JP2009047067A - Control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain deterioration of drivability or exhaust emission caused by mixing of different fuel when the unusable different fuel is mixed into fuel supplied to an engine. <P>SOLUTION: When it is determined that the different fuel is mixed into the fuel supplied into the engine 11, a mixing ratio of the different fuel is estimated. Not during air-fuel ratio feedback control (during open loop control), a fuel injection amount is corrected and excess or insufficient fuel for contributing to combustion is restrained in accordance with that a ratio of flame-retardant fuel with respect to injection fuel is varied in correspondence with the mixing ratio of the different fuel, and thereby, deterioration of the combustion state is restrained, and deterioration of drivability is suppressed. During air-fuel ratio feedback control, a target air-fuel ratio is corrected and is set within a range of the purification window of a catalyst 25 in accordance with that a theoretical air-fuel ratio is varied in correspondence with the mixing ratio of the different fuel and the purification window of the catalyst 25 is varied, and thus, deterioration of the exhaust emission is suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device for an internal combustion engine that improves a control method in the case where different types of fuel are mixed in the fuel supplied to the internal combustion engine.

Since the properties of the fuel used in the internal combustion engine may vary depending on the region, season, etc., as described in Patent Document 1 (Japanese Patent Laid-Open No. 3-179150), the fuel supplied to the internal combustion engine There is a type in which a heavy / lightness degree (fuel property) is detected by a heavy / lightness sensor, and a fuel injection amount is corrected in accordance with the heavy / lightness degree of fuel.
JP-A-3-179150 (first page, etc.)

  By the way, the internal combustion engine includes a gasoline engine using gasoline and a diesel engine using light oil. In recent years, since the number of self-stands where the driver refuels himself / herself is increasing, there is a possibility that the driver will accidentally refuel the gasoline engine vehicle with light oil, which is a different kind of unusable fuel. Moreover, there is a possibility that poor fuel obtained by intentionally mixing different fuels such as light oil and kerosene into gasoline is supplied. Depending on the region and season, etc., the gasoline's heavy and lightness (fuel properties) may be different. By using the technology of the above-mentioned Patent Document 1, etc., the gasoline engine vehicle is supplied with gasoline with different heavy and lightness (fuel properties). Can be operated normally.

  On the other hand, even if different types of fuel such as light oil and kerosene and poor fuel are supplied to the gasoline engine vehicle, the fuel is supplied with some gasoline remaining in the fuel tank. If the mixing ratio of dissimilar fuel to gasoline in the fuel tank is small, the engine can be operated by ignition timing control, etc., but the ratio of flame retardant fuel to injected fuel increases as the mixing ratio of dissimilar fuel increases. As the amount of fuel that contributes to combustion decreases and the combustion state of the engine deteriorates, the engine rotation becomes unstable and drivability deteriorates.In the worst case, the engine stops and the vehicle cannot run. There is also a possibility.

  In recent electronically controlled engine control systems, an exhaust gas purification catalyst is installed in the exhaust pipe, and an exhaust gas sensor (such as an air-fuel ratio sensor or an oxygen sensor) is installed upstream of the catalyst. Air-fuel ratio feedback control that feedback-controls the air-fuel ratio (fuel injection amount and intake air amount) of the air-fuel mixture so that the air-fuel ratio of the exhaust gas matches the target air-fuel ratio (for example, the theoretical air-fuel ratio) based on the output of the exhaust gas sensor By executing the control, the exhaust gas purification efficiency of the catalyst is improved by controlling the air / fuel ratio of the exhaust gas to be within the purification window of the catalyst (in the air / fuel ratio range where the exhaust gas purification efficiency is high).

  However, when different types of fuel are mixed into the gasoline supplied to the engine, the stoichiometric air-fuel ratio changes (for example, the stoichiometric air-fuel ratio in the case of 100% gasoline is about 14.7, but the stoichiometric air-fuel ratio in the case of 100% diesel oil. The fuel ratio is about 14.4). When the stoichiometric air-fuel ratio changes, the catalyst purification window changes accordingly. Therefore, when different fuels are mixed into gasoline, the same target air-fuel ratio as that before the different fuels are mixed (for example, the theoretical air-fuel ratio in the case of 100% gasoline) If the air-fuel ratio feedback control is executed in this manner, the air-fuel ratio of the exhaust gas may be out of the range of the catalyst purification window, the exhaust gas purification efficiency of the catalyst may be reduced, and the exhaust emission may be deteriorated.

  The present invention has been made in consideration of these circumstances. Accordingly, the object of the present invention is to provide drivability by mixing different types of fuel when the different types of fuel are mixed in the fuel supplied to the internal combustion engine. It is an object of the present invention to provide a control device for an internal combustion engine that can suppress deterioration of exhaust gas and exhaust emission.

  In order to achieve the above object, the invention according to claim 1 estimates the mixing ratio of the different fuel mixed in the fuel supplied to the internal combustion engine by the different fuel mixing ratio estimating means, and estimates the different fuel mixing ratio. The fuel injection amount is corrected by the fuel injection amount correction means in accordance with the mixing ratio of the different fuel estimated by the means.

  In this configuration, when different types of fuel are mixed into the fuel supplied to the internal combustion engine, the fuel injection amount is corrected in accordance with the change in the ratio of the flame-retardant fuel to the injected fuel according to the mixing rate of the different types of fuel. Thus, excess or deficiency of the amount of fuel contributing to combustion can be prevented. Thereby, the deterioration of the combustion state by mixing of different fuels can be suppressed, and the deterioration of drivability can be suppressed.

  The invention according to claim 1 is applied to a gasoline engine that uses gasoline as a fuel as in claim 2, and when estimating the mixing ratio of at least one of light oil, kerosene, and heavy oil as a different fuel, It is preferable to correct the fuel injection amount to the increase side as the mixing ratio of the different types of fuel increases.

  In general, when different types of fuel such as light oil, kerosene, and heavy oil are mixed in gasoline, the higher the mixing rate of the different types of fuel, the higher the proportion of flame retardant fuel to the injected fuel. If the fuel injection amount is corrected to the increase side, the fuel injection amount is corrected to the increase side corresponding to the increase in the ratio of flame retardant fuel to the injected fuel as the mixing ratio of different fuel increases, contributing to combustion It is possible to reliably prevent an excess or deficiency of the amount of fuel to be performed.

  Further, as in claim 3, the air-fuel ratio (fuel injection amount or intake air amount) is set so that the air-fuel ratio of the exhaust gas matches the target air-fuel ratio based on the output of the exhaust gas sensor provided in the exhaust passage of the internal combustion engine. In the case of a system that performs air-fuel ratio feedback control for feedback control, the target air-fuel ratio correction means corrects the target air-fuel ratio according to the mixture ratio of the different fuel estimated by the different fuel mixture ratio estimation means during the air-fuel ratio feedback control. You may make it do.

  In this way, when different types of fuel are mixed in the fuel supplied to the internal combustion engine, the theoretical air-fuel ratio changes according to the mixing ratio of the different types of fuel, and the catalyst purification window (exhaust gas purification efficiency becomes higher). The target air-fuel ratio can be corrected within the range of the purification window of the catalyst by correcting the target air-fuel ratio in response to a change in the increasing air-fuel ratio). As a result, even when the heterogeneous fuel is mixed and the stoichiometric air-fuel ratio is changed, the air-fuel ratio of the exhaust gas can be controlled by the air-fuel ratio feedback control so that it falls within the range of the catalyst purification window. The deterioration of exhaust gas purification efficiency of the catalyst due to can be suppressed and deterioration of exhaust emission can be suppressed.

  The invention according to claim 3 is applied to a gasoline engine that uses gasoline as a fuel as in claim 4, and when estimating the mixing ratio of at least one of light oil, kerosene, and heavy oil as a different fuel, It is preferable to correct the target air-fuel ratio to the decreasing side (rich side) as the mixing ratio of the different fuel becomes higher.

  In general, when different types of fuel such as light oil, kerosene, and heavy oil are mixed in gasoline, the higher the mixing ratio of the different types of fuel, the smaller the stoichiometric air-fuel ratio becomes, and the purification window of the catalyst decreases in the air-fuel ratio (rich direction). Therefore, if the target air-fuel ratio is corrected to decrease as the mixing ratio of the different fuel increases, the theoretical air-fuel ratio decreases as the mixing ratio of the different fuel increases, and the purification window of the catalyst changes in the decreasing direction of the air-fuel ratio. In response to this, the target air-fuel ratio can be corrected to the decreasing side, and the target air-fuel ratio can be accurately set within the range of the catalyst purification window.

Hereinafter, an embodiment in which the best mode for carrying out the present invention is applied to a gasoline engine (an engine using gasoline as fuel) will be described.
First, a schematic configuration of the entire engine control system will be described with reference to FIG.

  An air cleaner 13 is provided at the most upstream portion of the intake pipe 12 of the engine 11 that is an internal combustion engine, and an air flow meter 14 that detects the intake air amount is provided downstream of the air cleaner 13. A throttle valve 16 whose opening is adjusted by a motor 15 and a throttle opening sensor 17 for detecting the opening (throttle opening) of the throttle valve 16 are provided on the downstream side of the air flow meter 14.

  Further, a surge tank 18 is provided on the downstream side of the throttle valve 16, and an intake manifold 20 for introducing air into each cylinder of the engine 11 is provided in the surge tank 18. A fuel injection valve 21 for injecting fuel is attached in the vicinity of the intake port of the intake manifold 20 of each cylinder. An ignition plug 22 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 22.

  On the other hand, the exhaust pipe 23 of the engine 11 is provided with an exhaust gas sensor 24 (air-fuel ratio sensor, oxygen sensor, etc.) for detecting the air-fuel ratio or rich / lean of the exhaust gas. A catalyst 25 such as a three-way catalyst for purifying gas is provided.

  A cooling water temperature sensor 26 that detects the cooling water temperature and a knock sensor 29 that detects knocking are attached to the cylinder block of the engine 11. A crank angle sensor 28 that outputs a pulse signal every time the crankshaft 27 rotates by a predetermined crank angle is attached to the outer peripheral side of the crankshaft 27. Based on the output signal of the crank angle sensor 28, the crank angle and engine The rotation speed is detected.

  A fuel pump 31 that pumps up fuel is provided in a fuel tank 30 that stores fuel (gasoline). The fuel discharged from the fuel pump 31 is sent to the delivery pipe 33 through the fuel pipe 32 and is distributed from the delivery pipe 33 to the fuel injection valve 21 of each cylinder. A filter 34 and a pressure regulator 35 are connected in the vicinity of the fuel pump 31 in the fuel pipe 32, and the discharge pressure of the fuel pump 31 is adjusted to a predetermined pressure by the pressure regulator 35. Is returned to the fuel tank 30 by the fuel return pipe 36.

  The outputs of the various sensors described above are input to a control circuit (hereinafter referred to as “ECU”) 37. The ECU 37 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount of the fuel injection valve 21 can be changed according to the engine operating state. The ignition timing of the spark plug 22 is controlled.

  At this time, the ECU 37 sets the air-fuel ratio (the air-fuel ratio of the air-fuel mixture) so that the air-fuel ratio of the exhaust gas matches the target air-fuel ratio based on the output of the exhaust gas sensor 24 when a predetermined air-fuel ratio F / B control execution condition is satisfied. The air-fuel ratio F / B control is executed to F / B control the fuel injection amount and the intake air amount). Here, “F / B” means “feedback” (hereinafter the same).

  By the way, even if different types of fuel such as light oil or kerosene or poor fuel mixed with different types of fuel is supplied to the vehicle of the gasoline engine 11, gasoline is supplied in a state where some gasoline remains in the fuel tank 30. In such an electronically controlled engine control system, the engine 11 can be operated by ignition timing control or the like if the mixing ratio of the different fuel to the gasoline in the fuel tank 30 is small. As the ratio increases, the ratio of the flame-retardant fuel to the injected fuel increases and the amount of fuel contributing to combustion decreases, so the combustion state of the engine 11 deteriorates, engine rotation becomes unstable, and drivability deteriorates. Of course, in the worst case, the engine 11 may stop and become unable to run.

  Further, when different types of fuel are mixed in the gasoline supplied to the engine 11, the theoretical air-fuel ratio changes (for example, the theoretical air-fuel ratio in the case of 100% gasoline is about 14.7, but the theory in the case of 100% light oil. The air / fuel ratio is about 14.4). When the stoichiometric air-fuel ratio changes, the purification window of the catalyst 25 (the air-fuel ratio range in which the exhaust gas purification efficiency becomes high) changes accordingly. Therefore, when different types of fuel are mixed into gasoline, When the air-fuel ratio F / B control is executed at the fuel ratio (for example, the stoichiometric air-fuel ratio in the case of 100% gasoline), the air-fuel ratio of the exhaust gas deviates from the range of the purification window of the catalyst 25, and the exhaust gas purification efficiency of the catalyst 25 May decrease and exhaust emissions may deteriorate.

  Therefore, the ECU 37 performs the following control by executing routines shown in FIGS. 3 and 4 described later. First, a knock generation ignition timing (ignition timing at which knocking occurs) is obtained based on a detection signal of the knock sensor 29, and a different type of fuel that cannot be used as fuel (gasoline) supplied to the engine 11 based on the knock generation ignition timing. It is determined whether (at least one of light oil, kerosene, heavy oil, etc.) is mixed.

  Specifically, the detection of the knock sensor 29 pays attention to the characteristic that when the fuel supplied to the engine 11 is mixed with different types of fuel such as light oil, kerosene, and heavy oil, the knock limit of the ignition timing changes to the retard side. Each time it is determined whether knocking has occurred based on the signal and it is determined that knocking has occurred, the ignition timing at that time is stored as the knocking ignition timing, and the ignition timing is reduced by a predetermined amount. Whether or not the knock generation ignition timing is retarded from a predetermined determination value (for example, the retard side limit value of the knock generation ignition timing when normal gasoline is supplied) by repeating the retarding process When the knock occurrence ignition timing is retarded from the determination value, it is determined that different types of fuel (light oil, kerosene, heavy oil, etc.) are mixed. Accordingly, it can be accurately determined whether or not the different fuel is mixed, and when the different fuel is mixed, the mixing of the different fuel can be detected promptly.

  In addition, paying attention to the characteristic that the knock limit changes and the knock generation ignition timing changes according to the mixing ratio of the different fuel, if it is determined that the different fuel is mixed, the knock generation ignition timing is set. Using a map or a mathematical formula for calculating the mixing ratio of the different fuel as a parameter, the mixing ratio of the different fuel is estimated from the knock generation ignition timing.

  Further, when it is determined that different types of fuel are mixed, it is determined whether or not the air-fuel ratio F / B control is being performed. If the air-fuel ratio F / B control is not being performed (when open-loop control is being performed) ), A fuel increase correction coefficient is calculated by a map or a mathematical formula according to the mixing ratio of different fuels, and the fuel injection amount is corrected using this fuel increase correction coefficient, so that Correct the fuel injection amount. Accordingly, the fuel injection amount is corrected in response to the change in the ratio of the flame-retardant fuel to the injected fuel in accordance with the mixing ratio of the different fuel, so that the fuel amount contributing to combustion does not become excessive or insufficient. .

On the other hand, when the air-fuel ratio F / B control is being performed, as shown in the time chart of FIG. 2, the target air-fuel ratio is calculated by a map or a mathematical formula according to the mixing ratio of the different fuel, thereby mixing the different fuel. The target air-fuel ratio is corrected according to the ratio. Thus, the target air-fuel ratio is corrected in accordance with the change in the theoretical air-fuel ratio according to the mixing ratio of the different fuels and the purification window of the catalyst 25 is changed, and the target air-fuel ratio is set within the range of the purification window of the catalyst 25. Set in.
Hereinafter, the processing content of each routine of FIG.3 and FIG.4 which ECU37 performs is demonstrated.

[Fuel injection control routine for detection of mixed fuels]
The fuel injection control routine at the time of detecting mixing of different fuels shown in FIG. 3 is executed at a predetermined cycle while the ECU 37 is powered on. When this routine is started, first, in step 101, a heterogeneous fuel mixture determination routine of FIG. 4 described later is executed, so that different types of fuel (light oil, kerosene) that cannot be used as fuel (gasoline) supplied to the engine 11 are executed. , Heavy oil or the like) is mixed, and if it is determined that the different fuel is mixed, the mixing ratio of the different fuel is estimated.

  Thereafter, the process proceeds to step 102, where it is determined whether or not there is a mixture of different fuels based on the determination result of the different fuel mixture determination process (step 101). This routine is terminated without performing the processing after step 103.

  On the other hand, if it is determined in step 102 that there is a mixture of different types of fuel, the process proceeds to step 103 to determine whether air-fuel ratio F / B control is being performed. As a result, when it is determined that the air-fuel ratio F / B control is not being performed (when it is determined that the open loop control is being performed), the routine proceeds to step 104, and the map for the fuel increase correction coefficient shown in FIG. Then, a fuel increase correction coefficient corresponding to the current mixing ratio of the different fuel is calculated.

  In general, when different types of fuel such as light oil, kerosene, and heavy oil are mixed in gasoline, the ratio of flame retardant fuel to injected fuel increases as the mixing ratio of the different types of fuel increases. Therefore, the fuel increase correction shown in FIG. The coefficient map is set so that the fuel increase correction coefficient increases as the mixing ratio of different types of fuel increases and the fuel injection amount is corrected to the increase side. As a result, the fuel injection amount is corrected to the increase side corresponding to the increase in the ratio of the flame retardant fuel to the injected fuel as the mixing ratio of the different types of fuel increases, so that the excess or deficiency of the fuel amount contributing to combustion is ensured. I try to suppress it.

  Thereafter, the process proceeds to step 105, where the fuel injection amount is corrected using the fuel increase correction coefficient according to the mixing ratio of the different fuel, thereby correcting the fuel injection amount according to the mixing ratio of the different fuel and performing combustion. Make sure that there is no excess or deficiency in the amount of fuel that contributes. The processing in these steps 104 and 105 serves as fuel injection amount correction means in the claims.

  On the other hand, if it is determined in step 103 that the air-fuel ratio F / B control is being performed, the routine proceeds to step 106, where the current mixture ratio of the different fuels is referred to with reference to the target air-fuel ratio map shown in FIG. The target air-fuel ratio corresponding to is calculated.

  In general, when different types of fuel such as light oil, kerosene, and heavy oil are mixed in gasoline, the higher the mixing ratio of the different types of fuel, the smaller the theoretical air-fuel ratio becomes, and the purification window of the catalyst 25 tends to decrease in the air-fuel ratio (rich direction). 6), the target air-fuel ratio map shown in FIG. 6 is set such that the target air-fuel ratio decreases as the mixing ratio of different types of fuel increases. As a result, the higher the mixing ratio of the different types of fuel, the smaller the stoichiometric air-fuel ratio, and the target air-fuel ratio is corrected to the decreasing side in response to the purification window of the catalyst 25 changing in the air-fuel ratio decreasing direction. Is accurately set within the range of the purification window of the catalyst 25. The process of step 106 serves as a target air-fuel ratio correcting means in the claims.

[Different fuel mixing routine]
The heterogeneous fuel mixture determination routine shown in FIG. 4 is a subroutine executed in step 101 of the fuel injection control routine at the time of detecting the heterogeneous fuel mixture in FIG. When this routine is started, first, in step 201, it is determined whether or not knocking has occurred based on the detection signal of the knock sensor 29. If it is determined that knocking has not occurred, step 202 and subsequent steps are performed. This routine is terminated without performing the above process.

  Thereafter, when it is determined in step 201 that knocking has occurred, the process proceeds to step 202, the current ignition timing at which knocking has occurred is stored as the knocking ignition timing, and then the process proceeds to step 203. The ignition timing is retarded by a predetermined amount.

  After this, the routine proceeds to step 204, where it is determined whether or not the knocking ignition timing exceeds the determination value and is on the retard side with respect to the determination value. Here, for example, the judgment value is set to the retard side limit value of the knock generation ignition timing when normal fuel (gasoline) is supplied, or a value slightly behind (that is, near the knock limit). Has been.

  If it is determined in step 204 that the knocking ignition timing does not exceed the determination value, the routine proceeds to step 205, where there is no mixing of different fuels such as light oil, kerosene, heavy oil (for reasons other than mixing of different fuels). This routine is terminated. As a result of the above processing, every time knocking is detected, the ignition timing at that time is stored as the knocking ignition timing, and after the ignition timing is retarded by a predetermined amount, whether or not the knocking ignition timing exceeds the determination value The process (step 201-204) which determines is repeated.

  Thereafter, when it is determined in the above step 204 that the knocking ignition timing exceeds the determination value and is retarded from the determination value, the process proceeds to step 206, where different types of fuel (light oil, kerosene, heavy oil, etc.) are mixed. After determining that it is present, the routine proceeds to step 207, where a different fuel mixture warning lamp 38 provided on the instrument panel of the driver's seat is turned on, or a warning display section (not shown) of the instrument panel of the driver's seat. The driver is warned by displaying a warning of “mixing of different fuels”. As a result, the driver is informed early of the mixing of different fuels.

  Thereafter, the process proceeds to step 208, and the mixture ratio of the different fuel according to the current knocking ignition timing is calculated with reference to the map of the mixture ratio of the different fuel shown in FIG. Since the knock limit tends to change to the retard side and the knock generation ignition timing tends to change to the retard side as the mixture ratio of the different fuel increases, the map of the mixture ratio of the different fuel shown in FIG. It is set so that the mixing ratio of the different fuel becomes higher as the ignition timing is retarded. The processing of step 208 serves as a different fuel mixture ratio estimation means in the claims.

  After that, when it is determined in step 201 that knocking has ceased to occur, the ignition timing has become retarded from the retarded limit value of the knocking ignition timing corresponding to the actual heterogeneous fuel mixture ratio. By determining and ending this routine, the processing after step 202 (ignition timing of ignition timing, etc.) is stopped.

  In the present embodiment described above, when it is determined that different fuels such as light oil, kerosene, and heavy oil are mixed in the gasoline supplied to the engine 11, the mixing ratio of the different fuels is estimated, and the air-fuel ratio F When the / B control is not being performed (during open loop control), the fuel injection amount is corrected according to the mixing ratio of the different fuel, so the ratio of the flame-retardant fuel to the injected fuel is determined according to the mixing ratio of the different fuel. Corresponding to the change, the fuel injection amount can be corrected to suppress the excess or deficiency of the fuel amount contributing to combustion. Thereby, the deterioration of the combustion state by mixing of different fuels can be suppressed, and the deterioration of drivability can be suppressed.

  On the other hand, as shown in the time chart of FIG. 2, during the air-fuel ratio F / B control, the target air-fuel ratio is corrected according to the mixing ratio of the different fuel. The target air-fuel ratio can be corrected in response to the change of the fuel ratio and the purification window of the catalyst 25, and the target air-fuel ratio can be set within the range of the purification window of the catalyst 25. Thereby, even when different fuels are mixed and the stoichiometric air-fuel ratio changes, the actual air-fuel ratio of the exhaust gas can be controlled by the air-fuel ratio F / B control so that it falls within the range of the purification window of the catalyst 25. A reduction in exhaust gas purification efficiency of the catalyst 25 due to mixing of different types of fuel can be suppressed, and deterioration of exhaust emission can be suppressed.

  In the above embodiment, it is determined whether or not the different fuel is mixed based on the knocking ignition timing. However, the determination method of the different fuel may be appropriately changed. When mixed, the air-fuel ratio, in-cylinder pressure, exhaust temperature, exhaust gas HC concentration, etc. of the exhaust gas change, so the output of the exhaust gas sensor 24, the air-fuel ratio F / B correction amount, in-cylinder pressure, exhaust temperature, exhaust gas It may be determined whether or not a different type of fuel is mixed based on any one of the HC concentrations. Furthermore, the mixing ratio of different fuels may be estimated based on any one of the output of the exhaust gas sensor 24, the air-fuel ratio F / B correction amount, the in-cylinder pressure, the exhaust temperature, the HC concentration of the exhaust gas, and the like.

  In the above embodiment, it is determined whether or not light oil, kerosene, or heavy oil is mixed in the gasoline supplied to the engine 11 as a different type of fuel. It is possible to determine whether or not the fuel injection amount or the target air-fuel ratio is corrected in accordance with the mixing ratio when alcohol exceeding the allowable amount is mixed.

  Further, the present invention is not limited to the intake port injection type engine as shown in FIG. 1, and includes an in-cylinder injection type engine, and a fuel injection valve for intake port injection and a fuel injection valve for in-cylinder injection. It can also be applied to dual-injection engines.

  Furthermore, when the present invention is applied to a diesel engine that uses light oil as a fuel and gasoline that is a different kind of fuel that cannot be used is mixed in the light oil supplied to the engine, the amount of fuel injected according to the mixing ratio Alternatively, the target air-fuel ratio may be corrected.

  Further, light oil that is a different type of fuel that cannot be used as fuel supplied to the engine by applying the present invention to a fuel engine that can use gasoline, alcohol, and alcohol mixed fuel obtained by mixing alcohol with gasoline as fuel. When kerosene, heavy oil or the like is mixed, the fuel injection amount or the target air-fuel ratio may be corrected according to the mixing ratio.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a time chart which shows the execution example of the target air fuel ratio correction | amendment according to the mixing ratio of a different fuel. It is a flowchart explaining the flow of a process of the fuel injection control routine at the time of the detection of mixing of different types of fuel. It is a flowchart explaining the flow of a process of a different fuel mixing determination routine. It is a figure which shows notionally an example of the map of a fuel increase correction coefficient. It is a figure which shows notionally an example of the map of a target air fuel ratio. It is a figure which shows notionally an example of the map of a different fuel mixing ratio.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Intake pipe, 16 ... Throttle valve, 21 ... Fuel injection valve, 22 ... Spark plug, 23 ... Exhaust pipe, 24 ... Exhaust gas sensor, 25 ... Catalyst, 29 ... Knock sensor, 30 ... Fuel tank, 31 ... fuel pump, 32 ... fuel piping, 37 ... ECU (different fuel mixture ratio estimation means, fuel injection amount correction means, target air-fuel ratio correction means)

Claims (4)

A different fuel mixing ratio estimation means for estimating a mixing ratio of different fuels mixed in the fuel supplied to the internal combustion engine;
A control device for an internal combustion engine, comprising: a fuel injection amount correcting unit that corrects a fuel injection amount in accordance with the mixing rate of the different fuel estimated by the different fuel mixing rate estimating unit. The internal combustion engine is a gasoline engine that uses gasoline as fuel,
The different fuel mixture ratio estimation means estimates at least one mixture ratio of light oil, kerosene, and heavy oil as the different fuel,
2. The control device for an internal combustion engine according to claim 1, wherein the fuel injection amount correction unit corrects the fuel injection amount to an increase side as the mixing ratio of the different fuel increases. In a control apparatus for an internal combustion engine that performs air-fuel ratio feedback control for performing feedback control of the air-fuel ratio so that the air-fuel ratio of exhaust gas matches the target air-fuel ratio based on the output of an exhaust gas sensor provided in an exhaust passage of the internal combustion engine,
A different fuel mixture ratio estimation means for estimating a mixture ratio of different fuels mixed in the fuel supplied to the internal combustion engine;
An internal combustion engine comprising: a target air-fuel ratio correcting unit that corrects the target air-fuel ratio in accordance with the mixing ratio of the different fuel estimated by the different fuel mixing ratio estimating unit during the air-fuel ratio feedback control. Control device. The internal combustion engine is a gasoline engine that uses gasoline as fuel,
The different fuel mixture ratio estimation means estimates at least one mixture ratio of light oil, kerosene, and heavy oil as the different fuel,
4. The control apparatus for an internal combustion engine according to claim 3, wherein the target air-fuel ratio correcting means corrects the target air-fuel ratio to a decreasing side as the mixing ratio of the different fuel becomes higher.

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