JP2011190781A - Cylinder intake air amount calculation device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cylinder intake air amount calculation device, reducing the number of maps or tables used for calculating a predicted value (a predicted cylinder intake air amount) of a cylinder intake air amount, and constantly calculating an accurate predicted cylinder intake air amount without influence of changes with time in engine characteristics. <P>SOLUTION: A stoichiometric cylinder intake air amount GAIRSTD is calculated based on intake pressure PBA and an intake temperature TA, volumetric efficiency ηv'(=GAIRCYLP(k)/GAIRSTD(k)) is calculated by using the stoichiometric cylinder intake air amount GAIRSTD, and the volumetric efficiency ηv' is corrected by using a lift amount correction coefficient KLIFT set according to an intake valve lift amount LIFT to calculate predicted volumetric efficiency ηva. A predicted cylinder intake air amount GAIRCYL is calculated by using a last cylinder intake air amount GAIRCYLP recalculated by using a detected lift amount LIFT, an estimated throttle valve passage air amount HGAIRTH, and the predicted volumetric efficiency ηva. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cylinder intake air amount calculation device that calculates a cylinder intake air amount that is a fresh air amount drawn into a cylinder of an internal combustion engine, and in particular, an internal combustion engine having a valve operating mechanism capable of changing a lift amount of an intake valve. This relates to the calculation of the cylinder intake air amount.

  Patent Document 1 discloses an apparatus that calculates a cylinder intake air amount using an engine speed, intake pressure, and charging efficiency (volumetric efficiency). According to this device, the air-fuel ratio learning value that corrects the variation in the charging efficiency is calculated according to the detected air-fuel ratio, and the cylinder intake air amount is calculated using the charging efficiency that is corrected by the air-fuel ratio learning value.

  Patent Document 2 discloses a fuel injection amount control device that calculates a predicted value of a cylinder intake air amount of an internal combustion engine and calculates a fuel injection amount based on the calculated predicted value. According to this apparatus, the current predicted value of the cylinder intake air amount is obtained by applying the previous predicted value of the cylinder intake air amount and the detected intake air flow rate to the physical model equation set based on the intake mass conservation law. The fuel injection amount is calculated based on the calculated current predicted value. By using the predicted value, the accuracy of air-fuel ratio control in the transient operation state of the engine is improved.

JP 7-259630 A Japanese Patent Laid-Open No. 2-157451

  In the apparatus disclosed in Patent Document 1, the charging efficiency is calculated by searching a map set according to the engine speed and the intake pressure. Therefore, man-hours are required to set the map in advance. Further, in an engine equipped with a valve mechanism that changes the operating characteristics (lift amount, opening / closing valve timing) of the intake valve (and exhaust valve), a plurality of maps are provided according to the operating characteristics of the intake valve (and exhaust valve). It is necessary, and the map setting man-hour becomes enormous. Further, in order to cope with an operation state different from the engine operation state at the time of map setting, correction of the map search value (for example, correction by the above-described air-fuel ratio learning value) is necessary.

  In order to improve the air-fuel ratio control accuracy in the transient operation state of the engine, it is effective to use a predicted value of the cylinder intake air amount as disclosed in Patent Document 2. However, since the predicted value naturally includes a prediction error, the method of Patent Document 2 that calculates the predicted value of the cylinder intake air amount using the previous predicted value has room for improvement in terms of calculation accuracy of the predicted value. It was.

  The present invention reduces the number of maps and tables used to calculate the predicted value of the cylinder intake air amount (predicted cylinder intake air amount), and is always accurate and predictable cylinder intake without being affected by changes in engine characteristics over time. It is an object of the present invention to provide a cylinder intake air amount calculation device capable of obtaining an air amount.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a cylinder intake air amount that is a fresh air amount sucked into a cylinder of an internal combustion engine having a valve operating mechanism (40) capable of changing a lift amount of the intake valve. In the cylinder intake air amount calculation device for the internal combustion engine to be calculated, an intake air flow rate acquisition means for acquiring an intake air flow rate (HGAIR) which is a flow rate of fresh air passing through the intake pipe (2) of the engine; Intake pressure detection means for detecting intake pressure (PBA), intake air temperature detection means for detecting intake air temperature (TA), which is the temperature of air sucked into the engine, intake pressure (PBA) and intake air temperature (TA) ) Based on the theoretical cylinder intake air amount (GAIRSTD), and the volume efficiency of calculating the volume efficiency (ηv ′) of the engine using the theoretical cylinder intake air amount (GAIRSTD). Calculation A volume efficiency correction means for correcting the volume efficiency (ηv ′) according to the lift amount (LIFT) of the intake valve and calculating a corrected volume efficiency (ηva), the intake air flow rate (HGAIR) and the correction A predicted cylinder intake air amount calculating means for calculating a predicted cylinder intake air amount (GAIRCYL) that is a predicted value of the cylinder intake air amount using volumetric efficiency (ηva), and the predicted cylinder intake air amount calculating means includes: The predicted cylinder intake air amount (GAIRCYL) is calculated using a past equivalent value (GAIRCYLP) of the predicted cylinder intake air amount, and the volumetric efficiency calculating means calculates a past equivalent value (GAIRCYLP) of the predicted cylinder intake air amount. The volumetric efficiency (ηv ′) is calculated by dividing by the theoretical cylinder intake air amount (GAIRSTD).

  According to a second aspect of the present invention, in the cylinder intake air amount calculation device of the internal combustion engine according to the first aspect, the volumetric efficiency correction means uses the predicted value (HLIFT) of the lift amount to calculate the corrected volumetric efficiency (HLIFT). ηva) is calculated.

  According to a third aspect of the present invention, in the cylinder intake air amount calculation device for an internal combustion engine according to the first or second aspect, the apparatus further comprises a lift amount detection means for detecting a lift amount (LIFT) of the intake valve, and the predicted cylinder. The intake air amount calculating means calculates the past equivalent value (GAIRCYLP) using the detected lift amount (LIFT).

  According to the first aspect of the present invention, the theoretical cylinder intake air amount is calculated based on the intake pressure and the intake air temperature, and the volumetric efficiency of the engine is calculated using the theoretical cylinder intake air amount. The corrected volumetric efficiency is calculated by correcting according to the lift amount, and the predicted cylinder intake air amount is calculated using the intake air flow rate and the corrected volumetric efficiency. In calculating the predicted cylinder intake air amount, a past equivalent value of the predicted cylinder intake air amount is applied, and volume efficiency is calculated by dividing the past equivalent value by the theoretical cylinder intake air amount. Thereby, the number of maps and tables used for calculating the predicted cylinder intake air amount can be reduced. In addition, since the volumetric efficiency is updated using the detection parameter, it is possible to always obtain an accurate predicted cylinder intake air amount without being affected by changes in engine characteristics over time. Furthermore, volumetric efficiency changes when the lift amount of the intake valve is changed, so using the corrected volumetric efficiency corrected according to the lift amount reflects changes in volumetric efficiency as the lift amount changes, and transient operation Even in the state, an accurate predicted cylinder intake air amount can be calculated.

  According to the second aspect of the invention, since the corrected volumetric efficiency is calculated using the predicted value of the intake valve lift amount, it is possible to increase the accuracy of volumetric efficiency calculation in the transient operation state.

  According to the third aspect of the present invention, since the past equivalent value of the predicted cylinder intake air amount is calculated using the detected lift amount, the previous value of the predicted cylinder intake air amount is used as the past equivalent value. Compared to the above, it is possible to reduce an error caused by using the predicted value of the lift amount.

It is a figure which shows the structure of the internal combustion engine and its control apparatus concerning one Embodiment of this invention. It is a figure for demonstrating operation | movement of a valve action characteristic variable apparatus. It is a figure which shows typically the intake system of an internal combustion engine. It is a time chart for demonstrating the calculation method of the cylinder intake air amount in a transient state. 6 is a flowchart of a process for calculating a predicted cylinder intake air amount. It is a figure which shows the table referred by the process of FIG. It is a flowchart of the HGAIRTHP calculation process performed by the process of FIG. It is a figure which shows the map and table referred by the process of FIG. It is a flowchart of the HLIFFTP calculation process performed by the process of FIG. It is a figure for demonstrating the process of FIG. It is a figure which shows the table referred by the process of FIG. It is a flowchart of the HLIFT calculation process performed by the process of FIG. It is a flowchart of the HGAIRTH calculation process performed by the process of FIG.

Embodiments of the present invention will be described below with reference to 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. For example, an internal combustion engine (hereinafter simply referred to as “engine”) 1 having four cylinders includes an intake valve and an exhaust valve. A first valve operating characteristic variable mechanism that includes cams that drive these, and that continuously changes the lift amount and opening angle (valve opening period) of the intake valve, and the crankshaft rotation angle of the cam that drives the intake valve Is provided with a variable valve operation characteristic device 40 having a second valve operation characteristic variable mechanism as a cam phase variable mechanism that continuously changes the operation phase with reference to.

  A throttle valve 3 is arranged in the middle of the intake pipe 2 of the engine 1. A throttle valve opening (TH) sensor 4 is connected to the throttle valve 3, and an electric signal corresponding to the opening of the throttle valve 3 is output to an electronic control unit (hereinafter referred to as “ECU”) 5. Supply. An actuator 7 that drives the throttle valve 3 is connected to the throttle valve 3, and the operation of the actuator 7 is controlled by the ECU 5.

  The 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). At the same time, it is electrically connected to the ECU 5 and the opening time and timing of the fuel injection valve 6 are controlled by a signal from the ECU 5.

The ignition plug 13 of each cylinder of the engine 1 is connected to the ECU 5, and the ECU 5 supplies an ignition signal to the ignition plug 13 to perform ignition timing control.
An intake air flow rate sensor 14 for detecting the intake air flow rate GAIR and an intake air temperature sensor 9 for detecting the intake air temperature TA are provided on the upstream side of the throttle valve. An intake pressure sensor 8 that detects an intake pressure PBA is attached downstream of the throttle valve 3, and an engine coolant temperature sensor 10 that detects an engine coolant temperature TW is attached to the main body of the engine 1. Detection signals of these sensors 8 to 10 and 14 are supplied to the ECU 5.

  The ECU 5 includes a crank angle position sensor 11 that detects a rotation angle of a crankshaft (not shown) of the engine 1 and a cam angle that detects a rotation angle of a camshaft to which a cam that drives an intake valve of the engine 1 is fixed. A position sensor 12 is connected, and signals corresponding to the rotation angle of the crankshaft and the rotation angle of the camshaft are supplied to the ECU 5. The crank angle position sensor 11 generates one pulse (hereinafter referred to as “CRK pulse”) for every predetermined crank angle cycle (for example, a cycle of 6 degrees) and a pulse for specifying a predetermined angular position of the crankshaft. The cam angle position sensor 12 has a pulse (hereinafter referred to as “CYL pulse”) at a predetermined crank angle position of a specific cylinder of the engine 1 and a pulse (hereinafter referred to as “TDC”) at the start of the intake stroke of each cylinder. "TDC pulse"). These pulses are used for various timing controls such as fuel injection timing and ignition timing, and detection of engine speed (engine speed) NE. The actual operating phase CAIN of the camshaft is detected from the relative relationship between the TDC pulse output from the cam angle position sensor 12 and the CRK pulse output from the crank angle position sensor 11.

  The ECU 5 includes an accelerator sensor 31 for detecting an accelerator pedal depression amount (hereinafter referred to as “accelerator pedal operation amount”) AP of a vehicle driven by the engine 1 and a vehicle speed sensor 32 for detecting a traveling speed (vehicle speed) VP of the vehicle. , And an atmospheric pressure sensor 33 for detecting the atmospheric pressure PA is connected. Detection signals from these sensors are supplied to the ECU 5.

  The valve operating characteristic variable device 40 continuously changes the intake valve operating phase and the first valve operating characteristic variable mechanism that continuously changes the maximum lift amount and opening angle (hereinafter simply referred to as “lift amount”) of the intake valve. A second valve operating characteristic variable mechanism to be changed and an actuator for driving these mechanisms are provided. The configuration of the first valve operating characteristic variable mechanism is shown in, for example, Japanese Patent Application Laid-Open No. 2008-25418, and the specific configuration of the second valve operating characteristic variable mechanism is shown in, for example, Japanese Patent Application Laid-Open No. 2000-227013. ing.

  The lift amount is changed by the first valve operation characteristic variable mechanism by rotating a control shaft included in the mechanism by an actuator, and CS that detects a rotation angle (hereinafter referred to as “CS angle”) CSA of the control shaft. An angle sensor 15 is provided, and a detection signal thereof is supplied to the ECU 5. The lift amount LIFT is detected by the CS angle CSA. As a parameter indicating the operation phase of the intake valve, the valve operation phase VTC calculated from the operation phase CAIN of the camshaft is used.

  The lift amount LIFT of the intake valve is changed by the first valve operating characteristic variable mechanism as shown in FIG. In addition, the second valve operating characteristic variable mechanism causes the intake valve to center on the characteristics indicated by the solid lines L3 and L4 in FIG. 5B, with the most advanced angles indicated by the broken lines L1 and L2 as the cam operating phase CAIN changes. It is driven at a phase between the phase and the most retarded angle phase indicated by alternate long and short dash lines L5 and L6. In the present embodiment, the valve operation phase VTC is defined as an advance amount with the most retarded phase as a reference (0 degree).

The engine 1 is also provided with an exhaust gas recirculation mechanism (not shown), and the exhaust gas of the engine 1 is recirculated to the downstream side of the throttle valve 3 in the intake pipe 2.
The ECU 5 shapes input signal waveforms from various sensors, corrects the voltage level to a predetermined level, converts an analog signal value into a digital signal value, etc., and a central processing unit (hereinafter referred to as “CPU”). And an output circuit for supplying a drive signal to the actuator 7, the fuel injection valve 6, and the valve operation characteristic variable device 40, in addition to a storage circuit for storing a calculation program executed by the CPU, a calculation result and the like.

  The CPU of the ECU 5 controls the ignition timing, the opening degree of the throttle valve 3, the control of the amount of fuel supplied to the engine 1 (opening time of the fuel injection valve 6), and the intake valve according to the detection signal of the sensor. Perform operation control.

  Further, the CPU of the ECU 5 determines the predicted cylinder intake air amount GAIRCYL [g / TDC] (1 TDC period, which is a predicted value of the new air amount sucked into the cylinder of the engine 1 based on the detected intake pressure PBA and intake air temperature TA. That is, the amount of air per hour required for the crankshaft of the engine 1 to rotate 180 degrees is calculated. The calculated cylinder intake air amount GAIRCYLN is applied to control of the fuel supply amount and ignition timing.

  A method of calculating the cylinder intake air amount GAIRCYLN in a steady operation state where the intake valve lift amount LIFT is substantially constant will be described with reference to FIG.

FIG. 3 is a diagram schematically showing the engine 1, and shows an intake valve 21, an exhaust valve 22, and a cylinder 1a. The change amount DGAIRIN of the air amount in the throttle valve downstream portion 2a of the intake pipe 2 is given by the following equation (1). In equation (1), Vin is the volume of the downstream portion 2a of the throttle valve, TAK is the intake air temperature TA converted to absolute temperature, R is the gas constant, DPBA is the amount of change in the intake pressure PBA (PBA (k) -PBA (k- 1)). “K” is a discretization time discretized in the TDC period. (K) indicating the current value is usually omitted.
DGAIRIN = Vin × DPBA / (R × TAK) (1)

Therefore, the difference between the throttle valve passing air flow rate GAIRTH [g / TDC], which is the flow rate of fresh air passing through the throttle valve 3 (intake air flow rate), and the cylinder intake air amount GAIRCYLN [g / TDC] is expressed by the following formula (2 ), The amount of change is equal to the amount of change DGAIRIN.
DGAIRIN = GAIRTH (k) −GAIRCYLN (k−1) (2)

On the other hand, the cylinder intake air amount GAIRCYLN is given by the following equation (3). In equation (3), Vcyl is the cylinder volume, and ηv is the volumetric efficiency.
GAIRCYLN = Vcyl × ηv × PBA / (R × TAK) (3)

When Expression (3) is used, the intake pressure change amount DPBA is given by Expression (4) below. By applying the relationship between DPBA given by equation (4) and equation (2) to equation (1), the following equation (5) is obtained.

Therefore, if the delay coefficient CDLY is defined by the following equation (6), the equation (5) is expressed by the following equation (5a), and the cylinder intake air amount GAIRCYLN is a first-order lag model with the throttle valve passage air flow rate GARITH as an input. It can be calculated using an equation.
CDLY = Vcyl × ηv / Vin (6)
GAIRCYLN (k) = (1−CDLY) × GAIRCYLN (k−1)
+ CDLY × GAIRTH (k) (5a)

  In order to calculate the delay coefficient CDLY by the equation (6), it is necessary to calculate the volume efficiency ηv. The volumetric efficiency ηv varies depending on the engine operating state (engine speed NE, intake pressure PBA), intake valve operating state (lift amount LIFT, valve operating phase VTC), exhaust gas recirculation rate, etc. When the calculation is performed by the method disclosed in Patent Document 1, there is a problem that the engine characteristics cannot be changed over time or the arithmetic processing is complicated.

Accordingly, the calculation process is simplified by calculating the volume efficiency ηv used for calculating the cylinder intake air amount GAIRCYLN (k) using the following equation (7).
ηv = GAIRCYLN (k−1) / GAIRSTD (k) (7)
GAIRSTD (k) in equation (7) is the theoretical cylinder intake air amount calculated by equation (8) below.
GAIRSTD (k) = PBA (k) × Vcyl / (R × TAK) (8)

  By using the equation (7), it is possible to calculate the volumetric efficiency ηv without using a map or a table, and since it is constantly updated, an optimum value can be obtained without being affected by changes in engine characteristics over time. .

In the above calculation method, when the intake valve lift amount LIFT is substantially constant, the cylinder intake air amount can be calculated with high accuracy. However, since the volumetric efficiency ηv changes depending on the lift amount LIFT, In a transient operation state in which the amount LIFT changes, the exact cylinder intake air amount cannot be calculated using equation (5a). That is, since the volume efficiency ηv changes and the delay coefficient CDLYa changes, it is necessary to use the following formula (9).
GAIRCYL (k) =
(RCDLY-CDLYa (k)) × GAIRCYLP (k)
+ CDLYa (k) × HGAIRTH (k) (9)

  According to Equation (9), the predicted cylinder intake air amount GAIRCYL (k) is calculated for the reason described later. GAIRCYLP (k) in equation (9) corresponds to the previous value of the predicted cylinder intake air amount GAIRCYL, but is recalculated using the current lift amount LIFT (k) as will be described later. Hereinafter, it is referred to as “recalculated previous cylinder intake air amount”. HGAIRTH (k) is the estimated throttle valve passing air amount, and is calculated according to the intake pressure PBA, the intake air temperature TA, and the like by the processing of FIG.

Further, the delay coefficient CDLYa in the equation (9) is given by the following equation (10), and ηva (k) in the equation (10) is the predicted volume efficiency given by the following equation (11). RCDLY in equation (9) is a delay coefficient ratio given by equation (12) below. KLIFT (k) in Expression (11) is a lift amount correction coefficient calculated according to the lift amount LIFT, and a calculation method will be described later. CDLYaP (k) in equation (12) corresponds to the previous value of the delay coefficient CDLYa (k), but is recalculated using the current lift amount LIFT (k) as will be described later. Hereinafter, it is referred to as “recalculation previous delay coefficient”.
CDLYa (k) = Vcyl × ηva (k) / Vin (10)
ηva (k) = KLIFT (k) × GAIRCYLP (k) / GAIRSTD (k) (11)
RCDLY = CDLYa (k) / CDLYaP (k) (12)

  4 (a) to 4 (d) show the transition of the lift amount LIFT in a transient operation state where the lift amount LIFT increases, the lift curve (# 1 to # 4 are cylinder numbers), and the calculation timing of the cylinder intake air amount, respectively. (Hereinafter simply referred to as “calculation time”) and a time chart showing the stroke of the # 1 cylinder. As shown in this figure, the time tINACT at which air is actually sucked into the cylinder (hereinafter referred to as “intake timing”) is after the calculation time tFICAL, and in the transient operation state in which the lift amount LIFT changes, In consideration of this timing difference, it is desirable to calculate a predicted value of the cylinder intake air amount at the intake timing tINACT at the calculation timing tFICAL. Therefore, in the present embodiment, this predicted value is indicated by the predicted cylinder intake air amount GAIRCYL (k), and the calculation method of the predicted cylinder intake air amount GAIRCYL (k) will be described in detail below.

The lift amount correction coefficient KLIFT (k) is calculated by the following equation (13).
KLIFT (k) = ηvaT (k) / ηvaTP (k) (13)
ΗvaT (k) in Expression (13) is a volumetric efficiency at the inhalation timing tINACT (hereinafter referred to as “searched volumetric efficiency”) calculated by searching the ηv table shown in FIG. The retrieval volume efficiency ηvaT (k) is calculated by searching the ηv table according to the predicted lift amount HLIFT (k) that is the lift amount at the inhalation timing tINACT.

  Calculation of the predicted lift amount HLIFT (k) is performed as follows. First, the lift amount (hereinafter referred to as the “next lift amount”) LIFTN (k) at the time point after one stroke period from the calculation time tFICAL depends on the previous value LIFT (k−1) and current value LIFT (k) of the detected lift amount. Next, the predicted lift amount HLIFT (k) is calculated according to the lift amount LIFT (k) and the next lift amount LIFTN (k).

  ΗvaTP (k) in equation (13) corresponds to the previous value of the retrieval volume efficiency ηvaT (k), but is recalculated using the current lift amount LIFT (k), and the inhalation time This is the retrieval volume efficiency (hereinafter referred to as “previous retrieval volume efficiency”) at tINAACTP (hereinafter referred to as “previous inhalation timing”) one time period before tINACT. The previous retrieval volume efficiency ηvaTP (k) is calculated based on the lift value at the previous suction timing tINACTP (hereinafter referred to as “recalculated previous lift amount”) based on the previous value LIFT (k−1) and current value LIFT (k) of the detected lift amount. Is calculated by searching the ηv table (FIG. 6) according to the recalculated previous lift amount HLIFFP (k).

FIG. 5 is a flowchart of a process for calculating the predicted cylinder intake air amount GAIRCYL. This process is executed in synchronization with the generation of the TDC pulse.
In step S11, the HLIFTP calculation process shown in FIG. 7 is executed to calculate the recalculated previous lift amount HLIFTP (k).

In step S12, the ηv table shown in FIG. 6 is searched according to the recalculated previous lift amount HLIFFP (k), and the recalculated previous search volume efficiency ηvaTP (k) is calculated.
In step S13, a recalculation previous lift amount correction coefficient KLIFTP (k) is calculated by the following equation (22). In formula (22), ηvaTP (k−1) is the previous value of the recalculated previous search volume efficiency.
KLIFTP (k) = ηvaTP (k) / ηvaTP (k−1) (22)

In step S14, the recalculated previous lift amount correction coefficient KLIFTP (k) is applied to the following equation (23) to calculate the recalculated previous volumetric efficiency ηvaP (k).
ηvaP (k) = KLIFTP (k) × GAIRCYLP (k−1) / GAIRSTD (k−1)
(23)

In step S15, a recalculation previous delay coefficient CDLYaP (k) is calculated by the following equation (24).
CDLYaP (k) = Vcyl × ηvaP (k) / Vin (24)

In step S16, the recalculation previous delay coefficient ratio RCDLYP (k) is calculated by the following equation (25).
RCDLYP (k) = CDLYaP (k) / CDLYaP (k-1) (25)

  In step S17, the HGAIRTHP calculation process shown in FIG. 7 is executed to calculate a recalculated estimated throttle valve passing air amount HGAIRTHP (k) corresponding to the previous value of the estimated throttle valve passing air amount.

  In step S41 of FIG. 7, the KPA map shown in FIG. 8A is retrieved according to the recalculated previous lift amount HLIFFP (k) and the atmospheric pressure PA, and the atmospheric pressure correction coefficient KPA (HLIFFTP) is calculated. The atmospheric pressure correction coefficient KPA takes into account that in the region where the atmospheric pressure PA is relatively low and the lift amount LIFT is close to the minimum lift amount LFTMIN, the contribution of the lift amount LIFT and the atmospheric pressure PA to the throttle valve passing air amount increases. The correction coefficient calculated as described above is applied to the calculation in the following step S42. In FIG. 8A, PA1 to PA3 are predetermined atmospheric pressures and satisfy the relationship PA1 <PA2 <PA3. LIFT1 is a predetermined lift amount slightly larger than the minimum lift amount LFTMIN.

In step S42, the intake air temperature TA (k-1), the intake pressure PBA (k-1), the throttle valve opening TH (k-1), the atmospheric pressure PA (k-1), and the atmospheric pressure correction coefficient KPA (HLIFFP ) Is applied to the following equation (26) to calculate the recalculated estimated intake air flow rate HGAIRP (k). In equation (26), KC is a conversion constant for setting the unit of flow rate to [g / sec], KTH (TH) is an opening area flow rate function calculated according to the throttle valve opening TH, and Ψ ( RP) is a pressure specific flow rate function calculated according to the ratio RP (= PBA / PA) between the atmospheric pressure PA that is the upstream pressure of the throttle valve 3 and the intake pressure PBA that is the downstream pressure, and R Is the gas constant. The value of the opening area flow rate function KTH (TH) is calculated using the KTH table shown in FIG. In the equation (26), RP (k-1) is PBA (k-1) / PA (k-1).

Further, the pressure specific flow rate function Ψ is given by the following equation (27). “Κ” in the equation (27) is a specific heat ratio of air. However, when the air flow velocity exceeds the sound velocity, the pressure ratio flow function Ψ takes a maximum value regardless of the pressure ratio. Therefore, in the actual calculation process, the value of the pressure ratio flow function Ψ (RP) is also set in advance. RP) table (FIG. 8C) is used for calculation.

In step S43, the recalculated estimated intake air flow rate HGAIRP (k) [g / sec] and the engine speed NE (k-1) are applied to the following equation (28), and the recalculated estimated corresponding to the generation period of the TDC pulse. The throttle valve passing air amount HGAIRTHP (k) [g / TDC] is calculated. KCV in Expression (28) is a predetermined conversion coefficient.
HGAIRTHP (k) = HGAIRP (k) × KCV / NE (k-1) (28)

Returning to FIG. 5, in step S18, the recalculated previous cylinder intake air amount GAIRCYLP (k) is calculated by the following equation (29).
GAIRCYLP (k) =
(RCDLYP (k) -CDLYaP (k)) × GAIRCYLP (k-1)
+ CDLYaP (k) × HGAIRTHP (k) (29)

In step S19, the next lift amount LIFTN (k) is calculated by the following equation (31).
LIFN (k) = LIFT (k) + (LIFT (k) −LIFT (k−1)) (31)
Equation (31) is an equation for calculating the next lift amount LIFTN by the simplest method, and the next lift amount LIFTN is calculated by using a more complicated method such as an auto-regression model or a neural network model. You may make it do.

  In step S20, the HLIFT calculation process shown in FIG. 12 is executed to calculate the predicted lift amount HLIFT (k). In step S21, the ηv table shown in FIG. 6 is searched according to the predicted lift amount HLIFT (k), and the search volume efficiency ηvaT (k) is calculated. In step S22, the lift amount correction coefficient KLIFT (k) is calculated by the equation (13).

  In step S23, the predicted volume efficiency ηva (k) is calculated from the equation (11), and in step S24, the delay coefficient CDLYa (k) is calculated from the equation (10). In step S25, the delay coefficient ratio RCDLY (k) is calculated by the equation (12).

  In step S26, the HGAIRTH calculation process shown in FIG. 14 is executed to calculate the estimated throttle valve passing air amount HGAIRTH (k). In step S27, the predicted cylinder intake air amount GAIRCYL (k) is calculated from the above equation (9). To do.

  FIG. 9 is a flowchart of the HLIFTP calculation process executed in step S11 of FIG. 5, and FIG. 10 is a diagram for explaining the process of FIG. First, the outline of the process shown in FIG. 9 will be described.

  1) Based on the previous value LIFT (k-1) and the current value LIFTN (k) of the lift amount, as shown in FIG. 10A, a straight line L11 indicating a change with time of the lift amount LIFT is determined, and the straight line L11 A calculation parameter CLIFT (i) (i = 0 to IMAX) indicating the lift amount at the upper operating point is calculated. In the present embodiment, since the calculation parameter CLIFT (i) is calculated every 10 degrees of crank angle, i = 0, 1, 2, 3,. . . Are crank angles 0 degrees, 10 degrees, 20 degrees, 30 degrees,. . . Corresponding to

  2) One of the INLFT tables shown in FIG. 11A is selected according to the index parameter i, the selected INLFT table is searched according to the calculation parameter CLIFT (i), and the instantaneous lift curve value INLFT (i) Is calculated. FIG. 11A shows only a typical INLFT table (corresponding to i = 0, 4, 9). FIG. 10B shows the transition of the instantaneous lift curve value INLFT calculated in this way. In a transient state where the lift amount LIFT is increasing, the lift curve does not have the shape shown in FIG. 2 but a deformed shape as shown in FIG. 10B.

  3) A time area parameter TALFT indicating the area of a region (shown with hatching) surrounded by the lift curve and crank angle axis shown in FIG. 10B is calculated. In the present embodiment, the time area parameter TALFT is calculated as the sum of the rectangular areas of the crank angle angular width DCA (= 10 deg).

  4) By searching the HLIFT table shown in FIG. 11B according to the time area parameter TALFT, the recalculated previous lift amount HLIFTP (k) is calculated.

  By this calculation, the recalculated previous lift amount HLIFFP (k) can be calculated as a parameter indicating the average lift amount in the transient state in which the lift amount changes.

Hereinafter, the process of FIG. 9 will be described step by step.
In step S31, the previous value LIFT (k-1) and current value LIFT (k) of the lift amount are set in the calculation parameters CLIFT (0) and CLIFT (I180), respectively. I180 is a value of the index parameter i corresponding to a crank angle of 180 degrees, and is “18” in the present embodiment.

In step S32, the calculation parameter CLIFT (i) is calculated by the following equation (41) (i = 0 to IMAX). IMAX is the maximum value of the index parameter i, and is set to “27” in the present embodiment. This is because the valve opening timing IVO and the valve closing timing IVC of the intake valve when the lift amount LIFT is the maximum value LIFTMAX are the crank angles “0 degrees” and “270 degrees”, respectively (however, the valve operating phase VTC is (In the case of 0 degree (most retarded phase)).
CLIFT (i) = (CLIFT (I180) −CLIFT (0)) × i / I180
+ CLIFT (0) (41)

  In step S33, the instantaneous lift curve value INLFT (i) is calculated by selecting the INLFT table according to the index parameter i and searching the INLFT table according to the calculation parameter CLIFT (i) (i = 0 to IMAX). ).

In step S34, the time area parameter TALFT is calculated by the following equation (42). The DCA in the equation (42) is 180 [deg] / I180, and is 10 [deg] in the present embodiment (see FIG. 10B).

  In step S35, the HLIFT table shown in FIG. 11B is searched according to the time area parameter TALFT to calculate the recalculated previous lift amount HLIFTP (k).

  FIG. 12 is a flowchart of the HLIFT calculation process executed in step S20 of FIG. In this process, steps S31 and S35 of the HLIFTP calculation process shown in FIG. 9 are changed to steps S31a and S35a, respectively.

  In step S31a, calculation parameters CLIFT (0) and CLIFT (I180) are set to the lift amount LIFT (k) and the next lift amount LIFTN (k), respectively. As a result, the calculation parameter CLIFT (i) is calculated as a lift amount on a straight line passing through the detected lift amount LIFT (k) and the next lift amount LIFTN (k).

  In step S35a, the HLIFT table in FIG. 11B is searched according to the time area parameter TALFT calculated in step S34, and the predicted lift amount HLIFT (k) is calculated.

  FIG. 13 is a flowchart of the HGAIRTH calculation process executed in step S26 of FIG. The calculation method in this process is the same as the HGAIRTHP calculation process in FIG.

  In step S51, a KPA map shown in FIG. 8A is retrieved according to the predicted lift amount HLIFT (k) and the atmospheric pressure PA, and an atmospheric pressure correction coefficient KPA (HLIFT) is calculated.

In step S52, the intake air temperature TA, the intake pressure PBA, the throttle valve opening TH, the atmospheric pressure PA, and the atmospheric pressure correction coefficient KPA (HLIFT) are applied to the following equation (43) to calculate the estimated intake air flow rate HGAIR. .

In step S53, the estimated intake air flow rate HGAIRP [g / sec] and the engine speed NE are applied to the following equation (44) to calculate the estimated throttle valve passing air amount HGAIRTH [g / TDC].
HGAIRTH = HGAIR × KCV / NE (44)

  As described above, in this embodiment, the theoretical cylinder intake air amount GAIRSTD is calculated based on the intake pressure PBA and the intake air temperature TA, and the volumetric efficiency ηv ′ (= GAIRCYLP (k) / GAIRSTD is calculated using the theoretical cylinder intake air amount GAIRSTD. (k)) is calculated, and the predicted volume efficiency ηva is calculated by correcting the volume efficiency ηv ′ using the lift amount correction coefficient KLIFT set according to the intake valve lift amount LIFT. Further, a predicted cylinder intake air amount GAIRCYL is calculated using the estimated throttle valve passing air amount HGAIRTH and the predicted volume efficiency ηva. For calculating the predicted cylinder intake air amount GAIRCYL, the recalculated previous cylinder intake air amount GAIRCYLP, which is a past equivalent value of the predicted cylinder intake air amount, is applied, and the recalculated previous cylinder intake air amount GAIRCYLP is used as the theoretical cylinder intake air amount. Volume efficiency ηv ′ is calculated by dividing by GAIRSTD. Thereby, the number of maps and tables used for calculating the predicted cylinder intake air amount GAIRCYL can be reduced. In addition, since the predicted volume efficiency ηva is updated using the detection parameter, it is possible to always obtain an accurate predicted cylinder intake air amount GAIRCYL without being affected by changes in engine characteristics over time. Further, since the volumetric efficiency changes when the intake valve lift amount LIFT is changed, by using the predicted volumetric efficiency ηva corrected using the lift amount correction coefficient KLIFT, the change in the volumetric efficiency due to the change in the lift amount LIFT is caused. It is reflected and an accurate predicted cylinder intake air amount GAIRCYL can be calculated even in a transient operation state.

  Further, the lift amount correction coefficient KLIFT is calculated using the predicted lift amount HLIFT, which is the predicted value of the intake valve lift amount, and the predicted volume efficiency ηva is calculated using the lift amount correction coefficient KLIFT. Efficiency calculation accuracy can be increased.

  Further, a recalculated previous cylinder intake air amount GAIRCYLP which is a past equivalent value of the predicted cylinder intake air amount is calculated according to the detected lift amount LIFT, and the predicted cylinder intake air amount GAIRCYL is calculated using the recalculated previous cylinder intake air amount GAIRCYLP. Therefore, an error caused by using the predicted lift amount HLIFT can be reduced as compared with the case where the previous value GAIRCYL (k−1) of the predicted cylinder intake air amount is used.

  In this embodiment, the intake pressure sensor 8 and the intake temperature sensor 9 correspond to intake pressure detection means and intake temperature detection means, respectively, and the CS angle sensor 15 corresponds to lift amount detection means. The ECU 5 constitutes intake air flow rate acquisition means, theoretical cylinder intake air amount calculation means, volumetric efficiency calculation means, volumetric efficiency correction means, and predicted cylinder intake air amount calculation means. Specifically, step S26 in FIG. 5 corresponds to intake air flow rate acquisition means, and steps S11 to S23 correspond to theoretical cylinder intake air amount calculation means, volumetric efficiency calculation means, and volumetric efficiency correction means, and step S24. , S25, S27 correspond to the predicted cylinder intake air amount calculation means.

  The present invention is not limited to the embodiment described above, and various modifications can be made. For example, in the above-described embodiment, the recalculated previous cylinder intake air amount GAIRCYLP is used as the past equivalent value of the predicted cylinder intake air amount, but the previous value GAIRCYL (k−1) of the predicted cylinder intake air amount is used. Also good.

  In the embodiment described above, the search volume efficiency ηvaT (ηvaTP) is calculated using the ηv table shown in FIG. 6, but the relationship between the lift amount LIFT and the engine speed NE and the volume efficiency ηv is set. The retrieved volume efficiency ηvaT (ηvaTP) may be calculated in accordance with the predicted lift amount HLIFT (HLIFTP) and the engine speed NE using the ηv map thus obtained.

  The predicted lift amount HLIFT (k) may be calculated as an average value of the detected lift amount LIFT (k) and the next lift amount LIFTN (k) ((LIFT (k) + LIFTN (k)) / 2) Similarly, the recalculated previous lift amount HLIFFP (k) may be calculated as an average value of the previous value LIFT (k−1) and the current value LIFT (k) of the detected lift amount.

  In the above-described embodiment, the estimated cylinder intake air amount GAIRCYL is calculated using the estimated intake air amount flow rate HGAIR estimated according to the engine operating parameter. However, the intake air detected by the intake air flow rate sensor 14 is calculated. A flow rate GAIR may be used.

  In the above-described embodiment, the present invention is applied to an engine having a valve mechanism that can continuously change the lift amount of the intake valve (the peak value of the lift curve). The present invention can also be applied to an engine having a valve mechanism that can be changed to (for example, two stages).

  The present invention can also be applied to the calculation of the cylinder intake air amount of a marine vessel propulsion engine such as an outboard motor having a vertical crankshaft.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 1a Cylinder 2 Intake pipe 3 Throttle valve 5 Electronic control unit (Intake air flow rate acquisition means, theoretical cylinder intake air amount calculation means, volume efficiency calculation means, volume efficiency correction means, predicted cylinder intake air amount calculation means)
8 Intake pressure sensor (Intake pressure detection means)
9 Intake air temperature sensor (intake air temperature detection means)
41 First valve operating characteristic variable mechanism (valve mechanism)

Claims (3)

In a cylinder intake air amount calculation device for an internal combustion engine that calculates a cylinder intake air amount that is a fresh air amount sucked into a cylinder of the internal combustion engine having a valve operating mechanism capable of changing a lift amount of the intake valve,
An intake air flow rate acquisition means for acquiring an intake air flow rate which is a flow rate of fresh air passing through the intake pipe of the engine;
An intake pressure detecting means for detecting an intake pressure of the engine;
An intake air temperature detecting means for detecting an intake air temperature that is a temperature of air sucked into the engine;
A theoretical cylinder intake air amount calculating means for calculating a theoretical cylinder intake air amount based on the intake pressure and the intake temperature;
Volumetric efficiency calculating means for calculating the volumetric efficiency of the engine using the theoretical cylinder intake air amount;
Volumetric efficiency correction means for correcting the volumetric efficiency according to the lift amount of the intake valve and calculating a corrected volumetric efficiency;
Predicted cylinder intake air amount calculating means for calculating a predicted cylinder intake air amount that is a predicted value of the cylinder intake air amount using the intake air flow rate and the corrected volumetric efficiency;
The predicted cylinder intake air amount calculating means calculates the predicted cylinder intake air amount using a past equivalent value of the predicted cylinder intake air amount;
The volumetric efficiency calculating means calculates the volumetric efficiency by dividing the past equivalent value of the predicted cylinder intake air amount by the theoretical cylinder intake air amount.   2. The cylinder intake air amount calculation device for an internal combustion engine according to claim 1, wherein the volumetric efficiency correction unit calculates the corrected volumetric efficiency using a predicted value of the lift amount. A lift amount detecting means for detecting a lift amount of the intake valve;
3. The cylinder intake air amount calculation device for an internal combustion engine according to claim 1, wherein the predicted cylinder intake air amount calculation means calculates the past equivalent value using a detected lift amount.

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