JPS62182436A - Supercharging pressure control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable engine torque to be maintained at a specified value irrespective of the magnitude of a delay angle, by a method wherein a supercharging pressure set value, set by a supercharging pressure setting means, is corrected according to an ignition timing obtained by a knocking control device. CONSTITUTION:A supercharging pressure control means 4 controls operation of the weight valve of a supercharger 2 by means of a supercharging pressure, set by a supercharging pressure setting means 5 depending upon the operating state of an engine, and a supercharging pressure, obtained by the supercharger 2, and the supercharging pressure control device of an internal combustion engine 1 controls the supercharging pressure to a given value. Meanwhile, a knocking control device 3, when the occurrence of knocking of the internal combustion engine 1 is detected, delays an ignition timing according to the magnitude of the knocking, a delay angle signal therefrom is inputted to a supercharging pressure correcting means 6 to correct the supercharging pressure set value so as to increase it by a given amount. This constitution enables engine torque to be maintained at a specified value irrespective of the magnitude of a delay angle, and permits improvement of acceleration performance.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a supercharged internal combustion engine equipped with a knock control device that corrects ignition timing based on a signal from a knock detection means such as a knock sensor. This invention relates to a supply pressure control device.

[Conventional technology]

A device (KO2) is known that suppresses knocking by controlling ignition timing depending on the presence or absence of a knocking signal from a knock sensor. That is, when it is detected that knocking has occurred, the ignition timing is retarded from the base value. As a result, when knocking is suppressed, the amount of retardation is reduced and the ignition timing is advanced toward the base value. Knocking can be suppressed by such feedback control.

[Problem that the invention seeks to solve]

When the ignition timing is retarded by the operation of KC3, the engine torque decreases in any KO2 operating range compared to standard operating conditions assuming ignition at the base value.

As a result, the acceleration performance of the engine is felt to deteriorate, and even at the same vehicle speed and throttle valve opening, the engine torque differs depending on whether KO2 is operating or not, so in vehicles equipped with automatic transmissions, shift shock occurs. It is possible that it will come out.

[Means for solving problems]

This invention focuses on the fact that in a system equipped with a turbocharger and capable of controlling the boost pressure, the torque changes depending on the magnitude of the boost pressure. By controlling the supply pressure in magnitude, it is possible to compensate for torque fluctuations caused by the operation of KO2. That is, in FIG. 1 showing the configuration of the present invention, an internal combustion engine 1 has a supercharger 2.
and a knocking control device that controls ignition timing according to the knocking state of the internal combustion engine. According to this invention,
means 4 for controlling the supercharging pressure obtained by the supercharger as desired; supercharging pressure setting means 5 for setting the supercharging pressure obtained by the supercharging pressure control means 4 according to engine operating conditions; and knocking control. A supercharging pressure control device is provided which includes a supercharging pressure setting value correcting means 6 for correcting the supercharging pressure setting value set by the supercharging pressure setting means 5 in accordance with the ignition timing obtained by the device 3.

[Example] To explain the present invention in detail below, in FIG. 2, 1
0 is a cylinder block, 12 is a piston, 14 is a connecting rod, 16 is a cylinder head, 18 is a combustion chamber, 20 is a spark plug, 22 is an intake valve, 24 is an intake valve, 2
6 is an exhaust valve, and 28 is an exhaust boat. Intake boat 24
is connected to an air cleaner (not shown) via an intake manifold 30, intake pipes 32, 34, and a tube 36. A fuel injector 40 is attached to a branch pipe of the intake manifold 30 proximate each intake boat 24. The throttle valve 42 is located upstream of the surge tank portion of the intake manifold 30.

Exhaust boat 28 is connected to exhaust manifold 46.48.

The distributor 50 has its distribution electrode connected to each spark plug 20 and its central electrode connected to an ignition device 52 consisting of an ignition coil and an ignition circuit.

As is well known, an ignition signal is applied to the ignition circuit from the control circuit 54, a high voltage is generated in the ignition coil, and this high voltage is distributed by the distributor to the ignition plug 20 of the cylinder in which ignition is to be performed. There is.

The internal combustion engine of the present invention includes a turbocharger 60 as a supercharger. The turbocharger 60 connects the intake pipes 32 and 3
the compressor 60a located between the exhaust pipe 4 and the exhaust pipe 4;
It consists of a turbine 60b located between 6 and 48, and a rotating shaft 60c connecting these. A bypass passage 62 is installed to bypass the turbine 60b, and a bypass control valve 64 (so-called wastegate valve) is installed in the bypass passage 60.
is placed. The wastegate valve 64 is connected to the link means 6
6 to a diaphragm actuator 68. The diaphragm actuator has an internal diaphragm connected to the intake pipe 32 of the turbocharger 60 downstream of the compressor 60a via a pressure conduit 70. When the pressure downstream of the compressor 60a is low, the actuator 68
4 is closed, but when the pressure increases, the actuator 68 opens the wastegate valve 64, and the boost pressure is set so as not to exceed a predetermined value determined by the engine.

The supercharging device of the present invention further includes means for controlling supercharging pressure. This means is constituted by a bleed control valve 72. The bleed control valve 72 is an electromagnetic on-off valve,
Located on the air bleed passage 74 to the pressure conduit 70 to the actuator 68 . 75 is a diaphragm for controlling the amount of bleed air.

Air bleed passage 74 is connected to intake pipe 34 upstream of compressor 60a of turbocharger 60. When the bleed control valve 72 opens, air is introduced into the pressure conduit 70;
The actuator 68 will not be driven unless the boost pressure downstream of the compressor increases accordingly. That is, the supercharging pressure when the actuator 68 drives the wastegate valve 64 to open is variably controlled so as to increase as the opening degree of the bleed control valve 72 increases. As will be described later, the air bleed control valve 72 is driven by a pulse signal and has an opening degree that corresponds to its duty ratio.

The control circuit 54 controls the ignition device 52 as described above, but according to the present invention it also performs control to generate a pulse signal that drives the bleed control valve 72.

In this embodiment, the control circuit 54 is configured as a microcomputer, and includes a microprocessing unit (MPU).
) 54a, memory 54b, input boat 54C, output boat 54d, and a bus 54 connecting these elements.
It is composed of e.

Each sensor is connected to the input capo 54C, and operating condition signals are input thereto. An intake pressure sensor 77 is installed in the surge tank portion of the intake manifold 30, and obtains a signal corresponding to the intake pressure PM corresponding to the engine load. Crank angle sensors 78 and 80 are attached to the distributor 50. The first crank angle sensor 78 generates a reference signal, for example, a pulse signal G every 720'' of the crankshaft.On the other hand, the second crank angle sensor 8
0 is, for example, the crankshaft pulse signal Ne every 30@
can be generated and the engine speed can be determined.

A throttle sensor 82 is connected to the throttle valve 42;
You can know the opening degree of the throttle valve.

Furthermore, a knock sensor 84 is attached to the cylinder block. The knock sensor 84 is, for example, a type of converter that converts mechanical vibrations of the engine into electrical vibrations, and can detect knocking or non-knocking based on the amplitude.

The output boat 54d includes an ignition device 52 and a fuel injector 4.
0, bleed control valve 72 is connected. The MPU 54a performs calculations according to the program described later, and converts the
) 54d outputs a drive signal to perform necessary control.

4 and 5 are flowcharts illustrating the operation of the control circuit 54. FIG. 3 shows a knocking control and ignition timing control routine, and this routine is a crank angle interrupt routine that is executed every time a pulse signal arrives every 30'' CA from the second crank angle sensor 80. In step 90, it is determined whether or not the crank angle period is such that knocking is detected.That is, the signal from the knock sensor 84 can be expressed, for example, as shown in FIG. Since the peak vibration occurs after the compression top dead center, the process of determining the presence or absence of knocking is performed only during this period as shown in (e).If it is determined that it is the knocking detection period, the process advances from step 90 to step 92, and the knocking*Jm device It is determined whether or not it is in the operating range of (KO2).Knocking occurs only in a certain range of engine speed and load (region above direct vAk in Fig. 7).K
If it is determined that it is not in the CS operating range, the process proceeds to step 94 and the ignition timing retard correction amount AKNK is fixed at 0. Therefore, the ignition timing will take the base value as described below.

If the KC3 operating range is reached, the process proceeds to step 96, where it is determined whether or not knocking has occurred. This determination is made by the knock sensor 84.
This is done by checking whether the amplitude from is larger than a predetermined value. If it is determined that there is knocking, the process proceeds to step 98, where the ignition timing retardation correction amount AKNK is increased by a predetermined value a. If it is determined that there is no knocking, the process proceeds to step 100, where it is determined whether or not the no-knocking state has continued for a predetermined number of ignitions. If Yes, proceed to step 101,
The retard angle correction amount AKNK is decreased by b. Knocking is prevented by such feedback control of the retardation correction amount, and the ignition timing is set as close to the base value as possible.

In step 102, a smoothing value of the correction value of the retard amount is calculated, which is used to calculate the correction value of the supercharging pressure, which will be described later.

The calculation formula for such a rounded value is, for example, AKNKav = ((c −1)8KNKav+/
IKNK)/c.

In step 104, the ignition timing retardation correction amount A is smoothed.
A correction value P of the supercharging pressure is calculated according to KNKaν. The meaning of this will be explained later.

If it is not within the crank angle range for knocking detection (No is determined in step 90, and it is determined in step 106 whether or not the crank angle period is for ignition calculation.Ignition calculation is performed at a predetermined crank angle before compression top dead center). Yes, see Figure 5 (c).If the ignition calculation crank angle is used, step 1
Proceed to 08 and the basic ignition timing θmAsE is the engine rotation speed N.
A map is calculated from e and intake pipe pressure PM. In step 110, the final ignition timing θ is the basic ignition timing θ1lASE.
It is calculated by subtracting the retard angle correction amount AKNK depending on the presence or absence of knocking. Step 112 shows the output of the ignition signal. See Figure 5 (d). As is well known, the ignition circuit is charged by the rising edge of the ignition signal, and a spark is generated by the falling edge of the ignition signal, and this point in time is the ignition timing θ measured in angle from TDC.

FIG. 4 shows the boost pressure control routine. This routine is
For example, it may be a time interrupt routine that is executed every 50 msec. In step 120, a duty ratio of the drive pulse signal of the bleed control valve 72 is calculated in accordance with the engine speed Ne and the throttle valve opening TH. Since the supercharging pressure is changed depending on the magnitude of the duty ratio, the supercharging pressure is set according to the engine operating conditions by the process of step 120.

In the next step 122, the duty ratio correction value ΔDut
y is calculated based on the pressure correction value ΔP,l corresponding to the annealed retardation correction amount calculated in step 104 of FIG. In step 144, the duty is calculated as 120.
The value obtained by subtracting ΔDuty from the value is DuLy. That is, the target value of the boost pressure is corrected according to the retardation correction amount. Step 146 shows the output of the duty signal. The bleed control valve 72 is driven by a pulse signal having this duty ratio.

In FIG. 6, a curve 1 shows the relationship between ignition timing and engine torque when the boost pressure is set to the original set value PIO. The straight line m is the limit of occurrence of knocking, and the supercharging pressure is P due to the action of KC3. In this case, the ignition timing is controlled around point A on this straight line m.

When the operating conditions shift to conditions where knocking is likely to occur, the knocking limit shifts to the retarded side by a crank angle of δ, as shown by wAn. Therefore, the engine torque moves to point B on the same curve pHl, and the torque decreases by ΔT.

On the other hand, set the boost pressure to the original setting value P. When the engine torque is increased by ΔP from ΔP, the engine torque is increased by that amount.

By appropriately selecting the value of ΔPI, it is possible to obtain a point C on the same knocking limit line n that can compensate and offset the torque ΔT that has dropped due to the retardation of the ignition timing. Note that the retard angle correction amount AKNK, which is the basis of the calculation of ΔP, has large temporal fluctuations as it is in order to prevent transient knocking, but such fluctuations can be suppressed by adding smoothing processing as in the example. P can be used as the basis for calculation.

FIG. 7 shows the change in torque with respect to the engine speed by the opening degree of each throttle valve. The area above the straight line is the operating range of KC5, and above this, retard control is executed in response to knocking. Conventionally, the torque changed between the solid line and the broken line at each throttle valve opening depending on the amount of retardation, but in this invention, the boost pressure is changed according to the amount of retardation, so the retardation A solid line torque characteristic can be obtained regardless of the magnitude of the angle.

FIG. 8 shows the relationship between engine speed and intake pipe pressure.

The area above the line p in the figure is the area where changing the boost pressure setting affects the intake pipe pressure, and the area above the line r is the area where the amount is increased in the fuel injection system (air-fuel ratio).
stoichiometric air-fuel ratio).

Since the fuel consumption rate can be improved by increasing the boost pressure, the fuel consumption rate can be improved in the diagonally shaded area surrounded by wAk, p, and r.

〔Effect of the invention〕

According to the present invention, in a supercharged engine having a system that retards ignition timing in response to knocking, the engine torque can be adjusted by controlling the supercharging pressure according to the amount of retardation. It is possible to maintain a constant value regardless of the Therefore, acceleration performance can be improved. Furthermore, when applied to a vehicle with an automatic transmission, switching shock can be reduced.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the present invention. FIG. 2 is an overall configuration diagram of an embodiment of the present invention. FIGS. 3 and 4 are flowcharts for explaining the operation of the first embodiment of the present invention. FIG. 5 is a timing chart explaining the ignition operation. FIG. 6, FIG. 7, and FIG. 8 are graphs explaining the operating characteristics of the internal combustion engine of the present invention. 30.32.34...Intake pipe 42...Throttle valve 46.48...Exhaust pipe 50...Distributor 52...Ignition device 54...Control circuit 60...Turbocharger 62...・Bypass passage 64...Wastegate valve 68...Actuator 70...Pressure conduit 72...Air bleed control valve 74...Air bleed passage Figure 1 Figure 4 Figure 6 Rotation speed'$7 figure

Claims (1)

[Claims] In a supercharged internal combustion engine having a knocking control device that corrects ignition timing depending on the presence or absence of knocking in the internal combustion engine, there is provided a means for controlling the supercharging pressure obtained by the supercharger as desired, and a means for controlling the boost pressure obtained by the supercharger according to engine operating conditions. a supercharging pressure setting means for setting the supercharging pressure obtained by the supercharging pressure control means according to the ignition timing obtained by the knocking control device; A supercharging pressure control device comprising a supercharging pressure setting value correcting means.