JPH0941976A - Cylinder fuel injection type internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To depend on an efficient fuel injection and a lean combustion without resting on an engine speed, in this cylinder fuel injection type engine made up so as to burn an air-fuel mixture in a state of being stabilized. SOLUTION: This internal combustion engine is provided with a combustion chamber 7 formed in space between the topside of a piston 2 to be inserted into a cylinder 3A and the underside of a cylinder head 1, an intake valve 9 to be installed on an underside of this cylinder head 1 at one side holding a virtual plane inclusive of a cylinder axis P between, an exhaust valve 8 to be installed on an underside of the cylinder head 1 at the other side as holding this virtual plane in between, and a fuel injection valve 10 being installed in space between the intake valve 9 and the exhaust valve 8 as being tilted to the side of the exhaust valve 8, and spraying fuel toward the piston topside. In addition, it is also provided with a spark plug 11 being installed in a cylinder head part at the opposite side to this fuel injection valve 10 in holding an axis L of the intake valve 9 between.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder injection type internal combustion engine for directly injecting fuel into a combustion chamber, and more particularly to a cylinder injection type internal combustion engine for burning a lean mixture in a stable state. Regarding

[0002]

2. Description of the Related Art Conventionally, as a fuel injection type gasoline engine, an engine in which fuel is injected into an intake port by an injector to supply the fuel is often used. In such an engine, in the intake port,
The inhaled air and fuel are mixed and ignited and burned in the combustion chamber.

On the other hand, in a diesel engine which mainly uses light oil as a fuel, fuel is directly injected into the combustion chamber, and the fuel is spontaneously ignited by compressed air in the combustion chamber to obtain power. By the way, also in the gasoline engine as described above, a cylinder injection type internal combustion engine that directly injects fuel into the combustion chamber to improve the responsiveness of the engine (for example, Japanese Patent Laid-Open No. 146886/1994 and Japanese Utility Model Publication No. No. 52334) is proposed.

The in-cylinder injection type gasoline engine disclosed in Japanese Unexamined Patent Publication No. 6-146886 requires a spark plug as an ignition means, and the arrangement of parts around the cylinder head is different from that of a diesel engine. . For example, as shown in FIGS. 7, 8 and 9, an upright intake port 101, a fuel injection valve 102 arranged on the intake side, and a curved combustion chamber 103 that is close to the intake side are formed. Piston 104 and 4 valves (2 exhaust valves, 2 intake valves)
A spark plug 106 arranged in the center of the valve) is provided, and by switching the injection timing for injecting fuel toward the upper surface of the piston 104, an operation in which the fuel concentration distribution in the cylinder is controlled is performed.

Further, Japanese Utility Model Laid-Open No. 3-52334 discloses that
A cylinder injection type internal combustion engine of a two-cycle engine is shown. In order to improve scavenging efficiency, a reverse tumble flow from the upper surface of the piston to the ignition plug through the lower surface of the cylinder is provided, and the piston is near the bottom dead center. In the above condition, the fuel is injected toward the upper surface of the piston from the fuel injection valve that is installed between the intake and exhaust valves of the cylinder head, and the premixing can be promoted.

[0006]

However, the former engine has a problem that the spray wall surface control in the curved combustion chamber 103 can be performed only in the latter half of the compression stroke in which the piston 104 is relatively close to the compression top dead center. That is, when the pressure-accumulation injector is operated by electronic control, the fuel is injected in the combustion chamber 1 because the piston 104 causes fuel injection at a raised crank angle in the medium and low speed range, as shown in FIG.
Although the fuel is efficiently injected in 03, it is necessary to complete the fuel injection in a short time in the high speed range, so it is necessary to perform the fuel injection in the first half of the compression stroke.

In such a case, as shown in FIG.
The fuel is injected at the position where the piston 104 is lowered, and the fuel is injected outside the combustion chamber 103, so that the fuel spray is not captured by the control wall surface of the piston and is scattered throughout the combustion chamber. , Can not be stratified. When the ignition operation as shown in FIG. 9 is performed in such a state, since the air-fuel mixture is dispersed around the spark plug 106, efficient combustion cannot be performed, and the ultra-lean air-fuel mixture is not produced. The problem arises that combustion does not work.

Further, in the latter engine, the fuel is injected downward near the bottom dead center of the piston, so that the fuel is dispersed in the cylinder and mixing is promoted. As a result, stable combustion under lean conditions is achieved. There is a problem that you cannot get it. The present invention
The present invention has been made in view of such problems, and an object thereof is to provide a cylinder injection internal combustion engine capable of performing efficient fuel injection and lean combustion regardless of the engine speed.

[0009]

For this reason, in the cylinder injection type internal combustion engine of the present invention as defined in claim 1, the combustion formed between the upper surface of the piston fitted in the cylinder and the lower surface of the cylinder head. Chamber, an intake valve provided on one side of the lower surface of the cylinder head that forms the combustion chamber with a virtual plane including the cylinder axis interposed therebetween, and an exhaust valve provided on the lower surface of the cylinder head with the virtual plane interposed therebetween. And a fuel injection valve that is provided between the intake valve and the exhaust valve so as to be inclined toward the exhaust valve and injects fuel toward the upper surface of the piston, and the fuel injection valve with the axis of the intake valve interposed therebetween. And a spark plug arranged in the cylinder head portion on the opposite side.

According to a second aspect of the present invention, there is provided an in-cylinder injection internal combustion engine according to the first aspect, wherein the fuel injection valve is inclined substantially parallel to the axis of the exhaust valve. It has a feature. Furthermore, the cylinder injection type internal combustion engine of the present invention according to claim 3 is the engine according to claim 1,
On the upper surface of the piston located on the one side, a recess having a downward convex curved surface is formed in a plan view orthogonal to the cylinder axis in order to promote the vortex flow of the intake air, and the fuel injection valve is formed in the recess. It is characterized in that the fuel is injected toward the spark plug and the fuel is reflected by the recess so as to face the spark plug.

According to a fourth aspect of the present invention, there is provided an in-cylinder injection internal combustion engine according to the first aspect of the present invention, wherein the ignition plug has a tip at the compression top dead center of the piston. It is characterized in that it is arranged in the recess. A cylinder injection type internal combustion engine according to a fifth aspect of the present invention is the engine according to the first aspect, further comprising: a combustion chamber formed between an upper surface of a piston fitted into a cylinder and a lower surface of a cylinder head. An intake valve provided on one side of the lower surface of the cylinder head forming the combustion chamber with a virtual plane including the cylinder axis interposed therebetween, an exhaust valve provided on the other side of the virtual plane with the exhaust valve located on the one side A recess formed on the upper surface of the piston so as to exhibit a downward convex curved surface in a plane view orthogonal to the cylinder axis in order to promote intake vortex flow,
While being provided between the intake valve and the exhaust valve,
A fuel injection valve for injecting fuel toward the recess, and an ignition plug provided on the cylinder head located on the opposite side of the fuel injection valve with the axis of the intake valve interposed therebetween. It has a feature.

Further, the cylinder injection type internal combustion engine of the present invention according to claim 6 is the engine according to any one of claims 1 to 5, wherein an intake system opened and closed by the intake valve is provided in the combustion chamber. It is characterized in that the intake air flow introduced is formed so as to form a vertical vortex flow from the lower surface of the cylinder head through the upper surface of the piston toward the spark plug.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A cylinder injection type internal combustion engine as an embodiment of the present invention will be described below with reference to the drawings. FIG.
Is a schematic front view showing the lower surface of the cylinder head, FIG.
4 is a schematic diagram showing its operating state, and FIG. 5 is a graph showing its combustion characteristics.

As shown in FIG. 1, this cylinder injection type internal combustion engine has an engine body composed of a cylinder head 1 and a cylinder block 3, and a piston 2 is inserted into a cylinder 3A of the cylinder block 3. ing. Also,
As shown in FIG. 2, the cylinder head 1 of this internal combustion engine is provided with two intake valves (see reference numerals 9 and 9 in FIG. 2) and two exhaust valves (see reference numerals 8 and 8 in FIG. 2) in each cylinder. It is configured as a valve type internal combustion engine.

A combustion chamber 7 is formed between the upper surface of the piston 2 and the lower surface 1A of the cylinder head 1. The cylinder head 1 portion of the combustion chamber 7 is a standard type of intake passage which is not upright. The intake port 4 and the exhaust port 5 of the exhaust passage are communicatively connected. Further, an intake valve 9 and an exhaust valve 8 are installed in the combustion chamber openings 4A and 5A of the intake and exhaust ports 4 and 5, respectively, and the combustion chamber openings 4A and 5A are provided by the intake and exhaust valves 9 and 8, respectively. It is designed to be opened and closed.

Here, the intake valve 9 has a virtual plane P including the cylinder axis on the lower surface of the cylinder head 1 forming the combustion chamber 7.
The exhaust valve 8 is provided on one side of the cylinder head 1 on the other side across the virtual plane P.
Further, the fuel injection valve 10 is provided between the intake valve 9 and the exhaust valve 8 so as to be inclined toward the exhaust valve 8 side, and the piston 2
Is configured to inject fuel toward the upper surface of the.

Further, the spark plug 1 is provided in the cylinder head portion opposite to the fuel injection valve 10 with the axis L of the intake valve 9 interposed therebetween.
1 is provided. Since the fuel injection valve 10 is installed so as to be inclined substantially parallel to the axis M of the exhaust valve 8, the fuel pipe (not shown) is separated from the exhaust port 5 side,
It can be mounted on the upper surface side of the cylinder head 1 which is unlikely to become hot. Further, as shown in FIG. 6, after the fuel injection hole 10A and the exhaust valve guide hole 8A are fixed in the machining step by using the cylinder head mounting jig 105 that matches the inclination angle, the hole is machined. Then, they are formed in the same process.

Further, in order to promote the vortex flow of the intake air on the upper surface of the piston 2 located on one side, a recess 13 having a downwardly convex curved surface in a plan view orthogonal to the cylinder axis is formed, and the fuel injection valve 10 Are configured to inject fuel toward the recess 13. As a result, this piston 2
Forms an intake side curved curved combustion chamber-shaped piston.

Further, the wall surface 12 of the recess 13 is arranged so as to reflect and guide the injected fuel and direct the injected fuel toward the spark plug 11. The spark plug 11 is arranged so that its tip reaches the recess 13 at the compression top dead center of the piston 2. Further, the intake system opened and closed by the intake valve 9 forms a longitudinal vortex flow (forward tumble flow) in which the intake flow introduced into the combustion chamber 7 is directed from the cylinder head lower surface 1A to the piston 2 upper surface toward the spark plug 11. Is configured to let.

Here, the intake system is formed by the intake port 4 and the combustion chamber 7, and is constructed so as to generate a forward tumble flow in the counterclockwise direction in FIG. 1 depending on the shape and the extending direction of these. There is. With the configuration as described above, the operation shown in FIG. 3 is performed. That is, when the engine is operated in the high speed range, fuel injection from the fuel injection valve 10 is performed in the first half of the compression stroke in which the piston 2 is relatively downward.

At this time, the fuel injection valve 10 injects fuel from the central position on the lower surface of the cylinder head 1. Here, since the fuel injection valve 10 is installed so as to incline toward the exhaust valve 8 side and the recess 13 is formed on the upper surface of the piston 2 on the intake valve 9 side, the injected fuel is injected into the recess 13. I will be heading.

After reaching the recess 13, the wall surface 1
2 and is repulsed at an acute angle, the injected fuel is guided to the position of the spark plug 11, as shown in FIG.
A rich mixture is formed immediately before ignition. In this state, the ignition operation is performed by the spark plug 11, so that efficient combustion is performed.

By the way, the intake air flows into the combustion chamber 7 through the combustion chamber opening 4A, but depending on the direction of the inflow, the velocity component, and the shape of the combustion chamber 7, a vertical vortex flow is generated as indicated by an arrow X in FIG. appear. That is, a tumble flow in the forward direction (counterclockwise in the figure) is generated to assist the fuel transportation and efficiently reach the position of the spark plug 11 while being efficiently mixed with the injected fuel injected from the fuel injection valve 10. Becomes

As a result, sufficient mixing and stratification with the fuel are achieved, and stable combustion is performed even in the high speed operation of the engine. By the way, considering the operation of the engine in the medium to low speed range, in such a speed range,
Fuel injection is performed from the fuel injection valve 10 in the latter half of the compression stroke (see the position in FIG. 4 for the piston position), whereby the injected fuel is also guided to the position of the spark plug 11 immediately before ignition. A rich mixture is formed, which results in stable engine combustion.

Such improvement in combustion characteristics is considered in the graph shown in FIG. That is, in FIG. 5, the abscissa represents the air-fuel ratio, and the ordinate represents the indicated mean effective pressure and combustion fluctuation rate, showing the respective characteristics. The dotted line in the figure shows the case of the conventional intake pipe injection, the dashed line shows the case of the structure shown in FIGS. 6 and 7, and the solid line shows the case of the present embodiment.

As can be seen from the figure, in the case of this embodiment, a stable indicated mean effective pressure is obtained up to the lean side, and the combustion fluctuation rate is also kept low until lean operation, so that stable lean operation is realized. To be done. In this way, the standard intake port 4 is provided, and the injection valve 10 is arranged in the center of the combustion chamber 7 slightly tilted toward the exhaust side with respect to the intake side curved curved combustion chamber-shaped piston 2, and the spark plug 11 is arranged from the intake side. By adopting the inclined arrangement, it is possible to cause the fuel spray to collide with the piston 10 during the compression stroke and control the fuel concentration distribution in the cylinder, so that the combustion stability in the high-speed operation range is improved, and this speed is improved. Super lean burn operation is possible in all operating ranges including the range, and fuel efficiency is improved.

Further, the fuel injection hole 10 for the fuel injection valve 10
Since A and the exhaust valve guide hole 8A can be formed in the same process, the number of man-hours required for manufacturing (man-hours for cutting) can be reduced, and the cost can be reduced.

[0028]

As described in detail above, according to the cylinder injection type internal combustion engine of the present invention as defined in claim 1, it is formed between the upper surface of the piston fitted into the cylinder and the lower surface of the cylinder head. A combustion chamber, an intake valve provided on one side of a lower surface of a cylinder head forming the combustion chamber with a virtual plane including a cylinder axis interposed therebetween, and an intake valve provided on the lower surface of the cylinder head on the other side of the virtual plane. An exhaust valve, a fuel injection valve that is provided between the intake valve and the exhaust valve and is inclined toward the exhaust valve side, and injects fuel toward the upper surface of the piston;
The fuel injection valve is sandwiched across the axis of the intake valve, and the ignition plug is arranged in the cylinder head portion on the opposite side, and the combustion stability in the high-speed operation range is improved. There is an advantage that fuel consumption can be improved by enabling ultra lean burn operation in the entire operation range including the speed range.

According to the cylinder injection type internal combustion engine of the present invention as defined in claim 2, in the engine according to claim 1, the fuel injection valve is inclined substantially parallel to the axis of the exhaust valve. With such a simple configuration, the fuel injection hole for the fuel injection valve and the exhaust valve guide hole can be formed in the same step, so that the number of steps is reduced and the cost is reduced. Furthermore, according to the cylinder injection type internal combustion engine of the present invention as set forth in claim 3, in the engine as set forth in claim 1, the cylinder axis and the cylinder axis are provided on the upper surface of the piston located on the one side to promote the swirling flow of intake air. Is formed with a downwardly convex curved surface in the orthogonal view, and the fuel injection valve injects fuel toward the recess and the fuel is reflected by the recess toward the spark plug. It is possible to form a rich air-fuel mixture near the spark plug through the recess with a simple configuration that is installed in the. It is possible to perform ultra-lean combustion operation in the entire operation range including the above, and there is an advantage that fuel consumption is improved.

According to the cylinder injection type internal combustion engine of the present invention as defined in claim 4, in the engine as defined in any one of claims 1 to 3, the tip of the spark plug at the compression top dead center of the piston. Is disposed in the recess, and the spark plug is disposed at a position where a rich air-fuel mixture is formed via the recess, which improves combustion stability in the high-speed operation range. In addition, there is an advantage that the super lean combustion operation becomes possible in the entire operation range including this speed range and the fuel consumption is improved.

According to a fifth aspect of the present invention, there is provided a direct injection internal combustion engine according to the first aspect of the present invention, wherein the engine according to the first aspect is formed between the upper surface of the piston fitted in the cylinder and the lower surface of the cylinder head. The combustion chamber, an intake valve provided on one side of the lower surface of the cylinder head forming the combustion chamber with a virtual plane including the cylinder axis interposed therebetween, an exhaust valve provided on the other side with the virtual plane interposed, and Between the intake valve and the exhaust valve, a recess formed on the upper surface of the piston located on one side so as to promote a vortex flow of intake air so as to exhibit a downward convex curved surface in a plane view orthogonal to the cylinder axis. A fuel injection valve for injecting fuel toward the recess and an ignition plug provided on the cylinder head located on the opposite side of the fuel injection valve with the axis of the intake valve interposed therebetween. Constitution With this simple configuration, a rich air-fuel mixture can be formed near the spark plug through the recess, improving combustion stability in the high-speed operating range, and improving the entire operation including this speed range. There is an advantage that fuel consumption is improved by realizing ultra lean burn operation in the range.

Further, according to the cylinder injection type internal combustion engine of the present invention described in claim 6, in the engine described in any one of claims 1 to 5, the intake system opened and closed by the intake valve is
With a simple configuration in which the intake flow introduced into the combustion chamber is configured to form a vertical vortex flow from the lower surface of the cylinder head to the ignition plug through the upper surface of the piston,
In addition to the rich mixture flowing through the recess, a vertical vortex flow is generated, so efficient fuel mixing and fuel transportation assistance to the vicinity of the spark plug are realized, and a mixture with a uniform lean air-fuel ratio is realized. Thus, there is an advantage that combustion stability is improved in a high speed operation range, super lean combustion operation is realized in the entire operation range including this speed range, and fuel economy is improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view schematically showing a configuration of a main part of a cylinder injection internal combustion engine as an embodiment of the present invention.

FIG. 2 is a schematic front view showing a lower surface of a cylinder head of a cylinder injection internal combustion engine as an embodiment of the present invention.

FIG. 3 is a schematic diagram showing an operating state of a cylinder injection internal combustion engine as an embodiment of the present invention.

FIG. 4 is a schematic diagram showing an operating state of a cylinder injection internal combustion engine as an embodiment of the present invention.

FIG. 5 is a graph showing fuel characteristics of a cylinder injection type internal combustion engine as an embodiment of the present invention.

FIG. 6 is a diagram showing a process of processing a fuel injection hole and an exhaust valve guide hole.

FIG. 7 is a schematic diagram showing an operating state of a conventional in-cylinder injection internal combustion engine.

FIG. 8 is a schematic diagram showing an operating state of a conventional in-cylinder injection internal combustion engine.

FIG. 9 is a schematic diagram showing an operating state of a conventional in-cylinder injection internal combustion engine.

[Explanation of symbols]

 1 Cylinder Head 1A Cylinder Head Lower Surface 2 Piston 3 Cylinder Block 3A Cylinder 4 Intake Port 4A Intake Passage Combustion Chamber Opening 5 Exhaust Port 5A Exhaust Passage Combustion Chamber Opening 7 Combustion Chamber 8 Exhaust Valve 8A Exhaust Valve Guide Hole 9 Intake Valve 10 Fuel Injection Valve 10A Fuel injection hole 11 Spark plug 12 Wall surface 13 Recess 101 Intake port 102 Fuel injection valve 103 Combustion chamber 104 Piston

Claims (6)

[Claims] 1. A combustion chamber formed between an upper surface of a piston fitted in a cylinder and a lower surface of a cylinder head, and a combustion chamber formed between the lower surface of the cylinder head and a lower surface of the cylinder head sandwiching a virtual plane including a cylinder axis. An intake valve provided on one side, an exhaust valve provided on the lower surface of the cylinder head on the other side across the virtual plane, and provided between the intake valve and the exhaust valve with an inclination toward the exhaust valve side. A fuel injection valve for injecting fuel toward the upper surface of the piston, and an ignition plug arranged on the cylinder head portion opposite to the fuel injection valve with the axis of the intake valve interposed therebetween. And a cylinder injection internal combustion engine. 2. The cylinder injection internal combustion engine according to claim 1, wherein the fuel injection valve is inclined substantially parallel to the axis of the exhaust valve. 3. A recess having a downwardly convex curved surface in a plan view orthogonal to the cylinder axis is formed on the upper surface of the piston located on the one side to promote the vortex flow of intake air, and the fuel injection valve is also provided. 2. The in-cylinder injection internal combustion engine according to claim 1, wherein the fuel is injected toward the recess and the fuel is reflected by the recess and is directed toward the spark plug. . 4. The in-cylinder injection internal combustion engine according to claim 1, wherein a tip of the spark plug is arranged in the recess at a compression top dead center of the piston. organ. 5. A combustion chamber formed between an upper surface of a piston fitted into a cylinder and a lower surface of a cylinder head, and a combustion chamber formed between the lower surface of the cylinder head and a lower surface of the cylinder head, the virtual plane including the cylinder axis being sandwiched between the combustion chamber and the combustion chamber. Side, an exhaust valve provided on the other side across the virtual plane, and an upper surface of the piston located on the one side in a plane view orthogonal to the cylinder axis in order to promote an intake vortex flow. A recess formed so as to exhibit a downwardly convex curved surface, and provided between the intake valve and the exhaust valve,
A fuel injection valve for injecting fuel toward the recess, and an ignition plug provided on the cylinder head opposite to the fuel injection valve with the axis of the intake valve interposed therebetween are provided. A characteristic is a cylinder injection internal combustion engine. 6. An intake system opened and closed by the intake valve,
The intake air flow introduced into the combustion chamber is configured to form a longitudinal vortex flow from the lower surface of the cylinder head to the upper surface of the piston toward the spark plug. The in-cylinder injection internal combustion engine described.