JPH04103229U - diesel engine combustion chamber - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to improve combustibility in the combustion chamber of a direct injection diesel engine. [Configuration] Fuel injection valve 1 is installed in cavity 3 of piston 2.
A plurality of grooves 5 extending along the fuel spray injected from the
and a plurality of vortex chambers 6 that expand into a substantially circular shape on the extension of each groove 5, and a diffusion chamber that protrudes on the cavity bottom surface 3a in opposition to the fuel spray guided to each vortex chamber 6 on the extension of each groove 5. It is characterized by being equipped with a stand 7.

Description

[Detailed explanation of the idea]

0001

[Industrial application field]

The present invention relates to a combustion chamber of a direct injection diesel engine.

0002

[Conventional technology]

In recent years, there has been an increasing demand for lower pollution and higher output diesel engines. For example, as shown in Fig. 5, conventional methods have been used to improve the combustibility of diesel engines. (See Utility Model Application Publication No. 57-75123). This includes a cavity 33 recessed in the top surface 32a of the piston 32, and this cavity A fuel injection valve 34 is provided facing the center of the tee 33. Fuel is injected radially from six nozzle holes. The cavity 33 has six grooves 35 extending along each fuel spray, and six grooves 35 extending along each fuel spray. From the fuel injection valve 34, six pairs of swirl chambers 36 are provided which extend in a circular manner on the extension of the fuel injection valve 35. By creating a pair of vortices for each radially injected fuel spray, fuel and air are separated. It is designed to promote the mixing of air.

0003

[Problem that the idea aims to solve]

However, the fuel spray injected from the fuel injection valve 34 is guided into the swirl chamber 36. In the process of being removed, it collided with the cavity bottom surface 33a and adhered to the cavity bottom surface 33a. Otherwise, there is a possibility that a wall flow will flow along the cavity bottom surface 33a. Therefore, the air utilization rate in the combustion chamber decreases, and HC and smoke increase in the exhaust gas. There was a problem that The present invention aims to solve the above problems.

0004

[Means to solve the problem]

This invention creates a combustion chamber between the cavity recessed into the top surface of the piston and the cylinder head. A fuel injection valve that injects fuel radially from multiple nozzle holes into the combustion chamber. In the diesel engine, the cavity has a lower part of the fuel injector. It is equipped with a plurality of grooves extending along the fuel injection direction from a common chamber on the side. The cavity is equipped with a plurality of vortex chambers that expand approximately circularly on the extension of each groove. A raised surface is formed on the bottom surface of the groove on the extension of each groove, facing the fuel spray guided to each swirl chamber. Equipped with a diffusion table.

[0005]

[Effect]

The fuel spray that is injected from multiple nozzle holes and diffuses in the radial direction of the piston is The flame jet spreads through each groove to each vortex chamber, and each vortex chamber has its own flame. A swirling flow is generated vertically. This swirling flow prevents the fuel sprays from colliding with each other. Mixing fuel and air in the late stage of combustion while avoiding During the process in which the above fuel spray is guided to the swirl chamber through the groove, some of the fuel enters the cavity. The fuel diffuses toward the bottom of the piston, but this fuel is diffused as it rises from the bottom of the piston along with the flame. It is reflected off the table and diffused into the swirl chamber, or it adheres to the bottom of the cavity and forms a wall flow. The resulting fuel is separated via a diffusion table and diffused into the swirl chamber. This allows the top The swirling flow promotes the mixing of fuel and air, increasing the air utilization rate in the combustion chamber and producing smoke. and emissions of unburned HC can be reduced.

[0006]

【Example】

Next, one embodiment of the present invention will be described based on FIGS. 1 and 2. A direct injection diesel engine has a cavity 3 recessed in the top surface 2a of the piston 2. A combustion chamber 10 is defined between the cylinder head 11 and the cylinder head 11. A fuel injection valve 1 that injects fuel into a combustion chamber 10 is provided. In addition, in the figure, 12 is a cylinder. 13 is a piston ring.

[0007] The fuel injection valve 1 includes a needle valve (not shown) and a seat surface on which the needle valve sits. , six nozzle injection holes are opened on this seat surface, and each nozzle injection hole opens as the needle valve lifts. Fuel is injected into the combustion chamber 10 from the hole. The center line of each nozzle hole is a dot chain in the diagram. As shown by line o, the openings are opened radially at equal intervals and the fuel is injected and supplied radially. It looks like this. Also, the needle valve is biased in stages by two springs, and the fuel injection pump The fuel is pumped at predetermined timing from Injects in stages with main injection with high injection pressure.

[0008] The cavity 3 is branched from a common chamber 4 located below the fuel injection valve 1, and Equipped with six grooves 5 extending radially along the direction of fuel injection from each nozzle nozzle. and six vortex chambers 6 that expand in a substantially circular shape on the extension of each groove 5. .

[0009] The common chamber portion 4 is defined by an outer shell 4a rising in an arc shape concentric with the fuel injection valve 1. It will be done. Six grooves 5 are opened at equal intervals in this outer shell 4a. Each groove part 5 is formed by an outer shell 5a that stands up parallel to the center line o of each nozzle orifice. It is defined by Each swirl chamber 6 has a continuous arc shape with the outer contour 5a of the groove 5 as its tangential direction. It is defined by the outer shell 6a. Each of the above-mentioned outer shells 4a, 5a, and 6a is shaped perpendicularly to the piston top surface 2a. will be accomplished.

0010 The bottom surface 3a of the cavity 3 is formed by a conical surface that descends outward in the piston radial direction. . On the bottom surface 3a of the cavity, there is provided fuel which is guided to the swirl chamber 6 on the extension of each groove 5. A diffusion platform 7 is provided which rises to face the spray. This diffusion table 7 has a reflective surface 7a that rises from the cavity bottom surface 3a while tilting. and an upper surface connected to the upper edge of the reflective surface 7a and extending parallel to the cavity bottom surface 3a. One end of this upper surface 7b extends from the outer contour 5a of the groove portion 5 to the outer contour of the swirl chamber portion 6. It is connected through 6a. The position, inclination angle and protrusion height of the reflective surface 7a are determined by the inclination of the nozzle orifice. It is set according to the angle and the inclination angle of the cavity bottom surface 3a, and as described later, Converts the force of the fuel spray or flame guided into the swirl chamber 6 to the upper region of the swirl chamber 6 At the same time, the fuel wall flow that is about to flow from the reflecting surface 7a to the upper surface 7b is effectively Peel it off. Also, the reflective surface 7a is located at a location relative to the center line o of the nozzle orifice on the plan view. The fuel spray is formed to be inclined at a constant angle and passes through the groove 5 and hits the reflective surface 7a in a swirl chamber. Diffusion into the center of section 6.

[0011] Next, the effect will be explained. The fuel spray during initial injection with low injection pressure diffuses in the common chamber 4 and ignites this fuel. An ignition nucleus is formed in the common chamber 4. During the subsequent main injection with high injection pressure, the particles are dispersed radially with a relatively strong force. The fuel spray passes through the ignition core in the common chamber 4 and turns into a flame jet. It diffuses through the groove 5 into each vortex chamber 6, as shown by the white arrows in FIG. A swirling flow is generated independently within each swirling chamber 6 guided by the arcuate outer shell 6a. child In this way, six swirling flows are generated for each fuel spray from each nozzle hole. This prevents the fuel sprays from colliding with each other, and allows the fuel and air to flow in the late stages of combustion. This promotes mixing of the ingredients and reduces smoke.

0012 In the process in which the fuel spray is guided to the swirl chamber 6 through the groove 5, some of the fuel is transferred to the vortex chamber 6. Although the diffusion is toward the bottom surface 3a of the groove, the diffusion table 7 is raised on the extension of each groove 5. As a result, the jet that reaches the diffusion table 7 as fuel spray or flame is reflected on this reflective surface 7a. The fuel is reflected and diffused into the swirl chamber 6, and the fuel adheres to the surface of the piston 2 and remains unburned. In addition to preventing smoke from being emitted, it also prevents the flame temperature from decreasing and smoke generation. Life is suppressed. In addition, in the process in which the fuel spray is guided to the swirl chamber 6 through the groove 5, The fuel that adheres to the cavity bottom surface 3a, becomes a wall flow, and reaches each diffusion table 7 is reflected on the reflecting surface. It peels off from the curved piston surface from 7a to the upper surface 7b and spreads into the swirl chamber 6. The swirling flow generated in each vortex chamber 6 promotes mixing with air, resulting in smoke. etc. can be suppressed.

[0013] Next, another embodiment shown in FIGS. 3 and 4 has a cavity formed in the piston 20. 23, a pair of swirl chambers 26 each extending in a substantially circular shape on the extension of the six grooves 25. It is equipped with the following.

[0014] Each swirl chamber 26 has a circular shape that expands symmetrically about the center line o of each nozzle orifice. A portion of the circular arcs intersect with each other between adjacent swirl chamber portions 26. The bottom surface 23a of the cavity is provided with fuel that is guided to the swirl chamber 26 on the extension of each groove 25. A diffusion platform 27 is formed which protrudes to face the material spray. This diffusion table 27 is shown in the plan view. It is located on the center line o of the nozzle nozzle hole and is formed into a trapezoid.

[0015] The cavity bottom surface 23a is formed between the lower region 24b of the common chamber 24 and each swirl chamber 26. A lower region 26b is formed parallel to the piston top surface 22a, and each groove 25 The lower region 25b of the piston 20 is inclined so that it gradually descends toward the outside in the radial direction of the piston 20. It's slanted. The diffusion table 27 has a reflective surface 27a that is inclined at a predetermined angle from the cavity bottom surface 23a, An upper surface 27b extending parallel to the cavity bottom surface 23a and a top surface 27b extending parallel to the cavity bottom surface 23a. It has a back surface 27c that is tilted at a predetermined angle.

[0016] In this case, during the main injection of the fuel injector 1, the fuel diffuses in the radial direction with a relatively strong force. The fuel spray penetrates the ignition kernel formed in the common chamber 24 during initial injection and forms a flame jet. It spreads through each groove part 25 and into each swirl chamber part 26 while becoming a As shown by the arrows, each swirl chamber 2 is guided by the outer shell 26a projecting in a V-shape. 6, a swirling flow is created. In this way, the fuel spray from each nozzle hole is By generating a pair of swirling flows, the velocity of the swirling flows is increased and the combustion is accelerated in the late stage of combustion. further promotes mixing of material and air.

[0017] In the process in which the fuel spray is guided to the swirl chamber 26 through the groove 25, some of the fuel is The flame spreads toward the cavity bottom surface 23a, but it also spreads along the extension of each groove 25. Because the table 27 is raised, it reaches the diffusion table 27 as fuel spray or flame. The fuel is reflected by this reflecting surface 27a and diffused into each swirl chamber 26, and the fuel is absorbed into the piston. This prevents it from adhering to the surface of the ton 22 and being discharged unburned, and also prevents fire. Smoke generation is suppressed by preventing a drop in flame temperature. In addition, the bottom surface of the cavity 2 The fuel that adheres to the surface 3a and reaches each diffusion table 27 as a wall flow flows through the reflection surface 27a and the upper surface. 27b and the back surface 27c, it peels off from the surface of the diffusion table 27 and forms the vortex chamber 2. 6, and the swirling flow generated in each swirl chamber 26 promotes mixing with air. The occurrence of smoke, etc. can be suppressed.

[0018]

[Effect of the idea]

As explained above, the present invention provides a combustion chamber for a direct injection diesel engine. The cavity extends from the common chamber below the fuel injection valve along the fuel injection direction. It is equipped with a plurality of grooves that extend in a direction, and a plurality of grooves that extend in a substantially circular shape on the extension of each groove. A vortex chamber is provided, and a groove is formed on the bottom of this cavity to be guided to each vortex chamber on the extension of each groove. Equipped with a diffusion platform that rises in opposition to the fuel spray, the fuel spray adheres to the bottom of the cavity. This reduces the amount of fuel and promotes the mixing of fuel spray and air to increase air utilization. As a result, unburned HC and smoke emissions are reduced, and engine output is increased. The transformation is measured.

[Brief explanation of drawings]

FIG. 1 is a plan view of a piston showing an embodiment of the present invention.

FIG. 2 is a longitudinal cross-sectional view taken along line AA in FIG. 2;

FIG. 3 is a plan view of a piston showing another embodiment.

FIG. 4 is a longitudinal cross-sectional view taken along line A-A in FIG. 3;

FIG. 5 is a plan view of a piston showing a conventional example.

[Explanation of symbols]

1 Fuel injection valve 2 piston 3 Cavity 3a Bottom of cavity 4 Common room 5 Groove 6 Whirlpool chamber 7 Diffusion stand 10 Combustion chamber

Claims (1)

[Scope of utility model registration request] Claim 1: A diesel engine that defines a combustion chamber between a cavity recessed in the top surface of a piston and a cylinder head, and includes a fuel injection valve that injects fuel radially from a plurality of nozzle injection holes into the combustion chamber. , in the cavity;
It includes a plurality of grooves extending along the fuel injection direction from a common chamber below the fuel injection valve, and a plurality of swirl chambers that expand in a substantially circular shape on the extension of each groove,
A combustion chamber for a diesel engine, characterized in that the bottom surface of the cavity is provided with a diffusion platform that protrudes on the extension of each groove to face the fuel spray guided to each swirl chamber.