JPH0129520B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel for eliminating the generation of large amounts of black smoke in exhaust gas when starting a diesel engine, under high load, during rapid acceleration, etc. The purpose is to almost eliminate the generation of smoke, increase combustion efficiency and engine output, and simplify the structure of the implementation device so that it can be implemented safely and easily at low cost.

Large vehicles (buses, trucks, work vehicles, etc.)
The model is equipped with a diesel engine in order to achieve high engine output and fuel economy, and uses light oil exclusively as its fuel. In addition, although diesel cars for general passenger cars are currently being produced, it is thought that the soaring price of crude oil and the shortage of crude oil will further promote the use of diesel cars in the future. In fact, automobile manufacturers are competing to rapidly promote the development of diesel vehicles.

One of the problems with diesel cars that use light oil as fuel is the generation of black smoke in the exhaust gas. Diesel engine combustion is carried out under excess air, high temperature, and high pressure, so the thermal efficiency is high, and the exhaust gas is relatively clean as it contains almost no CO or HC. The amount of black smoke generated is large when the fuel load is high, such as when driving or accelerating rapidly.Despite the regulations being implemented, black smoke pollution from the exhaust gas of diesel vehicles is currently the biggest problem in automobile exhaust gas pollution. be.

In order to solve the above-mentioned black smoke generation from exhaust gas of diesel cars, the amount of black smoke emissions can be reduced by mixing liquefied petroleum gas (hereinafter referred to as LPG) into the intake air as an auxiliary fuel (hereinafter referred to as auxiliary fuel intake method). That is, it is a known technique.

In the case of the above-mentioned auxiliary fuel intake system, 100% LPG is supplied independently from the auxiliary fuel system.
An extra LPG supply system will be required.

For this reason, an independent LPG with a pressure resistance of 10 kg/cm ² or more
Because it is necessary to equip a pressure tank, LPG vaporizer, control device, etc., the fuel supply system and operation of the engine become complicated, reducing safety and reliability, and at the same time, the cost of implementation becomes high. Moreover, if you try to apply it to existing diesel engines, not only will it require significant modification, but it will also involve considerable difficulties in the structure and layout of the engine's fuel supply system, making it extremely difficult to apply it to existing diesel vehicles. There are various drawbacks.

The present invention is intended to solve the above-mentioned drawbacks, and while using the fuel supply system of the existing diesel engine with almost no modifications, it uses LPG-dissolved light oil fuel to achieve the same or higher performance than the above-mentioned auxiliary fuel intake system. It can be effective.

Next, regarding the examples and experimental results of the present invention,
explain in detail.

LPG-dissolved diesel fuel is produced by adding LPG to diesel oil in an airtight pressure vessel and dissolving the LPG in the diesel oil under its vapor pressure.

It is well known that LPG dissolves in diesel fuel, but when putting LPG-dissolved diesel fuel into practical use,
As a result of experiments conducted on LPG dissolution characteristics and the stability of its fuel, it was found that LPG-dissolved diesel fuel is a homogeneous and stable liquid fuel, and good results were obtained regarding its viscosity, volatility, cetane number, etc. It was confirmed that it is an excellent fuel for engines. Figure 1 shows the amount of LPG-dissolved light oil fuel.
Experimental data on the relationship between LPG melt weight ratio and LPG vapor pressure are shown. The temperature during the experiment was the outer wall temperature of the container, which was 19~
It was 20℃. For the above temperature conditions, for example, 10%
The vapor pressure of LPG melted fuel is 2.3Kg/cm ² G. As can be seen from the above experimental data, LPG-dissolved gas oil fuel can be stored in a low-pressure pressure vessel, which is advantageous in terms of practical application.

FIG. 2 shows an example of a schematic configuration of a fuel supply system for a diesel engine, in which a fuel tank 2 is connected to a combustion chamber 1 of a diesel engine via a fuel supply path 9, a fuel filter 3, a fuel injection pump 4, and a fuel injector 5. The fuel tank 2 is configured as a sealed pressure tank and can contain fuel made by dissolving LPG in light oil, and the inlet pipe 7 of the sealed pressure fuel tank 2 is
Attach the refueling valve 6 to the refueling valve 6.
An airtight joint 8 for refueling is provided on the inlet side of the tank, and the airtight joint at the tip of the refueling pipe of the refueling tank (not shown) is connected to the airtight joint 8 for refueling of the closed pressure fuel tank 2, and With the refueling valve 6 open, the fuel in the refueling tank is configured to be injectable from the refueling tank into the closed pressure fuel tank 2 through the airtight joint 8 for refueling and the valve 6. While keeping the LPG-dissolved light oil fuel stored in the tank 2 in a liquid state, it is led out from the pressure fuel tank 2 to the fuel supply path 9, and is directly filtered by the fuel filter 3 without the need for pressure increase by the currently used fuel feed pump, and the fuel is The injection pump 4 is configured so that the fuel can be injected into the combustion chamber 1 in liquid form from the fuel injector 5.

The lubricating fuel portion of the fuel injector 5 is formed so as to return to the pressure fuel tank 2 through a flow path 10.

A take-out valve 12 is provided at the connection between the pressure fuel tank 2 and the supply path 9. The pressure fuel tank 2 is provided with a liquid level gauge 14, a pressure gauge 15, a safety valve 16, and a drain pot 13.

In addition, as a modification of the above fuel supply device, a diesel fuel tank and a 100% LPG fuel tank are provided, diesel oil and LPG are dissolved in a predetermined ratio, and the LPG-dissolved diesel fuel is led out to the fuel supply path, and the fuel filtration is carried out. vessel·
The fuel can be configured to be supplied to the combustion chamber via a fuel injection pump/fuel injector.

Next, the combustion characteristics of the LPG-dissolved gas oil fuel in the combustion chamber will be explained in detail.

When LPG-dissolved diesel fuel is injected into the combustion chamber from a fuel injector, this LPG-dissolved diesel fuel has a lower viscosity than diesel oil, so it has better dispersibility.
LPG has a low boiling point (-44 to -40℃) and is a light oil (boiling point 240℃).
Because it has extremely high volatility compared to temperatures (up to 350℃), it instantly turns into a flammable gas and quickly diffuses.
Its diffusion promotes the dispersion and atomization of light oil. On the other hand, the temperature in the combustion chamber is sufficiently higher than the ignition temperature of LPG (under high pressure conditions in the combustion chamber), and
The flammable concentration of LPG is extremely low at 2.3% even in air under atmospheric pressure, so LPG gas ignites instantly immediately after injection, and the heat generated by LPG combustion rapidly gasifies the atomized light oil droplets. to promote. Moreover, at the moment when LPG, which is uniformly dissolved in light oil, turns into combustible gas, the intermolecular attraction between LPG and light oil disturbs the balance of surface tension of the light oil particles, causing them to break up and become even finer particles. Since the surface area of the oil particles increases, the conversion of light oil particles to combustible gas is further promoted. For this reason, the light oil combustible gas rapidly mixes with the combustion air and ignites early.

Rapid diffusion due to the promotion of combustible gasification improves the combustion rate and improves the actual engine output. Furthermore, since the light oil ignites early, that is, the ignition delay is shortened, the amount of fuel injected before ignition is reduced, so that an abnormal pressure rise (diesel knock) in the combustion chamber at the time of ignition can be prevented.

As mentioned above, since the ignition delay is shortened and the combustibility of the fuel in the combustion chamber is significantly improved, the combustion period of the subsequent injected fuel is also sufficient, and it becomes a combustible gas, mixes well with the combustion air, and combusts. Therefore, the generation of black smoke is reduced, the combustion rate is improved, and the actual engine output is improved. Therefore, the fuel consumption rate is also reduced.

Next, we will explain the results of an experiment conducted by burning LPG-dissolved light oil fuel in an automobile diesel engine.

1 Overview of experimental method: (1) Diesel engine: 60PS, inline 4-cylinder 4
Cycle, total displacement 2530 c.c., compression ratio = 21, diesel engine for trucks, (2) Fuel: Light oil (JIS No. 1 light oil), LPG (JIS No. 1 liquefied propane), LPG-dissolved light oil fuel (weight ratio 7)
% and 20% LPG dissolved), 2 Experimental data Exhaust gas black smoke level, shaft torque, shaft output, and fuel consumption obtained by conducting experiments [] and [] with full-throttle fuel injection amount. The experimental data are shown in Figs. 3 to 6 and Figs. 7 and 8, respectively. In experiment [], the fuel supply governor was set to the engine standard setting, and in experiment [], it was set to high-volume injection.

3 Experimental Results As shown in Figures 3 to 6, the results of the experiment [] show that 7% LPG-dissolved diesel fuel is a superior fuel for diesel engines compared to diesel fuel. In other words, the degree of black smoke is reduced by 20 to 35% over the entire rotation speed range, that is, the entire range of various loads (Figure 3),
The fuel consumption rate is reduced by 4-6% (Figure 6). As shown in Figures 4 and 5, the shaft torque and shaft output were approximately the same values as when using light oil, and in areas with large external loads, results were obtained that exceeded these values. The reason for the significant decrease in black smoke level is to verify what was described in the section on combustion characteristics in the combustion chamber. With LPG-dissolved diesel fuel, as mentioned above, the combustion approaches complete combustion, and the amount of black smoke generated is significantly reduced.In other words, the fuel that was wasted in the form of black smoke with diesel fuel is combusted, contributing to engine output. This proves that the actual engine output increases by this amount, which in turn improves and reduces the fuel consumption rate.

The calorific value of LPG is slightly higher per unit weight than that of diesel oil, but the calorific value increases by only 0.4% per unit weight with 7% LPG-dissolved diesel fuel.

In addition, the fuel injection amount in the experiment [] is a standard injection amount that corresponds to that of an actual automobile diesel engine, so it matches an actual diesel car. However, by using LPG-dissolved diesel fuel, which generates less black smoke, the fuel injection amount can be reduced by limiting the amount of fuel injected to 50% or less, which limits the engine output. Since the engine power can be increased, it is also possible to improve engine output or reduce the size of the engine.

The results of experiment [], as shown in FIGS. 7 and 8, show a good tendency that is substantially the same as the results of experiment []. This experiment [] was conducted by removing the fuel supply limit adjustment mechanism of the engine governor and injecting a large amount of fuel.

The LPG-dissolved gas oil fuel according to the present invention has the above-described structure and operates as described above, so that it has the following effects.

B By implementing the present invention, the actual engine output can be improved.

In other words, LPG has a low boiling point (-44 to -40℃), so it is extremely volatile compared to diesel oil (boiling point 240 to 350℃), and it instantly turns into a flammable gas immediately after being injected into the engine combustion chamber. At the same time as it is diffused, the light oil is also dispersed, LPG quickly ignites, and the heat generated by this LPG combustion rapidly accelerates the conversion of the dispersed light oil droplets into combustible gas.
Moreover, LPG, which is uniformly dissolved in light oil,
At the moment when the light oil particles turn into combustible gas and evaporate, the light oil particles are split by the action of intermolecular attraction between LPG and light oil, promoting further miniaturization of the light oil particles, thereby converting the light oil into combustible gas. is promoted.

In this way, by promoting and speeding up the conversion of light oil particles into combustible gas, (i) uniform mixing of light oil combustible gas and combustion air, and (ii) early ignition of light oil combustible gas is realized. . As a result of (i), the combustion efficiency improves due to the improvement in the air utilization rate, and the real engine output increases. Therefore, the fuel consumption rate is reduced.

As a result of (ii), the time until the first injected fuel ignites, that is, the ignition delay time, is shortened, resulting in an abnormal pressure rise in the combustion chamber at the time of ignition (diesel lock).
is prevented, engine vibration and noise are improved, and at the same time, the actual engine output is also improved.

Furthermore, as a result of (ii), the combustion time of the fuel in the combustion chamber can be extended by promoting the subsequent combustible gasification and early ignition of the injected fuel, which promotes the mixing of combustible gas and combustion air, resulting in incomplete combustion. Combustion is eliminated and engine output increases, while at the same time
The amount of black smoke produced is also significantly improved, resulting in higher engine output and lower fuel consumption.

Furthermore, compared to the case where LPG is gasified alone and mixed into intake air, the amount of combustion air that can be taken in can be increased, which is more advantageous in terms of engine output.

Moreover, although the price per unit weight of LPG is higher than that of diesel oil, as the fuel consumption rate is reduced as mentioned above, the fuel cost becomes significantly cheaper.

(b) The safety of the LPG-dissolved diesel fuel supply system will be improved. That is, in the conventional auxiliary fuel intake system,
While a pressure tank of approximately 10 kg/cm ² G or more is essential for storing 100% LPG fuel, the present invention
When using LPG-dissolved diesel fuel, a pressure tank with a pressure of approximately 2 to 4 kg/cm ² G is sufficient depending on the LPG dissolution ratio and temperature conditions, making it extremely safe and suitable for automobile diesel engines. This is particularly advantageous when In this case, the air supply and fuel supply systems of the existing light oil diesel engine can be used as they are except for the fuel tank. That is, it can be applied to existing diesel engines by simply modifying the fuel tank to a low-pressure tank for LPG-dissolved light oil fuel, so it can be implemented extremely easily and at low cost.

[Brief explanation of drawings]

Figure 1 shows the LPG-dissolved light oil fuel according to the present invention.
A diagram of experimental data showing the relationship between the LPG melt weight ratio and LPG vapor pressure, Figure 2 is a schematic diagram of the fuel supply system of a diesel engine, and Figures 3 to 6 are related to the experiment [], and each shows the black smoke degree.・It is a diagram of experimental values of shaft torque, shaft output, and fuel consumption rate, and is shown in Figure 7.
FIG. 8 is a diagram of experimental values of black smoke degree and fuel consumption rate, respectively, regarding experiment [].

Claims (1)

[Claims] 1. A diesel that is characterized by adding liquefied petroleum gas to light oil in a sealed pressure vessel, dissolving the liquefied petroleum gas in light oil under the vapor pressure, and using the light oil in which the liquefied petroleum gas is dissolved as fuel for a diesel engine. Liquefied petroleum gas dissolved light oil fuel for engines.