JP6012646B2 - Fuel injection amount control device for internal combustion engine - Google Patents

Description

  The present invention relates to a fuel injection amount control device for an internal combustion engine, and more particularly to an internal combustion engine that detects a transient state such as an acceleration / deceleration state of the internal combustion engine and sets a fuel injection amount to be supplied to the internal combustion engine according to the detected transient state. The present invention relates to a fuel injection amount control device.

  When controlling the internal combustion engine, it may be necessary to detect the acceleration / deceleration state of the internal combustion engine. For example, when an EPI (electronic fuel injection device) is used as a device for supplying fuel to an internal combustion engine, it is detected whether the internal combustion engine is in an acceleration state or a deceleration state, and based on the detection result Addition / subtraction is performed on the basic fuel injection amount based on the average value of the intake pressure.

  The EPI includes an injector (electromagnetic fuel injection valve) that injects fuel into a combustion chamber or an intake port of an internal combustion engine, a fuel pump that supplies fuel to the injector, and a predetermined amount of fuel from the injector at a predetermined crank angle position of the internal combustion engine. And an ECU (electronic control unit) that controls the injector so as to inject fuel.

  Further, the ECU drives the injector so that the fuel injection amount is calculated based on various control conditions such as the atmospheric pressure and the temperature of the internal combustion engine, and the calculated fuel injection amount is injected from the injector. And a driving circuit for supplying a signal. Then, the ECU controls the injector according to various control conditions so that the air-fuel mixture having a predetermined air-fuel ratio is supplied into the combustion chamber of the internal combustion engine.

  In this type of fuel injection device, it is necessary to know the amount of intake air flowing into the combustion chamber of the internal combustion engine in order to determine the amount of fuel injected from the injector. As a method for obtaining the intake air amount, a method (speed density method) for estimating the intake air amount from the intake pressure and the volumetric efficiency of the internal combustion engine is known.

  Also, the intake pressure signal detected by the pressure sensor provided in the intake passage of the internal combustion engine is the lowest value in the intake stroke, and is equal to the atmospheric pressure in other strokes where the intake valve is closed. A large ripple (pulsation component) occurs in the detected value. For this reason, accurate intake pressure cannot be measured only from the detection value of the pressure sensor.

  Therefore, in a conventional internal combustion engine, a surge tank or the like having a large capacity is provided in the intake passage to reduce the ripple of the intake pressure, detect the intake pressure of an arbitrary stroke by detecting the rotation angle of the internal combustion engine, or The intake pressure is accurately measured by performing a large smoothing process on the detected value of the intake pressure.

  Thus, in an internal combustion engine in which the amount of intake air flowing into the combustion chamber is estimated from the intake pressure and the volumetric efficiency of the internal combustion engine to determine the fuel injection amount, a surge tank is provided or the intake pressure is detected. By performing a large smoothing process on the value, the air-fuel ratio of the air-fuel mixture may become lean or rich due to a response delay when in an acceleration state or a deceleration state.

  That is, when the throttle valve provided in the intake passage is suddenly opened for acceleration by the driver (driver), a change in the intake pressure accompanying a change in the opening of the throttle valve is detected, and an estimated value of the intake air amount There will be a time lag before is corrected. For this reason, the fuel injection amount calculated by the ECU becomes smaller than the fuel injection amount actually required by the internal combustion engine, and the air-fuel ratio shifts to the lean side.

  Also, when the driver closes the throttle valve suddenly to decelerate, the fuel injection amount calculated by the ECU becomes larger than the fuel injection amount actually requested by the internal combustion engine due to the same response delay as described above. The air-fuel ratio shifts to the rich side. Therefore, if the fuel injection amount is controlled without considering the response delay at the time of acceleration and deceleration of the internal combustion engine, drivability at the time of acceleration and deceleration is deteriorated and exhaust emission is deteriorated.

  Here, when a large smoothing process is performed on the detected value of the intake pressure in order to reduce the ripple of the intake pressure and measure the correct intake pressure, a change in the intake pressure during acceleration or deceleration is detected. The time delay until the estimated value of the intake air amount is corrected increases, and drivability and exhaust emission are further deteriorated.

  Furthermore, in an internal combustion engine in which the amount of intake air flowing into the combustion chamber is estimated from the intake pressure and the volumetric efficiency of the internal combustion engine to determine the fuel injection amount, the fuel pressure is detected using the detected value of the intake pressure with a large ripple. If the injection amount is controlled, the fuel injection amount during steady operation varies according to the pulsation component of the intake pressure, and the air-fuel ratio during steady operation fluctuates wastefully, which degrades the drivability of steady stability. Or exhaust emissions worsen.

  To prevent these problems from occurring, during steady operation, the intake pressure ripple should be reduced as much as possible to measure the correct intake pressure, while the throttle valve must be operated rapidly to accelerate or decelerate. When it is broken, it is necessary to correct the acceleration increase or deceleration decrease by adding or subtracting the fuel injection amount according to the transient state to prevent the air-fuel ratio from shifting to the lean side or the rich side.

  In addition to controlling the fuel injection amount, for example, when controlling the ignition timing of the internal combustion engine, in order to improve the acceleration performance or suppress knocking due to abnormal combustion of the internal combustion engine, Control may be performed in consideration of the state and the deceleration state.

  As a conventional control device for an internal combustion engine, for example, Patent Document 1 proposes to suppress deterioration of drivability and reduce exhaust emission.

  In Patent Document 1, in order to reduce an error at the time of intake air pulsation of an internal combustion engine, a smoothing process is performed after converting a measured signal into a signal having a linear relationship with an air amount. A signal that includes flow smoothing processing means and that has performed the flow smoothing process and a signal that is responsive to changes in the intake air amount and that has a low degree of flow smoothing, or a signal that does not perform the flow smoothing process. A control apparatus for an internal combustion engine is disclosed that uses the calculation of an intake air amount of the internal combustion engine.

  In addition, the time delay of the intake air amount that occurs due to the installation of a surge tank, etc., is detected by detecting the acceleration / deceleration state of the internal combustion engine and correcting the increase / decrease amount of the fuel injection amount necessary and sufficient during acceleration / deceleration. It is a known technique to improve the operability at the time and to obtain good exhaust gas performance.

Japanese Patent No. 4906815

  According to the control device for an internal combustion engine disclosed in Patent Document 1, even when the measurement error of the average flow rate at the time of intake air pulsation of the internal combustion engine is small and the intake air amount changes abruptly, the intake is performed without time delay. By calculating the amount of air, exhaust emission is reduced. However, Patent Document 1 has the following problems.

  In Patent Document 1, when the transition from the transient state to the steady state occurs, in the state where the actual intake pressure at the end of the transient operation is almost converged and stable (immediately before the transition timing), there is almost no need for correction. Since the intake pressure is unnecessarily corrected, there is a problem that the measurement error of the average intake pressure becomes large and the air-fuel ratio is rich (see the enclosure α in FIG. 3 (h)). Details of FIG. 3 will be described later.)

  In addition, when the transition from the transient state to the steady state is corrected by adding the intake pressure deviation to the intake pressure, the addition is prohibited at the transition timing, so a step occurs in the intake pressure. As a result, there is a problem that the air-fuel ratio shifts to the lean side (see an enclosure α in FIG. 3H).

  As described above, in Patent Document 1, the combustion torque difference between the cylinders at the operation point (period) in which the ripple of the intake pressure is large and the pulsation component is reflected in the intake pressure until the state returns from the transient state to the steady state. There is a problem that the driveability deteriorates due to expansion, and the exhaust ratio deteriorates due to the air-fuel ratio shifting to the lean side or the rich side.

  The present invention has been made to solve such a problem, and at the time of steady operation, the intake pressure ripple is reduced as much as possible to accurately measure the intake pressure, and during transient operation such as acceleration or deceleration, By correcting the acceleration increase or deceleration decrease by adding or subtracting the fuel injection amount according to the transient state, the air-fuel ratio is prevented from shifting to the lean side or the rich side, and the state boundary between the steady operation and the transient operation It is an object of the present invention to obtain a fuel injection amount control device for an internal combustion engine that can prevent the air-fuel ratio from shifting to the lean side or the rich side.

The present invention relates to an intake pressure sensor that detects an intake pressure downstream of a throttle valve provided in an intake passage of an internal combustion engine, and an output signal of the intake pressure sensor is sampled every predetermined time, and has a linear relationship with the intake pressure. A smoothing processing unit that performs a smoothing process after converting into a pressure signal, and as the smoothing process, a first level smoothing process and a second degree of smoothness greater than the first level A pressure signal obtained by performing the first level smoothing process on the output signal of the intake pressure sensor as a first smooth pressure signal, and an output signal of the intake pressure sensor A smoothing processing unit that outputs the first smoothing pressure signal and the second smoothing pressure signal, with the pressure signal obtained by performing the second level smoothing processing as a second smoothing pressure signal. And the smoothing processing unit The averaged intake pressure average value is calculated by averaging the converted first smooth pressure signal at each combustion interval of the internal combustion engine, and the basic fuel injection is supplied to the internal combustion engine based on the intake pressure average value A basic fuel injection amount calculation unit for calculating the amount, and a change amount for each combustion interval with respect to the second smooth pressure signal smoothed by the smoothing processing unit, thereby calculating the intake air pressure after smoothing. An acceleration state detection unit that calculates a change amount and determines whether or not the vehicle is in an acceleration state based on the amount of change in the smoothed intake pressure, and when the acceleration state detection unit determines that the vehicle is in an acceleration state An acceleration fuel correction unit that increases and corrects the basic fuel injection amount based on an output signal of the intake pressure sensor, and the basic fuel injection amount calculation unit calculates the basic fuel injection amount based on the first smooth pressure signal. Fuel the basic fuel injection amount, The basic fuel calculated by the acceleration fuel correction unit based on the output signal of the intake pressure sensor only when the acceleration state detection unit determines that the acceleration state is based on the second smooth pressure signal A fuel injection amount control device for an internal combustion engine that injects a fuel injection amount corresponding to an increase correction of the injection amount.

  According to the present invention, the basic fuel injection amount is calculated based on the weak smooth pressure signal with a low degree of smoothing, and it is determined whether or not the vehicle is in an acceleration state based on the strong smooth pressure signal with a high degree of smoothing. The basic fuel injection amount is corrected to increase, so that the correct intake pressure is measured during steady operation, and the necessary and sufficient amount of fuel injection amount while suppressing the time delay of intake pressure during transient operation during acceleration. By performing this increase correction, it is possible to obtain a fuel injection amount control device for an internal combustion engine that can suppress deterioration of drivability and exhaust emission.

1 is a configuration diagram schematically showing an internal combustion engine according to Embodiment 1 of the present invention and a configuration around it. FIG. It is a block diagram which shows the system structure at the time of replacing the technique of the said patent document 1 with the internal speed engine of a speed density system. FIG. 3 is a chart showing the behavior of intake pressure, fuel injection amount, ignition timing, and air-fuel ratio during acceleration in the system configuration of FIG. 2. It is a block diagram which shows the structure of the fuel injection amount control apparatus of the internal combustion engine which concerns on Embodiment 1 of this invention. It is a chart figure which shows the behavior of the intake pressure at the time of acceleration, the fuel injection quantity, the ignition timing, and the air fuel ratio by control of the fuel injection quantity control device of the internal-combustion engine concerning Embodiment 1 of the present invention.

  A preferred embodiment of a fuel injection amount control device for an internal combustion engine according to the present invention will be described below with reference to the drawings. Note that an engine of a gasoline engine is assumed as the internal combustion engine in the present invention.

  In order to deepen the understanding of the present invention, before describing the embodiment of the present invention, the prior art shown in the above-mentioned Patent Document 1 is replaced with a speed-density internal combustion engine using FIG. 2 and FIG. A case will be described, and problems in that case will be described first.

  FIG. 2 is a block diagram showing a system configuration when the technique of Patent Document 1 is replaced with a speed-density internal combustion engine.

  The pressure sensor 201 is provided in the intake passage of the internal combustion engine, and detects the intake pressure of the intake air flowing into the combustion chamber of the internal combustion engine. The intake pressure signal output from the pressure sensor 201 is input to the hard filter processing unit 202, and high-frequency component noise is removed by the primary smoothing process. The intake pressure signal from which the high-frequency component has been removed by the hard filter processing unit 202 is input to the A / D conversion processing unit 203 inside the ECU, and converted into the intake pressure Pbi, which is a discrete signal every predetermined time.

  Subsequently, the strong smoothing processing unit 204 calculates the intake pressure Pbfs subjected to the primary smoothing process in which the degree of smoothing is large with respect to the intake pressure Pbi. Further, the weak smoothing processing unit 205 calculates the intake pressure Pbfw that has been subjected to the primary smoothing process that is less smoothed than the intake pressure Pbi. The weak smoothing processing unit 205 may set the intake pressure Pbi = the intake pressure Pbfw without calculating the intake pressure Pbfw subjected to the primary smoothing process. The intake pressure Pbfw is input to the correction processing unit 206. The correction processing unit 206 obtains an intake pressure Pbfw ′ obtained by further smoothing the intake pressure Pbfw, and calculates an intake pressure deviation ΔPbfw which is a deviation between the intake pressure Pbfw and the intake pressure Pbfw ′.

  Further, the steady / transient determination determination processing unit 207 receives at least one parameter that affects the intake air amount of the internal combustion engine, such as an accelerator opening, a throttle opening, and an engine speed, and the amount of change in the parameter is determined. If it exceeds a predetermined threshold value, it is determined as a transient state (transient determination flag = 1), otherwise it is determined as a steady state (transient determination flag = 0).

  When the steady / transient determination determination processing unit 207 determines that the engine is in a steady state, the intake pressure ripple is reduced as much as possible, and the intake pressure Pbfs with high intake pressure measurement accuracy is output. It is used for calculation of base ignition that is ignition timing and base fuel amount that is fuel injection amount of the internal combustion engine.

  On the other hand, when it is determined that the steady state / transient determination determination processing unit 207 is in the transient state, the intake pressure deviation ΔPbfw calculated by the correction processing unit 206 is added to the intake pressure Pbfs, and the control Pb Used for base ignition and calculation of base fuel amount.

  Subsequently, the ΔPbf processing unit 208 calculates an intake pressure change amount ΔPbfs from one combustion interval before the intake pressure Pbfs output from the strong smoothing processing unit 204, and increases or decreases the fuel with respect to the base fuel amount. This is used for acceleration / deceleration determination for determining whether or not to perform correction. As the acceleration / deceleration determination, the fuel increase / decrease amount correction is performed when the intake pressure change amount ΔPbfs exceeds a predetermined acceleration / deceleration determination threshold (acceleration / deceleration correction flag = 1). Otherwise, the fuel increase / decrease amount correction is performed. Is not performed (acceleration / deceleration correction flag = 0).

  Next, when the acceleration / deceleration determination is established and the fuel increase / decrease amount correction is performed, the ΔPbi processing unit 209 calculates the intake pressure change amount ΔPbi from one combustion interval before the intake pressure Pbi, Used to calculate the amount of increase / decrease correction.

  By the above calculation, both the stability of the fuel injection amount during steady operation and the responsiveness of the fuel injection amount during transient operation are achieved.

FIG. 3 is a chart showing the behavior of intake pressure, fuel injection amount, ignition timing, and air-fuel ratio during acceleration when the technique of Patent Document 1 shown in FIG. 2 is replaced with a speed-density internal combustion engine. It is. More specifically, the following behaviors are shown as (a) to (h).
(A) Transient determination flag (b) Throttle opening (c) Intake pressure (d) Base fuel amount (e) Base ignition (f) Intake pressure change amount ΔPbfs
(G) Acceleration increase correction amount (h) Air-fuel ratio

  The transition determination flag shown in FIG. 3A switches between establishment / non-establishment (= 1/0) when the throttle opening degree shown in FIG. 3B changes. Specifically, if the throttle opening shown in FIG. 3B exceeds a predetermined threshold, the transient determination flag shown in FIG. 3A is changed from the steady state (transient determination flag = 0), Transition to a transient state (transient determination flag = 1). In FIG. 3, since the throttle opening shown in FIG. 3B exceeds a predetermined threshold at the timing t1, the transient determination flag is established at that point (transient determination flag = 1). Here, as an example, the throttle opening is used as a parameter that affects the intake air amount of the internal combustion engine, which is used for determination of steady / transient determination. However, the present invention is not limited to this, and the accelerator opening and engine rotation are not limited thereto. Other parameters may be used as long as they affect the intake air amount of the internal combustion engine, such as the number.

  Thus, when the transient determination flag is established (transient determination flag = 1), the control Pb (intake pressure) shown in FIG. 3C is obtained by adding the intake pressure deviation ΔPbfw to the intake pressure Pbfs during steady operation. Switch to When the base fuel amount shown in FIG. 3 (d) and the base ignition shown in FIG. 3 (e) are calculated by this control Pb, the pulsation component corresponding to the ripple of the intake pressure is included while the transient determination flag is established. As a response of the fuel injection amount, a time delay can be reduced.

  Further, although not provided in the configuration of FIG. 2, when a surge tank is provided. Due to the time delay of the intake pressure generated by providing the surge tank, an air-fuel ratio lean as shown by a broken line in FIG. In that case, the intake pressure change amount ΔPbfs shown in FIG. 3F exceeds the acceleration increase determination threshold. Therefore, since an acceleration / deceleration correction flag (not shown in FIG. 3) is established, it is possible to suitably control the air-fuel ratio without shifting to the lean side by performing the acceleration increase correction of the fuel shown in FIG.

  On the other hand, at the timing t2 when the transition determination flag returns from establishment to failure in FIG. 3A, the intake pressure deviation ΔPbfw has been added to the intake pressure Pbfs so far as the control Pb, whereas at the timing t2. Since the addition is prohibited, a step is generated in the control Pb.

  Further, at the timing immediately before t2 when the actual intake pressure at the end of the transient operation is almost convergent and stable, the intake pressure deviation ΔPbfw is added unnecessarily, and the measurement error of the average intake pressure becomes large. The rich air-fuel ratio occurs as in the enclosure portion α of 3 (h).

  At the operating point (period) in which the ripple of the intake pressure is large and the pulsation component is reflected in the control Pb until these transient determination flags are returned from establishment to failure, the combustion torque difference between the cylinders increases and drivability increases. Or the air-fuel ratio shifts to the lean side or the rich side and exhaust emission deteriorates.

  In the embodiment of the present invention, in order to solve such a problem, the intake pressure ripple is reduced as much as possible during steady operation to measure the correct intake pressure, and transient operation such as during acceleration or deceleration is performed. Sometimes, by correcting the acceleration increase or deceleration decrease by adding or subtracting the fuel injection amount according to the transient state, the air-fuel ratio is prevented from shifting to the lean side or the rich side, and the steady operation and the transient operation are performed. A fuel injection amount control apparatus for an internal combustion engine that can prevent the air-fuel ratio from shifting to the lean side or the rich side even at the state boundary will be described.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram schematically showing the configuration of an internal combustion engine (engine 1) according to Embodiment 1 of the present invention and its periphery. As shown in FIG. 1, an electronically controlled throttle valve 2 that is electronically controlled to adjust the intake air amount is provided upstream of the intake system of the engine 1. In order to measure the opening degree of the electronically controlled throttle valve 2, a throttle opening degree sensor 3 is provided.

  A surge tank 4 is provided on the engine 1 downstream of the electronically controlled throttle valve 2. The surge tank 4 is provided with an intake pressure sensor 5 for measuring the pressure in the surge tank 4 and an intake air temperature sensor 6 for measuring the intake air temperature.

  An intake port 7 downstream of the surge tank 4 is provided with an injector 8 for injecting fuel. The injector 8 may be provided so that it can be directly injected into the combustion chamber of the engine 1.

  An intake valve 9 for opening and closing between the intake port 7 and the combustion chamber of the engine 1 is provided at the downstream end of the intake port 7, and this intake valve 9 is used for the air-fuel mixture sucked into the combustion chamber. Regulate the amount. Further, a variable valve gear (not shown in FIG. 1) that can change the valve opening characteristics of the intake valve 9 may be provided.

  Furthermore, an ignition coil 10 for igniting the air-fuel mixture in the combustion chamber of the engine 1 and a spark plug 11 are provided for the engine 1. Further, a crank angle sensor 12 for detecting the edge of a plate provided on the crankshaft is provided for the engine 1 in order to detect the rotational speed and crank angle position of the engine 1.

  Further, an exhaust valve 14 that opens and closes between the exhaust port 13 downstream of the engine 1 and the combustion chamber is provided. Further, an O 2 sensor 15 that measures the oxygen concentration of the exhaust gas is provided downstream of the exhaust port 13. Further downstream, a catalyst 16 for purifying exhaust gas is provided. As the catalyst 16, for example, a three-way catalyst, a NOX catalyst, or the like is used.

  The intake pressure measured by the intake pressure sensor 5, the opening degree of the electronically controlled throttle valve 2 measured by the throttle opening sensor 3, the intake air temperature measured by the intake air temperature sensor 6, and the output from the crank angle sensor 12 The pulse synchronized with the edge of the plate provided on the crankshaft and the oxygen concentration of the exhaust gas measured by the O2 sensor 15 are input to an electronic control unit 18 (hereinafter referred to as “ECU18”). .

  The ECU 18 is a unit mainly composed of a microcomputer. In addition to the output signals of the sensors, the ECU 18 is measured by a battery output voltage, a starter switch on / off signal, and a water temperature sensor not shown in FIG. A coolant temperature signal, an atmospheric pressure signal measured by an atmospheric pressure sensor, and a position (angle) signal of the intake cam 17 measured by a variable valve operating device are input.

  The ECU 18 also includes an ignition timing control device that controls the advance / retard of the ignition timing (ignition base) by outputting an energization / interruption signal to the ignition coil 10 in accordance with various input signals. Further, the ECU 17 also outputs instruction signals to various actuators other than those described above.

  The ECU 18 also includes a fuel injection amount control device that injects an appropriate combustion injection amount from the injector 8 by obtaining an appropriate fuel injection amount in accordance with various input signals and outputting the fuel injection amount to the injector 8. .

  Next, the system configuration of the internal combustion engine fuel injection amount control apparatus according to the first embodiment will be described in detail with reference to FIG. In FIG. 4, components corresponding to those in FIG. 1 are denoted by the same reference numerals.

  As shown in FIG. 4, the fuel injection amount control apparatus for an internal combustion engine according to the first embodiment is configured to detect the intake pressure downstream of the throttle valve provided in the intake passage of the internal combustion engine mounted on the vehicle. The sensor 5, the output signal of the intake pressure sensor 5 is sampled every predetermined time, converted into a pressure signal having a linear relationship with the intake pressure, and then smoothed, and a smoothing processor 50. A basic fuel injection amount calculation unit 51 that calculates the basic fuel injection amount to be supplied to the internal combustion engine by calculating the intake air pressure average value by averaging the pressure signal smoothed by each combustion interval; By calculating a change amount for each combustion interval with respect to the pressure signal smoothed by the processing unit 50, a change amount of the smoothed intake pressure is calculated, and whether or not the vehicle is in an acceleration state based on the change amount. Acceleration state detector 5 for determining whether If, when it is determined that the acceleration state by the acceleration state detecting section 52, and a acceleration fuel correction unit 53 for increasing correction of the basic fuel injection amount.

  The smoothing process part 50 has two things from which the grade of smoothing differs as a smoothing process. Of the two smoothing levels, the smaller smoothing level is called the “first level”, and the higher smoothing level than the “first level” is called the “second level”. I will do it. The smoothing processing unit 50 includes a weak smoothing processing unit 504 that performs a “first level” smoothing process on an intake pressure Pbi output from an A / D conversion processing unit 503 described later, And a strong smoothing processing unit 506 that performs a “level” smoothing process. The smoothing processing in the weak smoothing processing unit 504 and the strong smoothing processing unit 506 may be performed by, for example, filter processing. The difference in the degree of smoothing may be determined as appropriate. However, as shown in FIG. 5C, the intake pressure (Pbfs) subjected to the strong smoothing process has a pulsation component corresponding to the ripple of the intake pressure. Although it is a gentle curve not included, the intake pressure (Pbfw) subjected to the weak smoothing process includes a pulsation component. Naturally, the pulsation component included in the intake pressure (Pbfw) subjected to the weak smoothing process is smaller than the pulsation component of the intake pressure Pbi output from the A / D conversion processing unit 503. That is, in the weak smoothing process, the pulsation component of the intake pressure Pbi is reduced, and in the strong smoothing process, the pulsation component of the intake pressure Pbi is removed. The fuel injection amount control apparatus for an internal combustion engine according to the first embodiment determines the basic fuel injection amount by the basic fuel injection amount calculation unit 51 based on the weak smooth pressure signal that has been subjected to the “first level” smoothing process. Acceleration / deceleration determination is performed by the acceleration state detection unit 52 based on the strong smooth pressure signal that has been calculated and subjected to the “second level” smoothing process in which the degree of smoothing is greater than the “first level”.

  The intake pressure sensor 5 includes a pressure sensor 501 and a hard filter processing unit 502. The pressure sensor 501 is provided in the intake passage of the engine 1 and detects the intake pressure on the downstream side of the throttle valve 2. The hard filter processing unit 502 receives the intake pressure signal output from the pressure sensor 501 and removes high-frequency component noise by a primary smoothing process.

The basic fuel injection amount calculation unit 51 includes an arithmetic mean processing unit 505. The arithmetic mean processing unit 505 receives the intake pressure Pbfw subjected to the “first level” smoothing processing by the weak smoothing processing unit 504. The arithmetic mean processing unit 505 performs arithmetic mean processing on the input intake pressure Pbfw at every combustion interval, and calculates control Pb, which is an intake pressure average value in the past one combustion interval. Using this control Pb, the base ignition, which is the ignition timing of the engine 1, and the base fuel amount, which is the fuel injection amount of the engine 1, are calculated.
As a base ignition calculation method, for example, a base ignition, that is, an ignition timing is calculated using a lookup table (map). The look-up table (map) is such that the optimal engine 1 ignition timing is set with respect to the grid point between the engine speed and the control Pb with the engine speed and the control Pb as axes. . Therefore, when the engine speed and the control Pb are input as input parameters to the lookup table, the optimum engine 1 ignition timing corresponding to the engine speed and the control Pb is retrieved from the lookup table and output. The
Further, as a base fuel calculation method, for example, the fuel amount in one stroke is calculated by multiplying the control Pb by a preset fuel amount conversion coefficient.

  The acceleration state detection unit 52 includes a ΔPbf processing unit 507. The ΔPbf processing unit 507 receives the intake pressure Pbfs subjected to the “second level” smoothing process by the strong smoothing processing unit 506. The ΔPbf processing unit 507 calculates an intake pressure change amount ΔPbfs from one combustion interval before the input intake pressure Pbfs, and uses the intake pressure change amount ΔPbfs to correct the fuel increase / decrease amount with respect to the base fuel amount. Acceleration / deceleration determination is performed to determine whether or not to perform. In the acceleration / deceleration determination, when the intake pressure change amount ΔPbfs exceeds a predetermined acceleration / deceleration determination threshold, it is determined that the vehicle is in an acceleration state or a deceleration state, and fuel increase / decrease amount correction is performed (acceleration / deceleration correction). Flag = 1), otherwise, it is determined that the vehicle is neither in the acceleration state nor in the deceleration state, and the fuel increase / decrease amount correction is not performed (acceleration / deceleration correction flag = 0). In addition, it is not restricted to this case, You may make it only determine whether it is acceleration. In this case, a predetermined acceleration determination threshold is set for the intake pressure change amount ΔPbfs, and when the threshold is exceeded, it is determined that the vehicle is in an acceleration state, and fuel increase correction is performed. (Acceleration / deceleration correction flag = 1), otherwise, it is determined that the vehicle is not in an acceleration state, and fuel increase correction is not performed (acceleration / deceleration correction flag = 0).

The acceleration fuel correction unit 53 includes a ΔPbi processing unit 508. The ΔPbi processing unit 508 receives the acceleration / deceleration determination result from the acceleration state detection unit 52 and the intake pressure Pbi from the A / D conversion processing unit 503. When the acceleration state detection unit 52 determines that the vehicle is in an acceleration state or a deceleration state, the ΔPbi processing unit 508 calculates an intake pressure change amount ΔPbi from one combustion interval before the intake pressure Pbi, and An increase / decrease amount correction amount for increasing / decreasing the basic fuel injection amount is calculated based on the atmospheric pressure change amount ΔPbi. As described above, when the acceleration state detection unit 52 only determines whether the vehicle is accelerating, the ΔPbi processing unit 508 determines that the acceleration state detection unit 52 determines that the vehicle is in the acceleration state. Then, an intake pressure change amount ΔPbi from one combustion interval before the intake pressure Pbi is calculated, and an increase correction amount for correcting the basic fuel injection amount is calculated based on the intake pressure change amount ΔPbi.
As a method for calculating the increase / decrease amount correction amount, for example, the intake pressure change amount ΔPbi is multiplied by a preset correction amount conversion coefficient, and further, a correction coefficient corresponding to the operating state such as the engine rotation speed and the water temperature is set. What is necessary is just to obtain by multiplying.

  Next, the operation of the internal combustion engine fuel injection amount control apparatus according to the first embodiment will be described with reference to FIG.

  The pressure sensor 501 is provided in the intake passage of the engine 1 and detects the intake pressure on the downstream side of the throttle valve 2. The intake pressure signal output from the pressure sensor 501 is input to the hard filter processing unit 502, and high-frequency component noise is removed by the primary smoothing process. The intake pressure signal from which the high frequency component has been removed by the hard filter processing unit 502 is input to an A / D conversion processing unit 503 in the ECU 18 and converted into an intake pressure Pbi that is a discrete signal every predetermined time.

  Subsequently, the weak smoothing processing unit 504 calculates the intake pressure Pbfw by performing a “first level” primary smoothing process with a low degree of smoothing on the intake pressure Pbi. Further, the arithmetic mean processing unit 505 performs arithmetic mean processing for each combustion interval with respect to the intake pressure Pbfw, and calculates control Pb which is an intake pressure average value in the past one combustion interval. Further, the arithmetic mean processing unit 505 calculates the base ignition that is the ignition timing of the internal combustion engine and the basic fuel injection amount (base fuel amount) that is the fuel injection amount of the internal combustion engine using the control Pb.

  In the first embodiment, by adopting such a system configuration, the base ignition and the base injection amount can be calculated without applying a primary smoothing with a large degree of smoothing, so that the response during transient operation is good. Thus, it is possible to suppress the deterioration of knocking due to the ignition delay during acceleration and the air-fuel ratio shift due to the delay in the base injection amount during acceleration.

  On the other hand, the strong smoothing processing unit 506 calculates the intake pressure Pbfs by performing a “second level” primary smoothing process with a high degree of smoothing on the intake pressure Pbi. Next, the ΔPbf processing unit 507 calculates the intake pressure change amount ΔPbfs from one combustion interval before the intake pressure Pbfs output from the strong smoothing processing unit 506, and uses the intake pressure change amount ΔPbfs to calculate the base pressure. Acceleration / deceleration determination is performed to determine whether to perform fuel increase / decrease correction for the fuel amount. As the acceleration / deceleration determination, the fuel increase / decrease amount correction is performed when the intake pressure change amount ΔPbfs exceeds a predetermined acceleration / deceleration determination threshold (acceleration / deceleration correction flag = 1). Otherwise, the fuel increase / decrease amount correction is performed. Is not performed (acceleration / deceleration correction flag = 0).

  Here, as the intake pressure used for acceleration / deceleration determination, if the internal combustion engine with a large ripple in the intake pressure or the primary smoothing with a large degree of smoothing is not performed in the operating state, the amount of change in the intake pressure is larger due to the pulsation component. Therefore, it becomes difficult to appropriately set the acceleration / deceleration determination threshold value in advance. If the acceleration / deceleration determination threshold value cannot be set appropriately, erroneous correction, overcorrection, or undercorrection of the fuel increase / decrease amount correction is caused, and the air-fuel ratio cannot be suitably controlled. That is, in order to perform fuel increase / decrease correction without exceeding the acceleration / deceleration determination threshold value during transient operation and exceeding the acceleration / deceleration determination threshold value during transient operation, the degree of smoothing is large with respect to the intake pressure. It is necessary to perform the following annealing. Therefore, in the present embodiment, acceleration / deceleration determination is performed using the intake pressure Pbfs subjected to the primary smoothing with a large degree of smoothing.

  Next, when the acceleration / deceleration determination is established and the fuel increase / decrease amount correction is performed, the ΔPbi processing unit 508 calculates the intake pressure change amount ΔPbi from one combustion interval before the intake pressure Pbi, A fuel increase / decrease amount correction amount is calculated based on the intake pressure change amount ΔPbi.

  In the first embodiment, such a system configuration makes it possible to appropriately remove the pulsation component even when the pulsation component of the intake pressure is large, and appropriately correct the fuel increase / decrease during transient operation. The air-fuel ratio can be suitably controlled by performing the above.

Next, the behavior of intake pressure, fuel injection amount, ignition timing, and air-fuel ratio during acceleration according to the first embodiment will be described in detail with reference to FIG. More specifically, the following behaviors are shown as (a) to (h).
(A) Transient determination flag (b) Throttle opening (c) Intake pressure (d) Base fuel amount (e) Base ignition (f) Intake pressure change amount ΔPbfs
(G) Acceleration / deceleration correction amount (h) Air-fuel ratio

  As shown in FIG. 5A, in the first embodiment, there is no transient determination flag as shown in FIG. 3A, and the control Pb is switched between steady operation and transient operation. Such a configuration is not necessary. Even if the value of a parameter that affects the intake air amount of the internal combustion engine such as the throttle opening shown in FIG. 5B changes, the control Pb shown in FIG. It is obtained by performing an arithmetic mean process for each combustion interval on Pbfw.

  By calculating the base fuel amount shown in FIG. 5 (d) and the base ignition shown in FIG. 5 (e) by this control Pb, the time delay can be suppressed as a responsiveness. As a result, knocking due to the ignition delay during acceleration Also, the deviation of the air-fuel ratio due to the delay of the base injection amount can be minimized. In addition, as a stability during steady operation, a measurement error can be kept small by an arithmetic averaging process for the intake pressure Pbfw.

  Further, when the air-fuel ratio lean as shown by the broken line in FIG. 5 (h) occurs due to the time delay of the intake pressure generated by providing the surge tank, after the strong smoothing shown in FIG. 5 (f). When the change amount ΔPbfs of the intake air pressure exceeds the acceleration increase determination threshold value, an acceleration / deceleration correction flag (not shown) in FIG. 5 is established at the timing t1, and the fuel acceleration increase correction shown in FIG. The fuel ratio can be suitably controlled without shifting to the lean side.

  Here, the acceleration increase correction amount is larger than that in the case of using the control Pb that is switched in the prior art shown in FIG. 3, but due to adaptation of the correction amount, the acceleration increase correction amount in the prior art shown in FIG. It is possible to make it equivalent to the air-fuel ratio behavior.

  Further, at the timing t2 when the transient operation is converging, since the control Pb is not switched as in the prior art shown in FIG. 3, the base fuel amount shown in FIG. 5D or FIG. As shown in FIG. 5, no step is generated due to the switching.

  Further, immediately before the timing t2 when the actual intake pressure at the end of the transient operation is almost convergent and stable, the difference in combustion torque between the cylinders is increased by using the control Pb containing a large pulsation component. Thus, it is possible to solve the conventional problems that the drivability is deteriorated and the exhaust emission is deteriorated because the air-fuel ratio is shifted to the lean side or the rich side. As a result, the air-fuel ratio can be suitably controlled as in the enclosure portion β in FIG.

Summarizing the above results, Embodiment 1 of the present application can obtain the following effects.
(Effect 1): As the smoothing process, the basic fuel injection amount (base fuel amount) is calculated based on the weakly smoothed intake pressure that has two smoothing processes with different smoothing levels. By deciding whether or not to perform fuel acceleration increase correction based on the intake pressure after strong smoothing with a large degree of smoothing, the effect of the ripple of intake pressure pulsation is reduced as much as possible during normal operation. By calculating the correct intake pressure, while maintaining stability, during transient operation, while suppressing the time delay of the intake pressure as much as possible, by correcting the acceleration increase of the necessary and sufficient amount of fuel, the knocking due to the ignition delay is suppressed, the air-fuel ratio Can be suitably controlled. As a result, it is possible to suppress deterioration of drivability and exhaust emission.
(Effect 2): has a deceleration determination threshold for determining whether to perform the acceleration increase correction of the fuel, the acceleration determination threshold in advance for the change amount of the intake pressure after the degree is large strong smoothing smoothing By setting and correcting the fuel acceleration increase when the intake pressure change amount exceeds the acceleration judgment threshold, the air-fuel ratio is controlled appropriately without causing erroneous correction, overcorrection, or insufficient correction of the acceleration increase correction. can do.

  As described above, in the first embodiment, the intake pressure sensor 5 that detects the intake pressure downstream of the throttle valve 2 provided in the intake passage of the engine 1 and the output signal of the intake pressure sensor 5 are output for a predetermined time. A smoothing processing unit 50 that samples each time and converts it into a pressure signal that is linearly related to the intake pressure, and performs a smoothing process, and the pressure signal smoothed by the smoothing processing unit 50 for each combustion interval of the engine 1 The basic fuel injection amount calculation unit 51 that calculates the basic fuel injection amount to be supplied to the engine 1 based on the intake pressure average value, and the smoothing processing unit 50 smoothes the intake pressure average value. The amount of change in the intake pressure after smoothing is calculated by calculating the amount of change for each combustion interval with respect to the converted pressure signal, and whether or not the acceleration state is based on the amount of change in the intake pressure after smoothing Acceleration state detector 5 for determining If, when it is determined that the acceleration state by the acceleration state detecting section 52, and a acceleration fuel correction unit 53 for increasing correction of the basic fuel injection quantity on the basis of the output signal of the intake pressure sensor 5. Further, the smoothing processing unit 50 has a first level as a smoothing degree of the smoothing process and a second level having a degree of smoothness larger than the first level, and an output signal of the intake pressure sensor 5 Is output as a first smooth pressure signal (weak smooth pressure signal), and a second level smoothing is performed on the output signal of the intake pressure sensor 5. The processed pressure signal is output as a second smooth pressure signal (strong smooth pressure signal), and the basic fuel injection amount calculation unit 51 uses the first smooth pressure signal as the smoothed pressure signal and the basic fuel. The injection amount is calculated, and the acceleration state detection unit 52 determines whether or not the vehicle is in the acceleration state using the second smooth pressure signal as the smoothed pressure signal. As a result, during steady operation, the intake pressure ripple is reduced as much as possible to measure the correct intake pressure, and during transient operation such as acceleration or deceleration, the fuel injection amount is added or subtracted depending on the transient state. Preventing the air-fuel ratio from shifting to the lean side or rich side by correcting the increase or deceleration, and preventing the air-fuel ratio from shifting to the lean side or rich side even at the boundary between steady operation and transient operation I can do it.

  In the first embodiment, the case where only acceleration is considered has been described. However, the present invention is not limited to this, and may be configured to be taken into consideration during deceleration.

  1 engine, 2 electronically controlled throttle valve, 3 throttle opening sensor, 4 surge tank, 5 intake pressure sensor, 6 intake air temperature sensor, 7 intake port, 8 injector, 9 intake valve, 10 ignition coil, 11 ignition plug, 12 Crank angle sensor, 13 exhaust port, 14 exhaust valve, 15 O2 sensor, 16 catalyst, 17 intake cam, start timing of T1 acceleration increase correction, timing when T2 transient determination flag is switched from established to unestablished, or transient operation converges Timing.

Claims (2)

An intake pressure sensor for detecting an intake pressure downstream of a throttle valve provided in an intake passage of the internal combustion engine;
A smoothing processing unit that samples an output signal of the intake pressure sensor every predetermined time, converts the output signal into a pressure signal that is linearly related to the intake pressure, and performs a smoothing process. Level smoothing process and a second level smoothing process having a degree of smoothness greater than that of the first level, and the first level smoothing with respect to the output signal of the intake pressure sensor. The processed pressure signal is defined as a first smooth pressure signal, and the pressure signal obtained by performing the second level smoothing process on the output signal of the intake pressure sensor is defined as a second smooth pressure signal. A smoothing processing unit that outputs a smooth pressure signal of 1 and the second smooth pressure signal;
The intake pressure average value is calculated by averaging the first smooth pressure signal smoothed by the smoothing processing unit at every combustion interval of the internal combustion engine, and the internal combustion engine is calculated based on the intake pressure average value. A basic fuel injection amount calculation unit for calculating a basic fuel injection amount to be supplied to the engine;
A change amount of the smoothed intake pressure is calculated by calculating a change amount for each combustion interval with respect to the second smooth pressure signal smoothed by the smoothing processing unit, and the smoothed intake pressure is calculated. An acceleration state detector that determines whether or not the vehicle is in an acceleration state based on a change amount of
An acceleration fuel correction unit that increases and corrects the basic fuel injection amount based on an output signal of the intake pressure sensor when the acceleration state detection unit determines that the vehicle is in an acceleration state ;
Fuel injection of the basic fuel injection amount calculated by the basic fuel injection amount calculation unit based on the first smooth pressure signal;
The basic fuel calculated by the acceleration fuel correction unit based on the output signal of the intake pressure sensor only when the acceleration state detection unit determines that the acceleration state is based on the second smooth pressure signal Inject the fuel injection amount for the amount obtained by increasing the injection amount,
A fuel injection amount control device for an internal combustion engine. The acceleration state detection unit has an acceleration determination threshold value for determining whether or not to increase the basic fuel injection amount, and when the amount of change in the smoothed intake pressure exceeds the acceleration determination threshold value The increase correction is performed, otherwise the increase correction is not performed,
The fuel injection amount control device for an internal combustion engine according to claim 1, wherein the acceleration determination threshold value is preset with respect to a change amount of the smoothed intake pressure.

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