JP2021025469A - Internal combustion engine - Google Patents

Abstract

To improve combustion stability in a cylinder of an internal combustion engine.SOLUTION: An internal combustion engine 1 has two intake valves 10 in one cylinder. In the cylinder deteriorated in combustion stability due to generation of swirl flow in the cylinder, caused by difference in flow rates in intake gases flowing from each of the intake valves 10a, 10b in operating the intake valves 10 in the same cylinder with the same valve opening characteristics, the swirl flow generated in the cylinder is suppressed by providing the intake valves 10a, 10b of the cylinder with difference in the valve opening characteristics. Thus the swirl flow in the cylinder can be weakened in the internal combustion engine 1, and the combustion stability in the cylinder can be improved by securing strength of tumble flow generated in the cylinder.SELECTED DRAWING: Figure 1

Description

The present invention relates to an internal combustion engine.

For example, Patent Document 1 discloses a technique for improving a combustion state by generating a swirl flow in an air-fuel mixture in a cylinder by making a difference in valve lifts of a plurality of intake valves of the same cylinder at a low load. There is.

Japanese Unexamined Patent Publication No. 6-280528

Here, the combustion state of the internal combustion engine can be improved by generating a tumble flow in the air-fuel mixture in the cylinder.

However, the tumble flow generated in the cylinder of the internal combustion engine is weakened by the swirl flow generated in the cylinder of the internal combustion engine.

That is, the internal combustion engine has room for further improvement in generating a tumble flow of the air-fuel mixture in the cylinder to improve the combustion state (combustion stability) in the cylinder.

In the internal combustion engine of the present invention, in a cylinder in which a flow rate difference occurs in the intake gas flowing from a plurality of intake valves of the same cylinder and a swirl flow is generated in the cylinder, the valve opening characteristics of each intake valve of the cylinder are different. It is characterized by suppressing the swirl flow generated in the cylinder.

The internal combustion engine of the present invention can weaken the swirl flow in the cylinder, secure the strength of the tumble flow generated in the cylinder, and improve the combustion stability in the cylinder.

An explanatory view schematically showing a schematic configuration of an in-line 3-cylinder internal combustion engine to which the present invention is applied. Explanatory drawing which shows typically the internal combustion engine in 1st Example of this invention. The explanatory view which shows an example of the valve timing when the valve opening characteristic of the intake valve of the same cylinder is different. The explanatory view which shows an example of the valve timing when the valve opening characteristic of the intake valve of the same cylinder is different. The explanatory view which shows typically the cylinder which becomes the main part of the internal combustion engine in the 2nd Example of this invention.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram schematically showing a schematic configuration of an in-line 3-cylinder internal combustion engine to which the present invention is applied. FIG. 2 is an explanatory diagram schematically showing the internal combustion engine 1 according to the first embodiment of the present invention.

An EGR passage 4 is connected to the intake passage 2 of the internal combustion engine 1 at a position downstream of the throttle valve 3 in the intake flow direction. The EGR passage 4 enables exhaust gas recirculation (EGR) in which a part of exhaust gas is returned to the intake passage 2 from an exhaust passage (not shown).

Further, the intake passage 2 is provided with an intake collector 5 having a certain amount of volume at a position downstream of the connection position of the EGR passage 4 in the intake flow direction. The intake collector 5 is arranged, for example, along the cylinder row direction.

The intake collector 5 distributes intake air to the intake ports 7 of each cylinder. An upstream end portion 8 which is an inlet portion of the intake port 7 is connected to the downstream side wall portion 5a of the intake collector 5. The downstream side wall portion 5a is a wall portion along the cylinder row direction, and is a wall portion located on the downstream side in the intake flow direction among the wall portions constituting the intake collector 5.

The intake port 7 is bifurcated on the downstream side in the intake flow direction. The intake port 7 has a pair of downstream end portions 9a and 9b at the downstream end portions in the intake flow direction. The pair of downstream end portions 9a and 9b are connected to the combustion chamber 11 (inside the cylinder) of the internal combustion engine 1 via an intake valve 10, respectively. That is, the internal combustion engine 1 has two intake valves 10 in one cylinder. In other words, the internal combustion engine 1 has a plurality of intake valves 10 in the same cylinder.

The downstream end portion 9a is located on one end side (lower side in FIG. 1, right side in FIG. 2) of the internal combustion engine 1 in the cylinder row direction with respect to the downstream end portion 9b of the same cylinder.

The internal combustion engine 1 has two intake valves 10a and 10b in each cylinder in order to open and close the downstream end portions 9a and 9b of the intake port 7. The intake valve 10a opens and closes the downstream end 9a of the intake port 7. The intake valve 10b opens and closes the downstream end 9b of the intake port 7. The intake valve 10a is located on one end side (lower side in FIG. 1, right side in FIG. 2) of the internal combustion engine 1 in the cylinder row direction with respect to the intake valve 10b of the same cylinder.

As shown in FIG. 2, the intake valve 10 of each cylinder is opened and closed by the valve operating mechanism 12. The valve operating mechanism 12 has a cam shaft 13 driven by a crankshaft (not shown), and first cam 14 and second cam 15 provided on the cam shaft 13. The first cam 14 and the second cam 15 are provided for each cylinder. The first cam 14 as the intake cam opens and closes the intake valve 10a. The second cam 15 as the intake cam opens and closes the intake valve 10b. Reference numeral 16 in FIG. 1 is a valve spring that urges the intake valve 10 in the valve closing direction. The valve spring 16a urges the intake valve 10a. The valve spring 16b urges the intake valve 10b. The valve operating mechanism 12 is a direct acting valve operating mechanism, and the phases of the lift / operating angle and the lift central angle of the intake valves 10a and 10b are always constant.

When a plurality of intake valves 10a and 10b of the same cylinder are operated with the same valve opening characteristics, a flow rate difference occurs in the intake gas flowing from each intake valve 10a and 10b, and a swirl flow is generated in the cylinder to stabilize combustion. In the cylinder whose property deteriorates, the swirl flow generated in the cylinder is suppressed by making a difference in the valve opening characteristics of the intake valves 10a and 10b of the cylinder.

For example, when the intake collector 5 is arranged along the cylinder row direction of the internal combustion engine 1, when the intake valves 10 of the same cylinder are operated with the same valve opening characteristics, the flow rate to the intake gas flowing from the intake valves 10a and 10b. The cylinders that make a difference are the # 1 cylinder located at the end on one end side in the cylinder row direction and the # 3 cylinder located at the end on the other end side.

In the # 1 cylinder, when the intake valves 10a and 10b are operated with the same valve opening characteristics, the intake gas flowing into the cylinder from the intake valve 10a becomes relatively large, as shown by the broken line in FIG. In FIG. 1, a counterclockwise swirl flow is generated.

In the # 3 cylinder, when the intake valves 10a and 10b are operated with the same valve opening characteristics, the intake gas flowing into the cylinder from the intake valve 10b becomes relatively large, as shown by the broken line in FIG. A clockwise swirl flow is generated in FIG.

Therefore, in this first embodiment, the valve opening characteristics of the intake valves 10a and 10b of the # 1 cylinder and the # 3 cylinder are different in advance, and the flow rate difference of the intake gas flowing from the intake valves 10a and 10b of the same cylinder is calculated. By making it smaller, the swirl flow generated in the cylinder is suppressed.

The valve opening characteristics of the intake valve 10 are an opening area characteristic value determined according to a change in the intake valve lift amount with respect to the crank angle of the crankshaft of the internal combustion engine 1, and a phase with respect to the crank angle during the intake valve opening period (lift of the intake valve 10). It changes according to the phase of the central angle), the valve diameter of the intake valve 10 (the hole diameter of the downstream end 9 of the intake port 7), and the like.

In the first embodiment, in the # 1 cylinder, the opening area characteristic value of the intake valve 10a located on the one end side end side of the internal combustion engine in the cylinder row direction is reduced to enter the cylinder via the intake valve 10a. The intake gas that flows in is reduced, and the opening area characteristic value of the intake valve 10b located on the other end side of the internal combustion engine in the cylinder row direction is increased to increase the intake air that flows into the cylinder through the intake valve 10b. I have a lot of gas.

Further, in the first embodiment, in the # 3 cylinder, the opening area characteristic value of the intake valve 10b located on the other end side of the internal combustion engine in the cylinder row direction is reduced to pass through the intake valve 10b. The intake gas flowing into the cylinder is reduced, and the opening area characteristic value of the intake valve 10a located on one end side of the internal combustion engine in the cylinder row direction is increased to flow into the cylinder through the intake valve 10a. The amount of intake gas is increased.

The valve opening characteristics of the intake valves 10a and 10b of the # 2 cylinder are the same as each other.

As a result, the internal combustion engine 1 can weaken the swirl flow in the cylinder in the # 1 cylinder and the # 3 cylinder, secures the strength of the tumble flow generated in the cylinder, and improves the combustion stability in the cylinder. Can be made to. In other words, the internal combustion engine 1 can prevent the tumble flow in the cylinder from being weakened by the swirl flow generated in the cylinder in the # 1 cylinder and the # 3 cylinder, and improve the combustion stability. Can be done.

3 and 4 are explanatory views showing an example of valve timing when the valve opening characteristics of the intake valves 10 of the same cylinder are different in order to suppress the swirl flow generated in the cylinder.

FIG. 3 shows a case where the valve opening characteristics of the intake valves 10a and 10b of the same cylinder are different by making a difference in the opening area characteristic values of the intake valves 10a and 10b of the same cylinder. The intake valve characteristic line C1 in FIG. 3 is the intake valve (intake on the large flow rate side) in which the amount of intake gas that flows in relatively increases when two intake valves 10 of the same cylinder are operated with the same valve opening characteristics. The valve timing of the valve) is shown. The intake valve characteristic line C2 in FIG. 3 is the intake valve (small flow rate side intake) in which the amount of intake gas that flows in relatively small when two intake valves 10 of the same cylinder are operated with the same valve opening characteristics. The valve timing of the valve) is shown.

FIG. 4 shows a case where the valve opening characteristics of the intake valves 10a and 10b of the same cylinder are different by making a difference in the phase of the intake valves 10a and 10b of the same cylinder with respect to the crank angle during the intake valve opening period. ing. The intake valve characteristic line C3 in FIG. 4 is the intake valve (intake on the large flow rate side) in which the amount of intake gas that flows in relatively increases when two intake valves 10 of the same cylinder are operated with the same valve opening characteristics. The valve timing of the valve) is shown. The intake valve characteristic line C4 in FIG. 4 is the intake valve (small flow rate side intake) in which the amount of intake gas that flows in relatively decreases when two intake valves 10 of the same cylinder are operated with the same valve opening characteristics. The valve timing of the valve) is shown.

The opening area characteristic value was obtained by integrating a function representing the intake valve lift amount with respect to the crank angle (intake valve characteristic lines C1 to C4 in FIGS. 3 and 4) in the section from the intake valve opening time to the intake valve closing time. The value. In other words, the opening area characteristic value is surrounded by an intake valve characteristic line represented by a coordinate system in which the Y-axis (vertical axis) is the intake valve lift amount and the X-axis (horizontal axis) is the crank angle, and the X-axis. It is the area of the removed part. The opening area characteristic values according to the intake valve characteristic lines C3 and C4 in FIG. 4 are the same values.

As the opening area characteristic value of the intake valve 10 becomes smaller, the amount of intake gas flowing into the cylinder during the intake valve opening period decreases.

Further, the intake valve 10 reduces the amount of intake gas flowing into the cylinder during the intake valve opening period by advancing the phase with respect to the crank angle during the intake valve opening period. For example, when the intake valve closing time as a result of advancing the intake valve opening period is before bottom dead center, the intake valve 10 enters the cylinder with the intake valve 10 closing time earlier. The amount of gas decreases relatively. Further, for example, when the intake valve closing time as a result of advancing the intake valve opening period is after the bottom dead center, the intake valve 10 enters the cylinder by inertia because the valve closing time of the intake valve 10 is earlier. The amount of incoming intake gas decreases relatively.

In the first embodiment described above, in order to set the valve timings of the plurality of intake valves 10a and 10b of the same cylinder as shown in FIG. 3 or 4, for example, the cam profiles of the first cam 14 and the second cam 15. Can be set to different cam profiles. That is, a difference may be provided between the shape of the first cam 14 and the shape of the second cam 15 so that the intake valves 10a and 10b at the valve timing as shown in FIG. 3 or FIG. 4 are obtained.

In the first embodiment described above, in order to set the valve timings of the plurality of intake valves 10a and 10b of the same cylinder as shown in FIG. 4, for example, the cam angle of the first cam 14 and the cam angle of the second cam 15 are set. May be set to different cam angles. That is, a difference may be provided between the cam angle of the first cam 14 and the cam angle of the second cam 15 so that the intake valves 10a and 10b have the valve timing as shown in FIG.

In the first embodiment described above, in order to set the valve timings of the plurality of intake valves 10a and 10b of the same cylinder as shown in FIG. 3, for example, the valve springs 16a for urging the intake valves 10a in the valve closing direction and The load characteristics (spring characteristics) of the valve spring 16b that urges the intake valve 10b in the valve closing direction may be set to different load characteristics. That is, even if a difference is provided between the spring constant (spring characteristic) of the valve spring 16a and the spring constant (spring characteristic) of the valve spring 16b so that the intake valves 10a and 10b have the valve timing as shown in FIG. Good. For example, if the spring constant of the valve spring 16 is increased, the mechanical portion such as the camshaft is bent and deformed by the spring force of the valve spring 16 when the intake valve 10 is opened, and the lift amount of the intake valve 10 is reduced by that amount. Therefore, the opening area characteristic value decreases, and as a result, the valve opening characteristic of the intake valve 10 changes.

Further, the internal combustion engine 1 flows into the cylinder from the intake valves 10a and 10b by setting the valve diameters of the intake valves 10a and the intake valves 10b to different sizes in advance in the # 1 cylinder and the # 3 cylinder. It is also possible that there is no difference in the flow rate of the intake gas. That is, in the intake valve 10 of the same cylinder, the valve diameters of the intake valve 10a and the intake valve 10b may be set to different sizes to provide a difference in valve opening characteristics. In other words, in the intake valve 10 of the same cylinder, the hole diameters of the downstream end portion 9a and the downstream end portion 9b may be set to different sizes to provide a difference in valve opening characteristics.

Specifically, in the # 1 cylinder, the internal combustion engine 1 reduces the valve diameter of the intake valve 10a located on one end side of the internal combustion engine in the cylinder row direction and enters the cylinder via the intake valve 10a. The intake gas that flows in is reduced, and the valve diameter of the intake valve 10b located on the other end side of the internal combustion engine in the cylinder row direction is increased to allow the intake gas that flows into the cylinder through the intake valve 10b. You may try to increase it.

Further, the internal combustion engine 1 flows into the cylinder through the intake valve 10b by reducing the valve diameter of the intake valve 10b located on the other end side of the internal combustion engine in the cylinder row direction in the # 3 cylinder. In addition to reducing the intake gas, increase the valve diameter of the intake valve 10a located on the one end side end side of the internal combustion engine in the cylinder row direction to increase the intake gas flowing into the cylinder through the intake valve 10a. It may be.

Hereinafter, other examples of the present invention will be described. The same components as those in the first embodiment described above are designated by the same reference numerals, and duplicate description will be omitted.

A second embodiment of the present invention will be described with reference to FIG. FIG. 5 is an explanatory view schematically showing a cylinder which is a main part of the internal combustion engine 21 in the second embodiment of the present invention.

The internal combustion engine 21 of the second embodiment has substantially the same configuration as the internal combustion engine 1 of the first embodiment described above, but each intake valve 10 of each cylinder is a variable valve whose valve timing can be changed. It can be driven at different valve timings. That is, each intake valve 10 of each cylinder is an electromagnetically driven valve that can be individually driven with different opening / closing timings, different valve lift amounts, different lift central angle phases, and the like. Reference numeral 22 in FIG. 5 is an electromagnetic drive unit that drives the intake valve 10.

Each intake valve 10 of each cylinder is open / closed controlled so as to have a predetermined valve timing based on a command signal from the control unit 23.

The control unit 23 is a well-known digital computer including a CPU, ROM, RAM, and an input / output interface. Detection signals of various sensors such as a crank angle sensor 24 for detecting the crank angle of the crankshaft and an in-cylinder pressure sensor 25 for detecting the in-cylinder pressure of each cylinder are input to the control unit 23. The crank angle sensor 24 can detect the engine speed of the internal combustion engine 21.

The control unit 23 can determine whether the combustion stability of each cylinder is good or bad by using the detection signal of the crank angle sensor 24. That is, the control unit 23 corresponds to the first combustion state determination unit that detects the combustion state of each cylinder.

Further, the control unit 23 can determine whether the combustion stability of each cylinder is good or bad by using the detection signal of the in-cylinder pressure sensor 25. That is, the control unit 23 corresponds to a second combustion state determination unit that detects the combustion state of each cylinder.

In the control unit 23, in the cylinder determined to have poor combustion stability, a flow rate difference occurs in the intake gas flowing in from the intake valves 10a and 10b of the cylinder, and a swirl flow is generated in the cylinder to deteriorate the combustion stability. It is judged that it has been done.

Then, the control unit 23 makes a difference in the valve opening characteristics of the intake valves 10a and 10b of the cylinder so that the swirl flow generated in the cylinder of the cylinder determined to have poor combustion stability is suppressed. The valve timing of the intake valves 10a and 10b is changed. Thereby, the reliability of the internal combustion engine 21 can be improved.

Further, in the internal combustion engine 21 of the second embodiment, similarly to the internal combustion engine 1 of the first embodiment described above, when a plurality of intake valves 10a and 10b of the same cylinder are operated with the same valve opening characteristics, each intake valve 10a In a cylinder in which a flow difference occurs in the intake gas flowing in from 10b and a swirl flow is generated in the cylinder to deteriorate combustion stability, the valve opening characteristics of the intake valves 10a and 10b of the cylinder are made different. The swirl flow generated inside is suppressed.

As a result, the internal combustion engine 21 of the second embodiment can exert substantially the same effects as those of the first embodiment described above.

Further, in the internal combustion engine 21 of the second embodiment, in the cylinder determined to have poor combustion stability in a predetermined operating state, the intake valve of the cylinder is maintained in the closed state to perform cylinder deactivation. May be good.

That is, in a predetermined operating state, the internal combustion engine 21 is driven only by a cylinder having good combustion stability in which no swirl flow is generated in the cylinder, and a cylinder having poor combustion stability in which swirl flow is generated in the cylinder is used. You may want to pause. Thereby, the reliability of the internal combustion engine 21 can be improved.

Here, the predetermined operating state in which the cylinder of the internal combustion engine 21 may be deactivated is, for example, a lean combustion operating condition in which the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, or an operation in which diluted combustion is performed by EGR. Conditions etc.

When the intake valve 10 is a variable valve, the intake valve 10 is not limited to the above-mentioned electromagnetic drive valve. The intake valve 10 may be used, for example, by switching between two types of cams having different cam profiles, one with a difference in valve opening characteristics and the other without.

Although specific examples of the present invention have been described above, the present invention is not limited to the above-mentioned examples, and various modifications can be made without departing from the spirit of the present invention.

For example, in the internal combustion engine 1, in the # 1 cylinder and the # 3 cylinder, the intake valves 10a and 10b of the same cylinder are changed by changing the valve opening characteristics of one of the pair of intake valves 10a and 10b of the same cylinder. The flow rate difference of the intake gas flowing in from may be reduced. In other words, even if the flow rate difference of the intake gas flowing from the intake valves 10a and 10b of the same cylinder is reduced by changing the valve opening characteristics of some of the intake valves 10 of the plurality of intake valves 10 of the same cylinder. Good.

Specifically, the internal combustion engine 1 flows into the cylinder when the valve opening characteristics of the intake valves 10a and 10b are different to reduce the flow difference of the intake gas flowing from the intake valves 10a and 10b of the same cylinder. The opening area characteristic of the intake valve 10 with less intake gas is increased, the phase of the valve opening period of the intake valve 10 with less intake gas flowing into the cylinder is advanced, or the intake gas flows into the cylinder. The difference in flow rate of the intake gas flowing from the intake valves 10a and 10b of the same cylinder may be reduced by increasing the valve diameter of the intake valve 10 having the smaller intake gas.

Further, in the internal combustion engine 1, when the valve opening characteristics of the intake valves 10a and 10b are different to reduce the difference in the flow rate of the intake gas flowing from the intake valves 10a and 10b of the same cylinder, the intake gas flowing into the cylinder is reduced. The opening area characteristic of the intake valve 10 that has a large amount of air is reduced, the opening period of the intake valve 10 that has a large amount of intake gas that flows into the cylinder is delayed, or the intake gas that flows into the cylinder is large. The difference in flow rate of the intake gas flowing from the intake valves 10a and 10b of the same cylinder may be reduced by reducing the valve diameter of the intake valve 10 of the above.

The internal combustion engine 1 of each of the above-described embodiments is an in-line 3-cylinder engine, but the present invention is also applicable to a multi-cylinder internal combustion engine other than the 3-cylinder engine. Further, the above-described embodiments other than those for cylinder deactivation can also be applied to a single-cylinder internal combustion engine.

Further, in constructing an internal combustion engine that suppresses the swirl flow generated in the cylinder by making a difference in the valve opening characteristics of the intake valves 10a and 10b of the same cylinder, the contents disclosed in the above-described embodiment are appropriately combined. May be configured.

1 ... Internal combustion engine 2 ... Intake passage 3 ... Throttle valve 4 ... EGR passage 5 ... Intake collector 5a ... Downstream end wall 7 ... Intake port 8 ... Upstream end 9a ... Downstream end 9b ... Downstream end 10 ... Intake valve 10a ... Intake valve 10b ... Intake valve 11 ... Combustion chamber 12 ... Valve mechanism 13 ... Camshaft 14 ... First cam 15 ... Second cam 16 ... Valve spring 16a ... Valve spring 16b ... Valve spring

Claims (16)

In an internal combustion engine having multiple intake valves in the same cylinder
In a cylinder in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, the swirl flow generated in the cylinder with a difference in the valve opening characteristics of each intake valve of the cylinder. An internal combustion engine characterized by suppressing. The internal combustion engine according to claim 1, wherein the valve opening characteristic of the intake valve changes according to an opening area characteristic value determined according to a change in the intake valve lift amount with respect to a crank angle. In a cylinder in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, the opening area characteristic value of the intake valve where the flow rate is relatively large is reduced, and the intake valve is changed. The internal combustion engine according to claim 2, wherein the intake gas flowing into the cylinder through the cylinder is reduced to suppress the swirl flow generated in the cylinder. In a cylinder in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, the opening area characteristic value of the intake valve whose flow rate is relatively small is increased, and the intake valve is changed. The internal combustion engine according to claim 2 or 3, wherein the intake gas flowing into the cylinder through the cylinder is increased to suppress the swirl flow generated in the cylinder. The valve opening characteristic of the intake valve changes according to the phase with respect to the crank angle during the valve opening period of the intake valve.
In a cylinder in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, the phase of the valve opening period of the intake valve in which the flow rate is relatively large is relatively large. The internal combustion engine according to any one of claims 1 to 4, wherein the swirl flow generated in the cylinder is suppressed by advancing the phase with respect to the phase of the valve opening period of the intake valve, which is reduced. Each intake valve of a cylinder in which a flow difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder is a variable valve whose valve timing can be changed, and is the same by the variable valve. The internal combustion engine according to any one of claims 1 to 5, wherein the valve opening characteristics of the intake valves of the cylinders are different. It has a first combustion state determination unit that detects the combustion state of each cylinder using the detection signal of the crank angle sensor.
In the cylinder judged to have poor combustion stability by the first combustion state determination unit, it is assumed that the combustion stability has deteriorated due to the generation of swirl flow, and the variable valve causes a difference in the valve opening characteristics of each intake valve of the cylinder. The internal combustion engine according to claim 6, wherein the swirl flow generated in the cylinder is suppressed. It has a second combustion state determination unit that detects the combustion state of each cylinder using the detection signal of the cylinder pressure sensor that detects the cylinder pressure.
In the cylinder judged to have poor combustion stability by the second combustion state determination unit, it is assumed that the combustion stability has deteriorated due to the generation of swirl flow, and the variable valve causes a difference in the valve opening characteristics of each intake valve of the cylinder. The internal combustion engine according to claim 6 or 7, wherein the swirl flow generated in the cylinder is suppressed. The internal combustion engine is a multi-cylinder internal combustion engine,
The variable valve keeps the intake valve of the cylinder in which a swirl flow is generated in the cylinder due to a difference in the flow rate of the intake gas flowing from each intake valve of the same cylinder in a predetermined operating state. The internal combustion engine according to claim 6, wherein the internal combustion engine is suspended. It has a first combustion state determination unit that detects the combustion state of each cylinder using the detection signal of the crank angle sensor.
A cylinder whose combustion stability is determined to be poor by the first combustion state determination unit is characterized in that the cylinder is deactivated by the variable valve, assuming that the combustion stability has deteriorated due to the generation of swirl flow. The internal combustion engine according to claim 9. It has a second combustion state determination unit that detects the combustion state of each cylinder using the detection signal of the cylinder pressure sensor that detects the cylinder pressure.
A cylinder whose combustion stability is determined to be poor by the second combustion state determination unit is characterized in that the cylinder is deactivated by the variable valve, assuming that the combustion stability has deteriorated due to the generation of swirl flow. The internal combustion engine according to claim 9 or 10. In a cylinder in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, the valve opening of each intake valve of the cylinder is made by providing a difference in the shape of the cam of each intake valve. The internal combustion engine according to any one of claims 1 to 5, wherein the swirl flow generated in the cylinder is suppressed by making a difference in characteristics. In a cylinder in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, the valve opening characteristic of each intake valve of the cylinder is provided by providing a difference in the cam angle of each intake valve. The internal combustion engine according to claim 5, wherein the swirl flow generated in the cylinder is suppressed by making a difference between the two. In a cylinder in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, the valve opening characteristic of each intake valve of the cylinder is provided by providing a difference in the valve diameter of each intake valve. The internal combustion engine according to any one of claims 1 to 5, wherein the swirl flow generated in the cylinder is suppressed by making a difference between the two. In a cylinder in which a flow difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder, by providing a difference in the spring constant of the valve spring of each intake valve, each intake valve of the cylinder concerned The internal combustion engine according to any one of claims 1 to 5, wherein the swirl flow generated in the cylinder is suppressed by making a difference in the valve opening characteristics. The internal combustion engine is a multi-cylinder internal combustion engine,
The cylinders in which a flow rate difference occurs in the intake gas flowing from each intake valve of the same cylinder and a swirl flow is generated in the cylinder are a cylinder located at one end in the cylinder row direction and a cylinder located at the other end. Yes,
For cylinders located at one end of the internal combustion engine, the opening area characteristic value of the intake valve located at one end of the internal combustion engine is reduced in the cylinder row direction.
In the cylinder located at the other end of the internal combustion engine, the opening area characteristic value of the intake valve located on the other end of the internal combustion engine is reduced in the cylinder row direction.
A claim characterized by suppressing a swirl flow generated in a cylinder located at one end of an internal combustion engine in the cylinder row direction and a cylinder located at the other end of the internal combustion engine in the cylinder row direction. The internal combustion engine according to any one of 1 to 6 and 12 to 15.

Images