JPH0874698A - Binary injection valve of diesel engine - Google Patents

Abstract

PURPOSE: To realize a fuel injection valve for a diesel engine capable of allowing combustion with less black smoke and high efficiency. CONSTITUTION: An inner side nozzle 9 and a fuel valve nozzle 2 are mounted below an injection valve main body 1 by means of a tightening cap 3, and an inner side needle valve 10 and an outer side needle valve 5 are vertically slidably inserted respectively in the center of the inner side nozzle 9 and the fuel valve nozzle 2, and they are pushed downward by needle valve pressing springs 11, 4. Fuel forcibly-fed from a fuel oil passage 6 is injected from an outer side injection hole 8. A fluid, different from fuel, such as air introduced from a fluid passage 15 is injected in the center of fuel atomization from the inner side injection hole 16 provided with its a center shaft coaxial with the outer side injection hole 8, and mixture at the center part or the top end part of fuel injection is improved so as to prevent generation of a fuel over- concentrated range. The inner side needle valve 10 is raised and opened by operational oil introduced from an operational oil passage 12.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a fuel injection valve for a diesel engine.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional example of a fuel injection valve for a diesel engine. In the fuel injection valve shown in FIG.
Attach the fuel valve nozzle 2a to the fuel valve body 1a and tighten the cap 3a.
The needle valve 5a and the needle valve pressing spring 4a are attached to the center of the fuel valve nozzle 2a.

Next, the operation of this fuel injection valve will be described. When the pressure feed of fuel from a fuel injection pump (not shown) starts, the pressure wave reaches the fuel oil sump 7a via the fuel oil passage 6a of the fuel injection valve, but the force of the needle valve pressing spring 4a set in advance causes the fuel oil sump to accumulate. When the internal hydraulic pressure overcomes, the needle valve 5a rises and fuel injection starts from the fuel valve injection hole 8a.
The fuel injected into the cylinder of the diesel engine from a is atomized by the kinetic energy of the fuel itself and the shearing force of the surrounding air, forms a combustible mixture while undergoing the process of evaporation and mixing with the surrounding air, and self-ignites. Then burns.

[0004]

However, the conventional fuel injection valve has the following drawbacks. The fuel injected into the cylinder is in the form of so-called Solid Injection in which only the fuel is injected at high pressure from the fuel valve injection hole 8a.
The injected fuel forms a combustible air-fuel mixture through the processes of atomization, evaporation, and mixing, self-ignites, and starts combustion.

As described above, in the form of diffusion spray combustion by Solid Injection, the fuel spray region is not uniform, and there are always a fuel rich region, a theoretical mixing region and a fuel lean region,
In particular, there is a fuel rich region at the center and the tip of the spray, which causes the generation of black smoke.Furthermore, in the latter part of the injection, the kinetic energy of the spray itself decreases due to the decrease of the injection pressure. Further black smoke is generated due to the lower mixing energy.

It is an object of the present invention to provide a fuel injection valve for a diesel engine, which is capable of overcoming the above-described conventional spray structure of the fuel injection valve and performing efficient combustion with low black smoke.

[0007]

In order to solve the above-mentioned problems in a fuel injection valve of a diesel engine, the present invention comprises an automatic valve for a fluid different from fuel, which is vertically slidably arranged in a central portion. An inner needle valve, an outer needle valve concentric with the inner needle valve, which is slidably arranged on the outer periphery of the inner needle valve, and which is an automatic valve for fuel oil, and the inner needle valve and the outer needle valve are provided in respective seats. The two-fluid injection valve has respective needle valve pressing springs to be pressed.

The central axis of the inner injection hole for the fluid different from the fuel provided at the tip of the inner needle valve and the outer injection hole for the fuel injection provided at the tip of the outer needle valve have the same central axis. Then, the structure is formed at the tip of the injection valve.

[0009]

The fuel injection valve according to the present invention has the above-mentioned structure, and the outer needle valve is pushed upward against the needle valve pressing spring by the fuel oil pressure supplied from the fuel injection pump, and the outer side for fuel injection is provided. Fuel injection starts from the injection holes. on the other hand,
The inner needle valve is pushed upward against the needle valve retainer spring by the hydraulic pressure from the hydraulic oil pump, and a fluid different from the fuel that has been pressurized above the cylinder internal pressure, such as air, is sprayed through the inner injection hole. By injecting toward the central axis, the air introduction rate to the fuel rich region at the center and the tip of the fuel spray is increased.

The time relationship between the operation of the fuel injection pump and the hydraulic oil pump can be set arbitrarily by making the operation of the double needle valve independent, and the injection of the fluid different from the fuel is slightly delayed from the start of the fuel injection. , Which continues during the fuel injection period and ends a little later than the end of the fuel injection, causes a different fluid from the fuel to follow the fuel spray whose kinetic energy has decreased in the latter and final injection stages. By supplying, the decrease in the kinetic energy of the fuel spray itself is compensated, and the mixing is promoted by the stronger turbulence.

According to the above-described operation, according to the two-fluid injection valve of the present invention, the fuel rich region at the central portion or the tip portion in the spray is provided concentrically with the outer injection hole for fuel injection,
The kinetic energy is strongly given by the supply of the fluid such as the air ejected from the inner nozzle hole for the fluid different from the fuel to promote the mixing, and the strong turbulence suppresses the generation of black smoke and the good combustion Cause

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A fuel injection valve according to the present invention will be specifically described below with reference to an embodiment shown in FIG. In the illustrated injection valve, an inner nozzle 9 and a fuel valve nozzle 2 are stacked under a two-fluid injection valve body 1 and assembled into one body by a tightening cap 3.

At the center of the inner nozzle 9, an inner needle valve 10 pushed downward by an inner needle valve pressing spring 11 is vertically slidably arranged, and an outer needle is provided between the inner nozzle 9 and the fuel valve nozzle 2. An outer needle valve 5 pushed downward by a valve retainer spring 4 is arranged so as to be vertically slidable. Reference numeral 12 is a hydraulic oil passage for raising the inner needle valve 10, 15 is a fluid passage for a fluid different from fuel, and 6 is a fuel oil passage.

Up to the seat portion 14 provided at the lower end of the inner needle valve 10 located at the center of the two-fluid injection valve body 1 for sealing a fluid different from the fuel, the pressure in the cylinder is made higher than the pressure in the cylinder by a pressurizing device (not shown). Water different from pressurized fuel,
Fluids such as air and steam are constantly supplied.

The high-pressure fuel sent from a fuel injection pump (not shown) passes through the fuel oil passage 6 in the fuel valve and acts on the outer needle valve seat portion 7 provided at the lower end of the outer needle valve 5 to seal the fuel. Outer needle valve retainer spring 4 provided on the outer needle valve 5
When the outer needle valve 5 rises, fuel is injected from the outer injection hole 8 into the cylinder of the diesel engine at high pressure.

On the other hand, hydraulic oil sent from a hydraulic oil pump (not shown), which is arbitrarily set to start the injection of a fluid different from the fuel slightly later than the start of the fuel injection, passes through the hydraulic oil passage 12 in the fuel valve and passes through the inner needle. When acting on the hydraulic operating portion 13 provided on the upper side surface of the valve 10 and overcoming the force of the needle valve pressing spring 11 provided on the upper portion of the needle valve 10, the inner needle valve 10 rises, and as described above, up to the seat portion 14. A fluid different from the pressurized fuel being supplied is supplied through the inner injection hole 16 toward the central axis of the fuel spray.

During the fuel injection period, the injection of the fluid different from the fuel is continued, and after the latter period of the fuel injection and after the end of the fuel injection, the fluid different from the fuel is supplied afterward and the injection is terminated.

As described above, in the injection valve according to this embodiment, the inner injection hole 16 for ejecting a fluid such as air having a different central axis is provided inside the outer injection hole 8 for injecting fuel. Since a fluid such as air is ejected toward the central axis of the fuel spray injected from the outer injection holes 8, the mixing can be favorably performed in the center of the fuel spray or where the fuel is likely to be concentrated in the tip. As a result, according to the present injection valve, generation of black smoke can be suppressed and good combustion can be performed.

[0019]

As described above, according to the two-fluid injection valve of the present invention, a fluid different from the fuel is supplied from the inner injection hole that is concentrically provided inside the fuel injection nozzle that exits from the outer injection hole. By injecting, it is possible to increase the introduction and mixing of air and the like to the fuel rich region at the center of the fuel spray and at the tip.

Further, the injection of a fluid different from the fuel is started slightly later than the start of the fuel injection, the injection of the fluid different from the fuel is continued during the fuel injection period, and the fuel injection is slightly delayed from the end of the fuel injection. Is operated so as to terminate the injection of different fluids, ensuring self-ignition of the fuel spray, and compensating for the decrease in the kinetic energy of the fuel spray itself after and after the end of fuel injection, and promoting mixing due to stronger turbulence. High efficiency combustion with low black smoke can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a two-fluid injection valve according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a conventional fuel injection valve.

[Explanation of symbols]

 1 Two-fluid injection valve body 2 Fuel valve nozzle 3 Tightening cap 4 Outer needle valve retainer spring 5 Outer needle valve 6 Fuel oil passage 7 Outer needle valve seat portion 8 Outer nozzle hole 9 Inner nozzle 10 Inner needle valve 11 Inner needle valve retainer Spring 12 Hydraulic oil passage 13 Hydraulic pressure operating portion 14 Inner needle valve seat portion 15 Fluid passage different from fuel 16 Inner injection hole

Claims (1)

[Claims] 1. An inner needle valve that is vertically slidably arranged in a central portion and is an automatic valve for a fluid different from fuel, and an outer peripheral portion is vertically slidably concentric with the inner needle valve. An outer needle valve consisting of an automatic valve for fuel oil, and respective needle valve pressing springs for pressing the inner needle valve and the outer needle valve against their respective seats, and the fuel provided at the tip of the inner needle valve. Different from the above, an inner injection hole for fluid and an outer injection hole for fuel injection provided at the tip of the outer needle valve are formed at the tip of the injection valve with their central axes being the same. Two-fluid injection valve for diesel engine.