation is small. Can be eliminated.

Focusing on the actual engine rotation fluctuation (actual engine rotation fluctuation), as shown in FIG. 8, the spill pulse generation position is substantially near the bottom dead center (BDC) position. 180 degrees before is an intermediate position between the bottom dead center (BDC) and the top dead center (TDC), which is an area where engine rotation fluctuation is small.

Therefore, the current spill time pulse is 18
The pulse time T of the engine rotation pulse before 0 ° CA
Basic remainder angle time TθRE based on NINT (n-48)
By obtaining M0, the basic residual angle time TθREM
0 can be stabilized, and the accuracy of the fuel injection amount control can be improved.

Therefore, in this embodiment, 180 ° CA
Pulse time TNINT of the previous engine rotation pulse
A smoothing correction amount ΔTθSPVX1 is calculated based on (n−48), and this is calculated in step 30 as the basic remainder angle time T
By reflecting this in θREM0, the basic residual angle time T
It is configured to stabilize θREM0. The smoothing correction amount ΔTθSPVX1 is obtained by the following equation using the above-described true spill-time pulse time TNINT0.

ΔTθSPVX1 = TNINT (n−48) −TNINT0 ... The smoothing correction amount ΔTθSPVX thus obtained
1, and the same cylinder correction amount ΔTθSPVX0 obtained in step 24 is the basic remainder angle time Tθ calculated in step 20 described above in step 30.
The remaining angle time TθREM is calculated by being reflected on REM0. The remaining angle time TθREM can be obtained by the following equation.

TθREM = TθREM0 + k ₀ × ΔTθSPVX0 + k ₁ × ΔTθSPVX1 where k ₀ and k ₁ are the basic remainder angle time T of the same cylinder correction amount ΔTθSPVX0 and smoothing correction amount ΔTθSPVX1.
This is a constant to be reflected on θREM0.

The residual angle time TθREM obtained in step 30 is the same as the actual value in which the same cylinder correction is performed to suppress the variation between cylinders and the smoothing correction is performed to eliminate the influence of engine rotation fluctuation. Is extremely close to the angle time.

In the following step 32, step 3
The fuel injection time TSPV is calculated based on the remaining angle time TθREM obtained at 0. Here, the fuel injection time T
SPV refers to the time from the reference position to the spill position ANGSPE (see FIG. 7). Now, assuming that a value obtained by converting the spill pulse number CANGLa obtained in step 14 into time is TCANGLa, the fuel injection time TSPV is expressed by the following equation.

TSPV = TCANGLa + TθREM where TCANGLa = TNINT (n−4) + TNI
NT (n-3) + TNINT (n-2) + TNINT
(N-1) By calculating the fuel injection time TSPV as described above,
The fuel injection time calculation processing ends. Based on the fuel injection time TSPV obtained by the above series of processes, the CPU
81 controls the drive of the electromagnetic spill valve 23. Specifically, the CPU 81 measures the elapsed time from the reference position using the connected clock 92, and turns on the electromagnetic spill valve 23 when the time TANGSPS from the reference position to the injection start position ANGSPS has elapsed. Then, the fuel injection is started, and when the fuel injection time TSPV obtained in step 32 has elapsed, the electromagnetic spill valve 23 is turned off to terminate the fuel injection.

At this time, as described above, the excess angle time Tθ
REM is a value very close to the actual remaining angle time, and therefore the fuel injection time TSPV calculated based on this remaining angle time TθREM is extremely accurate, and the fuel injection amount is controlled with high accuracy. be able to.

When an inner cam type fuel injection pump capable of pressurizing fuel at a higher pressure is used instead of the so-called face cam type fuel injection pump 1 used in this embodiment, for example, the fuel pressure increases. By doing so, it is necessary to more accurately perform on / off control of the electromagnetic spill valve 23.

That is, since the injection amount per unit time injected from the fuel injection nozzle 4 increases as the fuel pressure increases, the ON / OFF timing of the electromagnetic spill valve 23 is slightly shifted from the predetermined timing. Therefore, the amount of fuel injected greatly differs from the calculated predetermined injection amount. In this case, optimal engine control becomes impossible, resulting in deterioration of emission and large fluctuations in engine rotation.

On the other hand, the fuel injection amount control device according to the present invention can set the fuel injection time TSPV with extremely high accuracy, and thus can set the ON / OFF timing of the electromagnetic spill valve 23 with high accuracy. Therefore, by employing the fuel injection amount control device having the configuration of the present invention, the fuel injection amount control can be reliably performed even when the fuel injection pump that supplies the high fuel pressure as described above is employed.

In the above-described embodiment, the remaining angle θREM is converted into a time to obtain the remaining angle time TθREM, and based on this, the timing of turning off the electromagnetic spill valve 23 (that is, the spill position) is set with high accuracy. But
This processing may be applied to the injection start position ANGSPS to set the timing of turning on the electromagnetic spill valve 23 with higher accuracy. With this configuration,
Both the ON and OFF timings of the electromagnetic spill valve 23 can be set with high precision, and in particular, the fuel injection amount can be controlled with high accuracy in the fuel injection pump having a high fuel pressure as described above.

[0079]

[0080]

As described above, according to the present invention, it is possible to accurately set the fuel injection time by improving the calculation accuracy of the surplus angle time, thereby improving the accuracy of the fuel injection amount control. It has such features as possible.

[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 time calculation process executed by the ECU.

FIG. 6 is a flowchart showing a fuel injection time calculation process executed by the ECU.

FIG. 7 is a diagram for explaining how to determine a spill time pulse time and a fuel injection time.

FIG. 8 is a diagram for explaining how to obtain the same cylinder correction amount and the smoothing correction amount.

[Explanation of symbols]

 Reference Signs List 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 rotation speed 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 SPV: Fuel injection amount ANGSPS: Injection start position ANGSPE: Injection end position (spill position) CANGLa : The number of pulses at the time of spill TCANGLa: Time converted value of CANGLa θREM: Remaining angle TθREM: Remaining angle time ΔTθSPVX0: Same cylinder correction ΔTθSPVX1: smoothing correction amount TSPV: fuel injection time

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-223248 (JP, A) JP-A-4-86352 (JP, A) JP-A-5-288110 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F02D 45/00 F02D 41/04 F02D 41/38-41/40 F02D 1/02

Claims (1)

(57) [Claims] 1. A fuel injection pump for pressurizing fuel by a driving force generated by a diesel engine, and for pumping the pressurized fuel to the diesel engine while controlling a fuel injection amount by a spill valve, and an operation of the diesel engine. A spill position calculating means for calculating at least a timing of opening the spill valve corresponding to a fuel injection end timing based on a fuel injection amount determined according to a state; and outputting an engine rotation pulse at every constant crank angle of the diesel engine. Based on the engine rotation pulse output from the engine rotation detection unit at a constant crank angle, and counting the number of counts from the reference position to the spill position of the engine rotation pulse and satisfying one pulse thereof. A surplus angle calculating means for calculating a surplus angle, and a pulse time for one pulse of the engine rotation pulse A pulse time calculating means for calculating; and a surplus angle time calculated by the surplus angle calculating means based on a pulse time of an engine rotation pulse sandwiching the spill position calculated by the pulse time calculating means. Surplus angle time conversion means for calculating; pulse time storage means for storing a pulse time calculated by the pulse time calculation means; a count number from a reference position to a spill position calculated by the surplus angle calculation means; less the time timing determined based on the remainder angle time is calculated by the angle time conversion means which comprises a spill valve control means for driving and controlling the spill valve, 該余Ri angle time conversion means, the pulse time This time the spy that is stored in the storage means
At least one more than the engine rotation pulse including
The remainder angle based on the pulse time of the previous engine rotation pulse
And the current time stored in the pulse time storage means.
Crank angle than engine rotation pulse including
Engine rotational pulse of the pulse in the 720 degrees before and Le
Is generated due to cylinder-specific equipment errors based on the
The same cylinder supplement, which is a correction value for correcting engine
A configuration in which a positive amount is calculated and the remaining angle time is corrected by the same cylinder correction amount.
A fuel injection amount control device for a diesel engine, characterized in that: