JPH10274079A - Control device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge an operating condition of an engine precisely, and achieve engine control such as suitable fuel injection control by setting an acceleration/ deceleration judgment of an engine to a judging cycle which is long to the utmost, and judging the judgment of acceleration/deceleration on the basis of an intake air rate per prescribed rotating angle of a rotary shaft. SOLUTION: In an ECU 40, a suction intake rate Q is found out from an output signal of an air flow meter 21, and also a suction intake rate change ΔQL is calculated, and it is judged whether the suction intake rate change ΔQL is larger a prescribed value α or not. When 'YES' is judged, a suction intake rate QIST, at the time of a previous performance is read at a cycle shorter than a rotary angle synchronous timing of an engine. An intake rate Qf sucked into a cylinder is predicted, and also an accelerating judgment flag F showing the detection of an accelerating condition is set to 1. A newest suction intake rate Q is converted into a suction intake rate Q1 . In the case where acceleration is judged, a suction intake predicting rate Qf is employed as a referential intake rate Qa for deciding a fuel injection rate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of an engine, and more particularly, to control of an engine provided with a means for detecting an intake air amount based on an output of an air flow sensor or a throttle opening sensor.

[0002]

2. Description of the Related Art The output of an engine is basically determined by the amount of intake air and the amount of fuel. For naturally aspirated engines,
Although the fuel amount is automatically determined by the intake negative pressure, in the case of a fuel injection type engine, the output of the engine is controlled by detecting the intake air amount and setting an appropriate fuel injection amount corresponding thereto. It has become. In this case, the intake air amount is calculated based on the output from the air flow sensor, and the fuel injection amount is determined based on the calculated intake air amount so as to have a predetermined air-fuel ratio according to the operating state of the engine. You. However, the output of the air flow sensor does not always correspond to the amount of intake air actually introduced into the engine. Although the fuel injection amount is based on the output of the air flow sensor, it takes a long time to calculate the fuel injection amount before executing the fuel injection. For this reason, the output to the airflow sensor and the actual intake / intake air amount at the fuel injection timing are not signified. Therefore, when setting the fuel injection amount based on the output of the air flow sensor, it is necessary to calculate the fuel injection amount by replacing the output of the air flow sensor with the intake air amount actually charged into the combustion chamber. .

In this case, when the operating state of the engine is in a steady state, that is, when the throttle opening does not substantially change, the intake air intake amount does not change, and the output of the air flow sensor is directly used as the fuel injection amount. There is no problem even if it is adopted in the calculation of. However, in an acceleration / deceleration state in which the operating state of the engine is in an unsteady state, that is, a state in which the throttle opening changes, the difference between the output of the air flow sensor and the amount of intake air actually charged into the combustion chamber becomes remarkable. The fuel injection control cannot be achieved. Tokuhei 3
-64693 discloses an engine control device which calculates acceleration in an accelerating state of an engine and performs fuel increase correction in accordance with the acceleration. Also, at the time of acceleration / deceleration, based on the intake / intake air amount grasped from the output of the airflow sensor or throttle opening sensor, etc.
It is known that an intake air amount actually charged into a combustion chamber in an operation state corresponding to the output is predicted, and a fuel injection amount is calculated based on a predicted value of the intake air amount.

In this case, even when the engine is in a steady operation state, the output value of the means for detecting the amount of intake air such as an air flow sensor slightly fluctuates due to intake pulsation or the like. Therefore, in the conventional engine control, when the fluctuation of the output value of the intake air amount detection means is within a predetermined range so that the intake pulsation is not determined to be in the unsteady operation state, it is determined that the engine is in the steady state. The intake / intake air amount prediction control is not performed.

[0005]

However, in the conventional intake / intake air amount predicting control, with respect to fluctuations in the output value of the intake / intake air amount detecting means within a certain range, the operating state is regarded as a steady state, Since the intake amount prediction is not performed, even in a state where the operating state changes slightly, for example, in a state of slow acceleration, slow deceleration, etc., if the fluctuation of the output value is within the set range, the steady state is maintained. There is a problem that it is determined that the vehicle is in the state, and a proper prediction of the intake air amount is not performed.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and can accurately determine the operating state of an engine, thereby achieving appropriate engine control such as fuel injection control. It is an object of the present invention to provide an engine control device that can perform the operation. An object of the present invention is to provide an intake air amount detecting means for generating a signal indicating an intake air amount, and a first intake air amount calculating means for calculating an intake air amount of the engine at predetermined time intervals according to an output of the intake air amount detecting means. Means for predicting a reference intake air amount for subsequent engine control based on the intake air amount calculated by the first intake air amount calculating means; and the first intake air amount calculating means A second intake / intake air amount calculating means for calculating an intake / intake air amount of the engine at predetermined time intervals longer than
Acceleration / deceleration determining means for determining the acceleration / deceleration of the engine based on the output of the intake / intake air amount calculation means, wherein when the acceleration / deceleration determination means determines that the engine is not in the acceleration / deceleration state, the reference intake air amount prediction is performed. The prediction of the reference intake air amount by the means is invalidated.

In this case, preferably, the second
The intake / intake air amount calculation means calculates an intake / intake air amount for each predetermined rotation angle of a rotating shaft that rotates in response to engine rotation. The above-mentioned intake air amount detecting means includes any means for directly or indirectly generating an output corresponding to the intake air intake amount, such as an air flow sensor and a throttle opening sensor. Preferably, after the intake air amount detecting means generates a signal to calculate the intake air amount by the first intake air amount calculating means, the intake air amount to be charged into the combustion chamber of the cylinder to be in the intake stroke is predicted. It is supposed to. The reference intake amount predicting means normally predicts the reference intake amount based on the latest value calculated by the first intake intake amount calculating means. The reference intake amount is, for example, a reference for calculating the fuel injection amount.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the embodiment of the present invention, a signal from an arbitrary intake air amount detecting means such as an air flow sensor or a throttle opening sensor is preferably transmitted to an electronic control unit (including a microcomputer). EC
U) is continuously input. In the ECU, the first intake / intake air amount calculation means processes this signal at predetermined time intervals to calculate the intake / intake air amount of the engine based on the intake air amount detection means.
In this case, the predetermined interval at which the first intake / intake air amount calculating means performs the calculation is appropriately set within a range not affected by the output fluctuation due to the intake pulsation or the like from the intake air amount detecting means. A calculation process is performed to remove the intake air amount. Next, the reference intake amount predicting means predicts the reference intake intake amount for the subsequent engine control such as the fuel injection amount at the next injection timing, usually based on the latest calculated value of the intake intake amount and its change amount. It is supposed to. The latest intake / intake air amount means the intake / intake air amount calculated by the first intake / intake air amount calculation means immediately before the calculation of the fuel injection amount in the cylinder is started.

Thus, the time difference between the predicted intake air amount and the actual intake air amount at the injection timing can be minimized, and it is possible to predict the optimal reference intake amount as much as possible. it can. In this case, the reference intake air amount is determined in consideration of the amount of change in the intake air amount from the latest intake air amount calculated by evaluating the operating state of the engine, that is, the acceleration / deceleration state of the engine, until the intake valve closes. This is the predicted intake air amount actually charged into the combustion chamber. The calculation cycle of the reference intake air amount predicting means is set as short as possible within a range for ensuring the calculation time of the suction air reference intake air amount prediction calculation. According to the present invention, there is provided a second intake air amount calculating means for determining the operating state of the engine more precisely. The calculation cycle of the second intake / intake air amount calculation means is set longer than that of the first intake / intake air amount calculation means. Therefore, the second intake / intake air amount calculation means has a smaller fluctuation width in a short cycle than the first intake / intake air amount calculation means,
A large cycle change can be accurately grasped. Therefore, the first intake / intake air amount calculating means can properly detect the non-steady operation as well as the steady operation. In the present invention, the operation cycle of the first intake / intake air amount calculating means is set to, for example, about 2 ms to 10 ms, preferably, in synchronization with the engine rotation.
The calculation cycle of the intake / intake air amount calculation means is, for example, 20 to 10
It is set to 0 ms.

Further, the operation cycle of the first intake / intake air amount calculating means is set so as to eliminate the intake pulsation and to ascertain the fluctuation of the operating state as accurately as possible. You may comprise so that a steady state may be determined.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a multi-cylinder engine according to the present invention. The engine of this embodiment is a four-cylinder cycle engine 1, and in each cylinder, a combustion chamber 3 is formed in a cylinder bore above which a piston 2 slides. The combustion chamber 3 has an intake port and an exhaust port 5 which are open.
And the exhaust valve 7 are combined. Further, a spark plug 8 is attached to the cylinder head of the engine 1 as desired in the combustion chamber 3. The ignition plug 8 is connected to an ignition circuit 9 that starts an igniter at a predetermined ignition timing by electronic control.

The piston 2 of each cylinder of the engine 1 is attached to one common crankshaft as engine output means. A crank angle detecting member 11 having a projection 12 at a predetermined position on the outer periphery is attached to an end of the crankshaft. A crank angle sensor 13 composed of an electromagnetic pickup or the like is arranged at a position corresponding to the detection member 11. During the operation of the engine, a pulse signal is generated by detecting a magnetic field change caused by the projection 12 passing through the crank angle sensor 13.
A water temperature sensor 14 is attached to the engine 1. The intake system of the engine includes an intake passage 16 for introducing the intake air introduced through the air cleaner 15 into the engine 1. The intake passage includes an upstream common intake passage 17
And a surge tank 18 located downstream thereof, and a cylinder-specific intake passage 19 extending from the surge tank to the intake port 4 of each cylinder. The common intake passage 17 is provided with an air flow meter 21 for detecting an intake air amount and a throttle valve 22 for adjusting the intake air amount, and an idle speed control (ISC) passage 23 for bypassing the throttle valve 22 and this passage. ISC opening and closing 23
A valve 24 is provided. Further, an intake air temperature sensor 25 for detecting the intake air temperature, an idle switch 26 for detecting the full closing of the throttle valve 22, a throttle opening sensor 27 for detecting the throttle opening, and the like are provided.

An injector 28 for injecting and supplying fuel is provided near a downstream end of the cylinder-specific intake passage 19.
The injector 28 injects fuel supplied via a fuel passage by a fuel pump (not shown) toward the intake port 4. Downstream of the cylinder-specific intake passage 19, a secondary passage 19a used for lean burn operation or the like is provided, and a swirl control valve 29 is provided in the secondary passage 19a. The exhaust system of the engine is provided with an exhaust passage 31 communicating with the exhaust port 5 of each cylinder. The exhaust passage 31 is provided with a λO2 sensor 32, and a catalyst device 33 for purifying exhaust gas is provided downstream thereof. Is provided. The .lambda.O2 sensor 32 can detect an operating state at a stoichiometric air-fuel ratio.

An electronic control unit (ECU) 40 is provided for controlling the engine of this embodiment. It is composed of a microcomputer and the like. The ECU 40 includes the crank angle sensor 13, the water temperature sensor 14, an air flow meter 21, an intake air temperature sensor 25, an idle switch 26,
Signals from the throttle opening sensor 27, the λO2 sensor 32, and the like are input. The ECU 40 generates a fuel injection signal for the injector 28. Further, it generates an ignition timing control signal to the ignition circuit 9. Further, it outputs a control signal to the actuator 24a of the ISC valve 24, the actuator of the swirl control valve 29, and the like. An engine control according to one embodiment of the present invention will be described with reference to FIGS.

Referring to FIG. 2, there is shown a flowchart of a procedure for calculating the intake / intake air amount. This calculation of the intake air amount is performed in a 4 ms cycle. First, the ECU 40
When calculating the intake air amount, the signal q of the air flow sensor is read (step S1). Next, the ECU 40
Is the detected crank angle 1 based on the signal q.
At 80 °, that is, the intake air intake amount Q _(n) for the crank angle almost corresponding to the period during which the intake valve is open is calculated (step S2). Note that this calculation is performed on the assumption that q does not change. Then, the previously calculated intake air amount Q
_Is replaced with Q _1ST and the current value Q _(n) is stored as the previous value Q (step S3). That is, each time the intake / intake air amount calculation routine is executed, the value of the intake / intake air amount at a predetermined storage location is updated.

Next, an acceleration / deceleration determination routine according to one embodiment of the present invention will be described with reference to FIG. This acceleration / deceleration determination routine is executed every 180 ° crank angle (CA). The routine start timing
BTDC of the compression stroke is 360 °. ECU40
First, the intake air amount Q obtained by the above intake air amount calculation routine is read (step S11). Next,
Calculating the intake air quantity change Delta] Q _L (step S12).
In this case, intake air amount change Delta] Q _L, the value Q ₁ used as the latest intake air amount with the latest value Q and the previous acceleration determining routine calculated by the intake air quantum calculation routine (synchronizing with the engine rotation angle) Is the absolute value of the difference between Then, ECU 40 may intake air amount change Delta] Q _L is a predetermined value α
It is determined whether it is greater than (step S13). If the value is larger than the predetermined value α, the ECU 40 determines the value Q _IS of the intake air amount at the previous execution of the intake air amount calculation routine obtained in the intake air amount calculation routine sampled in a cycle shorter than the engine rotation angle synchronization timing. _T is read (step S14). Next, the ECU 40 predicts the intake air amount Qf introduced into the cylinder during the intake stroke (step S15).

The predicted intake air amount Qf is calculated based on the latest (currently executed) intake intake air amount Q (Q _(n) ) calculated by the above described intake air intake amount calculation routine and the intake air intake amount at the previous execution of the intake air intake amount calculation routine. Value Q _1ST , crankshaft rotation speed a
(The time required for the crank angle to advance by 180 °), the time from the start of fuel injection to the closing of the intake valve, the cycle crank angle c of the SGT signal (180 ° in this example), and the execution cycle d ( In this example, it is calculated using 4 ms) and the correction coefficient e. In this example, Qf is represented by the following equation. Qf = Q * RVEF where _{rvef = (Q / Q 1ST)} K K = {(a * b) / (b * d) + e} The above value Q _1, Q _1ST, the relationship between Delta] Q _L and Q for example , As shown in FIG.

That is, the acceleration determination in this embodiment is performed based on the results of a plurality of intake / intake air amount calculation routines. In FIG. 3, after calculating the predicted intake / intake air amount Qf, the acceleration determination flag F indicating that the acceleration state has been detected is set to 1 (step S16). If no acceleration determination is made in step S13, the ECU 40 sets the acceleration determination flag F to 0 (step S17). The latest intake air quantity Q to replace the previous intake air amount Q ₁ (step S18). Next, the fuel injection control will be described with reference to FIG. The fuel injection control routine of FIG. 4 is a crank angle synchronization execution control routine that is performed subsequent to the above-described acceleration determination routine.

The ECU 40 determines whether the acceleration determination flag F is 1 (step S21). When the acceleration determination flag F is 1, and the acceleration is determined, the ECU 40 employs the predicted intake air intake amount Qf calculated in the acceleration determination routine as the reference intake air amount Qa for determining the fuel injection amount ( Step S22). When the acceleration determination flag F is 0, the ECU 40 determines that the reference intake air amount Q
The value a of the latest intake / intake air amount calculated by a in the intake / intake air amount calculation routine is adopted (step S23). Next, the ECU 40
Is the operating state of the engine, for example, the engine speed N
e, a detection value such as an engine water temperature is read (step S2).
4). Then, based on the above-mentioned predicted value of the intake air amount or the reference intake air amount Qa which is the latest intake air amount, a basic fuel injection amount T _base = K · Qa / Ne (K: coefficient) is calculated (step S25). Next, the air-fuel ratio feedback correction coefficient T _CFB , the acceleration increase correction T
c and the like are set (step S26). In step S26 of the above control, the air-fuel ratio feedback control amount is increased for a predetermined period after the on / off switching of the external load. As a result, the control followability can be improved. Further, based on the port intake air temperature estimated from the intake air temperature and the engine water temperature, the intake intake air amount detected from the air flow sensor or the like is corrected. In the ignition timing control, when the air-fuel ratio is rich, knock retard is limited because the combustibility is stable. During the fuel increase and the high-load fuel increase after the start, the restriction is made in the same manner as the knock retard.

Then, a final fuel injection amount T _TOTAL is calculated (step S27). After determining whether it is the fuel injection timing (step S28), a fuel injection command is output at a predetermined timing (step S29).
In step S26 of the above control, the air-fuel ratio feedback control amount is increased for a predetermined period after the on / off switching of the external load. As a result, the control followability can be improved. According to the control of this example, when the acceleration is determined, the predicted intake air intake value is used to determine the fuel injection amount, and when the acceleration is not determined, the latest calculated intake air intake value is calculated. Since the fuel injection amount is calculated using the value, appropriate fuel injection control according to the operating state of the engine can be performed.

[0021]

As described above, in the present invention, since the engine acceleration / deceleration determination is set to the longest possible determination cycle, the engine operation state can be accurately determined even in a slow acceleration / deceleration state with a large cycle. Thus, the intake air amount can be predicted based on the accurate determination. And
Since the engine control amount such as the fuel injection amount is calculated on the basis of the value based on the prediction of the intake / intake air amount based on the accurate determination of the engine operation state, appropriate engine control can be performed. In the present invention, the acceleration / deceleration determination is set to the longest possible determination cycle. However, the acceleration / deceleration determination is determined based on the intake / intake air amount for each predetermined rotation angle of the rotating shaft, thereby opening and closing the intake valve. Accurate determination can be made without being affected by the intake pulsation generated in synchronization with the operation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a multi-cylinder engine to which the present invention can be applied;

FIG. 2 is a flowchart of an intake air intake amount calculation routine according to the engine control of the present invention;

FIG. 3 is a flowchart of an acceleration determination routine according to one embodiment of the present invention;

FIG. 4 is a flowchart of a fuel injection amount control routine according to the engine control of the present invention;

FIG. 5 is an explanatory diagram showing a relationship between calculated values of an intake air amount in the engine control of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Piston 3 Combustion chamber 4 Intake port 5 Exhaust port 6 Intake valve 7 Exhaust valve 8 Spark plug 12 Projection 13 Crank angle sensor.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshimitsu Yamaoka 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Yutaka Oizumi 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Inside the company

Claims (3)

[Claims] 1. An intake air amount detecting means for generating a signal representing an intake air amount, a first intake air amount calculating means for calculating an intake air amount of an engine at predetermined time intervals according to an output of the intake air amount detecting means. A reference intake amount predicting unit for predicting a reference intake intake amount for subsequent engine control based on the intake intake amount calculated by the first intake intake amount calculating unit; A second intake / intake air amount calculation means for calculating an intake / intake air amount of the engine every long predetermined time; and an acceleration / deceleration determination means for judging the acceleration / deceleration of the engine based on an output of the second intake / intake air amount calculation means. When the acceleration / deceleration determination means determines that the engine is not in the acceleration / deceleration state, the prediction of the reference intake air amount by the reference intake air amount prediction means is invalidated. Location. 2. The system according to claim 1, wherein said second intake / intake air amount calculating means calculates an intake / intake air amount for each predetermined rotation angle of a rotating shaft which rotates in response to engine rotation. 2. The control device for an engine according to claim 1. 3. A method for predicting the amount of intake air to be charged into a combustion chamber of a cylinder which is to be in an intake stroke after an intake amount detection means generates a signal to calculate an intake air amount by said first intake air amount calculation means. The engine control device according to claim 1 or 2, wherein the control is performed.