JPH09228898A - Mixed member and intake pipe shape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the mixed property of gaseous fuel with air, and thereby contrive to stabilize an idle operating condition, in a gaseous fuel injection valve by providing a mixing member giving turbulence to the tip end of an injection valve or facilitating injection of fuel reversely against an air flow. SOLUTION: A gaseous fuel injection valve for a gas engine using gaseous fuel such as natural has as fuel, allows a plunger to be raised up when a coil is energized, and also allows fuel to be injected out of a nozzle when a valve 305 is separated from a valve seat. In order to provide turbulence in fuel injection at this point of time, a turbulence promoter 402 is thereby formed at the downstream side of the nozzle 308. By this constitution, the direction of an air flow is changed with respect to fuel injection out of the nozzle when furl passes through the turbulence promoter 402 so as to allow collision and dispersion to be accelerated. As an another way to enhance the mixing property, a device can for example, be cited, which has a mixing member having a plurality of fuel injection ports over the side surface of a cylinder a pipe shape.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a mixing member and an intake pipe of a gas fuel injection valve for a gas engine.

[0002]

2. Description of the Related Art Gaseous fuels such as natural gas and hydrogen gas have been spotlighted as environmentally friendly fuels. When applying these gaseous fuels to a conventional gasoline engine,
Since the specific gravity difference between air and fuel, that is, the density of gaseous fuel is smaller than that of gasoline, the penetrating force into the air flow is reduced, and the homogeneity is deteriorated. If a homogeneous air-fuel mixture cannot be produced, the air-fuel mixture formation in the cylinder will be unevenly distributed, combustion will become irregular, and engine rotation will become unstable. This measure has not been considered yet. Therefore, the present invention proposes a method for improving the mixing property by giving turbulence to the gaseous fuel flow or the intake air flow for the purpose of uniformly mixing the gaseous fuel such as CNG and the intake air to improve combustion.

[0003]

In an internal combustion engine in which the fuel system has been changed from that for gasoline to that for gas, homogeneous mixing occurs due to the spray angle of the gas fuel, the spray diffusion state, and the density difference that occurs as compared with the case of liquid fuel. It has been found that there is a problem of deterioration of combustion property and combustion irregularity associated therewith.

An object of the present invention is to stabilize the idle operation state where combustion is likely to be irregular.

[0005]

In a fuel injection valve for a gas mounted on a gas engine that uses a gaseous fuel such as natural gas as a fuel, a member for imparting turbulence to the fuel and a direction opposite to a direction of intake air are provided. A member for ejecting fuel is provided and configured and arranged so as to promote the stirring effect, and the mixing speed is improved by increasing the relative speed of the gaseous fuel and the intake air. As another method, two stages of spiral fins are formed in the intake pipe, and the turbulence of the air flow generated by them is utilized to promote agitation.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the structure of a gas fuel system and an intake air system in the MPI system. A gaseous fuel such as natural gas is delivered from a fuel tank 101 which is stored in a high pressure state of about 200 MPa, and a pressure reducing valve 102 for reducing the fuel pressure to a constant pressure and a pressure gauge 103 for displaying the fuel pressure are used to supply about 500 kPa. In this state, the gas fuel is injected into the fuel injection valve 107. This fuel injection valve 107
Is installed on the upstream side of the intake valve 108, and measures and injects gaseous fuel at an optimum timing according to a command from the control unit. When gasoline is used as fuel in the conventional method, the intake valve 108 is used to avoid adhesion of fuel to the wall surface.
Although the spray angle was set so as to inject fuel toward, the problem of fuel adhesion does not occur when using gaseous fuel. In particular, in the case of inhalation process injection, there is no problem even if the injection is performed against the air flow. On the other hand, the air that has passed through the air cleaner 104 is measured by an air flow meter, passes through the throttle body 105, and is distributed by the collector 106 to the intake port portion 110 of each cylinder. The gaseous fuel and air injected from the fuel injection valve 107 at the intake port 110 are mixed and absorbed in the cylinder 109.

FIG. 2 shows an example of the state of engine speed during idle operation when gasoline and gas fuel are used. Both are the results when the ISC (Idle Speed Control) valve 112 is not functioning.
When changing from the middle speed range to low speed by changing the opening degree of the engine, in the case of gasoline fuel, the rotation continues sufficiently stably even in the low speed range, but in the case of gaseous fuel such as natural gas, the engine stops midway. . This is due to the characteristics of the gaseous fuel, and is lightweight C
It is considered that NG is not uniformly mixed with the intake air and is absorbed into the cylinder as it is, so that the air-fuel mixture near the spark plug 113 in FIG. 1 goes out of the flammable region and misfire occurs. When a certain kind of liquid fuel is injected and mixed in the air stream, the heavier fuel has a larger inertia and thus has a flying opportunity to come into contact with more air and is mixed well. That is, since gasoline has a heavier weight than gaseous fuel, the mixing property is improved. With the conventional injection valve and spray angle, the fuel is injected in the same direction as the flow direction of the intake air, and the relative velocity cannot be obtained and the fuel is sucked into the cylinder without being sufficiently mixed.

FIG. 3 shows a sectional view of a conventional gas fuel injection valve 301. A predetermined current is supplied to the injection valve 301 via the electrode terminal 302, magnetism is generated in the coil 303, the plunger 304 is pulled up, the valve 305 is separated from the valve seat portion 306, and a gap is generated. The fuel supplied from the nozzle is injected from the nozzle 308 to the outside. Plunger 304 lifted
Has a structure that stops when the flange portion 309 formed on the plunger 304 collides with the stopper 310. In the conventional configuration, since there is no obstacle in the downstream passage of the valve 305, the fuel moves downstream while diffusing in a cone shape. This does not result in intimate mixing with air.

FIG. 4 shows an example of a concrete improvement measure according to the present invention. Since the injected fuel 401 creates turbulence, the nozzle 3
A turbulence promoter 402 is formed on the downstream side of 08. In the conventional method, turbulence is not generated in the injected fuel, but in the method according to the present invention, the fuel ejected from the nozzle 308 passes through the turbulence promoter 402, the direction of the air flow is changed and collides, and diffusion is promoted. To be done. Since the gaseous fuel flowing in the same direction as the intake air flow is ejected in a different direction, it easily collides with the intake air flow and promotes mixing. Turbulence promoter 40
The cross section of 2 may be circular or polygonal. As shown in a specific example, a polygon such as a triangle is desirable.

FIG. 5 presents another method for improving the mixing property. The extension pipe 502 is attached to the tip of a conventional fuel injection valve, and a plurality of fuel injection ports 501 are provided on the side surface of the extension pipe 502. No turbulent flow is formed in the fuel 401 immediately after being injected from the nozzle 308, but when the fuel is injected from a plurality of fuel injection ports 501, the flow is against the intake air flow, so that mixing progresses and is improved. .
Further, as shown in FIG. 6, if the air inlet 601 is provided on the side surface of the extension pipe 502 facing the upstream side of the intake pipe, and the dynamic pressure of the air is taken in, the injected fuel 401 and the intake air are sufficiently stirred in the extension pipe 502. The formed homogeneous mixture 602 is ejected from the inside of the pipe, which has the effect of improving stirring. Also,
The gaseous fuel does not remain in the extension pipe 502, and the accuracy of fuel metering can be improved.

FIG. 7 shows an application example of FIG. 5, in which an air passage 701 is provided near the base of the extension pipe 502, and as shown in FIG. 1, the air passage 701 and the air pipe 111 upstream of the throttle 105 are bypassed to generate an air flow. Using the negative pressure in the guiding air pipe, it is installed so that air blows out from the direction perpendicular to the fuel 401 injected from the nozzle 308, and the air and fuel are sufficiently stirred in the pipe 502, and a homogeneous mixture 602 is obtained.
And is injected from the fuel injection port 501. The injected air-fuel mixture violently collides with the air flowing through the intake pipe, further promoting uniform mixing.

FIG. 8 shows an application example of a fuel injection valve having an air assist mechanism. Immediately after the fuel is injected from the nozzle, the air is uniformly blown from the surroundings through the air assist member 801, and a uniform air-fuel mixture is formed by the air. Liquid fuels such as gasoline provide sufficient mixing only with these mechanisms, but gas fuel with poor mixing does not sufficiently mix, and mechanisms such as the turbulence promoter 402 in FIG. 4 and the extension pipe 502 in FIG. The combination of the two accelerates the mixing of the gaseous fuel. That is, the problem at the time of using the gaseous fuel can be overcome by promoting the mixing in two steps.

FIG. 9 shows another method for improving the mixing property. When the airflow flowing in one pipe while swirling in one direction is forcibly swirled in the reverse direction, the turbulence of the airflow is always generated at the boundary of conversion. Therefore, in the present invention, the intake pipe 110 has two stages of spiral fins 901-.
1, 901-2 are formed. That is, the second stage spiral fin 901-2 is replaced with the first stage spiral fin 901-2.
The spiral fins 901-1 and 90-1 are provided so as to swirl in a direction opposite to the swirling direction of the air flow by 1-1.
The fuel injection valve 107 for gas is arranged between 1-2. Therefore, in the intake stroke of injecting the gaseous fuel, the air flow is violently disturbed in the intake pipe 110 below the gaseous fuel injection valve 107 as described above, and thus the injected gaseous fuel 4 is injected.
01 and the air swirl flow 902 are likely to collide with each other, and the mixing property is promoted.

FIG. 10 shows a method for disturbing the air flow to improve the mixing property. A part of the intake air is merged from the air pipe on the upstream side of the throttle 105 to the vicinity of the fuel injection valve mounting position of the intake pipe 110 via a bypass. The jet direction 1001 of the air passing through the bypass is the intake pipe 110.
By making the direction perpendicular to the direction of the air flow inside, the air collides and the flow is disturbed. As mentioned above, the air outlet 1
Since 002 is formed near the injection valve mounting position,
The gaseous fuel injected from the fuel injection valve 107 collides with turbulent air immediately after the injection and is sufficiently mixed. Furthermore, C
A dotted line in the figure shows a configuration that makes use of the properties of the gaseous fuel such as that the gaseous fuel such as NG is lighter than air and does not adhere to the wall surface. In other words, install the fuel injection valve under the intake pipe,
Further, a pipe for changing the direction of spraying is provided at the tip of the injection valve to inject fuel along the bottom of the intake pipe.
The injected fuel rises by nature. If the outlet 1002 is installed on the extension of the traveling direction of the ascending airflow, the air and the fuel collide with each other, and the stirring is further promoted.

FIG. 11 shows another method for disturbing the air flow. As shown in the drawing, an air turbulence member 1101 for changing the flow direction of a part of the air is provided in the intake pipe 110. With this configuration, a part of the air flowing through the intake pipe 110 always passes through the air turbulence member 1101. The air turbulence member 1101 is formed with an ejection port 1102, and the ejection port 1102 is set so that the air flows out in a direction opposite or perpendicular to the normal air flow direction. Therefore, the air that has passed through the air turbulence member 1101 collides with the air that maintains a normal flow, and the air flow is disturbed, and the fuel injector 107 injects the gaseous fuel 401 into the scattered air 1103 at an optimum timing. As a result, the stirring effect can be improved.

[0016]

According to the present invention, the mixing property of gaseous fuel such as natural gas and intake air can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a gas fuel system and an air system in an MPI system.

FIG. 2 is an explanatory diagram of a state of engine speed during idle operation.

FIG. 3 is a sectional view of a conventional fuel injection valve for gaseous fuel.

FIG. 4 is an explanatory view of the shape of a turbulence promoter.

FIG. 5 is an explanatory diagram of a pipe shape for promoting stirring.

6 is an explanatory diagram of an application example of the pipe of FIG.

FIG. 7 is an explanatory diagram of a shape of a mixing member when negative pressure is used.

FIG. 8 is an explanatory view of a tip shape of an injection valve when combined with air assist.

FIG. 9 is an explanatory view of an intake pipe shape for swirling an air flow.

FIG. 10 is an explanatory diagram of an intake pipe shape when negative pressure is used.

FIG. 11 is an explanatory view of an air turbulence member formed in the intake pipe.

[Explanation of symbols]

101 ... Fuel tank, 102 ... Pressure reducing valve, 103 ... Pressure gauge, 104 ... Air cleaner, 105 ... Throttle body, 106 ... Collector, 107 ... Fuel injection valve, 108 ...
Intake valve, 109 ... Cylinder, 110 ... Intake port, 1
11 ... Air pipe, 112 ... ISC valve, 113 ... Spark plug.

Claims (10)

[Claims] 1. A fuel injection valve for gas mounted on a gas engine using gaseous fuel as fuel, wherein the fuel flow is turbulent by attaching to the tip of the injection valve, or in the direction opposite to the direction of the air flow. A mixing member capable of injecting fuel. 2. The mixing member according to claim 1, which is a turbulence promoter having a rod shape and a polygonal cross section. 3. The mixing member according to claim 1, which has a plurality of fuel injection ports on a pipe-shaped side surface. 4. The mixing member according to claim 3, wherein an inlet for taking in the dynamic pressure of air is formed on the side surface of the pipe facing the intake pipe upstream side. 5. The gas fuel injection valve according to claim 3, wherein the gas fuel in the pipe bypasses the air pipe on the upstream side of the throttle and merges a part of the intake air. 6. The fuel injection valve for gas according to claim 1, further comprising an air assist mechanism. 7. An intake pipe in a gas engine using a gaseous fuel as a fuel, comprising a mechanism for swirling or scattering an air flow flowing through the intake pipe. 8. The intake pipe according to claim 7, wherein a first spiral fin is formed inside the intake pipe upstream of a mounting position of the fuel injection valve, and a second spiral fin is formed downstream thereof. 9. The intake pipe according to claim 7, wherein the intake pipe has an air ejection port near the fuel injection position for bypassing an air pipe on the upstream side of the throttle and merging a part of the intake air. 10. The intake air according to claim 7, wherein an air turbulence member is provided in the intake pipe, and the air passing through the member is formed so as to blow out in a direction opposite to or perpendicular to a normal air flow direction. tube.