JPH11148401A - Fuel injection control device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain proper fuel injection even when injection start time is changed by lowering the open valve pressure of a fuel injection nozzle. SOLUTION: A fuel injection control device calculates real injection start time T from a detected value by a nozzle lift sensor for each cylinder during idling of a diesel engine (S110) and calculates a deviation ΔT between proper injection start time T0 stored in ROM and the real injection start time T (S120). And timing correction values Δθ1, Δθ2, and Δθ3 are calculated from weighted average value ΔTa of deviation ΔT (S140). A map stored in ROM is used for calculation of the timing correction values Δθ1, Δθ2, and Δθ3. The calculated timing correction values #>=θ1, Δθ2, and Δθ3 are renewed and stored in backup RAM (s150). And the switching valve timing of an electro-magnetic spill valve is corrected for each cylinder using these timing correction values.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for controlling a fuel injection amount to a diesel engine.

[0002]

2. Description of the Related Art Conventionally, as one of fuel injection control devices for a diesel engine, fuel is pressurized by a plunger reciprocating in synchronization with the rotation of the diesel engine.
The pressurized fuel is overflowed by an electromagnetic spill valve that opens and closes at a timing corresponding to the reciprocating motion of the plunger, while controlling the amount of fuel to be pressurized and supplied by feeding the fuel to the fuel injection nozzle of the diesel engine. Those using a fuel injection pump are known. In this fuel injection control device, the timing of opening and closing the electromagnetic spill valve is controlled to inject fuel from the fuel injection nozzle in an amount corresponding to the operating state of the diesel engine (engine speed, accelerator opening, etc.).

[0003] Further, there is known a technique for preventing a fuel ignition delay in main injection by performing so-called pilot injection prior to main injection when injecting fuel. When the pilot injection is performed, the injected fuel burns evenly and satisfactorily, so that the combustion noise is significantly reduced and the amount of harmful substances contained in the exhaust gas is significantly reduced. For this reason, some of the above-described fuel injection control devices are configured to execute pilot injection prior to main fuel injection by controlling the timing of opening and closing the electromagnetic spill valve of the fuel injection pump.

[0004]

A fuel injection nozzle for injecting fuel pumped from a fuel injection pump into a cylinder of a diesel engine has a valve body which is normally biased in a valve closing direction by a built-in spring. When the pressure of the fuel sent from the fuel injection pump gradually rises and reaches a so-called nozzle opening pressure (hereinafter simply referred to as “valve opening pressure”) which is a pressure threshold, the valve body opens. It is configured to move in the valve direction and start fuel injection. For this reason, it is desirable that the valve opening pressure of the fuel injection nozzle be always constant, but since the biasing force of the spring gradually decreases with time, the valve opening pressure also increases with time. And gradually decrease. Then, the fuel injection nozzle opens before the fuel pressure becomes sufficiently high,
The fuel injection start timing based on the fuel pressurization start timing is earlier than the shipping timing. On the other hand, the end timing of the fuel injection is determined by the opening timing of the electromagnetic spill valve, so that even if the valve opening pressure of the fuel injection nozzle decreases, the effect is very small. That is, the duration of the fuel injection becomes longer than at the time of shipment, and the fuel injection amount becomes larger than the appropriate value.
For this reason, the diesel engine cannot fully exhibit its original performance.

[0005] In particular, in order to maximize the effects such as the reduction of combustion noise and the amount of harmful substances contained in exhaust gas by pilot injection, the pilot characteristics, that is, the injection amount in pilot injection (hereinafter referred to as "pilot injection"). It is necessary to calculate and set the interval between the pilot injection and the main injection (hereinafter referred to as “pilot interval”) with extremely high accuracy. Since the injection start time is advanced, the pilot injection amount and the pilot interval do not match the appropriate values. For this reason, the above-mentioned effects cannot be sufficiently exhibited.

Accordingly, an object of the present invention is to provide a fuel injection control device capable of performing proper fuel injection even if the injection start timing changes due to a decrease in the valve opening pressure of the fuel injection nozzle. And

[0007]

Means for Solving the Problems and Effects of the Invention A fuel injection control device for a diesel engine according to claim 1 has been made to achieve such an object (hereinafter simply referred to as "fuel injection control device"). First, the operating state detecting means detects the operating state of the diesel engine, specifically, the engine speed, the operating load (accelerator opening), and the like, and the rotational position signal generating means detects the driving shaft of the fuel injection pump. To generate a rotation position signal. Then, the target timing calculating means calculates the opening / closing valve timing of the electromagnetic spill valve required to supply the diesel engine with an amount of fuel corresponding to the operating state based on the detected operating state and the rotational position signal. Then, the fuel injection control means opens and closes the electromagnetic spill valve according to the calculated opening / closing valve timing, and injects fuel from the fuel injection nozzle according to the operation state of the diesel engine. As a result, appropriate fuel injection according to the operating load is performed, and the diesel engine can be satisfactorily operated.

In the fuel injection control device according to the present invention, in parallel with such a series of controls, the actual injection start timing detecting means detects the fuel injection after the fuel pressurization by the plunger in the fuel injection pump is started. The actual injection start timing at which fuel is actually injected from the injection nozzle is detected as the rotation angle of the drive shaft based on the rotational position signal, and the target timing correction means detects the actual injection start timing and the injection start timing storage means. The opening / closing valve timing of the electromagnetic spill valve is corrected based on the deviation from the proper injection start timing stored in the fuel injection control unit, and the fuel injection control unit causes the electromagnetic spill valve to open / close at the corrected opening / closing valve timing.

That is, in the fuel injection control device according to the present invention, the valve opening pressure of the fuel injection nozzle decreases, and the actual injection start timing is earlier than the proper injection start timing.
Even if the fuel injection amount becomes larger than the proper value, the fuel injection amount can be returned to the proper value by correcting the opening / closing timing of the electromagnetic spill valve. Further, since the proper injection start timing is a constant value stored in the proper injection start timing storage means, the deviation can be calculated easily and accurately,
The on-off valve timing of the electromagnetic spill valve can be accurately corrected. For this reason, even if the valve opening pressure of the fuel injection nozzle decreases and the injection start timing changes, it is possible to perform appropriate fuel injection according to the operating state, and to maximize the performance of the diesel engine. it can.

A fuel injection control device according to a second aspect of the present invention is applied to pilot injection control, wherein the target timing calculating means sets the timing of opening and closing the electromagnetic spill valve as the timing of opening and closing the plunger in the fuel injection pump. A first target timing at which the electromagnetic spill valve is opened to terminate the pilot injection of fuel after the start of fuel pressurization, and a second target at which the electromagnetic spill valve is closed to start the main fuel injection after the pilot injection is completed. Calculating a target timing and a third target timing for closing the main injection by opening the electromagnetic spill valve after the start of the main injection, wherein the target timing correcting means calculates a deviation between the actual injection start timing and the proper injection start timing; Based on the first to first calculated by the target timing calculation means.
Each of the third target timings is corrected, and the fuel injection control means controls the pilot injection amount and the main injection amount of the fuel to the diesel engine by opening and closing the electromagnetic spill valve at each corrected target timing.

If the valve opening pressure of the fuel injection nozzle decreases and the pilot injection amount and the pilot interval do not match the appropriate values, the effect of the pilot injection may hardly be obtained in some cases. In the fuel injection control device described above, the pilot injection amount and the pilot interval that no longer match the appropriate values can be returned to the appropriate values by correcting the first to third target timings, respectively.
Therefore, appropriate pilot injection can always be performed, and effects such as reduction of combustion noise and reduction of the amount of harmful substances contained in exhaust gas can be maximized.

Here, the target timing correcting means is configured to calculate the target timing by the target timing calculating means based on a deviation between the actual injection start timing and the proper injection start timing during idling operation. The opening / closing valve timing of the spill valve may be corrected, and the electromagnetic spill valve may be opened / closed at the corrected opening / closing valve timing for the fuel injection control means.

At the time of idling, since the engine speed is low and the speed fluctuation is small, the actual injection start timing can be accurately detected. Therefore, in the case of such a configuration, the deviation between the actual injection start timing and the proper injection start timing can be obtained more accurately, and the opening / closing valve timing of the electromagnetic spill valve can be more accurately corrected.

[0014] In the fuel injection control device according to any one of claims 1 to 3, the actual injection start timing detecting means may include:
For example, as described in claim 4, a nozzle lift sensor that detects movement of a valve body provided in the fuel injection nozzle in the valve opening direction (hereinafter, referred to as “nozzle lift”) can be employed. The fuel pumped from the fuel injection pump is injected at the same time as the nozzle lift is started. Therefore, when a nozzle lift sensor is employed, the actual injection start timing can be easily and accurately obtained.

In addition, a fuel pressure sensor for detecting the fuel pressure in the pressurized chamber of the fuel injection pump can be employed. When the pressure chamber gradually narrows due to the movement of the plunger, the fuel pressure gradually increases. Then, when the fuel pressure reaches the valve opening pressure and the fuel injection nozzle opens, the pressurizing chamber and the cylinder communicate with each other to increase the substantial volume, so that the fuel pressure slightly decreases. That is, the fuel pressure drops immediately after the start of fuel injection. Therefore,
When the fuel pressure sensor is employed, the actual injection start timing can be easily obtained by detecting the timing when the fuel pressure in the pressurizing chamber slightly decreases.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection control device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of an electronically controlled diesel engine. Diesel engine 11 is supplied with intake air from air cleaner 12.

Downstream of the air cleaner 12, an intake air temperature sensor 13 for detecting the temperature of the intake air is provided. Downstream of the intake air temperature sensor 13, a turbocharger 14 utilizing exhaust gas energy is provided. A wastegate valve 15 is provided downstream of the turbocharger 14 to prevent an excessive increase in the supercharging pressure.

An intake throttle valve 18 is provided in an intake passage 16 which is a passage for the air taken in from the air cleaner 12 in response to a depression operation of an accelerator pedal 17. This intake throttle valve 18 is
It is opened and closed according to the amount of depression. This intake throttle valve 1
8 is detected by the accelerator position sensor 19 as the accelerator opening Accp. An intake pressure sensor 20 that detects the pressure of intake air is provided downstream of the intake throttle valve 18.

A fuel injection nozzle 21 and a glow plug 2 are provided on a cylinder head 111 of the diesel engine 11 such that a tip thereof protrudes into an engine combustion chamber 112.
2 are provided. In addition, the fuel injection nozzle 21 includes:
A nozzle lift sensor 21a is provided which detects a nozzle lift, which is a movement of a valve body (not shown) provided in the fuel injection nozzle 21 in the valve opening direction, and switches ON / OFF of a switch corresponding to valve opening / closing. The cylinder block 113 of the diesel engine 11 is provided with a water temperature sensor 23 for detecting the temperature of the engine cooling water and a reference position sensor 24 for detecting a rotation reference position corresponding to the crank angle of the diesel engine 11. ing.

The fuel from the fuel injection pump 30 is supplied to the fuel injection nozzle 21 under pressure. The fuel injection pump 30 includes a pump drive shaft 31 that rotates in conjunction with rotation of the crankshaft of the diesel engine 11.
The pump drive shaft 31 is connected to and engaged with the crankshaft of the diesel engine 11 by a timing belt (not shown) to form a power transmission system. This pump drive shaft 31
Is connected to a feed pump 32 for pressurizing the fuel (in this figure, the feed pump is developed at 90 °), and a rotary gear 33 having a large number of teeth formed on the peripheral surface is attached to the tip. . Although the teeth of the rotary gear 33 are provided at equal intervals, some of the corresponding portions are missing teeth because they are used to identify each cylinder of the diesel engine 11.
The feed pump 32 and the rotary gear 33
Is directly driven to rotate by a pump drive shaft 31 that makes one rotation every two rotations of the crankshaft of the diesel engine 11.

At a position close to the outer peripheral surface of the rotary gear 33, a rotation sensor 35 attached to a roller ring 34
Is provided. The rotation sensor 35 is constituted by an electromagnetic pickup, and each tooth of the rotation gear 33 is
The pulse-shaped rotation position signal is output each time the signal passes through the vicinity of the reference numeral 5.

The pump drive shaft 31 is further provided with a face cam 36. When the face cam 36 rotates with the rotation of the pump drive shaft 31, the face cam 36 rides on the roller 34a provided on the roller ring 34, and reciprocates the plunger 37 in the axial direction. The reciprocating motion of the plunger 37 increases or decreases the volume of the pressurizing chamber 44. When the volume increases, fuel is sucked into the pressurizing chamber 44, and when the volume decreases, the fuel is pressure-fed to a delivery valve 42 described later. The timing of the reciprocating operation of the plunger 37 is determined by the rotational angle position of the roller ring 34. The rotation angle position of the roller ring 34 is variably controlled by a timer piston 38 (shown in a 90-degree development in this figure). Further, the position of the timer piston 38 is controlled by a timer control valve 39 (hereinafter, “TCV39”).
). That is, the TCV 39 controls the timing of the reciprocating operation of the plunger 37, and controls the fuel injection timing.

An electromagnetic spill valve 41 is connected to the pressurizing chamber 44 via a spill port 40. Electromagnetic spill valve 4
In a state where the valve 1 is closed, as described above, the fuel is pumped along with a decrease in the volume of the pressurizing chamber 44. However, in a state where the electromagnetic spill valve 41 is opened, the volume of the pressurizing chamber 44 is Is reduced, the fuel is released from the spill port 40 to the low pressure side of the fuel injection pump 30, and the pressure in the pressurizing chamber 44 does not increase. That is, the fuel injection amount is controlled by the electromagnetic spill valve 41. Here, the electromagnetic spill valve 41 is closed when energized, and the spill port 40 is closed.

When the fuel compressed according to the operation of the plunger 37 reaches a predetermined pressure in the pressurizing chamber 44, the fuel is discharged through the delivery valve 42 for preventing the fuel from flowing backward or drooping, and is discharged to the diesel engine 11. It is supplied to the arranged fuel injection nozzle 21. Thus, the fuel is injected from the fuel injection nozzle 21.

Intake air temperature sensor 13, accelerator position sensor 1
9, intake pressure sensor 20, water temperature sensor 23, rotation sensor 3
5. Detection signals from the nozzle lift sensor 21a and the like are supplied to a control circuit 43 which is an electronic control unit. The control circuit 43 processes an input signal from each sensor, and outputs a TC signal based on an output signal from the control circuit 43.
V39, the electromagnetic spill valve 41 and the like are controlled.

FIG. 2 is a diagram showing the configuration of the control circuit 43. The control circuit 43 is constituted by a microcomputer. The control circuit 43 includes a central processing unit (CP
U) 51, a ROM 52 for storing a control program and various data, a RAM 53 for temporarily storing operation data and the like in the CPU 51, a clock oscillator 54 for generating a clock signal, and the like.

Intake temperature sensor 13, accelerator position sensor 1
9, detection signals from the intake pressure sensor 20 and the water temperature sensor 23 are input to the multiplexer 55 via the respective buffers. The multiplexer 55 selects and outputs the input signals from the respective sensors in order and supplies the signals to the A / D converter 56. The input data from each sensor converted into digital data by the A / D converter 56 is supplied to an input / output port 57. The data input from the input / output port 57 is further processed by the CPU 5.
1, are communicated by a data bus 58 connecting the ROM 52 and the RAM 53, and are used for various arithmetic processing.

On the other hand, the rotation sensor 35 and the reference position sensor 2
4 output a pulse-like detection signal, and the waveform is shaped by the provided waveform shaping circuits 59 and 60, and is then taken into the CPU 51. Similarly, the output from the nozzle lift sensor 21a is also shaped by the waveform shaping circuit 70 before being taken into the CPU 51.

The CPU 51 computes and outputs control signals to the TCV 39 and the electromagnetic spill valve 41 based on these input data. These outputs are supplied as drive command signals to the TCV 39 and the electromagnetic spill valve 41 via drive circuits 61 and 62, respectively.

The diesel engine 1 configured as described above
In the first control device, since the rotation sensor 35 is attached to the roller ring 34, when the timer piston 38 is moved and the roller ring 34 rotates, the rotation sensor 35 also rotates integrally with the roller ring 34. Therefore, the relative position on the time axis between the cam angle of the face cam 36 and the rotation position signal detected by the rotation sensor 35 does not change even when the timer piston 38 moves.

Therefore, since the timing of the reciprocating operation of the plunger 37, that is, the fuel injection timing, can be detected from the rotational position signal, the electromagnetic spill valve 41 is energized based on the position of each pulse whose rotational position signal is shaped. ON /
The timing of turning off is determined, and the fuel injection amount is controlled.

Here, the position of each pulse is recognized by detecting a missing tooth position corresponding to the number of cylinders of the rotary gear 33. Then, the rotational position (angle) of the pump drive shaft 31 can be detected by detecting the position of the missing tooth and recognizing the order of each pulse detected subsequently.

In the injection timing control, the position of the timer piston 38 is moved by controlling the amount of the fuel in the high-pressure chamber 381 of the timer piston 38 to which the fuel pressure in the pump is applied to escape to the low-pressure chamber 382 via the TCV 39. This is performed by rotating the roller ring 34. here,
The TCV 39 is controlled by a command from the control circuit 43. The fuel injection timing is set to the most retarded side when the TCV 39 is turned on, and is set to the most advanced state when the TCV 39 is turned off. That is, the duty ratio control of the TCV 39 enables the feedback control of the fuel injection timing.

In the fuel injection control device configured as described above, fuel injection is performed as shown in the timing chart of FIG. First, in the initial state, as shown by the solid line, the electromagnetic spill valve 41 is closed at a timing before the reference position (0 °) immediately after the reference pulse corresponding to the missing tooth position of the rotary gear 33 is input. . When the rotational position of the pump drive shaft 31 exceeds the reference position (0 °) and the face cam 36 rides on the roller 34a, the pressurizing chamber 44
Is compressed, and the fuel pressure gradually increases. When the fuel pressure exceeds the valve opening pressure of the fuel injection nozzle 21, fuel is injected from the fuel injection nozzle 21 (pilot injection is started). Then, by counting the number of pulses of the rotational position signal, the target timing θ1 which is the timing for ending the pilot injection is detected, and when the target timing θ1 is reached, the electromagnetic spill valve 41 is opened.
Then, the fuel pressure immediately decreases, and the pilot injection ends accordingly. Then, similarly, when the target timing θ2, which is the timing for starting the main injection, is reached, the electromagnetic spill valve 41 is closed again to start the main injection. Then, when the target timing θ3, which is the timing for terminating the main injection, has been reached, the electromagnetic spill valve 41 is opened again to terminate the main injection. Here, the target timing θ1 corresponds to the above-described first target timing, and similarly, the target timings θ2 and θ3 correspond to the second and third target timings, respectively.

Next, the situation when the valve opening pressure of the fuel injection nozzle 21 is reduced will be described with broken lines. In this case, pilot injection is started before the fuel pressure becomes sufficiently high. That is, as shown in FIG.
1 in the state where the valve opening pressure has decreased (hereinafter, referred to as “actual injection start timing T”).
Is a proper pilot injection start timing T in the initial state.
0 (hereinafter referred to as “appropriate injection start timing T0”). If the target timing θ1 remains in the initial state with the pilot injection start timing advanced in this way, the time during which the pilot injection is being performed becomes longer than in the initial state, and the pilot injection amount increases. . Further, the pilot injection end timing is slightly delayed and the main injection timing is advanced, so that the pilot interval is shortened. Therefore, both the pilot injection amount and the pilot interval value do not coincide with the proper values, so that the effect obtained by performing the pilot injection, that is, the combustion noise is significantly reduced, and the amount of harmful substances contained in the exhaust gas is reduced. Cannot be sufficiently exhibited.

Therefore, in this fuel injection control device, if the pilot injection is not properly performed due to the decrease in the valve opening pressure of the fuel injection nozzle 21, the target timings θ1, θ2, and θ3 are reset. Amend,
Return the pilot injection amount and pilot interval to appropriate values.

The processing for setting and correcting the target timings θ1, θ2 and θ3 will be described with reference to the flowcharts shown in FIGS. First, the processing of the main routine shown in FIG. 4 will be described. This process is executed every predetermined time. When the processing of the main routine is started, the CPU 51 first reads values detected by the intake air temperature sensor 13, the accelerator position sensor 19, the intake pressure sensor 20, the water temperature sensor 23, the reference position sensor 24, and the rotation sensor 35 (S10). ). Then, the reference position sensor 24
Engine speed calculated from the rotation reference position corresponding to the crank angle detected by the
The provisional fuel injection amount and the fuel injection timing are calculated based on the accelerator opening detected from. The map stored in the ROM 52 is used for calculating the fuel injection amount and the fuel injection timing. The calculated fuel injection amount and fuel injection timing are taken into consideration by taking into account the intake air temperature detected by the intake air temperature sensor 13, the intake pressure calculated by the intake pressure sensor, and the water temperature calculated by the water temperature sensor 23. The target injection amount, which is the fuel injection amount, is calculated (S20), and the target injection timing, which is the optimal fuel injection timing, is calculated (S30). Subsequently, the CPU 51 calculates the duty ratio of the TCV 39 from the calculated target injection amount and target injection timing (S40), and sets the target timings θ1 and θ.
2 and θ3 are calculated (S50).

The processing from S10 to S50 is a processing that has been performed in the past, but in this fuel injection control device, following these processing, it is obtained for each cylinder by a correction value calculation routine described later. Timing correction value △
Based on θ1, Δθ2, and Δθ3, the target timings θ1, θ2, and θ3 are corrected for each cylinder (S60). In addition,
The values of the timing correction values △ θ1, △ θ2, and △ θ3 are 0 until obtained by the correction value calculation routine.

Next, the processing of the correction value calculation routine shown in FIG. 5 will be described. This process is executed for each cylinder during the idle operation of the diesel engine. When the processing of this correction value calculation routine is started, the CPU 51 first calculates the actual injection start timing T from the value detected by the nozzle lift sensor 21a (S110). Then, the proper injection start time T0 stored in the ROM 52 as the above-described proper injection start time storage means is read, and a deviation ΔT between the proper injection start time T0 and the actual injection start time T is calculated (S120). Next, a weighted average value ΔTa of the deviation ΔT is obtained. The value of ΔTa is obtained by (7 △ Ta + △ T) / 8, and the value is updated each time it is calculated (S130). Note that the initial value of ΔTa is 0. Subsequently, the timing correction values △ θ1, △ θ2, and △ θ3 are calculated from the deviation weighted average value △ Ta (S140). Note that the timing correction values {θ1, △
The maps stored in the ROM 52 are used for calculating θ2 and △ θ3. Then, the calculated timing correction values △ θ1, △ θ2 and △ θ3 are stored in the backup RAM.
The updated information is stored in the memory 53 (S150).

When such processing is performed, the fuel injection nozzle 2
Even if the valve opening pressure decreases, the pilot injection amount and the pilot interval can be returned to appropriate values. Specifically, the fuel injection is performed as shown by the one-dot chain line in FIG. That is, in order to advance the end timing by an amount corresponding to the earlier start timing of the pilot injection, the valve opening timing of the electromagnetic spill valve 41 is advanced by △ θ1 from the target timing θ1, and the pilot interval is made to coincide with an appropriate value. The valve closing timing of the electromagnetic spill valve 41 is advanced from the target timing θ2 by △ θ2, and the valve opening timing of the electromagnetic spill valve 41 is advanced by △ θ3 from the target timing θ3 in order to make the injection amount in the main injection coincide with an appropriate value. As a result, the pilot injection amount and the pilot interval are returned to appropriate values.

As described above, in the fuel injection control device according to the present embodiment, the valve opening pressure of the fuel injection nozzle 21 is reduced, and the actual injection start timing T is earlier than the proper injection start timing T0. Is larger than the appropriate value, the opening / closing valve timing (the target timings θ1, θ2, and θ3) of the electromagnetic spill valve 41 is changed to the timing correction value Δθ.
The fuel injection amount can be returned to an appropriate value by performing correction using 1, △ θ2 and △ θ3. Further, since the proper injection start time T0 is a constant value stored in the ROM 52, the deviation ΔT can be easily and accurately calculated, and the opening / closing timing of the electromagnetic spill valve 41 can be accurately corrected. For this reason, even if the valve opening pressure of the fuel injection nozzle 21 decreases and the injection start timing changes, it is possible to perform appropriate fuel injection according to the operating state and maximize the performance of the diesel engine 11. In addition to this, the effect of pilot injection, that is, the effect of reducing combustion noise and the amount of harmful substances contained in exhaust gas, can be maximized.

Further, the fuel injection control device of the present embodiment is configured to detect the actual injection start timing T during idling operation to determine the deviation ΔT. During idling operation, the engine speed is low and the rotation fluctuation is small, so that the actual injection start timing T can be detected more accurately, and the deviation ΔT can be calculated more accurately.

Further, in the fuel injection control device of the present embodiment, the actual injection start timing is detected by detecting the movement of the valve element provided in the fuel injection nozzle 21 in the valve opening direction using the nozzle lift sensor 21a. Since T is determined, detection is easy and accurate. In this embodiment, the rotation sensor 35 corresponds to the above-described rotation position signal generating means,
The accelerator position sensor 19 and the reference position sensor 24 correspond to the above-described operating state detecting means, the processing of S10 to S30 in the main routine corresponds to the processing of the target timing calculating means, and the processing of S40 and S50 in the main routine. The ROM 52 corresponds to the above-described proper injection start timing storage means, the nozzle lift sensor 21a corresponds to the above-described actual injection start timing detection means, and corresponds to the processing in the main routine.
The processing of 60 and the processing of the correction value calculation routine correspond to the processing of the target timing correction means.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention may be implemented in various modes. For example, in the above-described embodiment, the nozzle lift sensor 21a provided in the fuel injection nozzle 21 is employed as the actual injection start timing detecting means, but a fuel pressure sensor 44a indicated by a broken line in FIG. 1 may be employed. As shown in FIG. 3, the fuel pressure gradually rises with the movement of the plunger 37, and slightly drops when the fuel pressure reaches the valve opening pressure and the injection is started. By detecting the falling timing, the actual injection start timing T
Can be easily obtained. Further, two sensors may be used in combination.

In the above embodiment, the electromagnetic spill valve 41
Although only the opening / closing timing is corrected, the control amount of the timer control valve 39 may be further corrected. In this case, the correction can be made more smoothly and appropriately. In the above embodiment, the timing correction values △ θ1, △ θ2, and △ θ3 are repeatedly calculated and updated during the idling operation. However, during the idling operation, only the deviation weighted average value △ Ta is calculated and the idling operation is performed. , The timing correction values △ θ1, △ θ2, and △ θ3 may be calculated and updated.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing a fuel injection control device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating an electrical configuration of a fuel injection control device according to one embodiment of the present invention.

FIG. 3 shows a fuel injection control device according to one embodiment of the present invention, in which a rotation position signal generated by rotation of a pump drive shaft, an opening / closing timing of an electromagnetic spill valve, a fuel pressure change, 5 is a timing chart illustrating a relationship with a nozzle lift amount.

FIG. 4 is a flowchart illustrating a process of a main routine for calculating an opening / closing timing of an electromagnetic spill valve in the fuel injection control device according to the embodiment of the present invention;

FIG. 5 is a flowchart illustrating a process for calculating a correction value of the opening / closing valve timing of the electromagnetic spill valve in the fuel injection control device according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 ... Diesel engine 19 ... Accelerator position sensor 20 ... Intake pressure sensor 21 ... Fuel injection nozzle 21
a: Nozzle lift sensor 23: Water temperature sensor 24: Reference position sensor 35
Rotation sensor 39 Timer control valve (TCV) 41 Electromagnetic spill valve 43 Control circuit 44 Pressurizing chamber 44a Fuel pressure sensor.

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ Identification code FI F02D 45/00 322 F02D 45/00 322C 358 358Z F02M 65/00 306 F02M 65/00 306B

Claims (5)

[Claims] A driving shaft that rotates in synchronization with the rotation of the diesel engine; a reciprocating motion of a plunger accompanying the rotation of the driving shaft draws fuel into the pressurizing chamber and adds fuel in the pressurizing chamber. A fuel injection pump that pressurizes and pressurizes the pressurized fuel to a fuel injection nozzle provided in the diesel engine; and a valve that is provided in the fuel injection pump and is opened and closed at a predetermined timing corresponding to the reciprocation of the plunger. An electromagnetic spill valve for causing pressurized fuel in the pressurized chamber to overflow to the low pressure side of the fuel injection pump at the time of valve operation; and a rotational position signal for detecting a rotational position of a drive shaft of the fuel injection pump and generating a rotational position signal. Generating means, operating state detecting means for detecting an operating state of the diesel engine, based on the detected operating state and the rotational position signal,
Target timing calculation means for calculating the opening / closing valve timing of the electromagnetic spill valve required to supply the diesel engine with an amount of fuel corresponding to the operation state thereof, and according to the calculation result of the target timing calculation means. Fuel injection control means for opening and closing the electromagnetic spill valve to inject fuel corresponding to the operating state of the diesel engine from the fuel injection nozzle, wherein the fuel injection pump comprises: After the fuel pressurization by the plunger is started, the proper injection start time, which is the proper time at which fuel injection from the fuel injection nozzle is started, is stored in association with the rotation angle of the drive shaft. After the fuel pressurization is started by the plunger in the fuel injection pump, the storage means, An actual injection start timing detecting means for detecting an actual injection start timing, which is a timing at which fuel injection is started, as a rotation angle of the drive shaft based on the rotational position signal; and Based on the deviation from the injection start timing, the electromagnetic spill valve opening / closing valve timing calculated by the target timing calculating means is corrected, and the fuel injection control means is provided with the corrected spill valve timing based on the corrected opening / closing valve timing. A fuel injection control device for a diesel engine, comprising: target timing correction means for opening and closing a valve. 2. The fuel injection control apparatus according to claim 1, wherein the target timing calculating means opens and closes the electromagnetic spill valve after the start of pressurization of the fuel by the plunger in the fuel injection pump and performs pilot injection of fuel. A second target timing for closing the electromagnetic spill valve to start the main fuel injection after the end of the pilot injection, and for opening the electromagnetic spill valve after the start of the main injection. Calculating a third target timing for terminating the main injection, wherein the target timing correcting means calculates the first target timing calculated by the target timing calculating means based on a deviation between the actual injection start timing and the proper injection start timing. Correcting each of the third target timings, wherein the fuel injection control means opens and closes the electromagnetic spill valve at each corrected target timing. More, the fuel injection control apparatus for a diesel engine according to claim 1, characterized in that to control the pilot injection quantity and the main injection amount of fuel to the diesel engine. 3. An electromagnetic spill valve opening / closing valve timing calculated by the target timing calculation means based on a deviation between the actual injection start time and the proper injection start time during idling operation. 3. The fuel injection control device for a diesel engine according to claim 1, wherein the electromagnetic spill valve is opened / closed at the corrected opening / closing valve timing by the fuel injection control means. 4. . 4. The actual injection start timing detecting means includes a nozzle lift sensor for detecting a movement of a valve body provided in the fuel injection nozzle in a valve opening direction, wherein the valve body moves in the valve opening direction. The fuel injection control device for a diesel engine according to any one of claims 1 to 3, wherein a timing to start the fuel injection is detected as the actual injection start timing. 5. The actual injection start timing detecting means includes a fuel pressure sensor for detecting a fuel pressure in the pressurized chamber of the fuel injection pump, and after the fuel pressurization by the plunger is started, the fuel injection nozzle is opened. The fuel injection control device for a diesel engine according to any one of claims 1 to 3, wherein a timing at which the fuel pressure in the pressurized chamber falls by opening the valve is detected as the actual injection start timing.