JP2009270523A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device for an internal combustion engine capable of reducing a frequency of the occurrence of knocking. <P>SOLUTION: EFI-ECU executes a program provided with a step S100 for determining whether knocking occurs or not, a step S102 for retarding ignition timing by a predetermined retardation angle when it is determined that the knocking occurs (Yes in S100), a step S104 for advancing ignition timing by a predetermined advancement angle when it is determined that the knocking does not occur (No in S100), and a step S108 for prohibiting the renewal of a KCS learning value indicating corrected ignition timing if an alcohol concentration DEN in fuel is not lower than a predetermined concentration (Yes in S106). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control device, and more particularly to a technique for prohibiting learning of ignition timing in a knock control system (KCS).

  Conventionally, an FFV (Flexible Fuel Vehicle) using a fuel in which alcohol (for example, ethanol) is mixed with gasoline or a fuel composed only of alcohol (hereinafter also referred to as alcohol fuel) is known. Alcohol fuel has different characteristics from gasoline. For example, alcohol fuel has a higher octane number than gasoline. Therefore, it is difficult for knocking to occur. Therefore, the ignition timing is easily advanced by the knock control system.

  The knock control system determines whether or not knock has occurred based on the output signal of the knock sensor, and if it is determined that knock has occurred, the basic ignition timing determined according to the operating state of the internal combustion engine. This is a system that retards the ignition timing. On the other hand, if it is determined that knock has not occurred, the ignition timing is advanced. The retard amount from the basic ignition timing, that is, the ignition timing corrected by the knock control system is learned (stored) as a KCS learning value. Therefore, the ignition timing delayed from the basic ignition timing by the KCS learning value can be the actual ignition timing.

  The KCS learning value is stored in a RAM (Random Access Memory) or the like of an ECU (Electronic Control Unit) and is referred to when the internal combustion engine is operated next time. Therefore, for example, even if a fuel with a low alcohol concentration or gasoline without alcohol is supplied after FFV travels using a fuel with a high alcohol concentration, the ignition timing immediately after refueling will be compared to the alcohol concentration before refueling. Therefore, the ignition timing remains suitable. In this case, knocking may occur frequently immediately after refueling.

Therefore, after refueling, the knock control device described in Japanese Patent Application Laid-Open No. 2003-184615 (Patent Document 1) is used so that the ignition timing is quickly suitable for the alcohol concentration in the fuel after refueling. As described above, there has been proposed a technique for increasing the update speed of the KCS learning value when refueling is performed.
JP 2003-184615 A

  However, even if the update speed of the KCS learning value is increased, knocking may occur frequently until the knock control system operates normally and learning of the KCS learning value is completed.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a control device for an internal combustion engine that can reduce the frequency of occurrence of knocking.

  According to a first aspect of the present invention, there is provided a control device for an internal combustion engine, a means for detecting an alcohol concentration in fuel supplied to the internal combustion engine, a means for determining whether or not a knock has occurred, and a knock has occurred. A control means for controlling the ignition timing by correcting the ignition timing according to whether or not the ignition timing is stored and storing the ignition timing as a learning value, and when the alcohol concentration in the fuel is higher than a predetermined value And a prohibiting means for prohibiting the update of the learning value while continuing the correction of the ignition timing.

  According to this configuration, the ignition timing is controlled by correcting the ignition timing according to whether or not knocking has occurred, and storing the ignition timing as a learned value. When the alcohol concentration in the fuel of the internal combustion engine is higher than a predetermined value, the update of the learning value is prohibited while the correction of the ignition timing is continued. Thereby, only the update of the learning value can be stopped in the knock control system. Therefore, the ignition timing corrected so as to be suitable for a fuel having a high alcohol concentration can be prevented from being used in the subsequent operation of the internal combustion engine. As a result, immediately after fuel having a low alcohol concentration or gasoline not mixed with alcohol is supplied, the ignition timing corrected so as to be suitable for a fuel having a high alcohol concentration is not used, and knocking is prevented. It is possible to provide a control device for an internal combustion engine that can reduce the frequency of occurrence.

  In the control apparatus for an internal combustion engine according to the second invention, in addition to the configuration of the first invention, the control means corrects the ignition timing to be retarded when it is determined that knocking has occurred, Means for correcting the ignition timing to advance when it is determined that knocking has not occurred is included.

  According to this configuration, when it is determined that knocking has occurred, the ignition timing is retarded. Thereby, the combustion temperature in a cylinder can be reduced and the frequency which a knock generate | occur | produces can be reduced. If it is determined that knocking has not occurred, the ignition timing is advanced. Thereby, the combustion temperature in a cylinder can be made high and the output of an internal combustion engine can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  With reference to FIG. 1, an engine system of a vehicle equipped with a control device according to an embodiment of the present invention will be described. Although FIG. 1 shows an in-line four-cylinder gasoline engine as an engine, the present invention is not limited to such an engine, and various types of engines such as a V-type 6-cylinder engine and a V-type 8-cylinder engine can be used. Applicable to engine.

  The engine 10 is an internal combustion engine driven by alcohol fuel containing alcohol (for example, ethanol) in addition to gasoline or gasoline not containing alcohol. As shown in FIG. 1, the engine 10 includes four cylinders 112, and each cylinder 112 is connected to a common surge tank 30 via a corresponding intake manifold 20. The surge tank 30 is connected to the air cleaner 50 via the intake duct 40. A throttle valve 70 driven by an electric motor 60 is disposed in the intake duct 40. Each cylinder 112 is connected to a common exhaust manifold 80, and this exhaust manifold 80 is connected to a three-way catalytic converter 90.

  Each cylinder 112 is provided with a spark plug 110, an intake port or / and an injector 120 that injects fuel into the intake passage. Spark plug 110 and injector 120 are controlled based on an output signal from EFI (Electronic Fuel Injection) -ECU 300.

  Each injector 120 is connected to a delivery pipe 130, and the delivery pipe 130 is connected to an electric motor driven fuel pump 150 via a fuel pressure regulator 140. The fuel pressure regulator 140 is configured to return a part of the fuel discharged from the fuel pump 150 to the fuel tank 200 when the fuel pressure of the fuel discharged from the fuel pump 150 becomes higher than a predetermined set fuel pressure. Therefore, the fuel pressure supplied to the injector 120 is prevented from becoming higher than the set fuel pressure.

  A pipe 210 connected to the fuel pump 150 is inserted into the fuel tank 200. The fuel pump 150 sucks up the fuel in the fuel tank 200 through the pipe 210. The greater the number of revolutions of the fuel pump 150, the greater the amount of fuel drawn.

  The EFI-ECU 300 includes a digital computer, and includes a clock 310, a ROM (Read Only Memory) 320, a RAM 330, and a CPU (Central Processing Unit) 340.

  In the present embodiment, electric power is supplied from battery 302 to EFI-ECU 300. When the ignition switch 304 is turned on, the EFI-ECU 300 is activated. On the other hand, when the ignition switch 304 is turned off, the EFI-ECU 300 enters a dormant state.

  Further, when the ignition switch 304 is switched from on to off, the engine 10 is stopped. When the ignition switch 304 is switched from OFF to ON, the engine 10 is started.

The output voltage of the air-fuel ratio sensor 350 is input to the EFI-ECU 300. The air-fuel ratio sensor 350 is a global air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage proportional to the air-fuel ratio of the air-fuel mixture burned by the engine 10. The air-fuel ratio sensor 350 may be an O ₂ sensor that detects whether the air-fuel ratio of the air-fuel mixture burned by the engine 10 is rich or lean with respect to the stoichiometric air-fuel ratio. Good.

  In the present embodiment, EFI-ECU 300 calculates a feedback correction amount for the total fuel injection amount based on the output voltage of air-fuel ratio sensor 350. Further, when a predetermined learning condition is satisfied, a learning value of the feedback correction amount (a value representing a constant deviation amount of the fuel injection amount) is calculated. Note that the feedback correction amount and the method for calculating the learning value thereof may be obtained by using a commonly used technique, and thus detailed description thereof will not be repeated here.

  Further, the output voltage of knock sensor 360 is input to EFI-ECU 300. Knock sensor 360 generates an output voltage corresponding to the intensity of vibration of engine 10. For example, the EFI-ECU 300 determines that knock has occurred when the magnitude of vibration detected by the knock sensor 360 is greater than a threshold value, and knocks when the magnitude of vibration is less than the threshold value. A knock control system that determines that no occurrence has occurred is implemented. Note that the method for determining whether or not knocking has occurred is not limited to the above method.

  If it is determined that knocking has occurred, the ignition timing is retarded from the basic ignition timing determined according to the operating state of the engine 10 (for example, the engine speed and the intake air amount). If it is determined that knocking has occurred, the ignition timing is advanced. The retard amount from the basic ignition timing, that is, the ignition timing corrected by the knock control system is learned (stored) as a KCS learning value. Therefore, the ignition timing delayed from the basic ignition timing by the KCS learning value can be the actual ignition timing. However, as will be described later, when the update of the KCS learning value is prohibited, the ignition timing retarded by the KCS learning value from the basic ignition timing may differ from the actual ignition timing. The KCS learning value is stored in the RAM 330 of the EFI-ECU 300 and read when the engine 10 is operated next time or later.

  Further, the EFI-ECU 300 receives a signal indicating the remaining amount of alcohol fuel MASS from a sender gauge (fuel remaining amount meter) 370 that generates a signal indicating the remaining amount of alcohol fuel MASS in the fuel tank 200. The remaining amount MASS of the alcohol fuel is displayed on the fuel meter 372.

  Further, the EFI-ECU 300 receives a signal indicating the alcohol concentration DEN in the fuel from the concentration sensor 380. The alcohol concentration DEN may be estimated without using the concentration sensor 380.

  For example, the higher the alcohol concentration of the fuel, the smaller the amount of gasoline injected from the injector 120. Therefore, the air-fuel ratio becomes lean with respect to the target air-fuel ratio. In this case, the feedback correction amount is calculated so as to increase the fuel injection amount. Therefore, the alcohol concentration DEN may be estimated according to the learned value of the feedback correction amount of the air-fuel ratio. Further, the alcohol concentration DEN may be estimated according to whether or not refueling has been performed.

  The function of the EFI-ECU 300 will be described with reference to FIG. Note that the functions described below may be realized by hardware or may be realized by software.

  EFI-ECU 300 includes a knock control unit 400 and a prohibition unit 402. Knock control unit 400 has a function as a knock control system. That is, knock control unit 400 determines whether or not a knock has occurred. Further, knock control unit 400 corrects the ignition timing according to whether or not a knock has occurred, and controls the ignition timing by learning the corrected ignition timing as a KCS learning value.

  When the alcohol concentration in the fuel is equal to or higher than a predetermined concentration, the prohibiting unit 402 prohibits updating of the KCS learning value while continuing the correction of the ignition timing by the knock control unit 400.

  With reference to FIG. 3, a control structure of a program executed by EFI-ECU 300 which is the control device according to the present embodiment will be described. The program described below is recorded in the ROM 320, for example. The program executed by the EFI-ECU 300 may be recorded on a recording medium such as a CD (Compact Disc) or a DVD (Digital Versatile Disc) and distributed to the market.

  In step (hereinafter, step is abbreviated as S) 100, EFI-ECU 300 determines whether or not knocking has occurred based on the magnitude of vibration detected by knock sensor 360. If it is determined that knocking has occurred (YES in S100), the process proceeds to S102. If not (NO in S100), the process proceeds to S104.

  In S102, EFI-ECU 300 retards the ignition timing by a predetermined retard amount. In S104, EFI-ECU 300 advances the ignition timing by a predetermined advance amount.

  In S106, EFI-ECU 300 determines whether alcohol concentration DEN is equal to or higher than a predetermined concentration. If alcohol concentration DEN is equal to or higher than a predetermined concentration (YES in S106), the process proceeds to S108. If not (NO in S106), the process proceeds to S110.

  In S108, EFI-ECU 300 prohibits the update of the KCS learning value. In S110, EFI-ECU 300 updates the KCS learning value.

  An operation of the control device according to the present embodiment based on the above-described structure and flowchart will be described.

  During operation of engine 10, it is determined whether knock has occurred or not based on the intensity of vibration detected by knock sensor 360 (S100). If it is determined that knock has occurred (YES in S100), the ignition timing is retarded by a predetermined retard amount (S102). If it is determined that knock has not occurred (NO in S100), the ignition timing is advanced by a predetermined advance amount (S104).

  If the alcohol concentration DEN in the fuel is lower than a predetermined concentration (NO in S106), the KCS learning value is updated (S110). That is, the corrected ignition timing is stored as a new KCS learning value.

  By the way, alcohol fuel has a higher octane number than gasoline. Therefore, the higher the alcohol concentration DEN, the less likely knocking occurs. Therefore, the ignition timing is easily advanced by the knock control system. Therefore, if the ignition timing when the engine 10 is operated using a fuel with a high alcohol concentration is learned as a KCS learning value, it can be said that the ignition timing is early with respect to fuel with a low alcohol concentration or gasoline without alcohol. Therefore, after the engine 10 is operated using a fuel having a high alcohol concentration, if fuel having a low alcohol concentration or gasoline not mixed with alcohol is supplied, knocking may occur frequently.

  Therefore, in the embodiment, when the alcohol concentration DEN in the fuel is equal to or higher than a predetermined concentration (YES in S106), updating of the KCS learning value is prohibited (S108). Thereby, in the knock control system, only the update of the KCS learning value can be stopped while continuing the correction of the ignition timing. Therefore, the ignition timing corrected so as to be suitable for the fuel having a high alcohol concentration can be prevented from being used in the subsequent operation of the engine 10. As a result, immediately after fuel having a low alcohol concentration DEN or gasoline not mixed with alcohol is supplied, ignition timing corrected to be suitable for fuel having a high alcohol concentration DEN is not used, The frequency of knocking can be reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram of an engine system. It is a functional block diagram of EFI-ECU. It is a flowchart which shows the control structure of the program which EFI-ECU performs.

Explanation of symbols

  10 engine, 20 intake manifold, 30 surge tank, 40 intake duct, 42 air flow meter, 50 air cleaner, 60 electric motor, 70 throttle valve, 80 exhaust manifold, 90 three-way catalytic converter, 110 spark plug, 112 cylinder, 120 injector, 130 delivery pipe, 140 fuel pressure regulator, 150 fuel pump, 200 fuel tank, 210 pipe, 300 EFI-ECU, 302 battery, 304 ignition switch, 310 clock, 350 air-fuel ratio sensor, 360 knock sensor, 370 sender gauge, 372 fuel Meter, 380 Density sensor, 400 Knock control part, 402 Prohibited part.

Claims (2)

A control device for an internal combustion engine,
Means for detecting an alcohol concentration in a fuel supplied to the internal combustion engine;
Means for determining whether a knock has occurred;
Control means for controlling the ignition timing by correcting the ignition timing according to whether or not knocking has occurred and storing the ignition timing as a learning value;
A control device for an internal combustion engine, comprising: prohibiting means for prohibiting updating of the learned value while continuing correction of ignition timing when the alcohol concentration in the fuel is higher than a predetermined value.   The control means corrects the ignition timing to be retarded when it is determined that the knock has occurred, and corrects the ignition timing to be advanced when it is determined that the knock has not occurred. The control apparatus for an internal combustion engine according to claim 1, comprising means for

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