JP4419375B2 - Control device for variable valve engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The invention of this application relates to an engine used in a vehicle or the like, and more particularly, to a control device for a variable valve engine that controls the fuel injection amount together with the opening / closing timing of the intake valve and the lift amount.
[0002]
[Prior art]
As an engine used in a vehicle or the like, a variable valve device that controls the opening / closing timing and lift amount of an intake valve according to an operating state is provided. By controlling the variable valve device together with engine fuel injection, a pumping loss is reduced. Some have been reduced.
[0003]
As a control device for such a variable valve engine, for example, a device described in Japanese Patent Application Laid-Open No. 2000-87766 has been devised.
[0004]
The variable valve engine described in this publication is of a so-called throttle-less type, and uses an electromagnetic actuator as a variable valve driving device that drives an intake valve, and controls the electromagnetic actuator together with the fuel injection device for each cylinder. The engine control device has a problem in which the ratio of the fuel and the intake air amount deviates from the optimum value due to a difference in timing between the fuel injection control and the intake air amount control in a situation where the operation state suddenly changes during acceleration operation or the like. Therefore, the intake air amount control by the electromagnetic actuator is performed based on the operation state data at the time when the fuel injection amount is determined. Therefore, in this control device, even when the operating state suddenly changes during acceleration operation or the like, the electromagnetic actuator (variable valve operating device) does not perform the intake air amount control that does not match the fuel injection amount, and the engine always operates. Can be maintained at the optimum air-fuel ratio.
[0005]
[Problems to be solved by the invention]
However, the control device for the variable valve engine performs control of the variable valve device based on the operating state data at the time of determining the fuel injection amount, in other words, the variable valve control from the time of determining the fuel injection amount. For example, during rapid acceleration, the responsiveness may be reduced. In addition, it is difficult to adopt the system under a system in which continuous control of the variable valve operating device according to changes in the operating state is not desired to be stopped.
[0006]
That is, for example, in an engine having a plurality of cylinders, when the opening / closing timing of the intake valve of each cylinder and the change of the flit amount are mechanically linked in the plurality of cylinders, the variable valve operation of one cylinder is stopped. The variable valve actuation of other cylinders is also affected, and the air-fuel ratio control and output control for each cylinder cannot be performed strictly.
[0007]
Therefore, the invention of this application is capable of always performing optimal air-fuel ratio control without unnecessarily stopping the variable valve control, thereby improving the operating performance and suppressing emission deterioration reliably. An object of the present invention is to provide an engine control device.
[0008]
[Means for Solving the Problems]
As means for solving the above-described problems, the invention of this application includes a first fuel injection amount calculating means for calculating a first fuel injection amount based on an intake air amount, and a cylinder for injecting the first fuel injection amount. And a second fuel injection amount calculation means for calculating a second fuel injection amount based on the intake air amount estimated in consideration of the valve lift curve of Said Calculating the second fuel injection amount after injecting the first fuel injection amount; Said The first fuel injection amount and Said Further difference with the second fuel injection amount To contribute to combustion of fuel by the first fuel injection amount I tried to spray.
[0009]
【The invention's effect】
As described above, the invention of this application estimates the intake air amount by determining the control history from opening to closing of the intake valve based on the data related to the control of the variable valve operating apparatus, Since the fuel injection amount control is performed so as to correspond to the intake air amount, the optimal air-fuel ratio control can always be performed without unnecessarily stopping the control on the variable valve operating apparatus side.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, each embodiment of the invention of this application will be described with reference to the drawings.
[0011]
FIG. 1 is an overall configuration diagram of a first embodiment showing a spark ignition type variable valve engine to which a control device according to the invention of this application is applied. This engine is an in-line four-cylinder engine having four cylinders (# 1 cylinder to # 4 cylinder) arranged in series.
[0012]
The combustion chamber 1 of the engine is defined by a cylinder head 2, a cylinder block 3, and a piston 4 that reciprocates in a cylinder 3a of the cylinder block 3. The cylinder head 2 is formed with an intake port 5 and an exhaust port 6 that open to the combustion chamber 1. The intake valve 7 that opens and closes the intake port 5 is driven by a variable valve device 8. The variable valve operating device 8 includes a first variable mechanism (VEL) that can change the operating angle and lift amount of the intake valve 7 and a second variable mechanism (VTC) that can change the lift center angle phase ( Details will be described later). An exhaust valve 9 that opens and closes the exhaust port 6 is driven by an exhaust cam (not shown) of an exhaust camshaft 11 that is rotationally driven by a crankshaft 10.
[0013]
A fuel injection valve 12 (fuel injection device) that is located below the intake port 5 and directly injects fuel into the combustion chamber 1 is attached to the cylinder head 2. Therefore, in this engine, fuel can be supplied to the combustion chamber 1 regardless of whether the intake valve 7 is open or closed. The cylinder head 2 is also provided with an ignition plug 13 positioned substantially in the center of the combustion chamber 1, and the ignition plug 13 sparks the air-fuel mixture in the combustion chamber 1.
[0014]
An upstream side of the intake port 5 is connected to a collector 15 via an intake branch 14 for each cylinder, and an air cleaner 17 is disposed in an intake passage 16 upstream of the collector 15. A downstream side of the exhaust port 6 is connected to an exhaust purification catalyst 19 via an exhaust manifold 18. In this engine, it is assumed that the stoichiometric air-fuel ratio operation is performed under almost all operating conditions, and a general three-way catalyst is used as the exhaust purification catalyst 19.
[0015]
The engine control unit (ECU) 50 includes an air flow meter 51 that outputs a signal corresponding to the intake air amount, an accelerator position sensor 52 that outputs a signal corresponding to the accelerator opening, and the crankshaft 10 at a minute angle (for example, 1 °). A POS sensor 53 that outputs a signal (POS signal) each time it rotates, a REF sensor 54 that outputs a reference crank angle position signal (REF signal) for each cylinder, and a signal corresponding to the control state of the first variable mechanism. An output signal is sent from various sensors such as a first sensor 55 and a second sensor 56 that outputs a signal corresponding to the control state of the second variable mechanism, and the ECU 50 determines the fuel injection valve 12, spark plug 13, A drive signal to be transmitted to the drive control units (20, 21) of the first variable mechanism and the second variable mechanism is calculated.
[0016]
Next, the details of the variable valve gear 8 will be described with reference to FIG.
[0017]
As described above, the variable valve operating apparatus 8 includes the first variable mechanism 101 and the second variable mechanism 102. The first variable mechanism 101 is rotatably supported on the upper part of the cylinder head while being sprocketed. 110 and a drive shaft 150 that interlocks with the crankshaft 10 (see FIG. 1) via a timing chain (not shown) and the like, and each cylinder (# 1 cylinder) is fitted on the outer periphery of the drive shaft 150 so as to be swingable. ˜ # 4 cylinder) is interposed between the swing cam 120 that drives the intake valve 7 to move up and down, and the swing cam 120 is swung in conjunction with the rotation of the drive shaft 150 and the first variable mechanism 101 is driven. The actual use area of the cam surface of the swing cam 120 can be changed by the electric motor 20 which is a control unit.
[0018]
The first variable mechanism 101 includes a circular drive cam 121 that is eccentrically provided on the drive shaft 150 by press-fitting or the like, and a first link that is externally fitted to the outer periphery of the drive cam 121 so as to be relatively rotatable. 122, a control shaft 151 which is disposed substantially parallel to the drive shaft 150 at the top of the cylinder head and is rotationally driven by the electric motor 20, and a circular control which is eccentrically provided by press-fitting into the control shaft 151. A cam 123; a rocker arm 124 fitted on the outer periphery of the control cam 123 so as to be relatively rotatable; and one end pivotally connected to the end of the first link 122; and the other end of the rocker arm 124 And a second link 125 for pivotally connecting the swing cam 120. Although not shown in the drawings, these components are provided for each cylinder (# 1 cylinder to # 4 cylinder) except for the control shaft 151. By rotating the common control shaft 151, these components are provided. The behavior of the swing cam 120 of each cylinder can be controlled in conjunction.
[0019]
Since the rocker arm 124 is eccentrically supported by the control shaft 151 via the control cam 123, the rocking center of the rocker arm 124 changes according to the angular position of the control shaft 151. Therefore, when the rotational position of the control shaft 151 is operated by the electric motor 20, the rocking center of the rocker arm 124 changes so as to be close to or away from the drive shaft 150, and thereby via the second link 125. The actual use area (the pressing area for the intake valve 7) of the cam surface of the swing cam 120 that is operated in this manner is changed.
[0020]
The cam surface of the swing cam 120 has a base circle surface that forms a concentric arc with the drive shaft 150 and a lift surface that extends from the base circle surface in a predetermined curve. The pressing position with respect to the intake valve 7 is changed according to the posture. The base circle surface is a section where the lift amount becomes 0 as a base circle section, and the lift surface is a section where the lift amount is changed according to the profile of the outer surface. The rocking cam 120 changes the pressing area for the intake valve 7 by changing the rocking center of the rocker arm 124 accompanying the turning operation of the control shaft 151, thereby increasing the lift amount of the intake valve and the valve opening to closing. Change the angle range. The end of the control shaft 151 is provided with the first sensor 55 for outputting a signal corresponding to the rotation angle of the shaft 151, and the electric motor 20 is closed based on the detected actual control state. Loop controlled.
[0021]
The second variable mechanism 102 includes a sprocket 110 provided at the front end portion of the drive shaft 150, and a phase control hydraulic actuator 130 that relatively rotates the sprocket 110 and the drive shaft 150 within a predetermined angle range. It is configured. The hydraulic actuator 130 is controlled by an electromagnetic hydraulic control valve 21 that switches or holds pressure between the intake and exhaust hydraulic pressures on the advance side and the retard side. The hydraulic control valve 21 constitutes a drive control unit for the second variable mechanism 102. The hydraulic control valve 21 is controlled by the engine control unit 50 (see FIG. 1) and changes the rotational phase of the crankshaft 10 and the drive shaft 150 by appropriately rotating the sprocket 110 and the drive shaft 150 appropriately. Therefore, the lift center angle in the valve lift is changed to the advance angle or retard angle side by the control by the hydraulic control valve 21. The end of the drive shaft 150 is provided with the second sensor 56 that outputs a signal corresponding to the advance angle of the drive shaft 150 with respect to the crankshaft 10, and the hydraulic control valve 21 detects the detected actual Closed loop control is performed based on the control state.
[0022]
In the case of this engine, the opening / closing timing and lift amount of the intake valve 7 can be arbitrarily adjusted by the variable valve device 8 described above, so that the intake air amount can be controlled without depending on the throttle valve. it can.
[0023]
Next, engine control executed by the ECU 50 will be described.
[0024]
FIG. 3 is a flowchart showing a processing routine for controlling the variable valve gear 8. This processing routine is executed every predetermined time (for example, every 10 [ms]).
[0025]
In S 1, the accelerator opening APO is read from the output signal of the accelerator position sensor 52, the engine rotation speed Ne is read from the memory in the ECU 50, the actual control shaft rotation angle rEL is output from the output signal of the first sensor 55, and the second sensor 56. The actual drive shaft advance angle amount rTC is read from the output signal. However, the engine speed Ne is calculated by the ECU 50 as needed based on the generation time interval of the REF signal output from the REF sensor 54, and the latest value is stored in the memory.
[0026]
In S2, the target control shaft rotation angle tEL and the target drive shaft advance angle amount tTC are calculated based on the accelerator opening APO and the engine speed Ne. The details of the processing in this step will be described in detail. The target torque of the engine is calculated from APO and Ne, the target air amount for realizing this target torque in the theoretical air-fuel ratio operation is calculated, and this target air amount is The optimum valve lift characteristic obtained (for example, the pumping loss is minimized within a range in which combustion stability can be ensured) is determined, and tEL and tTC corresponding to the valve lift characteristic are calculated. However, tEL and tTC can be directly calculated from APO and Ne if the above processing is performed in advance and the result is made into a control map.
[0027]
In S3, a drive signal for causing the actual control shaft rotation angle rEL to approach the target control shaft rotation angle tEL is calculated and transmitted to the drive control unit (electric motor) 20 of the first variable mechanism.
[0028]
In S4, a drive signal for causing the actual drive shaft advance angle amount rTC to approach the target drive shaft advance angle amount tTC is calculated and transmitted to the drive control unit (hydraulic control valve) 21 of the second variable mechanism.
[0029]
FIG. 4 is a flowchart showing a processing routine for determining the control mode of the fuel injection and variable valve operating apparatus. This processing routine is executed every predetermined time (for example, every 10 [ms]).
[0030]
In S10, the accelerator opening APO and the engine speed Ne are read.
[0031]
In S11, an increase amount dAPO of the accelerator opening APO and an increase amount dNe of the engine speed Ne are calculated. As dAPO, a value obtained by subtracting APO from the previous execution of this routine from the APO read in S10, an increase amount of the moving average value of APO, or the like may be used. The same applies to dNe.
[0032]
In S12, it is determined whether or not the accelerator opening increase amount dAPO is smaller than a threshold value dAPOth.
[0033]
When the accelerator opening increase amount dAPO is smaller than the threshold value dAPOth, the routine proceeds to S13, where it is determined whether or not the engine rotation speed increase amount dNe is smaller than the threshold value dNeth.
[0034]
If the engine speed increase amount dNe is smaller than the threshold value dNeth, the process proceeds to S14, and it is determined whether or not a fuel cut condition is satisfied. For example, it is determined that the fuel cut condition is satisfied when the accelerator opening APO is substantially zero and the engine rotational speed Ne is greater than a predetermined rotational speed.
[0035]
When the fuel cut condition is satisfied, the process proceeds to S15, and the control mode is set to the fuel cut mode. When this mode is set, the control of the variable valve gear 8 is prohibited (maintains the current valve lift characteristics) until all cylinders shift to the fuel cut operation. This control is performed with priority over the control of FIG.
[0036]
Since the target air amount rapidly decreases during the shift to the fuel cut operation, a drive signal for rapidly decreasing the air amount is transmitted to the electric motor 20 and the hydraulic control valve 21 according to the control of FIG. . At this time, if there is a cylinder in which fuel injection has already been performed (or started) and is in the intake stroke, the air-fuel ratio of the cylinder may be significantly enriched and rich misfire may occur. For this reason, control of the variable valve gear 8 is prohibited until the combustion of the fuel injected before the fuel cut condition is satisfied.
[0037]
If the fuel cut condition is not satisfied in S14, the process proceeds to S16, and the control mode is set to the steady operation mode. When this mode is set, control of the variable valve gear is performed according to the control of FIG. The fuel injection control will be described later.
[0038]
If the determination in S12 or S13 is NO, the process proceeds to S17, and the control mode is set to the acceleration operation mode. Even when this mode is set, the control of the variable valve apparatus is performed according to the control of FIG. The fuel injection control will be described later.
[0039]
FIG. 5 is a flowchart showing a processing routine for calculating the first fuel injection amount and the injection timing for each cylinder. This processing routine is executed each time the REF sensor 54 outputs the REF signal (REF (1) to REF (4)) of each cylinder. In the following description, n represents a cylinder number, and will be described as processing when REF (n) (#n cylinder REF signal) is output.
[0040]
In S20, it is determined whether or not the currently set control mode is other than the fuel cut mode (steady operation mode or acceleration operation mode).
[0041]
When the control mode is other than the fuel cut mode, the process proceeds to S21, and the intake air amount Qa is read from the output signal of the air flow meter 51, and the engine rotational speed Ne is read from the memory in the ECU 50.
[0042]
In S22, a fuel injection amount Tp1 for setting the air-fuel ratio to the stoichiometric air-fuel ratio is calculated based on the following equation (1).
[0043]
[Expression 1]
Tp1 = K × Qa / Ne (1)
However, K is a constant. Tp1 is calculated as the valve opening time (unit [ms]) of the fuel injection valve 12 for obtaining a necessary fuel amount.
[0044]
In S23, it is determined whether or not the currently set control mode is the steady operation mode.
[0045]
When the control mode is the steady operation mode, the process proceeds to S24, and Tp1 is substituted for the first fuel injection amount Ti1 (n) of the #n cylinder. In this embodiment, as will be described later, fuel injection for each cylinder is performed in two stages, a first fuel injection in the front stage and a second fuel injection in the rear stage.
[0046]
When the control mode is not the steady operation mode in S23, the process proceeds to S25, and it is determined whether or not the fuel injection amount Tp1 is larger than the threshold value Tp1th.
[0047]
When the fuel injection amount Tp1 is larger than the threshold value Tp1th, the process proceeds to S26, and Tp1 is substituted for the first fuel injection amount Ti1 (n) of the #n cylinder.
[0048]
If the determination in S20 or S25 is NO, the process proceeds to S27, and zero is substituted for the first fuel injection amount Ti1 (n) of the #n cylinder. The reason for setting Ti1 (n) to zero when the fuel injection amount Tp1 is equal to or less than the threshold value Tp1th (when the determination in S25 is NO) is to improve the durability by reducing the number of times the fuel injection valve 12 is driven. It is.
[0049]
In S28, the first fuel injection timing IT1 (n) for the #n cylinder is calculated based on the first fuel injection amount Ti1 (n) for the #n cylinder. IT1 (n) is a value for setting the fuel injection start timing of the #n cylinder by the crank angle, and is set at a relatively early time after the exhaust valve 9 is closed. In the direct injection engine as in the present embodiment, it is necessary to inject fuel after the exhaust valve 9 is closed in order to prevent fuel blow-through into the exhaust passage, and also ensure the time for vaporization of the injected fuel and mixing with air. In order to achieve this, it is desirable to inject fuel as early as possible. When Ti1 (n) is zero, an invalid value (crank angle that is impossible in practice) is substituted for IT1 (n).
[0050]
FIG. 6 is a flowchart showing a processing routine for executing the first fuel injection and calculating and executing the second fuel injection amount. This processing routine is executed every time the POS sensor 53 outputs a POS signal.
[0051]
In S30, the crank angle CA is calculated. However, CA is a value taking a range of 1 ° to 720 ° (two revolutions of the crankshaft 10), and CA is calculated from the REF signal for each cylinder generated immediately before and the number of POS signals generated thereafter. be able to.
[0052]
In S31, it is determined whether or not the current crank angle CA coincides with the first fuel injection timing IT1 (n) of the #n cylinder. That is, a process of comparing CA with IT1 (1) to IT1 (4) is performed.
[0053]
When the crank angle CA coincides with the first fuel injection timing IT1 (n) of the #n cylinder, the process proceeds to S32, and a drive signal (valve opening signal) corresponding to the first fuel injection amount Ti1 (n) of the #n cylinder. ) Is transmitted to the fuel injection valve 12 of the #n cylinder. By this drive signal, the fuel injection valve 12 of the #n cylinder is opened only for Ti1 (n) [ms] from the present time.
[0054]
If the crank angle CA does not coincide with the first fuel injection timing of any cylinder, the process of S32 is skipped.
[0055]
In S33, it is determined whether or not the currently set control mode is the acceleration operation mode.
[0056]
At this time, if the control mode is not the acceleration operation mode (that is, the steady operation mode), the process does not proceed after S34, and therefore only the first fuel injection amount Ti1 (n) is given to each cylinder.
[0057]
If the control mode is the acceleration operation mode, the process proceeds to S34, and the actual control shaft rotation angle rEL, the actual drive shaft advance angle amount rTC, and the engine rotation speed Ne are read.
[0058]
In S35, the current intake valve lift amounts L (1) to L (4) of each cylinder are calculated based on the actual control shaft rotation angle rEL, the actual drive shaft advance angle amount rTC, and the crank angle CA.
[0059]
In S36, the data of the intake valve lift amounts L (1) to L (4) of each cylinder is stored in the memory in association with the current crank angle CA. That is, the intake valve lift amount of each cylinder is stored as the following array data.
[0060]
L (n, CA) ... {n: 1 to 4} {CA: 1 to 720}
In S37, it is determined whether or not the lift of the intake valve 7 of the #n cylinder is finished. When the intake valve lift amount L (n) of the #n cylinder when the routine is executed last time is a positive value and the current intake valve lift amount L (n) of the cylinder is zero, #n It can be determined that the cylinder lift has ended.
[0061]
When the lift of the intake valve 7 of the #n cylinder is completed, the process proceeds to S38, and the valve lift curve of the #n cylinder (which can be reproduced from the L (n, CA) data from the lift start to the lift end), the engine speed Ne, From this, the intake air amount Qa2 is calculated. During the acceleration operation, the control state of the variable valve operating device 8 is constantly changing toward the large intake air amount. If the calculation is performed in consideration of an actual valve lift curve reflecting this change, the intake air can be accurately calculated. The amount can be estimated.
[0062]
In S39, the fuel injection amount Tp2 for setting the air-fuel ratio to the stoichiometric air-fuel ratio is calculated based on the following equation (2).
[0063]
[Expression 2]
Tp2 = K × Qa2 / Ne (2)
In S40, the second fuel injection amount Ti2 is calculated by subtracting the already injected first fuel injection amount Ti1 (n) from the fuel injection amount Tp2 calculated in S39.
[0064]
In S41, a drive signal corresponding to the second fuel injection amount Ti2 is transmitted to the fuel injection valve 12 of the #n cylinder. By this drive signal, the fuel injection valve 12 of the #n cylinder is opened only for Ti2 [ms] from the present time (immediately after the end of the lift).
[0065]
If it is determined in S37 that none of the intake valve lift ends for any cylinder, the routine ends without performing the processing in S38 and subsequent steps.
[0066]
By performing the fuel injection control (FIGS. 4 to 6) as described above, it is possible to approach the stoichiometric air-fuel ratio even during acceleration operation. As a result, the lean air-fuel ratio during acceleration operation is prevented, and the engine The drivability is improved and the NOx emissions are also reduced.
[0067]
In the processing routine of FIG. 6, the intake air amount Qa2 is calculated from the history data of the intake valve lift amount. However, instead of the history data of the intake valve lift amount, the control state data of the variable valve gear is used as the crank angle. You may make it memorize | store corresponding to CA. In this case, the data to be stored is the following two array data, and the data amount can be reduced.
rEL (CA) ... {CA: 1 to 720}
rTC (CA) ... {CA: 1 to 720}
The intake valve lift amount of each cylinder at an arbitrary crank angle CA can be calculated from the actual control shaft rotation angle history data rEL (CA) and the actual drive shaft advance angle history data rTC (CA). The valve lift curve of any cylinder can be reproduced.
[0068]
In the processing routine of FIG. 5, the fuel injection amount Tp1 is calculated from the intake air amount Qa detected by the air flow meter 51. However, the intake is calculated from the actual control shaft rotation angle rEL and the actual drive shaft advance angle amount rTC at the time of execution of the routine. The air amount Qa may be calculated. During steady operation, the intake air amount calculated from rEL and rTC and the intake air amount detected by the air flow meter 51 should match. However, it is more advantageous to use an air flow meter in consideration of changes in environmental conditions (atmospheric pressure and atmospheric temperature), engine temperature conditions, and changes over time of the engine (such as deposits around the intake valve).
[0069]
In the processing routine of FIG. 4, the acceleration operation state is determined from the accelerator opening increase amount dAPO and the engine rotational speed increase amount dNe. The control state change amount of the variable valve device 8 (actual control shaft rotation) Change amount of angle rEL, change amount of actual drive shaft advance angle amount rTC, deviation amount between actual control shaft rotation angle rEL and target control shaft rotation angle tEL, actual drive shaft advance angle amount rTC and target drive shaft advance angle amount tTC It is even better to make a determination by adding a deviation amount).
[0070]
In the present embodiment, the second fuel injection is performed only during the acceleration operation. However, the second fuel injection may be performed during the transient operation including the deceleration operation. That is, if the process of FIG. 6 is applied as it is during the deceleration operation, the second fuel injection amount Ti2 becomes a negative value, but if the first fuel injection amount Ti1 is changed to be set to be smaller than Tp1 in advance, the deceleration operation is performed. The second fuel injection at the time can be a positive value. In this case, enrichment of the air-fuel ratio during deceleration operation can be prevented, and HC and CO emissions during deceleration operation can be reduced.
[0071]
Furthermore, in a spark ignition type engine that directly injects fuel into the cylinder as in this embodiment, when switching between stratified operation and homogeneous operation according to the operating conditions, the opening of the intake valve starts during stratified operation. Fuel injection is performed during the compression stroke in an amount corresponding to the control history of the variable valve operating apparatus from the valve to the valve closing. In this way, an appropriate amount of fuel can be obtained by one fuel injection during the stratified operation.
[0072]
FIG. 7 shows the overall configuration of the second embodiment.
[0073]
The fuel injection valve 12 b of this embodiment is attached to the intake branch 14 for each cylinder, and injects fuel toward the intake port 5. The other configuration is the same as that of the first embodiment, and in FIG. 7, the same reference numerals are given to the same portions as those of the first embodiment.
[0074]
In an intake port injection type engine, there is no need to consider fuel blow-off into the exhaust passage, so it is possible to supply fuel for the next cycle any time after the intake valve is closed. If fuel injection is performed during the valve closing period, the heat of the intake port and the intake valve can be effectively used to vaporize the fuel. Therefore, in the present embodiment, the first fuel injection timing IT1 (n) of each cylinder is set to the exhaust stroke of each cylinder.
[0075]
On the other hand, in an intake port injection type engine, the second fuel injection cannot be performed after the intake valve is closed as in the first embodiment. Therefore, it is necessary to estimate the intake air amount by predicting the valve lift curve until the valve is closed while the intake valve 7 is open, and to calculate the second fuel injection amount Ti2 based on the predicted intake air amount. There is. Hereinafter, a specific processing method will be described.
[0076]
FIG. 8 is a flowchart showing a processing routine for executing the first fuel injection and calculating and executing the second fuel injection amount. The steps (S30 to S35 and S39 to S41) common to FIG. 6 are shown. It is omitted.
[0077]
In S50, it is determined whether or not the lift of the intake valve 7 of the #n cylinder has started. When the intake valve lift amount L (n) of the #n cylinder when this routine was executed last time is zero and the current intake valve lift amount L (n) of the cylinder is a positive value, #n It can be determined that the cylinder lift has started.
[0078]
When the lift of the intake valve 7 of the #n cylinder starts, the process proceeds to S51, where the current actual control shaft rotation angle rEL is set to the control shaft rotation angle ELs (n) at the start of the #n cylinder lift, and the current actual drive shaft advance The angular amount rTC is stored as the drive shaft advance angle amount TCs (n) at the start of #n cylinder lift.
[0079]
In S52, the value of the timer t (n) prepared for each cylinder is reset to zero. This timer t (n) measures the elapsed time from the start of lift of the intake valve 7 of the #n cylinder.
[0080]
In S50, if it does not correspond to the intake valve lift start timing of any cylinder, the processing of S51 and S52 is skipped.
[0081]
In S53, it is determined whether or not the lift of the intake valve 7 of the #n cylinder is maximized. When the intake valve lift amount L (n) of the #n cylinder this time is a positive value and L (n) turns from increasing to decreasing, the lift of the intake valve 7 of the #n cylinder is maximized. Judgment can be made.
[0082]
If the lift of the intake valve 7 of the #n cylinder reaches the maximum, the process proceeds to S54, where the control shaft rotation angle ELs (n) at the start of the #n cylinder lift, the current actual control shaft rotation angle rEL, and the #n cylinder timer Based on t (n), the control shaft rotation speed vEL in the period from the lift start to the lift maximum is calculated based on the following equation (3).
[0083]
[Equation 3]
vEL = (rEL-ELs (n)) / t (n) (3)
In S55, from the start of the lift to the maximum lift based on the drive shaft advance amount TCs (n) at the start of #n cylinder lift, the current actual drive shaft advance amount rTC, and the #n cylinder timer t (n). The drive shaft advance angular velocity vTC in the period is calculated based on the following equation.
[0084]
[Expression 4]
vTC = (rTC−TCs (n)) / t (n) (4)
In S56, the control shaft rotation angle ELs (n) at the start of #n cylinder lift, the drive shaft advance angle amount TCs (n) at the start of #n cylinder lift, the control shaft rotation speed vEL, the drive shaft advance angle speed vTC, the engine rotation The intake air amount Qa2 is predicted based on the speed Ne. That is, the control state change speed of the variable valve device 8 calculated at the time of the maximum lift is regarded as the change speed from the start of lift to the end of lift, and from this change speed and the control state of the variable valve device 8 at the start of lift. The intake air amount Qa2 is estimated by predicting the valve lift curve. If the second fuel injection amount Ti2 is calculated using the intake air amount Qa2, the second fuel injection can be executed during the period from the lift maximum to the lift end.
[0085]
Note that the calculation of the intake air amount Qa2 is performed at the time when the lift is maximum, since approximately half of the valve opening period has elapsed, it is possible to calculate the average control state change speed to some extent, and the remaining This is because the second fuel injection can be surely executed during the period.
[0086]
Further, the point that the first fuel injection amount Ti1 (n) is set to zero when the fuel injection amount Tp1 is equal to or less than the threshold value Tp1th is the same as in the first embodiment. In the present embodiment, the first step of the exhaust stroke is performed. One fuel injection is not performed, and only the second fuel injection in the intake stroke is performed. In this case, the fuel cannot be vaporized by using the heat of the intake port 5 or the intake valve 7, but instead, the fuel is atomized by using the intake air flow when passing through the intake valve 7. be able to. That is, when the load is low such that Tp1 is equal to or less than Tp1th, the intake valve lift amount is also small, and the flow rate of the intake air when passing through the intake valve 7 is very fast. Good fuel atomization can be achieved by placing fuel directly on this fast air flow.
[0087]
The relationship between the change in the operating angle of the control shaft in accordance with the time change in the second embodiment described above, and the fuel injection timing and the intake valve lift amount change in each cylinder is as shown in FIG.
[0088]
Next, a third embodiment will be described.
[0089]
The overall configuration of this embodiment is the same as the overall configuration of the second embodiment shown in FIG. 7, and only the method for predicting the intake air amount Qa2 is different from that of the second embodiment. Hereinafter, a specific processing method will be described. FIG. 13 shows a time chart similar to FIG. 12 of this embodiment.
[0090]
FIG. 9 is a flowchart showing a processing routine for executing the first fuel injection and calculating and executing the second fuel injection amount. The steps (S30 to S35 and S39 to S41) common to FIG. 6 are shown. It is omitted.
[0091]
In S60, it is determined whether or not the lift of the intake valve 7 of the #n cylinder has started.
[0092]
When the lift of the intake valve 7 of the #n cylinder starts, the process proceeds to S61, and the control shaft rotational speed vEL is calculated based on the actual control shaft rotational angle rEL and the target control shaft rotational angle tEL. The greater the deviation between the two, the greater the control shaft rotational speed vEL. The relationship between the deviation and the control shaft rotational speed vEL is a known relationship determined by the control gain of the first variable mechanism control (S3 in FIG. 3).
[0093]
In S62, the drive shaft advance angle velocity vTC is calculated based on the actual drive shaft advance angle amount rTC and the target drive shaft advance angle amount tTC. The larger the deviation between the two, the larger the drive shaft advance angular velocity vTC. The relationship between the deviation and the drive shaft advance angular velocity vTC is a known relationship determined by the control gain of the second variable mechanism control (S4 in FIG. 3).
[0094]
In S63, the intake air amount Qa2 is predicted based on the actual control shaft rotation angle rEL, the actual drive shaft advance angle amount rTC, the control shaft rotation speed vEL, the drive shaft advance angle velocity vTC, and the engine rotation speed Ne. That is, the control state change speed calculated from the deviation between the current control state and the target control state of the variable valve apparatus 8 is regarded as the change speed from the lift start to the lift end, and the valve is calculated from this change speed and the current control state. A lift curve is predicted to determine the intake air amount Qa2.
[0095]
In the present processing routine (the processing routine in FIG. 6), the second fuel injection is executed immediately after the prediction of the intake air amount Qa2 is confirmed, so the second fuel injection in the present embodiment is executed immediately after the start of the lift. However, since the calculation of the control state change speed as in this embodiment can be performed at any time, the intake air amount Qa2 is predicted and the second fuel injection is performed at another timing (for example, immediately after the end of the first fuel injection). Is also possible. Further, for example, when the variable valve device 8 is controlled to the small lift side, fuel is injected (only the second fuel injection) during the intake stroke, and the variable valve device 8 exceeds the set threshold value. When controlled to the lift side, fuel injection (first fuel injection and second fuel injection) may be performed during the exhaust stroke. In such a case, the number of operations of the fuel injection valve 12b within one cycle can be reduced to one.
[0096]
When the change speed of the operation state (accelerator opening APO, engine speed Ne) is large, the control state change speed of the variable valve device 8 is slower than the operation state change speed (the control state of the variable valve device 8 is the operation state). The control state change speed in this case is determined by the control response speed of the variable valve apparatus 8. Therefore, an appropriate second fuel injection amount can be calculated even if the intake air amount Qa2 is predicted as in the present embodiment. Further, the processing is simpler than that of the second embodiment, and the calculation load on the ECU 50 can be reduced.
[0097]
Next, a fourth embodiment will be described. The time chart of this embodiment is the same as that in FIG.
[0098]
The overall configuration of the present embodiment is the same as the overall configuration of the second embodiment shown in FIG. 7, and only the method for predicting the intake air amount Qa2 is different from the second embodiment. Hereinafter, a specific processing method will be described.
[0099]
FIG. 10 is a flowchart showing a processing routine for executing the first fuel injection and calculating and executing the second fuel injection amount. The steps (S30 to S35 and S39 to S41) common to FIG. 6 are shown. It is omitted.
[0100]
In S70, it is determined whether or not the lift of the intake valve 7 of the #n cylinder is maximized.
[0101]
When the lift of the intake valve 7 of the #n cylinder reaches the maximum, the process proceeds to S71, and the intake air amount Qa2 is predicted based on the actual control shaft rotation angle rEL, the actual drive shaft advance angle amount rTC, and the engine rotation speed Ne. . That is, the intake air amount Qa2 is predicted and determined by predicting the valve lift curve from the control state of the variable valve apparatus 8 at the time when the lift becomes maximum.
[0102]
FIG. 11 shows a valve lift curve when the control shaft rotation angle increases at a constant speed. Since rEL increases during the lift, the actual valve lift changes as shown by a thick solid line. Here, when the valve lift curve corresponding to the control shaft rotation angle rEL at the maximum lift (without considering the change of the control shaft rotation angle) is compared with the actual valve lift curve, the maximum lift is obtained in the region where the lift amount increases. The time area of the corresponding valve lift curve is larger than the time area of the actual valve lift curve. Conversely, the time area of the actual valve lift curve is larger than the time area of the valve lift curve corresponding to the maximum lift in the region where the lift amount decreases. Become. As a result, there is no significant difference between the two in terms of the overall time area.
[0103]
On the other hand, if the drive shaft advance speed is constant, the lift center angle phase corresponding to the drive shaft advance angle at the maximum lift is substantially the same as the lift center angle phase of the actual valve lift curve.
[0104]
From the above, also in the present embodiment in which the intake air amount Qa2 is predicted very simply, the effect of reducing the air-fuel ratio leaning generated during the acceleration operation to some extent can be obtained.
[0105]
Hereinafter, technical ideas that can be grasped from the above-described embodiments will be listed together with their effects.
[0106]
(A) The control history of the variable valve operating device from the start to the closing of the intake valve is determined based on data related to the control, and the fuel injection amount is controlled according to the determined control history. A control apparatus for a variable valve engine characterized by the above.
[0107]
In this case, in order to control the injected fuel amount in consideration of the change in the intake air amount that occurs in response to the change in the intake valve control amount during the valve opening period that occurs at the time of acceleration / deceleration, the variable valve control is not stopped unnecessarily. It is possible to optimize the fuel ratio, improve drivability, and suppress emission deterioration.
[0108]
(B) The variable valve operating apparatus according to (a), wherein the variable valve operating apparatus adjusts the opening / closing timing and lift amount of the intake valve in conjunction with a plurality of cylinders.
[0109]
In this case, when the variable valve operating device is operated during the acceleration / deceleration operation, the fuel injection device corresponding to each cylinder is controlled taking into account the change in intake air amount corresponding to the variable valve control. The air-fuel ratio control hardly affects the air-fuel ratio control of other cylinders, and the air-fuel ratio control and output control for each cylinder can be performed more strictly.
[0110]
(C) The control history may be determined and predicted based on data related to control of the variable valve gear before completion of closing of the intake valve. Control device for variable valve engine.
[0111]
In this case, since the fuel injection amount is determined before the closing of the intake valve, the correction of the fuel injection amount can be performed reliably at an early stage.
[0112]
(D) When the engine is accelerating and / or decelerating, the control history is predicted and determined before the intake valve is closed based on the control amount change speed of the variable valve gear, The control apparatus for a variable valve engine according to (c), wherein additional control of fuel is performed according to a control history.
[0113]
In this case, similarly, correction of the fuel injection amount can be performed reliably at an early stage.
[0114]
(E) When the engine is accelerating and / or decelerating, the lift characteristic of the variable valve gear when the lift amount of the intake valve becomes substantially maximum is determined as the control history (c) A control apparatus for a variable valve engine according to claim 1.
[0115]
In this case, as in the case of (d), the correction of the fuel injection amount can be reliably performed at an early stage, and the control history to be determined is not easily affected by the change in the detected value, so that noise or the like It is possible to eliminate the unspecificity that the control becomes unstable due to the disturbance.
[0116]
(F) When the engine is accelerating and / or decelerating, the control history is predicted before the intake valve is closed based on the degree of deviation between the actual control value of the variable valve device and the control target value. The control apparatus for a variable valve engine according to (c), wherein the control is confirmed and additional control of the fuel is performed according to the control history during the intake stroke.
[0117]
Also in this case, correction of the fuel injection amount can be reliably performed at an early stage as in the cases (d) and (e).
[0118]
(G) Whether or not additional fuel is allowed during the intake stroke is determined based on the engine speed and the accelerator pedal opening, and when it is determined that the fuel is determined to be acceptable, the control history of the variable valve gear according to the speed and the opening The control apparatus for a variable valve engine according to any one of (c) to (f), wherein additional control of fuel is performed based on the control.
[0119]
In this case, since additional correction of fuel can be performed at the timing intended by the driver, the difference between the required torque and the actually obtained torque can be reduced and the driving feeling can be enhanced.
[0120]
(H) When the engine suddenly decelerates, the operation control of the variable valve operating device is stopped until the cut control or decrease control of the injected fuel is completed, and after the cut control or decrease control is completed, the variable valve operating device is moved to the small lift side. The control apparatus for a variable valve engine according to any one of (a) to (g), wherein
In this case, when the engine suddenly decelerates, before the cut control or reduction control of the injected fuel is completed, the variable valve operating device is controlled to the small lift side, so that the problem that the combustion temporarily becomes rich can be eliminated.
[0121]
(I) While determining from the engine speed and the accelerator pedal opening, from the control amount change speed of the variable valve operating system, or from the degree of deviation between the control target value and the control actual value, the steady operation and the acceleration operation are determined. The control of the variable valve engine according to any one of (a) to (h), wherein when it is determined that the engine is in steady operation, the fuel injection amount control according to the control history of the variable valve device is prohibited. apparatus.
[0122]
In this case, at the time of steady operation, an accurate air-fuel ratio can be obtained without being affected by sensor noise, atmospheric pressure change or the like.
[0123]
(J) While determining from the engine speed and the accelerator pedal opening, from the control amount change speed of the variable valve operating system, or from the degree of deviation between the control target value and the actual control value, it is determined during steady operation and acceleration operation. The fuel injection amount is controlled according to the control history of the variable valve operating apparatus from the start to the closing of the intake valve only when it is determined that the acceleration operation is being performed (a) to (i) The control apparatus for a variable valve engine according to any one of the above.
[0124]
In the case of this invention, at the time of acceleration operation, it is possible to perform fuel injection amount control adapted to the intake air amount in consideration of the control history from the start of opening of the intake valve to the valve closing, and at the time of steady operation, sensor noise and atmospheric pressure Stable air-fuel ratio control can be performed without being affected by changes or the like.
[0125]
(K) The variable valve device includes: a drive shaft that rotates in conjunction with a crankshaft of an engine; and a swing cam that is swingably fitted to the outer periphery of the drive shaft and drives the intake valve to move up and down. A drive cam provided eccentrically with respect to the drive shaft and rotating integrally with the drive shaft; and a first link externally fitted to the outer periphery of the drive cam so as to be relatively rotatable; A control shaft that is arranged substantially parallel to the drive shaft and is rotationally driven by an actuator, a control cam that is eccentrically provided on the control shaft, rotates integrally with the control shaft, and rotates relative to the outer periphery of the control cam. A rocker arm that is externally fitted and has one end connected to the tip of the first link, and a second link connected to the other end of the rocker arm and the swing cam. (A) to (j Control device for a variable valve engine according to any one of.
[0126]
In this case, the above-described effects can be obtained even with a direct acting valve drive system.
[0127]
(L) A control apparatus for a variable valve engine that performs fuel injection in the intake pipe, and when the variable valve apparatus is controlled to the small lift side, fuel is injected during the intake stroke, and the variable valve apparatus is set. The control device for a combustible valve engine according to any one of claims (a) to (k), wherein fuel is injected during an exhaust stroke when the engine is controlled to a large lift side exceeding a threshold value. .
[0128]
In this case, since the fuel is injected either in the intake stroke or in the exhaust stroke according to the control state of the variable valve operating apparatus, the fuel can be injected once per cycle. As a result, the number of fuel injections can be reduced, so that the life of the fuel injection device can be extended and the design cost of the injection drive circuit can be reduced.
[0129]
(M) A control device for a spark ignition type variable valve engine that directly injects fuel into a cylinder and switches between stratified operation and homogeneous operation according to the operating state. The control of the variable valve engine according to any one of (a) to (k), wherein fuel injection is performed during the compression stroke in an amount corresponding to the control history of the variable valve operating device from valve start to valve closing. apparatus
In this case, at the time of stratification operation, an appropriate amount of fuel can be achieved by one fuel injection.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a first embodiment of the invention of this application.
FIG. 2 is a schematic perspective view showing a variable valve mechanism of the same embodiment.
FIG. 3 is a flowchart showing a control flow of the embodiment.
FIG. 4 is a flowchart showing a control flow of the embodiment.
FIG. 5 is a flowchart showing a control flow of the embodiment.
FIG. 6 is a flowchart showing a control flow of the embodiment.
FIG. 7 is a schematic configuration diagram showing a second embodiment of the invention of this application.
FIG. 8 is a flowchart showing a control flow of the embodiment.
FIG. 9 is a flowchart showing a control flow of a third embodiment of the invention of this application.
FIG. 10 is a flowchart showing the flow of control according to the fourth embodiment of the invention of this application;
FIG. 11 is a diagram combining a control shaft rotation angle-crank angle characteristic diagram and an intake valve lift amount-crank angle characteristic diagram showing the embodiment;
FIG. 12 is a time chart showing operation timings of the second embodiment and the fourth embodiment.
FIG. 13 is a time chart showing the operation timing of the third embodiment.
[Explanation of symbols]
7 ... Intake valve
8 ... Variable valve gear
12, 12b ... Fuel injection valve (fuel injection device)
120 ... Oscillating cam
121 ... Driving cam
122 ... The first link
123 ... Control cam
124 ... Rocker arm
125 ... Second link
150 ... Drive shaft
151 ... Control axis

Claims (11)

A fuel injection device that supplies fuel to each cylinder and a variable valve device that can adjust the opening / closing timing and lift amount of the intake valve are provided, and the intake air amount can be controlled by controlling the variable valve device. In the control device for the variable valve engine,
First fuel injection amount calculating means for calculating a first fuel injection amount based on an intake air amount;
Second fuel injection amount calculating means for calculating a second fuel injection amount based on an intake air amount estimated in consideration of a valve lift curve of a cylinder that injects the first fuel injection amount;
During operating conditions a transient, after injecting the first fuel injection amount to calculate the second fuel injection amount, further wherein the first difference between the second fuel injection amount and the first fuel injection amount A control apparatus for a variable valve engine, which performs injection so as to contribute to combustion of fuel by a fuel injection amount .   2. The control apparatus for a variable valve engine according to claim 1, wherein the variable valve apparatus adjusts the opening / closing timing and lift amount of the intake valve in conjunction with a plurality of cylinders. The engine is a in which fuel is injected into an intake port, said second fuel injection amount calculating means, the first based on a valve lift curve and before closing the completion of the intake valve from the open-starting of the intake valve 3. The variable valve operating system according to claim 1 , wherein two fuel injection amounts are predicted , and a difference between the first fuel injection amount and the second fuel injection amount is injected by the end of lift of the intake valve. Engine control device.   The second fuel injection amount calculating means predicts a valve lift curve of the intake valve before the closing of the intake valve based on a control amount change speed of the variable valve operating apparatus, and predicts the valve lift curve of the intake valve. 4. The control of the variable valve engine according to claim 3, wherein the second fuel injection amount is calculated according to the fuel injection amount, and the same amount of fuel as the second fuel injection amount is injected as a total amount before completion of the intake stroke. apparatus.   The second fuel injection amount calculating means predicts a valve lift curve of the intake valve based on a control actual value of the variable valve apparatus when the lift amount of the intake valve becomes substantially maximum. Item 4. The control device for a variable valve engine according to Item 3.   The second fuel injection amount calculating means predicts a valve lift curve of the intake valve based on the degree of deviation between the actual control value of the variable valve operating device and the control target value before the intake valve is closed, and the prediction The second fuel injection amount is calculated according to the valve lift curve of the intake valve, and the same amount of fuel as the second fuel injection amount is injected as a total amount before completion of the intake stroke. Variable valve engine control device.   7. The fuel according to claim 1, wherein during the deceleration operation, when the first fuel injection amount is injected, an amount of fuel smaller than the calculated first fuel injection amount is injected. Control device for variable valve engine.   When the engine suddenly decelerates, the variable valve device operation control is stopped until the injection fuel cut control or reduction control is completed, and the variable valve device is controlled to the small lift side after the cut control or reduction control is completed. The control apparatus for a variable valve engine according to any one of claims 1 to 7.   Based on the engine speed and accelerator pedal opening, the control valve change rate of the variable valve system, or the degree of divergence between the control target value and the actual control value, the steady operation and the acceleration operation are judged and the steady operation 9. The control apparatus for a variable valve engine according to claim 1, wherein when the time is judged, calculation of the second fuel injection amount is prohibited and only the first fuel injection amount is injected. .   Judgment of steady operation and acceleration operation is made from the engine speed and accelerator pedal opening, the control amount change speed of the variable valve system, or the degree of deviation between the control target value and the control actual value, and the acceleration operation The second fuel injection amount is calculated only when it is determined that the time has elapsed, and after the first fuel injection amount is injected, the difference between the first fuel injection amount and the second fuel injection amount is further injected. The control apparatus for a variable valve engine according to any one of claims 1 to 9. The variable valve operating device is:
A drive shaft that rotates in conjunction with the crankshaft of the engine;
A swing cam that is swingably fitted to the outer periphery of the drive shaft and drives the intake valve to move up and down;
It is provided between
A drive cam provided eccentric to the drive shaft and rotating integrally with the drive shaft;
A first link that is fitted on the outer periphery of the drive cam so as to be relatively rotatable;
A control shaft disposed substantially parallel to the drive shaft and driven to rotate by an actuator;
A control cam provided eccentric to the control shaft and rotating integrally with the control shaft;
A rocker arm that is fitted on the outer periphery of the control cam so as to be relatively rotatable, and has one end connected to the tip of the first link;
A second link connected to the other end of the rocker arm and the swing cam;
The control device for a variable valve engine according to any one of claims 1 to 10, characterized in that

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