JP2001132549A - Fuel mixing device for gas engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve engine performance by improving uniformity of mixing of gas fuel and air supply, in a fuel mixing device of a gas engine. SOLUTION: An injector 13 for supplying gas fuel is disposed on an air supply branch pipe 12 connected to an air supply port of each cylinder, and blades 22 for generating swirl flow are disposed. Preferably, an nozzle pipe 21 of the injector 13 is extendedly disposed to a nearly center part of a circulating cross section of the air supply branch pipe 12, a plurality of blades 22 are radially disposed around the nozzle pipe 21, a plurality of injection hales 23 opened outward the diameter direction are formed between blades 22 in the nozzle pipe 21. Within a limited mixing distance, mixing is promoted, and uniform air-fuel mixture is thus formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel mixing apparatus for mixing gas fuel and air supply of a gas engine, and more particularly, to a gas engine having an injector for supplying fuel in an air supply pipe connected to an air supply port. The present invention relates to a fuel mixing device suitable for a fuel cell.

[0002]

2. Description of the Related Art In a gas engine having a structure in which an injector is disposed in an air supply pipe connected to an air supply port, since the distance from the injector to the combustion chamber is short, the gas fuel and the air supply must be sufficiently uniformly mixed. Is difficult. As a countermeasure, for example, in the invention described in Japanese Patent Application Laid-Open No. Hei 9-158785, as shown in FIG.
Injector 113 is connected to air supply pipe 112 connected to
, The injector 113 has a plurality of fuel injection directions F1,.
1 is provided, and among a plurality of ejection directions, a large amount of gas fuel is ejected in an ejection direction F1 which is affected by the supply air dynamic pressure, that is, in a direction opposed to the flow of the supply air. Achieve uniform mixing.

[0003]

As shown in FIG. 7, simply devising the injection direction and amount of gaseous fuel as shown in FIG. 7 is a short path from the injector to the combustion chamber, and is limited from the fuel injection to the ignition timing. It is difficult to achieve a sufficiently homogeneous mixture of the gas fuel and the supply air in time.

In particular, when a structure as shown in FIG. 7 is applied to a so-called multi-point injection type multi-cylinder gas engine in which injectors are arranged in respective supply branch pipes, mixing of gas fuel and supply air is performed. In order to secure the required mixing distance, the injector is placed near the air supply manifold, but if this is done, much of the gas fuel is blown out against the air supply. The possibility that a part of the gas fuel flows out to the collecting pipe increases, and the variation in the gas fuel supply amount among the cylinders increases. As a result, abnormal combustion may occur in a cylinder having an excessive amount of fuel, and a knocking phenomenon may occur.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to make it possible to forcibly generate a swirl flow in an air supply pipe from which fuel is injected from an injector, and to achieve sufficiently uniform mixing within a short distance and time range. It is to be.

[0006]

According to the first aspect of the present invention, an injector for supplying gaseous fuel and a swirl flow generating plate are provided in an air supply pipe connected to an air supply port of a cylinder. A fuel mixing device for a gas engine.

According to a second aspect of the present invention, in the fuel mixing device for a gas engine according to the first aspect, a nozzle pipe of the injector is extended to a substantially central portion of a flow cross section of the air supply pipe, and the swirl flow generating plate is provided. A plurality of blades are radially arranged around the nozzle tube, and the nozzle tube is formed with a plurality of ejection holes that open radially outward between the blades.

According to a third aspect of the present invention, in the fuel mixing device for a gas engine according to the first or second aspect, a plurality of cylinders are provided, and the supply port of each cylinder is branched from a supply manifold as a supply pipe. The air supply branch pipes are connected to each other, and an injector and a swirl flow generating plate are arranged in each air supply branch pipe.

[0009]

FIG. 1 is a partial front view of a six-cylinder gas engine to which the present invention is applied. An air supply manifold 1 is mounted on the front upper side of a cylinder head 2. One end in the length direction is connected to an intercooler 5 via a throttle valve 3, and the intercooler 5 is connected to an air intake device such as an air cleaner via a supercharger (not shown). The part is closed by a lid 6. The throttle valve 3 is connected to a rotary actuator 8 such as a motor, and the actuator 8 is connected to a control device so that the throttle opening can be adjusted.

[0010] In the air supply manifold 1, downwardly projecting branch pipes 10 are integrally formed at equally spaced positions in the length direction, and a cylinder head is provided at the lower end of each branch pipe 10. The extension pipes 11 that curve to the two sides are connected to each other, and the branch pipe 10 and the extension pipe 11 constitute an air supply branch pipe 12. Each of the extension pipes 11 is provided with an injector 13 for supplying gaseous fuel, thereby constituting a so-called multipoint injection type fuel supply structure.

FIG. 2 is an enlarged cross-sectional view taken along the line II-II of FIG. 1. The downstream end of each extension pipe 11 is directly connected to the inlet end of the air supply port 15 of each cylinder. The injector 13 is attached to the center of the entire length of the extension pipe 11 in the direction of the tube core O1 from obliquely below, and the nozzle pipe 21 of the injector 13 extends substantially vertically upward in the extension pipe 11 toward the air supply collecting pipe 1 side. Extends to The tip portion of the nozzle tube 21 is located at the center of the flow section of the extension tube 11, and at the tip portion of the nozzle tube, the tube core O2 of the nozzle tube 21 and the tube core O1 of the extension tube substantially match.

At the tip of the nozzle tube 21, four blades 22 are fixed radially at equal intervals in the circumferential direction as a swirling flow generating plate (swirl generating plate). It has a shape twisted with respect to 21 and generates a swirling flow S as shown by a white arrow. A plurality of ejection holes 23 are formed at the tip of the nozzle tube 21, and the ejection holes 23 are formed in the same cross section (III-III cross section) as the position on the nozzle tube 21 to which the blade 22 is attached. Further, as shown in FIG. 3, the ejection holes 32 are respectively arranged between the adjacent blades 22, so that the gas fuel is ejected outward in the radial direction.

[0013]

In FIG. 1, the air supplied from the supercharger or the like to the air supply manifold 1 via the intercooler 5 and the throttle 3 is distributed into each air supply branch pipe 12. In FIG. 2, in each air supply branch pipe 12, the supply air supplied from the branch pipe 10 into the extension pipe 11 is guided by the blades 22 so that the main flow becomes a swirl flow, and at the same time, the air supply from The gas fuel ejected outward enters the swirl flow of the supply air. Then, the supply air and the gas fuel are sufficiently uniformly mixed by the above-mentioned swirling action, and the inside of the extension pipe 11 and the supply port
5 to the combustion chamber.

Further, by extending the extension pipe 11 between the branch pipe 10 and the supply port 15, the distance from the branch port of the supply manifold 1 to the combustion chamber of each cylinder is extended, and
Since the blades 22 and the ejection holes 23 are arranged in the extension pipe 11 at a position close to the supply manifold 1, the mixing distance from the fuel ejection position to the combustion chamber is extended, and the uniform mixture of the mixture is also increased. Is improved.

[0015]

Other Embodiments (1) The embodiment shown in FIGS. 5 and 6 is an example in which a blade 22 as a swirling flow generating plate is separated from a nozzle pipe 21 and fixed to the air supply branch pipe 12 side. . That is, a plurality of blades 22 arranged radially
Is mounted on the mounting plate 2 via the annular retainer 25 and the support rod 26.
7, the mounting plate 27 is connected to the branch pipe 10 and the extension pipe 11
And sandwiched between. The mounting structure of the blade 22 to the supply branch pipe 12 may be, for example, the annular retainer 25 directly fixed to the inner peripheral surface of the extension pipe 11, and is not limited to the mounting structure of FIG.

(2) As shown in FIG. 2, the structure in which the ejection holes 23 are formed in the same cross section (III-III cross section) as the mounting position of the blade 22 is most effective for uniform mixing of gas fuel and air supply. However, the invention according to claim 1 of the present application is arranged such that, for example, with respect to the blade 22 at the mounting position shown in FIG.
3 is also included, and even in this case,
Compared to the structure without the blade 22, the uniformity of the air-fuel mixture is improved.

FIG. 4 shows the amount of exhausted NOx on the vertical axis as an index of the non-uniformity of mixing of gas fuel and air supply, and the horizontal axis shows the equivalence ratio of gas fuel to air supply (corresponding to the reciprocal of the air-fuel ratio). 2) and FIG. 5 (Graph X1), in the case of the structure according to the present invention shown in FIG. 2 and FIG. 5 (Graph X1), when the position of the ejection hole 23 is changed to the position B with respect to the blade position in FIG. 2 is a comparison between a case in which the blade 22 is removed from the structure in FIG. 2 (graph X3) and a case in an ideal state in which air supply and gas fuel are completely mixed in advance (graph X4). As compared with the graph X3 of the structure without the blade, FIG.
When the position of the blade 22 and the position of the ejection hole 23 are aligned as shown in FIG. 5, the degree of non-uniformity can be suppressed to a state close to the graph X4 in a substantially ideal state, and as shown in the graph X2. Even when the positions of the blades 22 and the ejection holes 23 are shifted, the degree of non-uniformity can be significantly reduced as compared with the conventional structure X3.

(3) The structure of the swirling flow generating plate is not limited to the plurality of blades 22 as shown in FIGS. 2 and 5, and for example, a spiral blade can be attached. Further, in a structure in which a plurality of blades 22 are radially arranged as shown in FIG. 3, the number of blades 2 can be two, three, five or more. A plurality may be arranged.

[0019]

As described above, according to the invention of the present application: (1) Since an injector for supplying gaseous fuel and a swirl flow generating plate are provided in an air supply pipe connected to an air supply port of a cylinder. Within a limited mixing distance to the combustion chamber, mixing can be promoted and a uniform mixture can be obtained.
In particular, in the case of a multi-cylinder gas engine, the engine performance is suppressed by suppressing the variation between cylinders and without causing the transfer of gas fuel from the air supply branch pipe to the other air supply branch pipe via the air supply manifold. Can be improved.

(2) Since the mixing of the gaseous fuel and the supply air is promoted and the mixing time can be set short, the fuel injection period can be set long, whereby the pressure of the supplied fuel can be kept low. Gas compressor power can be saved.

(3) The nozzle pipe of the injector is extended to substantially the center of the flow cross section of the air supply pipe, and a plurality of blades are radially arranged around the nozzle pipe as a swirling flow generating plate. When a plurality of ejection holes that open outward in the radial direction are formed between the blades, gas fuel is ejected radially from the center of the swirling flow toward the swirling flow. The uniformity of the air is further improved.

[Brief description of the drawings]

FIG. 1 is a front view of a multi-cylinder gas engine to which the present invention is applied.

FIG. 2 is an enlarged cross-sectional view taken along the line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III in FIG. 2;

FIG. 4 is a diagram showing the difference in the degree of non-uniformity of the air-fuel mixture between the present invention and a conventional example, etc., using the exhausted NOx amount as an index.

FIG. 5 is an enlarged cross-sectional view showing another embodiment.

6 is a sectional view taken along line VI-VI of FIG.

FIG. 7 is a longitudinal sectional view showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air supply collecting pipe 2 Cylinder head 10 Branch pipe 11 Extension pipe 12 Air supply branch pipe (an example of an air supply pipe) 13 Injector 15 Air supply port 21 Nozzle pipe 22 Blade (an example of a swirling flow generation plate) 23 Jet hole

Claims (3)

[Claims] An injector for supplying gaseous fuel is provided in an air supply pipe connected to an air supply port of a cylinder.
A fuel mixing device for a gas engine, comprising a swirl flow generating plate. 2. A nozzle pipe of an injector is extended to a substantially central portion of a flow cross section of an air supply pipe, and a plurality of blades are radially arranged around the nozzle pipe as a swirling flow generating plate. 2. The fuel mixing device for a gas engine according to claim 1, wherein a plurality of ejection holes that open outward in the radial direction are formed between the blades. 3. A plurality of cylinders, each of which is connected to an air supply port of each cylinder as an air supply pipe and an air supply branch pipe branched from an air supply collecting pipe. 3. The fuel mixing device for a gas engine according to claim 1, wherein a plate is arranged.