JPH11343854A - In-cylinder injection type spark ignition engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize stratified charge combustion and to improve exhaust emission by preventing the sticking of fuel to a piston crown face or the like. SOLUTION: Intake air supplied from a sub-port during stratified charge combustion is heated to a high temperature by a second intake air collector 15 provided on an exhaust manifold 13, and then flows into a combustion chamber 4 to generate a strong reverse tumbling flow and heats a combustion inner chamber inner face such as the crown face of a piston 2 or the like. Fuel sprays injected from a fuel injection valve during a compression stroke are promoted for gasifying by the high temperature reverse tumbling flow and transported to the ignition plug 9 of a combustion chamber center part, while fuel sprays stuck to the crown face of the piston 2 are quickly gasified, thereby stable stratified charge combustion is carried out, unburned HC is reduced, and thus exhaust emission is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a direct injection type spark ignition engine.

[0002]

2. Description of the Related Art An in-cylinder injection spark ignition engine is, for example, as disclosed in Japanese Patent Application Laid-Open No. 6-81651, in which a reverse tumble flow is generated as an in-cylinder gas flow field. Various types are known, such as a type that generates a forward tumble flow as an in-cylinder gas flow field as disclosed in JP-A-86873.

[0003]

In any of the above-mentioned types, since fuel is directly injected from the fuel injection valve into the combustion chamber, the fuel spray is generated during the stratified charge combustion, particularly in the quench region on the piston crown surface or cylinder peripheral surface. Unburned H
It is undeniable that C, smoke and deposits are generated.

Accordingly, the present invention provides an in-cylinder injection spark ignition engine capable of preventing fuel spray from adhering to a piston crown surface or the like, thereby improving the stability of stratified combustion and improving exhaust emissions. is there.

[0005]

According to the first aspect of the present invention, an in-cylinder injection type spark ignition engine having an ignition plug in a combustion chamber and a fuel injection valve for directly injecting fuel into the combustion chamber is provided. A first intake collector connected to the intake port, and a second intake collector provided on the exhaust manifold,
The second intake collector is characterized in that a sub-port is provided in the vicinity of the intake valve of the intake port, the sub-port being connected to the intake port to enhance gas flow in the combustion chamber by intake air supplied from the second intake collector. .

According to a second aspect of the present invention, the second intake collector according to the first aspect communicates with the main intake passage of the first intake collector via a branch passage, and the branch passage and the main intake passage are provided. An open / close control valve is provided on the first and second intake collectors to control the distribution of the intake air to the first intake collector and the second intake collector in accordance with the operation state of the stratified combustion operation and the homogeneous combustion operation. .

[0007] In the invention of claim 3, claims 1 and 2
In the in-cylinder injection spark ignition engine described in (1), the first intake collector is shut off when the engine is under a low load, and the intake is performed from the second intake collector. .

In the invention of claim 4, claims 1 and 2
In the in-cylinder injection spark ignition engine described in (1), the first intake collector side is shut off when the engine is running at a low speed, and intake is performed from the second intake collector side.

In the invention of claim 5, claims 1 to 4 are provided.
The exhaust manifold and the second intake collector described in
The exhaust gas is recirculated from the second intake collector by communicating with an EGR passage provided with a GR control valve.

According to the invention of claim 6, claims 1 to 5 are provided.
Direction of intake air supplied from the subport described in
The present invention is characterized in that a reverse tumble flow is set in the combustion chamber.

According to the invention of claim 7, claims 1 to 5 are provided.
Direction of intake air supplied from the subport described in
The present invention is characterized in that forward tumble flow is set in the combustion chamber.

In the invention of claim 8, claims 1 to 5
Direction of intake air supplied from the subport described in
The swirl flow is generated in the combustion chamber.

According to the ninth aspect of the present invention, the sixth and eighth aspects of the present invention are described below.
In the in-cylinder injection type spark ignition engine described in the above, the ignition plug is disposed substantially at the center of the combustion chamber, and the fuel injection valve is disposed on the side of the combustion chamber on the side of the intake valve, while the piston crown surface Is characterized in that a cavity combustion chamber is provided which is deviated to the side where the intake valve is disposed to preserve the gas flow in the combustion chamber and to hold the fuel spray.

According to a tenth aspect of the present invention, in the cylinder injection type spark ignition engine according to the seventh aspect, the ignition plug is disposed substantially at the center of the combustion chamber, and the fuel injection valve is disposed in the combustion chamber. On the side where the intake valve is arranged, the central part of the piston crown is formed in an arc shape when viewed from the front of the engine and extends in the front-rear direction to preserve the forward tumble flow in the combustion chamber. For providing a recess.

[0015]

According to the first aspect of the present invention, since the gas flow in the combustion chamber can be enhanced by the intake air supplied from the subport, the fuel spray injected in the compression stroke is applied to the strong gas flow to perform the predetermined operation. Of course, the intake air supplied from the subport is heated to a high temperature by the second intake collector provided on the exhaust manifold, so that it is introduced into the combustion chamber during the intake stroke. When this is performed, the combustion chamber surfaces including the piston crown surface are heated by the high-temperature intake air, and therefore, the fuel spray injected in the compression stroke is promoted to be vaporized by the high-temperature intake air, and is formed on the piston crown surface and the like. Even when sprayed, it is instantaneously vaporized and does not adhere to a liquid film, resulting in improved stratified combustion stability, improved exhaust emissions, and improved piston crown surfaces. It is possible to prevent the adhesion of deposit deposition.

[0016] In addition, the vaporization of the fuel spray can be promoted by the high-temperature intake air, and the ignition and the flame propagation can be stabilized. Therefore, the combustible air-fuel ratio can be increased, and the unburned HC can be further reduced. You can also.

Further, even in the homogeneous combustion in which the suction stroke injection is performed, under the operating condition in which the high-temperature intake air is introduced from the subport, the gas flow and the fuel vaporization can be simultaneously performed to increase the combustible air-fuel ratio. Therefore, it is possible to improve fuel efficiency and reduce unburned HC.

According to the invention of claim 2, according to claim 1,
In addition to the effects of the invention, the open / close control valves provided in the main intake passage communicating with the first intake collector and the branch passage communicating with the second intake collector respectively enable the stratified combustion operation and the homogeneous combustion operation to be performed. Since the amount of intake air to the first intake collector and the second intake collector can be appropriately controlled in accordance with the operation state, the stability of combustion and the emission mission in each operation of stratified combustion operation and homogeneous combustion operation can be improved. It can be further improved.

According to the third aspect of the present invention, in addition to the effects of the first and second aspects of the present invention, when the engine has a small intake amount and a low load, the high-temperature intake air is supplied only from the second intake collector through the subport. Is performed, and the gas flow in the combustion chamber is strengthened, so that the stability during low load operation and the exhaust emission can be improved.

According to the fourth aspect of the invention, in addition to the effects of the first and second aspects, the gas flow intensity in the combustion chamber is proportional to the engine speed. High-temperature intake is performed only from the intake collector through the subport, and the gas flow in the combustion chamber is strengthened. Therefore, stability during low-speed operation and improvement in exhaust emission can be achieved.

According to the invention described in claim 5, according to claim 1,
In addition to the effect of to 4 of the invention, not only can suppress the NO _x by the exhaust gas recirculation from the second intake collector side, to be able to further high temperature of intake air supplied from the sub-port, vaporization promotion of the fuel spray Can be further improved.

According to the inventions of claims 6 to 8, in addition to the effects of the inventions of claims 1 to 5, the desired engine concept can be easily adapted by changing the direction of intake from the subport. Can be.

According to the ninth aspect of the present invention, in the engine of the reverse tumble flow concept and the swirl flow concept, the reverse tumble flow or the swirl flow is stored in the cavity combustion chamber on the piston crown surface without causing deformation. The fuel spray injected from the fuel injection valve near the intake valve in the compression stroke by the cavity combustion chamber can be suppressed and diffusion can be suppressed, so that the fuel spray can be reliably transported to the ignition plug at the center of the combustion chamber. As a result, the stability of stratified combustion can be further improved.

According to the tenth aspect of the invention, in the engine of the concept of the forward tumble flow, the forward tumble flow is collected at the center of the combustion chamber by the arc-shaped concave portion at the center of the piston crown surface to cause a shape collapse. The fuel spray can be ignited at the center of the combustion chamber because the recess can provide the effect of receiving the fuel spray injected from the fuel injection valve near the intake valve during the compression stroke and suppress diffusion. The fuel can be reliably transported to the plug, and the stability of stratified combustion can be further improved.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

In FIGS. 1 to 3, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head, 4 is a cylinder block 1, a piston 2 and a cylinder head 3
1 shows a combustion chamber formed by

The cylinder head 3 is provided with two intake ports 5 opened and closed by intake valves 6 and two exhaust ports 7 opened and closed by exhaust valves 8 to face each other.

The center of the cylinder head 3, that is,
A spark plug 9 is disposed at the center of the combustion chamber 4, and the side of the combustion chamber 4 on the side where the intake valve is disposed is located near the two intake valves 6 and 6. A fuel injection valve 10 for directly injecting fuel is provided.

The intake ports 6 and 6 are connected to the branch section 12 of the first intake collector 11, while the exhaust port 7 is connected to the branch section 14 of the exhaust manifold 13.

A second intake collector 15 is formed integrally with the exhaust manifold 13 over a plurality of branches 14.

The cylinder head 3 is provided with subports 16 which are opened near the intake valves of the respective intake ports 5 and are connected to the second intake collector 15 for communication. The flow of gas in the combustion chamber 4 can be enhanced by the intake air.

In this embodiment, the sub-port 16 is opened almost immediately above the intake valve 6, and the intake air supplied from the sub-port 16 is directed to the lower side of the intake valve 6. It flows in along the side surface on the valve arrangement side, descends, and reverses upward at the crown surface of the piston 2 toward the exhaust valve arrangement side, thereby generating a reverse tumble flow in the combustion chamber 4.

A cavity combustion chamber 17 is recessed in a substantially half portion of the crown surface of the piston 2 which is deviated toward the intake valve arrangement side,
The preservation of the reverse tumble flow generated and enhanced in the combustion chamber 4 and the retention of the fuel spray injected from the fuel injection valve 10 during the compression stroke can be enhanced.

In the present embodiment, the second intake collector 15 is connected to the main intake passage 18 of the first intake collector 11 downstream of the throttle valve 19 via a branch passage 20.

The branch passage 20 and the main intake passage 18
Are provided with opening / closing control valves 21 and 22, and the first intake collector 1 is provided in accordance with the operation state of the stratified combustion operation and the homogeneous combustion operation.
The distribution of the amount of intake air to the first and second intake collectors 15 is controlled.

This is achieved by controlling the opening degrees of the open / close control valves 21 and 22 based on, for example, a control map shown in FIG. 9 by a control unit (not shown) so that the first intake collector 11 and the second intake collector are controlled. 15 is performed.

The open / close control valves 21 and 22 are controlled to open and close by a control unit based on detection signals from various sensors such as an accelerator opening sensor and a crank angle sensor (not shown). On the low load side where stratified combustion is performed as shown in FIG.
In the low load region A, intake air is only supplied from the second intake collector 15, and in the medium load region B, intake air is distributed to the second intake collector 15 and the first intake collector 11 according to the load condition. The characteristic is such that intake is performed only from the first intake collector 11 in the high load region C where homogeneous combustion is performed.

On the other hand, the opening / closing characteristics of the opening / closing control valves 21 and 22 due to the engine rotation are such that, as shown in FIG. First in high-speed region 2 where combustion takes place
The characteristic is such that only the intake from the intake collector 11 is performed.

The operation of the open / close control valves 21 and 22 is specifically controlled according to, for example, a flowchart shown in FIG.

In FIG. 10, when detection signals from various sensors such as an accelerator opening sensor and a crank angle sensor are read in step S1, an operation state of stratified combustion or homogeneous combustion is determined based on the detection results in step S2. Is determined.

If it is determined in step S2 that the operation is in stratified charge combustion, the process proceeds to step S3, where the opening degree of the opening / closing control valve 22 on the first intake collector 11 side is set, and step S3 is performed.
4, the opening degree of the opening / closing control valve 21 on the side of the second intake collector 15 is set, and the first intake collector 11 and the second intake collector 11 are set in accordance with the operation states of the load regions A and B shown in FIG. The intake air amount to the collector 15 is appropriately distributed.

If it is determined in step S2 that the combustion operation is the homogeneous combustion operation, the process proceeds to step S5, where the opening / closing control valve 22 on the first intake collector 11 side is fully opened, and in step S6, the operation on the second intake collector 15 side is performed. The opening / closing control valve 21 is fully closed, and air is taken only from the first intake collector 11.

According to the structure of the above-described first embodiment, in the low / medium load, low rotation range where stratified combustion is performed, the subport 16
The gas flow in the combustion chamber 4 can be strengthened by the intake air supplied from the combustion chamber 4, so that the fuel spray injected from the fuel injection valve 10 arranged on the intake valve arrangement side in the compression stroke is put on this strong gas flow, and Of course, the intake air supplied from the subport 16 can be reliably transported to the ignition plug 9 side of the second intake collector 9 provided on the exhaust manifold 13.
5, the inner surface of the combustion chamber 4 including the crown surface of the piston 2 is heated by the high-temperature intake air when introduced into the combustion chamber 4 during the intake stroke. The injected fuel spray is vaporized by the high-temperature intake air, and can be prevented from being immediately vaporized and adhering to a liquid film even when the fuel spray hits the crown surface of the piston 2 or the like.

As a result, the stability of stratified combustion can be improved, the unburned HC can be reduced, the exhaust emission can be improved, and the deposit and deposition on the piston crown surface can be prevented. .

Further, as described above, the high-temperature intake air from the sub port 16 can promote the vaporization of the fuel spray, thereby stabilizing the ignition of the air-fuel mixture by the spark plug 9 and stabilizing the flame propagation. It can be expanded and the unburned HC can be further reduced.

Particularly, in this embodiment, the subport 16
Is opened almost immediately above the intake valve 6, and the sub port 16 is opened.
Is directed to the lower side of the intake valve 6 to generate a strong reverse tumble flow in the combustion chamber 4, and a cavity combustion chamber 17 is provided on the side of the piston crown where the intake valve is disposed. Therefore, when the intake valve 6 is opened during the intake stroke during stratified charge combustion as shown in FIG. 4A, the intake air a from the subport 16 passes below the intake valve 6 and is located on the intake valve arrangement side of the combustion chamber 4. This intake air a is smoothly inverted upward along the ball shape of the cavity combustion chamber 17 on the crown surface of the piston 2 toward the exhaust valve arrangement side. reverse tumble flow a ₁ undisturbed can be generated Te.

In the compression process, (b) and (b) of FIG.
As shown in (c) and (d), the cavity combustion chamber 17
By it is possible to store without being collapsed form an inverse tumble flow a _1, because diffusion holds fuel spray F injected from the fuel injection valve 10 can be suppressed, as shown in FIG. (E) it is possible to improve further the stability of stratified combustion can put the fuel spray F reversed tumble flow a ₁ transports reliably to the spark plug 9 in the combustion chamber center.

As described above, even if the cavity combustion chamber 17 is recessed in the crown surface of the piston 2, the intake a ₁ supplied from the subport 16 is exhausted by the exhaust manifold 13 as described above.
Since the surface of the cavity combustion chamber 17 is already heated by the high-temperature intake air before the fuel injection by the high-temperature intake air, even if the fuel spray F blows on the cavity combustion chamber 17 by the compression stroke injection, the air is immediately vaporized. Thus, the liquid does not adhere to the surface of the cavity combustion chamber 17 in the form of a liquid film, and the generation and adhesion of deposits to the surface of the cavity combustion chamber 17 can be avoided.

On the other hand, when the engine is started or when the warm-up is not completed, the homogeneous combustion operation is performed to maintain the combustion stability. fuel even when the gas flow is weak low engine speed in the chamber 4, which is injected from reinforcing action of the reverse tumble flow a ₁ by hot air from the sub-port 16 in the same manner as described above is obtained, the fuel injection valve 10 in the intake stroke It is possible to positively promote the vaporization of the spray and the diffusion homogenization.

As a result, the combustible air-fuel ratio can be increased for the above-described reason, as well as the combustion stability and the exhaust emission in such an operating range can be improved, so that the fuel consumption can be improved and the unburned HC can be reduced. Can be.

In the first embodiment, the gas flow field in the combustion chamber 4 is set to the reverse tumble flow. However, the opening direction of the subport 16 is set so that the intake air turns horizontally in the combustion chamber 4. Therefore, even when the swirl flow is generated, the preservation of the swirl flow and the retention of the fuel spray by the cavity combustion chamber 17 are improved, so that the stability of stratified combustion is improved and the exhaust emission is improved. Can be.

The second embodiment shown in FIG.
Is arranged such that the intake air a flows in the direction of the exhaust valve disposed in the combustion chamber 4 through the upper side of the intake valve 6, and the strongest order in the combustion chamber 4 is opposite to that of the first embodiment. in which the tumble flow a ₂ was set to be generated.

In this embodiment, in addition to setting the gas flow field in the combustion chamber 4 to the forward tumble flow a ₂ , the piston 2 is formed at the center of the crown surface in an arc shape when viewed from the front of the engine. to form a relatively large recess 23 extends has been the front-rear direction, is as enhanced and storability forward tumble flow a _2, and a holding of the fuel spray is the compression stroke injection by the recess 23 .

That is, the relatively large arc-shaped concave portion 23 is formed in the center of the crown surface of the piston 2, so that the forward tumble flow a ₂ generated in the combustion chamber 4 by the intake from the subport 16 is shaped. Combustion chamber 4 without collapse
Can be collected and stored in the center of the fuel spray, and the effect of receiving the fuel spray injected in the compression stroke by the recess 23 can be obtained to suppress the diffusion. Therefore, the fuel spray can be transferred to the ignition plug 9 in the center of the combustion chamber. It can be transported reliably and the stability of stratified combustion can be further improved.

FIG. 6 shows a third embodiment of the present invention. In this embodiment, the above-described exhaust manifold 13 is used.
And the second intake collector 15 provided on the exhaust manifold 13 through an EGR passage 24 provided with an EGR control valve 25 to recirculate exhaust gas from the second intake collector 15 side. I am trying to make it.

As the EGR control valve 25, a known negative-pressure-operated diaphragm valve is used, and a control unit (not shown) controls the supply of negative pressure from a negative pressure source such as a vacuum pump according to the operation state to appropriately exhaust exhaust gas. The flow rate is obtained.

Therefore, according to the structure of the third embodiment, in addition to the effects of the first and second embodiments,
NO due to exhaust gas recirculation from the second intake collector 15 side
Not to mention that _x can be suppressed, the intake air supplied from the subport 16 can be further heated by the recirculation exhaust gas, and the promotion of vaporization of the fuel spray can be further improved.

In each of the above embodiments, the branch passage 20
And the main intake passage 18 are provided with open / close control valves 21 and 22,
Although the intake air is distributed to the first intake collector 11 and the second intake collector 15, the branch passage 20
May be made larger in diameter than the main intake passage 18 so that the intake distribution control is performed only by the open / close control valve 21 provided in the branch passage 20. It is also possible to connect to the upstream side of the throttle valve 19 to perform the same intake air distribution control as described above.

[Brief description of the drawings]

FIG. 1 is a schematic sectional explanatory view showing a first embodiment of the present invention.

FIG. 2 is a schematic plan explanatory view of the embodiment.

FIG. 3 is a sectional view taken along line AA of FIG. 1;

FIG. 4 is an explanatory diagram showing the behavior of intake air and fuel spray during stratified charge combustion of the embodiment.

FIG. 5 is a schematic sectional explanatory view showing a second embodiment of the present invention.

FIG. 6 is a schematic plan explanatory view showing a third embodiment of the present invention.

FIG. 7 is a characteristic diagram of intake air distribution according to an engine load of an on-off control valve.

FIG. 8 is a characteristic diagram of intake air distribution according to engine rotation of an opening / closing control valve.

FIG. 9 is a control map diagram of an opening / closing control valve.

FIG. 10 is a flowchart of a control system of the on-off control valve.

[Explanation of symbols]

 Reference Signs List 4 combustion chamber 5 intake port 6 intake valve 9 spark plug 10 fuel injection valve 11 first intake collector 13 exhaust manifold 15 second intake collector 16 subport 17 cavity combustion chamber 18 main intake passage 20 branch passage 21, 22 opening / closing control valve 23 recess 24 EGR passage 25 EGR control valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02F 3/26 F02F 3/26 A F02M 35/10 F02M 69/00 310T 69/00 310 35/10 301Q

Claims (10)

[Claims] An in-cylinder injection spark ignition engine having an ignition plug in a combustion chamber and a fuel injection valve for injecting fuel directly into the combustion chamber, a first intake collector connected to an intake port, and an exhaust gas. A second intake collector provided on the manifold, wherein the second intake collector is opened in the vicinity of an intake valve of an intake port so that gas flow in the combustion chamber can be controlled by intake air supplied from the second intake collector. An in-cylinder injection spark ignition engine characterized by communicating and arranging a subport to be strengthened. 2. A second intake collector communicates with a main intake passage of the first intake collector through a branch passage, and an opening / closing control valve is provided in each of the branch passage and the main intake passage so that stratified charge combustion operation and homogeneous combustion are performed. The in-cylinder injection spark ignition engine according to claim 1, wherein the distribution of intake air to the first intake collector and the second intake collector is controlled in accordance with an operation state during operation. 3. The in-cylinder according to claim 1, wherein when the engine is under a low load, the first intake collector is shut off so that intake is performed from the second intake collector. Injection spark ignition engine. 4. The in-cylinder according to claim 1, wherein the first intake collector side is shut off when the engine is running at a low speed, and intake is performed from the second intake collector side. Injection spark ignition engine. 5. An exhaust manifold and a second intake collector communicate with each other through an EGR passage provided with an EGR control valve.
The in-cylinder injection spark ignition engine according to any one of claims 1 to 4, wherein the exhaust gas is recirculated from an intake collector side of the engine. 6. The in-cylinder injection system according to claim 1, wherein the direction of intake air supplied from the subport is set such that a reverse tumble flow is generated in the combustion chamber. Spark ignition engine. 7. The in-cylinder injection system according to claim 1, wherein the direction of intake air supplied from the subport is set such that a forward tumble flow is generated in the combustion chamber. Spark ignition engine. 8. The in-cylinder injection spark according to claim 1, wherein a direction of intake air supplied from the subport is set so that a swirl flow is generated in the combustion chamber. Ignition engine. 9. A spark plug is disposed substantially at the center of the combustion chamber, and a fuel injection valve is disposed on a side of the combustion chamber on the side where the intake valve is disposed. The in-cylinder injection spark ignition engine according to claim 6, wherein a cavity combustion chamber is provided so as to deviate and conserve gas flow in the combustion chamber and retain fuel spray. 10. A spark plug is disposed at a substantially central portion of the combustion chamber, and a fuel injection valve is disposed at a side of the combustion chamber on a side where the intake valve is disposed. The in-cylinder injection spark ignition according to claim 7, wherein a concave portion is formed in an arc shape as viewed from the front and extends in the front-rear direction so as to preserve a forward tumble flow in the combustion chamber. organ.