JPH0717780Y2 - Spark assist in-cylinder fuel injection engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a spark assist in-cylinder fuel injection engine in which fuel is directly injected into a cylinder and ignited by a spark plug for combustion.

[Prior Art] In a spark assist in-cylinder fuel injection engine, in order to promote atomization of the fuel and dispersion in the combustion chamber, the fuel injected from the fuel injection valve into the cylinder is made to collide with the fuel collision wall surface once, and There is known an engine combustion chamber structure in which the fuel is dispersed by collision and the atomized fuel reflected toward the spark is ignited by the spark.
-87169, JP 61-113822, JP 62-1399
21 and U.S. Pat. No. 3,195,520).

Further, there is also known a structure in which at least a part of the fuel injected into the cylinder is directly sprayed on the spark plug gap portion without colliding with the collision wall surface (for example, JP-A-61-167116, actual opening). 62-87127 publication).

[Problems to be solved by the invention] However, the one in which a part of the fuel is directly wiped by the spark plug has a problem that smoldering of the spark plug occurs, and the atomization of the fuel is poor and stable ignition performance is difficult to obtain.

Further, in the case where a part of the fuel is once collided with the fuel collision wall surface and atomized, although the atomization is promoted, since the fuel collision wall surface is usually formed on the piston, due to the difference in fuel injection timing, The distance between the piston and the fuel injection valve changes, and unless the angle of fuel injection is parallel to the trajectory of the piston, the collision position of the fuel and the wall changes,
There is a problem that the fuel dispersion becomes unstable, the injection timing is restricted, and the ignition becomes unstable.
Even when the fuel collision wall surface is fixed to the cylinder head side (for example, in the above-mentioned U.S. Pat.No. 3,195,520), the extension line of the fuel disengagement portion of the fuel collision wall surface passes through the upstream side of the spark plug in the swirl direction. Therefore, the fuel that has separated from the fuel collision wall surface is carried to the spark plug by swirl, and it is difficult to control the timing of swirl generation, swirl strength, and fuel injection timing, and stable ignition is achieved. It was difficult to get sex.

According to the present invention, the positional relationship between the fuel injection valve and the fuel collision wall surface is
An object of the present invention is to provide a spark assist in-cylinder fuel injection engine that is stable regardless of the position of the piston and that can obtain stable fuel atomization.

[Means for Solving the Problems] According to the present invention, the above-mentioned problems can be achieved by the following (i) spark assist in-cylinder fuel injection engine.

(I) In a spark assist in-cylinder fuel injection engine in which at least a part of the fuel injected from the fuel injection valve directly collides with the fuel collision wall surface, the fuel collision wall surface is formed on the cylinder head side, and the fuel injection valve and the spark plug are combined. The fuel impingement wall surface is formed substantially at right angles to the center line of fuel injection toward the fuel impingement wall surface in the vertical inward direction, and the extension line on the fuel release wall side of the fuel impingement wall surface of the spark plug is provided. The inside of the spark assist cylinder, characterized in that almost all of the fuel that has passed through the lower side and has collided with the fuel collision wall surface is lifted up to the spark plug portion in accordance with the upward movement of the piston facing directly below the spark plug. Fuel injection engine.

The spark assist in-cylinder fuel injection engine of (i) above can have the following aspects.

(Ii) a combustion chamber surrounded by a lower surface of the cylinder head, an upper surface of the piston, and a wall surface of the cylinder bore; an ignition plug facing the combustion chamber; and a fuel injected directly into the combustion chamber facing the combustion chamber, A fuel injection valve whose injection direction is oriented so that fuel injected from at least one of the injection holes flies toward the spark plug; and between the spark plug and the fuel injection valve, the spark plug The fuel flying toward the spark plug is provided so as to project downward from the lower surface of the cylinder head so as to prevent the fuel flying toward the spark plug from directly reaching the spark plug, and the fuel flying toward the spark plug on the side facing the fuel injection valve. Colliding with each other and having a fuel collision wall surface formed substantially at right angles to the center line of the flight fuel, and the fuel separation wall portion is formed so that an extension line of the fuel separation wall portion of the fuel collision wall surface passes under the spark plug. Is formed, Out section and; a has (i) a spark-assisted cylinder fuel injection engine according.

(Iii) The spark assist in-cylinder fuel injection engine according to (ii), wherein the protrusion has a size such that fuel flying toward the spark plug does not directly hit the spark plug.

(Iv) The spark assist in-cylinder fuel injection engine according to (ii), wherein the fuel collision wall surface has an edge portion at a lower end, and the edge portion constitutes the fuel release portion.

(V) The fuel injection valve has a single injection hole (i
i) The spark assist in-cylinder fuel injection engine described above.

(Vi) The fuel injection valve has a plurality of injection holes, part of which is directed to the fuel collision wall surface, and the rest is directed to the top surface of the piston (ii). Internal fuel injection engine.

(Vii) The spark assist in-cylinder fuel injection engine according to (vi), wherein the injection hole directed to the fuel collision wall surface has a larger diameter than the injection hole directed to the piston top surface.

[Operation] In the engine described in (i), the fuel injected from the fuel injection valve and flying toward the spark plug directly collides with the fuel collision wall surface and is dispersed, so that the fuel is widely dispersed below the spark plug. The region is lifted up in the vicinity of the spark plug in accordance with the upward movement of the piston, and a dense mixture zone in which atomization is promoted is formed in the vicinity of the spark plug, where it is ignited and burned.

Therefore, atomization is promoted, stable combustion and ignition are obtained, and spark smolder does not occur as compared with the case where the spray is directly sprayed on the spark plug gap.

Further, since the fuel collision wall surface is provided on the cylinder head side, the relative position between the fuel collision wall surface and the fuel injection valve is constant, and stable fuel distribution is performed even if the injection timing and the injection period are changed, and the ignitability is improved. Stabilize. Such stability cannot be obtained by the conventional one in which the fuel collision wall surface is formed on the piston.

[Embodiment] A preferred embodiment of a spark assist in-cylinder fuel injection engine according to the present invention will be described below with reference to the drawings.
1 and 2 relate to the first embodiment of the present invention, FIG. 3 relates to the second embodiment of the present invention, FIG. 4 relates to the third embodiment of the present invention, and FIG. Regarding the fourth embodiment.

Explaining the configuration common to each embodiment, the cylinder head 2
The combustion chamber 12 is surrounded by the lower surface 4, the upper surface 8 of the piston 6, and the cylinder bore wall surface 10. A spark plug 14 and a fuel injection valve 16 face the combustion chamber 12. The fuel injection valve 16 is installed in the combustion chamber 12
Fuel 18 is directly injected into at least one of the injection holes,
The fuel injected from the at least one injection hole is spark plug 14
The jet direction is directed to fly towards. A portion of the injected fuel that is directed to the spark plug 14 is indicated by reference numeral 18a. On the lower surface 4 of the cylinder head, a spark plug 14 and a fuel injection valve
A projecting portion 20 formed so as to project downward is provided between the fuel cell 16 and the fuel cell 16 so as to prevent the fuel 18a flying toward the spark plug 14 from directly reaching the spark plug 14. This protrusion 20
The wall surface on the side facing the fuel injection valve 16 constitutes a fuel collision wall surface 22 on which the fuel 18a directly collides. Fuel collision wall
Since 22 is for colliding the fuel 18a to atomize it, the collision angle should not be made too shallow. Protrusion 20
Further, since the fuel collision wall surface 22 is provided on the cylinder head 2 side, the relative position between the fuel collision wall surface 22 and the fuel injection valve 16 is always constant, and the position does not change unlike when it is provided on the piston. An extension line of the fuel release portion 34 (same as the edge portion described later) of the fuel collision wall surface 22 passes under the spark plug 14, and therefore the fuel (which is different from the one using the swirl like USP3195520) is It flows downwards of the spark plug 14. 24 is an intake port, 26 is an exhaust port, and 28 and 30 are intake and exhaust valves.

The fuel impingement wall surface 22 is composed of an inclined flat surface and has a spark plug.
To the centerline 40 of the flow of fuel 18a flying toward 14,
It is almost a right angle. However, the angle of the fuel collision wall is 90 ° or more downward with respect to the center line of the fuel jet.
Is inclined so as to have. Due to the function of collision atomization, θ should not be close to 180 °, but is about 135 ° or less, and is preferably close to 90 °. 90 ° and above is
This is because when the fuel 18a collides with the fuel collision wall surface 22, the atomized fuel 32, which is collided and atomized and dispersed, is directed downward and toward the downward extension of the spark plug 14.

The size of the protrusion 20 (the size of the spread in the left-right direction and the vertical direction) is set to a size that can block the fuel 18a flying toward the spark plug 14 from directly hitting the spark plug 14. . This is because the injected fuel 18a directly hits the spark plug 14 and does not cause ignition line smoldering or ignition instability due to the non-atomized fuel.

An extension of the fuel impingement surface 22 passes through a downward extension of the spark plug 14. This helps direct the atomized fuel 32 down the spark plug 14 and prevent the fuel 18a from hitting the spark plug gap directly.

The fuel collision wall surface 22 has a sharp edge portion 34 at its lower end. The edge portion 34 helps the atomized fuel 32 to separate from the fuel collision wall surface 22, and prevents the atomized fuel 32 from adhering to the lower end wall surface of the protruding portion 20 and getting around to the spark plug 14 side.

Next, the specific configuration of each embodiment will be described. In the first embodiment, as shown in FIGS. 1 and 2, the spark plug 14 is arranged in the central portion of the cylinder, and the fuel injection valve 16 is arranged in the outer peripheral portion of the cylinder. The central disposition of the spark plug 14 in the cylinder improves combustibility by minimizing the flame spread distance. Further, the central portion of the cylinder is a dead space that does not interfere with the ports 24, 26, etc., and by arranging the spark plug 14 whose diameter is relatively difficult to be arranged at this position, the parts, the ports 24, 26, and the water jacket are arranged. Makes it easy. Since the fuel injection valve 16 can be relatively easily reduced in diameter, it can be relatively easily arranged on the outer peripheral portion of the cylinder. Such a configuration is effective not only for an engine that does not generate swirl flow but also for an engine that generates swirl flow, and the fuel injected from the fuel injection valve 16 has a strong penetrating force immediately after it exits the injection hole. Is passed through the swirl flow of the section, atomized at the fuel collision surface 22 and the penetration force is weakened, and is supplied to the central part of the cylinder where diffusion due to the swirl flow is relatively unlikely to occur, forming an ignition mixture just below the spark plug. Can be maintained. In the first embodiment, the fuel injection valve 16 has a single injection hole, and most of the injected fuel flies toward and collides with the fuel collision wall surface 22. The piston 6 has a flat top surface. The ports 24 and 26 are provided in the cylinder head 2.

As shown in FIG. 3, the second embodiment is similar to the first embodiment except for the following points. In the second embodiment, the fuel injection valve 16 is
It has multiple injection holes, and some of the injected fuel
a is directed to the fuel collision wall surface 22, and the other parts 18b and 18c are directed to the piston top surface 8. The piston top surface 8 has a wall 36 that rises upward on the outer peripheral portion, and the wall 36 has a cutout portion 38 to avoid interference with the fuel injection valve 16. The wall 36 prevents fuel impinging on the piston top surface 8 from spreading along the top surface and adhering to the cylinder bore wall surface 10.

As shown in FIG. 4, the third embodiment is similar to the second embodiment except for the following points. In the third embodiment, the fuel injection valve 16 has a plurality of injection holes, among which the fuel directed toward the fuel collision wall surface 22.
The diameter of the injection hole for injecting 18a is larger than that of the injection holes for injecting the remaining fuels 18b, 18c, 18d. By doing so, the amount of fuel introduced to the spark plug 14 can be increased as needed.

As shown in FIG. 5, the fourth embodiment is similar to the second embodiment except for the following points. In the fourth embodiment, the spark plug 14 is located off the central portion of the cylinder, and the ports 24 and 26 (in this case, the scavenging port) are open to the cylinder bore and the piston 6
Also serves as a valve.

Next, the operation common to each embodiment will be described.

The fuel 18 injected from the fuel injection valve 16 is at least partially
The 18a flies toward the spark plug 14 and first collides with the fuel collision wall surface 22 of the protruding portion 20, and the fuel 18a is dispersed and atomized by this collision and becomes the atomized fuel 32 to become the fuel collision wall surface.
It moves from the vicinity of 22 to the position below the spark plug 14. Since the particles are atomized by collision and dispersion, the particles are atomized regardless of the presence of swirl or squish in the combustion chamber 12. The dense mixture zone of the atomized fuel 32 is pushed up by the airflow in accordance with the upward movement of the piston 6, moves to the ignition gearup portion of the spark plug 14, is ignited and burns, and the flame is generated in the combustion chamber 2 The entire air-fuel mixture in the combustion chamber 12 is burnt by being spread throughout.

Since the protrusion 20 and the fuel collision wall surface 22 are provided on the cylinder head 2 side, even if the fuel injection timing and the fuel period change, the injected fuel 18a directed to the spark plug 14 is inevitably at a constant angle. The fuel collides against the fuel collision wall surface 22, and the collision, dispersion, and atomization are stably performed. If a collision wall surface is provided on the piston side as in the prior art, such a stable collision cannot be obtained. The formation of the rich air-fuel mixture zone 32 can be formed regardless of swirl or squish.

In the protruding portion 20, the fuel 18a directed to the spark plug 14 directly
The size and position are set so as to block the flight fuel 18a so that it will not be hit by flight.Therefore, columnar liquid fuel may be applied to the spark plug 14 to cause ignition instability or spark smolder. Does not happen.

Next, the unique operation of each embodiment will be described. First
In the embodiment, since all the fuel collides with the fuel collision wall surface 22 provided on the cylinder head side and is atomized and dispersed, the piston top surface 8 is flat as compared with the engine having the fuel collision wall surface on the piston. A flat piston can be used, the weight of the piston can be reduced, and friction can be reduced.

In the case where the fuel injection valve 16 has a plurality of injection holes and a part of the fuel 18a is injected toward the piston top surface 8 as in the second to fourth embodiments, the fuel evaporation on the piston top surface 8 is You also get a boost. In such a case, the fuel injected on the piston top surface 8 is prevented from flowing to the cylinder bore wall surface 10 by the wall 36.
Is set up.

[Effects of the Invention] According to the present invention, the following effects can be obtained.

(A) Since the positional relationship between the fuel injection valve 16 and the fuel collision wall surface 22 is always kept constant regardless of the piston position,
Even if the injection timing changes, stable fuel distribution is performed,
Ignition is stable.

(B) The projecting portion 20 prevents the fuel from flying directly to the spark plug 14 and hitting it, thus preventing smoldering of the spark plug.

(C) In addition, due to atomization due to direct collision and dispersion on the fuel collision wall surface that is almost perpendicular to the centerline of the fuel flow in the vertical direction, mixing in a wide area where atomization is promoted. Air is formed from the fuel-collision wall surface directly below the spark plug and is carried to the spark plug site as the piston rises, so that the ignition is stable without being affected by the swirl.

[Brief description of drawings]

1 is a sectional view of a spark assist in-cylinder fuel injection engine according to a first embodiment of the present invention, FIG. 2 is a plan view of the engine of FIG. 1, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a sectional view of a spark assist in-cylinder fuel injection engine, FIG. 4 is a sectional view of a spark assist in-cylinder fuel injection engine according to a third embodiment of the present invention, and FIG. 5 is a spark assist according to a fourth embodiment of the present invention. FIG. 3 is a cross-sectional view of a cylinder fuel injection engine. 2 ... Cylinder head 6 ... Piston 12 ... Combustion chamber 14 ... Ignition plug 16 ... Fuel injection valve 18a ... Injection fuel toward ignition plug 20 ... Projection 22 ... Fuel collision wall surface 32 ... Atomization Fuel 34 …… Edge part (fuel release part)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiji Hashimoto 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Masanori Koyasu 1 Toyota Town, Toyota City, Aichi Toyota Motor Co., Ltd. (56) References: Kaihei Hei 1-127929 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. In a spark assist in-cylinder fuel injection engine in which at least a part of fuel injected from a fuel injection valve directly collides with a fuel collision wall surface, the fuel collision wall surface is formed on a cylinder head side, and the fuel injection valve and ignition are performed. It is provided between the plugs, and the fuel collision wall surface is formed substantially at right angles to the center line of fuel injection toward the fuel collision wall surface in the vertical inward direction, and an extension line of the fuel collision wall surface on the fuel release side is ignited. Spark assist, characterized in that almost all of the fuel that has passed through the lower side of the plug and has collided with the fuel collision wall surface is lifted up to the spark plug portion in accordance with the ascent of the piston facing directly below the spark plug. In-cylinder fuel injection engine.