JPH1026026A - Spark ignition engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily form fuel steam around an ignition plug at the time of low and middle load operation, by closing one intake valve while a valve lift amount is few after two intake valves are simultaneously opened at the time of low and middle load operation, and operating both intake valves in a manner that they are opened and close at the same timing at the time of high load operation. SOLUTION: At the time of high load operation, intake valves 5A, 5B are opened at a predetermined crank angle by a controller 8, and made to suck air by the lowering of a piston 2. At this time, fuel 9 ejected at a predetermined timing is circulated in a combustion chamber 3 by draft, evaporated and diffused during intake and compression strokes so as to form uniform fuel steam, and ignited and burnt by an ignition plug 7 just before the compression stroke is finished. While, at the time of low and middle load operation, when suction is started, the fuel 9 is ejected from an injector 6, and next, the intake valve 5B is closed, thereby draft 12 is formed by air led to flow from the intake valve 5A, and the fuel 9 is kept in the combustion chamber 3, and after that, it is ignited and burnt by the plug 7 just before the compression stroke is finished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spark ignition engine, and more particularly to an intake device for a spark ignition engine having improved ignitability during lean combustion.

[0002]

2. Description of the Related Art In an internal combustion engine, in order to reduce the fuel consumption rate, the proportion of fuel in the fuel / air mixture during low and medium load operation is made smaller than that during high load operation, that is, lean. Attention has been paid to combustion (lean burn).

In order to perform combustion with a small amount of fuel during low and medium load operation, it is necessary to have a fuel vapor having a combustible concentration around the ignition plug at the time of ignition. On the other hand, at the time of high-load operation, it is necessary to make the fuel vapor having a stoichiometric mixture ratio and a uniform concentration exist throughout the combustion chamber.

[0004] For this reason, conventionally, a notched valve is provided in the intake port, and the flow of air flowing into the cylinder is changed by closing the valve. However, in this system, there is a problem that the thickness of the valve becomes the resistance of the intake air when performing the stoichiometric mixture combustion, resulting in a pressure loss, a reduction in the intake air amount, and a reduction in the engine output.

As another means, a dent is provided in a piston, an injector is provided in a cylinder head at an angle for injecting fuel into the dent, and fuel is injected into the dent just before ignition to ignite. I have been. However, this method required a high-pressure injector.

[0006] From such a background, recently, in a two-intake valve type intake device, an intake port for forming a swirl or a port for forming an air-fuel mixture has been provided.
At the time of low and medium load operation, fuel vapor is present around the spark plug. These are described in
JP-189713, JP-A-6-117251, JP-A-2-
No. 267321.

[0007]

SUMMARY OF THE INVENTION The present invention does not require a notched valve in the intake port, does not require a high pressure injector, and does not provide a mixture forming port. It is an object of the present invention to provide a spark ignition engine in which fuel vapor can be easily formed around a spark plug at times.

[0008]

Means for Solving the Problems A first invention of the present invention is:
A fuel injector having two intake ports communicating with the combustion chamber, an intake valve for opening and closing an intake port of the intake port, an injector for injecting fuel above a center of the combustion chamber, and ignition means; In a spark ignition engine having control means for opening and closing a valve, the control means may be configured to open two intake valves simultaneously during low and medium load operation, and then close one of the intake valves while the valve lift is small. , And the two intake valves are similarly opened and closed at the same timing during high-load operation.

A second invention has an intake port communicating with a combustion chamber, a collector upstream of the intake port, a butterfly valve at a connection between the collector and the intake port, A pipe is drawn out of the intake port, and a tip of the pipe is opened in the intake port. An intake valve is provided at a connection portion between the intake port and the combustion chamber, and an injector for injecting fuel above the center of the combustion chamber and ignition A spark ignition engine having control means for opening and closing the intake valve and the butterfly valve at least.
During medium load operation, after opening the butterfly valve and intake valve,
It is characterized in that the butterfly valve is operated so as to close only, and the butterfly valve and the intake valve are opened and closed in the same manner during high load operation.

A third aspect of the present invention has two intake ports communicating with the combustion chamber, one of the intake ports is arranged so that the air flow supplied to the combustion chamber turns, and the two intake ports are provided. A port and a connection portion between the combustion chamber and each having an intake valve,
Spark ignition having an injector for injecting fuel into each of the two intake ports, having ignition means above the center of the combustion chamber, and having at least control means for opening and closing the intake valve and controlling the injector; In the engine, the control means opens the two intake valves at the same time during low and medium load operation, injects fuel from an injector installed in the intake port that does not give a swirl to the airflow,
The two intake valves are closed and operated to stop fuel injection. During high-load operation, the two intake valves are opened and closed in the same manner at the same timing, and fuel is supplied from the injectors installed at each intake port. It is characterized in that it is configured to inject.

[0011] In the first aspect of the present invention, during high load operation, 2
By opening and closing the two intake ports in the same manner at the same timing, the two air flows collide with each other, whereby the flow of the air flows is blocked, and a uniform concentration of fuel vapor can be formed throughout the combustion chamber. . In addition, during low and medium load operation, the two intake ports are simultaneously opened, and only one intake valve is closed while the valve lift is small, so that the fuel vapor is initially located near the center of the combustion chamber when the valve lift is small. Are gathered, and this is included in the swirling flow generated by opening only one of the intake valves, so that a region with a high fuel concentration can be formed near the center of the combustion chamber.

In the second invention, during low and medium load operation, the butterfly valve and the intake valve are opened and then only the butterfly valve is closed, and during high load operation, the butterfly valve and the intake valve are opened and closed in the same manner. By operating, the same state as in the first invention can be created in the combustion chamber.

[0013] In the third aspect of the present invention, during low and medium load operation, two intake valves are simultaneously opened to inject fuel from an injector installed in an intake port that does not impart a swirl to the airflow, and thereafter, two intake valves are provided. To operate to stop the fuel injection, and to open and close the two intake valves at the same timing at the same time during the high load operation, so that the fuel is injected from the injectors installed at the respective intake ports. The first invention or the second invention
A state similar to that at the time of the invention can be created in the combustion chamber.

[0014]

Embodiments of the present invention will be described with reference to the drawings. 1 to 3 are plan views showing the configuration of the spark ignition engine according to the first invention. FIGS. 1 and 3 show a state during low and medium load operation, and FIG. 2 shows a state during high load operation. 1 to 3, a piston 2 is inserted into a cylinder 1 composed of a cylinder head and a cylinder block to form a combustion chamber 3. The intake ports 4A, 4B communicate with the cylinder 1. The intake ports 4A and 4B communicate with the intake manifold. An intake valve 5A is installed in the intake port 4A so as to be openable and closable, and an intake valve 5B is installed in the intake port 4B so as to be openable and closable. The description of the exhaust port and exhaust valve is omitted. An injector 6 and a spark plug 7 are installed in the upper center of the combustion chamber 3. The injector 6 atomizes and injects the fuel 9 in a conical shape so that the injected fuel 9 does not collide with the inner wall of the cylinder 1 or the piston 2 and is easily evaporated. The angle is set toward the center of the chamber 3.

The control device 8 is connected to an air flow sensor, a rotation sensor, and the like for detecting an operation state of the engine, and includes intake valves 5A and 5B, injectors 6, spark plugs 7 and the like.
Are controlled by the control device 8. Each operation can be freely controlled by the control device 8.

FIGS. 4 and 5 are graphs showing the relationship between the crank angle of the automobile engine and the valve lift amount input to the control device 8. 4 shows a low and medium load operation state, and FIG. 5 shows a high load operation state. At the time of high load operation, the intake valves 5A and 5B are set to perform the same operation as shown in FIG. 5, and at the time of low and medium load operation, the intake valves 5A and 5B are set as shown in FIG.
A performs the same operation as during the high-load operation, but the intake valve 5B is set to have a smaller valve lift and close earlier than during the high-load operation.

In the high load operation shown in FIG. 2, the ratio of the amount of air taken into the combustion chamber 3 to the amount of fuel injection, that is, the air-fuel ratio is 15
It is set so that it is a theoretical mixture of the degree. At the ignition timing at the time of high load operation, it is desirable that all the fuel 9 injected into the combustion chamber 3 becomes fuel vapor and that the fuel vapor is uniformly distributed in the combustion chamber 3. Therefore, the fuel 9 is injected at a time when the piston 2 is lowered to some extent during the intake process.
The reason for this is that the liquid film adheres to the piston 2 that is injected too early. On the other hand, if the injection is too slow, the fuel 9 evaporates, and there is not enough time for fuel vapor to be uniformly distributed. It is.

The operation during high load operation will be described. Each condition is set, and the control device 8 opens the intake valves 5A and 5B at a predetermined crank angle, and the piston 2 starts descending and performs intake. The air flow 10 from the intake manifold 4 flows into the combustion chamber 3 through the intake ports 4A and 4B. The fuel 9 injected at a predetermined timing previously input to the control device 8 circulates in the combustion chamber 3 by the airflow 10,
It evaporates and diffuses during the compression process to form uniform fuel vapor in the combustion chamber 3. If the fuel is ignited by the ignition plug 7 just before the end of the compression step, an ideal combustion can be performed because uniform fuel vapor is formed in the combustion chamber 3.

In the low and medium load operation shown in FIG. 1, the air-fuel ratio is set to 20 to 30 in order to improve the fuel efficiency by performing lean combustion in which combustion is performed with a small amount of fuel. Of course,
Since the fuel injection amount is smaller than that during the high load operation, if the fuel vapor is uniformly distributed in the combustion chamber 3, the fuel vapor concentration becomes lean, and the ignition does not occur even when ignited. Therefore, in order to perform lean combustion, it is necessary to collect fuel near the ignition plug 7 and ignite it. In order to collect fuel near the spark plug 7, the fuel 9 is injected while the graphs of the intake valves 5A and 5B of FIG. 4 follow the same line. When the fuel 9 is injected at this timing, the airflow 11 from the intake manifold 4 becomes as shown in FIG.
As shown in FIG. At this time, the angular momentum of the airflow 11 with respect to the central axis of the cylinder 1 cancels out, and the momentum of the airflow 11 is small, so that even if the airflow 11 is mixed with the fuel 9, it cannot be diffused. But,
If the intake air is continued as in the high load operation, the fuel 9 diffuses and the fuel vapor concentration becomes lean. Therefore, when the intake valve 5B is closed as shown in the graph of FIG. 4, air flows only into the intake valve 5A as shown in FIG.
An airflow 12 is formed. Since the airflow 12 flows only from the intake valve 5A, the momentum is large. When the airflow 12 flows into the combustion chamber 3, it flows along the wall surface of the cylinder 1, and therefore has an angular momentum with respect to the center axis of the cylinder 1. At this time, two types of air flows exist in the combustion chamber 3. One is a gas flow 11 having a small momentum and flowing from the intake valves 5A and 5B and mixed with the fuel 9, and a gas flow 12 having a large angular momentum and not being mixed with the fuel. Because the momentum is different like this,
The airflow 12 having a centrifugal force flows along the wall of the cylinder 1 while eliminating the airflow 11 having no centrifugal force, and the airflow 11 containing the fuel 9 stays at the center of the combustion chamber 3.

The operation during low and medium load operation will be described. The controller 8 controls the intake valve 5 at a predetermined crank angle.
When A and 5B are opened and the piston 2 starts descending and starts inhaling, fuel 9 is injected from the injector 6. Then, the airflow 11 flows from the intake manifold 4 into the combustion chamber 3 and the fuel 9
Mix with. At a predetermined timing, the intake valve 5B is closed, and the air flowing from the intake valve 5A forms an airflow 12. The airflow 12 traps the fuel 9 in the combustion chamber 3 as described above. After the intake valve 5A is closed, the airflow 12 weakens but does not disappear, and it is possible to perform lean combustion because the fuel 9 having a combustible concentration is held near the ignition plug 7 immediately before the end of the compression process. it can.

An embodiment of the second invention will be described with reference to FIGS. 6 to 8 are sectional views of the configuration of the spark ignition engine. FIGS. 6 and 8 show low and medium load states, and FIG. 7 shows a high load state. In this embodiment, a collector 14 communicates upstream of the intake port 20, and a butterfly valve 13 is provided at a connection between the intake port 20 and the collector 14. A pipe 15 is drawn from the collector 14,
It is connected to the intake port 20. As shown in FIG. 6, the connection position of the pipe 15 is such that the collector 14 is connected to the pipe 15 by closing the butterfly valve 13 during low and medium load operation.
From the pipe 15 and the jet from the pipe 15
Is the position where Other than this, it is completely the same as the case of FIGS.

The operation during high load operation will be described. The control device 8 opens the intake valve 5 at a predetermined crank angle, and the piston 2 starts descending and performs intake. As shown in FIG. 7, the butterfly valve 13 is fully opened. Then, since the airflow does not flow into the pipe 15, the airflow 10 from the intake port 20 flows into the combustion chamber 3. The fuel 9 injected at a predetermined timing previously input to the control device 8 circulates in the combustion chamber 3 by the airflow 10, evaporates and diffuses during the intake and compression processes, and forms uniform fuel vapor in the combustion chamber 3. To form If the fuel is ignited by the ignition plug 7 just before the end of the compression step, an ideal combustion can be performed because uniform fuel vapor is formed in the combustion chamber 3.

The operation during low and medium load operation will be described. First, as shown in FIG. 8, when the butterfly valve 13 is fully opened, the intake valve 5 is opened, and the piston 2 starts descending, the air flow 1
1 is formed and flows into the combustion chamber 3. Then, fuel 9 is injected from the injector 6. Although the fuel 9 and the gas flow 11 are mixed, the speed and the momentum of the gas flow 11 at the stage when the intake is started are still small, so that even if mixed, the gas flow 11 does not spread much. However, if the intake air is continued as in the high load operation, the fuel 9 diffuses and the fuel vapor concentration becomes lean. Therefore, as shown in FIG. 6, when the fuel 9 and the airflow 11 are mixed and diffusion is not progressing, the butterfly valve 13
Is closed, air flows into the pipe 15 and the airflow 12 is formed. Since the airflow 12 has a smaller diameter than the intake port 20, the airflow velocity increases. Since the airflow 12 flows along the wall surface of the cylinder 1 and the piston 2, it has an angular momentum. At this time, two types of air flows exist in the combustion chamber 3. One is an airflow 11 having no angular momentum and flowing from the butterfly valve 13 and mixed with the fuel 9, and the other is an airflow 12 having an angular momentum and not mixed with the fuel. Because of such a difference in momentum, the airflow 12 having a centrifugal force and forming a swirling flow flows along the wall surface of the cylinder 1 while eliminating the airflow 11 having no centrifugal force, and the airflow 11 containing the fuel 9 flows into the combustion chamber 3. Will stay at the center of the After the intake valve 5 is closed, the airflow 12 is weakened but not extinguished, and near the end of the compression process, the fuel 9 having a combustible concentration is held near the ignition plug 7 to enable lean combustion. Can be.

An embodiment of the third invention will be described with reference to FIGS. 9 to 11 are sectional views of the configuration of the spark ignition engine. FIGS. 9 and 11 show low and medium load states, and FIG. 10 shows a high load state. In this embodiment, two intake valves 5
Independent intake ports 4A and 4B for A and 5B
And the injectors 6A and 6B. Intake port 4
A is obliquely attached to the air flow 10A flowing into the combustion chamber 3 so as to give a swirl component, and has a slightly larger diameter than the intake port 4B. This is to make a difference in the flow rate of air with respect to the intake port.
This is to give a flow stronger than 0B. Injector 6
A and 6B indicate that the injected fuel 9A and 9B is the intake port 4
Fuel 9 so that it does not adhere to A and 4B and is easy to evaporate.
A and 9B are atomized in a conical shape and injected, and the angles are set so that the fuels 9A and 9B are parallel to the airflow flowing through the intake ports 4A and 4B.

The operation during high load operation will be described. In this embodiment, a case will be described in which the fuel injection ratio of the injectors 6A and 6B is 1: 1. The control device 8 opens the intake valves 5A and 5B at a predetermined crank angle, and the piston 2 starts descending and performs intake. At the same time, fuels 9A and 9B are injected from injectors 6A and 6B. The intake port 4A forms an airflow 10A, and the intake port 4B
0B flows into the combustion chamber 3 so as to form 0B. The fuel 9A mixes with the airflow 10A, and the fuel 9B flows into the combustion chamber 3 while mixing with the airflow 10B. The fuels 9A and 9B evaporate and diffuse during the intake and compression steps, forming uniform fuel vapor in the combustion chamber 3. Immediately before the end of the compression process, the spark plug 7
When the fuel is ignited, uniform fuel vapor is formed in the combustion chamber 3, so that ideal combustion can be performed.

The operation during low and medium load operation will be described. In response to a command from the control device 8, the intake valves 5A and 5B open at a predetermined crank angle, and the piston 2 starts descending and performs intake. The difference from the high load operation is that the fuel 9 is injected only from the injector 6B as shown in FIG. The intake port 4A forms an airflow 10A, and the intake port 4B flows into the combustion chamber 3 so as to form an airflow 10B. The fuel 9 flows into the combustion chamber 3 while mixing with the airflow 10B. When the airflow 10A flows into the combustion chamber 3, the cylinder 1
And has angular momentum with respect to the central axis of the cylinder 1. Since the air flow 10B containing the fuel 9 has a small angular momentum, the air flow 10A flowing along the cylinder 1 wall is in a state where the air flow 10B is excluded and pushed toward the center. As shown in FIG. 9, even if the intake valves 5A and 5B are closed and the inflow of air from the intake ports 4A and 4B is stopped,
The momentum 2 is weakened but not extinguished. Since the fuel 9 having a combustible concentration is held near the ignition plug 7 immediately before the end of the compression step, lean combustion can be performed.

According to the third aspect, the injector 6 provided in the intake port 4B installed at an angle where it is difficult to form a swirling flow in the direction of the center of the combustion chamber during low and medium load operation.
By injecting fuel from B and not injecting fuel from an injector 6A provided in an intake port 4A installed so as to easily form a swirling flow in the combustion chamber, the airflow flowing along the wall surface of the combustion chamber is reduced. No fuel is contained, and fuel vapor can be retained and ignited near the spark plug. In this method, the pressure loss is small because no valve is provided in the intake port.

[0028]

According to the present invention, the ignitability at the time of lean combustion can be improved without requiring a high-pressure injector.

[Brief description of the drawings]

FIG. 1 is a plan view of a spark ignition engine according to a first embodiment of the present invention during low-load operation.

FIG. 2 is a plan view of the spark ignition engine according to the first embodiment of the present invention during a high-load operation.

FIG. 3 is a plan view of the spark igniter according to the first embodiment of the present invention during a low load operation.

FIG. 4 is a graph showing a relationship between a valve lift amount and a crank angle during a low load operation according to the first embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a valve lift and a crank angle during a high-load operation according to the first embodiment of the present invention.

FIG. 6 is a cross-sectional view of the spark ignition engine according to the second embodiment of the present invention at the time of low load operation.

FIG. 7 is a cross-sectional view of the spark ignition engine according to the second embodiment of the present invention at the time of high load operation.

FIG. 8 is a sectional view of a spark ignition engine according to a second embodiment of the present invention during a low load operation.

FIG. 9 is a plan view of the spark ignition engine according to the third embodiment of the present invention at the time of low load operation.

FIG. 10 is a plan view of a spark ignition engine according to a third embodiment of the present invention during a high-load operation.

FIG. 11 is a plan view of a spark ignition engine according to Embodiment 3 of the present invention during a low load operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cylinder, 2 ... Piston, 3 ... Combustion chamber, 4 ... Intake manifold, 4A, 4B ... Intake port, 5, 5A, 5B
... intake valves, 6, 6A, 6B ... injectors, 7 ... spark plugs, 8 ... control devices, 9 ... fuel, 10, 11, 12 ... airflow, 13 ... butterfly valves, 14 ... collectors, 15 ... pipes, 20 ... intake port.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location F02D 13/02 F02D 13/02 H 41/04 310 41/04 310C 41/34 9523-3G 41 / 34 C F02M 69/00 360 F02M 69/00 360 G

Claims (3)

[Claims] 1. An intake valve communicating with a combustion chamber, an intake valve for opening and closing an intake port of the intake port, an injector for injecting fuel above a center of the combustion chamber, and ignition means. In a spark ignition engine having at least control means for opening and closing the intake valve, the control means opens the two intake valves at the same time during low and medium load operation, then sets one of the intake valves to a valve lift amount. A spark ignition engine characterized in that it is operated so as to close during a short period of time and to open and close two intake valves in the same timing at the same timing during a high load operation. 2. An intake port communicating with a combustion chamber, a collector upstream of the intake port, a butterfly valve at a connection between the collector and the intake port, and a pipe extending from the collector. A leading end opening in the intake port, an intake valve at a connection between the intake port and the combustion chamber, an injector for injecting fuel above the center of the combustion chamber, and ignition means. In a spark ignition engine having at least control means for opening and closing the intake valve and the butterfly valve, the control means may be configured to open the butterfly valve and the intake valve during low and medium load operation, and then close only the butterfly valve. A spark ignition engine characterized in that the butterfly valve and the intake valve are opened and closed in the same manner during high load operation. 3. An intake port communicating with a combustion chamber, wherein one of the intake ports is arranged so that an air flow supplied to the combustion chamber is swirled, and the two intake ports and the combustion port are provided. An intake valve at a connection with the chamber; an injector for injecting fuel into each of the two intake ports; an ignition means above a center of the combustion chamber; and at least an opening / closing operation of the intake valve And a control means for controlling the injector, the control means comprising: an injector installed at an intake port that opens two intake valves simultaneously during low and medium load operation and does not impart a swirl to the airflow; From the fuel, then close the two intake valves, operate to stop the injection of fuel, during high load operation, open and close the two intake valves at the same timing at the same time, respectively Spark ignition engine, characterized by being configured so as to inject fuel from the installed injector to the intake port.