JPH01216056A - Controller for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the number of used sensors by providing a combustion condition detecting means in a specified cylinder, setting a first control parameter at a different value from those for the other cylinders, and controlling a second control parameter of all the cylinders based on the output of this detecting means. CONSTITUTION:In a four-cylinder engine, a specified cylinder, or a first cylinder for example, is provided with a cylinder inner pressure sensor 3 of a combustion condition detector, and its output signal is inputted to a knock detecting circuit 41 in a control circuit 4. The output signal of this knock detecting circuit 41 is inputted to a computer 43 together with the output signals from an intake air pressure sensor 6, an air flow sensor 8 and a crank angle sensor 5. The computer 43 sets the fuel injection quantity for the first cylinder on the dilute side to make it easier to generate a knock in the first cylinder, and when the knock is detected, the ignition timings for the first cylinder and other cylinders are controlled for an angular delay of a predetermined value, thereby production of knocks are prevented for all the cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an internal combustion engine control device that controls the combustion state of the internal combustion engine.

[Conventional technology]

As a device for controlling the combustion state of an internal combustion engine, there is a device that detects the occurrence of knock using, for example, an in-cylinder pressure sensor, and controls combustion control parameters such as ignition timing, air-fuel ratio, and boost pressure in a direction that prevents knock from occurring. For example, in the published patent publication (Sho 61-215942), a cylinder pressure sensor is installed in each cylinder in a multi-cylinder engine, the occurrence of knock in each cylinder is detected from the output signals of these cylinder pressure sensors, and the detection signal is Accordingly, it has been shown that the ignition timing is controlled to the limit point at which knock occurs. In this type of control device, compared to the method of detecting the knock vibration of the cylinder of the engine using a single vibration sensor installed in the engine block, etc., a highly sensitive detection method that directly detects the knock vibration from the cylinder pressure is required. It becomes possible.

[Problem to be solved by the invention]

However, on the other hand, this method requires as many cylinder pressure sensors as the number of cylinders in the engine, which increases costs, and also has the disadvantage that sensor signal processing becomes complicated.

The present invention has been made in view of these problems, and is intended to detect the combustion state with high sensitivity using a minimum number of sensors in a multi-cylinder engine, and to efficiently control the cylinders. purpose.

[Means for Solving the Problem] [Operation] In order to achieve the above object, the control device for an internal combustion engine according to the present invention detects the combustion state of at least one specific cylinder in a multi-cylinder internal combustion engine. and the first one related to combustion in this particular cylinder.
The combustion control parameter of is set in advance to a value different from the combustion control parameter of other than the specific cylinder, and the second combustion control parameter different from the first combustion control parameter of the specific cylinder is controlled by detection of the combustion state, The second combustion control parameter other than the specific cylinder is controlled according to the detected amount or controlled amount in the specific cylinder.

[Embodiment] FIG. 1 shows a block diagram of an embodiment of the present invention. In Fig. 1, (1) is an engine with four cylinders arranged in series, from the first cylinder to the fourth cylinder, and each cylinder has injectors (71) to (71) that inject fuel into the intake pipe.
74) is installed, and an ignition coil Ω~(241) is connected to the spark plug of each cylinder.
is an in-cylinder pressure sensor, which is especially installed only in the first cylinder. (4) is a control circuit, and a block diagram showing its configuration is shown within the broken line.

(41) is a knock detection circuit that determines the presence or absence of knock from the output signal of the cylinder pressure sensor (8) and outputs a signal according to the amount of knock occurrence; (42) is a knock detection circuit that detects the knock detection circuit and the intake air pressure of the engine. An intake pressure sensor (6) to detect the intake air amount, and an air 70-sensor (8) to detect the intake air amount of the engine.
) is an A/D converter that converts an analog signal output from
), RAM (433), input/output boat (434)
, output capo) (435). Input/output port (-
is connected to the A/D converter (42) and the crank angle sensor (6), and the output capo (435) is connected to the ignition device (44) and the injector drive circuit (45). The ignition device (44) is further connected to the ignition coil 121) to the engine (44) based on the crank angle signal and cylinder identification signal of the crank angle sensor (6) mounted on the engine, based on the calculation command of the microcomputer (43). 1) Ignite each cylinder. Further, the injector drive circuit (45) drives the range filter based on the intake air amount signal from the air flow sensor (8) and based on the calculation command from the microcomputer (43).

Here, a ring-shaped piezoelectric type cylinder pressure sensor, for example, can be used as the cylinder pressure sensor (8).

As shown in FIG. 2, this cylinder pressure sensor (8) is installed between the cylinder head (9), which forms the earthen wall of the combustion cylinder of the engine (1), and the spark plug (to). Cylinder pressure sensor (
The output signal of 8) indicates the pressure inside the combustion chamber as shown in Figure 3, and from there it is possible to detect the absolute value of the pressure related to the combustion state, its fluctuations, and pressure vibrations due to knocking. Used as a state detector. Next, the knock detection circuit (41) includes a charge amplifier (412), a band pass filter (413), as shown in FIG.
), noise level detector (41), comparator (415)
, an integrator (416). 9 First, the output signal of the cylinder pressure sensor (8) is converted into a voltage value by the charge amplifier (412), the pressure vibration component due to knock is extracted by the bandpass filter (413), and then the output signal of the bandpass filter (413) is converted to a voltage value. The noise level detector (414) generates a threshold voltage for removing noise components other than knock contained in the noise level detector (414), and the comparator (
415) compares the output signal of the bandpass filter (413) with the threshold voltage of the noise level detector (414), and detects only the pressure vibration component due to knock. Then, the comparator (41) is operated by the integrator (416).
5) Integrate the output signal. Therefore, the knock detection circuit (
41) outputs a voltage according to the amount of knocking.

Next, the control operation of the above embodiment will be explained. FIG. 5 is a flowchart representing the control program stored in the ROM (432) of the microcomputer (43).

First, when the control circuit (4) is powered on by the key switch, the process starts from step (101) and then step (102) is executed. In this step (102), the input/output port is set to input mode or output mode, and after clearing the data in PAM (433), necessary data is initialized. RAM (43
3) is for temporarily storing calculation data in the control program shown in FIG. Step (103)
Now, calculate the rotation speed N of the engine (1) from the crank angle signal of the crank angle sensor (6), and calculate the rotation speed N of the engine (1) from the crank angle signal of the crank angle sensor (6).
) from the output value of the engine (1), and the intake air amount A from the output value of the air flow sensor (8). Then, step (104) is a ROM (432
), the basic ignition timing data θB corresponding to the rotational speed N and load LK calculated in step (103) are obtained from the basic ignition timing map according to the rotational speed and load stored in ), and from the basic fuel injection amount map. The basic fuel injection amount Qa corresponding to the air amount A is read out. In step (105), it is determined from the rotational speed N and the load whether or not it is in the operating range where knock control is performed, and if it is not in the knock control zone, step (105) is performed.
17) Move to K, set the fuel injection amount and ignition timing in step (113) with the fuel injection amount Q as a fist and the ignition timing θ as θB, and set the fuel injection amount and ignition timing in the injector drive circuit (45) and ignition device (44), respectively. Sends commands for fuel injection amount and ignition timing. Thereafter, the process returns to step (103) to repeat execution of the routine. If it is determined in step (105) that the area is in the knock control zone, step (106)
), the cylinder currently targeted for ignition timing calculation is identified from the cylinder identification signal of the crank angle sensor (5). Then, in step (107), it is determined whether or not the cylinder identified in step (106) is the first cylinder, and if it is not the first cylinder, the process moves to step (112)K, which will be described later. Also,
In the case of the first cylinder, the process proceeds to step (108), where the basic fuel injection amount for the first cylinder is reset to a new θB obtained by subtracting a predetermined value QO from the QB read in step (104). . That is, by setting the basic fuel injection amount of the first cylinder to be leaner by a predetermined value than the basic fuel injection amounts of the other cylinders, conditions are created in which knocking is likely to occur. Next, in step (109), it is determined from the output data of the knock detection circuit (41) stored in RAM (433) K for each predetermined crank angle of the first cylinder whether knock has occurred or not. If it is determined, step (110
) and clear the timer counter described below. Further, in step (111) K, the ignition timing retard control amount θR is added and updated by a predetermined angle Δθ. Then, in step (112), from the basic ignition timing θB to the retard control amount θn
A final ignition timing calculation is made by subtracting the step (
113), the ignition timing is set. As a result, the ignition timing of the first cylinder is retarded and the occurrence of knock is suppressed. On the other hand, if it is determined in step (109) that there is no knock, the process moves to step (114). In step (114), it is determined whether the count value M of the timer counter is greater than or equal to a predetermined count value. Here the timer counter is O
The clock pulse that operates the PU (431) is sent to the CPU.
counts, stores the count data in RAM (433), and updates the data at any time.

If the count value M is less than one, the process moves to step (112). In addition, if the count value M is one or more, step (115
) Advances by K, the count value of the timer counter, that is, RAM
Clear data M of C433). Furthermore, the process proceeds to step (116), where the retard control amount θB is updated by subtracting the predetermined angle Δθ. In other words, if no knock occurs during the period in which the timer counter counts only the knock, the retard control amount θ
3 is returned to the advance side by Δθ.

In this way, by setting the basic fuel injection amount of the first cylinder to the lean side pressure by QO, knocking becomes more likely to occur in the first cylinder. Knock is detected by the round internal pressure sensor (8)K installed in the first cylinder, and the ignition timing of the first cylinder is retarded to the knock limit by the control program. On the other hand, the ignition timing of cylinders other than the first cylinder is
Since the retard angle control is performed by the retard angle control amount θR obtained by the cylinder knock detection, a state in which no knock always occurs is maintained.

Here, since the basic fuel injection amount in the first cylinder is set to the lean side, knocking is more likely to occur.
The ignition timing of the first cylinder can be set to the same value as the other cylinders, and the ignition timing of the gold cylinder can be controlled with the same retard control amount. Therefore, the calculation of ignition timing setting in the computer (43) and the control circuit in the ignition device (44) can be simplified by controlling the ignition timing to be the same for all cylinders.

In the above embodiment, knock control is taken as an example of combustion control, but information obtained from the output signal of the cylinder pressure sensor (8), such as the maximum cylinder pressure value, the crank angle at the maximum cylinder pressure point, By using the indicated mean effective pressure, etc., it is possible to control not only the ignition timing but also combustion control parameters such as the air-fuel ratio and boost pressure using the control process according to the present invention.

Further, in the knock control, a vibration detector may be used instead of the cylinder pressure sensor to detect knock only in the first cylinder with high sensitivity.

Further, in the above embodiment, the cylinder pressure sensor is installed only in the first cylinder, but a plurality of cylinder pressure sensors may be installed in other cylinders as necessary. In this case, the knock detection circuit (
By providing an analog multiplexer in front of 41), knock signals for multiple cylinders can be input. In the control program shown in FIG. 5, step (
107) may be replaced with a determination as to whether or not the cylinder is equipped with an in-cylinder pressure sensor.

In addition, the ignition timing control of the cylinder without the cylinder pressure sensor does not follow the retard control amount of the cylinder with the cylinder pressure sensor.
The control may be performed using the output data of the knock detection circuit (41) or a retard control amount independently calculated from the retard control amount. In this case, in the control program shown in FIG. 5, in the branch from step (107) to step (n2), a step is provided to calculate the second retard control amount and ignition timing, and the program proceeds to step (n3). That's fine.

〔Effect of the invention〕

As explained above, according to the present invention, when controlling the combustion of a multi-cylinder engine, each cylinder can be efficiently and easily controlled using the minimum number of sensors required, without using sensors for the number of cylinders. The effect is that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is an engine installation diagram of the cylinder pressure sensor, Figure 3 is an output waveform diagram of the cylinder pressure sensor, Figure 4 is a block diagram of the knock detection circuit (41), and Figure 5 is a flowchart showing the control program in the embodiment. be.

Claims (1)

[Claims] In an internal combustion engine having a plurality of combustion cylinders, a combustion state detection means detects a combustion state of at least one specific cylinder, and a first combustion control parameter related to combustion in this specific cylinder is previously set for a combustion state related to a cylinder other than the specific cylinder. control parameter setting means for setting a value different from the parameter, and controlling a second combustion control parameter different from the first combustion control parameter of the specific cylinder according to the combustion state detection means, and controlling a second combustion control parameter different from the first combustion control parameter of the specific cylinder. A control device for an internal combustion engine, comprising: a control means for controlling the second combustion control parameter for cylinders other than the specific cylinder according to the combustion state detection amount or the control amount.