JP2007032312A - Controller of internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a proper air-fuel ratio by approaching the air-fuel ratio to a target one by further reducing a jetted amount even in an area where a fuel jetting time is short. <P>SOLUTION: An engine ECU performs a program including a step (S106) of reducing the fuel pressure of an injector 110 for cylinder injection when the learned value of a feedback correction amount is smaller than a determination value (YES in S104) and the reduced amount of a jetted amount by the feedback correction amount and the learned value is larger than a predetermined amount. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an internal combustion engine control apparatus that calculates a fuel injection amount correction value based on an air-fuel ratio and injects an amount of fuel corresponding to the calculated correction value. .

  An injector for injecting intake passage for injecting fuel into the engine intake passage and an in-cylinder injector for injecting fuel at all times into the engine combustion chamber, the engine load being higher than a predetermined set load There is known an internal combustion engine that stops fuel injection from the intake passage injector when the engine load is low and injects fuel from the intake passage injector when the engine load is higher than the set load.

  Even in such an internal combustion engine, the fuel injection amount may not be a desired injection amount due to deposits accumulated in the injector and individual differences during manufacture. That is, the air-fuel ratio may deviate from a desired air-fuel ratio (for example, the theoretical air-fuel ratio). In order to correct the deviation of the fuel injection amount, the fuel injection amount is corrected by feedback control of the air-fuel ratio, similarly to the internal combustion engine in which one injector is provided for one cylinder.

  Japanese Patent Laying-Open No. 3-185242 (Patent Document 1) discloses a fuel injection amount control device for an internal combustion engine that accurately corrects the fuel injection amount in an internal combustion engine having a plurality of fuel injection valves per cylinder. This fuel injection amount control device learns a value based on an output signal from a control unit that controls fuel injection from a plurality of fuel injection valves according to an operating state and an oxygen sensor provided in an exhaust system of the engine. Each learning using a learning unit for correcting the fuel injection amount, a setting unit for setting a plurality of learning regions corresponding to the use states of the plurality of fuel injection valves, and each learning value learned in each of the learning regions And a correction unit that corrects the fuel injection amount in the operation state corresponding to the region.

According to the fuel injection amount control device described in this publication, the fuel injection valve that is used in the learning region matches the fuel injection valve that is used when the fuel injection amount is corrected using the learned value. Therefore, the correction accuracy of the fuel injection amount is improved. Accordingly, the air-fuel ratio followability is improved accordingly, and exhaust emission is improved. Further, since the error from the target air-fuel ratio becomes small, even if the air-fuel ratio is set to the lean side, the possibility of misfire can be reduced and fuel efficiency can be improved.
Japanese Patent Laid-Open No. 3-185242

  In an internal combustion engine in which feedback control of air-fuel ratio is performed as in the fuel injection amount control device described in Japanese Patent Laid-Open No. 3-185242, when the air-fuel ratio becomes richer than a target air-fuel ratio (for example, theoretical air-fuel ratio). The fuel injection amount is corrected so as to decrease. By the way, in the injector for fuel injection, in the relationship between the injection amount and the injection time (Q-tau characteristic), the desired injection amount cannot be injected with respect to the injection time in the region below the minimum injection amount with linearity. . That is, the accuracy of the injection amount cannot be ensured in a region where the Q-tau characteristic is not linear (a region where the injection amount is extremely small). For this reason, in the injector, a guard is provided so that the injection time is equal to or longer than the time corresponding to the minimum injection amount. Therefore, even if the air-fuel ratio is richer than the target air-fuel ratio, the fuel injection amount cannot be reduced by the air-fuel ratio feedback control, and an appropriate air-fuel ratio may not be realized. Further, in an operation state where the injection time is close to the time corresponding to the minimum injection amount, it is not always possible to obtain an injection amount that uniquely corresponds to the injection time. Therefore, feedback control is prohibited in order to suppress mislearning and the like in feedback control. Even in such a case, the fuel injection amount cannot be reduced by air-fuel ratio feedback control, and an appropriate air-fuel ratio may not be realized.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a control device for an internal combustion engine that can realize an appropriate air-fuel ratio.

  A control apparatus for an internal combustion engine according to a first aspect controls an internal combustion engine provided with a fuel injection means for injecting fuel into a cylinder. The control device includes a detection unit for detecting an air-fuel ratio of the internal combustion engine, a calculation unit for calculating a correction value for the fuel injection amount based on the detected air-fuel ratio, and an amount of fuel corresponding to the correction value. When the reduction amount of the fuel injection amount by the correction value is larger than a predetermined amount, the pressure of the fuel supplied to the fuel injection unit is controlled. Pressure reducing means for reducing the size.

  According to the first invention, the air-fuel ratio is detected, and an amount of fuel corresponding to the correction value calculated based on the detected air-fuel ratio is injected. For example, when the air-fuel ratio is richer than the target air-fuel ratio, the correction value is calculated so as to decrease the fuel injection amount. Even if the fuel injection amount corresponding to the correction value at this time is equal to or less than the minimum injection amount with the linearity of the fuel injection means, the accuracy of the injection amount cannot be ensured, so the injection time shorter than the injection time corresponding to the minimum injection amount Cannot be set. In this case, it may be impossible to make the air-fuel ratio lean to the desired air-fuel ratio. Therefore, when the amount of decrease in the fuel injection amount due to the correction value is larger than a predetermined amount, the pressure of the fuel supplied to the fuel injection means is reduced. Thereby, the injection amount can be reduced without shortening the injection time. Therefore, the air-fuel ratio can be made leaner and close to the target air-fuel ratio. As a result, it is possible to provide a control device for an internal combustion engine that can realize an appropriate air-fuel ratio.

  A control apparatus for an internal combustion engine according to a second invention controls an internal combustion engine provided with fuel injection means for injecting fuel into a cylinder. The control device includes a detection unit for detecting an air-fuel ratio of the internal combustion engine and a calculation for calculating a correction value of the fuel injection amount based on the detected air-fuel ratio when a predetermined condition is satisfied. Means, a control means for controlling the fuel injection means so that an amount of fuel corresponding to the correction value is injected, and a reduction amount of the fuel injection amount by the correction value is larger than a predetermined amount, And a relaxation means for relaxing a predetermined condition.

  According to the second aspect of the invention, the air-fuel ratio is detected, and an amount of fuel corresponding to the correction value calculated based on the detected air-fuel ratio is injected. By the way, in a fuel injection means such as an injector, a desired injection amount is injected with respect to the injection time in the region below the minimum injection amount with linearity in the relationship between the injection amount and the injection time (Q-tau characteristic). Can not. That is, the accuracy of the injection amount cannot be ensured in a region where the Q-tau characteristic is not linear (a region where the injection amount is extremely small). For this reason, for example, the correction value of the fuel injection amount is calculated based on the detected air-fuel ratio only when the condition that the fuel injection time from the fuel injection means is longer than a predetermined time is satisfied. . This correction value is calculated so as to decrease the fuel injection amount when the air-fuel ratio is richer than the target air-fuel ratio. At this time, since the injection time corresponding to the fuel injection amount is shorter than the injection time that should be satisfied to start the calculation of the correction value, the air-fuel ratio becomes the target air-fuel ratio if the correction value is not calculated. Even if it is richer than this, there may be a case where the injection amount cannot be reduced by the correction value. Therefore, when the amount of decrease in the fuel injection amount due to the correction value is larger than the predetermined amount, the predetermined condition to be satisfied to start the calculation of the correction value is relaxed. As a result, it is possible to enlarge the region where the correction value can be calculated and the fuel injection amount can be reduced. Therefore, the air-fuel ratio can be made leaner and close to the target air-fuel ratio. As a result, it is possible to provide a control device for an internal combustion engine that can realize an appropriate air-fuel ratio.

  In the control apparatus for an internal combustion engine according to the third invention, in addition to the configuration of the second invention, the predetermined condition is that the fuel injection time from the fuel injection means is longer than the predetermined time. is there. The mitigation means includes means for shortening the predetermined time when the amount of decrease in the fuel injection amount by the correction value is larger than the predetermined amount.

  According to the third invention, since the accuracy of the injection amount cannot be ensured in the region where the fuel injection amount is small, the fuel injection time from the fuel injection means is set to a predetermined time in order to suppress erroneous calculation of the correction value. If the condition of longer than is satisfied, the correction value of the fuel injection amount is calculated. At this time, since the injection time corresponding to the fuel injection amount is shorter than the injection time that should be satisfied to start the calculation of the correction value, the air-fuel ratio becomes the target air-fuel ratio if the correction value is not calculated. Even if it is richer than this, there may be a case where the injection amount cannot be reduced by the correction value. Therefore, when the amount of decrease in the fuel injection amount due to the correction value is larger than a predetermined amount, the time that must be satisfied to start the calculation of the correction value is shortened. As a result, it is possible to enlarge the region where the correction value can be calculated and the fuel injection amount can be reduced. Therefore, the air-fuel ratio can be made leaner and close to the target air-fuel ratio. As a result, an appropriate air-fuel ratio can be realized.

  A control device for an internal combustion engine according to a fourth invention is, in addition to the configuration of the second or third invention, means for detecting a combustion abnormality of the internal combustion engine, and prohibits correction when a combustion abnormality is detected. And means.

  According to the fourth aspect of the present invention, when the fuel injection amount is reduced more than necessary, the fuel required for the air-fuel mixture to normally fuel in the cylinder is insufficient, and combustion abnormality such as misfire occurs. When a combustion abnormality occurs, a sudden rotational fluctuation or the like may occur. Therefore, correction is prohibited when a combustion abnormality is detected. As a result, an appropriate air-fuel ratio that can normally burn the air-fuel mixture can be realized.

  In the control apparatus for an internal combustion engine according to the fifth invention, in addition to the configuration of any one of the first to fourth inventions, the fuel injection means is a first fuel injection means. The internal combustion engine is provided with a second fuel injection means for injecting fuel into the intake passage in addition to the first fuel injection means. The correction value is a correction value for the fuel injection amount from the first fuel injection means.

  According to the fifth invention, the internal combustion engine is provided with the first fuel injection means for injecting fuel into the cylinder and the second fuel injection means for injecting fuel into the intake passage. In order to inject fuel into the cylinder in such an internal combustion engine, a high fuel pressure is required. Therefore, the pressure of the fuel supplied to the first fuel injection means is supplied to the second fuel injection means. Higher than fuel pressure. For this reason, the injection time of the first fuel injection unit is likely to approach the injection time corresponding to the minimum injection amount, compared to the injection time of the second fuel injection unit. Therefore, when the amount of decrease in the fuel injection amount by the correction value of the fuel injection amount from the first fuel injection means is larger than a predetermined amount, the pressure of the fuel supplied to the fuel injection means is reduced or corrected. A predetermined condition that should be satisfied in order to start calculating the value may be relaxed. As a result, the air-fuel ratio can be made leaner and close to the target air-fuel ratio. Therefore, an appropriate air / fuel ratio can be realized.

  In the control apparatus for an internal combustion engine according to the sixth invention, in addition to the configuration of the fifth invention, the first fuel injection means is an in-cylinder injector, and the second fuel injection means is the intake passage. It is an injector for injection.

  According to the sixth aspect of the invention, in the internal combustion engine that shares the injected fuel by separately providing the in-cylinder injector that is the first fuel injection means and the intake passage injection injector that is the second fuel injection means A simple air-fuel ratio can be realized.

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

<First Embodiment>
FIG. 1 shows a schematic configuration diagram of an engine system controlled by an engine ECU (Electronic Control Unit) which is a control device for an internal combustion engine according to an embodiment of the present invention. FIG. 1 shows an in-line four-cylinder gasoline engine as an engine. However, the present invention is not limited to such a type of engine, and V-type six-cylinder, V-type eight-cylinder, in-line six-cylinder, etc. The present invention can be applied to any engine as long as it has at least an in-cylinder injector for each cylinder. In the following description, a case where each cylinder has an in-cylinder injector and an intake manifold injector will be described.

  As shown in FIG. 1, the engine 10 includes four cylinders 112, and each cylinder 112 is connected to a common surge tank 30 via a corresponding intake manifold 20. The surge tank 30 is connected to an air cleaner 50 via an intake duct 40, an air flow meter 42 is disposed in the intake duct 40, and a throttle valve 70 driven by an electric motor 60 is disposed. The opening degree of throttle valve 70 is controlled based on the output signal of engine ECU 300 independently of accelerator pedal 100. On the other hand, each cylinder 112 is connected to a common exhaust manifold 80, and this exhaust manifold 80 is connected to a three-way catalytic converter 90.

  For each cylinder 112, an in-cylinder injector 110 for injecting fuel into the cylinder, and an intake passage injection injector 120 for injecting fuel into the intake port or / and the intake passage. And are provided respectively. These injectors 110 and 120 are controlled based on the output signal of engine ECU 300, respectively. The in-cylinder injectors 110 are connected to a common fuel distribution pipe 130, and the fuel distribution pipe 130 is connected to the fuel distribution pipe 130 through a check valve that can flow to the engine-driven high pressure. It is connected to the fuel pumping device 150. In the present embodiment, an internal combustion engine in which two injectors are separately provided will be described, but the present invention is not limited to such an internal combustion engine. For example, it may be an internal combustion engine having one injector that has both an in-cylinder injection function and an intake passage injection function.

  As shown in FIG. 1, the discharge side of the high-pressure fuel pump 150 is connected to the suction side of the fuel distribution pipe 130 via an electromagnetic spill valve. The smaller the opening of the electromagnetic spill valve, the higher the pressure of the high-pressure fuel pump 150. When the amount of fuel supplied from the device 150 into the fuel distribution pipe 130 is increased and the electromagnetic spill valve is fully opened, the fuel supply from the high pressure fuel pump 150 to the fuel distribution pipe 130 is stopped. ing. The electromagnetic spill valve is controlled based on the output signal of engine ECU 300. Details of this will be described later.

  On the other hand, each intake passage injector 120 is connected to a common low-pressure side fuel distribution pipe 160, and the fuel distribution pipe 160 and the high-pressure fuel pump 150 are driven by an electric motor via a common fuel pressure regulator 170. It is connected to a low pressure fuel pump 180 of the type. Further, the low pressure fuel pump 180 is connected to the fuel tank 200 via a fuel filter 190. The fuel pressure regulator 170 returns a part of the fuel discharged from the low-pressure fuel pump 180 to the fuel tank 200 when the fuel pressure of the fuel discharged from the low-pressure fuel pump 180 becomes higher than a predetermined set fuel pressure. Therefore, the fuel pressure supplied to the intake manifold injector 120 and the fuel pressure supplied to the high-pressure fuel pump 150 are prevented from becoming higher than the set fuel pressure.

  The engine ECU 300 is composed of a digital computer, and is connected to each other via a bidirectional bus 310, a ROM (Read Only Memory) 320, a RAM (Random Access Memory) 330, a CPU (Central Processing Unit) 340, and an input port 350. And an output port 360.

  The air flow meter 42 generates an output voltage proportional to the amount of intake air, and the output voltage of the air flow meter 42 is input to the input port 350 via the A / D converter 370. A water temperature sensor 380 that generates an output voltage proportional to the engine cooling water temperature is attached to the engine 10, and the output voltage of the water temperature sensor 380 is input to the input port 350 via the A / D converter 390.

  A fuel pressure sensor (fuel pressure sensor) 400 that generates an output voltage proportional to the fuel pressure in the fuel distribution pipe 130 is attached to the fuel distribution pipe 130, and the output voltage of the fuel pressure sensor 400 is converted into an A / D converter. It is input to the input port 350 via 410. The exhaust manifold 80 upstream of the three-way catalytic converter 90 is provided with an air-fuel ratio sensor 420 that generates an output voltage proportional to the oxygen concentration in the exhaust gas. The output voltage of the air-fuel ratio sensor 420 is converted into an A / D converter. It is input to the input port 350 via 430.

The air-fuel ratio sensor 420 in the engine system according to the present embodiment is a global air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage proportional to the air-fuel ratio of the air-fuel mixture burned by the engine 10. The air-fuel ratio sensor 420 may be an O ₂ sensor that detects whether the air-fuel ratio of the air-fuel mixture burned in the engine 10 is rich or lean with respect to the stoichiometric air-fuel ratio. Good.

  In the present embodiment, engine ECU 300 executes feedback control to the air-fuel ratio when a predetermined execution start condition is met. The feedback control execution start condition includes a condition that the fuel injection time is longer than a threshold value.

  In the feedback control, a feedback correction amount for the total fuel injection amount is calculated based on the output voltage of the air-fuel ratio sensor 420. Further, when a predetermined learning condition is satisfied, a learning value of the feedback correction amount (a value representing a constant deviation amount of the fuel injection amount) is calculated. The calculation of the feedback correction amount and its learning value is performed within a predetermined learning region with the intake air amount as a parameter. The learning area will be described in detail later.

  In the present embodiment, when the air-fuel ratio is lean (when leaner than the stoichiometric air-fuel ratio), the feedback correction amount is calculated to increase. When the air-fuel ratio is rich (when it is richer than the theoretical air-fuel ratio), the feedback correction amount is calculated to decrease. As a method for calculating the feedback correction amount, a known general technique may be used. Therefore, detailed description thereof will not be repeated here.

  The learning value is calculated by adding the update amount determined based on the map to the previously calculated learning value or subtracting from the previously calculated learning value when a predetermined learning condition is satisfied. The The predetermined learning condition is, for example, a condition that the average value (control center value) of the feedback correction amount is smaller than the threshold value (1) or threshold value (2) (threshold value (2)> threshold value It is a condition that it is larger than (1)).

The learning value is calculated as a smaller value as the fuel injection amount is excessive (as the actual fuel injection amount is larger than the target fuel injection amount). On the other hand, the smaller the fuel injection amount (the smaller the actual fuel injection amount than the target fuel injection amount), the larger the learning value is calculated.
In addition, about the calculation method of a learning value, what is necessary is just to use a well-known general technique, Therefore The further detailed description is not repeated here.

  The fuel injection amount is corrected based on the feedback correction amount and the learned value. That is, the larger the feedback correction amount and the learning value, the more the fuel injection amount is corrected. The smaller the feedback correction amount and the learned value, the smaller the fuel injection amount is corrected. In the present embodiment, the fuel injection amount correction amount (hereinafter also referred to as fuel correction amount) is calculated as the sum of the feedback correction amount and the learning value.

  The accelerator pedal 100 is connected to an accelerator opening sensor 440 that generates an output voltage proportional to the depression amount of the accelerator pedal 100, and the output voltage of the accelerator opening sensor 440 is input to the input port 350 via the A / D converter 450. Is input. The input port 350 is connected to a rotational speed sensor 460 that generates an output pulse representing the engine rotational speed. In the ROM 320 of the engine ECU 300, the value of the fuel injection amount and the engine cooling that are set according to the operating state based on the engine load factor and the engine speed obtained by the accelerator opening sensor 440 and the engine speed sensor 460 described above are stored. Correction values based on the water temperature and the like are previously mapped and stored.

  The fuel supply mechanism of the engine 10 described above will be described with reference to FIG. As shown in FIG. 2, this fuel supply mechanism is provided in a fuel tank 200, and feed pump 1100 that supplies fuel with a discharge pressure of low pressure (pressure regulator pressure of about 0.3 MPa) (low pressure fuel of FIG. 1). The same as the pump 180), a high-pressure fuel pump 150 (high-pressure fuel pump 1200) driven by a cam 1210, and a high-pressure delivery pipe 1110 (see FIG. 1) provided to supply high-pressure fuel to the in-cylinder injector 110. The same as fuel distribution pipe 130), in-cylinder injector 110 for each cylinder provided in high-pressure delivery pipe 1110, and low-pressure delivery pipe provided for supplying fuel to intake passage injector 120 1120 and the intake manifold of each cylinder provided in the low pressure delivery pipe 1120 And a intake manifold injector 120 of each individual.

  The discharge port of the feed pump 1100 of the fuel tank 200 is connected to a low pressure supply pipe 1400, and the low pressure supply pipe 1400 branches into a low pressure delivery communication pipe 1410 and a pump supply pipe 1420. The low pressure delivery communication pipe 1410 is connected to a low pressure delivery pipe 1120 provided with an intake passage injector 120.

  The pump supply pipe 1420 is connected to the inlet of the high pressure fuel pump 1200. A pulsation damper 1220 is provided in front of the entrance of the high-pressure fuel pump 1200 to reduce fuel pulsation.

  The discharge port of the high-pressure fuel pump 1200 is connected to the high-pressure delivery communication pipe 1500, and the high-pressure delivery communication pipe 1500 is connected to the high-pressure delivery pipe 1110. A relief valve 1140 provided in the high pressure delivery pipe 1110 is connected to the high pressure fuel pump return pipe 1600 via the high pressure delivery return pipe 1610. The return port of the high pressure fuel pump 1200 is connected to the high pressure fuel pump return pipe 1600. The high-pressure fuel pump return pipe 1600 is connected to the return pipe 1630 and is connected to the fuel tank 200.

  FIG. 3 shows an enlarged view of the vicinity of the high-pressure fuel pump 150 shown in FIG. The high-pressure fuel pump 150 includes a high-pressure fuel pump 1200, a pump plunger 1206 that is driven by a cam 1210 and slides up and down, an electromagnetic spill valve 1202, and a check valve 1204 with a leak function.

  When the pump plunger 1206 is moved downward by the cam 1210 and the electromagnetic spill valve 1202 is open, fuel is introduced (sucked), and the pump plunger 1206 is moved upward by the cam 1210. The timing at which the electromagnetic spill valve 1202 is closed during the operation is changed to control the amount of fuel discharged from the high-pressure fuel pump 1200. During the pressurizing stroke in which the pump plunger 1206 is moving upward, more fuel is discharged as the timing for closing the electromagnetic spill valve 1202 is earlier, and less fuel is discharged as the pump plunger 1206 is moved upward.

  The characteristics of the high-pressure fuel pump 1200 will be described with reference to FIG. FIG. 4A is a pump characteristic curve showing the relationship between the crank angle (CA) for closing the electromagnetic spill valve 1202 and the discharge amount Q when the fuel pressure is 4 MPa, with the rotational speed NE of the engine 10 as a parameter. FIG. 4B is a pump characteristic curve showing the relationship between the crank angle (CA) for closing the electromagnetic spill valve 1202 and the discharge amount Q when the fuel pressure is 13 MPa, with the rotational speed NE of the engine 10 as a parameter. In addition to the 4 MPa and 13 MPa, the fuel pressure P has a characteristic curve analyzed using the fuel pressure P as a parameter at an appropriate interval between 4 MPa and 13 MPa.

  As shown in FIGS. 4A and 4B, in any case, the discharge amount Q of the high-pressure fuel pump 1200 has the fuel pressure P and the engine speed NE as parameters. For this reason, when the required discharge amount (target discharge amount) is determined, the crank angle (CA) for closing the electromagnetic spill valve 1202 is calculated as shown by the arrows in FIG. 4 (A) and FIG. 4 (B). be able to.

  For example, even when the required discharge amount is Q (1) and the engine speed NE is NE (3), the crank angle CA for closing the electromagnetic spill valve 1202 is different if the fuel pressure P is different. Specifically, in this case, when the fuel pressure P is 4 MPa, the crank angle CA that closes the electromagnetic spill valve 1202 is CA (1), and when the fuel pressure P is 13 MPa, the crank angle CA that closes the electromagnetic spill valve 1202 is CA (2). It becomes.

  Further, even when the required discharge amount is Q (1) and the fuel pressure P is 4 MPa, the crank angle CA for closing the electromagnetic spill valve 1202 is different if the engine speed NE is different. Specifically, in this case, the crank angle CA for closing the electromagnetic spill valve 1202 is CA (1) when the engine speed NE is NE (3), and the electromagnetic spill valve 1202 is when the engine speed NE is NE (1). The crank angle CA for closing is CA (3).

  When the crank angle (CA) for closing the electromagnetic spill valve 1202 is early, a large amount of fuel is discharged from the high pressure fuel pump 1200, and when the crank angle (CA) for closing the electromagnetic spill valve 1202 is slow, a small amount of fuel is discharged from the high pressure fuel pump 1200. The If the electromagnetic spill valve 1202 is not closed, it remains open and the pump plunger 1206 slides up and down as long as the cam 1210 rotates (as long as the engine 10 rotates). Since 1202 is not closed, the fuel is not pressurized, and the discharge amount Q becomes zero.

  The pressurized fuel is pushed open to the high pressure delivery pipe 1110 through the high pressure delivery communication pipe 1500 by pushing open the check valve 1204 with leak function (set pressure of about 60 kPa). At this time, feedback control is performed using the fuel pressure by the fuel pressure sensor 400 provided in the high-pressure delivery pipe 1110.

  When the crank angle (CA) for closing the electromagnetic spill valve 1202 is fast (the time during which the electromagnetic spill valve 1202 is closed is long), the fuel discharge amount of the high-pressure fuel pump 1200 increases and the fuel pressure P increases. Further, if the crank angle (CA) for closing the electromagnetic spill valve 1202 is slow (the time during which the electromagnetic spill valve 1202 is closed is short), the fuel discharge amount of the high-pressure fuel pump 1200 decreases and the fuel pressure P decreases. .

  When operating the high-pressure fuel pump 1200, the engine speed NE is detected, the fuel pressure P of the high-pressure fuel system is detected, and PI is adjusted so as to eliminate the deviation between the detected fuel pressure P and the target fuel pressure P (0). Feedback control is performed.

  In this PI feedback control, a required discharge amount Q that is a fuel discharge amount from the high-pressure fuel pump 1200 is calculated.

The required discharge rate Q is
Q = Qp + Qi + F (1)
Here, the Qp term is a proportional term in PI feedback control, the Qi term is an integral term in PI feedback control, and the F term represents a required injection amount.

The required injection amount F is obtained by using f as a function.
F = f (load, increase, DI ratio r) (2)
Is calculated by

  Further, the proportional term Qp is calculated using the following equation (3) based on the actual fuel pressure P, the preset target fuel pressure P (0), and the like.

Qp = K (1) · (P (0) −P) (3)
Here, K (1) is a coefficient, P is the detected actual fuel pressure, and P (0) is the target fuel pressure. As can be seen from equation (3), the actual fuel pressure P is smaller than the target fuel pressure P (0) and the difference between the two ("P (0) -P") (> 0) is large. The proportional term Qp (> 0) becomes a larger value, and the fuel discharge amount of the high-pressure fuel pump 1200 is increased. Conversely, as the actual fuel pressure P becomes larger than the target fuel pressure P (0) and the difference between them (“P (0) −P”) (<0) becomes smaller, the proportional term Qp (< 0) is a small value and is changed to a side where the fuel discharge amount of the high-pressure fuel pump 1200 is reduced.

  Furthermore, the integral term Qi is calculated using the following equation (4) based on the previous integral term Qi, the actual fuel pressure P, the preset target fuel pressure P (0), and the like.

Qi = Qi + K (2) · (P (0) −P) (4)
Here, K (2) is a coefficient, P is an actual fuel pressure, and P (0) is a target fuel pressure. As can be seen from the equation (4), while the actual fuel pressure P is smaller than the target fuel pressure P (0), it corresponds to the difference between them (“P (0) −P”) (> 0). The obtained value is added to the integral term Qi every predetermined period. As a result, the integral term Qi is gradually updated to a larger value and is changed to the side where the required discharge amount Q of the high-pressure fuel pump 1200 is increased. Conversely, while the fuel pressure P is larger than the target fuel pressure P (0), the value corresponding to the difference between the two (“P (0) −P”) (<0) is an integral term for each predetermined period. Subtracted from Qi. As a result, the integral term Qi is gradually updated to a small value, and is changed to a side where the required discharge amount Q of the high-pressure fuel pump is reduced.

  The required discharge amount Q is calculated using the above equations (1) to (4), and the crank angle CA indicating the timing for closing the electromagnetic spill valve 1202 that satisfies the required discharge amount Q is calculated using the map shown in FIG. (With engine speed NE and fuel pressure P as parameters). When calculating the crank angle (CA) representing the timing for closing the electromagnetic spill valve 1202, the engine speed NE and the fuel pressure P are used as parameters, so that sufficiently good control characteristics can be obtained even under the influence of them. become.

  Note that the ratio (θ / θ (0)) of the cam angle θ at which the electromagnetic spill valve 1202 is closed to the cam angle θ (0) corresponding to the pumping stroke of the high-pressure fuel pump is calculated as a duty ratio that is a control value. Then, the electromagnetic spill valve 1202 may be controlled using this duty ratio.

  Referring to FIGS. 5 and 6, the injection ratio of in-cylinder injector 110 and intake manifold injector 120 (hereinafter referred to as DI ratio (r)), which is information corresponding to the operating state of engine 10, is also referred to. Will be described). These maps are stored in the ROM 320 of the engine ECU 300. FIG. 5 is a warm map of the engine 10, and FIG. 6 is a cold map of the engine 10.

  As shown in FIG. 5 and FIG. 6, these maps are shown in percentages where the engine 10 rotational speed is on the horizontal axis, the load factor is on the vertical axis, and the share ratio of the in-cylinder injector 110 is the DI ratio r. It is shown.

  As shown in FIGS. 5 and 6, the DI ratio r is set for each operation region determined by the rotational speed and load factor of the engine 10. “DI ratio r = 100%” means a region where fuel injection is performed only from in-cylinder injector 110, and “DI ratio r = 0%” means from intake manifold injector 120. This means that only the region where fuel injection is performed. “DI ratio r ≠ 0%”, “DI ratio r ≠ 100%” and “0% <DI ratio r <100%” indicate that in-cylinder injector 110 and intake passage injector 120 perform fuel injection. It means that the area is shared. In general, the in-cylinder injector 110 contributes to an increase in output performance, and the intake manifold injector 120 contributes to the uniformity of the air-fuel mixture. By using two types of injectors having different characteristics depending on the rotation speed and load factor of the engine 10, the engine 10 is in a normal operation state (for example, when the catalyst is warmed up at idle when the engine 10 is in an abnormal state other than the normal operation state). In this case, only homogeneous combustion is performed.

  Further, as shown in FIG. 5 and FIG. 6, the DI share ratio r of the in-cylinder injector 110 and the intake manifold injector 120 is defined separately for the warm time map and the cold time map. did. If the temperature of the engine 10 is different, the temperature of the engine 10 is detected by detecting the temperature of the engine 10 using a map set so that the control areas of the in-cylinder injector 110 and the intake manifold injector 120 are different. If it is equal to or higher than a predetermined temperature threshold value, the map at the time of warming in FIG. 5 is selected. Otherwise, the map at the time of cold shown in FIG. 6 is selected. Based on the selected maps, the in-cylinder injector 110 and / or the intake manifold injector 120 are controlled based on the rotation speed and load factor of the engine 10.

  In the present embodiment, the fuel injection amount from in-cylinder injector 110 and the fuel from intake manifold injector 120 are based on DI ratio r so that the total fuel injection amount becomes a desired injection amount. The injection amount is determined.

  The engine speed and load factor of engine 10 set in FIGS. 5 and 6 will be described. In FIG. 5, NE (1) is set to 2500 to 2700 rpm, KL (1) is set to 30 to 50%, and KL (2) is set to 60 to 90%. Further, NE (3) in FIG. 6 is set to 2900-3100 rpm. That is, NE (1) <NE (3). In addition, NE (2) in FIG. 5 and KL (3) and KL (4) in FIG. 6 are also set as appropriate.

  When FIG. 5 and FIG. 6 are compared, NE (3) of the map for cold shown in FIG. 6 is higher than NE (1) of the map for warm shown in FIG. This indicates that as the temperature of the engine 10 is lower, the control range of the intake manifold injector 120 is expanded to a higher engine speed range. That is, since the engine 10 is in a cold state, deposits are unlikely to accumulate at the injection port of the in-cylinder injector 110 (even if fuel is not injected from the in-cylinder injector 110). For this reason, it sets so that the area | region which injects a fuel using the intake manifold injector 120 may be expanded, and a homogeneity can be improved.

  Comparing FIG. 5 and FIG. 6, in the region where the engine 10 has a rotational speed of NE (1) or higher in the warm map and in the region of NE (3) or higher in the cold map, “DI ratio r = 100% ". Further, the load factor is “DI ratio r = 100%” in the region of KL (2) or higher in the warm map and in the region of KL (4) or higher in the cold map. This indicates that only the in-cylinder injector 110 is used in a predetermined high engine speed region, and only the in-cylinder injector 110 is used in a predetermined high engine load region. . That is, in the high speed region and the high load region, even if the fuel is injected only by the in-cylinder injector 110, the engine 10 has a high rotational speed and load, and the intake amount is large. It is because it is easy to homogenize. Thus, the fuel injected from the in-cylinder injector 110 is vaporized with latent heat of vaporization (sucking heat from the combustion chamber) in the combustion chamber. Thereby, the temperature of the air-fuel mixture at the compression end is lowered. As a result, the knocking performance is improved. Further, since the temperature of the combustion chamber is lowered, the suction efficiency is improved and high output can be expected.

  In the warm map shown in FIG. 5, only the in-cylinder injector 110 is used at a load factor KL (1) or less. This indicates that when the temperature of the engine 10 is high, only the in-cylinder injector 110 is used in a predetermined low load region. This is because when the engine 10 is warm, the engine 10 is in a warm state, and deposits are likely to accumulate at the injection port of the in-cylinder injector 110. However, since the injection port temperature can be lowered by injecting fuel using the in-cylinder injector 110, it is conceivable to avoid deposit accumulation, and the minimum fuel injection amount of the in-cylinder injector Therefore, it is conceivable that the in-cylinder injector 110 is not blocked, and for this reason, the in-cylinder injector 110 is used as an area.

  Comparing FIG. 5 and FIG. 6, the region of “DI ratio r = 0%” exists only in the cold map of FIG. 6. This indicates that when the temperature of the engine 10 is low, only the intake manifold injector 120 is used in a predetermined low load region (KL (3) or less). This is because the engine 10 is cold and the load on the engine 10 is low and the intake air amount is low, so that the fuel is difficult to atomize. In such a region, it is difficult to perform good combustion with the fuel injection by the in-cylinder injector 110. In particular, a high output using the in-cylinder injector 110 is required in the region of low load and low rotation speed. Therefore, only the intake passage injector 120 is used without using the in-cylinder injector 110.

  In addition, in the case other than the normal operation, the in-cylinder injector 110 is controlled so as to perform stratified combustion when the engine 10 is at the time of catalyst warm-up when idling (in a non-normal operation state). By performing stratified charge combustion only during such catalyst warm-up operation, catalyst warm-up is promoted and exhaust emission is improved.

  With reference to FIGS. 7 and 8, the learning region in which the feedback correction amount and its learning value are calculated will be described. FIG. 7 shows a learning area in the warm map, and FIG. 8 shows a learning area in the cold map.

  In FIG. 7 and FIG. 8, a region sandwiched between curves indicated by alternate long and short dashed lines is a learning region. The learning area is divided according to the intake air amount. The reason why the learning area is set according to the intake air amount is that the error in the output of the air flow meter 42 differs depending on the intake air amount.

  In the present embodiment, four learning areas from learning areas (1) to (4) are provided. The intake air amount increases in the order of the learning area (1), the learning area (2), the learning area (3), and the learning area (4). Note that the number of learning regions is not limited to four.

  In the present embodiment, in addition to the learning area, the injection area ("DI ratio r = 100%" area, "0% <DI ratio r <100%" area, and "DI ratio r = 0%" area) ), The feedback correction amount and its learning value are calculated. That is, for each injection region, a feedback correction amount is calculated for each learning region, and a learning value is calculated corresponding to the injection region and the learning region as shown in FIG. FIG. 9 shows a state where one learning value is calculated for each learning region in each injection region. Square points in FIG. 9 indicate learning values in the region of “DI ratio r = 100%”. Circle points indicate learning values in the region of “0% <DI ratio r <100%”. Triangular points indicate learning values in the region of “DI ratio r = 0%”. The calculated learning value is stored in the RAM 330.

  Referring to FIG. 10, a control structure of a program executed by engine ECU 300 that is the control device for the internal combustion engine according to the present embodiment will be described.

  In step (hereinafter, step is abbreviated as S) 100, engine ECU 300 determines DI ratio r based on the maps shown in FIGS. In S102, engine ECU 300 determines whether or not “DI ratio r = 100%”. If “DI ratio r = 100%” (YES in S102), the process proceeds to S104. Otherwise (NO in S102), this process ends.

  In S104, engine ECU 300 determines whether or not the learning value of the feedback correction amount is smaller than the determination value. If the learning value is smaller than the determination value (YES in S104), it is determined that the feedback correction amount or the amount of decrease in the injection amount due to the learning value is greater than the predetermined amount, and the process proceeds to S106. Otherwise (NO in S104), this process ends.

  In S106, engine ECU 300 decreases the fuel pressure of in-cylinder injector 110. Engine ECU 300 reduces the fuel pressure of in-cylinder injector 110 by decreasing target fuel pressure P (0), for example. Note that the fuel pressure of in-cylinder injector 110 may be reduced by reducing the duty ratio. Thereafter, this process ends.

  The operation of engine ECU 300 that is the control device for the internal combustion engine according to the present embodiment based on the above-described structure and flowchart will be described.

  If abnormality occurs in in-cylinder injector 110 and the injection amount becomes excessive, if “DI ratio r = 100%” (YES in S104), that is, fuel injection from in-cylinder injector 110 is performed. In the region where the operation is performed, the feedback correction amount and the learning value are calculated so that the fuel injection amount is reduced by the air-fuel ratio feedback control.

  At this time, even if the reduction amount of the fuel injection amount due to the feedback correction amount or the learning value is large, if the injection amount becomes too small, the accuracy cannot be secured, so the injection time corresponds to the minimum injection amount with linearity. Can't fall below time. In particular, since the in-cylinder injector 110 is set to have a high fuel pressure in order to inject fuel directly into the cylinder, the injection time is shorter and the injection time corresponding to the minimum injection amount than the intake passage injector 120 is used. It is easy to take a guard at.

  Thus, when the injection time is guarded by the injection time corresponding to the minimum injection amount, in this state, the fuel injection amount is further reduced, the air-fuel ratio is made lean, and the target air-fuel ratio (for example, the stoichiometric air-fuel ratio) is approached. There is a risk that it will not be possible.

  Therefore, if the learning value of the feedback correction amount is smaller than the determination value (YES in S104) and it can be said that the reduction amount of the injection amount due to the feedback correction amount or the learning value is larger than the predetermined amount, the in-cylinder injector The fuel pressure of 110 is reduced (S106).

  Thereby, the injection amount can be reduced without shortening the injection time. Therefore, the air-fuel ratio can be made leaner and close to the target air-fuel ratio. As a result, an appropriate air-fuel ratio can be realized.

  As described above, according to the engine ECU that is the control device according to the present embodiment, the learning value is smaller than the determination value, and it can be said that the reduction amount of the injection amount by the air-fuel ratio feedback control is larger than the predetermined amount. First, the fuel pressure of the in-cylinder injector 110 is reduced. Thereby, the injection amount can be reduced without shortening the injection time. Therefore, while ensuring the linearity of the in-cylinder injector and accurately injecting fuel, the air-fuel ratio can be made leaner and close to the target air-fuel ratio with high accuracy. As a result, an appropriate air-fuel ratio can be realized.

  In the present embodiment, when the learning value is smaller than the determination value in the region of “DI ratio r = 100%”, the fuel pressure of in-cylinder injector 110 is reduced, but “DI ratio r = When the learned value is smaller than the determination value in the region of “0% <DI ratio r <100%” in addition to the region of “100%”, the fuel pressure of the in-cylinder injector 110 may be reduced.

<Second Embodiment>
Hereinafter, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment described above in that the condition for starting execution of feedback control is relaxed instead of reducing the fuel pressure of in-cylinder injector 110. Other structures are the same as those in the first embodiment. The function about them is the same. Therefore, detailed description thereof will not be repeated here.

  Referring to FIG. 11, a control structure of a program executed by engine ECU 300 in the present embodiment will be described. The same processes as those in the first embodiment described above are denoted by the same step numbers, and detailed description thereof will not be repeated here.

  In S200, engine ECU 300 decreases the injection time threshold value in the feedback control execution start condition.

  In S202, engine ECU 300 determines whether or not an air-fuel mixture combustion abnormality has occurred. For example, when the engine speed NE fluctuates (when the rate of change is greater than the threshold value or when the difference between the maximum and minimum values of the engine speed is large), or when a misfire is detected, mixing It is determined that an abnormal combustion of gas has occurred. If combustion abnormality has occurred (YES in S202), the process proceeds to S204. Otherwise (NO in S202), this process ends.

  In S204, engine ECU 300 prohibits feedback control of the air-fuel ratio. Thereafter, this process ends.

  An operation of engine ECU 300 according to the present embodiment based on the above-described structure and flowchart will be described.

  If abnormality occurs in in-cylinder injector 110 and the injection amount becomes excessive, if “DI ratio r = 100%” (YES in S104), that is, fuel injection from in-cylinder injector 110 is performed. In the region where the operation is performed, the feedback correction amount and the learning value are calculated so that the fuel injection amount is reduced by the air-fuel ratio feedback control.

  If the amount of decrease in the fuel injection amount due to the feedback correction amount or the learning value increases, the injection amount decreases, so the injection time is shortened, and it becomes difficult to ensure linearity. That is, it becomes difficult to accurately inject the injection amount.

  If the air-fuel ratio feedback control is executed in such a state, the accuracy may be deteriorated, so that the feedback control is prohibited. When feedback control is prohibited in this way, erroneous calculation of the learned value can be suppressed, but in this state, even if the air-fuel ratio is richer than the target air-fuel ratio, the injection amount is reduced. The air / fuel ratio cannot be brought close to the target air / fuel ratio.

  Therefore, when the learning value is smaller than the determination value (YES in S104) and it can be said that the feedback correction amount and the amount of decrease in the injection amount due to the learning value are larger than the predetermined amount, the injection time in the feedback control execution start condition Is lowered (S200). Thereby, the area | region where the feedback control of an air fuel ratio is performed can be expanded. Therefore, the air-fuel ratio can be made leaner and close to the target air-fuel ratio. As a result, an appropriate air-fuel ratio can be realized.

  However, in a state where it is difficult to ensure the linearity of the injector, the injection amount can be further reduced and the injection time can be shortened, so that the injection amount is not stable and can be less than the injection amount necessary for normal combustion. In this case, combustion abnormality is induced and the desired operating state cannot be maintained.

  Therefore, if a combustion abnormality occurs (eg, YES in S202), such as when the engine speed NE fluctuates or misfire is detected (YES in S202), air-fuel ratio feedback control is prohibited (S204). Thereby, it is possible to obtain an appropriate air-fuel ratio at which the air-fuel mixture can normally burn by suppressing the injection amount from being reduced more than necessary.

  As described above, according to the engine ECU according to the present embodiment, when it can be said that the learning value is smaller than the determination value and the reduction amount of the injection amount by the feedback control of the air-fuel ratio is larger than the predetermined amount, The injection time threshold in the feedback control execution start condition is lowered. Thereby, the area | region where the feedback control of an air fuel ratio is performed can be expanded. Therefore, the air-fuel ratio can be made leaner and close to the target air-fuel ratio. As a result, an appropriate air-fuel ratio can be realized.

  In the present embodiment, when the learning value is smaller than the determination value in the region of “DI ratio r = 100%”, the threshold value of the injection time in the feedback control execution start condition is lowered. When the learning value is smaller than the determination value in the region of “0% <DI ratio r <100%” in addition to the region of “DI ratio r = 100%”, the threshold of the injection time in the execution start condition of the feedback control is set. It may be lowered.

<Third Embodiment>
A third embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the DI ratio r is calculated using a map different from that of the first embodiment.

  Other structures and processing flow are the same as those in the first embodiment. The function about them is the same. Therefore, detailed description thereof will not be repeated here.

  With reference to FIGS. 12 and 13, a map representing the injection ratio between in-cylinder injector 110 and intake passage injector 120, which is information corresponding to the operating state of engine 10, will be described. These maps are stored in the ROM 320 of the engine ECU 300. FIG. 12 is a map for the warm of the engine 10, and FIG. 13 is a map for the cold of the engine 10.

  12 and 13 differ from FIGS. 5 and 6 in the following points. The rotational speed of the engine 10 is “DI ratio r = 100%” in the region of NE (1) or more in the warm map and in the region of NE (3) or more in the cold map. In the region where the load factor is KL (2) or higher excluding the low rotational speed region in the warm map, and in the region where KL (4) is higher than the low rotational speed region in the cold map, “DI” Ratio r = 100% ”. This is because only the in-cylinder injector 110 is used in a predetermined high engine speed region, and only the in-cylinder injector 110 is used in a predetermined high engine load region. Indicates. However, in the high load region of the low engine speed region, mixing of the air-fuel mixture formed by the fuel injected from the in-cylinder injector 110 is not good, and the air-fuel mixture in the combustion chamber is inhomogeneous and combustion is unstable. Tend to be. For this reason, the injection ratio of the in-cylinder injector is increased with the shift to the high rotation speed region where such a problem does not occur. In addition, the injection ratio of the in-cylinder injector 110 is decreased as the engine shifts to a high load region where such a problem occurs. These changes in the DI ratio r are indicated by cross arrows in FIGS. If it does in this way, the fluctuation | variation of the output torque of an engine resulting from combustion being unstable can be suppressed. It should be noted that these things can be achieved by reducing the injection ratio of the in-cylinder injector 110 as the engine shifts to the predetermined low rotational speed region, or by the in-cylinder injection as the vehicle shifts to the predetermined low load region. The fact that it is substantially equivalent to increasing the injection ratio of the injector 110 for operation will be described. Further, areas other than such areas (areas where the crossed arrows are described in FIGS. 12 and 13) and areas where fuel is injected only by the in-cylinder injector 110 (high rotation side, low load) On the other hand, it is easy to homogenize the air-fuel mixture with the in-cylinder injector 110 alone. Thus, the fuel injected from the in-cylinder injector 110 is vaporized with latent heat of vaporization (sucking heat from the combustion chamber) in the combustion chamber. Thereby, the temperature of the air-fuel mixture at the compression end is lowered. As a result, the knocking performance is improved. Further, since the temperature of the combustion chamber is lowered, the suction efficiency is improved and high output can be expected.

  In the engine 10 described in the first to third embodiments, the homogeneous combustion is performed by setting the fuel injection timing of the in-cylinder injector 110 as the intake stroke, and the stratified combustion is performed by the in-cylinder injector 110. This can be realized by setting the fuel injection timing in the compression stroke. That is, by setting the fuel injection timing of the in-cylinder injector 110 as the compression stroke, stratified combustion is realized in which the rich air-fuel mixture is unevenly distributed around the spark plug and the entire combustion chamber ignites a lean air-fuel mixture. Can do. Further, even when the fuel injection timing of the in-cylinder injector 110 is set to the intake stroke, if rich air-fuel mixture can be unevenly distributed around the spark plug, stratified combustion can be realized even with the intake stroke injection.

  Further, the stratified combustion here includes both stratified combustion and weakly stratified combustion described below. In the weak stratified combustion, the intake passage injector 120 is injected with fuel in the intake stroke to produce a lean and homogeneous mixture in the entire combustion chamber, and the in-cylinder injector 110 is injected with fuel in the compression stroke. A rich air-fuel mixture is generated around the spark plug to improve the combustion state. Such weak stratified combustion is preferable when the catalyst is warmed up. This is due to the following reason. That is, it is necessary to significantly retard the ignition timing and maintain a good combustion state (idle state) in order to allow high-temperature combustion gas to reach the catalyst during catalyst warm-up. Moreover, it is necessary to supply a certain amount of fuel. Even if this is done by stratified combustion, there is a problem that the amount of fuel is small, and even if this is done by homogeneous combustion, there is a problem that the retard amount is small compared to stratified combustion to maintain good combustion. is there. From such a viewpoint, it is preferable to use the above-described weak stratified combustion at the time of warming up the catalyst, but either stratified combustion or weak stratified combustion may be used.

  In the engine described in the first to third embodiments, the timing of fuel injection by the in-cylinder injector 110 is preferably performed in the compression stroke for the following reason. However, in the engine 10 described above, in a basic most region (a weak operation that is performed only when the catalyst is warmed up, the intake passage injection injector 120 is injected in the intake stroke and the in-cylinder injector 110 is compressed in the compression stroke. The timing of fuel injection by the in-cylinder injector 110 other than the stratified combustion region is a basic region) is the intake stroke. However, for the following reasons, the fuel injection timing of the in-cylinder injector 110 may be temporarily set to the compression stroke injection for the purpose of stabilizing the combustion.

  By setting the fuel injection timing from the in-cylinder injector 110 during the compression stroke, the air-fuel mixture is cooled by fuel injection at a time when the in-cylinder temperature is higher. Since the cooling effect is enhanced, knock resistance can be improved. Furthermore, if the fuel injection timing from the in-cylinder injector 110 is in the compression stroke, the time from the fuel injection to the ignition timing is short, so that the air flow can be strengthened by spraying and the combustion speed can be increased. From these improvement in knocking property and increase in combustion speed, combustion fluctuation can be avoided and combustion stability can be improved.

  Furthermore, regardless of the temperature of the engine 10 (that is, whether the engine is warm or cold), it is off-idle (when the idle switch is off or the accelerator pedal is depressed). May use the warm map shown in FIG. 5 or FIG. 12 (in-cylinder injector 110 is used in the low load region regardless of the cold warm).

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

It is a schematic block diagram of the engine system controlled by the control apparatus which concerns on the 1st Embodiment of this invention. FIG. 2 is an overall schematic diagram of a fuel supply mechanism in the engine system of FIG. 1. FIG. 3 is a partially enlarged view of FIG. 2. It is a figure which shows the characteristic curve of a high pressure fuel pump. It is a figure showing DI ratio map at the time of warm memorized by engine ECU which is a control device concerning a 1st embodiment of the present invention. It is a figure showing the DI ratio map at the time of cold memorized by engine ECU which is a control device concerning a 1st embodiment of the present invention. It is FIG. (1) which shows the learning area | region of the fuel injection quantity memorize | stored in engine ECU which is a control apparatus which concerns on the 1st Embodiment of this invention. FIG. 8 is a diagram (No. 2) illustrating a fuel injection amount learning region stored in the engine ECU that is the control device according to the first embodiment of the present invention. It is a figure which shows the state by which the learning value was calculated for every learning area | region about each injection area | region. It is a flowchart which shows the control structure of the program which engine ECU which is a control apparatus which concerns on the 1st Embodiment of this invention performs. It is a flowchart which shows the control structure of the program which engine ECU which is a control apparatus which concerns on the 1st Embodiment of this invention performs. It is a figure showing the DI ratio map at the time of warm memorize | stored in engine ECU which is a control apparatus which concerns on the 3rd Embodiment of this invention. It is a figure showing DI ratio map at the time of cold memorized by engine ECU which is a control device concerning a 3rd embodiment of the present invention.

Explanation of symbols

  10 engine, 20 intake manifold, 30 surge tank, 40 intake duct, 42 air flow meter, 50 air cleaner, 60 electric motor, 70 throttle valve, 80 exhaust manifold, 90 three-way catalytic converter, 100 accelerator pedal, 110 in-cylinder injector , 112 cylinder, 119 spark plug, 120 intake manifold injector, 121 exhaust valve, 122 intake valve, 123 piston, 130 fuel distribution pipe, 150 high pressure fuel pump, 160 fuel distribution pipe (low pressure side), 170 fuel pressure regulator , 180 Low pressure fuel pump, 190 Fuel filter, 200 Fuel tank, 300 Engine ECU, 310 Bidirectional bus, 320 ROM, 330 RAM, 340 CPU, 350 ON Port, 360 output port, 370, 390, 410, 430, 450 A / D converter, 380 water temperature sensor, 400 fuel pressure sensor, 420 air-fuel ratio sensor, 440 accelerator opening sensor, 460 rpm sensor, 1100 feed pump, 1110 High pressure delivery pipe, 1120 Low pressure delivery pipe, 1140 Relief valve, 1200 High pressure fuel pump, 1202 Electromagnetic spill valve, 1204 Leak function check valve, 1206 Pump plunger, 1210 Cam, 1220 Pulsation damper, 1400 Low pressure supply pipe, 1410 Low pressure delivery communication pipe, 1420 Pump supply pipe, 1500 High pressure delivery communication pipe, 1600 High pressure fuel pump return pipe, 1610 High pressure delivery return pipe, 1 30 return pipe.

Claims (6)

A control device for an internal combustion engine comprising fuel injection means for injecting fuel into a cylinder,
Detecting means for detecting an air-fuel ratio of the internal combustion engine;
Calculation means for calculating a correction value of the fuel injection amount based on the detected air-fuel ratio;
Control means for controlling the fuel injection means such that an amount of fuel corresponding to the correction value is injected;
A control device for an internal combustion engine, comprising: a pressure reducing means for reducing the pressure of the fuel supplied to the fuel injection means when the reduction amount of the fuel injection quantity by the correction value is larger than a predetermined amount. A control device for an internal combustion engine comprising fuel injection means for injecting fuel into a cylinder,
Detecting means for detecting an air-fuel ratio of the internal combustion engine;
A calculation unit for calculating a correction value of the fuel injection amount based on the detected air-fuel ratio when a predetermined condition is satisfied;
Control means for controlling the fuel injection means such that an amount of fuel corresponding to the correction value is injected;
A control device for an internal combustion engine, comprising: mitigation means for mitigating the predetermined condition when the amount of decrease in the fuel injection amount by the correction value is greater than a predetermined amount. The predetermined condition is a condition that a fuel injection time from the fuel injection means is longer than a predetermined time,
The internal combustion engine according to claim 2, wherein the mitigation means includes means for shortening the predetermined time when the amount of decrease in the fuel injection amount by the correction value is larger than the predetermined amount. Control device. The controller is
Means for detecting a combustion abnormality of the internal combustion engine;
The control device for an internal combustion engine according to claim 2 or 3, further comprising means for prohibiting correction when the combustion abnormality is detected. The fuel injection means is a first fuel injection means,
The internal combustion engine is provided with second fuel injection means for injecting fuel into the intake passage in addition to the first fuel injection means,
The control device for an internal combustion engine according to claim 1, wherein the correction value is a correction value of a fuel injection amount from the first fuel injection unit. The first fuel injection means is an in-cylinder injector,
6. The control device for an internal combustion engine according to claim 5, wherein the second fuel injection means is an intake passage injection injector.

Images