JPH0742557A - Large two-cycle direct injection type methanol engine - Google Patents

Abstract

PURPOSE:To improve thermal efficiency and to reduce a production cost by a method wherein the composite angle of pilot methanol spray satisfies a specified expression while an inter-center distance between the nozzle of an auxiliary fuel value and a glow plug and a diameter of a nozzle satisfy a specified expression. CONSTITUTION:The axis CC1 of a nozzle for pilot spray C1 passing the nozzle center phi1 of an auxiliary fuel valve 1 and the axis CC2 of the nozzle for a pilot spray C2 have respective projections on a horizontal plane which are overlapped with each other. The axis CC1 has an upward angle thetaC1 to a horizontal line H1 passing through the tip of the nozzle and the axis CC2 has a downward angle thetaC2 to the horizontal line H1, and satisfy a condition of 20 deg.C<=(thetaC1+thetaC2)<=37.5 deg.. Nozzles for pilot sprays D1 and D2 from an auxiliary fuel valve 2 are formed in a similar manner described above. Provided a distance between the nozzle centers phi1 and phi2 of the auxiliary fuel valves 1 and 2 to the centers of glow plugs 3 and 4 is L and a diameter of a nozzle is dn, the glow plugs 3 and 4 are mounted so that an expression of 55<=(L/dn)<=120 is eastablished. This constitution performs reliable ignition of methanol spray, improves thermal efficiency, and reduces a production cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion chamber structure for a large two-cycle direct injection type methanol engine.

[0002]

2. Description of the Related Art As an example of a conventional large-cycle two-cycle methanol engine, the structure thereof will be described with reference to FIG. 10 showing a vertical sectional view of a combustion chamber of Japanese Patent Application No. 3-87233. In the figure, 1 and 2 are auxiliary fuel valves, 3 and 4 are glow plugs, 5 and 6 are injection ports communicating from the auxiliary combustion chambers B1 and B2 to the main combustion chamber A, 7 and 8 are main fuel valves, and U is U. A cylinder head, W is an exhaust valve, X is a piston, and Y is a cylinder liner. Further, C and D represent pilot sprays injected from the auxiliary fuel valves 1 and 2, and Z1, Z2 and Z3 represent main sprays from the main fuel valve 7.

Next, the operation will be described. The pilot spray C of methanol injected from the auxiliary fuel valve 1 into the auxiliary combustion chamber B1 is ignited by the glow plug 3 and burned, and combustion gas is ejected from the injection port 5 to the main combustion chamber A. On the side of the auxiliary combustion chamber B2 as well, the pilot spray D is similarly ignited and burned at the same time, and the combustion gas is ejected from the injection port portion 6 to the main combustion chamber. The pilot sprays C and D are relatively easy to ignite and burn stably in the sub-combustion chambers B1 and B2, and the jet flow of the combustion gas serves as so-called seed fire from the main fuel valves 7 and 8 to the main combustion chamber A. It ignites and burns the main spray of methanol injected into.

[0004]

The reason why the auxiliary combustion chamber system is adopted in the large-sized methanol engine is that stable ignition and combustion are relatively easy in the auxiliary combustion chamber, and the combustion gas ejected from the injection port is a pilot flame. This is because the main spray injected into the main combustion chamber is reliably ignited and burned. However, the auxiliary combustion chamber system has the following drawbacks. That is, since the combustion gases of the pilot sprays C and D are squeezed out by the injection ports 5 and 6 and are ejected, there is a loss due to the squeeze, which hinders improvement of thermal efficiency. In addition, there are drawbacks such as burnout of the injection ports 5, 6 and difficulty in ensuring the reliability of the auxiliary combustion chambers B1 and B2, and the production cost of the engine itself is increased due to the formation of the auxiliary combustion chamber. Problems have also been pointed out.

The object of the present invention is to solve the above-mentioned drawbacks and to reliably ignite the methanol spray even at the time of start-up or low load, and to provide a reliable large-sized two-cycle direct type which can improve the thermal efficiency and reduce the production cost. An injection type methanol engine is provided.

[0006]

A large two-cycle direct injection type methanol engine of the present invention is a large two-cycle direct injection type methanol engine using 100% methanol as a fuel, and is a cylinder paired symmetrically with a cylinder axis. It has auxiliary fuel valves 1 and 2 and glow plugs 3 and 4 mounted on the head, and main fuel valves 7 and 8, and the direction of pilot spray injected from the auxiliary fuel valve and the injection from the main fuel valve. Each of the main spray directions is injected in a direction having a component in the same direction as the swirl generated in the main combustion chamber A, and two pilot sprays are provided from each of the sub fuel valves for each of the sub fuel valves. The axis of the injection port of the pilot injection nozzle overlaps with its projection on the horizontal plane and is 2 with respect to the horizontal line passing through the nozzle tip of the auxiliary fuel valve.
The axis of each nozzle has an upward angle θC1 and a downward angle θC2.
And the combined angle (θC1 + θC
2) satisfies the condition of 20 ° ≦ (θC1 + θC2) ≦ 37.5 °, and the glow plugs 3 and 4 are mounted on the extension of the axis of the pilot spray nozzles of the auxiliary fuel valves 1 and 2, and When the distance between the centers of the nozzle and the glow plug is L and the nozzle injection port diameter is dn, 55 ≦ (L / dn) ≦ 12
It is characterized in that the condition of 0 is satisfied.

[0007]

The large-sized two-cycle methanol engine according to the present invention adopts the direct injection system and is constructed as described above, so that the following effects can be obtained. Combustion tends to be unstable in a methanol engine at the time of starting or under low load, and attention is paid to the total hydrocarbon emission concentration as an index for determining the quality of ignition at that time. From each of the sub fuel valves 1 and 2, the axis of the nozzle nozzle has an upward angle θC1 and a downward angle θ.
Although the C2 pilot methanol spray is injected, by appropriately setting the synthetic angle (θC1 + θC2), the above-mentioned total hydrocarbon emission concentration can be reduced. FIG. 7 shows an example of experimental results regarding the relationship between the value of (θC1 + θC2) and the total hydrocarbon emission concentration. Compared with the value at the time of ¼ load in the auxiliary combustion chamber system according to the conventional technique represented by the two-dot chain line, the value of (θC1 + θC2) is 20 ° ≦ (θ
C1 + θC2) ≦ 37.5 ° was found in the region set to 37.5 °, and it can be determined that ignition by pilot injection is being performed stably.

A further condition for improving the ignitability is the distance L between the center of the nozzle of the auxiliary fuel valve and the glow plug. Let the diameter of the nozzle of the pilot injection nozzle be dn, and define the dimensionless center-to-center distance by (L / dn). Figure 8 shows the dimensionless nozzle-glow plug distance (L / dn) and total hydrocarbon emission concentration. Regarding the relationship of, the example of the experimental result when (θC1 + θC2) is set to 35 ° is shown. Expressed by a dotted line, compared with the value at the time of ¼ load in the auxiliary combustion chamber method according to the conventional technique,
In the region where the value of (L / dn) is 55 ≦ (L / dn) ≦ 120, it can be determined that the total hydrocarbon emission concentration is reduced and the ignitability is improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a large two-cycle direct injection type methanol engine in which the combustion chamber is composed of only the main combustion chamber, and the fuel used is 100% methanol including pilot injection,
No specific auxiliary fuel for starting is used. 1 and 4 are longitudinal sectional views showing the arrangement structure of the main fuel valve of the direct injection type methanol engine according to the first embodiment of the present invention, and FIGS. 2 and 5 are the auxiliary fuel valve and the glow in the engine of FIG. It is a longitudinal cross-sectional view showing the arrangement structure of the plug. FIGS. 3 and 6 show FIGS.
3 and 4 are explanatory views of the spray pattern in the main combustion chamber of the engine shown in FIGS. The configuration will be described with reference to FIGS. In these figures, 1 and 2
Is a sub fuel valve, 3 and 4 are glow plugs, 7 and 8 are main fuel valves, A is a main combustion chamber, U is a cylinder head, W is an exhaust valve,
X is a piston. The main combustion chamber A is formed in the upper part of the cylinder in a space surrounded by the piston X, the exhaust valve W, and the cylinder head U, and the main fuel valves 7 and 8 and the auxiliary fuel valves 1 and 2 are formed.
The glow plugs 3 and 4 are mounted in a pair symmetrically with respect to the axis of the cylinder.

From the main fuel valve 7, methanol main spray Z1,
Z2 and Z3 are injected, and main spray Y1 is also supplied from the main fuel valve 8.
Although Y2 and Y3 are injected, the injection direction of these main sprays is the same as the direction component of the swirl generated in the main combustion chamber. Methanol pilot sprays C1 and C2 are injected from the sub fuel valve 1 and pilot sprays D1 and D2 are also sprayed from the sub fuel valve 2. The injection direction of these pilot sprays is generated in the main combustion chamber as in the case of the main spray. It is injected in a direction having a component in the same direction as the swirl. In addition, the axis CC1 of the nozzle of the pilot spray C1 passing through the nozzle center φ1 of the auxiliary fuel valve 1 and the pilot spray C
The projections of the two nozzles on the horizontal plane of the nozzle line CC2 overlap each other, and have an upward angle θC1 and a downward angle θC2 with respect to a horizontal line H1 passing through the tip of the nozzle, and 20 ° ≦ (θ
C1 + θC2) ≦ 37.5 °. The injection ports of the pilot sprays D1 and D2 from the sub fuel valve 2 have the same structure.

The glow plug 3 is mounted on an extension of the axial lines CC1 and CC2 (both projections of the axial lines overlap on the horizontal plane) of the injection ports of the pilot sprays C1 and C2 of the auxiliary fuel valve 1.
Further, the glow plug 4 is a pilot fuel spray D for the auxiliary fuel valve.
Corresponding to 1 and D2, it is installed similarly. In addition, from the nozzle centers φ1 and φ2 of the auxiliary fuel valves 1 and 2, to the glow plugs 3 and 4
The glow plugs 3 and 4 are attached so that 55 ≦ (L / dn) ≦ 120, where L is the distance to the center of the nozzle and dn is the nozzle orifice diameter.

Next, the operation and effect of the above configuration will be described. The methanol pilot sprays C1 and D1 injected from the auxiliary fuel valves 1 and 2 along the swirl direction are respectively attached to the glow plugs 3
And 4 are contacted and heated to ignite, and the heat of reaction also ignites the pilot sprays C2 and D2 to generate a flame flow as the entire pilot spray flow. Methanol main spray is injected from the main fuel valves 7 and 8 so as to collide with the flame flow generated by the pilot spray flow, and is ignited and burned. With this configuration, accurate ignition and stable combustion, which have hitherto depended on the auxiliary combustion chamber method, can be realized even in the direct injection method.

In a methanol engine, attention is paid to the total hydrocarbon emission concentration as an index for determining the quality of ignition. FIG. 7 shows an example of the experimental results on the relationship between the total hydrocarbon discharge concentration and the value of the combined angle (θC1 + θC2) of the upward angle θC1 and the downward angle θC2 of the axis of the nozzle of the auxiliary fuel valve. Compared with the value at the time of 1/4 load in the auxiliary combustion chamber system according to the conventional technique represented by the two-dot chain line, the value of (θC1 + θC2) is 2
A reduction in the total hydrocarbon emission concentration was observed in the region set to 0 ° ≦ (θC1 + θC2) ≦ 37.5 °, and it can be determined that ignition by pilot injection is being performed stably.

A further condition for improving the ignitability is the distance L between the nozzle of the auxiliary fuel valve and the center of the glow plug. Letting the diameter of the nozzle of the pilot injection nozzle be dn, the dimensionless center-to-center distance is defined as (L / dn).
Regarding the relationship between / dn) and the total hydrocarbon concentration, an example of the experimental result when (θC1 + θC2) is set to 35 ° is shown. The value of (L / dn) is 5 when compared with the value at the time of 1/4 load in the auxiliary combustion chamber system according to the prior art represented by the dotted line.
In the region of 5 ≦ (L / dn) ≦ 120, it can be determined that the total hydrocarbon emission concentration is reduced and the ignitability is improved.

FIG. 9 is an explanatory view of the spray pattern in the main combustion chamber of the engine according to the second embodiment of the present invention.
Unlike the first embodiment, the sub fuel valve 1 is arranged downstream of the swirl SW with respect to the main fuel valve 7. Also in this second embodiment, the same data as the experimental results shown in FIGS. 7 and 8 are obtained.

[0016]

According to the present invention, accurate ignition and stable combustion, which have hitherto depended on the auxiliary combustion chamber system, can be realized by the direct injection system. As a result, the methanol spray can be reliably ignited even at startup or under a low load, thermal efficiency can be improved, production cost can be reduced, and a highly reliable large two-cycle direct injection type methanol engine can be provided.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a spray pattern from a main fuel valve of a large two-cycle direct injection type methanol engine according to a first embodiment of the present invention and an arrangement structure thereof.

2 is a longitudinal sectional view showing a pilot spray pattern from a sub fuel valve and an arrangement structure of a glow plug in the engine of FIG.

FIG. 3 is an explanatory plan view of arrangements of main / sub fuel valves, glow plugs, and spray patterns in the main combustion chamber of the engine shown in FIGS. 1 and 2;

4 is a vertical cross-sectional view showing the injection direction of the main spray in the engine of FIG.

5 is a longitudinal sectional view for explaining pilot spray from the auxiliary fuel valve in the engine of FIG.

6 is an explanatory plan view of an axis line of a nozzle injection port of a main / sub fuel valve and a glow plug arrangement in FIGS. 4 and 5; FIG.

FIG. 7 is a diagram showing an example of experimental results on the combined angle of the nozzle axis of the pilot spray nozzle and the total hydrocarbon emission concentration in the methanol engine according to the present invention.

FIG. 8: Experiment of total hydrocarbon emission concentration about dimensionless center distance (L / dn) by center distance L between auxiliary fuel valve nozzle and glow plug and methanol nozzle diameter dn in methanol engine according to the present invention An example of the result

FIG. 9 is an explanatory plan view of the arrangement structure in the main combustion chamber of the methanol engine according to the second embodiment of the present invention.

FIG. 10 is a vertical cross-sectional view of a combustion chamber of a methanol engine of a sub combustion chamber type according to the related art.

[Explanation of symbols]

1, 2 ... Sub fuel valve, 3, 4 ... Glow plug, 7, 8 ... Main fuel valve, A ... Main combustion chamber, U ... Cylinder head, W ... Exhaust valve, X ... Piston, Z1, Z2, Z3, Y1 , Y2, Y
3 ... Methanol main spray, C1, C2, D1, D2 ... Methanol pilot spray, SW ... Swirl, φ1, φ2 ...
Center of sub fuel valve nozzle, H1 ... Horizontal line, CC1, CC2 ...
Pilot spray nozzle axis, θC1 ... Angle upward of nozzle axis CC1, θC2 ... Angle downward of nozzle axis CC2, dn
... diameter of the auxiliary fuel valve nozzle, L ... distance between the auxiliary fuel valve nozzle and the center of the glow plug.

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[Procedure amendment]

[Submission date] September 24, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

A further condition for improving the ignitability is the distance L between the nozzle of the auxiliary fuel valve and the center of the glow plug. The dimensionless center-to-center distance is defined by defining the nozzle diameter of the pilot injection nozzle as dn and L (L / dn).
Regarding the relationship between / dn) and the total hydrocarbon discharge concentration, an example of the experimental result when (θC1 + θC2) is set to 35 ° is shown. Compared with the value at the time of 1/4 load in the auxiliary combustion chamber system according to the prior art represented by the dotted line, the value of (L / dn) is 55 ≦ (L / dn) ≦ 120 It can be judged that the reduction is seen and the ignition performance is improved.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location F02P 19/00 A (72) Inventor Kunihiko Shimoda 12 Nishiki-cho, Naka-ku, Yokohama-shi, Kanagawa Mitsubishi Heavy Industries Shares Company Yokohama Institute

Claims (1)

[Claims] 1. A large size 2 using 100% methanol as fuel.
In a cycle direct injection type methanol engine, auxiliary fuel valves (1) and (2) and glow plugs (3) and (4), which are symmetrical to the axis of the cylinder and which are mounted on the cylinder head in pairs, and the main fuel valve ( 7) and (8), the direction of the pilot spray injected from the auxiliary fuel valve and the direction of the main spray injected from the main fuel valve are both swirl generated in the main combustion chamber A. Two pilot sprays are injected from each of the auxiliary fuel valves for each auxiliary fuel valve, and the axis of the injection port of the pilot injection nozzle is projected on its horizontal plane. The axes of the two nozzles have an upward angle θC1 and a downward angle θC2 with respect to a horizontal line that overlaps and passes through the nozzle tip of the auxiliary fuel valve. The combined angle (θC
1 + θC2) is 20 ° ≦ (θC1 + θC2) ≦ 37.5
Is satisfied, the glow plugs (3) and (4) are mounted on the extension of the axis of the pilot fuel spray nozzles of the auxiliary fuel valves (1) and (2), and the nozzles of the auxiliary fuel valve and the glow plug are attached. When the center-to-center distance is L and the nozzle nozzle diameter is dn,
A large two-cycle direct injection type methanol engine, which satisfies the condition of 55 ≦ (L / dn) ≦ 120.