JP2002188502A - Abnormality diagnostic device for fuel injection controlling device for diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an abnormality diagnostic device for fuel injection controlling devices for diesel engines, which can detect the time lag from the proper injection time for after-injection. SOLUTION: This abnormality diagnostic device for fuel injection controlling devices for diesel engines is provided with a fuel injection valve 5 for injecting fuel directly in the fuel chamber 4 of a diesel engine, a main injection control means 36 for controlling the main injection, that is, fuel injection from the fuel injection valve in a specified time from a position in suction stroke to a position near the top dead center for compression stroke, an after-injection means 36 for injecting fuel additionally in the injection time set based on the time when the combustion caused by the main injection has finished, a detection means 36 for detecting the combustion state in the combustion chamber 4, and a diagnostic means 36 for diagnosing the injection state of the alter-injection means based on the detection result of the detection means 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality diagnosis device for a fuel injection control device for a diesel engine, and more particularly, to a diesel engine for controlling post-injection in which additional fuel is injected after fuel injection by main injection. The present invention relates to an abnormality diagnosis device for a fuel injection control device.

[0002]

2. Description of the Related Art For the purpose of efficiently purifying NOx contained in exhaust gas of a diesel engine, additional fuel is burned at a predetermined timing following normal fuel injection (main injection) into a combustion chamber. 2. Description of the Related Art A fuel injection control device for a diesel engine that performs post-injection for indoor injection is known (Japanese Patent Application Laid-Open No. 2000-170585).

In the prior application (Japanese Patent Application No. 2000-321699) of the present applicant, which does not correspond to the prior art, the injection timing of post-injection is set based on the end point of diffusion combustion by main injection. There is a statement that soot emission can be effectively reduced.

In such a post-injection, the injection valve does not operate at a desired timing due to aging or the like, and the timing at which fuel is actually injected from the post-injection valve deviates from a set timing, or the aging of the engine itself occurs. An injection timing shift (abnormality) such as a shift of the injection timing of the post-injection set from an appropriate position due to deterioration occurs, and a desired effect such as soot reduction may not be obtained. When such a situation occurs, it is necessary to detect it immediately.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of such a point, and when the injection timing of the post-injection is shifted from an appropriate timing, this can be detected. An object of the present invention is to provide an abnormality diagnosis device for a fuel injection control device of a diesel engine.

[0006]

According to the present invention, there is provided a fuel injection valve for directly injecting fuel into a combustion chamber of a diesel engine. Main injection control means for controlling main injection in which fuel is injected from the fuel injection valve at a predetermined timing, and post-injection for injecting additional fuel at an injection timing set based on a timing at which combustion by the main injection is completed And a diagnostic means for diagnosing an injection state of the post-injection means based on a detection result of the detection means. An abnormality diagnosis device for a fuel injection control device for a diesel engine is provided.

According to such a configuration, since the injection state of the post-injection is diagnosed based on the actual combustion state detected by the detecting means, the injection state of the post-injection can be accurately diagnosed in accordance with the actual situation.

According to a preferred aspect of the present invention, the detecting means detects a degree of heat generation in the combustion chamber, and the diagnosing means performs the diagnosis based on the degree of heat generation during combustion by the post-injection. I do.

According to such a configuration, since the combustion state is detected based on the degree of heat generation in the combustion chamber which is directly related to combustion, it is possible to accurately diagnose the injection state of the post-injection.

According to another preferred aspect of the present invention, the diagnosis means makes the diagnosis based on heat generation by post-injection executed when heat generation of combustion by the main injection is equal to or less than a predetermined value.

According to such a configuration, since the heat generation by the post-injection is detected in a state where the heat generation by the main injection is low, it is possible to accurately diagnose the injection state of the post-injection.

According to another preferred aspect of the present invention, the detecting means detects the combustion state based at least on the output torque after the execution of the post-injection.

According to such a configuration, the output torque is
Since it can be detected or estimated relatively easily, the injection state of the post-injection can be accurately diagnosed with an inexpensive configuration.

According to another preferred aspect of the present invention, the main injection control means and the post-injection means can change an interval between the main injection and the post-injection, and the diagnostic means changes the interval. Then, when the fluctuation of the output torque is equal to or more than a predetermined value, it is diagnosed that the post-injection means is normal.

According to such a configuration, since the output torque of the post-injection fluctuates depending on the interval from the main injection, the interval of the post-injection is changed to intentionally change the interval with the main injection. By detecting whether the output torque fluctuates, it is possible to diagnose whether the injection timing of the post-injection has been changed as intended, that is, whether the post-injection means is normal.

According to another aspect of the present invention, the fuel injection control means performs feedback control so that the engine speed converges to a predetermined speed during idling, and the diagnostic means performs the high speed or high load operation. Steady operation area,
Alternatively, the diagnosis is performed during the feedback control.

In a high-speed or high-load steady-state operation region, the combustion state of the engine is easily detected, and during feedback control performed at the time of idling, the operation state of the engine is stable. It becomes possible.

[0018]

Next, preferred embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram illustrating a configuration of a fuel injection control device for a diesel engine according to an embodiment of the present invention.

As shown in FIG. 1, the fuel injection control device includes a diesel engine 1 mounted on a vehicle. The diesel engine 1 has four cylinders 2, 2,.
A piston 3 is disposed in a cylinder constituting each cylinder 2 so as to be able to reciprocate, and a combustion chamber 4 is formed by the piston 3 and the inner peripheral wall of the cylinder. Have been. At substantially the center of the upper surface of the combustion chamber 4, a fuel injection valve (injector) 5 is disposed such that the injection hole at the tip thereof faces the combustion chamber 4. The fuel injection valve 5 is configured to inject fuel directly into the cylinder, that is, into the combustion chamber 4 at a predetermined timing. Further, a water temperature sensor 18 for measuring the temperature of the cooling water (engine water temperature) is provided so as to face a water jacket of the engine 1 (not shown).

Each fuel injection valve 5 is connected to a common common rail (accumulation chamber) 6 for storing high-pressure fuel. High pressure fuel is supplied to the common rail 6 by an injection pump driven after the engine is started by the engine or the motor,
A pressure sensor 6a for detecting an internal fuel pressure (common rail pressure) is arranged, and a high-pressure supply pump 8 driven by a crankshaft 7 is connected. The high-pressure supply pump 8 reduces the fuel pressure in the common rail 6 detected by the pressure sensor 6a to, for example, about 20 MPa during idling operation.
a, and at other times, it is kept at 50 MPa or more.

The crankshaft 7 is provided with a crank angle sensor 9 for detecting the rotation angle. The crank angle sensor 9 includes a plate to be detected provided at the end of the crankshaft 7 and an electromagnetic pickup arranged so as to correspond to the outer periphery of the plate. It is configured to generate a pulse signal in response to the passage of the protrusions formed at predetermined angles.

The engine 1 has an intake passage 10 for introducing the intake air filtered by an air cleaner (not shown) into the combustion chamber 4. The downstream end of the intake passage 10 branches via a surge tank (not shown), and is connected to the combustion chamber 4 of each cylinder 2 via an intake port. Further, an intake pressure sensor 10a for detecting a supply pressure supplied to each cylinder 2 in the surge tank is provided.

The intake passage 10 has an air flow sensor 11 for detecting the flow rate of intake air taken into the engine 1 in order from the upstream side to the downstream side.
, Which cools the air compressed by the blower 12, and an intake throttle valve 14 which narrows the cross-sectional area of the intake passage 10
Are provided.

The intake throttle valve 14 is formed of a butterfly valve provided with a notch so that intake air can flow even in a fully closed state. Is adjusted by the negative pressure control solenoid valve 16 to control the opening degree of the valve. Further, a sensor (not shown) for detecting the opening degree of the intake throttle valve 14 is also provided.

An exhaust passage 20 for discharging exhaust gas from the combustion chamber 4 of each cylinder 2 is connected to the engine 1.
The upstream end of the exhaust passage 20 branches and is connected to the combustion chamber 4 of each cylinder 2 by an exhaust port (not shown). The exhaust passage 20 includes, in order from the upstream side to the downstream side, an O2 sensor (not shown) whose output changes suddenly when the air-fuel ratio of the exhaust gas is substantially the stoichiometric air-fuel ratio, and a turbine rotated by the exhaust flow. 21 and at least NO in the exhaust
A NOx reduction catalyst 22 that reduces and purifies x, and a NOx sensor 19 that detects the concentration of NOx in exhaust gas that has passed through the NOx reduction catalyst 22 are arranged. The NOx purification catalyst that is the NOx reduction catalyst 22 includes a cordierite carrier formed in a honeycomb structure having a large number of through holes extending parallel to each other along the flow direction of the exhaust gas, and a catalyst layer is formed on each of the through hole wall surfaces. It is formed in two layers. Specifically, the catalyst layer is formed by supporting platinum (Pt) and rhodium (Rh) as support materials such as MFI-type zeolite (ZSM5) which is a porous material.

The NOx purifying catalyst 22 reduces NOx even when the mixture in the combustion substance 4 is lean and the oxygen concentration in the exhaust gas is high, for example, when the oxygen concentration is 4% or more. It is configured to purify NOx in exhaust gas by reacting with the agent and reducing it. The NOx purification catalyst 22 functions as a three-way catalyst when the oxygen concentration is low.

The exhaust passage 20 is branched and connected to an upstream end of an exhaust gas recirculation passage (EGR passage) 23 for recirculating a part of exhaust gas to the intake side at a position upstream of the turbine 21.
The downstream end of the EGR passage 23 is connected to the intake passage 10 at a position downstream of the intake throttle valve 14. EG
At a position near the downstream side of the R passage 23, a negative-pressure operated exhaust gas recirculation amount adjusting valve (EGR valve) 24, whose opening degree can be adjusted, is provided. In this embodiment, a part of the exhaust gas in the exhaust passage 20 is configured to be recirculated to the exhaust passage 10 while the flow rate is adjusted by the EGR valve 24.
The EGR passage 23 constitutes an exhaust gas recirculation (EGR) means 33.

The EGR valve 24 has its valve body (not shown) urged in the closing direction by a spring, and is actuated in the opening direction by a diaphragm 24a to open the EGR passage 23.
Is linearly adjusted. That is, a negative pressure passage 27 is connected to the diaphragm 24a, and the negative pressure passage 27 is connected to a vacuum pump (negative pressure source) 29 via a negative pressure control electromagnetic valve 28. Is connected to or shuts off the negative pressure passage 27 by a control signal from the ECU 35 described later, whereby the negative pressure for driving the EGR valve is adjusted, and the EGR valve 24 is opened and closed. Further, a lift sensor 26 for detecting the position of the valve body of the EGR valve 24 is provided.

Each fuel injection valve 5, high-pressure supply pump 8, intake throttle valve 14, EGR valve 24, turbocharger 25 and the like are provided with a control unit (Engine Control Uni
t: ECU) 35 is configured to operate in response to a control signal.

On the other hand, the ECU 35 outputs an output signal of the pressure sensor 6a, an output signal of the crank angle sensor 9, an output signal of the air flow sensor 11, an output signal of the water temperature sensor 18,
An output signal of the lift sensor 26 of the GR valve 24, an output signal from an accelerator opening sensor 32 for detecting an operation amount (accelerator opening) of an accelerator pedal (not shown) by a driver of the vehicle, and the like are input. I have.

In this embodiment, the ECU 35 controls the operation of the engine, and controls the main injection in which fuel is injected from the fuel injection valve 5 at a predetermined time near the top dead center of the compression stroke. And the heat generation rate by the main injection is approximately 0
An injection control means 36 for performing post-injection control or the like for controlling the post-injection fuel injected from the fuel injection valve 5 to start combustion when the following conditions are satisfied (that is, when diffusion combustion by the main injection is completed): , An EGR control means 37 for controlling the EGR valve 24 to control the exhaust gas recirculation amount. That is,
In the present embodiment, the injection control means 36, the injection valve 5 and the like constitute a post-injection means, and the injection control means 36 also constitutes a detection means and a diagnosis means.

The ECU 35 is configured to detect the combustion state in the combustion chamber based on torque fluctuation, in-cylinder pressure, etc., and to correct the injection timing of the post-injection by the post-injection control means based on the detection result. . Further, the ECU 35 of the present embodiment is configured to perform feedback control (ISC control) that converges the engine speed to a predetermined speed during idling.

Next, fuel injection control including abnormality diagnosis control executed by the ECU 35 will be described with reference to the flowcharts of FIGS. 2A, 2B, and 2C.

First, in step S1 after the start, data such as a crank angle signal from the crank angle sensor 9, an accelerator opening from the accelerator opening sensor 32, and an intake air amount from the air flow sensor 11 are input. Next, in step S2, the target torque Tr calculated from the accelerator opening is set.
Read from the basic injection quantity map which is set based on the engine speed Ne obtained from the crank angle signal, the read basic fuel injection amount Q _b, a map previously set the injection timing I _b .

Next, in step S3, the idle region (I
D) is determined. In this embodiment, the engine
500 rpm to 1000 rpm, and
Although the xel opening of 0 is the idle region,
Therefore, an idle area may be determined. Y in step S3
If the ES is determined to be in the idle area,
At step S4, the current rotational speed Ne (k) is stored, and
In step S5, the average value Ne of the past k rotation speeds Ne_aveIs calculated
Then, in step S6, the average value Ne is calculated._aveFrom the current
Rotation speed Ne_RealIs subtracted to obtain the difference ΔNe. Next,
In step S7, the idling time from the map is determined based on ΔNe.
Fuel injection correction amount Q_IDCIs set, and in step S8, the basic
Fuel injection quantity Q_bThe fuel injection correction amount Q_IDCAdd the basic fuel
Injection quantity Q _bAnd the process proceeds to step S9. On the other hand,
If NO in step S3, that is, if it is determined that the vehicle is not idling,
Resets the rotation speed Ne (k) to 0 in step S10
Then, the process proceeds to step S9.

In step S9, the post-injection injection amount _Qfu and the injection timing _Ifu are set. The injection amount Q _fu and the injection timing I _fu of the post-injection are based on the target torque Tr and the engine speed N.
The amount corresponding to e is read from a preset map and set.

In this map, the post-injection injection amount Q _fu
The fuel injection (amount or rate) by the post-injection is larger than when the amount of soot is less than the predetermined amount in an operation state in which the soot generated by combustion by the main injection is equal to or more than a predetermined amount (high rotation and high load). So that the generation of soot is suppressed. Here, the fuel injection amount by the post-injection indicates the absolute amount of fuel injected by the post-injection, and the fuel injection rate by the post-injection indicates a ratio of the injection amount of the post-injection to the injection amount of the main injection.

In this embodiment, the ratio of the injection amount of the post-injection to the injection amount of the main injection is 10 to 2 at low rotation and low load.
0%, and is increased to 20 to 50% or more at high rotation and high load.

Further, as a modified example, the fuel injection amount Q by the post-injection is also increased in a region where the amount of soot is increased other than at the time of high rotation and high load, for example, at the time of A / F rich, at the time of pilot injection, and at the time of main injection retard. _fu may be increased compared to other operating conditions.

[0040] In addition, the state of occurrence of soot using a map that sets the injection amount Q _fu of after-injection independent, may set the injection amount Q _fu of soot injection. Further, a configuration may be adopted in which the post-injection is not performed at the time of low rotation and low load such as idling, and the post-injection is performed in a region other than at the time of low rotation and low load. Furthermore, a map may be used in which the post-injection amount is 0 during the steady operation, and a post-injection is executed only at a predetermined acceleration by adding a predetermined value to the post-injection amount being 0 as described later.

The injection timing _Ifu of the post-injection is such that the combustion of the fuel by the post-injection is started when the diffusion combustion by the main injection ends, that is, when the heat generation rate of the combustion by the main injection becomes substantially 0 or less. The ignition delay of the post-injection (0.4 to 0.7 m
s) and the ineffective injection time are set on the map.

With this setting, when the heat generation rate becomes substantially equal to or less than 0, that is, when the diffusion combustion of the main injection fuel in the combustion chamber ends, the combustion of the fuel by the post injection starts. Will be done. For this reason, in the state where the mixing of the soot and oxygen present in the combustion chamber 4 is promoted, the combustion by the post-injection starts, and it is considered that the generation of the soot is reduced.

Further, around the time when the heat generation rate by the main injection becomes substantially 0 or less (in terms of crank angle, preferably ± 10
°, more preferably within ± 5 °), the post-injection injection timing may be set such that combustion by the post-injection starts.

The heat release rate dQ / dθ is calculated as follows:
According to (Fujio Nagao, Yokendo Co., Ltd.), it is expressed as the following equation (1).

DQ / dθ = A / (K (θ) −1) × [V (θ) · (dP (θ) / dθ) + K (θ) · P (θ) · (dV (θ) / dθ) ] (1) Here, A is the work equivalent of heat, K (θ) is the specific heat ratio, V
(Θ) is the stroke volume, P (θ) is the cylinder pressure, and θ is the crank angle.

A combustion analyzer CB5 manufactured by Ono Sokki Co., Ltd.
According to the manual of No. 66, the specific heat ratio K (θ) is expressed based on the following equations (2) to (5).

K (θ) = Cp / Cv (2) Cp = ap + b (T (θ) / 100) + c (T (θ) / 100) 2 + d (100 / T (θ) ... (3) Cv = Cp− (A · Ro) / M (4) T (θ) = (P (θ) · V (θ)) / 29.27 · G (5) where Cp is constant pressure specific heat, and Cv is constant. Specific heat, Ro is a gas constant, M is the molecular weight of air, T (θ) is gas temperature, G is gas weight, and ap, b, c, and d are other constants.

From the above equations (2) to (5), the heat release rate dQ / dθ shown in equation (1) is a function f (P (θ) of the cylinder pressure P (θ) and the stroke volume V (θ). ), V (θ)). When the stroke volume V (θ) is represented based on the bore diameter B and the stroke S, the following equation (6) is obtained. Therefore, the heat release rate dQ / dθ is expressed by the following equation (7). As shown.

V (θ) = (π · B2S / 8) · (1−cos θ) (6) dQ / dθ = [f (P (θ + Δθ), V (θ + Δθ)) − f (P (θ), V (θ))] / Δθ (7) Accordingly, if there is in-cylinder pressure data for each crank angle, the above heat generation rate can be calculated based on the data.
In the present embodiment, from the heat release rate thus obtained,
The end point of the diffusion combustion is calculated (that is, the point at which the heat release rate becomes substantially equal to or less than 0). A map with time _Ifu is used.

The end time of the diffusion combustion varies according to the operating state of the engine, and the end timing of the diffusion combustion tends to be delayed as the engine load and the engine speed increase. For example, if the engine speed is 2000 rpm and the average effective pressure P
At the time of middle rotation and middle load where e is 0.57 Mpa, as shown in FIG. 3B which is a graph of the result calculated by the above-described method, the fuel that has been mainly injected near the compression top dead center of the piston is discharged. The heat generation Y by diffusion combustion is substantially the same as the heat generation Y by premix combustion, and the ignition delay τ _f2 (about 0.5 ms) from about 35 ° (CA) after the compression top dead center.
Diffusion combustion ends at time t2, which is delayed only by the delay.

Further, when the engine speed is 2500 rpm,
At high rotation and high load where the average effective pressure Pe is 0.9 MPa, as shown in FIG. 3C, heat generation K due to diffusion combustion occurs for a considerably longer time than heat generation Y due to premix combustion, resulting in compression. Time point t3, which is much later than ignition timing τ _f3 (about 0.7 ms) after about 48 ° (CA) after top dead center
It can be seen that diffusion combustion ends.

When the engine speed is 1500 rpm,
At low rotation speed and low load where the average effective pressure Pe is 0.3 Mpa, as shown in FIG. 3A, it is difficult to distinguish premixed combustion and diffusion combustion of heat by heat generation. Ignition delay τ _f1 from about 30 ° (CA) after dead center
It can be seen that diffusion combustion ends at a relatively early point in time t1 (about 0.6 ms).

Therefore, in the vicinity of the end of the diffusion combustion, that is, 25 to 35 ° (CA) after the compression top dead center at low rotation and low load, and 33 to 40 after compression top dead center at medium rotation and middle load. In (° C), it is preferable to set the post-injection timing so as to execute post-injection at 45 to 48 ° (CA) after the compression top dead center at the time of high rotation and high load.

In the present embodiment, as shown by the needle lift amount in FIG.
° (CA) at medium load during rotation
° (CA), at high rotation and high load, 48
° (CA), the post-injection timing is set so that the post-injection is performed, and the diffusion combustion ends in each operating state.
Starting combustion by post-injection at 1, t2, and t3,
It is set on the map so that the heat generation indicated by the dotted line in FIG. 3 occurs. In other operating states, the injection timing of the post-injection is set on the map so that the combustion by the post-injection starts when the diffusion combustion ends.

In step S11, it is determined whether the failure diagnosis has been completed. In the present embodiment, one failure diagnosis is performed for one operation (drive). Therefore, in step S11, NO, that is, it is determined that the failure diagnosis has not been performed since the engine was started this time. If so, the process proceeds to step S12 to enter control for performing a failure diagnosis. Note that the engine of the present embodiment is a four-cylinder engine, and fuel injection is performed for each cylinder. Therefore, failure diagnosis of the post-injection means is also performed sequentially for each of the four cylinders. Accordingly, the completion of the failure diagnosis indicates that the failure diagnosis has been completed for all four cylinders.

In step S12, a high rotation range (for example, 2
It is determined whether or not the engine speed is higher than 500 rpm (NO in step S13).

In step S12 or S13, Y
ES, that is, when it is determined that the engine is in the high rotation range or the high load range, the process proceeds to step S14, and the accelerator sensor 3
2, the rate of change Δα of the accelerator opening α
Is smaller than a predetermined value Δα ₀ , that is, whether the vehicle is in a predetermined steady operation state.

In step S13 or S14,
If NO, that is, if it is determined that the vehicle is not in the high load region or that the vehicle is not in the predetermined steady operation state, it is determined in step S15 whether the vehicle is in an idle region (ID). In the present embodiment, the engine speed is from 500 rpm to 1000 rpm.
Although m and the accelerator opening 0 are defined as the idle region, the idle region may be determined based on other criteria.

[0059] When it is determined not to be NO That idle region in step S15, the process proceeds to step S16, the counter u and described below _{Tθ n, Tθ n-1,} ΔTθ 0 is reset.

If YES in step S11, that is, if the failure diagnosis has already been performed, and if reset has been performed in step S16, the process proceeds to step S17, where the amount Q set in step S2, S8, or S9 is set. _The fuel injection valve 5 is operated in accordance with _b , _Qfu and the timings _Ib , _Ifu , and the main injection into the combustion chamber 4 and the post-injection are performed.

In step S14 or step S15,
If YES, that is, if it is determined that the vehicle is in the predetermined steady-state operation state or in the idle region, 1 is added to the counter u in step S18 as shown in FIG.
Proceeding to step S19, it is determined whether u = 1 to 4. u = 1 to 4 means the first injection after control start for each of the four cylinders, that is, the first cycle injection after control start. Since there is a possibility that a stable diagnosis result cannot be obtained in the first cycle, the diagnosis is not performed when u = 1 to 4.

NO in step S19, that is, 2
If the injection is after the cycle, in step S20,
It is determined whether or not u = 5 to 8, that is, whether or not it is the second cycle after the start of the control. If YES in step S20, that is, if it is the second cycle after the start of control, step S21
Then, it is determined whether or not the current injection is an injection to the first cylinder, the third cylinder, or the fourth cylinder. In the present embodiment, injection and combustion of the four cylinders are performed in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.

YES in step S21, that is, the current injection
The injection is injection into the first, third or fourth cylinder
Sometimes, in step S22, the fourth cylinder is set to K_n-1And
If NO in step S21, that is, if the current injection is the first cylinder,
It is not injection to the third cylinder or the fourth cylinder (that is,
(Injection to two cylinders), the process proceeds to step S23.
The injection timing I of the post-injection set in step S9_fuPlace
Fixed value I_fuDAnd I_{f uD}Only the injection timing is shifted to the retard side
Then, in step S24, the second cylinder is set to K _nage
And go to the next.

NO in step S20, that is, 3
If the injection is after the cycle, in step S25,
It is determined whether or not u = 9 to 12, that is, whether or not it is the third cycle after the start of the control. If YES in step S25, that is, if it is the third cycle after the start of control, step S26
Then, it is determined whether or not the current injection is injection to the third cylinder, the fourth cylinder, or the second cylinder.

If YES in step S26, that is, if the current injection is injection to the third, fourth or second cylinder, the second cylinder is set to Kn _{-1 in} step S27.
If NO in step S26, that is, if the current injection is the third cylinder,
Not injected into the fourth cylinder and the second cylinder (i.e., the injection into a first cylinder) Sometimes, the process proceeds to step S28, by adding a predetermined value I _FUD to the injection timing I _fu injection after setting at step S9, I _{f uD} only to shift the injection timing retarded, at step S29, the first cylinder as K _n, proceeding.

NO in step S25, that is, 4
If it is the injection after the cycle, in step S30,
It is determined whether or not u = 13 to 16, that is, whether or not u is the fourth cycle after the start of the control. If YES in step S30, that is, if it is the fourth cycle after the start of control, step S3
At 1, it is determined whether or not the current injection is an injection to the fourth cylinder, the second cylinder, or the first cylinder.

If YES in step S31, that is, if the current injection is injection to the fourth cylinder, the second cylinder, or the first cylinder, the first cylinder is set to Kn _{-1 in} step S32.
If NO in step S31, that is, if the current injection is the fourth cylinder,
When the injection is not to the second cylinder or the first cylinder (that is, the injection is to the third cylinder), the process proceeds to step S33, and a predetermined value I _fuD is added to the injection timing I _fu of the post-injection set in step S9. I _{f uD} only to shift the injection timing retarded, at step S34, the third cylinder as K _n, proceeding.

NO in step S30, that is, 5 after control starts.
If the injection is after the cycle, in step S35,
It is determined whether the current injection is injection to the second cylinder, the first cylinder, or the third cylinder. Here, after the sixth cycle, since the diagnosis for all the cylinders has been completed, the result is NO in step S11, and the process does not proceed to the diagnosis control step. Therefore, if NO in step S30, that is, if the injection is in the fifth and subsequent cycles after the start of control, the injection is in the fifth cycle.

If YES in step S35, that is, if the current injection is injection to the second cylinder, the first cylinder, or the third cylinder, the third cylinder is set to Kn _{-1 in} step S36.
If NO in step S35, that is, if the current injection is the second cylinder,
Not injected into the first cylinder or the third cylinder (i.e., the fourth is an injection into the cylinder) Sometimes, the process proceeds to step S37, by adding a predetermined value I _FUD to the injection timing I _fu injection after setting at step S9, I _{f uD} only to shift the injection timing retarded, at step S38, the fourth cylinder as K _n, proceeding.

As described above, steps S20 to S
The processing up to 38, in the first second period, the fourth second cylinder is the K _n, the injection and combustion takes place before the second cylinder
The cylinder is set to Kn _-1 (from step S20 to step S2).
4), in the first third cycle, the first cylinder is the K _n, second cylinder injection and combustion before the first cylinder is performed is the K _n-1 (step S29 from step S25), and the the fourth period, the third cylinder is the K _n, first cylinder injection and combustion is performed before the third cylinder is set to the K _n-1 (step S34 from step S30), further, the fifth cycle in the eyes, the fourth cylinder is set to the K _n, third cylinder injection and combustion is performed before the fourth cylinder is the K _n-1 (step S38 from step S35). As a result, during the second to fifth cycles,
All of the first to fourth cylinder is the K _n once, the injection timing of the post injection for K _n, it can be seen that migrated retarded only I _FUD.

If NO in step S19, that is, if it is the first cycle, and steps S22, S24, S27, S2
9, after the processing of S32, S34, S36 and S38, the process proceeds to step S39 (FIG. 2C),
2, S8 or amount Q _b is set at S9, Q _fu and timing I _b, in accordance with I _fu,, the fuel injection valve 5 is actuated, the main injection, and post injection is executed to the combustion chamber 4 .

Then, the process proceeds to a step S40, wherein a required time Tθ ′ for a predetermined crank period is read. As the predetermined crank period, for example, 10 ° to 60 ° crank angle (CA) is set from immediately after the main injection to 60 ° crank angle (CA), and the required time of this predetermined crank angle is determined by the expansion stroke of each cylinder. Each time it is detected and read by an IC timer or the like. The longer the required time Tθ ′, the larger the torque decrease. Therefore, it is possible to detect (estimate) the torque generated by the main injection and the post-injection based on the detected required time Tθ ′. Become.

Further, the routine proceeds to step S41, where it is determined whether or not the injection / combustion has been performed on the _Kn-1 cylinder. If YES in step S41, that is, if it is a Kn _-1 cylinder, the process proceeds to step S42, and the current Tθ ′ is set to (n−
1) Store as the required time Tθ _(n-1) of the cylinder and return. On the other hand, if NO in step S41, that is, if it is not the _Kn-1 cylinder, the process proceeds to step S42 to perform the current injection
It is determined whether or not combustion has been performed on the _Kn cylinder. When is YES i.e. K _n cylinder at step S42, the process proceeds to step S43, Tθ _(n-1) determines whether the memory already.

NO in step S42, that is, K_nIn the cylinder
And NO in step S43, that is, Tθ
_(n-1)Is not already stored in memory,_nCylinder requirements
Time Tθ _nAnd K_(n-1)Required time Tθ of cylinder_(n-1)Compare with
Return because it can not.

[0075] When YES, that Tθ _(n-1) is already memory step S43, the process proceeds to step S44, and the memory the current T.theta 'as required time T.theta _n of K _n cylinders,
Proceeding to step S45, the required time Tθ _{( n-1) in} the K _n-1 cylinder where the previous injection / combustion was performed, and the required time Tθ in the K _n cylinder where the current injection / combustion was performed Take the difference from _n
Let ΔTθ.

Further, the process proceeds to step S46, where a threshold value ΔTθ ₀ of the required time according to the operating state is set. In the present embodiment, noting that there is a predetermined relationship between the injection timing of the post-injection and the output torque of the engine, this threshold ΔT
The abnormality of the post-injection means is diagnosed based on θ ₀ .

First, the relationship between the post-injection injection timing and the engine output torque will be described.

FIG. 4 shows the state at high load and high rotation (2500 rpm).
m, 0.9 Mpa) is a graph showing the relationship between the fuel efficiency and the post-injection injection timing. This graph shows that the accelerator opening is selected such that the sum of the torque due to the combustion of the main injection and the torque due to the combustion of the post-injection becomes a certain target torque, and the injection timing of the post-injection is changed to the injection timing of the main injection. The vertical axis indicates the fuel efficiency when the vehicle is moved from the angle to the retard side. From this graph, it can be seen that when the injection timing of the post-injection is more retarded than about 48 ° (crank angle) after the main injection, which is the set timing of the post-injection at the time of high load and high rotation, the fuel efficiency is rapidly deteriorated. Understand. This means that when the injection timing of the post-injection is retarded from about 48 ° (crank angle) after the main injection, the accelerator opening must be increased in order to produce the target torque. . Accordingly, when the injection timing of the post-injection is retarded from about 48 ° (crank angle) after the main injection and the accelerator opening is maintained, the output torque decreases.

Here, it is considered that the torque due to the combustion of the main injection is not affected by the injection timing of the post-injection.
The drop in the output torque is a drop in the torque due to the combustion of the post-injection.
It is considered that the output torque of the engine decreases due to the combustion of the post-injection when the angle is more retarded than ° (crank angle). Note that this phenomenon occurs to some extent even when the load is not high rotation and high load.

Therefore, the injection timing of the post-injection is set to a predetermined timing, for example, 4 hours after the main injection, which is the set timing of high rotation and high load.
If the engine is shifted from 8 ° to the retard side, the output torque of the engine during (after) combustion by post-injection should be lower than that in the case where the engine is not shifted to the retard side. For this reason, control is performed to intentionally shift the injection timing of the post-injection to the specific cylinder to the retard side, and the output torque of the engine during (after) combustion by the post-injection is detected. If the degree has decreased, the post-injection injection timing has shifted to the retard side as intended, and the post-injection means is normal. On the other hand, if the output torque does not decrease by a predetermined degree, the injection timing of the post-injection does not shift to the retard side as intended, and the post-injection means is abnormal.

In the present embodiment, the output torque (that is, the required time Tθ _n ) of a specific cylinder (the cylinder in which injection combustion has been performed _nth ) is detected by intentionally shifting the timing of the post-injection. The difference between the output torque and the output torque of the cylinder whose post-injection timing is not shifted (the cylinder in which the (n-1) th injection combustion has been performed) (that is, the required time Tθ _n-1 ) is obtained. Threshold (Δ
Larger than T.theta _0), the post-injection at this n-th cylinder are made at the right time, the injection means after the n-th cylinder is determined to be normal.

Here, this threshold value (ΔTθ ₀ ) is determined by the operating state of the engine at the time of diagnosis, steps S23, S28,
The retard angle set at S33 or S37 (I _fuD )
A value (for example, a larger value as the rotation speed and the target torque are larger) is set on the map, and an appropriate value is drawn from the map according to the driving state and the like.

Next, the process proceeds to step S47, where
Derutatishita calculated in 45, whether the threshold Derutatishita ₀ or greater than that set in step S46 is determined.

[0084] When YES, that Derutatishita is larger than the threshold Derutatishita ₀ in step S47, the I had a predetermined torque variation by the control to shift the post-injection retarded, transition to the retard side of the post injection is controlled (Instruction), it is determined that the post-injection means is functioning normally, and it is memorized in step S48 that it is normal, and step S50 is performed.
Proceed to. On the other hand, when the NO That Derutatishita is the threshold Derutatishita ₀ or less at step S47, the since there is no predetermined torque variation by the control to shift to the retard side of the post-injection, the transition to the retard side of the post injection is controlled (Instruction), it is determined that there is some abnormality in the post-injection means, and in step S49, it is memorized that there is an abnormality in post-injection, and a warning (warning) is displayed to the driver. Then, the process proceeds to step S50.

In step S50, it is determined whether or not the diagnosis of all cylinders has been completed, based on whether or not the counter u is equal to or greater than 21. If YES in step S50, that is, if it is completed, after the failure completion flag is set and the counter u is reset in step S51, N
Directly when the O i.e. not completed, the process proceeds to step _{S52, Tθ n, Tθ n-} 1, ΔTθ 0 is reset, the routine returns.

According to such a configuration, abnormality diagnosis is performed by comparing the output torque between the cylinder in which the post-injection has been shifted to the retard side and the cylinder in which the injection and combustion have been executed immediately before. Therefore, the accuracy of detecting an abnormality is improved. Also, a drop in overall torque can be prevented.

In the first embodiment, the post-injection timing is retarded by I _{fuD with} respect to the continuously burning cylinders (that is, the first cylinder, the third cylinder, the fourth cylinder, the second cylinder,...). , The post-injection time is retarded by a predetermined time I _fuD ),
By detecting the degree of torque drop at this time,
Abnormality diagnosis may be performed.

In the above embodiment, whether or not post-injection has been performed at a predetermined time is determined based on the output torque of the engine. However, the second embodiment in which the main part is shown in the flowchart of FIG. In such a process, it may be determined whether or not the post-injection has been executed at a predetermined timing based on the fluctuation of the in-cylinder pressure of the combustion chamber.

Hereinafter, the fuel injection control including the abnormality diagnosis executed by the ECU according to the second embodiment will be described. The flowchart of FIG. 5 shows a main part of the process of diagnosing the post-injection means based on the fluctuation of the in-cylinder pressure of the combustion chamber, and is a continuation of step S9 of FIG. 2A. Here, only steps after step S11, which are different from the first embodiment, will be described. The hardware configuration of the second embodiment is basically
This is the same as the first embodiment, but differs from the first embodiment in that each cylinder is provided with a sensor for detecting the in-cylinder pressure.

[0090] When the diagnosis in step S11 it is determined not completed, the process proceeds to step S60, step S2, S8 or S9 amounts set in (FIG. _{2A) Q b,, Q f} u and timing I _b, According to _Ifu , the fuel injection valve 5 is operated, and the main injection into the combustion chamber 4 and the post-injection are performed.

Then, the process proceeds to a step S61, wherein the locus of the in-cylinder pressure during a predetermined crank period is detected by the in-cylinder pressure sensor. The predetermined crank period is, for example, 60 minutes immediately after the main injection.
A crank angle (CA) of 10 ° to 60 ° is set up to the crank angle (CA).

Next, in step S62, the heat release rate for each crank angle is calculated by the above-described method, and the process proceeds to step S63, where the heat release rate calculated in step S62 is calculated at a predetermined heat release rate. Warm, that is, FIG.
(A) It is determined whether or not the heat generation rate corresponds to the heat generation by the post-injection indicated by the dotted lines in (b) and (c). If the post-injection means functions normally and post-injection is performed at a predetermined timing, the heat release rates calculated in step S62 are shown in FIGS. 3 (a), (b), and (c). Such a predetermined heat generation rate should be obtained. Therefore, if YES in step S63, that is, if the heat release rate calculated in step S62 is the predetermined heat release rate, step S63
At 64, the post-injection means is stored as normal, and the process proceeds to step S6.
Proceed to 6. In addition, NO in step S63, that is, step S63
If the heat release rate calculated in 62 is not the predetermined heat release rate, it is stored in step S65 that there is an abnormality in the post-injection, and a warning (warning) to the driver is made.
The display is performed, and the process proceeds to step S66. Step S66
Then, the failure completion flag is set, and then the process returns. In the second embodiment, such abnormality diagnosis is repeated at least four times until the abnormality diagnosis of all cylinders is completed.

Instead of detecting the post-injection injection timing based on the in-cylinder pressure, the combustion state in the combustion chamber is detected by measuring the combustion light in the combustion chamber to determine the post-injection injection timing. It may be.

Next, a third embodiment of the present invention will be described with reference to the flowcharts of FIGS. 6A, 6B and 6C. The hardware configuration of the third embodiment is the same as that of the first embodiment, except for the control processing performed by the ECU.

First, as shown in FIG. 6A, in step S101 after the start, the crank angle signal from the crank angle sensor 9, the accelerator opening from the accelerator opening sensor 32, and the amount of intake air from the air flow sensor 11 are obtained. Is input. Next, in step S102, the basic injection amount map is set based on the engine speed Ne determined from the target torque Tr and the crank angle signal obtained from the accelerator opening degree, the basic fuel injection amount Q _b
And the injection timing _Ib is read from a preset map.

Next, in step S103, the idle area
(ID) is determined. In the present embodiment,
Engine rotation speed 500 rpm to 1000 rpm, and
Although the accelerator opening 0 is set to the idle region,
The idle area may be determined based on a reference. Step S
If YES in 103, that is, if it is determined that the vehicle is in the idle region
In step S104, the current rotational speed Ne (k) is
In step S105, the average of the rotation speeds Ne of the past k times is stored.
Average Ne_aveIs calculated, and in step S106,
Average Ne_aveFrom the current rotational speed Ne_RealSubtract the difference ΔNe
Ask for. Next, in step S107, based on ΔNe,
And the fuel injection correction amount Q at idling from the map_IDCSet
In step S108, the basic fuel injection amount Q_bTo fuel
Injection correction amount Q _IDCAnd the basic fuel injection amount Q_bAnd then
Proceed to step S109. On the other hand, if NO in step S103
That is, when it is determined that the vehicle is not idling, the step
In S110, the rotation speed Ne (k) is reset to 0, and
Proceed to step S109.

In step S109, the post-injection injection amount Q _fu
And the injection timing _Ifu are set. Injection amount _{Qfu of} post-injection
In addition, the injection timing _Ifu is set by reading an amount corresponding to the target torque Tr and the engine speed Ne from a preset map.

In this map, the post-injection injection amount Q _fu
The fuel injection (amount or rate) by the post-injection is larger than when the amount of soot is less than the predetermined amount in an operation state in which the soot generated by combustion by the main injection is equal to or more than a predetermined amount (high rotation and high load). So that the generation of soot is suppressed. Here, the fuel injection amount by the post-injection indicates the absolute amount of fuel injected by the post-injection, and the fuel injection rate by the post-injection indicates a ratio of the injection amount of the post-injection to the injection amount of the main injection.

In this embodiment, the ratio of the injection amount of the post-injection to the injection amount of the main injection is 10 to 2 at low rotation and low load.
0%, and is increased to 20 to 50% or more at high rotation and high load.

Further, as a modified example, the fuel injection amount Q by the post-injection is also increased in a region where the amount of soot is increased except at the time of high rotation and high load, for example, at the time of A / F rich, at the time of pilot injection, and at the time of main injection retard. _fu may be increased compared to other operating conditions.

[0102] Further, the state of occurrence of soot using a map for setting the injection amount Q _fu of after-injection regardless may set the injection amount Q _fu of soot injection. Further, a configuration may be adopted in which the post-injection is not performed at the time of low rotation and low load such as idling, and the post-injection is performed in a region other than at the time of low rotation and low load. Furthermore, a map may be used in which the post-injection amount is 0 during the steady operation, and a post-injection is executed only at a predetermined acceleration by adding a predetermined value to the post-injection amount being 0 as described later.

The injection timing _Ifu of the post-injection is such that the combustion of the fuel by the post-injection is started when the diffusion combustion by the main injection is completed, that is, when the heat generation rate of the combustion by the main injection becomes substantially 0 or less. The ignition delay of the post-injection (0.4 to 0.7 m
s) and the ineffective injection time are set on the map.

With this setting, when the heat release rate becomes substantially equal to or less than 0, that is, when the diffusion combustion of the fuel mainly injected into the combustion chamber ends, the combustion of the fuel by the post-injection starts. Will be done. For this reason, in the state where the mixing of the soot and oxygen present in the combustion chamber 4 is promoted, the combustion by the post-injection starts, and it is considered that the generation of the soot is reduced.

Further, around the time when the heat generation rate by the main injection becomes substantially 0 or less (in terms of crank angle, preferably ± 10
°, more preferably within ± 5 °), the post-injection injection timing may be set such that combustion by the post-injection starts.

In the present embodiment, the end point of the diffusion combustion (ie, the point at which the heat release rate becomes approximately 0 or less) is calculated from the heat release rate obtained by the above-described calculation method. A map is used in which the injection timing _Ifu of the post-injection is a point in time that is earlier by a delay such as the ignition delay time of the post-injection.

Also in this embodiment, similarly to the first embodiment, near the end of diffusion combustion, that is, at low rotation speed and low load, 25 to 35 ° (CA) after compression top dead center.
At the time of medium rotation and medium load, 33-40 ° after compression top dead center
In (CA), it is preferable to set the post-injection timing so as to execute the post-injection at 45 to 48 ° (CA) after the compression top dead center at the time of high rotation and high load.

In this embodiment, as shown by the needle lift amount in FIG.
° (CA) at medium load during rotation
° (CA), at high rotation and high load, 48
° (CA), the post-injection timing is set so that the post-injection is performed, and the diffusion combustion ends in each operating state.
Starting combustion by post-injection at 1, t2, and t3,
It is set on the map so that the heat generation indicated by the dotted line in FIG. 3 occurs. In other operating states, the injection timing of the post-injection is set on the map so that the combustion by the post-injection starts when the diffusion combustion ends.

Next, in step S111, step S111
In accordance with the quantities Q _b , Q _fu and the timings I _b , I _fu set in 102, S108, or S109, the fuel injection valve 5
Is operated, and the main injection into the combustion chamber and the post-injection are executed.

Next, in step S112, it is determined whether or not the engine is in a high rotation range (for example, 2500 rpm or more).
If NO, that is, if the engine is not in the high rotation range, the process proceeds to step S13, and it is determined whether the engine is in the high load area based on, for example, the slot opening.

Step S112 or step S113
In YES, that is, when it is determined that the high rpm or high load region, the process proceeds to step S114, based on a signal from the accelerator sensor 32, the change rate [Delta] [alpha] of the accelerator opening degree α is smaller than the predetermined value [Delta] [alpha] ₀ It is determined whether or not the vehicle is in a predetermined steady operation state.

Step S113 or step S114
If NO, that is, if it is determined that the vehicle is not in the high load region or that the vehicle is not in the predetermined steady operation state, it is determined in step S115 whether the vehicle is in an idle region (ID). In this embodiment, the engine speed is from 500 rpm to 1000 r.
Although the pm and the accelerator opening 0 are defined as the idle region, the idle region may be determined based on other criteria. If NO in step S115, that is, if it is determined that it is not the idle region, the process proceeds to step S116, where the counter n and T ′ (θ) described later are reset and the process returns.

Step S114 or S115
If YES in step S117, that is, if it is determined that the vehicle is in a predetermined steady-state operating state or is in an idle region.
In FIG. 6B, a required time Tθ ′ for a predetermined crank period is read. The predetermined crank period is, for example, from 10 ° to 6 ° from immediately after the main injection to 60 ° crank angle (CA).
A 0 ° crank angle (CA) or the like is set, and the required time of this predetermined crank angle is detected and read by an IC timer or the like for each expansion stroke of each cylinder. The longer the required time Tθ ′, the larger the torque decrease. Therefore, it is possible to detect (estimate) the torque generated by the main injection and the post-injection based on the detected required time Tθ ′. Become.

Next, in step S118, 1 is added to the counter n, and in step S119, Tθ ′ (n), which is the current Tθ ′, is stored. In step S120, whether the counter n is equal to or more than a predetermined value n ₀ is determined. Is determined. n ₀ is an arbitrary constant, but is selected from the range of 10 to 1000 in the present embodiment. When the determination is NO in step S120, the process returns. When the determination is YES, in step S121, Tθ ′ (n ₁ ) to Tθ ′ (n ₀ ).
Are averaged to calculate an average value Tθ.

[0114] Subsequently, by clearing the counter n in step S122, T.theta in step S123 whether greater than a predetermined value T.theta ₀ is determined. Y in step S123
When ES i.e. T.theta is determined to be greater than a predetermined value T.theta _0, the process proceeds to step S124, the coefficient α is subtracted from the injection timing I _fu injection after being set in step S109,
A correction is made to shift the injection timing of the post-injection to the advance side. On the other hand, NO is determined in step S123, that is, Tθ is a predetermined value T.
If it is determined that it is not more than θ ₀ , the process proceeds to step S12
In step 5, the coefficient β is added to the post-injection injection timing _Ifu set in step S9, and correction is made to shift the post-injection injection timing to the retard side. Note that, since there is a relationship of | α |> | β |, the degree of correction to the advance side is set to be larger than the degree of correction to the retard side.

As described above, from FIG. 4, when the injection timing of the post-injection is retarded from about 48 ° (crank angle) after the main injection, which is the set timing of the post-injection at high load and high rotation,
It can be seen that the fuel efficiency deteriorates rapidly. This means that when the injection timing of the post-injection is retarded from about 48 ° (crank angle) after the main injection, the accelerator opening must be increased in order to produce the target torque. . Therefore, the injection timing of the post injection is about 48 after the main injection.
If it is more retarded than ° (crank angle) and the accelerator opening is maintained, the output torque will drop.

Here, it is considered that the torque due to the combustion of the main injection is not affected by the injection timing of the post-injection.
The drop in the output torque is a drop in the torque due to the combustion of the post-injection.
It is considered that the output torque of the engine decreases due to the combustion of the post-injection when the angle is more retarded than ° (crank angle).

For this reason, the output torque of the engine during (after) combustion by the post-injection is detected, and this value is set to a predetermined value (T
If it is lower than (θ ₀ ), it is understood that the injection timing of the post-injection is on the retard side from a predetermined timing, for example, about 48 ° (crank angle) after the main injection. Therefore, the injection timing of the post-injection is shifted to the advance side by α, and the delay of the post-injection is corrected.

On the other hand, when the output torque during combustion by the post-injection is equal to or more than the predetermined value (Tθ ₀ ), the post-injection injection timing becomes
Since the injection timing of the main injection is on the advance side from about 48 ° (crank angle), the injection timing of the post-injection is shifted to the retard side by β to reduce the “early premature” of the post-injection. to correct.

In the present embodiment, the correction to the advance side and the correction to the retard side are always executed to control the post-injection to be performed at an appropriate timing.

Next, in step S126, it is determined whether or not the corrected injection timing _Ifu of the post-injection is larger than the retard limit value (LLM) (retarded). Step S
If YES in 126, that is, if the post-injection injection timing _Ifu is greater than the retard limit value (LLM), 1 is added to the counter L in step S127, and the counter S is cleared in step S128, and the next (step S134) Proceed to.

On the other hand, if NO in step S126, that is, if the post-injection injection timing _Ifu is equal to or less than the retard limit value (LLM), the counter L is cleared in step S129, and further, in step S130, the corrected post-injection It is determined whether the injection timing _Ifu is greater than the advance limit value (SLM) (advanced).

If YES in step S130, that is, if the corrected injection timing _Ifu is greater than the advance limit value (SLM) (advanced), 1 is added to the counter S in step S131. The counter L is cleared in step S132, and the process proceeds to the next step (step S134).
If NO in step S130, that is, if the corrected injection timing _Ifu is equal to or less than the advance limit value (SLM), the counter S is cleared in step S133, and the process proceeds to the next (step S134). These LLMs, and
The SLM is set on a map in advance.

[0123] In step S134, the counter L is equal to or a predetermined value L ₀ or more, when YES, that more than the predetermined value, LLM long time, since it is above the limit value, the process proceeds to step S135, after When there is an abnormality in the injection, it is memorized and a warning to the driver (warning)
Display is performed. Further, in step S134, when NO That counter L is a predetermined value L ₀ is smaller than a predetermined value,
The process proceeds to step S136, the counter S is equal to or a predetermined value S ₀ or more, when YES, that above a predetermined value, LLS long time, the post-injection because it is more a limit value is abnormal The process proceeds to step S135, where it is memorized that there is an abnormality in the post-injection, and a warning (warning) is displayed to the driver.

If NO in step S137, LL
Since neither the M nor the LLS exceeded the limit value for a long time, it is stored in step S168 that the post-injection means is normal, and in step S139, the post-injection injection timing I _fu
Rewrites the map for setting and returns.

When rewriting the map, for example, the injection timing I _fu (Ne, T
When the correction amount (advance angle) of r) is α, the rotation speed Ne ₁ ,
Injection time I _fu for the torque _{Tr 1 (Ne 1, Tr 1} )
Is an amount corresponding to the difference in the number of revolutions or the torque, such that the angle is advanced by (Ne ₁ / Ne) α or (Tr ₁ / Tr) α.

When an abnormality warning is issued in step S135, the map of the post-injection injection timing _Ifu is rewritten to the basic map in step S139. This is to return to the basic post-injection control for the time being because the post-injection means is not operating normally.

The present invention is not limited to the above embodiment, and various changes or modifications can be made within the scope of the technical matters described in the claims. For example, when the post-injection timing is retarded according to the amount of torque change when the post-injection timing is forcibly advanced or retarded, when the torque is greatly reduced, the advanced angle is corrected while the decrease in torque is small. When it is (not more than a predetermined value), control may be performed to execute the retard correction (the correction degree is small).

Further, when the post-injection timing is retarded according to the amount of change in torque when the post-injection timing is forcibly advanced or retarded, the advance correction is performed when the torque greatly decreases, while the torque is corrected. When the decrease is small (below a predetermined value) (the degree of correction is small), it may be controlled to execute the retard correction.

In the above embodiment, the main injection and the post-injection are executed only once, respectively.
The present invention can be applied to those in which these are multi-stage injections.

Further, in this embodiment, the injection by the main injection is the diffusion combustion accompanied by the generation of soot, but the main injection is performed from the intake stroke to the first half of the compression stroke, and all the combustion by the main injection is performed. It is a configuration that is performed by premixed combustion, and even when performing post-injection to supply HC or the like as a reducing agent to a downstream catalyst, based on torque, in-cylinder pressure, etc.
The end timing of combustion by the main injection may be accurately determined, and the diagnosis of the post-injection means may be performed based on the end timing of combustion determined in this manner.

Further, since the amount of soot generated varies depending on the injection timing of the post-injection, when a particulate filter is provided in the exhaust system, the degree of increase in soot in the filter is detected by the pressure before and after the filter. Based on the degree of increase, the post-injection injection timing having a certain correlation with the generation of soot may be detected, and the post-injection means may be diagnosed accordingly.

[0132]

As described above, according to the present invention, when the injection timing of the post-injection is shifted from an appropriate timing, this can be detected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a diesel engine fuel injection control device according to an embodiment of the present invention.

FIG. 2A is the first half of a flowchart showing fuel injection control executed by an ECU in the first embodiment of the present invention.

FIG. 2B is a middle part of a flowchart showing the fuel injection control executed by the ECU in the first embodiment of the present invention.

FIG. 2C is the first half of a flowchart showing the fuel injection control executed by the ECU in the first embodiment of the present invention.

FIG. 3 is a time chart showing a heat generation rate in a combustion chamber.

FIG. 4 is a graph showing a relationship between a post-injection timing and a fuel efficiency.

FIG. 5 is a second half of a flowchart showing fuel injection control executed by the ECU in the second embodiment of the present invention.

FIG. 6A is the first half of a flowchart showing the fuel injection control executed by the ECU in the third embodiment of the present invention.

FIG. 6B is a middle part of a flowchart showing the fuel injection control executed by the ECU in the third embodiment of the present invention.

FIG. 6C is the first half of a flowchart showing fuel injection control executed by the ECU in the third embodiment of the present invention.

[Explanation of symbols]

 1: diesel engine 2: cylinder 5: fuel injection valve 35: ECU 36: injection control means 37: EGR control means

Continued on the front page (72) Inventor Akihiro Kobayashi 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda F-term (reference) 3G084 AA01 BA13 BA15 CA03 CA04 CA09 DA27 EB22 FA07 FA10 FA20 FA21 FA29 FA33 FA38 3G301 HA02 HA11 HA13 JB09 KA07 KA09 KA25 LB11 MA18 MA26 ND01 PA01Z PA11Z PB08Z PC01Z PD01Z PD03Z PE01A PE01Z PE03Z PE08Z PF03Z

Claims (6)

[Claims] 1. A fuel injection valve for directly injecting fuel into a combustion chamber of a diesel engine, and a main injection in which fuel is injected from the fuel injection valve at a predetermined time from an intake stroke to near a compression stroke top dead center. Main injection control means for performing; post-injection means for executing post-injection for injecting additional fuel at an injection timing set based on the timing at which combustion by the main injection has ended; and detecting a combustion state in the combustion chamber. An abnormality diagnosis device for a fuel injection control device for a diesel engine, comprising: a detection unit; and a diagnosis unit that diagnoses an injection state of the post-injection unit based on a detection result of the detection unit. 2. The method according to claim 1, wherein the detection unit detects a degree of heat generation in the combustion chamber, and the diagnosis unit performs the diagnosis based on a degree of heat generation during combustion by the post-injection. An abnormality diagnosis device for a fuel injection control device for a diesel engine as described in the above. 3. The diesel engine according to claim 1, wherein the diagnosis unit performs the diagnosis based on heat generation by post-injection executed when heat generation of combustion by the main injection is equal to or less than a predetermined value. An abnormality diagnosis device for the fuel injection control device of the engine. 4. The abnormality diagnosis device for a fuel injection control device for a diesel engine according to claim 1, wherein the detection means detects the combustion state based on at least an output torque after the execution of the post-injection. 5. The main injection control unit and the post-injection unit can change an interval between the main injection and the post-injection, and the diagnostic unit determines that when the interval is changed, the fluctuation of the output torque is predetermined. The abnormality diagnosis device for a fuel injection control device for a diesel engine according to claim 4, wherein when the value is equal to or more than the value, the after-injection means is diagnosed as normal. 6. The fuel injection control means performs feedback control so that the engine speed converges to a predetermined speed during idling, and the diagnostic means performs the high-speed or high-load steady operation region, or The abnormality diagnosis device for a fuel injection control device for a diesel engine according to any one of claims 1 to 5, wherein the diagnosis is performed during feedback control.