JP3617348B2 - Fuel injection timing control device for diesel engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection timing control device for a diesel engine that performs fuel injection timing control according to the operating state of the diesel engine.
[0002]
[Prior art]
Conventionally, as for the fuel injection timing of a diesel engine, an appropriate basic fuel injection timing is determined from the viewpoints of fuel consumption, noise, output, emission, and the like, and fuel injection for preventing misfire with respect to this basic fuel injection timing. Timing correction is made (Japanese Patent Laid-Open Nos. 6-299894 and 10-252529).
[0003]
[Problems to be solved by the invention]
In the technology described in Japanese Patent Laid-Open No. 6-299894, the basic fuel injection timing is corrected in advance according to the altitude, and in the technology described in Japanese Patent Laid-Open No. 10-252529, the basic fuel injection timing is corrected according to the intake pressure and the intake air temperature. doing.
[0004]
However, there are the following problems in correcting the advance angle of the basic fuel injection timing based on the operating state of the diesel engine in order to prevent misfire.
That is, the advance correction of the injection timing is performed based on the relationship shown in the map using the intake pressure, intake air temperature, etc. and the engine speed as parameters, and the engine load is included in the parameters. Absent. Therefore, in order to cover the correction amount corresponding to the engine load, the maximum correction value by the engine load is added to all the correction amounts. Since the maximum value for the engine load is taken into account in this way, excessive advance angle correction is performed in most operating regions as compared with actual operation.
[0005]
In addition, regarding the basic fuel injection timing that is subject to advance angle correction, the engine load is included in the parameter, but the basic fuel injection timing is set according to a request such as emission during warm-up (warm time). And at least misfire is not the main determinant.
[0006]
For this reason, in order to prevent misfire, the fuel injection timing obtained by advancing the basic fuel injection timing with the intake pressure, intake air temperature, etc. as a parameter has been advanced excessively from the misfire region in most operating regions. It will be set as a thing. In particular, when the load is high, the degree of excessive advance is large.
[0007]
Such an excessive advance angle of the fuel injection timing at the time of high load increases combustion noise and may cause environmental problems due to engine noise.
In addition, techniques (JP-A-10-103126 and JP-A-7-91300) for preventing the fuel injection timing from becoming excessively advanced by feedback control have also been proposed. It converges slowly at the injection timing, temporarily leading to an over-advance state, and it cannot be said that combustion noise is sufficiently suppressed.
[0008]
An object of the present invention is to prevent an over-advanced angle in fuel injection timing control for preventing misfire in a diesel engine and to suppress combustion noise.
[0009]
[Means for Solving the Problems]
The fuel injection timing control device for a diesel engine according to claim 1 is a fuel injection timing control device for a diesel engine that performs fuel injection timing control according to the operating state of the diesel engine.While determining the basic fuel injection timing based on the operating condition of the diesel engine using emissions as a setting factor, the misfire limit is used as a setting factor.The basic misfire limit injection timing is determined based on the relationship between the engine speed and engine load in the diesel engine operating condition.When determining, independently of the basic fuel injection timingThe basic misfire limit injection timing is corrected by a limit change correction value obtained based on a relationship using a limit change factor in the operating state of the diesel engine as a parameter to obtain a misfire limit injection timing,SaidWhen the basic fuel injection timing is present behind the misfire limit injection timing, the actual fuel injection timing is controlled based on the misfire limit injection timing, and the basic fuel injection timing is advanced from the misfire limit injection timing. If it is present on the side, the actual fuel injection timing is controlled based on the basic fuel injection timing.
[0010]
In the present invention, as in the prior art,Emission is required as a setting factorRather than correcting the basic fuel injection timing to prevent misfire,Using misfire limit as a setting factorThe basic misfire limit injection timing is obtained based on the relationship between engine speed and engine load as parameters.In this case, this is determined independently of the basic fuel injection timing.. Therefore, the engine load is reflected in the basic misfire limit injection timing. Then, the misfire limit injection timing is obtained by correcting the basic misfire limit injection timing with a limit change correction value obtained on the basis of the relationship using the limit change factor in the operating state of the diesel engine as a parameter. As a result, the misfire limit injection timing does not include setting factors such as emissions as in the case where the basic fuel injection timing is corrected in the prior art, and the misfire limit injection timing should be calculated with high accuracy reflecting the engine load. Can do.
[0011]
The misfire limit injection timing is used to control the actual fuel injection timing based on the misfire limit injection timing when the basic fuel injection timing is on the retard side of the misfire limit injection timing. As a result, the actual fuel injection timing is set at the misfire limit position, so that misfire can be surely prevented and an excessive advance is not made.
[0012]
Also,Emission is required as a setting factorWhen the basic fuel injection timing is on the more advanced side than the misfire limit injection timing, the actual fuel injection timing is controlled based on the basic fuel injection timing. In this case, the basic fuel injection timing is advanced from the misfire limit, but the basic fuel injection timing itself is not corrected for advancement from the viewpoint of misfire prevention. No advance is made.
[0013]
Therefore, the actual fuel injection timing can be controlled to an advance angle state that is equal to or greater than the misfire limit, and combustion noise can be suppressed because it does not become an over-advance angle.
The fuel injection timing control device for a diesel engine according to claim 2 is a fuel injection timing control device for a diesel engine that performs fuel injection timing control in accordance with the operation state of the diesel engine. Means,Basic fuel injection timing calculating means for obtaining basic fuel injection timing according to the operating state of the diesel engine detected by the operating state detecting means with emission as a setting factor, and misfire limit as a setting factorBased on the relationship between the engine speed and the engine load in the operating state of the diesel engine detected by the operating state detecting means as parameters.Independent of the basic fuel injection timingA basic misfire limit calculation means for obtaining a basic misfire limit injection timing, and a limit for obtaining a limit change correction value on the basis of a relationship in which the limit change factor in the operating state of the diesel engine detected by the operating state detecting means is a parameter. The misfire limit injection timing obtained by correcting the basic misfire limit injection timing obtained by the change correction value calculating means and the basic misfire limit calculation means by the limit change correction value obtained by the limit change correction value calculating means. Misfire limit injection timing correction means,PreviousThe misfire limit injection timing obtained by the misfire limit injection timing correction means and the basic fuel injection timing obtained by the basic fuel injection timing calculation means are compared, and the basic fuel is more than the misfire limit injection timing. When the injection timing is on the retard side, the actual fuel injection timing is controlled based on the misfire limit injection timing, and the basic fuel injection timing is on the advance side with respect to the misfire limit injection timing Comprises fuel injection timing control means for controlling the actual fuel injection timing based on the basic fuel injection timing.
[0014]
Basic misfire limit calculation meansUsing misfire limit as a setting factorBased on the relationship between engine speed and engine load as parametersIndependent of basic fuel injection timingObtain the basic misfire limit injection timing. Then, the limit change correction value calculation means obtains the limit change correction value based on the relationship using the limit change factor in the operating state of the diesel engine as a parameter. The misfire limit injection timing correction means corrects the basic misfire limit injection timing with the limit change correction value to obtain the misfire limit injection timing. As a result, it is possible to obtain a highly accurate misfire limit injection timing that does not include setting factors such as emissions in the case of the prior art in which the basic fuel injection timing is corrected and reflects the engine load.
[0015]
Then, the fuel injection timing control means compares the misfire limit injection timing with the basic fuel injection timing, and if the basic fuel injection timing is retarded than the misfire limit injection timing, the fuel injection timing control means Based on this, the actual fuel injection timing is controlled. As a result, the actual fuel injection timing is set at the misfire limit position, so that misfire can be surely prevented and an excessive advance is not made.
[0016]
Also, the fuel injection timing control means is more effective than the misfire limit injection timing.Emission is required as a setting factorWhen the basic fuel injection timing is on the advance side, the actual fuel injection timing is controlled based on the basic fuel injection timing. In this case, although the basic fuel injection timing is advanced from the misfire limit, the basic fuel injection timing itself is not corrected for advancement from the viewpoint of preventing misfire, so the actual fuel injection timing is excessively advanced. No corners are made.
[0017]
Therefore, as in the first aspect, the actual fuel injection timing can be controlled to an advanced angle state that is equal to or greater than the misfire limit, and combustion noise can be suppressed because the actual fuel injection timing does not become an excessive angle.
The fuel injection timing control device for a diesel engine according to claim 3 is the configuration according to claim 2, wherein the limit changing factor is one or more values selected from intake pressure, cooling water temperature and intake air temperature. And the engine speed.
[0018]
As described above, by using one or more values selected from the intake pressure, the coolant temperature and the intake air temperature, and the engine speed as the limit change factor, the optimum limit change adapted to the operating state of the diesel engine is achieved. A correction value can be obtained. For this reason, by using the misfire limit injection timing obtained by being corrected by the limit change correction value, in addition to the function and effect of the second aspect, more precise control becomes possible.
[0019]
According to a fourth aspect of the present invention, there is provided the fuel injection timing control device for a diesel engine according to the second or third aspect, wherein the limit change correction value calculating means is configured to determine the limit based on a map using the limit change factor as a parameter. A change correction value is obtained.
[0020]
Thus, since the limit change correction value can be obtained from the map that can reflect the experimental data, in addition to the operational effect of the second or third aspect, precise control that is more practically adapted can be realized.
[0021]
In addition to the structure in any one of Claims 2-4, the fuel injection timing control apparatus of the diesel engine of Claim 5 isWhen the fuel injection timing control means controls the actual fuel injection timing based on the misfire limit injection timing,The misfire limit injection timing obtained by the misfire limit injection timing correction means isTo prevent excessive advance angle, which is a problem for the protection of diesel enginesWhen the advance angle upper limit guard value is on the advance side, the advance angle upper limit guard means for resetting the misfire limit injection timing based on the advance angle upper limit guard value is provided.
[0022]
The advance angle upper limit guard means has the misfire limit injection timing determined by the misfire limit injection timing correction means,To prevent excessive advance angle, which is a problem for the protection of diesel enginesIf the advance angle is higher than the advance angle upper guard value, the misfire limit injection timing is reset based on the advance angle upper guard value..
[0023]
In this way, in addition to the operational effects of any one of claims 2 to 4, it is possible to prevent the misfire limit injection timing from becoming an excessive advance angle which causes a problem in protecting the diesel engine. For this reason, it is possible to prevent the fuel injection timing control means from setting an excessively advanced injection timing which is a problem in protecting the diesel engine in the actual fuel injection timing, thereby protecting the diesel engine.
[0024]
According to a sixth aspect of the present invention, in the fuel injection timing control device for a diesel engine, in the configuration according to the fifth aspect, the advance upper limit guard means detects the advance upper limit guard value by the operating state detection means. It is obtained according to the operating state of the diesel engine.
[0025]
Thus, by setting the advance angle upper limit guard value according to the operating state of the diesel engine, in addition to the effect of the fifth aspect, more precise advance angle upper limit guard becomes possible.
[0026]
According to a seventh aspect of the present invention, in the fuel injection timing control device for a diesel engine, the advance angle upper limit guard means detects the advance angle upper limit guard value by the operating state detection means. Further, it is obtained according to the engine speed and the engine load in the operating state of the diesel engine.
[0027]
Specifically, by obtaining the advance angle upper limit guard value in this way, the operational effect of claim 6 can be produced.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
FIG. 1 is a block diagram showing a schematic configuration of a diesel engine control device 2 to which the above-described invention is applied.
[0029]
The diesel engine 4 is mounted on a vehicle for driving an automobile. The diesel engine 4 includes a turbocharger 6, and the air introduced into the intake pipe 10 via the air cleaner 8 is supercharged by the turbocharger 6, and enters the cylinder 16 via the intercooler 12 and the venturi 14. To the combustion chamber 18.
[0030]
Exhaust after the fuel is injected from the fuel injection valve 20 in the combustion chamber 18 and combusted is discharged to the exhaust pipe 22 and driven to the outside by driving the turbocharger 6. An exhaust gas recirculation pipe 24 is provided between the exhaust pipe 22 upstream of the turbocharger 6 and the intake pipe 10 downstream of the venturi 14. The exhaust gas recirculation pipe 24 is provided with an EGR valve 26 whose opening / closing is adjusted via an electric negative pressure adjustment valve (EVRV) 74 in accordance with an instruction from an electronic control unit (hereinafter simply referred to as “ECU”) 51. When the EGR valve 26 is in an open state, the exhaust gas recirculation pipe 24 supplies exhaust gas from the exhaust pipe 22 to the intake pipe 10 according to the opening degree, thereby realizing exhaust gas recirculation.
[0031]
High-pressure fuel is supplied to the fuel injection valve 20 from the distributed fuel injection pump 28 with the fuel injection timing and fuel injection amount adjusted. The distribution type fuel injection pump 28 is provided with a timing control valve 30 and is driven by the ECU 51 to adjust the fuel injection timing. Further, the distribution type fuel injection pump 28 is provided with an electromagnetic spill valve 32, which is driven by the ECU 51 to adjust the fuel injection amount.
[0032]
The first throttle valve 34 in the venturi 14 opens and closes in conjunction with the accelerator pedal 36, and an accelerator sensor 38 is provided on the rotating shaft of the first throttle valve 34, so that the accelerator opening ACCP, that is, the operation. The amount of operation of the accelerator pedal 36 by the person is detected. The second throttle valve 40 provided in the venturi 14 in parallel with the first throttle valve 34 is adjusted by the ECU 51 via the diaphragm mechanism 42 and the negative pressure switching valve 72.
[0033]
The electrical configuration of the ECU 51 will be described with reference to the block diagram of FIG.
The ECU 51 includes a central processing control unit (CPU) 52, a read only memory (ROM) 53 that stores programs and maps necessary for control in advance, a random access memory (RAM) 54 that temporarily stores calculation results of the CPU 52, and the like. A backup RAM 55 for storing stored data and the like, a timer counter 56, an input interface 57, an output interface 58, and the like are provided. Each of the above-described units 52 to 56 is connected to the input interface 57 and the output interface 58 by a bus 59.
[0034]
The above described accelerator sensor 38, the intake pressure sensor 62 for detecting the pressure of intake air downstream from the venturi 14, the water temperature sensor 64 for detecting the engine cooling water temperature THW of the diesel engine 4, and the temperature of the fuel in the distribution type fuel injection pump 28 are determined. The fuel temperature sensor 66 to be detected, the intake air temperature sensor 67 provided in the intake pipe 10 to detect the temperature of intake air, and other sensors are respectively connected via a buffer, a multiplexer, and an A / D converter (not shown). Are connected to the input interface 57.
[0035]
Further, a rotational speed sensor 68 that detects the engine rotational speed ene of the diesel engine 4 from the rotation of the distribution type fuel injection pump 28, a crank position sensor 70 that detects the reference angular position of the crankshaft of the diesel engine 4, a vehicle speed sensor 71, and others These sensors are connected to the input interface 57 via a waveform shaping circuit (not shown). Further, although not shown, a starter switch or the like is directly connected to the input interface 57. Thus, the CPU 52 can read the signals of the respective sensors.
[0036]
Further, the operation of the timing control valve 30, the electromagnetic spill valve 32, and the diaphragm mechanism 42 described above is adjusted by supplying a negative pressure generated by a vacuum pump (not shown) and an atmospheric pressure to thereby adjust the second throttle valve 40. Adjusting the opening of the negative pressure switching valve 72 for adjusting the opening and the opening of the EGR valve 26 according to the supply state of the negative pressure and the atmospheric pressure of the vacuum pump adjusts the recirculation flow rate of the exhaust through the exhaust recirculation pipe 24. Each EVRV 74 is connected to the output interface 58 via a drive circuit (not shown).
[0037]
Therefore, the CPU 52 preferably uses the timing control valve 30, the electromagnetic spill valve 32, the negative pressure switching valve 72, the EVRV 74, and the like via the output interface 58 based on the detection values of the sensors read via the input interface 57 as described above. The driving state of the diesel engine 4 is appropriately controlled.
[0038]
Next, fuel injection timing control among the controls executed by the ECU 51 in the present embodiment will be described. 3 and 4 show a flowchart of the fuel injection timing setting process. This process is executed by a crank angle interruption for each explosion stroke. The steps in the flowchart corresponding to the individual processes are represented by “S˜”.
[0039]
When the processing is started, first, the engine speed ene obtained from the detected value of the rotational speed sensor 68 is read into the working memory in the RAM 54 (S110), and the intake speed obtained from the detected value of the intake pressure sensor 62 is read. The atmospheric pressure epim is read (S120). Further, the cooling water temperature gthw obtained from the detection value of the water temperature sensor 64 is read into the working memory in the RAM 54 (S130), and the intake air temperature gtha obtained from the detection value of the intake air temperature sensor 67 is read (S140). Then, the final fuel injection amount eqfin (corresponding to the engine load) calculated in a separately executed fuel injection amount setting process (not shown) is read into the working memory in the RAM 54 (S150).
[0040]
Next, based on the engine speed ene and the final fuel injection amount eqfin, a basic misfire is calculated from the basic misfire limit injection timing eabsel using the engine speed ene and the final fuel injection amount eqfin shown in FIG. 5 as parameters. The limit injection timing eabsel is calculated (S160). Next, based on the engine speed ene and the intake pressure epim, an intake pressure advance angle correction value is obtained from a two-dimensional map of the intake pressure advance angle correction value eapim using the engine speed ene and the intake pressure epim as parameters shown in FIG. eapim is calculated (S170). Next, based on the engine speed ene and the cooling water temperature gthw, a cold advance angle correction value is obtained from a two-dimensional map of the cold advance angle correction value eacld using the engine speed ene and the cooling water temperature gthw shown in FIG. 7 as parameters. eacld is calculated (S180). Next, based on the engine speed ene and the intake air temperature gtha, an intake air temperature advance correction value is obtained from a two-dimensional map of the intake air temperature advance correction value eatha using the engine speed ene and the intake air temperature gtha as parameters shown in FIG. eatha is calculated (S190).
[0041]
Note that the engine speed ene, the intake pressure epim, the cooling water temperature gthw, and the intake air temperature gtha used as parameters in the processes of steps S170, S180, and S190 correspond to the limit change factors, and the intake pressure advance angle correction calculated respectively. The value eapim, the cold advance angle correction value eacld, and the intake air temperature advance angle correction value eatha correspond to the limit change correction value.
[0042]
The two-dimensional maps of the basic misfire limit injection timing eabsel, the intake pressure advance angle correction value eapim, the cold advance angle correction value eacld, and the intake air temperature advance angle correction value eatha used in steps S160 to S190 are the injection timing and diesel This is set by experiment based on the degree of misfire of the engine 4. For example, the limit of the injection timing at which white smoke is generated from the exhaust is set as the misfire limit.
[0043]
Next, using the intake pressure advance correction value eapim, the cold advance correction value eacld and the intake air temperature advance correction value eatha thus obtained, the basic misfire limit injection timing eabsel is expressed as To correct the misfire limit injection timing A (S200).
[0044]
[Expression 1]
A ← eabsel + eapim + eacld + eata [Formula 1]
Next, based on the engine speed ene and the final fuel injection amount eqfin, the advance angle upper limit guard value eatmx having the engine speed ene and the final fuel injection amount eqfin shown in FIG. An upper limit guard value eatmx is calculated (S210).
[0045]
Next, as in the following expression 2, the smaller one of the advance angle upper guard value eatmx and the misfire limit injection timing A is set as a new misfire limit injection timing B (S220).
[0046]
[Expression 2]
B ← Min (eatmx, A) ... [Formula 2]
Here, Min () represents an operator that extracts the smaller numerical value in parentheses.
[0047]
Next, based on the engine speed ene and the final fuel injection amount eqfin, a warm-time base injection timing eabse using the engine speed ene and the final fuel injection amount eqfin shown in FIG. An intermittent base injection timing eabse is calculated (S230).
[0048]
Next, the larger one of the warm base injection timing eabse and the misfire limit injection timing B is set as the target injection timing eatrg as shown in the following equation (S240).
[0049]
[Equation 3]
eatrg <-Max (eabse, B) ... [Formula 3]
Here, Max () represents an operator that extracts the larger numerical value in parentheses.
[0050]
Thus, the process is temporarily terminated. Henceforth, the process mentioned above is repeated for every control period.
Then, the ECU 51 adjusts the timing control valve 30 to control the actual injection timing to be the target injection timing eatrg obtained as described above.
[0051]
Of the processes executed by the ECU 51 described above, steps S110 to S150 correspond to processes as operating state detection means, step S160 corresponds to processes as basic misfire limit calculation means, and steps S170 to S190 correspond to limit change correction values. Step S200 corresponds to processing as a calculation means, step S200 corresponds to processing as misfire limit injection timing correction means, steps S210 and S220 correspond to processing as advance angle upper limit guard means, and step S230 calculates basic fuel injection timing. Step S240 corresponds to the processing as the fuel injection timing control means.
[0052]
According to the first embodiment described above, the following effects can be obtained.
(I). In the first embodiment, first, in step S160, the basic misfire limit is determined based on the relationship (here, the map shown in FIG. 5) using the engine speed ene and the engine load (here, the final fuel injection amount eqfin) as parameters. The injection timing eabsel is obtained. For this reason, the engine load is reflected in the basic misfire limit injection timing eabsel.
[0053]
Further, with respect to the basic misfire limit injection timing eabsel, the limit changing factors (in this case, the engine speed ene, the intake pressure epim, the cooling water temperature gthw, and the intake air temperature gtha) in the operating state of the diesel engine 4 are used as parameters. Limit change correction values (here, intake pressure advance angle correction value eapim, cold advance angle correction value eacld, and intake air temperature advance angle correction value) obtained based on the relationship (here, the maps shown in FIGS. 6, 7, and 8) The misfire limit injection timing A is obtained by correcting with eta).
[0054]
As a result, as shown in FIG. 11, when the basic fuel injection timing is corrected as in the prior art, an excessive advance angle is obtained. However, in the first embodiment, the setting factor such as emission is a misfire limit injection. Since it is not included in the timing A, the misfire limit injection timing A is not advanced excessively. In addition, it is possible to obtain the misfire limit injection timing A with high accuracy reflecting the engine load.
[0055]
Then, using this misfire limit injection timing A (misfire limit injection timing B when guarded in step S220), as shown on the left side of the point Q in FIG. 11, the basic fuel injection timing (here, When the warm base injection timing eabse) is present behind the misfire limit injection timing A (or B), the actual fuel is obtained by obtaining the target injection timing eatrg based on the misfire limit injection timing A (or B). The injection timing is controlled. Therefore, since the actual fuel injection timing is set at the misfire limit position, misfire can be reliably prevented and an excessive advance angle is not made. Here, the Q point indicates the point at which the basic fuel injection timing (the warm base injection timing ebse) matches the misfire limit injection timing A (or B).
[0056]
Further, as shown on the right side of the point Q in FIG. 11, when the basic fuel injection timing (the warm base injection timing eabse) is on the advance side of the misfire limit injection timing A (or B). The actual fuel injection timing is controlled by obtaining the target injection timing eatrg based on the basic fuel injection timing (the warm base injection timing eabse). In this case, the basic fuel injection timing (warm base injection timing eabse) is advanced from the misfire limit, but the basic fuel injection timing (warm base injection timing eabse) itself is from the viewpoint of preventing misfire. Since the advance angle is not corrected, an excessive advance angle is not made at the actual fuel injection timing.
[0057]
Therefore, in any case, the actual fuel injection timing can be set to an advance angle state that is equal to or greater than the misfire limit, and combustion noise can be suppressed because it does not become an over-advance angle.
[0058]
In the prior art, the basic fuel injection timing (warm base injection timing eabse) is corrected to advance as shown by the broken line in FIG. 11 in order to prevent misfires. Therefore, combustion noise cannot be suppressed.
[0059]
(B). Further, the limit change correction values (intake pressure advance angle correction value eapim, cold advance angle correction value eacld, and intake air temperature advance angle correction value eatha) for obtaining the misfire limit injection timing A are based on a map using the operating state as a parameter. Calculated. Since the map is used in this way, an experimental value suitable for the actual diesel engine 4 can be extracted as the limit change correction value. Thus, it is possible to obtain a limit change correction value that is more suitable for the actual diesel engine 4 than the theoretical value, and it is possible to perform precise control that is more suitable for actual use.
[0060]
(C). In step S220, if the misfire limit injection timing A is more advanced than the advance angle upper limit guard value eatmx, the advance angle upper limit guard value eatmx is reset as the misfire limit injection timing B. This advance angle upper limit guard value eatmx is provided to prevent the injection timing from becoming an excessive advance angle which is a problem in protecting the diesel engine 4.
[0061]
Thus, it is possible to prevent the misfire limit injection timing B from becoming an excessive advance angle which causes a problem in protecting the diesel engine 4. Therefore, it is possible to prevent the excessively advanced target injection timing eatrg from being set in step S240, which is a problem in protecting the diesel engine 4, and to protect the diesel engine 4.
[0062]
(D). Further, the advance angle upper limit guard value eatmx is obtained from a two-dimensional map according to the operating state of the diesel engine (here, the engine speed ene and the final fuel injection amount eqfin).
[0063]
Thus, by setting the advance angle upper limit guard value according to the operating state of the diesel engine, a more precise advance angle upper limit guard becomes possible.
[Other embodiments]
In the first embodiment, each of the two dimensions of the basic misfire limit injection timing eabsel, the intake pressure advance angle correction value eapim, the cold advance angle correction value eacld, and the intake air temperature advance angle correction value eatha shown in FIGS. The map is set by experiments based on the injection timing and the degree of white smoke generation. Besides this, the limit of the injection timing at which the rotational fluctuation of the diesel engine 4 becomes large may be set as the misfire limit. The map may be created by measuring other physical quantities that reflect the degree of misfire.
[0064]
In the first embodiment, the distribution type fuel injection pump 28 is used for fuel injection, but in addition to this, a row type fuel injection pump, a pressure accumulation type fuel injection device, and the like can be used.
[0065]
【The invention's effect】
In the fuel injection timing control device for a diesel engine according to claim 1,Using misfire limit as a setting factorThe basic misfire limit injection timing is obtained based on the relationship between engine speed and engine load as parameters.In this case, this is determined independently of the basic fuel injection timing.. . Therefore, the engine load is reflected in the basic misfire limit injection timing. Then, the misfire limit injection timing is obtained by correcting the basic misfire limit injection timing with a limit change correction value obtained on the basis of the relationship using the limit change factor in the operating state of the diesel engine as a parameter. As a result, the misfire limit injection timing does not include setting factors such as emissions as in the case where the basic fuel injection timing is corrected in the prior art, and the misfire limit injection timing should be calculated with high accuracy reflecting the engine load. Can do. The misfire limit injection timing is used to control the actual fuel injection timing based on the misfire limit injection timing when the basic fuel injection timing is on the retard side of the misfire limit injection timing. As a result, the actual fuel injection timing is set at the misfire limit position, so that misfire can be surely prevented and an excessive advance is not made. Also,Emission is required as a setting factorWhen the basic fuel injection timing is on the more advanced side than the misfire limit injection timing, the actual fuel injection timing is controlled based on the basic fuel injection timing. In this case, the basic fuel injection timing is advanced from the misfire limit, but the basic fuel injection timing itself is not corrected for advancement from the viewpoint of misfire prevention. No advance is made. Therefore, the actual fuel injection timing can be controlled to an advance angle state that is equal to or greater than the misfire limit, and combustion noise can be suppressed because it does not become an excessive advance angle.
[0066]
In the fuel injection timing control device for a diesel engine according to claim 2, the basic misfire limit calculation means includes:Using misfire limit as a setting factorBased on the relationship between engine speed and engine load as parametersIndependent of basic fuel injection timingObtain the basic misfire limit injection timing. Then, the limit change correction value calculation means obtains the limit change correction value based on the relationship using the limit change factor in the operating state of the diesel engine as a parameter. The misfire limit injection timing correcting means corrects the basic misfire limit injection timing with the limit change correction value to obtain the misfire limit injection timing. Accordingly, it is possible to obtain a misfire limit injection timing with high accuracy that does not include setting factors such as emissions in the case of the prior art in which the basic fuel injection timing is corrected and reflects the engine load. Then, the fuel injection timing control means compares the misfire limit injection timing with the basic fuel injection timing, and if the basic fuel injection timing is retarded than the misfire limit injection timing, the fuel injection timing control means Based on this, the actual fuel injection timing is controlled. As a result, the actual fuel injection timing is set at the misfire limit position, so that misfire can be surely prevented and an excessive advance is not made. Also, the fuel injection timing control means is more effective than the misfire limit injection timing.Emission is required as a setting factorWhen the basic fuel injection timing is on the advance side, the actual fuel injection timing is controlled based on the basic fuel injection timing. In this case, although the basic fuel injection timing is advanced from the misfire limit, the basic fuel injection timing itself is not corrected for advancement from the viewpoint of preventing misfire, so the actual fuel injection timing is excessively advanced. No corners are made. Therefore, as in the first aspect, the actual fuel injection timing can be controlled to an advanced angle state that is equal to or greater than the misfire limit, and combustion noise can be suppressed because the actual fuel injection timing does not become an excessive angle.
[0067]
In the fuel injection timing control device for a diesel engine according to claim 3, in the configuration according to claim 2, the limit changing factor is one or more selected from intake pressure, cooling water temperature, and intake air temperature. Value and engine speed. As described above, by using one or more values selected from the intake pressure, the coolant temperature and the intake air temperature, and the engine speed as the limit change factor, the optimum limit change adapted to the operating state of the diesel engine is achieved. A correction value can be obtained. For this reason, by using the misfire limit injection timing obtained by being corrected by the limit change correction value, in addition to the function and effect of the second aspect, more precise control becomes possible.
[0068]
According to a fourth aspect of the present invention, in the fuel injection timing control device for a diesel engine, the limit change correction value calculating means, based on a map using the limit change factor as a parameter, is based on the configuration according to the second or third aspect. The limit change correction value is obtained. Thus, since the limit change correction value can be obtained from the map that can reflect the experimental data, in addition to the operational effect of the second or third aspect, precise control that is more practically adapted can be realized.
[0069]
The fuel injection timing control device for a diesel engine according to claim 5 includes an advance angle upper limit guard means in addition to the structure according to any one of claims 2 to 4. This advance angle upper limit guard means has the misfire limit injection timing obtained by the misfire limit injection timing correction means,To prevent excessive advance angle, which is a problem for the protection of diesel enginesIf the advance angle is higher than the advance angle upper guard value, the misfire limit injection timing is reset based on the advance angle upper guard value.. ThisThus, in addition to the operation and effect of any one of claims 2 to 4, it is possible to prevent the misfire limit injection timing from becoming an excessive advance angle which causes a problem in protecting the diesel engine. For this reason, it is possible to prevent the fuel injection timing control means from setting an excessively advanced injection timing which is a problem in protecting the diesel engine in the actual fuel injection timing, thereby protecting the diesel engine.
[0070]
In the fuel injection timing control device for a diesel engine according to claim 6, in the configuration according to claim 5, the advance angle upper limit guard means detects the advance angle upper limit guard value by the operating state detection means. It is determined to be determined according to the operating state of the diesel engine. In this way, by setting the advance angle upper limit guard value according to the operating state of the diesel engine, in addition to the effect of the fifth aspect, a more precise advance angle upper limit guard becomes possible.
[0071]
In the fuel injection timing control device for a diesel engine according to claim 7, in the configuration according to claim 6, the advance angle upper limit guard means detects the advance angle upper limit guard value by the operating state detection means. The engine speed is determined according to the engine speed and the engine load in the operating state of the diesel engine. Specifically, by obtaining the advance angle upper limit guard value in this way, the operational effect of claim 6 can be produced.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a schematic configuration of a diesel engine control apparatus according to a first embodiment.
FIG. 2 is a block diagram showing an electrical configuration of an ECU used in the first embodiment.
FIG. 3 is a flowchart showing a fuel injection timing control process executed by the ECU in the first embodiment.
FIG. 4 is a flowchart showing a fuel injection timing control process executed by the ECU in the first embodiment.
FIG. 5 is an explanatory diagram of a basic misfire limit injection timing map used in the fuel injection timing control process.
FIG. 6 is a configuration explanatory diagram of an intake pressure advance correction value map used in the fuel injection timing control process.
FIG. 7 is a diagram illustrating the configuration of a cold advance correction value map used in the fuel injection timing control process.
FIG. 8 is a diagram illustrating the configuration of an intake air temperature advance correction value map used in the fuel injection timing control process.
FIG. 9 is a diagram illustrating the configuration of an advance angle upper limit guard value map used in the fuel injection timing control process.
FIG. 10 is a diagram illustrating the configuration of a warm-time base injection timing map used in the fuel injection timing control process.
FIG. 11 is a graph showing effects in the first embodiment.
[Explanation of symbols]
2 ... Diesel engine control device, 4 ... Diesel engine, 6 ... Turbocharger, 8 ... Air cleaner, 10 ... Intake pipe, 12 ... Intercooler, 14 ... Venturi, 16 ... Cylinder, 18 ... Combustion chamber, 20 ... Fuel injection valve, DESCRIPTION OF SYMBOLS 22 ... Exhaust pipe, 24 ... Exhaust gas recirculation pipe, 26 ... EGR valve, 28 ... Distribution type fuel injection pump, 30 ... Timing control valve, 32 ... Electromagnetic spill valve, 34 ... First throttle valve, 36 ... Accelerator pedal, 38 ... Accelerator sensor, 40 ... second throttle valve, 42 ... diaphragm mechanism, 51 ... electronic control unit (ECU), 52 ... central processing control unit (CPU), 53 ... read only memory (ROM), 54 ... random access memory (RAM) ), 55 ... Backup RAM, 56 ... Timer counter, 57 ... Input interface, 58 ... Force interface 59 ... Bus 62 ... Intake pressure sensor 64 ... Water temperature sensor 66 ... Fuel temperature sensor 67 ... Intake temperature sensor 68 ... Rotation speed sensor 70 ... Crank position sensor 71 ... Vehicle speed sensor 72 ... Negative Pressure switching valve, 74 ... Electric negative pressure regulating valve (EVRV).

Claims (7)

In a fuel injection timing control device for a diesel engine that performs fuel injection timing control according to the operating state of the diesel engine,
While determining the basic fuel injection timing based on the operating condition of the diesel engine with emission as a setting factor , based on the relationship between the engine speed and the engine load in the operating condition of the diesel engine with the misfire limit as a setting factor When determining the basic misfire limit injection timing, the basic misfire limit injection timing is determined independently of the basic fuel injection timing, and the basic misfire limit injection timing is determined based on a relationship that uses a limit change factor in the operating state of the diesel engine as a parameter. corrected by the limiting changed correction value seeking misfire limit fuel injection timing, the basic fuel injection timing is the misfire actual fuel injection timing based on the misfire limit fuel injection timing when present retarded than the limit injection timing When the basic fuel injection timing is on the advance side of the misfire limit injection timing, the basic fuel injection time Fuel injection timing control device for a diesel engine and controlling the actual fuel injection timing based on. In a fuel injection timing control device for a diesel engine that performs fuel injection timing control according to the operating state of the diesel engine,
Driving state detecting means for detecting the driving state of the diesel engine;
Basic fuel injection timing calculating means for obtaining basic fuel injection timing according to the operating state of the diesel engine detected by the operating state detecting means with emission as a setting factor;
Based on the relationship between the engine speed and the engine load in the operating state of the diesel engine detected by the operating state detection means using the misfire limit as a setting factor, independently of the basic fuel injection timing. A basic misfire limit calculating means for obtaining a basic misfire limit injection timing;
Limit change correction value calculating means for obtaining a limit change correction value based on a relationship using as a parameter a limit change factor in the operating state of the diesel engine detected by the operating state detecting means;
Misfire limit injection timing correction for determining the misfire limit injection timing by correcting the basic misfire limit injection timing obtained by the basic misfire limit calculation means with the limit change correction value obtained by the limit change correction value calculation means. Means ,
The misfire limit injection timing determined by the misfire limit injection timing correction means and the basic fuel injection timing determined by the basic fuel injection timing calculation means are compared, and the basic fuel is more than the misfire limit injection timing. When the injection timing is on the retard side, the actual fuel injection timing is controlled based on the misfire limit injection timing, and the basic fuel injection timing is on the advance side with respect to the misfire limit injection timing Includes fuel injection timing control means for controlling the actual fuel injection timing based on the basic fuel injection timing;
A fuel injection timing control device for a diesel engine, comprising: 3. The fuel injection timing control device for a diesel engine according to claim 2, wherein the limit changing factor is one or more values selected from an intake air pressure, a coolant temperature, and an intake air temperature and an engine speed. The fuel injection timing control device for a diesel engine according to claim 2 or 3, wherein the limit change correction value calculation means obtains the limit change correction value based on a map having the limit change factor as a parameter. In addition to the configuration according to any one of claims 2 to 4,
When the fuel injection timing control means controls the actual fuel injection timing based on the misfire limit injection timing,
The misfire limit injection timing obtained by the misfire limit injection timing correcting means is on the advance side with respect to the advance angle upper limit guard value for preventing the misfire limit injection timing from becoming an excessive advance angle state which is a problem in protecting the diesel engine. In this case, the fuel injection timing control device for a diesel engine is provided with an advance upper limit guard means for resetting the misfire limit injection timing based on the advance upper limit guard value. 6. The fuel injection of a diesel engine according to claim 5, wherein the advance angle upper limit guard means obtains the advance angle upper limit guard value according to the operating state of the diesel engine detected by the operating state detecting means. Timing control device. The advance angle upper limit guard means obtains the advance angle upper limit guard value according to the engine speed and the engine load in the operating state of the diesel engine detected by the operating state detecting means. The fuel injection timing control device for a diesel engine according to claim 6.

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