JP6844237B2 - Internal combustion engine control device - Google Patents

Description

The present invention relates to a control device for an internal combustion engine.

Conventionally, as a combustion form of an internal combustion engine such as a gasoline engine, SI (Spark Ignition) combustion in which an air-fuel mixture is forcibly ignited by a spark discharge from a spark plug has been widely and generally used. In recent years, the development of a gasoline engine that utilizes premixed compression self-ignition combustion in which a high-temperature burned gas is introduced into a cylinder to self-ignite the air-fuel mixture as a combustion mode has been promoted. Here, the premixed compression self-ignition combustion is referred to as HCCI (Homogeneous Charge Compression Ignition) combustion.

According to Patent Document 1, by opening the exhaust valve from immediately before the intake valve opening period to the intake valve opening period, a large air flow is generated in the combustion chamber, the mixing of the air-fuel mixture is improved, and the mixture is stable. It is disclosed that the air-fuel mixture is self-ignited.

Japanese Unexamined Patent Publication No. 2005-201127

However, in such a compression self-ignition internal combustion engine, as a result of the promotion of mixing of the air-fuel mixture, when the load increases and the amount of fuel increases, the air-fuel mixture in the entire cylinder ignites at the same time and burns due to steep combustion. There was a problem that noise was generated. Further, when steep combustion occurs, there is a problem that an excessive load is applied to the internal combustion engine.

Therefore, an object of the present invention is to provide a control device for an internal combustion engine capable of preventing steep combustion even if the amount of fuel is increased in order to perform high-load HCCI operation.

In order to solve the above problems, the present invention is a control device for an internal combustion engine provided with a plurality of intake valves and exhaust valves per cylinder and combusts the air-fuel mixture in the combustion chamber by compression self-ignition, during the exhaust stroke. A control unit for opening a part of the intake valves among the plurality of intake valves and opening all of the plurality of intake valves in the next intake stroke is provided , and the control unit is of the internal combustion engine. The function of controlling the combustion period due to the compression self-ignition according to the required load, and the required combustion start time from the required load of the internal combustion engine when the operating region is a high load region among the combustion regions due to the compression self-ignition. When the required high-temperature cylinder temperature is calculated from the required combustion end time, the required high-temperature cylinder temperature is obtained, the opening period of a part of the intake valve during the exhaust stroke is changed, and the required high-temperature cylinder temperature is high. The function of controlling to increase the opening period of the intake single valve, which is the period for opening one of the intake valves during the exhaust stroke, and the required low temperature in-cylinder temperature obtained from the required combustion end time, and the intake valve during the intake stroke. to change the closing timing, when the request cold cylinder temperature is low, a shall and a function of controlling so as to retard the intake valve closing timing in the intake stroke.

As described above, according to the present invention, steep combustion can be prevented even if the amount of fuel is increased in order to perform high-load HCCI operation.

FIG. 1 is a block diagram of a main part of a control device for an internal combustion engine according to an embodiment of the present invention. FIG. 2 is a view of the internal combustion engine of the internal combustion engine control device according to the embodiment of the present invention as viewed from above the cylinder. FIG. 3 is a diagram showing an operating region of a control device for an internal combustion engine according to an embodiment of the present invention. FIG. 4 is a diagram showing an example of a map for obtaining a required combustion period of a control device for an internal combustion engine according to an embodiment of the present invention. FIG. 5 is a diagram showing an example of a map for obtaining a required combustion ratio 50% position of a control device for an internal combustion engine according to an embodiment of the present invention. FIG. 6 is a diagram showing an example of a map for obtaining the required high temperature in-cylinder temperature and the required low-temperature in-cylinder temperature of the control device of the internal combustion engine according to the embodiment of the present invention. FIG. 7 is a diagram showing an example of a map for obtaining the intake valve closing timing during the intake stroke of the control device of the internal combustion engine according to the embodiment of the present invention. FIG. 8 is a diagram showing an example of a map for obtaining the intake valve closing timing during the exhaust stroke of the control device of the internal combustion engine according to the embodiment of the present invention. FIG. 9 is a diagram showing an example of an opening period of the intake single valve during the exhaust stroke of the control device of the internal combustion engine according to the embodiment of the present invention. FIG. 10 is a flowchart showing a procedure of intake single valve opening control processing of the control device of the internal combustion engine according to the embodiment of the present invention.

The control device for an internal combustion engine according to an embodiment of the present invention is a control device for an internal combustion engine that includes a plurality of intake valves and exhaust valves per cylinder and burns an air-fuel mixture in a combustion chamber by compression self-ignition. Therefore, it is configured to include a control unit for opening a part of the intake valves among the plurality of intake valves during the exhaust stroke and opening all of the plurality of intake valves in the next intake stroke.

As a result, steep combustion can be prevented even if the amount of fuel is increased in order to perform high-load HCCI operation.

Hereinafter, the control device for the internal combustion engine according to the embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, a vehicle 1 equipped with an internal combustion engine control device according to an embodiment of the present invention includes an internal combustion engine type engine 2 and an ECU (Electronic Control Unit) 3 as a control unit. ..

The engine 2 includes a cylinder block 4 and a cylinder head 5 fastened to the upper portion of the cylinder block 4. A cylinder 4a is formed in the cylinder block 4, and a piston 6 capable of reciprocating up and down is housed inside the cylinder (hereinafter referred to as "inside the cylinder").

A combustion chamber 7 is provided above the cylinder 4a. The combustion chamber 7 is defined by the top surface of the piston 6 and the bottom surface of the cylinder head 5. The engine 2 is a so-called four-cycle gasoline engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston 6 reciprocates twice in the cylinder.

The piston 6 is connected to a crankshaft (not shown) via a connecting rod 8. The connecting rod 8 converts the reciprocating motion of the piston 6 into the rotational motion of the crankshaft.

The cylinder head 5 is provided with a spark plug 50. The spark plug 50 is arranged in the cylinder head 5 with the electrodes protruding into the combustion chamber 7, and the ignition timing is adjusted by the ECU 3.

As shown in FIG. 2, the cylinder head 5 has two intake ports 51a and 51b (indicated by reference numeral "51" in FIG. 1), two exhaust ports 52a, and an exhaust port 52b (in FIG. 1). Reference numeral "52") is provided. FIG. 2 is a top view of the cylinder 4a of the engine 2.

The intake port 51a and the intake port 51b merge and are connected to the intake manifold 13 (see FIG. 1). The intake port 51a and the intake port 51b communicate with the combustion chamber 7 (see FIG. 1) and the intake passage 16a (see FIG. 1) described later.

The intake port 51a and the intake port 51b are provided with an intake valve 11a and an intake valve 11b (indicated by reference numeral "11" in FIG. 1, respectively). The intake valve 11a and the intake valve 11b are opened and closed to communicate or shut off the intake passage 16a and the combustion chamber 7. The intake valve 11a and the intake valve 11b are opened and closed by the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b (indicated by reference numeral "12" in FIG. 1, respectively).

As the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b, for example, an electromagnetic variable valve mechanism that opens and closes the intake valve 11a and the intake valve 11b by an electromagnetic actuator composed of an electromagnet, a spring, or the like is used. be able to. Specifically, the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b are always closed by a spring by attracting the movable parts fixed to the intake valve 11a and the intake valve 11b by the excitation of the electromagnet. The intake valve 11a and the intake valve 11b that are urged in the direction are moved in the valve opening direction.

Further, the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b are electrically connected to the ECU 3 described later, and the excitation and non-excitation of the electromagnet are controlled by the ECU 3. Therefore, the ECU 3 can arbitrarily change the opening / closing timing of each of the intake valve 11a and the intake valve 11b, whereby the valve opening periods of the intake valve 11a and the intake valve 11b can be easily adjusted independently.

As the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b, if the intake valve 11a and the intake valve 11b can be controlled independently, a hydraulic actuator is used instead of the electromagnetic actuator. The variable valve mechanism of the above may be used. Further, as the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b, a mechanical variable valve mechanism capable of changing the opening / closing timing of the intake valve 11 by using cam members such as a main cam and a sub cam is used. It doesn't matter.

Further, the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b have a configuration in which the lift amount can be continuously changed with the opening / closing timing by adjusting the exciting current for the electromagnet, for example, by the ECU 3. It may be.

Injectors 10a and 10b (indicated by reference numeral "10" in FIG. 1) are provided in the vicinity of the intake valve 11a and the intake valve 11b of the intake port 51a and the intake port 51b, respectively. The injector 10a and the injector 10b inject fuel supplied by a fuel pump from a fuel tank (not shown) into the intake port 51a and the intake port 51b, respectively.

Between the confluence of the intake port 51a and the intake port 51b and the intake valve 11a and the intake valve 11b, an intake temperature sensor 43a and an intake temperature sensor 43b that detect the intake temperature of each of the intake port 51a and the intake port 51b (FIG. 1). , The reference numeral “43” is provided.

The cylinder head 5 is provided with an in-cylinder pressure sensor 49. The in-cylinder pressure sensor 49 detects the in-cylinder pressure, which is the internal pressure of the cylinder 4a.

In FIG. 1, the fuel injected into the intake port 51 is mixed with intake air, that is, fresh air to form an air-fuel mixture, which is introduced into the combustion chamber 7. The air-fuel mixture introduced into the combustion chamber 7 is burned and exploded by spark discharge by the spark plug 50 or self-ignition by compression in the combustion chamber. Due to the combustion and explosion of this air-fuel mixture, the piston 6 reciprocates in the cylinder 4a, and the crankshaft rotates.

A surge tank 14 is provided on the upstream side of the intake manifold 13 in the intake direction in which the intake air flows. The surge tank 14 is provided with an intake pressure sensor 15 that detects the intake pressure.

An intake pipe 16 is connected to the upstream side of the surge tank 14 in the intake direction. Inside the intake pipe 16, an intake passage 16a communicating with the intake port 51a and the intake port 51b is formed. The intake passage 16a is provided with a compressor 17 for compressing air, an intercooler 18 for cooling the compressed air, and a throttle valve 19 for adjusting the flow rate of air in this order from the upstream in the intake direction.

The throttle valve 19 adjusts the intake air amount of the engine 2 by controlling the throttle opening degree in response to a command signal from the ECU 3. The throttle valve 19 is provided with a throttle opening sensor 41 for detecting the throttle opening.

A supercharging pressure sensor 42 for detecting the supercharging pressure by the supercharger 9, which will be described later, is provided on the upstream side of the throttle valve 19 in the intake direction.

On the other hand, in FIG. 2, the exhaust port 52a and the exhaust port 52b are provided with an exhaust valve 21a and an exhaust valve 21b (indicated by reference numeral "21" in FIG. 1, respectively). The exhaust valve 21a and the exhaust valve 21b are opened and closed to communicate or shut off the exhaust passage 23a (see FIG. 1) and the combustion chamber 7 (see FIG. 1), which will be described later. The exhaust valve 21a and the exhaust valve 21b are opened and closed by the exhaust side variable valve mechanism 22a and the exhaust side variable valve mechanism 22b (indicated by reference numeral "22" in FIG. 1).

Since the exhaust side variable valve mechanism 22a and the exhaust side variable valve mechanism 22b have the same configuration as the intake side variable valve mechanism 12a and the intake side variable valve mechanism 12b described above, detailed description thereof will be omitted. In the exhaust side variable valve mechanism 22a and the exhaust side variable valve mechanism 22b, the opening / closing timing of the exhaust valve 21a and the exhaust valve 21b is arbitrarily changed by controlling the excitation and non-excitation of the electromagnet by the ECU 3. Therefore, the ECU 3 can easily adjust the valve opening period of the exhaust valve 21a and the exhaust valve 21b.

In FIG. 1, an exhaust pipe 23 is connected to the exhaust port 52 side of the cylinder head 5. Inside the exhaust pipe 23, an exhaust passage 23a communicating with the exhaust port 52 is formed. The exhaust passage 23a is provided with an exhaust turbine 24 driven by an exhaust flow, a catalyst (not shown) for purifying the exhaust, and a muffler (not shown) for silencing.

The exhaust turbine 24 is connected to the compressor 17. The power of the exhaust turbine 24 driven by the exhaust flow is used as the power for the compressor 17 to compress the air. The compressor 17 and the exhaust turbine 24 constitute a supercharger 9.

A bypass passage 25 is provided between the upstream side and the downstream side in the exhaust direction in which the exhaust gas of the exhaust pipe 23 flows across the exhaust turbine 24. The bypass passage 25 is provided with a wastegate valve 26 capable of adjusting the exhaust flow to the exhaust turbine 24. The wastegate valve 26 can control the supercharging pressure, which is the pressure of the intake air obtained by supercharging the supercharger 9, by adjusting the exhaust flow to the exhaust turbine 24. The wastegate valve 26 is composed of, for example, an electromagnetic valve, and is controlled to open and close by the ECU 3. The boost pressure may be controlled by using a variable nozzle turbo whose boost pressure can be changed.

The ECU 3 is composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an input port, and an output port.

The ROM of the computer unit stores various control constants, various maps, and the like, as well as a program for making the computer unit function as an ECU 3. That is, when the CPU executes the program stored in the ROM, the computer unit functions as the ECU 3.

In addition to the above-mentioned intake pressure sensor 15, throttle opening sensor 41, boost pressure sensor 42, intake temperature sensor 43a, intake temperature sensor 43b, and in-cylinder pressure sensor 49, the input port of the ECU 3 includes an air flow meter 44 and a crank angle. Various sensors such as a sensor 45, an exhaust pressure sensor 46, an exhaust temperature sensor 47, and an accelerator opening sensor 48 are connected.

The air flow meter 44 detects the intake air amount. The crank angle sensor 45 outputs a rectangular crank angle signal for each predetermined crank angle as the engine 2 rotates. The ECU 3 calculates the engine speed, which is the engine speed of the engine 2, based on the crank angle signal.

The exhaust pressure sensor 46 detects the exhaust pressure. The exhaust temperature sensor 47 detects the temperature of the exhaust gas. The accelerator opening sensor 48 detects the amount of depression of the accelerator pedal (not shown) by the driver as the accelerator opening.

On the other hand, the output port of the ECU 3 includes the above-mentioned injector 10a, injector 10b, intake side variable valve mechanism 12a, intake side variable valve mechanism 12b, throttle valve 19, and exhaust side variable valve mechanism 22a. , Exhaust side variable valve mechanism 22b, wastegate valve 26, and various control objects including a spark plug 50 are connected.

The ECU 3 switches between SI combustion and HCCI combustion according to the operating state of the engine 2. Specifically, the ECU 3 sets the operating region of the engine 2 to either the SI operating region or the HCCI operating region by referring to the operating region map as shown in FIG. 3 in which the engine speed and the required engine load are parameters. It is determined whether or not there is, and based on this determination, SI combustion or HCCI combustion is selected.

The ECU 3 calculates the engine required load based on the accelerator opening degree and the like input from the accelerator opening degree sensor 48.

The ECU 3 controls the intake single valve opening to open one of the intake valve 11a and the intake valve 11b during the exhaust stroke when the operating region obtained by obtaining the engine speed and the required engine load as parameters is within the high load HCCI operating region. To do. The high load HCCI operating region is a region in which the engine required load is high in the HCCI operating region. For example, the engine required load in the HCCI operating region is 70% or more of the engine required load of the entire HCCI operating region.

The intake port 51 that opens the intake valve during the exhaust stroke is the high temperature side intake port, and the other intake port 51 is the low temperature side intake port.

When the operating region is the high load HCCI operating region, the ECU 3 calculates the required combustion period and the required combustion ratio 50% position according to the engine required load. The required combustion period is the required combustion period of the engine 2 according to the required engine load. The required combustion ratio 50% position is a crank angle at which the center of the combustion period is located.

The ECU 3 obtains the required combustion period from, for example, a map in which the required combustion period is determined from the engine required load, as shown in FIG.

The ECU 3 obtains the required combustion ratio 50% position from, for example, a map in which the required combustion ratio 50% position is determined from the engine required load as shown in FIG.

The ECU 3 calculates the required combustion start time and the required combustion end time from the required combustion period and the required combustion ratio 50% position by the following equations (1) and (2).
Required combustion start time = Required combustion ratio 50% Position-Required combustion period / 2 ... (1)
Required combustion end time = Required combustion ratio 50% position + Required combustion period / 2 ... (2)

If the required combustion start time and the required combustion end time are not within the predetermined ranges, the ECU 3 determines that the HCCI operation cannot be performed due to premature ignition or misfire, and shifts to the SI operation. The predetermined range is the range of the required combustion start time and the required combustion end time in which premature ignition or misfire does not occur.

The ECU 3 calculates the required high temperature in-cylinder temperature from the required combustion start time. The required high temperature in-cylinder temperature is the temperature of the high-temperature portion of the air-fuel mixture in the cylinder required to start combustion at the start of required combustion. The required high temperature in-cylinder temperature changes mainly depending on the amount of burned gas held in the high temperature side intake port.

The ECU 3 calculates the required low temperature in-cylinder temperature from the required combustion end time. The required low temperature in-cylinder temperature is the temperature of the low-temperature portion of the air-fuel mixture in the cylinder required to generate combustion until the required combustion end time. The required low temperature in-cylinder temperature changes mainly depending on the amount of gas mainly composed of fresh air sucked from the low temperature side intake port.

For example, the ECU 3 obtains the required high temperature in-cylinder temperature from the required combustion start time and the required low temperature in-cylinder temperature from the required combustion end time by a map in which the in-cylinder temperature is determined from the ignition timing as shown in FIG.

The ECU 3 determines the intake valve closing timing during the intake stroke from the required low temperature cylinder temperature. For example, the ECU 3 obtains the intake valve closing timing during the intake stroke from a map in which the intake valve closing timing during the intake stroke is determined from the required low temperature in-cylinder temperature as shown in FIG. The lower the required low temperature in the cylinder, the lower the effective compression ratio needs to be, so the intake valve closing timing during the intake stroke is delayed.

When the required high temperature in-cylinder temperature is high with respect to the measured value of the intake air temperature sensor 43 of the high temperature side intake port, the ECU 3 increases the intake single valve opening period, which is the period for opening one intake valve during the exhaust stroke. A large amount of high temperature residual gas is blown back to the intake port 51. The ECU 3 adjusts, for example, the closing timing of the intake valve 11 of the high temperature side intake port during the exhaust stroke to adjust the intake single valve opening period. For example, the ECU 3 obtains the closing time of the intake valve 11 of the high temperature side intake port during the exhaust stroke from a map in which the intake valve closing timing during the exhaust stroke is determined from the required high temperature cylinder temperature as shown in FIG.

Here, during the intake single valve opening period during the exhaust stroke, the exhaust valve is opened at the maximum, as shown in FIG. 9, in order to minimize the exhaust loss and to blow back as much residual gas as possible to the intake port 51. It is the period from the period until the in-cylinder pressure and the intake pressure become equal. That is, the intake single valve opening time during the exhaust stroke is after the exhaust valve opening time. In addition, the intake single valve closing time during the exhaust stroke is before the time when the in-cylinder pressure becomes equivalent to the intake pressure.

By opening the intake valve 11 on one side during the exhaust stroke in this way, the high-temperature burnt gas is held in the intake port 51 on one side. By opening both the intake valves 11a and the intake valves 11b in the next intake stroke, the high-temperature gas in which fresh air and the burned gas are mixed is taken in from the intake port 51 in which the high-temperature burned gas is re-inhaled. Further, low-temperature gas containing fresh air as a main component is taken in from the intake port 51 in which the burned gas is not re-inhaled.

The gas introduced from both the intake port 51a and the intake port 51b forms a tumble, respectively, and the temperature distribution at the time of intake is maintained without being mixed until immediately before combustion. Therefore, even if the amount of fuel is increased for high-load HCCI operation, the in-cylinder air-fuel mixture does not ignite at the same time, and steep combustion can be prevented.

On the other hand, in order to prevent misfire and premature ignition due to stratification of the air-fuel mixture temperature, if the required combustion start time and the required combustion end time are not within the predetermined ranges, the SI operation is shifted to.

The intake single valve opening control process by the control device of the internal combustion engine according to the present embodiment configured as described above will be described with reference to FIG. The intake single valve opening control process described below is started when the process of the ECU 3 is started, and is executed at preset time intervals.

In step S1, the ECU 3 calculates the engine required load from the accelerator opening degree detected by the accelerator opening degree sensor 48, and calculates the engine speed based on the crank angle signal output by the crank angle sensor 45. The ECU 3 determines whether or not the operating region of the engine 2 is within the high load HCCI operating region based on the engine required load and the engine speed. When it is determined that the operating region of the engine 2 is not within the high load HCCI operating region, the ECU 3 ends the process.

When it is determined that the operating region of the engine 2 is within the high load HCCI operating region, in step S2, the ECU 3 calculates the required combustion period from the engine required load according to the map of FIG. Further, the ECU 3 calculates the required combustion ratio 50% position from the engine required load according to the map of FIG.

In step S3, the ECU 3 calculates the required combustion start time and the required combustion end time from the required combustion period and the required combustion ratio 50% position by the above equations (1) and (2).

In step S4, the ECU 3 obtains the required low temperature in-cylinder temperature and the required high-temperature in-cylinder temperature from the required combustion start time and the required combustion end time by the map of FIG.

In step S5, the ECU 3 determines whether or not the required combustion start time and the required combustion end time are within a predetermined range. When it is determined that the required combustion start time and the required combustion end time are not within the predetermined ranges, the ECU 3 ends the process. In this case, the engine 2 is in a state where it is impossible to perform HCCI operation due to premature ignition or misfire.

When it is determined that the required combustion start time and the required combustion end time are within the predetermined ranges, in step S6, the ECU 3 sets the required low temperature in-cylinder temperature and the required high-temperature in-cylinder temperature as target values during the intake stroke. Calculate the intake valve closing time and the intake single valve opening period during the exhaust stroke. The ECU 3 calculates the intake valve closing timing during the intake stroke from the required low temperature in-cylinder temperature according to the map of FIG. The ECU 3 calculates the intake valve closing timing during the exhaust stroke from the required high temperature in-cylinder temperature according to the map of FIG.

In step S7, the ECU 3 adjusts the intake valve closing timing during the intake stroke according to the intake valve closing timing during the intake stroke obtained in step S6. As a result, the required low temperature in-cylinder temperature is realized by adjusting the amount of gas mainly composed of fresh air sucked from the low temperature side intake port.

In step S8, the ECU 3 adjusts the closing time of one of the intake valves 51 according to the closing time of the intake valve during the exhaust stroke obtained in step S6, thereby adjusting the opening period of the intake single valve during the exhaust stroke and processing. To finish. As a result, the amount of burnt gas held in the high temperature side intake port is adjusted to realize the required high temperature in-cylinder temperature.

By opening the intake valve 11 on one side during the exhaust stroke in this way, the high-temperature burnt gas is held in the intake port 51 on one side. By opening both intake valves 11 in the next intake stroke, the high-temperature gas in which fresh air and the burned gas are mixed is taken in from the intake port 51 in which the high-temperature burned gas is re-inhaled. Further, a low-temperature gas containing fresh air as a main component is taken in from the intake port 51 in which the burned gas is not re-inhaled.

As a result, the gases introduced from both intake ports 51 form a tumble, and the temperature distribution at the time of intake is maintained without being mixed until immediately before combustion. Therefore, even if the amount of fuel is increased in order to perform high-load HCCI operation, the in-cylinder air-fuel mixture does not ignite at the same time, and steep combustion can be prevented.

Further, the required combustion period and the required combustion ratio 50% position according to the required engine load are obtained, and the HCCI operation is performed with the obtained values as the target values. As a result, steep combustion can be avoided and highly efficient combustion can be realized.

Further, it is determined whether or not the required combustion start time and the required combustion end time obtained from the required combustion period and the required combustion ratio 50% position exceed the threshold value, and if the threshold value is exceeded, the SI operation is started. As a result, premature ignition and misfire can be avoided.

In addition, the required high temperature in-cylinder temperature and the required low-temperature in-cylinder temperature are obtained according to the required combustion start time and required combustion end time, and the intake valve closing time during the intake stroke and the intake single valve opening period during the exhaust stroke are aimed at. To adjust.

As a result, the required combustion ratio 50% position and the required combustion period can be realized by independently adjusting the required high temperature in-cylinder temperature and the required low-temperature in-cylinder temperature.

In addition, the opening time of the intake single valve during the exhaust stroke shall be after the exhaust valve opening time. This makes it possible to prevent exhaust loss due to opening earlier than the exhaust valve 21.

Further, the closing time of the intake single valve during the exhaust stroke is before the time when the in-cylinder pressure becomes equivalent to the intake pressure. As a result, it is possible to prevent the in-cylinder pressure from falling below the intake pressure and the high-temperature burned gas once blown back to the intake port 51 from returning to the inside of the cylinder during the exhaust stroke.

In this embodiment, the fuel injection method is a port injection method, but a direct injection method in which fuel is directly injected into the cylinder may also be used.

Further, in this embodiment, the required low temperature in-cylinder temperature is adjusted by controlling the intake valve closing timing during the intake stroke, but by intake cooling by the intercooler 18, external EGR (Exhaust Gas Recirculation), water injection, or the like. The required low temperature in-cylinder temperature may be adjusted.

Although the embodiments of the present invention have been disclosed, it is clear that some skilled in the art can make changes without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

1 Vehicle 2 Engine 3 ECU (control unit)
11, 11a, 11b Intake valve 12, 12a, 12b Intake side variable valve mechanism 21, 21a, 21b Exhaust valve 22, 22a, 22b Exhaust side variable valve mechanism 43, 43a, 43b Intake temperature sensor 45 Crank angle sensor 48 Accelerator Opening sensor 51, 51a, 51b Intake port

Claims (3)

It is a control device for an internal combustion engine that is equipped with a plurality of intake valves and exhaust valves per cylinder and burns the air-fuel mixture in the combustion chamber by compression self-ignition.
During the exhaust stroke, some of the intake valves among the plurality of intake valves are opened.
In the next intake stroke, a control unit for opening all of the plurality of intake valves is provided .
The control unit has a function of controlling the combustion period due to the compression self-ignition according to the required load of the internal combustion engine, and
When the operating region is a high load region in the combustion region due to compression self-ignition, the required combustion start time and the required combustion end time are calculated from the required load of the internal combustion engine, and the required high temperature cylinder is charged from the required combustion start time. When the temperature is obtained and the opening period of a part of the intake valves during the exhaust stroke is changed and the required high temperature in-cylinder temperature is high, the intake single valve which is the period during which one of the intake valves is opened during the exhaust stroke. A function to control the opening period and
The required low temperature cylinder temperature is obtained from the required combustion end time, the valve closing timing of the intake valve during the intake stroke is changed, and when the required low temperature cylinder temperature is low, the intake valve closing timing during the intake stroke is determined. The function to control the retardation and
Control apparatus for an internal combustion engine Ru comprising a. The control device for an internal combustion engine according to claim 1, wherein the control unit controls the transition from the compression self-ignition to the spark ignition when the required combustion start time or the required combustion end time exceeds a threshold value. The control device for an internal combustion engine according to claim 2, wherein the control unit controls the closing time of the intake valve during the exhaust stroke to be before the time when the in-cylinder pressure becomes equal to the intake pressure.

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