JP2004251136A - Fuel aspect estimating device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately estimate the concentration of a single component in fuel. <P>SOLUTION: This fuel aspect estimating device for an internal combustion engine for estimating the concentration of a single component in fuel on the basis of an exhaust air-fuel ratio has an oil diluting fuel rate computing means for computing an oil diluting fuel rate for diluting engine oil leaked from a clearance between a piston and a cylinder, and a means for estimating an evaporation fuel rate in blow-by gas evaporated in the blow-by gas in oil diluting fuel for diluting the engine oil. The ratio of the evaporation fuel rate in the blow-by gas in relation to a representative value of a fuel injection quantity is computed, and when the computed ratio is a redetermined value or higher, the single-component concentration estimation of the fuel is inhibited. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel property estimation device for an internal combustion engine.
[0002]
[Prior art]
There is an automobile 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.
[0003]
Alcohol has a different C (carbon) atom content from normal gasoline (mixed fuel). Therefore, when supplying a mixed fuel of alcohol and gasoline to an internal combustion engine used for a flexible fuel vehicle, the alcohol in the fuel is used. It is necessary to adjust the fuel injection amount according to the concentration.
[0004]
For this reason, in such a flexible fuel vehicle, the alcohol concentration in the fuel is detected by an alcohol concentration sensor provided in the fuel tank, and when the alcohol concentration sensor fails, the alcohol concentration is calculated based on the exhaust air-fuel ratio. There is conventionally known an apparatus for estimating an alcohol concentration based on a correlation between an average value of an air-fuel ratio feedback correction coefficient and an alcohol concentration (see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-5-163992 (pages 1-4, FIG. 5)
[0006]
[Problems to be solved by the invention]
Also, when the oil-diluted fuel that leaks out of the gap between the piston and the cylinder and dilutes the engine oil evaporates from the engine oil and is drawn into the intake system from the blow-by system, the exhaust air-fuel ratio changes to the oil dilution that evaporates from the engine oil It is known that the fuel is affected by the fuel and adversely affects the exhaust air-fuel ratio.
[0007]
That is, when estimating the alcohol concentration in the fuel based on the exhaust air-fuel ratio as in the prior art, the exhaust air-fuel ratio is affected by the oil-diluted fuel evaporated from the engine oil. There is a possibility that estimation cannot be performed well.
[0008]
[Means for Solving the Problems]
Therefore, the fuel property estimating apparatus for an internal combustion engine according to the present invention comprises: an oil-diluted fuel amount calculating means for calculating an oil-diluted fuel amount; Means for estimating the amount of fuel evaporated in blow-by gas for estimating the amount of fuel. The ratio of the amount of fuel evaporated in blow-by gas to the representative value of the fuel injection amount is calculated. It is characterized in that the estimation of the concentration of one component is prohibited.
[0009]
【The invention's effect】
According to the present invention, it is possible to remove the influence of the blow-by mixed fuel, which is one of the dominant factors in the deterioration of the accuracy of the estimation of the concentration of a single component in the fuel, so that the accuracy of the estimated value of the concentration of the single component in the fuel is reduced. Can be improved.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 shows a schematic configuration of a fuel property estimation device for an internal combustion engine according to one 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 to the combustion chamber 2 via an exhaust valve 5.
[0012]
In the intake passage 4, an air cleaner 7, an air flow meter 8 for detecting an intake air amount, a throttle valve 9 for controlling the intake air amount, and a fuel injection valve 11 for injecting fuel during intake are arranged.
[0013]
The fuel injection valve 11 injects and supplies fuel during intake so as to attain a predetermined air-fuel ratio in accordance with an operation condition by an injection command signal from an engine control unit 12 (hereinafter, referred to as ECU).
[0014]
An oxygen concentration sensor 13 for detecting the oxygen concentration in the exhaust gas and a three-way catalyst 14 are provided in the exhaust passage 6.
[0015]
The three-way catalyst 14 can simultaneously purify NOx, HC, and CO in the exhaust gas with the maximum conversion efficiency when the air-fuel ratio is in a so-called window centered on the stoichiometric air-fuel ratio. The feedback control of the air-fuel ratio is performed so that the exhaust air-fuel ratio fluctuates within the range of the above window based on the output from the oxygen concentration sensor 13 provided in the above.
[0016]
The ECU 12 includes a water temperature sensor 15 for detecting the temperature of the cooling water of the engine body 1, a crank angle sensor 16 for detecting the engine speed, an outside air temperature sensor 17 for detecting the outside air temperature, and a vehicle speed sensor 18 for detecting the vehicle speed. Is input.
[0017]
Here, during the operation of the engine, when a part of the fuel adheres to the inner wall surface of the cylinder and leaks from the gap between the piston and the cylinder to dilute engine oil, so-called oil dilution occurs, and the fuel is burned in the combustion chamber 2. As the fuel amount decreases, the air-fuel ratio becomes excessively lean (air rich), which may adversely affect drivability and exhaust performance. Also, when the fuel that dilutes the engine oil by oil dilution evaporates from the engine oil and is drawn into the intake system from the blow-by system or the like, the air-fuel ratio becomes excessively rich (fuel rich), and the drivability increases. And exhaust performance may be adversely affected.
[0018]
First, the fuel property estimation device estimates an oil dilution fuel amount OF mixed into engine oil by oil dilution according to the following procedure.
[0019]
The flowchart shown in FIG. 2 is executed every predetermined time, and shows the entire flowchart for obtaining the oil dilution fuel amount OF.
[0020]
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 dilution fuel amount is calculated.
[0021]
In S2 comprising the second subroutine (details will be described later), the reduction ratio B of the oil dilution fuel amount is calculated.
[0022]
In S3, the change amount COF of the oil dilution fuel amount is calculated using the increase amount A of the oil dilution fuel amount and the decrease ratio B of the oil dilution fuel amount. That is, the change amount COF is calculated based on the decreasing speed of the oil dilution fuel in the engine oil. Here, OF _n-1 is the oil dilution fuel amount calculated last time. Then, in S4, the oil dilution fuel amount OF is calculated.
[0023]
FIG. 3 shows a control flow in the first subroutine described above.
[0024]
In S11, a fuel drop rate C, which is an increase rate of the increase amount A, is calculated with reference to a MOFD map (described later). FIG. 4 shows a characteristic example of the MOFD map. This MOFD map is for calculating 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 lower the engine speed, the lower the fuel drop rate C As the cylinder wall temperature TC decreases, the fuel drop rate C increases. This is because it is considered that when the engine is running at a low speed, the gas flow is small, the fuel is poorly vaporized and atomized, and the fuel easily adheres to the wall surface. The cylinder wall temperature TC depends on the fuel volatilization characteristics.
[0025]
In S12, the load correction ratio D is calculated with reference to a load correction table (described later). FIG. 5 shows a characteristic example of the load correction table. The load correction table is for calculating a load correction rate D from a basic injection amount Tp (described later) obtained from an intake air amount Qa obtained from an output of the air flow meter 8 and an engine speed Ne as an engine load. As the unburned fuel ratio in the combustion chamber 2 increases, the load correction rate D increases. This is because it is considered that the fuel volatility changes depending on the pressure.
[0026]
In S13, the increase amount A is calculated using 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.
[0027]
FIG. 6 shows a control flow in the second subroutine described above. In the second subroutine, in S21, a reduction rate B, which is an evaporation rate of oil-diluted fuel from engine oil, is calculated with reference to a MOFU map (described later). FIG. 7 shows a characteristic example of the MOFU map. This MOFU map is for calculating the reduction ratio B from the oil temperature TO and the engine speed Ne. The correlation between the decrease rate and the oil temperature TO is such that the higher the oil temperature TO is, the larger the decrease rate B is, due to the volatility of the fuel. In addition, the correlation between the decrease rate and the engine speed Ne is that the evaporation of the fuel in the engine oil is promoted by the oil stirring by the oil pump and the oil stirring by the counterweight of the crankshaft. The higher the rotation speed Ne, the greater the decrease rate B.
[0028]
Next, a control flow for predicting the cylinder wall temperature TC used when calculating the increase amount A is shown in FIG.
[0029]
First, in S31, it is determined whether the engine has been started or the ECU 12 has been initially energized. If the engine has been started or the ECU 12 has been initially energized, the process proceeds to S32, in which the cylinder wall temperature TC is determined. the value of the initial value TC ₀ as cooling water temperature Tw and equivalence of the engine, and further comprising a temperature rise of the next operation.
[0030]
If it is determined in S31 that it is neither the engine start nor the initial energization of the ECU 12, the process proceeds to S33, in which it is determined whether the engine is in a fuel cut state. The process proceeds to S35 if the engine is not under fuel cut.
[0031]
If the engine is in the fuel cut state, the cylinder wall temperature TC converges toward the engine cooling water temperature Tw. Therefore, in S34, the temperature rise equilibrium temperature TCH from the engine cooling water temperature Tw is set to zero (TCH = 0). .
[0032]
On the other hand, if the engine is not in the fuel cut state, a temperature rise equilibrium temperature TCH which is a temperature difference between the cylinder wall temperature TC and the engine cooling water temperature Tw is calculated in S35 with reference to an MTCH map (described later). FIG. 9 shows a characteristic example of the MTCH map. This MTCH map calculates the temperature rise equilibrium temperature TCH 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 and the higher the basic injection amount Tp, that is, the higher the engine load, the higher the value.
[0033]
In S36, a temperature change rate KTC corresponding to a temperature time constant is calculated with reference to a KTC map (described later). FIG. 10 shows a characteristic example of the KTC map. This KTC map calculates the temperature change ratio KTC using the engine speed Ne and the basic injection amount Tp. The rate of temperature change KTC has a large influence on the engine speed Ne because heat flow to the cylinder wall is dominated by the gas flow rate. I have. In other words, the temperature change rate KTC increases as the engine speed Ne increases and the basic injection amount Tp increases.
[0034]
In the present embodiment, a method of calculating the temperature rise equilibrium temperature TCH and the temperature change ratio KTC from a map in which the engine speed Ne and the basic injection amount Tp are assigned is presented. It is also possible to prepare a calculation table to which the intake air amount Qa, which is a detection signal from the meter, is allocated, and obtain the calculation table using these calculation tables.
[0035]
Next, in S37, an instantaneous predicted temperature DTC is obtained from the temperature rise equilibrium temperature TCH and the temperature change ratio KTC. The predicted temperature DTC is a temperature difference between the engine coolant temperature _Tw, represented by _{DTC n = DTC n-1 +} (TCH-DTC n-1) × KTC. This equation is a temporary delay equation, and makes the predicted temperature DTC follow the temperature rise equilibrium temperature TCH with a temporary delay. The reason for the temporary delay is that it is considered that the ratio is theoretically fixed at a constant rate depending on the balance with the heat escape, and therefore, it is considered to be the same as the experienced valve temperature rise waveform actually measured by the inventors. DTC _n-1 is the predicted temperature at the time of the previous calculation.
[0036]
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 temperature rises from the engine coolant temperature Tw, the engine coolant temperature Tw is added last.
[0037]
In this embodiment, an example in which the cylinder wall temperature TC is predicted has been described. However, this is to provide a system at a low cost, and even if a temperature sensor is embedded in the cylinder to directly detect the cylinder wall temperature. There is no problem, and the accuracy is higher.
[0038]
Next, FIG. 11 shows a prediction control flow of the oil temperature TO used when calculating the oil reduction ratio B using the MOFU map of FIG. 7 described above.
[0039]
In S41, it is determined whether the engine is started or the ECU 12 is first energized. If the engine is started or the ECU 12 is energized for the first time, the process proceeds to S42, and the value of TO ₀ is set to the value of the engine. The same value as the cooling water temperature Tw is set.
[0040]
If it is determined in S41 that it is neither the start of the engine nor the first energization of the ECU 12, the process proceeds to S43.
[0041]
In S43, the heat flow TTW between the engine oil and the engine cooling water is calculated using the engine cooling water temperature Tw, TTWS, and the oil temperature TOn _-1 at the previous calculation. TTWn = (Tw−TO _n−1 ) × TTWS. That is, since the heat transfer amount is proportional to the temperature difference and is a function of the flow velocity, it is obtained by multiplying the TTWS obtained from the engine speed Ne.
[0042]
FIG. 12 shows a characteristic example of the TTWS calculation table. TTWS becomes a large value in proportion to the engine speed Ne. Here, when calculating the TTWS, the engine speed Ne was used because the engine coolant or the cylinder block and the cylinder head in contact with the engine coolant and the heat transfer between the engine oil and the engine oil were performed by turning the oil pump. This is because the rotation speed is proportional to Ne. In addition, there is a portion that is transmitted through the oil pan, but this can be dealt with by appropriately fitting a clog to the characteristics shown in FIG.
[0043]
In S44, the heat flow TTC with the combustion is calculated using the engine coolant temperature Tw, TTCT, and TTCN. _{TTC n = (TTCT-TO n} -1) × TTCN.
[0044]
Here, FIG. 13 shows a characteristic example of the TTCT calculation table, and FIG. 14 shows a characteristic example of the TTCN calculation table. TTCT is the temperature of the piston cylinder wall, and is related to the combustion temperature. Therefore, TTCT is obtained from the calculation table of FIG. 13 using the product of the fuel injection amount Te and the engine speed Ne. TTCN is an engine oil flow velocity for heat transfer, which is obtained from the calculation table in FIG. 14 using the engine speed Ne.
[0045]
In S45, the amount of heat radiation 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. 15 shows an example of the characteristics of the TTAVSP calculation table.
[0046]
Then, in S46, it calculates the oil temperature TO _{n. TO n = TO n-1 +} TTWn + TTC n -TTA n. In other words, the formula for calculating the oil temperature TO _n shown in S46, the engine oil is warmed by the piston cylinder by the combustion and engine coolant, is a formula that models the phenomenon that is cooled by running wind (engine cooling water) .
[0047]
The oil temperature TO thus obtained is used for calculating the evaporation of the oil-diluted fuel.
[0048]
In the present embodiment, an example of predicting the oil temperature TO has been described. However, this is to provide a system at a low cost, and the temperature of the engine oil may be directly detected by a temperature sensor. , Which results in higher accuracy.
[0049]
In this embodiment, the oil pan is cooled by the outside air temperature Ta and the hot air from the radiator is neglected. However, in the case of a vehicle that receives a lot of hot air from the radiator, the hot air from the radiator is considered. If Ta is used after correction, the accuracy can be improved.
[0050]
FIG. 16 shows a case where the fuel injection pulse width Ti calculated using the fuel injection amount Te determined by the operating state of the engine in the engine performing the air-fuel ratio control is corrected according to the oil dilution fuel amount OF. Is a flowchart showing the flow of the control, which is executed at predetermined time intervals.
[0051]
In S51, a basic injection amount Tp is calculated. The basic injection amount Tp is obtained by multiplying the intake air amount per engine revolution (Qa / Ne) 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. Is calculated. Here, the basic injection amount Tp is a representative value of the engine load, which is a basis for calculating the fuel injection amount Te described above.
[0052]
In S52, an air-fuel ratio correction coefficient KMR is calculated from a map to which the engine speed Ne and the throttle valve opening are assigned. The map for calculating the air-fuel ratio correction coefficient KMR is stored in the ECU 12 in advance.
[0053]
In S53, a water temperature increase correction coefficient KTW is calculated from the table to which the engine cooling water temperature Tw is allocated. The table for calculating the water temperature increase correction coefficient KTW is stored in the ECU 12 in advance.
[0054]
In S54, the target fuel-air ratio equivalent amount TFBYA is calculated using the oil drop rate C and the load correction rate D calculated by the above-described oil dilution fuel amount estimation device. TFBYA = 1 + KMR + KTW + (C × D × GUB). Here, GUB is set so that GUB = (H1 + H2) / H2, where H1 is the discharge amount to the exhaust system and H2 is the oil dilution fuel amount. Value. In other words, the product of the oil drop rate C and the load correction rate D is multiplied by GUB because the fuel adhering to the cylinder wall includes fuel that is scraped by the piston and becomes oil-diluted fuel that dilutes engine oil, and burns. Some are discarded from the exhaust system, and are multiplied by a predetermined constant GUB in anticipation of that amount.
[0055]
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, which 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 the above α, and KTR is a transient correction coefficient representing a correction amount of wall-flow fuel.
[0056]
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 which is a correction amount of a difference between the energization time of the fuel injection valve 11 and the actual injection time.
[0057]
Then, 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.
[0058]
Since fuel containing alcohol has a different C (carbon) atom content from normal gasoline (mixed fuel), a large injection amount is required to obtain the same equivalence ratio. In supplying the mixed fuel to the engine, it is necessary to adjust the fuel injection amount according to the alcohol concentration in the fuel.
[0059]
Therefore, using the detection value of the oxygen concentration sensor 13, the alcohol concentration in the fuel is predicted as quickly and accurately as possible.
[0060]
In the present embodiment, the alcohol concentration in the fuel as the single component concentration in the fuel is estimated by the following procedure. FIG. 17 is a flowchart showing a flow of control for estimating the alcohol concentration in the fuel, which is executed at predetermined time intervals.
[0061]
First, in step 61, the air-fuel ratio feedback correction coefficient α calculated based on the output signal of the oxygen concentration sensor 13 is read.
[0062]
In S62, it is determined whether or not the air-fuel ratio learning condition is satisfied. If the air-fuel ratio learning condition is satisfied, the process proceeds to S63, and the map value of the αm calculation map for each operation region is rewritten. . If the air-fuel ratio learning condition is not satisfied, the process proceeds to S64 without rewriting the map value of each αm calculation map. Here, αm is an air-fuel ratio learning correction coefficient calculated based on α. The air-fuel ratio feedback correction coefficient α and the air-fuel ratio learning correction coefficient αm are parameters used for the above-described air-fuel ratio feedback control, and the fuel injection amount from the fuel injection valve 11 is corrected according to α and αm. . In addition, the calculation method of the air-fuel ratio feedback correction coefficient α and the air-fuel ratio learning correction coefficient αm can be any known calculation method, and thus a detailed description of these calculation methods is omitted.
[0063]
In S64, the air-fuel ratio learning correction coefficient αm as the air-fuel ratio correction amount is obtained for each operation region with reference to the current αm map for each operation region.
[0064]
In S65, the blow-by gas influence ratio RTOBL is calculated. The blow-by gas influence ratio RTOBL is obtained from the ratio of the reduction ratio B multiplied by the oil dilution fuel amount OF _n-1 calculated last time and the injection fuel integrated value TISUM per predetermined time, which is the fuel injection amount representative value. It is.
[0065]
Here, the fuel injection integrated value TISUM is obtained by integrating the above-described fuel injection amount Te for each fuel injection timing.
[0066]
That is, in S65, the ratio of the amount of fuel evaporated in the blow-by gas to the integrated fuel injection value TISUM based on the fuel injection amount Te is calculated. The blow-by gas influence ratio RTOBL is substantially equal to the fuel It shows the ratio of the amount of fuel evaporated in the blow-by gas to the injection amount Te.
[0067]
In S66, the magnitude of the blow-by gas influence ratio RTOBL calculated in S65 is compared with a predetermined determination threshold value RTOBLSL, and only when the determination threshold value RTOBLSL is greater than the blow-by gas influence ratio RTOBL, the process proceeds to S67. Otherwise, the process ends without estimating the alcohol concentration in the fuel. That is, when the blow-by gas influence ratio RTOBL is smaller than the determination threshold value RTOBLSL, it is considered that the influence of the fuel vapor from the engine oil is small, and the estimation of the alcohol concentration is permitted. That is, even if the blow-by gas generation amount is somewhat large, it is possible to estimate the alcohol concentration in the fuel when the fuel injection amount itself is large.
[0068]
In S67, it is determined whether or not other permission conditions for performing the alcohol concentration estimation are satisfied. That is, the alcohol concentration estimation requires permission conditions in addition to the condition relating to the blow-by gas (S66). In S67, the water temperature, the time after engine start, the progress of the air-fuel ratio learning control, the refueling history, and the like are determined. It is determined whether or not the condition is satisfied. If the condition is satisfied, the process proceeds to S68. If the condition is not satisfied, the process ends without performing the alcohol concentration estimation.
[0069]
In S68, the average value of αm in the representative rotational load region among the αm values in each operation region obtained in S64, that is, the average value of αm in approximately four regions frequently used as an engine, is used as shown in FIG. Is calculated from the map shown in FIG. Here, the above-mentioned four regions are regions where the frequency of use as the engine is relatively high and a region where the amount of intake air is not too small is selected. This region secures the learning frequency and evaporates from the engine oil, for example. This is to select a relatively large air amount region that is not easily affected by the oil dilution fuel.
[0070]
Also, in FIG. 18, the alcohol concentration has a characteristic of having a dead zone with respect to the average value of αm. This is because when alcohol is filled with gasoline or when a standard blend fuel (gasoline-alcohol fuel) is used. ) Is a characteristic set to use a stable control value (control constant). Here, the above-mentioned control values include ignition timing-related, fuel wall flow-related, so-called λ control control ternary point adjustment constant, cooling increase, and the like. If these values fluctuate, the reproducibility of emission deteriorates. Therefore, it is a dead zone.
[0071]
As described above, in the fuel property estimation device for the internal combustion engine described above, the ratio of the decrease ratio B multiplied by the previously calculated oil dilution fuel amount OF _n-1 to the integrated fuel injection value TISUM per predetermined time is determined by the ratio. When the blow-by gas influence ratio RTOBL is larger than the determination threshold value RTOBLSL, it is considered that the blow-by gas has a large effect on the exhaust air-fuel ratio, and the estimation of the alcohol concentration in the fuel is prohibited. In other words, when the degree of influence of the evaporated fuel in the blow-by gas on the exhaust air-fuel ratio is large, the estimation of the alcohol concentration in the fuel based on the exhaust air-fuel ratio is prohibited, thereby reducing the accuracy of the alcohol concentration estimated value. Since the influence of the fuel mixed with blow-by, which is one of the dominant factors, can be removed, the accuracy of the estimated alcohol concentration can be improved.
[0072]
In the above-described embodiment, the integrated fuel injection value per predetermined time TISUM is used as the fuel injection amount representative value. However, the fuel injection amount representative value is not limited to the injected fuel integrated value TISUM. For example, the intake air amount Qa detected by the air flow meter 8 can be used as the fuel injection amount representative value. However, the determination threshold value RTOBLSL is reset according to the parameter used as the fuel injection amount representative value.
[0073]
Further, in the above-described embodiment, the amount of decrease in the amount of the oil-diluted fuel is calculated by calculating the amount of the oil-diluted fuel. However, the present invention is not limited to this. It is also possible to determine the rate of decrease in the oil-diluted fuel ratio based on this detection value.
[0074]
The technical ideas of the present invention that can be grasped from the above embodiments will be listed together with their effects.
[0075]
(1) A fuel property estimation device for an internal combustion engine that estimates the concentration of a single component in fuel based on an exhaust air-fuel ratio calculates an oil dilution fuel amount that leaks from a gap between a piston and a cylinder to dilute engine oil. Fuel evaporating fuel estimating means for estimating the amount of fuel evaporated in the blow-by gas evaporating into the blow-by gas of the oil-diluted fuel for diluting the engine oil. The ratio of the amount of fuel evaporated in the blow-by gas to the representative amount is calculated. If the ratio is equal to or greater than a predetermined value, the estimation of the concentration of a single component in the fuel is prohibited. As a result, the influence of the fuel mixed with blow-by, which is one of the dominant factors in the deterioration of the accuracy of the estimation of the concentration of the single component in the fuel, can be removed, and the accuracy of the estimated value of the concentration of the single composition in the fuel is improved. be able to.
[0076]
(2) In the fuel property estimating device for an internal combustion engine according to the above (1), more specifically, the means for estimating the amount of fuel evaporated in the blow-by gas uses the blow-by based on the decreasing speed of the oil dilution fuel amount in the engine oil. The amount of fuel vapor in the gas is estimated.
[0077]
(3) In the fuel property estimating device for an internal combustion engine according to the above (1), more specifically, the means for estimating the amount of fuel evaporated in the blow-by gas may be based on the decreasing rate of the dilution ratio of the oil dilution fuel in the engine oil. The amount of evaporated fuel in blow-by gas is estimated.
[0078]
(4) The fuel property estimation device for an internal combustion engine according to any one of (1) to (3) uses the fuel injection amount as the fuel injection amount representative value, more specifically.
[0079]
(5) More specifically, the fuel property estimation device for an internal combustion engine according to any one of (1) to (3) uses an intake air amount as a fuel injection amount representative value.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel property estimation device for an internal combustion engine according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a flow of control for calculating an oil dilution fuel amount.
FIG. 3 is a flowchart showing a control flow of a first subroutine of FIG. 2;
FIG. 4 is an explanatory diagram showing a characteristic example of a MOFD map.
FIG. 5 is an explanatory diagram showing a characteristic example of a load correction table.
FIG. 6 is a flowchart showing a control flow of a second subroutine in FIG. 2;
FIG. 7 is an explanatory diagram showing a characteristic example of a MOFU map.
FIG. 8 is a flowchart showing prediction control of a cylinder wall temperature TC.
FIG. 9 is an explanatory diagram showing a characteristic example of an MTCH map.
FIG. 10 is an explanatory diagram showing a characteristic example of a KTC map.
FIG. 11 is a flowchart showing prediction control of an oil temperature TO.
FIG. 12 is an explanatory diagram showing a characteristic example of a TTWS calculation table.
FIG. 13 is an explanatory diagram showing a characteristic example of a TTCT calculation table.
FIG. 14 is an explanatory diagram showing a characteristic example of a TTCN calculation table.
FIG. 15 is an explanatory diagram showing a characteristic example of a TTAVSP calculation table.
FIG. 16 is a flowchart showing a control flow when correcting the fuel injection pulse width Ti according to the oil dilution fuel amount OF.
FIG. 17 is a flowchart showing the flow of control for estimating the alcohol concentration in fuel.
FIG. 18 is an explanatory diagram showing a characteristic example of an alcohol concentration calculation map.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine 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 (5)

In a fuel property estimation device for an internal combustion engine that estimates a single component concentration in fuel based on an exhaust air-fuel ratio,
Oil-diluted fuel amount calculating means for calculating an oil-diluted fuel amount that leaks from a gap between the piston and the cylinder and dilutes engine oil;
A blow-by gas evaporated fuel amount estimating means for estimating the blow-by gas evaporated fuel amount evaporating into the blow-by gas out of the oil diluted fuel for diluting the engine oil,
Calculating the ratio of the amount of fuel evaporated in the blow-by gas to the representative value of the fuel injection amount, and if the ratio is equal to or greater than a predetermined value, estimating the concentration of a single component in the fuel is prohibited. Estimation device. 2. The fuel for an internal combustion engine according to claim 1, wherein the evaporative fuel amount in blow-by gas estimating means estimates the amount of evaporative fuel in blow-by gas based on the decreasing speed of the oil dilution fuel amount in the engine oil. Property estimation device. 2. The internal combustion engine according to claim 1, wherein the evaporative fuel amount in blow-by gas estimating means estimates the amount of evaporative fuel in blow-by gas based on a decreasing speed of a dilution ratio of oil-diluted fuel in engine oil. Fuel property estimation device. 4. The fuel property estimation device for an internal combustion engine according to claim 1, wherein the fuel injection amount is used as the fuel injection amount representative value. 4. The fuel property estimation device for an internal combustion engine according to claim 1, wherein an intake air amount is used as a fuel injection amount representative value.

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