JP2001355500A - Fuel injection device for multicylinder engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic control accumulation fuel injection system for diesel engine capable of inhibiting an engine vibration of a whole V type 6-cylinder diesel engine 10 and also inhibiting a mechanical engine inherent vibration which every cylinder has. SOLUTION: When an unloading state of a diesel engine 10 is detected, a rotation speed variation every in explosion stroke of the respective cylinder is detected. An average value of the rotation speed variation of all cylinders is compared with a detection value of the rotation speed variation of every cylinder. A FCCB study control for compensating a fuel injection amount to the respective cylinders of the diesel engine 10 is carried out so as to flatten the rotation speed variation every in the explosion stroke of the respective cylinders based on this comparison result. Thereafter, an injection amount weight is added to a fuel injection amount to a specific cylinder being a vibration source so as to reduce a mechanical inherent vibration which every cylinder has. Thereby, not only an engine vibration of the whole engine is inhibited but also a mechanical engine inherent vibration which every cylinder has can be inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection system for a multi-cylinder engine provided with a plurality of fuel injection valves for injecting fuel into each cylinder of the multi-cylinder engine, and more particularly to a high-pressure fuel discharged from a fuel injection pump. The present invention relates to a pressure-accumulating fuel injection device for a multi-cylinder engine having a common rail for accumulating fuel.

[0002]

2. Description of the Related Art Conventionally, from the viewpoint of strengthening regulations on exhaust gas, protecting the global environment, and improving the operability of an engine, a fuel pumped from a fuel tank by a low-pressure supply pump is pressurized by a high-pressure supply pump to form a pressure accumulation chamber. Pressure on the common rail
The high-pressure fuel stored in the common rail is injected into the combustion chamber of each cylinder of the diesel engine by energizing or stopping energizing a plurality of electromagnetic fuel injection valves connected to fuel pipes branched from the common rail for each cylinder. Pressure accumulating type fuel injection device for a diesel engine (Japanese Patent Application Laid-Open Nos. 59-82534 and 62-258160).
And the like) have been proposed.

[0003]

However, in a diesel engine, engine vibrations are generated due to fluctuations in the rotational speed of each cylinder during the explosion stroke due to variations in the explosive power between the cylinders. In particular, in a no-load state of the diesel engine, that is, in an idling state in which the rotation speed is low, the engine vibration and noise may give a discomfort to the driver. It is known that fluctuations in rotational speed between cylinders are caused by variations in fuel injection amount between cylinders due to individual differences in fuel injection valves for each cylinder and combustion factors of a diesel engine.

[0004] Therefore, in order to reduce the rotational speed fluctuation between cylinders, an optimum rotational speed fluctuation between cylinders is detected by detecting the rotational speed fluctuation at each explosion stroke of each cylinder. An unequal amount compensation control (FCCB learning control) for individually compensating the fuel injection amount is performed. The unequal amount compensation control detects the average value of the rotational speed fluctuations of all cylinders after detecting the rotational speed fluctuations of each cylinder of the diesel engine during the explosion stroke while detecting the no-load state of the diesel engine. By comparing with the detected value of rotation speed fluctuation for each cylinder,
The fuel injection amount to each cylinder is corrected so as to smooth the rotational speed fluctuation between the cylinders.

However, the above unequal amount compensation control (FCC)
B learning control) can reduce the engine vibration of the entire diesel engine, but it is impossible to reduce the mechanical vibration (engine-specific vibration) of each cylinder of the diesel engine. Therefore, even in the no-load state of the diesel engine, that is, in the idling state where the rotation speed is low, it is impossible to reduce the natural vibration of the engine, which causes a problem that the driver feels uncomfortable.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection device for a multi-cylinder engine which can suppress engine vibration of the entire multi-cylinder engine and also suppress mechanical inherent vibration of each cylinder. Is to provide.

[0007]

According to the first aspect of the present invention, rotation speed fluctuations of each cylinder of a multi-cylinder engine for each explosion stroke are detected, and rotation speed fluctuations of each cylinder for each explosion stroke are smoothed. By correcting the fuel injection amount to each cylinder of a multi-cylinder engine individually, the fluctuation of the rotation speed between cylinders due to the variation of the explosion force between cylinders due to the individual difference of the fuel injection valve The engine vibration of the entire multi-cylinder engine can be suppressed. Estimating a specific cylinder that generates mechanical natural vibration for each cylinder of the multi-cylinder engine, and correcting the fuel injection amount to the specific cylinder so as to reduce the estimated natural vibration of the specific cylinder. Thereby, the mechanical natural vibration of each cylinder can be suppressed. Therefore, the discomfort of the driver can be eliminated.

According to the second aspect of the present invention, each time the no-load state of the multi-cylinder engine is detected or estimated by the no-load state detecting means, the first injection amount correcting means or the second injection amount correcting means is used. By performing at least one of the injection amount correction means at least once, the engine vibration of the entire multi-cylinder engine or the mechanical natural vibration of each cylinder can be suppressed. , The discomfort of the driver can be eliminated.

According to the third aspect of the invention, each time the no-load state of the multi-cylinder engine is detected or estimated by the no-load state detecting means, the first injection is performed after the second injection amount correcting means is implemented. By prohibiting the amount correcting means, after suppressing the vibration specific to the specific cylinder, it is possible to prohibit the unequal amount compensation control for increasing the vibration specific to the specific cylinder again. In the middle, it is possible to prevent the control output to the fuel injection valve of the specific cylinder from fluctuating excessively.

According to the present invention, the average value of the rotational speed fluctuations of all the cylinders is compared with the detected value of the rotational speed fluctuations of each cylinder. Then, based on the comparison result, the fuel injection amount to each cylinder is compensated. For example, by providing unequal amount compensation control means for correcting (increase or decrease by the injection amount correction amount) a uniform basic injection amount for all cylinders determined according to the operating state of the multi-cylinder engine, The variation in the fuel injection amount injected from the injector to each cylinder, that is, the uneven amount of the fuel injection amount to each cylinder is reduced, and the rotational speed fluctuation between the cylinders due to the individual difference of the fuel injector is reduced. Therefore, engine vibration of the entire multi-cylinder engine can be suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 to FIG. 8 show an embodiment of the present invention. FIG. 1 is a diagram showing the overall configuration of an electronically controlled accumulator type fuel injection system for a diesel engine, and FIG. FIG. 3 is a diagram illustrating an injection amount calculation map, and FIG. 3 is a diagram illustrating a behavior of a rotation speed variation of each cylinder of a diesel engine for each explosion stroke.

The electronically controlled accumulator type fuel injection system for a diesel engine according to this embodiment corresponds to the fuel injection system for a multi-cylinder engine of the present invention, and is called a common rail type fuel injection system (accumulator type fuel injection system). . The fuel injection system includes a plurality of fuel injection valves 1 to 6 mounted corresponding to respective cylinders (cylinders) # 1 to # 6 of a diesel engine 10 mounted in an engine room of a vehicle such as an automobile; A variable discharge type fuel injection pump 7 for pressurizing the fuel, a common rail 8 which is a kind of surge tank for accumulating high pressure fuel discharged from the fuel injection pump 7, a plurality of fuel injection valves 1 to 6, and fuel injection. An electronic control unit for engine control (hereinafter referred to as ECU) 9 for electronically controlling each actuator of the pump 7 is provided.

The diesel engine 10 of the present embodiment corresponds to the multi-cylinder engine of the present invention, and each of the cylinders # 1 to # 1
# 6 is divided into two banks (cylinder head, cylinder block), and each bank is driven by a V-type 6-cylinder direct injection diesel engine in which each bank is arranged in a V-shape around a crankshaft. Work as a vehicle driving engine.

The two cylinder heads of the diesel engine 10 have intake pipes (not shown) including intake manifolds for sucking air into the combustion chamber from the intake ports of the cylinders # 1 to # 6. Exhaust pipes (not shown) including exhaust manifolds for exhausting exhaust gas generated in the combustion chamber from exhaust ports # 1 to # 6 are respectively attached. The engine torque (output) of the diesel engine 10 is controlled by the amount of fuel injected into the combustion chambers of the cylinders # 1 to # 6.

A plurality of fuel injection valves (fuel injection nozzles: hereinafter referred to as injectors) 1 to 6 of this embodiment are respectively connected to downstream ends of a plurality of fuel pipes 21 to 26 communicating with the common rail 8. . From these injectors 1 to 6, each cylinder # 1 to # of the diesel engine 10
The injection of fuel into the combustion chamber of each of the injectors 1 to 6
Energizing and stopping energizing (O) the plurality of injection amount control solenoid valves (corresponding to injection amount control actuators) 11 to 16 provided in the middle of each of the fuel pipes 21 to 26 corresponding to
N / OFF).

Each of the injectors 1 to 6 connects a plurality of (six in this example) fuel pipes 21 to 26 while the injection amount control solenoid valves 11 to 16 are open (valve opening period). The high-pressure fuel supplied from the common rail 8 is injected into the combustion chamber of each cylinder of the diesel engine 10 via the common rail 8. The amount of fuel injected into the combustion chamber of each cylinder of the diesel engine 10 depends on the valve opening period of each of the injectors 1 to 6 (the time from when the valve element opens until the valve closes) and the injection pressure (common rail described later). Pressure).

In the common rail 8, it is necessary to continuously accumulate a relatively high predetermined common rail pressure (for example, 20 to 30 MPa) corresponding to the fuel injection pressure. A fuel injection pump (supply pump: hereinafter referred to as a high-pressure supply pump) 7 is connected via a valve 32.

The high-pressure supply pump 7 of this embodiment is driven by the diesel engine 10 to rotate,
A known low-pressure supply pump 34 for pumping fuel from the fuel cell is built in. The high-pressure supply pump 7 pressurizes the fuel sucked into the pump chamber via the low-pressure supply pump 34 to a high pressure and discharges the fuel to the common rail 8 via the fuel supply pipe 31. The adjustment of the discharge amount of the high-pressure supply pump 7 is performed by energizing and stopping energization (ON / OFF) of the injection pressure control solenoid valve 27.
OFF).

The ECU 9 of the present embodiment is configured to include the function of the injection amount control device of the present invention. And ECU
Numeral 9 includes the functions of the rotational speed fluctuation detecting means and the specific cylinder estimating means. Inside the ECU 9, a CPU for performing control processing and arithmetic processing, memories (ROM, RAM) for storing various control programs and various data,
A microcomputer including functions such as an I / O port (input / output circuit), a power supply circuit, and a drive circuit is provided. The ECU 9 is configured so that sensor signals from various sensors are A / D converted by an A / D conversion circuit and then input to a microcomputer.

Basic sensors input to the ECU 9 include:
A crank angle sensor 41 for detecting a rotation angle of a crankshaft of the diesel engine 10, an accelerator opening sensor 42 as a load detecting means for detecting a depression amount of an accelerator pedal (accelerator opening: AC), a cooling water temperature of the diesel engine 10. Water temperature sensor 43 as a cooling water temperature detecting means for detecting a fuel temperature, a fuel temperature sensor 44 as a fuel temperature detecting means for detecting a fuel temperature, and a vehicle speed sensor 4 for detecting a running speed (vehicle speed) of a vehicle such as an automobile.
There are 5 magnitudes.

The accelerator opening sensor 42 corresponds to the no-load state detecting means of the present invention. Further, the vehicle speed sensor 45 corresponds to the no-load state detecting means of the present invention, and constitutes a running state detecting means of a vehicle such as an automobile. The crank angle sensor 41, the accelerator opening sensor 42, the cooling water temperature sensor 43, and the fuel temperature sensor 44 are operating state detecting means for detecting the operating state of the diesel engine 10.

Here, the crank angle sensor 41 corresponds to the rotational speed fluctuation detecting means of the present invention, and comprises a timing rotor made of a magnetic material which rotates in synchronization with the crankshaft of the diesel engine 10, and an outer surface of the timing rotor. And an electromagnetic rotation sensor including a permanent magnet that generates a magnetic flux, and the like, and an electromagnetic pickup disposed opposite to the electromagnetic pickup. Note that the ECU 9 outputs the crank angle signal (NE
The engine rotation speed (NE) can be detected by measuring the interval time between the pulse signals.

In this embodiment, one cycle of the diesel engine 10 (intake stroke, compression stroke, explosion stroke, exhaust stroke),
That is, the crankshaft of the diesel engine 10 is 2
24 teeth are provided on the outer surface of the timing rotor so that 48 crank angle signals (1 pulse 15 ° CA) are generated during rotation (720 ° CA). Note that the specific NE pulse corresponds to the top dead center (TD
C).

The ECU 9 determines that the engine speed is equal to or less than a predetermined value (for example, NE = 1000 rpm), the engine load (accelerator opening) is equal to or less than a predetermined value (for example, AC = 0%),
By determining whether the vehicle speed is equal to or less than a predetermined value (for example, SPD = 0 km / h), an idling state in which the engine speed of the diesel engine 10 is low (no-load state)
It is configured to include a function of a no-load state detecting means for detecting whether or not the condition is true.

When the parking brake ON signal is input, or when the select lever is in the N range or the P range,
By combining input information, such as when it is detected that the clutch pedal is being depressed when operating in the range, the no-load state of the diesel engine 10 can be more effectively detected.

The ECU 9 controls the injection pressure control solenoid valve 27 so that the injection pressure of the high-pressure supply pump 7 becomes an optimum value in accordance with the engine speed and the engine load (accelerator opening).
To output a control signal. More preferably, a rail pressure sensor 46 as a rail pressure detecting means for detecting the pressure in the common rail 8 (common rail pressure) is provided on the common rail 8, and a sensor signal from the rail pressure sensor 46 is used in advance to determine the engine rotation speed ( NE) and discharge amount control means for controlling the discharge amount discharged from the high-pressure supply pump 7 to the common rail 8 so as to have an optimal pressure value set in accordance with the accelerator opening (AC).

The ECU 9 also determines the engine operating state determined by the engine speed and the engine load (accelerator opening) during vehicle running and the basic injection amount calculation map (injection amount control) during vehicle running shown in FIG. Characteristics) and from
Calculates the optimal fuel injection amount (basic injection amount: corresponding to the valve opening period of the injectors 1 to 6) Q and corrects the basic injection amount Q based on operating conditions such as cooling water temperature, intake pressure, intake temperature or fuel temperature. Then, the target injection amount QF is calculated. further,
The ECU 9 calculates or determines the optimal injection timing (corresponding to the valve opening timing of the injectors 1 to 6) from the engine operating state determined by the engine rotation speed and the engine load (accelerator opening).

The ECU 9 of this embodiment is configured to include the function of the first injection amount correcting means of the present invention. As shown in FIG. 3, the first injection amount correction means detects rotation speed fluctuations of each cylinder # 1 to # 6 for each explosion stroke,
In order to smooth the rotation speed fluctuation between the cylinders # 1 to # 6, the basic injection amount Q for each of the cylinders # 1 to # 6 is added to the basic injection amount Q in the direction in which the rotation speed fluctuation between the cylinders is smoothed. Function to add one injection amount correction amount (unequal amount compensation control, FCCB learning control:
Fuel Control for Cylinder
Balancing).

The ECU 9 includes a function of the second injection amount correcting means of the present invention. As shown in FIG. 4, the second injection amount correction means stores, in a memory (ROM), specific cylinders # 1 and # 2 which generate mechanical engine-specific vibrations for each cylinder in advance in a memory (ROM). The injection amount weight (second injection amount correction amount) is added to the basic injection amount and the first injection amount correction amount for the specific cylinders # 1 and # 2 so as to reduce the engine specific vibration in the specific cylinders # 1 and # 2. Is a function to add.

[Method of Calculating Injection Amount of Embodiment] Next, a method of controlling the accumulator type fuel injection device of the embodiment will be briefly described with reference to FIGS. Here, FIG. 5 is a flowchart showing a method of calculating the fuel injection amount by the ECU 9.

When the ignition switch is turned on (IG / O
N), the routine of FIG. 5 is started. First, input data is read from various sensors or various operation switches. Specifically, the engine speed NE, the engine load (accelerator opening) AC, the coolant temperature THW, and the fuel temperature T
The HO, the vehicle speed SPD, the common rail pressure PC, the lever position of the select lever, and the like are read (step S1).

Next, it is determined whether a control condition for executing the FCCB learning control is satisfied (step S2).
Specifically, the engine speed NE is set to a predetermined value (for example, 1
000 rpm) or less, engine load (accelerator opening) A
By determining whether C is equal to or less than a predetermined value (for example, 0%) and the vehicle speed SPD is equal to or less than a predetermined value (for example, 0 km / h), it is determined whether or not the control condition is satisfied. That is, it is determined whether or not the vehicle is in an idling state (no-load state) where the engine rotation speed of the diesel engine 10 is low, in which noise caused by the vibration of the diesel engine 10 is conspicuous and the driver feels more discomfort.

If the result of the determination in step S2 is NO, the FCCB learning control prohibition flag is turned OFF (0) (step S3). Next, the engine speed (NE) and the accelerator opening (AC = AC) read in step S1 are read.
0% to 100%) and the injection amount control characteristics during vehicle running stored in advance in the ROM (see the basic injection amount calculation map during vehicle running in FIG. 2). The basic injection amount Q to be injected indoors is calculated (basic injection amount determining means: step S4).

Next, the basic injection amount Q obtained in step S4 is corrected based on the operating conditions such as the coolant temperature (THW), common rail pressure (PC), and fuel temperature (THO) read in step S1. I do. That is, a fuel injection amount (target injection amount) QF uniform for all cylinders is obtained from the basic injection amount Q and the operating conditions (fuel injection amount determining means: step S5).

Next, the valve opening periods of the injectors 1 to 6 are calculated so that the fuel injection amount QF obtained in step S5 is obtained, and the injection timing, that is, the injectors 1 to 6
Is calculated. Then, control signals are output to the injection amount control solenoid valves 11 to 16 so that the calculated valve opening periods and valve opening times of the injectors 1 to 6 are obtained (injection amount control means: step S6). Thereafter, the process exits the routine of FIG.

On the other hand, if the decision result in the step S2 is YES, it is determined that the control condition for executing the FCCB learning control is satisfied, and the FCCB learning control prohibition flag is set to OFF.
It is determined whether or not F (0) (step S7). If the result of this determination is NO, the control processing of step S1 and subsequent steps is repeated.

If the result of the determination in step S7 is YES, the engine speed (NE = 1000 rpm)
And the accelerator opening (AC = 0%) and the injection amount control characteristic during idle operation stored in advance in the ROM, the basic injection amount during idle operation to inject into the combustion chamber of each cylinder of the diesel engine 10. Q is calculated (basic injection amount determining means: step S8). Next, FCCB learning control is performed (step S9).

Specifically, before the top dead center of a certain cylinder (BTD
When there is an interruption of C15 ° CA), the instantaneous rotation speed of a certain cylinder is calculated by calculating the interval time (30 ° CA time: μs) between the crank angle signals (BTDC 15 ° CA to ATDC 15 ° CA). The instantaneous rotation speed is read as the minimum rotation speed Min of this cylinder.

After the top dead center of the cylinder (ATDC4
5 ° CA), the crank angle signal (A
The instantaneous rotational speed of a certain cylinder is calculated by calculating the interval time (30 ° CA time: μs) between 45 ° CA of TDC and 75 ° CA of ATDC, and this instantaneous rotational speed is read as the maximum rotational speed Max of this cylinder.

After these calculations are performed for each cylinder, the maximum rotation speed Max and the minimum rotation speed M for each cylinder are calculated.
By calculating the rotation speed difference from the rotation speed in, a single value of the rotation speed fluctuation for each of the explosion strokes of each cylinder is calculated. Here, FIG.
Solid line indicates the behavior of the rotation speed fluctuation of each cylinder of the diesel engine 10 in which there is no variation in the rotation speed fluctuation of all the cylinders # 1 to # 6, and the broken line in FIG.
The behavior of the rotational speed fluctuation of each cylinder of the diesel engine 10 in which the rotational speed fluctuation varies from one cylinder to another is shown.

Next, the rotational speed fluctuations of all cylinders are averaged to calculate the average value of the rotational speed fluctuations of all cylinders. next,
A single value of the rotation speed fluctuation of each cylinder # 1 to # 6 of the diesel engine 10 for each explosion stroke is compared with an average value of the rotation speed fluctuations of all the cylinders. The amount of fuel injected into each of the cylinders # 1 to # 6 is compensated for in the direction of smoothing.

Here, the injection amount correction amount for each cylinder, which is added to the basic injection amount Q at the time of idling operation obtained in step S8, is shown in FIG. 6 based on the rotational speed fluctuation shown by the broken line in FIG. The first injection amount correction amount. Therefore, as shown in the following equation (1), from the basic injection amount Q during idling operation and the first injection amount correction amount (see FIG. 6) ΔQ1n,
Fuel injection amount (target injection amount) for each cylinder injected into each cylinder
QFn is calculated.

(Equation 1)

Next, it is determined whether the FCCB learning control for all cylinders has been completed (step S10). If this determination is NO, the FCCB learning control of step S9 is continued. Also, if the determination result of step S10 is Y
In the case of ES, natural vibration suppression control for correcting the basic injection amount during idling operation and calculating the fuel injection amount (target injection amount) QF for each cylinder to be injected into each cylinder is performed (step S11).

In the natural vibration suppression control, a specific cylinder serving as a vibration source that generates mechanical natural vibration (engine natural vibration) for each cylinder of the diesel engine 10 that differs for each engine type is obtained in advance by experiments. In the V-type six-cylinder diesel engine 10 of the present embodiment, as shown in FIG. 4, the cylinder # 1 is compared with the mechanical natural vibration of each of the cylinders # 5, # 3, # 6, and # 4. The mechanical natural vibration of the cylinder # 2 is large, and the mechanical natural vibration of the cylinder # 2 is small.

Therefore, in this embodiment, the cylinders # 1 and # 2 are stored in the memory (ROM) in advance as the specific cylinders serving as vibration sources. The injection amount weight (second injection amount correction amount: ΔQ2n) to be added to the basic injection amount Q and the first injection amount correction amount ΔQ1n is determined in advance by an experiment or the like to obtain a value capable of reducing the engine natural vibration. The value is stored in a memory (ROM) in advance.

The injection amount correction amount for each cylinder determined by the FCCB learning control in step S9 is further added to the injection amount weight (see FIG. 7) for the specific cylinder serving as the vibration source, as indicated by the hatched portion in FIG. As shown in FIG. 8, specific cylinders # 1, #
2), which is a value that can suppress the natural vibration.

Therefore, as shown in the following equation (2), each of the injections into each cylinder is determined from the basic injection amount Q during idling, the first injection amount correction amount ΔQ1n, and the second injection amount correction amount ΔQ2n. The fuel injection amount (target injection amount) QFn for each cylinder is calculated.

(Equation 2)

More specifically, the specific cylinder # 1 has an average rotation speed fluctuation and an engine-specific vibration larger than the other cylinders, so that the first injection amount correction amount ΔQ is larger than the basic injection amount Q.
The fuel injection amount to the specific cylinder # 1 is reduced by 1n, and the fuel injection amount to the specific cylinder # 1 is further reduced by an arbitrarily determined second injection amount correction amount ΔQ2n.

Further, since the specific cylinder # 2 has a smaller rotation speed fluctuation than the other cylinders and a smaller engine natural vibration than the other cylinders, the specific injection cylinder # 2 has a first injection amount correction amount ΔQ1n smaller than the basic injection amount Q. Only the fuel injection amount to the specific cylinder # 2 is increased, and the arbitrarily determined second injection amount correction amount ΔQ2n
The fuel injection amount to the specific cylinder # 2 is increased by the amount.

Here, in the implementation of the addition of the injection amount weight, various operating conditions of the diesel engine 10 (eg, engine type, vehicle body structure, engine mounting method, etc.) can be entered. It is also possible to select whether or not to use the natural vibration suppression control.

Next, the FCCB learning control prohibition flag is turned on.
(1) Perform (Step S12). Next, the fuel injection amount QFn for each cylinder obtained in steps S9 and S11 described above.
Thus, the valve opening periods of the injectors 1 to 6 attached corresponding to the respective cylinders are calculated, and the injection start timing, that is, the valve opening timing of the injectors 1 to 6 is calculated.
Then, the injection amount control solenoid valves 11 to 1 are set so that the calculated valve opening periods and valve opening times of the injectors 1 to 6 are obtained.
6 (injection amount control means: step S
13). Thereafter, the process exits the routine of FIG.

[Effects of the Embodiment] As described above, in the electronically controlled accumulator type fuel injection system for a diesel engine according to the present embodiment, when the diesel engine 10 is in a no-load state, that is, in an idling state where the rotation speed is low.
By performing the FCCB learning control described above, the vibration of the entire diesel engine 10 can be reduced.

After the FCCB learning control is performed, the natural vibration suppression control described above is performed to reduce the mechanical natural vibration (engine natural vibration) of each cylinder of the diesel engine 10. Therefore, in the no-load state of the diesel engine 10, that is, in the idling state where the rotation speed is low, engine vibration,
Since the noise can be reduced, no discomfort is given to the driver.

Further, every time the no-load state of the diesel engine 10, that is, the idling state with a low rotation speed is detected, the above-mentioned natural vibration suppression control is performed, and then the above-mentioned FCCB learning control is prohibited to thereby specify the specific state. After suppressing the vibration unique to the cylinder, the unequal amount compensation control for increasing the mechanical vibration inherent to the engine for each cylinder can be prohibited again.

Therefore, during the no-load state of the diesel engine 10, the control output to the injectors 1 and 2 attached to the specific cylinders # 1 and # 2 can be prevented from excessively fluctuating. . Note that the injection amount weight ΔQ2n of the specific cylinders # 1 and # 2 during the natural vibration suppression control.
For any cylinder, any injection amount weight (second
By adding the injection amount correction amount), the present invention can be applied to a multi-cylinder engine of various engine types described later, and can exhibit a natural vibration suppressing effect.

[Modification] In this embodiment, the present invention is applied to an electronically controlled accumulator type fuel injection system for a diesel engine having a common rail 8 for accumulating high pressure fuel pressurized by a fuel injection pump (high pressure supply pump) 7. The present invention is applied to an electronically controlled fuel injection system for a diesel engine which does not have a common rail and has a combination of a distribution type fuel injection pump or a row type fuel injection pump and an injector (fuel injection nozzle). May be.

The crank angle sensor 41, the accelerator opening sensor 42, the cooling water temperature sensor 43, and the like constitute operating state detecting means for detecting the operating state of the diesel engine 10. The operating state detecting means may be configured to include an injection timing sensor, an intake pressure sensor, and an intake air temperature sensor.

In this embodiment, an example has been described in which a V-type six-cylinder direct injection diesel engine is employed as the type of the multi-cylinder engine.
A diesel engine of a cylinder, a V-type 8-cylinder, or a V-type 12-cylinder may be employed, or an in-line six-cylinder diesel engine or an in-line four-cylinder diesel engine may be employed.

Other types of multi-cylinder engines include a horizontal type, a horizontally opposed type, a U-type, a VZ type multi-cylinder diesel engine, an in-line type, a horizontal type, a horizontally opposed type, and the like.
V-type, U-type, and VZ-type multi-cylinder gasoline engines may be employed. Further, a multi-cylinder internal combustion engine such as an eddy-flow diesel engine or a sub-chamber diesel engine may be employed as the multi-cylinder engine.

In this embodiment, one or more specific cylinders, which are sources of mechanical vibration (engine-specific vibration) of each cylinder of a multi-cylinder engine, are determined in advance by experiments and the like.
After the CB learning control is completed, natural vibration suppression control for adding the injection amount weight ΔQ2n to the first injection amount correction amount ΔQ1n so as to remove the predetermined engine specific vibration component of the specific cylinder is performed.

However, after the FCCB learning control is completed, an acceleration sensor, a strain sensor, or a pressure sensor is attached to each cylinder of the multi-cylinder engine to detect the mechanical vibration (engine natural vibration) of each cylinder. Alternatively, one or more specific cylinders serving as vibration sources may be determined, and feedback control may be performed so as to add an injection amount weight so as to remove a mechanical natural vibration component of each cylinder.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an overall configuration of an electronically controlled pressure accumulation type fuel injection system (embodiment).

FIG. 2 is a diagram showing a basic injection amount calculation map (embodiment).

FIG. 3 is a diagram showing a behavior of a rotational speed fluctuation of each cylinder for each explosion stroke (example).

FIG. 4 is a diagram showing the behavior of mechanical vibration inherent to the engine of each cylinder (Example).

FIG. 5 is a flowchart illustrating a method of calculating a fuel injection amount by an ECU (embodiment);

FIG. 6 is a diagram showing an injection amount correction amount to each cylinder during FCCB learning control (Example).

FIG. 7 is a diagram showing an injection amount correction amount to each cylinder during natural vibration suppression control (Example).

FIG. 8 is a diagram showing the behavior of mechanical engine-specific vibrations possessed for each cylinder (embodiment).

[Explanation of symbols]

Reference Signs List 1 injector (fuel injection valve) 2 injector (fuel injection valve) 3 injector (fuel injection valve) 4 injector (fuel injection valve) 5 injector (fuel injection valve) 6 injector (fuel injection valve) 7 high-pressure supply pump 8 common rail 9 ECU (Injection amount control device, first and second injection amount correction means, rotation speed fluctuation detection means, specific cylinder estimation means, no-load state detection means) 10 diesel engine (multi-cylinder engine) 41 crank angle sensor (rotation speed detection means) , Rotation speed fluctuation detecting means, no-load state detecting means) 42 accelerator opening sensor (no-load state detecting means) 43 cooling water temperature sensor 45 vehicle speed sensor (no-load state detecting means, running state detecting means) # 1 cylinder # 2 Cylinder # 3 Cylinder # 4 Cylinder # 5 Cylinder # 6 Cylinder

Continuation of the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) F02D 45/00 314 F02D 45/00 314C 340 340D 362 362H 362J 362E 364 364G F term (reference) 3G084 AA01 BA13 CA03 DA39 EB08 EB08EB20 EB25 FA00 FA05 FA10 FA20 FA33 FA34 FA38 FA39 3G301 HA02 HA08 JA05 JA17 JA37 KA07 LB11 LC01 MA11 NA01 NA06 NA08 NC01 ND37 NE01 NE06 PA07Z PA10Z PB01Z PB03A PB03Z PB08Z PE01Z PE02Z PE03Z PE08Z PF01ZPFZZ PF01Z

Claims (4)

[Claims] 1. A fuel injection valve for injecting fuel into each cylinder of a multi-cylinder engine, and an injection for individually controlling the fuel injection valves so that the calculated fuel injection amount to each cylinder is obtained. A fuel injection device for a multi-cylinder engine, the fuel injection device comprising: (a) a rotation speed detection means for detecting a rotation speed of the multi-cylinder engine; and (b) a rotation speed detection means. Rotation speed fluctuation detecting means for detecting a rotation speed fluctuation of each cylinder of the multi-cylinder engine for each explosion stroke in accordance with the rotation speed of the multi-cylinder engine detected by (c). Specific cylinder estimating means for estimating a specific cylinder serving as a vibration source that generates mechanical natural vibrations, and (d) smoothing rotation speed fluctuations of each cylinder detected by the rotation speed fluctuation detection means for each explosion stroke. A first injection amount correcting means for individually correcting the fuel injection amount to each cylinder of the multi-cylinder engine; and (e) reducing the natural vibration of the specific cylinder estimated by the specific cylinder estimating means. Thus, the fuel injection device for a multi-cylinder engine is provided with the second injection amount correction means for correcting the fuel injection amount to the specific cylinder. 2. The fuel injection device for a multi-cylinder engine according to claim 1, further comprising: a no-load state detecting means for detecting or estimating a no-load state of the multi-cylinder engine; Each time the no-load state of the cylinder engine is detected or estimated, at least one of the first injection amount correction unit and the second injection amount correction unit is executed at least once. Fuel injection device for multi-cylinder engine. 3. The fuel injection system for a multi-cylinder engine according to claim 2, wherein each time the no-load state detecting means detects or estimates a no-load state of the multi-cylinder engine, the second injection amount correcting means. After the step (a) is performed, the first injection amount correcting means is prohibited. 4. A fuel injection system for a multi-cylinder engine according to claim 1, wherein said first injection amount correcting means calculates an average value of fluctuations in rotation speed of all cylinders and a value for each cylinder. A fuel injection device for a multi-cylinder engine, characterized in that the fuel injection device is a non-uniform amount compensation control means for comparing the detected value of the rotational speed fluctuation of the engine and the amount of fuel injection into each cylinder based on the comparison result.