JPH09144583A - Fuel injection timing control device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To realize accurate fuel injection timing control that is not affected by noise. SOLUTION: Vibration generated during fuel combustion in a cylinder is
The vibration sensor 4 detects the ignition signal. CPU
32 is the engine 1 detected by the reference position sensor 3
The actual ignition timing is calculated from the reference position signal of 1 and the ignition signal from the vibration sensor 4, and the target ignition timing and the target injection timing are calculated based on the engine operating state. Further, the CPU 32 obtains an injection timing correction amount based on the deviation between the actual ignition timing and the target ignition timing, and corrects the target injection timing with the injection timing correction amount. On the other hand, the CPU 32
Is when the phase of the fuel injection timing by the timer mechanism 6 changes,
Depending on the phase change state of the actual ignition timing at that time, it is determined whether or not the ignition signal detected by the vibration sensor 4 is due to noise, and if it is determined that it is noise, the target injection based on the ignition signal is performed. Prohibit timing correction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection timing control device applied to a diesel engine, for example.

[0002]

2. Description of the Related Art Conventionally, as a fuel injection timing control device of this type, vibration generated during a combustion stroke of an engine is detected as an ignition signal (combustion signal), and an injection timing is controlled by a timer mechanism based on the ignition signal. A technique for enabling the above is disclosed. In such a device, by controlling the injection timing by the timer mechanism so that the actual ignition timing coincides with the target ignition timing, the actual ignition timing caused by mechanical error of the fuel injection pump, engine difference, secular change, etc. The deviation from the target ignition timing of can be corrected.

[0003]

However, in the above-described conventional fuel injection timing control device, the seating noise of the intake or exhaust valve of the engine is erroneously detected as an ignition signal during combustion, and the fuel injection timing is controlled. There was a risk of causing a problem of deterioration in accuracy. Especially high rotation
In the high load state, the seating noise becomes large, and the above problem may become significant.

The present invention has been made in view of the above-mentioned problems, and its purpose is to properly determine whether the detected ignition timing is due to combustion or noise, and eventually to detect noise. An object of the present invention is to provide a fuel injection timing control device that can realize accurate fuel injection timing control that is not affected by.

[0005]

In order to achieve the above object, in the invention described in claim 1, for example, a vibration sensor attached to a cylinder block of an engine is used to inject fuel from a fuel injection pump into a cylinder of the engine. An ignition signal generated during combustion of the supplied fuel is detected (ignition timing detection means). And the reference position sensor (reference position detecting means)
The actual ignition timing is calculated from the reference position signal corresponding to the reference crank angle position of the engine detected by and the ignition signal from the ignition timing detecting means (actual ignition timing calculating means). Further, the target ignition timing and the target injection timing by the timer mechanism are calculated based on the engine operating state (target ignition timing calculation means, target injection timing calculation means). Further, the injection timing correction amount is obtained based on the deviation between the actual ignition timing and the target ignition timing, and the target injection timing is corrected by the injection timing correction amount (injection timing correction means). The operation of the timer mechanism is controlled based on the target injection timing (injection timing control means).

Further, in the characterizing feature of the present invention, when the phase of the fuel injection timing is changed by the timer mechanism, the ignition signal detected by the ignition timing detecting means is detected according to the phase change state of the actual ignition timing at that time. It is determined whether or not it is due to noise (noise determining means). Further, when the noise determination unit determines that the ignition signal is noise, the correction of the target injection timing by the injection timing correction unit is prohibited (correction prohibition unit).

In short, when the vibration during the combustion of the fuel (at the time of ignition) is detected as the ignition signal as described above, the seating noise of the intake or exhaust valve or the like may be erroneously detected as the ignition signal. However, the phase of the detection signal corresponding to the seating noise is originally fixed to the reference crank angle position of the engine, while the detection signal corresponding to actual ignition is fixed to the reference crank angle position by the timer mechanism. Produces a phase difference according to the injection timing control. Therefore, by determining the phase change state of the actual ignition timing at that time when the phase of the fuel injection timing is changed by the timer mechanism, it is possible to determine whether or not the ignition signal is due to noise. Then, when the ignition signal is due to noise, the adverse effect of noise can be avoided by prohibiting the injection timing correction based on the ignition signal, and as a result, highly accurate fuel injection timing control can be realized.

Particularly, in the invention according to claim 2, the noise determining means detects the ignition timing detecting means if the phase change of the fuel injection timing by the timer mechanism and the phase change of the actual ignition timing are in the same direction. It is determined that the ignition signal is due to combustion of fuel, and if it is in a different direction, the ignition signal is due to noise. Therefore, the noise can be discriminated more clearly. Here, the fact that the phase change of the fuel injection timing and the phase change of the actual ignition timing are in different directions means that
In addition to the fact that the change directions are different from each other, a relative change state in which one changes and the other does not change is included.

Further, in the invention according to the third aspect, the noise discrimination means carries out the noise discrimination of the ignition signal only when it is judged that the engine operating state has changed. That is, when the engine operating state is a steady state, the phase change of the fuel injection timing by the timer mechanism is small and the phase change of the actual ignition timing is also relatively small. Therefore, the noise determination process is not performed in such a steady state, and the noise determination process is performed only when the engine operating state changes (in the transient state), whereby the calculation load can be significantly reduced.

According to another aspect of the invention, when the phase change of the fuel injection timing by the timer mechanism is smaller than the predetermined value, the noise determining means ignites when the phase change of the actual ignition timing at that time exceeds the predetermined value. Determine that the signal is due to noise. That is, when the phase change of the fuel injection timing by the timer mechanism is smaller than the predetermined value, the phase change of the actual ignition timing should be small. Therefore, according to the above configuration, it is possible to clearly discriminate noise.

Further, in the invention according to claim 5, the past actual ignition timing and the fuel injection timing for calculating the phase change of the actual ignition timing and the fuel injection timing are stored for each cylinder, so that the fuel injection timing The control accuracy can be further enhanced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a fuel injection control system for a diesel engine will be described below with reference to the drawings. The fuel injection control system in the present embodiment includes a distributed face cam fuel injection pump, and supplies the fuel compressed to a high pressure in the pump to the fuel injection nozzle of the diesel engine. The fuel injection amount from the fuel injection pump to the fuel injection nozzle is controlled by a well-known electromagnetic spill valve provided in the fuel injection pump, and the fuel injection timing is also provided by a well-known timer mechanism also provided in the fuel injection pump. It is supposed to be done. The operations of the electromagnetic spill valve and the timer mechanism are controlled by an electronic control unit (hereinafter, referred to as an ECU) according to an engine operating state.

FIG. 1 is a configuration diagram showing an outline of a fuel injection control system in the present embodiment. In FIG.
Engine 1 consists of a 4-cylinder diesel engine,
The fuel pressure-fed from the distributed fuel injection pump 2 is injected into each cylinder from the fuel injection nozzle 8. Engine 1 has
A reference position sensor 3 for outputting a reference signal for each predetermined reference crank angle (in this embodiment, every 180 ° CA) in accordance with the rotation of the engine 1, and during ignition of fuel in the engine cylinder (during combustion) 2) is provided with a vibration sensor 4 for detecting the vibration generated in the engine) and a fuel temperature sensor 5 for detecting the fuel temperature of the engine 1.

Here, the reference position sensor 3 is the engine 1
It is composed of a gear that rotates in synchronization with the crankshaft and an electromagnetic pickup that faces the gear, and is also used for measuring the engine speed. Vibration sensor 4
Is directly attached to the cylinder block of the engine 1. As the sensor 4, for example, a knock sensor used in a gasoline engine is used. These sensors 3
The detection signals of ~ 5 are fetched by the ECU 30 described later.
In the present embodiment, the reference position sensor 3 constitutes the reference position detecting means, and the vibration sensor 4 constitutes the ignition timing detecting means.

Further, the fuel injection pump 2 is provided with a hydraulically driven timer mechanism 6 for controlling the fuel injection timing and an electromagnetically driven electromagnetic spill valve 7 for controlling the fuel injection amount. There is.

FIG. 2 shows the structure of the timer mechanism 6. In FIG. 2, a timer piston 10 slidably arranged in a timer housing 9 is connected to a roller ring 12 via a slide pin 11. Further, in the timer housing 9, the intake fuel to the vane type feed pump 14 is introduced into the low pressure chamber 13, and the discharge fuel from the feed pump 14 is introduced into the high pressure chamber 15. Here, the feed pump 14 is rotated by a drive shaft (not shown) of the fuel injection pump 2,
Fuel is pumped from the fuel tank 16 to the pump chamber 17.

The timer piston 10 slides in the left-right direction in the figure by the balance between the urging force of the timer spring 18 arranged on the low pressure chamber 13 side and the fuel pressure in the high pressure chamber 15, and the roller ring 12 rotates. To do. The fuel pressure in the high pressure chamber 15 is adjusted by the timer control valve 19, and the timer control valve 19 is duty-controlled by a drive signal from the ECU 30. When the timer piston 10 moves to the left in the figure, the roller ring 12 rotates in the clockwise direction in the figure, at which time the fuel injection timing shifts to the advance side.

Further, in FIG. 1, the fuel injection pump 2 is provided with a phase detection sensor 2 for outputting a phase detection signal at every predetermined angle as the drive shaft of the pump 2 rotates.
1 is provided. The configuration of the same phase detection sensor 21 is shown in FIG. In FIG. 3, the phase detection sensor 21 is an electromagnetic pickup 2 attached to the roller ring 12.
2 and a disc 2 attached to the drive shaft 24 of the fuel injection pump 2 and facing the electromagnetic pickup 22.
And 3. The disc 23 has four teeth 2 at 90 ° intervals.
3a is provided. In this case, the drive shaft 24 rotates at 1/2 speed in synchronization with the crankshaft of the engine 1, and as a result, the phase detection sensor 21 outputs a phase detection signal every 180 ° CA of the engine 1. Since the roller ring 12 rotates about the drive shaft 24 as the timer piston 10 slides, the phase detection signal corresponds to the reference position according to the injection timing controlled by the timer mechanism 6. The reference position signal from the sensor 3 has a predetermined phase difference (hereinafter referred to as an actual phase difference).

The ECU 30 includes a CPU 32, a memory 33,
The microcomputer 31 mainly includes a timer 34 and the like, and the microcomputer 31 controls the fuel injection amount and the fuel injection timing of the fuel injection pump 2.
The ECU 30 also includes an A / D converter 35, an input circuit 3
6, 37, 38, and output circuits 39, 40. Specifically, the A / D converter 35 converts the analog signal from the fuel temperature sensor 5 into a digital signal and outputs it to the microcomputer 31. The output signal of the accelerator position sensor 26 for detecting the amount of depression of the accelerator pedal 25 is input to the A / D converter 35, and the A / D conversion signal of the sensor 26 is input to the microcomputer 3
It is output to 1.

In the present embodiment, the CPU 32 controls the actual ignition timing calculation means, the target ignition timing calculation means, the target injection timing calculation means, the injection timing correction means, the injection timing control means, the noise discrimination means and the correction prohibition means. It is configured.

Here, the input circuit 38 is a circuit for waveform-processing the output signal from the vibration sensor 4, and its configuration is shown in FIG. In FIG. 4, the signal from the vibration sensor 4 is input to a filter 41 for removing high frequency noise and AC components, and its output Vf is input to an integration circuit 42 and a peak hold circuit 43. The respective outputs Vi and Vp are input to the comparator 44, and the magnitudes of the outputs Vi and Vp are compared. In the present embodiment, when the output Vp (peak hold circuit output) becomes larger than the output Vi (integration circuit output), the comparator 44 outputs, for example, a signal of 5V, and otherwise outputs 0V. Has become.

Therefore, when the level of combustion oscillation is small and the peak hold output does not exceed the integrated output, the output voltage of the comparator 44 remains 0V. A reset signal is input to the peak hold circuit 43 from the microcomputer 31, and the reset signal is output at 90 ° CA after the compression TDC of each cylinder.
It is reset every combustion of each cylinder.

Details of the operation of the input circuit 38 are shown in FIG.
The signal obtained by filtering the signal from the vibration sensor 4 is (a). The waveform obtained by inputting this signal to the integration circuit 42 becomes like "Vi" shown by the broken line in (b),
The waveform obtained by inputting it to the peak hold circuit 43 becomes like "Vp" shown by the solid line in (b). When these two "Vi, Vp" are input to the comparator 44, (c)
The output Vc shown in is obtained.

The input circuits 36 and 37 are composed of well-known waveform shaping circuits for shaping the reference position signal from the reference position sensor 3 or the phase detection signal from the phase detection sensor 21. The configuration is shown in FIG. 6 (detailed description is omitted). Further, FIG. 7 shows signal waveforms of the reference position signal, the phase detection signal, and the ignition timing detection signal.

In FIG. 7, the reference position sensor 3 outputs an AC signal as shown in (a) at a predetermined reference crank angle position. When this AC signal is input to the input circuit 36, the waveform is shaped and the pulse period T as shown in FIG.
n reference position signals are output. On the other hand, when the output signal of the phase detection sensor 21 is waveform-shaped by the input circuit 37,
The phase detection signal shown in (c) is obtained. At this time, the actual phase difference TP by the timer mechanism 6 is obtained from the pulse of the reference position signal and the pulse of the phase detection signal. That is, the difference between the timer value ti (the count value of the timer 34 in the microcomputer 31) corresponding to the rising edge of the pulse of the reference position signal and the timer value tk corresponding to the rising edge of the pulse of the phase detection signal is real. Phase difference T
Corresponds to P (TP = ti-tk).

Further, the actual ignition timing associated with fuel injection into the engine 1 is obtained from the pulse of the ignition timing detection signal from the vibration sensor 4 and the pulse of the reference position signal. That is,
The difference between the timer value tj corresponding to the rising edge of the pulse of the ignition timing detection signal and the timer value ti corresponding to the rising edge of the pulse of the reference position signal is the actual injection timing TT.
Corresponds to P (TTP = tj-ti).

Next, the operation of the present embodiment will be described. 8 to 13 show a CPU 32 in the microcomputer 31.
The processing performed by is shown in a flowchart, and this flow will be described step by step. FIG. 8 shows a fuel injection timing control routine as a main routine, FIG. 9 shows a noise determination routine showing details of a noise determination portion, and FIGS. 10 to 13 show various interrupt routines.

In FIG. 8, the CPU 32 executes the step 1
In 01, perform necessary initialization at power-on (for example,
The correction term ΔT described later is cleared). Next, CPU3
In step 102, the engine speed Ne is calculated by taking the reciprocal of the pulse cycle Tn of the reference position signal from the reference position sensor 3 and multiplying it by a constant in step 102.

At this time, an interrupt is made to occur at the rising edge of the pulse of the reference position signal shown in FIG. 7B, and the pulse cycle Tn is calculated according to the reference position interrupt routine shown in FIG. That is, the reference position interrupt routine starts in synchronization with the rising edge of the reference position signal, and the CPU 32 reads the timer value ti at that time in step 301, and in the subsequent step 302, pulses the difference from the previous timer value ti-1. It is calculated as a cycle Tn (Tn = ti-ti-1). Further, the CPU 32
In step 303, the actual phase difference TP of the phase detection signal with respect to the reference crank position is calculated (TP = ti-tk). Here, the timer value tk is obtained by the phase signal interrupt routine of FIG. That is, the phase signal interrupt routine is shown in FIG.
The CPU 32 is activated in synchronization with the rising edge of the pulse of the phase detection signal shown in (c), and the CPU 32 reads the timer value tk in step 401.

Returning to FIG. 8, the CPU 32 causes the step 10
3 the actual fuel injection amount by the fuel injection pump 2 (hereinafter,
The actual injection amount Q) is calculated. Here, the actual injection amount Q
Is the engine speed N at that time using a map not shown.
It is calculated according to e and the accelerator opening. Then the CPU
32 is the engine speed Ne at that time in step 104.
The basic target phase difference TB is calculated by a map or a calculation formula in accordance with the actual injection amount Q and the actual injection amount Q. Further, the CPU 32 calculates the target ignition timing TTS in the following step 105. Similar to the basic target phase difference TB, the target ignition timing TTS is obtained by a map or a calculation formula according to the engine speed Ne and the actual injection amount Q.

Then, in step 106, the CPU 32 calculates the actual ignition timing TTP from the pulse of the reference position signal and the pulse of the ignition timing detection signal. However, the actual ignition timing TTP calculation process is actually executed by the ignition timing signal interrupt routine shown in FIG. That is, the ignition timing signal interrupt routine is started in synchronization with the rising edge of the pulse of the ignition timing detection signal shown in FIG.
Reads the timer value tj at the time when the signal rises in step 501, and calculates the difference from the immediately preceding timer value ti in step 502 as the actual ignition timing TTP (TTP = tj-ti).

Next, the CPU 32 subtracts the previous value TP (i-1) from the current value TP (i) of the actual phase calculation TP calculated in step 303 of FIG. 10 in step 107 to change the fuel injection timing. The amount, that is, the actual phase difference change amount ΔTP is calculated. Further, the CPU 32 at the subsequent step 108 calculates the actual ignition timing TTP calculated at step 502 of FIG.
Then, the previous value TTP (i-1) is subtracted from the current value TTP (i) to calculate the actual ignition timing change amount ΔTTP.

Then, the CPU 32 determines in step 109 whether or not the noise determination flag flag is "0". Here, the noise determination flag flag is a flag for determining whether the detection signal (ignition timing detection signal) of the vibration sensor 4 used this time is due to ignition (combustion) of the engine 1 or due to noise. If it is (combustion), the flag flag is reset (flag =
0), if it is noise, the same flag is set (flag = 1). The noise determination flag flag is operated according to the process of FIG. 9 described later based on the actual phase difference change amount ΔTP and the actual ignition timing change amount ΔTTP.

In this case, if flag = 0, then CP
U32 considers that the current ignition timing detection signal is not noise, and calculates the correction term ΔT in step 110. The correction term ΔT is the target ignition timing T calculated in step 105.
TS and actual ignition timing TTP calculated in step 106
It is calculated as a feedback correction term for eliminating the deviation between and. If flag = 1, the CPU 32 considers that the ignition timing detection signal of this time is noise, and sets the correction term ΔT to “0” in step 111. That is, the injection timing correction based on the current ignition timing detection signal is prohibited.

After that, the CPU 32 adds the basic target phase difference TB and the correction term ΔT in step 112 to calculate the corrected target phase difference TS (TS = TB + ΔT). Next, the CPU 32 calculates the actual phase difference TP in step 113. For this, the actual phase difference TP obtained in step 303 of FIG. 10 described above may be used. Next, the CPU 32
In step 114, the corrected target phase difference TS and the actual phase difference TP
The duty ratio D of the drive signal output to the timer control valve 19 is calculated in order to eliminate the deviation from the above.

After proceeding to step 114, the process returns to step 102, and the same process is repeated to calculate the output duty ratio D again. While the routine is being executed in this manner, the scheduled interrupt routine shown in FIG.
In step 01, a constant time interrupt process (for example, drive process of the electromagnetic spill valve 7) is executed, and in step 602, the duty ratio D calculated in step 114 of FIG. 8 is output to the output circuit 40. With this duty ratio D, the drive of the timer control valve 19 of the timer mechanism 6 is duty-controlled.

Next, the noise discrimination procedure in step 109 of FIG. 8 will be described in detail with reference to the noise discrimination routine of FIG. Note that this routine is performed by, for example, the combustion injection cycle of each cylinder (in this embodiment, 180 ° C.
It is executed by the CPU 32 in cycle A).

Now, when the routine of FIG. 9 starts,
First, in step 201, the CPU 32 clears the noise discrimination flag flag to “0”. Then, the CPU 32
Is the value Δ according to the crank angle multiplied by the actual phase difference change amount ΔTP in step 202 by the engine speed Ne at that time.
Convert to θTP. Further, the CPU 32 executes step 20.
In step 3, the actual ignition timing change amount ΔTTP is multiplied by the engine speed Ne at that time to be converted into a value ΔθTTP according to the crank angle. In other words, if the change amounts ΔTP and ΔTTP are treated as time units, the detection sensitivity may decrease as the engine speed increases, so the change amounts ΔTP and ΔTT may be reduced.
P is converted into change amounts ΔθTP and ΔθTTP in angle units.

Further, the CPU 32 proceeds to step 204,
At 205, it is determined whether or not the pulse of the ignition timing detection signal detected by the vibration sensor 4 is due to noise, based on the magnitudes of the absolute values of the changes ΔθTP and ΔθTTP. That is, in step 204, the actual phase difference change amount Δθ
The absolute value | ΔθTP | of TP is a predetermined value S1 (for example, + 1 °
It is determined whether it is less than (CA). Step 2
In 05, when | ΔθTP | <predetermined value S1, the absolute value | ΔθTTP | of the actual ignition timing change amount ΔθTTP |
It is determined whether it is smaller than 2. Here, step 2
The determination value S2 of 05 may be the same value as the predetermined value S1 of step 204, or may be a value obtained by multiplying the predetermined value S1 by a coefficient K (K> 1) in consideration of some variation.
Further, the coefficient K can be variably set depending on the engine speed and the load.

If both | ΔθTP | and | ΔθTTP | are less than the predetermined values S1 and S2, the CPU 32 proceeds to step 209 and considers that the ignition timing detection signal is due to the actual ignition (combustion) and determines the noise determination flag. flag
Is cleared (flag = 0). In addition, | ΔθTTP |
Is greater than or equal to the predetermined value S2, the CPU 32 proceeds to step 210.
Then, the ignition timing detection signal is considered to be due to noise, and the noise determination flag flag is set (flag
= 1).

On the other hand, if the absolute value of the actual phase difference change amount ΔθTP exceeds the predetermined value S1 in step 204,
The CPU 32 makes a negative decision in step 204 and proceeds to step 2
In 06 to 208, the presence or absence of noise is discriminated by whether or not the changing directions of the actual phase difference and the actual ignition timing are the same direction.

Specifically, in step 206, it is judged whether or not the actual phase difference change amount ΔθTP is a value exceeding “0”, and in step 207, the actual ignition timing change amount ΔθTTP.
Is determined to be greater than "0". At step 208, it is judged if the actual ignition timing change amount ΔθTTP is less than “0”. In this case, the actual phase difference change amount Δ
If θTP and the actual ignition timing change amount ΔθTTP are changing in the same direction (if both Steps 206 and 207 are YES, or Step 206 is NO and Step 20).
8 is YES), the actual phase difference TP by the timer mechanism 6
It means that the actual ignition timing TTP has changed in the same direction with the change of. Therefore, the CPU 32 considers that the pulse of the actual ignition timing signal detected by the vibration sensor 4 is due to the actual ignition (combustion), and the noise determination flag fl.
Clear ag (flag = 0).

If the actual phase difference change amount ΔθTP and the actual ignition timing change amount ΔθTTP change in different directions (YES in step 206 and NO in step 207).
Or if both steps 206 and 208 are NO), it means that the actual ignition timing TTP has not changed or changed in the opposite direction despite the change of the actual phase difference TP by the timer mechanism 6. Therefore, the CPU 32 considers that the pulse of the actual ignition timing signal detected by the vibration sensor 4 is due to noise, and the noise determination flag f
Set the flag (flag = 1). Such a series of noise discrimination processing is reflected in the routine of FIG.

The effects of this embodiment described in detail above will be summarized and described below. In the present embodiment, when the phase of the fuel injection timing by the timer mechanism 6 changes (when the actual phase difference TP changes), according to the phase change state of the actual ignition timing (change state of the actual ignition timing TTP) at that time, Whether or not the ignition timing detection signal detected by the vibration sensor 4 is due to noise is determined. The specific content is as described above (steps 204 to 208 in FIG. 9).

In short, when the vibration detection result of the vibration sensor 4 is detected as the ignition timing detection signal, the seating noise of the intake or exhaust valve may be erroneously detected as the ignition signal. However, the phase of the detection signal corresponding to the seating noise is originally fixed to the reference crank angle position of the engine, while the detection signal corresponding to actual ignition is fixed to the reference crank angle position by the timer mechanism. Produces a phase difference according to the injection timing control. Therefore, by determining the phase change state of the actual ignition timing TTP at the time when the actual phase difference TP is changed by the timer mechanism 6, it is possible to determine whether or not the ignition timing detection signal is due to noise.

If the pulse of the ignition timing detection signal detected by the vibration sensor 4 is not due to noise,
The target injection timing is corrected based on the ignition timing detection signal, and if there is noise, the correction of the target injection timing based on the ignition timing detection signal is prohibited (step 1 in FIG. 8).
09-111). Therefore, it is possible to avoid the problem that the noise is erroneously detected as the ignition timing detection signal and the control accuracy of the fuel injection timing is deteriorated. As a result, the accuracy of control of fuel injection by the fuel injection pump 2 can be improved.

In the present embodiment, the vibration sensor (knock sensor) detects the vibration generated when the engine burns as the ignition timing detecting means. However, when the knock sensor is used in a gasoline engine, It has the following differences. That is, in a gasoline engine, both noise caused by seating of an intake valve or an exhaust valve and vibration caused by knocking occur at a specific position in the rotational phase of the engine. Therefore, in order to remove the noise of the knock sensor, a method of masking the knock sensor output in a region other than a specific section of the engine rotation phase (for example, 10 to 50 ° CA after the compression top dead center) and monitoring the signal only in the section is known. Has been taken. On the other hand, in the diesel engine, the combustion is self-ignition, and the start of combustion (ignition timing) is closely related to the fuel injection start timing. That is, the phase of the ignition timing also changes in response to the phase change of the injection timing. From the above, the ignition timing of the diesel engine can be reliably detected by the vibration sensor (knock sensor).

Further, according to the configuration of the present embodiment, a new noise removing means is provided for the ignition timing detection signal from the vibration sensor 4, and the injection timing control region (engine speed, load, etc.) is limited. The injection timing control can be realized more easily and surely with no need to carry out.

(Second Embodiment) Next, a second embodiment of the present invention will be described.
An embodiment will be described. However, in the configuration of the present embodiment, the description of the same components as those in the above-described first embodiment will be omitted. Then, the differences from the first embodiment will be mainly described below. In addition, in the present embodiment, the CPU 32 constitutes an operating state determination means.

FIG. 14 shows a noise discrimination routine in this embodiment. In FIG. 14, the CPU 32 first determines in step 701 whether the engine operating state is a transient state, that is, whether the engine operating state is changing. This determination is performed based on, for example, the degree of change in the engine speed Ne and the load (accelerator opening degree, etc.). If the engine is not in the transient state, the CPU 32 proceeds to step 708 and clears the noise determination flag flag.

If the engine operating state is in a transient state, the processing from step 702 is executed. Step 7
The processing of 02 to 704 is performed in steps 201 to 20 of FIG.
This is the same as the processing of No. 3, and description thereof is omitted here. Further, the CPU 32 determines the presence or absence of noise in steps 705 to 707 depending on whether the changing directions of the actual phase difference TP and the actual ignition timing TTP are the same direction.

At this time, in the routine of FIG. 9, the noise determination of the ignition timing detection signal is performed in steps 204 and 205 based on the magnitude of the absolute values of the changes ΔθTP and ΔθTTP. In FIG. 14, since noise discrimination is performed only in the engine transient state, the above step 2 is performed.
The processing corresponding to 04 and 205 can be omitted.

Then, the CPU 32 executes steps 705 to 705.
Similar to 206 to 208 in FIG. 9, in 707, the actual ignition timing detected by the vibration sensor 4 is determined according to whether the actual phase difference variation ΔθTP and the actual ignition timing variation ΔθTTP are changing in the same direction. Determine whether the signal pulse is due to actual ignition (combustion) or noise.
In summary, when the changes ΔθTP and ΔθTTP change in the same direction, the CPU 32 clears the noise determination flag flag in step 708 (flag = 0). When the change amounts ΔθTP and ΔθTTP change in different directions, the CPU 32 sets the noise determination flag flag in step 709 (flag = 1).

In the second embodiment, the object of the present invention can be achieved as in the case of the above-described embodiment, and the following effects can be obtained. That is, when the engine operating state is the steady state, the phase change of the fuel injection timing by the timer mechanism 6 is small and the phase change of the actual ignition timing is also relatively small. Therefore, in the present embodiment, the noise determination of the ignition signal is performed only when it is determined that the engine operating state has changed. As a result, it is possible to significantly reduce the calculation load on the CPU 32 when the engine is stationary.

The present invention can be embodied in the following modes other than the above-described embodiment. (1) In the first embodiment, in FIG. 9, noise discrimination of the ignition timing detection signal is performed based on the magnitude of the amount of change in the actual phase difference and the actual ignition timing (step 20).
4, 205), the noise discrimination of the ignition timing detection signal is similarly performed based on the directionality of the actual phase difference and the variation amount of the actual ignition timing (steps 206 to 208), but this may be changed. For example, the processing of steps 204 and 205 or the processing of steps 206 to 208 may be applied to separate fuel injection control systems. Even in such a case, the noise determination flag flag is appropriately operated, and the adverse effect of noise on the injection timing control can be avoided.

(2) In the routine of FIG. 14 of the second embodiment, the noise determination flag was reset as it was without performing noise determination during engine steady operation (step 708), but this was changed. May be. For example, when the engine is in steady operation, the actual ignition timing change amount Δ
If θTTP (absolute value) exceeds a predetermined value, the noise determination flag flag may be set to determine that the pulse of the ignition timing detection signal is noise (NO in step 701 and | ΔθTTP | ≧ predetermined value,
flag = 1).

(3) In the noise discrimination processing, various parameters such as the actual phase difference TP, the actual phase difference change amount ΔTP, the actual ignition timing TTP, the actual ignition timing change amount ΔTTP are stored in the memory 33 in the microcomputer 31 for each cylinder. It may be stored and the noise determination and the injection timing control may be performed for each cylinder using the same cylinder data. In this case, the accuracy of controlling the fuel injection timing can be further improved.

(4) Actual phase difference TP, actual phase difference change amount ΔT
When P, the actual ignition timing TTP, and the actual ignition timing change amount ΔTTP are handled, they may be obtained by the time difference by the timer 34 or may be obtained by the angle difference corresponding to the engine speed. However, more accurate control can be achieved by obtaining the angle difference.

(5) As the ignition timing detecting means, in addition to the vibration sensor, a sensor for detecting combustion pressure or ion current, or a phototransistor for detecting combustion light can be applied.

(6) In the routine of FIG. 8, the actual injection amount Q is calculated when the basic target phase difference TB and the target ignition timing TTS are calculated.
Was used as a parameter, the accelerator opening may be used instead of this.

(7) In the above embodiment, the present invention is applied to the distributed type face cam type fuel injection pump, but it may be applied to the inner cam type fuel injection pump. Further, the invention can be similarly applied to a row-type injection pump that controls the injection timing by changing the rotational phase of the pump driven shaft and the crankshaft.

(8) In the above embodiment, as shown in FIG. 3, the same number of cylinders (4
One tooth 23a is provided, the detection result of the sensor 21 is output as a phase detection signal of the fuel injection pump 2, and the engine speed is detected by the same phase detection signal. This may be changed to another embodiment. For example, as shown in FIG.
(For example, 64 teeth in the case shown) are provided, and the same number of toothless portions 45a to 45d as the number of cylinders are provided. In such a case, the signal obtained by the phase detection sensor 21 is shaped as shown in FIG.
The waveform becomes 6. The time between the rising edges of the front and rear pulses of this signal is measured every time, the missing tooth is determined from the size of the time, and the next rising (G) of the missing tooth is detected. This G point can be used instead of the phase signal of the above-mentioned embodiment. In this case, the frequency of inputting the rotation information increases, and the fuel injection control can be stably performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a fuel injection control system in an embodiment of the invention.

FIG. 2 is a configuration diagram showing a timer mechanism of a fuel injection pump.

FIG. 3 is a configuration diagram showing a mounting state of a phase detection sensor.

FIG. 4 is a schematic configuration diagram showing a vibration sensor and a signal input circuit thereof.

FIG. 5 is a signal waveform diagram in each part of FIG.

FIG. 6 is an electric circuit diagram showing a reference position sensor and a signal input circuit thereof.

FIG. 7 is a signal waveform diagram showing a reference position signal, a phase detection signal, and an ignition timing detection signal.

FIG. 8 is a flowchart showing a fuel injection timing control routine in the first embodiment.

FIG. 9 is a flowchart showing a noise discrimination routine according to the first embodiment.

FIG. 10 is a flowchart showing a reference position interrupt routine.

FIG. 11 is a flowchart showing a phase signal interrupt routine.

FIG. 12 is a flowchart showing an ignition timing signal interrupt routine.

FIG. 13 is a flowchart showing a scheduled interrupt routine.

FIG. 14 is a flowchart showing a noise discrimination routine according to the second embodiment.

FIG. 15 is a diagram showing another embodiment of the phase detection sensor.

16 is a waveform diagram of a signal obtained by shaping the signal generated by the sensor of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine, 2 ... Fuel injection pump, 3 ... Reference position sensor as reference position detection means, 4 ... Vibration sensor as ignition timing detection means, 6 ... Timer mechanism, 32 ...
Actual ignition timing calculation means, target ignition timing calculation means, target injection timing calculation means, injection timing correction means, injection timing control means,
CPU as noise discriminating means, correction prohibiting means, operating state discriminating means.

Claims (5)

[Claims] 1. A fuel injection pump for supplying high-pressure fuel to an engine, a reference position detecting means for detecting a reference crank angle position of the engine, and a fuel injection pump for combustion of fuel injected and supplied to a cylinder of the engine. An ignition timing detection means for detecting an ignition signal, a timer mechanism for adjusting the fuel injection timing by the fuel injection pump, an actual ignition timing from a reference position signal by the reference position detection means and an ignition signal by the ignition timing detection means. An actual ignition timing calculating means for calculating, a target ignition timing calculating means for calculating a target ignition timing based on the engine operating state, a target injection timing calculating means for calculating a target injection timing based on the engine operating state, and the actual ignition The injection timing correction amount is calculated based on the deviation between the actual ignition timing calculated by the timing calculation means and the target ignition timing calculated by the target ignition timing calculation means. A fuel injection timing control device including: an injection timing correction unit that corrects the target injection timing with the injection timing correction amount; and an injection timing control unit that operates the timer mechanism based on the target injection timing, When the phase of the fuel injection timing is changed by the timer mechanism, noise determining means for determining whether or not the ignition signal detected by the ignition timing detecting means is due to noise according to the phase change state of the actual ignition timing at that time. And a correction prohibiting means for prohibiting correction of the target injection timing by the injection timing correcting means when the noise determining means determines that the ignition signal is noise. Timing control device. 2. The noise discriminating means, if the phase change of the fuel injection timing by the timer mechanism and the phase change of the actual ignition timing are in the same direction, the ignition signal detected by the ignition timing detecting means burns the fuel. The fuel injection timing control device according to claim 1, wherein the fuel injection timing control device determines that the ignition signal is caused by noise if the ignition signals are in different directions. 3. A fuel injection timing control device, comprising: an operating state determining means for determining whether or not the engine operating state has changed, wherein the noise determining means indicates that the engine operating state has changed by the operating state determining means. The fuel injection timing control device according to claim 1, wherein the noise determination of the ignition signal is performed only when the determination is made. 4. The ignition timing detecting means, when the phase change of the fuel injection timing by the timer mechanism is smaller than a predetermined value and the phase change of the actual ignition timing at that time exceeds a predetermined value. The fuel injection timing control device according to any one of claims 1 to 3, wherein the ignition signal detected by is determined to be due to noise. 5. The present invention is applied to a multi-cylinder diesel engine, and stores past actual ignition timing and fuel injection timing for calculating a phase change of the actual ignition timing and fuel injection timing for each cylinder. 5. The fuel injection timing control device according to any one of claims 1 to 4.