JP4055568B2 - Oil dilution fuel estimation device and control device for internal combustion engine using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil diluted fuel amount estimation device and an internal combustion engine control device using the same.
[0002]
[Prior art]
In an internal combustion engine, so-called oil dilution may occur in which fuel leaks from a gap between a piston and a cylinder to dilute engine oil. In order to suppress the occurrence of such oil dilution, when performing fuel injection during an intake stroke in a direct injection internal combustion engine, based on a parameter representing the ease with which fuel adheres to the internal combustion engine, Conventionally, a fuel injection start time is changed (see Patent Document 1).
[0003]
[Patent Document 1]
JP 2002-13428 A (page 3-4, FIG. 3)
[0004]
[Problems to be solved by the invention]
By the way, the volatility of the fuel mixed in the engine oil is various and has a boiling point of 30 ° C. to 150 ° C. or more. In addition, the fuel adheres to the wall surface in the combustion chamber and mixes with the oil. At that time, the low-volatile high-temperature boiling component dissolves in the oil without burning or evaporating and remains as it is. Evaporation is not promoted unless the temperature is significantly increased. Even if the engine warms up at the water temperature after starting the engine, there is a lot of oil-diluted fuel if the oil temperature is about the same as the water temperature.For example, even when the oil temperature further rises due to climbing after complete warming, etc. Since the fuel evaporates from the oil and is sucked into the engine, an air-fuel ratio error occurs. For example, mis-learning with the air-fuel ratio learning control or misdiagnosis with the fuel system diagnosis is easy. .
[0005]
In particular, in a vehicle called a so-called flexible fuel vehicle (FFV) that can run on a mixed fuel of various compositions of alcohol and gasoline in addition to gasoline, a system that estimates the alcohol concentration using the equivalent ratio deviation is inexpensive. However, the speed of estimation and the accuracy of concentration estimation are required when the fuel is replaced with a different fuel type, and the effect of the evaporated fuel from the oil is not sufficient in the conventional method. As a result, the engine control amount correction using the alcohol concentration estimation result, for example, the ignition timing accuracy due to the difference in the combustion speed due to the fuel, and the transient air-fuel ratio accuracy due to improper wall flow correction due to the difference in volatility are not sufficient, and the exhaust performance There is a problem in that there is a deterioration in operability such as deterioration in variability, hesitation and surge.
[0006]
[Means for Solving the Problems]
The oil diluted fuel amount estimation device according to the present invention is characterized in that the oil diluted fuel amount is calculated in accordance with an oil diluted fuel index set for each predetermined temperature range of the engine. Also, it has an alcohol concentration calculation means for calculating the alcohol concentration in the fuel from the air-fuel ratio deviation, and permits the calculation of the alcohol concentration according to the amount of oil diluted fuel when using fuel mixed with alcohol in gasoline. The alcohol concentration calculation permission condition is set.
[0007]
【The invention's effect】
According to the present invention, since the evaporation state of the oil diluted fuel amount is known for each temperature region, any engine operation history or environment change history is not affected by the oil diluted fuel, that is, the oil diluted fuel condition. A state where there is no influence can be detected.
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0008]
FIG. 1 shows a schematic configuration of a control device for an internal combustion engine according to an embodiment of the present invention. An intake passage 4 is connected to the combustion chamber 2 of the engine body 1 via an intake valve 3, and an exhaust passage 6 is connected via an exhaust valve 5.
[0009]
In the intake passage 4, an air cleaner 7, an air flow meter 8 for detecting the intake air amount, a throttle valve 9 for controlling the intake air amount, and a fuel injection valve 11 for injecting and supplying fuel during intake are disposed.
[0010]
The fuel injection valve 11 injects and supplies fuel during intake air so as to achieve a predetermined air-fuel ratio in accordance with operating conditions by an injection command signal from an engine control unit 12 (hereinafter referred to as ECU).
[0011]
An oxygen concentration sensor 13 that detects the oxygen concentration in the exhaust gas and a three-way catalyst 14 are disposed in the exhaust passage 6.
[0012]
Since the three-way catalyst 14 can simultaneously purify NOx, HC, and CO in the exhaust gas with maximum conversion efficiency when the so-called window centered on the stoichiometric air-fuel ratio has an air-fuel ratio, the ECU 12 has an upstream side of the three-way catalyst 14. The air-fuel ratio feedback control is performed so that the exhaust air-fuel ratio fluctuates with a constant period within the range of the window based on the output from the oxygen concentration sensor 13 provided in the above-mentioned window.
[0013]
The ECU 12 includes a water temperature sensor 15 that detects the coolant temperature of the engine body 1, a crank angle sensor 16 that detects the engine speed, an outside air temperature sensor 17 that detects outside air temperature, and a vehicle speed sensor 18 that detects vehicle speed. Signal is being input.
[0014]
Here, during engine operation, a part of the fuel adheres to the inner wall surface of the cylinder, leaks from the gap between the piston and the cylinder, and so-called oil dilution that dilutes engine oil occurs, so that combustion occurs in the combustion chamber 2. The amount of fuel is reduced, and the air-fuel ratio becomes excessively lean (air rich), which may adversely affect operability and exhaust performance. In addition, if the fuel that has diluted engine oil due to oil dilution evaporates from the engine oil and is sucked into the intake system from a blow-by system or the like, the air-fuel ratio becomes excessively rich (fuel rich), and drivability There is a risk of adversely affecting exhaust performance.
[0015]
Further, as the engine temperature rises (combustion chamber temperature rise), the increase in oil-diluted fuel decreases. Conversely, vaporization, that is, evaporation of oil-diluted fuel mixed in engine oil is promoted as engine temperature rises (oil temperature rise). However, the evaporation of the oil-diluted fuel varies depending on the fuel components (light and heavy). That is, even if light components are mixed in engine oil, they are vaporized from a relatively low temperature. However, heavy components are difficult to vaporize if mixed into engine oil even at relatively high temperatures. Therefore, the amount of oil-diluted fuel mixed in the engine oil varies depending on the history of the oil temperature immediately after the start.
[0016]
Therefore, in the oil diluted fuel estimation device according to the first embodiment of the present invention, the oil diluted fuel amount OF mixed in the engine oil by oil dilution is estimated by the following procedure.
[0017]
The flowchart shown in FIG. 2 is executed every predetermined time, and shows an overall flowchart for obtaining the oil diluted fuel amount OF.
[0018]
In step 1 (hereinafter simply referred to as S) consisting of a first subroutine (details will be described later), an increase amount A of the oil diluted fuel amount is calculated.
[0019]
In S2 including the second subroutine (details will be described later), the evaporation rate of the oil diluted fuel from the oil, that is, the reduction rate B of the oil diluted fuel amount is calculated.
[0020]
In S3 and S4, the content (oil diluted fuel index) of the oil diluted fuel amount table TOF (described later) allocated by the oil temperature TO is calculated by the amount A of increase in the oil diluted fuel amount calculated in S1 and S2. The oil dilution fuel amount reduction rate B is updated.
[0021]
FIG. 3 is an explanatory diagram schematically showing the oil diluted fuel amount table TOF. The oil temperature region is set for each predetermined temperature region, for example, every 0 (° C.) to 10 (° C.). The total oil-diluted fuel amount OF is estimated from the sum of the oil-diluted fuel amount (oil-diluted fuel index) for each temperature region, that is, the area between the characteristic line illustrated in FIG. 3 and the horizontal axis in FIG. To do. Here, each oil temperature region corresponds to the fuel component (light and heavy) mixed in the engine oil, and the heavy component (boiling point is high and difficult to evaporate) toward the right side of the horizontal axis in FIG. ) Represents the remaining amount of oil-diluted fuel.
[0022]
As shown in FIG. 3, the amount of oil-diluted fuel for each temperature component mixed in the engine oil changes according to the history of the oil temperature immediately after the start. In other words, the light component of the oil diluted fuel increases immediately after starting, and even at a relatively low temperature, the light component vaporizes more than the accumulation of the heavy component of the oil diluted fuel, and the amount of oil diluted fuel decreases. There is a tendency. When the warm-up state ends, a certain temperature history is passed. For example, when the oil temperature reaches M (° C.), the light components are completely vaporized at that time. And few. On the other hand, even if the warm-up is completed, if the oil temperature further rises to N (° C.), the temperature at which the heavy components can be vaporized is increased, and the amount of fuel vaporized further increases to n.
[0023]
Therefore, in S3, the increase amount A calculated in S1 is added and increased for all temperature regions assigned to the oil diluted fuel amount table TOF. Next, in S4, the value assigned to the temperature range lower than the current oil temperature TO is updated as new value = old value−old value × B. The new value is the amount of oil diluted fuel for each temperature component after update, and the old value is the amount of oil diluted fuel for each temperature component before update.
[0024]
The oil diluted fuel amount table TOF is a memory that is backed up by the battery and is not erased even when the engine is stopped, and can store the oil diluted fuel amount regardless of the number of engine start times.
[0025]
In S5, the oil diluted fuel amount OF is calculated from the updated oil diluted fuel amount table TOF.
[0026]
FIG. 4 shows a control flow in the first subroutine described above.
[0027]
In S11, referring to a MOFD map (described later), a fuel drop rate C that is an increase rate of the increase amount A is calculated for each temperature region of the oil diluted fuel amount table TOF. FIG. 5 shows a characteristic example of the MOFD map. This MOFD map calculates the fuel drop rate C from the cylinder wall temperature TC (details will be described later) as the engine temperature and the engine speed Ne. The fuel drop rate C decreases as the engine speed decreases. The fuel drop rate C increases as the cylinder wall temperature TC decreases. This is because when the engine is running at a low speed, the gas flow becomes small, the vaporization and atomization of the fuel is poor, and the fuel is likely to adhere to the wall surface. Further, the cylinder wall temperature TC depends on the volatilization characteristics of the fuel.
[0028]
In S12, a load correction rate D is calculated with reference to a load correction table (described later). FIG. 6 shows a characteristic example of the load correction table. The load correction table calculates a load correction factor D from a basic injection amount Tp (described later) obtained from the intake air amount Qa obtained from the output of the air flow meter 8 and the engine speed Ne as an engine load, As the proportion of unburned fuel in the combustion chamber 2 increases, the load correction factor D becomes a large value. This is because a change in fuel volatility due to pressure is considered to have an effect.
[0029]
At S13, the fuel drop rate C, the load correction rate D, the engine speed Ne, and the fuel injection amount Te determined by the operating state of the engine as the engine load are used to calculate the increase amount A, and each temperature of the oil diluted fuel amount table TOF. Calculate for the region.
[0030]
FIG. 7 shows the flow of control in the second subroutine described above. In this second subroutine, in S21, a reduction rate B, which is the evaporation rate of the oil-diluted fuel from the engine oil, is calculated with reference to a MOFU map (described later). FIG. 8 shows a characteristic example of the MOFU map. This MOFU map is used to calculate the reduction rate B from the oil temperature TO and the engine speed Ne. As for the correlation between the reduction rate and the oil temperature TO, the reduction rate B increases as the oil temperature TO increases due to the volatility of the fuel. Further, the correlation between the reduction rate and the engine speed Ne is that the evaporation of the fuel in the engine oil is promoted by the oil agitation by the oil pump and the oil agitation by the counterweight of the crankshaft. The reduction rate B increases as the rotational speed Ne increases.
[0031]
Next, FIG. 9 shows a predictive control flow of the cylinder wall temperature TC used when calculating the increase amount A.
[0032]
First, in S31, it is determined whether the engine is being started or the ECU 12 is being energized for the first time. If the engine is being started or the ECU 12 is being energized for the first time, the process proceeds to S32 and the cylinder wall temperature TC is determined. The initial value TC ₀ is set to the same value as the engine coolant temperature Tw to prepare for the temperature rise in the next calculation.
[0033]
If it is determined in S31 that the engine is not started or the ECU 12 is initially energized, the process proceeds to S33 to determine whether or not the engine is in a fuel cut. If the engine is not under fuel cut, the process proceeds to S35.
[0034]
If the engine is under fuel cut, the cylinder wall temperature TC converges toward the engine cooling water temperature Tw. Therefore, in S34, the equilibrium temperature TCH corresponding to the temperature rise from the engine cooling water temperature Tw is set to zero (TCH = 0). .
[0035]
On the other hand, if the engine is not in the fuel cut, an equilibrium temperature TCH corresponding to a temperature increase that is a temperature difference between the cylinder wall temperature TC and the engine coolant temperature Tw is calculated in S35 with reference to an MTCH map (described later). FIG. 10 shows an example of the characteristics of the MTCH map. This MTCH map is used to calculate the equilibrium temperature TCH corresponding to the temperature rise using the engine speed Ne and the basic injection amount Tp. Since the temperature rise equilibrium temperature TCH has a strong correlation with the combustion temperature, the higher the engine speed Ne, the higher the basic injection amount Tp, that is, the higher the engine load, the higher the value.
[0036]
In S36, a temperature change rate KTC corresponding to a temperature time constant is calculated with reference to a KTC map (described later). FIG. 11 shows a characteristic example of the KTC map. This KTC map calculates the temperature change rate KTC using the engine speed Ne and the basic injection amount Tp. The temperature change rate KTC has a large influence of the engine speed Ne because the gas flow rate is dominant in the heat transfer to the cylinder wall, and has sensitivity to the basic injection amount Tp, that is, the engine load due to the heat transfer due to the pressure. Yes. That is, the temperature change rate KTC increases as the engine speed Ne increases and the basic injection amount Tp increases.
[0037]
In the present embodiment, a method of calculating the equilibrium temperature TCH and the temperature change rate KTC for the temperature increase from a map in which the engine speed Ne and the basic injection amount Tp are assigned is shown. A calculation table to which the intake air amount Qa that is a detection signal from the meter is assigned may be prepared and obtained using these calculation tables.
[0038]
Next, in S37, the predicted temperature DTC is obtained every moment from the equilibrium temperature TCH and the temperature change rate KTC for the temperature increase. The predicted temperature DTC is a temperature difference from the engine coolant temperature Tw, and is expressed by DTC _n = DTC _n-1 + (TCH-DTC _n-1 ) × KTC. This equation is a temporary delay equation that causes the predicted temperature DTC to follow the temperature rise equilibrium temperature TCH with a temporary delay. The reason for the temporary delay is that it seems to change theoretically at a constant rate due to the balance with the escape of heat, and therefore, it was considered to be the same as the rising waveform of the valve temperature that the inventors have actually measured. DTC _n-1 is the predicted temperature at the previous calculation.
[0039]
Then, in S38, the engine cooling water temperature Tw, a value obtained by adding the predicted temperature DTC _n calculated in S37 and the cylinder wall temperature TC _n, terminates the prediction of the cylinder wall temperature TC. That is, since the temperature rise equilibrium temperature TCH and the predicted temperature DTC are the amount of temperature rise from the engine coolant temperature Tw, the engine coolant temperature Tw is finally added.
[0040]
In this embodiment, an example of predicting the cylinder wall temperature TC is shown, but this is for providing a system at a low cost, and even if the temperature of the cylinder wall is directly detected by embedding the temperature sensor in the cylinder. There is no problem, and it is more accurate.
[0041]
Next, FIG. 12 shows a predictive control flow of the oil temperature TO used when calculating the oil reduction rate B (evaporation rate of oil-diluted fuel) using the MOFU map of FIG. 8 described above.
[0042]
In S41, it is determined whether or not the engine is being started or the ECU 12 is being energized for the first time. If the engine is being started or the ECU 12 is being energized for the first time, the process proceeds to S42 and the value of TO ₀ is set. It is set to the same value as the cooling water temperature Tw.
[0043]
If it is determined in S41 that the engine is not started or the ECU 12 is initially energized, the process proceeds to S43.
[0044]
In S43, the heat flow component TTW between the engine oil and the engine coolant is calculated using the engine coolant temperature Tw, TTWS, and the oil temperature TO _n-1 at the previous calculation. TTWn = (Tw−TO _n−1 ) × TTWS. That is, the amount of heat transfer is proportional to the temperature difference and is a function of the flow velocity, and is obtained by multiplying TTWS obtained from the engine speed Ne.
[0045]
FIG. 13 shows an example of characteristics of the TTWS calculation table. TTWS has a large value in proportion to the engine speed Ne. Here, when calculating TTWS, the engine speed Ne is used because the heat transfer between the engine coolant or the cylinder block, the cylinder head in contact with the engine coolant, and the engine oil rotates the oil pump. This is because it is proportional to the rotational speed Ne. Moreover, there is a part transmitted through the oil pan, but this can be dealt with by appropriately correcting the characteristics of FIG.
[0046]
In S44, the heat flow TTC with combustion is calculated using the engine coolant temperature Tw, TTCT, and TTCN. TTC _n = (TTCT−TO _n−1 ) × TTCN.
[0047]
Here, FIG. 14 shows an example of characteristics of a TTCT calculation table, and FIG. 15 shows an example of characteristics of a TTCN calculation table. Since TTCT is the temperature of the piston cylinder wall and is related to the combustion temperature, it is obtained from the calculation table of FIG. 14 using the product of the fuel injection amount Te and the engine speed Ne. TTCN is the engine oil flow rate for heat transfer, and is obtained from the calculation table of FIG. 15 using the engine speed Ne.
[0048]
In S45, a heat release amount TTA to the outside air is calculated. TTA _n = (TO _n-1 -Ta) × TTAVSP. Ta is an outside air temperature as an output signal of the outside air temperature sensor 17, and TTAVSP is a flow rate for heat transfer obtained from an output signal VSP (vehicle speed) of the vehicle speed sensor 18. FIG. 16 shows a characteristic example of a calculation table of TTAVSP.
[0049]
Then, in S46, it calculates the oil temperature TO _{n. TO n = TO n-1 +} TTWn + TTC n -TTA n. That is, the equation for calculating the oil temperature TO _n shown in S46 is a modeled model of the phenomenon in which the engine oil is warmed by the piston cylinder by the engine cooling water and combustion and cooled by the traveling wind (and the engine cooling water). .
[0050]
The oil temperature TO thus obtained is used for the evaporation calculation of the oil diluted fuel.
[0051]
In this embodiment, an example of predicting the oil temperature TO has been shown. However, this is for providing a system at a low cost, and the temperature of the engine oil may be directly detected by a temperature sensor. , It will be more accurate.
[0052]
In this embodiment, the oil pan is cooled by the outside air temperature Ta and the warm air from the radiator is ignored. However, in the case of a vehicle that receives a lot of warm air from the radiator, the warm air from the radiator is considered. If Ta is corrected and used, the accuracy can be increased.
[0053]
In such an oil-diluted fuel amount estimation device, the mixing and evaporating state of the oil-diluted fuel is known for each temperature region, so that any operating history or history of environmental changes is not affected by the oil-diluted fuel, that is, A state where there is no influence of oil-diluted fuel can be detected.
[0054]
Further, since the oil dilution fuel amount (oil dilution estimation index) for each temperature region is set to be variable according to the engine temperature history, that is, the engine temperature, in other words, the oil temperature, the oil dilution fuel is set. The quantity can be estimated accurately. More specifically, by operating the oil dilution fuel amount (oil dilution estimation index) by temperature range assigned to the temperature range below the oil temperature during operation in a decreasing direction, the oil dilution fuel can be reliably evaporated. It is possible to detect a condition with few.
[0055]
The increase amount A of the oil-diluted fuel is uniformly increased in all temperature regions regardless of the current temperature. Thus, a simple method of increasing uniformly regardless of the volatility distribution of gasoline fuel. Even so, it is possible to detect conditions where the evaporation of oil-diluted fuel is low. When pursuing only the accuracy, it is conceivable to predict the fuel component of only the unburned component and increase the table value by its volatilization temperature distribution.However, the unburned combustion component varies greatly depending on the operating conditions, so the accuracy is improved. Hateful. As in the first embodiment described above, uniformly increasing the oil dilute fuel will be dealt with broadly, so that it is difficult to mislearn.
[0056]
In the first embodiment described above, the decrease in the amount of oil-diluted fuel due to evaporation is uniformly reduced regardless of the temperature range, but the region higher than the current temperature region is smaller and the region lower is greatly decreased. It is also possible to handle fuels that evaporate below the boiling point.
[0057]
Next, a second embodiment of the present invention will be described. In the second embodiment, the oil dilution fuel amount estimation device in the first embodiment described above is mounted on an engine that performs air-fuel ratio control, and the oil dilution fuel amount OF calculated by the oil dilution fuel amount estimation device is added. Accordingly, the fuel injection pulse width Ti calculated using the fuel injection amount Te determined by the operating state of the engine is corrected.
[0058]
FIG. 17 is a flowchart showing a specific control flow in the second embodiment.
[0059]
In S51, a basic injection amount Tp is calculated. The basic injection amount Tp is obtained by multiplying the intake air amount (Qa / Ne) per engine rotation by a predetermined constant K using the engine speed Ne and the intake air amount Qa obtained from the output from the air flow meter 8. Calculated. Here, the basic injection amount Tp serves as a basis for calculating the fuel injection amount Te described above, and is a representative value of the engine load.
[0060]
In S52, an air-fuel ratio correction coefficient KMR is calculated from a map in which the engine speed Ne and the throttle valve opening are assigned. A map for calculating the air-fuel ratio correction coefficient KMR is stored in advance in the ECU 12.
[0061]
In S53, the water temperature increase correction coefficient KTW is calculated from the table to which the engine cooling water temperature Tw is assigned. A table for calculating the water temperature increase correction coefficient KTW is stored in advance in the ECU 12.
[0062]
In S54, the target fuel-air ratio equivalent amount TFBYA is calculated using the oil drop rate C and the load correction factor D calculated by the above-described oil diluted fuel amount estimation device. TFBYA = 1 + KMR + KTW + (C × D × GUB). Here, the GUB is set so that GUB = (H1 + H2) / H2 where H1 is the amount discharged to the exhaust system and H2 is the oil diluted fuel. Value. In other words, multiplying the product of the oil drop rate C and the load correction rate D by the GUB is that the fuel adhering to the cylinder wall is burned if it becomes an oil diluted fuel that is scraped off by the piston and dilutes the engine oil. However, some of them are discarded from the exhaust system, and the predetermined constant GUB is multiplied in anticipation of that amount.
[0063]
In S55, the fuel injection amount Te is calculated. Te = Tp × TFBYA × α × αm × KTR. Here, α is an air-fuel ratio feedback correction coefficient, and is calculated based on the output signal of the oxygen concentration sensor 13 by a flowchart different from this flowchart. Αm is an air-fuel ratio learning correction coefficient calculated based on α, and KTR is a transient correction coefficient representing the correction amount of wall flow fuel.
[0064]
In S56, a fuel injection pulse width Ti, which is a pulse width required to inject the fuel injection amount Te described above, is calculated. Ti = Te × KWJ + Ts. Here, KWJ is an injection amount correction coefficient, and Ts is an invalid pulse width that is a correction amount for the difference between the energization time of the fuel injection valve 11 and the actual injection time.
[0065]
In step S57, the fuel injection pulse width Ti is output, and the fuel injection valve 11 is controlled to perform fuel injection with the fuel injection pulse width Ti.
[0066]
In the second embodiment of the present invention, the ECU 12 reduces the memory and reduces the man-hours required by correcting the increase in the amount of unburned fuel by sharing the map and table of the oil dilution fuel amount estimation device. It becomes possible.
[0067]
In the second embodiment, the fuel injection pulse width Ti is corrected by paying attention to the increase amount A of the oil-diluted fuel amount. However, the fuel injection pulse Ti paying attention to the increase amount A and the decrease ratio B. It is also possible to correct. Further, in the MTCH map (FIG. 10) and the KTC map (FIG. 11), it is possible to assign the fuel injection amount Te instead of the basic injection amount Tp. In this case, the oil diluted fuel amount is actually The correction is made according to the fuel injection amount Te injected from the engine.
[0068]
Next, a third embodiment of the present invention will be described.
[0069]
Currently, many cars can burn gasoline with low concentrations of alcohol. In recent years, an automobile called a so-called flexible fuel vehicle (FFV) that can run with a mixed fuel of various compositions of alcohol and gasoline in addition to gasoline has become widely known.
[0070]
Alcohol fuel is required to have a large injection amount in order to obtain the same equivalent ratio as compared with gasoline from the number of atoms of C (carbon), H (hydrogen), and O (oxygen). Therefore, the alcohol concentration in the fuel is predicted as quickly and accurately as possible from the deviation of the feedback control coefficient by the oxygen concentration sensor 13, that is, the air-fuel ratio deviation.
[0071]
Therefore, in the third embodiment, a case will be described in which the techniques of the first and second embodiments described above are applied to an internal combustion engine that uses a fuel containing alcohol.
[0072]
FIG. 18 is a flowchart showing a control flow of alcohol concentration estimation in the third embodiment.
[0073]
In S61, the air-fuel ratio feedback correction coefficient α calculated based on the output signal of the oxygen concentration sensor 13 is read according to a flowchart different from this flowchart.
[0074]
In S62, the oil diluted fuel amount table TOF is referred to from the oil temperature TO, and the oil diluted fuel amount OF at the current temperature is calculated.
[0075]
In S63, it is determined whether or not the oil diluted fuel amount OF calculated in S61 is smaller than a predetermined estimated permitted dilution amount LOF #. If it is smaller, the process proceeds to S64, and if not, the process proceeds to S66.
[0076]
In S64, it is determined whether other learning conditions are satisfied. The prohibition of the learning condition determines not only the oil diluted fuel amount but also other conventionally used conditions and updates the learning value. Examples of prohibition conditions include low water temperature, overheating, during α feedback control, during canister purge cut, or when the purge concentration is low and during acceleration / deceleration.
[0077]
In general, the learning value is often a map of the engine speed Ne and the load Tp, and is exemplified, but is not defined here.
[0078]
Thus, the learned value is retrieved regardless of whether or not the learned value is updated, and is used as fuel injection amount control as αm.
[0079]
In S65, the map value of the αm calculation map for each operation region is rewritten.
[0080]
In S66, the current αm map for each operating region is referred to determine αm for each operating region.
[0081]
In S67, the oil diluted fuel amount table TOF is referred to from the oil temperature TO, and the oil diluted fuel amount OF at the current temperature is calculated.
[0082]
In S68, it is determined whether or not the oil diluted fuel amount OF calculated in S67 is smaller than a predetermined estimated permitted dilution amount LOF #. If the oil diluted fuel amount OF is small, it is considered that the influence of the evaporated fuel from the engine oil is small, and the alcohol concentration The process moves to a path that permits estimation, but the alcohol concentration estimation requires other permission conditions (S69). In this embodiment, the engine cooling water temperature, the time after engine start, and the progress of air-fuel ratio learning control When the conditions such as the refueling history are satisfied, the alcohol concentration is estimated (S70).
[0083]
In S70, an average value of αm in a representative rotational load region among αm for each operation region is calculated. That is, the average value of αm in about four regions is calculated, and the alcohol concentration is calculated from the table shown in FIG. 19 using the result. Here, the above-mentioned four regions are regions that are relatively frequently used as an engine and are selected as regions that do not have a very small intake air amount. This ensures the frequency of learning, for example, evaporates from engine oil. A relatively large air amount region that is not easily affected by the oil-diluted fuel is selected.
[0084]
In S71, the fuel system diagnosis is performed using the average value of αm. That is, it is determined whether or not the average value of αm is larger than the predetermined diagnosis lower limit value and smaller than the predetermined diagnosis upper limit value, and when the average value of αm is within the above range, The process proceeds to S72 and the diagnosis is OK, and if the average value of αm is outside the above range, the process proceeds to S73 and the diagnosis is NG. Here, the fuel system diagnosis is a diagnosis of components that determine the fuel flow rate such as an air flow meter and a fuel injection valve by using an air-fuel learning correction coefficient αm that is a learning value. For example, an average of αm When the value is 80, the diagnosis lower limit value is set, and when the average value of αm is 180, the diagnosis upper limit value is set.
[0085]
As described above, in the third embodiment of the present invention, when the oil diluted fuel amount is smaller than the predetermined value (estimated permitted dilution amount LOF #), the fuel vaporization is small, and the influence on the air-fuel ratio fluctuation is small, the alcohol Permits concentration estimation, air-fuel ratio learning control, and fuel system diagnosis.
[0086]
Therefore, by controlling the engine using the air / fuel learning correction coefficient αm and the alcohol concentration estimated value obtained in this way, the accuracy is excellent because it is not affected by the evaporation of the oil diluted fuel amount. Therefore, an engine with good exhaust performance and driving performance can be supplied.
[0087]
The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.
[0088]
(1) The oil-diluted fuel estimation device determines the amount of oil-diluted fuel that has leaked from the gap between the piston and cylinder and diluted engine oil in accordance with the oil-diluted fuel index set for each predetermined temperature range of the engine. calculate. As a result, since the evaporation state of the oil diluted fuel amount is known for each temperature range, any engine operation history or environmental change history is not affected by the oil diluted fuel, that is, there is no effect of the oil diluted fuel. The state can be detected.
[0089]
(2) In the oil diluted fuel amount estimation device according to (1), the oil diluted fuel index is set to be variable according to the engine temperature history. As a result, the amount of oil-diluted fuel can be estimated more accurately.
[0090]
(3) In the oil dilution fuel amount estimation device according to (1) or (2), an increase amount calculation means for calculating an increase amount of the oil dilution fuel, and a decrease amount calculation for calculating a decrease amount of the oil dilution fuel amount Means, and after updating the oil dilution fuel index using the engine temperature, the increase amount of the oil dilution fuel, and the decrease amount of the oil dilution fuel, according to the updated oil dilution fuel index, Oil diluted fuel amount is calculated. As a result, the amount of evaporation of the oil-diluted fuel from the engine oil is taken into consideration, and the amount of oil-diluted fuel can be estimated with higher accuracy.
[0091]
(4) In the engine dilution fuel amount estimation device described in (3) above, the increase amount of the oil dilution fuel calculated by the increase amount calculation means is calculated according to the engine temperature, the engine speed and the engine load. .
[0092]
(5) In the engine dilution fuel amount estimation device described in (3) above, the increase amount of the oil dilution fuel calculated by the increase amount calculation means is uniformly added to each oil dilution fuel index.
[0093]
(6) In the engine dilution fuel amount estimation device according to any one of (3) to (5), the reduction amount of the oil dilution fuel calculated by the reduction amount calculation means depends on the engine temperature and the engine speed. It has been calculated.
[0094]
(7) In the oil diluted fuel estimation device according to any one of (1) to (6), the temperature of the engine oil is used as the engine temperature.
[0095]
(8) The oil-diluted fuel estimation device according to any one of (1) to (7) described above, having alcohol concentration calculation means for calculating the alcohol concentration in the fuel from the air-fuel ratio deviation, wherein alcohol is mixed in gasoline When fuel is used, an alcohol concentration calculation permission condition for permitting calculation of the alcohol concentration is set according to the amount of oil diluted fuel. The inflow of the oil-diluted fuel into the engine oil and the evaporation of the oil-diluted fuel from the engine oil are constant, and an accurate alcohol concentration can be calculated.
[0096]
(9) In the oil dilution fuel estimation device described in (8) above, at least one of the oil dilution fuel amount is a predetermined value or less or the change in the oil dilution fuel amount is a predetermined value or less depending on the alcohol concentration calculation permission condition. When the condition is met, the calculation of the alcohol concentration is permitted.
[0097]
(10) In the oil diluted fuel estimation device according to any one of (1) to (9), the oil diluted fuel amount is corrected according to the fuel injection amount actually injected from the engine.
[0098]
(11) The control device for the internal combustion engine corrects the fuel injection amount in accordance with the oil diluted fuel amount calculated by the oil diluted fuel estimation device according to any one of (1) to (10). As a result, an appropriate air-fuel ratio can be realized.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of a control device for an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a control flow according to the first embodiment of the present invention.
FIG. 3 is an explanatory diagram schematically showing an oil diluted fuel amount table TOF.
FIG. 4 is a flowchart showing a flow of control of the first subroutine of FIG. 2;
FIG. 5 is an explanatory diagram showing a characteristic example of a MOFD map.
FIG. 6 is an explanatory diagram illustrating a characteristic example of a load correction table.
FIG. 7 is a flowchart showing a flow of control of the second subroutine of FIG. 2;
FIG. 8 is an explanatory diagram showing a characteristic example of a MOFU map.
FIG. 9 is a flowchart showing predictive control of cylinder wall temperature TC.
FIG. 10 is an explanatory diagram showing a characteristic example of an MTCH map.
FIG. 11 is an explanatory diagram showing a characteristic example of a KTC map.
FIG. 12 is a flowchart showing predictive control of an oil temperature TO.
FIG. 13 is an explanatory diagram showing a characteristic example of a TTWS calculation table.
FIG. 14 is an explanatory diagram showing a characteristic example of a TTCT calculation table.
FIG. 15 is an explanatory diagram showing a characteristic example of a TTCN calculation table.
FIG. 16 is an explanatory diagram showing a characteristic example of a TTAVSP calculation table.
FIG. 17 is a flowchart showing a control flow according to the second embodiment of the present invention.
FIG. 18 is a flowchart showing a control flow according to the third embodiment of the present invention.
FIG. 19 is an explanatory diagram showing a characteristic example of an alcohol concentration calculation table.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine main body 2 ... Combustion chamber 3 ... Intake valve 4 ... Intake passage 5 ... Exhaust valve 6 ... Exhaust passage 7 ... Air cleaner 8 ... Air flow meter 9 ... Throttle valve 11 ... Fuel injection valve 12 ... Engine control unit 13 ... Oxygen concentration sensor 14 ... Three-way catalyst 15 ... Water temperature sensor 16 ... Crank angle sensor 17 ... Outside air temperature sensor 18 ... Vehicle speed sensor

Claims (10)

In the oil diluted fuel amount estimation device that calculates the amount of oil diluted fuel that leaks from the gap between the piston and cylinder and dilutes the engine oil,
Having alcohol concentration calculation means for calculating the alcohol concentration in the fuel from the air-fuel ratio deviation;
The oil diluted fuel amount is calculated according to the oil diluted fuel index set for each predetermined temperature range of the engine,
An oil-diluted fuel amount estimation device in which an alcohol concentration calculation permission condition for permitting the calculation of the alcohol concentration is set according to the amount of oil-diluted fuel when using fuel in which alcohol is mixed in gasoline .   2. The oil dilution fuel amount estimation device according to claim 1, wherein the oil dilution fuel index is set to be variable according to the engine temperature history. An increase amount calculating means for calculating an increase amount of the oil diluted fuel;
A decrease amount calculating means for calculating a decrease amount of the oil diluted fuel amount, and the oil diluted fuel index is updated using the engine temperature, the increased amount of the oil diluted fuel, and the decreased amount of the oil diluted fuel. 3. The oil diluted fuel amount estimation device according to claim 1, wherein the oil diluted fuel amount is calculated in accordance with the updated oil diluted fuel index.   The oil dilution fuel amount estimation device according to claim 3, wherein the increase amount of the oil dilution fuel calculated by the increase amount calculation means is calculated according to the engine temperature, the engine speed and the engine load.   4. The oil dilution fuel amount estimation device according to claim 3, wherein the increase amount of the oil dilution fuel calculated by the increase amount calculation means is uniformly added to each of the oil dilution fuel indexes.   6. The oil diluted fuel estimation device according to claim 3, wherein the amount of decrease in the oil diluted fuel calculated by the decrease amount calculating means is calculated according to the engine temperature and the engine speed. .   The oil dilution fuel amount estimation device according to any one of claims 1 to 6, wherein the temperature of the engine oil is used as the engine temperature. According to the alcohol concentration calculation permission condition, the calculation of the alcohol concentration is permitted when at least one of the conditions where the oil diluted fuel amount is a predetermined value or less or the change in the oil diluted fuel amount is a predetermined value or less is satisfied. The oil-diluted fuel estimation device according to any one of claims 1 to 7 . Amount of fuel diluted in oil is actually fuel diluted in oil amount estimating apparatus according to any one of claims 1 to 8, characterized in that it is corrected in accordance with the fuel injection quantity injected from the engine. A control device for an internal combustion engine, wherein the fuel injection amount is corrected in accordance with the oil diluted fuel amount calculated by the oil diluted fuel estimating device according to any one of claims 1 to 9 .

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