JP5708909B2 - Engine control device - Google Patents

Description

  The present invention relates to an engine control device, and more particularly to an engine control device that advances VVT during idling and retards VVT during off-idling.

The so-called pre-ignition that prematurely ignites near the top dead center of the compression stroke is mainly suppressed by reducing the in-cylinder temperature and the in-cylinder pressure.
Here, a variable valve timing mechanism (hereinafter referred to as a VVT mechanism) that makes the opening / closing timing of the intake valve timing variable is known. By this VVT, the VVT retarded angle, that is, the closing timing of the intake valve is delayed, thereby reducing the effective compression ratio in the cylinder. As a result, adiabatic compression is less likely to occur, the in-cylinder pressure is reduced, and pre-ignition It is known that the occurrence of the occurrence can be suppressed.

  Patent Document 1 discloses an engine control device that suppresses pre-ignition by retarding the opening / closing timing of an intake valve to reduce the effective compression ratio at low rotation / high load.

Japanese Patent Laying-Open No. 2005-076466

  Here, the situation where the driver depresses the throttle pedal and shifts to off-idle time from idling is due to the fact that the amount of air in the cylinder increases relatively rapidly and the in-cylinder pressure rises. This is the situation where pre-ignition is most likely to occur. Since such pre-ignition affects the reliability of the engine, the VVT mechanism retards the intake valve by the VVT mechanism and suppresses the occurrence of pre-ignition at the time of transition from the idling time to the off-idling time. There is a need.

Here, the VVT mechanism mainly includes a hydraulic type and an electric motor type. The electric motor type has a higher response speed than the hydraulic type, and can accurately obtain the VVT retardation speed and the advance amount.
However, in the experiment and development process, the inventors of the present invention also have a predetermined VVT retardation that is a target for suppressing pre-ignition when shifting from idle to off-idle even in a VVT mechanism that uses an electric motor. On the other hand, it was found that a response delay occurs in the actually obtained VVT retardation. This response delay is the timing at which the intake valve closes earlier than the target timing. As a result, the effective compression ratio in the cylinder and the in-cylinder pressure cannot be reduced sufficiently, so The present inventors have found a problem that the occurrence of ignition cannot be suppressed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an engine control device capable of suppressing the occurrence of pre-ignition even when a response delay of an actual VVT retardation occurs. And

In order to achieve the above object, the present invention is an engine control device having a variable valve timing mechanism that varies the opening / closing timing by retarding an intake valve by VVT or advancing VVT. Based on the effective compression ratio limit, the VVT delay angle control means for causing the mechanism to advance the VVT at the time of idling and retarding the VVT from the VVT advance angle position at the time of off-idle, and the effective compression ratio limit at which pre-ignition occurs. VVT advance limit amount calculating means for calculating the VVT advance limit amount, target VVT advance amount setting means for setting the target VVT advance amount of the variable valve timing mechanism at the time of transition from idle time to off-idle time, When the target VVT advance angle amount is larger than the VVT advance angle limit amount at the time of transition from idle to off-idle, VVT advance limit amount control means for limiting the VVT advance amount to the VVT advance limit amount, and at the time of transition from idling time to off-idle time, the VVT retard angle control means sets the target VVT advance amount The variable valve timing mechanism is controlled so as to obtain the target VVT advance amount set by the setting means or the VVT advance limit amount limited by the VVT advance limit control means, and the engine control means further includes: During transition from idling to off-idling and until the actual VVT advance amount becomes the target VVT advance amount by control of the variable valve timing mechanism by the VVT retard control means, or the actual VVT advance angle If the actual VVT advance amount is larger than the VVT advance limit amount until the amount reaches the limited VVT advance limit amount, the pre-ignition is based on the actual phase of the VVT at the time of transition. A first limit air amount calculating means for calculating a limit air amount at which a throttle occurs, and a first throttle valve opening setting for setting the throttle valve opening so that the actual air amount does not increase beyond the calculated limit air amount And means.
In the present invention configured as described above, the limit air amount at which pre-ignition occurs is calculated based on the actual phase of the VVT at the time of transition from the idle time to the off-idle time, and is greater than the calculated limit air amount. Since the throttle valve opening (change) is set so that the actual air amount does not increase, the occurrence of pre-ignition can be suppressed. In addition, since the throttle valve opening (change) is set so that the actual air volume does not increase beyond the calculated limit air volume, the occurrence of pre-ignition is suppressed without smoothing the throttle opening. However, the start of the vehicle can be secured by opening the throttle valve as quickly as possible. That is, if the throttle opening is uniformly smoothed, the throttle valve closes and the startability is sacrificed even if there is a sufficient amount of air for pre-ignition. Since the throttle valve opening (change) is set so that the actual air amount does not increase as described above, this can be prevented.

In the present invention, it is preferable that the second limit air amount calculating means for calculating the limit air amount of the pre-ignition based on the actual phase of the VVT at the time of low rotation, and more than the calculated limit air amount. Second throttle valve opening setting means for setting the throttle valve opening so that the amount of air does not increase.
In the present invention configured as described above, since the (maximum) opening of the throttle valve is set so that the pre-ignition limit air amount does not exceed the pre-ignition limit air amount at the time of low rotation, the transition from the idle time to the off-idle time, The occurrence of pre-ignition can be suppressed even during low rotation after the vehicle has started.

In the present invention, preferably, the calculation of the pre-ignition limit air amount by the first limit air amount calculation means and / or the second limit air amount calculation means is first performed using a predetermined polynomial model from the actual intake manifold pressure. The effective compression ratio limit at which ignition occurs is calculated, then the limit intake manifold pressure is calculated from the actual phase of VVT that is equivalent to the actual effective compression ratio , using an inverse function of a predetermined polynomial model , and this limit The limit air amount at which pre-ignition corresponding to the intake manifold pressure occurs is calculated.
In the present invention configured as described above, the effective compression ratio limit at which pre-ignition occurs from the actual intake manifold pressure is calculated using a predetermined polynomial model, and further, the inverse function of the predetermined polynomial model is used to calculate the VVT. Since the limit air amount that causes pre-ignition is calculated from the actual phase, even if the response of the actual VVT delay is delayed from the target VVT delay, the limit air amount that causes the pre-ignition can be obtained effectively.

  According to the engine control apparatus of the present invention, it is possible to suppress the occurrence of pre-ignition even when the response delay of the actual VVT retardation occurs.

It is a schematic block diagram of the engine provided with the engine control apparatus by embodiment of this invention. It is a partial cross section side view which shows the structure of the variable valve timing mechanism of the engine provided with the control apparatus of the engine by embodiment of this invention. It is a front view which shows the structure of the variable valve timing mechanism of the engine provided with the control apparatus of the engine by embodiment of this invention. It is a block diagram which shows the control apparatus of the engine by embodiment of this invention. It is a flowchart which shows the control flow of the control performed by the control apparatus of the engine by embodiment of this invention. It is a figure for demonstrating the content of the calculation performed within the control flow of FIG. It is a diagram which shows the effective compression ratio limit / VVT advance angle limit with respect to intake manifold pressure / limit air quantity and effective compression ratio / VVT actual phase. FIG. 5 is a diagram showing an actual VVT advance amount and a target VVT advance amount for explaining a response delay of an actual VVT delay angle at the time of transition from idle time to off-idle time. It is a diagram which shows the relationship between the throttle opening and an intake manifold pressure at the time of the transition from idling to off idling. It is a diagram which shows the target air quantity for demonstrating an example of the calculation result performed with the control flow of FIG. FIG. 6 is a diagram showing an intake manifold pressure and a throttle opening for explaining an example of a control result executed in the control flow of FIG. 5.

Hereinafter, an engine control apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.
First, a schematic configuration of an engine provided with an engine control apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of an engine including an engine control apparatus according to an embodiment of the present invention.

  First, as shown in FIG. 1, an engine 1 includes a cylinder 2 that forms a combustion chamber 2a, a piston 4 that reciprocates in the cylinder 2, a connecting rod 6 that is connected to the piston 4 at one end, It has a crankshaft 8 to which the other end of the connecting rod 6 is connected, and a fuel supply device 10 for supplying fuel to the combustion chamber 2a.

  An intake system that supplies air to the combustion chamber 2a of the engine 1 is provided with an air cleaner 12 that purifies the intake air, and an intake passage 13 that extends from the air cleaner 12 to the intake port 20. 12, an intake air temperature / flow rate sensor 14 for detecting the temperature and flow rate of the air sucked through 12; an electronically controlled throttle valve 16 for changing the intake air amount; and a throttle valve opening for detecting the opening of the throttle valve 16 A sensor 18 is provided. The air sucked through these intake systems flows into the combustion chamber 2a through the intake port 20 communicating with the intake opening of the combustion chamber 2a and the intake valve 22 that opens and closes the intake opening. The engine 1 also has a spark plug 23 that burns an air-fuel mixture obtained by injecting fuel into the air flowing into the combustion chamber 2a.

The exhaust gas combusted in the combustion chamber 2a is discharged to the exhaust system of the engine 1 through an exhaust port 24 communicating with the exhaust opening of the combustion chamber 2a and an exhaust valve 26 that opens and closes the exhaust opening. The exhaust system that exhausts the exhaust gas of the engine 1 is provided with a linear O ₂ sensor 28, a first catalyst 30, a lambda O ₂ sensor 32, and a second catalyst 34.

  The engine 1 also includes a crank angle sensor 36 that detects the rotation angle of the crankshaft 8 and an engine water temperature sensor 38 that detects the temperature of engine cooling water flowing through the water jacket of the cylinder block of the engine.

  Next, as shown in FIG. 1, the fuel supply device 10 is pumped by the fuel tank 40 that stores the fuel, the low-pressure fuel pump 42 that pumps the fuel in the fuel tank 40, and the low-pressure fuel pump 42. A fuel filter 44 for filtering the fuel, a pressure regulator 46 for making the pressure applied by the low-pressure fuel pump constant, a high-pressure fuel pump 48 for pressurizing the fuel pumped from the low-pressure fuel pump 42, and pressurization by the high-pressure fuel pump 48 A fuel pressure sensor 50 for detecting the pressure of the injected fuel, an injector 52 as a fuel injection valve for injecting fuel pressurized by the high-pressure fuel pump 48 into the combustion chamber 2a, and a pressure supplied to the injector 52 Relief that is a second fuel pressure adjusting means for returning the pressurized fuel to the upstream side of the high-pressure fuel pump 48 when the pressure exceeds a predetermined pressure. And a 54.

  Next, as shown in FIG. 1, the engine 1 has an intake side camshaft 60 and an exhaust side camshaft 62 at the upper part of the cylinder head. The intake side camshaft 60 and the exhaust side camshaft 62 rotate with the rotation of the camshafts 60, 62 to operate the intake valve 22 and the exhaust valve 26. An intake cam 64 and an exhaust cam 66 configured to open and close at a predetermined timing and to open and close the exhaust opening of the exhaust port 24 at a predetermined timing are provided.

  The engine 1 also has an intake cam angle sensor 68 that detects the rotational phase of the camshaft 60. The intake cam angle sensor 68 is an encoder, and is configured to output a timing pulse by one pulse every time the camshaft 60 rotates by a predetermined unit angle.

  The engine 1 also has a variable valve timing mechanism 70 that changes the phase of the opening / closing timing of the intake valve 22. The variable valve timing mechanism 70 will be described with reference to FIGS. FIG. 2 is a partially sectional side view showing a configuration of a variable valve timing mechanism of an engine provided with a control device according to an embodiment of the present invention, and FIG. 3 is a variable valve of the engine provided with a control device according to an embodiment of the present invention. It is a front view which shows the structure of a timing mechanism.

As shown in FIG. 2, the variable valve timing mechanism 70 is provided at one end of the intake camshaft 60.
The variable valve timing mechanism 70 includes a rotatable case 72, a rotating body 74 fastened and fixed to one end portion of the intake camshaft 60 with a bolt, an electric motor 76 fixed to the case 72, an intake air A predetermined rotation amount of the electric motor 76 is rotated so that the valve 22 is advanced or retarded by a predetermined valve timing amount (hereinafter referred to as “VVT advance angle (amount)” or “VVT delay angle (amount)”). 74, a power transmission mechanism (not shown) for transmitting to 74, and the like.
The power transmission mechanism holds the sun gear of the external gear, the ring gear of the internal gear arranged concentrically with the sun gear, and the pinion gear meshing with the sun gear and the ring gear so as to rotate and revolve. A gear mechanism having a carrier as a rotating element.

  As shown in FIG. 3, an annular sprocket 80 formed with teeth engageable with a timing chain 78 driven by the crankshaft 8 is provided on the outer peripheral surface of the case 72, and the rotational power of the crankshaft 8 is The casing 72, the electric motor 76, the power transmission mechanism, and the rotating body 74 are transmitted to the intake camshaft 60.

  Next, a protrusion 72 a and a protrusion 72 b that protrude in the axial direction of the intake camshaft 60 are provided on the inner peripheral surface of the case 72. The protrusion 72 a is provided on the advance side with respect to the intake side camshaft 60, and the protrusion 72 b is provided on the retard side with respect to the intake side camshaft 60. On the other hand, on the outer peripheral side of the rotator 74, a protrusion 82 protruding in the radial direction is provided.

  The rotating body 74 is formed to be rotatable relative to the case 72 via the power transmission mechanism by the operation of the electric motor 76, and is configured to be able to change the valve timing at which the intake valve 22 opens and closes. That is, for example, when the electric motor 76 is operated so that the rotating body 74 rotates relative to the case 72 relative to the case 72 as indicated by an arrow A in FIG. The phase with respect to the rotation of the shaft 8 can be delayed to retard the intake valve 22. The position where the protrusion 82 and the protrusion 72b abut is the most retarded position.

Next, an engine control apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram showing a schematic configuration of the engine control apparatus according to the embodiment of the present invention.
As shown in FIG. 4, the engine 1 according to the present embodiment includes an engine control unit (ECU) 90 that controls the engine 1 based on detection signals of the sensors. Specifically, the engine control unit 90 includes a microprocessor, a memory, a program for operating them, and the like (not shown), and controls valve timing at which the intake valve 22 opens and closes under predetermined conditions. Furthermore, a VVT advance / retard angle control means 92 for controlling the electric motor 76 of the variable valve timing mechanism 70, and a throttle valve opening degree control means 94 for controlling the opening degree of the electronically controlled throttle valve 16 under predetermined conditions. Have.

  The engine control unit 90 includes values of the air temperature and the air amount in the intake passage 13 detected by the intake air temperature / flow rate sensor 14, the value of the throttle opening detected by the throttle valve opening sensor 18, and a crank angle sensor. The value of the rotational speed of the crankshaft 8 detected by the engine 36, the value of the engine water temperature detected by the engine water temperature sensor 38, and the valve timing advance amount or retard amount of the intake valve 22 detected by the intake cam angle sensor 68. Each value is entered. The engine control unit 90 is configured to control the electric motor 76 and the electronically controlled throttle valve 16 by the VVT advance / retard angle control means 92 and the throttle valve opening degree control means 92 based on these values. Yes.

  Next, the control contents of the engine control apparatus according to the embodiment of the present invention will be described with reference to FIGS. FIG. 5 is a flowchart showing a control flow of control executed by the engine control apparatus according to the embodiment of the present invention, and FIG. 6 is a diagram for explaining calculation contents executed in the control flow of FIG. FIG. 7 is a diagram showing the effective compression ratio limit / VVT advance limit with respect to the intake manifold pressure / limit air amount and effective compression ratio / VVT actual phase, and FIG. 8 is a diagram at the time of transition from idling to off-idling. FIG. 9 is a diagram showing the actual VVT advance amount and the target VVT advance amount for explaining the response delay of the actual VVT delay angle, and FIG. 9 shows the throttle opening and the intake manifold pressure at the time of transition from idle to off-idle. 10 is a diagram showing a target air amount for explaining an example of a calculation result executed in the control flow of FIG. 5, and FIG. 11 is a control flow of FIG. Control performed Is a diagram showing an intake manifold pressure for explaining an example of a fruit. In FIG. 5, S indicates each step.

  In the following, in the control of the engine control device according to the embodiment of the present invention, when the driver depresses the accelerator when the vehicle is stopped, and the engine speed starts to increase from the idling state (transition from idle time to off-idle time). An example applied to the case) will be described.

  First, as shown in FIG. 5, in S1, the VVT is retarded from the idle time to the off-idle time. That is, in the present embodiment, when the throttle opening is raised by the throttle operation by the driver, in order to suppress the pre-ignition, the VVT advance amount (hereinafter, “VVT advance amount” in the present embodiment is the “maximum advance amount”). The target is set so as to be retarded as shown in FIG. 6 (target VVT advance angle indicated by a broken line in FIG. 6), and such target VVT advance angle is assumed. Is controlled to control the electric motor 76 of the variable valve timing mechanism 70. The target VVT advance amount is determined from the target torque in the engine operating state at the present time.

Here, the characteristics of the variable valve timing mechanism 70 of the present embodiment when the control of S1 is performed will be described with reference to FIG. 6, and as a comparative example, the control by the engine control device of the present embodiment (FIG. 5) is performed. The fact that pre-ignition is likely to occur when not executed will be described with reference to FIG.
As described above, in S1, the target is set so that the VVT advance amount is retarded as shown in FIG. 6, and the electric motor 76 is controlled to obtain such a target VVT advance angle. As shown by the actual VVT advance angle indicated by the broken line in FIG. 6, a response delay occurs in the VVT delay angle, and the closing timing of the intake valve 22 becomes earlier than the target timing. With such a response delay, as shown in FIG. 7, the response of the intake pressure in the intake passage 13 (hereinafter referred to as “in manifold pressure”) increases as the opening of the throttle valve 16 increases. 6 and pre-ignition occur in the time range as indicated by A in FIG. 7 or are likely to occur. The throttle opening diagram shown in FIG. 7 is the throttle opening corresponding to the driver's accelerator request. In the control by the engine control apparatus according to the present embodiment (FIG. 5), the processing after S2 is executed as follows so as to suppress such pre-ignition of the time range A.

Returning to the description of the control contents of the engine control apparatus according to the present embodiment.
After delaying the VVT in S1, an effective compression ratio limit at the current engine operating state, more specifically, the current crank angle is calculated in S2. The effective compression ratio limit in the present embodiment is a limit of an effective compression ratio at which pre-ignition does not occur.
As shown in FIG. 8A, the effective compression ratio limit (y) is calculated using an intake compression pressure (x) as a variable and using an effective compression ratio limit polynomial model.

The details of this calculation will be specifically described.
First, an effective compression ratio limit polynomial model is a model (y = f (x)) represented by a quadratic expression such as “effective compression ratio (y) = ax ² + bx + c” when expressed most simply. In this model, the variable x is the intake manifold pressure, and a, b, and c are constants. The quadratic model that is actually used is a more complex equation to more accurately predict the effective compression ratio limit. As shown in FIG. 8 (a), the fuel injection timing, the engine speed, the in-cylinder temperature when the intake valve is closed, and the fuel octane number are substituted for the constant.

As the fuel injection timing, the value of the fuel injection timing corresponding to the engine operating state at the time of the processing of S2 is output from the engine control unit 90 and substituted as a constant of the above model.
As the engine speed, the value detected by the crank angle sensor 36 at the time of processing of S2 is substituted as a constant of the model.
The in-cylinder temperature is estimated from the air temperature in the intake passage 13 detected by the intake air temperature / flow rate sensor 14 and the value of the engine water temperature detected by the engine water temperature sensor 38 at the time of the processing of S2. Assigned as a constant. Note that the time when the intake valve is closed is detected by the intake cam angle sensor 68.
As the octane number of the fuel, the octane number learned in the memory of the engine control unit 90 is substituted as a constant of the above model.

  The calculation result by S2 is obtained as a relationship between the intake manifold pressure (x) and the effective compression ratio (y) as shown in FIG.

Next, proceeding to S3, the VVT advance limit is calculated. The VVT advance limit in the present embodiment is a limit of the VVT advance amount in which pre-ignition does not occur.
In S3, the VVT advance limit of the variable valve timing mechanism 70 is calculated based on the limit effective compression ratio calculated in S2. That is, the VVT advance limit is calculated from the relationship between the early closing timing of the intake valve 22 due to the increase in the VVT advance amount of the variable valve timing mechanism 70 and the accompanying increase in the effective compression ratio. The VVT advance limit calculated in S3 is also a quadratic curve similar to the limit effective compression ratio limit calculated in S2, as shown in FIG.

  Next, in S4, it is determined whether or not the target VVT advance amount described above is larger than the VVT advance limit calculated in S3. If it is determined that the target VVT advance amount is larger than the VVT advance limit calculated in S3, the process proceeds to S5, and the target VVT advance amount set in S1 is set to the VVT advance limit calculated in S3. Limit to. That is, in S5, the target VVT advance amount is set so that the VVT advance amount does not become a VVT advance amount that causes pre-ignition, and the variable valve timing mechanism 70 is set so as to obtain such a VVT advance amount. The electric motor 76 is controlled.

  Next, after the processing of S5 is performed, or when it is determined in S4 that the target VVT advance angle amount is equal to or less than the VVT advance limit calculated in S3, the process proceeds to S6 and the current VVT advance angle is determined. It is determined whether or not the amount is larger than the VVT advance limit calculated in S3. If it is determined in S6 that the current VVT advance amount is larger than the VVT advance limit calculated in S3, the process proceeds to S7 to calculate the limit intake manifold pressure.

The calculation of the limit intake manifold pressure in S7 will be specifically described with reference to FIG. 8B and FIG.
In S7, the current VVT advance amount is calculated based on the valve closing timing of the intake valve 22 detected by the intake cam angle sensor 68, and is set as a variable y. And the intake manifold pressure x is calculated | required with the inverse function "x = g (y)" of the effective compression ratio limit polynomial model (quadratic expression) used by S2. The limit intake manifold pressure may be calculated using the current effective compression ratio as the variable y. Here, since the intake manifold pressure is calculated from the current VVT advance amount y using the inverse function of the effective compression ratio limit polynomial model, the calculated intake manifold pressure x is the pre-ignition at the current time. It is the limit intake manifold pressure that does not occur.

  The process of S7 will be described with reference to FIG. As described above, in S2 and S3, the effective compression ratio limit polynomial model is used to obtain a quadratic curve of effective compression ratio limit / VVT advance limit as shown in FIG. As indicated by the broken line 9, the limit intake manifold pressure is calculated from the current VVT advance amount y for the quadratic curve of the VVT advance limit.

Here, the inverse function (x = g (y)) of the effective compression ratio limit polynomial model will be described as corresponding to the simplest quadratic expression described above, “ax ² + bx + (cy) = φ”. The intake manifold pressure x (“x = (− b ± √ (b ² −4ac)) / 2a”) is obtained by substituting the value of the effective compression ratio y into this equation. As mentioned above, this is the simplest example because the quadratic model that is actually used uses a more complex equation to more accurately predict the effective compression ratio limit. The values assigned to the constants a, b, and c are the same as those described in S2.

  After the limit intake manifold pressure is calculated in S7, the process proceeds to S8, and the limit air charging efficiency (intake negative pressure) Ce corresponding to the limit intake manifold pressure calculated in S7 is calculated. Here, under the same VVT advance amount, the intake negative pressure Ce (the air filling rate per rotation obtained by dividing the air amount by the engine speed) is proportional to the intake manifold pressure. Using such a proportional relationship, the limit air charging efficiency is calculated according to the current VVT advance amount.

  After the limit air charging efficiency is calculated in S8, the process proceeds to S9, and the opening degree of the electronic control throttle valve 16 is limited so that the air charging efficiency is equal to the limit air charging efficiency.

And the process of S1-S9 is repeated.
By repeating the processing of S1 to S9, in S8, as shown in FIG. 10, the limit air filling efficiency corresponding to the crank angle is calculated, and in accordance with such limit air filling efficiency as shown in FIG. The opening degree is adjusted, and the opening degree of the electronic control throttle valve 16 is controlled as shown in FIG. 11, and a response of the intake manifold pressure as shown in FIG. 11 is obtained accordingly.

  That is, when the response of the VVT delay is delayed as described above by repeating the processing of S1 to S9, and when the driver's accelerator request causes pre-ignition, for example, from idling to off-idling When starting the vehicle at a low speed or when driving at low speed, the electronic control throttle valve 16 is set so that the air charging efficiency obtained by the opening degree of the electronic control throttle valve 16 becomes the limit air charging efficiency. It is controlled to open gradually. That is, without limiting the throttle opening uniformly, the limit effective compression ratio is always set when the engine crank angle rotates according to the operating state of the engine 1 and the VVT retarded state of the variable valve timing mechanism 70. The processes of S1 to S9 such as obtaining are repeatedly executed to adjust the throttle opening to obtain the intake manifold pressure. As shown in FIG. 11, the opening degree of the electronically controlled throttle valve 16 is controlled so that the response of the intake manifold pressure is suppressed in the region A where pre-ignition occurs.

  In the present embodiment, basically, by repeating the processes of S1 to S9 until the VVT response delay disappears (at the time of catching up with the target VVT), the pre-ignition is performed as shown by the solid line arrows in FIG. The effective compression ratio is lowered, that is, the VVT retardation is performed so as not to enter the region where it occurs. On the other hand, as shown by a two-dot chain line arrow in FIG. 9, when the control according to the prior art or this embodiment is not performed, the response of the intake manifold pressure to the throttle opening as described in FIG. 7. Quickly enters the pre-ignition generation region.

  In addition, although the above-mentioned control content mainly demonstrated the case where it delays VVT at the time of off-idle from idling at the time of start, the engine control apparatus by this embodiment becomes low engine speed after start. The present invention is also applicable to the case where the VVT is retarded when the driver steps on the accelerator.

Next, main functions and effects of the engine control apparatus according to the embodiment of the present invention will be described.
According to the present embodiment, the limit air amount at which pre-ignition occurs is calculated based on the detected VVT advance amount (actual phase of VVT) at the time of transition from idle time to off-idle time. Since the opening degree of the throttle valve 16 is limited so that the actual air amount does not increase beyond the limit air amount, the occurrence of pre-ignition in the period A accompanying the VVT response delay can be suppressed (FIGS. 6 and 7). FIG. 11).

  In addition, according to the present embodiment, the opening degree of the throttle valve 16 is limited so that the actual air quantity does not increase beyond the calculated limit air quantity. The throttle valve can be opened as quickly as possible while suppressing the occurrence of ignition to ensure the startability of the vehicle. In other words, if the throttle opening is uniformly smoothed, the throttle valve closes and the startability is sacrificed even if there is a sufficient amount of air to generate pre-ignition. Depending on the state, the calculation process is repeated each time, and the opening degree of the throttle valve 16 is limited so that the actual air amount does not increase beyond the limit air amount corresponding to the operation state. I can do it.

  Further, according to the present embodiment, since the opening degree of the throttle valve 16 is set so as not to exceed the limit air amount at which pre-ignition occurs even at a low engine speed, the transition from idling to off-idling is performed. Also, the occurrence of pre-ignition can be suppressed even during low rotation after the vehicle has started.

  Further, according to the present embodiment, the effective compression ratio polynomial model is used to calculate the limit effective compression ratio limit where pre-ignition occurs from the detected intake manifold pressure (actual intake manifold pressure), and further, the effective compression ratio polynomial model Using the inverse function, the limit air amount that causes pre-ignition is calculated from the detected VVT advance amount (actual phase of VVT), so even if the response of the actual VVT retard is delayed from the target VVT retard (VVT delay) In the case of trying to make an angle, the actual VVT advance amount controlled by the electric motor 76 (the advance amount with respect to the most retarded position) has a response delay with respect to the target VVT advance amount). In particular, it is possible to determine the limit air amount at which pre-ignition occurs.

1 Multi-cylinder direct injection engine 14 Intake temperature / flow rate sensor 16 Electronically controlled throttle valve 18 Throttle valve opening sensor 36 Crank angle sensor 38 Engine water temperature sensor 68 Intake cam angle sensor 70 Variable valve timing mechanism 76 VVT advance angle of variable valve timing mechanism Or VVT retarding electric motor 90 Engine control unit 92 VVT advance / retard control means 94 Throttle valve opening control means

Claims (3)

An engine control device having a variable valve timing mechanism that makes an intake valve VVT retarded or VVT advanced to vary its opening and closing timing,
VVT retard control means for causing the variable valve timing mechanism to advance the VVT at the time of idling and retarding the VVT from the VVT advance position at the time of off idling;
VVT advance angle limit calculating means for calculating an effective compression ratio limit where pre-ignition occurs and calculating a VVT advance limit amount based on the effective compression ratio limit;
Target VVT advance amount setting means for setting a target VVT advance amount of the variable valve timing mechanism at the time of transition from idle time to off-idle time;
VVT advance limit amount that limits the target VVT advance amount to the VVT advance limit amount when the target VVT advance amount is larger than the VVT advance limit amount during the transition from idle to off-idle. Control means, and
At the time of transition from idling to off-idling, the VVT retard control means is limited by the target VVT advance amount set by the target VVT advance amount setting means or the VVT advance limit control means. The variable valve timing mechanism is controlled so that the VVT advance limit amount is obtained,
The engine control means is further configured to change the actual VVT advance amount from the target VVT advance amount at the time of transition from idling to off-idle and by control of the variable valve timing mechanism by the VVT retard control means. Or when the actual VVT advance amount is larger than the VVT advance limit amount until the actual VVT advance amount reaches the limited VVT advance limit amount, the VVT at the time of the transition First limit air amount calculation means for calculating a limit air amount at which pre-ignition occurs based on the actual phase of
And a first throttle valve opening setting means for setting the throttle valve opening so that the actual air amount does not increase beyond the calculated limit air amount. Further, a second limit air amount calculating means for calculating a limit air amount at which pre-ignition occurs based on the actual phase of VVT at the time of low rotation,
The engine control device according to claim 1, further comprising second throttle valve opening setting means for setting the throttle valve opening so that the actual air amount does not increase beyond the calculated limit air amount.   The calculation of the pre-ignition limit air amount by the first limit air amount calculating means and / or the second limit air amount calculating means starts with effective compression in which pre-ignition is generated from the actual intake manifold pressure using a predetermined polynomial model. The ratio limit is calculated, and then the limit intake manifold pressure is calculated from the actual phase of VVT that is equivalent to the actual effective compression ratio, using the inverse function of the predetermined polynomial model. The engine control device according to claim 1 or 2, wherein a limit air amount at which the pre-ignition occurs is calculated.

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