JP2006105100A - Cylinder suction air volume measuring device and cylinder suction air volume measuring method of engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily measure the cylinder suction air volume considering the influence of intake pulsation. <P>SOLUTION: A correction corresponding to a variation quantity caused by the intake pulsation, is applied to the basic suction air volume QcylO determined on the basis of intake pressure Pm and cylinder internal pressure Pcyl. For this correction, a pressure correction factor PRSATE (=(Pm+K1×ΔPmivc)/Pm:0≤K1≤1) and a temperature correction factor TRATE (=ä(Tm+K1×ΔTmivc)/Tm}<SP>-1/(2-K2)</SP>:0≤K2≤1), are calculated as a factor corresponding to a state of a suction air flow. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a cylinder intake air amount measuring apparatus and a cylinder intake air amount measuring method for an engine, and more specifically, when the cylinder intake air amount is controlled by controlling the valve timing of an intake valve, the actual cylinder intake air amount is determined. The present invention relates to a technique for simple measurement.

  Conventionally, a gasoline engine is provided with a throttle valve for controlling the amount of intake air, and the amount of air passing through the throttle valve is measured by an air flow meter installed upstream, and the amount of air passing through the throttle valve is determined as a load. Generally used as an indicator.

As an index of load, instead of the amount of air passing through the throttle valve, the amount of air flowing into the cylinder (hereinafter referred to as “cylinder intake air amount”) is adopted, and this is the direct object of measurement. Are known. That is, the amount of air flowing into the intake manifold from the output of the air flow meter is calculated, and the balance between the amount of air flowing into the manifold section and the amount of cylinder intake air flowing into the cylinder from the intake manifold is calculated. The cylinder intake air amount is calculated while calculating the amount (Patent Document 1).
JP 2001-050091 A

  2. Description of the Related Art In recent years, it has been known to control an intake air amount (that is, a cylinder intake air amount) by variably controlling an operation characteristic of an intake valve in place of control by a throttle valve. Even with this, there is a demand to measure the actual cylinder intake air amount and use it as an index of load. According to the cylinder intake air amount, unlike the throttle valve passing air amount, a load index is provided for each cylinder and for each intake stroke. Therefore, the target torque is realized for each cycle, and the engine during transient operation is realized. It becomes possible to refine the output control. However, on the other hand, since it is strongly influenced by the intake pulsation, it is desired to develop a simple technique for measuring the cylinder intake air amount in consideration of this influence.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique for easily measuring the cylinder intake air amount in consideration of the influence of intake pulsation.

  The present invention provides an apparatus and method for measuring a cylinder intake air amount, which is an amount of air taken into a cylinder of an engine. In the present invention, the basic intake air amount is calculated as the cylinder intake air amount determined based on the intake pressure and the in-cylinder pressure, and the cylinder caused by air column vibration in the intake passage is calculated with respect to the calculated basic intake air amount. The actual cylinder intake air amount is calculated by performing correction according to the variation of the intake air amount. With regard to this correction, a first region where the flow of intake air toward the cylinder choke and a second region other than the first region are set, and the correction characteristics between the first and second regions are set. Make it different. In the first region, the correction amount of the cylinder intake air amount corresponding to the fluctuation amount is substantially zero, while in the second region, it is proportional to the actual intake pressure considering the air column vibration amount, In addition, this correction is preferably performed based on a characteristic proportional to the reciprocal of the actual intake air temperature taking into account the air column vibration.

  According to the present invention, the cylinder intake air amount calculation method (that is, the correction method) is different between the first region where the flow of intake air chokes and the second region other than the first region. The amount can be accurately corrected for each region. In particular, in the latter second region, this correction is proportional to the actual intake pressure that takes into account the air column vibration in the intake passage, and is also proportional to the reciprocal of the actual intake air temperature that takes into account this air column vibration. By providing such a characteristic, it is possible to easily calculate an accurate cylinder intake air amount in consideration of the influence of intake pulsation.

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

  FIG. 1 shows a configuration of a spark ignition engine (hereinafter simply referred to as “engine”) 1 according to an embodiment of the present invention.

  An electronically controlled throttle valve 102 is installed in the intake passage 101 of the engine 1. Although it is possible to control the amount of air introduced into the intake passage 101 by the throttle valve 102, in this embodiment, the control of the valve timing of the intake valve 104, which will be described later, is mainly controlled. Therefore, the throttle valve 102 is adopted to control the intake pressure Pm, which is a precondition for the control based on the valve timing. Further, an injector 103 for supplying fuel is installed in the intake passage 101. The injector 103 injects an amount of fuel necessary to achieve a predetermined equivalence ratio under a controlled intake air amount. A poppet type intake valve 104 is installed in the port portion 101a of the intake passage. The intake valve 104 is driven by a valve operating device (hereinafter referred to as “intake valve operating device”) 105 disposed above the intake valve 104. During the open period of the intake valve 104, intake air and fuel mixture are in-cylinder. To be introduced. In the present embodiment, the intake valve operating device 105 continuously changes the operating angle of the intake valve 104 (hereinafter referred to as “intake operating angle”) and the lift amount, and the center phase of the intake operating angle (hereinafter referred to as “operation center”). "Corner") can be changed continuously.

  In the engine body, a spark plug 106 is installed on the cylinder head H so as to face the substantially upper center of the combustion chamber. The spark plug 106 ignites the air-fuel mixture introduced into the cylinder.

  After combustion, the generated exhaust gas is sent out to the exhaust passage 107. A poppet type exhaust valve 108 is installed in the port portion 107a of the exhaust passage. The exhaust valve 108 is driven by another valve gear 109 disposed above the exhaust valve 108, and exhaust gas is sent out while the exhaust valve 108 is open. In the present embodiment, unlike the intake valve 104, the operating angle, lift amount, and central phase of the operating angle of the exhaust valve 108 are constant, but those having the same configuration as the intake valve device 105 or others It is also possible to adopt a known variable valve device so that the operating angle can be changed.

  The operations of the intake valve operating device 105, the throttle valve 102, and the like are controlled by an engine controller (hereinafter referred to as “ECU”) 201 configured as an electronic control unit. The ECU 201 has a detection signal from the accelerator sensor 211 that detects the amount of depression of the accelerator pedal (indicating the accelerator opening APO) and a detection signal from the crank angle sensor 212 that detects the rotational position of the crankshaft (based on this) Is calculated, and the detection signal of the intake pressure sensor 213 for detecting the pressure (hereinafter referred to as “intake pressure”) Pm in the intake passage 101 (herein, the surge tank), intake air A detection signal from the intake temperature sensor 214 that detects the temperature Tm in the passage 101, a detection signal from the exhaust pressure sensor 215 that detects the pressure in the exhaust passage (hereinafter referred to as “exhaust pressure”) Pe, and the like are input. The ECU 201 controls the intake operation angle and the operation center angle by the intake valve operating device 105 and the throttle opening by the throttle valve 102 based on various input detection signals. In the present embodiment, the ECU 201 has a function as a cylinder intake air amount measuring device, and when controlling the throttle opening, the ECU 201 determines the amount of air actually taken into the cylinder as the cylinder intake air amount Qcyl. Calculate as

  FIG. 2 shows the configuration of the intake valve operating device 105 according to the present embodiment.

  The intake valve operating device 105 includes an operating angle changing mechanism A and a center angle changing mechanism B.

  A drive shaft 151 is installed above the intake valve 104 so as to extend in the cylinder row direction. A swing cam 152 is attached to the drive shaft 151 so as to be relatively rotatable. The swing cam 152 is in contact with the lifter 141 of the intake valve, and drives the intake valve 104 up and down via the lifter 141. The operating angle changing mechanism A changes the intake operating angle by changing the attitude of a link, which will be described later, connecting the drive shaft 151 and the swing cam 152. On the other hand, the center angle changing mechanism B changes the operation center angle by changing the phase of the drive shaft 151 with respect to a crankshaft (not shown).

  Here, the operating principle of the former operating angle changing mechanism A will be described with reference to FIG.

  The operating angle changing mechanism A is arranged in parallel with the drive shaft 151, a circular eccentric drive cam 153 fixed to the drive shaft 151, a ring-shaped link 154 that is fitted on the eccentric drive cam 153 so as to be relatively rotatable. A control shaft 155, a circular eccentric control cam 156 fixed to the control shaft 155, a rocker arm 157 externally fitted to the eccentric control cam 156 so as to be relatively rotatable, and connected to the ring-shaped link 154 at one end; A rod-shaped link 158 that connects the rocker arm 157 to the swing cam 152 is configured. The control shaft 155 rotates when the electromagnetic actuator 161 drives the gear train.

  The operation of the operating angle changing mechanism A is as follows. When the drive shaft 151 rotates in conjunction with the crankshaft, the rocker arm 157 swings around the axis of the eccentric control cam 156 in conjunction with the reciprocating motion of the ring-shaped link 154 and swings by the rod-shaped link 158. The cam 152 is driven. Further, by rotating the control shaft 155 by the electromagnetic actuator 161, the shaft center position of the eccentric control cam 156 changes, the rotation center of the rocker arm 157 is displaced, and the intake operation angle (and valve lift) is continuously increased. Change. For this reason, by operating the control shaft 155 by the electromagnetic actuator 161, the intake operation angle can be continuously changed.

  The center angle changing mechanism B may employ any known variable valve operating device that can change the phase of the drive shaft 151 with respect to the cam sprocket. In this embodiment, an intermediate gear is interposed between the cam sprocket and the drive shaft 151, a helical gear train is formed between them, and the relative phase of the drive shaft 151 is changed by moving the intermediate gear back and forth. The thing is adopted.

  Hereinafter, the configuration of the ECU 201 according to the present embodiment and the contents of the control (mainly measurement of the cylinder intake air amount Qcyl) performed by the ECU 201 will be described with reference to a block diagram.

  The control performed by the ECU 201 is simply as follows. The ECU 201 calculates and sets a target torque tTe that should be generated by the engine 1 based on operating conditions such as the accelerator operation amount APO and the engine speed Ne, and based on the target torque tTe, the intake valve operating device 105 and the throttle valve 102 is activated. That is, the ECU 201 calculates the target fresh air amount tQcyl as the cylinder intake air amount necessary to achieve the target torque tTe, sets the target intake air operating angle tθevent based on the target fresh air amount tQcyl, The valve device 105 is activated. Further, the ECU 201 measures the actual cylinder intake air amount Qcyl, and operates the throttle valve 102 to a position where the cylinder intake air amount Qcyl is decreased according to a deviation (= tQcyl−Qcyl) from the target fresh air amount tQcyl. To adjust the intake pressure Pm.

  Here, a method of measuring the cylinder intake air amount Qcyl according to the present embodiment will be described with reference to FIG.

  FIG. 11 shows the operation characteristics of the intake valve 104 and the exhaust valve 108 (indicated by valve lifts VLIFTi and VLIFTe), the cylinder pressure Pcyl obtained by the operation characteristics, and the cylinder intake air amount per unit crank angle (that is, the flow rate). ) Shows the relationship with DLTQ.

In order to measure the cylinder intake air amount Qcyl, the ECU 201 sends the reference cylinder intake air amount Q _D given by the following equations (1a) and (1b) under the in-cylinder pressure P0 and the actual cylinder intake air amount ( hereinafter, the simply relationship between "the cylinder intake air amount" of.) Qcyl (determined by experimentation or simulation for each condition.), is stored as the data created by dimensionless by the theoretical maximum intake air quantity Q _MAX . That is, the ratio between the reference cylinder intake air amount and the theoretical maximum intake air amount (corresponding to the “first ratio”) RQ1 = Q _D / Q _MAX and the ratio between the cylinder intake air amount and the theoretical maximum intake air amount (“ corresponding to the second ratio ".) RQ2 = table data unique relation between Qcyl / Q _MAX (e.g., block 213 (FIG. 4) to create and set as table data) shown in, storing ECU201 Stored in the device. In the present embodiment, as the in-cylinder pressure P0, the in-cylinder pressure Pctr obtained by the operation center angle IVCNT of the intake valve 104 is employed when the in-cylinder state change in the intake stroke is performed by adiabatic expansion. Yes. In this case, the in-cylinder pressure P0 (= Pctr) can be easily calculated by a thermodynamic theoretical formula. In the equations (1a) and (1b), the total opening area of the intake port 101a during the intake valve opening period is ΣA (calculated by integrating the opening area A for each unit crank angle) and the opening area A Is the θθ, and the specific heat ratio, gas constant, and temperature of the intake air are κ, Ra, and Tm. The theoretical maximum intake air amount Q _MAX is the cylinder intake air amount obtained when the stroke volume from the start to the end of intake is filled with the density (or pressure) and temperature of the intake air upstream of the intake valve. The cylinder volume at TDC is VTDC, and the cylinder volume at intake valve closing timing IVC is VIVC.

Q _D = ΣA × (Δθ / 6 · Ne) × (Pm / √ (Ra · Tm)) × X (1a)
X = √ {(2κ / (κ−1)) × ((P0 / Pm) ^{2 /} κ− (P0 / Pm) ⁽ κ ^{+ 1) /} κ)} (1b)
Q _MAX = (Pm / (Ra · Tm)) × (VIVC−VTDC) (2)
In the present embodiment, the pressure Pctr under adiabatic expansion is adopted as the in-cylinder pressure P0, so that the flow of intake air is theoretically choked in the entire operation region of the engine 1, and the intake air flows into the cylinder at the speed of sound. Therefore, the pressure ratio P0 / Pm in the equation (1b) always indicates the critical pressure ratio (= (2 / (κ + 1)) κ ^{/ (} κ− ¹⁾ = const). For this reason, this reference cylinder intake air amount Q _D is particularly referred to as “virtual sonic intake air amount”.

In the present embodiment, the calculation period PRDQMAX of the theoretical maximum intake air amount Q _MAX is determined from the point (hereinafter referred to as “effective top dead center”) TDCR at which the in-cylinder pressure Pcyl decreases to coincide with the intake pressure Pm. The point at which compression of the intake air is substantially started (hereinafter referred to as “effective closing timing”) is set to the period until IVCR. Therefore, the cylinder volume VTDCR at the effective top dead center TDCR is adopted as the cylinder volume VTDC of the equation (2), and the cylinder volume VIVCR at the effective closing timing IVCR is adopted as the cylinder volume VIVC. Note that the effective top dead center TDCR and the effective closing timing IVCR are, for control purposes, the offset amount TDCOFS from the overlap center angle OVLCNT, the set intake valve closing timing (hereinafter referred to as “set closing timing”) IVC. It shall be expressed by IVCOFS.

The ECU 201 calculates the virtual sonic intake air amount Q _D and the theoretical maximum intake air amount Q _MAX during actual operation, and searches the stored table using these to calculate the basic intake air amount Qcyl0. The basic intake air amount Qcyl0 is a static cylinder intake air amount given based on the intake pressure Pm and the in-cylinder pressure Pcyl. The ECU 201 corrects the basic intake air amount Qcyl0 according to the variation of the cylinder intake air amount caused by the intake pulsation, and calculates the final cylinder intake air amount Qcyl.

  In the present embodiment, correction for intake pulsation is performed as follows. The cylinder intake air amount Qcyl is given by the following equation (3), where the ratio of the intake pressure Pm and the in-cylinder pressure Pcyl is RP (= Pcyl / Pm).

Qcyl = ΣA × (Pm / √ (Ra · Tm)) × √ {(2κ / (κ−1)) × (RP ^{2 /} κ−RP ⁽ κ ^{+ 1) /} κ)} × Δt (3 )
In the present embodiment, the characteristics of the cylinder intake air amount Qcyl are defined separately for a first region in which the flow of intake air is choked and a second region other than this. In the first region, this characteristic is given by the following equation (4). This is apparent from the fact that the pressure ratio RP in the equation (3) is the critical pressure ratio (= const). In the equation (4), the cylinder intake air amount Qcyl is proportional to the intake pressure Pm, and the intake air temperature Tm It is proportional to the inverse of the square root. On the other hand, in the second region, this characteristic is given by the following equation (5), assuming that the state change in the cylinder proceeds quasi-statically. This is clear from the gas state equation when the cylinder is filled with the density and temperature in the intake passage 101 at the intake valve closing timing IVC. Equation (5) indicates that the cylinder intake air amount Qcyl is It is proportional to the actual intake pressure Pm (= Pmave + ΔPmivc) taking the intake pulsation into account, and is proportional to the inverse of the actual intake temperature Tm (= Tmave + ΔTmivc). In Equation (5), Pmave and Tmave indicate average or representative intake pressure and intake temperature, and ΔPmivc and ΔTmivc indicate the average intake pressure Pmave and average of the intake pressure Pmivc and the intake temperature Tmivc at the intake valve closing timing IVC. The amount of change with respect to the intake air temperature Tmave is shown. Further, regarding this embodiment, the symbol ∝ indicates that the value on the left side is proportional to the value on the right side.

a) DLTQ >> 0:
Qcyl∝Pm × (Tm) ^−1/2 (4)
b) DLTQ≈0:
Qcyl∝Pcylibc × (Tcylibc) ⁻¹
= Pmivc × (Tmivc) ⁻¹
= (Pmave + ΔPmivc) × (Tmave + ΔTmivc) ⁻¹ (5)
Assuming that the two characteristics thus obtained are included, one most probable characteristic over the entire operation region including the first and second regions is set by approximation. In the present embodiment, two coefficients that can be changed according to the flow state are defined as K1 and K2, and this one characteristic is defined by the following equation (6). The coefficient K1, K2 are each 0 or more and 1 have the following values, depending on the ratio of the cylinder intake air quantity Qcyl and the theoretical maximum intake air quantity Q _MAX, which is set to a greater value as when larger (Blocks B204a and B205a in FIG. 4).

Qcyl∝ (Pmave + K1 · ΔPmivc) × (Tmave + K1 · ΔTmivc) ^{−1 / (2-K2)} (6)
The actual cylinder intake air amount Qcyl taking into account the intake pulsation is based on the characteristics of the equation (6) and when taking the intake pulsation ΔPmivc and ΔTmivc into 0 and taking this intake pulsation into 0 Is given by the following equations (7) and (8).

Qcyl = Qcyl0 × Rpul (7)
Rpul = {(Pmave + K1 · ΔPmivc) / Pmave} × {(Tmave + K1 · ΔTmivc) / Tmave} ^{−1 / (2-K2)} (8)
A pressure correction term and a temperature correction term are extracted from the equation (8) and set as a pressure correction coefficient PRATE and a temperature correction coefficient RATE for the cylinder intake air amount, respectively.

PRATE = (Pmave + K1 · ΔPmivc) / Pmave (9)
TRATE = {(Tmave + K1 · ΔTmivc) / Tmave} ^{−1 / (2-K2)} (10)
The ECU 201 calculates the cylinder intake air amount Qcyl by multiplying the basic intake air amount Qcyl0 calculated by searching the table by the pressure correction coefficient PRATE and the temperature correction coefficient RATE.

  Below, the structure and control of ECU201 are demonstrated for every block. In the present embodiment, in the calculation related to the measurement of the cylinder intake air amount Qcyl, the average pressure and average temperature for each cycle in the intake passage 101 are employed as the intake pressure Pm and the intake temperature Tm.

  FIG. 4 shows a configuration of a part related to the measurement of the cylinder intake air amount Qcyl in the ECU 201.

Virtual sonic intake air quantity calculation section B201, based on the intake valve opening timing IVO and the intake valve closing timing IVC and the like, and calculates a virtual sonic intake air quantity Q _D by (1a) and (1b) type. The intake valve closing timing IVO and the like can be calculated from the intake operation angle and the operation center angle set at the time of the previous calculation execution. In the present embodiment, the calculation period PRDQD (FIG. 11) of the total opening area ΣA in the equation (1a) is set to a period from the effective top dead center TDCR to the set closing timing IVC of the intake valve 104. The effective top dead center TDCR is calculated as a time delayed from the overlap center angle OVLCNT by the top dead center offset amount TDCOFS. This offset amount TDCOFS is estimated by searching from the trend map shown in FIG. In the map of FIG. 5, the offset amount TDCOFS is set to a larger value as the engine speed Ne is higher and the opening area during the overlap period (for example, the first half opening area ΣAiv described later) is smaller. The overlap center angle OVLCNT is a crank angle at which the difference between the lift amount of the intake valve 104 and the lift amount of the exhaust valve 108 is the smallest. In this embodiment, the valve timing of the exhaust valve 108 is fixed. Therefore, it can be determined from the intake operation angle and the operation center angle.

The configuration of the virtual sonic intake air amount calculation unit B201 is shown in FIG. With respect to the cylinder intake air amount qsonic # per unit opening area obtained under the critical pressure ratio (= (2 / (κ + 1)) κ ^{/ (} κ− ¹⁾ ), a variable (= Pm / √ (Ra # · Tm)) and the total opening area ΣA during the intake valve opening period are multiplied, and this is converted into a time unit to calculate the virtual sonic intake air amount Q _D.

The theoretical maximum intake air amount calculation unit B202 calculates the theoretical maximum intake air amount Q _MAX by the equation (2) based on the set closing timing IVC of the intake valve 104 and the overlap center angle OVLCNT. As described above, the calculation period PRDQMAX of the theoretical maximum intake air amount Q _MAX is set to a period from the effective top dead center TDCR to the effective closing timing IVCR, but this effective closing timing IVCR is the set closing timing. The offset amount IVCOFS is calculated as a timing advanced from IVC by the offset amount IVCOFS of the intake valve closing timing, and this offset amount IVCOFS is estimated by searching from the trend map shown in FIG. In the map of FIG. 6, the offset amount IVCOFS is set to a larger value as the engine speed Ne is higher and the valve lift VLIFTi (for example, the maximum valve lift) of the intake valve 104 is smaller.

The configuration of the theoretical maximum intake air amount calculation unit B202 is shown in FIG. The cylinder volume VTDCR at the effective top dead center is calculated, the cylinder volume VIVCR at the effective closing timing is calculated, and the effective volume calculated as the difference between these (= VIVCR−VTDCR) is substituted into the equation (2), The maximum intake air amount Q _MAX is calculated.

Basic intake air quantity calculation section B203 calculates a basic intake air quantity Qcyl0 on the basis of the calculated virtual sonic intake air quantity Q _D and theoretical maximum intake air quantity Q _MAX. That is, the first ratio RQ1 is calculated, the table is searched based on the first ratio RQ1, the corresponding second ratio RQ2 is calculated, and the theoretical maximum intake air amount Q _{MAX is} added to the second ratio RQ2. To calculate the basic intake air amount Qcyl0. As described above, in this embodiment, since the cylinder intake air quantity Qsonic # per unit opening area takes a constant value under the critical pressure ratio, a virtual sonic intake air quantity Q _D is proportional to the total opening area ΣA .

The pressure correction coefficient calculation unit B204 calculates the pressure correction coefficient PRATE from the equation (9) based on the pulsation pressure change amount ΔPmivc calculated by the pulsation change amount calculation unit described later. Coefficient K1 is 0 or more and within a range of 1 or less, the ratio Qcyl / Q _MAX is increased, the state change of the cylinder increases quadratically in accordance with the approach the ones quasi-static.

The temperature correction coefficient calculation unit B205 calculates the temperature correction coefficient RATE by the equation (10) based on the pulsation temperature change amount ΔTmivc calculated by the pulsation change amount calculation unit described later. Coefficient K2 also coefficients k1 and likewise 0 or more and within a range of 1 or less, the ratio Qcyl / Q _MAX is the accordance increased quadratically larger.

  FIG. 10 shows the configuration of the pulsation change amount calculation unit. Based on the intake operating angle θevent (= IVC−IVO) and the engine speed Ne, a basic value ΔPmivc0 of the pulsation pressure change amount is calculated by searching from the map, and the actual intake pressure Pm (= Pmave) is calculated with respect to the basic value ΔPmivc0. ) To calculate the pulsation pressure change amount ΔPmivc. Similarly, a basic value ΔTmivc0 of the pulsation temperature change amount is calculated by searching from the map based on the intake operating angle θevent and the engine speed Ne, and the actual intake temperature Tm (= Tmave) is calculated with respect to the basic value ΔTmivc0. Correction is performed to calculate a pulsation temperature change amount ΔTmivc. In the equations (11) and (12), the atmospheric pressure is Patm.

ΔPmivc = ΔPmivc0 × Pm / Patm (11)
ΔTmivc = ΔTmivc0 × Pm / Patm (12)
In FIG. 4, the ECU 201 calculates the cylinder intake air amount Qcyl by the following equation (13) based on the calculated basic intake air amount Qcyl0. In the equation (13), the amount of gas blown back from the cylinder into the intake passage 101 during the overlap period (ie, blown gas amount) is defined as Q _IFB . The blow-back gas amount Q _IFB is calculated by the following equations (14) and (15) based on the intake pressure Pm and the exhaust pressure Pe, with a coefficient K3. In the equation (14), the first half opening area ΣAiv from the intake valve opening timing IVO to the overlap center angle OVLCNT is adopted as the opening area ΣA of the intake port 104a. The coefficient K3 is set as one or more values proportional to the engine speed Ne (FIG. 7). As the exhaust pressure Pe and the exhaust temperature Te, the average pressure and average temperature for each cycle in the exhaust passage 107 are employed.

Qcyl = (Qcyl0−Q _IFB ) × PRATE × TRATE (13)
Q _IFB = ΣAiv × (Δθ / (6 · Ne)) × Pe / (√ (Ra · Te)) × V _IFB × K3 (14)
V _IFB = √ {(2κ / (κ−1)) × ((Pm / Pe) ^{2 /} κ− (Pm / Pe) ⁽ κ ^{+ 1) /} κ)} (15)
According to this embodiment, the following effects can be obtained.

  That is, in this embodiment, since the correction method of the cylinder intake air amount Qcyl is different between the first region where the flow of intake air chokes and the second region other than this, the correction of the cylinder intake air amount Qcyl is performed. Accurate and simple for each region, it is possible to easily calculate an accurate cylinder intake air amount Qcyl in consideration of the influence of intake pulsation.

  Further, by adopting coefficients K1 and K2 that can be changed according to the flow state, and by setting correction coefficients PRATE and RATE that can be generally adopted over the first and second regions by this coefficient, Regardless of the occurrence, correction can be performed by one equation, avoiding heavy use of maps and the like, and reducing the calculation load required for calculating the cylinder intake air amount Qcyl.

In addition, the virtual sonic intake air amount Q _D and the theoretical maximum intake air amount Q _MAX are defined, and an unambiguous relationship between them and the cylinder intake air amount Qcyl is set. Regardless, the cylinder intake air amount Qcyl can be calculated based on this relationship, and the calculation load can be reduced.

Further, the cylinder intake air amount Qcyl can be calculated more accurately by subtracting the blow back gas amount Q _IFB from the calculated cylinder intake air amount (that is, the basic intake air amount Qcyl0).

  In the above description, the measured cylinder intake air amount Qcyl is used for correcting the intake pressure Pm, but this can also be used for setting the fuel injection amount.

  In addition, the intake air amount may be controlled by controlling the valve timing over the entire operating range, but control by the valve timing is performed only during transient operation, and during steady operation, it may be performed by controlling the throttle opening. Good. In this case, an air flow meter is installed upstream of the throttle valve, and instead of the cylinder intake air amount, the throttle valve passing air amount is adopted as the intake air amount detected during the steady operation.

  The cylinder intake air amount measuring device according to the present invention can also be employed in a direct injection gasoline engine.

Configuration of engine according to one embodiment of the present invention Same as above Configuration of the operating angle changing mechanism of the intake valve operating device Configuration of cylinder intake air volume measurement unit Calculation map of top dead center offset TDCOFS Calculation map of intake valve closing timing IVCOFS Setting map for coefficient K3 Configuration of virtual sonic intake air amount calculation unit Configuration of theoretical maximum intake air amount calculation unit Configuration of pulsation change calculation unit Relationship between valve operating characteristics, cylinder pressure and cylinder intake air volume per unit crank angle

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Engine, 101 ... Intake passage, 102 ... Throttle valve, 103 ... Injector, 104 ... Intake valve, 105 ... Intake valve operating device, 106 ... Spark plug, 107 ... Exhaust passage, 108 ... Exhaust valve, 151 ... Drive shaft, 152 ... Swing cam, 153 ... Eccentric drive cam, 154 ... Ring-shaped link, 155 ... Control shaft, 156 ... Eccentric control cam, 157 ... Rocker arm, 158 ... Rod-shaped link, 161 ... Electromagnetic actuator, 162 ... Gear train, DESCRIPTION OF SYMBOLS 201 ... Engine controller, 211 ... Accelerator sensor, 212 ... Crank angle sensor, 213 ... Intake pressure sensor, 214 ... Intake temperature sensor, 215 ... Exhaust pressure sensor, A ... Operating angle change mechanism of intake valve operating device, B ... Intake movement Center angle change mechanism of the valve device.

Claims (9)

A device for measuring a cylinder intake air amount that is an amount of air sucked into a cylinder of an engine,
Basic intake air amount calculation means for calculating a basic intake air amount as a cylinder intake air amount determined based on the intake pressure and the in-cylinder pressure;
Cylinder intake air amount calculating means for calculating the actual cylinder intake air amount by correcting the calculated basic intake air amount in accordance with the variation of the cylinder intake air amount caused by air column vibration in the intake passage. And comprising
The cylinder intake air amount calculating means defines a first area where the flow of intake air flowing into the cylinder chokes and a second area other than the first area, and the first area and the second area The cylinder intake air amount measuring device for the engine which performs the correction according to the different characteristics in the region.   2. The cylinder intake air amount measurement device for an engine according to claim 1, wherein the cylinder intake air amount calculation means sets the correction amount of the cylinder intake air amount corresponding to the variation in the first region to be substantially zero. .   The cylinder intake air amount calculation means is proportional to the actual intake pressure taking into account the air column vibration in the second region, and proportional to the reciprocal of the actual intake air temperature taking into account the air column vibration. The cylinder intake air amount measuring device for an engine according to claim 1 or 2, wherein the correction is performed according to characteristics. The basic intake air amount calculating means sets the cylinder intake air amount obtained when the intake air is sucked as a sonic flow with an opening area corresponding to the operating characteristics of the intake valve as a virtual sonic intake air amount Q _D and from the start to the end of intake The cylinder intake air amount obtained when the stroke volume is filled with the intake air density and temperature upstream of the intake valve is defined as a theoretical maximum intake air amount Q _MAX , and the first ratio Q _D / An unambiguous relationship between Q _MAX and the second ratio Qcyl / Q _MAX is set, and when the engine is operating, the first ratio is calculated, and based on the calculated first ratio, The engine cylinder intake air amount measurement device according to claim 1, wherein the basic intake air amount is calculated.   5. The basic intake air amount calculation means calculates the virtual sonic intake air amount as a cylinder intake air amount from an effective top dead center where the in-cylinder pressure is reduced to an intake pressure to a set closing timing of the intake valve. The cylinder intake air amount measuring device for an engine according to 1.   The basic intake air amount calculation means calculates the theoretical maximum intake air amount from the effective top dead center at which the in-cylinder pressure is reduced to the intake pressure, and the intake valve effective at which the intake air compression is substantially started in the cylinder. 6. The cylinder intake air amount measuring device for an engine according to claim 4, wherein the cylinder intake air amount is calculated as a cylinder intake air amount until a closing timing.   Blowing gas for subtracting the amount of blowback gas blown back from the cylinder into the intake passage during the overlap period between the intake valve open period and the exhaust valve open period from the basic intake air quantity calculated by the basic intake air quantity calculation means The cylinder intake air amount measuring device for an engine according to any one of claims 1 to 6, further comprising a quantity subtracting means. The cylinder intake air amount calculation means represents typical intake pressure and intake temperature as Pm, Tm, and changes in intake pressure and intake temperature with respect to the representative pressure and representative temperatures Pm, Tm at the set closing timing of the intake valve. As ΔPmivc and ΔTmivc, the pressure correction coefficient PRATE and the temperature correction coefficient RATE are calculated by the following formulas (a-1) and (a-2) where the coefficients K1 and K2 are values of 0 or more and 1 or less, respectively. The cylinder intake air amount measurement device for an engine according to any one of claims 1 to 7, wherein an actual cylinder intake air amount Qcyl is calculated by the following equation (b), where the basic intake air amount is Qcyl0.
PRATE = (Pm + K1 · ΔPmivc) / Pm (a-1)
TRATE = {(Tm + K1 · ΔTmivc) / Tm} ^{-1 / (2-K2)} (a-2)
Qcyl = Qcyl0 × PRATE × TRATE (b) A method of measuring a cylinder intake air amount, which is an amount of air sucked into an engine cylinder,
The basic cylinder intake air amount, which is determined based on the intake pressure and the in-cylinder pressure, is corrected according to the variation in the cylinder intake air amount caused by air column vibration in the intake passage. While calculating the cylinder intake air volume,
Regarding the correction of the cylinder intake air amount,
A first region where the flow of the intake air toward the cylinder chokes and a second region other than the first region;
In the first region, the first characteristic proportional to the intake pressure and proportional to the inverse of the square root of the intake air temperature is set as the characteristic of the cylinder intake air amount, while in the second region, the cylinder intake air amount is set. A second characteristic that is proportional to the actual intake pressure that takes into account the air column vibration as a characteristic and that is proportional to the reciprocal of the actual intake temperature that takes the air column vibration into account,
One characteristic of the cylinder intake air amount including the first and second characteristics over the entire operating range of the engine is set by approximation as a third characteristic,
The correction characteristic is determined by using a ratio between the cylinder intake air amount obtained by the third characteristic and the cylinder intake air amount obtained by setting the air column vibration amount to 0 by the third characteristic. To measure the cylinder intake air amount of the engine.

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