JP2513612Y2 - Stratified combustion internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a stratified combustion internal combustion engine that generates barrel swirl (tumble flow) in a mixture in a combustion chamber.

[Prior Art] Conventionally, an air-fuel ratio rich air-fuel mixture and a lean air-fuel mixture or air are supplied to the combustion chamber of a cylinder in a layered (non-uniform) manner to perform lean combustion as a whole. , A stratified combustion internal combustion engine has been proposed for improving fuel efficiency, reducing CO, or improving knocking performance.

In such a case, a stratified barrel swirl (tumble flow) is generated in the cylinder by the mixed air flow in the cylinder supplied from the two intake ports, and only one of the intake ports eccentric from the center of the cylinder is provided. Injecting fuel, at a position eccentric from the center of the cylinder on the intake port side where the fuel is injected, that is, in a region where the air-fuel ratio is rich, by providing a spark plug, even if the air-fuel ratio is lean, compared to conventional engines, It has been found that a relatively stable combustion can be obtained.

This will be described in more detail with reference to FIGS.
The stratified combustion internal combustion engine shown in FIGS. 5 and 6 is a four-cylinder gasoline engine 1, and each cylinder 2 is provided with two independent intake ports 3 and 4 (intake valves are not shown). A two-valve engine is constructed.

The intake ports 3 and 4 are connected to the branch pipes 5a and 5b of the intake manifold 5, and the intake manifold 5 is connected.
Is connected from a surge tank 5c through a throttle valve 6 to an intake pipe (not shown).

Further, the intake ports 3 and 4 have their plane projection axes Y,
All of X are arranged so as to be substantially orthogonal to the diameter of the cylinder along the center line CL of the engine, so that the intake air is blown toward the combustion chamber 7 obliquely downward with respect to the reciprocating direction of the piston 8. Has become.

An electromagnetic fuel injection valve 9 is provided in one of the intake ports 3, and the cylinder head 2a near the open end of the intake port 3 to which fuel is supplied to each cylinder 2 is further ignited to face the combustion chamber 7. A stopper 10 is provided.

The operation of the thus-configured stratified combustion internal combustion engine will be described. First, during the intake stroke of the engine 1, the air-fuel mixture and air are sucked from the intake ports 3 and 4 as the piston 8 descends, and are introduced into the combustion chamber 7. Be guided. At this time,
Fuel is injected from the fuel injection valve 9 into one of the intake ports 3, and a mixture of air and fuel is sucked into the combustion chamber 7, while only air is sucked from the intake port 4.

Since the plane projection axes Y and X of the intake ports 3 and 4 are orthogonal to the diameter of the cylinder and are located at the left and right symmetrical positions, most of the air-fuel mixture and air taken into the combustion chamber 7 Turn into so-called barrel swirls C and D, which flow in layers separated along the reciprocating direction of the piston 8.

Thus, the intake air sucked into the combustion chamber 7 is compressed in the subsequent compression stroke, and then ignited by the spark plug 10 mounted in the vicinity of the opening end of the intake port 3. Moreover, in the combustion chamber 7, the air-fuel mixture and the air are mixed. Since the layers are rotating while being separated, the air-fuel mixture burns stably.

That is, when the air-fuel mixture supplied from the intake port 3 to the combustion chamber 1 is set to be rich in air-fuel ratio, even a lean air-fuel mixture having a lean air-fuel ratio as a whole together with the air supplied from the intake port 4 is used. Combustion is performed stably.

And such a lean burn is excellent in anti-knock property,
In addition, it contributes to improving fuel efficiency and CO emissions.

Further, conventionally, a control valve or the like (not shown) is provided in either one of the intake ports 3 and 4, and the control valve or the like is used in the engine 1
There is proposed an engine that opens and closes according to the driving state of. That is, in such an engine 1, at the time of low speed operation, the control valve and the like are closed to close one intake port to increase the swirl of the air-fuel mixture supplied to the combustion chamber 7, and at the time of high speed operation, open the control valve and the like. In this state, the two intake ports are opened to enhance the efficiency of filling the air-fuel mixture supplied to the combustion chamber 7.

[Problems to be solved by the device]

However, in such a conventional stratified-combustion internal combustion engine, smoke is generated when fuel is injected into only one intake port, especially under operating conditions where acceleration of fuel is required to be increased outside the lean feedback region such as during acceleration operation. May occur.

Therefore, in order to cope with such acceleration operation, as shown in FIG. 4, the fuel injection valve 9A is separately provided so as to inject fuel toward the respective intake ports of the two-valve engine.
However, this requires two fuel injection valves 9 and 9A, which complicates the mounting position and structure of the fuel injection valve, and also makes the operation complicated and expensive. .

Further, in an engine having a control valve or the like in the intake port as described above, there is a problem that intake air in the intake port is disturbed by the control valve or the like and intake efficiency is reduced. further,
In such an engine, when a large amount of fuel is injected into one of the two air-fuel mixture layers, the air in the cylinder becomes insufficient, resulting in incomplete combustion of the air-fuel mixture, which also causes smoke. It may occur.

The present invention has been made in view of these problems,
In the first operating state in which the engine is operated with a lean air-fuel ratio, by using one fuel injection valve and not ejecting the exhaust gas recirculation gas as assist air toward the fuel injection port, one side is used. It is an object of the present invention to provide a stratified combustion internal combustion engine capable of realizing full intake port injection in a second operating state in which the intake port injection is performed and the engine is operated at an air-fuel ratio richer than the lean air-fuel ratio. .

[Means for solving the problem]

In order to achieve the above-mentioned object, the stratified combustion internal combustion engine of the present invention has two intake ports opening into the combustion chamber of the cylinder of the engine, and the plane projection axis X, of these intake ports.
Y is disposed so as to be substantially orthogonal to the diameter of the cylinder, and the intake air sucked into the combustion chamber from the intake port during the engine intake stroke allows the piston in the cylinder to be operated in the entire operating region of the engine. Intake passage means configured to generate two stratified tumble flows flowing in the reciprocating direction, and a combustion injection direction is directed to a branch portion of the two intake ports so as to supply fuel to the two intake ports. And a fuel injection valve arranged in such a manner that one end communicates with the exhaust passage side of the engine and the other end has an exhaust gas recirculation gas nozzle for ejecting exhaust gas recirculation gas near the fuel injection port of the fuel injection valve. In the first operating state in which the lean air-fuel ratio is operated, the exhaust gas recirculation gas nozzle is configured to direct the fuel injection direction of the fuel injection valve to one of the two intake ports. Exhaust gas recirculation gas is ejected from the fuel injection valve, and in a second operating state in which the engine is operated at an air-fuel ratio that is richer than the lean air-fuel ratio, the fuel injection direction of the fuel injection valve is set to a branch portion of the two intake ports. And an exhaust gas recirculation gas assist device for stopping ejection of the exhaust gas recirculation gas from the exhaust gas recirculation gas nozzle so as to direct it.

[Action]

In the above-described stratified combustion internal combustion engine of the present invention, in the first operating state in which the engine is operated at the lean air-fuel ratio, the fuel injection of the fuel injection valve installed near the branch point upstream of the two branched intake ports is performed. By injecting, for example, exhaust gas recirculation gas from the side of the mouth, the fuel injection valve injects fuel only toward one intake port.

On the other hand, in the second operating state in which the engine is operated at an air-fuel ratio that is richer than the lean air-fuel ratio, the injection of exhaust gas recirculation gas to the fuel injection valve is stopped, so that the fuel injection valve can operate in two intake ports. Fuel is injected toward each.

〔Example〕

Hereinafter, a stratified combustion internal combustion engine as one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic plan view showing the overall configuration of the stratified combustion internal combustion engine, and FIG. FIG. 3 is a schematic plan view showing an injection state, FIG. 3 is a schematic plan view showing a fuel injection state when the exhaust gas recirculation gas is not ejected, and the same reference numerals as those in FIGS. 4 to 6 in FIGS. Is shown.

First, the stratified combustion internal combustion engine according to this embodiment is a four-cylinder gasoline engine 1 as shown in FIG. 1, and an intake passage means 30 is connected to the engine 1. The intake passage means 30 is an intake passage formed of intake ports 3 and 4, and each cylinder 2 is provided with two independent intake ports 3 and 4, thereby forming an intake two-valve engine.

The two intake ports 3 and 4 are connected to the branch pipe 5a of the intake manifold 5, and more
It is configured so that it branches into the crotch. The intake manifold 5 is connected to an air cleaner 13 via an intake pipe 12 via a surge tank 5c and a throttle valve 6.

Further, the openings 3a and 4a (see FIGS. 1 to 3) of the intake ports 3 and 4 have their plane projection axes Y and X (see FIGS. 3 and 4).
Are arranged at an angle that is substantially orthogonal to the diameter of the cylinder 2 along the engine centerline CL direction, and the intake air is directed toward the combustion chamber 7 in the reciprocating direction of the piston 8 (see FIG. 6). It is designed to be blown obliquely downward with respect to the flow direction, so that the flow in the reciprocating direction of the piston 8 in the cylinder 2
Two layered tumble flows can be generated (6th
See figure).

Further, on the upstream side of the intake ports 3 and 4, an electromagnetic fuel injection valve 9 that injects toward the openings of the intake ports 3 and 4 is provided in a part of the intake manifold 5.

Further, each fuel injection valve 9 is directly connected to a fuel delivery pipe 11 at a rear end portion 9c, fuel is supplied through the fuel delivery pipe 11, and an ECU (electronic control unit) connected to an injection connector (not shown). ) 20
The fuel injection amount is controlled by the control signal e from the.

By the way, the engine 1 is provided with an exhaust gas recirculation gas assist device 50. The exhaust gas recirculation gas assist device 50 mainly includes an exhaust gas recirculation gas nozzle 14, a base pipe 15, an EGR valve 16, and an exhaust gas recirculation gas passage 25.

That is, to the side of each fuel injection valve 9, the fuel injection port 9b
The exhaust gas recirculation gas (EGR) injection exhaust gas recirculation gas nozzles 14 capable of changing the fuel injection direction from the front to the front are provided respectively. As shown in FIG. Is ejected toward one of the intake ports 3, and when the ejection is stopped, fuel is ejected toward each of the intake ports 3 and 4, as shown in FIG. That is, depending on the ejection mode of the exhaust gas recirculation gas,
It is configured so that the fuel injection direction can be changed.

The base of each exhaust gas recirculation gas nozzle 14 is a single base pipe.
The base pipe 15 is connected to a part of the exhaust manifold 26 by the exhaust gas recirculation gas passage 25 via the EGR valve 16.

The EGR valve 16 includes a valve portion 16a and a valve portion 16a.
And a differential pressure responsive actuator 16b for driving to open and close.

Further, each exhaust manifold 26 from each combustion chamber 2 is connected to an exhaust passage 27.

Further, in order to control the EGR valve 16, a solenoid valve 17 configured as a three-way switching valve is provided. The solenoid valve 17 is operated by the ECU 20, and the atmospheric pressure from the air cleaner 17a and the pipe 19 are provided. The negative pressure in the surge tank 5c connected by is switched to the above-mentioned atmospheric pressure or negative pressure through the pipe 18 and the EGR valve 16
The actuator 16b is actuated by acting on the actuator 16b. And
When the actuator 16b is operated in this way, the EGR
The valve portion 16a of the valve 16 opens and closes.

Further, the ECU 20 receives a boost signal b from an air flow sensor 21 provided in the air cleaner 13, an engine speed signal c from a crank angle sensor (engine speed sensor) 24 facing the flywheel 23, and the like, In addition to outputting the control signal e to the fuel injection valve 9, the drive signal d is output to the solenoid valve 17, but in the lean feedback region of the engine and the region where the injected fuel flow rate may be relatively low, the solenoid By switching the valve 17 to the negative pressure side, the valve portion 16a of the EGR valve 16 is opened, and in areas other than the above, the solenoid valve 17 is switched to the atmospheric pressure side and the valve portion 16a of the EGR valve 16 is closed. .

Next, the operation of the stratified combustion internal combustion engine according to this embodiment will be described with reference to FIGS.

First, when the engine is operating in the lean feedback region (the first operating state in which the engine is operating at the lean air-fuel ratio), the ECU 20 commands the solenoid valve 17 to the negative pressure side and the EGR valve 16 to operate. The valve portion 16a is opened, and the exhaust gas recirculation gas A is ejected from the exhaust gas recirculation gas nozzle 14. As a result, the fuel injection is directed obliquely downward as shown in FIG. 2 and toward the one intake port 3, and as a result, the fuel is injected toward only one intake port (reference F ₁ Will be referred to). As a result, the air-fuel mixture is blown into one intake port 3 and the air is blown into the other intake port 4.

Therefore, in this first operating state, the fuel is injected only into one of the intake ports 3 by the exhaust gas from the exhaust gas recirculation gas assist device 50, so that a mixture layer is formed from the two intake ports 3 and 4. Two tumble streams are formed in the cylinder 2 with the air layer separated,
By igniting the tumble flow side of the air-fuel mixture among the two tumble flows, the air and the air-fuel mixture in the cylinder can be stably burned. And as a result of this, one intake port 3
The air-fuel ratio of the entire combustion chamber due to the sum of the air-fuel mixture introduced from the air intake system and the air introduced from the other intake port 4 becomes significantly larger than the theoretical air-fuel ratio, and such lean combustion with a significantly large air-fuel ratio is performed. Fuel economy and
There is an effect that CO (carbon monoxide) can be reduced.

Also, in the first operating state in which the air-fuel ratio is operated in the lean air-fuel ratio,
By ejecting the exhaust gas recirculation gas to change the fuel injection direction and promote atomization of the air-fuel mixture, a synergistic effect of reducing NO _X and stabilizing stratified charge combustion can be obtained.

Further, in an area where the engine needs to be accelerated to increase the amount of fuel such as acceleration operation (the second operating state in which the engine is operated at an air-fuel ratio richer than the lean air-fuel ratio), the solenoid valve 17 is set to the atmospheric pressure side. , The valve portion 16a of the EGR valve 16 is closed, and the ejection of the exhaust gas recirculation gas from the exhaust gas recirculation gas nozzle 14 is stopped. As a result, the fuel injection valve 9 is directed obliquely downward in the center as shown in FIG. 3, that is, toward the boundary between the three air ports 3 and 4, and the fuel that is expanded and injected is injected into both the intake ports 3 and 4. Will be injected toward each of the above (see reference code F ₂ ). As a result, the air-fuel mixture is blown into both intake ports 3 and 4.

Therefore, in this second operating state, fuel is injected toward each of the two intake ports 3 and 4 due to the stop of the exhaust recirculation gas injection of the exhaust gas recirculation gas assist device 50, and each of the two intake ports 3 and 4 is injected. By introducing the air-fuel mixture into the combustion chamber 7, a tumble flow of two air-fuel mixture layers is formed in the combustion chamber 7. By igniting these two tumble flows, flames can be propagated throughout the combustion chamber and stable mixed combustion can be carried out, and a high output can be obtained.

Further, when the first operating state is changed to the second operating state in which the air-fuel ratio is richer than the lean air-fuel ratio, the fuel is injected toward each of the two intake ports 3 and 4. It is possible to prevent the air-fuel mixture introduced from one of the intake ports 3 from partially becoming eddy rich, and a large amount of fuel is injected into one of the two air-fuel mixture layers. It is possible to prevent smoke from being emitted due to incomplete combustion.

Further, in the second operating state, even if the three-way catalyst does not function sufficiently due to the air-fuel mixture leaner than the stoichiometric air-fuel ratio, the presence of exhaust gas recirculation gas can significantly reduce NO _X , Further, there is an advantage that the atomization of the fuel is promoted by the ejection of the high temperature exhaust gas recirculation gas and the stratified charge combustion can be more stabilized.

Further, conventionally, by providing a control valve or the like in the intake port, the problem that intake air in the intake port is disturbed and intake efficiency is reduced can be solved.

As described above, according to the stratified combustion internal combustion engine according to the present embodiment, one fuel injection is performed for both the one-side intake port injection region and the both-side intake port injection region of the fuel according to the operating state of the engine. This can be dealt with by changing the injection mode of the exhaust gas recirculation gas A to the valve 9, and this can be easily and easily achieved by attaching the simple exhaust gas recirculation gas assist device 50.

Further, in the first operating state in which the air-fuel ratio is operated at the lean air-fuel ratio, since the exhaust recirculation gas of relatively high pressure assists, the heating effect of the exhaust recirculation gas of the air assist effect further promotes atomization of the fuel. The flammability limit on the lean side expands, and stable lean combustion can be obtained.

Further, since the exhaust gas recirculation gas is introduced into the mixture just before flowing into the combustion chamber, the mixture can be heated without impairing the charging efficiency, and the pumping loss can be reduced.

In the first operating state, by stopping the injection of the exhaust gas recirculation gas to the vicinity of the fuel injection port of the fuel injection valve, the fuel from the fuel injection valve is injected only to one intake port, In the second operating state other than the above, the exhaust gas recirculation gas is injected near the fuel injection port of the fuel injection valve so that the fuel from the fuel injection valve is injected toward each of the two intake ports. Good.

[Effect of device]

As described above in detail, according to the stratified combustion internal combustion engine of the present invention, the exhaust gas recirculation gas nozzle is provided in the vicinity of the fuel injection port of the fuel injection valve, and the exhaust gas recirculation gas injection mode enables
It is possible to perform injection in two directions with one fuel injection valve and to perform injection into one and both of the two intake ports, so that the lean feedback region and the injected fuel flow rate can be achieved with a simple configuration. In the region where the flow rate is relatively low, one-side intake port injection can be used, and in all other regions, full intake port injection can be realized. There is an advantage that it is further promoted.

That is, the intake air sucked into the combustion chamber from the intake port during the intake stroke of the engine can generate two stratified tumble flows that flow in the reciprocating direction of the piston in the cylinder in the entire operating region of the engine. In the first operating state in which the fuel ratio is operated, the fuel gas is injected into only one intake port by the exhaust gas recirculation gas injection of the exhaust gas recirculation gas assist device, so that the air-fuel mixture layer and the air layer are discharged from the two air intake ports. Two tumble streams are formed in the cylinder while and are separated, and of these two tumble streams,
By igniting the air-fuel mixture on the tumble flow side, it is possible to stably burn the air and the air-fuel mixture in the cylinder. As a result, the air-fuel ratio of the entire combustion chamber due to the sum of the air-fuel mixture introduced from one intake port and the air introduced from the other intake port becomes significantly larger than the theoretical air-fuel ratio,
By performing such lean burn with a significantly large air-fuel ratio, there are effects that fuel efficiency can be improved and CO (carbon monoxide) can be reduced.

Also, in the first operating state in which the air-fuel ratio is operated in the lean air-fuel ratio,
By ejecting the exhaust gas recirculation gas to change the fuel injection direction and promote atomization of the air-fuel mixture, a synergistic effect of reducing NO _X and stabilizing stratified charge combustion can be obtained.

On the other hand, in the second operating state in which the air-fuel ratio is richer than the lean air-fuel ratio, such as during acceleration operation, the exhaust recirculation gas assist device stops the exhaust gas recirculation gas injection, and fuel is supplied to each of the two intake ports. Is injected and the air-fuel mixture is introduced into the combustion chamber from each of the two intake ports, so that the tumble flow of the two air-fuel mixture layers is formed in the combustion chamber. By igniting these two tumble flows, it is possible to carry out homogeneous mixed combustion in which the flame propagates throughout the combustion chamber and a stable complete combustion is achieved, and a high output can be obtained.

Further, conventionally, by providing a control valve or the like in the intake port, the problem that intake air in the intake port is disturbed and intake efficiency is reduced can be solved.

Further, when the first operating state is changed to the second operating state in which the air-fuel ratio is richer than the lean air-fuel ratio, the fuel is injected toward each of the two intake ports, thereby It is possible to prevent the air-fuel mixture introduced from the intake port from becoming partially eddy rich.
A large amount of fuel is injected into one of the two air-fuel mixture layers to prevent smoke from being generated due to incomplete combustion.

Further, in the second operating state, even if the three-way catalyst does not function sufficiently due to the air-fuel mixture leaner than the stoichiometric air-fuel ratio, the presence of exhaust gas recirculation gas can significantly reduce NO _X , Further, there is an advantage that the atomization of the fuel is promoted by the ejection of the high temperature exhaust gas recirculation gas and the stratified charge combustion can be more stabilized.

[Brief description of drawings]

1 to 3 show a stratified combustion internal combustion engine as an embodiment of the present invention. FIG. 1 is a schematic plan view showing the overall structure of the stratified combustion internal combustion engine, and FIG. 2 is exhaust gas recirculation gas injection. Is a schematic plan view showing the fuel injection state at the time, FIG. 3 is a schematic plan view showing the fuel injection state when the exhaust gas recirculation gas is not ejected, and FIG. 4 shows the conventional injection state to both intake ports. FIG. 5 is a schematic plan view, and FIGS. 5 and 6 show a conventional stratified-combustion internal combustion engine. FIG. 5 is a schematic plan view showing the entire structure, and FIG. 6 is a perspective view of a combustion chamber. . 1 ... engine, 2 ... cylinder, 2a ... cylinder head,
3,4 …… Intake port, 3a, 4a …… Intake port opening, 5 ……
Intake manifold, 5a, 5b …… Branch pipe, 5c …… Surge tank, 6 …… Throttle valve, 7 …… Combustion chamber, 8 ……
Piston, 9 ... fuel injection valve, 9b ... injection port, 9c ... rear end of fuel injection valve, 10 ... spark plug, 11 ... fuel delivery pipe, 12 ... intake pipe, 13 ... air cleaner, 14 …… Exhaust gas recirculation gas nozzle, 15 …… Base pipe, 16 …… EGR valve, 16a
...... Valve part, 16b ...... Actuator, 17 ...... Solenoid valve, 17a ...... Air cleaner, 18,19 ...... Pipe, 20 ...
… ECU, 21 …… Air flow sensor, 22 …… Boost sensor, 23 …… Flywheel, 24 …… Crank angle sensor,
25 …… Exhaust gas recirculation passage, 26 …… Exhaust manifold, 27
...... Exhaust passage, 30 ...... Intake passage means, 50 ...... Exhaust gas recirculation gas assist device, A ...... Exhaust gas recirculation gas, X, Y …… Plane projection axis of intake port, Z …… Center line of fuel injection valve, F ₁ , F
₂ …… Injected fuel.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 69/00 310 F02M 69/00 310Z 69/04 69/04 R (56) References 61-116026 (JP, A) JP 62-223456 (JP, A) JP 61-201826 (JP, A) JP 61-112773 (JP, A) Actual development Sho 60-102432 (JP, A) U) Actually opened 63-48920 (JP, U) Actually opened 63-71423 (JP, U) Actually opened 61-130717 (JP, U) Actually opened 57-107970 (JP, U) Actually opened 60 -188863 (JP, U)

Claims (1)

(57) [Scope of utility model registration request] 1. An engine has two intake ports that open into a combustion chamber of a cylinder, and the plane projection axes of these intake ports.
Both X and Y are arranged so as to be substantially orthogonal to the diameter of the cylinder, and the intake air sucked into the combustion chamber from the intake port during the engine intake stroke causes the cylinder to enter the cylinder in the entire operating region of the engine. Intake passage means configured to generate two laminar tumble flows that flow in the reciprocating direction of the piston, and a combustion injection direction to branch the two intake ports to supply fuel to the two intake ports. A fuel injection valve disposed so as to be oriented, one end of which is in communication with the exhaust passage side of the engine, and the other end of which has an exhaust gas recirculation gas nozzle for ejecting exhaust gas recirculation gas near the fuel injection port of the fuel injection valve, In the first operating state in which the engine is operated at a lean air-fuel ratio, the exhaust gas recirculation gas nozzle is configured to direct the fuel injection direction of the fuel injection valve to one of the two intake ports. Exhaust gas recirculation gas is ejected from the engine, and in a second operating state in which the engine is operated at an air-fuel ratio that is richer than the lean air-fuel ratio, the fuel injection direction of the fuel injection valve is set to the branch portion of the two intake ports. An exhaust gas recirculation gas assist device for stopping the ejection of the exhaust gas recirculation gas from the exhaust gas recirculation gas nozzle so as to direct it;