JP2005048609A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately determine existence or nonexistence of combustion failure in a combustion chamber of an internal combustion engine. <P>SOLUTION: A control device for an internal combustion engine comprises: a cylinder pressure detection means 47 detecting pressure in the combustion chamber 5 of the internal combustion engine; a calculation means calculating the product PV of pressure in the combustion chamber detected by the cylinder pressure detection means and a capacity of the combustion chamber; a timing detection means detecting timing CAp in which the product calculated by the calculation means becomes maximum as peak timing; and a combustion failure determination means determining the existence or nonexistence of the combustion failure in the combustion chamber based on the peak timing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for an internal combustion engine.
[0002]
[Prior art]
A control apparatus for an internal combustion engine that increases the air-fuel ratio of an air-fuel mixture in a combustion chamber when it is detected that a misfire (that is, a state in which fuel does not combust) has occurred in the combustion chamber of the internal combustion engine. Is disclosed. In the control device described in Patent Document 1, it is determined that misfire has occurred when the difference between the two peaks of the in-cylinder pressure (that is, the pressure in the combustion chamber) becomes negative. That is, in the internal combustion engine described in Patent Document 1, the in-cylinder pressure reaches the first peak near the compression top dead center due to the compression of the air-fuel mixture by the piston. After that, if combustion is performed without misfire, the in-cylinder pressure reaches a second peak higher than the first peak due to this combustion. Therefore, in the control device described in Patent Document 1, the in-cylinder pressure is detected as the first in-cylinder pressure at the timing when the in-cylinder pressure is expected to reach the first peak, and the in-cylinder pressure is expected to reach the second peak. The in-cylinder pressure is detected as the second in-cylinder pressure at the timing. Here, if the combustion is performed without causing misfire, the difference between the first in-cylinder pressure and the second in-cylinder pressure (= second in-cylinder pressure−first in-cylinder pressure) should be a positive value. If this difference is positive, it is determined that no misfire has occurred. On the other hand, if misfire has occurred, the second peak does not appear after the first peak, and the in-cylinder pressure decreases after the first peak. Therefore, the above difference becomes a negative value. If it is negative, it is determined that misfire has occurred.
[0003]
[Patent Document 1]
JP 11-93748 A
[Patent Document 2]
Japanese Patent Laid-Open No. 9-68081
[Patent Document 3]
JP-A-2-23255
[Patent Document 4]
Japanese Patent Laid-Open No. 7-247883
[0004]
[Problems to be solved by the invention]
As described above, in the control device described in Patent Document 1, the presence or absence of misfire is determined based only on the in-cylinder pressure. However, such a determination method has room for improvement in order to further improve the determination accuracy. That is, in the control device described in Patent Document 1, the second in-cylinder pressure is detected at a timing at which the second peak is expected to appear, but the second peak does not necessarily appear at this timing. For example, if the fuel ignition timing is earlier or later than the predicted timing, the second peak does not always appear at the predicted timing. In this case, it is determined that misfire has occurred despite the combustion being performed. Also, for example, even if the fuel ignites at the expected time, if the fuel does not burn at a time and burns relatively slowly, the second peak does not always appear at the expected timing. There is a possibility that the peak 2 itself does not appear.
[0005]
In any case, there is room for improvement in order to further improve the determination accuracy in the method of determining the presence or absence of misfire based on only the in-cylinder pressure as in the control device described in Patent Document 1.
[0006]
In the field of control devices for internal combustion engines, it is meaningful not only to determine whether misfire has occurred, but also to determine whether there is a combustion delay. That is, in the field of control devices for internal combustion engines, there is also a demand for determining whether there is a combustion failure such as misfire or combustion delay.
[0007]
Accordingly, an object of the present invention is to more accurately determine whether or not there is a combustion failure in a combustion chamber of an internal combustion engine.
[0008]
[Means for Solving the Problems]
In order to solve the above problem, in a first aspect of the invention, an in-cylinder pressure detecting means for detecting a pressure in a combustion chamber of an internal combustion engine, a pressure in the combustion chamber detected by the in-cylinder pressure detecting means and a volume of the combustion chamber In a control device for an internal combustion engine comprising a calculating means for calculating a product, a timing detecting means for detecting, as a peak timing, a timing at which a product calculated by the calculating means is maximum, and a combustion chamber based on the peak timing. Combustion failure determination means for determining the presence or absence of combustion failure.
In the second invention, in the first invention, the combustion failure determination means determines that the combustion failure in the combustion chamber is a misfire when the peak timing is earlier than the top dead center of the engine compression stroke.
According to a third aspect, in the first aspect, the timing detection means detects, as a reference timing, a timing at which a product calculated by the calculation means becomes maximum when combustion is not performed in the combustion chamber, and the combustion The failure determination means determines that the combustion failure in the combustion chamber is misfire when the peak timing is near the reference timing.
According to a fourth aspect of the invention, there is provided control means for controlling the timing of injecting fuel from the fuel injection valve so that the peak timing becomes the target timing in the second or third aspect of the invention, and the control means comprises the combustion failure. When the determination means determines that the combustion failure in the combustion chamber is misfire, the timing at which fuel is injected from the fuel injection valve is controlled so that the timing later than the peak timing becomes the target timing.
According to a fifth aspect, in the second or third aspect, the internal combustion engine is provided with exhaust introduction means for reintroducing exhaust gas discharged from the combustion chamber into the combustion chamber, and the control device has the peak timing as a target timing. And a control means for controlling the amount of exhaust gas reintroduced into the combustion chamber by the exhaust introduction means so that the control means determines that the combustion failure in the combustion chamber is misfiring by the combustion failure determination means. When the determination is made, the amount of exhaust gas reintroduced into the combustion chamber by the exhaust introduction means is controlled so that the timing later than the peak timing becomes the target timing.
According to a sixth aspect, in the first aspect, the combustion failure determination means has a combustion failure in the combustion chamber that the peak timing is a timing later than a predetermined timing that is later than the top dead center of the engine compression stroke. Is determined to be a combustion delay.
In order to solve the above problems, in a seventh aspect of the invention, the in-cylinder pressure detecting means for detecting the pressure in the combustion chamber of the internal combustion engine, the pressure in the combustion chamber detected by the in-cylinder pressure detecting means and the volume of the combustion chamber A control device for an internal combustion engine comprising a calculation means for calculating a product, further comprising a combustion failure determination means for determining the presence or absence of a combustion failure in the combustion chamber based on the product calculated by the calculation means.
In an eighth aspect based on the seventh aspect, the combustion failure determination means determines that the combustion failure in the combustion chamber is misfiring when the product calculated by the calculation means is substantially zero.
According to a ninth aspect, in the eighth aspect, the timing detecting means for detecting the timing at which the product calculated by the calculating means is maximum as a peak timing, and the fuel injection valve so that the peak timing becomes a target timing. Control means for controlling the timing at which fuel is injected, and the control means determines that a timing later than the peak timing is the target time when the combustion failure determination means determines that the combustion failure in the combustion chamber is misfiring. The timing for injecting fuel from the fuel injection valve is controlled so as to be the timing.
According to a tenth aspect, in the eighth aspect, the internal combustion engine includes exhaust introduction means for reintroducing the exhaust gas discharged from the combustion chamber into the combustion chamber, and the control device has the peak timing as a target timing. The control means further controls the amount of exhaust gas re-introduced into the combustion chamber by the exhaust introduction means, and the control means determines that the combustion failure in the combustion chamber is misfiring by the combustion failure determination means. In this case, the amount of exhaust gas reintroduced into the combustion chamber by the exhaust introduction means is controlled so that the timing later than the peak timing becomes the target timing.
According to an eleventh aspect, in the seventh aspect, the combustion failure determination means determines that the combustion failure in the combustion chamber is a combustion delay when the product calculated by the calculation means is smaller than a predetermined value. .
According to a twelfth aspect, in any one of the first to eleventh aspects, the combustion improving means for improving the combustion in the combustion chamber when the combustion failure determination means determines that the combustion in the combustion chamber is defective. In addition.
In a thirteenth aspect based on the twelfth aspect, the control means for controlling the amount of fuel injected from the fuel injection valve by the combustion improving means, the control means for controlling the timing at which fuel is injected from the fuel injection valve, and the combustion And at least one control means for controlling the amount of exhaust gas discharged from the chamber and reintroduced into the combustion chamber. The control means determines that the combustion in the combustion chamber is defective by the combustion failure determination means. A reduction in the amount of fuel injected from the fuel injection valve, an advance angle of timing for injecting fuel from the fuel injection valve, a reduction in the amount of exhaust gas discharged from the combustion chamber and reintroduced into the combustion chamber, Perform at least one of the following:
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an overall view of a four-cylinder four-stroke compression ignition type internal combustion engine. In FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a cylinder head, 4 is a piston, 5 is a combustion chamber, 6 is an electrically controlled fuel injection valve, 7 is an intake valve, 8 is an intake port, and 9 is Exhaust valves and 10 indicate exhaust ports, respectively. The fuel injection valve 6 is opened when electric power is supplied thereto, whereby fuel is injected from the fuel injection valve 6. Then, by controlling the time for supplying power to the fuel injection valve 6 (hereinafter referred to as “energization time”), the time during which the fuel injection valve 6 is open is controlled. The amount of fuel (hereinafter referred to as “fuel injection amount”) is controlled.
[0010]
The intake port 8 is connected to the surge tank 12 via a corresponding intake branch pipe 11. The surge tank 12 is connected to the air cleaner 14 via the intake duct 13. A throttle valve 16 driven by a step motor 15 is disposed in the intake duct 13. On the other hand, the exhaust port 10 is connected via an exhaust branch pipe 17 and an exhaust pipe 18 to a catalytic converter 20 containing a catalyst 19 having an oxidation function. An air-fuel ratio sensor 21 is attached to the exhaust branch pipe 17.
[0011]
The exhaust branch pipe 17 and the surge tank 12 are connected to each other via an exhaust gas recirculation (hereinafter referred to as “EGR”) passage 22. A part of the exhaust gas discharged from the combustion chamber 5 to the exhaust port 10 is introduced into the surge tank 12 via the EGR passage 22 and finally introduced into the combustion chamber 5. An electrically controlled EGR control valve 23 is disposed in the EGR passage 22. By controlling the opening degree of the EGR control valve 23 (hereinafter referred to as “EGR opening degree”), the amount of exhaust gas introduced into the combustion chamber 5 is controlled. Further, around the EGR passage 22, a cooling device 24 for cooling the exhaust gas flowing in the EGR passage 22 (hereinafter also referred to as “EGR gas”) is disposed. Cooling water for cooling the internal combustion engine is guided into the cooling device 24.
[0012]
On the other hand, the fuel injection valve 6 is connected to a so-called common rail 26 through a fuel supply pipe 25. Fuel is supplied into the common rail 26 from an electrically controlled fuel pump 27 with variable discharge amount. The fuel supplied into the common rail 26 is supplied to the fuel injection valve 6 through the fuel supply pipe 25. A fuel pressure sensor 28 for detecting the pressure of the fuel in the common rail 26 (hereinafter referred to as “fuel pressure”) is attached to the common rail 26. Based on the output signal of the fuel pressure sensor 28, the discharge amount of the fuel pump 27 is controlled so that the fuel pressure in the common rail 26 becomes the target pressure.
[0013]
The electronic control unit 30 comprises a digital computer and is connected to each other by a bidirectional bus 31. A ROM (read only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, an input port 35, and an output A port 36 is provided. The output signal of the air-fuel ratio sensor 21 is input to the input port 35 via the corresponding AD converter 37. The output signal of the fuel pressure sensor 28 is also input to the input port 35 via the corresponding AD converter 37. A water temperature sensor 29 for detecting the temperature of cooling water for cooling the internal combustion engine is attached to the engine body 1. The output signal of the temperature sensor 29 is input to the input port 35 via the corresponding AD converter 37.
[0014]
A temperature sensor 46 for detecting the temperature of the exhaust gas that has passed through the catalyst 19 is disposed in the exhaust pipe 45 downstream of the catalyst 19. The output signal of the temperature sensor 46 is input to the input port 35 via the corresponding AD converter 37.
[0015]
The cylinder head 3 is provided with an in-cylinder pressure sensor 47 for detecting the pressure in the combustion chamber 5 (hereinafter referred to as “in-cylinder pressure”). The output signal of the in-cylinder pressure sensor 47 is input to the input port 35 via the corresponding AD converter 37.
[0016]
The accelerator pedal 40 is connected to a load sensor 41 that generates an output voltage proportional to the depression amount L of the accelerator pedal 40. The output voltage of the load sensor 41 is input to the input port 35 via the corresponding AD converter 37. Further, a crank angle sensor 42 that generates an output pulse every time the crankshaft 49 rotates, for example, 30 ° is connected to the input port 35. On the other hand, the output port 36 is connected to the fuel injection valve 6, the step motor 15, the EGR control valve 23, and the fuel pump 27 via a corresponding drive circuit 38.
[0017]
Next, control related to the operation of the fuel injection valve will be described. Parameters controlled with respect to the operation of the fuel injection valve include a fuel injection amount and a timing at which fuel is injected from the fuel injection valve (hereinafter referred to as “injection timing”). First, control of the fuel injection amount will be described.
[0018]
In the present embodiment, an optimal fuel injection amount for the operating state of the internal combustion engine (hereinafter referred to as “engine operating state”) is obtained in advance by experiments or the like, and the engine speed N and the required load are determined using these fuel injection amounts as target fuel injection amounts TQ. A function with L is stored in advance in the ROM 32 in the form of a map as shown in FIG. During engine operation, the target fuel injection amount TQ is read from the map of FIG. 2 based on the engine speed N and the required load L. Furthermore, in the present embodiment, the energization time with the fuel injection amount as the target fuel injection amount TQ is defined as a basic energization time ΤBase in the form of a map as shown in FIG. Remember. In the map of FIG. 3, the basic energization time ΤBase increases as the target fuel injection amount TQ increases. During engine operation, the basic energization time AUbase is read from the map of FIG. 3 based on the target fuel injection amount TQ.
[0019]
Here, if the fuel injection valve 6 operates as scheduled, the fuel injection amount should be the target fuel injection amount by supplying power to the fuel injection valve 6 for the basic energization time ＵBase. However, actually, even if power is supplied to the fuel injection valve 6 for the basic energization time ｂBase due to the manufacturing error of the fuel injection valve 6 and deterioration over time, the fuel injection amount is not always the target fuel injection amount. Absent. Therefore, in the present embodiment, the final target valve opening time ΤAU is calculated according to the following equation (1).
ΤAU = ΤAUbase × Ki (1)
Although details will be described later, Ki used in the above equation (1) is a coefficient for setting the fuel injection amount to the target fuel injection amount based on a parameter related to the amount of fuel actually burned in the combustion chamber 5. It is. In any case, by supplying electric power to the fuel injection valve 6 for the target valve opening time ΤAU calculated according to the above equation (1), fuel of the target fuel injection amount is injected from the fuel injection valve 6.
[0020]
In the present embodiment, the basic energization time ｂBase is stored in advance in the ROM 32 as a function of the target fuel injection amount TQ. However, the engine speed N and the required engine energization time Τbase are associated with each target fuel injection amount TQ. It may be stored in advance in the ROM 32 as a function of the load L. In this case, the basic energization time ΤBase is directly read based on the engine speed N and the required load L during engine operation.
[0021]
Next, a method for calculating the coefficient Ki used in the above equation (1) will be described with reference to FIG. In FIG. 4, the horizontal axis CA is the crank angle, and the vertical axis PV is the product of the in-cylinder pressure P and the volume of the combustion chamber 5 (hereinafter referred to as “in-cylinder volume”) V (hereinafter referred to as “PV value”). is there. In FIG. 4, TDC is the top dead center of the compression stroke (hereinafter referred to as “compression top dead center”). In FIG. 4, the solid line indicates the change in PV value when combustion is performed in the combustion chamber 5, and the chain line is when combustion is not performed in the combustion chamber 5 (that is, the piston 4 The change in PV value when the air-fuel mixture in the combustion chamber 5 is only compressed / expanded due to the vertical movement of is shown.
[0022]
As indicated by the chain line in FIG. 4, when the combustion is not performed in the combustion chamber 5 and therefore only the compression / expansion of the air-fuel mixture in the combustion chamber 5 due to the vertical movement of the piston 4 is performed, the PV value is The crank angle CA gradually increases as it approaches the compression top dead center TDC. The PV value peaks when the crank angle CA reaches the compression top dead center TDC, and then gradually decreases. In this case, the change curve of the PV value indicated by a chain line is symmetric with respect to the compression top dead center TDC.
[0023]
On the other hand, as shown by the solid line in FIG. 4, when combustion is performed in the combustion chamber 5, the PV value gradually increases as the crank angle CA approaches the compression top dead center TDC. The PV value peaks when the crank angle CA reaches the compression top dead center TDC. The change in the PV value so far is the same as the change in the PV value when combustion is not performed in the combustion chamber 5. However, when the crank angle CA passes the compression top dead center TDC, the PV value slightly decreases, but the fuel injected into the combustion chamber 5 from the fuel injection valve 6 (for example, this fuel is just before the compression top dead center TDC. When the combustion of (injected at the timing) starts, the PV value rises at a stretch. And PV value reaches a peak again. In the following description, the crank angle (CAp in FIG. 4) when the PV value reaches the peak again is referred to as peak timing, and the PV value (PVmax in FIG. 4) at that time is referred to as the maximum PV value. The PV value decreases at a stroke after reaching the maximum PV value.
[0024]
Here, the difference between the maximum PV value (PVmax in FIG. 4) and the PV value at the time of motoring at the peak timing CAp (PVbase in FIG. 4) (ΔPV in FIG. 4, hereinafter referred to as “ΔPV” or “PV difference”) ) Is mainly generated from the combustion heat of the fuel in the combustion chamber 5. This combustion heat should be approximately proportional to the amount of fuel burned in the combustion chamber 5. Therefore, ΔPV is a parameter representing the amount of fuel combusted in the combustion chamber 5 (that is, the actual fuel injection amount). In other words, the actual fuel injection amount can be known from ΔPV. Further, if ΔPV is used, a coefficient for correcting the energization time so that the actual fuel injection amount becomes the target fuel injection amount (this coefficient is the coefficient Ki used in the above equation (1)). Can be sought.
[0025]
Therefore, in the present embodiment, ΔPV when the fuel injection amount is the target fuel injection amount is obtained in advance by experiments or the like, and the ΔPV is set as the target ΔPV as shown in FIG. 5 as a function of the target fuel injection amount TQ. It is stored in advance in the ROM 32 in the form of a map. In the map of FIG. 5, the target ΔPV increases as the target fuel injection amount TQ increases. During engine operation, the target ΔPV is read from the map of FIG. 5 based on the target fuel injection amount TQ. Then, ΔPV is calculated for each expansion stroke, and the calculated ΔPV is compared with the target ΔPV.
[0026]
Here, when ΔPV is smaller than the target ΔPV, the fuel injection amount is smaller than the target fuel injection amount. Therefore, the coefficient Ki is increased so that the energization time becomes longer. In this case, the coefficient Ki is increased by a predetermined value (this may be a constant value or a value that increases in proportion to the difference between ΔPV and the target ΔPV) as shown in the following equation (2): ΔKii Or a predetermined ratio (this is a value larger than 1.0 and may be a constant value or proportional to the difference between ΔPV and the target ΔPV, as shown in the following equation (3). The value may be increased by Rii).
Ki = Ki + ΔKii (2)
Ki = Ki × Rii (3)
In the above formulas (2) and (3), Ki on the right side is the current coefficient, and Ki on the left side is a coefficient that is newly updated this time and used next time.
According to this, the target energization time ΤAU calculated according to the above equation (1) becomes longer, and therefore the fuel injection amount is increased, so that the fuel injection amount becomes the target fuel injection amount, or at least the target fuel injection amount. It will approach the amount.
[0027]
On the other hand, when ΔPV is larger than the target ΔPV, the fuel injection amount is larger than the target fuel injection amount. Therefore, the coefficient Ki is reduced so that the energization time is shortened. In this case, the coefficient Ki is reduced by a predetermined value (this may be a constant value or a value that increases in proportion to the difference between ΔPV and the target ΔPV), as shown in the following equation (4): ΔKid Or a predetermined ratio (this is a value smaller than 1.0 and may be a constant value or proportional to the difference between ΔPV and the target ΔPV, as shown in the following equation (5). (It may be a smaller value) Rid may be smaller.
Ki = Ki−ΔKid (4)
Ki = Ki × Rid (5)
Also in the above equations (4) and (5), Ki on the right side is the current coefficient, and Ki on the left side is a coefficient that is newly updated this time and used next time.
According to this, the target energization time ΤAU calculated according to the above equation (1) is shortened, and therefore the fuel injection amount is reduced, so that the fuel injection amount becomes the target fuel injection amount, or at least the target fuel injection amount. It will approach the amount.
[0028]
Next, injection timing control will be described. In the present embodiment, the optimal injection timing for the engine operating state (specifically, the injection timing at which the peak timing (CAp in FIG. 4) becomes a predetermined timing) is obtained in advance by experiments or the like, and these injection timings are determined as basic injection. The timing TTbase is stored in advance in the ROM 32 in the form of a map as shown in FIG. 6 as a function of the engine speed N and the required load L. During engine operation, the basic injection timing TTbase is read from the map of FIG. 6 based on the engine speed N and the required load L.
[0029]
Here, if the fuel injection valve 6 operates as planned, the peak timing (CAp in FIG. 4) should be the target timing by supplying power to the fuel injection valve 6 at the basic injection timing TTbase. . However, actually, even if power is supplied to the fuel injection valve 6 at the basic injection timing TTbase due to the manufacturing error of the fuel injection valve 6 and deterioration with time, the peak timing CAp is set at a predetermined target timing. Not necessarily. Therefore, in the present embodiment, the final target injection timing TT is calculated according to the following equation (6).
TT = TTbase × Kt (6)
Although details will be described later, Kt used in the above (6) is a coefficient for setting the peak timing to the target timing. In any case, power is supplied to the fuel injection valve 6 at the target injection timing TT calculated according to the above equation (6), so that the peak timing becomes the target timing.
[0030]
Next, a method for calculating the coefficient Kt used in the above equation (6) will be described. As described above, the optimal injection timing for the engine operating state is a timing at which the peak timing (CAp in FIG. 4) becomes a predetermined timing. Here, as a general tendency, if the injection timing is advanced, the peak timing is also advanced, and conversely, if the injection timing is delayed, the peak timing is also delayed. Therefore, when the peak timing is later than the predetermined timing, the peak timing approaches the predetermined timing if the injection timing is advanced (that is, if the injection timing is advanced). Conversely, when the peak timing is earlier than the predetermined timing, if the injection timing is retarded (that is, delayed), the peak timing approaches the predetermined timing.
[0031]
Therefore, in the present embodiment, the optimum peak timing for the engine operating state is obtained in advance by experiments or the like, and the peak timing is set as a target peak timing TCAp as a function of the engine speed N and the required load L as shown in FIG. It is stored in advance in the ROM 32 in the form of a simple map. During engine operation, the target peak timing TCAp is read from the map of FIG. 7 based on the engine speed N and the required load L. Then, the peak timing is detected for each expansion stroke, and the detected peak timing is compared with the target peak timing TCAp.
[0032]
Here, when the detected actual peak timing CAp is earlier than the target peak timing TCAp, since the injection timing is earlier than the target injection timing, the coefficient Kt is increased. In this case, the coefficient Kt may be a predetermined value (this may be a constant value or a value that increases in proportion to the difference between the actual peak timing and the target peak timing, as shown in the following equation (7). ) ΔKti may be increased, or as shown in the following equation (8), a predetermined ratio (this is a value larger than 1.0 and may be a constant value, or the actual peak timing and target (It may be a value that increases in proportion to the difference from the peak timing.) It may be increased by Rti.
Kt = Kt + ΔKti (7)
Kt = Kt × Rti (8)
In the above equations (7) and (8), Kt on the right side is the current coefficient, and Kt on the left side is the coefficient that is newly updated this time and is used next time.
According to this, since the final target injection timing TT calculated according to the above equation (6) is delayed, the actual peak timing becomes the target peak timing, or at least approaches the target peak timing.
[0033]
On the other hand, when the actual peak timing CAp is later than the target peak timing TCAp, since the injection timing is later than the target injection timing, the coefficient Kt is decreased. In this case, the coefficient Kt may be a predetermined value (this may be a constant value or a value that increases in proportion to the difference between the actual peak timing and the target peak timing, as shown in the following equation (9). ) ΔKtd may be reduced, or as shown in the following equation (10), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value, or the actual peak timing and target (It may be a value that decreases in proportion to the difference from the peak timing.) It may be decreased by Rtd.
Kt = Kt−ΔKtd (9)
Kt = Kt × Rtd (10)
Also in the above formulas (9) and (10), Kt on the right side is the current coefficient, and Kt on the left side is the coefficient that is newly updated this time and used next time.
According to this, since the final target injection timing TT calculated according to the above equation (6) is advanced, the actual peak timing becomes the target peak timing, or at least approaches the target peak timing.
[0034]
Next, control related to the operation of the EGR control valve will be described. As a parameter to be controlled with respect to the operation of the EGR control valve, there is an amount of exhaust gas introduced into the combustion chamber 5 (hereinafter referred to as “EGR gas amount”). Since the EGR gas amount can be controlled by controlling the opening degree (EGR opening degree) of the EGR control valve, the EGR opening degree is controlled in this embodiment.
[0035]
Specifically, in the present embodiment, the EGR opening degree that achieves the optimum amount of EGR gas for the engine operating state (specifically, the amount at which the peak timing (CAp in FIG. 4 becomes a predetermined timing)). The EGR opening is previously stored in the ROM 32 in the form of a map as shown in FIG. 8 as a function of the engine speed N and the required load L as a basic EGR opening TDbase. During engine operation, the basic EGR opening degree TDbase is read from the map of FIG. 8 based on the engine speed N and the required load L.
[0036]
Here, if the EGR control valve 23 is controlled so that the EGR opening becomes the basic EGR opening TDbase, theoretically, the EGR gas amount becomes the optimum amount, and therefore the peak timing should be the predetermined timing. It is. However, actually, even if the EGR control valve 23 is controlled so that the EGR opening becomes the basic EGR opening TDbase due to the manufacturing error of the EGR control valve 23, deterioration with time, or the like, the peak timing CAp is the target. It is not always the predetermined timing. Therefore, in the present embodiment, the final target EGR opening degree TD is calculated according to the following equation (11).
TD = TDbase × Ke (11)
Although details will be described later, Ke used in the above equation (11) is a coefficient for setting the peak timing to the target timing. In any case, the peak timing becomes the target timing by controlling the EGR control valve 23 so that the EGR opening becomes the target EGR opening TD calculated according to the above equation (11).
[0037]
Next, a method for calculating the coefficient Ke used in the above equation (11) will be described. As described above, the optimum amount of EGR gas for the engine operating state is such that the peak timing (CAp in FIG. 4) becomes a predetermined timing. Here, as a general tendency, if the amount of EGR gas is large, the time from when the fuel is injected from the fuel injection valve 6 until the ignition of the fuel starts (so-called fuel ignition delay time) becomes longer, and The time from the start of fuel ignition to the completion of fuel combustion (so-called combustion time) also becomes longer. In any case, if the amount of EGR gas is large, the time from when the fuel is injected until the combustion of the fuel is completed becomes longer, so the peak timing is delayed. Conversely, if the amount of EGR gas is small, the peak timing is advanced. Therefore, when the peak timing is later than the predetermined timing, the peak timing approaches the predetermined timing if the EGR gas amount decreases (that is, the EGR opening decreases). Conversely, when the peak timing is earlier than the predetermined timing, the peak timing approaches the predetermined timing if the EGR gas amount increases (that is, if the EGR opening increases).
[0038]
Therefore, in the present embodiment, the target peak timing TCAp is read from the map of FIG. 7 based on the engine speed N and the required load L during engine operation. Then, the peak timing is detected for each expansion stroke, and the detected peak timing is compared with the target peak timing TCAp.
[0039]
Here, when the detected actual peak timing CAp is earlier than the target peak timing TCAp, the EGR gas amount is smaller than the target EGR gas amount, and therefore, the EGR opening is smaller than the target EGR opening. The coefficient Ke is increased. In this case, as shown in the following equation (12), the coefficient Ke may be a predetermined value (this may be a constant value or a value that increases in proportion to the difference between the actual peak timing and the target peak timing). ) ΔKei may be increased, or, as shown in the following equation (13), a predetermined ratio (this is a value larger than 1.0 and may be a constant value, or the actual peak timing and target (It may be a value that increases in proportion to the difference from the peak timing.) It may be increased by Rei.
Ke = Ke + ΔKei (12)
Ke = Ke × Rei (13)
In the above equations (12) and (13), Ke on the right side is the current coefficient, and Ke on the left side is a coefficient that is newly updated this time and used next time.
According to this, since the final target EGR opening degree TD calculated according to the above equation (11) becomes large, the actual peak timing becomes the target peak timing, or at least approaches the target peak timing.
[0040]
On the other hand, when the actual peak timing CAp is later than the target peak timing TCAp, the EGR gas amount is larger than the target EGR gas amount, and therefore, the EGR opening is larger than the target EGR opening. Is reduced. In this case, the coefficient Ke is a predetermined value (this may be a constant value or a value that increases in proportion to the difference between the actual peak timing and the target peak timing, as shown in the following equation (14). ) ΔKed may be reduced, or, as shown in the following equation (15), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value, or the actual peak timing and target It may be a value that decreases in proportion to the difference from the peak timing).
Ke = Ke−ΔKed (14)
Ke = Ke × Red (15)
In the above (12) and (13), Ke on the right side is the current coefficient, and Ke on the left side is a coefficient that is newly updated this time and used next time.
According to this, since the final target EGR opening degree TD calculated according to the above equation (11) becomes small, the actual peak timing becomes the target peak timing, or at least approaches the target peak timing.
[0041]
By the way, when the fuel injection amount, the injection timing, and the EGR opening degree are controlled as described above, misfire in the combustion chamber 5 (that is, despite fuel being injected from the fuel injection valve 6) The fuel may not ignite). This often occurs because the fuel injection amount is too large, the injection timing is too late, or the EGR gas amount is too large. Therefore, misfire can be suppressed by reducing the fuel injection amount, advancing the injection timing, or reducing the EGR gas amount when misfire occurs. In addition, when misfire occurs, the fuel does not burn, and the unburned fuel remains in the combustion chamber 5 or is discharged from the combustion chamber 5 as it is. If the fuel remains in the combustion chamber 5, the fuel injected in the next engine cycle becomes difficult to burn, and if the unburned fuel is discharged from the combustion chamber 5, the fuel consumption deteriorates and the exhaust emission Will be worsened.
[0042]
On the other hand, if the fuel injection amount is reduced, it becomes easier to burn the fuel, and deterioration of fuel consumption and exhaust emission can be suppressed. Therefore, in the present embodiment, it is determined whether or not misfire has occurred in the combustion chamber 5 as follows. When it is determined that misfire has occurred, the occurrence of misfire is determined as follows. In order to suppress this, the fuel injection amount, the injection timing, and the EGR opening degree are controlled. Next, a misfire determination method according to the present embodiment (that is, a method of determining whether or not misfire has occurred in the combustion chamber 5), and the present embodiment when it is determined that misfire has occurred. A control method for the fuel injection amount, the injection timing, and the EGR opening will be described.
[0043]
First, the misfire determination method in the present embodiment will be described. In the combustion chamber 5, the misfire occurs when combustion is not performed in the combustion chamber 5. At this time, the mixture in the combustion chamber 5 due to the vertical movement of the piston 4 is reduced. Only compression and expansion are performed. Therefore, at this time, the PV value changes as shown by the chain line in FIG. That is, the PV value gradually increases as the crank angle CA approaches the compression top dead center TDC, reaches a peak when the crank angle CA reaches the compression top dead center TDC, and then gradually decreases. Therefore, in this case, theoretically, the peak timing (CAp in FIG. 4) is the compression top dead center TDC. Of course, even when a misfire occurs, the peak timing CAp does not accurately become the compression top dead center TDC but may slightly deviate from the compression top dead center TDC. In this case, the peak timing CAp is in the vicinity of the compression top dead center TDC, and at least is hardly earlier than the compression top dead center TDC. Therefore, it can be determined that a misfire has occurred when the peak timing CAp is in the vicinity of the compression top dead center TDC, or when the peak timing CAp is earlier than the compression top dead center TDC.
[0044]
Therefore, in the first embodiment of the misfire determination method, the peak timing CAp is detected for each expansion stroke, and the detected peak timing CAp is compared with the compression top dead center TDC. Here, when the detected actual peak timing CAp is earlier than the compression top dead center TDC, it is determined that misfire has occurred. Conversely, when the detected actual peak timing CAp is later than the compression top dead center TDC, it is determined that no misfire has occurred. Thereby, it can be determined whether misfire has occurred in the combustion chamber 5.
[0045]
In the second embodiment of the misfire determination method, the detected actual peak timing CAp is a predetermined range in the vicinity of the compression top dead center TDC (the range in which the peak timing can be taken when misfire occurs). For example, when it is obtained in advance by experiments or the like and is within the range of “misfire range”), it is determined that misfire has occurred. On the other hand, when the detected actual peak timing CAp is outside the misfire range, it is determined that no misfire has occurred. This also makes it possible to determine whether or not misfire has occurred in the combustion chamber 5.
[0046]
In the second embodiment of the misfire determination method, if the most advanced angle value of the misfire range (that is, the earliest timing in the misfire range) is too close to the compression top dead center TDC, the misfire occurs. The peak timing CAp may be earlier than the most advanced angle value. In this case, although it must be determined that misfire has occurred, it is determined that no misfire has occurred. Therefore, in order to avoid this, it is necessary to set the most advanced value to a value (timing) sufficiently earlier than the compression top dead center TDC. Therefore, when it is difficult to set a value (timing) sufficiently earlier than the compression top dead center TDC in this way, the misfire range is simply set without setting the most advanced value of the misfire range. Only the most retarded angle value (that is, the latest timing in the misfire range) is used to determine that misfire has occurred when the peak timing CAp is earlier than the most retarded angle value, and conversely, the peak timing CAp It may be determined that no misfire has occurred when is slower than the most retarded angle value.
[0047]
Further, in the second embodiment of the misfire determination method, when it is difficult to set the most retarded value of the misfire range, the peak timing CA is simply set as in the first embodiment of the misfire determination method. It is advantageous to determine whether or not misfire has occurred compared to the compression top dead center TDC.
[0048]
By the way, when misfire has occurred, theoretically, the above-mentioned ΔPV becomes zero. Of course, even when misfiring occurs, ΔPV may not be exactly zero and may deviate from zero, but in any event, when misfiring occurs, ΔPV is at least close to zero. . Therefore, it can be determined that misfire has occurred when ΔPV is near zero or very small.
[0049]
Therefore, in the third embodiment of the misfire determination method, ΔPV is calculated for each expansion stroke, and the calculated ΔPV and a predetermined range near zero (this can be determined that misfire has occurred. This is a range of ΔPV of a certain degree and is a range obtained in advance by experiments or the like, and this is hereinafter referred to as “misfire range”). Here, when the calculated ΔPV is within the misfire range, it is determined that misfire has occurred. Conversely, when the calculated ΔPV is outside the misfire range, it is determined that no misfire has occurred. This also makes it possible to determine whether or not misfire has occurred in the combustion chamber 5.
[0050]
Further, in the fourth embodiment of the misfire determination method, when the calculated ΔPV is smaller than a predetermined value (a value greater than zero but close to zero, hereinafter referred to as “predetermined value”). It is determined that a misfire has occurred, and conversely, when the calculated ΔPV is greater than the predetermined value, it is determined that no misfire has occurred. This also makes it possible to determine whether or not misfire has occurred in the combustion chamber 5.
[0051]
In the third embodiment of the misfire determination method, if the minimum value (negative value) of the misfire range is too close to zero, ΔPV when misfire occurs may be smaller than the minimum value. There is a possibility (in practice, ΔPV is not often a negative value, but ΔPV may be calculated as a negative value). In this case, although it must be determined that misfire has occurred, it is determined that no misfire has occurred. Therefore, in order to avoid this, it is necessary to set the minimum value to a negative value sufficiently smaller than zero. Therefore, considering this, it is better to determine whether or not misfire has occurred by simply comparing ΔPV with a predetermined value (a value greater than zero but close to zero) as in the fourth embodiment of the misfire determination method. It is advantageous.
[0052]
In general, when the engine speed is small and the required load is small, the fuel injection amount is small, and therefore ΔPV is also a small value (that is, a value close to zero). At this time, as described above, when it is determined whether or not misfire has occurred based on ΔPV, since ΔPV is close to zero, it is determined that misfire has occurred even though misfire has not occurred. There is a possibility of being. Therefore, when the engine speed is small and the required load is small, it can be said that the determination result is more accurate if it is determined whether misfire has occurred based on the peak timing.
[0053]
Next, a control method for the fuel injection amount in the present embodiment when it is determined that misfire has occurred will be described. When misfire occurs, the fuel injected from the fuel injection valve 6 may remain in the combustion chamber 5. In this case, when the fuel of the desired amount (target fuel injection amount determined as described above) is injected from the fuel injection valve 6 in the next engine cycle, the air-fuel ratio of the air-fuel mixture becomes very small. . In this case, it becomes difficult for the ignition of the fuel to occur, or even if the ignition of the fuel occurs, the amount of air is small for the fuel to burn completely, so some of the fuel is wasted without being burned, It also causes deterioration of exhaust emissions.
[0054]
Therefore, in the method for controlling the fuel injection amount of the present embodiment when a misfire occurs, the target fuel injection amount is reduced when it is determined that a misfire has occurred. Specifically, the final target valve opening time ΤAU calculated according to the above equation (1) is reduced, or the coefficient Ki used in the above equation (1) is reduced. When the coefficient Ki is made small, the coefficient Ki is not updated according to the above equation (2), but as shown in the following equation (16), it may be a predetermined value (this may be a constant value or peak timing) If it is later than the compression top dead center, it may be inversely proportional to the difference between the peak timing and the compression top dead center, or if ΔPV is positive, it may be a value that increases inversely proportional to ΔPV). Instead of updating according to the above equation (3), as shown in the following equation (17), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value). If the peak timing is later than the compression top dead center, the value may be inversely proportional to the difference between the peak timing and the compression top dead center, or if ΔPV is positive, it may be a value that decreases in inverse proportion to ΔPV. It may be made smaller.
Ki = Ki−ΔKidu (16)
Ki = Ki × Ridu (17)
In the above equations (16) and (17), Ki on the right side is the current coefficient, and Ki on the left side is a coefficient that is newly updated this time and used next time.
According to this, the target energization time ΤAU calculated according to the above equation (1) is shortened, and therefore the fuel injection amount is reduced, so that the fuel is easily ignited, and the fuel is not burned and is wasted. And the deterioration of exhaust emission is also suppressed.
[0055]
Next, a control method for the injection timing of the present embodiment when misfire occurs will be described. Since the peak timing when misfire occurs is close to the compression top dead center, the peak timing at this time is much earlier than the target peak timing read from the map of FIG. In this case, in the above-described embodiment, the coefficient Kt is calculated according to the above formula (7) or (8). According to this, the injection timing is retarded. Here, generally, the later the injection timing, the more difficult the fuel is ignited. That is, if the injection timing is controlled according to the above equation (6) using the coefficient Kt calculated according to the above equation (7) or (8), the occurrence of misfire continues.
[0056]
Therefore, in the first embodiment of the method for controlling the injection timing when a misfire occurs, the injection timing is advanced when it is determined that a misfire has occurred. Specifically, when it is determined that misfire has occurred, a timing sufficiently later than the target peak timing is used instead of the actual peak timing detected. That is, a timing sufficiently later than the target peak timing is used as the actual peak timing. In this case, in the above-described embodiment, the coefficient Kt is calculated according to the above equation (9) or (10), and therefore the injection timing is advanced. According to this, it is avoided that the injection timing is retarded. In addition, according to this, since the injection timing is advanced, the fuel is easily ignited and the misfire is eliminated.
[0057]
Further, in the second embodiment of the method for controlling the injection timing when misfire occurs, when it is determined that misfire has occurred, the coefficient Kt used in the above equation (6) is directly reduced. In this case, the coefficient Kt is not updated according to the above equation (7), but as shown in the following equation (18), the coefficient Kt may be a predetermined value (this may be a constant value, and the peak timing is a compression top dead center. If it is later, it may be a value that increases in inverse proportion to the difference between the peak timing and the compression top dead center.) It may be reduced by ΔKtdu, or may not be updated according to the above equation (8). As shown in (19), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value, or when the peak timing is later than the compression top dead center, (It may be a value that becomes inversely proportional to the difference from the dead point.) It may be made smaller by Rtdu.
Kt = Kt−ΔKtdu (18)
Kt = Kt × Rtdu (19)
In the above formulas (18) and (19), Kt on the right side is the current coefficient, and Kt on the left side is the coefficient that is newly updated this time and is used next time.
According to this, the target injection timing TT calculated according to the above equation (6) is advanced, and therefore the injection timing is advanced. According to this, it is avoided that the injection timing is retarded when misfire occurs. In addition, according to this, since the injection timing is advanced, the fuel is easily ignited and the misfire is eliminated.
[0058]
Next, a control method for the EGR opening degree of the present embodiment when misfire occurs will be described. As described above, since the peak timing when misfire occurs is close to the compression top dead center, the peak timing at this time is much earlier than the target peak timing read from the map of FIG. ing. In this case, in the above-described embodiment, the coefficient Ke is calculated according to the above equation (12) or (13). However, according to this, the EGR opening degree is increased, and thus the EGR gas amount is increased. Here, in general, as the amount of EGR gas increases, the fuel tends to be more difficult to ignite. That is, if the EGR opening degree is controlled according to the above equation (11) using the coefficient Ke calculated according to the above equation (12) or (13), the occurrence of misfire continues.
[0059]
Thus, in the first embodiment of the method for controlling the EGR opening when a misfire occurs, when it is determined that a misfire has occurred, the EGR opening is reduced. Specifically, when it is determined that a misfire has occurred, a timing sufficiently later than the target peak timing is used instead of the actual peak timing to be detected (the timing used here is a misfire occurrence). The timing may be the same as or different from the timing used in the first embodiment of the method for controlling the injection timing at the time, but the same is easier in terms of control). That is, a timing sufficiently later than the target peak timing is used as the actual peak timing. In this case, in the above-described embodiment, the coefficient Ke is calculated according to the above formula (14) or (15), and therefore, the EGR opening becomes small. According to this, an increase in the amount of EGR gas is avoided. In addition, according to this, since the amount of EGR gas is reduced, the fuel is easily ignited and the misfire is eliminated.
[0060]
Further, in the second embodiment of the injection timing control method at the time of misfire occurrence, when it is determined that misfire has occurred, the coefficient Ke used in the above equation (11) is directly reduced. In this case, the coefficient Ke is not updated according to the above equation (12), but as shown in the following equation (20), the coefficient Ke may be a predetermined value (this may be a constant value, and the peak timing is a compression top dead center). If it is later, it may be a value that increases in inverse proportion to the difference between the peak timing and the compression top dead center.) It may be reduced by ΔKedu, or may not be updated according to the above equation (13), but As shown in (21), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value, or when the peak timing is later than the compression top dead center, It may be a value that decreases in inverse proportion to the difference from the dead point).
Ke = Ke−ΔKedu (20)
Ke = Ke × Redu (21)
In the above equations (20) and (21), Ke on the right side is the current coefficient, and Ke on the left side is a coefficient that is newly updated this time and used next time.
According to this, since the target EGR opening degree TD calculated according to the above equation (11) becomes small, the EGR opening degree becomes small. According to this, it is avoided that the amount of EGR gas increases when misfire occurs. In addition, according to this, since the amount of EGR gas is reduced, the fuel is easily ignited and the misfire is eliminated.
[0061]
By the way, when the fuel injection amount, the injection timing, and the EGR opening degree are controlled as described above, the combustion delay (that is, the phenomenon in which the combustion is slowed down) is caused even if no misfire occurs in the combustion chamber 5. May occur. This often occurs because the fuel injection amount is too large, the injection timing is too late, or the EGR gas amount is too large. Therefore, if the fuel injection amount is reduced, the injection timing is advanced, or the EGR gas amount is reduced when the combustion delay occurs, the combustion delay can be suppressed. In addition, when the combustion delay occurs, the fuel is difficult to burn, a part of the fuel does not burn, and the unburned fuel remains in the combustion chamber 5 or is discharged from the combustion chamber 5 as it is. I'm sorry. If the fuel remains in the combustion chamber 5, the fuel injected in the next engine cycle is difficult to burn, and if the fuel is discharged from the combustion chamber 5, the fuel efficiency is deteriorated. Therefore, if the fuel injection amount is reduced when the combustion delay occurs, the fuel can be easily burned, and the deterioration of fuel consumption can be suppressed. Therefore, in the present embodiment, it is determined whether or not a combustion delay has occurred in the combustion chamber 5 as follows, and when it is determined that the combustion delay has occurred, the combustion is performed as follows. In order to suppress the occurrence of delay, the fuel injection amount, the injection timing, and the EGR opening degree are controlled. Next, a combustion delay determination method in this embodiment (that is, a method for determining whether or not a combustion delay has occurred in the combustion chamber 5), and this implementation when it is determined that a combustion delay has occurred. A control method for the fuel injection amount, the injection timing, and the EGR opening in the embodiment will be described.
[0062]
First, the combustion delay determination method in the present embodiment will be described. When the combustion delay occurs, the peak timing (that is, the timing at which the PV value becomes maximum and is CAp in FIG. 4) is delayed. Therefore, it can be determined that the combustion delay has occurred when the peak timing CAp is relatively late. Therefore, in the first embodiment of the combustion delay determination method, the peak timing CAp is detected for each expansion stroke, and the detected peak timing CAp and a predetermined timing (for example, a combustion delay occurs). The timing that is the earliest of the timings that are obtained and that is obtained in advance by experiments or the like, and is hereinafter referred to as “predetermined timing”. Here, when the detected actual peak timing CAp is later than the predetermined timing, it is determined that a combustion delay has occurred. On the other hand, when the detected actual peak timing CAp is earlier than the predetermined timing, it is determined that no combustion delay has occurred. Thereby, it can be determined whether or not a combustion delay occurs in the combustion chamber 5.
[0063]
Further, when the combustion delay occurs, the ΔPV is relatively small. Therefore, it can be determined that the combustion delay occurs when ΔPV is relatively small. Therefore, in the second embodiment of the combustion delay determination method, ΔPV is calculated for each expansion stroke, and this calculated ΔPV and a predetermined value (for example, ΔPV when the combustion delay occurs) And the value obtained in advance through experiments or the like, hereinafter referred to as “predetermined value”). Of course, when the misfire determination is performed at the same time, the calculated ΔPV and the misfire range (this is a range of values of ΔPV that can be recognized as misfires, and in a range near zero. It is also compared with the maximum value. Here, when the calculated ΔPV is smaller than the predetermined value and larger than the maximum value of the misfire range, it is determined that a combustion delay has occurred. On the other hand, when the calculated ΔPV is larger than the predetermined value, it is determined that the combustion delay has not occurred. This also makes it possible to determine whether or not a combustion delay has occurred in the combustion chamber 5.
[0064]
Of course, the combustion delay may be determined by combining the first and second embodiments of the combustion delay determination method described above. In this case, it may be determined that the combustion delay has occurred when the peak timing CAp is later than the predetermined timing or ΔPV is smaller than the predetermined value and larger than the maximum value of the misfire range. Further, it may be determined that the combustion delay has occurred when the peak timing CAp is later than the predetermined timing and ΔPV is smaller than the predetermined value and larger than the maximum value of the misfire range.
[0065]
Next, a control method for the fuel injection amount of the present embodiment when the combustion delay occurs will be described. When the combustion delay occurs, the fuel injected from the fuel injection valve 6 may remain in the combustion chamber 5. As described in relation to the case where misfire has occurred, in this case, the fuel of the expected amount (target fuel injection amount determined as described above) from the fuel injection valve 6 in the next engine cycle. Is injected, the air-fuel ratio of the air-fuel mixture becomes very small. In this case, it becomes difficult for the ignition of the fuel to occur, or even if the ignition of the fuel occurs, the amount of air is small for the fuel to burn completely. It will be wasted and exhaust emissions will deteriorate.
[0066]
Therefore, in the method for controlling the fuel injection amount according to this embodiment when the combustion delay occurs, the target fuel injection amount is decreased when it is determined that the combustion delay has occurred. Specifically, the final target valve opening time ΤAU calculated according to the above equation (1) is reduced, or the coefficient Ki used in the above equation (1) is reduced. When the coefficient Ki is made small, the coefficient Ki is not updated according to the above equation (2), but as shown in the following equation (22), it may be a predetermined value (this may be a constant value or peak timing) May be a value that increases in proportion to the difference between and a predetermined timing or inversely proportional to ΔPV, but may be reduced by ΔKidv (which is smaller than the predetermined value ΔKidu used in the above equation (16)). As shown in the following equation (23), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value, or inversely proportional to the difference between the peak timing and the predetermined timing, or It may be a value that is inversely proportional to ΔPV, but may be made smaller by Ridv (which is a value that is larger than the predetermined ratio Ridu used in the above equation (17)).
Ki = Ki−ΔKivd (22)
Ki = Ki × Riv (23)
In the above equations (22) and (23), Ki on the right side is the current coefficient, and Ki on the left side is a coefficient that is newly updated this time and used next time.
According to this, the target energization time ΤAU calculated according to the above equation (1) is shortened, and therefore the fuel injection amount is reduced, so that the fuel is easily ignited, and the fuel is not burned and is wasted. And the deterioration of exhaust emission is also suppressed.
[0067]
Next, an injection timing control method according to this embodiment when a combustion delay occurs will be described. The later the injection timing, the greater the possibility that a combustion delay will occur. Therefore, if the injection timing is advanced while the combustion delay is occurring, the possibility that the combustion delay will occur is reduced. Therefore, in the injection timing control method of this embodiment when the combustion delay occurs, the injection timing is advanced when it is determined that the combustion delay occurs. Specifically, the coefficient Kt used in the above equation (6) is reduced. In this case, the coefficient Kt is not updated according to the above equation (7), but as shown in the following equation (24), the coefficient Kt may be a predetermined value (this may be a constant value, the peak timing and the predetermined timing It may be a value that increases in proportion to the difference between them or in proportion to ΔPV, but may be made smaller by ΔKtdv (which is smaller than the predetermined value ΔKtdu used in the above equation (18)), or 8) Instead of being updated according to 8), as shown in the following equation (25), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value, or the peak timing and the predetermined timing described above). It may be a value that is inversely proportional to the difference between the two and ΔPV, or may be a value that is smaller than the predetermined ratio Rtdu used in the above equation (19).
Kt = Kt−ΔKtdv (24)
Kt = Kt × Rtdv (25)
In the above equations (24) and (25), Kt on the right side is the current coefficient, and Kt on the left side is the coefficient that is newly updated this time and is used next time.
According to this, the target injection timing TT calculated according to the above equation (6) is advanced, and therefore, the fuel is easily ignited and the combustion delay is eliminated.
[0068]
Next, a method for controlling the EGR opening degree of the present embodiment at the time of combustion delay occurrence will be described. As the EGR gas amount increases, the possibility of combustion delay increases. Therefore, if the EGR opening is decreased when the combustion delay occurs (that is, if the EGR gas amount is decreased), the combustion delay is increased. Is less likely to occur. Therefore, in the EGR opening degree control method of the present embodiment when the combustion delay occurs, when it is determined that the combustion delay occurs, the EGR opening degree is decreased. Specifically, the coefficient Ke used in the above equation (11) is reduced. In this case, the coefficient Ke is not updated in accordance with the above equation (12), but as shown in the following equation (26), it may be a predetermined value (this may be a constant value, the peak timing and the predetermined timing It may be a value that increases in proportion to the difference of Δ or inversely proportional to ΔPV, but may be reduced by a predetermined value ΔKedv used in the above equation (20), or updated according to the above equation (13). Rather, as shown in the following equation (27), a predetermined ratio (this is a value smaller than 1.0 and may be a constant value, or inversely proportional to the difference between the peak timing and the predetermined timing. Alternatively, it may be a value that becomes smaller in proportion to ΔPV, but may be made smaller by Redv (which is a value larger than the predetermined ratio Redu used in the above equation (21)).
Ke = Ke−ΔKedv (26)
Ke = Ke × Redv (27)
In the above equations (26) and (27), Ke on the right side is the current coefficient, and Ke on the left side is a coefficient that is newly updated this time and used next time.
According to this, since the target EGR opening degree TD calculated according to the above equation (11) becomes small, the EGR opening degree becomes small. According to this, since the amount of EGR gas is reduced, the fuel is easily ignited and the combustion delay is eliminated.
[0069]
FIG. 9 shows an example of control of the fuel injection amount according to the present embodiment. In FIG. 9, CAp is the peak timing (CAp in FIG. 4), ΔPV is the PV difference, Q is the fuel injection amount, Qb is the amount of fuel burned in the combustion chamber 5, and Qu is the combustion This is the amount of fuel remaining in the chamber 5. In the diagram showing the peak timing CAp, TDC indicates a compression top dead center. In the diagram showing the fuel injection amount Q, 1 to 7 indicate the number of times of fuel injection from the fuel injection valve 6, 1 is the first fuel injection, 2 is the second fuel injection, and so on. 7 represents the seventh fuel injection.
[0070]
In the example shown in FIG. 9, in the first fuel injection, an expected amount Q3 of fuel is injected. At this time, in the example of FIG. 9, the combustion fuel amount Qb is an amount Q3 equal to the fuel injection amount. That is, all the injected fuel burns. Therefore, the remaining fuel amount Qu is zero. The peak timing CAp is an intended timing (ie, target timing) TCA, and ΔPV is an intended value (ie, target ΔPV) TΔPV. In this case, the peak timing CAp is later than the most retarded timing A of the misfire range and earlier than the predetermined timing (that is, the earliest timing among the timings at which combustion is delayed) B, and ΔPV is greater than the misfire range ( That is, it is larger than the maximum value D of the range of ΔPV values that can be recognized as misfiring and is larger than the predetermined value (that is, the largest value of ΔPV when combustion delay occurs) C. Therefore, it is determined that neither misfire nor combustion delay occurs. Therefore, even in the second fuel injection, a predetermined amount of fuel (in the example of FIG. 9, the same amount Q3 as the first fuel injection amount) is injected.
[0071]
In the example of FIG. 9, even in the next second fuel injection, the combustion fuel amount Qb is the amount Q3 equal to the fuel injection amount, and all the injected fuel is combusted. Therefore, the remaining fuel amount Qu is zero, the peak timing CAp is the intended timing TCA, and ΔPV is the intended value TΔPV. Therefore, at this time, neither misfire nor fuel delay occurs, so the fuel of the desired amount (the same amount Q3 as the first fuel injection amount in the illustrated example) is injected even in the third fuel injection. The
[0072]
However, in the example of FIG. 9, the combustion fuel amount Qb is zero in the next third fuel injection. That is, misfire has occurred. Therefore, the remaining fuel amount Qu is an amount Q3 equal to the fuel injection amount. The peak timing CAp is near the compression top dead center TDC, and ΔPV is substantially zero. In this case, since the peak timing CAp is earlier than the most retarded timing A of the misfire range and ΔPV is smaller than the maximum value D of the misfire range, it is determined that misfire has occurred. For this reason, in the fourth fuel injection, an amount of fuel Q2 smaller than the intended amount is injected. Of course, at this time, in order to facilitate combustion of the fuel, the amount of EGR gas is reduced, and the timing of the fourth fuel injection is advanced.
[0073]
Since the fuel is easily combusted in the fourth fuel injection, in the example of FIG. 9, the combustion fuel amount Qb is smaller than the fuel injection amount Q2 in the fourth fuel injection but larger than zero Q1. It has become. Therefore, although the remaining fuel amount Qu increases from Q3 to Q4, the peak timing CAp is later than the most retarded angle timing A of the misfire range, and ΔPV is larger than the maximum value D of the misfire range. That is, the combustion in the combustion chamber 5 is improved. However, since the peak timing CAp is later than the predetermined timing B and ΔPV is smaller than the predetermined value C, it is determined that a combustion delay has occurred. Therefore, in the fifth fuel injection, an amount of fuel Q1 that is smaller than the fuel injection amount Q2 in the fourth fuel injection is injected. Also at this time, in order to facilitate the combustion of the fuel, the amount of EGR gas is further reduced, and the timing of the fifth fuel injection is further advanced.
[0074]
Since the fuel is more easily combusted in the fifth fuel injection, the fuel combustion amount Qb is an amount Q2 larger than the fuel injection amount Q1 in the fifth fuel injection in the example of FIG. . Therefore, the remaining fuel amount Qu decreases from Q4 to Q3. However, since the peak timing CAp is later than the predetermined timing B and ΔPV is smaller than the predetermined value C, it is determined that a combustion delay has occurred. For this reason, in the example of FIG. 9, the fuel injection amount in the sixth fuel injection is reduced to zero. At this time as well, the EGR gas amount is reduced to make the fuel easier to burn, and the timing of the sixth fuel injection is further advanced.
[0075]
In the sixth fuel injection, since the fuel is more easily combusted, the fuel combustion amount Qb is Q3 in the example of FIG. Therefore, the remaining fuel amount Qu decreases from Q3 to zero. At this time, the peak timing CAp is later than the most retarded angle timing A of the misfire range and earlier than the predetermined timing B, and ΔPV is larger than the maximum value D of the misfire range and larger than the predetermined value C. Therefore, it is determined that neither misfire nor combustion delay occurs. Therefore, in the seventh fuel injection, a predetermined amount of fuel (in the example of FIG. 9, the same amount Q3 as the first fuel injection amount) is injected.
[0076]
According to this embodiment, when a misfire or a combustion delay occurs, the misfire or the combustion delay is eliminated through such a process. In addition, when the combustion property is different from the intended property, the ignition delay of the fuel becomes large. According to this process, such an ignition delay is also eliminated. Further, the combustion period of the fuel is also a desirable period, and the shift in the fuel ignition (combustion start) timing caused by the fuel adhering to the wall surface defining the combustion chamber 5 is eliminated. Further, since the air-fuel ratio is prevented from being excessively rich, misfires and excessive combustion due to the air-fuel ratio being excessively rich (this increases combustion noise). ) Is also suppressed.
[0077]
Incidentally, in the above-described embodiment, ΔPV is calculated for each engine cycle, and the calculated ΔPV is compared with the target ΔPV read from the map of FIG. 5 to correct the fuel injection amount. According to this, since the correction of the fuel injection amount is performed every engine cycle, the number of corrections of the fuel injection amount is large, and therefore the accuracy of correction of the fuel injection amount is high. However, in order to correct the fuel injection amount for each engine cycle, it is necessary to prepare a map as shown in FIG. 5 and store this map in the ROM 32 in advance. In order to prepare the map as shown in FIG. 5, labor for that is required, and in order to store such a map in the ROM 32, it is necessary to increase the storage capacity of the ROM 32.
[0078]
Therefore, a plurality of points determined by the engine speed N and the target fuel injection amount TQ (hereinafter referred to as “operation points”) are discretely (that is, at a constant engine speed interval and a constant target fuel injection amount). A map including an interval (for example, a map as shown in FIG. 10A, where a point indicated by a black dot is an operating point) is prepared. Furthermore, a map (for example, FIG. 10 (FIG. 10)) that includes a plurality of points (hereinafter also referred to as “operation points”) determined by the engine speed N and the target ΔPV corresponding to each operation point on FIG. B) is also prepared, where a point indicated by a black dot is an operating point). Then, ΔPV is calculated when the current operating point (that is, the engine speed and the target fuel injection amount) matches any of the operating points on the map of FIG. 10A, and the target ΔPV at this time is calculated. The fuel injection amount may be corrected by reading from the map of FIG. 10B and comparing the ΔPV with the target ΔPV. This reduces the effort for preparing the map and reduces the need to increase the storage capacity of the ROM 32 for storing the map.
[0079]
However, according to this, correction to the fuel injection amount is performed only when the current operating point (engine speed and target fuel injection amount) matches any of the operating points in FIG. It will be. For this reason, there exists a malfunction that the correction | amendment precision with respect to fuel injection quantity becomes low. Compared to when the engine operating state is in a transient state (that is, a state in which the engine speed and the required load change are relatively large), the engine operating state is in a steady state (that is, the engine speed and the required load change). The accuracy of calculation of ΔPV is higher when it is in a (smaller state) (hereinafter referred to as “steady operation”). Therefore, in order to ensure high correction accuracy for the fuel injection amount, it is preferable that correction for the fuel injection amount is performed during steady operation. However, during steady operation, changes in engine speed and required load are relatively small, so the current operating point rarely coincides with any of the operating points in FIG. For this reason, there are problems that the number of executions of correction for the fuel injection amount is small and the correction accuracy for the fuel injection amount is low. Therefore, hereinafter, the amount of data stored in the ROM 32 for correction of the fuel injection amount is small, but the amount of data collected for correction of the fuel injection amount is large, and much data is collected even during steady operation. An embodiment of a fuel injection amount correction method according to the present invention will be described.
[0080]
The flowchart which implement | achieves the correction method with respect to such fuel injection quantity was shown to FIG. 11 and FIG. Hereinafter, another embodiment of the correction method for the fuel injection amount will be described with reference to the flowcharts of FIGS. 11 and 12. In the flowcharts of FIGS. 11 and 12, first, in step 10, one of the operating points on the map of FIG. 10A is selected as a reference point. Various reference point selection methods are conceivable. For example, there is a method of selecting an operation point that is close in average to all of a plurality of operation points over a plurality of engine cycles. FIG. 13 shows an enlarged region near the reference point. Hereinafter, the engine speed at the reference point is N ₀ The target fuel injection amount at the reference point is expressed as TQ ₀ The flowchart will be described.
[0081]
In step 11, the engine speed N at the reference point according to the following equation (28): ₀ A difference ΔN between the current engine speed N and the target fuel injection amount at the reference point (hereinafter referred to as “reference target fuel injection amount”) TQ according to the following equation (29): ₀ A difference ΔTQ in the current target fuel injection amount TQ with respect to is calculated.
ΔN = N−N ₀ ... (28)
ΔTQ = TQ−TQ ₀ ... (29)
[0082]
Next, in step 12, the absolute value of the difference ΔN is n / 2 or less (| ΔN | ≦ n / 2) and the absolute value of the difference ΔTQ is tq / 2 or less (| ΔTQ | ≦ tq / 2). ) Is determined. Here, n is the distance between the operating points along the horizontal axis of the map of FIG. 10 (A), which is displayed in FIG. Moreover, tq is the distance between the operating points along the vertical axis of the map of FIG. 10A, and this is also displayed in FIG. That is, in step 12, it is determined whether or not the operating point composed of the current engine speed N and the current target fuel injection amount TQ is within a region W surrounded by a one-dot chain line in FIG. When it is determined at step 12 that | ΔN |> n / 2 or | ΔTQ |> tq / 2, the routine returns to step 11. In this case, step 11 is executed again. Therefore, in this flowchart, step 11 is repeatedly executed until it is determined in step 12 that | ΔN | ≦ n / 2 and | ΔTQ | ≦ tq / 2. When it is determined in step 12 that | ΔN | ≦ n / 2 and | ΔTQ | ≦ tq / 2, the routine proceeds to step 13.
[0083]
In step 13, the amount of air sucked into the combustion chamber 5 (hereinafter referred to as “intake amount”) Ga and a reference intake amount Ga. ₀ Is smaller than the predetermined value α (| Ga-Ga ₀ | <Α), and the air-fuel ratio AF of the air-fuel mixture in the combustion chamber 5 and the reference air-fuel ratio AF ₀ Is smaller than the predetermined value β (| AF−AF) ₀ | <Β), and the injection timing T and the reference injection timing T ₀ The absolute value of the difference from the value is smaller than the predetermined value γ (| T−T ₀ Whether or not | <γ) is determined. That is, the deviation of the current intake air amount from the reference intake air amount, the current air fuel ratio deviation from the reference air fuel ratio, and the current injection timing deviation from the reference injection timing are within a certain range. It is determined whether or not. Where | Ga-Ga ₀ | ≧ α, or | AF-AF ₀ | ≧ β or | T−T ₀ When it is determined that | ≧ γ, the routine returns to step 11 and step 11 is executed again. Therefore, in this flowchart, in step 13, | Ga-Ga ₀ | ≧ α and | AF-AF ₀ | ≧ β and | T−T ₀ Steps 11 and 12 are repeatedly executed until it is determined that | ≧ γ. In step 13, | Ga-Ga ₀ | ≧ α and | AF-AF ₀ | ≧ β and | T−T ₀ When it is determined that | ≦ γ, the routine proceeds to step 14.
[0084]
In step 14, the coefficient f is calculated according to the following equation (30).
f = ((1-2 × | ΔN | / n) + (1-2 × | ΔTQ | / tq)) / 2 (30)
Here, (1-2 × | ΔN | / n) on the right side is obtained by converting ΔN on the horizontal axis to f (ΔN) on the vertical axis from the relationship shown in FIG. On the other hand, (1-2 × | ΔTQ | / tq) on the right side is obtained by converting ΔTQ on the horizontal axis to f (ΔTQ) on the vertical axis from the relationship shown in FIG. Therefore, according to the above equation (30), the average value of these f (ΔN) and f (ΔTQ) is used as the coefficient f. The coefficient f is a coefficient used in equations (31) and (32) described later, and the function of the coefficient f when used in equation (31) is to change ΔPV calculated in each engine cycle to ΔPV. It is determined how much to be reflected in the integral value of. Therefore, as is clear from the above equation (30) and equation (31) described later, the value of ΔPV reflected in the integrated value of ΔPV decreases as the operating point is further away from the reference point. The coefficient f is also a coefficient used in the equation (32). The function of the coefficient f when used in the equation (32) is to calculate ΔPV once in each engine cycle as data. The extent to which the number of acquisitions is reflected is determined. Therefore, as is clear from the above equation (30) and equation (32) described later, the more the operating point is away from the reference point, the smaller the number of times reflected in the data acquisition times.
[0085]
Next, in step 15, an integrated value ΔPVsum of ΔPV is calculated according to the following equation (31).
ΔPVsum = ΔPVsum + f × (1−ΔTQ / TQ ₀ ) × ΔPV (31)
Here, ΔPVsum on the left side is the integrated value of ΔPV newly calculated this time, and ΔPVsum on the right side is the integrated value of ΔPV up to the previous time. Also, on the right side, TQ ₀ Is the reference target fuel injection amount, and ΔTQ is the reference target fuel injection amount TQ calculated in step 11 ₀ The difference in the current target fuel injection amount TQ with respect to. Also, (1-ΔTQ / TQ on the right side ₀ ) Is for linearly interpolating ΔPV calculated when the operating point does not match the reference point to ΔPV to be calculated when the operating point matches the reference point. That is, since a linear relationship is established between ΔPV and the fuel injection amount, (1-ΔTQ / TQ on the right side) ₀ ) Can be used to change ΔPV calculated in each engine cycle to ΔPV to be calculated when the operating point coincides with the reference point. Further, f on the right side is a coefficient calculated in step 14. Therefore, as described above, according to this, as the operating point moves away from the reference point, the value of ΔPV reflected in the integrated value ΔPVsum of ΔPV decreases.
[0086]
Next, at step 16, a data acquisition number counter C is calculated according to the following equation (32).
C = C + f (32)
Here, C on the left side is the data acquisition count newly calculated this time, and C on the right side is the data acquisition count up to the previous time. Since f on the right side is a coefficient calculated in step 14, as described above, the number of times reflected in the data acquisition number of ΔPV decreases as the operating point moves away from the reference point. .
[0087]
Next, at step 17, it is judged if the data acquisition number counter C calculated at step 16 is larger than a predetermined value δ (C> δ). That is, it is determined whether or not the number of data acquisition times (that is, the number of samples) exceeds a certain number of times (that is, a certain number of samples). If it is determined that C ≦ δ, the routine returns to step 11 and step 11 is executed again. That is, steps 11 to 16 are repeatedly executed until it is determined in step 17 that C> δ. On the other hand, when it is determined that C> δ, the routine proceeds to step 18.
[0088]
In step 18, the average value ΔPVave of the integrated value ΔPVsum of ΔPV calculated in step 15 is calculated according to the following equation (33).
ΔPVave = ΔPVsum / C (33)
Here, on the right side, ΔPVsum is the integrated value of ΔPV calculated in step 15, and C is the number of data acquisition times calculated in step 16.
[0089]
Next, at step 19, in accordance with the following equation (34), the reference target fuel injection amount TQ ₀ A correction value Δq for is calculated.
Δq = − (ΔPVave−TΔPV ₀ ) / TΔPV ₀ × TQ ₀ ... (34)
Here, on the right side, ΔPVave is the average value of the integrated value ΔPVsum of ΔPV calculated in step 18, and TΔPV ₀ Is the reference engine speed N in the map of FIG. ₀ Is the target ΔPV corresponding to.
[0090]
Next, at step 20, it is determined whether a condition for feedback control of the target fuel injection amount (hereinafter referred to as “feedback condition”) is satisfied. Here, when it is determined that the feedback condition is not satisfied, the routine ends as it is. On the other hand, when it is determined that the feedback condition is satisfied, the routine proceeds to step 21 where the target fuel injection amount TQ at the reference point is determined according to the following equation (35). ₀ Is calculated.
TQ ₀ = TQ ₀ + Δq (35)
Where TQ on the left side ₀ Is the newly calculated reference target fuel injection amount, and the right side TQ ₀ Is the reference target fuel injection amount up to the previous time. Further, Δq on the right side is the correction value calculated in step 19.
[0091]
According to this method, even when the operating point does not match the reference point, ΔPV is calculated for each engine cycle, and ΔPV is converted into ΔPV when the operating point matches the reference point. This is reflected in the correction of the target fuel injection amount. Therefore, according to this, the amount of data stored in the ROM 32 for correcting the fuel injection amount can be reduced, the amount of data collected for correcting the fuel injection amount is large, and a large amount is also obtained during steady operation. Data is collected.
[0092]
This method is for correcting the fuel injection amount based on ΔPV, but can also be applied to correcting the fuel injection amount based on peak timing.
[0093]
By the way, the determination of the occurrence of misfire or the occurrence of combustion delay becomes a calculation load of the ECU 30, and when it is determined that the misfire or the combustion delay has occurred, the fuel injection amount, the injection timing, and If the ECU opening degree is changed, there is a possibility that another problem occurs while the above-described effect is obtained. Considering this, the determination of the occurrence of misfire or combustion delay, and the change in fuel injection amount, injection timing, and ECU opening when it is determined that misfire or combustion delay has occurred are the minimum required. It may be preferable to limit to a minimum and not to perform as much as possible. On the other hand, misfire and combustion delay are particularly likely to occur immediately after the internal combustion engine is started. Therefore, the occurrence of misfire or the occurrence of a combustion delay is determined only until a certain time has elapsed since the internal combustion engine is started, and the above-described operation is performed when it is determined that a misfire or a combustion delay has occurred. In this manner, the fuel injection amount, the injection timing, and the ECU opening degree may be changed. According to this, the calculation load of the ECU 30 is reduced, and in some cases, the operation state of the internal combustion engine is maintained in a preferable state as a whole.
[0094]
In the above-described embodiment, when it is determined that misfire has occurred, the fuel injection amount, the injection timing, and the EGR opening degree are controlled according to the control method described above. However, only one or two of these fuel injection amount, injection timing, and EGR opening may be controlled. Therefore, it can be said that the present invention controls at least one of the fuel injection amount, the injection timing, and the EGR opening degree according to the control method described above when it is determined that misfire has occurred.
[0095]
In the above-described embodiment, the presence or absence of misfire in the combustion chamber is determined by directly using the peak timing. However, the presence or absence of misfire in the combustion chamber is determined using another parameter obtained by using the peak timing. You may make it determine. Therefore, the present invention can be said to determine the presence or absence of misfire in the combustion chamber based on the peak timing.
[0096]
In the above-described embodiment, misfire has occurred when the peak timing is earlier than the compression top dead center or when it is near the reference timing (specifically, compression top dead center). It is determined that the combustion delay has occurred when the peak timing is relatively late. Here, considering that these misfires and combustion delays are one form of combustion failure, it can be said that the present invention determines that a combustion failure has occurred in the combustion chamber based on the peak timing.
[0097]
In the above-described embodiment, the presence or absence of misfire in the combustion chamber is determined by directly using the PV value. However, the presence or absence of misfire in the combustion chamber is determined using another parameter converted from the PV value. It may be. Therefore, the present invention can be said to determine the presence or absence of misfire in the combustion chamber based on the PV value.
[0098]
In the above-described embodiment, it is determined that a misfire has occurred when the PV value is zero or a value near zero, and that a combustion delay has occurred when the PV value is relatively small. . Here, considering that these misfires and combustion delays are one form of combustion failure, the present invention indicates that combustion failure occurs in the combustion chamber when the PV value is smaller than a predetermined value. It can be said that it is a judgment.
【The invention's effect】
According to the present invention, it is possible to accurately determine the presence or absence of combustion failure.
[Brief description of the drawings]
FIG. 1 is an overall view of an internal combustion engine to which the present invention is applied.
FIG. 2 is a diagram showing a map used for calculating a target fuel injection amount TQ based on an engine speed N and a required load L.
FIG. 3 is a view showing a map used for calculating a target energization time ΤBase based on a target fuel injection amount TQ.
FIG. 4 is a diagram showing changes in PV value.
FIG. 5 is a diagram showing a map used for calculating a target PV difference TΔPV based on a target fuel injection amount TQ.
FIG. 6 is a diagram showing a map used for calculating a target injection timing TT based on an engine speed N and a required load L.
FIG. 7 is a diagram showing a map used for calculating a target peak timing TCAp based on an engine speed N and a required load L.
FIG. 8 is a diagram showing a map used for calculating a basic EGR opening degree TDbase based on an engine speed N and a required load L.
FIG. 9 is a diagram for explaining an example of control of the fuel injection amount according to the embodiment of the present invention.
10A is a diagram showing a map used for calculating a target fuel injection amount TQ based on the engine speed N, and FIG. 10B shows a target PV difference TΔPV based on the engine speed N; It is a figure which shows the map used in order to calculate.
FIG. 11 is a diagram showing a part of a flowchart for correcting a fuel injection amount;
FIG. 12 is a diagram showing a part of a flowchart for correcting the fuel injection amount.
13 is an enlarged view of a part of FIG.
14 is a diagram for explaining calculation formulas in the flowcharts shown in FIGS. 11 and 12. FIG.
[Explanation of symbols]
1 ... Engine body
6 ... Fuel injection valve
7 ... Intake valve
9 ... Exhaust valve
22 ... EGR passage
23 ... EGR control valve
47 ... In-cylinder pressure sensor

Claims (13)

Control of an internal combustion engine comprising in-cylinder pressure detecting means for detecting the pressure in the combustion chamber of the internal combustion engine, and calculating means for calculating the product of the pressure in the combustion chamber detected by the in-cylinder pressure detecting means and the volume of the combustion chamber The apparatus comprises timing detection means for detecting, as a peak timing, a timing at which the product calculated by the calculation means is maximum, and combustion failure determination means for determining whether there is a combustion failure in the combustion chamber based on the peak timing. A control device. 2. The control device according to claim 1, wherein the combustion failure determination unit determines that the combustion failure in the combustion chamber is misfire when the peak timing is earlier than the top dead center of the engine compression stroke. . The timing detection means detects a timing at which the product calculated by the calculation means becomes maximum when combustion is not performed in the combustion chamber as a reference timing, and the combustion failure determination means detects the peak timing near the reference timing. The control device according to claim 1, wherein it is determined that a combustion failure in the combustion chamber is a misfire based on the timing. Control means for controlling the timing at which fuel is injected from the fuel injection valve so that the peak timing becomes the target timing is further provided, and the control means determines that the combustion failure in the combustion chamber is misfiring by the combustion failure determination means. 4. The control device according to claim 2, wherein when the operation is performed, a timing at which fuel is injected from the fuel injection valve is controlled so that a timing later than the peak timing becomes the target timing. 5. The internal combustion engine has exhaust introduction means for reintroducing exhaust gas discharged from the combustion chamber into the combustion chamber, and the control device reintroduces into the combustion chamber by the exhaust introduction means so that the peak timing becomes the target timing. And a control means for controlling the amount of exhaust gas to be emitted. When the combustion failure determination means determines that the combustion failure in the combustion chamber is misfire, a timing later than the peak timing is set to the target time. 4. The control apparatus according to claim 2, wherein the amount of exhaust gas reintroduced into the combustion chamber by the exhaust gas introduction means is controlled so as to be timed. The combustion failure determination means determines that the combustion failure in the combustion chamber is a combustion delay when the peak timing is later than a predetermined timing later than the top dead center of the engine compression stroke. The control device according to claim 1. Control of an internal combustion engine comprising in-cylinder pressure detecting means for detecting the pressure in the combustion chamber of the internal combustion engine, and calculating means for calculating the product of the pressure in the combustion chamber detected by the in-cylinder pressure detecting means and the volume of the combustion chamber A control apparatus comprising: a combustion failure determination unit that determines whether or not there is a combustion failure in the combustion chamber based on the product calculated by the calculation unit. 8. The control apparatus according to claim 7, wherein the combustion failure determination means determines that the combustion failure in the combustion chamber is misfire when the product calculated by the calculation means is substantially zero. Timing detection means for detecting a timing at which the product calculated by the calculation means is maximum as a peak timing, and control means for controlling the timing at which fuel is injected from the fuel injection valve so that the peak timing becomes the target timing. The control means injects fuel from the fuel injection valve so that a timing later than the peak timing becomes the target timing when the combustion failure determination means determines that the combustion failure in the combustion chamber is misfire. The control apparatus according to claim 8, wherein the control timing is controlled. The internal combustion engine has exhaust introduction means for reintroducing exhaust gas discharged from the combustion chamber into the combustion chamber, and the control device reintroduces into the combustion chamber by the exhaust introduction means so that the peak timing becomes the target timing. And a control means for controlling the amount of exhaust gas to be emitted. When the combustion failure determination means determines that the combustion failure in the combustion chamber is misfire, a timing later than the peak timing is set to the target time. 9. The control apparatus according to claim 8, wherein the amount of exhaust gas reintroduced into the combustion chamber by the exhaust introduction means is controlled so as to be timed. 8. The control according to claim 7, wherein the combustion failure determination means determines that the combustion failure in the combustion chamber is a combustion delay when the product calculated by the calculation means is smaller than a predetermined value. apparatus. The combustion improvement means for improving the combustion in the combustion chamber when the combustion failure determination means determines that the combustion in the combustion chamber is defective, further comprising: a combustion improvement means. The control device described. Control means for controlling the amount of fuel injected from the fuel injection valve by the combustion improving means, control means for controlling timing for injecting fuel from the fuel injection valve, and exhausted from the combustion chamber and reintroduced into the combustion chamber At least one of control means for controlling the amount of exhaust gas, and the control means is an amount of fuel to be injected from the fuel injection valve when the combustion failure judgment means judges that the combustion in the combustion chamber is bad. At least one of a decrease in the amount of exhaust gas, a lead angle at which fuel is injected from the fuel injection valve, and a decrease in the amount of exhaust gas discharged from the combustion chamber and reintroduced into the combustion chamber. The control device according to claim 12.

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