JP2016200039A - Fuel spray abnormality determination device for cylinder injection type diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine abnormality in fuel injection that is injected from a fuel injection valve.SOLUTION: At a fuel spray abnormality determination device for cylinder injection type diesel engine including a fuel injection valve and a cylinder pressure sensor 2, it is judged that spray of fuel injected from a fuel injection valve has abnormality when a cylinder pressure level Fc of primary resonance frequency band that is a cylinder pressure level at a resonance frequency band depending on a diameter of a combustion chamber is lower than a first reference value Fct and a cylinder pressure level Fb at a secondary resonance frequency band that is a cylinder pressure level at a resonance frequency band depending on a bore diameter is higher than a second reference value Fb or when a cylinder pressure level Fc at the primary resonance frequency band is higher than the first reference value Fct and the cylinder pressure level Fb at the secondary resonance band is lower than the secondary reference value Fbt.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a fuel spray abnormality determination device for a direct injection diesel engine having a fuel injection valve that directly injects fuel into a cylinder and an in-cylinder pressure sensor that detects the in-cylinder pressure, and in particular, an injection from the fuel injection valve. The present invention relates to a fuel spray abnormality determining device for a direct injection diesel engine capable of determining a fuel spray abnormality.

  2. Description of the Related Art Conventionally, a cylinder injection type internal combustion engine having a fuel injection valve that directly injects fuel into a cylinder and a glow plug integrated cylinder pressure sensor that detects cylinder pressure is known. An example of this type of in-cylinder injection internal combustion engine is described in Patent Document 1, for example. Patent Document 1 describes that the amount of deposit accumulated between the pressure receiving portion of the in-cylinder pressure sensor and the cylinder head of the engine is estimated when the engine is in a predetermined operating state.

JP 2009-2222031 A

By the way, in the in-cylinder internal combustion engine described in Patent Document 1, although the amount of deposit accumulated in the in-cylinder pressure sensor can be estimated, the deposit has accumulated in the fuel injection valve or the fuel injection valve has deteriorated. I can't estimate what I did. That is, it is not possible to estimate an abnormality in spraying of fuel injected from the fuel injection valve due to deposit accumulation on the fuel injection valve or deterioration of the fuel injection valve.
Therefore, in the in-cylinder injection internal combustion engine described in Patent Document 1, when deposits accumulate on the fuel injection valve or when the fuel injection valve deteriorates, an abnormality occurs in the spray of fuel injected from the fuel injection valve. As a result, there is a risk that emission may deteriorate and fuel consumption may deteriorate. In detail, there is a possibility that driving may be continued without being aware of the emission and the deterioration of fuel consumption.
As a result of intensive studies by the inventor, it has been found that the in-cylinder pressure level in the resonance frequency band depending on the combustion chamber diameter changes when the fuel spray injected from the fuel injection valve changes from normal to abnormal. It was. Specifically, when the penetration force of the fuel spray injected from the fuel injection valve becomes smaller than normal, the in-cylinder pressure level in the resonance frequency band depending on the combustion chamber diameter decreases, and the fuel injection valve injects. It has been found that the in-cylinder pressure level in the resonance frequency band depending on the combustion chamber diameter increases when the penetrating force of the sprayed fuel becomes larger than normal.
Further, as a result of intensive studies by the inventor, the in-cylinder pressure level in the resonance frequency band depending on the bore diameter may change when the fuel spray injected from the fuel injection valve changes from normal to abnormal. I was found. Specifically, when the penetration force of the fuel spray injected from the fuel injection valve becomes smaller than normal, the in-cylinder pressure level in the resonance frequency band depending on the bore diameter increases, and the fuel injection valve injects the fuel pressure. It has been found that the in-cylinder pressure level in the resonance frequency band depending on the bore diameter decreases when the penetration force of the fuel spray becomes larger than normal.

  That is, an object of the present invention is to provide a fuel spray abnormality determination device for a direct injection diesel engine that can determine an abnormality in fuel spray injected from a fuel injection valve.

According to the present invention, a fuel injection valve that directly injects fuel into a cylinder of a diesel engine;
An in-cylinder pressure sensor for detecting the in-cylinder pressure;
Based on the in-cylinder pressure detected by the in-cylinder pressure sensor, the in-cylinder pressure level in the resonance frequency band that depends on the combustion chamber diameter and the in-cylinder pressure level in the resonance frequency band that depends on the bore diameter. Frequency characteristic analyzing means for obtaining a secondary resonance frequency band in-cylinder pressure level which is a level;
In a fuel spray abnormality determining device for a direct injection diesel engine, comprising a fuel spray abnormality determining means for determining whether or not there is an abnormality in fuel spray injected from the fuel injection valve,
When the primary resonance frequency band in-cylinder pressure level is lower than a first reference value and the secondary resonance frequency band in-cylinder pressure level is higher than a second reference value; or
When the primary resonance frequency band in-cylinder pressure level is higher than the first reference value and the secondary resonance frequency band in-cylinder pressure level is lower than the second reference value,
There is provided a fuel spray abnormality determination device for a direct injection diesel engine, wherein the fuel spray abnormality determination means determines that there is an abnormality in fuel spray injected from the fuel injection valve.

That is, in the fuel spray abnormality determination device for a direct injection type diesel engine of the present invention, the fuel injection rate itself is set to a normal value due to, for example, injection hole corrosion due to deterioration of the fuel injection valve over time, deposit accumulation in the injection holes, and the like. Although not changed, it is possible to determine the state in which the spray abnormality has occurred. As a result, it is possible to suppress the deterioration of emissions and the deterioration of fuel consumption associated with the spray abnormality.
Specifically, for example, by taking measures such as notifying the driver of the occurrence of a spray abnormality, it is possible to reduce the continuing operation without noticing the emission or fuel consumption deterioration associated with the spray abnormality. it can.

  According to the present invention, it is possible to determine an abnormality in fuel spray injected from the fuel injection valve.

It is the schematic block diagram which showed the fuel spray abnormality determination apparatus of the cylinder injection type diesel engine of 1st Embodiment. It is the figure which compared the case where the spray of the fuel injected from a fuel injection valve is normal, and the case where it is abnormal. It is the figure which showed the relationship between the cylinder pressure detected by the cylinder pressure sensor 2, and time. It is the figure which showed the relationship between the heat release rate ROHR calculated from the cylinder pressure by the control apparatus 3, and time. It is the figure which showed the relationship between a cylinder pressure level and a frequency. It is a flowchart for demonstrating fuel spray abnormality determination of the cylinder injection type diesel engine of 1st Embodiment.

Hereinafter, a first embodiment of a fuel spray abnormality determination device for a direct injection diesel engine of the present invention will be described. FIG. 1 is a schematic configuration diagram illustrating a fuel spray abnormality determination device for a direct injection diesel engine according to the first embodiment. The fuel spray abnormality determination device for a direct injection diesel engine according to the first embodiment is applied to a diesel engine 1 (see FIG. 1) having a fuel injection valve (not shown) that directly injects fuel into the cylinder. .
In the fuel spray abnormality determination device for the in-cylinder injection type diesel engine of the first embodiment, the in-cylinder pressure [KPa] is detected by the in-cylinder pressure sensor 2 as shown in FIG. Based on the in-cylinder pressure [KPa], a control unit (ECU) 3 calculates an in-cylinder pressure level CPL (cylinder pressure level) [dB].

FIG. 3 is a diagram showing the relationship between the in-cylinder pressure detected by the in-cylinder pressure sensor 2 (see FIG. 1) and time. Specifically, FIG. 3 shows the relationship between the crank angle after top dead center (Crank Angle ATDC) [deg] (horizontal axis) and the in-cylinder pressure [KPa] (vertical axis) when fuel is normally injected from the fuel injection valve. It is the figure which showed the relationship.
In the earnest research of the present inventor, for example, even when a spray abnormality of fuel injected from the fuel injection valve occurs due to, for example, injection hole corrosion due to deterioration over time of the fuel injection valve, deposit accumulation in the injection hole, etc. It has been found that when the fuel injection rate itself does not change from the normal value, the in-cylinder pressure detected by the in-cylinder pressure sensor 2 is the same as the in-cylinder pressure shown in FIG.
That is, according to the earnest study of the present inventor, even if the relationship between the in-cylinder pressure [KPa] and the crank angle after top dead center [deg] as shown in FIG. It has been found that it is not possible to determine whether or not an abnormality has occurred in the spray of fuel injected from the fuel injection valve due to the associated injection hole corrosion, deposit accumulation in the injection hole, or the like.
In addition, in the diligent research of the present inventor, there was a case where an abnormality in spraying of fuel injected from the fuel injection valve occurred due to, for example, injection hole corrosion due to deterioration of the fuel injection valve over time, deposit accumulation in the injection hole, or the like. However, if the fuel injection rate itself does not change from the normal value, the overall value [dB] of the combustion noise level calculated from the in-cylinder pressure [KPa] by the control device 3 is equal to that when no spray abnormality has occurred. It has been found that the combustion noise level is similar to the overall value [dB].
Inventor's diligent research has shown that the combustion noise level overall is obtained under the operating conditions in which the relationship between the crank angle [deg] after top dead center [deg] (horizontal axis) and the in-cylinder pressure [KPa] (vertical axis) shown in FIG. The value became 89 [dB].

FIG. 4 is a diagram showing a relationship between the heat generation rate ROHR (rate of heat release) [J / deg] calculated from the in-cylinder pressure [KPa] by the control device 3 (see FIG. 1) and time. Specifically, FIG. 4 shows the relationship between the crank angle after top dead center [deg] (horizontal axis) and the heat release rate ROHR [J / deg] (vertical axis) when fuel is normally injected from the fuel injection valve. FIG.
In the earnest research of the present inventor, for example, even when a spray abnormality of fuel injected from the fuel injection valve occurs due to, for example, injection hole corrosion due to deterioration over time of the fuel injection valve, deposit accumulation in the injection hole, etc. When the fuel injection rate itself does not change from the normal value, it has been found that the heat generation rate ROHR calculated from the in-cylinder pressure by the control device 3 is the same as the heat generation rate ROHR shown in FIG.
That is, according to the present inventors' earnest research, even if the relationship between the heat generation rate ROHR [J / deg] and the crank angle after top dead center [deg] as shown in FIG. It has been found that it is not possible to determine whether or not an abnormality has occurred in the spray of fuel injected from the fuel injection valve due to corrosion of the injection hole due to deterioration over time, deposit accumulation in the injection hole, or the like.

On the other hand, in earnest research of the inventor, for example, when an abnormal spray of fuel injected from the fuel injection valve occurs due to, for example, corrosion of the injection hole due to deterioration of the fuel injection valve over time, deposit accumulation in the injection hole, etc. It has been found that the emission value, particularly the smoke component concentration value FSN (filter smoke number), increases.
FIG. 2 is a diagram comparing the case where the fuel spray injected from the fuel injection valve is normal and the case where it is abnormal. In FIG. 2, the vertical axis represents the smoke component concentration value FSN, and the horizontal axis represents the NOx generation amount [g / h]. The curve connecting the “◯” marks in FIG. 2 shows the case where deposits accumulate in the nozzle holes of the fuel injection valve and a spray abnormality occurs that reduces the spray penetration force. A curve connecting “Δ” marks in FIG. 2 indicates a case where fuel is normally injected from the fuel injection valve and normal spray having a large spray penetration force is formed.
As shown in FIG. 2, in earnest research by the present inventor, when deposits accumulate in the nozzle holes of the fuel injection valve and a spray abnormality that reduces the spray penetration force occurs, fuel is normally injected from the fuel injection valve. It was found that the concentration value FSN of the smoke component increased compared to the case where the smoke component is present.

Furthermore, as a result of intensive studies by the inventor, when the spray of fuel injected from the fuel injection valve becomes abnormal from normal, the in-cylinder pressure level CPL [dB] in the resonance frequency band depending on the combustion chamber diameter. Has been found to change. Further, it has been found that the in-cylinder pressure level CPL [dB] in the resonance frequency band depending on the bore diameter changes when the fuel spray injected from the fuel injection valve changes from normal to abnormal.
FIG. 5 is a diagram showing the relationship between the in-cylinder pressure level CPL [dB] (vertical axis) and the frequency f [Hz] (horizontal axis). Specifically, FIG. 5 shows the in-cylinder pressure level CPL [dB] when the fuel is normally injected from the fuel injection valve and a normal spray having a large spray penetration force is formed, and the fuel injection valve corrodes. FIG. 6 is a diagram showing a comparison with an in-cylinder pressure level CPL [dB] in a case where a spray abnormality occurs where the spray penetration force is reduced as a result of deposits being deposited in the nozzle holes of the fuel injection valve.
The relationship between the in-cylinder pressure level CPL [dB] and the frequency f [Hz] as shown in FIG. 5 is determined from the in-cylinder pressure [KPa] detected by the in-cylinder pressure sensor 2 (see FIG. 1). dB] is calculated by the control device 3 (see FIG. 1), and then the relationship between the in-cylinder pressure level CPL [dB] and time (crank angle after top dead center) is determined by, for example, the frequency characteristic analysis device 3a ( It can be obtained by performing computation (for example, fast Fourier transform) according to FIG.

Specifically, as shown in FIG. 5, when the present inventor has conducted earnest research, combustion occurs when a spray abnormality occurs in which the penetration force of the fuel spray injected from the fuel injection valve becomes smaller than normal. In the resonance frequency band of about 5000 to 6600 [Hz] depending on the chamber diameter, the in-cylinder pressure level CPL [dB] decreases from the normal value, and in the resonance frequency band of about 6600 to 9000 [Hz] depending on the bore diameter. It has been found that the in-cylinder pressure level CPL [dB] increases from the normal value.
As the penetration force of the fuel spray injected from the fuel injection valve becomes smaller than normal, the combustion position changes, and as a result, a resonance frequency band of about 5000 to 6600 [Hz] depending on the combustion chamber diameter. It is considered that the in-cylinder pressure level CPL [dB] at 1 is decreased from the normal value and the in-cylinder pressure level CPL [dB] in the resonance frequency band of about 6600 to 9000 [Hz] depending on the bore diameter is increased from the normal value.
Although not shown in the figure, as a result of earnest research conducted by the present inventor, when a spray abnormality in which the penetration force of the fuel spray injected from the fuel injection valve becomes larger than normal for some reason occurs, the combustion chamber diameter In the resonance frequency band of about 5000 to 6600 [Hz] depending on the cylinder, the in-cylinder pressure level CPL [dB] increases from the normal value, and in the resonance frequency band of about 6600 to 9000 [Hz] depending on the bore diameter, It was found that the internal pressure level CPL [dB] decreased from the normal value.
As the penetration force of the fuel spray injected from the fuel injection valve becomes larger than normal, the combustion position changes, and as a result, a resonance frequency band of about 5000 to 6600 [Hz] depending on the combustion chamber diameter. It is considered that the in-cylinder pressure level CPL [dB] at 1 is increased from the normal value, and the in-cylinder pressure level CPL [dB] in the resonance frequency band of about 6600 to 9000 [Hz] depending on the bore diameter is decreased from the normal value.

  That is, the relationship between the in-cylinder pressure [KPa] and the crank angle after top dead center [deg] shown in FIG. 3, the overall value of the combustion noise level, and the heat generation rate ROHR [J / deg] shown in FIG. Depending on the relationship with the post-crank crank angle [deg], an abnormality in the fuel injection rate can be determined, but an abnormality in the spray cannot be determined, and the in-cylinder pressure [KPa] shown in FIG. Discrimination is made based on the relationship with the crank angle [deg] after the point, the overall value of the combustion noise level, and the relationship between the heat generation rate ROHR [J / deg] and the crank angle [deg] after the top dead center shown in FIG. It has been found by inventor's earnest research that the spray abnormality that cannot be performed can be determined by the relationship between the in-cylinder pressure level CPL [dB] and the frequency f [Hz] shown in FIG.

FIG. 6 is a flowchart for explaining fuel spray abnormality determination of the direct injection diesel engine of the first embodiment.
As shown in FIG. 6, when the fuel spray abnormality determination of the direct injection diesel engine of the first embodiment is started, whether or not EGR cut is executed during idle operation or steady operation in step S101. Is determined. When the result is Yes, the process proceeds to step S102, and when the result is No, it is determined that the operation state is not suitable for executing the fuel spray abnormality determination, and this routine is terminated, and the process from step S101 is resumed after a predetermined period.
Since the idle operation state and the steady operation state are operation states that are always included during normal driving of the vehicle, the fuel spray abnormality determination is performed by executing the fuel spray abnormality determination in the idle operation state or the steady operation state. The execution frequency can be improved.
On the other hand, when the EGR valve is open, for example, the value of the in-cylinder pressure level CPL [dB] of normal spray shown in FIG. 5 may vary depending on the EGR rate based on the opening of the EGR valve (that is, In the example shown in FIG. 6, when the EGR valve is not fully closed, it is determined No in step S101.

In step S102, the in-cylinder pressure [KPa] is detected by the in-cylinder pressure sensor 2 (see FIG. 1).
Next, in step S103, the history of in-cylinder pressure [KPa] detected in step S102 is compared with the in-cylinder pressure history map recorded in the map 3c (see FIG. 1) of the control device 3 (see FIG. 1). As the in-cylinder pressure history map, for example, the relationship between the in-cylinder pressure [KPa] and the crank angle after top dead center [deg] when the fuel shown in FIG. 3 is normally injected from the fuel injection valve is used.
In step S103, when it is determined that the history of the in-cylinder pressure [KPa] detected in step S102 is in accordance with the in-cylinder pressure history map, the process proceeds to step 104. On the other hand, when the in-cylinder pressure [KPa] history detected in step S102 is different from the in-cylinder pressure history map, it is determined that a fuel injection rate abnormality has occurred, and the process proceeds to step S110.
In the example shown in FIG. 6, for example, the relationship between the in-cylinder pressure [KPa] and the crank angle after top dead center [deg] shown in FIG. 3 is used for determining the fuel injection rate abnormality. FIG. 4 shows the relationship between the heat generation rate ROHR [J / deg] and the crank angle after top dead center [deg], for example, the combustion center of gravity estimated from the in-cylinder pressure [KPa], the 50% combustion end position, etc. It can also be used for abnormality determination.

In step S104, the frequency characteristic analysis is executed by the frequency characteristic analysis device 3a (see FIG. 1) and the filter processing device 3b (see FIG. 1) of the control device 3 (see FIG. 1).
Specifically, for example, when it is necessary to acquire the in-cylinder pressure level CPL [dB] in a resonance frequency band of about 5000 to 6600 [Hz] depending on the combustion chamber diameter, the cylinder calculated from the in-cylinder pressure [KPa]. Components of the internal pressure level CPL [dB] other than the frequency band of about 5000 to 6600 [Hz] are removed by the filter processing device 3b, and the in-cylinder pressure level CPL [dB] in the frequency band of about 5000 to 6600 [Hz] is obtained. can get.
For example, when it is necessary to acquire the in-cylinder pressure level CPL [dB] in the resonance frequency band of about 6600 to 9000 [Hz] depending on the bore diameter, the in-cylinder pressure level CPL [dB] calculated from the in-cylinder pressure [KPa]. ] Other than the frequency band of about 6600 to 9000 [Hz] is removed by the filter processing device 3b, and the in-cylinder pressure level CPL [dB] in the frequency band of about 6600 to 9000 [Hz] is obtained.

Next, in step S105, the overall value [dB] of the combustion noise level calculated from the in-cylinder pressure [KPa] by the control device 3 (see FIG. 1) is recorded in the map 3c (see FIG. 1) of the control device 3. It is compared with the overall value map of the combustion noise level. As the overall value map of the combustion noise level, for example, the overall value of the combustion noise level when the fuel is normally injected from the fuel injection valve is used.
If Yes, that is, if it is determined that the overall value [dB] of the combustion noise level calculated from the in-cylinder pressure [KPa] by the control device 3 is in accordance with the overall value map of the combustion noise level, the routine proceeds to step 106. On the other hand, when No, that is, when the overall value [dB] of the combustion noise level calculated from the in-cylinder pressure [KPa] by the control device 3 is different from the overall value map of the combustion noise level, the fuel spray abnormality determination is executed. This routine is terminated, and the processing from step S101 is resumed after a predetermined period.
Specifically, in the fuel spray abnormality determination device for the in-cylinder injection type diesel engine of the first embodiment, the overall value [dB] of the combustion noise level calculated from the in-cylinder pressure [KPa] by the control device 3 is the combustion noise level. When the difference is different from the overall value map, the swirl variation occurring in the cylinder is large, and the value of the normal pressure in-cylinder pressure CPL [dB] shown in FIG. 5 varies (that is, the accuracy of the abnormal spray determination). It is determined that the operation state is not suitable for executing the fuel spray abnormality determination.

In step S106, about 5000 in FIG. 5 depending on the combustion chamber diameter calculated by the frequency characteristic analysis device 3a (see FIG. 1) and the filter processing device 3b (see FIG. 1) of the control device 3 (see FIG. 1). In the resonance frequency band of about 6600 to 9000 [Hz] in FIG. 5 depending on the primary resonance frequency band in-cylinder pressure level Fc which is the in-cylinder pressure level [dB] in the resonance frequency band of ˜6600 [Hz] and the bore diameter. A secondary resonance frequency band in-cylinder pressure level Fb that is in-cylinder pressure level [dB] is obtained.
Next, in step S107, the fuel is recorded in the map 3c (see FIG. 1) of the control device 3 (see FIG. 1) and depends on the combustion chamber diameter when the fuel is normally injected from the fuel injection valve in FIG. The first reference value Fct which is the in-cylinder pressure level [dB] in the resonance frequency band of about 5000 to 6600 [Hz] and about the bore diameter in FIG. 5 depending on the bore diameter when the fuel is normally injected from the fuel injection valve. The in-cylinder pressure level [dB] in the resonance frequency band of 6600 to 9000 [Hz] and the second reference value Fbt are read.

Next, in step S108, the primary resonance frequency band in-cylinder pressure level Fc obtained in step S106 is lower than the first reference value Fct read in step S107, and the secondary resonance frequency band obtained in step S106. It is determined whether or not the cylinder pressure level Fb is higher than the second reference value Fbt read in step S107.
If Yes, it is determined that a spray abnormality having a small spray penetration force has occurred as in the example shown in FIG. 5, and the process proceeds to step S110. On the other hand, if No, the process proceeds to step S109.

In step S109, the primary resonance frequency band in-cylinder pressure Fc obtained in step S106 is higher than the first reference value Fct read in step S107, and the secondary resonance frequency band in-cylinder pressure obtained in step S106. It is determined whether or not the level Fb is lower than the second reference value Fbt read in step S107.
If Yes, it is determined that a spray abnormality having a large spray penetration force has occurred, and the process proceeds to step S110. On the other hand, when the determination is No, it is determined that no spray abnormality has occurred, and this routine is terminated, and the processing from step S101 is resumed after a predetermined period.

  In step S110, measures are taken such as notifying the driver that a fuel injection abnormality such as a fuel injection rate abnormality or a spray abnormality has occurred. Specifically, for example, a MIL (malfunction indicator lamp) (abnormal warning lamp) is turned on.

In other words, in the fuel spray abnormality determination device for the in-cylinder injection type diesel engine of the first embodiment, the combustion chamber diameter is adjusted based on the in-cylinder pressure [KPa] detected by the in-cylinder pressure sensor 2 (see FIG. 1). 5 depends on the primary resonance frequency band in-cylinder pressure level Fc (see FIG. 6) which is the in-cylinder pressure level CPL [dB] in the resonance frequency band of about 5000 to 6600 Hz in FIG. 5, and about in FIG. The control device 3 (see FIG. 1) functioning as a frequency characteristic analyzing means for obtaining a secondary resonance frequency band in-cylinder pressure level Fb (see FIG. 6) which is the in-cylinder pressure level CPL [dB] in the resonance frequency band of 6600 to 9000 Hz. A frequency characteristic analysis device 3a (see FIG. 1) and a filter processing device 3b (see FIG. 1) are provided.
Moreover, the control apparatus 3 which functions as a fuel spray abnormality determination means which determines the presence or absence of the spray abnormality of the fuel injected from the fuel injection valve is provided.
Specifically, the primary resonance frequency band in-cylinder pressure level Fc is lower than the first reference value Fct (the value of the “normal spray” in-cylinder pressure level CPL [dB] in the frequency band of about 5000 to 6600 Hz in FIG. 5). When the in-cylinder pressure level Fb of the secondary resonance frequency band is higher than the second reference value Fbt (the value of the in-cylinder pressure level CPL [dB] of “normal spray” in the frequency band of about 6600 to 9000 Hz in FIG. 5). Furthermore, in step S108 (see FIG. 6), the control device 3 functioning as the fuel spray abnormality determining means has an abnormality in the spray of the fuel injected from the fuel injection valve (specifically, compared with the normal spray). It is determined that the spray penetration force is small.
When the primary resonance frequency band in-cylinder pressure level Fc is higher than the first reference value Fct and the secondary resonance frequency band in-cylinder pressure level Fb is lower than the second reference value Fbt, step S109 (see FIG. 6). ), The control device 3 functioning as a fuel spray abnormality determining means determines that there is an abnormality in the fuel spray injected from the fuel injection valve (specifically, the spray penetration force is greater than that of the normal spray). To do.
Therefore, according to the fuel spray abnormality determination device for the in-cylinder injection type diesel engine of the first embodiment, the fuel injection rate is increased due to, for example, injection hole corrosion due to deterioration of the fuel injection valve over time, deposit accumulation in the injection holes, and the like. Although the value itself is not different from the normal value, it is possible to determine the state in which the spray abnormality has occurred.

  In the second embodiment, the above-described first embodiment and each example can be appropriately combined.

1 Engine 2 In-cylinder pressure sensor 3 Control device 3a Analysis device 3b Filter processing device 3c Map

Claims (1)

A fuel injection valve that directly injects fuel into the cylinder of the diesel engine;
An in-cylinder pressure sensor for detecting the in-cylinder pressure;
Based on the in-cylinder pressure detected by the in-cylinder pressure sensor, the in-cylinder pressure level in the resonance frequency band that depends on the combustion chamber diameter and the in-cylinder pressure level in the resonance frequency band that depends on the bore diameter. Frequency characteristic analyzing means for obtaining a secondary resonance frequency band in-cylinder pressure level which is a level;
In a fuel spray abnormality determining device for a direct injection diesel engine, comprising a fuel spray abnormality determining means for determining whether or not there is an abnormality in fuel spray injected from the fuel injection valve,
When the primary resonance frequency band in-cylinder pressure level is lower than a first reference value and the secondary resonance frequency band in-cylinder pressure level is higher than a second reference value; or
When the primary resonance frequency band in-cylinder pressure level is higher than the first reference value and the secondary resonance frequency band in-cylinder pressure level is lower than the second reference value,
The fuel spray abnormality determining apparatus for a direct injection diesel engine, wherein the fuel spray abnormality determining means determines that there is an abnormality in the fuel spray injected from the fuel injection valve.

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