KR20000055220A - Direct injection gasoline engine combustion system - Google Patents

Abstract

PURPOSE: A directly spraying type gasoline engine is provided to effectively realize the gasoline engine characteristic of a directly spraying type. CONSTITUTION: An engine operation condition of high speed and load is applied in an output mode. Absorbed air is let in a combustion chamber(100) during an intake process. A swirl control valve installed in a tumble port(120a) is perfectly opened to absorb much air. The absorbed air through the tumble and swirl ports forms a flow of a tumble/swirl mixed type according to each port characteristic and has a strong warm current element. Fuel is sprayed through a fuel injector(130) during the intake process and mixed with the flow of the absorbed air. An equal air/fuel mixing period is generated until a compression process.

Description

DIRECT INJECTION GASOLINE ENGINE COMBUSTION SYSTEM}

The present invention relates to a direct gasoline engine, and more particularly, to a combustion system of a direct gasoline engine capable of appropriately controlling the flow in the combustion chamber through an effective design such as an intake port constituting the combustion chamber and a mounting position of the fuel injector. It is about.

In general, the main goal we pursue in all engines, not just gasoline engines, is to reduce operating costs and reduce harmful emissions while still getting maximum output at the same displacement.

As a technique for realizing ultra-lean combustion for the purpose of reducing fuel, a mixer is injected by injecting fuel from the intake port and pursuing lean combustion by appropriate flow in the cylinder, and by injecting the cylinder directly and in-cylinder flow. There is a way of pursuing lean burning through stratification (forming a partially thick mixer).

First, in the intake port injection type gasoline engine, the method of homogenizing the sprayed fuel as much as possible and rapidly burning it with a strong flow in the cylinder is mainly used, but the limit of lean burn is narrow and the intake port must be designed to generate a strong flow. The disadvantage is that the maximum output is reduced. In the intake port injection type gasoline engine, the fuel injector is mounted in the intake pipe or the cylinder head to inject fuel into the intake port. At this time, the injected fuel is generally introduced into the combustion chamber during the intake stroke, and the fuel and air in the combustion chamber are in the form of a uniform mixer during ignition. The intake port of the intake port injection type gasoline engine is required to be designed in consideration of the intake flow rate, tumble flow and swirl flow of the mixer. The lean burn intake port injection type gasoline engine is similar to the general intake port injection type gasoline engine, but the intake flow swirl (horizontal rotational flow, swirl) and tumble (vertical rotational flow, tumble) are used to secure combustion stability at lean fuel consumption. Enhances the properties of the inducer to induce uniform distribution or stratification of the mixer. These engines are divided into a combustion control mode into a region in which lean combustion is applied (fuel mode) and a region in which general combustion is applied (output mode), and the fuel injection method and injection timing in each combustion mode are the same.

The direct injection gasoline engine (G.D.I Engine) is a method of directly injecting fuel into the combustion chamber and pursuing lean combustion through stratification of the mixer by appropriate in-cylinder flow. In recent years, the development of high pressure injector technology and the need for improvement of fuel economy have begun to develop in earnest. Such direct injection engines have a revolutionary fuel economy by applying a combustion system capable of ultra-thin operation of about 40: 1 during partial load operation. It brings an improvement. Looking at the configuration, a fuel injector driven at high pressure is mounted to the cylinder head, and fuel is injected directly into the combustion chamber. The combustion mode of the direct injection gasoline engine is divided into the fuel efficiency mode, which is an ultra-lean fuel economy operation section, and the output mode, which is a general operation section, and each mode is classified by the fuel injection timing and the flow phenomenon of the mixer. The fuel economy mode enables ultra-thin combustion through stratification of the mixer (making the fuel richer around the ignition plug) and the injection timing of the fuel takes place during the compression stroke to maximize the mixer stratification effect. In the case of the output mode, the same as the intake port injection method except for direct injection of fuel, injection is performed during the intake stroke and a uniform mixer is used. The direct injection gasoline engine has an upright invertible tumble intake port, a spiral intake port with a swirl control valve, etc. for proper stratification and fuel injection timing of the mixer, and a piston top design suitable for each intake port shape. Control the flow of the mixer.

1A relates to a conventional direct gasoline engine shown in US Patent 5305720. As shown in FIG. 1A, the conventional combustion system includes a cylinder head 12 having an upright inverted tumble intake port 10, a piston 14 having a hemispherical top shape, and a high pressure fuel injector 16 mounted to the cylinder head 12. Etc.) The thick tumble mixer is formed around the spark plug 18 by generating a reverse tumble flow by the inverted tumble intake port 10 and impinging a flow injected at a high pressure on the upper surface of the piston 14 to the hemispherical upper surface of the piston 14. By forming it, combustion is possible even in ultra-thin air-fuel ratio. Upright invertible tumble intake port is used and there is no separate flow control device It uses a stratification technique of air / fuel mixture that distributes the fuel injected during the compression stroke in a strong reverse tumble flow generated during intake, around the spark plug 18 and sparsely away from the spark plug 18. . The same intake system is used in fuel consumption mode and output mode.

FIG. 1B is another conventional technique shown in Japanese Patent 08246878 (technical paper SAE970540), and is configured in such a manner that the stratification of the mixer is flowed by a strong swirl flow using the spiral intake port 20 and the swirl control valve 22. As shown in FIG.

Figure 1c is another conventional technique shown in the Nissan technical paper (SAE980149) by applying an intake port (Simamesed intake port) 24, which is widely applied to the intake port injection system has a configuration difficult to adjust the amount of swirl of the intake flow .

On the other hand, Figure 2 is a configuration showing the general mounting of the conventional fuel injector in the fuel injector 26 in the fuel injector in a state in which the center line l ₁ of the fuel injector and the crankshaft center line perpendicular direction l ₂ are parallel to each other. In some cases, special arrangements may be made for the fuel injector 26 in order to install 26 and adjust the fuel injection direction as necessary.

On the other hand, Figure 3 is a longitudinal cross-sectional view showing the flow state in the port when the swirl pot does not have curvature, Figure 4 is a plan view showing the main flow state in the conventional swirl pot. First, FIG. 3 shows an angle θ ₂ formed between the swirl line 32 centerline 13 and the cylinder head 30 horizontal plane 34. The arrow shows the flow of air. 4 shows an angle γ 'formed between a line L ₄ connecting the spark plug 34 at the center of the swirl pot and the main swirl flow direction line L ₅ in the swirl pot with the swirl pot having a shape without curvature. Reference numeral 36 denotes a swirl control valve.

However, since the conventional direct gasoline engine shown in FIG. 1A does not have a separate intake flow control system, there are disadvantages in that it does not satisfy the required flow generation conditions in two modes required in the direct engine. In addition, since the shape of the intake port is different from that of the conventional intake port injection engine, it is necessary to modify the overall design of the main parts of the engine such as a cylinder head, and thus there is a problem in that a large investment cost is required.

The conventional direct gasoline engine shown in FIG. 1B satisfies the above two operation modes by adopting a swirl control valve for intake flow control, but has a large resistance to intake flow by using a spiral intake port. Therefore, there is a problem that a loss of output occurs during full load operation.

The conventional direct gasoline engine shown in FIG. 1C does not use a standalone intake port, but uses an intake port and a swirl control valve suitable for the intake port injection engine. Therefore, effective swirl flow control is difficult.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a direct gasoline engine capable of effectively realizing a direct gasoline engine characteristic in pursuit of fuel efficiency improvement by ultra-thin fuel efficiency.

1A is a perspective view of a conventional direct gasoline engine.

1B is a perspective view of a conventional direct gasoline engine.

1C is a perspective view of a conventional direct gasoline engine.

2 is a plan view showing an installation state of a conventional fuel injector.

3 is a longitudinal cross-sectional view showing the flow state in the port when the swirl pot does not have curvature.

4 is a plan view showing a main flow state in a conventional swirl pot.

5 is a longitudinal sectional view showing a combustion system of a direct gasoline engine according to the present invention;

6 is a plan view showing a combustion system of a direct gasoline engine according to the present invention;

7 is a plan view showing a state in which the fuel injection direction is adjusted by mounting the fuel injector according to the present invention.

8 is a perspective view showing the mixer flow in the open state of the swirl valve.

9 is a perspective view showing the mixer flow in the closed state of the swirl valve.

10 is a longitudinal sectional view showing a state of the mixer with a curvature in the swirl pot;

11 is a configuration diagram showing a port dedicated tool use state.

12 is a plan view showing a main flow state in a state where the swirl pot is formed to have a curvature.

** Description of symbols for the main parts of the drawing **

100: combustion chamber 110: exhaust port

112: exhaust valve 114: exhaust valve seat

124: intake valve seat 120: intake port

120a: tumble pot 120b: swirl pot

122: intake valve 124: exhaust valve seat

130: fuel injector 140: spark plug

150: swirl control valve θ ₁ : the angle between the tumble port center line and the cylinder head horizontal plane

θ ₂ : Angle between the swirl pot center line and the cylinder head horizontal plane

α: inclination angle between the center line of the fuel injector and the line perpendicular to the center line of the crankshaft

γ: angle formed between the center of the swirl pot and the crankshaft center line

θ ₃ : Intake valve angle of gasoline engine

θ ₄ : exhaust valve angle of gasoline engine

θ ₅ : Angle formed between the combustion chamber surface of the cylinder head and the cylinder head plane

L ₀ : Cylinder center line

L ₁ : Tumble port center line

L ₂ : Swirlport Centerline

L ₃ : centerline of fuel injector

L ₄ : Crankshaft center line perpendicular

L _5, L ₆ : Mounting center line of intake / exhaust valve

L ₇ : Wire connecting the ignition plug

L ₈ : Main swirl flow direction line in swirl pot

The present invention is to properly control the flow in the combustion chamber through the effective design of the intake port and the fuel injector mounting position constituting the combustion chamber, to achieve the above object is configured as follows. That is, an exhaust port having an exhaust valve is formed at one side of the cylinder head, and an intake port having an intake valve is formed at the other side, and the intake port is formed as a separate port of the tumble port having a swirl port and a swirl control valve. And a fuel injector formed at a lower end of the intake port on the cylinder head, and a fuel gas injector directly injecting fuel into a combustion chamber formed by forming a spark plug at the center of the cylinder head. When the angle formed by the horizontal plane is θ ₁ , and the angle formed by the swirl pot center line and the cylinder head horizontal plane is θ ₂ , θ ₁ is larger than θ ₂ .

In the above configuration, the angle formed by the line in the direction perpendicular to the fuel injector center line and the crankshaft center line can be appropriately selected according to the in-cylinder flow formation.

In addition, an exhaust port having an exhaust valve is formed at one side of the cylinder head, and an intake port having an intake valve is formed at the other side, and the intake port is formed as a separate port of the tumble port having a swirl port and a swirl control valve. A fuel injector is formed at the lower end of the intake port on the cylinder head, and a spark plug is formed at the center portion of the cylinder head to directly inject fuel into the combustion chamber. The upper surface of the swirl pot close to the intake valve guide is characterized by having a curvature recessed downward.

In addition, an exhaust port having an exhaust valve is formed at one side of the cylinder head, and an intake port having an intake valve is formed at the other side, wherein the intake port is formed as a separate port of the tumble port having a swirl port and a swirl control valve. And a fuel injector formed at a lower end of the intake port on the cylinder head, and a fuel injection injecting fuel directly into a combustion chamber formed by forming a spark plug at the center of the cylinder head. The curvature has a curvature having a line perpendicular to the center line and a predetermined angle γ to enhance the generation of swirl flow in the swirl pot.

Hereinafter, the combustion system of a direct gasoline engine according to a preferred embodiment of the present invention will be described in detail.

5 is a longitudinal sectional view showing a combustion system of a direct gasoline engine according to the present invention, and FIG. 6 is a plan view showing a combustion system of a direct gasoline engine according to the present invention.

First, as illustrated in FIGS. 5 to 6, the present invention directly injects fuel into the combustion chamber 100 and seeks lean combustion through stratification of the mixer by appropriate swirl and tumble flow. An exhaust port 110 having an exhaust valve 112 is formed therein, and an intake port 120 having an intake valve 122 is formed at the other side. Here, the intake port 120 is formed of independent ports of the tumble port 120a and the swirl pot 120b, and each port is opened and closed by the intake valve 122. When the intake valve 122 is opened, the intake air is introduced into the combustion chamber 100 through the intake port 120 and mixed in the combustion chamber 100 with fuel injected through the fuel injector 130 during the intake or compression process. . In the compression process, the compressed air / fuel mixer is ignited by the spark plug 140. In addition, the exhaust port 110 in the combustion chamber 100 is opened and closed by an exhaust valve 112 and exhausts the exhaust gas after combustion from the combustion chamber to the outside during the exhaust stroke. An intake valve seat 124 is positioned downstream of the intake port 120, and suction air flows into the combustion chamber 100 through a space leading to the intake valve 122 and the intake valve seat 124, and the exhaust port 110. ) Is also equipped with an exhaust valve seat 114. The surface constituting the combustion chamber 100 of the cylinder head is configured in a pen loop shape and includes the above-described intake and exhaust ports 110 and 120, a fuel injector 130, a spark plug 140, and the like.

The fuel injector 130 of the direct injection gasoline engine is typically mounted on the cylinder head on the intake port side, and in the case of using stratification of the air / fuel mixture using swirl flow, it is advantageous to inject fuel in the same direction as the swirl flow. In view of this point, in the present invention, an angle between the tumble port 120a center line L ₁ and the cylinder head horizontal plane is θ ₁ , and an angle between the swirl pot center line L ₂ and the cylinder head horizontal plane is θ ₂ . At this time, θ ₁ is formed larger than θ ₂ . Here, θ ₁ is 35 ° to 45 °, and θ ₂ is preferably 20 ° to 25 °. In general, a large intake port angle is advantageous for tumble flow and a low flow resistance enables high output at high speed at full load operation. On the other hand, in order to obtain a strong swirl flow, it is advantageous that the intake port angle is small, so that the combustion stability can be improved in the low-speed partial load operation. Therefore, the configuration of the intake port allows the tumble flow and the swirl flow to be optimally generated according to the operating conditions by arranging each intake port angle differently.

7 is a plan view showing a state in which the fuel injection direction is adjusted by mounting a fuel injector according to the present invention. Looking at the mounting position of the fuel injector 130 described above with reference to Figure 7, the fuel injector 130 is installed on the lower end of the intake valve 122 of the cylinder head, the fuel of the fuel injector 130 is swirl pot 120b The angle formed between the center line L ₃ of the fuel injector 130 and the line L _{4 in the} direction perpendicular to the crankshaft center line so as to be injected into the combustion chamber 100 in the same direction as the swirl flow generated in It is installed. Here, the spark plug 140 is located at the center of the combustion chamber 100 in a state slightly biased toward the exhaust port side. In other words, the above-described conventional technique is a case where the injection direction is adjusted by the injection angle of the fuel injector 130 (shown in FIG. 2), and thus, many problems such as difficulty in manufacturing the fuel injector 130 and an increase in cost occur. do. Therefore, in order to solve this disadvantage, the present invention achieves excellent combustion performance by mounting the fuel injector 130 at an inclination angle α in the swirl flow direction when the fuel injector 130 is mounted. Here, the angle α formed by the center line L ₃ of the fuel injector 130 and the line L _{4 in} the right angle direction of the crankshaft center line may be appropriately selected according to the internal flow formation of the combustion chamber 100.

8 is a perspective view showing the mixer flow in the open state of the swirl valve, Figure 9 is a perspective view showing the mixer flow in the closed state of the swirl valve. 8 and 9, the intake manifold connected to an upstream side of the tumble port 120a of the intake port 120 is equipped with a swirl control valve 150 and flows into the tumble port 120a through opening and closing thereof. By adjusting the amount of air to be appropriately controlled the total amount of air flowing into the combustion chamber 100 and the type of flow according to the operating conditions. That is, in operating conditions requiring high output at high speed and high load, as shown in FIG. 8, the swirl control valve 150 is opened to allow a large amount of intake air to flow and at the same time, a cylinder center line (L _0: shown in FIG. 5). It enhances the direction of and the tumble flow, which is a flow component, and creates a favorable flow for high output.

On the other hand, in the low and high speed operation, as shown in FIG. 9, the intake air flows into the swirl pot 120b only by closing the swirl control valve 150, and the horizontal flow is perpendicular to the cylinder center line L ₀ direction. Enhances the swirl flow of the component to induce stratification of the air / fuel mixer around the spark plug 140 when mixing with the fuel injected during the compression process.

10 is a longitudinal sectional view showing a state of the mixer with a curvature portion in the swirl pot. As shown in FIG. 10, the curvature Ra which is recessed downward is formed at the side of the swirl pot 120b close to the valve guide 126 so that the swirl flow is introduced along the intake port side combustion chamber 100. have. In other words, the main flow, which can be represented by the centerline L ₂ of the swirl pot 120b, to flow the strong swirl flow into the combustion chamber 100 without colliding with the intake valve seat 124 of the swirl pot 120b. It is preferable to flow into the cylinder wall surface along the combustion chamber 100 on the exhaust port side. However, current gasoline engine development is a cylinder made perpendicular to the center line (L ₀ ) of the cylinder and the mounting center line (L ₅ ) (L ₆ ) of the intake and exhaust valves in order to make the size of the cylinder head as small as shown in FIG. The angle formed between the combustion chamber surface of the head and the cylinder head plane (θ _{5: shown in} Fig. 10) becomes small, so that the aforementioned flow is difficult to be expected. That is, when the swirl pot angle (θ ₂ : the angle between the swirl pot center line and the cylinder head horizontal plane) is reduced to generate the swirl flow as shown in FIG. 3, the main flow collides with the intake valve seat of the swirl pot to effectively swirl. It is difficult to generate flow. In order to realize such a flow, the present invention provides a curvature Ra to a portion of the valve guide 126 of the swirl pot 120b so that the main flow of the intake air collides with the valve seat 124. Avoid it.

11 is a configuration diagram showing a port-only tool use state. As shown in FIG. 11, the intake and exhaust valve seats 114 and 124 provided on the intake port 120 are formed in the same shape by the dedicated tool 200, and generally, the outlet portion of the intake port 120 is provided. The intake valve seat 124 is mounted on the seating surface is formed with the valve by machining using a special tool after mounting. In case of developing a direct injection engine based on the intake port injection engine, as described above, if an appropriate swirl flow is generated by the curvature portion (Ra: shown in FIG. 10) in the swirl intake port, the intake valve of the intake port injection type gasoline engine The angle θ ₃ can be shared. Therefore, in this case, when the intake port injection engine and the direct injection engine are mixed, the intake valve processing part is processed by the same tool not only the tumble port but also the swirl pot, thereby improving the productivity.

12 is a plan view showing a main flow state in a state where the swirl pot is formed to have a curvature. As shown in FIG. 12, a swirl pot is formed to have a predetermined curvature to form a line L ₇ connecting the spark plug 140 at the center of the swirl pot and a main swirl flow direction line L _{8 in the} swirl pot. It is possible to maximize the effect of the engine by forming (γ) larger than the angle (γ ') shown in the related art.

Referring to the operation of the combustion system of a direct gasoline engine according to the present invention configured as described above are as follows.

As shown in FIGS. 5 to 12, the operation of the direct gasoline engine is largely divided into an output mode and a fuel consumption mode, and accordingly, the operation of the intake system also varies according to each operation mode.

First, in the output mode, it is applied to the engine operating conditions of high speed and high load. Intake air flows into the combustion chamber 100 during the intake stroke, and the swirl control valve 150 mounted in the tumble port 120a is completely opened. Allow air to be inhaled. The air sucked through the tumble pot 120a and the swirl pot 120b forms a tumble / swirl mixed flow according to the respective port characteristics and has a strong turbulent component.

On the other hand, the fuel is injected during the intake stroke through the fuel injector 130 and mixed with the flow of the inhaled air and produces a uniform air / fuel mixer until the compression process.

On the other hand, in the fuel consumption mode is applied to the engine operation of low and medium speed and low load, the intake air flows into the combustion chamber 100 during the intake stroke of the engine, mainly by closing the swirl control valve 150 mounted on the tumble port (120a) Air is sucked in through the swirl pot 120b. In this case, the swirl control valve 150 can be linearly controlled to adjust the opening and closing degree of the valve according to the engine operating conditions.

Inhaled air is the main flow of the horizontal swirl flow perpendicular to the cylinder center line (L ₀ ) and is maintained during the compression stroke. The fuel is injected through the fuel injector 130 during the compression process, and the fuel injector 130 has a predetermined angle α in the swirl flow direction to improve the followability of the swirl flow in which the injected fuel is formed in the cylinder. Is mounted.

Due to the preformed swirl flow, a rich air / fuel mixture is formed around the spark plug, and an adult mixture is formed that becomes thinner as the distance from the spark plug 130 increases. It ensures the ignition by the spark plug to greatly improve the fuel economy of the engine.

Although the present invention has been described with reference to the preferred embodiments shown in the drawings, which are merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art.

As described above, the present invention has the following effects.

First, the fuel efficiency improvement in low and medium speed operation and the output improvement effect in high speed operation can be obtained.

Second, the fuel injection in the desired direction is possible by the mounting method without special design for the fuel injection angle of the fuel injector.

Third, the combustion stability is improved by the combustion of the stratified mixer, so that a large amount of EGR gas can be introduced, thereby reducing the emission of nitrogen oxides from the engine and increasing the additional fuel efficiency.

Fourth, it is possible to improve engine output by suppressing knocking and improving volumetric efficiency by accompanied by the effect of lowering the temperature of intake air due to the direct injection of fuel.

Fifth, in case of producing direct injection engine by design change of existing intake port injection type gasoline engine, it is possible to share common tools for intake port and intake valve seat. .

Claims (6)

An exhaust port having an exhaust valve is formed at one side of the cylinder head, and an intake port having an intake valve is formed at the other side, and the intake port is formed as a separate port of the tumble port having a swirl port and a swirl control valve. In a direct gasoline engine in which a fuel injector is formed at a lower end of the intake port on a cylinder head, and a fuel plug is directly injected into a combustion chamber formed by forming a spark plug at a central portion of the cylinder head. When the angle between the tumble port and the cylinder head horizontal plane is θ ₁ , and the angle between the swirl pot and the cylinder head horizontal plane is θ ₂ , θ ₁ is formed larger than θ _2. system. The angle of inclination α of claim 1, wherein the fuel injector is inclined at a predetermined angle with a line perpendicular to the center line of the fuel injector and the crankshaft center line so that the fuel of the fuel injector can be injected in the same direction as the swirl flow generated in the swirl pot. Combustion system of a direct gasoline engine, characterized in that formed by. 3. The combustion system of a petrol engine according to claim 1 or 2, wherein θ ₁ is 35 ° to 45 ° and θ ₂ is 20 ° to 25 °. An exhaust port having an exhaust valve is formed at one side of the cylinder head, and an intake port having an intake valve is formed at the other side, and the intake port is formed as a separate port of the tumble port having a swirl port and a swirl control valve. In a direct gasoline engine in which a fuel injector is formed at a lower end of the intake port on a cylinder head, and a fuel plug is directly injected into a combustion chamber formed by forming a spark plug at a central portion of the cylinder head. A combustion system of a direct gasoline engine, characterized in that the upper surface of the swirl pot proximate to the intake valve guide of the intake valve on the swirl valve side has a curvature recessed downward. 5. The combustion system of a direct gasoline engine according to claim 4, wherein the intake / exhaust valve seat provided on the intake port side is formed in the same shape by a dedicated tool. An exhaust port having an exhaust valve is formed at one side of the cylinder head, and an intake port having an intake valve is formed at the other side, and the intake port is formed as a separate port of the tumble port having a swirl port and a swirl control valve. In a direct gasoline engine in which a fuel injector is formed at a lower end of the intake port on a cylinder head, and a fuel plug is directly injected into a combustion chamber formed by forming a spark plug at a central portion of the cylinder head. And said swirl pot is formed with a curvature having a predetermined angle [gamma] with a line in a direction perpendicular to the crankshaft center line to enhance the generation of swirl flow in the swirl pot.