JP4853675B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine.

  In general, as a control device for an internal combustion engine equipped with an ignition plug, a timing for igniting an air-fuel mixture formed in a combustion chamber based on a parameter (for example, engine rotation speed) indicating an operating state (hereinafter referred to as “ignition timing”). It is known what determines "." This control device is described in Patent Document 1 below, for example.

  In this type of control device, the crank angle when the gas pressure in the combustion chamber reaches the maximum value matches the predetermined crank angle (for example, ATDC 10 ° CA) that is retarded from the compression top dead center. In addition, the ignition timing is often determined. This is based on the viewpoint of bringing the output torque of the crankshaft that changes according to the ignition timing close to the maximum value. Hereinafter, the predetermined crank angle is also referred to as “maximum torque crank angle”. The ignition timing when the output torque reaches the maximum value is also referred to as “maximum torque ignition timing”.

In many cases, the relationship between the maximum torque ignition timing and the parameter representing the operating state is defined in advance. Therefore, in this type of apparatus, for example, the maximum torque ignition timing is determined using a table that defines this relationship (hereinafter also referred to as “basic ignition timing determination table”). By performing ignition at the maximum torque ignition timing determined in this way, deterioration of fuel consumption can be suppressed.
JP-A-4-116244

  By the way, in the basic ignition timing determination table, the ratio of moisture contained in the fuel (hereinafter, simply referred to as “moisture ratio”) is not considered. On the other hand, there may be a situation where water is mixed into the fuel due to the opening and closing of the fuel filler opening of the fuel tank. In this case, if the ignition timing is determined using the basic ignition timing determination table, the following problem occurs.

  FIG. 18 is a graph showing the relationship between the crank angle and the gas pressure in the combustion chamber when ignition is performed at the ignition timing CAig1 determined by the basic ignition timing determination table. The water itself mixed in the fuel does not contribute to the combustion reaction in the combustion chamber, but takes away a part of the combustion heat of the combustible component. For this reason, the temperature of the gas in the combustion chamber becomes lower as the moisture ratio increases (when the air-fuel ratio is constant). As a result, the combustion rate of the air-fuel mixture becomes smaller as the moisture ratio increases.

  When the moisture ratio is zero, the crank angle at which the gas pressure becomes maximum (hereinafter also referred to as “maximum pressure crank angle”) is the value CA1 (that is, the maximum torque crank angle), and in this case It is assumed that the output torque obtained in (1) becomes the value TQ1 (maximum value). On the other hand, when water is mixed in the fuel and ignition is performed at the same timing as the ignition timing CAig1, the maximum pressure crank angle becomes a value CA2 that is retarded from the value CA1. The degree of shift of the value CA2 from the value CA1 to the retard side becomes larger as the combustion speed of the air-fuel mixture is smaller (that is, the moisture content is larger).

  FIG. 19 is a graph showing the relationship between the ignition timing and the output torque. When water is mixed in the fuel, the maximum pressure crank angle is deviated from the maximum torque crank angle by ignition at the ignition timing CAig1. Therefore, in this case, the output torque is a value smaller than the value TQ1. The degree of decrease in the output torque corresponds to the degree of shift of the value CA2 from the value CA1 to the retard side. That is, the degree of decrease in the output torque becomes larger as the moisture ratio increases. As the output torque decreases in this way, the degree of deterioration of fuel consumption increases.

  In other words, when water is mixed in the fuel, it is conceivable to make the maximum pressure crank angle close to the maximum torque crank angle in order to suppress the above-described decrease in output torque. That is, it is necessary to perform ignition at a timing that is more advanced than the ignition timing CAig1 in accordance with the degree of shift (that is, the moisture ratio). Therefore, as the moisture ratio increases, the curve representing the relationship between the ignition timing and the output torque (that is, the maximum torque ignition timing) moves in parallel toward the advance side.

  If the ignition timing is determined without considering the moisture ratio, for example, when water is mixed into the fuel, the degree of deterioration in fuel consumption increases. Accordingly, an object of the present invention is to provide a control device for an internal combustion engine that can suppress the degree of deterioration of fuel consumption in consideration of the proportion of moisture contained in the fuel.

  A control device according to the present invention includes an injection valve that injects fuel toward a combustion chamber of an internal combustion engine, and an ignition plug that ignites an air-fuel mixture formed in the combustion chamber by the fuel injected by the injection valve. It is applied to the internal combustion engine provided.

  The control device according to the present invention includes a fuel injection amount determining means that determines a fuel injection amount that is an amount of fuel injected by the injection valve based on an operating state of the internal combustion engine, and an ignition timing determination that determines the ignition timing. Means.

  A feature of the control device according to the present invention is that it comprises a moisture ratio estimating means for estimating the moisture ratio based on a value that changes according to the combustion speed of the air-fuel mixture, and the ignition timing determining means includes the moisture ratio estimating means. The ignition timing is determined based on the moisture ratio estimated by the above.

  More specifically, the ignition timing determining means is configured to determine the ignition timing as a more advanced timing as the moisture ratio increases. Here, the moisture ratio may be a weight ratio of moisture contained in the fuel or a volume ratio. Further, for example, the reference ignition timing may be determined based on the operating state of the internal combustion engine, and the determined reference ignition timing may be corrected to a more advanced timing according to the moisture ratio.

  According to the said structure, a water | moisture content ratio can be estimated easily based on the value which changes according to the combustion speed of air-fuel | gaseous mixture. Further, the ignition timing can be brought close to the maximum torque ignition timing according to the moisture ratio. Therefore, even if water is mixed in the fuel, the above-described decrease in output torque can be suppressed. As a result, the deterioration degree of fuel consumption can be suppressed.

  In the control apparatus according to the present invention, for example, the control apparatus includes a transition acquisition unit that acquires a transition of the pressure of the gas in the combustion chamber, and the moisture ratio estimation unit corresponds to a case where the moisture ratio is a predetermined ratio. The ratio of the moisture may be estimated based on the difference between the transition of the pressure stored in advance and the transition of the pressure acquired by the transition acquisition unit.

  Here, the transition of pressure may be, for example, the transition (change) of the gas pressure with respect to the crank angle (or time itself) in a period including at least the second half of the compression stroke and the first half of the expansion stroke. Further, the transition of the pressure stored in advance may be, for example, a transition of pressure obtained when the operating state of the internal combustion engine is in a predetermined state and ignition is performed at a predetermined ignition timing. .

  The change in pressure changes according to the combustion speed of the air-fuel mixture. That is, the transition of the pressure can change according to the moisture ratio (see FIG. 18). Therefore, according to the said structure, a moisture ratio can be estimated easily based on the difference of the transition of the pressure memorize | stored previously and the transition of the acquired pressure.

  Further, in the control device according to the present invention, for example, the control device includes transition acquisition means for acquiring the transition of the output torque of the crankshaft of the internal combustion engine, and the moisture ratio estimation means has the moisture ratio of a predetermined ratio. The ratio of the moisture may be estimated based on a difference between the transition of the output torque stored in advance corresponding to the case and the transition of the output torque acquired by the transition acquisition unit.

  Here, the transition of the output torque may be, for example, the transition (change) of the output torque (average or maximum in one combustion cycle) with respect to the ignition timing. Further, the transition of the output torque stored in advance is, for example, the transition of the output torque obtained when the operating state of the internal combustion engine is in a predetermined state and ignition is performed at a predetermined ignition timing. Also good.

  The transition of the output torque can also change according to the moisture ratio, similar to the transition of the pressure (see FIG. 19). Therefore, even with the above configuration, the moisture ratio can be easily estimated based on the difference between the transition of the output torque stored in advance and the transition of the acquired output torque.

  In the control device according to the present invention, the control device includes a temperature acquisition unit that acquires the temperature of the internal combustion engine, and the fuel injection amount determination unit has a temperature acquired by the temperature acquisition unit that is lower than a predetermined temperature. As the air / fuel ratio of the air / fuel mixture becomes richer than the stoichiometric air / fuel ratio and the water ratio estimated by the water ratio estimating means increases, the air / fuel ratio becomes richer from the stoichiometric air / fuel ratio. It is preferable that the fuel injection amount is determined so that the degree of deviation in the direction becomes larger.

  In this case, for example, an air-fuel ratio sensor that outputs a value corresponding to the air-fuel ratio of the exhaust gas is disposed in the exhaust passage of the internal combustion engine, and the temperature acquired by the temperature acquisition means is determined by the fuel injection amount determination means. When the temperature is equal to or higher than the temperature, the fuel injection amount may be determined so that the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio based on the output value of the air-fuel ratio sensor.

  In general, when the temperature of the internal combustion engine is low, the fuel injection amount is often determined so that the air-fuel ratio of the air-fuel mixture becomes richer than the stoichiometric air-fuel ratio. This is based on the viewpoint that the fuel hardly evaporates and the catalyst is warmed up. On the other hand, when water is mixed in the fuel, if the temperature of the internal combustion engine is low, the fuel is difficult to evaporate and the heat of combustion is greatly lost to the water. Due to this, misfire is more likely to occur in the combustion chamber as the moisture ratio increases. As a result, the variation degree of the output torque is further increased.

  In order to suppress the occurrence of the misfire described above, it is conceivable to change the degree of shift of the air-fuel ratio from the stoichiometric air-fuel ratio to the rich direction in accordance with the moisture ratio. The above configuration is based on such knowledge. According to this, even when the temperature of the internal combustion engine is low, the state of the air-fuel mixture in the combustion chamber can be appropriately changed to a combustible state regardless of the water content ratio, and the occurrence of misfire can be suppressed. As a result, the above-described fluctuation degree of the output torque can be suppressed.

  Further, in the control device according to the present invention, when the internal combustion engine is configured to use a fuel containing alcohol as the fuel, the control device obtains an alcohol proportion that obtains a proportion of the alcohol contained in the fuel. And the fuel injection amount determination means determines the fuel injection amount so that the degree of shift in the rich direction becomes greater as the alcohol ratio acquired by the alcohol ratio acquisition means increases. Preferably, it is configured.

  In general, hydrocarbon fuels (eg, gasoline) often contain components having a relatively low boiling point. On the other hand, the boiling point of alcohol is often higher than that of the low boiling point component. In addition, the latent heat of vaporization of alcohol is often larger than that of hydrocarbon fuel. These are considered to be based on the OH group possessed by the alcohol.

  Therefore, when alcohol containing alcohol is used, the fuel is particularly difficult to evaporate if the temperature of the internal combustion engine is low. In addition, combustion heat is greatly deprived of alcohol. Due to this, as in the case of the moisture ratio described above, misfire in the combustion chamber is more likely to occur as the alcohol ratio increases. As a result, the variation degree of the output torque is further increased.

  According to the said structure, irrespective of the magnitude | size of the ratio of alcohol, the state of the air-fuel mixture in a combustion chamber can be made into a combustible state appropriately, and generation | occurrence | production of misfire can be suppressed. As a result, the above-described fluctuation degree of the output torque can be suppressed.

  Hereinafter, embodiments of a control device for an internal combustion engine according to the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 shows a schematic configuration of a system in which a control device for an internal combustion engine according to a first embodiment of the present invention is applied to a spark ignition type multi-cylinder (four-cylinder) internal combustion engine 10. The internal combustion engine 10 includes a cylinder block 20 including a cylinder block, a cylinder block lower case, and an oil pan, a cylinder head 30 fixed on the cylinder block 20, and a fuel mixture in the cylinder block 20. And an exhaust system 50 for releasing exhaust gas from the cylinder block 20 to the outside.

  The internal combustion engine 10 can use only gasoline (ethanol concentration Ret = 0%), gasoline containing ethanol, and only ethanol (ethanol concentration Ret = 100%) as fuel. Here, the ethanol concentration Ret is a percent concentration expressed by “Vet / (Vgas + Vet)” where Vgas is the volume of gasoline contained in the fuel and Vet is the volume of ethanol contained in the fuel.

  The cylinder block unit 20 includes a cylinder 21, a piston 22, a connecting rod 23, and a crankshaft 24. The piston 22 reciprocates in the cylinder 21, and the reciprocating motion of the piston 22 is transmitted to the crankshaft 24 through the connecting rod 23, whereby the crankshaft 24 rotates. The heads of the cylinder 21 and the piston 22 form a combustion chamber 25 together with the cylinder head portion 30.

  The cylinder head portion 30 includes an intake port 31 communicating with the combustion chamber 25, an intake valve 32 that opens and closes the intake port 31, an intake camshaft that drives the intake valve 32, and continuously changes the phase angle of the intake camshaft. The variable intake timing device 33, the actuator 33 a of the variable intake timing device 33, the exhaust port 34 communicating with the combustion chamber 25, the exhaust valve 35 that opens and closes the exhaust port 34, the exhaust camshaft 36 that drives the exhaust valve 35, and the spark plug 37 , An igniter 38 including an ignition coil for generating a high voltage to be applied to the spark plug 37, and a fuel injection valve 39 for injecting fuel into the intake port 31.

  The intake system 40 is provided in an intake pipe 41 including an intake manifold that communicates with the intake port 31 and forms an intake passage together with the intake port 31, an air filter 42 provided at an end of the intake pipe 41, and the intake pipe 41. A throttle valve 43 for changing the opening cross-sectional area of the intake passage and a throttle valve actuator 43a made of a DC motor constituting throttle valve driving means are provided.

  The exhaust system 50 includes an exhaust manifold 51 that communicates with the exhaust port 34, and an exhaust pipe (exhaust pipe) that is connected to the exhaust manifold 51 (actually, a collection portion of the exhaust manifolds 51 that communicate with each exhaust port 34). ) 52, and a three-way catalyst 53 disposed (intervened) in the exhaust pipe 52. The exhaust port 34, the exhaust manifold 51, and the exhaust pipe 52 constitute an exhaust passage.

  On the other hand, this system includes a hot-wire air flow meter 61, a throttle position sensor 62, a cam position sensor 63, a crank position sensor 64, a water temperature sensor 65 (corresponding to a part of the temperature acquisition means), an air-fuel ratio sensor 66, and a filler opening / closing. A sensor 67 and a combustion chamber pressure sensor 68 are provided.

  The hot-wire air flow meter 61 detects the mass flow rate per unit time of the intake air flowing through the intake pipe 41 and outputs a signal representing the mass flow rate (intake air flow rate) Ga. The throttle position sensor 62 detects the opening degree of the throttle valve 43 and outputs a signal representing the throttle valve opening degree. The cam position sensor 63 generates a signal (G2 signal) having one pulse every time the intake camshaft rotates 90 ° (that is, every time the crankshaft 24 rotates 180 °). This signal represents the opening / closing timing of the intake valve 32.

  The crank position sensor 64 outputs a signal having a narrow pulse every time the crankshaft 24 rotates 10 °, and a wide pulse every time the crankshaft 24 rotates 360 °. This signal represents the operating speed NE. The water temperature sensor 65 detects the temperature of the cooling water of the internal combustion engine 10 and outputs a signal representing the cooling water temperature THW. The coolant temperature THW corresponds to the temperature of the internal combustion engine.

  The air-fuel ratio sensor 66 is disposed on the upstream side of the three-way catalyst 53 in the exhaust passage. The air-fuel ratio sensor 66 is a so-called “limit current type oxygen concentration sensor” that detects the air-fuel ratio of the exhaust gas flowing into the three-way catalyst 53 and outputs an output value Vafs (V) that is a voltage corresponding to the air-fuel ratio of the exhaust gas. Is output.

  The fuel filler opening / closing sensor 67 is disposed in a fuel filler provided in a fuel tank (not shown), and outputs a predetermined current when the fuel filler is changed from a closed state to an open state. The combustion chamber pressure sensor 68 detects the gas pressure in the combustion chamber 25 and outputs a signal representing the gas pressure P.

  The electric control device 70 includes a CPU 71 connected by a bus, a routine (program) executed by the CPU 71, a table (look-up table, map), a ROM 72 in which constants and the like are stored in advance, and the CPU 71 temporarily stores data as necessary. This is a microcomputer comprising a RAM 73 for storing data, a backup RAM 74 for storing data while the power is turned on and holding the stored data while the power is shut off, an interface 75 including an AD converter, and the like. .

  The interface 75 is connected to the sensors 61 to 68, supplies signals from the sensors 61 to 68 to the CPU 71, and in response to instructions from the CPU 71, the actuator 33a, the igniter 38, and the fuel injection valve 39 of the variable intake timing device 33. , And a drive signal is sent to the throttle valve actuator 43a and the like.

(Outline of control)
Next, an outline of control performed by the control device configured as described above will be described. In principle, the control device in this example determines the fuel injection amount Fi based on the output value Vafs of the air-fuel ratio sensor 66 so that the air-fuel ratio of the air-fuel mixture (that is, the air-fuel ratio of the exhaust gas) becomes the stoichiometric air-fuel ratio. To do. That is, air-fuel ratio feedback control is executed. Further, as will be described later, the control device in this example determines the ignition timing CAig based on the operating state of the internal combustion engine 10, the ethanol concentration Ret, and the water concentration Raq. Then, the fuel-air mixture injected with the fuel injection amount Fi at the ignition timing CAig is ignited.

  Here, the moisture concentration Raq is a percent concentration represented by “Vaq / (Vgas + Vet + Vaq)” where Vaq is the volume of water contained in the fuel.

  FIG. 2 is a diagram showing an outline of air-fuel ratio feedback control executed by the control device in this example. The air-fuel ratio feedback control is executed when conditions such as the air-fuel ratio sensor 66 being normal and the coolant temperature THW being equal to or higher than the predetermined temperature THW1 are satisfied. When the cooling water temperature THW is lower than the predetermined temperature THW1, feedback control is not executed and the air-fuel ratio of the air-fuel mixture is made richer than the stoichiometric air-fuel ratio as will be described later (hereinafter referred to as this The control is referred to as “air-fuel ratio rich control”). Hereinafter, an overview of feedback control will be described with reference to FIG.

  First, basic fuel injection is performed by dividing the amount of intake air per intake stroke by the stoichiometric air-fuel ratio stoich (in this example, 14.6 (constant value)) of gasoline-only fuel (ethanol concentration Ret = 0%). The quantity Fbase is determined. Here, the intake air amount is determined based on the air mass flow rate Ga and the operating speed NE. Then, the fuel injection amount Fi for injection from the fuel injection valve 39 is calculated by multiplying the determined basic fuel injection amount Fbase by the feedback coefficient α calculated by the feedback coefficient α calculating unit.

  The feedback coefficient α calculation unit calculates the feedback coefficient α based on the output value Vafs and the target value Vafsref of the air-fuel ratio sensor 66. Specifically, the feedback coefficient α is calculated by performing PID processing on a value obtained by subtracting the target value Vafsref from the output value Vafs. Here, the target value Vafsref is a value corresponding to the theoretical air-fuel ratio stoich. When the fuel is a gasoline-only fuel (ethanol concentration Ret = 0%), the feedback coefficient α is “1”.

  Thereby, even when the ethanol concentration Ret changes, the basic fuel injection amount Fbase is corrected by the feedback coefficient α calculated in accordance with this change. As a result, the air-fuel ratio matches the stoichiometric air-fuel ratio by feedback control. In other words, the feedback coefficient α can be a value that changes according to the ethanol concentration Ret.

  Therefore, the control device in this example determines the ethanol concentration Ret using the relationship between the feedback coefficient α defined in advance and the ethanol concentration Ret. More specifically, the ethanol concentration Ret is determined based on the basic ethanol concentration determination table that defines the relationship between the feedback coefficient α and the ethanol concentration Ret shown by the solid line in FIG. 3 and the feedback coefficient α. This table is created on the basis of an experimental result that matches the ethanol concentration Ret when the water concentration Raq is zero. According to this table, the ethanol concentration Ret is determined to be a larger value as the feedback coefficient α is larger.

  In this example, when the ethanol concentration Ret is the value R1 and the water concentration Raq is zero, the calculated feedback coefficient α is assumed to be the value α1. Here, consider a case where the ethanol concentration Ret is equal to the value R1 and water is mixed in the fuel. In this case, the feedback coefficient α is a value (α1 + Δα) larger than the value α1 by a value Δα corresponding to the water concentration Raq. This is because the water itself mixed in the fuel does not contribute to the combustion reaction in the combustion chamber 25.

  That is, when water is mixed in the fuel, the relationship between the feedback coefficient α and the ethanol concentration Ret is different from the relationship in the basic ethanol concentration determination table (see the broken line in FIG. 3). Accordingly, when the basic ethanol concentration determination table is used in this case, the ethanol concentration Ret is determined to be a value R2 (> value R1) corresponding to the value (α1 + Δα).

  Thus, when the above table is used when water is mixed in the fuel, the ethanol concentration Ret is determined to be larger than the actual ethanol concentration. Hereinafter, a value determined using the basic ethanol concentration determination table is referred to as “basic ethanol concentration Rbase”.

  The ethanol concentration Ret is a parameter used to determine the ignition timing CAig and the like as will be described later. For this purpose, it is necessary to determine the ethanol concentration Ret with high accuracy. Therefore, the control device in this example estimates the water concentration Raq based on the transition of the gas pressure P in the combustion chamber 25, and corrects the basic ethanol concentration Rbase based on the estimated water concentration Raq.

  Further, as described above, the larger the moisture concentration Raq, the smaller the combustion rate of the air-fuel mixture as compared with the case where the moisture concentration Raq = 0%. For this reason, the degree of deviation of the maximum pressure crank angle from the maximum torque crank angle toward the retard side becomes larger (see FIG. 18). As a result, the ignition timing CAig and the crankshaft 24 A curve representing the relationship with the output torque (that is, the maximum torque ignition timing) moves in a parallel direction toward the more advanced side (see FIG. 19).

  Therefore, the control device in this example determines the basic ignition timing CAbase based on the operating speed NE, the load KL of the internal combustion engine 10, and the ethanol concentration Ret, and determines the basic ignition timing CAbase based on the estimated water concentration Raq. to correct.

  In addition, the control device in this example corrects the fuel injection amount when executing the air-fuel ratio rich control based on the estimated water concentration Raq and the ethanol concentration Ret obtained by the correction. The above is the outline of the control performed by the control device in this example.

(Actual operation)
Next, the actual operation of this apparatus will be described. Hereinafter, for convenience of explanation, “MapX (a1, a2,...)” Represents a table for obtaining a value X having a1, a2,. Further, when the value of the argument is a detection value of the sensor, the current value is used.

  In the routine for determining the fuel injection amount Fi and the ignition timing CAig shown in the flowchart of FIG. 4, the CPU 71 sets the crank angle of each cylinder to a predetermined crank angle before each intake top dead center (for example, BTDC 90 ° CA). Each time it is executed repeatedly.

  Therefore, when the crank angle of an arbitrary cylinder reaches the predetermined crank angle, the CPU 71 starts processing from step 400 and proceeds to step 405 to determine whether or not the coolant temperature THW is equal to or higher than the predetermined temperature THW1. Here, the predetermined temperature THW1 is the lower limit of the range of the cooling water temperature THW at which the state of the air-fuel mixture becomes combustible in the combustion chamber 25 regardless of the ethanol concentration Ret when the air-fuel ratio of the air-fuel mixture is the stoichiometric air-fuel ratio. Value.

  First, the case where the coolant temperature THW is equal to or higher than the predetermined temperature THW1 will be described. In this case, the CPU 71 determines “Yes” in step 405 and proceeds to step 410 to calculate the feedback coefficient α based on the output value Vafs of the air-fuel ratio sensor 66 as described above. When the feedback condition is not satisfied (for example, when it is determined that the air-fuel ratio sensor 66 is abnormal), the feedback coefficient α is set to “1”.

  Next, the CPU 71 proceeds to step 415 to determine the fuel injection amount Fi by multiplying the basic fuel injection amount Fbase (current value at the present time) by the feedback coefficient α calculated in step 410.

  Next, the CPU 71 proceeds to step 420 to determine whether or not the moisture concentration Raq estimation condition is satisfied. Here, the water concentration Raq estimation condition is established when the water concentration Raq and the ethanol concentration Ret have not been estimated yet after the oil supply port opening / closing sensor 67 detects that the oil supply port has been changed from the closed state to the open state. That is, each time the detection is performed, the moisture concentration Raq estimation condition is satisfied only once. This is based on the fact that the water concentration Raq and the ethanol concentration Ret are likely to change when the fuel filler opening is opened and fueling or the like is performed. In this example, the moisture concentration Raq estimation condition is satisfied when the operation state of the internal combustion engine 10 is in a steady state and the load KL of the internal combustion engine 10 is smaller than the predetermined value KL1 in addition to the above-described conditions. Shall.

  Now, description will be made assuming that the moisture concentration Raq estimation condition is not satisfied. In this case, the CPU 71 makes a “No” determination at step 420 and proceeds to step 425 to determine the basic ignition timing CAbase based on the basic ignition timing determination table MapCAbase (NE, KL, Ret). This basic ignition timing determination table MapCAbase (NE, KL, Ret) is calculated based on the ignition timing CAig corresponding to the case where the output torque TQ with respect to the ignition timing CAig becomes the maximum value when the moisture concentration Raq is zero. It is the table produced based on the experimental result which adapts a torque ignition timing. In this example, the output torque TQ means the average value of the output torque of the crankshaft 24 per combustion cycle.

  FIG. 5A shows the relationship between the operating speed NE and the load KL and the basic ignition timing CAbase determined based on the basic ignition timing determination table MapCAbase (NE, KL, Ret) when the ethanol concentration Ret is constant. FIG. In this case, the basic ignition timing CAbase is determined to be a more advanced timing as the operating speed NE is higher. This is based on the fact that the time per unit crank angle becomes shorter as the operating speed NE is higher. Further, the basic ignition timing CAbase is determined at a more retarded timing as the load KL is larger. This is based on the fact that the larger the load KL, the higher the gas pressure P in the combustion chamber 25 and the higher the combustion speed of the air-fuel mixture.

  In the range where “KL ≧ KL1”, the degree of deviation of the basic ignition timing CAbase with respect to the increase in the load KL toward the retard side is greater than in the range where “KL <KL1”. This is based on the viewpoint of suppressing abnormal combustion (that is, knocking) that tends to occur as the gas pressure P increases.

  FIG. 5B shows the relationship between the ethanol concentration Ret and the basic ignition timing CAbase determined based on the basic ignition timing determination table MapCAbase (NE, KL, Ret) when the operation speed NE and the load KL are constant. FIG. When “KL <KL1”, the basic ignition timing CAbase is determined at a constant timing regardless of the ethanol concentration Ret. On the other hand, when “KL ≧ KL1”, the basic ignition timing CAbase is determined to be a more advanced timing as the ethanol concentration Ret is larger. Since ethanol has a higher octane number than gasoline, ethanol in the fuel acts as an anti-knock agent. For this reason, even when “KL ≧ KL1”, the greater the ethanol concentration Ret, the greater the margin that the basic ignition timing CAbase can be set to the advance side. The tendency of the basic ignition timing CAbase with respect to the ethanol concentration Ret when “KL ≧ KL1” is based on this.

  Next, the CPU 71 proceeds to step 430 to obtain the ignition timing CAig by subtracting the advance degree DCA calculated in step 650 described later from the basic ignition timing CAbase determined in step 425. When the ignition timing CAig is set to a value obtained by subtracting the advance angle DCA from the basic ignition timing CAbase, the ignition timing CAig is set to the advance side by the advance angle DCA from the basic ignition timing CAbase. Means.

  Next, the CPU 71 proceeds to step 435, instructs the igniter 38 and the like so that ignition is performed at the ignition timing CAig obtained in step 430, and then proceeds to step 495 to end the processing of this routine once. .

  Thereafter, as long as the moisture concentration Raq estimation condition is not satisfied, the CPU 71 determines “No” in step 420 and repeatedly executes the processes of steps 405, 410 to 420, and 425 to 435. When the moisture concentration Raq estimation condition is satisfied, the CPU 71 that has repeatedly executed the above process determines “Yes” when the process proceeds to step 420 and proceeds to step 440. The CPU 71 starts a routine process from step 600 for executing calculation of various values shown in the flowchart of FIG.

  The CPU 71 which has proceeded to step 600 proceeds to step 605 and determines the reference ignition timing MBTstd based on the reference ignition timing determination table MapMBTstd (NE, KL). This reference ignition timing determination table MapMBTstd (NE, KL) is based on the experimental result that matches the maximum torque ignition timing when the moisture concentration Raq is zero and “KL <KL1”. It is the produced table.

  Next, the CPU 71 proceeds to step 610 to determine the reference crank angle CAstd based on the reference crank angle determination table MapCAstd (NE, KL). This reference crank angle CAstd is when the gas pressure P in the combustion chamber 25 with respect to the crank angle becomes the maximum value when the water concentration Raq is zero and ignition is performed at the reference ignition timing MBTstd. The corresponding crank angle (that is, the maximum torque crank angle).

  Next, the CPU 71 proceeds to step 615 to instruct the igniter 38 and the like so that ignition is performed at the reference ignition timing MBTstd determined in step 605. Subsequently, the CPU 71 proceeds to step 620 to determine whether or not the corresponding maximum pressure crank angle CApmax has been acquired when the gas pressure P in the combustion chamber 25 with respect to the crank angle reaches the maximum value Pmax.

  FIG. 7 is a graph showing the relationship between the crank angle and the gas pressure P when ignition is performed at the reference ignition timing MBTstd. In FIG. 7, the transition of the gas pressure P indicated by the broken line is for the case where the moisture concentration Raq is zero. As described above, the larger the moisture concentration Raq, the smaller the combustion rate of the air-fuel mixture. As the combustion speed of the air-fuel mixture decreases, the degree of increase in the gas pressure P is smaller after the reference ignition timing MBTstd. From the above, the greater the moisture concentration Raq, the more retarded the maximum pressure crank angle CApmax.

  That is, the greater the moisture concentration Raq, the greater the crank angle difference ΔCA between the reference crank angle CAstd and the maximum pressure crank angle CApmax. In other words, the crank angle difference ΔCA is a value that changes according to the moisture concentration Raq. Therefore, the water concentration Raq can be estimated based on the crank angle difference ΔCA. The control device in this example estimates the water concentration Raq based on this knowledge. These steps 605 to 620 correspond to a part of the transition acquisition means.

  Accordingly, the CPU 71 determines “No” in step 620 until the maximum pressure crank angle CApmax is acquired, and if “Yes” is determined in step 620, the CPU 71 proceeds to step 625 and starts from the acquired maximum pressure crank angle CApmax. A crank angle difference ΔCA is obtained by subtracting the reference crank angle CAstd determined in step 610.

  Next, the CPU 71 proceeds to step 630 and estimates the water concentration Raq based on the crank angle difference ΔCA obtained in step 625 and the water concentration determination table MapRaq (ΔCA). FIG. 8 is a diagram showing a moisture concentration determination table MapRaq (ΔCA). According to the moisture concentration determination table MapRaq (ΔCA), the moisture concentration Raq is estimated to be larger as the crank angle difference ΔCA is larger. These steps 625 and 630 correspond to a part of the moisture ratio estimating means.

  Next, the CPU 71 proceeds to step 635 to estimate the basic ethanol concentration Rbase based on the feedback coefficient α calculated in step 410 and the basic ethanol concentration determination table MapRbase (α) (see the solid line in FIG. 3). This step 635 corresponds to a part of the alcohol ratio acquisition means.

  Subsequently, the CPU 71 proceeds to step 640 to determine an ethanol concentration correction coefficient KR (0 <KR ≦ 1) based on the water concentration Raq estimated in step 630 and the ethanol concentration correction coefficient determination table MapKR (Raq). To do. FIG. 9 is a diagram showing an ethanol concentration correction coefficient determination table MapKR (Raq). According to the ethanol concentration correction coefficient determination table MapKR (Raq), the ethanol concentration correction coefficient KR is determined to be smaller as the water concentration Raq is larger.

  Next, the CPU 71 proceeds to step 645 to obtain the ethanol concentration Ret by multiplying the basic ethanol concentration Rbase estimated in step 635 by the ethanol concentration correction coefficient KR determined in step 640.

  Next, the CPU 71 proceeds to step 650, and determines the advance angle DCA used in step 430 based on the moisture concentration Raq estimated in step 630 and the advance angle determination table MapDCA (Raq). FIG. 10 is a diagram showing an advance angle determination table MapDCA (Raq). According to the advance degree determination table MapDCA (Raq), the advance degree DCA is determined to be a larger value as the water concentration Raq is larger. Steps 425, 430 and 650 correspond to a part of the ignition timing determining means.

  Subsequently, the CPU 71 proceeds to step 655, and based on the water concentration Raq estimated in step 630, the ethanol concentration Ret obtained in step 645, and the rich control correction coefficient determination table MapKβ (Raq, Ret). Thus, the rich control correction coefficient Kβ (≧ 1) is determined. Then, the CPU 71 proceeds to step 495 in FIG. 4 via step 695 and temporarily ends the processing of this routine.

  The rich control correction coefficient Kβ is used in the air-fuel ratio rich control (see step 450 described later). FIG. 11 is a diagram showing a rich control correction coefficient determination table MapKβ (Raq, Ret). According to the rich control correction coefficient determination table MapKβ (Raq, Ret), the rich control correction coefficient Kβ is determined to be a larger value as the water concentration Raq is larger and the ethanol concentration Ret is larger.

  In this example, every time the latest values of the water concentration Raq, the ethanol concentration Ret, the advance angle DCA, and the rich control correction coefficient Kβ are calculated, they are stored and updated in the backup RAM 74. .

  Next, a case where the coolant temperature THW is lower than the predetermined temperature THW1 will be described. In this case, the CPU 71 determines “No” in step 405 and proceeds to step 445 to determine the basic rich control coefficient βbase (> 1) based on the basic rich control coefficient determination table Mapβbase (THW). This basic rich control coefficient βbase is used for determining the fuel injection amount Fi so that the air-fuel ratio of the air-fuel mixture becomes richer than the stoichiometric air-fuel ratio. More specifically, according to the basic rich control coefficient determination table Mapβbase (THW), the basic rich control coefficient βbase is determined to be a larger value as the cooling water temperature THW is lower.

  Next, the CPU 71 proceeds to step 450, and obtains the rich control coefficient β (> 1) by multiplying the basic rich control coefficient βbase determined in step 445 by the rich control correction coefficient Kβ determined in step 655. Subsequently, the CPU 71 proceeds to step 455 and multiplies the rich control coefficient β obtained in step 450 by the value obtained by multiplying the basic fuel injection amount Fbase by the fuel injection amount correction coefficient KF (≧ 1). The injection amount Fi is obtained.

  Here, the fuel injection amount correction coefficient KF is a value determined in consideration of the ethanol concentration Ret so that the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio when the fuel is injected with the value (KF · Fbase). is there. More specifically, the fuel injection amount correction coefficient KF is determined based on a table that defines the relationship between the fuel injection amount correction coefficient KF and the ethanol concentration Ret shown in FIG. According to this table, the larger the ethanol concentration Ret, the larger the fuel injection amount correction coefficient KF is determined. Thereafter, the CPU 71 executes the processing after step 420. Steps 405, 410, 415, 445, 450, 455, 655 correspond to a part of the fuel injection amount determining means.

  As described above, when the cooling water temperature THW is lower than the predetermined temperature THW1, the fuel injection amount Fi is determined as described above, so that the lower the cooling water temperature THW, the more the air-fuel ratio deviates from the stoichiometric air-fuel ratio in the rich direction. The degree of transfer is greater. This is based on the fact that the lower the coolant temperature THW, the more difficult the fuel evaporates and the greater the need to warm the catalyst 53. In this example, the greater the moisture concentration Raq and the greater the ethanol concentration Ret, the greater the degree of shift in the rich direction. This is based on the fact that when the cooling water temperature THW is low, the influence on misfire due to the heat deprived by water and ethanol is particularly great.

  As described above, according to the first embodiment of the control apparatus for an internal combustion engine according to the present invention, when the water concentration Raq estimation condition is satisfied, ignition is performed at the reference ignition timing MBTstd and the gas pressure P is the maximum value. The maximum pressure crank angle CApmax is obtained. A crank angle difference ΔCA, which is a difference between the acquired maximum pressure crank angle CApmax and a previously stored reference crank angle CAstd corresponding to the case where the moisture concentration Raq is zero, is obtained. Then, the moisture concentration Raq is estimated based on the crank angle difference ΔCA.

  Here, the larger the moisture concentration Raq, the smaller the combustion rate of the air-fuel mixture. For this reason, the maximum pressure crank angle CApmax becomes more retarded as the moisture concentration Raq increases, and the crank angle difference ΔCA becomes larger. In other words, the crank angle difference ΔCA can be a value representing the moisture concentration Raq. Therefore, the water concentration Raq can be estimated easily and accurately.

  Further, according to the first embodiment, the basic ignition timing CAbase is determined based on the operating state such as the operating speed NE, and the ignition timing CAig is more advanced than the basic ignition timing CAbase by the advance degree DCA corresponding to the moisture concentration Raq. Only the advance time is set. That is, the ignition timing CAig is set to a more advanced timing as the moisture concentration Raq is larger.

  Due to the fact that the higher the moisture concentration Raq, the lower the combustion speed of the air-fuel mixture, even if the operating state is constant, the greater the moisture concentration Raq, the more the maximum torque ignition timing becomes the more advanced timing. Become. Therefore, as shown by the broken line in FIG. 13, if the ignition timing CAig is set to the same timing as the basic ignition timing CAbase, the degree of decrease in the output torque TQ increases as the moisture concentration Raq increases (see FIG. 19). See), and the degree of deterioration of fuel consumption also becomes larger.

  On the other hand, in the first embodiment, the ignition timing CAig is set to the advance timing by the advance angle DCA corresponding to the moisture concentration Raq with respect to the basic ignition timing CAbase. That is, the ignition timing CAig can be brought close to the maximum torque ignition timing. For this reason, as shown by the solid line in FIG. 13, the degree of deterioration of the fuel consumption with respect to the increase in the water concentration Raq can be further reduced. Here, “fuel consumption” means a travelable distance with respect to a unit amount of fuel including water. Therefore, the degree of deterioration of fuel consumption increases as the water concentration Raq increases.

  Further, according to the first embodiment, when the coolant temperature THW is lower than the predetermined temperature THW1, the fuel injection amount Fi (= α · Fbase) is determined so that the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio. (In other words, instead of executing the air-fuel ratio feedback control), the fuel injection amount Fi (= β · (KF · Fbase) is set so that the air-fuel ratio of the air-fuel mixture is made richer than the stoichiometric air-fuel ratio. )) Is determined (that is, air-fuel ratio rich control is executed). In this air-fuel ratio rich control, the basic rich control coefficient βbase is determined based on the cooling water temperature THW, and the rich control coefficient β is determined by setting the rich control correction coefficient Kβ corresponding to the water concentration Raq and the ethanol concentration Ret to the basic rich control coefficient βbase. Determined by the multiplied value.

  As shown by the broken line in FIG. 14, if the fuel injection amount Fi is determined to be a value (βbase · (KF · Fbase)) in the air-fuel ratio rich control, the water concentration Raq (or ethanol concentration Ret) is large. Accordingly, misfire is more likely to occur in the combustion chamber 25, and the degree of fluctuation of the output torque TQ becomes larger.

  On the other hand, in the first embodiment, as shown by the solid line in FIG. 14, the greater the water concentration Raq (or ethanol concentration Ret), the greater the degree of shift of the air-fuel ratio from the stoichiometric air-fuel ratio to the rich direction. Since the fuel injection amount Fi is determined so as to be larger, the occurrence of misfire in the combustion chamber 25 can be suppressed. As a result, the degree of fluctuation of the output torque TQ with respect to the increase in the moisture concentration Raq can be further reduced.

  The present invention is not limited to the first embodiment, and various modifications can be employed within the scope of the present invention. For example, in the first embodiment, the basic ignition timing CAbase is determined on the basis of the basic ignition timing determination table MapCAbase (NE, KL, Ret), and the ignition timing CAig is advanced from the determined basic ignition timing CAbase. However, instead of this, the ignition timing CAig may be determined based on the ignition timing determination table MapCAig (NE, KL, Raq, Ret). In this case, according to the ignition timing determination table MapCAig (NE, KL, Raq, Ret), the ignition timing CAig is determined to be a more advanced timing as the moisture concentration Raq is larger.

  In the first embodiment, the crank angle difference ΔCA is obtained and the water concentration Raq is estimated based on the water concentration determination table MapRaq (ΔCA). Instead, the water concentration Raq is zero. In this case, the difference between the maximum value of the gas pressure P when ignition is performed at the reference ignition timing MBTstd and the gas pressure P corresponding to the reference crank angle CAstd when ignition is performed at the reference ignition timing MBTstd. ΔP may be obtained, and the moisture concentration Raq may be estimated based on the moisture concentration determination table MapRaq (ΔP). In this case, according to the moisture concentration determination table MapRaq (ΔP), the moisture concentration Raq is estimated to be larger as the pressure difference ΔP is larger.

  In the first embodiment, the water concentration Raq is estimated based on the water concentration determination table MapRaq (ΔCA) in which only the crank angle difference ΔCA is used as an argument. Instead, the operation is further performed as an argument. The water concentration Raq may be estimated based on the water concentration determination table MapRaq (ΔCA, NE) in which the speed NE is used. According to the moisture concentration determination table MapRaq (ΔCA, NE), the moisture concentration Raq is estimated to be a smaller value as the operation speed NE is larger. This is based on the fact that, even when the crank angle difference ΔCA is constant, the time corresponding to the crank angle difference ΔCA is shorter as the operating speed NE is higher. Further, the moisture concentration Raq may be estimated based on a moisture concentration determination table MapRaq (ΔCA, NE, KL) in which the load KL is further used as an argument. According to the moisture concentration determination table MapRaq (ΔCA, NE, KL), the greater the load KL, the smaller the moisture concentration Raq is estimated.

(Second Embodiment)
Next, an internal combustion engine control apparatus according to a second embodiment of the present invention will be described. The internal combustion engine to which the second embodiment is applied differs from the internal combustion engine 10 of the first embodiment only in that a torque sensor 69 is provided instead of the combustion chamber pressure sensor 68 (see the broken line in FIG. 1). . The torque sensor 69 detects the output torque of the crankshaft 24 and outputs a signal representing the output torque TQ.

  In the first embodiment, the moisture concentration Raq is based on the difference between the transition of the gas pressure P and the transition of the gas pressure P corresponding to the case where the moisture concentration Raq is zero (that is, the crank angle difference ΔCA). It was estimated. In the second embodiment, instead of this, the moisture concentration Raq is estimated based on the difference between the transition of the output torque TQ and the transition of the output torque TQ corresponding to the case where the moisture concentration Raq is zero. The second embodiment is different from the first embodiment only in this respect.

  Specifically, the CPU 71 of the second embodiment executes the same routine as the routine shown in FIG. 4 executed by the CPU 71 of the first embodiment, and the routine shown by the flowchart in FIG. 15 corresponding to FIG. Execute. Hereinafter, the routine shown in FIG. 15 unique to the second embodiment will be described. In FIG. 15, the same steps as those shown in FIG. 6 are denoted by the same step numbers as those in FIG.

  In step 1505, the CPU 71 of the second embodiment determines the reference output torque TQstd based on the reference output torque determination table TQstd (NE, KL). This reference output torque TQstd is an output torque TQ obtained when the water concentration Raq is zero and ignition is performed at the reference ignition timing MBTstd. In step 1510, the CPU 71 of the second embodiment determines whether the output torque TQ has been acquired by the torque sensor 69.

  FIG. 16 is a graph showing the relationship between the ignition timing CAig and the output torque TQ. In FIG. 16, a curve representing the relationship between the ignition timing CAig and the output torque TQ indicated by a broken line is a case where the moisture concentration Raq is zero. Here, as described above, the greater the moisture concentration Raq, the greater the degree of deviation of the maximum pressure crank angle from the maximum torque crank angle (the crank angle difference ΔCA) (see FIG. 7). That is, the greater the moisture concentration Raq, the greater the degree of reduction of the output torque TQ corresponding to the reference ignition timing MBTstd from the reference output torque TQstd (hereinafter, this reduction degree is referred to as “output torque difference ΔTQ”). .

  In other words, the output torque difference ΔTQ is a value that changes according to the moisture concentration Raq. Therefore, the water concentration Raq can be estimated based on the output torque difference ΔTQ. The control device in this example estimates the water concentration Raq based on this knowledge. These steps 605, 1505, 615, 1510 correspond to a part of the transition acquisition means.

  Therefore, if the CPU 71 of the second embodiment determines “Yes” in step 1510, the CPU 71 proceeds to step 1515 and subtracts the output torque TQ acquired from the reference output torque TQstd determined in step 1505 to thereby reduce the output torque difference. ΔTQ is obtained. In step 1520, the CPU 71 of the second embodiment estimates the moisture concentration Raq based on the output torque difference ΔTQ obtained in step 1515 and the moisture concentration determination table MapRaq (ΔTQ).

  FIG. 17 is a diagram showing a moisture concentration determination table MapRaq (ΔTQ). According to the moisture concentration determination table MapRaq (ΔTQ), the moisture concentration Raq is estimated to be larger as the output torque difference ΔTQ is larger. These steps 1515 and 1520 correspond to a part of the moisture ratio estimating means.

As described above, according to the second embodiment of the control apparatus for an internal combustion engine according to the present invention, when the moisture concentration Raq estimation condition is satisfied, ignition is performed at the reference ignition timing MBTstd and the output torque TQ is acquired. The An output torque difference ΔTQ that is a difference between the acquired output torque and the reference output torque TQstd stored in advance corresponding to the case where the moisture concentration Raq is zero is obtained. Then, the moisture concentration Raq is estimated based on the output torque difference ΔTQ.
Here, the output torque difference ΔTQ can be a value representing the moisture concentration Raq. Accordingly, the water concentration Raq can be estimated easily and accurately as in the first embodiment.

  The present invention is not limited to the second embodiment, and various modifications can be adopted within the scope of the present invention. For example, in the second embodiment, the output torque difference ΔTQ is obtained, and the water concentration Raq is estimated based on the water concentration determination table MapRaq (ΔTQ). Instead, a predetermined crank angle range is used. The ignition is sequentially performed at a plurality of ignition timings, and the maximum torque ignition timing corresponding to the case where the output torque TQ becomes the maximum value is acquired, and the crank angle between the acquired maximum torque ignition timing and the reference ignition timing MBTstd The difference ΔMBT may be obtained, and the water concentration Raq may be estimated based on the water concentration determination table MapRaq (ΔMBT). In this case, according to the moisture concentration determination table MapRaq (ΔMBT), the greater the crank angle difference ΔMBT, the larger the moisture concentration Raq is estimated.

  Further, a curve representing the relationship between the ignition timing and the output torque obtained by sequentially performing ignition at a plurality of ignition timings within a predetermined crank angle range is obtained, and the obtained curve has a moisture ratio Rqa of zero. The crank angle difference ΔMBT may be obtained by obtaining the amount of parallel movement from the curve obtained in a certain case to the advance side from the previously stored curve.

  In the second embodiment, the moisture concentration Raq is estimated based on the moisture concentration determination table MapRaq (ΔTQ) in which only the output torque difference ΔTQ is used as an argument. Instead, the operation is further performed as an argument. The water concentration Raq may be estimated based on the water concentration determination table MapRaq (ΔTQ, NE) in which the speed NE is used. According to the moisture concentration determination table MapRaq (ΔTQ, NE), the moisture concentration Raq is estimated to be smaller as the operation speed NE is larger. Further, the moisture concentration Raq may be estimated based on a moisture concentration determination table MapRaq (ΔTQ, NE, KL) in which the load KL is further used as an argument. According to the moisture concentration determination table MapRaq (ΔTQ, NE, KL), the moisture concentration Raq is estimated to be a smaller value as the load KL increases.

  In the second embodiment, the output torque TQ is detected by the torque sensor 69. Instead, for example, a vehicle on which the internal combustion engine 10 is mounted includes a motor generator, and the output of the internal combustion engine 10 is output. When the torque is transmitted to the motor generator and a motor generator torque detection mechanism is provided, the output torque TQ may be obtained using the torque detection mechanism. In this case, the torque detection mechanism can be used effectively when acquiring the output torque TQ.

  In each of the above embodiments, the control device according to the present invention is applied to the internal combustion engine 10 that can use gasoline mixed with ethanol as a fuel. However, the fuel does not mix alcohol (for example, gasoline). The present invention may be applied to an internal combustion engine that uses

  In addition, for example, when the internal combustion engine 10 includes a second spark plug different from the spark plug 37, ignition is performed on one of these spark plugs in one combustion cycle, and ignition is performed on the other. The interval between the ignition timing at one spark plug and the timing at which a flame is detected at the other spark plug (or the combustion speed of the air-fuel mixture calculated from the interval) is acquired. Also good. The moisture concentration Raq may be estimated to be larger as the acquired interval is larger (that is, as the combustion speed of the air-fuel mixture is smaller). Moreover, it can replace with a 2nd spark plug, and the said space | interval can also be acquired by providing the probe which detects flames, such as a frame rod.

1 is a schematic configuration diagram of a system in which a control device according to a first embodiment of the present invention is applied to a spark ignition internal combustion engine. It is a figure for demonstrating the feedback control of the air fuel ratio which the control apparatus concerning 1st Embodiment of this invention performs. It is the graph which showed the relationship between ethanol concentration and a feedback coefficient. It is the flowchart which showed the program for execution of determination of the fuel injection quantity and ignition timing which CPU shown in FIG. 1 performs. It is the graph which showed the relationship between load and an operating speed, and basic ignition timing, and the graph which showed the relationship between ethanol and basic ignition timing. It is the flowchart which showed the program for execution of calculation of various values, such as a water concentration and ethanol concentration, which CPU shown in FIG. 1 performs. It is a figure for demonstrating transition of the gas pressure in a combustion chamber with respect to a crank angle when ignition is performed at the same ignition timing which changes according to a water concentration. It is the figure which showed the table which prescribes | regulates the relationship between a crank angle difference and moisture concentration which CPU shown in FIG. 1 refers. It is the figure which showed the table which prescribes | regulates the relationship between a water concentration and an ethanol concentration correction coefficient which CPU shown in FIG. 1 refers. It is the figure which showed the table which prescribes | regulates the relationship between the water concentration and the advance degree of ignition timing which CPU referred to in FIG. It is the figure which showed the table which prescribes | regulates the relationship between a water concentration and a rich control correction coefficient which CPU referred to in FIG. It is the figure which showed the table which prescribes | regulates the relationship between the ethanol concentration and the fuel injection amount correction coefficient which CPU referred to in FIG. It is a figure for demonstrating the suppression effect of the deterioration degree of a fuel consumption when ignition is performed at the ignition timing set by the control apparatus concerning 1st Embodiment of this invention. The effect of suppressing the variation degree of the output torque when the air-fuel ratio rich control is performed when the temperature of the internal combustion engine is low at the fuel injection amount set by the control device according to the first embodiment of the present invention will be described. It is a figure for doing. It is the flowchart which showed the program for execution of calculation of various values, such as a water concentration and ethanol concentration, which CPU of 2nd Embodiment of this invention performs. It is a figure for demonstrating transition of an output torque when ignition is performed at the same ignition timing which changes according to a water concentration. It is the figure which showed the table which prescribes | regulates the relationship between the output torque difference and moisture concentration which CPU of 2nd Embodiment of this invention refers. It is a figure for demonstrating transition of the gas pressure in a combustion chamber with respect to a crank angle when ignition is performed when water mixes in fuel. It is a figure for demonstrating transition of the output torque with respect to ignition timing when ignition is performed when water mixes in fuel.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Spark ignition internal combustion engine, 37 ... Spark plug, 39 ... Fuel injection valve, 65 ... Cooling water temperature sensor, 68 ... Combustion chamber pressure sensor, 69 ... Torque sensor, 70 ... Electric controller, 71 ... CPU

Claims (6)

An injection valve for injecting fuel toward the combustion chamber of the internal combustion engine;
An ignition plug for igniting an air-fuel mixture formed in the combustion chamber by the fuel injected by the injection valve;
Applied to an internal combustion engine with
Fuel injection amount determination means for determining a fuel injection amount that is an amount of fuel injected by the injection valve based on an operating state of the internal combustion engine;
Ignition timing determining means for determining an ignition timing that is a timing at which ignition is performed by the spark plug based on an operating state of the internal combustion engine;
An internal combustion engine control device comprising:
A moisture ratio estimating means for estimating a ratio of moisture contained in the fuel based on a value that changes according to a combustion speed of the air-fuel mixture;
The ignition timing determining means is
A control device for an internal combustion engine configured to determine the ignition timing based on a moisture ratio estimated by the moisture ratio estimating means. The control apparatus for an internal combustion engine according to claim 1,
The ignition timing determining means is
A control apparatus for an internal combustion engine configured to determine the ignition timing to be a more advanced timing as the moisture ratio increases. A control device for an internal combustion engine according to claim 1 or 2,
A transition acquisition means for acquiring a transition of gas pressure in the combustion chamber;
The moisture percentage estimating means includes
Estimating the moisture ratio based on the difference between the pre-stored pressure transition corresponding to the case where the moisture ratio contained in the fuel is a predetermined ratio and the pressure transition acquired by the transition acquisition means A control device for an internal combustion engine configured to A control device for an internal combustion engine according to claim 1 or 2,
Transition acquisition means for acquiring transition of output torque of the crankshaft of the internal combustion engine,
The moisture percentage estimating means includes
The ratio of the moisture based on the difference between the transition of the output torque stored in advance corresponding to the case where the ratio of the moisture contained in the fuel is a predetermined ratio and the transition of the output torque acquired by the transition acquisition means A control device for an internal combustion engine configured to estimate A control device for an internal combustion engine according to any one of claims 1 to 4,
Temperature acquisition means for acquiring the temperature of the internal combustion engine,
The fuel injection amount determining means includes
When the temperature acquired by the temperature acquisition means is lower than a predetermined temperature, the water estimated by the water ratio estimation means so that the air-fuel ratio of the mixture is richer than the stoichiometric air-fuel ratio. The control apparatus for an internal combustion engine configured to determine the fuel injection amount so that the degree of shift of the air-fuel ratio from the stoichiometric air-fuel ratio in the rich direction becomes larger as the ratio of the fuel-air ratio increases. A control device for an internal combustion engine according to claim 5,
The internal combustion engine
The fuel is configured to use a fuel containing alcohol,
Comprising an alcohol ratio acquisition means for acquiring a ratio of the alcohol contained in the fuel;
The fuel injection amount determining means includes
The control apparatus for an internal combustion engine configured to determine the fuel injection amount so that the degree of shift in the rich direction becomes greater as the alcohol ratio acquired by the alcohol ratio acquisition means increases.

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