JPH085306Y2 - In-cylinder injection spark ignition engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a direct injection spark ignition engine.

[Prior Art] Conventionally, a cylinder injection type spark ignition engine is disclosed in Japanese Patent Laid-Open No. 61-167116.
JP-A-61-87127, JP-A-61-87169, JP-A-62-139921 and JP-A-61-1739921.

Among these, Japanese Patent Laid-Open Nos. 61-167116 and 61-8712
In JP 7 and JP-A 61-87169, one of the multiple injection holes of the fuel injection valve is directed to the ignition gap of the spark plug, and the other is directed to the piston, which improves the ignitability at a light load. It's stripped. Further, in Japanese Patent Laid-Open No. 62-139921, the fuel injected from the fuel injection valve collides with the convex portion formed on the piston and is reflected and diffused throughout the combustion chamber to improve the combustibility at high load. Furthermore, in Japanese Utility Model Publication No. 61-1739921,
The piston has a shallow plate and a deep plate.When the load is light, the fuel is injected into the deep plate, and when the load is high, the fuel is injected into the shallow plate. Combustion at light load and high load Both sexuality are achieved.

[Problems to be Solved by the Invention] However, the conventional technology has the following problems.

First, in JP-A-61-167116, JP-A-61-87127, and JP-A-61-87169, since a part of fuel is directly injected into the spark plug gap, the fuel is not vaporized. If it is adjusted so that good combustion can be obtained when the load is bad and the load is light, excess fuel will be generated at the time of high load and spark smolder will occur.

Further, in JP-A-62-139921, since fuel injected from a fuel injection valve provided facing the convex portion having a small top surface formed on the piston is made to collide and diffuse,
The evaporation of fuel on the piston wall is not promoted well.

Further, in Japanese Utility Model Laid-Open No. 61-173728, since the ignition plug is not provided in the center of the cylinder, the flame transfer distance becomes large, and the ignition plug and the fuel injection valve are compactly arranged on the cylinder head. There was a problem that it was difficult.

The present invention promotes fuel evaporation and diffusion in the high load range,
An object of the present invention is to provide an in-cylinder injection spark ignition engine in which a rich mixture is formed in the vicinity of a spark plug in a light load region to improve ignitability and a spark plug and a fuel injection valve are compactly arranged. .

[Means for Solving the Problems] According to the present invention, the above-mentioned problems can be achieved by the following cylinder injection type spark ignition engine. (1) In a direct injection spark ignition engine in which fuel is injected from the fuel injection valve toward the top of the piston, and evaporative fuel is ignited and burned by a spark plug, the fuel injection valve at the time of a light load in the piston top A cylinder injection type spark ignition engine characterized in that a groove that gradually deepens along the injection direction of the fuel at the top of the piston and smoothly curves and rises near the end is formed at the position where the fuel injected from .

The cylinder injection type spark ignition engine of the above (1) can take the following modes.

(2) A combustion chamber formed by the piston, the lower surface of the cylinder head, and the wall surface of the cylinder bore; two intake ports and at least one exhaust port opening to the combustion chamber; An ignition plug that projects from the lower surface of the cylinder head into the combustion chamber; a fuel injection valve that is provided at an outer peripheral portion of a cross section of the cylinder and injects fuel toward the top of the piston;
A groove is formed on the top of the piston at a position where at least a part of the fuel injected from the fuel injection valve hits at the time of a light load with a late injection timing, and the hit fuel is reflected toward the spark plug side. (1) The in-cylinder injection type spark ignition engine.

(3) The in-cylinder injection spark ignition according to (2), wherein the groove is inclined in a direction orthogonal to the extending direction of the groove such that a groove portion farther from the spark plug is higher than a groove portion near the spark plug. organ.

(4) The in-cylinder injection spark ignition engine according to (2), in which a plurality of the grooves are formed, and the injected fuel sequentially hits the grooves as the piston rises, and fuel is intermittently dispersed in the combustion chamber.

(5) The in-cylinder injection according to (2), wherein the piston has a circular and concave shallow dish portion whose center coincides with the piston axis, and the groove is formed on the bottom surface of the shallow dish portion. Type spark ignition engine.

(6) The in-cylinder injection according to (2), in which a top surface portion of the top portion of the piston, which is at least part of the fuel injected from the fuel injection valve at the time of high load with an early injection timing, is a flat plane. Type spark ignition engine.

(7) The fuel injection valve comprises a multi-injection fuel injection valve, and some of the plurality of injection holes inject fuel toward the top of the piston, and the rest inject fuel into the combustion chamber space. (2) The in-cylinder injection spark ignition engine described in (2).

(8) The spark plug is located at a position surrounded by the two intake ports and the at least one exhaust port in a cylinder cross-sectional direction, and the fuel injection valve is located between the two intake ports. (1) The in-cylinder injection type spark ignition engine.

(9) The cylinder according to (1), wherein the spark plug extends upward from the combustion chamber parallel to a piston axis, and the fuel injection valve extends obliquely upward and outward from an outer peripheral portion of the combustion chamber. Internal injection spark ignition engine.

(10) The in-cylinder injection spark as set forth in (5), wherein the shallow dish portion has a flat bottom surface extending in a direction perpendicular to the piston axis and a side surface that smoothly curves and rises from an outer peripheral portion of the bottom surface. Ignition engine.

(11) The in-cylinder injection spark ignition engine according to (2), wherein the intake port includes a swirl port for introducing intake air into the combustion chamber in a tangential direction.

(12) The cylinder injection type spark ignition engine according to (2), wherein the intake port includes a port for introducing intake air into the combustion chamber toward a center of the combustion chamber.

(13) The cylinder injection type spark ignition engine according to (2), wherein the exhaust port extends straight in a plan view.

[Operation] In a cylinder injection type spark ignition engine, it is ideal that the fuel is dispersed well at high load and that the fuel is dispersed in the light load region without increasing the degree of stratification to burn the fuel.
Although it is possible to provide an engine with good fuel economy, it has been difficult to achieve both of them in the past.

In the present invention, the fuel injected from the fuel injection valve consists of the injected fuel directed to the top of the piston and the injected fuel injected into the space of the combustion chamber. When the injection timing is early, the injected fuel toward the top of the piston collides with the top of the piston, spreads on the top surface of the piston, and evaporates to form a mixture. When the injection timing is gradually delayed, the injected fuel enters the groove at the top of the piston, changes its direction toward the spark plug, evaporates in the air, forms a mixture, is ignited by the spark plug, and burns. Done. Here, in a cylinder injection engine, in a high load region where the injection amount is large, it is necessary to advance the injection timing to gain evaporation time, and in a light load region where the injection amount is small, dispersion of the air-fuel mixture is prevented and stratification is increased. Therefore, it is necessary to delay the injection timing. In the present invention, in the high load region where the injection amount is large, the injection timing is advanced to spread the fuel to the top of the piston to increase the evaporation area and promote the formation of the air-fuel mixture, thereby improving the output, and in the light load region where the injection amount is small. In this case, the fuel can be directed toward the spark plug by the groove and evaporated in the air before the injected fuel speed is attenuated by delaying the injection timing, thereby forming a highly stratified mixture near the spark plug. It is possible to stabilize the ignitability and improve fuel efficiency.

[Embodiment] The construction and operation of a preferred embodiment of a direct injection spark ignition engine according to the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a piston, a spark plug, a fuel injection valve, and the vicinity of a combustion chamber of a cylinder injection type spark ignition engine according to an embodiment of the present invention.
FIG. 2 shows a plan view of a piston, a combustion injection valve and injected fuel injected from the piston, and FIG. 3 shows a sectional view of a groove, including reflection of the injected fuel by the groove. Further, FIG. 4 is a sectional view of the cylinder injection type spark ignition engine of the embodiment of the present invention, FIG. 5 is a plan view of the cylinder head portion thereof, and FIG. 6 is a fuel injection valve. Shows an example.

In FIGS. 4 and 5, combustion is performed from the space surrounded by the wall surface of the cylinder bore 14 formed in the cylinder lock 12 of the cylinder injection type spark ignition engine, the concave lower surface toward the lower side of the cylinder head 13, and the piston 8. The chamber 15 is formed. The piston 8 has a shallow dish portion 10 having a circular outer diameter, which is formed in a shallow concave shape facing upward. However, the shallow plate portion 10 may be omitted. The concave space defined by the shallow dish portion 10 constitutes a part of the combustion chamber 15. The combustion chamber 15 has two intake ports
Intake port 2 consisting of 2a and 2b is open and at least 1
One exhaust port 5 is open. The illustrated example shows a case where there are two exhaust ports 5. An intake valve 3 is attached to each of the two intake ports 2 so that the ports can be opened and closed, and an exhaust valve 4 is attached to the exhaust port 5 so that the ports can be opened and closed. The spark plug 1 is located substantially in the center of the cross-sectional direction of the cylinder (direction perpendicular to the axis of the cylinder) and extends in parallel with the axis of the cylinder. The spark plug 1 projects from the lower surface of the cylinder head 13 into the combustion chamber 15. A fuel injection valve 6 is arranged at the outer peripheral portion of the cylinder in the cross-sectional direction. The injection timing of the fuel injection valve 6 is set so as to inject fuel toward the top of the piston late when the engine is lightly loaded and early when the engine is highly loaded.

The spark plug 1 has two intake ports 2 in the cylinder cross section direction.
It is located at a position surrounded by a and 2b and at least one exhaust port 5, and the fuel injection valve 6 is located between the two intake ports 2a and 2b. The spark plug 1 extends upward parallel to the cylinder axis,
The fuel injection valve 6 is provided from the outer peripheral portion of the combustion chamber 15 to the intake port 2a,
It extends diagonally upward and outward through the space between 2b. Since the position of the spark plug 1 is a position where the intake and exhaust ports 2 and 5 do not exist, it can be provided without interfering with the intake and exhaust ports 2 and 5. The fuel injection valve 6 can be provided at a relatively low temperature position without interfering with the intake port 2 by utilizing the position of the conventional dead space between the intake ports 2a and 2b.
The axial center of the spark plug 1 located substantially in the center of the cylinder, the axial center of the fuel injection valve 6 and the piston axial center of the outer peripheral portion are in the same plane including the cylinder axial center, and the axial center of the fuel injection valve 6 is It is located on the side opposite to the axis of the spark plug 1 with respect to the axis of the piston.

With the above configuration, in the multi-valve engine, the spark plug 1,
The fuel injection valve 6 can be arranged reasonably in space, and swirl is generated in the combustion chamber to obtain good evaporative fuel combustion characteristics. Further, the arrangement of the spark plug 1 at substantially the center of the cylinder minimizes the flame transfer distance, improves combustion characteristics, and prevents knocking.

The bottom surface 10a of the shallow dish 10 on the top of the piston 8 (the piston top surface when the shallow dish 10 is not formed) is shown in FIG.
As shown in the figure, a groove 20 is formed. The groove 20 is for the injected fuel 7a injected from the fuel injection valve 6 when the engine is lightly loaded,
It is formed at a position where at least one of 7b and 7c, that is, two of the injected fuels 7b and 7c, hits in the figure. The injected fuels 7b and 7c do not hit the groove 20 when the engine is under a high load with an early injection timing, so that the flat top surface of the piston 8 and the shallow pan 10 are formed. It hits the flat bottom surface 10a of the shallow plate portion 10. The remaining injected fuel 7a is injected toward the space inside the combustion chamber 15. The groove 20 has a slope that reflects the injected fuel 7b, 7c hitting the groove 20 toward the spark plug 1 side.

Further, specifically, the groove 20 is, as shown in FIG.
In the longitudinal direction, it gradually deepens in the direction of fuel injection and smoothly curves up near the end to rise to the piston top surface, and the shallow pan
When 10 is formed, it is connected to the flat bottom surface 10a of the shallow dish portion 10. Further, as shown in FIG. 3, the groove 20 has a groove portion far from the spark plug 1 in a direction orthogonal to the longitudinal direction of the groove.
It is inclined so that it is higher than the groove portion close to. This helps direct the reflected fuel towards the spark plug 1 side.

As shown in FIG. 2, when the shallow pan 10 is formed on the piston top surface, a plurality of grooves 20 are formed on the bottom surface 10a of the shallow pan 10 so that the injection is performed as the piston rises. Fuel 7b, 7c
In sequence to the groove 20, and fuel is intermittently dispersed in the combustion chamber.

The shallow dish portion 10 has a flat bottom surface 10a extending in a direction perpendicular to the piston axis and a side surface 10b rising from the outer peripheral portion of the bottom surface 10a at a right angle to the bottom surface 10a. The surfaces 10a and 10b and the surface of the groove 20 are fuel evaporation surfaces, and in particular, the side surface 10b of the shallow dish portion 10 prevents the fuel from scattering on the wall surface of the cylinder bore.

The two intake ports 2 that open into the combustion chamber 15 preferably include swirl ports 2a. Swirl formation improves the vaporization and combustibility of the fuel. Swirl port 2a
Consists of a port that introduces intake air tangentially into the combustion chamber 15, and preferably does not use a helical port that increases resistance when the flow rate becomes large. The swirl port 2a can generate swirl in the combustion chamber 15 without increasing intake resistance.

The two intake ports 2 that open into the combustion chamber 15 preferably include a port 2b that introduces intake air toward the center of the cylinder. The intake air introduced from port 2b is swirl port 2a.
Since it is perpendicular to the swirl flow swirling in the combustion chamber 15 introduced from, the microturbulence can be generated without weakening the swirl generated by the swirl port 2a, and the combustibility can be improved.

At least one exhaust port 5 opening into the combustion chamber 15,
In the illustrated example, the two exhaust ports 5 and 5 do not need to be positioned between the spark plugs 1 and therefore do not need to be curved as in the conventional case, and extend straight in a plan view. As a result, the exhaust resistance is reduced as compared with the curved port, and the engine output can be increased.

The fuel injection valve 6 is composed of a multi-hole fuel injection valve. 1 and 2 show the case of three injection holes. Injection 7a, 7
Of b and 7c, 7b and 7c are injections that hit the groove 20 when the load is light, and injection 7a shows fuel injection that is injected into the air in the combustion chamber 15.

The fuel injection valve 6 has multiple injection holes at the tip of a valve body 61 as shown in FIG. 6, and a needle 63 is opened by an electrostrictive actuator or the like 62 to inject fuel from a fuel tank 64.
The injection amount is controlled by the opening time of the needle 63. The injection timing detects the engine speed and engine load and guides the signal to the engine control computer, which increases the injection amount and accelerates the injection timing when the load is high, and controls the injection amount when the load is light. The energization of the electrostrictive actuator 62 is controlled so as to reduce the injection timing and reduce the injection timing. The structure and control itself of these fuel injection valves 6 are similar to those already proposed in Japanese Patent Application No. 62-58756 and Japanese Patent Application No. 61-260621, but the structure and control itself are not the purpose of this invention. Since it does not exist, detailed description is omitted.

 Next, the main operation will be described.

At high load with a large amount of injection, the injection start timing is early, so
Of the injected fuel 7a, 7b, 7c, the fuel injection 7b, 7c injected toward the top of the piston is a flat top surface of the piston, and the flat bottom surface of the shallow dish 10 when the shallow dish 10 is formed. It is injected into 10a, collides there, spreads over the entire surface, and is evaporated in the entire combustion chamber 15. When the intake port 2 includes the swirl port 2a, evaporation is promoted by the swirl generated by the swirl port 2a and dispersed, and the injected fuel 7a also disperses along the swirl and the rich mixture is generated in the vicinity of the spark plug 1. Is not generated, and smoldering and smoke of the spark plug 1 are not generated.

When the load is small and the load is small, the injection timing is late, so the fuel injection 7b, 7c of the injected fuel 7a, 7b, 7c that is injected toward the top of the piston is the groove 20, and as the piston moves up, the multiple grooves 20 The injected fuel 7b, 7c is reflected toward the spark plug 1 side and evaporated due to the inclination of the groove 20, and the air-fuel mixture in the vicinity of the spark plug 1 does not become excessively lean, and good ignition performance is obtained. To be

That is, good combustion can be obtained under both high and low loads.

In addition, since the groove was gradually deepened in the fuel injection direction and smoothly curved at the end to rise, the injection angle of incidence (angle between the fuel spray and the groove bottom) was small, and the fuel hitting the groove bottom was small. Is prevented from being trapped in the groove in the direction opposite to the fuel injection direction, and the generation of smoke and deposit accumulation that may occur in the case of fuel confinement is prevented.

[Advantage of Invention] According to the present invention, the following effects are obtained.

Since it is configured as the means (1) for solving the above problems, it is possible to prevent the air-fuel mixture from being concentrated in the vicinity of the spark plug 1 at the time of high load,
Good ignitability at light load is obtained.

In addition, since the groove was gradually deepened in the fuel injection direction and smoothly curved at the end to rise, the injection angle of incidence (angle between the fuel spray and the groove bottom) was small, and the fuel hitting the groove bottom was small. Is prevented from being trapped in the groove in the direction opposite to the fuel injection direction, and the generation of smoke and deposit accumulation that may occur in the case of fuel confinement is prevented.

When the configurations (2) to (15) described in the means for solving the problems are adopted, the following additional effects are obtained.

By arranging the spark plug 1 at the substantially central position of the cylinder and the outer peripheral portion of the fuel injection valve 6 having the configuration of (2), the engine can be made compact and the arrangement can be made smooth, and the flame spread distance can be minimized. Is achieved.

With the configuration of (3), it is possible to smoothly reflect the injected fuel.

With the configuration of (4), it is possible to intermittently continue the injection fuel reflection under light load.

By forming the shallow dish portion (5), the adhesion of fuel to the cylinder bore can be minimized.

The configuration of (6) can promote compatibility between light load and high load.

With the configuration of (7), atomization of fuel can be promoted. (8)
With the configurations (1) to (13), the arrangement relationship between the spark plug 1, the fuel injection valve 6, the intake port 2, and the exhaust port 5 can be optimized in terms of space.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a cylinder injection type spark ignition engine according to the present invention, FIG. 2 is a plan view of a piston portion of FIG. 1, and FIG. 3 is a groove along line III-III of FIG. 4 is a longitudinal sectional view of a direct injection spark ignition engine according to the present invention, FIG. 5 is a plan view of FIG. 1, and FIG. 6 is a sectional view of an example of a fuel injection valve. . 1 ... Spark plug 2 ... Intake port 5 ... Exhaust port 6 ... Fuel injection valve 8 ... Piston 10 ... Shallow pan 15 ... Combustion chamber 20 ... Groove

Claims (1)

[Scope of utility model registration request] 1. A cylinder injection type spark ignition engine in which fuel is injected from a fuel injection valve toward the top of a piston, and evaporative fuel is ignited by a spark plug to burn the fuel injection valve when the piston top has a light load. A cylinder injection type spark ignition engine characterized in that a groove that gradually deepens along the injection direction of the fuel at the top of the piston and smoothly curves and rises near the end is formed at the position where the fuel injected from .