JPS62111170A - Knocking control device for internal combustion engine with supercharger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a knock control for internal combustion engines with a supercharger! If
! Regarding.

[Conventional technology]

Although supercharging of an internal combustion engine increases the output of the engine6, it also makes knocking more likely to occur. Therefore, knock control WtM is used, which detects knock by attaching a knock sensor consisting of a vibration detector to the cylinder block or the like and controls the engine to suppress knocking. One way to suppress knocking is to lower the boost pressure.
It is known that the ignition timing is corrected by retardation. In general, ignition timing control is based on engine speed N and load Q/N (
This is done by determining the basic ignition timing θβ from the intake air amount Q/rotational speed) or the intake pressure, and retarding the ignition timing from the basic ignition timing θβ depending on the state of occurrence of knock.

In recent years, in addition to devices that avoid knock by controlling only the ignition timing, devices have been developed that utilize the advantages of upward knock control to obtain high torque. A device has been proposed that controls direct flame timing and boost pressure in conjunction with each other. This type of device generally retards the ignition timing and lowers the boost pressure, but when the boost pressure is lowered, the basic ignition timing θβ moves to the advanced side, so the decrease in the boost pressure causes There has been a problem in that the ignition timing is temporarily advanced and knocking is more likely to occur. For example, as shown in Fig. 6, due to the reduction in boost pressure Pa, the knock limit ignition timing θKN, which is the limit for knock occurrence, is advanced, but if the basic ignition timing θβ is The problem is that the angle advances, and the required retard angle correction amount R increases rapidly, resulting in frequent knocks. Of course, this problem is a transient problem, and eventually, due to the occurrence of knock, the direct flame timing will be retarded and controlled to the knock limit flame timing θKNii, but even if it is only temporary, frequent knocks will Therefore, in order to solve the problem of lowering the boost pressure, a method has been proposed in which the basic ignition timing is calculated based on the boost pressure just before the boost pressure decreases and the ignition timing is controlled (Japanese Patent Laid-Open No. 1983-1999).
However, in this method, the ignition timing does not advance even if knock does not occur while the boost pressure is being reduced, and the ignition timing is controlled to be retarded than the knock limit ignition timing θKN. Therefore, there was a problem in that the torque loss was large.

[Problem that the invention attempts to solve]

The present invention has been made to solve the above problems, and aims to provide a knock control device that prevents frequent knocks when boost pressure decreases and minimizes torque loss. .

[Means for solving problems]

For this reason, the present invention includes a knock sensor, an ignition timing control means, and a supercharging pressure control means, and adjusts the retardation correction amount and supercharging pressure for correcting the ignition timing in the retarded direction depending on the state of occurrence of knock. The knock control device for a supercharged internal combustion engine is characterized in that the knock control device for a supercharged internal combustion engine is provided with means for increasing the amount of increase in the retardation correction amount when a knock occurs when reducing the boost pressure. A knock control device for an internal combustion engine with a supercharger is provided.

[Effect]

According to the above configuration, the correction speed of the retard correction amount increases only when the boost pressure decreases, and the ignition timing is quickly corrected by following the increase in the required retard correction amount due to the sudden advance of the basic ignition timing. This can prevent frequent knocks. Furthermore, when the reduction in boost pressure ends, the correction speed of the retard correction amount returns to the original value, so the ignition timing does not become unstable.

〔Example〕

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

FIG. 1 is an overall configuration diagram, in which 1 is an engine body, 2 is a supercharger, and 3 is an electronic control device. An electromagnetically actuated fuel injection valve 4 is disposed near each intake port of the intake manifold. Fuel maintained at a constant pressure is fed to each fuel injection valve 4 by a fuel pump (not shown), and the injection amount is controlled by the time the fuel injection valve 4 is operated and opened. Each generously provided spark plug 5
As is well known, the distributor 6 that distributes power to the crankshaft rotates once every two revolutions of the crankshaft, and inside it there is a reference angle sensor 7 that detects a specific position of the crankshaft, and a reference angle sensor 7 that detects the rotation of the crankshaft and detects the rotation of the engine. It is equipped with a rotation angle sensor 8 that generates an output signal.

The ignition coil 9 connected to the distributor is configured integrally with an igniter 10 that cuts off power to the ignition coil 9.

Further, a knock sensor 11, which is a piezoelectric type vibration detector, is attached to the shilling block and detects the vibration waveform of the ennon. It goes without saying that the knock sensor 11 may be of any type, such as an electrodynamic type, a piezoresistive type, or a strain gauge type, in addition to the piezoelectric type.

The fuel tank 12 of the supercharger 2 is provided in an exhaust passage 13, and the compressor 14 is provided in an intake passage 15. A waste date valve 17 is provided in a bypass passage 16 that bypasses the turbine 12.

The waste date valve 17 is operated by a Daifutsum-type seven-cut duct 18 to adjust the opening degree of the bypass passage 16. A diaphragm chamber of the diaphragm actiniator 18 is communicated with an intake passage 20 downstream of the compressor 14 through a pressure conduit 19, and intake air pressurized by the compressor 14 is guided therethrough. Moreover, the pressure conduit 19 is communicated with the intake passage 15 upstream of the compressor via a solenoid valve 21 from the middle thereof. Then, turn it on and off from the electronic control device 3! When the IJll signal is output, the solenoid valve 21 is turned on and off, and the effective opening degree of the solenoid valve 21 is controlled by the duty ratio of the on/off control signal, and the pressure applied to the diaphragm actuator 18 is controlled. The higher the open time ratio of the solenoid valve 21 is, the more the amount of air escaping to the upstream intake passage 15 increases, and the waste date valve 17 will not operate until the pressure in the downstream intake passage 20, that is, the boost pressure becomes higher. . Therefore, the boost pressure to the engine is controlled by the effective opening degree of the solenoid valve 21, and the larger the opening degree, the more
In other words, the solenoid valve 21 has a high duty ratio of the on/off control signal.
The higher the ratio of open time, the higher the boost pressure is controlled. Although an on-off type solenoid valve is used here as the solenoid valve 21, it is also possible to use a control valve having an opening adjustment function proportional to voltage.

The intake passage 15.2 is used to detect the operating condition of the engine.
The engine body 1 is equipped with an F70-meter 22 that detects the amount of intake air, an intake temperature sensor 23 that detects the intake air temperature, and a throttle valve opening sensor 24 that detects the opening of the throttle valve. A sensor 25 is provided in the exhaust passage, and an 02 sensor 26 that detects the oxygen concentration in the exhaust bus and informs the air-fuel ratio is provided.

FIG. 2 is a block diagram showing the detailed configuration of the electronic control device 3 and connections with various devices.

The electronic control device a3 includes a microcomputer 30 for control.

The reference angle sensor 7 and rotation angle sensor 8 are electromagnetic pickup type detectors, and their respective output signals are shaped into pulses by waveform shaping circuits 31 and 32, and sent to the micro combinator 30 as reference angle signals and rotation angle signals, respectively. is input. In addition, each sensor 22 to detect the operating state
The signal from 26 is input to a digital or analog input terminal of microcombiator 30.

The output signal of the knock sensor 11 is input to a knock detection circuit 33. This knock detection circuit 33 includes a band pass filter for extracting only the knock-specific frequency band (generally 6 to 9 K)12), and a band pass filter for rectifying and integrating the signal of this filter to extract the average value of the sensor signal. a determination level creation circuit for creating a knock determination level based on this average value signal, a comparator for detecting knock between this determination level and the output after passing through the filter,
A monostable multivibrator is built in to stretch this comparator output for a certain period of time. The knock detection circuit 33 detects a knock of a predetermined intensity or more, and inputs a digital signal to the microcomputer 30 indicating the presence or absence of knock.

The microcomputer 30 receives rotation angle information from the reference angle sensor 7 and rotation angle sensor 8, and various operating state sensors 22.
The ignition timing is calculated based on the operating state information from 26 to 26, and the ignition timing is corrected based on the knocking information from the /tsuk sensor 11, and the ignition signal is adjusted. Output. Then, by driving the igniter 1o to energize the ignition coil 9 and cutting off the energization at the calculated ignition timing, the high voltage generated when energization is resumed is guided to the ignition plug 5 of a predetermined cylinder via the distributor 6. , each cylinder is ignited in sequence. Further, the microcomputer 30 calculates the optimum boost pressure, and controls the boost pressure by changing the duty ratio of the on/off control signal to the solenoid valve 21.

Furthermore, the microcomputer 30 calculates the calculated fuel injection M
An injection signal is output to a predetermined crank angle position with a pulse width corresponding to fl, and the fuel injection valve 4 is opened for each cylinder to inject fuel.

The internal configuration of the microcomputer 30 will be briefly described. 8-bit configuration central processing unit (CPU) 4
1 stores control programs and constants necessary for calculations via the CPU path 42 (read-only memory (RO
M) 43. Temporary memory for temporarily storing calculation data (
RAM) 44, an interrupt control unit 45 for causing the cptJ41 to perform interrupt control, a 16-bit timer 46 configured to increase the count value by one for each clock cycle, which is the basic cycle of CPU operation, and a multiplexer. An A-D converter 548 for converting the analog signal selected at 47 into a digital signal, an input port 49 for the digital signal, and an output port 50 for outputting the digital signal are connected. Signals from the air 7a/-ta 22, the intake temperature sensor 23, and the cooling water temperature sensor 25 are input to the multiplexer 47 to which analog signals are input. The input boat 49 receives a 2-bit contact signal from the throttle valve opening sensor 24 and a 0. A glue lean signal is input from the sensor 26. From the output boat 50, a direct fire signal to the igniter 10, an injection signal to the fuel injection valve 4, an on/off control signal to the solenoid valve 21, and a multiplexer 47
The reference angle signal and rotation angle signal from the reference angle sensor 7 and the rotation angle sensor 8 are inputted to the zero interrupt control section 45, which outputs the control signal to the reference angle sensor 7 and the rotation angle sensor 8. The engine rotation speed and crank angle position are detected by the timer 46 and the interrupt control section 45 in the following manner. That is, each time an interrupt occurs due to the reference angle signal from the reference angle sensor 7, the CPU 41 reads the count value of the timer 46. Since the count value of the timer 46 increases every clock cycle (for example, 1 μs), the current By calculating the difference between the count value at the time of the interrupt and the count value at the time of the previous interrupt, the time interval of the reference angle signal, that is, the time required for one revolution of the engine can be measured. The engine rotation speed can then be determined. Further, since the rotation angle signal from the rotation angle sensor 8 is output at every fixed crank angle (for example, 30° CA), the crank angle position is determined by the reference angle signal from the reference angle sensor 7 (for example, the upper dead position [)].
The crank angle at that time can be found in units of 30'CA based on . This rotation angle signal every 30°GA is used as a reference point for generating an ignition signal.

The operation of the knock control device according to the present invention will be explained based on the above configuration.

Figures 3 and 4 are flowcharts showing actual processing in the microcomputer 30.

When the internal combustion W1 jump is started and an interrupt for ignition timing calculation is issued, the interrupt process is started from step 100. In step 101, the rotation speed N and the load Q/N (=intake air amount Q/rotation speed N) are calculated.

In step 102, a map of basic ignition timing and basic injection time stored in advance is searched and interpolated based on the rotation speed N and load Q/N calculated in step 101, and basic ignition timing 0 day and basic injection time are searched and interpolated. The injection time is calculated. In addition, the basic supercharging pressure is set in step 103, in which advance and retardation of the ignition timing and correction of the injection time are simultaneously performed based on information from various operating state sensors 22 to 26 other than the knock sensor 11. The basic duty ratio is calculated. The basic duty ratio is calculated by searching and interpolating pre-stored table values based on the rotational speed N.

Next, in step 104, it is determined whether the current operating conditions are knock control execution conditions. For example, it is generally known that when the load on the engine is light, knocking will almost always occur, and if you forcefully control the knock even if the engine is lightly loaded, the output, combustion pipe, etc. will actually decrease. In this embodiment, the knockdown wheel is executed only when the engine load Q/N is equal to or higher than a predetermined value. In addition, it is also possible to set a limit based on the engine speed.

If it is determined that the knock control execution condition is met, in step 105, the ignition timing retardation correction amount by knock control is calculated and the boost pressure is corrected.
Then, in the next step 106, the final duty ratio for setting the final ignition timing and boost pressure is calculated. The final ignition timing is calculated as (corrected basic ignition timing) - (retardation correction amount).

Details of step 105, which is a characteristic part of the present invention, will be explained with reference to FIG.

First, in step 201, it is determined based on the output of the knock detection circuit 33 whether or not a knock has occurred.

If it is determined that there is a knock, proceed to step 202.
In step 202, it is determined whether or not the boost pressure is being reduced. If it is not decreasing, it is in a steady state, so step 2
03, the retardation correction amount R is increased by a predetermined angle Δθ1. The value of Δθ1 is set, for example, to 1°GA (crank angle). If the boost pressure is decreasing, it is in a transient state, so the process proceeds to step 204, and the retardation correction amount R is set to Δ larger than Δθ1.
It increases by θ2. The value of Δθ2 is set to 2@CA, for example.

On the other hand, if it is determined in step 201 that there is no knock, the process proceeds to step 205. In step 205, it is determined whether or not the knock continues for a predetermined period of time (generally about 0.5 to 1 second). If the process has not been performed for a predetermined period of time or longer, the process proceeds to step 206, and the current retardation correction amount R is held. If the no-knock state continues for a predetermined period of time or more, the process advances to step 207.

Step 20? Then, as in step 202, it is determined whether or not the boost pressure is being reduced. If it is not decreasing, the process proceeds to step 208, where the retard angle correction amount R is decreased by a predetermined angle Δθ3. The value of Δθ3 is set, for example, to 1°GA, which is the same as Δθ1, but of course it may be set to a different value from Δθ1.If the boost pressure is decreasing, it is in a transient state, so the process proceeds to step 209, and the retardation is performed. The correction amount R is decreased by a predetermined angle Δθ4. For example, the value of Δθ4 is larger than Δθ3
Although it is set to 2° GA, which is the same as θ2, depending on the type of engine, it may be preferable to set it to a value as small as Δθ3.

In this way, the ignition timing retardation correction jlR is increased, decreased, or maintained depending on the knock occurrence state.

Next, in step 210, the magnitude of the retard correction amount R set as described above is determined.

If the retardation correction amount R is small and is equal to or less than the first set value R1 close to O (R>R1), the process proceeds to step 211, and the duty ratio of the on/off control signal is changed to increase the supercharging pressure Pg by a predetermined pressure ΔP. Correct.

If the retard angle correction ILR is within a predetermined range (R1≦R≦R2), it is determined that the boost pressure is appropriate, and the process proceeds to step 212, where the current boost pressure is maintained. If the retardation correction tR is large and equal to or higher than the second predetermined value R2 (R2<R), it is determined that the operating condition is such that the exhaust temperature becomes a problem, and the process proceeds to step 2.13, where the boost pressure Pa is increased. The duty ratio of the on/off control signal is corrected to reduce the pressure by a predetermined amount Δp. Appropriately, the predetermined pressure ΔP1Δp for increasing or decreasing the boost pressure Pa is about 50 mtaHg, the first predetermined value R1 for determining the magnitude of the retardation correction fiR is 2°GA, and the second predetermined value R2 is about 7°GA. It was suitable to set it to .

FIG. 5 is a timing chart showing an example of changes in supercharging pressure Pa and retardation correction IR controlled as described above.

Every time a knock occurs, the retard angle correction amount R becomes Δθ1 (to 1゛C1) f! is increased, and if knock does not occur for a predetermined time T, Δ
Decreased by θ3 (1°GA) (301 in Figure 5)
, and when the retardation correction amount R exceeds the second predetermined value R2, the supercharging pressure Pa starts to decrease (302 in FIG. 5),
, while the boost pressure Pa is decreasing, the amount of increase and amount of decrease of the retard angle correction amount is increased, and the retard angle correction amount R is increased every time a knock occurs.
is increased by Δθ2 (2° GA), and is decreased by Δθ4 (2' CA) if knock does not occur for a predetermined time T (303 in Fig. 5). It is possible to increase the sensitivity of the angle correction fiR to knocks, quickly follow sudden changes in the basic ignition timing θβ, and prevent frequent knocks. Then, when the retardation correction amount R decreases and the reduction in supercharging pressure Pa ends, the amount of increase in the retardation correction amount R per knock is also returned to the original value (Δθ1) (304 in FIG. 5). .

In this way, not only in steady state but also in transient state,
Since the retardation correction 11R is controlled so that the ignition timing is near the knock limit ignition timing (θKN in FIG. 6), knock control with small torque loss is realized.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to prevent frequent knocking when boost pressure drops, minimize torque loss, and achieve high torque knock control by linking ignition timing and boost pressure. There are excellent effects that can be done.

[Brief explanation of drawings]

1 to 5 show one embodiment of the present invention, FIG. 1 is an overall configuration diagram, FIG. 2 is a block diagram showing an electronic control device,
Figures 3 and 4 are 70-charts showing the processing in the microcomputer, Figure 5 is a timing chart showing the transition of boost pressure and retardation correction amount, and Figure #6 is a chart showing the changes in boost pressure and retardation correction amount. FIG. 3 is a characteristic diagram showing knock limit ignition timing characteristics. DESCRIPTION OF SYMBOLS 1... Engine main body, 2... Supercharger, 3... Electronic control device, 5... Spark plug, 6... Distributor, 7... Reference angle sensor, 8... Rotation angle sensor, 11... Knock sensor, 12... Turbine, 14
...Compressor, 16...Bypass passage, 17.
... Waste date valve, 18... Diaphragm actuator, 21... Solenoid valve, 30... Microcomputer, 33... Knock detection circuit. Figure 5/y9 "' Il, '71fl
Figure 6

Claims (1)

[Claims] 1. A knock sensor, an ignition timing control means, and a supercharging pressure control means, and a retardation correction amount and supercharging pressure that correct the ignition timing in a retarded direction according to the state of occurrence of knock. The knock control device for a supercharged internal combustion engine is characterized in that the knock control device for a supercharged internal combustion engine is provided with means for increasing the amount of increase in the retardation correction amount when a knock occurs when reducing the boost pressure. Knock control device for internal combustion engine with supercharger. 2. The knock control device for a supercharged internal combustion engine according to claim 1, further comprising means for increasing the amount of decrease in the retardation correction amount when knock does not occur when reducing the supercharging pressure.