KR102072703B1 - Direct injection type combustion engine - Google Patents

Abstract

The present invention relates to a direct injection internal combustion engine for improving cold startability. The direct injection internal combustion engine according to the present invention includes an injector and a glow plug, and the cavity is concave on the top surface of the piston, the center of the cavity is deflected from the center of the piston, and the injector tip is positioned on the center axis of the cavity. The injector tip has a fuel injection hole disposed in the circumferential direction, and the fuel injection hole has a plurality of second and third fuel injection holes for forming a fuel injection line toward the outer periphery of the piston with the red portion of the glow plug tip interposed therebetween. And the second and third fuel injection holes, the second and third fuel injection holes being directed toward two equal branch points closest to the glowing portion when the outer periphery of the piston is equally divided by the total number of fuel injection holes. And to form second and third fuel injection lines that are angularly deflected from the third equidistant along the in-cylinder swirl flow direction. The.

Description

Direct injection type combustion engine

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine, and more particularly, to a direct injection internal combustion engine that generates fuel by directly injecting and burning fuel in a cylinder.

A diesel engine is a type of internal combustion engine that draws air into a cylinder, compresses it to high temperature, high pressure, and injects liquid fuel into it, which is powered by an explosion caused by spontaneous combustion and the movement of a piston. Unlike the plug ignition method of the gasoline engine, such a diesel engine is realized as a serial output by the explosion of diesel fuel injected in an evaporated state by the compressed force inside the cylinder generated during the compression stroke of the piston.

Diesel engines can be broadly classified into direct injection methods in which fuel is injected directly into a cylinder maintaining a high-pressure compression environment, and indirect injection types in which a separate sub-combustion chamber is installed and fuel injected therein. Among them, the direct injection diesel engine has the advantage that the noise during combustion is greater than the indirect injection type, but is superior to the indirect injection type in terms of fuel efficiency.

In general, a direct injection diesel engine has a cavity formed in a cylinder and a top surface of a piston that can be lifted up and down inside a cylinder, and a cylinder head is assembled above a cylinder block for forming a cylinder. A fuel injection nozzle for supplying fuel to a combustion chamber partitioned by a piston is provided, and an intake valve and an exhaust valve are provided on one side and the other side based on the fuel injection nozzle.

The direct injection diesel engine configured as described above has the advantage that a separate ignition means such as a spark plug is not required, unlike a gasoline engine, by using a diesel fuel having good ignition so as to fuel spontaneously if a certain temperature or more. When the engine is cooled due to the low temperature environment, such as winter, there is a disadvantage that the start-up is inferior because the initial explosion, that is, the ignition is not smooth.

In order to solve the problem of cold startability in winter, a device which assists to reach the internal temperature of the combustion chamber before start-up to a temperature which is favorable for ignition, such as a glow plug, is generally adopted. There is a problem that it is difficult to expect the improvement of the startability as desired due to the instability of the operation state for a short time until the engine start is implemented and the engine reaches a normal operation state.

Japanese Patent Laid-Open No. 2011-144758 (published July 28, 2011)

The technical problem to be solved by the present invention is to improve the cold startability in winter through the spray layout improvement in consideration of the swirl direction characteristics in the cylinder.

According to the present invention as a means for solving the problem, the injector 15 and the glow plug 16 is provided, the tip of the injector 15 and the glow plug 16 protrudes into the cylinder, the cavity on the top surface of the piston 12 Is formed concave, the center of the cavity 13 is a direct injection type internal combustion engine which is deflected from the center of the piston 12, and the tip of the injector 15 is located on the central axis of the cavity 13,

The tip portion of the injector 15 has a fuel injection hole arranged in the circumferential direction, and the fuel injection hole forms a fuel injection line toward the outer periphery of the piston 12 with the glowing portion 160 at the tip of the glow plug 16 interposed therebetween. And second and third fuel injection holes 152 and 154 and a plurality of first fuel injection holes 150,

The second and third fuel injection holes 152 and 154 face the two equal branch points closest to the glowing portion 160 when the outer periphery of the piston 12 is equally divided into the total number of fuel injection holes. Forming second and third fuel injection lines A2 and A3 angularly deflected from the second and third equipotential lines L2 and L3 along the swirl direction in the cylinder;

The plurality of first fuel injection holes 150 may form a plurality of fan-shaped first fuel injection lines A1 toward the other equal branch limiting two equal branch points to which the second and third equal dividing lines face. To provide a direct injection internal combustion engine.

In the embodiment of the present invention, the second fuel injection line A2 formed by the second fuel injection hole 152 is based on the swirl direction in which the intake of the cylinder flows, and the glow plug 16 The third fuel injection line A3 formed by the third fuel injection hole 154 is formed in the rear region of the glow plug 16. Can be.

In this case, the second fuel injection line A2 is deflected from the second equidistant line L2 toward the integrating portion 160 based on the swirl flow direction, and the third fuel injection line A3 is formed in a third direction. Second and third fuel injection holes 152 and 154 may be formed to be deflected from the three dividing line L3 in a direction away from the glowing portion 160.

Here, the angle α at which the second fuel injection line A2 by the second fuel injection hole 152 is deflected with respect to the second equipotential line L2, and the third fuel injection line by the third fuel injection hole An angle β in which A3 is deflected with respect to the third equal line L3 may be formed differently.

In this case, the deflection angle α of the second fuel injection line A2 with respect to the second equipotential line L2 is the deflection angle β of the third fuel injection line A3 with respect to the third equipotential line L3. It is preferable to configure so that it may become larger than).

According to the direct injection type internal combustion engine according to the embodiment of the present invention, in consideration of the position of the glow plug in the cylinder and the air flow direction (swirl direction) introduced into the cylinder through the intake valve, an optimum that can raise the temperature of the fuel faster By injecting the fuel to the position of the, it is possible to implement an internal combustion engine that can be started cold stably without the auxiliary device for cold start, such as fuel heater or air heater.

1 is a schematic representation of a system relating to direct injection internal combustion engine operation in accordance with an embodiment of the present invention;
Figure 2 is a perspective view of the cylinder is installed from the bottom of the piston of the direct injection internal combustion engine according to the present invention.
3 is a view showing an in-cylinder fuel injection layout by the injector of FIG.
Figure 4 is a schematic diagram for showing the air flow (Swirl direction) in the cylinder during the piston compression stroke.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the present invention, a detailed description of known configurations will be omitted, and a detailed description thereof will be omitted for configurations that may unnecessarily obscure the subject matter of the present invention.

1 is a view schematically showing a system related to a direct injection internal combustion engine operation according to an embodiment of the present invention, and schematically shows only a part of an engine.

An engine system related to engine operation shown in FIG. 1 includes an engine as a power source and an engine ECU (Electronic Control Unit) 1 that collectively controls the operation of the engine. The engine system also includes an injector 15 that directly injects fuel into a cylinder 10 of the engine.

The engine may be a multi-cylinder diesel engine mounted on a vehicle, each cylinder 10 having a piston 12 partitioning the combustion chamber. The piston 12 is freely mounted on the cylinder 10 of the engine, and is connected to a crank shaft (not shown), which is an output shaft member that substantially outputs engine power via a connecting rod 14, respectively. have.

The engine ECU 1 uses the cylinder 10 based on information such as the amount of intake air from the air flow meter 3 and the position of the piston 12 obtained from the crank angle sensor 2. The injection amount and the timing of injection of the internal fuel are determined to transmit an associated signal to the injector 15, and the injector 15 supplies fuel in the cylinder 10 at the fuel injection amount and the injection timing instructed according to the signal. Spray it.

The fuel injected from the injector 15 is evenly mixed by the suction air introduced into the cylinder 10 with the opening of the intake valve 17 in the cylinder 10 and the swirl direction of the suction air, The fuel mixed with the air is combusted by being strongly compressed and ignited in the cylinder 10 by the upward movement of the piston 12. The combustion causes the cylinder 10 to expand and the piston 12 to descend to output. Obtained.

In Fig. 1, reference numeral 4 denotes an accelerator displacement sensor, which detects a driver's accelerator (not shown) operation amount and transmits the detection result to the engine ECU 1. The engine ECU 1 recognizes the displacement amount of the accelerator based on the detected detection result, and adjusts the opening amount of the throttle valve by the amount corresponding to the recognized displacement amount.

The injector 15 has a plurality of fuel injection holes through which a substantial injection of fuel is carried out at its tip portion projecting into the cylinder 10, and is inclinedly mounted on the cylinder head at a constant inclination. The fuel injection hole is arranged so that fuel can be injected in the shape of an umbrella toward the outer periphery of the piston 12, and a preheating plug 16 for preheating the air inside the cylinder 10 at the start of the injector 15 is located on the side of the injector 15. It is located adjacent to.

The glow plug 16 glows by the current applied from the battery at the time of key-on and heats the air inside the cylinder 10. Specifically, the integrating portion 160 of the tip which is substantially integrated by the applied current is inclined to the cylinder head so as to protrude into the cylinder 10, and the cylinder ( 10) The internal air is hot.

The piston 12 is provided with a cavity 13 concave to a certain depth on its top surface. The cavity 13 is arcuately partitioned and its center is deflected from the center of the piston 12. The tip of the injector 15 is positioned on the central axis of the cavity 13 such that the axis extending vertically from the center of the cavity 13 coincides with the center of the tip of the injector 15 having a plurality of fuel injection holes. do

With reference to FIGS. 2 to 4, the configuration in which the cavity is biased with respect to the piston center and the injector is disposed on the cavity center axis, and the fuel injection layout of the injector in consideration of the glow plug position and the glow plug position will be described.

FIG. 2 is a perspective view of a cylinder in which a piston of a direct injection internal combustion engine according to the present invention is viewed from a bottom. FIG. 3 is a view illustrating an in-cylinder fuel injection layout by the injector of FIG. 2. And Figure 4 is a schematic diagram for showing the air flow (Swirl direction) in the cylinder during the compression stroke.

As shown in the figure, the center of the cavity 13 concavely recessed in the top surface of the piston 12 is located offset from the center of the piston 12 and on a central axis extending vertically from the center of the cavity 13. Injector 15 is positioned so that the tip center is located at. A tip glowing portion of the glow plug 16 is located at a position adjacent to the injector 15 and deflected from the center of the cavity 13.

 In the center portion of the cavity 13 recessed surface, a protrusion 130 (see FIG. 1 above) may be formed to form a more dynamic air flow during intake, and is formed along a gentle curved surface continuous from the protrusion 130. The wall surface of the cavity 13 is formed. As shown in FIG. 2, the cylinder is viewed from the bottom, the intake valve 17 and the exhaust valve 18 are substantially symmetrical with respect to the horizontal axis X of the piston 12.

Therefore, when the intake valve 17 is opened and air (hereinafter, referred to as 'intake') is introduced into the cylinder 10 due to the lowering of the piston 12 installed in the cylinder 10, the intake air is the cavity 13 during the compression process. In the space of the protrusions 130 and the ring around the protrusions, as shown by the arrows shown through FIGS. 2 and 4, the air flows downward on the intake valve 17 side and upwards on the exhaust valve 18 side. It forms a swirl.

The fuel is injected into the cylinder 10 through a plurality of fuel injection holes 150, 152, and 154 formed at the tip of the injector 15, which protrudes into the cylinder 10, just before the piston 12 reaches the top dead center during the compression stroke. The fuel is uniformly injected into the air and mixed with the air, and the fuel mixed with the air in the cylinder 10 is spontaneously compressed by the upward movement of the piston 12 to ignite and combust naturally.

Preferably, a plurality of fuel injection holes 150, 152, and 154 are provided at a tip portion of the injector 15 positioned in the piston as shown in FIG. 3 to enable fuel injection toward the outer circumference of the piston 12. A configuration is formed on the same circumference at predetermined intervals.

In the present invention, the fuel injection hole is a plurality of first fuel injection holes 150 and the piston outer periphery (3) between the inlet portion 160 of the tip of the glow plug 16 located in the cylinder, starting from the injector tip portion. And a second fuel injection hole 152 and a third fuel injection hole 154 forming two fuel injection lines A2 and A3 facing the outside.

When the second and third fuel injection holes 152 and 154 are evenly divided (six equal parts) into the total number of fuel injection holes in the outer circumference of the piston 12, the two closest to the glowing portion 160 The second and third fuel injection lines A2 and A3 are angularly deflected from the second and third equipotential lines L2 and L3 facing the equal branch points along the swirl flow direction in the cylinder.

The plurality of first fuel injection holes 150 limit the two equal points to which the second and third equal lines L2 and L3 face, and the fan faces toward the other equal branch points (four equal branch points). A plurality of (four) first fuel injection lines A1 of a shape are formed (see FIG. 3).

The second fuel injection line A2 formed by the second fuel injection hole 152 is based on the swirl flow direction in which the intake of the cylinder flows (see the arrow direction in the drawing). The third fuel injection line A3 formed by the third fuel injection hole 154 is formed in the rear region of the glowing portion 160.

On the basis of the swirl direction, the second fuel injection line A2 is deflected from the second equipotential line L2 toward the red portion 160, and the third fuel injection line A3. The second and third fuel injection holes 152 and 154 are formed to be deflected from the third equipotential line L3 away from the red portion 160.

If the second fuel injection line A2 formed in the area in front of the glowing portion is deflected in a direction closer to the glowing portion 160 as described above, the second fuel injection line may actually be affected by the swirl effect during the compression stroke. A2) passes closer to the glowing portion 160, the fuel temperature is rapidly increased, the overall temperature of the fuel mixed with the air in the cylinder 10 may be increased to improve the cold startability.

The second fuel injection line A2 is biased toward the glowing portion 160 from the second equidistant line L2, and the third fuel injection line A3 is disposed with the glowing portion 160 interposed therebetween. Along the third dividing line L3 equally dividing the outer periphery of the fuel, fuel injection is biased toward the glowing portion 160 such that the overall fuel distribution in the cylinder 10 becomes uneven and the combustion efficiency decreases, resulting in a large amount of smoke. Can be.

Accordingly, the third fuel injection line A3 formed at the rear of the glowing portion 160 in a swirl direction so that the fuel injection can be uniformly distributed throughout the entire area is formed around the piston 12. It is to be deflected in a direction away from the glowing portion 160 from the third dividing line L3 that is equally divided.

In consideration of the mixing of the fuel in consideration of the swirl flow in the cylinder and the temperature rise of the fuel for improving the cold startability, the angle α in which the second fuel injection line A2 is deflected with respect to the second equipotential line L2 is determined. It is preferable to form so that the 3rd fuel injection line A3 by 3 fuel injection holes may make an angle larger than the angle (beta) deflected with respect to the 3rd equidistant line L3.

According to the direct injection type internal combustion engine according to the embodiment of the present invention, the temperature of the fuel can be increased more rapidly in consideration of the position of the glow plug in the cylinder and the air flow characteristic introduced into the cylinder through the intake valve. By injecting the fuel to the optimum position, it is possible to implement an internal combustion engine that can be cold-started stably without the need for an auxiliary device for cold start, such as fuel heater or air heater.

In the detailed description of the present invention, only specific embodiments thereof have been described. It is to be understood, however, that the present invention is not limited to the specific forms referred to in the description, but rather includes all modifications, equivalents, and substitutions within the spirit and scope of the invention as defined by the appended claims. Should be.

1: engine ECU 2: crank angle sensor
3: air flow meter 4: Excel displacement sensor
10 cylinder 12 piston
13: cavity 14: connecting rod
15: injector 16: glow plug
17: intake valve 18: exhaust valve
150: first fuel injection hole 152: second fuel injection hole
154: third fuel injection hole

Claims (5)

The injector 15 and the glow plug 16 are provided, and the tip of the injector 15 and the glow plug 16 protrudes into the cylinder, and the cavity 12 is concave on the top surface of the piston 12, and the cavity 13 is provided. Is a direct injection internal combustion engine which is deflected from the center of the piston 12 and whose tip portion of the injector 15 is located on the central axis of the cavity 13,
The tip portion of the injector 15 has a fuel injection hole arranged in the circumferential direction, and the fuel injection hole forms a fuel injection line toward the outer periphery of the piston 12 with the glowing portion 160 at the tip of the glow plug 16 interposed therebetween. And second and third fuel injection holes 152 and 154 and a plurality of first fuel injection holes 150,
The second and third fuel injection holes 152 and 154 face the two equal branch points closest to the glowing portion 160 when the outer periphery of the piston 12 is equally divided into the total number of fuel injection holes. Configured to form second and third fuel injection lines A2 and A3 that are angularly deflected from the second and third equipotential lines L2 and L3 along the in-cylinder swirl direction,
The plurality of first fuel injection holes 150 are configured to form a plurality of fan-shaped first fuel injection lines A1 toward the other equal branch limiting the two equal branch points facing the second and third equal dividing lines. ,
Based on the swirl flow direction, the second fuel injection line A2 is deflected from the second equidistant line L2 toward the red portion 160, and the third fuel injection line A3 is divided into third equal parts. A direct injection internal combustion engine, characterized in that the second and third fuel injection holes (152) (154) are formed so as to be deflected from the line (L3) away from the glowing portion (160).
The method of claim 1,
The second fuel injection line A2 formed by the second fuel injection hole 152 is based on the swirl direction in which the intake air flows in the cylinder, and the front glowing portion 160 of the glow plug 16. And a third fuel injection line A3 formed by the third fuel injection hole 154 in the rear region of the front end glowing portion 160 of the glow plug 16. Internal combustion engine.
delete The method of claim 1,
The angle α at which the second fuel injection line A2 by the second fuel injection hole 152 is deflected with respect to the second equipotential line L2, and the third fuel injection line A3 by the third fuel injection hole ) Is a direct injection internal combustion engine, characterized in that the angle (beta) is deflected with respect to the third equipotential line (L3).
The method of claim 4, wherein
The deflection angle α of the second fuel injection line A2 with respect to the second equipotential line L2 is greater than the deflection angle β of the third fuel injection line A3 with respect to the third equipotential line L3. Direct injection internal combustion engine, characterized in that.

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