JP2023154256A - Intake system of internal combustion engine - Google Patents

Abstract

To provide an intake system capable of making operation characteristics of an internal combustion engine variable.SOLUTION: An intake system includes: a first intake valve which is provided on a swirl port of a combustion chamber of an internal combustion engine; a second intake valve which is provided on a tumble port of the combustion chamber and in which a time of an open state is determined to be longer than a time of an open state of the first intake valve; and an adjustment valve which is provided on a tumble intake passage connected to the tumble port. In a close state of the adjustment valve, a swirl flow of a high swirl ratio is generated in the combustion chamber and an Otto cycle is realized, and in an open state of the adjustment valve, a mirror cycle is realized while lowering the swirl ratio of the swirl flow in the combustion chamber.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an intake system for an internal combustion engine.

BACKGROUND ART Intake systems that change the operating characteristics of an engine (internal combustion engine) by changing the operating characteristics of engine valves have been known (see Patent Document 1).

Japanese Patent Application Publication No. 2014-102670

By the way, in the case of conventionally known intake systems, the configuration for making the operating characteristics of engine valves variable tends to be complicated. For this reason, the cost of the intake system and, by extension, the vehicle equipped with the intake system may increase.

An object of the present disclosure is to provide an intake system for an internal combustion engine that can make the operating characteristics of the internal combustion engine variable at low cost.

An intake system for an internal combustion engine according to the present disclosure includes:
A first intake valve provided in a swirl port of a combustion chamber of an internal combustion engine;
a second intake valve that is provided at a tumble port of the combustion chamber and whose open state time is set longer than the open state time of the first intake valve;
A regulating valve provided in the tumble intake passage connected to the tumble port,
When the regulating valve is closed, a swirl flow with a high swirl ratio is generated in the combustion chamber, and an Otto cycle is realized.
When the regulating valve is open, the mirror cycle is realized while lowering the swirl ratio of the swirl flow in the combustion chamber.

According to the present disclosure, an intake system for an internal combustion engine that can make the operating characteristics of the internal combustion engine variable can be provided at low cost.

FIG. 1 is a diagram showing the configuration of an engine according to an embodiment of the present disclosure. FIG. 2 is a diagram for explaining the shape of the first cam. FIG. 3 is a diagram for explaining the shape of the second cam. FIG. 4 is a diagram showing the relationship between crank angle and lift amount regarding the first cam and the second cam. FIG. 5 is a schematic diagram for explaining the operation of the intake system. FIG. 6 is a schematic diagram for explaining the operation of the intake system. FIG. 7 is a schematic diagram for explaining the operation of the intake system. FIG. 8 is a flowchart showing the operation of the intake system. FIG. 9 is a diagram for explaining the relationship between the operating status of the engine and the status of the intake system.

Embodiments according to the present disclosure will be described below based on the drawings.

<Embodiment>
FIG. 1 shows the configuration of an internal combustion engine 1 according to an embodiment of the present disclosure. The internal combustion engine 1 is, for example, a diesel engine mounted on a vehicle such as a truck.

A cylinder block 11 of the internal combustion engine 1 is provided with a plurality of cylinders 12 . Note that in FIG. 1, only one cylinder 12 is shown.

The cylinder 12 is provided with a piston 13. The piston 13 is connected to a crankshaft (not shown) via a connecting rod 14. The piston 13 moves up and down within the cylinder 12 in response to rotation of the crankshaft.

Cylinder 12 has a combustion chamber 120 defined by the inner surface of cylinder 12 and the upper surface of piston 13 . The combustion chamber 120 has a swirl port 121 and a tumble port 122, which are intake ports, and at least one (in the case of this embodiment, two) exhaust ports 30 and 31 (see FIGS. 5 to 7).

A swirl intake passage 17 is connected to the swirl port 121 . Further, the tumble intake passage 18 is connected to the tumble port 122. The swirl intake passage 17 and the tumble intake passage 18 include, for example, an intake passage formed in the cylinder head 15 and an intake passage provided in a so-called intake manifold.

Air flowing into the combustion chamber 120 from the swirl port 121 through the swirl intake passage 17 generates a swirl flow with a high swirl ratio within the combustion chamber 120.

In other words, the swirl intake passage 17 has a configuration (shape, angle with respect to the swirl port 121, etc.) that can supply air to the combustion chamber 120 to generate a swirl flow with a high swirl ratio within the combustion chamber 120. .

Note that the swirl ratio means the number of rotations of the swirl flow during one reciprocation of the piston 13. For example, if the number of revolutions of the swirl flow during one reciprocation of the piston 13 is two revolutions, the swirl ratio is two.

Furthermore, the air flowing into the combustion chamber 120 from the tumble port 122 through the tumble intake passage 18 generates a tumble flow with a high tumble ratio within the combustion chamber 120.

In other words, the tumble intake passage 18 has a configuration (shape, angle with respect to the tumble port 122, etc.) that can supply air to the combustion chamber 120 to generate a tumble flow with a high tumble ratio within the combustion chamber 120. .

Note that the tumble ratio means the number of rotations of the tumble flow during one reciprocation of the piston 13. For example, if the number of revolutions of the tumble flow during one reciprocation of the piston 13 is two, the tumble ratio is two.

A cylinder head 15 that covers the upper part of the cylinder block 11 is provided with an injector 16, an intake system 2, and an exhaust system 3 for each cylinder 12.

The injector 16 is, for example, a piezo type injector, and injects light oil, which is fuel for ignition, into the cylinder 12. The injection of light oil from the injector 16 is controlled by a control section 27, which will be described later.

Next, the configuration of the intake system 2 will be explained. The intake system 2 is a system for supplying intake air to the combustion chamber 120 of the cylinder 12. An intake system 2 is provided for each cylinder 12. The configuration of the intake system 2 corresponding to one cylinder 12 will be described below.

The intake system 2 includes a first intake valve 20 , a second intake valve 21 , a regulating valve 22 , a camshaft 23 , a first cam 24 , a second cam 25 , a supercharger 26 , and a control section 27 .

The first intake valve 20 is provided at the swirl port 121 of the combustion chamber 120 of the cylinder 12 . The first intake valve 20 is a valve for opening and closing the swirl port 121.

The first intake valve 20 can take an open state and a closed state by moving in the axial direction according to the rotation of a first cam 24, which will be described later. When the first intake valve 20 is in the open state, the swirl port 121 is opened. When the first intake valve 20 is in the closed state, the swirl port 121 is closed.

The first intake valve 20 is configured such that the time it is in the open state is a first predetermined time. The first predetermined time is a time set based on the shape of the first cam 24, which will be described later. Further, the timing at which the first intake valve 20 completely closes is the same or approximately the same as the timing at which the piston 13 reaches the bottom dead center.

The second intake valve 21 is provided at the tumble port 122 of the combustion chamber 120 of the cylinder 12 . The second intake valve 21 is a valve for opening and closing the tumble port 122.

The second intake valve 21 can take an open state and a closed state by moving in the axial direction according to the rotation of a second cam 25, which will be described later. When the second intake valve 21 is in the open state, the tumble port 122 is opened. When the second intake valve 21 is in the closed state, the tumble port 122 is closed.

The second intake valve 21 is configured so that the time in the open state is a second predetermined time. The second predetermined time is a time set based on the shape of the second cam 25, which will be described later. In the case of this embodiment, the second predetermined time is longer than the first predetermined time. Further, the timing at which the second intake valve 21 is completely closed is after a predetermined period of time has elapsed after the piston 13 reaches the bottom dead center.

The regulating valve 22 is a solenoid valve whose opening degree can be adjusted, and is provided in the tumble intake passage 18 . The operation of the regulating valve 22 is controlled by a control section 27, which will be described later. The regulating valve 22 can take a closed state where the degree of opening is zero and an open state where the degree of opening is greater than zero. Further, a state in which the opening degree of the regulating valve 22 is at its maximum is referred to as a fully open state.

When the regulating valve 22 is in the closed state, intake air is not supplied to the combustion chamber 120 from the tumble port 122 regardless of the state of the second intake valve 21.

On the other hand, when the regulating valve 22 is in the open state, intake air is supplied from the tumble port 122 to the combustion chamber 120 when the second intake valve 21 is in the open state. At this time, the amount of intake air supplied from the tumble port 122 to the combustion chamber 120 is adjusted by the opening degree of the regulating valve 22.

Camshaft 23 is supported by cylinder head 15. The camshaft 23 is rotatable, and its movement in the axial direction is restricted by a restriction mechanism (not shown). The camshaft 23 rotates based on the rotation of a crankshaft (not shown).

The first cam 24 is a cam for opening and closing the first intake valve 20. The first cam 24 is fixed to the camshaft 23. That is, in the case of this embodiment, the first cam 24 is rotatable together with the camshaft 23 and does not move in the axial direction. Therefore, the operating characteristics (opening/closing timing, opening amount, etc.) of the first intake valve 20 do not change.

The cam surface 240 of the first cam 24 is in contact with the upper end of the first intake valve 20 . Note that the first cam does not need to be in direct contact with the first intake valve as long as it can open and close the first intake valve. For example, the first cam may open and close the first intake valve via another member (for example, a rocker arm).

In the case of the present embodiment, the first cam 24 defines the opening/closing timing, opening amount (lift amount), open state time, etc. of the first intake valve 20 based on the shape of the cam surface 240. In the case of the present embodiment, the first cam 24 determines the amount of opening of the first intake valve 20 ( (lift amount) is specified as the first opening amount.

Further, the first cam 24 defines the open state time of the first intake valve 20 to a first predetermined time based on the shape of the cam nose 241 on the cam surface 240.

The second cam 25 is a cam for opening and closing the second intake valve 21. The second cam 25 is fixed to the camshaft 23. That is, the second cam 25 is rotatable together with the camshaft 23 and does not move in the axial direction. Therefore, the operating characteristics (opening/closing timing, opening amount, etc.) of the second intake valve 21 do not change.

The cam surface 250 of the second cam 25 is in contact with the upper end of the second intake valve 21 . Note that the second cam does not need to be in direct contact with the second intake valve as long as it can open and close the second intake valve. For example, the second cam may open and close the second intake valve via another member (for example, a rocker arm).

In the case of the present embodiment, the second cam 25 defines the opening/closing timing, opening amount (lift amount), and open state time of the second intake valve 21 based on the shape of the cam surface 250.

The second cam 25 controls the opening amount (lift amount) of the second intake valve 21 based on the difference between the major axis D2 (cam height) and the minor axis d2 (cam width) of the second cam 25. The opening amount is specified.

Further, the second cam 25 defines the open state time of the second intake valve 21 as a second predetermined time based on the shape of the cam nose 251 on the cam surface 250.

In the case of this embodiment, the first opening amount, which is the opening amount (lift amount) of the first intake valve 20, and the second opening amount, which is the opening amount (lift amount) of the second intake valve 21, are equal. In other words, as shown in FIGS. 2 to 4, the difference between the major axis D1 (cam height) and minor axis d1 (cam width) of the first cam 24 and the major axis D2 (cam height) of the second cam 25 The difference between the short diameter d2 (the width of the cam) and the short diameter d2 (the width of the cam) is equal.

Further, the second predetermined time, which is the time during which the second intake valve 21 is in the open state, is longer than the first predetermined time, which is the time during which the first intake valve 20 is in the open state.

Here, FIG. 4 is a diagram showing the relationship between the crank angle and the lift amount (opening amount) regarding the first cam 24 (first intake valve 20) and the second cam 25 (second intake valve 21). . The solid line in FIG. 4 shows the relationship between the crank angle and the lift amount (opening amount) regarding the first cam 24 (first intake valve 20). Further, the dotted line in FIG. 4 indicates the relationship between the crank angle and the lift amount (opening amount) regarding the second cam 25 (second intake valve 21).

From FIG. 4, the crank angle range (that is, time) at which the lift amount (opening amount) of the second cam 25 (second intake valve 21) is maximum is the It can be seen that the amount (amount of opening) is longer than the range of crank angles (that is, the time) at which the amount (amount of opening) is maximum.

In order to define the relationship between the second predetermined time and the first predetermined time as described above, in the case of this embodiment, the profile of the first cam 24 (specifically, the shape of the cam nose 241) and the second cam The profile of the cam nose 25 (specifically, the shape of the cam nose 251) is different from that of the cam nose 251 as shown in FIGS. 2 and 3.

The first cam 24 and the second cam 25 are supported by the camshaft 23 such that the center points of the cam noses 241 and 251 are in phase with each other in the circumferential direction of the camshaft 23.

Further, the supercharger 26 supplies compressed air to the combustion chamber 120 under the control of a control section 27, which will be described later. The supercharger 26 may be, for example, a conventionally known supercharger such as a so-called turbocharger or a supercharger. Further, the supercharger 26 may be an electric supercharger.

The control unit 27 controls the operations of electronic devices and the like mounted on the vehicle, including the intake system 2. The control unit 27 is, for example, an electronic control device such as an ECU (Electronic Control Unit) mounted on the vehicle.

In the case of this embodiment, the control unit 27 controls opening and closing of the regulating valve 22 according to the operating status of the internal combustion engine 1. Further, the control unit 27 controls the operation of the supercharger 26. The operation of the control unit 27 will be explained in the explanation of the operation of the intake system 2, which will be described later.

The operation of the intake system 2 will be described below with reference to FIGS. 8 and 9. As described above, the intake system 2 according to the present embodiment has the first intake valve 20 provided at the swirl port 121 of the combustion chamber 120 of the internal combustion engine 1 and the tumble port 122 of the combustion chamber 120, and is in an open state. The second intake valve 21 whose time period (second predetermined time period) is longer than the open state time (first predetermined time period) of the first intake valve 20 and the tumble intake passage 18 connected to the tumble port 122. A regulating valve 22 is provided.

The control unit 27 then controls opening and closing of the regulating valve 22 according to the operating status of the internal combustion engine 1. Specifically, the control unit 27 closes the regulating valve 22 to generate a swirl flow with a high swirl ratio in the combustion chamber 120 and realize the Otto cycle. Furthermore, the control unit 27 opens the regulating valve 22 to realize the Miller cycle while lowering the swirl ratio of the swirl flow in the combustion chamber 120.

FIG. 8 is a flowchart for explaining the operation of the intake system 2. The operation of the intake system 2 begins, for example, when the internal combustion engine 1 is started and ends when the internal combustion engine 1 is stopped. FIG. 9 is a diagram for explaining the relationship between the operating status of the internal combustion engine 1 and the status of the intake system 2. As shown in FIG.

Further, FIG. 9 shows three load regions of the internal combustion engine 1 corresponding to the rotational speed of the internal combustion engine 1 and the torque of the internal combustion engine 1.

Specifically, in FIG. 9, a region with diagonal lines downward to the right indicates a low load region R1 in which the load on the internal combustion engine 1 is low. Further, in FIG. 9, a region marked with diagonal lines downward to the left indicates a high load region R3 in which the load on the internal combustion engine 1 is high. Further, in FIG. 9, a region with a diagonal grid indicates a medium load region R2 in which the load of the internal combustion engine 1 is higher than the low load region R1 and lower than the high load region R3.

As described above, FIG. 9 shows the operating status (load status) of the internal combustion engine determined based on the rotational speed of the internal combustion engine and the torque of the internal combustion engine, and the preset load ranges (low load range R1, medium load range R1, It is also a diagram showing the relationship between the region R2 and the high load region R3.

The control unit 27 stores the information shown in FIG. 9 in advance as a map (hereinafter referred to as "load area map"). That is, the control unit 27 can obtain various information that can be read from FIG. 9 by referring to the load area map.

Note that the low load area, medium load area, and afterload area of the internal combustion engine are, for example, areas that are preset for each vehicle type, and are not limited to the case shown in FIG. For example, the low load region and the medium load region may be determined experimentally based on the smoke concentration in the exhaust gas of the internal combustion engine. Further, the medium load region and the afterload region may be set experimentally based on the volumetric efficiency of the internal combustion engine.

The control unit 27 determines whether the operating condition of the internal combustion engine 1 belongs to a low load region, a medium load region, or an afterload region, and adjusts the adjustment valve according to the result of the determination. Change the state of 22.

Hereinafter, an example of the operation of the intake system 2 will be described with reference to FIG. 8. The main body of the operation shown in FIG. 8 is the control unit 27. Hereinafter, the control executed by the control unit 27 in FIG. 8 will be collectively referred to as intake control.

Note that the flowchart shown in FIG. 8 shows an example of the operation of the intake system 2. For convenience of explanation, some operations of the intake system 2 are omitted in FIG. 8. Therefore, the operation of the intake system 2 is not limited to the operation shown in FIG.

Specifically, in step S101 of FIG. 8, the control unit 27 determines whether the operating condition of the internal combustion engine 1 corresponds to the low load region R1. The control unit 27 obtains the rotation speed of the internal combustion engine 1 and the torque of the internal combustion engine 1. Next, the control unit 27 acquires the operating status of the internal combustion engine 1 based on the acquired rotational speed of the internal combustion engine 1 and the acquired torque of the internal combustion engine 1. Then, the control unit 27 determines whether the obtained operating condition of the internal combustion engine 1 belongs to the low load region R1 based on the load region map stored in advance.

If the operating condition of the internal combustion engine 1 falls within the low load region R1 (YES in step S101 of FIG. 8), the control unit 27 advances the control process to step S102. The operating situation of the internal combustion engine 1 that belongs to the low load region R1 corresponds to the first situation. On the other hand, if the operating condition of the internal combustion engine 1 does not fall under the low load region R1 (NO in step S101 in FIG. 8), the control unit 27 advances the control process to step S103.

In step S102 of FIG. 8, the control unit 27 closes the regulating valve 22 (fully closed state). In step S102 of FIG. 8, if the regulating valve 22 is already in the closed state, the control unit 27 maintains the regulating valve 22 in the closed state.

In step S102 of FIG. 8, when the regulating valve 22 is in the open state, the control unit 27 closes the regulating valve 22 to bring it into the closed state. Thereafter, after completing the control process, the control unit 27 repeats the intake control from step S101.

In step S102 of FIG. 8, when the regulating valve 22 is closed, the intake system 2 enters the state shown in FIG. 5 (also referred to as a low load compatible state).

When the intake system 2 is in a low-load compatible state, intake air is supplied from the swirl port 121 to the combustion chamber 120 . On the other hand, when the intake system 2 is in a low-load compatible state, intake air is not supplied from the tumble port 122 to the combustion chamber 120. That is, intake air is supplied to the combustion chamber 120 only from the swirl port 121 of the swirl port 121 and the tumble port 122.

As a result, a swirl flow with a high swirl ratio is generated in the combustion chamber 120. Furthermore, since the timing at which the first intake valve 20 completely closes is the same as or almost the same as the timing at which the piston 13 reaches the bottom dead center, when the intake system 2 is in a low-load compatible state, the internal combustion engine 1 has a so-called otto The cycle is realized.

The intake system 2 of this embodiment can generate a swirl flow with a high swirl ratio in the combustion chamber 120 when the intake system 2 is in a low-load compatible state, so that the exhaust performance of the internal combustion engine 1 can be improved (that is, smoke (concentration can be lowered) and fuel efficiency can be improved.

In step S103 of FIG. 8, the control unit 27 determines whether the operating condition of the internal combustion engine 1 falls under the medium load region R2. The procedure for this determination is almost the same as the procedure for determination in step S101.

If the operating condition of the internal combustion engine 1 falls within the medium load region R2 (YES in step S103 of FIG. 8), the control unit 27 advances the control process to step S104. The operating situation of the internal combustion engine 1 belonging to the medium load region R2 corresponds to the second situation. On the other hand, if the operating condition of the internal combustion engine 1 does not fall under the medium load region R2 (NO in step S103 of FIG. 8), the control unit 27 advances the control process to step S107.

In step S104 in FIG. 8, the control unit 27 adjusts the opening degree of the regulating valve 22. After that, the control unit 27 advances the control process to step S105.

In step S104 of FIG. 8, when the regulating valve 22 is in the closed state, the control unit 27 opens the regulating valve 22 to bring it into the open state, and adjusts the degree of opening of the regulating valve 22.

Further, in step S104 of FIG. 8, if the regulating valve 22 is already in the open state, the control unit 27 adjusts the opening degree of the regulating valve 22.

In step S104 in FIG. 8, the control unit 27 adjusts the opening degree of the regulating valve 22 so that the fuel efficiency and exhaust performance of the internal combustion engine 1 are optimized. The control unit 27 sets the opening degree of the regulating valve 22 at which the fuel efficiency and exhaust performance of the internal combustion engine 1 are optimized based on a control map stored in advance.

The control map is obtained by experimentally determining the relationship between the operating condition of the internal combustion engine 1 (rotational speed of the internal combustion engine and the torque of the internal combustion engine) and the opening degree of the regulating valve 22 that optimizes fuel efficiency and exhaust performance. This was obtained by

When the opening degree of the regulating valve 22 is adjusted in step S104 in FIG. 8, the intake system 2 enters, for example, the state shown in FIG. 6 (also referred to as a medium load compatible state). In FIG. 6, the regulating valve 22 is in an open state.

When the intake system 2 is in a state corresponding to a medium load, intake air is supplied from the swirl port 121 to the combustion chamber 120 . Further, when the intake system 2 is in a state corresponding to a medium load, an amount of intake air is supplied from the tumble port 122 to the combustion chamber 120 in accordance with the opening degree of the regulating valve 22. That is, when the intake system 2 is in a state corresponding to a medium load, intake air is supplied to the combustion chamber 120 from both the swirl port 121 and the tumble port 122.

As a result, the intake air flowing into the combustion chamber 120 from the swirl port 121 and the intake air flowing into the combustion chamber 120 from the tumble port 122 interfere with each other, and the swirl ratio of the swirl flow in the combustion chamber 120 changes when the combustion chamber 120 is in a state corresponding to a low load. It is smaller than the swirl ratio of the swirl flow in the chamber 120.

Further, the timing at which the first intake valve 20 completely closes is the same as or approximately the same as the timing at which the piston 13 reaches the bottom dead center, but the timing at which the second intake valve 21 completely closes is the timing at which the piston 13 reaches the bottom dead center. Since a predetermined period of time has elapsed since reaching this point, a so-called Miller cycle is realized in the internal combustion engine 1 when the intake system 2 is in a state corresponding to a medium load. The degree of the mirror cycle is determined according to the opening degree of the regulating valve 22. As a result, the intake system 2 according to the present embodiment can improve fuel efficiency in the medium load state of the intake system 2.

In step S105 of FIG. 8, the control unit 27 determines whether or not the supercharger 26 is used. The control unit 27 may determine whether to use the supercharger 26 from the viewpoint of fuel efficiency of the internal combustion engine 1 or the like. In other words, the control unit 27 determines to use the supercharger 26 when the situation is such that the fuel efficiency of the internal combustion engine 1 is improved by using the supercharger 26.

When using the supercharger 26 (YES in step S105 in FIG. 8), the control unit 27 advances the control process to step S106. On the other hand, if the supercharger 26 is not used (NO in step S105 in FIG. 8), the control unit 27 repeats the intake control from step S101 after completing the control process.

In step S106 of FIG. 8, the control unit 27 operates the supercharger 26 to perform supercharging. Compressed air supplied from the supercharger 26 passes through the tumble intake passage 18 and is supplied to the combustion chamber 120 from the tumble port 122.

By supplying compressed air to the combustion chamber 120 by the supercharger, the volumetric efficiency of the internal combustion engine 1 increases, so that the fuel efficiency of the internal combustion engine 1 improves.

In step S107 of FIG. 8, the control unit 27 sets the opening degree of the regulating valve 22 to the maximum opening degree, and brings the regulating valve 22 into a fully open state. After that, the control unit 27 advances the control process to step S108.

Note that between step S103 and step S107 in FIG. 8, a control process may be executed to determine whether the operating condition of the internal combustion engine 1 corresponds to the high load region R3.

However, if the operating condition of the internal combustion engine 1 does not belong to the low load area R1 or the medium load area R2 in the practical operating area R4 (the area surrounded by the dotted line in FIG. 9), which is the practical operating area, the internal combustion engine The operating situation No. 1 belongs to the high load region R3. Therefore, it is not necessary to execute the control process for determining whether or not the operating condition of the internal combustion engine 1 corresponds to the high load region R3. Note that the operating situation of the internal combustion engine 1 that belongs to the high load region R3 corresponds to the third situation.

In step S107 of FIG. 8, when the regulating valve 22 becomes fully open, the intake system 2 enters the state shown in FIG. 7 (also referred to as a high load compatible state).

In step S108 of FIG. 8, the control unit 27 operates the supercharger 26 to perform supercharging. Compressed air supplied from the supercharger 26 passes through the tumble intake passage 18 and is supplied to the combustion chamber 120 from the tumble port 122.

When the intake system 2 is in a high-load compatible state, intake air is supplied to the combustion chamber 120 from both the swirl port 121 and the tumble port 122.

As a result, the intake air flowing into the combustion chamber 120 from the swirl port 121 and the intake air flowing into the combustion chamber 120 from the tumble port 122 interfere, and the swirl ratio of the swirl flow in the combustion chamber 120 changes between the low load compatible state and the medium load state. The swirl ratio is smaller than the swirl ratio of the swirl flow in the combustion chamber 120 in the load corresponding state. Note that the higher the opening degree of the regulating valve 22, the smaller the swirl ratio of the swirl flow in the combustion chamber 120.

Furthermore, in the same manner as in the medium-load compatible state of the intake system 2, when the intake system 2 is in the high-load compatible state, the so-called Miller cycle is realized in the internal combustion engine 1. When the intake system 2 is in a state corresponding to a high load, the regulating valve 22 is opened at its maximum opening degree, so the degree of Miller cycle is also maximized.

In a situation where the Miller cycle is realized, part of the intake air in the combustion chamber 120 may return to the intake side through the tumble port 122 during the compression process of the internal combustion engine 1, and the amount of intake air in the combustion chamber 120 may decrease. There is.

In contrast, the intake system 2 of the present embodiment performs supercharging by the supercharger 26 when the intake system 2 is in a high-load compatible state. As a result, when the intake system 2 is in a high-load compatible state, the required amount of intake air in the combustion chamber 120 can be secured, so that the fuel efficiency of the internal combustion engine 1 can be improved.

(Actions and effects of this embodiment)
In the case of the intake system 2 according to the present embodiment as described above, by adopting a simple configuration in which the state of the regulating valve 22 is adjusted according to the operating situation, the operating characteristics of the internal combustion engine can be adjusted to desired values as described above. can change the state. As a result, according to this embodiment, an intake system for an internal combustion engine that can make the operating characteristics of the internal combustion engine variable can be provided at low cost. Other functions and effects of the intake system 2 according to this embodiment are as described above.

The intake system for an internal combustion engine according to the present disclosure can be applied to various internal combustion engines.

1 Internal Combustion Engine 11 Cylinder Block 12 Cylinder 120 Combustion Chamber 121 Swirl Port 122 Tumble Port 13 Piston 14 Connecting Rod 15 Cylinder Head 16 Injector 17 Swirl Intake Path 18 Tumble Intake Path 2 Intake System 20 First Intake Valve 21 Second Intake Valve 22 Adjustment Valve 23 Camshaft 24 First cam 240 Cam surface 241 Cam nose 25 Second cam 250 Cam surface 251 Cam nose 26 Supercharger 27 Control section 3 Exhaust system 30, 31 Exhaust port R1 Low load range R2 Medium load range R3 High load range R4 Practical driving area

Claims (5)

A first intake valve provided in a swirl port of a combustion chamber of an internal combustion engine;
a second intake valve that is provided at a tumble port of the combustion chamber, and whose open state time is set longer than the open state time of the first intake valve;
a regulating valve provided in the tumble intake passage connected to the tumble port,
generating a swirl flow with a high swirl ratio in the combustion chamber when the regulating valve is closed, and realizing an Otto cycle;
A mirror cycle is realized while lowering the swirl ratio of the swirl flow in the combustion chamber when the adjustment valve is in an open state.
Internal combustion engine intake system. a first cam that opens and closes the first intake valve;
a second cam that opens and closes the second intake valve and has a different profile from the first cam;
further comprising a camshaft which is rotatable, whose movement in the axial direction is restricted, and which supports the first cam and the second cam;
The intake system for an internal combustion engine according to claim 1, wherein the time period during which the second intake valve is opened by the second cam is longer than the time period during which the first intake valve is opened by the first cam. 2. The first cam and the second cam have different cam nose shapes, and are supported by the camshaft such that the center points of the cam noses are in phase with each other in the circumferential direction of the camshaft. The internal combustion engine intake system described in . further comprising a control unit that controls opening and closing of the regulating valve according to operating conditions of the internal combustion engine,
The control unit includes:
closing the regulating valve when the operating condition of the internal combustion engine corresponds to a first condition;
when the operating situation of the internal combustion engine corresponds to a second situation, adjusting the opening degree of the regulating valve according to the operating situation of the internal combustion engine;
When the operating state of the internal combustion engine corresponds to a third situation, the regulating valve is fully opened;
An intake system for an internal combustion engine according to claim 1. The intake system for an internal combustion engine according to claim 4, wherein the control unit controls the supercharger to send compressed air to the combustion chamber when the regulating valve is in an open state.

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