JPH08121286A - Fuel injection device - Google Patents

Abstract

PURPOSE: To reduce quantities of black smoke and hydrocarbon in exhaust gas by regulating an injection angle in fuel spray from a nozzle hole of a fuel injection nozzle. CONSTITUTION: A cone angle of a nozzle hole formed in the tip part of a nozzle main body 34 in a fuel injection nozzle is set to be 180 deg. or more, while a projection quantity of the nozzle main body 34 to the inside of a cylinder is increased, and fuel is injected from the nozzle hole to the vicinity of an edge 71 of a combustion chamber 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device, and more particularly to a fuel injection device which atomizes pressurized fuel and injects it.

[0002]

2. Description of the Related Art In a diesel engine, the intake air is compressed to a high temperature state by moving the piston to the top dead center side, and fuel is injected in synchronization with the piston reaching almost the top dead center. The fuel spray is spontaneously ignited by the heat of the compressed intake air for combustion. Therefore, the diesel engine is usually provided with a fuel injection pump, which pressurizes the fuel and injects the fuel into the cylinder from the injection port of the fuel injection nozzle.

Particularly in a direct injection diesel engine, the injection port 2 is formed on the tip side of the nozzle body 1 of the fuel injection nozzle as shown in FIG. 8 and is formed on the top surface of the piston 3 as shown in FIG. Fuel is injected toward the combustion chamber 4 that is open. Here, in the conventional fuel injection nozzle, the cone angle of the injection port 2, that is, the injection port 2
The apex angle of the cone with the axis of is approximately 140-160 °
The fuel injection amount is set to a value of 1 and the fuel is injected obliquely downward from the injection port 2 toward the inner wall surface of the combustion chamber 4.

[0004]

According to such a conventional fuel injection device, it is not always possible to ideally mix the spray of the fuel injected from the injection port 2 with the air, and There was a problem of containing black smoke and hydrocarbons (HC).

In order to reduce the black smoke in the exhaust gas, high-pressure injection is performed and measures such as forming a reentrant type combustion chamber in the piston are taken. Further, in order to reduce hydrocarbons, measures such as reducing suck volume of the fuel injection nozzle are taken.

In response to such measures, the present invention adjusts the direction of fuel injection from the injection port of the fuel injection nozzle without performing high pressure injection or reducing the suck volume of the fuel injection nozzle. An object of the present invention is to provide a fuel injection device capable of simultaneously reducing black smoke and hydrocarbons in exhaust gas.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a fuel injection device adapted to inject pressurized fuel into an atomized form through an injection port provided at the tip of the fuel injection nozzle, and more particularly to a fuel injection nozzle. 180 ° cone angle
As described above, the fuel is injected through the injection port formed with such a cone angle.

Here, the cone angle of the injection port means the apex angle of a cone having the axis of the injection port as the generatrix and the axis of the fuel injection nozzle as the center line.

In particular, the fuel is injected from the injection port of the fuel injection nozzle toward the vicinity of the edge of the combustion chamber formed on the top surface of the piston, and the fuel is injected in such a direction. As a result, the fuel is injected so as to face the flow of air from the cylinder to the combustion chamber during the upward stroke of the piston, that is, the squish.

[0010]

The fuel is atomized and injected from the nozzle having a cone angle of 180 ° or more. In particular, when the fuel is injected from the injection port of the fuel injection nozzle toward the vicinity of the edge of the combustion chamber of the piston at the above-mentioned cone angle, the flow of air into the combustion chamber, that is, the fuel to be opposed to the squish Will be injected and thus the impingement of the fuel spray on the squish will greatly improve the mixing with the air and achieve a more ideal combustion.

[0011]

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. A fuel injection nozzle 20 is attached to the cylinder head 15 so as to inject fuel toward a combustion chamber 21 formed on the top surface of the piston 12.

The fuel injection nozzle 20, as shown in FIG.
It is connected to the corresponding pump unit 26 of the column fuel injection pump 25 by the injection pipe 24. The fuel injection pump 25 includes a mechanical governor 27, and the mechanical governor 27 moves a control rack 28 to
The amount of fuel that is injected each time is adjusted. The fuel injection pump 25 includes a cam shaft 29, and a cam 30 attached to the cam shaft 29.
Drive 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 of the nozzle body 34 is composed of a nozzle body 34.
5 is formed. 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 is pressed downward by the compression coil spring 40 in the nozzle holder 37 via the pressing rod 39. As a result, the nozzle needle 38 moves the nozzle body 34
It is crimped to the valve seat 41 formed in the above to shut off the fuel. In addition, the nozzle holder 37
A fuel passage 42 communicating with the injection pipe 24 is formed therein. The fuel passage 42 is the fuel passage 43 of the nozzle body 34.
It is designed to communicate with. A fuel sump 51 is formed at the end of the fuel passage 43.

The spring 40 pressing the pressing rod 39 has its upper end received by a 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 pair of protrusions 48 is formed on the side surface side of the nozzle holder 37, male screws 49 are formed on these protrusions 48, and the injection pipe 24 is formed by a connecting nut 50 screwed with these male screws 49. Nozzle holder 37
It is designed to be connected to.

Next, the structure of each pump unit 26 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 delivery valve 64 is pressed toward the valve seat 66 by the coil spring 67.

Next, an outline of the operation of the fuel injection device having the above structure will be described.

A timer 31 is provided depending on a part of the output of the engine.
When the cam shaft 29 of the column fuel injection pump 25 is driven via the cam, the cam 30 pushes up the roller of the tappet 55, which causes the plunger 54 to move upward in the barrel 57. Then, the peripheral 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 59 eventually 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 fuel is pumped. finish.

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 the 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 combustion chamber 21 formed on the top surface of the piston 12 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 cone angle θ of the injection port 35 formed in the nozzle body 34 on the tip side of the fuel injection nozzle of the fuel injection device for injecting fuel in this way is set to 180 ° or more, for example 190 °. As shown in FIG. 5, the protrusion amount L of the nozzle body 34 from the lower surface of the cylinder head 15 is increased. Such a protrusion amount is obtained when the tip of the nozzle body 34 is at the top dead center of the piston 1
No. 2 does not collide with the bottom of the combustion chamber 21, and the spray of fuel injected from the injection port 35 is
It is a value that prevents direct injection onto the lower surface of No. 5.

Since the amount L of projection of the fuel injection nozzle 20 to the lower side of the nozzle main body 34 is increased and the cone angle of the injection port 35 is set to, for example, 190 °, the nozzle main body 34 having such a configuration is used. The fuel spray 70 injected from the injection port 35 is injected toward the vicinity of the edge 71 of the combustion chamber 21 formed on the top surface of the piston 12, as shown in FIG. That is, the fuel is injected obliquely upward from a position lower than in the conventional case, particularly toward the vicinity of the edge 71.

In general, in the upward stroke of the piston 12, as shown in FIG. 6, a flow of air from the cylinder into the combustion chamber 21 toward the inside of the combustion chamber 21, that is, a squish 72 is generated. When the fuel spray 70 is injected toward the edge 71 of the combustion chamber 21, the fuel spray 70 directly faces the squish 72.

Therefore, particularly at high load and when the injection amount is large, the squish 72 promotes the mixing of the fuel spray 70 and the air, and more ideal combustion is performed. By ideally performing the combustion, it is possible to significantly reduce the black smoke in the exhaust gas and suppress the content ratio of hydrocarbons.

Further, according to such a fuel injection nozzle,
The fuel spray 70 is injected from a position away from the lower surface of the cylinder head 15. Therefore, when the penetration force of the fuel spray 70 is small and the spread of the fuel spray 70 is large at the time of light load, the fuel spray 70 does not come into contact with the cylinder head 15 as shown in FIG. 7.
That is, the fuel spray is less likely to be cooled on the lower surface of the cylinder head 15 at the time of light load, which makes it possible to reduce the formation of hydrocarbons especially at light load.

The above embodiment relates to a fuel injection device using a fuel injection nozzle combined with a row type fuel injection pump, but the present invention is a fuel injection device using a unit injector or a pressure accumulation type fuel injection device. It is also applicable to.

[0030]

As described above, according to the present invention, the cone angle of the injection port of the fuel injection nozzle is 180 ° or more. Therefore, the fuel spray is injected obliquely upward, which promotes the mixing with the air introduced into the combustion chamber, which contributes to the reduction of black smoke especially under high load and reduces It is possible to prevent cooling by the cylinder head under load and reduce the production of unburned hydrocarbons.

A second aspect of the present invention is such that fuel is injected from the injection port of the fuel injection nozzle toward the vicinity of the edge of the combustion chamber of the piston. Therefore, in particular, the fuel is injected so as to directly face the air flow, that is, the squish, which occurs in the process of ascending the piston, whereby the mixing with the air is further promoted. Therefore, it becomes possible to provide a fuel injection device capable of achieving more ideal combustion.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a main part of a diesel engine including a fuel injection device 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.

FIG. 4 is an enlarged vertical sectional view of a tip portion of a nozzle body of a fuel injection nozzle.

FIG. 5 is a vertical cross-sectional view of a main part showing a state of fuel injection.

FIG. 6 is a longitudinal cross-sectional view of a main part showing mixing of fuel and air by squish.

FIG. 7 is a vertical cross-sectional view of essential parts showing fuel spray at a light load.

FIG. 8 is a vertical cross-sectional view of a main part of a tip portion of a conventional fuel injection nozzle.

FIG. 9 is a longitudinal sectional view of a main part showing a conventional fuel injection state.

[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 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 Main 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 Thread 47 Cap 48 Projection 49 Male Thread 50 Connection Nut 51 Fuel sump 52 One-way valve 54 Plunger 55 Tappet 56 Coil spring 57 Barrel 58 Spill port 59 Sloping groove 60 Anions 61 the control sleeve 62 the notch 63 engagement plate 64 Deriberibarubu 65 casing 66 valve seat 67 coil spring 70 the fuel spray 71 edge 72 squish

Claims (2)

[Claims] 1. A fuel injector in which pressurized fuel is atomized and injected through an injection port provided at a tip of a fuel injection nozzle, wherein a cone angle of the injection port of the fuel injection nozzle is 180 °. A fuel injection device characterized by the above. 2. The fuel injection device according to claim 1, wherein the fuel is injected from the injection port of the fuel injection nozzle toward the vicinity of the edge of the combustion chamber of the piston.