JP2781878B2 - Engine control device - Google Patents

Description

The present invention relates to a control device for an internal combustion engine (engine),
In particular, the present invention relates to an engine control device that solves a problem when an intake air amount cannot be normally detected due to surging in an intake system due to deceleration in an engine having a supercharger. Conventionally, there has been proposed an engine which detects an intake air amount by an air flow sensor and performs fuel supply control or the like based on the actual intake air amount thus detected. However, when a turbocharger is attached to this type of engine, surging may occur in the engine intake system due to the relationship between the rotational inertia of the turbocharger turbine and the compressor, for example, during deceleration when the intake air amount sharply decreases. There is a problem that the output of the air flow sensor becomes abnormal, so that accurate fuel supply control or the like cannot be performed, causing a shock or stopping the engine, that is, causing a so-called engine stall. The surging is continued until the turbine rotation falls to a value corresponding to the intake air amount. As a measure against this problem, that is, when the output of the airflow sensor becomes an abnormal value in a specific operation state,
For example, in the specific operation state described above, the operating parameters are determined based on sensor outputs other than the airflow sensor (for example, the output of a load sensor such as a throttle sensor and an intake negative pressure sensor, the output of a rotation speed sensor, or a combination of these two sensor outputs). It is conceivable to estimate (for example, the intake air amount) and control the engine based on the estimated output. However, this measure has the following disadvantages. First, a relatively wide operating area (state) is set as an abnormal value occurrence area (state) so as to reliably include an operation state in which the output of the airflow sensor becomes an abnormal value. If the engine is controlled by the estimated value based on the output of the sensor, the abnormal value occurrence region (state) includes a portion where the output of the airflow sensor is normally normal. In (state), the engine control based on the estimated value causes deterioration in control accuracy. Therefore, when considering setting the abnormal value occurrence area (state) to be narrow in order to use the accurate airflow sensor output as much as possible,
(Even if this setting is correct)
In the vicinity of the set abnormal value occurrence area (state), the output of the airflow sensor may indicate an abnormal value based on subtle changes in environmental conditions, aging, individual differences, and the like. The control accuracy in the vicinity of ()) may be extremely deteriorated. Further, as the specific operation state in which the output of the airflow sensor becomes abnormal, there is a specific operation state in which a normally used operation state sensor (for example, a load sensor or a rotation speed sensor) cannot accurately detect the state (for example, When the specific operation state is an excessive operation state such as acceleration / deceleration operation). And in such a case,
Usually, the starting point of the specific operation state is captured based on some sensor output, and then the period in which the specific operation state is to be continued is measured by a timer or the like to set the specific operation state. However, even in this case, if the set period is too long, the former problem described above, that is, the problem that the estimated value is still used even though the output of the airflow sensor has already returned to normal. If a point occurs and the set period is too short, the latter problem described above, that is, engine control based on the output of the airflow sensor is performed even though the abnormal output of the airflow sensor has not been completed. Problems occur. That is, when the normal / abnormal of the airflow sensor output is determined only from the operating state of the engine, and the control based on the determination result is switched between the control based on the output of the main sensor and the engine control based on the estimated value from another sensor output. Has a limit in its control accuracy naturally. The present invention seeks to solve such a problem, and determines whether or not an output of an airflow sensor becomes an abnormal value from an actual operating state of an engine, and an actual output of the airflow sensor. To improve the accuracy of airflow sensor output normality / abnormality judgment by combining the result of comparing the airflow sensor output with the simulated output obtained from the output of other sensors and determining whether the output of the airflow sensor becomes an abnormal value. In addition, an object of the present invention is to provide an engine control device capable of performing engine control with high reliability by switching a process of taking in engine control operation parameters based on a result of the high-precision determination. For this reason, the engine control device of the present invention includes an airflow sensor that detects an actual intake air amount in an intake passage of the engine, a first control unit that controls the engine based on an output of the airflow sensor, A throttle sensor for detecting the opening of the interposed throttle valve,
Simulated intake air amount setting means for setting a simulated intake air amount based on an output of the throttle sensor; second control means for controlling an engine based on the simulated intake air amount; Deceleration state detection means for detecting that the vehicle is operating, comparison means for detecting a difference between the output of the airflow sensor and the simulated intake air amount and comparing the detected value with a predetermined value, and wherein the deceleration state detection means is in a deceleration state. And when the comparing means determines that the difference between the output of the air flow sensor and the simulated intake air amount is equal to or greater than a predetermined value, the second controlling means takes priority over the first controlling means. It is characterized by having operation control means for operating. In general, in an engine equipped with a supercharger, a detection value of an airflow sensor that detects an intake air amount or an equivalent information amount may be abnormal due to surging generated in an intake system due to deceleration or the like. However, in the engine control device of the present invention, when the engine is operated under a “deceleration operation state” in which the output of the airflow sensor may become an abnormal value, the detection value of the airflow sensor and the throttle sensor Then, it is determined whether or not the output of the airflow sensor has an abnormal value by comparing the simulation information set based on the output of the airflow sensor. If the engine is operating normally, the first control means for controlling the engine based on the output of the air flow sensor is operated. While it is possible to use the detection value of the airflow sensor with higher accuracy with respect to the air amount information for engine control, if the determination is abnormal, actuate the second control means for controlling the engine based on the throttle sensor. Accordingly, it is possible to continue the engine control while avoiding the use of the abnormality detection value of the intake air amount due to the surging for the engine control. Further, when the engine is not operating under the "deceleration operation state", the first control means for controlling the engine based on the output of the air flow sensor is operated, so that more accurate information regarding the intake air amount information can be obtained. The engine is controlled based on the high airflow sensor output. Hereinafter, an engine control device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram, FIG. 2 is a graph for explaining its operation, and FIG. 3 is an explanation of its operation. FIG. As shown in FIG. 1, an internal combustion engine E (hereinafter simply referred to as “engine E”) such as a gasoline engine mounted on a vehicle according to the present embodiment includes a turbocharger 3. The turbocharger 3 includes a turbine 4 interposed in the exhaust passage 2 of the engine E, and includes a compressor 5 interposed in the intake passage 1 of the engine E and rotationally driven by the turbine 4. In the intake passage 1 of the engine E, an air flow sensor 16, a compressor 5 of the turbocharger 3, an intercooler 8, and an electromagnetic fuel constituting a fuel supply unit as an engine controlled unit are arranged in this order from the upstream side (air cleaner side). Injection valves 9 and 10 (the injection capacities of these valves 9 and 10 are different) and a throttle valve 11 are provided, and a turbocharger 3 is provided in the exhaust passage 2 of the engine E in order from the upstream side (the engine combustion chamber side). And a muffler (not shown). The air flow sensor 16 detects the number of Karman vortices generated by the columnar body disposed in the intake passage 1 by an ultrasonic modulating means or by detecting a change in a resistance value, thereby realizing the actual intake passage 1. The digital output from the air flow sensor 16 is input to the controller 14. Note that the digital output from the airflow sensor 16 is
Inside, for example, it is applied to a 1/2 frequency divider and then subjected to various processes for fuel supply control and the like. It is generally said that the airflow sensor 16 malfunctions due to intake pulsation or the like in a low-speed and high-load state of the engine E. By appropriately adjusting, the above-described intake pulsation hardly occurred, so that the measurement reliability or accuracy of the airflow sensor 16 is considered to be sufficiently high. However, as described above, since the turbocharger is provided, there is a possibility that the airflow sensor 16 may malfunction due to surging. Further, a rotational speed sensor 17 is provided. The rotational speed sensor 17 detects the engine rotational speed N by detecting the engine rotational speed information from a primary minus terminal of the ignition coil 28, for example. Further, the opening degree of the throttle valve 11 (throttle opening degree) θ
A throttle sensor 20 for detecting the pressure is provided. A potentiometer is used as the throttle sensor 20, and its output is used as a second operation parameter by the controller.
Entered in 14. Further, an intake air temperature sensor 18 for detecting an intake air temperature, an atmospheric pressure sensor 19 for detecting an atmospheric pressure are provided, and in addition, a water temperature sensor 21 for detecting an engine cooling water temperature, and an O for detecting an oxygen concentration in exhaust gas. ₂ sensor 22, knock sensor 23 for detecting engine knock state, vehicle speed sensor 2 for detecting vehicle speed
4, Idle switch 2 for detecting engine idle state
5, a cranking switch 26 for detecting the time of engine cranking, a crank angle sensor 31 for detecting the crank angle by photoelectric conversion means with a distributor 29, and the like are provided, and signals from these sensors and switches are sent to the controller 14. Is to be entered. The intake air temperature sensor 18, the atmospheric pressure sensor 19, the water temperature sensor 2
1, a throttle sensor 20, O ₂ sensor 22, such as a knock sensor 23, the detection signal because the analog signal is input via an A / D converter to the controller 14. Further, the atmospheric pressure sensor 19 may be incorporated in the controller 14. Further, an ignition coil 28 is provided,
The ignition coil 28 includes a power transistor (switching transistor) 30 as an engine controlled part.
Thus, the primary current is interrupted. The power transistor 30 receives a signal for turning on and off from the controller 14. A display gauge 13 is provided in the vehicle interior. As the indicator 13, for example, a needle driving unit is
A needle that indicates any one of a negative pressure region, a supercharging region, and a supercharging region (the supercharging region is also referred to as a red zone) by receiving a control signal (current) from 14 and rotating the needle. A device having a formula display unit 13a or a device having a segment-type display unit 13b in which light emitting diodes (LEDs) are arranged in a row and these LEDs blink as appropriate are conceivable. Display 1
When 3 has a needle type display unit 13a, a control signal is supplied from the controller 14 to the display unit 13 via the fV converter and the current drive circuit. By the way, the controller 14 is configured with a CPU, a memory (including a map), and an appropriate input / output interface.
It has a function of a first control means M1 for outputting a first signal for engine control based on an actual intake air amount Ar (first operation parameter) to engine controlled parts such as electromagnetic fuel injection valves 9 and 10, and has the following function. When the first condition is satisfied, the first control means M1
Means for setting a simulated intake air amount As as simulated information estimated from the throttle opening θ and the engine speed N in preference to (hereinafter referred to as “simulation information setting means”, and The second control means M2 outputs a second engine control signal to the engine controlled parts such as the electromagnetic fuel injection valves 9 and 10 based on the data stored in the map of the controller 14). ing. Here, the conditions for the control by the second control means M2 are as follows: (1) A predetermined deceleration state, that is, a closing speed of the throttle valve 11
| dθ / dt | exceeds a predetermined limit value (predetermined value). (2) The actual intake air amount Ar / simulated intake air amount As (this Ar / As is referred to as a malfunction rate ε) is a predetermined limit value (predetermined value). (3) The difference between the actual intake air amount Ar and the simulated intake air amount As exceeds a predetermined limit value (predetermined value). Then, when any of the conditions (1) and (2) or the conditions (1) and (3) is satisfied, the condition for shifting to the control by the second control means M2 is set. Here, the above (1) corresponds to the operating state detecting means for detecting whether the engine is operating in a specific operating state in which the output of the air flow sensor 16 indicates an abnormal value, and (2) and (3) correspond to the air flow. This corresponds to a comparison unit that compares the output of the sensor with the simulation information. The control using the intake air amount data includes, in addition to fuel supply control, control for ignition timing control, display of intake passage pressure, and EGR control when the engine E has an exhaust gas recirculation (EGR) system. Or this engine E
2 is a combined intake type engine (CIS engine)
Controls related to the engine load (boost), such as valve operation stop control for the next intake valve and the like, can be considered. With the above-described configuration, for example, as shown by the line (a) in FIG. 2, when the closing speed of the throttle valve 11 is reduced beyond a predetermined limit value, surging occurs in the intake system. As shown in the curve (b) of FIG.
2 (limit value), the control is switched from the control based on the intake air amount (actual intake air amount) data based on the output of the airflow sensor to the control based on the simulated intake air amount data, as shown in the column (c) of FIG. . The flow of the process for switching from the control based on the actual intake air amount to the control based on the simulated intake air amount as described above is as shown in steps A1 to A5 in FIG. Further, the above-mentioned deceleration state disappears, and the malfunction rate ε becomes ε2
When ε1 is smaller than ε1 (this ε1 is a limit value for canceling control based on the simulated intake air amount) and this state continues for a predetermined time t0 or more, control is switched again to the actual intake air amount. As described above, in the case of the process of switching from the control based on the simulated intake air amount to the control based on the actual intake air amount, a determination as to whether or not a predetermined time has elapsed before the process of step A5 is inserted in the process illustrated in FIG. And YE
If S, the process of step A5 is performed, and if NO, the process of step A4 is performed. Note that ε0 in FIG. 2 (b) indicates a normal state of the air flow sensor 16. Thus, according to this embodiment, the airflow sensor
When the output from 16 becomes abnormal, all the controls that have been relying on the actual intake air amount data are replaced with the simulated intake air amount data. Only after the change, the subsequent processing can use the logic when the air flow sensor 16 is normal,
As a result, even if surging occurs in the engine E, the same control as the normal operation of the air flow sensor 16 can be performed, and the effect that the engine control is not disturbed even when such surging occurs can be obtained. When performing control based on the actual intake air amount, data obtained by correcting the intake air amount with the intake air temperature, the atmospheric pressure, or the like is used, but this correction is not always necessary. Further, when the fuel injection is performed in synchronization with the pulse of the output of the air flow sensor, the fuel injection is first switched to the rotation synchronous injection when performing the control based on the simulated intake air amount, and the injection pulse width is determined by the simulated intake air amount. It is assumed that various corrections determined from the simulated intake air amount data and other various data are further added to the pulse width. Further, ignition timing control and intake passage pressure display are also performed based on the actual intake air amount or the simulated intake air amount according to the engine operating state. In step A3 of FIG. 3, it may be determined whether or not the difference between the actual intake air amount and the simulated intake air amount has exceeded a predetermined limit value. Therefore, in this embodiment, even when the air flow sensor 16 is disconnected and fails, the above-described difference exceeds a predetermined limit value. Therefore, even when the air flow sensor 16 fails, control based on the simulated intake air amount is performed. Thus, the reliability of engine control can be improved. If the control zone based on the simulated intake air amount is limited to, for example, a low load region, a simulated intake air amount determined by only the throttle opening information (this data is also stored in a map) can be used. The reference numeral 6 in FIG.
Is a two-diaphragm pressure responsive device for opening and closing the wastegate valve 6, an actuator 12 such as a DC motor for rotating the throttle valve 11 via a rod or the like during idling, and a pressure responsive device 15 (A valve 15 has a return spring (not shown) for a valve body) for controlling the valve. As described in detail above, according to the engine control device of the present invention, the following effects and advantages can be obtained. (1) The engine is operated under a specific operation state in which the detection output of the airflow sensor that detects the intake air amount of the engine having the turbocharger or the equivalent information amount may become an abnormal value. Sometimes, the output of the airflow sensor is compared with the simulation value set based on the output of the throttle sensor that detects the opening of the throttle valve provided in the intake passage of the engine. It is determined whether or not the value is abnormal, and if the value is normal, engine control is performed based on the output of the air flow sensor. That is, even if the engine is in the specific operation state, the engine control can be performed based on the detection value of the airflow sensor with higher accuracy with respect to the intake air amount information as long as the detection value of the airflow sensor is normal. (2) In the above (1), when the output value of the air flow sensor is abnormal, the engine control based on the output of the throttle sensor is performed, thereby detecting the abnormality of the intake air amount due to surging generated in the intake system of the engine. It is possible to continue the engine control while avoiding the value being used for the engine control. (3) When the engine is not operating under the specific operation mode, engine control is performed based on the output of the air flow sensor, so that the intake air amount information is based on the air flow sensor output with higher accuracy. Engine control. (4) Since the operating parameters for engine control can always be obtained with high accuracy, engine control without disturbance can be achieved.
As a result, engine control resistant to disturbance can be realized, and as a result, the reliability of engine control can be greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an engine control apparatus according to an embodiment of the present invention. FIG. 1 is an overall configuration diagram, FIG. 2 is a graph for explaining its operation, and FIG. Is a flowchart for explaining the operation. DESCRIPTION OF SYMBOLS 1 ... Intake passage, 2 ... Exhaust passage, 3 ... Turbocharger, 4 ... Turbine, 5 ... Compressor, 6 ... Wastegate valve, 7 ... Pressure response device, 8 ... Intercooler, 9,10 … Electromagnetic fuel injection valve, 11… Throttle valve, 12 …… Actuator, 13 …… Display gauge, 13a ……
Needle display unit, 13b Segment display unit, 14 Controller, 15 Solenoid switching valve, 16 Airflow sensor, 17 Rotation speed sensor, 18 Intake temperature sensor, 19
Atmospheric pressure sensor, 20 ...... throttle sensor, 21 ...... water temperature sensor, 22 ...... O ₂ sensor, 23 ...... knock sensor, 24 ...... vehicle speed sensor, 25 ...... idle switch, 26 ...... cranking switch, 27 ... ... Catalyst converter, 28 ... Ignition coil, 29 ... Distributor, 30 ... Power transistor, 31 ... Crank angle sensor, E ... Engine, M1 ... First control means, M2 ... Second control means.

Claims (1)

(57) [Claims] An air flow sensor that detects an actual intake air amount in an intake passage of the engine; first control means that controls the engine based on an output of the air flow sensor; and an opening degree of a throttle valve interposed in the intake passage is detected. A simulated intake air amount setting means for setting a simulated intake air amount based on an output of the throttle sensor; and a second control unit for controlling an engine based on the simulated intake air amount.
A deceleration state detection means for detecting that the engine is operating under a deceleration state; a deviation between the output of the airflow sensor and the simulated intake air amount detected and compared with a predetermined value The comparing means, and the deceleration state detecting means detects a deceleration state, and when the comparing means determines that either the output of the airflow sensor or the simulated intake air amount is greater than or equal to a predetermined value, the first An engine control device comprising: an operation control unit that operates the second control unit prior to the control unit.