JPH10316979A - Fuel for direct-jet gasoline engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fuel for direct-jet gasoline engines which can increase engine power while inhibiting black smoke generation. SOLUTION: This fuel contains 5-45 vol.% at least one ether compd. of the formula: R1 OR2 (wherein R1 is methyl; and R2 is 5-6C alkyl, phenyl, or benzyl) and 0-30 vol.% (including 0 vol.%) arom. component other than an ether compd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel for a direct-injection gasoline engine having excellent engine output performance and capable of preventing an increase in black smoke in exhaust gas.

[0002]

2. Description of the Related Art Automobiles are required to have low harmful substances contained in exhaust gas and good fuel economy. Examples of methods for improving fuel efficiency include (1) a method of increasing thermal efficiency by increasing the compression ratio of the engine, and (2) a method of reducing pump loss, which is a mechanical loss, by Linburn combustion with an increased excess air ratio.

However, in an engine having a high compression ratio as in (1), knocking is likely to occur, so that gasoline having a high octane number is required. Even a commercially available gasoline having a high octane number has an octane number of about 100, and there is a limit in improving the compression ratio. The upper limit of the excess air ratio in the Linburn combustion of (2) is about 1.2. If the excess air ratio is further increased, the combustion becomes unstable, and the output is reduced, the drivability is deteriorated, and the exhaust gas performance is easily deteriorated.

On the other hand, in recent years, a direct injection gasoline engine that sprays fuel directly into a combustion chamber and ignites sparks has attracted attention as a technique for achieving both improvement in fuel efficiency and improvement in engine output. In particular, when fuel is sprayed into the combustion chamber in the compression step at low load (hereinafter referred to as late injection), it is said that stable combustion can be achieved even with an excess air ratio of about 5, and the fuel efficiency may be greatly improved. There is.

[0005] However, conventional gasoline fuel is premised on that the fuel sprayed by an intake manifold is guided to a combustion chamber in an intake process and is compressed and burned, and is suitable for late injection and combustion of a direct injection gasoline engine. Not necessarily. Specifically, when the load is low, the fuel is ignited immediately after being sprayed into the combustion chamber, so that the fuel concentration locally increases and black smoke (soot) is easily generated. In a state where soot is generated, ignition may be incomplete due to clogging of the injection valve or carbon adhering to the spark plug. Therefore, a fuel suitable for a direct injection gasoline engine is required.

[0006] In order to suppress the generation of soot in the late injection, the concentration of the saturated aliphatic hydrocarbon gasoline base material having excellent flammability may be increased. However, such a fuel has a low calorific value per volume, so that the engine output may be insufficient at a high load in which the fuel is sprayed (referred to as the former injection) in an intake process corresponding to the conventional combustion. This is because the fuel is light and the calorific value per volume is low. For this reason, there has been a demand for a fuel that does not cause lightening of the fuel and that can suppress the occurrence of soot in the latter-stage injection and combustion.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems. In the fuel for a direct-injection gasoline engine, the output performance of the engine at high and medium loads is not reduced. -To provide a fuel that generates less soot in combustion.

[0008]

As a result of diligent studies by the present inventors, gasoline to which methyl-t-amyl ether (TAME) has been added can suppress the generation of soot in the latter injection, and at the time of medium and high load. We found that the engine output improved. Result of further study, a methyl group and R ₁ ether compound R ₁ -O-R _2, an alkyl group of R ₂ to 5 to 6 carbon atoms, a phenyl group, be changed to a one selected from benzyl , And TAME. Further, the concentration of the ether compound is 5 to
It was found that the effect was effective in the range of 45% by volume, and the present invention was completed.

That is, the above-mentioned problem is solved by the ether compound (R
₁-OR_TwoR₁Is a methyl group, R _TwoHas 5 to 6 carbon atoms
Select from the group consisting of alkyl, phenyl, and benzyl groups
Containing 5 to 45% by volume of at least one of
The problem was solved by using a fee.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a base material of the gasoline of the present invention, straight-run gasoline obtained by atmospheric distillation of crude oil or soft naphtha, cracked gasoline obtained by catalytic cracking, hydrocracking or thermal cracking, etc. , A reformed gasoline obtained by catalytic reforming, etc., an alkylate obtained by adding a lower olefin such as propylene to a lower hydrocarbon such as isobutane and alkylating the same, an isomer obtained by isomerization of soft naphtha and the like. Can be used.

In order to obtain the gasoline of the present invention, an ether compound (R ₁ -OR ₂ of R ₁ -OR ₂ is a methyl group and R ₂ is a C 5 -C 5)
6, one or more selected from the group consisting of an alkyl group, a phenyl group, and a benzyl group. Specific examples of the ether compound include TAME, methyl- (3-methyl-2-butyl) ether, and methyl- (2-methyl-3
-Pentyl) ether, methyl- (3-methyl-3-pentyl) ether, anisole, methylbenzylether and the like. Among these ether compounds, TAME, in terms of the availability and the size of the effect,
Anisole is particularly preferred.

An ether compound having an alkyl group having 7 to 9 carbon atoms, an ethylphenyl group or the like as R ₂ also exhibits the same effect as the ether compound according to the present invention. However, these ether compounds are less effective than the ether compounds according to the present invention.

From the viewpoint of suppressing the generation of soot in the late injection / combustion at a low load, the larger the amount of the ether compound, the more preferable. However, there is a maximum value for the engine output under a medium or high load, and 5 to 45% by volume,
Preferably 10 to 40% by volume, more preferably 15 to 3% by volume.
5% by volume. If it is less than 5% by volume, the effect of preventing the occurrence of soot and the effect of improving the engine output are undesirably reduced. On the other hand, if it exceeds 45% by volume, the effect of preventing soot generation is improved, but the effect of improving the engine output is reduced, which is not preferable.

Methyl-t-butyl ether (MTBE)
Is an ether compound, but is not suitable as the ether compound according to the present invention. MTBE is widely known as a base material added to gasoline to improve octane number. This is because MTBE has a slight effect on suppressing the generation of black smoke, but has a low output improving effect.

The concentration of aromatic hydrocarbons contained in gasoline as a final product is 0 to 30% by volume (including 0% by volume), excluding those derived from ether compounds, and 0 to 25% by volume. % Is preferable. If it exceeds 30% by volume, not only does the amount of black smoke generated increase, but also the effect of preventing the generation of black smoke due to the addition of the ether compound tends to be weak. However, when the concentration of aromatic hydrocarbons other than the ether compound is less than 15% by volume and the calorific value of the fuel is insufficient, it may be dealt with by increasing the blending amount of anisole. When anisole is not blended, it is preferable to blend 20 to 30% by volume of aromatic hydrocarbons other than the ether compound from the viewpoint of securing the calorific value of the fuel.

As a component for increasing the calorific value, there is also a method of compounding an olefin.
It is about 10% by volume. Addition of more than this may cause problems such as a decrease in long-term storage stability and heat resistance of gasoline. Although an alicyclic hydrocarbon may be blended for the same purpose, it is preferable to blend methylcyclopentane and methylcyclopentene having a high octane value. In particular, methylcyclopentane is a preferable base material having a high octane value and no limitation on the amount of the compound. Among cycloaliphatic hydrocarbons, cyclohexane and its derivatives have a low octane number, so that when blending, it is necessary to pay attention to the octane number of the final product.

The benzene content in the gasoline of the present invention is preferably set to 1% by volume or less from the viewpoint of reducing harmful components in exhaust gas. There is no particular lower limit, and it may be considered to be 0% by volume.

[0018]

EXAMPLES The present invention will be described with reference to examples. Example 1 90% by volume of alkylate and 10% by volume of light naphtha were blended to prepare a reference fuel having the properties shown in Table 1. 80% by volume of this reference fuel and methyl-t-amyl ether (TAM)
E) 20% by volume were blended to produce gasoline of Example 1 having the properties shown in Table 2. As the TAME, a commercially available reagent was used.

Example 2 As in Example 1, 90% by volume of reference fuel and
% Gasoline, and gasoline of Example 2 having the properties shown in Table 2 was prepared.

Example 3 As in Example 1, 70% by volume of reference fuel and
% Gasoline, and gasoline of Example 3 having the properties shown in Table 2 was prepared.

Example 4 As in Example 1, the reference fuel 60% by volume and the TAME 40
% Gasoline, and gasoline of Example 4 having the properties shown in Table 2 was prepared.

Example 5 As in Example 1, 80% by volume of reference fuel and anisole 2
0% by volume to prepare gasoline of Example 5 having the properties shown in Table 2. In addition, the commercially available reagent was used for anisole.

Example 6 Example 3 having the properties shown in Table 3 in the same manner as in Example 1 except that the reference fuel was 56% by volume and 24% by volume of catalytic reforming gasoline (RFG) shown in Table 1 was blended. 6 gasoline was produced.

Example 7 A gasoline of Example 6 having the properties shown in Table 3 was prepared in the same manner as in Example 5, except that the reference fuel was 56% by volume and the RFG shown in Table 1 was blended at 24% by volume. .

Example 8 As in Example 1, 80% by volume of the reference fuel and methyl- (3
-Methyl-3-pentyl) ether in an amount of 20% by volume to prepare gasoline of Example 8 having the properties shown in Table 3. Note that a commercially available reagent was used for methyl- (3-methyl-3-pentyl) ether.

Comparative Example 1 A reference fuel having the properties shown in Table 1 was prepared by blending 90% by volume of alkylate with 10% by volume of light naphtha.

Comparative Example 2 80% by volume of a reference fuel and methyl-t-butyl ether (M
TBE) was mixed with 20% by volume to produce gasoline of Comparative Example 2 having the properties shown in Table 4. In addition, the commercially available reagent was used for MTBE.

Comparative Example 3 70% by volume of reference fuel and catalytic cracking gasoline (F
CCW) of 30% by volume to produce gasoline of Comparative Example 3 having the properties shown in Table 4.

[0029] by blending the RFG30 volume% shown in Comparative Example 4 the reference fuel 70 volume% and Table 1, to prepare a gasoline of Comparative Example 4 having properties shown in Table 4.

[0030] Comparative Example 5 the reference fuel 56 volume%, and MTBE20 volume%, by blending with RFG24 volume% shown in Table 1, to prepare a gasoline of Comparative Example 5 having properties shown in Table 4.

[0031] by blending 50 volume percent and TAME50 volume% Comparative Example 6 the reference fuel, to produce a gasoline of Comparative Example 6 having properties shown in Table 4.

[0032]

[Table 1]

[0033]

[Table 2]

[0034]

[Table 3]

[0035]

[Table 4]

Test Example 1: Measurement of Black Smoke Generation and Engine Power Based on the "ASTM-CFR" gasoline engine,
In this engine, a fuel injection device was attached to the side wall surface of the combustion chamber, and a cavity was provided in the piston head so that the fuel spray was formed at an optimum position with respect to the position of the spark plug. In addition, the fuel injection device uses a separately prepared fuel injection pump to supply fuel at a fuel pressure of approximately 5.0 MPa and drives the fuel injection device by electronic control.
A pressure pickup (AV)
L Co., Ltd., "8QPC"), and the indicated output (engine output) is measured by a combustion analyzer (Ono Sokki Co., Ltd., "CB-36").
6 "). Further, the exhaust gas was sampled from an engine exhaust pipe, and the amount of black smoke in the exhaust gas was measured using a smoke meter (“AVL415” manufactured by AVL). The air-fuel efficiency is measured using an air-fuel meter (Horiba Seisakusho, "ME
XA110λ ”). Table 5 shows the specifications of this engine.

[0037]

[Table 5]

For the gasoline of Examples 1 to 8 and the gasoline of Comparative Examples 1 to 6, the engine output and the black smoke generation concentration were
Each was compared. The engine output is the excess air ratio 2.
The measurement was performed under the conditions of 0, 2.4, 2.8, and 3.2, and the average value was obtained. In addition, the black smoke concentration was measured at a value at an excess air ratio of 2.0. The results of the system based on the standard fuel and the system added with RFG or FCCW to the standard fuel are as follows:
The results are shown in Tables 6 and 7, respectively.

[0039]

[Table 6]

[0040]

[Table 7]

As shown in Tables 6 and 7, in the gasolines of Examples 1 to 8, the output of the engine was significantly improved as compared with the gasolines of Comparative Examples 1 to 6, due to the effect of the addition of the ether compound according to the present invention. , The occurrence of black smoke, Comparative Examples 1 to
It was kept at about the same value as the 6 gasoline.

[0042]

The gasoline of the present invention, when used as a fuel for a direct-injection gasoline engine, has a remarkable effect of improving the engine output and reducing the generation of black smoke when it contains an ether compound.

Claims (1)

[Claims] 1. An ether compound (R ₁ —O—R ₂ ; R ₁
Is a methyl group, and R ₂ is at least one selected from the group consisting of an alkyl group having 5 to 6 carbon atoms, a phenyl group, and a benzyl group) in an amount of 5 to 45% by volume. Engine fuel.