JP7327086B2 - Control device for internal combustion engine - Google Patents

Description

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

In a diesel engine, which is one of internal combustion engines, various controls such as adjustment of the EGR amount according to the operating state are simultaneously performed in order to improve the purification rate of exhaust gas, for example. , there are various cases in which the actual torque is insufficient with respect to the required torque. In particular, in a vehicle equipped with an internal combustion engine, if the actual torque is insufficient with respect to the required torque, the driver feels the lack of torque and feels uncomfortable, which is not preferable.

In diesel engines, the amount of fuel injection is generally controlled at a lean air-fuel ratio in which the amount of air is excessive relative to the amount of fuel. can get higher output. When adjusting the air-fuel ratio (Air/Fuel: A/F) so that the air-fuel ratio in a lean state approaches the theoretical air-fuel ratio within a specific operating range, the amount of intake air is is reduced to bring the air-fuel ratio closer to the theoretical air-fuel ratio from the lean state, the torque down amount accompanying the reduction in the air amount gradually increases, and the difference between the required torque and the actual torque gradually increases.

For example, in Patent Document 1, in a control device for an internal combustion engine that compressively ignites light oil or a mixed fuel of light oil and other fuel, a cylinder pressure sensor (in-cylinder pressure sensor) is provided in each cylinder, and the accelerator opening and engine rotation The amount of fuel supplied to the cylinder based on the difference between the required torque calculated based on the number and the actual torque (actual instantaneous torque) that is the actual torque detected using the cylinder pressure sensor (in-cylinder pressure sensor). A control device for an internal combustion engine is disclosed that controls the supply timing of the fuel and the amount of EGR.

Japanese Unexamined Patent Application Publication No. 2010-38012

In Patent Document 1, an in-cylinder pressure sensor is arranged on the upper surface of the combustion chamber in each cylinder or on the glow plug to detect the actual torque from the in-cylinder pressure of each cylinder. However, it is difficult to install an in-cylinder pressure sensor in each cylinder, and it is necessary to correct the deterioration of the in-cylinder pressure sensor, which is exposed to high temperature and high pressure in the combustion chamber, and to correct individual differences in the in-cylinder pressure sensor. , which is not very desirable because the control becomes very complicated.

The present invention has been devised in view of this point, and it is possible to detect the difference between the required torque and the actual torque with a simpler and easier configuration without the need to dispose an in-cylinder pressure sensor in each cylinder. An object of the present invention is to provide a control device for an internal combustion engine that can appropriately reduce the noise.

In order to solve the above-described problems, a first invention is a control device for an internal combustion engine that controls a diesel engine by controlling the amount of fuel injected from an injector, wherein an intake path of the diesel engine is provided with fuel for the diesel engine. An intake air amount detecting means for measuring an intake air amount, and a throttle valve as an intake air amount adjusting means capable of adjusting the intake air amount of the diesel engine are provided . Further, a required torque characteristic in which a required torque is set according to the engine speed and the accelerator pedal depression amount, a required base injection amount characteristic in which a required base injection amount according to the required torque is set, or the required torque A computational expression for calculating the required base injection amount from, an engine load obtained based on the fuel injection amount and the engine speed, and a combustion that is a region where a higher output is desired according to the engine speed and a storage means for storing combustion region characteristics in which switching regions are set. The control device controls A/F, which is the air-fuel ratio of the diesel engine, the intake air amount, the throttle valve opening, which is the opening of the throttle valve, the engine speed, and the amount of depression of the accelerator pedal. and a driving state detection unit that detects a driving state including; a request torque that is obtained based on the engine speed, the accelerator pedal depression amount, and the request torque characteristic; and a requested base injection amount calculation unit that calculates the requested base injection amount based on the injection amount characteristic or the arithmetic expression. Then, when both the engine load and the engine speed are within the combustion switching region set in the combustion region characteristics, the engine load or the fuel injection amount and the engine speed or the target A/F set at approximately the stoichiometric air-fuel ratio is obtained, and the actual A/F, which is the detected actual A/F, approaches the target A/F. The intake air amount is gradually reduced by controlling the opening of the throttle valve, which is the intake air amount adjusting means, and the engine load or the engine speed is not within the combustion switching region set as the combustion region characteristic, Alternatively, if the intake air amount is not equal to or less than a preset intake air amount threshold value, the required base injection amount is set to the final injection amount to be injected from the injector, and both the engine load and the engine speed are controlled by the combustion engine. When it is within the combustion switching region set as the region characteristic and the intake air amount is equal to or less than the intake air amount threshold value, the torque generation rate is adjusted according to the air-fuel ratio related amount, which is an amount related to the air-fuel ratio. A torque generation rate related quantity, which is a related quantity, is based on an air-fuel ratio related quantity/torque generation rate related quantity characteristic represented by a curve and the intake air amount/total injection quantity, and the total injection amount. Since the product of the injection amount and the required base injection amount is the required base injection amount, the total injection amount is calculated by increasing the required base injection amount, and the calculated total injection amount is used as the final injection amount to be injected from the injector. is set to prevent torque reduction caused by the gradual reduction of the intake air amount.

Next, a second invention is the control apparatus for an internal combustion engine according to the first invention , wherein the air-fuel ratio related quantity/torque generation rate related quantity characteristic represented by the curve is represented by a quadratic curve. It is a control device for an internal combustion engine.

According to the first invention, the A/F (air-fuel ratio), which is generally controlled in the lean state, is changed from the lean state to the target A/F (for example, the theoretical air-fuel ratio) when the air-fuel ratio control condition is satisfied. close to At that time, the intake air amount is gradually reduced using the intake air amount adjusting means to approach the target A/F from the lean state. Torque down occurs. The occurrence of this torque reduction is predicted, and the final injection amount that prevents the predicted torque reduction is calculated based on the required base injection amount and the intake air amount. Therefore, there is no need to dispose an in-cylinder pressure sensor in each cylinder, and the difference between the required torque and the actual torque can be appropriately reduced with a simpler and easier configuration.

According to the first invention , the appropriate final injection amount can be obtained relatively easily based on the parameters based on the air-fuel ratio related quantity/torque generation rate related quantity characteristic, the required base injection quantity, and the intake air quantity. can be done.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating an example of the configuration of a diesel engine system to which a control device for an internal combustion engine according to the present invention is applied; 4 is a flowchart for explaining an example of a processing procedure [whole processing] of a control device for an internal combustion engine; FIG. 3 is a flowchart for explaining the details of a [combustion switching flag setting process] in the flowchart shown in FIG. 2 ; FIG. 4 is a diagram illustrating an example of a "combustion switching region" in the flowchart shown in FIG. 3; FIG. FIG. 3 is a flowchart for explaining the details of [final injection amount calculation processing] in the flowchart shown in FIG. 2 ; FIG. FIG. 5 is a diagram of an air-fuel ratio/torque generation rate characteristic, which is an example of an air-fuel ratio related amount/torque generation rate related amount characteristic; FIG. 3 is a flowchart for explaining the details of an "intake amount adjustment process" in the flowchart shown in FIG. 2; FIG. 3 is a diagram for explaining an example of operation waveforms when the control device executes the processing of the flowchart shown in FIG. 2; FIG.

Embodiments for carrying out the present invention will be described below with reference to the drawings. First, with reference to FIG. 1, the overall configuration of a diesel engine system 1 having an internal combustion engine control device (hereinafter referred to as a control device 50) according to the present invention will be described. In the description of the present embodiment, an example of a vehicle equipped with a diesel engine as an internal combustion engine will be described.

● [Example of overall configuration of diesel engine system 1 (Fig. 1)]
The overall configuration of a diesel engine system 1 having a control device 50 (control device for an internal combustion engine) will be described in order from the intake side to the exhaust side with reference to FIG. An intake passage is formed by the intake pipes 11A and 11B and the intake manifold 11C, and an exhaust passage is formed by the exhaust manifold 12A and the exhaust pipe 12B.

An intake air amount detection means 21 (for example, an intake air amount sensor) is provided on the inflow side of the intake pipe 11A. The intake air amount detection means 21 outputs a detection signal to the control device 50 according to the flow rate of the intake air taken in by the internal combustion engine 10 (diesel engine). Further, the intake air amount detecting means 21 is provided with an intake air temperature detecting means 28A (for example, a temperature sensor). The intake air temperature detecting means 28A outputs a detection signal to the control device 50 according to the temperature of the intake air passing through the intake air amount detecting means 21 (outside air temperature).

The outflow side of the intake pipe 11A is connected to the inflow side of the throttle device 47 . The outflow side of the throttle device 47 is connected to the inflow side of the intake pipe 11B.

The throttle device 47 drives a throttle valve 47V that adjusts the opening degree of the intake pipe 11B (intake pipe 11A) based on a control signal from the control device 50, and can adjust the amount of intake air. The control device 50 outputs a control signal to the throttle device 47 based on a detection signal from the throttle opening detection means 47S (for example, a throttle opening sensor) and a target throttle opening to open the intake pipe 11B (intake pipe 11A). It is possible to adjust the opening degree of the throttle valve 47V provided in. In the diesel engine system 1, the controller 50 normally controls the throttle valve 47V to be fully open.

The accelerator pedal depression amount detection means 25 is, for example, an accelerator pedal depression angle sensor, and is provided on the accelerator pedal. The control device 50 can detect the amount of depression of the accelerator pedal by the driver based on the detection signal from the accelerator pedal depression amount detection means 25 .

The downstream side of the intake pipe 11B is connected to the inflow side of the intake manifold 11C. The outflow side of the intake manifold 11C is connected to the inflow side of the internal combustion engine 10 .

The internal combustion engine 10 has a plurality of cylinders 45A, each of which is provided with an injector 43A. Fuel is supplied to the injectors 43A via a common rail (not shown), and the injectors 43A are driven by control signals from the control device 50 to inject fuel into the respective cylinders 45A.

The internal combustion engine 10 is provided with a rotation detection means 22, a coolant temperature detection means 28C, and the like. The rotation detection means 22 is, for example, a rotation sensor, and outputs a detection signal corresponding to the rotation speed of the crankshaft of the internal combustion engine 10 (that is, the engine rotation speed) to the control device 50 . The coolant temperature detection means 28C is, for example, a temperature sensor, detects the temperature of the cooling coolant circulating in the internal combustion engine 10, and outputs a detection signal corresponding to the detected temperature to the control device 50.

The inflow side of an exhaust manifold 12A is connected to the exhaust side of the internal combustion engine 10, and the inflow side of an exhaust pipe 12B is connected to the outflow side of the exhaust manifold 12A. The outflow side of the exhaust pipe 12B is connected to the inflow side of the exhaust purification device 60 . Although not shown, the internal combustion engine 10 is a diesel engine, so the exhaust purification device 60 includes an oxidation catalyst, a diesel particulate filter, a selective reduction catalyst, and the like.

The exhaust pipe 12B is provided with an A/F detection means 26 and an exhaust temperature detection means 29A. The A/F detection means 26 is an air-fuel ratio sensor, for example, and outputs a detection signal corresponding to the air-fuel ratio detected from the exhaust gas to the control device 50 . Also, the exhaust temperature detection means 29A is, for example, an exhaust temperature sensor, and outputs a detection signal corresponding to the exhaust temperature to the control device 50 . As will be described later, when the A/F is calculated based on the intake air amount and the final injection amount, the A/F detection means 26 may be omitted.

The control device 50 has a CPU 51, a RAM 52, a storage means 53, an EEPROM 54, a timer 55 and the like. The RAM 52, storage means 53, EEPROM 54, timer 55, etc. are connected to the CPU 51 via various buses. The storage means 53 is, for example, a storage device such as a Flash ROM, and stores programs, data, and the like for executing processes described later. The CPU 51 also has an operating state detection section 51A, a required base injection amount calculation section 51B, a target A/F calculation section 51C, an intake air amount adjustment section 51D, a final injection amount calculation section 51E, and the like, which will be described later.

The control device 50 controls various actuators including the injector 43A and the throttle device 47 described above. The control device 50 is not limited to the detection means and actuators shown in FIG. can detect the operating state of

● [Processing procedure of the control device 50 (FIGS. 2 to 8)]
A processing procedure of the control device 50 (CPU 51) will be described below. In the present embodiment, when the operating state of the internal combustion engine satisfies the air-fuel ratio control conditions including the combustion switching region (see FIG. 4), the lean state air-fuel ratio is set to the target A/F (for example, the theoretical air-fuel ratio). To prevent torque down in advance by correcting the fuel injection amount while throttling the intake air amount so as to reduce the intake air amount. In this embodiment, the A/F (air-fuel ratio) is detected using the A/F detection means 26, or calculated based on the intake air amount and the final injection amount. 2 at predetermined time intervals (for example, intervals of several [ms] to several tens of [ms]) or each time a predetermined crank angle rotates (for example, each time the crankshaft rotates 180 [°]). A process is started and a process is advanced to step S010.

In step S010, control device 50 detects the operating state of internal combustion engine 10, and proceeds to step S015. Specifically, the control device 50 detects the intake air amount based on the detection signal from the intake air amount detection means 21, detects the intake air temperature based on the detection signal from the intake air temperature detection means 28A, and detects the throttle opening. The opening of the throttle valve 47V is detected based on the detection signal from the means 47S. The control device 50 also detects the rotational speed of the internal combustion engine 10 based on the detection signal from the rotation detection means 22, and detects the coolant temperature based on the detection signal from the coolant temperature detection means 28C. The control device 50 also detects the exhaust temperature based on the detection signal from the exhaust temperature detection means 29A. Further, the control device 50 detects the depression amount of the accelerator pedal based on the detection signal from the accelerator pedal depression amount detection means 25 . The control device 50 also detects the amount of fuel (final injection amount) that it is injecting from the injector 43A. Further, when the control device 50 has the A/F detection means 26, the control device 50 detects the actual A/F, which is the actual air-fuel ratio, based on the detection signal from the A/F detection means 26, and detects the A/F. If the control device 50 does not have the means 26, the control device 50 calculates the actual A/F based on the detected intake air amount and the final injection amount calculated by itself. The controller 50 then stores each detected operating state.

The control device 50 (CPU 51) executing the processing of step S010 causes the operating state detection unit 51A (see FIG. 1) for detecting the operating state including the A/F that is the air-fuel ratio of the internal combustion engine 10 (diesel engine). Equivalent.

In step S015, the control device 50 obtains the requested torque based on the detected operating state, obtains the requested base injection amount, which is the fuel injection amount (requested injection amount) corresponding to the obtained requested torque, and proceeds to step S020. proceed. For example, the storage means of the control device 50 stores the required torque characteristic in which the required torque is set according to the engine speed and the amount of depression of the accelerator pedal. The required torque is obtained based on the amount and the stored required torque characteristics. Further, for example, the storage means of the control device 50 stores a required base injection amount characteristic in which a required base injection amount is set according to the required torque, or an arithmetic expression for calculating the required base injection amount from the required torque, etc. The control device 50 obtains and stores the requested base injection amount based on the requested torque and the requested base injection amount characteristic (or an arithmetic expression). Note that the required base injection amount may be obtained based on the engine speed and the amount of depression of the accelerator pedal.

The control device 50 (CPU 51) executing the process of step S015 calculates a required base injection amount that is a fuel injection amount (required injection amount) that satisfies the required torque determined based on the operating state. It corresponds to the calculator 51B (see FIG. 1).

In step S020, control device 50 executes process S100 [combustion switching flag setting process] and advances the process to step S030. Details of the processing S100 [processing for setting combustion switching flag] will be described later.

In step S030, control device 50 executes process S200 [final injection amount calculation process], and advances the process to step S050. Details of the process S200 [process for calculating the final injection amount] will be described later.

In step S050, control device 50 executes process S400 [intake amount adjustment process]. The processing shown in FIG. 2 ends. Details of the process S400 [intake amount adjustment process] will be described later.

● [Process S100: Combustion switching flag setting process (Figs. 3 and 4)]
Next, details of the process S100 [combustion switching flag setting process] will be described with reference to FIGS. 3 and 4. FIG. When executing the process S100 in step S020 shown in FIG. 2, the control device 50 advances the process to step S110 shown in FIG.

In step S110, the control device 50 determines whether or not the detected operating state is within the combustion switching region set in the combustion region characteristics preliminarily stored in the storage means. If it is within (Yes), the process proceeds to step S120, and if the operating state is not within the combustion switching range (No), the process proceeds to step S130B. For example, as shown in FIG. 4, the storage means of the control device 50 stores the engine speed and the load (for example, the load obtained using a map or the like from the fuel injection amount and the engine speed). Combustion region characteristics in which switching regions are set are stored. The control device 50 determines whether or not the current engine speed and load are within the combustion switching region based on the detected engine speed and load and the combustion region characteristics stored in the storage means. . For example, the combustion switching region is a region in which the combustion control state of the diesel engine is switched from a lean state in which the air amount is excessive relative to the fuel amount to a combustion control state close to the stoichiometric air-fuel ratio, and a higher output is desired. area. An appropriate combustion switching region is set through experiments, simulations, or the like, for example. In order to prevent hunting, hysteresis or the like is used to determine whether or not the engine is within the combustion switching region.

If the process proceeds to step S120, the control device 50 determines whether or not another condition is satisfied. If the other condition is satisfied (Yes), the process proceeds to step S130A, and the other condition If not satisfied (No), the process proceeds to step S130B. For example, there are various other conditions such as coolant temperature>80 [° C.], first exhaust temperature≦exhaust temperature≦second exhaust temperature, etc., but “other conditions” are limited to these conditions. not to be

If the process proceeds to step S130A, the air-fuel ratio control condition is satisfied, and the control device 50 sets the combustion switching flag to ON, and proceeds to step S140.

In step S140, control device 50 calculates and stores the target A/F, ends (returns) the process shown in FIG. 3, and advances the process to step S030 shown in FIG. For example, the target A/F may be fixed at approximately the theoretical air-fuel ratio (eg, 14.6), or determined from a map or the like set according to the engine speed and load (or fuel injection amount, etc.). You may do so. For example, if the target A/F is fixed at the stoichiometric air-fuel ratio, the controller 50 sets the target A/F value to the stoichiometric air-fuel ratio value (approximately 14.6) in step S140. Remember.

The control device 50 (CPU 51) executing the processing of step S140, when the operating state satisfies preset air-fuel ratio control conditions (in this case, when both step S110 and step S120 are satisfied), , corresponds to the target A/F calculator 51C (see FIG. 1) for obtaining the target A/F.

If the process proceeds to step S130B, it means that the air-fuel ratio control condition is not satisfied. The process proceeds to step S030 shown in FIG.

● [Process S200: final injection amount calculation process (Figs. 5 and 6)]
Next, details of the process S200 [final injection amount calculation process] will be described with reference to FIGS. 5 and 6. FIG. When executing the process S200 in step S030 shown in FIG. 2, the control device 50 advances the process to step S210 shown in FIG.

In step S210, the control device 50 determines whether or not the detected intake air amount is equal to or less than the intake air amount threshold. is greater than the intake air amount threshold (No), the process proceeds to step S280. For example, the intake air amount threshold may be set to a fixed value in advance, or may be obtained from a map or the like in which the intake air amount threshold corresponding to the required base injection amount is set. When the intake air amount becomes equal to or less than a certain threshold value, the torque reduction becomes conspicuous. Therefore, the torque reduction is prevented by the following processing.

When the process proceeds to step S280, the control device 50 sets the combustion switching history flag to OFF and proceeds the process to step S285.

When the process proceeds to step S285, the controller 50 stores the requested base injection amount as the final injection amount, ends (returns) the process shown in FIG. 5, and proceeds to step S050 shown in FIG.

If the process proceeds to step S215, the control device 50 determines whether or not the combustion switching flag is ON, and if the combustion switching flag is ON (Yes), the process proceeds to step S220, is not ON (No), the process proceeds to step S225.

When the process proceeds to step S220, the control device 50 sets the combustion switching history flag to ON and proceeds to step S245.

When the process proceeds to step S225, the control device 50 determines whether or not the combustion switching history flag is ON, and when the combustion switching history flag is ON (Yes), the process proceeds to step S245, If the switching history flag is not ON (No), the process proceeds to step S285.

The inventors have found through experiments that the torque We found that it is possible to predict the occurrence of down, and found that the necessary amount of fuel should be increased to prevent torque down. Therefore, when "the intake air amount ≤ the intake air amount threshold value", it is predicted that torque reduction will occur, and the final injection amount that prevents this torque reduction is calculated in step S245, which will be described later.

When the process proceeds to step S245, the control device 50 calculates the total injection amount qt using the total injection amount calculation formula shown in (Equation 1) below, stores the total injection amount qt as the final injection amount, and stores the total injection amount qt as the final injection amount. 5 ends (returns), and the process proceeds to step S050 shown in FIG. Here, qt is the total injection amount, q is the requested base injection amount, m is the intake air amount, and a, b, and c are parameters based on the air-fuel ratio related quantity/torque generation rate related quantity characteristics.
qt={(q-bm)±√[(q-bm) ² -4cam ² ]}/2c (Equation 1)

Parameters a, b, and c are air-fuel ratio related quantities (quantities related to torque generation rate) corresponding to air-fuel ratio related quantities (quantities related to air-fuel ratio) of the internal combustion engine 10 (diesel engine). It is a parameter based on the fuel ratio related quantity/torque generation rate related quantity characteristic. For example, the air-fuel ratio/torque generation rate characteristic shown in FIG. 6 will be described as an example of the air-fuel ratio related quantity/torque generation rate related quantity characteristic. The air-fuel ratio/torque generation rate characteristic shown in FIG. 6 is the characteristic of the internal combustion engine 10 with the air-fuel ratio (A/F) on the horizontal axis (x-axis) and the torque generation rate on the vertical axis (y-axis). This characteristic can be expressed by Equation 2, where x is the air-fuel ratio on the horizontal axis and y is the torque generation rate on the vertical axis. Moreover, the following (Formula 3) is materialized.
y(x)=ax ² +bx+c (Formula 2)
q=qt*y(x) (Formula 3)

The following (Equation 4) is obtained from the above (Equation 2) and (Equation 3), and by solving this for qt, the above (Equation 1) can be obtained.
q=qt*y(x)=qt*y(A/F)=qt*y(m/qt)
=qt*[a(m/qt) ² +b(m/qt)+c] (Equation 4)

The A/F under the corrected total injection amount qt is m/qt, and the product of the torque generation rate y(x) [=y(m/qt)] and the total injection amount qt at that time is the control The total injection quantity qt that matches the required base injection quantity q before correction determined by the device is determined by the above (Equation 1). As a result, it is possible to obtain the total injection amount qt that can prevent a decrease in torque with respect to the required base injection amount q that is determined without considering a decrease in torque. In addition, among the double signs (±) in the above (formula 1), the "- (minus)" side, "qt = {(q-bm)-√[(q-bm) ² -4cam ² ]} /2c" is stored as the final injection amount.

The control device 50 (CPU 51) executing the process of step S245 calculates the calculated required base injection amount (q), the measured (detected) intake air amount (m), the air-fuel ratio related quantity/torque generation rate related quantity, It corresponds to the final injection amount calculation section 51E (see FIG. 1) that calculates the total injection amount (qt), which is the final injection amount, based on the parameters (a, b, c) based on the characteristics. In addition, the control device 50 (CPU 51) executing the process of step S245 predicts (in step S210) torque reduction in accordance with the transition of the intake air amount, and the final injection amount to prevent the predicted torque reduction. , which corresponds to the final injection amount calculator 51E (see FIG. 1).

As shown in FIG. 8, the combustion switching history flag is set to "ON" when the combustion switching flag is ON and the intake air amount≦the intake air amount threshold, and is set to "OFF" when the intake air amount>the intake air amount threshold. ”. Therefore, as shown in FIG. 8, the "ON" state is maintained for a while after the combustion switching flag is set to ON --> OFF. As shown in FIG. 8, the maintained period is the period (time T3 to time T4) until the intake air amount exceeds the intake air amount threshold while the actual A/F gradually increases from the target A/F.

● [Process S400: intake air amount adjustment process (Figs. 7 and 8)]
Next, details of the process S400 [intake amount adjustment process] will be described with reference to FIGS. 7 and 8. FIG. When executing the process S400 in step S050 shown in FIG. 2, the control device 50 advances the process to step S410 shown in FIG.

In step S410, the control device 50 determines whether or not the combustion switching flag is ON. If the combustion switching flag is ON (Yes), the process proceeds to step S420A, and if the combustion switching flag is not ON ( No) advances the process to step S420B.

When the process proceeds to step S420A, the control device 50 feeds back the opening of the throttle valve 47V (intake air amount adjusting means) so that the detected actual A/F becomes (approaches) the target A/F. Control is performed to gradually narrow the opening of the throttle valve 47V (time T1 to time T2 in FIG. 8), the process shown in FIG. 7 is terminated (returned), and the process of FIG. 2 is terminated.

When the process proceeds to step S420B, the control device 50 feedback-controls the opening of the throttle valve 47V (target opening=fully open) so that the opening of the throttle valve 47V (intake amount adjusting means) is fully feedback control) to gradually bring the opening of the throttle valve 47V closer to full opening (after time T3 in FIG. 8), and the process shown in FIG. 7 ends.

The control device 50 (CPU 51) executing the processes of steps S410, S420A, and S420B detects the actual detected actual It corresponds to the intake air amount adjusting section 51D (see FIG. 1) which controls the throttle valve 47V (intake air amount adjusting means) so that the actual A/F, which is A/F, approaches the target A/F to gradually throttle the intake air amount. ing.

● [Description of operating waveforms (Fig. 8)]
FIG. 8 shows an example of operation waveforms by the processing of the control device 50 described with reference to FIGS. For example, the amount of depression of the accelerator pedal by the driver is substantially constant, the engine speed is substantially constant, the operating state is within the combustion switching region shown in FIG. 4, and the other conditions of step S120 in FIG. 3 are satisfied. Then, at time T1 shown in FIG. 8, it is assumed that the combustion switching flag becomes OFF --> ON.

In FIG. 8, after the combustion switching flag is turned OFF --> ON at time T1, when the intake air amount≦the intake air amount threshold, the combustion switching history flag is also set OFF --> ON. Also, the target A/F is calculated at time T1. Then, from time T1 to time T2, the opening of the throttle valve is gradually reduced, and the actual A/F value in the lean state approaches the target A/F value. From time T1 to time T2, the final injection amount gradually increases in accordance with the transition of the intake air amount to prevent torque reduction.

Further, in FIG. 8, when the combustion switching flag becomes ON --> OFF at time T3, the throttle valve is gradually moved to the fully open position during time T3 to time T4 using the combustion switching history flag. While returning, the final injection amount is gradually returned to the required base injection amount. In other words, when the state where the air-fuel ratio control condition is satisfied changes to the state where the air-fuel ratio control condition is not satisfied (when the combustion switching flag becomes ON --> OFF), the control device 50 controls the intake air amount adjusting section to While controlling the amount adjusting means (throttle valve) to release the throttling of the intake air amount and gradually return the intake air amount (after time T3), the execution of the final injection amount calculation section is maintained, and the intake air amount reaches the intake air amount threshold value. When it returns (time T4), the maintenance of execution of the final injection amount calculation unit is ended.

In this way, the torque reduction that occurs when the actual A/F is brought closer to the target air-fuel ratio (for example, the theoretical air-fuel ratio) from the lean air-fuel ratio, and the target air-fuel ratio (for example, the theoretical air-fuel ratio) Predicting the occurrence of torque reduction when returning to the lean state, the final injection amount is increased or decreased based on the required base injection amount and the intake air amount using the total injection amount calculation formula (Equation 1). Prevents torque reduction. Therefore, it is not necessary to dispose an in-cylinder pressure sensor in each cylinder, and it is possible to appropriately reduce the difference between the required torque and the actual torque (prevent torque reduction) with a simpler and easier configuration. . Moreover, since the output is corrected according to the actual A/F of the diesel engine, stable output can be obtained.

The control device for an internal combustion engine of the present invention is not limited to the configuration, processing procedure, operation, etc. described in the present embodiment, and various modifications, additions, and deletions are possible without changing the gist of the present invention.

Further, the application of the internal combustion engine control device 50 of the present invention is not limited to the diesel engine system 1 shown in the example of FIG. 1, but can be applied to various diesel engine systems.

In the description of the present embodiment, the combustion switching region is set within the combustion region characteristics (see FIG. 4) corresponding to the engine speed and load, but the invention is not limited to this. For example, the combustion switching region may be set within the region characteristics corresponding to the engine speed and the fuel injection amount.

In the description of the present embodiment, the throttle valve is provided in the intake path as an example of the intake air amount adjusting means for adjusting the intake air amount of the diesel engine, but the intake air amount adjusting means is limited to the throttle valve. isn't it.

Also, the numerical values used in the description of the present embodiment are examples, and the present invention is not limited to these numerical values. Greater than (≧), less than (≦), greater than (>), less than (<), etc. may or may not include an equal sign.

1 diesel engine system 10 internal combustion engine (diesel engine)
11A, 11B intake pipe 11C intake manifold 12A exhaust manifold 12B exhaust pipe 21 intake air amount detection means 22 rotation detection means 25 accelerator pedal depression amount detection means 26 A/F detection means 28A intake air temperature detection means 28C coolant temperature detection means 29A exhaust temperature detection Means 43A Injector 45A Cylinder 47 Throttle Device 47S Throttle Opening Detection Means 47V Throttle Valve (Intake Amount Adjusting Means)
50 control device 51A operating state detection unit 51B required base injection amount calculation unit 51C target A/F calculation unit 51D intake air amount adjustment unit 51E final injection amount calculation unit 53 storage means 60 exhaust purification device a, b, c parameters

Claims (2)

A control device for an internal combustion engine that controls a diesel engine by controlling the amount of fuel injected from an injector,
The intake path of the diesel engine is provided with intake air amount detection means for measuring the intake air amount of the diesel engine, and a throttle valve as intake air amount adjusting means capable of adjusting the intake air amount of the diesel engine. ,
a required torque characteristic in which the required torque is set according to the engine speed and the amount of depression of the accelerator pedal;
a requested base injection amount characteristic in which a requested base injection amount corresponding to the requested torque is set, or an arithmetic expression for calculating the requested base injection amount from the requested torque;
an engine load obtained based on the fuel injection amount and the engine speed, and a combustion region characteristic in which a combustion switching region, which is a region where a higher output is desired, is set according to the engine speed;
has storage means in which is stored
The control device is
The operating state including A/F , which is the air-fuel ratio of the diesel engine, the intake air amount, the throttle valve opening, which is the opening of the throttle valve, the engine speed, and the amount of depression of the accelerator pedal. an operating state detection unit that detects
The required torque is obtained based on the engine speed, the amount of depression of the accelerator pedal, and the required torque characteristic, and the required base injection amount is calculated based on the calculated required torque and the required base injection amount characteristic or the arithmetic expression . a request base injection amount calculation unit that calculates an injection amount;
has
When both the engine load and the engine speed are within the combustion switching region set in the combustion region characteristic,
obtaining a target A / F set according to the engine load or the fuel injection amount and the engine speed, or a target A/F set substantially at the stoichiometric air-fuel ratio ;
gradually reducing the intake air amount by controlling the opening of the throttle valve, which is the intake air amount adjusting means, so that the detected actual A/F, which is the actual A/F, approaches the target A/F ;
When the engine load or the engine speed is not within the combustion switching range set in the combustion range characteristics, or when the intake air amount is not equal to or less than a preset intake air amount threshold,
setting the required base injection amount to the final injection amount to be injected from the injector;
When both the engine load and the engine speed are within the combustion switching region set in the combustion region characteristic, and the intake air amount is equal to or less than the intake air amount threshold,
A torque generation rate-related quantity, which is a quantity related to the torque generation rate, according to the air-fuel ratio-related quantity, which is a quantity related to the air-fuel ratio, is combined with the air-fuel ratio-related quantity/torque generation rate-related quantity characteristic represented by the curve. Since the required base injection amount is the product of the torque generation rate-related amount based on the intake air amount/total injection amount and the total injection amount, the total injection amount increased from the required base injection amount is calculated. calculating and setting the calculated total injection amount as the final injection amount to be injected from the injector, thereby preventing torque reduction caused by gradually reducing the intake air amount;
A control device for an internal combustion engine. The control device for an internal combustion engine according to claim 1,
The air-fuel ratio related quantity/torque generation rate related quantity characteristic represented by the curve is represented by a quadratic curve,
A control device for an internal combustion engine.

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