JP2023161700A - Internal combustion engine control apparatus - Google Patents

Abstract

To prevent or suppress an abnormal combustion caused by a fuel vapor without assuring in a failure in the operating state of an internal combustion engine.SOLUTION: An internal combustion engine control apparatus, for use in an internal combustion engine that includes a first injector for injecting fuel to an intake port that introduces an intake air into a combustion chamber and a second injector for directly injecting the fuel into the combustion chamber, controls the fuel injection by the first injector and the fuel injection by the second injector. The control apparatus includes: temperature determination means for determining whether a temperature of oil for lubricating the engine is equal to or higher than a boiling point (step S3); and injection adjustment means for increasing a fuel injection amount by the first injector and reducing a fuel injection amount by the second injector in a case where the temperature of the oil is equal to or higher than the boiling point (step S6).SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device for an internal combustion engine equipped with an injector that injects fuel, and in particular is configured to perform so-called port injection, which injects fuel into an intake port, and in-cylinder injection, which injects fuel directly into a combustion chamber. The present invention relates to a device for controlling fuel injection in an internal combustion engine.

It is conventionally known that fuel supplied to the combustion chamber of an internal combustion engine such as a gasoline engine mixes with oil adhering to the wall of a cylinder bore and is carried into the crankcase. The boiling point of the fuel mixed in the oil is lower than the boiling point of the oil, and when an internal combustion engine is operated under high load, the temperature of the oil may exceed the boiling point of the fuel. Vapors may be generated. Patent Document 1 describes an internal combustion engine configured to process this fuel vapor without causing any hindrance to operation.

A portion of the fuel sent into the combustion chamber adheres to the inner wall surface of the cylinder bore, and this, along with lubricating oil, is swept down into the oil pan (or crankcase) by the piston ring and stored in the oil pan. Fuel vapor generated inside the oil pan is sent to the intake side of the internal combustion engine by so-called purge control and is consumed as fuel. However, when the temperature of the lubricating oil becomes higher than the boiling point of the fuel, the fuel mixed in the lubricating oil evaporates all at once, so if the fuel vapor thus generated is introduced into the intake side using normal purge control, The amount of fuel in the mixture increases, making the air-fuel ratio richer than expected. Therefore, in the internal combustion engine described in Patent Document 1, purge control is prohibited or suppressed when the temperature of the lubricating oil is higher than or close to the boiling point of the fuel.

JP2008-202472A

As described in Patent Document 1, when the fuel mixed in the lubricating oil (oil) is heated to a temperature above or near the boiling point, evaporation is promoted, so the fuel in the oil pan or crankcase is heated. The amount of steam increases. The internal combustion engine described in Patent Document 1 suppresses a large amount of fuel vapor generated at one time from entering the intake air, thereby preventing or suppressing the air-fuel ratio from becoming rich. However, such control results in a large amount of fuel vapor remaining in the oil pan or crankcase. The fuel vapor is returned to the intake system and flows into the combustion chamber. In that case, if the engine is equipped with a supercharger, it will be cooled and condensed in the intercooler, and at that time, the oil component in the blow-by gas will be taken in. If the fuel containing oil droplets flows into the combustion chamber in this way, the incompletely burned oil components may become an ignition source, causing abnormal combustion in which the fuel burns before ignition in the next cycle. .

This invention has been made with a focus on the above-mentioned technical problem, and is capable of preventing or suppressing abnormal combustion caused by fuel vapor in an internal combustion engine without causing a problem in the operating state of the internal combustion engine. The purpose of this invention is to provide a control device for the following.

In order to achieve the above object, the present invention provides an internal combustion engine that includes a first injector that injects fuel into an intake port that introduces intake air into a combustion chamber, and a second injector that injects fuel directly into the combustion chamber. A control device for an internal combustion engine that controls fuel injection by the first injector and fuel injection by the second injector, the control device determining whether the temperature of oil lubricating the internal combustion engine is equal to or higher than the boiling point of the fuel. temperature determining means; and injection adjusting means for increasing the amount of fuel injected by the first injector and decreasing the amount of fuel injected by the second injector when the temperature of the oil is equal to or higher than the boiling point of the fuel. It is characterized by the fact that

In this invention, fuel is supplied by injection toward the intake port and direct injection into the combustion chamber. A portion of the fuel inevitably mixes with the oil adhering to the inner wall surface of the combustion chamber. On the other hand, if it is determined that the oil temperature determined from the oil temperature and water temperature of the internal combustion engine is higher than the boiling point of the fuel, the injection of fuel into the combustion chamber is reduced and the fuel is directed toward the intake port. Increase the injection of. Therefore, the amount of fuel that is sprayed directly onto the inner wall surface of the combustion chamber to which oil is attached is reduced, so the amount of fuel that mixes with the oil and evaporates from the oil is reduced. As a result, fuel vapor evaporated from the oil and returned to the intake system can be suppressed to prevent or suppress abnormal combustion. Furthermore, since the decrease in fuel injection into the combustion chamber is compensated for by the increase in fuel injection into the intake port, no particular problem occurs in the operation of the internal combustion engine.

FIG. 2 is a schematic diagram for explaining a blow-by gas processing system in an internal combustion engine targeted by the present invention. It is a schematic diagram when one of the cylinder heads of the internal combustion engine is viewed diagonally from above. It is a flow chart for explaining an example of control performed by a control device in an embodiment of this invention.

Next, embodiments of the invention will be described with reference to the drawings. Note that the embodiment described below is only an example of implementing the present invention, and is not intended to limit the present invention.

FIG. 1 is a schematic diagram for explaining an embodiment of the present invention, mainly showing a blow-by gas processing system. The internal combustion engine 1 shown here (hereinafter referred to as the engine 1) pumps a mixture of air and fuel sucked into a combustion chamber formed by a cylinder bore and a piston reciprocably housed inside the cylinder bore. This is a well-known reciprocating engine that outputs mechanical power by pushing back a piston using high-temperature, high-pressure gas generated by compressing the compressed gas and explosively combusting it to rotate a crankshaft.

As an example, FIG. 2 shows a part of a cylinder head of a spark ignition engine. The example shown here includes two intake valves 2 and two exhaust valves 3, and a spark plug 4 is provided almost at the top of a combustion chamber (not shown). Furthermore, an injector 5 (hereinafter referred to as the first injector 5) that injects fuel into either one of the intake ports, and an injector 6 (hereinafter referred to as the second injector) that injects fuel directly into the inside of the combustion chamber (inside the cylinder). 6) is provided. These injectors 5 and 6 are conventionally known injectors that are electrically controlled and instantaneously spray hydrocarbon liquid fuel such as gasoline, diesel oil, or alcohol. It is configured to appropriately control the injection amount depending on the injection rate and injection time.

The engine 1 also includes a supercharger 7. The supercharger 7 is a turbocharger that is driven by the exhaust gas of the engine 1 to pressurize intake air, and guides the exhaust gas from an exhaust manifold 8 to a turbine (not shown) through an exhaust pipe 9 to drive a compressor integrated with the turbine. It is configured as follows. An air cleaner 10 is connected to the intake side of the compressor, and an intercooler 11 is connected to the discharge side. The intercooler 11 is connected to an intake manifold 13 via an intake air temperature gauge 12.

Like a normal engine, the engine 1 is equipped with a crankcase breather (not shown) that discharges blow-by gas, and a PCV (positive crankcase ventilation valve) 14 is provided on the discharge side of the crankcase breather. There is. This PCV 14 is a one-way valve that opens only in the direction in which gaseous components flow out, and is used to mix gaseous components such as fuel vapor that is mixed into the oil and then boiled and separated from the oil into the intake air of the engine 1. , is provided in a conduit 15 that communicates a downstream (downstream) part of a throttle valve (not shown) with the crankcase. Therefore, the fuel vapor may pick up oil in the blow-by gas as it cools and condenses. Note that the crankcase and the suction side of the compressor are connected by piping to introduce fresh air.

Furthermore, an electronic control unit (ECU) 16 that controls the engine 1 is provided. The ECU 16 is mainly composed of a microcomputer consisting of arithmetic elements, memory, etc., and performs calculations using input data and pre-stored data, and outputs the results of the calculations as control command signals. It is configured. The ECU 16 shown in FIG. 1 has at least a function of controlling fuel injection by each of the injectors 5 and 6 described above, and for this control, at least the temperature of the oil that lubricates the engine 1 is input as data. The temperature of this oil may be the temperature of the oil inside the oil pan or the crankcase (each not shown) or the temperature of the cooling water of the engine 1. Further, it is configured to output at least a control signal for controlling the amount of fuel injected by each injector 5, 6.

That is, the ECU 16 includes a temperature determining section 16A and an injection adjusting section 16B as its functional configuration. The temperature determining unit 16A is a functional means for determining whether the temperature of the oil is equal to or higher than the boiling point of the fuel mixed in the oil. Furthermore, the temperature may not be the temperature itself detected by a predetermined sensor, but may be the temperature of oil or engine water estimated from the detected temperature. Therefore, the EUC 16 includes the boiling point of the fuel as pre-stored data.

In addition, the injection adjustment unit 16B determines the fuel injection amount according to the accelerator opening representing the required driving force and the fuel injection amount in each injector 5 and 6 necessary to output the required driving force, It is configured to output a control command signal to each injector 5, 6. Therefore, the accelerator opening degree is input to the ECU 16 as detection data from a predetermined sensor, and the fuel injection amount corresponding to the accelerator opening degree is stored in advance as data.

The control device according to the embodiment of the present invention including the ECU 16 described above prevents or suppresses mixing of fuel into oil and evaporation of fuel from oil as much as possible, and further prevents abnormal combustion from occurring. , fuel injection by each injector 5, 6 is controlled as described below. That is, when fuel is injected directly into the cylinder from the second injector 6 described above, a portion of the fuel is directly sprayed onto the inner wall surface of the cylinder bore. Oil for lubrication is attached to the inner wall surface of the cylinder bore, and the oil is scraped down by the piston ring and returned to the crankcase and oil pan. A portion of the fuel sprayed toward the inner wall surface of the cylinder bore mixes with the oil and is stored in the crankcase or oil pan. When the temperature of the oil exceeds the boiling point of the mixed fuel, the mixed fuel boils and its steam fills the crankcase and oil pan. The vapor is returned to the intake system, where it condenses and picks up oil, which can then be sent to the combustion chamber and cause abnormal combustion.

Therefore, the embodiment of the present invention is configured to execute the control shown in FIG. 3, as an example. FIG. 3 is a flowchart for explaining an example of the control, and the control shown in this routine is executed by the ECU 16 described above. First, in step S1, it is determined whether the learned value of the air-fuel ratio (A/F) is greater than or equal to a predetermined reference value. The above-mentioned ECU 16 learns the fuel injection amount in relation to engine torque, accelerator opening, etc. while the engine 1 is operating, and controls the air-fuel ratio so as to obtain the learned air-fuel ratio. It is determined whether the air-fuel ratio obtained in this way is equal to or higher than a predetermined reference value.

If a negative determination is made in step S1, the routine shown in FIG. 3 is temporarily terminated without performing any particular control. On the other hand, if a positive determination is made in step S1, it is determined whether the cumulative fuel injection amount below the fuel boiling point immediately before the current point in time is equal to or greater than a predetermined injection reference value (step S2 ). This judgment is to estimate that the amount of fuel mixed in the oil is increasing. Therefore, if a negative judgment is made in step S2, there is a problem with the amount of fuel evaporated from the oil. Since it is considered that this is not enough, the routine shown in FIG. 3 is temporarily ended without performing any particular control. Note that the functional means that executes the control in step S3 corresponds to the temperature determining means in the embodiment of the present invention.

On the other hand, if the determination in step S2 is affirmative, it is determined whether the oil temperature (oil temperature) is higher than the boiling point of the fuel and is trending upward (step S3). Here, the oil temperature may be a temperature directly detected by a sensor, or may be a temperature estimated from the engine water temperature, and in short, it may be a temperature obtained from data input to the ECU 16 described above. Further, it is possible to determine whether or not the oil temperature is on the rise based on the comparison result between the previous value and the current value of the oil temperature. If a negative determination is made in step S3, it is considered that there is a low possibility that the fuel in the oil will boil, so the routine of FIG. 3 is temporarily terminated without performing any particular control.

On the other hand, if the determination in step S3 is affirmative, the determination of the fuel evaporation time period is established (step S4). That is, the abnormal combustion avoidance mode is turned on. Next, it is determined whether the abnormal combustion avoidance mode is continuing (step S5). Immediately after the abnormal combustion avoidance mode is turned ON in step S4, an affirmative determination is made in step S5, and in that case, injection adjustment control is executed to increase the port fuel injection amount and reduce the in-cylinder direct injection amount. (Step S6). That is, the amount of fuel injected from the first injector 5 described above is increased, and the amount of fuel injected from the second injector 6 is decreased. Note that such a change in the amount of fuel injected from each injector 5, 6 is performed so that the total amount of fuel injected from each injector 5, 6 does not change before and after the change. Therefore, the functional means that executes the control in step S6 corresponds to the injection adjustment means in the embodiment of the present invention.

After this step S6, the process returns to step S4. In step S4, the time period during which the abnormal combustion avoidance mode is maintained on is controlled. That time is a predetermined time, and therefore, until the duration of the abnormal combustion avoidance mode has passed the predetermined time, an affirmative determination is made in step S5, and the port injection amount is increased and the in-cylinder The state where the amount of direct injection is reduced is maintained. If the time has elapsed and a negative determination is made in step S5, the routine shown in FIG. 3 is temporarily terminated. That is, the control of increasing the injection amount by the first injector 5 and decreasing the injection amount by the second injector 6 in the abnormal combustion avoidance mode is finished, and these injection amounts are controlled by adjusting the accelerator opening, engine speed, or exhaust purification catalyst. control based on predetermined conditions such as temperature.

Accordingly, in the control according to the embodiment of the present invention described with reference to FIG. suppressed. As mentioned above, when fuel is directly injected into the cylinder, the fuel is directly sprayed onto the inner wall surface of the cylinder bore to which oil is attached, making it easy for the fuel to mix with the oil. Since the control device according to the embodiment of the present invention suppresses in-cylinder direct injection, fuel is less likely to be mixed into oil, and therefore generation of fuel vapor is suppressed even if the temperature of the oil exceeds the boiling point of the fuel. As a result, abnormal combustion caused by fuel vapor being returned to the intake system, once condensed, and then sent to the combustion chamber can be avoided or suppressed.

Note that this invention is not limited to the embodiments described above, and can be implemented with appropriate modifications within the scope of the purpose of this invention. For example, in addition to an internal combustion engine that uses a single low-boiling point fuel, the internal combustion engine of the present invention uses a single low-boiling component fuel and at least one type of fuel that has different properties from the single low-boiling component fuel. It may be an internal combustion engine that operates alone or together with the combustion chamber. Furthermore, in the embodiment of the present invention, the above-mentioned abnormal combustion avoidance mode may be executed when the engine temperature or oil temperature is higher than the boiling point of the fuel mixed in the oil, and the temperature tends to increase. The abnormal combustion avoidance mode may be executed even when other conditions are not satisfied, such as when it is not determined.

1 Internal combustion engine (engine)
2 Intake valve 3 Exhaust valve 4 Spark plug 5 First injector 6 Second injector 7 Supercharger 8 Exhaust manifold 9 Exhaust pipe 10 Air cleaner 11 Intercooler 12 Intake air temperature gauge 13 Intake manifold 14 Positive crankcase ventilation valve (PCV)
15 Pipe line 16 Electronic control unit (ECU)
16A Temperature judgment section 16B Injection adjustment section

Claims (1)

Fuel injection by the first injector and the second injector in an internal combustion engine comprising a first injector that injects fuel into an intake port that introduces intake air into a combustion chamber, and a second injector that directly injects fuel into the combustion chamber. A control device for an internal combustion engine that controls fuel injection by
temperature determining means for determining whether the temperature of oil lubricating the internal combustion engine is equal to or higher than the boiling point of the fuel;
and injection adjusting means for increasing the amount of fuel injected by the first injector and decreasing the amount of fuel injected by the second injector when the temperature of the oil is equal to or higher than the boiling point of the fuel. A control device for an internal combustion engine.

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