JP4063198B2 - Control device for internal combustion engine and control method for internal combustion engine - Google Patents

Description

  The present invention relates to control of an internal combustion engine including a port injection valve and an in-cylinder injection valve. More specifically, the present invention relates to an internal combustion engine control apparatus and an internal combustion engine control method capable of suppressing an increase in catalyst bed temperature.

A so-called direct-injection internal combustion engine that injects fuel directly into a cylinder and ignites it directly injects fuel during the compression stroke to form a mixture that is easily ignited by stopping the fuel spray near the spark plug. Separate from the surrounding air layer, that is, stratify. In this state, by operating the direct injection internal combustion engine under the so-called stratified combustion in which the air-fuel mixture in the vicinity of the spark plug is ignited and burned, an ultra lean combustion operation can be realized. Thus, it is possible to improves the fuel consumption, reduces the emissions of CO _2.

  A direct-injection internal combustion engine is operated under a so-called homogeneous combustion in which fuel is directly injected into the cylinder during the intake stroke to diffuse the fuel into the cylinder to form and burn a homogeneous mixture. Can do. In the homogeneous combustion region, the intake air can be further cooled by the heat of vaporization of the fuel directly injected into the cylinder during the intake stroke, so that the charging efficiency can be increased. Thereby, a high output can be obtained in the operation in the homogeneous combustion region of the direct injection internal combustion engine. Due to such advantages, in recent years, direct injection internal combustion engines have attracted attention and have been put into practical use.

  When a direct-injection spark-ignition internal combustion engine is operated with homogeneous combustion, the amount of fuel supplied increases especially at high output, so fuel vaporization is not in time, resulting in poor combustion of homogeneous combustion. There is a case. For this reason, in recent years, a direct injection internal combustion engine that further includes a port injection valve that injects fuel into the intake passage in addition to the in-cylinder injection valve that injects fuel into the cylinder has been proposed. In such a direct injection internal combustion engine, Patent Document 1 discloses a fuel injection device for an internal combustion engine that detects an abnormality of in-cylinder injection from the air-fuel ratio, stops the in-cylinder injection when the abnormality occurs, and switches to port injection. It is disclosed. Thereby, even when the fuel pump for the cylinder injection valve has an abnormality, it is possible to avoid the stop of the internal combustion engine.

Japanese Patent Laid-Open No. 7-103050

  However, the temperature rise of the catalyst bed cannot be detected only by detecting the change in the air-fuel ratio, and the combustion state deteriorates when there is an abnormality in the fuel spray of the in-cylinder injection valve. It may shrink. Therefore, the present invention has been made in view of the above, and controls an internal combustion engine that can suppress overheating of the catalyst bed temperature when operating an internal combustion engine that includes a cylinder injection valve and a port injection valve. It is an object of the present invention to provide an apparatus and a control method for an internal combustion engine.

  In order to achieve the above object, an internal combustion engine control apparatus according to the present invention controls an internal combustion engine including a port injection valve and a cylinder injection valve, and a catalyst for purifying exhaust gas from the internal combustion engine. A catalyst bed temperature determination unit for determining whether or not the catalyst bed temperature exceeds a predetermined reference value based on a parameter relating to the catalyst bed temperature; and when the catalyst bed temperature exceeds the predetermined reference value, the port An injection ratio control unit configured to increase a fuel injection amount of the injection valve more than a fuel injection amount of the port injection valve determined by an operating condition of the internal combustion engine.

  In the internal combustion engine control apparatus according to the present invention, the exhaust gas of the internal combustion engine is purified by a plurality of catalysts in the internal combustion engine control apparatus, and each of the catalysts is provided in the plurality of internal combustion engines. When purifying exhaust gas discharged from one or more cylinders, the catalyst bed temperature determination unit determines whether any one of the catalysts exceeds the predetermined reference value. And when the catalyst bed temperature of any one of the catalysts exceeds the predetermined reference value, the injection ratio control unit determines whether the port injection valve corresponding to the catalyst exceeds the predetermined reference value. The fuel injection amount is increased more than a fuel injection amount of the port injection valve determined by an operating condition of the internal combustion engine.

  Further, the internal combustion engine control apparatus according to the present invention is characterized in that, in the control apparatus for the internal combustion engine, the injection ratio control unit is configured to detect the port injection valve when the catalyst bed temperature exceeds the predetermined reference value. The fuel injection amount is increased more than the fuel injection amount of the port injection valve determined by the operating condition of the internal combustion engine, and the fuel injection of the in-cylinder injection valve is stopped.

  Further, the internal combustion engine control apparatus according to the present invention is characterized in that, in the internal combustion engine control apparatus, the injection ratio control unit injects the internal combustion engine when the catalyst bed temperature exceeds the predetermined reference value. The fuel injection amount of the port injection valve is determined by the operating conditions of the internal combustion engine by increasing the fuel injection ratio of the port injection valve without changing the total amount of fuel to be It is characterized by increasing.

  Further, the internal combustion engine control apparatus according to the present invention is characterized in that, in the internal combustion engine control apparatus, the injection rate control unit increases the fuel injection amount of the port injection valve even though the fuel injection amount is increased. Is greater than the predetermined reference value, the total amount of fuel injected into the internal combustion engine is increased more than the total fuel injection amount determined by operating conditions of the internal combustion engine.

  The following control method for an internal combustion engine according to the present invention is based on a parameter relating to a catalyst bed temperature of a catalyst for purifying exhaust gas of the internal combustion engine when controlling the internal combustion engine including a port injection valve and a cylinder injection valve. The procedure for determining whether or not the catalyst bed temperature exceeds a predetermined reference value, and when the catalyst bed temperature exceeds the predetermined reference value, the fuel injection amount of the port injection valve is determined as the internal combustion engine. And a procedure for increasing the fuel injection amount of the port injection valve determined by the operating conditions.

  Further, the internal combustion engine control method according to the present invention is the internal combustion engine control method, wherein the exhaust gas of the internal combustion engine is purified by a plurality of catalysts, and each of the catalysts is a plurality provided in the internal combustion engine. When purifying exhaust gas discharged from one or more of the cylinders, it is determined whether the catalyst bed temperature of any one of the catalysts exceeds the predetermined reference value, and any one of the catalysts When one catalyst bed temperature exceeds the predetermined reference value, the fuel injection amount of the port injection valve corresponding to the catalyst exceeding the predetermined reference value is determined by the operating condition of the internal combustion engine. The fuel injection amount of the injection valve is increased.

  Further, the internal combustion engine control method according to the present invention is directed to the internal combustion engine control method in which the total amount of fuel injected into the internal combustion engine is changed when the catalyst bed temperature exceeds the predetermined reference value. Without increasing the fuel injection rate of the port injection valve, the fuel injection amount of the port injection valve is increased more than the fuel injection amount of the port injection valve determined by the operating conditions of the internal combustion engine. Features.

  According to the control apparatus and control method for an internal combustion engine according to the present invention, overheating of the catalyst bed temperature can be suppressed when operating the internal combustion engine including the in-cylinder injection valve and the port injection valve.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements of the following embodiments include those that can be easily assumed by those skilled in the art or those that are substantially the same. Further, the present invention can be preferably applied to a reciprocating internal combustion engine, and in particular to an internal combustion engine mounted on a vehicle such as a passenger car, a bus, or a truck.

  The control apparatus and control method for an internal combustion engine according to the first embodiment are characterized by the following points. That is, it is determined whether or not the catalyst bed temperature exceeds a predetermined reference value based on a parameter related to the catalyst bed temperature. When the catalyst bed temperature exceeds the predetermined reference value, the fuel injection amount from the port injection valve is determined. It is characterized by increasing it.

  FIG. 1 is a conceptual diagram illustrating an example in which an internal combustion engine is controlled by a control device for an internal combustion engine according to a first embodiment. The control apparatus for an internal combustion engine according to the present invention is used to control an internal combustion engine provided with a fuel injection valve in each of the intake passage 4 and the cylinder 1s. The internal combustion engine 1 that is a control target of the control device 10 of the internal combustion engine is a reciprocating internal combustion engine using gasoline as fuel. The internal combustion engine 1 includes a port injection valve 2 that injects fuel F into an intake passage 4, and an in-cylinder injection valve 3 that injects fuel F into a cylinder 1s. Then, the fuel F is supplied to the internal combustion engine 1 using at least one of the port injection valve 2 and the in-cylinder injection valve 3.

  The air introduced into the cylinder 1s from the intake passage 4 forms an air-fuel mixture with the fuel injected from the port injection valve 2 or the in-cylinder injection valve 3, and is ignited and burned by the spark plug 6 to become combustion gas. . The combustion pressure of the combustion gas is transmitted to the piston 5 and causes the piston 5 to reciprocate. The combustion gas after driving the piston 5 is guided to the three-way catalyst 9 through the exhaust gas passage 7, where CO, HC and NOx components in the combustion gas are reduced and purified.

  The three-way catalyst 9 is provided with a catalyst bed thermometer 40 for measuring a catalyst bed temperature (hereinafter referred to as catalyst bed temperature) Tc as an example of a detection means for detecting a parameter relating to the catalyst bed temperature. Thereby, the OT (Over Temperature) of the three-way catalyst is detected by monitoring the catalyst bed temperature Tc. The catalyst bed temperature Tc detected by the catalyst bed thermometer 40 is used for control for suppressing the OT of the three-way catalyst 9. In addition, an air-fuel ratio sensor (hereinafter referred to as A / F sensor) 41 for measuring an air-fuel ratio A / F (Air Fuel Ratio) of the internal combustion engine 1 is attached to the exhaust manifold 8. Used for detection and the like. For example, a combustion abnormality of the internal combustion engine 1 can be detected by comparing the output from the A / F sensor 41 with a target air-fuel ratio determined by the operating conditions of the internal combustion engine 1. In this embodiment, the outputs of the catalyst bed thermometer 40 and the A / F sensor 41 are taken into the control device 10 of the internal combustion engine via the ECU 30, but the outputs of the sensors are taken directly into the control device 10 of the internal combustion engine. It may be.

  Here, the parameters relating to the catalyst bed temperature include the exhaust gas temperature of the internal combustion engine 1 and the exhaust gas temperature of the internal combustion engine 1 estimated by the exhaust gas temperature counter in addition to the catalyst bed temperature itself. That is, any parameter that can estimate the catalyst bed temperature Tc without directly measuring the catalyst bed temperature Tc can be used as a parameter related to the catalyst bed temperature. Here, the exhaust gas temperature counter estimates the catalyst bed temperature based on the operating state of the internal combustion engine. In the exhaust gas temperature counter, for example, the catalyst bed temperature Tc is estimated by obtaining the intake air amount of the internal combustion engine 1 from the relationship between the intake air amount of the internal combustion engine 1 and the change amount per unit time of the catalyst bed temperature. There is.

  FIG. 2 is an explanatory diagram illustrating a configuration of the control device for the internal combustion engine according to the first embodiment. The configuration of the control device 10 for the internal combustion engine according to the first embodiment will be described with reference to FIG. The internal combustion engine control method of the present invention can be realized by the internal combustion engine control apparatus 10 of the present invention. The control device 10 for an internal combustion engine includes a processing unit 10p and a storage unit 10m. The processing unit 10p further includes a combustion determination unit 21, a catalyst bed temperature determination unit 22, and an injection ratio determination unit 23. Here, the combustion determination part 21, the catalyst bed temperature determination part 22, and the injection ratio determination part 23 become a part which performs the control method of the internal combustion engine which concerns on this invention.

  The storage unit 10m, the combustion determination unit 21, the catalyst bed temperature determination unit 22, and the injection ratio determination unit 23 are connected via an input / output port (I / O) 29 of the control device 10 for the internal combustion engine. Thereby, the memory | storage part 10m, the combustion determination part 21, the catalyst bed temperature determination part 22, and the injection ratio determination part 23 are comprised so that each can exchange data bidirectionally. Note that data may be transmitted and received in one direction as required in the device configuration.

  The control device 10 of the internal combustion engine and the ECU 30 are connected via an input / output port (I / O) 29 of the control device 10 of the internal combustion engine, and can exchange data with each other. Thereby, the control device 10 of the internal combustion engine acquires the load KL of the internal combustion engine 1 and the engine speed NE and other operation control data of the internal combustion engine which the ECU 30 has, or information from various sensors of the internal combustion engine 1 via the ECU. Or the control of the control device 10 of the internal combustion engine can be interrupted to the operation control routine of the internal combustion engine of the ECU 30. Further, the control device 10 for the internal combustion engine according to the present invention may be incorporated in the ECU 30, and the function of the control device 10 for the internal combustion engine according to the present invention may be realized by using a part of the function of the ECU 30. .

  The storage unit 10m stores a computer program including a processing procedure of the control method of the internal combustion engine according to the present invention, a data map such as a catalyst bed temperature, a fuel injection ratio between the port injection valve 2 and the in-cylinder injection valve 3, and the like. Has been. Here, the storage unit 10m can be configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a flash memory, or a combination thereof. The processing unit 10p can be configured by a memory and a CPU.

  The ECU 30 controls the operation of the internal combustion engine 1 by acquiring outputs from the throttle sensor 42, the air flow sensor 43, and other various sensors, and so on. In this embodiment, the control device 10 for an internal combustion engine according to the present invention is connected to the ECU 30, and the control function function of the internal combustion engine 1 provided in the ECU 30 is realized in realizing the control method for the internal combustion engine according to the present invention. It is configured to be available.

  The computer program may be capable of realizing the processing procedure of the control method for an internal combustion engine according to the present invention by a combination with a computer program already recorded in the processing unit 10p or the ECU 30. The processing unit 10p may realize the functions of the combustion determination unit 21, the catalyst bed temperature determination unit 22, and the injection ratio determination unit 23 using dedicated hardware instead of the computer program. Next, a procedure for realizing the control method of the internal combustion engine according to the first embodiment using the control device 10 for the internal combustion engine will be described. In this description, please refer to FIGS.

  FIG. 3 is a flowchart illustrating a control procedure of the control method of the internal combustion engine according to the first embodiment. This internal combustion engine control method is applied when operating the internal combustion engine 1 using at least the in-cylinder injection valve 3, and is not applied when operating the internal combustion engine 1 using only the port injection valve. In realizing the control method for the internal combustion engine according to the first embodiment, first, the ECU 30 acquires the engine speed NE, the air-fuel ratio A / F, and the like of the internal combustion engine 1, and obtains the load KL of the internal combustion engine (step S101). ). The total fuel injection amount TAU supplied to the internal combustion engine 1 is calculated by the injection ratio determination unit 23 provided in the ECU 30 or the control device 10 of the internal combustion engine based on the load KL, the engine speed NE, and the like.

  Next, the catalyst bed temperature determination unit 22 compares the catalyst bed temperature Tc acquired from the catalyst bed thermometer 40 with a predetermined reference value (step S102). As the predetermined reference value, for example, the catalyst bed heat resistance temperature Tl of the three-way catalyst 9 or the corrected catalyst bed heat resistance temperature Tlc (= (Tl−δT)) obtained by subtracting the safety margin temperature δT from the catalyst bed heat resistance temperature Tl can be used. . In addition, the catalyst bed temperature of the three-way catalyst 9 determined from the operating conditions such as the load KL of the internal combustion engine 1, the engine speed NE, the air-fuel ratio A / F, etc. is mapped in advance and corresponds to the acquired operating conditions of the internal combustion engine 1. It is also possible to use the temperature value of the catalyst bed temperature map. In Example 1, the corrected catalyst bed heat resistant temperature Tlc is used as the predetermined reference value.

  In addition to comparing the catalyst bed temperature Tc with a predetermined reference value, for example, by predicting a time exceeding the predetermined reference value from the rate of temperature increase of the catalyst bed temperature Tc, the fuel injection ratio of the port injection valve 2 is increased. May be. FIG. 4 is an explanatory diagram showing an example of the time change of the catalyst bed temperature. For example, the catalyst bed temperature determination unit 22 calculates the increase rate ΔTc / Δt of the catalyst bed temperature Tc, and exceeds a predetermined reference value (here, the catalyst bed heat resistance temperature Tl) from the current catalyst bed temperature Tc and the increase rate. Predict time to. When the catalyst bed temperature determination unit 22 determines that the time to when the catalyst bed temperature Tc exceeds the predetermined reference value is equal to or less than a predetermined reference time, the injection ratio determination unit 23 performs the fuel injection of the port injection valve 2. Start the control to increase the rate.

  When Tc is lower than Tlc (step S102; No), it can be determined that the catalyst bed temperature Tc is normal and no abnormal temperature rise has occurred. Therefore, the fuel is injected without changing the total fuel injection amount TAU and without changing the injection ratio between the port injection valve 2 and the in-cylinder injection valve 3 (step S108). Hereinafter, this fuel injection mode is referred to as normal injection.

  When Tc is equal to or higher than Tlc (step S102; Yes), it can be determined that the catalyst bed temperature Tc has almost reached the upper limit of the heat resistant temperature. As a cause of the increase in the catalyst bed temperature Tc, for example, a high load operation may be continued for a long time. Also, the catalyst bed temperature rises due to lean air-fuel ratio A / F due to poor fuel spray formation due to malfunction of in-cylinder injection valve 3 or deposit adhesion to in-cylinder injection valve 3, etc. There is also. In either case, if the operation is continued as it is, durability may be shortened due to overheating of the three-way catalyst 9.

  Therefore, the injection ratio determination unit 23 receives the determination result of the catalyst bed temperature determination unit 22 and performs control so as to lower the exhaust gas temperature of the internal combustion engine 1. Specifically, the injection ratio determination unit 23 increases the injection ratio of the port injection valve 2 without changing the total amount of fuel to be injected into the internal combustion engine 1, that is, the total fuel injection amount TAU. The fuel injection amount is adjusted so as to reduce the injection ratio of the valve 3 (step S103). Then, the port injection valve 2 injects fuel at this injection ratio (step S104). As a result, when the catalyst bed temperature Tc becomes lower than Tlc, the routine proceeds to normal injection (step S105; No, step S108).

  Here, the reason why the exhaust gas temperature is lowered by increasing the injection ratio of the port injection valve 2 in order to lower the catalyst bed temperature Tc will be described. FIG. 5 is an explanatory diagram showing the catalyst bed temperature when the injection ratio between the in-cylinder injection valve and the port injection valve is changed. As shown in FIG. 5, the catalyst bed temperature Tc decreases as the injection ratio of the port injection valve 2 is increased. This is because the port injection promotes the mixing of fuel and air and promotes the vaporization of the fuel, so the amount of HC and CO in the exhaust gas can be reduced and the catalyst bed temperature Tc can be lowered. is there. For this reason, if the total fuel injection amount TAU is constant, increasing the injection ratio of the port injection valve 2 and decreasing the injection ratio of the in-cylinder injection valve 3 is effective in reducing the catalyst bed temperature Tc. In this way, the catalyst bed temperature Tc can be lowered while suppressing fuel consumption.

  Further, when the air-fuel ratio A / F becomes lean due to the poor fuel spray formation of the in-cylinder injection valve 3 and the catalyst bed temperature Tc is increased, the injection ratio from the port injection valve 2 is increased. Thus, the catalyst bed temperature Tc can be effectively reduced. Further, since the lean air-fuel ratio A / F can be brought close to the target air-fuel ratio, an increase in HC and CO in the exhaust gas can also be suppressed.

  When the catalyst bed temperature determination unit 22 determines that the catalyst bed temperature Tc is equal to or higher than Tlc even if the injection rate of the port injection valve 2 is increased (step S105; Yes), the injection rate determination unit 23 determines the total fuel injection amount. By increasing TAU, the fuel injection amounts of both the port injection valve 2 and the in-cylinder injection valve 3 are increased (step S106). Then, the port injection valve 2 injects fuel at this injection ratio (step S107). As a result, the combustion state is improved by lowering the air-fuel ratio A / F to enrich the fuel, so that the amount of unburned HC contained in the exhaust gas is reduced. As a result, the exhaust gas temperature is lowered, so that the catalyst bed temperature Tc can be lowered. When the total fuel injection amount TAU is increased, the increase rate of the port injection valve 2 may be made larger than the increase rate of the in-cylinder injection valve 3, or the increase amount of the total fuel injection amount TAU is all increased by the port injection valve. It is good also as 2 injection amount increase. Further, the total fuel injection amount TAU may be increased, the injection amount of the in-cylinder injection valve 3 may be set to 0, and the entire amount may be injected from the port injection valve 2. In this way, the fuel vaporization promoting effect by promoting the mixing of the fuel and air by the port injection becomes larger, so the amount of unburned HC contained in the exhaust gas can be efficiently reduced, and the exhaust gas temperature and the catalyst can be reduced. The bed temperature Tc can be lowered.

  If the catalyst bed temperature Tc becomes lower than Tlc as a result of increasing the total fuel injection amount TAU, the routine proceeds to normal injection (step S101; No). When the catalyst bed temperature Tc is equal to or higher than Tlc, the above steps S103 to S107 are repeated until the catalyst bed temperature Tc becomes lower than Tlc (step S102; Yes). When the rate of decrease of the catalyst bed temperature Tc is slower than a predetermined value, the control device 10 of the internal combustion engine increases the total fuel injection amount TAU and injects at least from the port injection valve 2 (steps S106, S107). ) May be repeated. As a result, the catalyst bed temperature Tc can be lowered more quickly due to the enrichment of the air-fuel ratio A / F, so that it is possible to suppress a decrease in the durability of the three-way catalyst 9 due to a high temperature.

  Next, the procedure for determining the fuel injection ratio according to the first embodiment will be described. FIG. 6 is a flowchart showing a procedure for determining the fuel injection ratio. The injection ratio determination unit 23 provided in the control device 10 for an internal combustion engine according to the first embodiment determines the fuel injection ratio between the port injection valve 2 and the in-cylinder injection valve 3 according to the procedure shown in the flowchart of FIG. First, the injection ratio determination unit 23 acquires the total fuel injection amount TAU under the engine operating conditions calculated by the ECU 30 from the load KL and the engine speed NE of the internal combustion engine 1 (step S201). The injection ratio determination unit 23 may acquire the load KL and the engine speed NE of the internal combustion engine 1 from the ECU 30, and calculate the total fuel injection amount TAU from these.

  Next, the injection ratio determination unit 23 determines whether it is necessary to increase the total fuel injection amount TAU (step S202). The case where the total fuel injection amount TAU is increased is a case where the decrease in the catalyst bed temperature Tc is insufficient only by increasing the injection ratio of the port injection valve 2. When the injection ratio determination unit 23 determines that the increase in the total fuel injection amount TAU is necessary (step S202; Yes), the injection ratio determination unit 23 adds the injection amount increase α to the TAU determined first. The calculated value is replaced with the total fuel injection amount TAU (step S203). When it is not necessary to increase the total fuel injection amount TAU (step S202; No), the injection ratio determination unit 23 sets the first determined TAU as the total fuel injection amount TAU (step S204). Next, it is determined whether or not the combustion determination unit 21 is in the homogeneous combustion region (step S205). If the combustion determination unit 21 is in the homogeneous combustion region (step S205; Yes), the injection ratio determination unit 23 determines that the port injection valve 2 and the in-cylinder The injection ratio with the injection valve 3 is determined (step S206).

  FIG. 7 is an explanatory diagram showing an example of an injection ratio map showing the injection ratio of the port injection valve with respect to the load of the internal combustion engine. The injection ratio k of the port injection valve 2 (hereinafter referred to as injection ratio k) is determined as shown in the injection ratio map 50 of FIG. 7, and is set so that the injection ratio of the port injection valve 2 increases as the load KL increases. . The injection ratio determination unit 23 acquires the load KL of the internal combustion engine 1 from the ECU 30, gives the load KL to the injection ratio map 50 stored in the storage unit 10 m of the control device 10 for the internal combustion engine, and calculates the required injection ratio k. Obtained and determined as the injection ratio of the port injection valve 2.

  Next, the injection ratio determination unit 23 determines whether or not an increase in the injection ratio of the port injection valve 2 is necessary (step S207). The case where the injection ratio of the port injection valve 2 is increased refers to a case where the catalyst bed temperature Tc exceeds a predetermined reference value when the internal combustion engine 1 is operated using at least the in-cylinder injection valve 3. When it is necessary to increase the injection ratio of the port injection valve 2 (step S207; Yes), the injection ratio determination unit 23 calculates a value obtained by adding the injection ratio increase β to the initially determined injection ratio k. (Step S208). When it is not necessary to increase the injection ratio of the port injection valve 2 (step S207; No), the injection ratio determination unit 23 sets the first determined injection ratio k as the injection ratio k (step S209).

When the injection ratio k used for the control is determined, the injection ratio determination unit 23 next calculates the fuel injection amount Qp of the port injection valve 2 and the fuel injection amount Qd of the port injection valve 2 using the injection ratio k. (Step S210).
Qp = k × TAU
Qd = (1-k) × TAU
The port injection valve 2 and the port injection valve 2 inject fuel with this injection amount.

  When it is determined that the combustion determination unit 21 is not in the homogeneous combustion region (step S205; No), the injection ratio determination unit 23 determines whether or not an increase in the injection ratio of the port injection valve 2 is necessary (step S211). ). Since it is a stratified combustion region that it is not a homogeneous combustion region, the internal combustion engine 1 is operated by injection only by the in-cylinder injection valve 3 in principle. First, when it is not necessary to increase the injection ratio of the port injection valve 2 (step S211; No), the internal combustion engine 1 is operated by continuously injecting fuel only from the in-cylinder injection valve 3. Therefore, the injection ratio determination unit 23 sets the fuel injection amount Qp of the port injection valve 2 to 0, and sets the fuel injection amount Qd of the port injection valve 2 to the total fuel injection amount TAU (step S212). When it is necessary to increase the injection ratio of the port injection valve 2 (step S211; Yes), the injection ratio determination unit 23 increases the injection ratio of the port injection valve 2. In the first embodiment, the fuel injection amount Qp of the port injection valve 2 is set to the total fuel injection amount TAU, and the fuel injection amount Qd of the in-cylinder injection valve 3 is set to 0 (step S213).

  Thus, even in the stratified combustion region, by using the port injection valve 2, the fuel vaporization promoting effect by promoting the mixing of the fuel and the air by the port injection makes it possible to efficiently remove the unburned HC contained in the exhaust gas. By reducing the amount, the exhaust gas temperature and the catalyst bed temperature Tc can be lowered. In the stratified combustion region, the injection ratio of the port injection valve 2 may be changed according to the load KL of the internal combustion engine 1, the engine speed NE, and other operating conditions. As an example of such control, for example, there is one that increases the injection ratio of the port injection valve 2 as the load KL of the internal combustion engine 1 increases. Here, when the injection ratio of the port injection valve 2 is increased, as described above, the catalyst bed temperature Tc exceeds a predetermined reference value.

  As described above, in the first embodiment, the ratio of the port injection is first increased without changing the entire fuel injection amount according to the catalyst bed temperature, so that the catalyst temperature can be efficiently reduced. As a result, the fuel consumption of the internal combustion engine can be suppressed, and the catalyst bed temperature can be lowered with little influence on the entire air-fuel ratio change. Moreover, since the ratio of port injection is controlled by the catalyst bed temperature, the catalyst bed temperature can be accurately reflected to improve the control accuracy, and the overheating of the three-way catalyst can be more reliably suppressed.

  Furthermore, when there is a defect in the spray formation of the in-cylinder injection valve, the air-fuel ratio is made lean by the port injection valve, so that the air-fuel ratio can be maintained at the target value and overheating of the catalyst can be suppressed. Here, the contents disclosed in the first embodiment can be applied to the following embodiments and modifications. In addition, the present invention of Example 1 can be applied regardless of the homogeneous combustion region and the stratified combustion region, but from the viewpoint that the catalyst bed temperature can be efficiently reduced, the catalyst bed temperature is particularly likely to rise. Suitable for high load and high power operation (homogeneous combustion region) (the same applies hereinafter).

(Modification)
FIG. 8 is an explanatory diagram illustrating a configuration of a control device for an internal combustion engine according to a modification of the first embodiment. FIG. 9 is a flowchart illustrating the procedure of the control method for the internal combustion engine according to the modification of the first embodiment. The internal combustion engine control method has substantially the same configuration as the internal combustion engine control method according to the first embodiment of the present invention, except that fuel is injected by both the port injection valve and the in-cylinder injection valve. Before determining the catalyst bed temperature Tc, the actual air-fuel ratio AF1 during operation of the internal combustion engine is compared with the target air-fuel ratio AFa, so that the actual air-fuel ratio AF1 during operation approaches the target air-fuel ratio AFa. The difference is that the fuel injection amount of the valve or the in-cylinder injection valve is increased. The description of the same configuration as the first embodiment is omitted, and the same reference numeral is given to the same configuration. In the following description, please refer to FIG. 1 as necessary.

  First, the ECU 30 acquires the engine speed NE, the air-fuel ratio A / F, and the like of the internal combustion engine 1, and obtains the load KL and the like of the internal combustion engine (step S301). Next, the air-fuel ratio determination unit 24 included in the control device 10 ′ of the internal combustion engine acquires the actual air-fuel ratio AF1 during operation of the internal combustion engine 1 from the A / F sensor 41 and compares it with the target air-fuel ratio AFa (step) S302). When the actual air-fuel ratio AF1 is larger than the target air-fuel ratio AFa (step S302; Yes), the internal combustion engine 1 is operated with the air-fuel mixture lean. As a cause of this, it is conceivable that an abnormality such as a poor fuel spray formation has occurred in at least one of the port injection valve 2 or the in-cylinder injection valve 3 to cause combustion abnormality or combustion instability. As a result, it can be estimated that the actual air-fuel ratio AF1 is larger than the target air-fuel ratio AFa.

  When the actual air-fuel ratio AF1 is larger than the target air-fuel ratio AFa (step S302; Yes), it is assumed that a fuel spray formation defect has occurred in the in-cylinder injection valve 3. The in-cylinder injection valve 3 is supplied with high-pressure fuel as compared with the port injection valve 2 and thus may cause a malfunction. Further, since the fuel is injected into the cylinder 1s, carbon or the like is likely to accumulate. Because. When the actual air-fuel ratio AF1 is larger than the target air-fuel ratio AFa, first, the fuel is injected by increasing the fuel injection amount Qp of the port injection valve 2. For this reason, the injection ratio control unit 23 sets the value Qp + γ obtained by adding the increase amount γ to the fuel injection amount Qp injected by the port injection valve 2 out of the total fuel injection amount TAU as the corrected fuel injection amount Qp1 of the port injection valve 2. (Step S303). Then, the port injection valve 2 injects fuel with this fuel injection amount (step S304).

  When the fuel injection amount of the port injection valve 2 is increased and fuel is injected, the air-fuel ratio determination unit 24 acquires the actual air-fuel ratio AF1 and compares it with the target air-fuel ratio AFa (step S305). At this time, if the actual air-fuel ratio AF1 is equal to or lower than the target air-fuel ratio AFa (step S305; No), the catalyst bed temperature Tc is compared with a predetermined reference value (step S308). In this modification, a catalyst map temperature Tcm obtained from a catalyst bed temperature map is used as the predetermined reference value.

  Here, when the fuel injection amount of the port injection valve 2 is increased to inject fuel and the actual air-fuel ratio AF1 becomes equal to or less than the target air-fuel ratio AFa, it is estimated that there is some abnormality in the in-cylinder injection valve 3. it can. It is preferable to store this record in the memory of the ECU 30 because it is easy to identify the cause of the malfunction at the time of inspection and repair. Further, a warning may be issued when the number of times of increasing the fuel injection amount of the port injection valve 2 exceeds a predetermined number, and the driver may be encouraged to check and repair.

  If the actual air-fuel ratio AF1 is larger than the target air-fuel ratio AFa even though the fuel injection amount of the port injector 2 is increased (step S305; Yes), fuel spray formation abnormality also occurs in the port injector 2 Therefore, the fuel injection amount Qd of the in-cylinder injection valve 3 is increased. For this reason, the injection ratio control unit 23 adds the amount of increase δ to the fuel injection amount Qd injected by the in-cylinder injection valve 3 out of the total fuel injection amount TAU (Qd + δ) is the corrected fuel injection amount of the port injection valve 2. Correction is made so as to be Qd1 (step S306). The in-cylinder injection valve 3 injects fuel with this fuel injection amount (step S307). In addition, when the abnormality of the port injection valve is estimated, the record can be stored in the memory of the ECU 30 as in the case of the in-cylinder injection valve 3.

  FIG. 10 is a flowchart showing a procedure for determining the fuel injection amount. The injection ratio determination unit 23 included in the control device 10 for an internal combustion engine according to the present invention of this modification determines the fuel injection amounts of the port injection valve 2 and the in-cylinder injection valve 3 according to the procedure shown in the flowchart of FIG. First, the injection ratio determination unit 23 determines the injection ratio k between the port injection valve 2 and the in-cylinder injection valve 3 from the operating conditions of the internal combustion engine 1, and the fuel injection amount Qp of the port injection valve 2 and the in-cylinder injection valve. 3 is determined (step S401).

  When the fuel injection amount Qp of the port injection valve 2 is increased, the injection ratio determination unit 23 adds a predetermined increase amount γ to the fuel injection amount Qp, and (Qp + γ) is corrected fuel injection of the port injection valve 2. The amount is set as Qp1 (step S402). Next, when the fuel injection amount Qd of the in-cylinder injection valve 3 is to be increased, the injection ratio determination unit 23 adds the predetermined increase amount δ to the fuel injection amount Qd and sets (Qd + δ) to the in-cylinder injection valve 3. The corrected fuel injection amount Qd1 is set (step S403). Then, subsequent control is executed based on the corrected fuel injection amounts Qp1 and Qd1.

  Next, it is compared whether or not the actual air-fuel ratio AF1 is equal to or less than the target air-fuel ratio AFa (step S302). If the actual air-fuel ratio AF1 is larger than the target air-fuel ratio AFa (step S302; Yes), the actual air-fuel ratio AF1 is compared. Steps S303 to S307 are repeated until the fuel ratio AF1 becomes equal to or less than the target air-fuel ratio AFa, and the increase in Qp or Qd is continued. When the actual air-fuel ratio AF1 is equal to or lower than the target air-fuel ratio AFa (step S302; No), the catalyst bed temperature Tc is compared with a predetermined reference value (here, the catalyst map temperature Tcm obtained from the catalyst bed temperature map). (Step S308).

  When the catalyst bed temperature Tc is equal to or higher than the catalyst map temperature Tcm as a result of comparing the catalyst bed temperature Tc with the catalyst map temperature Tcm that is a predetermined reference value (step S308; Yes), the port injection valve 2 or the in-cylinder injection valve. This is a case where the catalyst bed temperature Tc is increased even though the actual air-fuel ratio AF1 of the internal combustion engine 1 becomes normal by increasing the fuel injection amount 3. If the internal combustion engine 1 is operated as it is, the durability of the three-way catalyst 9 is lowered due to the temperature rise of the three-way catalyst 9, so that the injection ratio control unit 23 keeps the total fuel injection amount TAU constant and the port injection valve 2 The injection ratio is increased (step S309), and the injection ratio of the in-cylinder injection valve 3 is decreased. Then, the port injection valve 2 injects fuel at this injection ratio (step S310). The reason why the injection ratio of the port injection valve 2 is increased is that, as described above, the use of port injection is more effective for lowering the catalyst bed temperature Tc.

  As a result, when the catalyst bed temperature Tc becomes lower than Tcm, the routine proceeds to normal injection (step S311; No). Thereby, the catalyst bed temperature Tc can be lowered while suppressing fuel consumption. Further, since the lean air-fuel ratio A / F can be brought close to the target air-fuel ratio, an increase in HC and CO in the exhaust gas can also be suppressed.

  When the catalyst bed temperature determination unit 22 determines that the catalyst bed temperature Tc is equal to or higher than Tcm even if the injection rate of the port injection valve 2 is increased (step S311; Yes), the injection rate determination unit 23 determines the total fuel injection amount. Increase TAU. As a result, the fuel injection amounts of both the port injection valve 2 and the in-cylinder injection valve 3 are increased (step S312). Then, the port injection valve 2 injects fuel at this injection ratio (step S313). Thereby, the combustion state can be improved by lowering the air-fuel ratio A / F and enriching it, and the amount of unburned HC in the exhaust gas can be reduced. As a result, the exhaust gas temperature can be lowered and the catalyst bed temperature Tc can be lowered.

  As a result of increasing the total fuel injection amount TAU, when the catalyst bed temperature Tc becomes lower than Tcm (step S308; No), the routine proceeds to normal injection (step S314). When the catalyst bed temperature Tc is higher than Tcm, the above steps S309 to S313 are repeated until the catalyst bed temperature Tc becomes Tcm or less (step S308; Yes). Thereby, the catalyst bed temperature Tc can be set to Tcm or less, and the durability fall of the three-way catalyst 9 can be suppressed.

  Example 2 includes a port injection valve and an in-cylinder injection valve, and in an internal combustion engine including a plurality of three-way catalysts, a cylinder in charge of the three-way catalyst whose catalyst bed temperature has increased (provides fuel to the intake passage). It is characterized in that the catalyst bed temperature of the three-way catalyst is lowered by increasing the injection ratio of the port injection valve.

FIG. 11 is a conceptual diagram illustrating an example of an internal combustion engine controlled by the control method for an internal combustion engine according to the second embodiment. As shown in FIG. 11, the internal combustion engine 1 a is an in-line four cylinder, and includes a first three-way catalyst 9 ₁ and a second three-way catalyst 9 ₂ . The exhaust gases from the cylinders 1as ₁ and 1as ₄ are guided to the first three-way catalyst 9 ₁ through the first and second exhaust manifolds (hereinafter referred to as exhaust manifolds) 8 ₁ and 8 ₄ and purified there. Exhaust gases from the cylinders 1as ₂ and 1as ₃ pass through the second and third exhaust manifolds 8 ₂ and 8 ₃ to the second three-way catalyst 9 ₂ where they are purified.

The catalyst bed temperatures of the first and second three-way catalysts are measured by a first catalyst bed thermometer 40 ₁ and a second catalyst bed thermometer 40 ₂ , respectively. The measured first and second catalyst bed temperatures Tc ₁ and Tc ₂ are used in the method for controlling an internal combustion engine according to the second embodiment of the present invention. As described above, the internal combustion engine 1a includes two three-way catalysts, but the second embodiment can be applied to an internal combustion engine including three or more three-way catalysts. The second embodiment can also be applied to an internal combustion engine having two or more cylinders.

FIG. 12 is a flowchart illustrating a procedure of the control method of the internal combustion engine according to the second embodiment. This internal combustion engine control method is applied when the internal combustion engine 1a is operated using at least the first to fourth in-cylinder injection valves 3 _{1 to} 3 ₄ , and the first to fourth port injection valves 2 ₁ to 2. _This is not applicable when the internal combustion engine 1a is operated using only ₄ . Further, the control method of the internal combustion engine according to the second embodiment can be realized by the control device 10 for the internal combustion engine according to the first embodiment. For this reason, refer to FIG. 2 as necessary for the description of the configuration of the control device 10 for the internal combustion engine.

  In realizing the control method for the internal combustion engine according to the second embodiment, first, the ECU 30 acquires the engine speed NE, the air-fuel ratio A / F, and the like of the internal combustion engine 1, and obtains the load KL and the like of the internal combustion engine (step S501). ). The total fuel injection amount TAU supplied to the internal combustion engine 1 is calculated by the injection ratio determination unit 23 provided in the ECU 30 or the control device 10 of the internal combustion engine based on the load KL, the engine speed NE, and the like.

In the second embodiment, the corrected catalyst bed heat resistant temperature Tlc (= Tl−δT) is used as a predetermined reference value for comparing the catalyst bed temperature. Next, the catalyst bed temperature determination unit 22 includes a first catalyst bed temperature Tc ₁ of the first three-way catalyst 9 ₁ obtained from the first catalyst bed temperature gauge 40 _1, obtained from the second catalyst bed thermometer 40 ₂ the second three-way catalyst 9 compares ₂ of the second catalyst bed temperature Tc ₂ (step S502). When the second catalyst bed temperature Tc ₂ is higher than the first catalyst bed temperature Tc ₁ (step S502; Yes), the catalyst bed temperature determination unit 22 determines that the second catalyst bed temperature Tc ₂ is the corrected catalyst bed heat resistance. It is determined whether or not the temperature is equal to or higher than Tlc (step S503). The first three-way catalyst 9 ₁ In the second three way catalyst 9 _2, one of the catalyst bed temperature either by combustion temperature variation of each cylinder is sometimes easily increased. In such a case, even if the catalyst bed temperature comparison procedure (step S502) between the three-way catalysts is changed so that the temperature reduction control can be executed first for the three-way catalyst that is likely to increase in temperature. Good.

When Tc ₂ is lower than Tlc (step S503; No), it can be determined that the second catalyst bed temperature Tc ₂ is normal and no abnormal temperature rise has occurred. For this reason, it transfers to normal injection (step S508). When Tc ₂ is equal to or higher than Tlc (step S503; Yes), it can be determined that the second catalyst bed temperature Tc ₂ has almost reached the upper limit of the heat-resistant temperature. Thus, continuing the operation as it is, there is a fear of lowering the durability due to overheating of the second three-way catalyst 9 _2. Therefore, the fuel injection ratio determining unit 23 by the determination result of the catalyst bed temperature determination unit 22, and controls to decrease the second catalyst bed temperature Tc ₂ of the second three-way catalyst 9 _2.

Specifically, the injection ratio determination unit 23 does not change the total fuel injection amount TAU, and the second port injection valve 2 ₂ , the third port injection valve 2 ₃ (the port corresponding to the second three-way catalyst 9 _2). Increase the injection rate of the injection valve. Here, the 2nd port injection valve 2 ₂ and the 3rd port injection valve 2 ₃ are the 2nd and 3rd intake passages 4 of 2nd cylinder 1as ₂ and 3rd cylinder 1as _{3 which} 2nd three way catalyst 9 ₂ takes charge of. ₂ and 4 ₃ are provided respectively. The second cylinder injection valve 3 _2, determines the amount of fuel injection to reduce the fuel injection ratio of (for in-cylinder injection valve corresponding to the second three-way catalyst 9 ₂₎ 3-cylinder injection valve 3 ₃ ( Step S504). The second and third port injection valves 2 ₂ and 2 ₃ and the second and third in-cylinder injection valves 3 ₂ and 3 ₃ inject fuel at this injection ratio (step S505). As a result, when the second catalyst bed temperature Tc ₂ becomes equal to or lower than Tlc, the routine proceeds to normal injection (step S506; No, step S508).

When the catalyst bed temperature determining unit 22 when also increasing the fuel injection ratio of the second port injection valve 2 ₂ like the second catalyst bed temperature Tc ₂ is not less than Tlc is determined (step S506; Yes), the fuel injection ratio determining section 23 increases the total fuel injection amount TAU to increase the fuel injection amounts of the second and third port injection valves 2 ₂ , 2 ₃ , and the second and third in-cylinder injection valves 3 ₂ , 3 ₃ . (Step S507). The second and third port injection valves 2 ₂ and 2 ₃ and the second and third in-cylinder injection valves 3 ₂ and 3 ₃ inject fuel at this injection ratio (step S508). As a result, the air-fuel ratio A / F can be lowered and enriched, so that the combustion state can be improved. As a result, the amount of unburned HC contained in the exhaust gas is reduced and the exhaust gas temperature is lowered, so that the second catalyst bed temperature Tc ₂ can be lowered.

As a result of increasing the total fuel injection amount TAU, when the second catalyst bed temperature Tc ₂ becomes lower than Tlc, the second and third cylinders 1as ₂ and 1as ₃ shift to normal injection (step S502; No, step S508), the process proceeds to the first monitoring catalyst bed temperature Tc ₁ of the first three-way catalyst 9 ₁ (step S509). On the other hand, the second catalyst bed temperature Tc ₂ may be more Tlc, second catalyst bed temperature Tc ₂ is repeated step S503~ step S507 until the lower Tlc (step S503; Yes). When the rate of decrease in the second catalyst bed temperature Tc ₂ is slower than a predetermined value, the control device 10 for the internal combustion engine increases the total fuel injection amount TAU and injects at least from the port injection valve 2 (step) It may be controlled to repeat S506 and S507). Thus, it is possible to lower earlier the air-fuel ratio A / F second catalyst bed temperature Tc ₂ by enrichment, it is possible to suppress the deterioration in durability of the second three-way catalyst 9 ₂ due to high temperature.

Next, in the step S502, if the direction of the first catalyst bed temperature Tc ₁ is determined to be higher than the second catalyst bed temperature Tc ₂ (step S502; No), the second three-way catalyst 9 ₂ normally It can be determined that it is functioning. Therefore, for the second cylinder 1as ₂ and the third cylinder 1as ₃ corresponding to the second three-way catalyst 9 _2, operating in the normal injection (step S508). Next, the catalyst bed temperature determination unit 22 determines whether or not the first catalyst bed temperature Tc ₁ is equal to or higher than the corrected catalyst bed heat resistant temperature Tlc (step S509). The first catalyst bed temperature Tc ₁ is corrected catalyst heat resistance temperature when it is determined that the Tlc or more; in order to reduce the (step S509 Yes), the catalyst bed temperature Tc ₁ of the first three-way catalyst 9 _1, the fuel injection ratio The determination unit 23 executes control of the fuel injection amount according to the present invention. Here, the cylinders of the internal combustion engine 1a to the catalyst 9 ₁ first three-way charge is first cylinder 1as _1, a fourth cylinder 1as _4. Therefore, the injection valve to be controlled injection rate determination unit 23, a fourth port which first port injection valve 2 ₁ first cylinder 1as ₁ comprises, first direct injection valve 3 _1, the fourth cylinder 1as ₄ comprising These are the injection valve 2 ₄ and the fourth in-cylinder injection valve 3 ₄ .

Step S509 the fuel injection ratio determining unit 23 in the following runs, the procedure of lowering the first catalyst bed temperature Tc ₁ (step S510~ step S513) will be omitted because it is similar to step S504~ step S507. When the first catalyst bed temperature Tc ₁ is lower than the corrected catalyst bed heat resistant temperature Tlc (step S509; No), fuel is injected by normal injection (step S514), and the process returns to step S501 to return to the first and second catalyst beds. Monitoring of the temperatures Tc ₁ and Tc ₂ is continued.

Conventionally, when one of the first or second three-way catalysts 9 ₁ and 9 ₂ is heated, the total fuel injection amount supplied to all the cylinders 1as _{1 to} 1as _{4 of} the internal combustion engine 1 is increased. . For this reason, fuel consumption has increased. However, according to the control device and the control method for an internal combustion engine according to the second embodiment, only for the cylinder in charge of the three-way catalyst, the fuel injection ratio of the port injection valve and the in-cylinder injection valve corresponding to the cylinder, or Adjust the total fuel injection amount. As a result, the catalyst bed temperature can be reduced to suppress a decrease in the durability of the three-way catalyst due to overheating, and the fuel consumption of the internal combustion engine can be reduced.

  As described above, the control apparatus and control method for an internal combustion engine according to the present invention is suitable for an internal combustion engine including a port injection valve and a cylinder injection valve, and is suitable for efficiently reducing the temperature of a heated catalyst. Yes.

1 is a conceptual diagram illustrating an example when an internal combustion engine is controlled by a control device for an internal combustion engine according to Embodiment 1. FIG. 1 is an explanatory diagram illustrating a configuration of a control device for an internal combustion engine according to Embodiment 1. FIG. 2 is a flowchart illustrating a control procedure of the internal combustion engine control method according to the first embodiment. It is explanatory drawing which shows an example of the time change of a catalyst bed temperature. It is explanatory drawing which shows the catalyst bed temperature at the time of changing the injection ratio of a cylinder injection valve and a port injection valve. It is a flowchart which shows the determination procedure of a fuel injection ratio. It is explanatory drawing which shows an example of the injection ratio map which shows the injection ratio of the port injection valve with respect to the load of an internal combustion engine. FIG. 6 is an explanatory diagram illustrating a configuration of a control device for an internal combustion engine according to a modification of the first embodiment. 6 is a flowchart illustrating a procedure of an internal combustion engine control method according to a modification of the first embodiment. It is a flowchart which shows the determination procedure of fuel injection quantity. FIG. 6 is a conceptual diagram illustrating an example of an internal combustion engine controlled by an internal combustion engine control method according to a second embodiment. 7 is a flowchart illustrating a procedure of a control method for an internal combustion engine according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1a Internal combustion engine 1s Cylinder 2 Port injection valve 3 In-cylinder injection valve 4 Intake passage 5 Piston 7 Exhaust gas passage 8 Exhaust manifold 9 Three-way catalyst 10, 10 'Control device of internal combustion engine 10m, 10m' Memory | storage part 10p Processing part 21 Combustion determination unit 22 Catalyst bed temperature determination unit 23 Injection ratio control unit 24 Air-fuel ratio determination unit 40 Catalyst bed thermometer

Claims (5)

Control an internal combustion engine having a port injection valve and a cylinder injection valve,
A catalyst bed temperature determination unit that determines whether or not the catalyst bed temperature exceeds a predetermined reference value based on a parameter related to a catalyst bed temperature of a catalyst that purifies the exhaust gas of the internal combustion engine;
When the catalyst bed temperature exceeds the predetermined reference value, the fuel injection amount of the port injection valve is determined by the operating condition of the internal combustion engine without changing the total amount of fuel injected into the internal combustion engine. When the catalyst bed temperature exceeds the predetermined reference value even though the fuel injection amount of the injection valve is increased and the fuel injection amount of the port injection valve is increased, the internal combustion engine An injection ratio control unit that increases the total amount of fuel injected into the total fuel injection amount determined by operating conditions of the internal combustion engine ;
A control apparatus for an internal combustion engine, comprising: When the exhaust gas of the internal combustion engine is purified by a plurality of catalysts, and each of the catalysts purifies exhaust gas discharged from one or more cylinders among the plurality of cylinders included in the internal combustion engine,
The catalyst bed temperature determination unit determines whether or not the catalyst bed temperature of any one of the catalysts exceeds the predetermined reference value,
When the catalyst bed temperature of any one of the catalysts exceeds the predetermined reference value, the injection ratio control unit is configured to perform a fuel injection amount of the port injection valve corresponding to the catalyst that exceeds the predetermined reference value. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel injection amount of the port injection valve determined by operating conditions of the internal combustion engine is increased. The injection ratio control unit
When the catalyst bed temperature exceeds the predetermined reference value, the fuel injection amount of the port injection valve is increased more than the fuel injection amount of the port injection valve determined by operating conditions of the internal combustion engine, and 3. The control apparatus for an internal combustion engine according to claim 1, wherein the fuel injection of the in-cylinder injection valve is stopped. In controlling an internal combustion engine provided with a port injection valve and a cylinder injection valve,
A procedure for determining whether or not the catalyst bed temperature exceeds a predetermined reference value based on a parameter relating to the catalyst bed temperature of a catalyst that purifies exhaust gas of the internal combustion engine;
When the catalyst bed temperature exceeds the predetermined reference value, the fuel injection amount of the port injection valve is determined by the operating condition of the internal combustion engine without changing the total amount of fuel injected into the internal combustion engine. A procedure for increasing the fuel injection amount of the injection valve;
When the catalyst bed temperature exceeds the predetermined reference value even though the fuel injection amount of the port injection valve is increased, the total amount of fuel injected into the internal combustion engine is determined as the operation of the internal combustion engine. A procedure for increasing the total fuel injection amount determined by the conditions;
A control method for an internal combustion engine comprising: When the exhaust gas of the internal combustion engine is purified by a plurality of catalysts, and each of the catalysts purifies exhaust gas discharged from one or more cylinders of the plurality of cylinders included in the internal combustion engine,
Determining whether the catalyst bed temperature of any one of the catalysts exceeds the predetermined reference value;
When the catalyst bed temperature of any one of the catalysts exceeds the predetermined reference value, the fuel injection amount of the port injection valve corresponding to the catalyst exceeding the predetermined reference value is determined as the operation of the internal combustion engine. The control method for an internal combustion engine according to claim 4 , wherein the fuel injection amount of the port injection valve determined by conditions is increased.

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