JP6730779B2 - Engine controller - Google Patents

Description

The present invention relates to an engine control device, and more particularly to an engine control device having a compression ratio variable mechanism and a supercharger that does not have a delay in rising of the boost pressure.

There is a vehicle equipped with an engine equipped with a variable compression ratio mechanism and a turbocharger having a delay in rising boost pressure (see Patent Document 1).

JP, 2011-21524, A

By the way, it is assumed that the vehicle of Patent Document 1 described above is changed from a turbocharger having a delay in rising of the boost pressure to a turbocharger having no delay in rising of the boost pressure. When the response time from the supercharger drive to change the supercharging pressure from the pre-acceleration state to the post-acceleration state is shorter than the response time from the compression ratio to the post-acceleration state. It is conceivable that new knocking will occur.

Therefore, the present invention provides a response time until the supercharging pressure changes from the state before acceleration to the state after acceleration when the supercharger is driven, and the response time until the compression ratio changes from the state before acceleration to the state after acceleration. An object of the present invention is to provide a device that can avoid knocking even in a shorter case.

The engine control device of the present invention includes a supercharger that supercharges intake air , a compression ratio variable mechanism, an actuator of the compression ratio variable mechanism, a required compression ratio setting means, and an actuator control means . The control device for the engine is configured such that the response time until the supercharging pressure changes from the state before acceleration to the state after acceleration by driving the supercharger is It is shorter than the response time to reach the state. Further, the engine control device includes a road information acquisition unit, an acceleration prediction unit, and a pre-acceleration compression ratio reduction processing unit. The compression ratio variable mechanism can change the compression ratio of the engine. The required compression ratio setting means sets the required compression ratio such that the compression ratio is relatively high on the low load side and relatively low on the high load side according to the engine operating conditions. The actuator control means controls the actuator so that the required compression ratio is set. The supercharger supercharges intake air. The track information acquisition means acquires information on a track on which the vehicle is scheduled to travel. The acceleration predicting means uses the traveling road information acquiring means to predict whether or not acceleration from a low load state to a high load state will be performed on a traveling road from now on. When the pre-acceleration compression ratio reduction processing means predicts that acceleration from a low load state to a high load state will be performed on the road going from here, the actuator is driven to compress from the compression ratio when the acceleration is predicted. The ratio is lowered beforehand.

As a result, the response time until the supercharging pressure changes from the pre-acceleration state to the post-acceleration state by driving the supercharger changes from the pre-acceleration state to the post-acceleration state when the compression ratio is driven by the actuator. Even if it is shorter than the response time up to, knocking can be avoided.

It is a schematic block diagram of the engine control apparatus of 1st Embodiment of this invention. It is a schematic block diagram of a compression ratio variable mechanism. It is a posture figure of each link in a high compression ratio position and a low compression ratio position. It is a characteristic view of a target intake air amount. It is a flow chart for explaining calculation of an ignition timing command value. It is a characteristic diagram of basic ignition timing. It is a timing chart which shows a change when accelerating from a low load state to a high load state. It is a schematic block diagram of VICS (trademark). 9 is a flowchart for explaining calculation of a time required to reduce the compression ratio at the timing at which the predicted acceleration is performed and the actual compression ratio to the compression ratio V3 at the timing at which the predicted acceleration is performed. It is a characteristic view of a required engine torque. It is a characteristic view for explaining learning of a required engine torque. It is a characteristic view of a required compression ratio. It is a characteristic diagram of a required supercharging pressure. It is a flow chart for explaining the compression ratio reduction processing before acceleration. It is a flow chart for explaining acceleration processing. It is a characteristic diagram of a required supercharging pressure. FIG. 6 is a characteristic diagram showing a change in compression ratio when a vehicle equipped with the engine of the present embodiment is run.

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

(First embodiment)
FIG. 1 is a schematic configuration diagram of a control device for an engine 1 according to a first embodiment of the present invention. The engine 1 is mounted on a vehicle (not shown).

In FIG. 1, an intake passage 23 and an exhaust passage 24 are opened in a combustion chamber 21 of the engine 1. An intake valve 25 is provided at an opening end of the intake passage 23 to the combustion chamber 21, and an exhaust passage 24 is opened to the combustion chamber 21. An exhaust valve 26 is provided at the end.

The intake passage 23 is provided with a throttle valve 29 (throttle valve device) whose opening is controlled by an actuator 30 such as a motor. Further, a throttle sensor 31 for detecting the actual opening degree of the throttle valve is provided.

A fuel injection valve 33 is provided at the intake port of the intake passage 23, and a spark plug 34 is provided at the ceiling of the combustion chamber 21. A fuel injection amount that obtains a target air-fuel ratio is calculated based on the intake air amount detected by the air flow meter 38, and this injection amount of fuel is injected and supplied from the fuel injection valve 33 at a predetermined time, and is injected into the combustion chamber 21. The formed air-fuel mixture is ignited by the spark plug 34 at a predetermined time. The fuel injection valve 33 may be provided so as to face the combustion chamber 21.

The engine 1 is provided with a compression ratio variable mechanism capable of continuously changing the compression ratio of the engine. This engine provided with a variable compression ratio mechanism was previously proposed by the present applicant, and is known, for example, from Japanese Patent Laid-Open No. 2001-227367. Therefore, only the outline of the compression ratio variable mechanism will be described with reference to FIG.

In FIG. 2, a crankshaft 2 is provided with a crank journal 3 rotatably supported by a main bearing (not shown) in a cylinder block 1 forming a part of an engine body for each cylinder. The axis O of each crank journal 3 coincides with the axis (rotation center) of the crankshaft 2, and constitutes a rotating shaft portion of the crankshaft 2.

The crankshaft 2 also has a crankpin 4, a crank arm 4a, and a counterweight 4b. The crank pin 4 is provided eccentrically from the axis O for each cylinder. The crank arm 4 a connects the crank pin 4 to the crank journal 3. The counterweight 4b is arranged on the side opposite to the crankpin 4 with respect to the axis O, and mainly reduces the rotational primary vibration component of piston movement. The crank arm 4a and the counterweight 4b are integrally formed in this embodiment.

The piston 9 slidably fitted to the cylinder 10 formed for each cylinder and the crank pin 4 are mechanically linked by a plurality of link members, that is, the upper link 6 and the lower link 5. ing. The upper end side of the upper link 6 is fitted onto the piston pin 8 fixedly provided on the piston 9 so as to be relatively rotatable around the axis Oc. Further, the lower end side of the upper link 6 and the one main body 5a of the lower link 5, which is substantially bisected, are connected to each other by a connecting pin 7 that is inserted through the two so as to be relatively rotatable around the axis Od.

The lower link 5 is configured by attaching two main bodies 5a and 5b so as to hold the crank pin 4, and is mounted so as to be rotatable relative to the crank pin 4 and the axis Oe at the holding portion. There is. The other lower link body 5b and the upper end side of the control link (third link) 11, which are substantially bisected, are connected to each other by a connecting pin 12 that penetrates them so as to be relatively rotatable around the axis Of.

The lower end side of the control link 11 is externally fitted and supported by a control shaft 13 having an eccentric cam portion 14 rotatably supported by the cylinder block 1 so as to be swingable around its axis Ob. That is, the eccentric cam portion 14 is rotatably provided on the outer periphery of the control shaft 13, and the shaft center Oa of the eccentric cam part 14 is eccentric to the shaft center Ob of the control shaft 13 by a predetermined amount. The eccentric cam portion 14 is rotationally controlled by a compression ratio control actuator 16 via a worm gear 15 in accordance with the operating state of the engine, and is held at an arbitrary rotational position. It is preferable to use an electric motor as the actuator 16. It is preferable to use an SRM (Switched Reluctance Motor) as the electric motor when operation under high temperature conditions is necessary, and an IPM (Interior Permanent Magnet) motor when high torque is required as the electric motor load.

With such a configuration, the piston 9 moves up and down in the cylinder 10 via the crank pin 4, the lower link 5, the upper link 6, and the piston pin 8 as the crankshaft 2 rotates. The control link 11 connected to the lower link 5 swings around the swing axis Ob on the lower end side as a fulcrum.

Further, by controlling the rotation of the eccentric cam portion 14 by the compression ratio control actuator 16, the shaft center Ob of the control shaft 13 serving as the swing shaft center of the control link 11 is moved around the shaft center Oa of the eccentric cam portion 14. That is, the rotation center position Ob of the control link 11 moves with respect to the engine body (and the crankshaft rotation center O). As a result, the stroke of the piston 9 changes, and the compression ratio of each cylinder of the engine is variably controlled. For reference, FIG. 3 schematically shows the postures of the three links 6, 5, 11 at the piston top dead center position. The left side of FIG. 3 is the high compression ratio position, and the right side of FIG. 3 is the low compression ratio position. Of each link posture.

The greatest feature of this compression ratio variable mechanism is that the top dead center position (combustion chamber volume) of the piston 9 can be changed by controlling the angular position of the control shaft 13, and exhibits a function as a so-called compression ratio variable mechanism. In the present embodiment, the multi-link type compression ratio variable mechanism has been described, but the compression ratio variable mechanism is not limited to the multi-link type. For example, the actual compression ratio can be changed by changing the closing timing of the intake valve.

It is generally known that increasing the compression ratio improves the thermal efficiency of the engine. On the other hand, if the compression ratio is increased too much, knocking will occur, so that the compression ratio cannot be increased particularly in the high load region. Therefore, in the engine 1 having the variable compression ratio mechanism, the required compression ratio is set large on the low load side and small on the high load side as shown in FIG. 12, so that knocking does not occur. Improves fuel consumption.

Returning to FIG. 1, the engine 1 further includes an electric assist turbocharger 45. The electric assist turbocharger 45 includes an exhaust turbine 46, a compressor 47, a shaft 48 that coaxially connects these, and a motor generator 49. The motor generator 49 is driven by a signal from the engine controller 35.

For example, when accelerating from a low speed running state, the motor generator 49 is driven as a motor to drive the exhaust turbine 46. As a result, even when the exhaust energy of the engine is low in the initial stage of acceleration, the intake turbine 47 can be sufficiently supercharged by increasing the exhaust turbine rotation speed by driving the motor. As a result, the supercharging delay in seconds called turbo lag is eliminated, and the responsiveness of the engine output to the accelerator opening (accelerator pedal operation amount) is improved.

A normally closed wastegate valve 52 is provided in a passage 51 that bypasses the exhaust turbine 46. The waste gate valve 52 bypasses the exhaust gas when it becomes equal to or higher than the set supercharging pressure and releases the exhaust gas so that the supercharging pressure does not exceed the set supercharging pressure. A supercharging pressure sensor 39 for detecting an actual supercharging pressure is provided in the intake passage 23 upstream of the throttle valve 29.

When the electric assist turbocharger 45 is further provided to the engine 1 having the variable compression ratio mechanism as described above, the required compression ratio is determined differently from the naturally aspirated engine as follows. That is, since the target intake air amount tQac during natural intake is determined as shown in FIG. 4 according to the accelerator opening APO and the engine rotation speed Ne, the ratio between the atmospheric pressure Pa and the actual supercharging pressure rPb is determined. The target intake air amount tQac during this natural intake is corrected. That is, the supercharging pressure correction target intake air amount tQac, which is the target intake air amount during supercharging, is calculated by the following equation. h is calculated.

tQac h=tQac×Pa/rPb (1)
In the state of natural intake without the turbocharger 45, the value of Pa/rPb, which is the fraction on the right side of the equation (1), becomes 1, and the boost pressure correction target intake air amount tQac h matches the target intake air amount tQac. On the other hand, since the actual supercharging pressure rPb is larger than the atmospheric pressure Pa when the turbocharger 45 operates, the value of Pa/rPb, which is a fraction on the right side of the equation (1), becomes a positive value smaller than 1. Supercharging pressure correction target intake air amount tQac h becomes smaller than the target intake air amount tQac. Thus, during supercharging, the boost pressure correction target intake air amount tQac The reason why h is set to be smaller than the target intake air amount tQac is that intake air excessively enters the combustion chamber 21 during supercharging as compared with natural intake because the intake pressure is higher than atmospheric pressure. .. That is, if an intake air amount that exceeds the target intake air amount tQac flows into the combustion chamber 21, the pressure and temperature inside the combustion chamber 21 will rise correspondingly, and knocking may not occur. Therefore, during supercharging, the intake air amount (tQac) is smaller than the target intake air amount tQac that is suitable for natural intake. h) makes the actual intake air amount during supercharging the same as the actual intake air amount during natural intake. This prevents knocking.

To the engine controller 35, signals of an accelerator opening APO from an accelerator opening sensor 36, a rotation speed Ne from an engine rotation speed sensor 37, and an intake air amount Qa from an air flow meter 38 are input. The engine controller 35 calculates the target throttle valve opening, the required compression ratio, the fuel injection amount, and the ignition timing command value based on these signals. Then, the actuator 30 of the throttle valve 29 is driven so as to obtain the calculated target throttle valve opening, and the compression ratio control actuator 16 is driven so as to obtain the calculated required compression ratio. Further, the fuel injection valve 33 and the ignition plug 34 are controlled so that the calculated fuel injection amount and ignition timing command value are obtained.

The calculation of the ignition timing command value performed by the engine controller 35 will be briefly described. The flow of FIG. 5 is for calculating the ignition timing command value, and is executed for each predetermined crank angle position. Here, as the predetermined crank angle position, a position slightly ahead of the ignition timing is set in advance.

In step 1, the basic ignition timing ADV0 [degCA(BTDC)] at which the MBT is obtained is calculated by searching a map having the contents of FIG. 6 from the engine load and the engine rotation speed Ne. Although the contents of ADV0 are not shown in FIG. 6, a known example may be used.

In step 2, the knock level detected by the knock sensor 40 and the slice level are compared. If the knock level exceeds the slice level, it is determined that knock has occurred, and the routine proceeds to step 3.

In step 3, a value obtained by adding a predetermined value a[degCA] to the previous value "FBz" of the feedback amount FB is set as the current feedback amount FB[degCA], that is, the feedback amount FB[degCA] of the ignition timing is calculated by the following equation. ] Is calculated.

FB=FBz+a (2)
However, a: predetermined value (positive value),
FBz: Previous value of FB,
In step 7, the feedback amount FB is subtracted from the basic ignition timing ADV0, that is, the ignition timing command value ADV[degCA(BTDC)] is calculated by the following equation.

ADV=ADV0-FB (3)
Since the ignition timing command value ADV in equation (3) is a value measured from the compression top dead center to the advance side, subtracting the feedback amount FB from the basic ignition timing ADV0 is delayed by the feedback amount FB from the basic ignition timing ADV0. It means to correct to the corner side. The initial value of “FBz”, which is the previous value of the feedback amount FB in the above equation (3), is zero.

If the feedback amount FB is zero before knocking occurs, a predetermined value a is entered in FB at the timing when knocking occurs. That is, at the ignition timing immediately after the timing at which knocking occurs, the ignition timing retarded by the predetermined value a from the basic ignition timing ADV0 becomes the ignition timing command value.

If the basic ignition timing is retarded by the predetermined value a this time, knocking will not occur next time. At this time, since the knock level becomes less than the slice level in step 2, the process proceeds to step 4.

In step 4, the value obtained by subtracting the predetermined value b[degCA] (b<a) from the previous value "FBz" of the feedback amount FB is set as the current feedback amount FB[degCA], that is, the feedback amount FB according to the following equation. To calculate.

FB=FBz-b (4)
However, b: predetermined value (positive value),
FBz: Previous value of FB,
At the next timing of the ignition timing immediately after the timing at which knocking occurs, the value retarded by ab from the basic ignition timing ADV0 becomes the ignition timing command value ADV. Similarly, the feedback amount FB decreases to a-2b, a-3b, a-4b,... Each time the ignition timing is reached. Therefore, at step 5 when the feedback amount FB becomes a negative value, the process proceeds to step 6 and the feedback amount FB is set to zero. The ignition timing command value ADV returns to the basic ignition timing ADV0 at the timing when the feedback amount FB is set to zero.

Now, in a vehicle in which the engine 1 having the variable compression ratio mechanism is mounted and the electric assist turbocharger 45 is added, when the accelerator pedal is depressed to accelerate from the low load state to the high load state, knocking is newly generated. It is possible that This will be described with reference to the timing chart of FIG.

FIG. 7 shows, as a model, a change when the accelerator opening is stepwise changed from a predetermined value APO1 to a predetermined value APO2. Here, the target to be changed is the actual boost pressure, the ignition timing, the actual compression ratio, and the actual engine torque.

Here, the load state of the engine is roughly divided into a low load state, a medium load state, and a high load state. In the present embodiment, acceleration from a low load state to a high load state (hereinafter, also simply referred to as “acceleration”). .) is handled. The acceleration may be, for example, a case where the vehicle is accelerated from a general road, passing through a toll gate on the expressway, and joining the flow of the vehicle traveling on the main line on the expressway. The reason why acceleration from a low load state to a high load state is handled is as follows. That is, when the turbocharger 45 is driven, the response time from when the actual supercharging pressure changes from a low load state before acceleration to a high load state after acceleration, and when the compression ratio control actuator 16 is driven, the actual compression ratio is before acceleration. This is because the response time from the low load state to the high load state after acceleration greatly deviates.

In FIG. 7, the case of the current engine is shown by a one-dot chain line, the case of the engine of the comparative example is shown by a broken line, and the case of the engine of the first embodiment of the present invention is shown by a solid line. Hereinafter, the current engine, the engine of the comparative example, and the engine of the first embodiment will be described in this order.

First, it is assumed that the current engine is an engine that includes a variable compression ratio mechanism and a normal turbocharger that does not have a motor generator.

In the existing engine, the compression ratio of the engine 1 is controlled to a relatively high side in a normal region of the vehicle (when cruising in an urban area or a highway), and the fuel efficiency is improved by increasing the thermal efficiency. On the other hand, in the high output range (sudden acceleration or uphill running), the engine output is improved while avoiding knocking by switching to the side where the compression ratio is relatively low in order to perform supercharging.

Therefore, when the accelerator opening is stepwise changed in order to accelerate from the low load state to the high load state, the actual supercharging pressure is changed at the timing of t4 as shown by the dashed line in the second step of FIG. It changes from the predetermined value B1 to the higher side and reaches the predetermined value B2 at the timing of t8. Note that the change of the actual supercharging pressure is shown in the second stage of FIG. 7, but the actual supercharging pressure in the low load state and the required supercharging pressure in the low load state match, and It is assumed that the actual supercharging pressure and the required supercharging pressure in the high load state are the same.

On the other hand, when the accelerator opening is step-changed from the predetermined value APO1 to the predetermined value APO2 at the timing of t4, the actual compression ratio becomes the predetermined value at the timing of t4 as shown by the dashed line in the fourth row of FIG. It linearly decreases from V1 and reaches a predetermined value V2 at the timing of t9. Although the actual compression ratio changes in the fourth row of FIG. 7, the actual compression ratio in the low load state and the required compression ratio in the low load state match, and the actual compression ratio in the high load state is shown. It is assumed that the ratio and the required compression ratio in the high load state also match.

In this case, what is important is that the timing at which the actual boost pressure reaches the predetermined value B2 is t8, and the timing at which the actual compression ratio reaches the predetermined value V2 is t9, which are almost the same timing (t8 and t9). That is the point.

Here, the response period from the driving of the supercharger until the actual supercharging pressure changes from the predetermined value B1 in the low load state before acceleration to the predetermined value B2 in the high load state after acceleration (this response time will be referred to as "actual charging It is also referred to as the "pressure response time".) Tb1 is determined by the specifications of the current engine and a normal turbocharger. Further, when the compression ratio control actuator 16 is driven, the actual compression ratio is changed from a predetermined value V1 in a low load state before acceleration to a predetermined value V2 in a high load state after acceleration (this response time will be referred to as "actual compression" below). Also referred to as "ratio response time".) Tc1 is determined by the specifications of the compression ratio variable mechanism. Here, the response period Tc1 of the actual compression ratio, that is, the rate of decrease (the slope of the straight line) of the actual compression ratio is largely determined by the following three. That is, the specifications of the compression ratio control actuator 16, the gear ratio, and the link ratio.

As shown by the alternate long and short dash line in the third stage of FIG. 7, the ignition timing linearly advances from the predetermined value ADV01 at the timing of t4 to the predetermined value ADV02 at the timing of t8. ..

In the current engine, the response period Tb1 of the actual supercharging pressure due to the operation of the normal turbocharger and the response period Tc1 of the actual compression ratio are substantially equal to each other, so that knocking does not occur and an ideal level is achieved. To increase the engine torque (see the dashed line at the bottom of Fig. 7). Thus, there is no problem with the current engine, but the downsizing concept is in progress as a recent trend.

Here, the downsize concept is to use a turbocharger such as a turbocharger or a supercharger in an automobile to reduce the displacement while maintaining the same power performance as the current engine and to reduce fuel consumption during cruising. It is the engine design concept that improves the engine. Under this concept, it is conceivable to install an electric assist turbocharger to enhance the response of the turbocharger. Therefore, the engine provided with the electric assist turbocharger 45 as shown in FIG. 1 in place of the normal turbocharger of the current engine is a comparative engine. That is, the engine of the comparative example is an engine including the variable compression ratio mechanism and the electric assist turbocharger 45.

In the engine of the comparative example, in order to eliminate the turbo lag that occurs in a normal turbocharger, by driving the motor generator 49 as a motor at the start of acceleration, the exhaust turbine 46 is rotated from the acceleration start timing to force supercharging. Can be done automatically. As a result, the degree of increase in the actual supercharging pressure becomes larger than that in the case of the normal turbocharger of the current engine. Therefore, as shown by the broken line in the second stage of FIG. Reach B2.

However, even in the engine of the comparative example, the response time Tc1 of the actual compression ratio is the same as that of the current engine (see the broken line in the fourth stage of FIG. 7). Although the response time Tc1 of the actual compression ratio does not change, if the response time Tb2 of the actual boost pressure becomes shorter than the response time Tb1 of the actual boost pressure in the case of the current engine, the following problems occur. That is, in the engine of the comparative example, the combustion state in the combustion chamber 21 is improved by the amount of excess air compared to the current engine in the state where the actual compression ratio does not drop to the predetermined value V2, and self-ignition occurs. Accompanied knocking occurs.

In this case, in order to avoid knocking, the engine controller 35 performs feedback control of the ignition timing based on the knock sensor 40. That is, as indicated by the broken line in the third row of FIG. 7, the ignition timing command value ADV is retarded by the feedback amount FB (=predetermined value a) from the basic ignition timing ADV0 at the timing t5 when knocking occurs. Avoid knocking. After that, the ignition timing is gradually advanced with the feedback amount FB that decreases by a predetermined value b (b<a). As a result, the ignition timing command value ADV returns to the predetermined value ADV02 which is the basic ignition timing in the high load state at the timing of t7.

In the engine of the comparative example, while knocking is avoided in this way, the ignition efficiency is retarded due to the occurrence of knocking, so that the combustion efficiency in the combustion chamber 21 deteriorates. As a result, the engine torque increases from the predetermined value Tor1 and finally reaches the predetermined value Tor2, as shown by the broken line in the bottom of FIG. 7, but the engine torque temporarily decreases immediately after acceleration. If the engine torque temporarily rises immediately after acceleration and then the engine torque temporarily decreases, hesitation occurs in the vehicle, which deteriorates drivability.

In summary, the reason why knocking occurred in the engine of the comparative example is as follows. That is, while the response time Tb2 of the actual boost pressure becomes shorter than the response time Tb1 of the actual boost pressure in the case of the current engine, the response time Tc1 of the actual compression ratio is the same as that in the case of the current engine. Therefore, the actual compression ratio cannot follow the change of the actual supercharging pressure, and the actual compression ratio does not fall sufficiently to the actual compression ratio commensurate with the actual supercharging pressure.

Therefore, the inventor of the present invention has the following idea. That is, if it is possible to predict that acceleration will be performed on the road on which the vehicle is going, before the acceleration is performed, the actual compression ratio may be reduced in advance before the acceleration, so that the actual compression is performed from the predicted acceleration timing. Reduce the ratio without delay. In this case, it is possible to sufficiently reduce the actual compression ratio to match the actual supercharging pressure, and it is possible to suppress the occurrence of knocking. Hereinafter, the road on which the vehicle is heading will be simply referred to as "the road to head." In response to this, in the first embodiment of the present invention, when the response time of the actual supercharging pressure is shorter than the response time of the actual compression ratio, the traveling road information acquisition means is used to drive the road (the traveling road to which it is heading) Predict whether or not the acceleration from the low load state to the high load state will be performed. Here, the above-mentioned running road information acquisition means acquires information about the running road on which the vehicle is to travel. Then, when it is predicted that acceleration from the low load state to the high load state will be performed on the road going from here, the compression ratio control actuator 16 is driven to set the actual compression ratio in advance from the actual compression ratio when the acceleration is predicted. Lower.

A process of reducing the actual compression ratio in advance before the predicted timing of acceleration (hereinafter, referred to as “pre-acceleration compression ratio reduction process”) will be described with reference to FIG. 7. Here, the engine of the present embodiment is the same as the engine of the comparative example, that is, the engine including the variable compression ratio mechanism and the electric assist turbocharger 45. However, the compression ratio control method differs between the engine of the comparative example and the engine of the present embodiment.

In FIG. 7, knocking does not occur if the actual compression ratio has dropped to the predetermined value V2 at the timing of t6 when the actual supercharging pressure almost reaches the predetermined value B2. That is, as shown by the solid line in the fourth row of FIG. 7, it is necessary to advance the timing at which the actual compression ratio reaches the predetermined value V2 from the arrival timing (t9) in the engine of the comparative example to the timing of t6. There is.

Here, when the decreasing speed of the actual compression ratio, that is, the slope of the straight line is set to −Δ1 [/s] (Δ1>0), the predicted acceleration is started (performed) at the timing (t4) using the slope Δ1. ), the compression ratio V3 [unknown number] can be obtained by the following equation.

V3=V2+Δ1·(Tc1-Tb2) (5)
However, Tc1: actual compression ratio response time [s],
Tb2: Response time [s] of actual boost pressure,
Next, the time Tc2[s] required to reduce the actual compression ratio to the compression ratio V3 at the timing when the predicted acceleration starts from the predetermined value V1 can be calculated by the following equation using the slope Δ1.

Tc2=(V1-V3)/Δ1 (6)
However, in this embodiment, since the allowance margin Tyo [s] is provided, the time Tc3 [s required to reduce the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing when the predicted acceleration is started. ] Can be calculated by the following equation.

Tc3=(V1-V3)/Δ1+Tyo (7)
If the acceleration from t4 can be predicted before the timing of t2 before the required time Tc3 from the timing of the predicted acceleration of t4, the acceleration at which the actual compression ratio is predicted is started from the timing of t2. It is possible to reduce the compression ratio V3 to V3. As a result, the actual compression ratio is reduced to the compression ratio V3 at the timing when the predicted acceleration is started immediately before the time when the predicted acceleration is started at t4. In other words, when acceleration is performed as predicted at t4, the actual compression ratio can be reduced to the predetermined value V2 at the same timing as t6 when the actual boost pressure reaches the predetermined value B2.

Due to the variable compression ratio mechanism, the actual reduction ratio of the compression ratio (that is, the slope of the straight line) actually varies. The above margin Tyo is for absorbing the variation in the decreasing speed of the actual compression ratio. That is, by providing the margin allowance Tyo, even if there is variation in the reduction speed of the actual compression ratio, the compression ratio V3 at the timing at which the predicted acceleration of the actual compression ratio is surely performed immediately before the timing of t4 is matched. be able to.

In the present embodiment, as described above, since the actual compression ratio can be reduced to the predetermined value V2 at the same timing as the timing of t6 when the actual supercharging pressure reaches the predetermined value B2, knocking does not occur. Therefore, the ignition timing linearly moves to the retard side from the timing of t4 and reaches the predetermined value ADV02 at the timing of t6, as shown by the solid line in the third stage of FIG. As described above, when it becomes possible to avoid knocking, engine torque is generated according to the degree of increase of the actual boost pressure as shown by the solid line in the lowermost part of FIG. 7, and thereby quick acceleration is realized. You can

Next, in order to predict that acceleration will be performed from the timing of t4 before the timing of t2, in the present embodiment, an ITS (Intelligent Transportation System) as an example of the road information acquisition means is used. Here, ITS is a general term that refers to a series of systems that utilize IT (Information Technology) to contribute to the improvement of transportation efficiency and comfort of traffic. The system contained in the IT S, there are sophisticated the car navigation system.

Here, as an advanced car navigation system, there is a car navigation system compatible with VICS (Vehicle Information and Communication System). This VICS provides the driver with real-time information such as traffic congestion, regulatory information, parking lot fullness, etc. via a car navigation system. The VICS Center was established as the operating entity, and provides VICS services with three media: radio beacons, optical beacons, and FM multiplex broadcasting.

This will be specifically described. FIG. 8 is a schematic configuration diagram of the ITS 60 . The ITS 60 includes a navigation system 50 , a Japan road traffic information center 61, a VICS center 62, an optical beacon 64 1 , a radio wave beacon 63 3 , and an FM multiplex broadcast 65. Of these, the navigation system 50 mounted on the vehicle is composed of a GPS antenna 53, a GPS receiver 54, a direction sensor 55, a vehicle speed sensor 56, a navigation controller 57, a display 58, and map data 59.

Here, the GPS antenna 53 and the GPS receiver 54 are for receiving a radio wave from an artificial satellite to know the location of the vehicle (vehicle position). The own vehicle position can be basically known from the position information from the satellite. However, the azimuth sensor 55 and the vehicle speed sensor 56 are provided because there is an error only with the signal from the satellite and the position signal from the satellite cannot be received while traveling in the tunnel. The azimuth sensor 55 is for knowing the direction in which the vehicle is heading. The vehicle speed sensor 56 is for knowing the moving distance of the vehicle. The map data 59 stores information on whether the road is a slope or an expressway.

The navigation controller 57 collates the information from the GPS receiver 54 and the sensors 55 and 56 with the map data 59, and displays the position of the own vehicle on the map on the display 58, for example.

Furthermore, by connecting the navigation controller 57 and the engine controller 35 by CAN communication 71, the engine controller 35 is made to provide the navigation controller 57 with acceleration information of the vehicle. Then, the navigation history is stored in the navigation controller 57, which includes the road (running road) on which the acceleration is performed, the accelerator opening and the engine rotation speed when the acceleration is performed. For example, in the case where a vehicle travels on almost the same road to and from work and home, which of the multiple roads (including highways) used for commuting has been accelerated Or, if the distance of each road is long, the data on which section the acceleration is performed is saved as an acceleration history. In addition, at the time of acceleration, the amount of accelerator opening is saved as an acceleration history together with the engine rotation speed at that time.

Various kinds of information such as traffic jams, accidents, construction, main parking lots, etc. on general roads and expressways are collected by the Japan Road Traffic Information Center 61, and various kinds of information are transmitted to the VICS center 62. The VICS center 62 edits and processes various kinds of information, and then sends the edited and processed information to the radio wave beacon 63, the optical beacon 64, and the FM multiplex broadcast 65. Here, the above-mentioned radio wave beacon 63 is mainly grounded on a highway, and uses radio waves as a medium to provide necessary information to the installed location. The above-mentioned optical beacon 64 is mainly installed on a general road, and uses light (near infrared) as a medium to provide necessary information to the installed place. The above-mentioned FM multiplex broadcast 65 is provided to multiplex and provide information to FM broadcast (NHK), and the information can be used in all areas of broadcasting stations in various places.

If accelerating the vehicle to join the flow of vehicles traveling on the main road on the highway after traveling on the general road as described above, if it is repeated for commuting, at the time of commuting today The behavior of the vehicle can be known in advance by the navigation controller 57. For example, in FIG. 7, during the period from t1 to t2, whether or not acceleration will be performed on the road to which the vehicle is heading is predicted based on the acceleration history stored in the navigation controller 57. Then, when it is predicted that the acceleration will be performed from t4, the pre-acceleration compression ratio lowering process from t2 is performed.

This control performed by the engine controller 35 in cooperation with the navigation controller 57 will be further described with reference to the flowchart. The flowchart of FIG. 9 calculates the compression ratio V3 at the timing at which the predicted acceleration is performed, and the time Tc3 required to reduce the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing at which the predicted acceleration is performed. This is done for every fixed time (for example, every 10 ms).

In step 11, the V3 and Tc3 calculated flags (initially set to zero at startup) are checked. Here, it is assumed that V3 and Tc3 calculated flag=0, and the process proceeds to step 12 and subsequent steps.

In step 12, the navigation controller 57 is inquired whether or not acceleration from the low load state to the high load state (abbreviated as “acceleration scene with high load” in FIG. 9) is performed. Upon receiving this inquiry, the navigation controller 57 predicts whether or not the acceleration from the low load state to the high load state will be performed based on the acceleration history stored in the navigation controller 57. Then, the predicted result is returned to the engine controller 35. When the navigation controller 57 does not predict the acceleration from the low load state to the high load state, the current processing is ended.

When the navigation controller 57 predicts acceleration from the low load state to the high load state in step 12, the process proceeds to step 13. For example, if the driver uses a highway free of traffic during daily commuting, the navigation controller 57 may accelerate from a low load state to a high load state before entering a tollgate on the highway. Since it is predicted, the process proceeds from step 12 to step 13.

However, even if the highway is used for daily commuting, the highway used for commuting may be congested. In this case, whether or not the highway used for commuting is congested cannot be known from the acceleration history stored in the navigation controller 57. Even if the expressway is congested, it is assumed that acceleration from a low load state to a high load state is predicted, and the actual compression ratio may have been lowered before entering the toll gate on the expressway. The fuel efficiency will be returned and deteriorated in the period before passing the place and joining the main line of the highway. In this case, lowering the actual compression ratio ends up in vain.

Therefore, in step 13, the navigation controller 57 is inquired from the road traffic information (runway information) provided from the VICS center 62 ( ITS60 ) whether or not there is a traffic jam on the future highway. When the navigation controller 57 receives this inquiry, it confirms whether or not there is a traffic jam on the highway to be headed, based on the information from the VICS center. Then, the confirmed information is returned to the engine controller 35. When the navigation controller 57 obtains the information that there is a traffic jam on the future highway, it is determined that acceleration will not be performed on the future highway, and the current process is terminated.

On the other hand, in step 13, when the navigation controller 57 obtains the information that there is no traffic jam on the highway to which it is going, it proceeds to step 14 and subsequent steps. Steps 14 to 22 are parts for calculating the time Tc3 required to reduce the compression ratio V3 at the timing at which the predicted acceleration is performed and the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing at which the predicted acceleration is performed. Is.

First, in step 14, the actual (current) load state, that is, the actual compression ratio in the low load state is calculated as a predetermined value V1 [anonymous number]. The actual compression ratio in the low load state can be known from the command value issued to the compression ratio control actuator 16 by the engine controller 35.

In step 15, the actual (current) load state, that is, the actual supercharging pressure under the low load state is calculated as a predetermined value B1 [MPa]. The actual supercharging pressure in the low load state is detected by the supercharging pressure sensor 39.

In step 16, the navigation controller 57 is inquired about the accelerator opening APOri [unknown number] and the engine speed Neri [rpm] when the predicted acceleration is performed. When the navigation controller 57 receives this inquiry, the acceleration controller stores the accelerator opening APOri and the engine speed Neri at the time of acceleration for merging with the main line of the highway from the acceleration history stored in the navigation controller 57. read out. Then, the read out accelerator opening APOri and engine speed Neri are sent to the engine controller 35. The engine controller 35 calculates the required engine torque Tor2 [Nm] by searching a map having the contents shown in FIG. 10 from the sent accelerator opening APOri and engine speed Neri. The required engine torque Tor2 is an engine torque that will be obtained when the same acceleration as that in the acceleration history is performed because the vehicle joins the main line of the highway.

For example, it is assumed that the read accelerator opening APOri is a predetermined value APOri1 and the read engine rotation speed Neri is a predetermined value Neri1. At this time, as shown in FIG. 10, the required engine torque Tor21 [Nm] at the point where these two values APOri1 and Neri1 intersect is calculated.

The map value of the required engine torque according to the present embodiment is updated (learned) based on the acceleration history stored in the navigation controller 57. This will be described with reference to FIG. It is assumed that the map characteristic of the required engine torque shown in the upper left of FIG. 11 is the initial characteristic. The initial characteristic is a characteristic that is adapted when the vehicle is shipped from the factory. The required engine torque of the initial characteristic is defined as "basic required engine torque".

The way the accelerator pedal is pressed differs depending on the driver. If you are a driver who focuses on fuel efficiency, try not to push the accelerator pedal too much.
The accelerator opening at the time of acceleration is stored in the navigation controller 57 as an acceleration history together with the engine rotation speed at that time. However, if the driver does not press the accelerator pedal to a large extent in this way, acceleration is accelerated. The accelerator opening becomes relatively small when it is performed. In response to this point, the map characteristic of the required engine torque shifts to the map characteristic shown in the upper right of FIG. That is, in the characteristic shown in the upper right of FIG. 11, the engine torque line indicated by the solid line moves to a higher load side than the initial characteristic. For reference, the initial characteristic is shown by a broken line. According to the same characteristic indicated by the solid line, the required engine torque is lower than the basic required engine torque at the same accelerator opening APO and the same engine rotation speed Ne. By making an effort not to generate the engine torque in this way, the fuel economy will gradually improve.

On the other hand, if the driver emphasizes output, the driver often depresses the accelerator pedal greatly. If the driver frequently depresses the accelerator pedal, the accelerator opening degree when accelerating becomes relatively large, and this is stored as acceleration history data. In response to this point, the map characteristic of the required engine torque shifts to the map characteristic shown in the lower left of FIG. That is, in the characteristic shown in the lower left portion of FIG. 11, the engine torque line indicated by the solid line moves to the low load side from the initial characteristic. For reference, the initial characteristic is shown by a broken line. According to the same characteristic indicated by the solid line, the required engine torque is higher than the basic required engine torque at the same accelerator opening APO and the same engine rotation speed Ne. In this way, if the driver frequently depresses the accelerator pedal frequently, the engine torque output will gradually increase even if the accelerator pedal is depressed by the same amount.

In this way, by correcting the basic required engine torque according to the acceleration history, which is the history of the acceleration performed by the driver, the characteristics of the required engine torque will be adapted to the driver's intention.

Returning to the flow of FIG. In step 17, the required compression ratio is calculated by searching the map having the contents of FIG. 12 from the required engine torque Tor2 obtained in step 16 and the engine rotation speed Neri sent from the navigation controller 57. The value of the calculated required compression ratio is put in a predetermined value V2 [anonymous number].

In step 18, the required supercharging pressure is calculated by searching the map having the contents of FIG. 13 from the required engine torque Tor2 obtained in step 16 and the read engine rotation speed Neri. The calculated value of the required supercharging pressure is put in the predetermined value B2 [MPa].

These predetermined values V2 and B2 will be obtained when the same acceleration as that in the acceleration history is performed because the vehicle merges with the main line of the highway from now on, and the compression ratio in the high load state after acceleration and It is supercharging pressure.

For example, it is assumed that the calculated required engine torque is the predetermined value Tor21 and the engine rotation speed Neri sent from the navigation controller 57 is the predetermined value Neri1. At this time, as shown in FIG. 12, the required compression ratio V21 [anonymous number] at the point where these two values Tor21 and Neri1 intersect is calculated. Similarly, as shown in FIG. 13, the required supercharging pressure B21 [MPa] at the point where these two values Tor21 and Neri1 intersect is calculated.

In step 19, the response time Tb2 [s] of the actual supercharging pressure is calculated based on the predetermined value B1 obtained in step 15 , the predetermined value B2 obtained in step 18 , and the specifications of the turbocharger 45. For example, if the slope of the rise of the actual supercharging pressure is approximated by a predetermined value Δ2 (a positive value) from the specifications of the turbocharger 45, the response time Tb2[s] of the actual supercharging pressure is calculated by the following equation. You can

Tb2=(B2-B1)/Δ2 (8)
In step 20, the response time Tc1 [s] of the actual compression ratio is calculated based on the predetermined value V1 obtained in step 14 , the predetermined value V2 obtained in step 17 , and the specifications of the compression ratio variable mechanism. For example, if the rate of decrease of the compression ratio is set to −Δ1 (predetermined value Δ1>0) from the specifications of the variable compression ratio mechanism, the response time Tc1 [s] of the actual compression ratio can be calculated by the following equation.

Tc1=(V1-V2)/Δ1 (9)
In step 21, from the actual compression ratio response time Tc1, the actual boost pressure response time Tb2, the predetermined value V2, and the predetermined value Δ1, the compression ratio V3 at the timing (t4) at which the acceleration predicted by the following equation is performed Number] is calculated.

V3=V2+Δ1·(Tc1-Tb2) (10)
In step 22, the time Tc3 [s] required to reduce the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing when the predicted acceleration is performed is calculated by the following equation.

Tc3=(V1-V3)/Δ1+Tyo (11)
However, Tyo: allowance,
The allowance allowance Tyo is determined by conformity.

With this, since the time Tc3 required to reduce the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing at which the predicted acceleration is performed and the compression ratio V3 at the timing at which the predicted acceleration is performed are completed, In step 23, the V3 & Tc3 completed flag=1 is set. As a result, the process cannot proceed from step 11 to step 12 after the next time.

In this way, it is necessary to reduce the compression ratio V3 and the actual compression ratio at the timing at which the predicted acceleration is obtained in the flow of FIG. 9 from the predetermined value V1 to the compression ratio V3 at the timing at which the predicted acceleration is performed. The time Tc3 is stored in the memory. These two values V3 and Tc3 are used in the pre-acceleration compression ratio reduction processing.

Next, the flow of FIG. 14 is for performing the pre-acceleration compression ratio reduction process, and is executed at regular time intervals (for example, every 10 ms) following the flow of FIG. 9.

In step 31, the pre-acceleration compression ratio reduction processing completion flag (abbreviated as “pre-processing completion flag” in FIG. 14) is checked. The pre-acceleration compression ratio reduction processing completion flag is initially set to zero when the engine is started. Here, it is assumed that the pre-acceleration compression ratio reduction processing completion flag=0, and the process proceeds to step 32 and thereafter.

The operations of steps 32 and 33 are the same as the operations of steps 12 and 13 of FIG. That is, when the navigation controller 57 predicts the acceleration from the low load state to the high load state, and when the navigation controller 57 obtains the information that there is no traffic jam on the highway from now on, the process proceeds to step 34.

In step 34, the pre-acceleration compression ratio reduction processing start flag (abbreviated as “pre-processing start flag” in FIG. 14) is checked. The pre-acceleration compression ratio reduction processing start flag is initially set to zero when the engine is started. Here, assuming that the pre-acceleration compression ratio reduction processing start flag=0, the process proceeds to step 35. At step 35, is the timing before the start of acceleration by the time Tc3 (calculated by the flow of FIG. 9) required to reduce the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing at which the predicted acceleration is performed? See if it doesn't. If the timing before the time Tc3 required to reduce the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing at which the predicted acceleration is performed from the start of acceleration is not yet reached, the current process is terminated.

In step 35, when the timing Tc3 before the start of acceleration by the time Tc3 required to reduce the actual compression ratio from the predetermined value V1 to the compression ratio V3 at the timing at which the predicted acceleration is performed, the pre-acceleration compression ratio reduction process is performed. In order to start, the process proceeds to step 36 and the pre-acceleration compression ratio reduction process start flag=1 is set.

In step 37, the compression ratio control actuator 16 is driven to the side where the compression ratio decreases, and the actual compression ratio is decreased from the predetermined value V1.

Since the pre-acceleration compression ratio reduction process start flag=1 is set in step 36, the process proceeds from step 34 to step 38 from the next time onward. In step 38, the current (current) actual compression ratio V is compared with the compression ratio V3 (calculated by the flow of FIG. 9) at the predicted acceleration timing. The actual compression ratio V this time can be known from the command value issued to the compression ratio control actuator 16 by the engine controller 35. If the actual compression ratio V this time is not less than the compression ratio V3 at the timing when the predicted acceleration is performed, the process proceeds to steps 36 and 37, and the operations of steps 36 and 37 are executed. Unless the actual compression ratio V this time is less than the compression ratio V3 at the timing when the predicted acceleration is performed in step 38, the operations of steps 36 and 37 are repeated.

Eventually, if the actual compression ratio V of this time becomes less than the compression ratio V3 at the timing at which the predicted acceleration is performed in step 38, the actual compression ratio V at this time reaches the compression ratio V3 at the timing at which the predicted acceleration is performed. If so, the process proceeds to step 39 to stop driving the compression ratio control actuator 16.

This completes the pre-acceleration compression ratio reduction processing, so in step 40, the pre-acceleration compression ratio reduction processing completion flag=1 is set. In step 41, the pre-acceleration compression ratio reduction processing start flag=0 is set in order to prepare for the next acceleration from the low load state to the high load state. By setting the pre-acceleration compression ratio reduction processing completion flag=1, it is not possible to proceed from step 31 to step 32 after the next time.

Next, the flow of FIG. 15 is for performing an acceleration process, and is executed at regular time intervals (for example, every 10 ms) following the flow of FIG.

In step 51, the acceleration flag (initially set to zero at engine start) is checked. Here, it is assumed that the acceleration flag=0 and the process proceeds to step 52.

In step 52, based on the accelerator opening detected by the accelerator sensor 36, it is determined whether or not the acceleration is from a low load state to a high load state. When it is not the acceleration from the low load state to the high load state, the current processing is ended as it is.

On the other hand, when the accelerator opening changes from a predetermined value APO1 to a predetermined value APO2 (APO2>APO1) as shown in the uppermost part of FIG. 7, it is determined that the acceleration is from a low load state to a high load state. , Go to step 53. In step 53, the required supercharging pressure is calculated by searching the map having the content shown in FIG. 16 from the predetermined value APO2 and the engine rotation speed Ne. Corresponding to FIG. 7, the required supercharging pressure is a predetermined value B2 that is the supercharging pressure in the high load state after acceleration shown in the second stage of FIG. 7. As shown in FIG. 16, the required supercharging pressure is a value that increases as the accelerator opening APO increases. The predetermined value APO2 is detected by the accelerator sensor 36.

In step 54, a timer is started (timer value t=0). This timer is for measuring the elapsed time from the start of acceleration.

In step 55, the motor generator 49 is energized and driven to rotate the exhaust turbine 46 (force the turbocharger 45 to work).

In step 56, the acceleration flag is set to 1. In step 57, the compression ratio control actuator 16 is driven to the side where the actual compression ratio decreases. In this case, due to the pre-acceleration compression ratio reduction processing shown in FIG. 14, the actual compression ratio immediately before the acceleration should have settled to the compression ratio V3 at the timing when the predicted acceleration is performed. Therefore, the compression ratio control actuator 16 further decreases the actual compression ratio from the compression ratio V3 from the acceleration start timing.

Since the acceleration flag is set to 1 in step 56, the process proceeds from step 51 to step 58 from the next time onward. In step 58, the actual boost pressure Boost [MPa] detected by the boost pressure sensor 39 is compared with the required boost pressure [MPa] obtained in step 53. When the actual boost pressure Boost is less than the required boost pressure, the routine proceeds to step 59.

In step 59, the timer value t is compared with the fixed time. Here, the fixed time is a time during which the motor generator 49 is energized, and is set in advance. If the timer value t is less than the fixed time, the process proceeds to steps 55, 56 and 57, and the operations of steps 55, 56 and 57 are executed. As long as the actual boost pressure Boost is less than the required boost pressure and the timer value t is less than the fixed time, the operations of steps 55, 56 and 57 are repeated.

Eventually, when the timer value t becomes equal to or longer than the certain time in step 59, the process proceeds to step 60, the power supply to the motor generator 49 is stopped, the motor generator 49 is made non-driving, and the operations of steps 56 and 57 are performed. Execute. This is because if a certain time has elapsed from the start of acceleration, the exhaust turbine 46 will spontaneously rotate with the increased exhaust energy even if the exhaust turbine 46 is not forcibly driven by the motor generator 49. This is because it is not necessary to drive.

After the timer value t becomes equal to or longer than the predetermined time, the operations of steps 60, 56 and 57 are repeated as long as the actual boost pressure Boost is less than the required boost pressure in step 58.

Eventually, when the actual boost pressure Boost reaches the required boost pressure (predetermined value B2 in FIG. 7) in step 58, the actual compression ratio is the value in the high load state after acceleration (predetermined value V2 in FIG. 7). It should have fallen to. At this time, it is determined that it is unnecessary to further reduce the actual compression ratio, and the routine proceeds to step 61, where the compression ratio control actuator 16 is not driven. In step 62, the motor generator 49 is continuously driven.

Steps 63 to 65 are post-processing after the end of acceleration. In steps 63 and 64, zero is put in the compression ratio V3 and the required time Tc3 to set V3 and Tc3 calculated flag=0. In step 65, the pre-acceleration compression ratio reduction processing completion flag=0 is set in preparation for the next acceleration.

FIG. 17 is a simulation of how the compression ratio changes when a vehicle equipped with the engine of the present embodiment including a variable compression ratio mechanism and an electric assist turbocharger 45 is run in three test modes. The obtained data is summarized on the characteristics of the required compression ratio. FIG. 17 shows the difference between the test modes in three kinds of points, which are a black circle, a white circle and a square.

In FIG. 17, a point included in a region surrounded by a broken line is a compression ratio before the transition from the low load state to the medium load state by acceleration. In other words, the region surrounded by the broken line is a region where the compression ratio at the transition destination settles when traveling only on a general road, and is located on the low engine torque side. The point included in the area surrounded by the alternate long and short dash line is the compression ratio before the transition from the low load state to the high load state by acceleration. In other words, the area surrounded by the alternate long and short dash line is an area where the compression ratio at the transition destination is settled down when traveling on an expressway is included, and is located on the high engine torque side. There is a difference in the compression ratio at the transition destination between the acceleration from the low load state to the medium load state and the acceleration from the low load state to the high load state, and especially the transition ratio due to the acceleration from the low load state to the high load state. The compression ratio is greatly reduced (changed). As described above, the present invention is applied when the compression ratio at the transition destination is greatly reduced by the acceleration from the low load state to the high load state, that is, when traveling on the highway is included.

Here, the operation and effect of this embodiment will be described.

In the present embodiment, the compression ratio variable mechanism, the compression ratio control actuator 16, the required compression ratio setting means (35), the actuator control means (35), the turbocharger 45, the track information acquisition means, and the acceleration. A prediction unit (57) and a pre-acceleration compression ratio reduction processing unit (35) are provided. The compression ratio variable mechanism can change the compression ratio of the engine. The required compression ratio setting means (35) sets the required compression ratio so that the low load side has a relatively high compression ratio and the high load side has a relatively low compression ratio according to the engine operating conditions. The actuator control means (35) controls the compression ratio control actuator 16 (actuator of the compression ratio variable mechanism) so that the set required compression ratio is achieved. The turbocharger 45 (supercharger) supercharges intake air. The track information acquisition means acquires information on a track on which the vehicle is scheduled to travel. When the response time of the actual supercharging pressure is shorter than the response time of the actual compression ratio, the acceleration predicting means (57) uses the running road information acquisition means to increase the road from the low load state to the high load state on the road going forward (the running road going forward). Predict whether acceleration to load condition will occur. When the pre-acceleration compression ratio reduction processing means (35) predicts that an acceleration from a low load state to a high load state will be performed on the road going forward, when the compression ratio control actuator 16 is driven to predict the acceleration. The compression ratio is lowered in advance from the compression ratio. As a result, the response time from the turbocharger driving when the boost pressure changes from the state before acceleration to the state after acceleration is Even if it is shorter than the response time until it becomes, it is possible to avoid knocking.

In this embodiment, the track information acquiring hand stage I TS 60 is contributing system to improve traffic transport efficiency and comfort by utilizing IT. The ITS 60 includes a navigation system 50 compatible with VICS (registered trademark) , and the navigation system 50 is based on a road on which acceleration is performed (a track on which acceleration is performed), an accelerator opening degree and an engine rotation speed at the time of acceleration. Save the configured acceleration history. The acceleration predicting means predicts whether or not acceleration is to be performed on a road heading from these vehicles (a road running from here) based on the vehicle position and the acceleration history. Accordingly, if the ITS 60 including the navigation system 50 is already installed in the vehicle, increase in cost can be suppressed.

In this embodiment, the pre-acceleration compression ratio lowering means includes a compression ratio calculating means (35), a required time means (35), and an actuator drive starting means (35). When the predicted acceleration is performed on the road (the road to which the road is heading), the compression ratio calculating means (35) is the timing when the supercharging pressure is in the post-acceleration state and the compression ratio is in the post-acceleration state. The compression ratio V3 at the timing at which the acceleration is predicted to be the same as the timing is calculated. The required time means (35) reduces the compression ratio to the compression ratio V3 at the timing at which the predicted acceleration is performed, based on the compression ratio V3 at the timing at which the predicted acceleration is performed and the predetermined reduction rate of the compression ratio. The time Tc2 required for the calculation is calculated. The actuator drive starting means (35) starts driving the compression ratio control actuator 16 (actuator) to the side where the compression ratio decreases before the required time Tc2 calculated from the predicted acceleration timing. As a result, the compression ratio control actuator 16 can be driven to the side where the compression ratio decreases without delay.

In the present embodiment, the margin Tyo is included in the required time Tc3. As a result, even if there is a manufacturing variation in the compression ratio variable mechanism that determines the speed at which the compression ratio is reduced, the compression ratio V3 at the predicted timing of acceleration can be reliably obtained.

Even if there is a traffic jam on the road going from here (the road going from here), it is useless to reduce the compression ratio in advance, assuming that the acceleration from the low load state to the high load state is performed. In the present embodiment, based on the road traffic information (running road information) provided by the ITS 60 , the operation of the pre-acceleration compression ratio reduction processing means is stopped when there is a traffic jam on the road going from here. As a result, unnecessary reduction of the compression ratio is eliminated, so that it is possible to maintain high thermal efficiency on average and improve fuel efficiency.

The present embodiment has a basic ignition timing calculation means (35), a knock sensor 40, and an ignition timing feedback control means (35). The basic ignition timing calculation means (35) calculates the basic ignition timing at which MBT is obtained. The ignition timing feedback control means (35) retards the ignition timing by a fixed amount (a) when knocking occurs by the knock sensor 40, and thereafter returns the ignition timing to the advance side by a fixed amount (b). As a result, even when the response time Tb2 of the actual boost pressure is shorter than the response time Tc1 of the actual compression ratio, it is possible to obtain the optimum ignition timing MBT.

In the embodiment, the turbocharger 45, which uses the energy of the exhaust gas to supercharge the intake air and uses the motor generator 49 as a motor to rotate the exhaust turbine 46 during acceleration, has been described. Not limited. The present invention is also applicable to a supercharger.

1 Engine 16 Compression ratio control actuator (actuator)
35 engine controller (requested compression ratio setting means, actuator control means, pre-acceleration compression ratio reduction processing means, compression ratio calculation means, required time calculation means, actuator drive start means)
40 Knock sensor 45 Electric assist turbocharger (supercharger )
50 navigation system 57 navigation controller (acceleration prediction means)
60 ITS (Track information acquisition means)

Claims (8)

A supercharger for supercharging intake air,
A compression ratio variable mechanism that can change the compression ratio of the engine,
An actuator of the compression ratio variable mechanism,
A required compression ratio setting means for setting a required compression ratio so that a relatively high compression ratio is obtained on the low load side and a relatively low compression ratio is obtained on the high load side in accordance with engine operating conditions;
And an actuator control means for controlling the actuator so that the set required compression ratio is obtained ,
The response time until the supercharging pressure changes from the pre-acceleration state to the post-acceleration state by driving the supercharger is the response time until the compression ratio changes from the pre-acceleration state to the post-acceleration state by driving the actuator. A control device for an engine that is shorter than time,
A track information acquisition means for acquiring information on a track on which the vehicle is scheduled to travel,
Utilizing pre SL track information obtaining means, an acceleration estimating means for estimating whether the acceleration from the low-load state to a high load state is carried out in future towards runway,
When it is predicted that acceleration from a low load state to a high load state will be performed on the road running from now on, the pre-acceleration compression ratio that reduces the compression ratio in advance from the compression ratio when driving the actuator and predicting the acceleration An engine control device comprising: a reduction processing unit. 2. The engine control device according to claim 1, wherein the runway information acquisition means is an ITS that is a system that contributes to improvement of transportation efficiency and comfort of traffic by using IT. The ITS includes a navigation system compatible with VICS (registered trademark),
The navigation system saves an acceleration history composed of a track on which acceleration is performed, an accelerator opening degree and an engine rotation speed when the acceleration is performed,
3. The engine control device according to claim 2, wherein the acceleration predicting unit predicts whether or not the acceleration will be performed on the traveling path to which the vehicle will travel, based on the position of the vehicle and the acceleration history. The pre-acceleration compression ratio reduction processing means predicts the timing at which acceleration is performed by using the track information acquisition means,
When the acceleration is performed on the road running from here onward, the prediction is made such that the timing when the supercharging pressure is in the state after the acceleration and the timing when the compression ratio is in the state after the acceleration are the same. Compression ratio calculation means for calculating a compression ratio at the timing of acceleration,
It is necessary to calculate the time required to reduce the compression ratio to the compression ratio at the timing at which the predicted acceleration is performed, based on the compression ratio at the timing at which the predicted acceleration is performed and the predetermined reduction rate of the compression ratio. Time calculation means,
Actuator drive starting means for starting the drive of the actuator to the side where the compression ratio decreases before the calculated required time from the timing at which the predicted acceleration is performed. An engine control device described in any one of 1. The engine control device according to claim 4, wherein a margin is included in the required time. The operation of the pre-acceleration compression ratio reduction processing means is stopped when there is a traffic jam on the road going from the road traffic information provided by the road information acquisition means. The engine control device according to one. 7. The engine control apparatus according to claim 1, wherein the variable compression ratio mechanism is a multi-link type. Means for calculating the basic ignition timing at which the MBT is obtained,
With a knock sensor,
8. An ignition timing feedback control means for delaying the ignition timing by a constant amount when knocking occurs by the knock sensor, and thereafter returning the ignition timing to the advance side by a constant amount. the engine control apparatus according to one.

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