JPH0650151A - Diesel engine - Google Patents

Abstract

PURPOSE:To reduce the generation of black smoke and particulates in exhaust gas by activating dispersion combustion especially at the second half stage of combustion of a diesel engine through collision of air and combustion gas. CONSTITUTION:A main combustion chamber 21 which is formed approximately in a spherical shape and the inlet part of which is throttled is formed at the central part of the top surface of a piston 12. An auxiliary combustion chamber 22 which is formed approximately in a spherical shape approximately symmetrical to the main combustion chamber 21 is formed on the under surface of a cylinder head 15. Fuel is simultaneously injected in the main and auxiliary combustion chambers 21 and 22 through a fuel injection nozzle 20 obliquely arranged to the cylinder head 15 at an angle approximately equal to a horizontal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diesel engine, and more particularly to a diesel engine in which fuel is injected by a fuel injection nozzle and burned by spontaneous ignition.

[0002]

2. Description of the Related Art In a diesel engine, by moving a piston to the top dead center side, intake air in the cylinder is compressed and kept in a high temperature state, and fuel is injected in synchronization with the piston almost reaching top dead center. The fuel is injected from the nozzle, and the fuel spray is spontaneously ignited by the heat of intake air to perform combustion.

The fuel spray injected from the fuel injection nozzle is mixed with intake air in a combustion chamber formed by a recess formed on the top surface of the piston to form a mixture, and this mixture is burned. ing.

[0004]

It is necessary for combustion that a good mixture is formed. If only the fuel spray is locally present and the mixture with the air is not sufficient, the fuel spray in that portion does not burn, which causes generation of black smoke and particulates. Therefore, the shape of the combustion chamber formed on the top surface of the piston is devised, for example, a recess is provided in the wall surface, or the combustion chamber is made a reentrant type. Alternatively, there is a combustion chamber having a rectangular shape when viewed from above.

By taking such measures, the flow of air in the combustion chamber is activated, mixing with the fuel spray is improved, and smoke generation is suppressed. However, in the conventional direct-injection diesel engine, it is impossible to completely mix the fuel and the intake air, so that the generation of smoke cannot be reduced to zero. Although high-pressure fuel injection has been attempted in view of such problems, there is a drawback that the cost of the injection device becomes high.

The present invention has been made in view of these problems, and diffused combustion of a diesel engine, particularly in the latter stage of combustion, is activated by collision of air and combustion gas in the combustion chamber, which causes black smoke and patties. An object of the present invention is to provide a diesel engine designed to reduce curate.

[0007]

According to the present invention, in a diesel engine in which fuel is injected by a fuel injection nozzle and burned by spontaneous ignition, a substantially spherical main combustion chamber is formed facing the top of the piston. A substantially spherical auxiliary combustion chamber is formed in the cylinder head so as to face the main combustion chamber substantially symmetrically when the piston reaches the top dead center, and the main injection chamber and the auxiliary combustion chamber are formed by the fuel injection nozzle. The present invention relates to a diesel engine characterized by injecting fuel into a room.

[0008]

The fuel spray injected into the main combustion chamber and the auxiliary combustion chamber by the fuel injection nozzle is spontaneously ignited in each combustion chamber, and the flame thus generated causes the main combustion chamber and the auxiliary combustion chamber. Spread toward the exit side of. Then, at the outlets of the main combustion chamber and the sub combustion chamber which are arranged so as to face each other, the flames diffused from these main combustion chamber and the sub combustion chamber collide violently. As a result, combustion becomes more active in the latter stage of diffusion combustion, and the remaining fuel spray associates with oxygen to suppress the generation of black smoke and particulates.

[0009]

1 shows a main part of a diesel engine equipped with a fuel injection device according to an embodiment of the present invention, in which a cylinder block 10 is provided with a cylinder 11 consisting of a through hole. A piston 12 is slidably arranged in the cylinder 11. The piston 12 is connected to the connecting rod 14 by a piston pin 13.

The upper opening of the cylinder 11 is closed by a cylinder head 15, and the cylinder head 15 has an intake port 16 and an exhaust port 1.
7 and 7 are formed respectively. These intake ports 1
6 and the exhaust port 17 are opened and closed by an intake valve 18 and an exhaust valve 19, respectively. Further, a fuel injection nozzle 20 is obliquely attached to the cylinder head 15, and faces a main combustion chamber 21 formed on the top surface of the piston 12 and a sub combustion chamber 22 formed on the lower surface of the cylinder head 15. To inject fuel.

The fuel injection nozzle 20, as shown in FIG.
It is connected to the corresponding pump unit 26 of the fuel injection pump 25 by the injection pipe 24. Fuel injection pump 25
Is equipped with a mechanical governor 27, and the mechanical governor 27 moves a control rack 28 to adjust the supply amount of fuel injected at one time. The fuel injection pump 25 has a cam shaft 29, and a cam 30 attached to the cam shaft 29 drives each pump unit 26. A timer 31 is provided on the camshaft 29, and the timing of injection is adjusted by the timer 31.

The fuel injection nozzle 20, as shown in FIG.
The tip portion is composed of a nozzle body 34, and two nozzle holes 35 are formed at the tip portion of the nozzle body 34. The nozzle body 34 is attached to the nozzle holder 37 by a retainer 36. A nozzle needle 38 is slidably held in the nozzle body 34.
The upper end of the nozzle needle 38 has a pressing rod 39.
The compression coil spring 40 in the nozzle holder 37 presses it downward. As a result, the nozzle needle 38 is pressure-bonded to the valve seat 41 formed on the nozzle body 34 to shut off the fuel. Further, the nozzle holder 37 is formed with a fuel passage 42 communicating with the injection pipe 24. The fuel passage 42 communicates with the fuel passage 43 of the nozzle body 34. A fuel sump 51 is formed at the end of the fuel passage 43.

The upper end of the spring 40 pressing the pressing rod 39 is received by the spring receiver 44. An adjusting screw 45 is attached to the upper end of the spring receiver 44. The adjusting screw 45 is screwed with a female screw 46 formed on the inner peripheral surface of the nozzle holder 37. Further, a protrusion 48 is formed on the side surface side of the nozzle holder 37, and a male screw 49 is formed on the protrusion 48, and a connection nut 50 screwed with the male screw 49.
The injection pipe 24 is connected to the nozzle holder 37.

Next, the structure of each pump unit of the fuel injection pump 25 will be described. As shown in FIG. 3, a tappet 55 is attached to the lower end of the plunger 54.
The tappet 55 is pressed downward by the compression coil spring 56, and thereby pressed against the outer peripheral surface of the cam 30. A spill port 58 is formed in the barrel 57 in which the plunger 54 is slidably fitted, and an inclined groove 59 is formed in the outer peripheral surface of the plunger 54 so as to substantially face the spill port 58. ing.

A pinion 60 is rotatably supported on the outer peripheral side of the barrel 57. A control sleeve 61 is fixed to the pinion 60 and a notch 62 formed in the control sleeve 61.
Receives the engagement plate 63. The engagement plate 63 is fixed to the plunger 54.

A delivery valve 64 is provided on the outlet side of each pump unit 26, and is arranged on a valve seat 66 provided at the bottom of the casing 65.
The coil spring 67 presses the delivery valve 64 toward the valve seat 66.

Next, the outline of the operation of the direct injection diesel engine having the above-mentioned structure will be described.

The timer 31 is controlled by a part of the output of the engine.
When the camshaft 29 is driven via the camshaft 29, the cam 30 having the shape shown in FIG. 3 pushes up the roller of the tappet 55, which causes the plunger 54 to move.
Move up in 7. Then, the top surface of the plunger 54 closes the spill port 58 and starts the pressure feeding of the fuel. When the plunger 54 moves further upward, the inclined groove 5
9 aligns with the spill port 58, whereby the pressure in the space above the plunger 54 escapes to the spill port 58 side through the inclined groove 59, and the pumping of fuel is completed.

Mechanical governor 2 of fuel injection pump 25
When the 7 moves the control rack 28, the pinion 60 is rotated, which causes the control sleeve 6 to move.
1 will be rotated. The rotation of the control sleeve 61 is transmitted to the plunger 54 via the notch 62 and the engaging plate 63, and the plunger 54 is rotated in the barrel 57. Therefore spill port 5
8, the effective stroke determined by the position of the inclined groove 59 aligned with 8 is changed, the fuel is metered,
The supply amount of fuel injected at one time is controlled. The timer 31 provided on the camshaft 29 of the fuel injection pump 25 controls the phase angle of the camshaft 29 and adjusts the fuel injection timing.

When the plunger 54 pumps fuel in the barrel 57, the delivery valve 64 is opened and the fuel is pumped to the fuel injection nozzle 20 through the injection pipe 24. The fuel passage 4 of the fuel injection nozzle 20 shown in FIG.
When fuel pressure is applied to the fuel sump 51 through 2 and 43, the nozzle needle 38 moves through the rod 39 into the spring 4
0 is compressed and moves upward, whereby the tip end side portion of the nozzle needle 38 separates from the valve seat 41, and fuel is injected through the injection port 35. When the pressure feed of the fuel is completed, the elastic restoring force of the spring 40 pushes the nozzle needle 38 downward via the rod 39, and the tip end thereof is pressed against the valve seat 41 to stop the fuel injection.

The fuel is sprayed by the injection port 3 of the fuel injection nozzle 20.
5, the fuel is injected toward the main combustion chamber 21 formed on the top surface of the piston 12 and the auxiliary combustion chamber 22 formed on the lower surface of the cylinder head 15 shown in FIG.
Then, this fuel spray is spontaneously ignited by the heat of the compressed intake air, combustion occurs in the cylinder 11, the piston 12 is pushed downward, and the output of the engine is taken out. After this, the exhaust valve 19 is opened, and exhaust gas is discharged through the exhaust port 17.

The main combustion chamber 21 formed at the top of the piston 12 is a relatively small combustion chamber having a substantially spherical shape, and its inlet portion is narrowed. A sub combustion chamber 22 is formed on the lower surface of the cylinder head 15 so as to face the main combustion chamber. The auxiliary combustion chamber 22 has a size and a shape that are substantially symmetrical to the main combustion chamber 21 when the piston 12 reaches the top dead center, and has a spherical shape with a narrowed inlet portion. Has become.

The main combustion chamber 21 and the sub combustion chamber 22 into which the fuel is injected by the fuel injection nozzle 20 are formed on the top surface of the piston 12 and the bottom surface of the cylinder head 15, respectively. When the piston 12 reaches the top dead center, the main combustion chamber 21 and the sub combustion chamber 22 are arranged so as to be substantially symmetrical as shown in FIG. In addition, the inlet portions of these combustion chambers 21 and 22 are narrower than the inner portions, so as to form a collision combustion portion.

Therefore, when the fuel spray is injected from the fuel injection nozzle 20 as described above as shown in FIG. 1, the fuel spray strikes the bottom wall surfaces of the main combustion chamber 21 and the sub combustion chamber 22 and is ignited. The flame generated by this spreads in these combustion chambers 21 and 22 toward the outlet side. That is, at this time, the diffusion combustion process is already under way. The flame has a large kinetic energy when it reaches the exit portion of the combustion chambers 21, 22.

The flame from the lower main combustion chamber 21 and the flame from the upper sub-combustion chamber 22 are combined into these combustion chambers 2.
At the outlets of 1, 22 they will collide with air and combustion gases. That is, the outlet portions of the main combustion chamber 21 and the auxiliary combustion chamber 22 form a collision combustion portion, and the collision of air and combustion gas is further activated in this portion. As a result, combustion becomes more active in the latter stage of diffusion combustion. This suppresses the generation of black smoke and particulates due to the oil droplets of the fuel spray that remain unburned.

As described above, the fuel injection nozzle 20 is obliquely attached to the cylinder head 15 at an angle substantially horizontal, and the fuel is injected into the main combustion chamber 21 of the piston 12 and the auxiliary combustion chamber 22 of the cylinder head 15 by Combustion of a diesel engine, particularly diffuse combustion in the latter stage of combustion, is activated by collision of air and combustion gas in the combustion chamber, and black smoke and particulates can be reduced.
This brings an advantage that the emission control of diesel engine is easy.

[0027]

As described above, according to the present invention, a substantially spherical main combustion chamber is formed facing the top of the piston, and when the piston reaches the top dead center, it is substantially opposed to the main combustion chamber. A substantially spherical auxiliary combustion chamber is formed in the cylinder head, and fuel is injected into the main combustion chamber and the auxiliary combustion chamber by a fuel injection nozzle. Therefore, the flame generated by the spray of the fuel injected into the main combustion chamber and the auxiliary combustion chamber diffuses by violently colliding with each other at the exit portion of these combustion chambers, and especially the diffusion combustion in the latter stage of combustion is performed in the combustion chamber. It becomes active due to the collision of air and combustion gas, it becomes possible to reduce black smoke and particulates, and it becomes easy to comply with strict exhaust gas regulations.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a direct injection diesel engine according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a fuel injection nozzle.

FIG. 3 is a perspective view of a main part of a fuel injection pump.

[Explanation of symbols]

 10 Cylinder Block 11 Cylinder 12 Piston 13 Piston Pin 14 Connecting Rod 15 Cylinder Head 16 Intake Port 17 Exhaust Port 18 Intake Valve 19 Exhaust Valve 20 Fuel Injection Nozzle 21 Main Combustion Chamber 22 Secondary Combustion Chamber 24 Injection Pipe 25 Fuel Injection Pump 26 Pump Unit 27 Mechanical governor 28 Control rack 29 Cam shaft 30 Cam 31 Timer 34 Nozzle body 35 Nozzle 36 Retainer 37 Nozzle holder 38 Nozzle needle 39 Push rod 40 Spring 41 Valve seat 42, 43 Fuel passage 44 Spring bearing 45 Adjusting screw 46 Female screw 47 Cap 48 protrusion Part 49 Male screw 50 Connection nut 51 Fuel sump 54 Plunger 55 Tappet 56 Coil spring 57 Barrel 58 Spill port 59 Inclined groove 60 Pinion 61 Control sleeve 62 Notch 63 Engagement plate 64 Delivery valve 65 Casing 66 Valve seat 67 Coil spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Suzuki 3-1-1 Hinodai, Hino-shi, Tokyo Hino Motors Ltd. (72) Inventor Tsunesuke Fujii 3-1-1 Hinodai, Hino-shi, Tokyo Hino Motors Co., Ltd. (72) Inventor Makoto Endo 3-1-1 Hinodai, Hino City, Tokyo Hino Motors Co., Ltd.

Claims (1)

[Claims] 1. Injecting fuel with a fuel injection nozzle,
In a diesel engine that is designed to burn by spontaneous ignition, a substantially spherical main combustion chamber is formed facing the top of the piston, and when the piston reaches the top dead center, it faces the main combustion chamber in a substantially symmetrical manner. Thus, the diesel engine is characterized in that the substantially spherical auxiliary combustion chamber is formed in the cylinder head, and the fuel is injected into the main combustion chamber and the auxiliary combustion chamber by the fuel injection nozzle.