JPH10252550A - Fuel property detection device and fuel injection amount control device for internal combustion engine - Google Patents

Abstract

(57) [Problem] To provide a fuel property detection device capable of detecting the property of fuel supplied to an internal combustion engine without using a new sensor. A fuel injection amount of a fuel injection valve is feedback-controlled in accordance with a detection value of an air-fuel ratio sensor provided in an exhaust system of an engine. A fuel property parameter representing a fuel property is detected by using a neural network that inputs an engine operation parameter including a detection value of the air-fuel ratio sensor 22 and a fuel injection amount. Transport delay correction of the fuel injection amount is performed according to the detected fuel property parameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel property estimating apparatus for estimating the property of fuel supplied to an internal combustion engine and a fuel injection quantity control apparatus for controlling an amount of fuel injected into an intake pipe of the internal combustion engine.

[0002]

2. Description of the Related Art Gasoline for internal combustion engines marketed on the market includes light gasoline mainly containing heptane and pentane and heavy gasoline mainly containing benzene and the like. The properties (physical properties such as density and volatility) vary to some extent.
In particular, the difference in volatility (vaporization temperature) greatly affects the gasoline atomization characteristics when gasoline is injected into the intake pipe of the engine and supplied. Therefore, the air-fuel ratio of the air-fuel mixture supplied to the engine combustion chamber is desired. It may cause deviation from the value.

[0003] Therefore, an ultrasonic fuel property sensor is provided in the middle of a fuel supply pipe, and a fuel injection amount is corrected in accordance with a detection value of the sensor to correct an amount of fuel injected into an intake pipe of an internal combustion engine. A control device has been conventionally known (Japanese Patent Application Laid-Open No. H8-177547).

[0004]

However, the provision of a new fuel property sensor complicates the apparatus and increases the cost. Therefore, the property of the fuel in use can be detected without using a new sensor. desirable.

It is common practice to calculate a fuel injection amount in accordance with a detection value of an air-fuel ratio sensor provided in an engine exhaust system and perform feedback control so as to obtain a desired air-fuel ratio. When the fuel ratio sensor is inactive or the like, the feedback control cannot be performed, so that the exhaust gas characteristics may be deteriorated due to the difference in the fuel properties.

[0006] The present invention has been made in view of the above points, and a first object of the present invention is to provide a fuel property detection device capable of detecting fuel properties without using a new sensor. It is a second object of the present invention to provide a fuel injection amount control device capable of detecting a fuel property without using a sensor and appropriately controlling the fuel injection amount.

[0007]

According to a first aspect of the present invention, there is provided a fuel property detecting device for detecting a property of fuel supplied to an internal combustion engine, the apparatus being provided in an exhaust system of the engine. An air-fuel ratio sensor, feedback control means for calculating an amount of fuel supplied to the engine based on a detection value of the air-fuel ratio sensor, and performing feedback control of an air-fuel ratio of an air-fuel mixture supplied to the engine; and at least the air-fuel ratio sensor And a fuel property parameter calculating means for calculating a fuel property parameter representing the property of the fuel by using a neural network which inputs the detected value of the fuel and the amount of fuel supplied to the engine.

According to this configuration, the amount of fuel supplied to the engine is calculated based on the value detected by the air-fuel ratio sensor provided in the exhaust system of the engine, so that the air-fuel ratio of the mixture supplied to the engine is controlled by feedback control. Then, a fuel property parameter representing the property of the fuel is calculated using a neural network that inputs at least the detection value of the air-fuel ratio sensor and the amount of fuel supplied to the engine.

According to a second aspect of the present invention, there is provided a fuel property detecting device for detecting a property of fuel supplied to an internal combustion engine,
An air-fuel ratio sensor provided in an exhaust system of the engine, and a feedback for calculating an amount of fuel to be supplied to the engine based on a detection value of the air-fuel ratio sensor and performing feedback control of an air-fuel ratio of a mixture supplied to the engine. Control means; and fuel property parameter calculating means for calculating a fuel property parameter representing the property of the fuel by using a multiple regression model having at least a detection value of the air-fuel ratio sensor and a fuel amount supplied to the engine as inputs. It is characterized by the following.

According to this configuration, the amount of fuel supplied to the engine is calculated based on the value detected by the air-fuel ratio sensor provided in the exhaust system of the engine, so that the air-fuel ratio of the mixture supplied to the engine is controlled by feedback. Then, a fuel property parameter representing the property of the fuel is calculated using a multiple regression model that receives at least the detection value of the air-fuel ratio sensor and the amount of fuel supplied to the engine.

According to a third aspect of the present invention, an air-fuel ratio sensor provided in an exhaust system of an internal combustion engine and a combustion chamber of the engine are provided in accordance with an operating parameter of the engine including a detection value of the air-fuel ratio sensor. Target fuel amount calculating means for calculating a target fuel amount to be supplied; fuel adhering parameter calculating means for calculating a fuel adhering parameter representing a fuel adhering characteristic in an intake passage according to an operation state of the engine; Based on the above, of the fuel injected from the fuel injection valve, the first fuel amount directly sucked into the combustion chamber and the fuel amount adhering to the wall surface of the intake passage evaporate to the combustion chamber. A fuel amount calculating means for calculating a second fuel amount to be sucked, and correcting the target fuel amount based on the first fuel amount and the second fuel amount to calculate a fuel injection amount by the fuel injection valve. Calculation of fuel injection amount to be calculated A fuel injection amount control device for an internal combustion engine, comprising: a fuel injection parameter control unit that calculates a fuel property parameter representing a property of the fuel by using a neural network that inputs at least a detection value of the air-fuel ratio sensor and the fuel injection quantity. The fuel deposition apparatus further includes property parameter calculation means, wherein the fuel adhesion parameter calculation means calculates the fuel adhesion parameter according to the fuel property parameter.

According to this configuration, based on the fuel adhesion parameter representing the fuel adhesion characteristic in the intake passage, of the fuel injected from the fuel injection valve, the first fuel amount directly sucked into the combustion chamber and The amount of fuel adhering to the wall of the intake passage evaporates and a second amount of fuel sucked into the combustion chamber is calculated, and based on the first amount of fuel and the second amount of fuel,
The target fuel amount to be supplied to the combustion chamber is corrected, and the fuel injection amount is calculated. Then, a fuel property parameter representing the property of the fuel is calculated using a neural network that receives at least the detection value of the air-fuel ratio sensor provided in the exhaust system and the calculated fuel injection amount, and according to the fuel property parameter, Thus, the fuel adhesion parameter is calculated.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
FIG. 1 is an overall configuration diagram of an internal combustion engine (hereinafter, simply referred to as an “engine”) including a fuel injection amount control device according to an embodiment of the present invention and an intake pipe 2 of a four-cylinder engine 1, for example.
Is provided with a throttle valve 3 in the middle. A throttle valve opening (θTH) sensor 4 is connected to the throttle valve 3 and outputs an electric signal corresponding to the opening of the throttle valve 3 to output an electronic control unit (hereinafter referred to as “EC”).
U ") 5.

A fuel injection valve 6 is provided for each cylinder between the engine 1 and the throttle valve 3 and slightly upstream of the intake valve (not shown) of the intake pipe 2, and each injection valve is connected to a fuel pump (not shown). The fuel injection time (valve opening time) is controlled by a signal from the ECU 5 while being electrically connected to the ECU 5.

On the other hand, an intake pipe absolute pressure (PBA) sensor 12 is provided immediately downstream of the throttle valve 3, and an absolute pressure signal converted into an electric signal by the absolute pressure sensor 12 is supplied to the ECU 5. . Further, an intake air temperature (TA) sensor 13 is attached downstream thereof, detects the intake air temperature TA, outputs a corresponding electric signal, and supplies the electric signal to the ECU 5.

The engine water temperature (TW) sensor 14 mounted on the main body of the engine 1 is composed of a thermistor or the like, detects the engine water temperature (cooling water temperature) TW, outputs a corresponding temperature signal, and supplies it to the ECU 5. Engine speed (NE)
The sensor 15 and the cylinder discrimination (CYL) sensor 16 are mounted around a camshaft (not shown) of the engine 1 or around a crankshaft. The engine speed sensor 15 is the engine 1
A pulse (hereinafter referred to as a "TDC signal pulse") at a predetermined crank angle position every time the crankshaft rotates by 180 degrees, and the cylinder discriminating sensor 16 outputs a signal pulse at a predetermined crank angle position of a specific cylinder. These signal pulses are supplied to the ECU 5.

A catalytic converter (three-way catalyst) 23 is disposed in an exhaust pipe 21 of the engine 1 and has H in exhaust gas.
Purification of components such as C, CO and NOx is performed. A proportional air-fuel ratio sensor 22 (hereinafter referred to as “LAF sensor 22”) is mounted on the exhaust pipe 21 upstream of the catalytic converter 23. The LAF sensor 22 detects the oxygen concentration in the exhaust gas, and The ECU 5 outputs an electric signal corresponding to the detected value.
To supply.

Next, the exhaust gas recirculation mechanism (EGR) will be described.

An exhaust recirculation passage 25 is provided between the intake pipe 2 and the exhaust pipe 21 in a bypass shape. The exhaust gas recirculation path 2
5 is an exhaust pipe 2 whose one end is upstream of the LAF sensor 22.
1 and the other end is connected to the intake pipe 2.

An exhaust gas recirculation amount control valve (hereinafter, referred to as an EGR valve) 26 is interposed in the exhaust gas recirculation passage 25. The EGR valve 26 includes a valve chamber 27 and a diaphragm chamber 28.
A wedge-shaped valve body 30 disposed in the valve chamber 27 and movably arranged in the vertical direction so that the exhaust gas recirculation passage 25 can be opened and closed; and a valve shaft 31.
Diaphragm 32 connected to the valve body 20 through
And a spring 33 for urging the diaphragm 32 in the valve closing direction.
It is composed of In addition, the diaphragm chamber 28
Atmospheric pressure chamber 3 defined on the lower side via diaphragm 32
4 and a negative pressure chamber 35 defined on the upper side.

The atmosphere chamber 34 communicates with the atmosphere via a vent 34a, while the negative pressure chamber 35 is connected to a negative pressure communication passage 36. That is, the negative pressure communication passage 36 is connected to the intake pipe 2.
And the absolute pressure (negative pressure) P in the intake pipe in the intake pipe 2
BA is introduced into the negative pressure chamber 35 via the negative pressure communication passage 36. An atmosphere communication passage 37 is connected in the middle of the negative pressure communication passage 36, and a pressure regulating valve 38 is provided in the middle of the atmosphere communication passage 37. The pressure regulating valve 3
Reference numeral 8 denotes a normally closed solenoid valve, and the atmospheric pressure or the negative pressure is selectively supplied to the negative pressure chamber 35 of the diaphragm chamber 28 through the pressure regulating valve 38, and the negative pressure chamber 35 is controlled by a predetermined control. Generate pressure.

Further, the EGR valve 26 is provided with a valve opening (lift) sensor 39.
9 detects the operating position (valve lift amount LACT) of the valve element 30 of the EGR valve 26, and outputs the detection signal to the ECU 5
To supply. The EGR control is executed after the engine is warmed up (for example, when the engine coolant temperature TW is equal to or higher than a predetermined temperature).

The ECU 5 shapes input signal waveforms from various sensors, corrects a voltage level to a predetermined level, and converts an analog signal value into a digital signal value. The CPU 5b includes a storage unit 5c for storing various calculation programs executed by the CPU 5b, calculation results, and the like, an output circuit 5d for supplying a drive signal to the fuel injection valve 6, and the like.

Based on the various engine parameter signals, the CPU 5b determines various engine operating states such as a feedback control operating area for feedback control of the air-fuel ratio in accordance with the detection value of the LAF sensor 22 and an open loop control operating area. At the same time, a fuel injection time Tout of the fuel injection valve 6 is calculated in synchronization with the TDC signal pulse according to the engine operating state. Fuel injection time Tout
Is proportional to the fuel injection amount by the fuel injection valve 6, and is also referred to as the fuel injection amount in this specification.

The CPU 5b further calculates a parameter (HATTEMP) representing the property of the fuel injected from the fuel injection valve 6 based on various engine parameter signals, and corrects the fuel injection time according to the calculated parameter.

Further, the CPU 5b determines a target lift amount LC of the EGR valve 26 based on various engine operation parameter signals.
MD is calculated, and the pressure regulating valve 38 is controlled such that the detected valve lift LACT matches the target lift LCMD.

The CPU 5b outputs, via the output circuit 5d, drive signals for the fuel injection valve 6 and the pressure regulating valve 38 based on the results calculated as described above.

In this embodiment, the ECU 5 includes a feedback control unit, a fuel property parameter calculation unit, a target fuel amount calculation unit, a fuel adhesion parameter calculation unit, a fuel amount calculation unit, and a fuel injection amount calculation unit described in the claims. Configure means.

Hereinafter, the detection of the fuel property by the CPU 5b will be described, and then the transport delay correction of the fuel injected into the intake pipe 2 and the fuel injection amount control accompanying the correction will be described.

[Detection of Fuel Property] In the present embodiment, a parameter representing the fuel property, more specifically, a 50% fractionation temperature HATTEMP of the fuel is calculated using a neural network. The 50% fractionation temperature HATTEMP is the temperature at which 50% of the fuel evaporates as the fuel is heated.

FIG. 2 is a diagram for explaining the schematic structure of the neural network employed in this embodiment. This neural network has a three-layer structure of an input layer, an intermediate layer, and an output layer, and a well-known back-propagation learning algorithm is employed as a learning algorithm thereof. Note that the learning algorithm may employ another method such as a random search method.

As shown in FIG. 2, information input to each cell (neuron) in the input layer is an engine operation parameter Xi (i = 1 to n), and the information is weighted by a coupling coefficient matrix. Is input to each cell in the middle layer. In the hidden layer, its output is determined for each cell by, for example, a sigmoid function, and similarly to the processing from the input layer to the hidden layer, the output weighted by the coupling coefficient matrix is input to the output layer, and as a fuel property parameter The 50% fractionation temperature HATTEMP is output. Each coefficient of the coupling coefficient matrix, when actually using fuel with different fuel properties, for each operation parameter value, using a known fuel property parameter value as teacher data, so that the total error function is minimized, Determined by the back propagation learning algorithm. The determined coupling coefficient is stored in the storage unit of the ECU 5.

As the engine operation parameters input to the input layer, the following are employed in this embodiment with n = 13.

X1 = Tout (k) (fuel injection time (current value)) X2 = Tout (k-4) (fuel injection time (value before 4TDC)) X3 = TA (intake temperature) X4 = TW (engine water temperature) X5 = NE (engine speed) X6 = PBA (intake pipe absolute pressure) X7 = θTH (throttle valve opening) X8 = LACT (EGR valve lift) X9 = KCMD (k) (target air-fuel ratio coefficient (current value) )) X10 = KCMD (k-4) (Target air-fuel ratio coefficient (4TDC
X11 = KACT (k) (Detection equivalent ratio (current value)) X12 = KACT (k-4) (Detection equivalent ratio (value before 4TDC)) X13 = ΔKACT (k) (Detection equivalent ratio change Quantity = KAC
T (k) -KACT (k-4)) Here, the target air-fuel ratio coefficient KCMD is one of the coefficients multiplied by the basic fuel amount Ti in a calculation formula of a fuel injection amount Tout described later, The target air-fuel ratio (A / F) set according to is converted into an equivalent ratio. The detected equivalent ratio KACT is obtained by converting the air-fuel ratio detected by the LAF sensor 22 into an equivalent ratio. The suffixes (k) and (k-4) are the current value and 4 TDC before (TDC
In this embodiment, the engine 1 is a four-cylinder engine, and therefore, for example, Tout (k) and To
ut (k-4) is a fuel injection time corresponding to one specific cylinder. All parameters for which the subscript (k) is omitted represent the current value.

In the following description, the input parameters are represented by X1 to Xn in order to avoid complexity of notation.

FIG. 3 is a flowchart of a process for executing an operation in each layer described above. This process is executed in the CPU 5b in synchronization with generation of a TDC signal pulse.

First, in step S101, input (read) of each engine operation parameter is performed, and then normalization processing of the input data is performed (step S102).

Specifically, as shown in FIG. 4, first, a limit check of input data is performed (step S11).
1). That is, each input data is set to the input upper / lower limit values LMTINH, LMTINL preset for each input data.
And if the input data exceeds the input upper limit LMTINH, the input data is set to the input upper limit LMTINH, and the input lower limit LMTIH is set.
If it is lower than NL, a process for setting the input lower limit value LMTINL is performed. For example, the input lower limit value and the input upper limit value of the engine speed NE are respectively set to NELMTNILL, N
Assuming that ELMTINH is satisfied, if NE <NELMTINL, NE = NELMTINL, and NE> NEL
When it is MTINH, NE = NELMTINH. Here, input upper and lower limit values LMTINH, LMTINL
Is set to the maximum and minimum values of the data used in learning to determine the coupling coefficient matrix of the neural network,
Assuming that upper and lower limits that each input data can take when the device is normal are LMTH and LMTL, LMTL ≦ LMTI
It has a relationship of NL <LMTINH ≦ LMTH.

In the following step S112, the input data X
i (i = 1 to n) is applied to the following equation to obtain normalized data N
Xi is calculated.

NXi = (Xi−CXi) / CXi (i = 1 to n) where CXi is the median of the input upper and lower limit values.
In the input data, the detected equivalent ratio change amount ΔKA
Since the median value of CT is “0”, this normalization operation is not performed.

As described above, by normalization, all input data is converted into data having a median value of "0". Therefore, the sigmoid function calculation can be executed by providing only one sigmoid function table. It is possible to do.

Returning to FIG. 3, in step S103, calculation of the intermediate layer is performed. That is, as shown in FIG.
A matrix operation (step S121) for multiplying the normalized data NXi by the following equation 1 by a first coupling coefficient matrix [aji] (i = 1 to n, j = 1 to m) is performed, and the first intermediate variable YA
1 to YAm. Here, the number m of the first intermediate variables YAj
Corresponds to the number of cells in the intermediate layer, for example, m is about 4. When the number of cells is increased, the accuracy is improved but the amount of calculation is increased. Therefore, the number m of cells is determined in consideration of both.

[0044]

(Equation 1) Next, a sigmoid function operation by table search is performed on the first intermediate variables YA1 to YAm, and the second intermediate variable YB
1 to YBm are calculated (step S122). In this embodiment, Equation 2 is used as the sigmoid function, and the input / output characteristics of this function are as shown in FIG. Since Equation 2 is an odd function symmetrical with respect to the origin, a table for calculating y for the region of x ≧ 0 in FIG. 6 is actually set. For the region of x <0,
By performing a table search with | x | and setting the sign of the search value y to a minus value, a sigmoid function operation is performed.

[0045]

Y = 2 / (1 + exp (−2x)) − 1 Here, when Equation 2 is represented as y = SGM (x), the calculation in Step S122 is represented as Equation 3.

[0046]

## EQU3 ## YBj = SGM (YAj) (j = 1 to m) In the following step S104, the operation of the output layer is performed. This operation is basically the same as that shown in FIG. 5A, as shown in FIG. 5B, and includes a second coupling coefficient matrix (row vector) [bj] (j = 1 to m). (Step S131), and a sigmoid function operation (step S13) for performing a table search on the third intermediate variable YC to calculate output data Z
2). These operations are represented by the following Expressions 4 and 5.

[0047]

(Equation 4)

[0048]

## EQU5 ## In step S105 of FIG. 3, the output data Z is inversely normalized to calculate the 50% fractionation temperature HATTEMP. The inverse normalization processing is performed by the following equation (6).

[0049]

[Equation 6] HATTTEMP = Z × HATTEMPC + H
ATTEMPC Here, HATTEMPC is a median value of a preset 50% fractionation temperature.

The coupling coefficient matrices [aji] and [bj] (j = 1 to m) used in Equations 1 and 4 are determined in advance by learning using teacher data as described above. .

FIG. 14A shows that HATTEMP = HAT
TEMP1, a poorly volatile first fuel, and HATT
The engine is operated with a highly volatile second fuel, EMP = HATTEMP2 (<HATTEMP1), and a 50% fractionation temperature HATT for many data
EMP is calculated, and the frequency distribution of the calculated value (detected value) is shown. In the figure, lines L1 and L2 correspond to the first fuel and the second fuel, respectively, and the line L1 is HA
While a steep peak characteristic centered on TTEMP = HATTEMP1 is shown, the line L2 is HATTEMP = HA
It shows a steep peak characteristic centered on TTEMP2, and it can be seen that the properties of the fuel can be detected with high accuracy.

As described above, in the present embodiment, 50% which is a parameter representing the fuel property using a neural network is used.
Since the fractionation temperature HATTEMP is calculated with high accuracy,
It is possible to detect the property of the fuel in use without providing a fuel property sensor.

The fuel property detection process shown in FIG.
After the calculation of the fractionation temperature HATTEMP is completed, the calculation may not be performed until the engine is stopped and then started. Also, usually in different engine operating conditions,
A plurality of 50% fractionation temperatures HATTEMP are calculated, and the calculated values are averaged and used in a fuel injection amount correction process described later. Also, the calculated 50% fractionation temperature HATT
The EMP is stored in a memory backed up by a battery. For example, when the LAF sensor is inactive immediately after the engine is started, this stored value is temporarily used and the LAF is used.
After the sensor is activated, the fuel property parameters calculated by the processing in FIG. 3 are used.

[Fuel Transport Delay Correction] Hereinafter, the fuel transport delay correction will be described.

Before describing the specific processing relating to the fuel transport delay correction, the principle of the fuel transport delay correction will be described first with reference to FIGS.

FIG. 7 shows a fuel injection amount Tout and a required fuel amount Tc as a target fuel amount to be supplied to the combustion chamber of the engine.
It is a figure for explaining the relation with yl.

Tout in the figure is the amount of fuel injected from the fuel injection valve 6 to the intake pipe 2 in a certain engine operation cycle. Of the amount of fuel Tout, (A (direct rate) × Tout) A corresponding amount is supplied directly to the cylinder (combustion chamber) without adhering to the wall surface of the intake port 2A, and the remaining amount is included in the wall-adhered fuel amount Fw adhering to the wall surface up to the previous cycle as an adhesion increment Fwin. It is captured. Here, the direct ratio A indicates a ratio of fuel directly injected into a cylinder during a certain cycle among fuels injected during a certain cycle, and is given by 0 <A <1.

Then, the above (A × Tout) and the amount of reduced adhesion Fwou carried away from the amount of fuel Fw adhered to the wall surface are considered.
The value obtained by adding t becomes the required fuel amount Tcyl to be actually supplied into the cylinder. (A × Tout) and adhesion reduction amount F
wout corresponds to the first and second fuel amounts described in the claims, respectively.

Next, a first method of correcting fuel transport delay will be described.

In the first method, the adhesion reduction amount Fwout
Is assumed to follow the adhesion increment Fwin with a predetermined time delay, and this is expressed, for example, as a first-order lag model, and the degree of delay of the adhesion reduction amount Fwout is expressed using a delay coefficient (time constant) T. .

As described above, the required fuel amount Tcyl is

[0062]

[Mathematical formula-see original document] Since Tcyl = A.Tout + Fwout, the fuel injection amount Tout and the adhesion increment Fwi are obtained.
n is

[0063]

[Mathematical formula-see original document] Tout = (Tcyl-Fwout) / A

[0064]

[Mathematical formula-see original document] Fwin = (1-A) Tout.

Since the adhesion decrease amount Fwout is a first-order delay of the adhesion increment amount Fwin, discretization by k gives
The adhesion reduction amount Fwout (k) in this cycle is

[0066]

## EQU10 ## Fwout (k) = Fwout (k-1) + (Fwi
n (k-1) -Fwout (k-1)) / T. According to this equation 10, the current adhesion decrease amount Fw
out (k) is calculated based on the previous value Fwout (k-1).
The value obtained by subtracting the previous adhesion decrease amount Fwout (k-1) from the previous adhesion increment amount Fwin (k-1) (the deviation) by 1 / T will increase. That is, if the same calculation is performed for each cycle, the adhesion reduction amount Fwout approaches the adhesion increment amount Fwin by 1 / T times the deviation.

For example, when the fuel injection amount Tout is increased stepwise, assuming that the direct rate A is constant, the adhesion increment Fwin also increases stepwise as shown in FIG. On the other hand, the adhesion decrease amount Fwout responds slowly based on the time constant T to increase the adhesion increment Fwi.
n. Here, the time constant T is a time required to reach 63.2% of the total change in the rising change of the adhesion reduction amount Fwout, and as described later, the parameter indicating the fuel property and the operating state of the engine. It is set according to.

Then, the fuel injection amount Tout can be obtained from the above equations 8, 9, and 10.

Next, a second method of correcting fuel transport delay will be described.

In the second method, in addition to the above-described direct rate A, of the fuel adhering to the port wall surface up to the previous time, the proportion of fuel taken into the combustion chamber due to evaporation or the like during the current cycle. The ratio B (0 <B <1) is used. (A × Tout) is the amount supplied directly to the combustion chamber without adhering to the port wall surface, and ((1−A) × Tout)
Is the same as the first method described above, but the adhesion decrease amount (removed amount) Fwout is (B ×
Fw).

As shown in the above equation 7, the required fuel amount Tc
yl is Tcyl = A · Tout + Fwout. Here, Fwout = B × Fw Fwin = (1−A) Tout, and the current amount Fw (k) of wall-deposited fuel is the additional amount Fwin (k−1) of the amount of fuel deposited on the wall Fw (k−1) up to the previous time.
And the amount of adhesion decrease Fwout is increased or decreased.

[0072]

Fw (k) = Fw (k−1) + Fwin−Fout = Fw (k−1) + (1−A) Tout−B × Fw (k−1) = (1−A) Tout + (1) −B) × Fw (k−1).

From the above equation (7), the fuel injection amount Tou
t is

[0074]

Since Tout = (Tcyl−Fwout) / A = (Tcyl−B · Fw) / A, the fuel injection amount Tout can be obtained from the above equations (11) and (12).

The above-described direct rate A, transport delay time constant T, and carry-out rate B correspond to the fuel deposition parameters described in the claims.

[Calculation of Fuel Injection Amount] FIG. 9 is a flowchart showing a fuel injection amount calculation routine. This routine is executed in synchronization with the TDC signal pulse generation. First, T is calculated based on the engine speed NE and the intake pipe absolute pressure PBA.
A basic fuel amount Ti is determined by searching the i map (step S1). Next, the correction coefficient KTOTAL is changed to a correction coefficient K corresponding to the target air-fuel ratio coefficient KCMD and the cooling water temperature TW.
The calculation is performed by multiplying various correction coefficients such as TW, a correction coefficient KAST immediately after the start, a correction coefficient KWOT corresponding to the load state, a leaning coefficient KLS, a correction coefficient KTA corresponding to the intake air temperature, and an air-fuel ratio correction coefficient KLAF (step S2). ). Then, the required fuel amount Tcyl of the cylinder is determined by multiplying the basic fuel amount Ti by the correction coefficient KTOTAL. The air-fuel ratio correction coefficient KLAF is a correction coefficient calculated by PID control so that the detected equivalent ratio KACT matches the target air-fuel ratio coefficient KCMD.

Next, the direct rate A and the transport delay time constant T are calculated by the processing of FIGS. 10 and 11 described later (step S3), and the required fuel amount Tcyl, the direct rate A, and the transport delay time constant T are calculated by the following equation (8). And 10, the fuel injection amount T
Out (k) is calculated (step S4). Here, the value calculated when the present routine was executed last time is used as the adhesion reduction amount Fwout (k-1). Current fuel injection amount To
When ut (k) is calculated, the current adhesion decrease amount Fwout is calculated.
(k) and the adhesion increase amount Fwin (k) are calculated by Expressions 9 and 10 (steps S5 and S6), and are used for calculating the next fuel injection amount Tout. When the above calculation ends, this routine ends.

[Calculation of Direct Rate A] Next, calculation of the direct rate A will be described. FIG. 10 is a flowchart showing a routine for calculating the direct rate A. This routine is executed in synchronization with the TDC signal pulse generation.

First, it is determined whether or not exhaust gas recirculation is being performed based on a flag FEGRAB which is set to a value "1" when performing exhaust gas recirculation (step S210). Flag F
When the exhaust gas recirculation is not performed when EGRAB is “0”, the basic value A0 of the direct rate A is determined based on the engine speed NE and the absolute pressure PBA in the intake pipe by using a normal A0 map (NE−
PBA map search) (Step S22)
0). Next, the intake pipe 2 calculated by the following equation (13)
A first direct rate correction coefficient KA1 of the direct rate A is calculated in accordance with the estimated wall surface temperature value TC and the engine speed NE (step S230).

[0080]

TC = KTC × TA + (1−KTC) × TW Here, TA and TW are the detected intake air temperature and engine water temperature, and KTC is determined according to the engine speed NE and the intake pipe absolute pressure PBA. It is a weight coefficient set to a value between 0 and 1.

In calculating the direct ratio A, the estimated value T of the intake pipe wall surface temperature is used.
C is used because the amount of fuel adhering to the wall surface of the intake pipe 2 without the fuel injected into the intake pipe 2 being sucked into the combustion chamber depends on the wall temperature of the intake pipe.

In the following step S232, the 50% fractionation temperature HATTEM calculated by the gasoline property detection process of FIG.
The KA2 table shown in FIG. 12A is searched according to P, and the second direct rate correction coefficient KA2 of the direct rate A is calculated. The KA2 table is set so that the KA2 value decreases as the 50% fractionation temperature increases (decreases in volatility).

In the following step S240, the direct rate A is calculated by multiplying the basic value A0 by the first and second direct rate correction coefficients KA1 and KA2.

Next, using the calculated direct rate A and the transport delay rate 1 / T calculated in the transport delay time constant T calculation routine described later, the fuel injection amount Tout calculated in the injection fuel amount calculation routine of FIG. Calculates the lower limit value ALMTL0 of the direct rate A in order to avoid an inappropriate value due to excessive transport delay correction (step S25).
0). This lower limit value ALMTL0 is normally set to a predetermined value (for example, 0.125), is set to a larger value immediately after the engine is started and immediately after the fuel cut is completed, and is set so as to gradually decrease to the predetermined value as time passes. You.

In the following steps S260 to S290, limit processing of the direct ratio A calculated in step S240 is performed. First, it is determined whether or not the direct ratio A exceeds an upper limit value ALMTH (for example, 0.9) (step S2).
60) If it is equal to or lower than the upper limit value ALMTH, it is determined whether or not the direct ratio A is lower than the lower limit value ALMTL0 (step S270). If it is lower than the lower limit value ALMTL0, the lower limit value ALMTL0 is set to the direct rate A (step S280), and this routine ends.
If it is not less than the lower limit value ALMTL0 in step S270, this routine ends without correcting the value of the direct rate A. In step S260, the direct rate A is equal to the upper limit value A.
When the rate exceeds LMTH, the direct rate A is set to the upper limit AL.
MTH is set (step S290), and this routine ends.

On the other hand, in step S210, the flag FEGRA
If B is set to “1” and it is determined that the exhaust gas recirculation is performed, the exhaust gas recirculation (EGR) A0 map (NE-PBA
Switching to map search (step S300), the basic value A0 of the direct rate A is calculated (step S230), and thereafter steps S230 to S290 are executed.

[Calculation of Transport Delay Time Constant T] Next, the calculation of the fuel transport delay time constant T used for calculating the fuel injection amount together with the direct rate A will be described. FIG. 11 is a flowchart showing a routine for calculating the transport delay time constant T.
This routine is executed in synchronization with the TDC signal pulse generation. The reciprocal of the transport delay time constant T is the transport delay rate 1 / T. First, similarly to the above-described calculation routine of the direct ratio A, the flag FEG set to the value “1” when the exhaust gas recirculation is performed.
It is determined whether the value of RAB is “1” or “0” (step S310). When the flag FEGRAB is reset to the value “0” and the exhaust gas recirculation is not performed, the engine speed NE and the intake pipe absolute pressure PBA
Then, the basic value 1 / T0 of the transport delay rate is calculated from the normal 1 / T0 map (NE-PBA map search) (step S320).

Since the transport delay rate 1 / T also depends on the wall temperature of the intake pipe 2 similarly to the direct rate A, the estimated wall temperature TC
Then, the KT1 map is searched according to the engine speed NE and the first transport delay rate correction coefficient KT1 is calculated (step S330). Furthermore, 50% fractionation temperature HATTEM
The KT2 table shown in FIG. 12B is searched according to P, and the second transport delay rate correction coefficient KT2 is calculated (step SS332). The KT2 table is set so that the KT2 value decreases as the fractionation temperature increases by 50% (as the volatility decreases).

Next, the transport delay rate 1 / T is calculated by multiplying the calculated first and second transport delay rate correction coefficients KT1 and KT2 by the basic value 1 / T0 (step S340).

Next, limit processing of the transport delay rate 1 / T is performed. That is, it is determined whether or not the transport delay rate 1 / T calculated in step S330 exceeds the upper limit value TLMTH (step S350). (Step S360). When the value is below the lower limit value TLMTL, the transport delay rate 1 /
A lower limit value TLMTL is set to T (step S37)
0), end this routine. When the transport delay rate 1 / T is equal to or greater than the lower limit value TLMTL in step S360, this routine ends without correction. Step S3
If the transport delay rate 1 / T exceeds the upper limit value TLMTH at 50, the transport delay rate 1 / T is set to the upper limit value TLMTH (step S380), and this routine ends.

In step S310, the flag FEGR is set.
When AB is set to the value "1" and it is determined that the exhaust gas recirculation is performed, the basic value 1 / T0 is calculated by switching to the 1 / T0 map for EGR (NE-PBA map search) (step S390), Thereafter, the above steps S330 to S38
Execute 0.

As described above, in the present embodiment, the direct rate A and the transport delay rate 1 / T are corrected according to the 50% fractionation temperature HATTEMP of the fuel used.
Even more appropriate transport delay correction is performed according to the properties of the fuel used, and good engine operability can be obtained even when feedback control according to the sensor output cannot be executed, particularly when the LAF sensor 22 is inactive. In addition, the exhaust gas characteristics can be maintained. That is, especially at the time of cold start of the engine, since the properties of the fuel used are greatly affected, the direct rate A and the transport delay rate 1 are set in accordance with the HATTEMP value stored in the memory backed up by the battery. By correcting / T, appropriate fuel injection amount control can be performed, and good engine operability and exhaust gas characteristics can be maintained.

(Second Embodiment) In this embodiment, gasoline property detection is performed by using a multiple regression model instead of the neural network in the first embodiment. The multiple regression model in the present embodiment is represented by the following equation (14).
This is a model assuming that a 0% fractionation temperature HATTEMP is expressed, and a coefficient matrix [ci] of Expression 14 (i = 0 to n)
Obtains a large amount of sample data under various engine operating conditions using gasoline having a known 50% fractionation temperature, and obtains the known 50% fractionation temperature HATTE according to Equation 15.
MP0 and 50% fractionation temperature HATT calculated by Equation 14
The sum of squares of the difference from EMP (residual sum of squares) S is set to be the minimum.

[0094]

[Equation 14]

[0095]

(Equation 15) Here, NSMPL is the number of samples.

FIG. 13 is a flowchart of a gasoline property detection process executed in place of the process of FIG. 3 in the first embodiment. This process is executed in synchronization with generation of a TDC signal pulse.

In step S151, each engine operation parameter is input (read), and then those parameter values are applied to equation (14) to obtain a 50% fractionation temperature HAT.
TEMP is calculated (step S152).

[0098] Except for the above points, it is the same as the first embodiment.

FIG. 14 (b) shows H as in FIG. 14 (a).
A first fuel having low volatility, ATTTEMP = HATTEMP1, and HATTEMP = HATTEMP2 (<H
The engine is operated by using the highly volatile second fuel which is ATTEMP1), and the 50% fractionation temperature HAT is obtained by using the multiple regression model of the present embodiment for many data.
TEMP is calculated, and the frequency distribution of the calculated value (detected value) is shown. In the figure, lines L3 and L4 correspond to a first fuel and a second fuel, respectively. The variation (error) in the detected values is larger than that in the case where the neural network shown in FIG.
This shows that the 0% fractionation temperature HATTEMP can be detected.

Therefore, according to the present embodiment, it is possible to detect a parameter representing the fuel property without newly providing a fuel property sensor.

(Other Embodiments) The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, in the first embodiment, a 50% fractionation temperature HATTEMP, which is a parameter representing fuel properties, is calculated using a neural network, and the 50% fractionation temperature HATTEM is calculated.
The direct rate A and the transport delay rate 1 / T are corrected according to P. However, two neural networks are provided so that each network directly outputs the direct rate A and the transport delay rate 1 / T. May be configured.

The parameter indicating the fuel property is 50%
The present invention is not limited to the fractionation temperature, and for example, a Reid vapor pressure (RVP) may be used.

Further, in the above-described embodiment, only the calculation of the fuel injection time Tout by the first method of the fuel transport delay correction is shown. However, the direct rate A and the carry-out rate B are adopted by adopting the second method. May be corrected according to a parameter representing the fuel property. The carry-out rate correction coefficient in that case is the same as the tendency shown in FIG.
It is set to decrease as ATTEMP increases.

The input parameters of the neural network and the multiple regression model do not use all of the above-mentioned 13 parameters. ) -PBA (k-
4)), the engine speed NE, the engine water temperature TW, the intake air temperature TA, the fuel injection time Tout (k), and the detected equivalent ratio change amount ΔKACT may be limited to seven. Thus, the amount of calculation in the CPU 5b can be reduced.

[0105]

As described in detail above, according to the first aspect of the present invention, the amount of fuel supplied to the engine is calculated based on the value detected by the air-fuel ratio sensor provided in the exhaust system of the engine. The air-fuel ratio of the air-fuel mixture supplied to the engine is feedback-controlled, and a fuel property parameter representing the property of the fuel is calculated using a neural network that inputs at least the detection value of the air-fuel ratio sensor and the amount of fuel supplied to the engine. Therefore, the gasoline property can be detected without using a new sensor.

According to the second aspect of the invention, the amount of fuel to be supplied to the engine is calculated by calculating the amount of fuel to be supplied to the engine based on the detection value of the air-fuel ratio sensor provided in the exhaust system of the engine. The invention according to claim 1, wherein the air-fuel ratio is feedback-controlled, and a fuel property parameter representing the property of the fuel is calculated using a multiple regression model having at least a detection value of the air-fuel ratio sensor and an amount of fuel supplied to the engine as inputs. It has the same effect as.

According to the third aspect of the present invention, the fuel property representing the property of the fuel using at least the neural network inputting the detected value of the air-fuel ratio sensor provided in the exhaust system and the calculated fuel injection amount. A parameter is calculated, a fuel deposition parameter representing a fuel deposition characteristic in the intake passage is calculated according to the fuel property parameter, and the target fuel to be supplied into the combustion chamber using the fuel deposition parameter calculated in this manner. Since the corrected fuel injection amount is calculated, the fuel property can be detected without using a new sensor, and the fuel transport delay suitable for the property of the fuel in use can be corrected. As a result, particularly when the air-fuel ratio sensor is inactive, good exhaust gas characteristics can be maintained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an internal combustion engine and a control device thereof according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a neural network.

FIG. 3 is a flowchart of a gasoline property detection process.

FIG. 4 is a flowchart of a process for normalizing input data.

FIG. 5 is a flowchart of a process corresponding to a calculation in an intermediate layer and an output layer of the neural network.

FIG. 6 is a diagram for explaining a sigmoid function.

FIG. 7 is a diagram for explaining fuel transport delay correction.

FIG. 8 is a diagram for explaining the significance of a fuel delay correction time constant.

FIG. 9 is a flowchart of a fuel injection amount calculation process.

FIG. 10 is a flowchart of a process for calculating a direct rate.

FIG. 11 is a flowchart of a process for calculating a transport delay time constant.

FIG. 12 is a diagram showing a table used in the processing of FIG. 10 or 11;

FIG. 13 is a flowchart of a gasoline property detection process according to the second embodiment of the present invention.

FIG. 14 is a diagram showing a frequency distribution of detected values of gasoline properties.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 4 Throttle valve opening sensor 5 Electronic control unit (feedback control means, fuel property parameter calculation means, target fuel amount calculation means, fuel adhesion parameter calculation means, fuel amount calculation means, fuel injection amount calculation means) Reference Signs List 6 Fuel injection valve 12 Absolute pressure sensor in intake pipe 13 Intake temperature sensor 14 Engine water temperature sensor 15 Engine speed sensor 21 Exhaust pipe 22 Air-fuel ratio sensor

Claims (3)

[Claims] 1. A fuel property detection device for detecting a property of fuel supplied to an internal combustion engine, comprising: an air-fuel ratio sensor provided in an exhaust system of the engine; Feedback control means for calculating the amount of fuel to be supplied and performing feedback control on the air-fuel ratio of the air-fuel mixture supplied to the engine, and using a neural network that receives at least the detection value of the air-fuel ratio sensor and the amount of fuel supplied to the engine. A fuel property parameter calculating means for calculating a fuel property parameter representing the property of the fuel. 2. A fuel property detection device for detecting a property of fuel supplied to an internal combustion engine, comprising: an air-fuel ratio sensor provided in an exhaust system of the engine; Feedback control means for calculating the amount of fuel to be supplied and performing feedback control on the air-fuel ratio of the air-fuel mixture supplied to the engine; and a multiple regression model having at least the detection value of the air-fuel ratio sensor and the amount of fuel supplied to the engine as inputs. A fuel property parameter calculating means for calculating a fuel property parameter indicating the property of the fuel using the fuel property parameter calculating means. 3. An air-fuel ratio sensor provided in an exhaust system of an internal combustion engine, and a target fuel amount supplied to a combustion chamber of the engine according to an operation parameter of the engine including a detection value of the air-fuel ratio sensor. Target fuel amount calculating means for calculating; fuel adhering parameter calculating means for calculating a fuel adhering parameter representing a fuel adhering characteristic in the intake passage according to the operating state of the engine; and a fuel injection valve based on the fuel adhering parameter. Of the fuel injected from the fuel tank, the first fuel amount directly drawn into the combustion chamber and the second fuel drawn into the combustion chamber by evaporating the fuel amount adhering to the wall surface of the intake passage Fuel amount calculating means for calculating an amount of fuel, and fuel injection amount calculating means for calculating the fuel injection amount by the fuel injection valve by correcting the target fuel amount based on the first fuel amount and the second fuel amount. Internal combustion engine equipped with A fuel property parameter calculating means for calculating a fuel property parameter representing a property of the fuel by using a neural network having at least a detection value of the air-fuel ratio sensor and the fuel injection quantity as inputs, The fuel injection amount control device for an internal combustion engine, wherein the fuel adhesion parameter calculation means calculates the fuel adhesion parameter according to the fuel property parameter.