JP2659648B2 - Lubricants for gas engines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant used for an internal combustion engine (gas engine), a gas turbine, and other gear driving devices using city gas such as methane, ethane, propane, butane and a mixed gas thereof as a fuel. Things.

[0002]

2. Description of the Related Art In a vehicle, a power generation engine and a cogeneration internal combustion engine equipped with a cylinder in which city gas containing methane gas as a main component is compressed and stored at a high pressure, gas fuel is mixed with air to burn well and to have high thermal efficiency. Propane gas has been widely used as a fuel for taxis. However, in an internal combustion engine using gas as fuel, especially methane gas as fuel, the combustion temperature is high and nitrogen oxide (NO
x) occurs in large quantities.

[0003]

However, in an internal combustion engine using city gas as a fuel, when the conventional multi-grade lubricating oil is used for 20 to 40 hours under full operation, the lubricating oil deteriorates, the friction coefficient increases, and the fuel consumption increases. While the rate worsens, N
If the combustion gas containing Ox leaks from the gap between the piston cylinder and the cylinder liner into the oil pan or the crankcase, the combustion products contained in the high-temperature gas and the high temperature significantly deteriorate the lubrication performance. As shown in the example, 273m
When the conventional lubricating oil was used in the L gas engine generator, the operation could not be continued for 30 hours due to deterioration.

[0004] That is, if NOx is contained in the leakage, nitric acid can be formed by mixing with water vapor or moisture existing in the oil pan or the crankcase, and the lubricating oil is oxidized and deteriorated by the influence of the high-temperature gas, and the viscosity is reduced. Increases, the lubrication performance deteriorates in a short time, the friction coefficient of the sliding surfaces of the internal combustion engine (piston liner and cylinder, cam and roller, bearings, etc.) increases, the output decreases, and the amount of gas consumed for combustion Increases. Therefore, there is a problem that the replacement time of the lubricating oil is shortened.

[0005]

A lubricant for a gas engine or the like according to the present invention is obtained by dispersing fine particles of petroleum or coal pitch-based carbon fiber into a nonionic dispersion in a lubricating oil of an internal combustion engine using city gas as a fuel. It is characterized by being added together with an agent.

The carbon fiber has a diameter of 5 to 20 millimicrons and a length of about 100 millimicrons or less,
The sintering temperature is about 1000 to 3000 ° C.

Further, the amount of the carbon fiber added is about 0.025.
０0.30% by weight, and the addition amount of the nonionic dispersant is about 1% or less.

The carbon fibers to be added include mesofused microbeads of spherical particles having a diameter of about 1 to 10 mm and having a mesofused pitch system, rayon systems, polyacrylonitrile systems, and graphite whiskers formed by vapor phase growth. , With a density of 1.6 to 2.26 g / mL.

[0009]

[Function] In the boundary lubrication state, the carbon fibers are brought into and interposed between the protrusions and depressions of the sliding surface as a carrier, so that there is no contact between metals, so that the temperature rise of the lubrication oil is relatively small, and lubrication is performed. It slows down the performance and keeps the oil slick better.

Therefore, the blow-by gas amount also decreases,
The lubricating oil will maintain its performance. As a result, the mechanical friction loss of the gas-fueled internal combustion engine is reduced, the combustion efficiency is improved, and the lubricating oil replacement period is lengthened. Further, the gas engine shown in the above example could be easily operated for 30 hours or more and 35 hours.

[0011]

Embodiments of the present invention will be described below. Commercially available lubricating oils or mineral or synthetic oil-based lubricating oils without additives, carbon fibers with a diameter of about 5-20
An approximately spherical graphite compound having a diameter of 3 mm is used in an amount of 0.05 to 0.1.
A special lubricant is produced in which 0% by weight is added together with 0.1% by weight of a nonionic dispersant.

The carbon fibers have a length of about 100 millimicrons or less and a firing temperature of about 1000 to 3000 ° C. Further, the amount of the carbon fiber added is 0.025 to 0.30.
% By weight, and the added amount of the nonionic dispersant is about 1% or less. The carbon to be added is a mesofused pitch type spherical particle having a diameter of about 1 to 10 mm, a rayon type,
A polyacrylonitrile-based or graphite whisker obtained by a vapor growth method, having a density of 1.6 to 2.26 g /
ml.

When this special lubricant is used as a lubricating oil for a gas internal combustion engine using methane, ethane, propane, butane or a mixed gas thereof as a fuel, it has a better mixing property with air than a liquid fuel. Because of this, the temperature of the combustion gas is also high. Therefore, the oil film thickness formed between the piston ring and the cylinder decreases the lubricating performance due to a decrease in viscosity due to high temperature and oxidation due to combustion products, and the boundary lubrication involves local contact of the uneven surface of the sliding surface.

For this reason, when the lubricating oil temperature increases, the amount of the blow-by gas leaks from the point where the lubricating oil no longer exists, thereby increasing the lubricating oil temperature of the oil pan or the crankcase and deteriorating the lubricating performance. Furthermore, HNO ₃ due to the combination of nitrogen oxides and moisture contained in the blow-by gas
Promotes the oxidation of the lubricating oil to increase the deterioration rate.

[0015] With the here special lubricating oil, since the carbon fibers during the concavo-convex portion of the sliding surface when the boundary lubrication state is write rare interposed has the lubricating oil as a carrier, because there is no metal-to-metal contact, lubricated The temperature rise of the oil is relatively small, and the decrease in lubricating performance is delayed, and the oil film is further maintained.

Therefore, the blow-by gas amount also decreases,
The lubricating oil will maintain its performance. As a result, the mechanical friction loss of the internal combustion engine using gas as fuel is reduced, and the combustion efficiency is improved. Conventionally, layered cleaving graphite, molybdenum disulfide and boron nitride have been used as solid lubricants, but they are fragmented and consumed by resistance and shearing force due to cleavage.

On the other hand, a polymer agent such as nylon reduces friction loss due to surface slippage,
Above, the friction loss increases due to the alteration swelling and the surface change. The carbon fiber used in the present invention is approximately 600 ° C. in air.
It does not deteriorate up to about 200 ° C. in lubricating oil without oxygen.

Further, since carbon fibers have a molecular structure similar to that of a solid lubricant such as nylon, the carbon fibers have inherent lubricating properties and are stable at high temperatures. Due to this characteristic, by using the special lubricant according to the present invention, even if the gas engine is fully operated for 20 to 40 hours, the lubrication performance is prevented from being significantly deteriorated.

The following are representative examples of test results.

This is a test result using a 273 ml single cylinder gas internal combustion engine generator using 13A (mainly methane gas) as fuel. Lubricating oil used is multi-grade oil (20W
Graphite whiskers and pitch-based carbon fibers (5 to 20 mm) and carbon fibers having a length of 100 mm or less were used for 40) and 20W40.

Table 1 shows that 12
Table 2 shows the viscosity represented by the viscosity (Pa · S) at 0 ° C., and Table 2 shows the friction coefficient obtained by comparing the lubricating oil after operation with the friction coefficient.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

When the lubricant according to the present invention described above is used in a gas engine or the like, the rate of increase in the friction coefficient is low and the fuel consumption rate is improved even when the deterioration is delayed and the engine is operated for a long time.
Therefore, the lubricating oil replacement period is prolonged, and the economy is increased.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C10N 70:00

Claims (4)

(57) [Claims] A lubricating oil for an internal combustion engine using city gas as a fuel, wherein fine particles of petroleum or coal pitch-based carbon fibers are added together with a nonionic dispersant to a lubricating oil for an internal combustion engine using a city gas as a fuel. Agent. 2. The gas according to claim 1, wherein the carbon fibers have a diameter of 5 to 20 millimicrons, a length of about 100 millimicrons or less, and a firing temperature of about 1000 to 3000 ° C. Lubricant for engines, etc. 3. The amount of carbon fiber added is 0.025 to 0.3.
2. The lubricant for a gas engine or the like according to claim 1, wherein the lubricant is 0% by weight, and the amount of the nonionic dispersant added is about 1% or less. 4. Carbon fibers to be added include spherical particles having a diameter of about 1 to 10 millimicrons in a meso-fuse pitch system, rayon systems, polyacrylonitrile systems, and graphite whiskers produced by a vapor growth method. .6 ~
The lubricant for a gas engine or the like according to claim 1, 2, or 3, wherein the lubricant contains 2.26 g / mL.