JP2011231643A - Intake device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable stratification of an EGR gas by optimally controlling the inflow method of the EGR gas in an internal combustion engine with an intake port divided in two at a low cost.SOLUTION: In an internal combustion engine comprising an EGR gas supply path for supplying an EGR gas to an intake port with a partition wall provided for dividing the intake port into a first intake path and a second intake path, a rotary flow control valve is provided at the inlet of the intake port for adjusting the opening degree of the first intake path and the second intake path. The flow control valve has a second plate part form a closed space in the second intake path with the intake valve of the combustion chamber and the partition wall at the time the inlet of the intake port is fully closed. A first plate part has a gap for supplying fresh air to the first intake path. Thus, the engine can be operated stably even in the case an EGR operation is carried out in a large amount.

Description

  The present invention relates to an intake device of an internal combustion engine (engine) in which an intake port is partitioned by a partition wall, and in particular, an improvement in the distribution of EGR (exhaust gas recirculation) gas and intake air (fresh air) in a combustion chamber. Involved.

  In the invention described in Patent Document 1, each of the intake port and the exhaust port is partitioned by a tumble plate, an intake control valve is provided at the upstream end of the intake side tumble plate, and an exhaust control valve is provided at the downstream end of the exhaust side tumble plate In-cylinder injection internal combustion engines have been proposed. In the present invention, when EGR is introduced, each airflow control valve is closed to control the flow of intake air and EGR gas, and a portion with a lot of air and a portion with a lot of EGR gas are formed in the cylinder. As a result, ignition by the ignition device is performed in a portion where there is a lot of air, and the air-fuel mixture can be reliably ignited. As a result, a large amount of EGR is realized and fuel efficiency is improved.

  In the invention described in Patent Document 2, the intake port is divided into upper and lower parts by a partition plate, and the flow rate of the upper intake port is reduced by the air control valve to suppress the generation of vertical swirl in the combustion chamber, and the lower side A combustion control device for an internal combustion engine, in which an outlet of EGR gas is opened in a lower side wall portion of an intake port, is disclosed. In the present invention, when the EGR is introduced, the air control valve is closed, intake air flows only to the lower intake port, and EGR gas is supplied only to the lower intake port. Thereby, the EGR gas is stratified in the cylinder and stably burned.

JP 2009-41531 A JP 2002-106419 A

In the invention described in Patent Document 1, since the airflow control valve in the exhaust port is exposed to a high temperature, the reliability is lowered. Further, since a plurality of devices for airflow control are provided and a high temperature resistant member is used to control the plurality of devices, the cost increases.
In the invention described in Patent Document 2, the EGR gas flows into the intake port not only in the intake stroke but also in the previous stroke and is mixed with fresh air, so that it is difficult to reliably stratify.

  An object of the present invention is to enable reliable EGR gas stratification at low cost by optimally controlling the inflow method of EGR gas in an internal combustion engine having an intake port divided into two. As a result, an internal combustion engine is provided in which stable operation of the engine is possible even when a large amount of EGR is realized, and fuel consumption can be improved.

  In the invention according to claim 1, in the internal combustion engine provided with an EGR gas supply path for supplying EGR gas to the intake port and provided with a partition wall that divides the intake port into a first intake passage and a second intake passage. A rotary airflow control valve for adjusting the opening degree of the first intake passage and the second intake passage is provided at the inlet of the intake port, and the airflow control valve includes a first plate portion that opens and closes the first intake passage, and a first plate portion. 2 The second plate portion that opens and closes the intake passage, the EGR gas supply path has a blow-out port that blows EGR gas above the second intake passage, and the airflow control valve fully closes the intake port inlet In this case, the second plate portion can form a closed space in the second intake passage by the intake valve and the partition wall of the combustion chamber, and the first plate portion has a gap or a notch for supplying fresh air to the first intake passage. It is characterized by that.

According to a second aspect of the present invention, in the first aspect of the present invention, the first plate portion that opens and closes the first intake passage and the second plate portion that opens and closes the second intake passage are separated from each other and are independent of each other. Control device.
In the invention according to claim 3, the outlet of the EGR gas is set to face the side wall of the combustion chamber through the intake port.

It is a schematic sectional drawing of the intake device of an internal combustion engine. It is a schematic sectional drawing of the intake device of an internal combustion engine. It is a schematic sectional drawing of the intake device of an internal combustion engine. It is a schematic plane sectional view of an intake port. It is a perspective view of an airflow control valve. FIG. 3 is a schematic cross-sectional view of an intake device for an internal combustion engine according to a second embodiment. FIG. 3 is a schematic cross-sectional view of an intake device for an internal combustion engine according to a second embodiment. 10 is a flowchart for explaining the operation of the second embodiment.

  A mode for carrying out the invention will be described together with embodiments shown in the drawings.

  1 is a schematic cross-sectional view of an intake device for an internal combustion engine according to a first embodiment of the present invention, in which C is a cylinder body and CH is a cylinder head. The cylinder head CH is provided with an intake port 2 communicating with the combustion chamber (cylinder) 1 via the intake port 21 and an exhaust port 3 communicating with the combustion chamber 1 via the exhaust port 31. An intake valve 22 and an exhaust valve 32 are installed in the intake port 21 and the exhaust port 31, respectively, and are opened and closed at a predetermined timing according to operations such as an intake stroke, a compression stroke, an ignition stroke, a combustion stroke, and an exhaust stroke of the internal combustion engine. The An ignition device 11 is attached to the ceiling portion of the combustion chamber 1 substantially at the center.

  In this embodiment, the intake port 2 has a horizontally long and substantially rectangular cross section, and a partition wall 23 is provided vertically. The partition wall 23 divides the intake port 2 into two in the flow path direction. The partition wall 23 has a length from the inlet recess 13 of the intake port 2 provided on the side surface 12 of the cylinder head CH to the vicinity of the intake port 21.

  As shown in the AA view, the intake port 2 is partitioned vertically (left and right in the figure) by a partition wall 23 provided in substantially the same plane as the central axis of the combustion chamber (cylinder) 1, and the left side is a first intake passage. 24, the right side is a second intake passage 25. The lower end portion 14 of the inlet recess 13 is set lower than the lower end of the intake port 2 by a predetermined amount (equivalent to the thickness of the airflow control valve 6 described later) from the lower end of the inlet 26 of the intake port 2.

  The internal combustion engine is provided with an EGR passage 4 for supplying EGR gas from the exhaust passage 33 to the intake port 2. The outlet 41 of the EGR passage 4 is provided on the upper wall surface 27 of the second intake passage 25 (intake port 2). An EGR valve 42 is interposed in the EGR passage 4 and is opened and closed according to the operating conditions of the internal combustion engine. The outlet 41 is set above the intake port 21 (intake valve 22) and closer to the center than the intake port 21. Further, the air outlet 41 is formed so as to be inclined from the center side of the combustion chamber (cylinder) 1 through the intake port 21 toward the cylinder liner (combustion chamber side wall) CL.

  An intake control mechanism 5 is installed in the inlet recess 13 of the intake port 2. The intake control mechanism 5 includes an airflow control valve 6 installed in the entrance recess 13, a valve shaft 51 of the airflow control valve 6, and an actuator 52 that rotationally drives the valve shaft 51. The airflow control valve 6 includes a first plate portion 61 that adjusts the opening of the inlet of the first intake passage 24 and a second plate portion 62 that adjusts the opening of the inlet of the second intake passage 25 in FIG. 4.

  As shown in FIG. 5, each of the first plate portion 61 and the second plate portion 62 has a substantially wing cross-sectional shape, the base 63 and 64 having a large diameter on the lower side in the drawing, the tip 65 having an edge shape on the upper side in the drawing, 66. In the first plate portion 61 and the second plate portion 62, the valve shaft 51 passes through the base portions 63 and 64 located at substantially the same position. An actuator 52 (see FIG. 4) is connected to the valve shaft 51, and the valve shaft 51 is rotated in accordance with the operating condition of the internal combustion engine by an engine control unit (ECU), and the airflow control valve 6 is rotated to be second. The opening adjustment of the inlet of the intake passage 25 and the inlet of the first intake passage 24 is performed.

  The front end 65 of the first plate portion 61 is set at a lower position with a gap 29 from the upper end 28 of the inlet of the first intake passage 24 at the closed position of the airflow control valve 6. Further, the tip 66 of the second plate portion 62 substantially coincides with the upper end of the inlet of the second intake passage 25 and seals the inlet of the second intake passage 25 at the valve closing position. That is, the first plate portion 61 is shorter than the second plate portion 62. The formation position, size, and shape of the gap 29 are design factors that differ depending on the shape of the intake port 2. Therefore, depending on the type of the internal combustion engine, whether the gap 29 is provided at the lower end of the inlet of the first intake passage 24 or the first plate portion 61 is provided with a notch or a hole, the same effect as the gap 29 of this embodiment is achieved. Can be realized.

  The operation of the present invention will be described with reference to FIGS. The airflow control valve 6 is set at the fully open position of the two-dot chain line in the figure when the internal combustion engine reaches a predetermined operating condition (for example, at fully open output), and is buried in the wall surface of the intake flow path to obstruct intake problems. Don't be. This is because the lower end portion 14 of the inlet recess 13 is set lower than the lower end of the intake port 2 by an amount equal to the thickness of the air flow control valve 6 from the lower end of the inlet 26 of the intake port 2, and the valve shaft 51 is set to the lower end portion. This is achieved by being located in the vicinity of 14.

  When the operating condition of the internal combustion engine becomes a predetermined condition such as cold start or low speed operation, the actuator 52 is actuated by a signal from the ECU, the valve shaft 51 is rotated, and the air flow control valve 6 is In this way, the inlet 26 of the intake port 2 is set to a position for closing. When the airflow control valve 6 is set to the valve closing position, the second plate portion 62 forms a closed space in the second intake passage 25 between the intake plate 2 and the closed intake valve 2. Similarly, when the operating condition becomes a predetermined condition, the EGR valve 42 is opened, EGR gas flows into the EGR passage, and EGR gas flows into the second intake passage 25.

  During the time other than the intake stroke, as shown in FIG. 2, the intake valve 22 closes the intake port 21, and EGR gas flows into the second intake passage 25 from the EGR passage 4 due to the differential pressure between intake and exhaust. The EGR gas flows in until the pressure in the closed space and the exhaust pressure become parallel, and stays in the second intake passage 25 that is the closed space.

  During the intake stroke, as shown in FIG. 3, the intake valve 22 opens the intake port 21, and the intake air (fresh air) passes through the gap 29 at the tip 65 of the first plate portion 61 and burns from the first intake passage. It flows into the chamber 1. At this time, EGR gas staying in the second intake passage 25 is also sucked into the combustion chamber 1. At the same time, EGR gas from the outlet 41 of the EGR passage 4 set above the second intake passage 25 above the intake port 21 is sucked into the combustion chamber 1.

  As a result, the intake air with less EGR flows as a jet from the first intake passage 24 to the left side of the combustion chamber 1 as shown by the arrow F through the intake port 21. At the same time, the air outlet 41 is set so as to face the cylinder liner (combustion chamber side wall) CR through the air inlet 21. For this reason, intake air with a large amount of EGR gas flows from the outlet 41 of the second intake passage 25 as a jet to the right side of the combustion chamber 1 through the intake port 21 as shown by the arrow E. As a result, the vicinity of the ignition device 11 becomes an atmosphere with a lot of fresh air advantageous for improving the ignitability.

  As shown in FIG. 4, in an internal combustion engine having two intake ports 21, 21 for each cylinder, intake air with less EGR gas and more fresh air as indicated by arrow F, and intake air with more EGR gas as indicated by arrow E. And are mutually intersecting directions, and the flow paths can be separated relatively large. For this reason, the rate at which both interfere or collide is small. Further, since the EGR gas outlet 41 is provided in the upper part of the intake port 2 (above the intake port and on the center side of the cylinder head CH), the intake air with a large EGR indicated by the arrow E is surely provided in the combustion chamber 1. Can be sprayed smoothly and strongly toward the side wall. As a result, an intake tumble (vertical vortex) having a large EGR indicated by an arrow E can be advantageously formed in the vicinity of one side wall of the combustion chamber 1 away from the ignition device 11.

Next, the effects of the present invention will be described.
(When other than the intake stroke)
During the compression, expansion, and exhaust strokes, EGR gas is supplied from the EGR passage 4 to the second intake passage 25 closed by the airflow control valve 6, the partition wall 23, and the intake valve 22. Filled with EGR gas. At this time, since the EGR gas flows into the second intake passage 25 until the pressure in the second intake passage 25 and the exhaust pressure reach an equilibrium state, it is possible to prevent a large amount of EGR gas from staying and Combustion deterioration can be prevented. For this reason, ignition and combustion become smooth, the limit of EGR can be increased, and exhaust gas purification and smooth operation of the internal combustion engine can be ensured.

(In the intake stroke)
When the intake valve 22 is opened during the intake stroke, fresh air flows into the combustion chamber 1 through the gap 29 at the tip 65 of the first plate portion 61 of the airflow control valve 6. At this time, since the flow velocity is increased by being throttled by the gap 29, a strong dumble is formed below the exhaust valve 32 in the combustion chamber 1. On the other hand, EGR gas in the second intake passage 25 also flows into the combustion chamber 1 as the negative pressure in the combustion chamber 1 increases, and mixes with fresh air from the first intake passage 24.

  At this time, the EGR gas is agitated by the dumble flow in the combustion chamber 1 and becomes homogeneous. As the negative pressure in the second intake passage 25 increases, EGR gas is ejected from the EGR passage 4 as a jet. At this time, since the EGR passage 4 is installed on the upper side of the suction port 2 (second intake passage 25) and is directed toward the intake port 21, the jet flows from the cylinder liner CL side of the intake port 21. It flows in and forms a dumble in the combustion chamber 1.

  6 and 7 show Embodiment 2 of an intake device for an internal combustion engine according to the present invention. In this embodiment, in the airflow control valve 6, the first plate portion 61a and the second plate portion 62b are separated, and are rotated by the valve shaft 51a and the valve shaft 51b, respectively. Actuators 52a and 52b are connected to the valve shaft 51a and the valve shaft 51b.

  Under predetermined operating conditions, the actuators 52a and 52b are actuated by the output from the engine control unit ECU, the shaft 51a and the valve shaft 51b rotate independently, and the first plate portion 61a and the second plate The part 62b is set to a predetermined angle. The first plate portion 61a and the second plate portion 62b are connected to the first intake passage 24 and the second intake passage 25 with the end portions of the first plate portion 61a and the second plate portion 62b and the wall surface of the intake port 2, respectively. Create a channel between them. Further, the EGR performs the opening control only when the second intake passage 25 is closed, and blows out EGR gas from the outlet 41 to the second intake passage 25.

The control example of Example 2 is demonstrated with the flowchart shown in FIG.
The engine control unit ECU grasps the state of the engine (71) such as the rotational speed of the internal combustion engine, the coolant temperature, and the opening degree of the accelerator pedal. At the same time, the required driving conditions are determined according to the driver's required torque.

[In the case of operating conditions with low cooling water temperature]
It is discriminated whether or not it is cold start (72), and at the time of cold start, the EGR valve 42 is closed and the first plate portion 61a and the second plate portion 62b are set at a predetermined angle as shown in FIG. (73). As a result, the first intake passage 24 and the second intake passage 25 are both the upper ends of the first plate portion 61a and the second plate portion 62b and the wall surface of the intake port 2 (the first intake passage 24 and the second intake passage). A throttled intake passage is secured between the upper end of each inlet of the passage 25).

[When the cooling water temperature of the internal combustion engine is sufficiently high]
In a condition where the driver does not require a large output, it is determined whether or not the EGR introduction condition is satisfied (74). If the EGR introduction condition is satisfied, the EGR valve 42 is opened by a predetermined opening in order to introduce EGR. Control is performed (75). When the EGR introduction condition is not satisfied, the first plate portion 61a and the second plate portion 62b are fully opened, and the EGR valve is kept closed (76). Further, the first plate portion 61a is opened by a predetermined opening, and the strength of the tumble flow in the combustion chamber 1 is controlled. The second plate portion 62b is fully closed and forms a closed space in the second intake passage 25 (75).

In the configuration of the second embodiment, the first plate portion 61a and the second plate portion 62b are independently controlled to create a flow having a high flow velocity in both the first and second intake passages 24 and 25, so that the start of the water temperature is particularly low. Sometimes, it is possible to promote the vaporization of the fuel adhering to the intake port and reduce the unburned HC in the exhaust gas.
Further, even under EGR introduction conditions, the first plate portion 61a is controlled to an optimum opening degree for each engine operating condition, so that an optimal tumble flow can be formed under a wide range of operating conditions.

  In the intake device for an internal combustion engine of the present invention, this jet is a gas having a high concentration of EGR gas having a low oxygen concentration, and is distributed in the combustion chamber 1 in a layered manner and does not exist in the vicinity of the ignition device 11. Does not affect ignitability. Furthermore, a large amount of EGR gas can be introduced together with the EGR gas that has flowed into the combustion chamber 1 at the previous timing. As a result, since equivalent torque is produced, the intake pressure approaches atmospheric pressure, pump loss can be reduced, and fuel efficiency is improved. Further, the present invention is low in cost because it can be controlled only by installing the airflow control valve 6 and the EGR passage 4 in the intake port 2.

C Cylinder body CH Cylinder head 1 Combustion chamber (cylinder)
2 intake port 21 intake port 22 intake valve 23 partition wall 24 first intake passage 25 second intake passage 26 intake port inlet 29 clearance 3 exhaust port 4 EGR passage 41 outlet 42 EGR valve 5 intake control mechanism 6 air flow control valve 61 first 1 plate part 62 2nd plate part

Claims (3)

In an intake system for an internal combustion engine, provided with an EGR gas supply path for supplying EGR gas to the intake port and provided with a partition wall that divides the intake port into a first intake passage and a second intake passage.
A rotary airflow control valve for adjusting the opening degree of the first intake passage and the second intake passage is attached to the inlet of the intake port, and the airflow control valve opens and closes the first intake passage. A plate portion and a second plate portion for opening and closing the second intake passage,
The EGR gas outlet of the EGR gas supply passage is provided above the second intake passage,
In the air flow control valve, when the inlet of the intake port is fully closed, the second plate portion forms a closed space in the second intake passage with the intake valve of the combustion chamber and the partition, and the first plate The internal combustion engine intake device characterized in that the portion has a gap for supplying fresh air to the first intake passage. The intake device for an internal combustion engine according to claim 1,
Intake of an internal combustion engine, wherein the first plate portion that opens and closes the first intake passage and the second plate portion that opens and closes the second intake passage are separated from each other, and each has an independent control device. apparatus. The intake device for an internal combustion engine according to claim 1 or 2,
An intake device for an internal combustion engine, wherein the EGR gas outlet is set at an upper portion of the second intake passage and is directed to a combustion chamber side wall through an intake port of the internal combustion engine.

Images