JP2021134694A - Control device of internal combustion engine - Google Patents

Abstract

To avoid a start-up failure or an engine stall caused by not carrying out an ignition with fuel being injected into a cylinder in a previous cycle.SOLUTION: A control device of an internal combustion engine is configured such that, when fuel is injected into a cylinder of an internal combustion engine and then an ignition is not carried out in the cylinder in the same cycle for combusting the fuel, a fuel injection amount into the cylinder in a following cycle is corrected to be reduced compared to the case in which the ignition is carried out, or a fuel injection is halted.SELECTED DRAWING: Figure 2

Description

The present invention relates to a control device for controlling an internal combustion engine mounted on a vehicle or the like.

In a 4-stroke internal combustion engine having a plurality of cylinders, it is necessary to know which stroke each cylinder is currently in and to perform fuel injection control and ignition control.

The crankshaft, which is the output shaft of the internal combustion engine, is provided with a crank angle sensor for detecting the rotation angle and the engine rotation speed. The crank angle sensor senses the rotation of the rotor fixed to the crankshaft, for example, every 10 ° CA (crank angle).

A cam angle sensor is also attached to the camshaft that rotates according to the crankshaft and opens and closes the intake valve or exhaust valve of each cylinder. The cam angle sensor senses the rotation of the rotor fixed to the camshaft.

The ECU (Electronic Control Unit) that controls the operation of the internal combustion engine grasps the stroke of each cylinder by referring to the output signal (N signal) of the crank angle sensor and the output signal (G signal) of the cam angle sensor. The fuel injection timing and the ignition timing in the above are determined (see, for example, the following patent documents).

Japanese Unexamined Patent Publication No. 2016-183661

By the way, although it is rare, the transmission line between the crank angle sensor and the ECU is about to be disconnected, noise is mixed in the signal, or the rotation speed drops during cranking of the internal combustion engine. The ECU may temporarily be unable to receive the crank angle signal, making it impossible to grasp the stroke of each cylinder. Of course, if the crank angle signal can be properly received again, the current stroke of each cylinder can be known, and the fuel injection control and the ignition control can be restarted.

However, if the reception of the crank angle signal is temporarily interrupted immediately after the fuel is injected into the cylinder, the proper ignition timing cannot be determined, so that the ignition for burning the fuel cannot be performed in the same cycle of the cylinder. After that, when the crank angle signal can be received again, the fuel is injected again in the next cycle, but the unburned fuel component injected in the previous cycle remains in the cylinder. When this is combined with the fuel injected in the next cycle, the air-fuel ratio becomes excessively rich in the cylinder, and there is a concern that the fuel will not ignite and burn normally even if ignition is performed. This causes a start failure during cranking of the internal combustion engine and an engine stall after the start.

The present invention has been made by paying attention to the above problems, and is intended to avoid a start failure or engine stall of an internal combustion engine due to failure to execute ignition while injecting fuel in the previous cycle. Is the purpose of.

In the present invention, after injecting fuel into a cylinder of an internal combustion engine, when the ignition for burning the fuel is not performed in the same cycle of the cylinder, as compared with the case where the fuel is not injected, the next cylinder of the cylinder is next. A control device for an internal combustion engine was configured to reduce or correct the fuel injection amount in the cycle or to suspend the fuel injection.

According to the present invention, it is possible to avoid a start failure of the internal combustion engine or an engine stall due to failure to execute ignition while injecting fuel in the previous cycle.

The figure which shows the schematic structure of the internal combustion engine for a vehicle and the control device in one Embodiment of this invention. The flow chart which shows the procedure example of the process executed by the control device of the internal combustion engine of the same embodiment.

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of an internal combustion engine for a vehicle according to the present embodiment. The internal combustion engine of the present embodiment is a port injection type 4-stroke spark ignition engine, and includes a plurality of cylinders 1 (for example, three cylinders, one of which is illustrated in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel into the cylinder 1 is provided for each cylinder 1. Further, a spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives an induction voltage generated by the ignition coil to induce a spark discharge between the center electrode and the ground electrode. The ignition coil is integrally built in the coil case together with the igniter which is a semiconductor switching element.

The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. An air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream on the intake passage 3.

The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 to the outside from the exhaust port of each cylinder 1. An exhaust manifold 42 and a three-way catalyst 41 for purifying exhaust gas are arranged on the exhaust passage 4.

The exhaust gas recirculation device 2 opens and closes the external EGR passage 21 that connects the exhaust passage 4 and the intake passage 3, the EGR cooler 22 provided on the EGR passage 21, and the EGR passage 21 to open and close the EGR passage 21. The element is an EGR valve 23 that controls the flow rate of EGR gas flowing through the passage 21. The inlet of the EGR passage 21 is connected to a predetermined position downstream of the catalyst 41 in the exhaust passage 4. The outlet of the EGR passage 21 is connected to a predetermined position downstream of the throttle valve 32 in the intake passage 3, particularly a surge tank 33.

The ECU 0, which is a control device for the internal combustion engine of the present embodiment, is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like. The ECU 0 may be a plurality of ECUs or controllers connected to each other so as to be able to communicate with each other via a telecommunication line such as CAN (Control Area Network).

The input interface of ECU0 is a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal output from an engine rotation sensor that detects the rotation angle of the crank shaft of the internal combustion engine and the engine rotation speed ( N signal b, accelerator opening signal c output from a sensor that detects the accelerator pedal depression amount or throttle valve 32 opening as accelerator opening (so to speak, required engine load factor or engine torque), brake pedal The brake depression signal d output from the sensor that detects the depression amount, the intake temperature in the intake passage 3 (particularly the surge tank 33) connected to the cylinder 1, and the intake temperature output from the temperature / pressure sensor that detects the intake pressure. -Cam angle sensor with multiple cam angles of the intake pressure signal e, the cooling water temperature signal f output from the water temperature sensor that detects the temperature of the cooling water (or coolant) of the internal combustion engine, and the intake cam shaft or the exhaust cam shaft. The cam angle signal (G signal) g output from, the shift position signal h output from the switch for detecting the position of the shift lever, and the like are input.

From the output interface, the ignition signal i is output to the igniter 13, the fuel injection signal j is output to the injector 11, the opening operation signal k is output to the throttle valve 32, the opening operation signal l is output to the EGR valve 23, and the like. do.

The processor of ECU 0 interprets and executes a program stored in the memory in advance, calculates an operation parameter, and controls the operation of the internal combustion engine. The ECU 0 acquires various information a, b, c, d, e, f, g, h necessary for the operation control of the internal combustion engine via the input interface, obtains the engine speed, and is sucked into the cylinder 1. Estimate the amount of air. Then, the required fuel injection amount, fuel injection timing (including the number of fuel injections for one combustion), fuel injection pressure, ignition timing (including the number of spark ignitions for one combustion), and required EGR corresponding to the intake air amount. Various operating parameters such as rate (or EGR gas amount) are determined. The ECU 0 applies various control signals i, j, k, l corresponding to the operation parameters via the output interface.

Further, the ECU 0 is controlled by an electric motor (starter motor (starter motor), ISG (Integrated Starter Generator), etc.) when the internal combustion engine is started (it may be a cold start or a return from idling stop). A signal o is input, and cranking is performed in which the crankshaft is rotationally driven by the motor. Cranking ends when the internal combustion engine goes from the initial explosion to the continuous explosion and the engine speed exceeds the judgment value determined according to the cooling water temperature of the internal combustion engine, etc., assuming that the complete explosion, that is, the start is completed. ..

Normally, the ECU 0 receives the crank angle signal b and the cam angle signal g, and grasps the current process of each cylinder 1 with reference to these signals b and g. Then, fuel is injected into each cylinder 1 at an appropriate fuel injection timing, and spark ignition of the air-fuel mixture is performed at an appropriate ignition timing. In a 4-stroke engine, a series of intake stroke-compression stroke-expansion stroke-exhaust stroke is one cycle, and fuel is injected from the injector 11 into the cylinder 1 at the end of the exhaust stroke or the beginning of the intake stroke of the cylinder 1. , The ignition by the spark plug 12 installed in the cylinder 1 is executed at the end of the compression stroke or the beginning of the expansion stroke of the same cycle.

However, if the reception of the crank angle signal b is temporarily interrupted immediately after the fuel is injected into the cylinder 1, the appropriate ignition timing in the cylinder 1 cannot be determined, and the fuel is burned in the same cycle of the cylinder 1. Cannot ignite. After that, when the crank angle signal b can be received again, the fuel is injected again in the next cycle of the cylinder 1, but the unburned fuel component injected in the previous cycle remains in the cylinder 1. doing. When this is combined with the fuel injected in the next cycle, the air-fuel ratio becomes excessively rich in the cylinder 1, and there is a concern that the fuel will not ignite and burn normally even if ignition is performed.

Therefore, as shown in FIG. 2, the ECU 0 of the present embodiment injects fuel into the cylinder 1 of the internal combustion engine (step S1), and then in the same cycle of the cylinder 1 due to the interruption of reception of the crank angle signal b. If ignition is not performed (step S2), the crank angle signal b can be received by the time the next cycle of the cylinder 1 arrives, and fuel injection and spark ignition become possible in the next cycle. (Step S3), the fuel injection amount in the next cycle is corrected to be less than normal, or the fuel injection in the next cycle is paused (step S4), and then spark ignition in the next cycle is executed (step S3). S5), the fuel is burned in the cylinder 1.

Supplementary information will be given regarding the reduction correction of the fuel injection amount referred to in step S4. If you are cranking to start the internal combustion engine,
Weight loss corrected fuel injection amount etast = basic injection amount etastb x correction coefficient t_knest x weight loss correction coefficient α
And. The correction coefficient t_knest is determined according to the engine speed at that time. As a general rule, the lower the engine speed during cranking, the smaller the amount of air taken into the cylinder 1. Therefore, the correction coefficient t_knest to be multiplied by the basic injection amount etastb is reduced, thereby reducing the fuel injection amount at start time. To lose more weight.

The weight loss correction coefficient α is determined according to the cooling water temperature suggesting the temperature of the internal combustion engine at that time. The higher the temperature of the internal combustion engine during cranking, that is, the higher the cooling water temperature, the smaller the friction loss of the internal combustion engine and the more stable the combustion of the air-fuel mixture in the combustion chamber of the cylinder 1. The coefficient α is made smaller, so that the starting fuel injection amount internal is further reduced.

If the start of the internal combustion engine has already been completed
Weight loss corrected fuel injection amount etauout = basic injection amount etaub × correction coefficient ekcil_ekcy × weight loss correction coefficient β
And. The correction coefficient ekcil_ekcy is determined according to the engine speed and the accelerator opening (engine load factor) at that time. As a general rule, the lower the engine speed and the smaller the accelerator opening, the smaller the amount of air sucked into the cylinder 1. Therefore, the correction coefficient ekcil_ekcy to be multiplied by the basic injection amount etaub is reduced, and thus the injection is performed after the start. The amount of airout is further reduced.

The weight loss correction coefficient β is determined according to the cooling water temperature of the internal combustion engine at that time. The higher the cooling water temperature of the internal combustion engine, the smaller the friction loss of the internal combustion engine and the more stable the combustion of the air-fuel mixture in the combustion chamber of the cylinder 1. Therefore, the reduction correction coefficient β multiplied by the basic injection amount etaub is reduced. Therefore, the injection amount internal combustion is further reduced after the start.

In the present embodiment, after the fuel is injected into the cylinder 1 of the internal combustion engine, when the ignition for burning the fuel is not performed in the same cycle of the cylinder 1, the cylinder 1 is compared with the case where the fuel is not ignited. The control device 0 of the internal combustion engine that reduces or corrects the fuel injection amount in the next cycle of the fuel injection or suspends the fuel injection is configured. According to the present embodiment, it is possible to appropriately avoid a start failure of the internal combustion engine or an engine stall due to failure to execute ignition while injecting fuel in the cycle ahead of the cylinder 1.

The present invention is not limited to the embodiments described in detail above. The specific configuration of each part, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

The present invention can be used for controlling an internal combustion engine mounted on a vehicle or the like.

0 ... Control device (ECU)
1 ... Cylinder 11 ... Injector 12 ... Spark plug b ... Crank angle signal c ... Accelerator opening signal f ... Cooling water temperature signal g ... Cam angle signal i ... Ignition signal j ... Fuel injection signal

Claims (1)

When fuel is injected into a cylinder of an internal combustion engine and then ignition for burning fuel is not performed in the same cycle of the cylinder, fuel injection in the next cycle of the cylinder is compared with the case where fuel is not injected. A control device for an internal combustion engine that reduces the amount or suspends fuel injection.

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