JPS6032928A - Combustion chamber of direct-injection type internal- combustion engine - Google Patents

Abstract

PURPOSE:To improve the irritating odor of exhaust gas and improve the maximum output, exhaust gas color, and fuel consumption by forming a recess in a windmill shape and forming a slant face on the upper portion from the middle of an intermediate wall face in an internal-combustion engine having a recessed main combustion chamber at the top of a piston. CONSTITUTION:A main combustion chamber made with a recess 2 is provided at the top of a piston 1. A distance L1 from an injection port center N0 to the wall face 2A hit by fuel is set in relation with a cylinder inter-diameter D so as to satisfy an equation L1=(0.25-0.35)XD, and a number of faces 2A hit by fuel are formed in response to individual injection ports. An intermediate wall face 2B on the swirl outflow side is set at a distance L2 0.8-0.9 times distance L1 and has the curvature gamma2 larger than the curvature gamma1. The recess 2 is formed in a windmill shape by connecting the wall face 2A and intermediate wall face 2B. A slant face 4 having a slant angle of 5 deg.-15 deg. is formed on the upper portion from the middle of the intermediate wall face 2B. Accordingly, the irritating odor of exhaust gas can be improved and the maximum output, exhaust gas color, and fuel consumption can be also improved.

Description

[Detailed description of the invention] This relates to the combustion chamber of a direct injection internal combustion engine.

Conventionally, the combustion chamber of a general direct-injection internal combustion engine has been of a toroidal type, which has a main combustion chamber of four parts 2 at the top of a piston 1, as shown in the side cross-sectional view of Fig. 1 and the plan view of Fig. 2. However, if the diameter d of the four parts 2 is increased for the same cylinder inner diameter D, the fuel spray reach l from the nozzle of the fuel injector 6 indirectly increases, and the injection reach lx
< l2 In contrast, the level of exhaust pungent odor at low speeds and low loads becomes good when the effective compression ratio ε is the same as shown in FIG. 3, and improves when the effective compression ratio ε is further increased.

In FIG. 2, θ indicates the 9-angle spread of the fuel spray from chorus [2-1], and arrow S indicates the swirl direction.

To increase the above effective compression ratio ε, the four parts 2 of the piston 1
By decreasing the volume of the concave portion 2 and increasing the diameter d of the recess 2, the squish speed decreases in inverse proportion to d/D.

As a result, the main combustion chamber volume ratio and squish speed decrease,
As shown in Figure 4, the maximum output ps significantly decreases, and the expansion of the diameter d of the stopper and the improvement of the effective compression ratio ε to reduce the irritating odor of the exhaust at low speeds and low loads reduce the maximum output at high speeds and high loads. lower.

In other words, in order to completely burn the small amount of fuel injected at low speed and low load in a direct injection internal combustion engine within the four parts 2 of the piston 1 and improve the irritating odor of the exhaust, it is necessary to increase the effective compression ratio ε and expand the spray reach l. It is.

If this is done in a conventional toroidal combustion chamber, it is possible to reduce the irritating odor of the exhaust, but at high speeds and high outputs, the compression ratio and spray reach are reduced! As a result of the expansion, the fuel ignites prematurely, and the combustion period becomes longer due to the reduction in squish power, which worsens the maximum output, exhaust color, and fuel consumption.

As a countermeasure for the above, Japanese Patent Publication No. 5]-29242 and Japanese Patent Publication No. 51-2924 concerning the combustion chamber of direct-injection diesel engines.
In the invention of No. 3 and Japanese Patent Publication No. 51-2924.4, the fuel spray is not applied to the corners of the four main combustion chambers, but is applied to straight parts and reflected, and the curvature r of the corners is The ratio r/R of the collision radius from each nozzle to
5, so r is always smaller than R.

If this curvature r is small, the fuel spray will accumulate after the collision,
The evaporation rate decreases, combustion becomes longer and performance deteriorates, and
Residues and the like in the fuel accumulate, further deteriorating the above performance.

In addition, the invention of Utility Model Application Publication No. 57168729 concerning the combustion chamber structure and the Japanese Patent Publication No. 1983 concerning the combustion chamber of diesel engines.
In the invention of No. 16881, the impact surface of the fuel spray is slightly curved, and the fuel spray is scattered by reflection.
When a small amount of fuel is injected at low force, the injection speed is very small compared to when the load is high, and there is almost no reflection. Therefore, unburned fuel accumulates on the wall soil installed to reflect it, causing unburnt or unburned gas to be emitted. It has the disadvantage that it generates a pungent odor from the exhaust gas.

Furthermore, Utility Model Application No. 57 regarding the combustion chamber of a diesel engine
-107821 and Utility Model Publication No. 55-4515 and Utility Model Application Publication No. 57-1 regarding the combustion chamber of direct injection diesel engines
In each of the inventions in No. 39631, a small amount of spray is completely combusted in compressed air when the force is low, but judging from the shape of the concave part, a brake is applied to the swirl during compression, and in reality, the swirl causes the spray to burn out completely. It has the disadvantage that it does not flow, and furthermore, in the device of Utility Model Application Publication No. 57-1396'31, the curvature of the inner wall of the fuel collision part is small, so unburned fuel does not spread when a small amount is sprayed, and unburned gas is emitted. With,
There are also disadvantages in that the opening area is large relative to the piston area, the squish force is reduced, and the air flow in the four parts due to swirl is reduced during compression.

SUMMARY OF THE INVENTION Therefore, the present invention solves the above-mentioned conventional drawbacks, improves the irritating odor of the exhaust at low speeds and low power of a direct injection internal combustion engine, and improves the peak color of the exhaust, fuel efficiency, etc. at high speeds and high power. It was made for the purpose of

That is, the present invention provides a direct injection internal combustion engine having a main combustion chamber with a concave portion at the top of a piston, in which the concave portion is filled with fuel spray from each nozzle of a fuel injection valve that reaches a wall surface on which it collides. The distance ttt [ff1L] is set to 0.35 times the inner diameter of the cylinder from 0625, and a fuel collision wall surface of 18° to 25° is formed in accordance with the number of nozzles depending on each fuel spray angle. Between the fuel collision walls,
The distance is set at a distance from the center of the sun which is 0.8 to 0.9 times the distance L], and the curvature r2 is larger than the curvature r1.
It is characterized by having four continuous intermediate wall surfaces having a windmill shape, and further forming one surface with an angle of 5° to 15° above the intermediate portion of the intermediate wall surface. be.

The present invention will be described in detail below with reference to the drawings. FIG. 5 is a side cross-sectional view showing the combustion chamber of a direct injection internal combustion engine in Embodiment 1 of the present invention, and FIG. 6 is a plan view of FIG. In this direct-injection internal combustion engine, which has a main combustion chamber from four parts 2 to the top of the piston 1, the fuel spray injected from each nozzle of the fuel injection valve 3 spreads through the four parts 2 at its spreading angle. θ=18°
The shape of the wall surface 2 that collides at an angle of ~25°, as shown in the plane cross-sectional view of the main part in FIG.
(0,25 to 0°35) 2
C is formed corresponding to the number of injection ports of the fuel injection valve 6.

Next, the distance between the four fuel collision walls 2A is set to a distance L2 from the nozzle center No. which corresponds to 0°8 to 0°9 times the distance L1 from the nozzle center No., and the distance L2 from the nozzle center No. The intermediate wall surface 2B on the swirl outflow side has a larger curvature r2 than r1, and the wall surface 2A on which the fuel spray collides, and the intermediate wall surfaces 2C and 2B are continuous to form a windmill shape.

In the fourth part 2 formed in the shape of a windmill in this way, the sixth
The fuel film after the collision is smoothly flowed and formed on the inner wall of the recessed portion 2 due to the swirl shown in the S direction in the figure, and the opening area relative to the piston surface area is reduced, thereby preventing a decrease in the air pressure.

Furthermore, in this embodiment, a deep bottom is formed at the bottom of the main combustion chamber of the four parts 2 so that the injected fuel sprays do not touch each other, and the bottom is deep so as to fill the wasteful parts between the fuel sprays. A polyhedral pyramidal convex portion 2D with a shallow height and the same number of nozzles as shown in FIG. 8 is formed.

As mentioned above, the center N of the nozzle on the inner wall surface of the fourth part 2.

The distance from Ll y L2 is L2/Ll = 0°7
By setting the value to 0.9, a vortex flow as shown by the arrow E in FIG. Air utilization is improved.

Note that the position of the center point of the curvature r1 is not limited to the first embodiment shown in FIG. 7, and may coincide with the center of the injected fuel spray, as shown in the second embodiment shown in FIG. .

Next, in the combustion chamber of the present invention, as shown in FIG. 11 showing the AA cross section of FIG. 6, the intermediate portion of the intermediate wall surface 2B,
That is, an inclined surface 4 having an angle of inclination dθ2 of 5° to 15° with respect to the vertical direction is formed above the top surface of the piston 1 at a depth h2.

The wall portion of the intermediate wall surface 2B having a curvature r2 from the bottom of the depth hl to the intermediate portion is also formed into an inclined surface having a small inclination angle d01 of 1° to 3°.

To explain the effect of the above-mentioned inclined surface 4, when the internal combustion engine is at low speed and low power, the amount of fuel injected from the fuel injection valve 6 is small, and complete combustion occurs during flight within a distance L1 from the fuel injection valve 6. However, since the fuel spray does not touch the wall surface 2A, no blue-white smoke or irritating odor from the exhaust gas is generated.

However, from Kotobuki, at high speeds and high loads, the fuel injection amount decreases at low speeds and under high loads.
As shown in Fig. 12, the fuel spray F collides with the wall 2AK, and further increases by 5 to 8 times as the force increases due to high-speed rotation.
The multi-fuel spray F is also flown by the speed of the swirl S from 0 to 100 M/S, and the fuel spray F adhering to the wall surface 2A is also evaporated while being flowed by the swirl S on the intermediate wall surface 2B, causing the top dead of the piston 1. The intermediate wall surface 2B and the rainbow flame H flow downward from the point as shown by the broken line.

However, as in the present invention, by forming the inclined surface 4 from the middle part to the upper part of the intermediate wall surface 2B, when a part of the fuel spray is flowed into the swirl S, it is possible to The flow flows above the piston 1 on the inclination 1 and 4, and flows smoothly to the upper surface of the piston 1.
Since the utilization of air on the upper surface is improved, the output of the internal combustion engine can be increased.

That is, in the present invention, the fuel injection iF colliding with the wall surface 2AK is
The piston 1 is divided into two parts: one that rotates within the four parts 2 of the piston 1, and one that flows upward from the piston 1 by an inclined surface 4 provided to utilize the air on the upper surface of the piston 1.

Therefore, in a direct injection internal combustion engine to which the combustion chamber of the present invention is applied, in order to completely burn a small amount of fuel in compressed air at low speed and low power, the spray reach distance at an appropriate effective compression ratio is reduced to the bottom. In addition, at high speeds and high forces, a large amount of fuel is applied to the collision area, but the shape is such that it flows smoothly in the form of a film on the inner wall surface downstream of the swirl caused by the suction swirl. The inner wall has an inner wall shape, and the inflow rim 11 is shaped to prevent unnecessary swirl from occurring in the swirl flowing into the injected fuel.

In addition, some unburned fuel spray from the intermediate wall downstream of the swirl after the fuel collision flows out to the upper surface of the piston, improving the utilization of air on the upper surface of the piston, thereby increasing the output of the internal combustion engine. .

As a result, the maximum output at high speeds and high loads increases, and the exhaust color and fuel efficiency are improved by 75 times.

Note that the present invention is mainly effectively applied to direct injection diesel engines.

[Brief explanation of drawings]

Figure 1 is a side sectional view of the combustion chamber of a conventional direct injection internal combustion engine, Figure 2 is a plan view of Figure 1, and Figure 3 is the exhaust odor level, effective compression ratio, and spray in the combustion chamber of Figure 1. Figure 4 is a diagram showing the relationship between the maximum output, effective compression ratio, and spray travel distance in the combustion chamber of Figure 1, and Figure 5 is a diagram showing the relationship between the maximum output and effective compression ratio in the combustion chamber of Figure 1, and the spray travel distance. A side sectional view showing the combustion chamber of a direct injection internal combustion engine, FIG. 6 is a plan view of FIG. 5, and FIG.
The figure is a plan sectional view of the fourth part of Fig. 5, Fig. 8 is a plane sectional view showing the bottom of the fourth part of Fig. 5, Fig. 9 is a plan view showing the vortex generated in the recess of Fig. 5, and Fig. 10. 11 is a plan sectional view of four parts of the combustion chamber in Embodiment 2 of the present invention, and FIG.
FIG. 12 is a plan view of the main part explaining the flow of fuel spray on the intermediate wall surface of FIG. 5, and FIG.
FIG. 2 is a longitudinal sectional view of the main part of the figure. 1... Piston, 2... Recess, 2A... Wall surface, 2
B...Intermediate wall surface, 4...Slanted surface, D...Cylinder inner diameter, LI Pb0...Distance, NO...Nozzle center,
ri, r2...curvature, dθ2... inclination angle. Agent: Patent Attorney Makoto Ogawa − Patent Attorney: Ken Noguchi Patent Attorney: Kazuhiko Saishita

Claims (1)

[Claims] In a direct injection internal combustion engine that has four main combustion chambers at the top of the piston, the distance L1 from the center of the nozzle to the wall surface on which the fuel spray of fuel injected from each nozzle of the fuel injection valve collides with the recess is defined as the cylinder inner diameter. 0025 to 0.35
A fuel collision wall surface of 18° to 25° corresponding to the number of nozzles is formed according to each fuel spray angle, and a curvature r1 is formed between each fuel collision wall surface on the inflow side of the swirl of this wall surface. wall, from 0.8 of the above distance L1 to the outflow side sail 9
set at twice the distance from the center of the nozzle, and the above curvature r1
The concave portion is formed in a windmill shape continuously on the intermediate wall surface having a relatively large curvature r2, and furthermore, an inclined surface with an angle of 5° to 15° is formed at the upper part of the intermediate wall surface. The combustion chamber of a direct injection internal combustion engine.