JP3380379B2 - In-cylinder injection engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a direct injection engine in which fuel is directly injected into a cylinder. 2. Description of the Related Art Conventionally, a direct injection engine has been proposed in which a fuel injection valve is mounted on a cylinder head so as to face a combustion chamber so as to directly inject fuel into a cylinder. The fuel injection valve is configured such that an injection port having a predetermined injection angle can be opened and closed by a valve body driven forward and backward by an electromagnetic coil, and controls an energization time to the electromagnetic coil according to a required fuel amount. The opening time of the injection port is controlled so that the fuel injection amount is adjusted. [0003] Incidentally, in the above-described in-cylinder injection engine, a uniform premixed fuel mixture in which the combustion speed is increased by uniformly diffusing and distributing the fuel in the cylinder according to the operating condition of the engine. It is required to perform stratified mixture combustion that prevents combustion or knocking under a high load by forming a highly concentrated mixture near the ignition plug and forming a lean mixture at the corners of the combustion chamber. I have. SUMMARY OF THE INVENTION The present invention has been made to meet the above-mentioned conventional demands, and has as its object to provide an in-cylinder injection engine capable of performing stratified mixture combustion and uniform premixed combustion. According to a first aspect of the present invention, there is provided an in-cylinder injection engine having an in-cylinder injection valve for injecting fuel into a cylinder. The fuel is formed in parallel in the axial direction, and viewed in the cylinder axial direction.
Connect the injection port of the injection valve to the opening of both intake valves of the cylinder head.
And the injection axis is directed toward the exhaust side.
And a spark plug near the cylinder axis.
Between the intake valve openings on the top wall of the combustion chamber of the Linda head
The fuel injected from the fuel injection valve is
To prevent direct contact with the electrodes of the
Forming a projection for promoting atomization of the material;
Separates the fuel injected from the injection opening into a left-right flow.
Surrounding the separation wall and the electrode of the spark plug,
And a shielding wall to prevent fuel from directly
It is characterized in that that. According to the first aspect of the present invention, since the projection is formed on the inner surface of the top wall of the cylinder head, the injected fuel is separated into left and right by the projection. For this reason, it is possible to prevent the injected fuel from being directly applied to the ignition plug, and the provision of the protruding portion increases the temperature particularly near the site where the separated fuel reaches, thereby promoting the atomization of the fuel. A first embodiment of the present invention will be described below with reference to the drawings. In all the drawings in the specification, the same reference numerals indicate the same or corresponding parts. 1 to 7 are views for explaining the in-cylinder injection engine according to the first embodiment. FIGS. 1 and 2 are cross-sectional side views, and FIG.
Fig. 4 is a bottom view of the cylinder head.
FIG. 5 is a plan view showing the piston cavity, FIG.
FIG. 7 is a diagram showing a temperature change in the combustion chamber. In FIG. 1, reference numeral 1 denotes a water-cooled 4-cycle parallel multi-cylinder 4-valve engine, in which a cylinder head 3 is coupled to a head side mating surface of a cylinder block 2 with a head bolt 20 and is formed above the cylinder head 3. The cam chamber 4 is covered with a head cover 5. A piston 7 is provided in the cylinder block 2.
Is fixedly inserted with a cylinder liner 6 made of cast iron having a cylinder bore 6d into which is slidably inserted. A flange portion 6a is formed on the upper portion of the cylinder liner 6 so as to be thick and approximately half the height of the piston stroke. The upper surface of the flange portion 6a communicates with a cooling jacket 3f in the cylinder head 3. An annular groove 6b is formed, and the annular groove 6b is formed by a through hole 6c formed to penetrate the flange 6a obliquely downward.
In the cooling jacket 2a. The piston 7 has a pin boss portion 7b into which a piston pin is inserted in a cylindrical portion 7a, and has an upper end closed by a top portion 7c. A cavity 8 constituting a combustion chamber is formed by the combustion recess 3a. As shown in FIG. 5 , the cavity 8 has a circular recess 8a,
An introduction portion 8b projecting radially outward on the intake side of the circular recess 8a, a reflecting portion 8c projecting radially center side on the exhaust side of the circular recess 8a, and left and right sides of the introduction inclined surface 8d. Depression
And are opposed to the left and right intake valve openings 10a, 10b.
Opposing concave portions 42a and 42b are provided. [0011] electrically join the club 8b of the circular recess 8a is for introducing the injected fuel into the cavity 8,
At its outer end, an introduction inclined surface 8d is formed. The reflecting portion 8c serves to blow up a part of the fuel injected from the fuel injection valve 14 toward the ignition plug 9 and direct the remainder toward the inside of the cavity 8, and has a reflective inclined surface 8e formed inside. Have been. This reflection inclined surface 8
e is located substantially at the center of the cylinder, and the electrode 9a of the ignition plug 9 is located directly above the reflection inclined surface 8e. The combustion recess 3a of the cylinder head 3 has two left and right intake valve openings 10a and 10b and two left and right exhaust pipe openings 11a and 11b. As shown in FIG. 1, the left and right intake valve openings 10a and 10b are led out to the rear wall 3b of the cylinder head while being joined by a bifurcated intake port 12a. Here, when viewed in the camshaft direction (see FIG. 1), the intake port 12a has a relatively long throat portion 12b formed coaxially with the valve shaft 15b of the intake valve 15.
A space for arranging a fuel injection valve 14, which will be described later, is provided between the straight portion 12c of FIG. A branch 12d of the intake manifold 12 is connected to the intake port 12a. A drift valve 17 is provided in the branch part 12d. The drift valve 17 has a notch 17a, and a valve shaft 17b parallel to the cam shaft.
It is rotatable between a fully open position and a closed position shown by a solid line in FIG. 2, and is opened and closed by an actuator (not shown). When the drift valve 17 is turned to the closed position, the intake air flows through the top wall of the intake port 12a and the notch 1.
7a, and flows toward the top wall side, flows axially along the exhaust-side inner surface of the cylinder bore 6d from near the center of the cylinder, and reverses at the piston top surface, whereby the vertical direction within the cylinder bore 6d. Vortex, so-called tumble, is generated in a pair of left and right. The left and right exhaust valve openings 11a, 11
The b is led out to the cylinder head front wall 3c while being joined by the bifurcated exhaust port 13a, and an exhaust pipe 13 is connected to the outlet. Due to the displaced arrangement of the intake valve openings 10a and 10b toward the exhaust side, a flat wide squish surface 3d is secured between the left and right intake valve openings 10a and 10b in the combustion recess 3a of the cylinder head 3. An injection opening 3e is formed in the center of the squish surface 3d in the cam axis direction. In the injection opening 3e, the straight portion 12c is provided between the straight portion 12c of the intake port 12a and the block side joint surface 3g.
c of the fuel injection valve 14 inserted substantially in parallel with
4a is located. The fuel injection valve 14 is connected to the injection section 14a.
The opening and closing of the injection nozzle formed therein is performed by a valve body driven forward and backward by an electromagnetic coil.
The distal end surface of is formed so as to be above the inner surface of the combustion recess 3a, and squish surface 3d flush. The above-mentioned injection
As shown in FIG. 2 , when the piston 7 is located at a ２〜 to ス ト ロ ー ク stroke position from the top dead center,
The angle and direction are set so that the fuel is injected toward the reflection inclined surface 8e of the piston 7. In this case, the injection angle is set to θ, and the injection direction is set to θ ′ between the axis of the injection valve 14 and the axis of the injected fuel. 14f is a fuel supply rail for supplying high-pressure fuel to the fuel injection valve 14. The left and right intake valve openings 10a, 10b
Are openable and closable by valve heads 15a of left and right intake valves 15, 15, and left and right exhaust valve openings 11a, 11b.
Can be opened and closed by the valve heads 16a of the left and right exhaust valves 16,16. The intake valve 15 and the exhaust valve 16 are arranged such that their respective valve shafts 15b, 16b form a predetermined angle between them. The lifters 17, 17 mounted on the upper ends of the respective valve shafts 15b, 16b are connected to each other. The opening and closing are driven by intake and exhaust camshafts 18 and 19 respectively. The intake camshaft 18 is supported by a bearing 18a and a bearing cap 18b formed on the cylinder head 3 side, and the exhaust camshaft 19 is supported by a bearing 19a and a bearing cap 19b on the cylinder head 3 side. It is supported by The intake camshaft 18 is located higher than the exhaust camshaft 19 by e. Here, the exhaust valve 16 is disposed at an inclination angle such that the intersection b between the axis a and the exhaust cam shaft 19 substantially coincides with the extension line c of the most exhaust side portion of the cylinder bore 6d. . The intake valve 15 has an axis a ′.
B 'of the cylinder bore 6d is disposed at an inclination angle deviated by d from the extension line c' of the most intake side portion of the cylinder bore 6d toward the cylinder axis. That is, in the engine of the present embodiment, the camshafts 18 and 19 are arranged with a small interval such that their axes are located substantially in the cylinder axial projection plane of the cylinder bore 6d, and the valve pinching angle is about 20. ° and narrow. By setting the valve sandwiching angle to be narrow as described above, the valve heads 15a and 16a become substantially flat surfaces. As a result, the surface shape of the combustion recess 3a becomes substantially flat and the volume of the combustion recess 3a is increased. And a high compression ratio is realized while the cavity 8 is provided. Also, since the valve sandwiching angle is reduced, the angle between the straight portion 12c of the intake port 12a and the cylinder axis can be made small, and in combination with the long throat portion 12b, The fuel injection valve 1 is provided between the intake port 12a and the block side mating surface 3g.
4 can secure the arrangement space. Further, as described above, since the intake camshaft 18 is disposed at a higher position by the dimension e, the intake port 12a can be raised while securing a necessary throat length, and the space for disposing the fuel injection valve 14 can be increased. Was secured.
And because there was relatively room in the placement space,
The cooling jacket 3f can be formed so as to surround the fuel injection valve 14, and the fuel injection valve 14 can be disposed at a position where fuel can be injected toward the combustion chamber 3a. 3 to 5 , reference numeral 40 denotes a left and right intake valve opening 10 which opens into the combustion recess 3 a of the cylinder head 3.
The projections disposed between (a) and (10b) (valve bridge) are shown. The projection 40 surrounds separation walls 40a and 40a for separating the fuel injected and supplied from the injection opening 3e into left and right flows D and E, and the electrode 9a of the spark plug 9, and the fuel 9 And a shielding wall surface 40b that avoids direct contact. As described above, in the present embodiment, the injected fuel is separated into the left and right flows D and E by the projections 40, and the intake valve openings 10a and 10a are located on the left and right sides on the introduction inclined surface 8d side.
Since the opposed recesses 42a and 42b facing the 10b are recessed, the mixing of fuel and air can be further promoted. Further, since the projections 40 are provided, the injected fuel is divided into left and right flows D and E, so that the injected fuel can be prevented from directly hitting the electrode 9a of the ignition plug 9. In addition, the provision of the protrusions 40 increases the temperature near the site where the separated fuel reaches, and promotes atomization. Here, the temperature distribution in the fuel recess 3a of the cylinder head due to the provision of the protrusion 40 was measured. In this measurement, the points 50, 51, 56, and 55 on the straight line A where the projection 40 is formed and the points 53, 52, 57, and 5 on the straight line B connecting the intake valve opening and the exhaust valve opening.
8 was examined. As shown in FIGS. 6 and 7 , at any point, the temperature rises with an increase in the engine speed and speed. In particular, the points located between the arrival points of the above-mentioned left and right flows D and E are shown. The temperature of 56, 57 is the engine speed,
Increases significantly with increasing speed. This allows
The separated fuel is given sufficient heat, and atomization is promoted. Generally, in an engine, it is necessary to atomize a large amount of fuel as the engine speed increases.
Moreover, it is necessary to reduce the time required for the atomization. In this engine, the left and right intake valve openings 10 in the combustion recess 3a are provided.
a, 10b, the projection 40 is provided so as to protrude.
By setting the value to 0, the temperature of the fuel reaching portion can be increased, and the evaporation time of the fuel can be shortened accordingly. In FIG. 6 , F is 800 rpm, G is 4800 rpm, H is 5600 rpm.
5 is a characteristic line showing a temperature change at each of the points at the time of. In FIG. 7 , I is a characteristic line showing a temperature change at 60 km / h, J is a characteristic line showing a temperature change at 120 km / h, and K is a characteristic line showing a temperature change at each of the above points at 180 km / h. According to the present invention , since the separating projection for separating the injected fuel is provided on the valve bridge of the cylinder head, it is possible to prevent the injected fuel from directly hitting the spark plug. Has the effect of promoting the atomization of water.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cylinder injection engine according to a first embodiment of the present invention .
It is sectional side view . FIG. 2 is a sectional side view of the engine of the first embodiment .
You . FIG. 3 is a sectional side view of a main part of the engine according to the first embodiment .
FIG. FIG. 4 shows a cylinder head of the engine according to the first embodiment;
It is a bottom view. FIG. 5 is a view showing a cavity of a piston of the engine according to the first embodiment;
It is a top view showing tee. FIG. 6 is a temperature characteristic diagram of the engine of the first embodiment.
You. FIG. 7 is a temperature characteristic diagram of the engine according to the first embodiment.
You. [Description of Signs] 1 In-cylinder injection engine 3 Cylinder head 6d Cylinder bore (cylinder) 9 Spark plug 10a, 10b Intake valve opening 14 Fuel injection valve 18 Intake camshaft 40 Projection 40a Separation wall surface 40b Shield wall D, E Left, right Directional flow

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02B 23/10 F02M 61/14 310 F02M 69/04

Claims (1)

(1) An in-cylinder injection engine provided with an in-cylinder injection valve for injecting fuel into a cylinder. In a cylinder injection engine, two intake valve openings are provided in a cylinder head in parallel in a cam axis direction. Form the fuel injection valve injection port viewed in the cylinder axis direction , cylinder head
And the injection axis is located between the two intake valve openings.
Side, and place the spark plug near the cylinder axis.
And the cylinder head combustion chamber top wall
Injection from the fuel injection valve into the portion between the two intake valve openings
Prevents fuel from directly hitting the spark plug electrodes
At the same time, a projection for promoting the atomization of the injected fuel is formed.
The projection is formed so that the fuel injected from the injection opening is supplied.
Separation wall that separates the fuel into left and right flow, and the spark plug
Surrounds the electrodes and avoids direct fuel application to the electrodes
A direct injection engine having a shielding wall .