JP3302719B2 - Control device for engine with turbocharger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of an engine provided with a turbocharger, and more particularly to control of ignition timing at the time of acceleration that causes a delay in a rise in supercharging pressure.

[0002]

2. Description of the Related Art Conventionally, there is generally known an engine with a turbocharger in which the output is increased by supercharging intake air by a turbocharger driven by the energy of exhaust gas. Further, in this type of turbocharged engine, as shown in, for example, JP-A-59-201944, the engine speed is set to be higher by a predetermined amount during idling operation after high-load operation than during normal idling operation. It is known to control the ignition timing to adjust the output at the time of idling, such as performing idle-up and advancing the ignition timing at the time of idle-up.

[0003]

In the above turbocharger, the turbine is driven by the exhaust gas flow, and the intake air is supercharged by the rotation of the compressor in conjunction with the exhaust gas flow. On the other hand, there is a certain delay between the increase in the rotation speed of the turbocharger due to the increase in the exhaust gas flow and the increase in the supercharging pressure. This delay is called a turbo lag, and hinders an improvement in acceleration response.

[0004] In order to increase the output by ignition timing control, it is conceivable to advance the ignition timing in order to solve such a problem. It cannot be hoped for and does not help to reduce turbo lag.

As ignition timing control at the time of acceleration, there is known an ignition timing control in which the ignition timing is retarded at the beginning of acceleration in order to suppress knocking which tends to occur at the beginning of acceleration (for example, Japanese Patent Application Laid-Open No. 59-1984). -7779 publication). But,
This control only retards the ignition timing at the timing when knocking occurs at the beginning of acceleration, and has not been considered as a countermeasure against the turbo lag problem in the turbocharged engine.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a control device for a turbocharged engine capable of shortening a turbo lag and improving acceleration response by increasing exhaust energy during acceleration. And

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an ignition timing adjusting means for enabling an ignition timing to be changed in an engine provided with a turbocharger, and a boost delay of a supercharging pressure. Determining means for judging an engine acceleration state in which the ignition occurs, and controlling the ignition timing adjusting means so as to retard the ignition timing during a period until a predetermined boost pressure rise state is reached during acceleration according to the judgment by the judgment means. Control means for increasing the exhaust energy given to the turbocharger, operating state detecting means for detecting the operating state of the engine, and a supercharging pressure sensor for detecting the supercharging pressure of the turbocharger, The control means predicts a supercharging pressure at the time of eliminating turbo lag in the turbocharger based on a detection result of the operating state detecting means, and detects the predicted supercharging pressure and the supercharging detected by the supercharging pressure sensor. With the difference is larger as the ignition timing retard quantity greater with, according to the gear position of the transmission, in which is configured to increase the ignition timing retardation amount during acceleration as will high speed stage.

[0008]

According to the present invention, during acceleration, the rotation of the turbocharger is accelerated by the increase in exhaust energy due to the retardation of the ignition timing, and this state is maintained until a predetermined supercharging pressure is increased. The pressure rise is accelerated.

In particular, the larger the difference between the predicted boost pressure and the boost pressure detected by the boost pressure sensor, the greater the ignition timing retard amount. The effect of increasing the machine speed is enhanced. Further, the ignition timing retard amount at the time of acceleration is increased as the speed becomes higher according to the shift speed of the transmission, so as to compensate for the tendency that the turbo lag tends to cause the backlash of the acceleration toward the higher speed. Accordingly, the effect of accelerating the turbocharger rotation due to the increase in the exhaust energy is enhanced.

[0010]

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 schematically shows the entire turbocharged engine. In FIG. 1, an engine body 1 is connected to an intake manifold 3 constituting a downstream portion of an intake passage 2 and an exhaust manifold 5 constituting an upstream portion of an exhaust passage 4. The engine is provided with a turbocharger 6.

The turbocharger 6 connects a turbine 7 provided in the exhaust passage 4 downstream of the exhaust manifold 5 and a compressor 8 provided in the intake passage 2 upstream of the intake manifold 3. The compressor 9 rotates with the rotation of the turbine 7 driven by the exhaust gas flow to supercharge the intake air. In order to adjust the maximum supercharging pressure of the turbocharger 6, a wastegate passage 11 communicating the upstream side and the downstream side of the turbine 7 and a wastegate valve 12 opening and closing this passage are provided. I have. A catalyst 1 for purifying exhaust gas is provided in an exhaust passage 4 downstream of the turbine 7.
3 are provided.

In the intake passage 2 of the engine, in addition to the compressor 8, an air cleaner 15, an air flow meter 16 for detecting an intake air amount, an intercooler 17 for cooling supercharged air, and a throttle valve 18 are arranged. An injector 19 for injecting and supplying fuel is provided near the downstream end of each branch passage of the manifold 3.

An ignition plug 21 is provided in the combustion chamber of each cylinder of the engine body 1. This spark plug 2
1 is connected to an ignition controller (ignition timing adjusting means) 22 composed of an ignition coil, an igniter and the like, and the ignition controller 22 can change the ignition timing.

The ignition controller 22 includes a control unit (EC) comprising a microcomputer or the like.
U) 30 are electrically connected. The ECU 30 includes the air flow meter 16 and a supercharging pressure sensor 23 for detecting a supercharging pressure in an intake passage downstream of the compressor 8.
, A throttle opening sensor 24 for detecting the opening of the throttle valve 18, a rotation speed sensor 25 for detecting the engine speed, and an oil temperature of lubrication and cooling oil supplied to the turbocharger 6. Each detection signal from the oil temperature sensor 26 is input. And from this ECU 30,
An ignition timing control signal is output to the ignition controller 22 and a fuel injection control signal is output to the injector 19.

FIG. 2 shows a functional configuration of the ECU 30. In this figure, the ECU 30 constitutes air-fuel ratio control means 31 for controlling the air-fuel ratio by controlling the fuel from the injector 19, and as basic means for controlling the ignition timing, a basic ignition timing setting means 32, an engine acceleration A state determining means 33 and a control means 34 for controlling the ignition timing according to the determination by the determining means 33 are provided.

The air-fuel ratio control means 31 sets the air-fuel ratio in accordance with the operating state determined by the engine speed N and the engine load equivalent such as the throttle opening TVO. Based on the setting, the air-fuel ratio (A / F) is set to be considerably leaner than the stoichiometric air-fuel ratio (further leaner than A / F = approximately 16 where NOx is likely to occur) in the predetermined operation region on the low-load low-speed side. On the other hand, the air-fuel ratio is set to be rich in the high load side and the high rotation side regions. Then, the fuel injection amount is calculated so as to obtain the set air-fuel ratio in accordance with the intake air amount Q and the engine speed N, and an injection pulse having a pulse width corresponding to the calculated amount is output to the injector 19.

The basic ignition timing setting means 32 sets the ignition timing according to the operating state as is known in general ignition timing control. The above determination means 3
3 is for judging an acceleration state of the engine such that a so-called turbo lag of the turbocharger causes a rise in supercharging pressure, and for example, a supercharging pressure prediction value and a supercharging pressure detection obtained from a map or the like according to an operating state. When the difference from the value P increases, it is determined that the vehicle is in the acceleration state.

The control means 34 retards (retards) the ignition timing when the vehicle enters the acceleration state based on the determination. In this case, the retard amount at the time of acceleration is adjusted according to the magnitude of the delay in increasing the boost pressure. For example, according to the difference ΔP between the boost pressure predicted value Pa and the actual boost pressure P, the larger the difference, the greater the difference. Increase the retard amount. Further, if necessary, the ignition timing retard amount at the time of acceleration is corrected in accordance with an element related to the turbo lag. For example, the retard is set so that the oil temperature becomes lower in accordance with the oil temperature To of the oil supplied to the turbocharger 6. Correct in the direction of increasing the amount. Further, instead of or in addition to such correction in accordance with the oil temperature, according to the detection signal 27 of the transmission gear stage of the transmission shown by the two-dot chain line in FIGS.
The retard amount is reduced at the low speed stage, and the retard amount is increased at the high speed stage.

FIG. 4 is a flowchart showing an example of the control of the ignition timing by the ECU 30. When the process of this flowchart starts, the ECU 30 first reads detection signals such as the intake air amount Q, the engine speed N, the throttle opening TVO, the supercharging pressure P, and the oil temperature To in step S1, and in step S2, reads the detection signals. The predicted pressure value Pa is read. The supercharging pressure predicted value Pa is obtained by preliminarily examining the supercharging pressure at the time of eliminating the turbo lag in various operating states (engine speed and throttle opening) and is stored as a map. Read the value according to the operating state.

Subsequently, in step S3, a difference ΔP between the supercharged pressure predicted value Pa and the detected supercharged pressure P is determined. In step S4, whether the difference ΔP is larger than a predetermined value α is determined. It is determined whether or not the vehicle is accelerating with a delay in increasing the supply pressure.

If the determination in step S4 is NO, in step S5, a basic ignition timing Pb corresponding to the operating state is obtained from a map of the basic ignition timing, and this is set as the final ignition timing θ.

On the other hand, when the acceleration is determined to be YES in step S4, the ignition timing θr for retard control during acceleration is set in step S6. The ignition timing θr is retarded more than the basic ignition timing according to the operation state at that time. In particular, the retard amount is increased as the difference ΔP is increased. Further, in step S7, a final ignition timing θ is obtained by adding a correction value α corresponding to the oil temperature to the ignition timing θr. The correction value α is set to a larger value as the oil temperature is lower, and is set to 0 when the oil temperature is higher than a predetermined value. Further, instead of or in addition to such correction in accordance with the oil temperature, the retard amount is decreased in the low speed stage and increased in the high speed stage according to the detection signal 27 of the transmission speed stage of the transmission. to correct.

Following step S5 or step S7,
After performing the process of executing ignition in step S8, the process returns.

According to the apparatus of this embodiment, when the boost pressure is delayed due to the turbo lag during the acceleration of the engine, the boost pressure predicted value Pa and the boost pressure P
Is larger than a predetermined value, this state is determined, and according to this determination, the ignition timing is retarded.

The retard of the ignition timing raises the exhaust gas temperature and increases the exhaust energy applied to the turbine 7 of the turbocharger 6, so that the boost pressure is promoted. In this case, the retard amount of the ignition timing is increased as the difference ΔP is increased, so that the effect of shortening the turbo lag is enhanced as the turbo lag is increased. The boosting pressure boosting action due to the ignition timing retard is caused by the boost pressure P sufficiently approaching the boost pressure predicted value Pa and the difference Δ
It is continued until P falls below a predetermined value. Thus, the supercharging responsiveness is enhanced, and the turbo lag is reduced.

The ignition timing retard control at the time of acceleration includes a correction based on the oil temperature. That is, when the oil temperature is low, the turbo lag tends to increase due to an increase in the viscosity of the oil supplied around the axis of the turbocharger 6, whereas the turbocharger increases by increasing the ignition timing retard amount. The effect of increasing the rotation speed of the feeder 6 is enhanced.

Further, when the ignition timing is retarded in this manner, the catalyst 1 becomes cold during cold operation due to a rise in exhaust gas temperature.
The effect of hastening the activation of 3 is also obtained, which is advantageous for exhaust gas purification.

Further, in the apparatus of this embodiment in which the air-fuel ratio is controlled based on the region setting as shown in FIG. 3, the operation in which the air-fuel ratio is made rich from a predetermined operation region in which the air-fuel ratio is set to lean is performed. In the case where the fuel is accelerated to the range (arrow in FIG. 3), the effect of suppressing the increase of NOx is obtained by the ignition timing retard. In other words, in such a case, the fuel injection amount is controlled so that the air-fuel ratio changes from lean to rich, but during the change of the air-fuel ratio, the air-fuel ratio becomes close to the air-fuel ratio where NOx is most likely to be generated. NOx
However, if the ignition timing is retarded at this time, the maximum combustion temperature is reduced and the effect of suppressing NOx is obtained, and the NOx suppressing effect and the boost pressure boosting promoting effect are simultaneously achieved. Will be done.

In addition, the retard amount is reduced in the low speed stage and the retard amount is increased in the high speed stage in accordance with the detection signal 27 of the speed stage of the transmission. The tendency of the occurrence of the occurrence is corrected, and the acceleration response at the high speed stage is improved.

The specific configuration of the present invention is not limited to the above-described embodiment, but can be variously modified, and several examples will be described below.

In order to achieve the above-described NOx suppressing action and boost pressure boosting action, at least when the air-fuel ratio is accelerated from the lean range to the rich range, the ignition timing is set to The ignition timing may be retarded during acceleration other than the above, although it is sufficient to retard the ignition timing.

As means for checking the supercharging pressure, instead of the direct detection by the supercharging pressure sensor, a means for indirectly checking the intake air amount detected by the air flow meter and the engine speed may be used. . Further, the determination of the engine acceleration state in which the turbo lag occurs may be performed based on the rate of change of the throttle opening.

[0034]

According to the present invention, the ignition timing adjusting means is controlled so as to delay the ignition timing during a period of time during which the supercharging pressure rises to a predetermined supercharging pressure increasing state during engine acceleration. Control means for increasing the exhaust energy given to the turbocharger, the increase in the exhaust energy due to the retardation of the ignition timing during acceleration promotes the increase in the rotation of the turbocharger, and can reduce the turbo lag. , Acceleration responsiveness can be improved.

In particular, the control means predicts the supercharging pressure at the time of eliminating the turbo lag in the turbocharger based on the detection result of the operating state detecting means, and detects the predicted supercharging pressure and the supercharging pressure detected by the supercharging pressure sensor. Since the ignition timing retard amount is configured to increase as the difference from the supply pressure increases, the boost pressure boosting action can be enhanced in accordance with the delay in the rise of the boost pressure.

Furthermore, since the ignition timing retard amount at the time of acceleration is increased in accordance with the shift speed of the transmission as the speed increases, the acceleration due to the turbo lag tends to occur during acceleration in the high speed. Can be corrected.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a control device for an engine with a turbocharger according to an embodiment of the present invention.

FIG. 2 is a functional block diagram of a control system.

FIG. 3 is an explanatory diagram showing an area setting of air-fuel ratio control according to an operation state.

FIG. 4 is a flowchart illustrating a specific example of control by a control unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 6 Turbocharger 19 Injector 21 Spark plug 22 Ignition controller 30 ECU 31 Air-fuel ratio control means 33 Judgment means 34 Control means

──────────────────────────────────────────────────続 き Continuation of front page (51) Int.Cl. ⁷ identification code FI F02D 45/00 312 F02D 45/00 312Q F02P 5/15 H (58) Field surveyed (Int.Cl. ⁷ , DB name) F02P 5/15 F02D 45/00 301 F02D 45/00 312

Claims (1)

(57) [Claims] 1. An engine equipped with a turbocharger, an ignition timing adjusting means for enabling an ignition timing to be changed, a judging means for judging an engine acceleration state in which a boost pressure rise delay occurs, and this judging means. Control means for controlling the ignition timing adjustment means so as to retard the ignition timing to increase exhaust energy given to the turbocharger during a period until the predetermined boost pressure rise state is reached during acceleration according to the determination; Operating state detecting means for detecting an operating state of the engine, and a supercharging pressure sensor for detecting a supercharging pressure of the turbocharger, wherein the control means is configured to perform control based on a detection result of the operating state detecting means. together when predicting the supercharging pressure at the time of turbo lag eliminated in the turbocharger, increasing the prediction supercharging pressure and the more the ignition timing retard amount is large difference between the supercharging pressure detected by the boost pressure sensor To the gear position of the transmission
A control device for a turbocharged engine, characterized in that the ignition timing retard amount at the time of acceleration is increased as the speed increases .