Control device for internal combustion engine

Abstract

A processor (CPU40e) of a control device (ECU0) for an internal combustion engine identifies a first throttle valve opening degree θA and a second throttle valve opening degree θB at which there is a change in the rate of change (differential value) of an index (deposit thickness, reduction ratio of effective opening area, flow rate reduction ratio, or the like) that is correlated with the reduction rate of the effective opening area of a throttle valve (s109). The processor (CPU40e) estimates an index for any throttle valve opening degree from the first throttle valve opening degree θA and the second throttle valve opening degree θB (s110), and calculates the effective opening area of the throttle valve from the estimated index (s112).

Description

Technical Field

[0001] The present invention relates to a control device for an internal combustion engine.

Background Art

[0002] In automotive exhaust gas regulations, which are becoming stricter year by year to reduce the environmental load, it is essential to improve the accuracy of a technique (air-fuel ratio control) for controlling the air-fuel ratio (the ratio of the amount of air to the amount of fuel in the cylinder) to an appropriate state. As methods of air-fuel ratio control, there are methods of detecting the oxygen concentration in the exhaust gas and correcting the fuel supply amount, and determining the fuel supply amount according to the intake air flow rate detected by an intake air flow sensor provided in the intake passage.

[0003] These methods are easy to apply when the operating state (rotation speed, output) of the internal combustion engine is in a state with no significant change (steady state). On the other hand, under transient operating conditions such as sudden acceleration or sudden deceleration of an automobile, these methods cannot capture the gas flow rate flowing into the cylinder that transiently changes (hereinafter referred to as the in-cylinder inflow gas flow rate), and thus cannot set the air-fuel ratio to an appropriate condition quickly enough.

[0004] Therefore, under conditions where the operation of the internal combustion engine is in a transient state, it is necessary to calculate the in-cylinder inflow gas amount using an intake air metering model and set an appropriate fuel injection amount to achieve the target air-fuel ratio. As a method for calculating the in-cylinder inflow gas flow rate of an internal combustion engine, there is a method of calculating the intake pipe pressure from the throttle valve passage gas flow rate calculated based on the intake air flow rate and the throttle valve effective opening area (hereinafter referred to as the throttle valve effective opening area) of the throttle valve, and calculating the in-cylinder inflow gas flow rate from the pressure.

[0005] When deposits adhere to the body part of the throttle valve of an internal combustion engine (hereinafter referred to as the throttle body), a part of the cross-section through which air can flow between the throttle valve and the throttle body is blocked by the deposits, so the effective opening area of the throttle valve (the effective area of the cross-section through which air can flow between the throttle valve and the body) decreases. Here, the deposits are formed by blow-by gas introduced into the intake air and unburned components of fuel in the exhaust gas adhering to, solidifying, and depositing on the throttle body.

[0006] When calculating the effective opening area of the throttle valve without reflecting the state of deposit accumulation in the intake air metering model, the effective opening area of the throttle valve calculated by the intake air metering model cannot reproduce the actual state and an error occurs. As a result, calculation errors in the throttle valve passing gas flow rate and the in-cylinder inflow gas flow rate occur. Therefore, it is necessary to reflect the change in the effective opening area of the throttle valve caused by deposit adhesion in the intake air metering model.

[0007] In the prior art, a technique is disclosed in which the effective opening area of the throttle valve calculated using the learned values of the air flow rate under steady operating conditions at three different throttle valve opening degrees is approximated by a quadratic curve with the opening degree as a variable to reflect the change in the effective opening area of the throttle valve due to deposit accumulation (see, for example, Patent Document 1).

[0008] In Patent Document 1, as the three throttle valve opening degrees, a first throttle valve opening degree which is the throttle valve opening degree in a predetermined idle state, an arbitrary second throttle valve opening degree smaller than the first throttle valve opening degree, and a predetermined third throttle valve opening degree larger than the first throttle valve opening degree and not affected by deposits accumulated near the throttle valve are used.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, in the prior art as disclosed in Patent Document 1, since it is assumed that the interval between the first throttle valve opening degree and the third throttle valve opening degree becomes large, when correcting to have characteristics approximated to a predetermined quadratic curve, the flow rate characteristics in the range of the first throttle valve opening degree and the third throttle valve opening degree, that is, the range of the throttle valve opening degree from the throttle valve opening degree in the idle state to the throttle valve opening degree not affected by deposits, are not necessarily accurately corrected.

[0011] As a result, when the throttle valve opening degree changes while passing between the first throttle valve opening degree and the third throttle valve opening degree, the calculation error of the throttle passage gas flow rate in the transient state becomes large, and a large error occurs in the calculated amount of the in-cylinder inflow gas flow rate in the transient state. As a result, it is difficult to maintain the air-fuel ratio during transient operation at a desired air-fuel ratio.

[0012] The present invention has been invented in view of such circumstances. An object of the present invention is to provide a control device for an internal combustion engine that can accurately calculate the effective opening area of a throttle valve reflecting the influence of deposits.

Means for Solving the Problems

[0013] To achieve the above object, a control device for an internal combustion engine according to the present invention identifies a first throttle valve opening degree and a second throttle valve opening degree at which a change rate of an index correlated with a reduction rate of the effective opening area of a throttle valve changes, estimates the index at an arbitrary throttle valve opening degree from the first throttle valve opening degree and the second throttle valve opening degree, and includes a processor that calculates the effective opening area of the throttle valve from the estimated index. The processor estimates that the value of the index in the range of throttle valve opening smaller than the first throttle valve opening is a constant value equal to the value of the index at the first throttle valve opening, estimates that the value of the index in the range of throttle valve opening larger than the second throttle valve opening is a constant value equal to the value of the index at the second throttle valve opening, estimates the value of the index in the range between the first throttle valve opening and the second throttle valve opening based on the value of the index at the first throttle valve opening and the value of the index at the second throttle valve opening, identifies the first throttle valve opening based on the minimum throttle valve opening at a throttle valve opening where the change rate of the index with respect to the throttle valve opening is within a predetermined range, identifies the second throttle valve opening based on the maximum throttle valve opening, and calculates a weighted average value of the previous value and the current value of the index as the learned value of the index. is provided.

Effects of the Invention

[0014] According to the present invention, the effective opening area of the throttle valve reflecting the influence of deposits can be accurately calculated. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

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Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11A

Figure 11B

Figure 11C

Figure 12

Figure 13

Figure 14

Figure 15

Mode for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. This embodiment relates to a control device for an internal combustion engine that calculates the in-cylinder inflow gas flow rate of an internal combustion engine equipped with a throttle valve in the intake passage. In this embodiment, the effective opening area of the throttle valve is accurately calculated in the region above the throttle valve opening degree in the idle state, the calculation accuracy of the in-cylinder inflow gas flow rate is improved, and particularly, the air-fuel ratio during transient operation can be maintained at a desired air-fuel ratio. The purpose is to provide a control device for an internal combustion engine.

[0017] (Embodiment 1) Fig. 1 shows a system configuration diagram of the engine in this embodiment. This system configuration is common to all the embodiments shown below.

[0018] The engine 100 (internal combustion engine) is a spark ignition internal combustion engine. An intake air flow sensor 3 for measuring the intake air flow rate passing through the intake passage of the engine, a compressor 4b of a supercharger for compressing the intake gas, an intercooler 5 for cooling the intake gas, and a throttle valve 6 for adjusting the intake air flow rate are provided at appropriate positions in the intake pipe 8 respectively. Note that an intake air temperature sensor 15 for detecting the intake air temperature is built in the intake air flow sensor 3, and a throttle position sensor for detecting the opening degree of the throttle valve is built in the throttle valve 6.

[0019] In addition, the engine 100 is provided with a variable intake valve 9a for controlling the opening and closing phase of the intake valve, a variable exhaust valve 9b for controlling the opening and closing phase of the exhaust valve, a fuel injection device 10 for injecting fuel into the combustion chamber 13, a spark plug 11 for supplying ignition energy, a crank angle sensor 12, and an atmospheric pressure sensor 16 for measuring the atmospheric pressure at appropriate positions of the engine 100 respectively. Note that phase sensors for detecting the opening and closing phases are provided in the variable intake valve 9a and the variable exhaust valve 9b respectively.

[0020] Furthermore, a turbine 4a for driving the compressor 4b by utilizing the energy of the exhaust gas, a catalytic converter 21 for purifying the exhaust gas, and an air-fuel ratio sensor 20 which is one aspect of an air-fuel ratio detector and detects the air-fuel ratio of the exhaust gas upstream of the catalytic converter 21 are provided at appropriate positions in the exhaust pipe 14 respectively. The air-fuel ratio sensor 20 may be an oxygen concentration sensor. An EGR pipe 32 for extracting EGR branches from upstream of the turbine 4a in the exhaust pipe 14, and an EGR cooler 30 for cooling the EGR and an EGR valve 31 for adjusting the EGR flow rate are provided at appropriate positions in the EGR pipe 32.

[0021] The detection signal (intake air flow rate) Ss3 obtained from the intake air flow sensor 3, the detection signal (throttle valve opening) Ss6 obtained from the throttle position sensor, the opening / closing phase detection signals (intake valve phase and exhaust valve phase) Ss9a, Ss9b obtained from the phase sensors of the variable intake valve 9a and the variable exhaust valve 9b, the detection signal (engine speed) Ss12 obtained from the crank angle sensor 12, the detection signal (atmospheric temperature) Ss15 obtained from the intake air temperature sensor 15, the detection signal (atmospheric pressure) Ss16 obtained from the atmospheric pressure sensor 16, and the detection signal Ss20 obtained from the air-fuel ratio sensor 20 are sent to the engine control unit (hereinafter referred to as ECU) 0. The signal Ss1 obtained from the accelerator pedal opening sensor 1 that detects the depression amount of the accelerator pedal, i.e., the accelerator opening, is sent to the ECU 0.

[0022] The ECU 0 calculates the required torque based on the output signal Ss1 of the accelerator pedal opening sensor 1 and various sensor signals. That is, the accelerator pedal opening sensor 1 is used as a required torque detection sensor that detects the required torque for the engine 100. The ECU 0 optimally calculates the main operating amounts of the engine 100, such as the opening of the throttle valve 6, the injection pulse duration of the fuel injection device 10, the ignition timing of the ignition plug 11, the opening / closing timing of the variable intake valve 9a and the variable exhaust valve 9b, and the opening of the EGR valve 31, based on the operating state of the engine 100 obtained from the outputs of the various sensors.

[0023] The fuel injection pulse duration calculated by the ECU 0 is converted into a fuel injection device drive signal Ds10 (open valve pulse signal) and sent to the fuel injection device 10. The opening of the throttle valve 6 calculated by the ECU 0 is sent to the throttle valve 6 as a throttle valve drive signal Ds6. Similarly, the ignition plug drive signal Ds11 is sent to the ignition plug 11. The opening of the EGR valve is sent to the EGR valve 31 as an EGR valve drive signal Ds31.

[0024] Air flowing into the combustion chamber 13 from the intake pipe 8 through the variable intake valve 9a is mixed with fuel injected from the fuel injection device 10 through a fuel pump (not shown) from a fuel tank (not shown) to form an air-fuel mixture. The air-fuel mixture is burned by a spark generated from the spark plug 11 at a predetermined ignition timing, and the combustion pressure pushes down the piston to generate the driving force of the engine 100. The exhaust gas after combustion is sent to the catalytic converter 21 through the variable exhaust valve 9b, the exhaust pipe 14, and the turbine 4a, and is discharged after the NOx, CO, and HC components are purified. A part of the exhaust gas is introduced into the intake pipe 8 through the EGR pipe 32, the EGR cooler 30, and the EGR valve 31.

[0025] Figure 2 is a system block diagram showing the configuration of the ECU0 according to an embodiment of the present invention. Output signals from the accelerator opening sensor 1, the intake air flow sensor 3, the phase sensors of the variable intake valve 9a and the variable exhaust valve 9b, the crank angle sensor 12, the intake air temperature sensor 15, the atmospheric pressure sensor 16, and the air-fuel ratio sensor 20 are input to the input circuit 40a of the ECU0. However, the input signals are not limited to these.

[0026] Input signals from the respective input sensors are sent to the input ports in the input / output port 40b. The values of the input signals sent to the input / output port 40b are stored in the random access memory (RAM) 40c and processed by the CPU 40e. At this time, signals composed of analog signals among the input signals sent to the input circuit 40a are converted into digital signals by an A / D converter provided in the input circuit 40a.

[0027] The control program describing the content of the arithmetic processing is pre-written in the read-only memory (ROM) 40d. Values indicating the operating amounts of the respective actuators calculated according to the control program are stored in the RAM 40c and then sent to the output ports of the input / output port 40b and further sent to the respective actuators through the respective drive circuits. In the case of this embodiment, there are a throttle drive circuit 40f, an EGR valve drive circuit 40g, a variable valve mechanism drive circuit 40h, a fuel injection device drive circuit 40i, and an ignition output circuit 40j as drive circuits.

[0028] Each drive circuit controls the throttle valve 6, the variable valve 9, the fuel injection device 10, the ignition plug 11, and the EGR valve 31. Although the ECU0 of the present embodiment includes the drive circuit in the ECU0, it is not limited thereto, and any one or all of the drive circuits may be provided outside the ECU0.

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 3 to 13. FIG. 3 shows a block diagram for correcting the effective opening area of the throttle valve according to the present embodiment. The outline of the function of each block is as follows.

[0030] The reduction rate correlation index calculation unit obtains a learned value of the reduction rate correlation index based on various detection values including the atmospheric pressure, the intake air flow rate, and the intake pipe pressure. In the present embodiment, the thickness of the deposit (deposit thickness) adhering to the throttle body is described as the reduction rate correlation index, but it is not limited thereto. For example, the reduction rate of the effective opening area of the throttle valve (the reduction rate of the effective opening area of the throttle valve after deposit adhesion with respect to the effective opening area of the throttle valve at the time of new product) or the reduction rate of the flow rate (the reduction rate of the flow rate after deposit adhesion with respect to the flow rate at the time of new product under reference conditions) can also be handled as the same index.

[0031] The change point calculation unit calculates the throttle valve opening degrees (low opening degree side change point and high opening degree side change point) at which the deposit thickness changes, which are necessary for calculating the deposit thickness at points where the learned value has not been obtained. Here, the change point is calculated based on the differential value of the deposit thickness with respect to the throttle valve opening degree.

[0032] The throttle valve effective opening area calculation unit calculates the deposit thickness of the throttle valve opening degree for which the learned value of the deposit thickness cannot be obtained based on the low opening degree side change point and the high opening degree side change point, and calculates the throttle valve effective opening area at an arbitrary throttle valve opening degree from the deposit thickness. The calculation of the upstream pressure and the downstream pressure of the throttle valve is executed by a block not shown.

[0033] First, before explaining the details of the processing performed in each block, examples of equations and calculation methods used in the description of this embodiment will be explained. Subsequently, the specific processing of this embodiment will be described.

[0034] First, examples of equations and calculation methods used in the description of this embodiment will be explained. Note that the equations and calculation methods shown below are merely examples. First, an outline of an example (I) of an intake system physical model for calculating the air behavior from the change in the throttle valve opening until the change in the in-cylinder inflow gas flow rate occurs will be explained, and the throttle valve passage gas flow rate (II) and the in-cylinder inflow gas flow rate (III) will be described.

[0035] (I) Basic principle of the intake system physical model In this embodiment, in the system shown in FIG. 1, the path from the intake port to the engine is divided into three control volumes (CVs): between the compressor and the throttle valve (hereinafter, this location is referred to as upstream of the throttle valve), between the throttle valve and the intake manifold (hereinafter, this location is referred to as the intake pipe), and the exhaust pipe. The mass, energy of the gas in each CV, and the mass flow rate and energy flow rate passing through each CV are calculated.

[0036] In the calculation, based on the following basic equations, using the intake flow rate detection value, intake temperature detection value, atmospheric pressure detection value, throttle valve opening detection value, EGR valve opening detection value, intake valve phase detection value, exhaust valve phase detection value, rotational speed detection value, cooling water temperature detection value, torque, and the mass flow rate and temperature calculated at the previous calculation time, the pressure and temperature are calculated from the mass and energy of each CV.

[0037]

Equation

[0038]

Equation

[0039]

Equation

[0040] [Number]

[0041] Here, m is the mass [kg], e is the energy [J], T is the temperature [K], κκ is the specific heat ratio [-], R is the gas constant [J / (kg·K)], Q is the heat transfer amount to the wall surface with which the gas is in contact (wall surface heat loss amount) [J], V is the volume [m 3 , and the subscript in represents the inflow into the CV, and out represents the outflow from the CV.

[0042] Next, the calculation methods for the mass, energy, temperature, and pressure upstream of the throttle valve will be described. The mass of the gas upstream of the throttle valve m Thr is calculated by Equation (5), which is a discretized form of Equation (1), based on the intake flow rate dG AFS , the previous value of the gas flow rate through the throttle valve dG Thr described later, and the previous value of the mass of the gas upstream of the throttle valve.

[0043] [Number]

[0044] The energy of the gas upstream of the throttle valve is calculated by Equation (6), which is a discretized form of Equation (2), based on the mass of the gas upstream of the throttle valve m Thr , the atmospheric temperature T atm , the previous value of the temperature upstream of the throttle valve T Thr , the intake flow rate dG AFS , and the previous value of the gas flow rate through the throttle valve dG Thr .

[0045] [Number]

[0046] Here, as representative values, the values of air under standard conditions are used for the specific heat ratio and the gas constant. Also, the intercooler cooling amount dQ c / dt is obtained experimentally in advance and given as a constant.

[0047] The upstream gas temperature of the throttle valve is calculated by Equation (4) based on the upstream gas energy of the throttle valve, and the upstream pressure of the throttle valve is calculated by Equation (3) based on the upstream gas temperature of the throttle valve and the upstream gas mass.

[0048] Next, the calculation methods for the mass, energy, temperature, and pressure of the intake pipe gas will be described. The intake pipe gas mass m mani is calculated by Equation (7), which is a discretized form of Equation (1), based on the previous value of the throttle valve passage flow rate dG Thr described later, the previous value of the in-cylinder inflow gas flow rate dG cyl and the previous value of the intake pipe gas mass.

[0049]

Equation

[0050] The intake pipe gas energy is calculated by Equation (8), which is a discretized form of Equation (2), based on the intake pipe gas mass m mani the previous value of the upstream temperature T of the throttle valve Thr the previous value of the intake pipe temperature T mani , the previous value of the throttle valve passage gas flow rate dG Thr and the previous value of the in-cylinder inflow gas flow rate dG cyl .

[0051]

Equation

[0052] Here, the specific heat ratio and the gas constant use the values of air at standard conditions as representative values. Also, the wall heat loss amount is given as a constant by experimentally obtaining it in advance.

[0053] The intake pipe gas temperature is calculated by Equation (4) based on the intake pipe gas energy. The intake pipe pressure is calculated by Equation (3) based on the intake pipe gas temperature and the intake pipe mass. When a device for detecting the intake pipe pressure is provided, the detected value can also be used.

[0054] (II) Throttle valve gas flow rate Next, the calculation method of the throttle valve gas flow rate will be described. In this embodiment, the throttle is regarded as an orifice, and a hydrodynamic model around the throttle is constructed to calculate the throttle valve gas flow rate. Here, the throttle valve gas flow rate is given by the following flow rate formula considering the compressibility of the fluid based on the opening degree of the throttle valve and the pressures before and after the throttle valve.

[0055]

Equation

[0056] dG Thr is the throttle valve gas flow rate [kg / s], μ is the throttle valve effective opening area correction coefficient [-], A is the throttle valve geometric opening area [m 2 ²], Pup is the upstream pressure of the throttle valve [Pa], Pdn is the downstream pressure of the throttle valve [Pa], R is the gas constant [J / (kg·K)], Tup is the upstream temperature of the throttle valve [K], and Ψ is the flow coefficient [-]. Also, the product of μ and A is an index called the throttle valve effective opening area [m 2 ²]. Here, the flow coefficient is selected according to either the above formula (9.2) or (9.3) depending on the pressure ratio Pdn / Pup between the upstream pressure Pup of the throttle valve and the downstream pressure Pdn of the throttle valve. Also, the inequality (9.2.1) for the condition of the ratio is called the sonic condition. Since the flow velocity passing through the valve becomes equal to the sonic velocity and the flow rate becomes saturated, the flow coefficient is given as a constant regardless of the pressure state. Note that the inequality (9.3.1) for the condition of the pressure ratio is the non-sonic condition, and the flow velocity passing through the valve is less than the sonic velocity.

[0057] (III) In-cylinder inflow gas flow rate Next, the in-cylinder inflow gas flow rate is calculated by the method described below. Equation 10 shows the calculation formula for the in-cylinder inflow gas flow rate.

[0058]

Equation

[0059] dG cyl wherein, V is the in-cylinder inflow gas flow rate [kg / s], η is the intake efficiency [-], Ne is the engine speed [rpm], Vs is the stroke volume [m 3 , Pmani is the intake pipe pressure downstream of the throttle valve [Pa], Tmani is the intake pipe gas temperature [K], and ncyl is the number of cylinders [-]. The intake efficiency is pre-calibrated and pre-set so that it can be retrieved from the engine speed, intake pipe pressure, intake valve phase, and exhaust valve phase.

[0060] In this way, the ECU0 repeats the calculations (I), (II), and (III) described above at each determined calculation cycle, and accurately calculates the pressure from upstream of the throttle valve to downstream of the cylinder using physical formulas, thereby enabling high-response and high-precision calculation of the in-cylinder inflow gas flow rate under transient conditions that cannot be accurately measured by the intake air flow rate sensor 3.

[0061] Next, the concept of a method for correcting the throttle valve effective opening area based on the deposit thickness, which is a key point of the present embodiment, will be described with reference to FIGS. 4 to 10.

[0062] FIG. 4 shows the flow state around the throttle valve when deposits adhere. When deposits accumulate near the throttle valve, the flow path is blocked and the throttle valve effective opening area decreases. If the throttle valve effective opening area is calculated without reflecting this state in the model, an error will occur between the calculated value of the throttle valve effective opening area and the actual state.

[0063] FIG. 5 shows the effective opening area of a throttle valve that is new and has no deposit adhesion, and a throttle valve that has traveled a considerable amount and has deposit adhesion. The solid line indicates no deposit adhesion, and the dashed line indicates deposit adhesion. As shown in FIG. 5, there is a range of throttle valve opening degrees in which the effective opening area of the throttle valve becomes smaller due to deposit adhesion compared to the case where there is no deposit adhesion. Here, as the throttle valve opening degree increases, the ratio of the area blocked by the deposit thickness to the effective opening area of the throttle valve becomes smaller, so the rate of change of the effective opening area of the throttle valve due to the deposit becomes smaller as the throttle valve opening degree increases.

[0064] Next, the characteristics of the deposit thickness distribution will be described. First, the definition of the deposit thickness in this embodiment will be described. FIG. 6 shows an image of deposit adhesion to the throttle body. Here, let the throttle valve opening degree be θ [deg]. In this embodiment, the deposit thickness at the valve tip position of the throttle valve when the throttle valve opening degree is set to θ is defined as the deposit thickness at the throttle valve opening degree θ.

[0065] FIG. 7 shows an example of the deposit thickness distribution. The inventors of the present application have found the characteristics of the deposit thickness distribution shown in the following (A) to (C).

[0066] (A) The deposit thickness is constant in the range where the throttle valve opening degree is small (throttle valve opening degree θ A and below).

[0067] (B) The deposit thickness increases between the throttle valve opening degrees θ A ~θ B .

[0068] (C) The deposit thickness is constant in the range where the throttle valve opening degree is large (the range where the throttle valve opening degree is θ B and above).

[0069] When the gas adiabatically expands as it passes through the throttle valve, the gas temperature decreases, and accordingly, the temperature of the throttle body wall surface drops. As a result, high-boiling hydrocarbons derived from blow-by gas and EGR gas contained in the intake air aggregate, deposits are formed, and the mechanism by which they adhere to the throttle body is known. It is presumed that the deposits adhering by such a mechanism exhibit the characteristics from (A) to (C).

[0070] In the present embodiment, the influence of deposit accumulation is reflected by using the characteristics from (A) to (C) shown above. Specifically, it was assumed that the deposit thickness would have a two-stage distribution with respect to the flow direction. By assuming such a deposit thickness distribution in the flow direction and calculating the deposit thickness at two points (for example, throttle valve opening degrees θ A and θ B ) having the thickness information of the two-stage distribution, the deposit thickness over a wide range in the flow direction can be calculated.

[0071] The details of the same modeling will be described below.

[0072] FIG. 8 shows a conceptual diagram of the modeling of the throttle valve opening area considering deposit adhesion. FIG. 8 is a diagram that copies the throttle valve in the flow direction from the upstream side of the throttle valve. Here, the clearance between the throttle body and the throttle valve is taken as the height, and a rectangle with an area equal to the throttle valve opening area is considered as the equivalent opening area, and the relationship between this equivalent opening area and the deposit thickness is modeled.

[0073] FIG. 8 shows the equivalent opening area according to the deposit adhesion state. In the state without deposit adhesion, the equivalent opening area has the same area as the throttle valve opening area AA [m 2 , and is a rectangle with a height h [m] and a length l [m]. Also, when it is assumed that deposit adhesion occurs only on the throttle body (only the lower side in the figure), in the state of deposit adhesion, the equivalent opening area has the same area as the throttle valve opening area AA’, and a rectangle with a height h’ [m] and a length l [m] is taken as the equivalent opening area. The following relationships hold among the throttle valve opening area, the clearance, and the deposit thickness.

[0074]

Number

[0075]

Number

[0076] Here, D is the deposit thickness [m]. From equations (11) and (12), the reduction rate of the throttle valve opening area is related to the deposit thickness. So far, the geometric throttle valve opening area has been described, but equation (11) is assumed to hold for the effective throttle valve opening area and is applied to learning. Specifically, equation (13) is defined, and from the effective throttle valve opening area that can be obtained during driving, the deposit thickness can be calculated by equation (13).

[0077]

Number

[0078] In addition to the reduction rate of the effective throttle valve opening area, the flow rate reduction rate can also be used. Generally, under sonic conditions where the flow velocity becomes the speed of sound, it is known that the intake air flow rate is proportional to the effective throttle valve opening area. Therefore, the reduction rate of the effective throttle valve opening area and the flow rate reduction rate are equivalent. Thus, in equation (11), it is possible to use the flow rate reduction rate as an alternative to the reduction rate of the effective throttle valve opening area.

[0079] Figure 9 shows the deposit thickness, the reduction rate of the effective throttle valve opening area, and the flow rate reduction rate. The reduction rate of the effective throttle valve opening area and the flow rate reduction rate tend to take a constant value at a predetermined throttle valve opening. From this tendency, at two points where the effective throttle valve opening area and the flow rate reduction rate become constant values, θ A and θ BBy defining this, two points where the deposit thickness changes can be extracted, and the deposit thicknesses at the two points can be defined. As a result, based on limited information, the deposit thickness over a wide range in the flow direction can be defined.

[0080] As described above, to calculate the deposit thickness, it is necessary to calculate the effective opening area of the throttle valve. The effective opening area of the throttle valve can be calculated from Equation (14) derived from Equation (9) assuming that it is equal to the throttle valve passing gas flow rate per unit time and the intake air flow rate detection value dG AFS in the steady state.

[0081]

Equation

[0082] From Equation (14), the effective opening area of the throttle valve can be calculated by inputting the intake air flow rate detection value, the throttle valve upstream pressure detection value, the intake air temperature detection value, the upstream temperature detection value, and the intake pipe pressure. Here, when there is no throttle valve upstream pressure sensor, the throttle valve upstream pressure detection value can be substituted with the atmospheric pressure detection value only under non-supercharged conditions.

[0083] In this embodiment, since the learning value is obtained under conditions where the throttle valve opening is small (conditions where the rotational speed is low and the engine load is small), it is an engine operating range where the atmospheric pressure detection value can be substituted. As a result, even in a system that does not have a means for obtaining the pressure upstream of the throttle valve, it is possible to obtain the detection value of the throttle valve upstream pressure under non-supercharged conditions. However, depending on the system configuration such as the control method of the wastegate valve and the control method of the variable capacity turbocharger provided, the range where the atmospheric pressure detection value can be substituted changes, so it is desirable to confirm this range through prior tests or the like.

[0084] From the above, under non-boost conditions, the effective throttle valve opening area can be calculated by inputting the intake air flow detection value, intake air temperature detection value, atmospheric pressure detection value, and intake pipe pressure into equation (14). By using the detection values, the effective throttle valve opening area (hereinafter referred to as the actual effective throttle valve opening area) that reflects the change in the effective throttle valve opening area due to deposit adhesion can be calculated. Thereby, even when deposits adhere, the effective throttle valve opening area can be accurately calculated.

[0085] Fig. 10 shows a flowchart for calculating the effective throttle valve opening area according to the present embodiment. Here, the entire logic including the logic for determining whether it is a predetermined condition when learning the deposit thickness will be described. Details will be described step by step below. Note that steps s101 to s103 are blocks not shown in Fig. 3, steps s104 to s105 are the reduction rate correlation index calculation unit, steps s106 to s109 are the change point calculation unit, and steps s110 to s112 are processed by the effective throttle valve opening area calculation unit.

[0086] <<Step s101>> In step s101, the engine speed, intake air flow, intake air temperature, atmospheric pressure, and throttle valve opening are detected by the crank angle sensor, intake air flow sensor, intake air temperature sensor, atmospheric pressure sensor, and throttle valve opening sensor.

[0087] <<Step s102>>[[ID=1(15)]] In step s102, based on the throttle valve opening and the table of the effective throttle valve opening area at the time of new product (hereinafter referred to as the initial effective throttle valve opening area) with the pre-stored throttle valve opening as the axis, the initial effective throttle valve opening area μA0 [m 2 is calculated. By tabulating the effective throttle valve opening area at the time of new product in this way, the calculation load on the ECU can be reduced.

[0088] <<Step s103>> In step s103, it is determined whether all of the following three conditions are satisfied, and a determination is made on whether to perform deposit learning activation. (A1) The rotational speed is equal to or lower than the threshold value (A2) The engine load is equal to or lower than the threshold value (A3) The throttle valve opening is constant

[0089] (A1) and (A2) adopt a method of comparing the rotational speed and the engine load with their respective threshold values. Thereby, it is determined whether the non-supercharging condition is met. The threshold value here is defined as the range that can be determined as the non-supercharging region, and it is necessary to define in advance, by experiment, the range where the upstream pressure of the throttle valve is smaller than a predetermined value compared to the atmospheric pressure. Thereby, since the atmospheric pressure detection value can be used as the upstream pressure of the throttle valve, it becomes possible to calculate the effective opening area of the actual throttle valve with high precision, and false learning can be prevented. Also, when a throttle valve upstream pressure sensor is provided, the detection value of the throttle valve upstream pressure sensor can be used.

[0090] (A3) adopts a method of comparing the difference value between the value of the throttle valve opening a predetermined time ago and the current value with the threshold value. The threshold value here depends on the relationship between the change amount of the throttle valve opening and the change amount of the effective opening area of the throttle valve. For example, it can be defined as the change amount of the throttle valve opening within which the change amount of the effective opening area of the throttle valve falls within a predetermined range. Thereby, since it can be determined whether the throttle valve opening is constant, learning can be performed under stable conditions, and false learning can be prevented.

[0091] If the learning start determination (s103) is No, the process proceeds to step s112. If the determination is Yes, the process proceeds to step s104.

[0092] <<Step s104>> In step s104, the learned value of the deposit thickness at the detected throttle valve opening θ is calculated. Here, based on the relationship that the reduction rate of the effective opening area of the throttle valve is equal to the reduction rate of the clearance, the deposit thickness is calculated by equation (15).

[0093]

Equation

[0094] Here, D is the deposit thickness [m], h0 is the distance between the throttle body and the tip of the throttle valve at the time of new product (hereinafter referred to as the initial clearance) [m], and μA is the actual throttle valve effective opening area [m 2 . Here, the initial clearance can be geometrically determined from the throttle valve opening and the diameter of the throttle valve.

[0095] In this embodiment, the initial clearance is stored in the ECU in advance as a table with the throttle valve opening as the axis. This can reduce the calculation load of the ECU. Also, by calculating the deposit thickness in this way, the learning value of the deposit thickness at the throttle valve opening θ can be calculated with high accuracy.

[0096] <<Step s105>> In step s105, the learning value of the deposit thickness, the number of learning times, and the running distance at the time of learning value acquisition are updated in the learning value map for change point search. FIG. 11A shows the learning value map for change point search. In this map, with the throttle valve opening as the grid points, the number of learning times, the running distance at the time of learning value acquisition, the learning value acquisition completion flag, the learning value of the deposit thickness, and the learning value of the deposit thickness for change point search are recorded. Note that the initial values of all variables in this map are set to 0. Generally, the influence of deposits on the throttle valve effective opening area is large at low openings and becomes smaller as the throttle valve opening increases. Therefore, for example, by defining the grid points within the range affected by deposits, the storage area used by the ECU can be reduced.

[0097] Also in step s105, the map is updated with the weighted average value of the calculated learning value of the deposit thickness and the learning value of the deposit thickness held in the map as the new learning value of the deposit thickness. By using the weighted average, the learning value of the deposit thickness in the map changes gradually. Therefore, for example, even when the learning value changes rapidly, such as when an outlier is input instantaneously, mislearning can be suppressed. Also, each time the process of s105 is executed, the number of learning times is incremented by 1 with respect to the previous value at the corresponding location in the map, and the map is updated.

[0098] <<Step s106>> In step s106, when the number of acquisitions of the learning value and the travel distance at the time of acquiring the learning value satisfy the predetermined conditions shown below, it is determined that the acquisition of the learning value of the throttle valve opening degree θ is completed, and the acquisition completion flag of the learning value map for change point search is updated. Here, the acquisition completion flag of the learning value indicates that 1 represents acquisition completion and 0 represents non-acquisition. (B1) The number of acquisitions of the learning value is equal to or greater than the threshold value (B2) The difference between the travel distance at the time of acquiring the learning value and the current travel distance is within the threshold value

[0099] (In B1), a method of comparing the number of acquisitions of the learning value with the threshold value is adopted. By setting a threshold value for the number of acquisitions of the learning value, it is possible to determine whether the learning value has been acquired a sufficient number of times. (In B2), a method of comparing the difference between the travel distance at the time of acquiring the learning value and the current travel distance with the threshold value is adopted. Generally, as the travel distance increases, the deposit thickness also increases. Therefore, it is important at what timing the learning value is acquired in order to ensure the reliability of the learning value.

[0100] For example, when it is considered that the effective opening area of the throttle valve decreases by about 1% during a 100 km travel and it is desired to detect a 2% change in the effective opening area of the throttle valve, the threshold value is set to about 200 km. Since the learning value is sufficiently learned by (B1) and (B2) and the learning value of relatively new information can be used, the reliability of the learning value is improved and mislearning can be prevented.

[0101] If the determination of completion of acquisition of the learning value of the deposit thickness (s106) is No, the process proceeds to step s112. If the determination is Yes, the process proceeds to step s107.

[0102] <<Step s107>> In step s107, it is determined whether it is possible to search for a change point in the deposit thickness. The throttle valve opening degree for confirming the presence or absence of the learning value is θ C θ or more D θ or less. In the present embodiment, θ C and θ Dis the low opening degree change point θ assumed by prior tests, idle opening degree settings, etc. A and the high opening degree change point θ B are set in advance so as to be included in the range of θ C or more and θ D or less.

[0103] θ C or more and θ D or less, when the learning value acquisition completion flag is 1 at at least one point, it is determined that the change point can be searched. By setting this determination condition, when the learning value of the deposit thickness has been obtained, it is possible to quickly reflect it in the calculation of the effective opening area of the throttle valve without waiting for the completion of the acquisition of the learning value under other conditions.

[0104] If the determination that the change point can be searched (s107) is No, proceed to step s112. If the determination is Yes, proceed to step s108.

[0105] <<Step s108>> In step s108, the differential value of the learning value of the deposit thickness is calculated. Here, the learning value of the deposit thickness recorded in the learning map for change point search is substituted into equation (16), and the differential value of the deposit thickness with respect to the throttle valve opening degree is calculated.

[0106]

Equation

[0107] Here, α is the differential interval [deg] (α is an even number). For example, if it is desired to calculate the change in deposit thickness in increments of 1 deg of throttle valve opening degree, α is set to 2 deg.

[0108] <<Step s109>> In step s109, the change point of the deposit thickness is calculated. In this embodiment, a mechanism is adopted in which the point at which the differential value of the deposit thickness becomes equal to or greater than the threshold value is set as the change point. Here, the throttle valve opening degree at which the differential value calculated in step s108 becomes equal to or greater than the threshold value L1 is searched. The smallest opening degree that satisfies the same condition is Mmin。 Let the maximum opening be M. max If there is only one opening that satisfies the same conditions, M min。 and M max shall be the same value. The openings obtained by equations (17) and (18) are defined as the low-opening-side change point θ A [deg] and the high-opening-side change point θ B [deg]. By performing such processing, the low-opening-side change point and the high-opening-side change point can be calculated with high precision from among the openings for which the learning value of the deposit thickness has been acquired.

[0109]

Number

[0110]

Number

[0111] However, when the number of grid points for which the learning value of the deposit thickness has been acquired is as follows within the range where the throttle valve opening θ C is greater than or equal to θ D and less than or equal to, the low-opening-side change point, the high-opening-side change point, and the deposit thickness are determined as follows.

[0112] (i) When the number of such grid points is 1 Let the low-opening-side change point be θ C (θ A = θ C ), and let the high-opening-side change point be θ D (θ B = θ D ). Also, based on the tendency that the reduction rate of the effective opening area of the throttle valve takes a constant value within the range where the throttle valve opening θ A is greater than or equal to θ B and less than or equal to, the deposit thicknesses at the low-opening-side change point and the high-opening-side change point are calculated by the following equations (19) and (20). Here, let the grid point for which the learning value of the deposit thickness has been acquired be θ1 (see FIG. 11B). This makes it possible to define the low-opening-side change point, the high-opening-side change point, and the deposit thickness even when there is only one condition for which the learning value of the deposit thickness has been acquired.

[0113]

Number

[0114]

Number

[0115] (ii) When the number of grid points is 2 Throttle valve opening θ C Above θ D Among the grid points where the deposit thickness learning value has been obtained within the range below, the grid point θ1 with a small throttle valve opening is defined as the low-opening side change point, and the grid point θ2 with a large throttle valve opening is defined as the high-opening side change point (see Fig. 11C). Also, the value of the deposit thickness obtained by learning is used. Thus, even when the condition for obtaining the learning value of the deposit thickness is two points, the low-opening side change point, the high-opening side change point, and the deposit thickness can be defined.

[0116] <<Step s110>> In step s110, the deposit thickness at the opening where the learning value of the deposit thickness has not been obtained is calculated. Here, based on the fact that the deposit thickness is distributed in two stages, the deposit thickness at the opening where the learning value of the deposit thickness has not been obtained is calculated by equation (21).

[0117]

Number

[0118] According to (i), the deposit thickness in the throttle valve opening range less than the low opening side change point where the learned value of the deposit thickness cannot be obtained can be calculated with high precision. Also, according to (ii), the deposit thickness in the throttle valve opening range equal to or greater than the low opening side change point and less than or equal to the high opening side change point where the learned value of the deposit thickness cannot be obtained can be calculated with high precision. Further, according to (iii), the deposit thickness in the throttle valve opening range greater than the high opening side change point where the learned value of the deposit thickness cannot be obtained can be calculated with high precision.

[0119] <<Step s111>> In step s111, the learned value of the deposit thickness at the opening where the learned value of the deposit thickness has not been obtained is updated to the learning value map for change point search.

[0120] <<Step s112>> In step s112, the effective opening area of the throttle valve at an arbitrary throttle valve opening is calculated based on the deposit thickness. Here, the effective opening area of the throttle valve is calculated by equation (22).

[0121]

Equation

[0122] Thereby, the effective opening area of the throttle valve can be accurately calculated in the region above the throttle valve opening in the idle state.

[0123] Fig. 12 shows a time chart when deposit thickness learning is performed taking deceleration as an example in this embodiment. The vertical axis from the upper part is throttle valve opening, throttle valve opening change amount, engine torque, rotational speed, throttle valve upstream pressure calculated value, stable condition determination value, number of learning times, deposit thickness learned value, deposit thickness learned value acquisition completion determination value, throttle valve effective opening area calculated value, and the horizontal axis is time.

[0124] In FIG. 12, after the engine torque and the rotational speed enter the learning condition range (the range is indicated by a dotted line), when the change amount of the throttle valve opening degree falls within a predetermined value range (less than the steady determination reference value indicated by the dotted line), it is determined that the throttle valve opening degree has stabilized.

[0125] The time when these three conditions are satisfied and the flag for stable condition determination (stable condition determination value) becomes ON is time t1. Acquisition of the learned value of the deposit thickness starts at time t1. As the number of learning times increases and exceeds the learning completion criterion at time t2, the flag for completion determination of the learned value of the deposit thickness becomes ON. Thereby, the calculated value of the effective opening area of the throttle valve is corrected. Due to the correction, the calculated value of the upstream pressure of the throttle valve increases and coincides with the atmospheric pressure.

[0126] FIG. 13 is a time chart during acceleration in the case where deposit thickness learning has been performed and in the case where there is no learning in the present embodiment. The vertical axis represents the throttle valve opening degree, the rotational speed, the calculated value of the upstream pressure of the throttle valve, the calculated value of the downstream pressure of the throttle valve, the calculated value of the in-cylinder inflow gas flow rate, the calculated value of the effective opening area of the throttle valve, and the exhaust air-fuel ratio, and the horizontal axis represents time. The solid line indicates the case of having learned, and the broken line indicates the case of not having learned.

[0127] Acceleration starts at time t3. In the case of no learning, the exhaust air-fuel ratio becomes lean during acceleration, whereas in the case of having learned, there is no fluctuation in the exhaust air-fuel ratio. This is because even when deposits adhere, the effective opening area of the throttle valve is corrected by learning, and the in-cylinder inflow gas flow rate can be calculated with high accuracy. Thereby, control of an appropriate fuel injection amount becomes possible, and deterioration of fuel consumption and exhaust emissions can be prevented.

[0128] According to this embodiment, when a predetermined learning condition is satisfied, an index correlated with the reduction rate of the effective opening area of the throttle valve is calculated based on the opening degree of the throttle valve provided in the intake passage of the internal combustion engine, the rotational speed of the internal combustion engine, the intake air amount passing through the throttle valve, the upstream pressure of the throttle valve, the downstream pressure of the throttle valve, and the atmospheric temperature. Based on the change amount of the index with respect to the throttle valve opening degree, the change point of the index is determined, and based on the change point of the index, the effective opening area of the throttle valve is calculated.

[0129] Thereby, even when deposits adhere to the throttle body, the effective opening area of the throttle valve can be calculated with high accuracy. Also, since the in-cylinder inflow gas flow rate during transient operation can be calculated with high accuracy, appropriate control of the fuel injection amount becomes possible, and deterioration of fuel consumption and exhaust emissions can be prevented.

[0130] (Embodiment 2) In Embodiment 2, when deposits adhere to the throttle body, a method for obtaining a learned value of the deposit thickness under a desired throttle valve opening condition by operating the intake valve closing timing and the exhaust valve closing timing is shown.

[0131] As described in Embodiment 1, in order to calculate the change point of the deposit thickness, it is necessary to obtain learned values of the deposit thickness at a plurality of opening degrees in the idle opening range. This embodiment is devised in view of this situation. In Embodiment 2 described below, the configuration other than the differences from Embodiment 1 is the configuration described in Embodiment 1.

[0132] First, the method for operating the closing timing of the intake valve and the exhaust valve and the method for operating the throttle valve opening degree implemented in this embodiment will be described. Subsequently, the specific processing of this embodiment will be described.

[0133] First, a method for operating the closing timing of the intake valve and the exhaust valve and a method for operating the throttle valve opening degree implemented in this embodiment will be described. FIG. 14 is a diagram showing the relationship between the valve overlap amount and the throttle valve opening degree that realizes a constant output under the condition of a constant rotational speed. Here, the valve overlap amount is the period during which both the intake valve and the exhaust valve are open simultaneously.

[0134] As a method for changing the valve overlap amount, an operation is performed on the variable valve mechanism to operate the intake valve or the exhaust valve, and the opening timing of the intake valve is set to be more advanced than the closing timing of the exhaust valve. As shown in FIG. 14, under the conditions of a constant rotational speed and a constant output, the valve overlap amount and the throttle valve opening degree have a positive correlation. Here, when the rotational speed is constant, increasing the valve overlap amount increases the combustion gas (internal EGR gas) carried over to the next cycle. As a result, if the throttle valve opening degree is not operated, the intake air flow rate decreases. In order to keep the intake air flow rate constant, it is necessary to increase the throttle valve opening degree.

[0135] By operating the variable valve mechanism and the throttle valve opening degree so that the valve overlap amount and the throttle valve opening degree have a positive correlation in this way, various throttle valve opening degrees can be set. As a result, at various throttle valve opening degrees, it is possible to obtain a learned value of the deposit thickness while preventing deterioration of drivability. Furthermore, for example, by setting a combination of the variable valve mechanism and the throttle valve opening degree under the condition that the valve overlap amount increases (in the right direction in FIG. 14), the amount of high-temperature combustion gas remaining in the cylinder can be increased. As a result, since the in-cylinder gas temperature increases, combustion stability can be improved even under conditions where the engine coolant temperature is low and combustion stability is poor, and learning can be performed in a stable engine operating state. Also, it becomes possible to widen the learnable coolant temperature range.

[0136] Subsequently, the specific processing of this embodiment will be described. FIG. 15 shows a flowchart for learning the deposit thickness and correcting the effective opening area of the throttle valve in this embodiment. Details will be described step by step below.

[0137] From step S201 to step S203, and from step S207 to step S215, since the processing is the same as that from step S101 to step S103 and from step S104 to step S112 in Embodiment 1, the description thereof will be omitted.

[0138] <<Step S204>> In step S204, it is determined whether the throttle valve opening degree matches the learning target throttle valve opening degree. Here, a method of comparing the difference between the throttle valve opening degree and the learning target throttle valve opening degree with a threshold value is adopted. Also, the learning target throttle valve opening degree is, for example, the minimum opening degree, the intermediate opening degree, and the maximum opening degree within the preset usage range of the idle opening degree.

[0139] If the determination (S204) is Yes, the process proceeds to S207. If the determination is No, the process proceeds to step S205.

[0140] <<Step S205>> In step S205, based on the relationship between the throttle valve opening degree and the valve "overlap amount" as shown in FIG. 14, the target intake valve closing timing and the target exhaust valve closing timing for realizing the target throttle valve opening degree set in step S204 are calculated.

[0141] <<Step S206>> In step S206, the intake valve, the exhaust valve, and the throttle valve opening degree are operated so as to achieve the target intake valve closing timing, the target exhaust valve closing timing, and the learning target throttle valve opening degree. By these operations, while keeping the rotational speed and the output constant, the combustion stability can be improved. Thereby, the deterioration of drivability can be prevented, and the learned value of the deposit thickness can be obtained.

[0142] After step S206 is completed, the process proceeds to step S203.

[0143] By operating the variable valve mechanism and throttle valve opening provided in the internal combustion engine so that the valve overlap amount and the throttle valve opening, at which both the intake valve and the exhaust valve are open, have a positive correlation, while keeping the rotational speed and output constant, the combustion stability is improved, so that the deterioration of drivability can be prevented and the learning value of the deposit thickness can be obtained.

[0144] As a result, since the learning value of the deposit thickness can be obtained at a plurality of openings in the idle state, the effective opening area of the throttle valve can be calculated with high accuracy. Also, as a result, even when deposits adhere to the throttle body, the in-cylinder inflow gas flow rate during transient operation can be calculated with high accuracy, so that appropriate control of the fuel injection amount is possible and deterioration of fuel consumption and exhaust emissions can be prevented.

[0145] The main features of Embodiments 1 and 2 can also be summarized as follows.

[0146] The processor (CPU40e, FIG. 2) of the control device (ECU0) of the internal combustion engine identifies the first throttle valve opening θ at which the change rate (differential value) of an index (deposit thickness, reduction rate of effective opening area, flow rate reduction rate, etc., FIG. 9) correlated with the reduction rate of the effective opening area of the throttle valve changes, and the second throttle valve opening θ (s109, FIG. 10). The processor (CPU40e) estimates the index at an arbitrary throttle valve opening from the first throttle valve opening θ and the second throttle valve opening θ (s110, FIG. 10), and calculates the effective opening area of the throttle valve from the estimated index (s112, FIG. 10). A and the second throttle valve opening θ B The processor (CPU40e) A and the second throttle valve opening θ B From this, the effective opening area of the throttle valve reflecting the influence of the deposit can be accurately calculated.

[0147] As a result, the effective opening area of the throttle valve reflecting the influence of the deposit can be accurately calculated.

[0148] As shown in FIG. 9, the index is, for example, the thickness of deposits accumulated on the throttle body, the rate of decrease in the air flow rate passing through the throttle valve, or the rate of decrease in the effective opening area of the throttle valve. Thereby, not only the thickness of the deposits but also the effective opening area of the throttle valve can be calculated from the rate of decrease in the flow rate or the rate of decrease in the effective opening area.

[0149] The processor (CPU40e) determines the first throttle valve opening θ A In the range of throttle valve openings smaller than, the value D(θ) of the index (for example, deposit thickness) is set to the first throttle valve opening θ A At the index value D(θ A ) is estimated to be a constant value equal to ((i) of equation (21)). Thereby, in the range on the lower opening side than the first throttle valve opening θ A The effective opening area of the throttle valve can be accurately calculated.

[0150] The processor (CPU40e) determines the second throttle valve opening θ B In the range of throttle valve openings larger than, the value D(θ) of the index (for example, deposit thickness) is set to the second throttle valve opening θ B At the index value D(θ B ) is estimated to be a constant value equal to ((iii) of equation (21)). Thereby, in the range on the higher opening side than the second throttle valve opening θ B The effective opening area of the throttle valve can be accurately calculated.

[0151] The processor (CPU40e) determines the first throttle valve opening θ A And the second throttle valve opening θ B In the range between, the value D(θ) of the index (for example, deposit thickness) is set to the first throttle valve opening θ A At the index value D(θ A ) and the second throttle valve opening θ B At the index value D(θ B ) ((ii) of equation (21)). Thereby, the first throttle valve opening θ A And the second throttle valve opening θ BIt is possible to accurately calculate the effective opening area of the throttle valve within a range with respect to

[0152] In this embodiment, the first throttle valve opening θ A and the second throttle valve opening θ B The throttle valve opening and the index value (for example, deposit thickness) in the range between them have a linear relationship ((ii) of formula (21)). Thereby, the effective opening area of the throttle valve can be calculated using the linear relationship.

[0153] The processor (CPU40e) is at the throttle valve opening where the change rate dD / dθ of the index (for example, deposit thickness) with respect to the throttle valve opening is within a predetermined range (for example, dD / dθ ≧ predetermined value L1), and the minimum throttle valve opening M min Based on this, the first throttle valve opening θ A is identified, and the maximum throttle valve opening M max Based on this, the second throttle valve opening θ B is identified (s109, FIG. 10). Thereby, within a predetermined range, the first throttle valve opening θ A and the second throttle valve opening θ B can be identified.

[0154] In this embodiment, the predetermined range is a range where the change rate dD / dθ of the index with respect to the throttle valve opening is equal to or greater than a predetermined value L1. Thereby, the range for searching for the first throttle valve opening θ A and the second throttle valve opening θ B can be narrowed.

[0155] The processor (CPU40e) calculates, as the learned value of the index, a value obtained by weighted-averaging the previous value and the current value of the index (for example, deposit thickness) (s105, FIG. 10). Thereby, the influence of outliers can be reduced.

[0156] The processor (CPU40e) determines whether the acquisition of the learning value of the index is completed based on the number of times the index is calculated and the difference between the travel distance at the time of calculating the index and the current travel distance (s106, FIG. 10). Thereby, the reliability of the learning value of the index is improved.

[0157] The processor (CPU40e) is within a range of a predetermined throttle valve opening degree (θ C ≦ θ ≦ θ D ), when there is at least one or more learning values of the acquired index (for example, deposit thickness), from the throttle valve opening degree (for example, θ1, θ2, etc.) corresponding to the learning value of the index, the first throttle valve opening degree θ A and the second throttle valve opening degree θ B are identified (FIGS. 11B and 11C). Thereby, when there is at least one or more learning values of the index, the first throttle valve opening degree θ A and the second throttle valve opening degree θ B can be identified.

[0158] The processor (CPU40e) is within a range of a predetermined throttle valve opening degree (θ C ≦ θ ≦ θ D ), when there is only one learning value of the acquired index (for example, deposit thickness), based on the throttle valve opening degree θ1 corresponding to the learning value D(θ1) of the index, the first throttle valve opening degree θ A and the second throttle valve opening degree θ B are identified (FIG. 11B). Thereby, even when there is one learning value of the index, the first throttle valve opening degree θ A and the second throttle valve opening degree θ B can be identified.

[0159] The processor (CPU40e) controls the throttle valve, the variable intake valve, and the variable exhaust valve so that the valve overlap amount increases as the throttle valve opening degree increases (FIG. 14), and learns the index (for example, deposit thickness) and the corresponding throttle valve opening degree (s206, FIG. 15).

[0160] As a result, it is possible to learn the index and the corresponding throttle valve opening degree while maintaining the rotational speed and the output torque.

[0161] Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Also, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0162] In addition, each of the above configurations, functions, etc. may be realized in hardware by designing a part or all of them, for example, by an integrated circuit. Also, each of the above configurations, functions, etc. may be realized in software by a processor interpreting and executing a program for realizing each function. Information such as a program, a table, a file, etc. for realizing each function can be placed in a memory, a recording device such as a hard disk, an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, a DVD.

[0163] Note that the embodiments of the present invention may also be the following aspects.

[0164] [1]. When predetermined learning conditions are satisfied, based on the opening degree of a throttle valve provided in an intake passage of an internal combustion engine, the rotational speed of the internal combustion engine, the intake air amount passing through the throttle valve, the upstream pressure of the throttle valve, the downstream pressure of the throttle valve, and the atmospheric temperature, a reduction rate correlation index calculation unit that calculates an index correlated with the reduction rate of the effective opening area of the throttle valve with respect to the flow direction at a first throttle valve opening degree and a second throttle valve opening degree, and a throttle valve effective opening area calculation unit that calculates the effective opening area of the throttle valve based on the index. In a control device for an internal combustion engine, a change point calculation unit that determines the first throttle valve opening degree and the second throttle valve opening degree based on a change in the index with respect to the throttle valve opening degree. A control device for an internal combustion engine, characterized by comprising the above components.

[0165] [2]. The control device for an internal combustion engine according to [1], characterized in that the index is the thickness of deposits accumulating on the throttle body, or the flow rate reduction rate, or the reduction rate of the effective opening area of the throttle valve.

[0166] [3]. The control device for an internal combustion engine according to [2], characterized in that the value of the index at a throttle valve opening degree less than the first throttle valve opening degree is equal to the value of the index at the first throttle valve opening degree.

[0167] [4]. The control device for an internal combustion engine according to [3], characterized in that the value of the index at a throttle valve opening degree greater than the second throttle valve opening degree is equal to the value of the index at the second throttle valve opening degree.

[0168] [5]. The control device for an internal combustion engine according to [4], characterized in that the value of the index at a throttle valve opening degree within the range of the first throttle valve opening degree and the second throttle valve opening degree is calculated based on the value of the index at the first throttle valve opening degree and the value of the index at the second throttle valve opening degree.

[0169] [6]. The control device for an internal combustion engine according to [5], wherein the change in the index with respect to the throttle valve opening is within a predetermined range at the throttle valve opening, and the minimum opening is the first throttle valve opening and the maximum opening is the second throttle valve opening.

[0170] [7]. The control device for an internal combustion engine according to [6], wherein a value obtained by weighted-averaging the previous value and the current value of the index is calculated as the learned value of the index.

[0171] [8]. The control device for an internal combustion engine according to [7], wherein it is determined whether acquisition of the learned value of the index is completed based on the number of times the index is calculated and the difference between the travel distance at the time of index calculation and the current travel distance.

[0172] [9]. The control device for an internal combustion engine according to [8], wherein when at least one learned value of the index can be obtained within a predetermined throttle valve opening range, it is determined that the first throttle valve opening and the second throttle valve opening are searchable.

[0173]

[10] . The control device for an internal combustion engine according to [9], wherein when the number of points at which the learned value of the index is obtained is one within a predetermined throttle valve opening range, the first throttle valve opening and the second throttle valve opening are calculated as the predetermined throttle valve opening, and the index of the first throttle valve opening and the second throttle valve opening is calculated based on the learned value of the point at which the learned value is obtained.

[0174]

[11] . The control device for an internal combustion engine according to

[10] , wherein when calculating the index, the throttle valve opening and the intake valve opening / closing timing are operated within a range where the rotational speed is within a predetermined range.

[0175] According to [1] to

[11] , the effective opening area of the throttle valve can be accurately calculated in the throttle valve opening area equal to or greater than the throttle valve opening in the idle state. As a result, even when deposits adhere, the gas flow rate passing through the throttle valve can be calculated with high precision. Consequently, the gas flow rate flowing into the cylinder can be calculated with high precision, enabling appropriate control of the fuel injection amount and preventing deterioration of fuel consumption and exhaust emissions.

Explanation of Signs

[0176] 100…Engine (Internal Combustion Engine), 0…ECU, 1…Accelerator Opening Sensor, 3…Intake Air Flow Sensor, 4…Supercharger, 5…Intercooler, 6…Throttle Valve, 8…Intake Pipe, 9a…Variable Intake Valve, 9b…Variable Exhaust Valve, 10…Fuel Injection Device, 11…Spark Plug, 12…Crank Angle Sensor, 13…Combustion Chamber, 14…Exhaust Pipe, 15…Intake Air Temperature Sensor, 16…Atmospheric Pressure Sensor, 20…Air-Fuel Ratio Sensor, 21…Catalytic Converter, 30…EGR Cooler, 31…EGR Valve, 32…EGR Pipe

Claims

1. identifying a first throttle valve opening degree and a second throttle valve opening degree at which a change rate of an index correlated with a reduction rate of an effective opening area of a throttle valve changes; estimating the index at an arbitrary throttle valve opening degree from the first throttle valve opening degree and the second throttle valve opening degree; comprising a processor that calculates an effective opening area of the throttle valve from the estimated index; the processor: estimating a value of the index in a range of throttle valve opening degrees smaller than the first throttle valve opening degree as a constant value equal to the value of the index at the first throttle valve opening degree; estimating a value of the index in a range of throttle valve opening degrees larger than the second throttle valve opening degree as a constant value equal to the value of the index at the second throttle valve opening degree; estimating a value of the index in a range between the first throttle valve opening degree and the second throttle valve opening degree based on the value of the index at the first throttle valve opening degree and the value of the index at the second throttle valve opening degree; identifying the first throttle valve opening degree based on a minimum throttle valve opening degree and identifying the second throttle valve opening degree based on a maximum throttle valve opening degree at a throttle valve opening degree at which a change rate of the index with respect to the throttle valve opening degree is within a predetermined range; A control device for an internal combustion engine, characterized in that a value obtained by weighted-averaging a previous value and a current value of the index is calculated as a learned value of the index.

2. The control device for an internal combustion engine according to claim 1, wherein the index is the thickness of deposits accumulated on the throttle body, the air flow rate reduction rate passing through the throttle valve, or the reduction rate of the effective opening area of the throttle valve. A control device for an internal combustion engine, characterized by the above.

3. The control device for an internal combustion engine according to claim 1, wherein the processor: determines whether acquisition of the learned value of the index is completed based on the number of times the index is calculated and the difference between the running distance at the time of calculating the index and the current running distance. A control device for an internal combustion engine, characterized by the above.

4. The control device for an internal combustion engine according to claim 3, wherein the processor: identifies the first throttle valve opening degree and the second throttle valve opening degree from the throttle valve opening degrees corresponding to the learned values of the index when at least one or more learned values of the index for which acquisition is completed are present in a predetermined range of throttle valve opening degrees. A control device for an internal combustion engine, characterized by the above.

5. A control device for an internal combustion engine according to claim 4, wherein the processor identifies the first throttle valve opening degree and the second throttle valve opening degree based on the throttle valve opening degree corresponding to the learning value of the index when there is only one learning value of the index for which acquisition has been completed within the range of the predetermined throttle valve opening degree. A control device for an internal combustion engine, characterized by the above.

6. A control device for an internal combustion engine according to claim 1, wherein the processor controls the throttle valve, the variable intake valve, and the variable exhaust valve so that the valve overlap amount increases as the throttle valve opening degree increases, thereby learning the index and the corresponding throttle valve opening degree. A control device for an internal combustion engine, characterized by the above.

7. A control device for an internal combustion engine according to claim 1, wherein a throttle valve opening degree within a range between the first throttle valve opening degree and the second throttle valve opening degree and a value of the index have a linear relationship. A control device for an internal combustion engine, characterized by the above.

8. A control device for an internal combustion engine according to claim 1, wherein the predetermined range is a range in which a change rate of the index with respect to the throttle valve opening degree is equal to or greater than a predetermined value. A control device for an internal combustion engine, characterized by the above.

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