JP2580155B2 - Knock control control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a knock control controller for an electronically controlled engine.

[Prior art]

Conventionally, as a knock control device of this type, as shown in, for example, Japanese Patent Application Laid-Open No. 58-72643, a cylinder pressure maximum position is determined by a cylinder pressure signal detected by a cylinder pressure sensor and a signal of a crank angle sensor. The engine is operated at the maximum efficiency by determining whether the engine is operating at the maximum output by comparing it with a predetermined range value and appropriately adjusting the ignition timing, the fuel supply amount, and the exhaust gas recirculation amount according to the result. The engine was controlled to operate with stable and stable combustion, and the occurrence of knocking was prevented. Further, as disclosed in Japanese Patent Application Laid-Open No. 58-20077, the rate of increase is obtained from the in-cylinder pressure detected by the in-cylinder pressure sensor, and the occurrence of knocking is predicted from this increase rate to retard the ignition timing. In some cases, knocking is prevented from occurring.

[Problems to be solved by the present invention]

By the way, the conventional knock control device configured as described above has a problem that it is not possible to accurately detect occurrence of knocking in each operation region, and it is not possible to perform control according to the intensity of knocking that has occurred. Furthermore, if the octane number of the gasoline used changes,
Correspondingly, there is a problem that the retard amount of the ignition timing or the control amount of the supercharging pressure when knocking occurs cannot be appropriately controlled. The present invention can accurately detect knocking, appropriately control the retard amount of the ignition timing according to the degree of knocking that has occurred, and rewrite the ignition timing map based on the deviation of the number of knocking occurrences in each operation region. It is an object of the present invention to prevent knocking while always ensuring the maximum output.

[Means for solving the problems]

In order to achieve the above object, a knock control control apparatus for an internal combustion engine according to the present invention includes, in an internal combustion engine including an in-cylinder pressure sensor and a crank angle sensor attached to a combustion chamber of an engine, a signal from both sensors. An in-cylinder pressure monitoring unit that calculates an in-cylinder pressure waveform with respect to a crank angle, a knock determination unit that calculates a pressure change rate from the in-cylinder pressure waveform to determine whether knocking has occurred, and the knock determination unit. In the knock count counter map for counting the detected knock count for each operation area, and in the knock count counter map, when the number of the operation areas in which the counted number of knocks exceeds an allowable value is equal to or greater than a predetermined value, the entire knock area is determined. An ignition timing map that rewrites the ignition timing in the retard direction, and an ignition timing read from the ignition timing map. Therefore characterized in that provided an ignition timing control means for controlling the ignition timing.

[Action]

Based on the above configuration, the knock control control device for the internal combustion engine according to the present invention obtains a change value of the in-cylinder pressure by the in-cylinder pressure sensor, and counts the number of abnormal occurrences of the in-cylinder pressure change value for each operation region. The number of occurrences of abnormalities in each operating area is compared with the allowable value of each operating area stored in the form of a map in advance, and when the number of operating areas exceeding the allowable value exceeds a predetermined number, the octane number of refilled gasoline Is changed, and the ignition timing map is rewritten in the read direction over the entire region until the next fuel supply, and optimal ignition timing control is performed for each region to prevent knocking from occurring.

【Example】

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First
FIG. 2 is a block diagram of an ignition timing control device including knock control, and FIG. 2 is a flowchart showing the operation of the present invention. In the figure, reference numeral 1 denotes an engine, 2 denotes an intake pipe, 3 denotes an exhaust pipe, an intake pipe 2 is provided with an injector 4, and a combustion chamber 1a of the engine 1 is provided with a spark plug 5 and an in-cylinder pressure sensor 6. ing. The exhaust pipe 3 has a turbocharger 7
And a compressor 7b driven by the turbine 7a is disposed in the intake pipe 2. A wastegate valve 8 for controlling the supercharging pressure of the compressor 7b is provided in a bypass passage 3a that bypasses the turbine 7a, and the wastegate valve 8 is controlled by an actuator 9. Reference numeral 10 denotes a distributor which applies ignition energy to the ignition plug 5 at a predetermined timing, that is, at a predetermined crank angle position. Then, a crank angle sensor provided on the crankshaft 1b
The output signal from 11 and the output signal from in-cylinder pressure sensor 6 output via charge amplifier 12 are input to control unit 20 comprising a microcomputer. The control unit 20 includes an in-cylinder pressure monitoring means 21 as a knock control function, a knock determination means 22, an ignition timing control means 24, and a general control circuit 26 such as an air-fuel ratio control. Output signals from the in-cylinder pressure sensor 6 and the crank angle sensor 11 are input to the in-cylinder pressure monitoring unit 21, and the in-cylinder pressure monitoring unit 21 detects an in-cylinder pressure P detected by the in-cylinder pressure sensor 6, Based on the crank position θ from the crank angle sensor 11, an in-cylinder pressure waveform is obtained, and an output signal from the in-cylinder pressure monitoring means 21 is input to the knock determination means 22. Change value of pressure P dp / dθ
Is calculated, and the maximum value (dp / dθ) MAX is compared with a preset allowable value (dp / dθ) SET. If the allowable value is exceeded, it is determined that knocking has occurred, and the deviation from the allowable value △ dp / dθ
Is output. In the ignition timing map 23 composed of a memory, the deviation △ dp / dθ
The retard amount at the time of occurrence of knocking is stored in several ranks in accordance with the engine speed, and the optimum ignition timing for the engine speed is stored in the form of a map in advance. Further, a memory area in which the ignition timing map can be rewritten is prepared. The output signal from knock determination means 22 is used as ignition timing control means.
The ignition timing control means 24 reads the ignition timing corrected by the retard amount corresponding to the deviation △ dp / dθ from the knock determination means 22 from the knock determination means 22 from the ignition timing map 23, and outputs the ignition timing signal to the distributor 10. I do. The knocking frequency counter map 25 composed of a RAM memory, etc., counts the number of knocking occurrences for each operation region prepared in the form of a map, monitors the operation at a constant time interval, and sets a predetermined knocking frequency allowable for each region. If the number of operating regions exceeding the allowable value exceeds the predetermined value, the command is issued to rewrite the entire region of the ignition timing map 23 as a change in the octane number of the gasoline being used, in the direction of retarding. Next, the operation of the present invention configured as described above will be described with reference to the flowchart shown in FIG. Simultaneously with the start of operation, the control unit 20 sets a knocking limit in each region with respect to an operation condition map including the engine speed N and the basic fuel injection pulse width Tp in the knock count counter map 25 prior to operation, that is, , The knocking count allowable value is set in advance. Further, the ignition timing map 23 stores in advance the optimal ignition timing determined by the engine speed N when knocking does not occur in the form of a map, and the retard amount for retarding the ignition timing when knocking occurs is determined by the knocking. Is divided into several ranks in accordance with the size of and stored in advance. The in-cylinder pressure monitoring means 21 reads the in-cylinder pressure P detected by the in-cylinder pressure sensor 6 via the charge amplifier 12 and the crank angle θ from the crank angle sensor 11, and the in-cylinder pressure waveform for each cycle. Is obtained (step S101). From this in-cylinder pressure waveform, knock determination means 22 determines in-cylinder pressure P
Is calculated and the maximum value (dp / dθ)
MAX is detected (step S102), and is compared with a preset allowable value (dp / dθ) SET (step S10).
3). If the tolerance is exceeded, the deviation △ dp / dθ
Is calculated by △ dp / dθ = (dp / dθ) MAX− (dp / dθ) SET (step S104), the control level is determined and output to the ignition timing control means 24 (step S105). If the maximum value (dp / dθ) MAX of the in-cylinder pressure change value does not exceed the allowable value, the ignition timing control means 24 outputs the ignition timing map 23 based on the signal from the crank angle sensor 11.
The optimum ignition timing is read out from the controller, the ignition timing signal is output to the distributor 10, and the ignition plug 5 is applied to the optimum ignition timing to maximize the engine output. On the other hand, if the allowable value (dp / dθ) is exceeded,
In accordance with the control level corresponding to the deviation △ dp / dθ, the ignition timing obtained by correcting the optimum ignition timing of the ignition timing map 23 with the retard amount of the rank classified based on the control level is read, and this ignition timing signal is sent to the distributor 10. Output (Step S106). In this case, since the retard amount for delaying the ignition timing is set according to the magnitude of knocking, for example, when the deviation is extremely large, the ignition timing is fully retarded and the waste gate valve 8 is opened to increase the supercharging pressure. To avoid knocking immediately and prevent heavy knocking. On the other hand, when the deviation is small, it is determined that the engine is right knocking or immediately before knocking, and control is performed so that the ignition timing is slightly retarded, thereby achieving both maximum performance of engine output and prevention of knocking. Next, when it is determined that knocking has occurred and the above-described control has been performed, the knocking number counter map 25 counts and records the number of knocking for each operation region prepared in advance as an N-Tp map (step S107). A comparison is made with a knocking count allowable value set for each area at certain time intervals (step S108). If the number of knocking-prone areas where the number of knockings exceeds the allowable value is smaller than a predetermined number and the occurrence of knocking is a specific area (step S1).
09), rewrite the ignition timing map of the knocking frequent occurrence area stored in the ignition timing map 23 (step S11)
0). On the other hand, if knocking occurs more than the allowable value in a large number of regions equal to or greater than the predetermined number, it is determined that the octane number of the gasoline used has decreased for some reason and is stored in the ignition timing map 23 in the entire operation region. The ignition timing is rewritten in the spare memory area in the direction in which the ignition timing is retarded (step S111), and the vehicle travels in accordance with the ignition timing map rewritten in the retard direction until the next refueling. In such a case, an alarm device (not shown) warns the driver, instructs the user to check the gasoline, and sets the ignition timing map after refueling.
23 is returned to the normal state. When knocking frequently occurs only in a specific region, not only the base setting in that region is rewritten, but also the control of the supercharging pressure may be changed.

【The invention's effect】

As described above, according to the present invention, the in-cylinder pressure waveform is monitored by the signals from the in-cylinder pressure sensor and the crank angle sensor provided in the combustion chamber of each cylinder, and the pressure change rate is monitored.
The maximum value of dp / dθ is compared with the permissible value to determine the presence or absence of knock, the number of knocks is counted for each operation region and monitored, and the ignition timing map is partially determined according to the range of the occurrence region. Alternatively, since rewriting is performed in the entire range, knocking detection is accurate, and even when the octane number of the gasoline used changes, it is possible to ensure engine output and prevent knocking. In addition, since the base setting of the ignition timing map can be changed according to the occurrence of knocking, it is possible to travel while learning the appropriate setting for knocking, and to more effectively avoid knocking. Can be.

[Brief description of the drawings]

1 and 2 show one embodiment of the present invention.
FIG. 1 is a block diagram of the knock control device, and FIG. 2 is a flowchart showing the operation of the present invention. 6 ... in-cylinder pressure sensor, 11 ... crank angle sensor, 20 ...
... Control unit, 21 ... In-cylinder pressure monitoring means, 22 ...
... Knock determination means, 23... Ignition timing map, 24... Ignition timing control means, 25.

Claims (1)

(57) [Claims] 1. An internal combustion engine having an in-cylinder pressure sensor and a crank angle sensor attached to a combustion chamber of an engine, wherein the in-cylinder pressure for calculating the in-cylinder pressure waveform with respect to the crank angle based on signals from the two sensors. Viewing means, knock determination means for calculating the pressure change rate from the in-cylinder pressure waveform to determine whether knocking has occurred, and a knock number counter for counting the number of knocks detected by the knock determination means for each operating region An ignition timing map for rewriting the ignition timing in the entire region in the retard direction when the number of operating regions in which the counted number of knocks exceeds an allowable value is equal to or greater than a predetermined value. Ignition timing control means for controlling the ignition timing according to the ignition timing read from the map. Knock control control device for an internal combustion engine and butterflies.