JPH09280123A - Fuel supply method and device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the combustion state of an internal combustion engine without using a high pressure fuel injection pump. SOLUTION: Fuel in a fuel tank 11 is pressurized to a supercritical pressure by a supercritical-pressure pump 17 and is supplied to a supercritical state forming device 18 having a heater 18a and the fuel in the supercritical state forming a device 18 is injected into the combustion room of an engine 1 from a fuel injection valve 2 by a supercritical-pressure fuel injection pump 19. When the fuel in a supercritical state in injector from the fuel injection valve 2, extremely fine fuel particles are formed uniformly in a combustion room, which greatly improves the combustion state of the engine 1.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a fuel supply method and apparatus for an internal combustion engine.

[0002]

2. Description of the Related Art In a fuel injection system for an internal combustion engine, it is required to supply fuel to the engine combustion chamber as fine particles as possible in order to improve the engine combustion state. In particular, in an engine that directly injects fuel into the combustion chamber, such as a diesel engine, the particle size of the injected fuel has a large effect on the engine performance, and the effect of improving combustion by atomizing the injected fuel is great. Hitherto, in order to atomize the fuel at the time of fuel injection, high-pressure fuel injection in which the fuel injection pressure is increased and fuel is injected from the fuel injection valve in a high pressure state has been effective. For this reason, the fuel injection pressure of the fuel injection device is becoming higher in response to the exhaust gas regulation and the demand for reducing the fuel consumption of the engine. For example, in the fuel injection device of a diesel engine or the like, in order to atomize the fuel, Injection pressure 50 MPa
There is also one that is set to a high pressure of about (500 atm).

[0003]

However, in order to achieve finer injection fuel by increasing the fuel injection pressure in this way, it is necessary to use a fuel injection pump capable of supplying high-pressure fuel. is there. However, since the high-pressure fuel injection pump is expensive, there is a problem that the cost of the fuel injection device itself is significantly increased if the fuel injection pressure is increased to make the injected fuel finer. Further, in the high-pressure fuel injection pump, since it is necessary to set the clearance of the liquid contact portion to be small in order to increase the discharge pressure, there is a problem that the sliding portion is apt to wear and the reliability for long-term use is not sufficient.

In view of the above problems, it is an object of the present invention to provide a fuel supply method and apparatus capable of improving combustion without increasing the fuel injection pressure.

[0005]

According to the invention as set forth in claim 1, there is provided a fuel supply method for an internal combustion engine in which a liquid fuel is brought into a supercritical state and the fuel in the supercritical state is supplied into a combustion chamber of the internal combustion engine. Provided. According to the invention described in claim 2, there is provided a fuel supply method for an internal combustion engine for a vehicle, wherein liquid fuel is supercritical in a vehicle for reforming, and the reformed fuel is used as a combustion chamber of the internal combustion engine. A fuel supply method for an internal combustion engine for a vehicle is provided.

According to the invention described in claim 3, further
The fuel supply method according to claim 2, wherein the fuel after reforming is supplied to the combustion chamber of the internal combustion engine in a supercritical state. According to the invention of claim 4, the internal combustion engine is a diesel engine, and the liquid fuel is light oil.
A fuel supply method according to any one of claims 1 to 3 is provided.

According to a fifth aspect of the invention, there is provided the fuel supply method according to the fourth aspect, wherein an oxygen-containing substance is added to the liquid fuel in advance. According to the invention of claim 6, a fuel tank for storing liquid fuel, a fuel injection valve for injecting fuel supplied from the fuel tank into a combustion chamber of an internal combustion engine, the fuel tank, and the fuel injection valve. A fuel supply device for an internal combustion engine is provided, which is provided in a fuel supply path between the two, and includes a supercritical state generating unit that brings the liquid fuel into a supercritical state.

According to a seventh aspect of the present invention, the supercritical state generating means includes pressurizing means for pressurizing the liquid fuel to a predetermined pressure and heating for heating the liquid fuel to a predetermined temperature. A fuel supply system according to claim 6 is provided. According to the invention as set forth in claim 8, there is provided a method for supplying light oil to an internal combustion engine, the light oil having a temperature of 400
Provided is a fuel supply method of reforming while maintaining the pressure at 1.5 ° C. or higher and at 1.5 MPa or higher, and then supplying the reformed light oil to the internal combustion engine.

According to a ninth aspect of the present invention, there is provided a method for supplying light oil to an internal combustion engine, the light oil being reformed while maintaining a pressure of 1.5 MPa or more between a temperature of 400 ° C. and 550 ° C. Then, a fuel supply method for supplying the reformed light oil to an internal combustion engine is provided. According to the invention described in claim 10,
A method of supplying light oil to an internal combustion engine, wherein the light oil is heated to a temperature of 4
Reforming is carried out at a temperature of 00 ° C. or higher and at a pressure of 1.5 MPa or higher, then the reformed gas oil is mixed with unmodified gas oil, and a mixture of the modified gas oil and unmodified gas oil is supplied to the engine. A method of supplying fuel is provided.

According to an eleventh aspect of the present invention, there is provided a method for supplying light oil to an internal combustion engine, the light oil having a temperature of 400 ° C.
To 550 ° C., the pressure is maintained at 1.5 MPa or more for reforming, and then the reformed gas oil is mixed with unmodified gas oil,
A fuel supply method for supplying a mixture of the reformed gas oil and the unreformed gas oil to an engine is provided. Hereinafter, the operation of the invention of each claim will be described.

In the first aspect of the invention, the liquid fuel is brought into a supercritical state and then supplied into the combustion chamber. As will be described later, by raising the temperature and raising the pressure to the supercritical state, the liquid fuel becomes a gas having an extremely high density and becomes a fluid phase having a property close to that of a liquid. Since the fluid phase in the supercritical state has a property close to that of gas, it diffuses when injected from the fuel injection valve,
Liquefaction produces extremely fine fuel particles. On the other hand, as will be described later, the critical pressure of liquid fuel is relatively low, for example, about several MPa (tens of atmospheric pressure) for light oil. For this reason,
In the fuel injection method of the first aspect, the injected fuel is atomized without performing high-pressure fuel injection. Liquid fuel such as light oil is a mixture of various hydrocarbon components, and each component has different critical temperature and pressure. Therefore, depending on the temperature and pressure conditions, there are cases where not all the components of the liquid fuel are in the supercritical state but only some of them are in the supercritical state. The effect of fuel refinement at the time of fuel injection and the fuel reforming described later is that all components of the liquid fuel are not in a supercritical state, that is, even if only some components are in a supercritical state. You can get enough. For this reason,
In the present specification, unless otherwise specified, the term "supercritical state" is used including the case where only a part of the components of liquid fuel such as light oil is in the supercritical state as described above.

According to the second aspect of the invention, the fuel is reformed by bringing the liquid fuel into a supercritical state on the vehicle. For example, liquid fuels such as light oil contain a large amount of heavy components such as straight chain saturated hydrocarbons having a large molecular weight and aromatic components, but these heavy components are difficult to burn in the combustion chamber and become particulate (exhaust particulates). Is exhausted together with the exhaust gas. However, these heavy components are decomposed at a relatively low temperature (for example, about 400 ° C.) in a supercritical state to generate light components such as linear saturated hydrocarbons having a small molecular weight. In the invention of claim 2, the supplied liquid fuel is maintained in a supercritical state on the vehicle and reformed into a fuel containing a large amount of light components. Therefore, the combustion state of the engine is improved by supplying the reformed fuel to the combustion chamber.

In the third aspect of the invention, the fuel containing a large amount of light components reformed by the method of the second aspect is further brought into a supercritical state and supplied to the combustion chamber of the internal combustion engine. Therefore, in the third aspect of the present invention, the combustion state of the engine is improved by the effects of both the increase of the light component by the reforming and the atomization of the injected fuel by the fuel injection in the supercritical state. In the invention of claim 4, the inventions of claims 1 to 3 are applied to a diesel engine using light oil as a fuel. This improves the combustion state of the diesel engine.

According to the invention of claim 5, in the invention of claim 4, the oxygen-containing substance is added to the liquid fuel in advance. here,
The oxygen-containing substance means a substance containing oxygen or a hydroxyl group (OH) ^- , such as water and methanol. Combustion of a fuel containing an oxygen-containing substance in a liquid fuel suppresses the formation of aromatic components during combustion, improving the combustion state and decomposing linear heavy components during fuel reforming in supercritical state. It is possible to obtain the effect that the generation of the aromatic component at the time of is suppressed and the generation of the particulates at the time of combustion of the fuel after reforming is reduced.

In the invention of claim 6, the fuel stored in the fuel tank is brought into a supercritical state by the supercritical state generating means before being injected from the fuel injection valve. Thereby, either one or both of the supply of the fuel into the combustion chamber in the supercritical state and the reforming of the fuel in the supercritical state are performed. In the invention of claim 7, the supercritical generation means of claim 6 comprises a pressurizing means and a heating means, and the liquid fuel is pressurized and heated so as to have a pressure not lower than the critical pressure and a temperature not lower than the critical temperature. And reach a supercritical state.

It has been found that when the light oil is reformed in a supercritical state, the heavy component is decomposed to produce a light component under the conditions of a pressure of 1.5 MPa or more and a temperature of 400 ° C. or more. In the invention of claim 8, the temperature of the light oil is 400 ° C. or higher,
By maintaining the pressure at 1.5 MPa or higher and reforming the fuel before supplying it to the internal combustion engine, it is possible to supply fuel containing a large amount of light components to the engine and improve the engine combustion state.

On the other hand, when light oil is reformed in a supercritical state,
When the reforming temperature is set to be high, an aromatic component may be produced when the heavy straight chain saturated hydrocarbon is decomposed. According to the experiment, the aromatic component at the time of light oil reforming has a temperature of 55.
It has been found that this often occurs when light oil is reformed under conditions of 0 ° C or higher. Therefore, in the invention of claim 9, the pressure of the light oil is 1.5 MPa at a temperature of 400 ° C. to 550 ° C.
By carrying out reforming while holding the above, the heavy linear saturated hydrocarbon component is decomposed while suppressing the production of aromatic components during reforming.

Further, the gas oil reformed in the supercritical state as described above has a substantially similar cetane number as compared to the unreformed gas oil, but the kinematic viscosity is greatly reduced and the volatility is greatly increased. It turns out. Therefore, by adding the modified gas oil to the unmodified gas oil as a combustion aid, the initial combustion of the gas oil in the combustion chamber can be promoted and the combustion state of the engine can be improved. Further, when the modified gas oil is mixed with the unmodified gas oil as a combustion aid, for example, if the modified gas oil is added in a range of about 1% to 30% by weight ratio after mixing, the effect of improving combustion can be obtained. It is known to be obtained. Therefore, in the inventions of claims 10 and 11, the effect of improving the combustion state of the internal combustion engine is provided by supplying to the internal combustion engine a mixture of light oil reformed in the supercritical state with unreformed diesel oil. It has gained.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. Before the description of specific embodiments, a supercritical state of liquid fuel will be described.
The supercritical state is a state obtained by raising the temperature of a substance to a temperature equal to or higher than the critical temperature under a pressure equal to or higher than the critical pressure. When the temperature of the liquid is raised to the supercritical state, the liquid undergoes a phase change into a gas. However, the gas in the supercritical state has an extremely high density and exhibits physical properties similar to those of the liquid.
That is, the liquid becomes a fluid in the supercritical state, which has physical properties intermediate between those of the gas and the liquid, in the supercritical state. Since the fluid in the supercritical state is a gas of extremely high density, it has a large energy density and exhibits various unique properties.

For example, when liquid fuel is supercritically injected into a combustion chamber of a lower pressure and temperature atmosphere from a nozzle, much finer fuel particles are uniformly distributed in the combustion chamber than when normal liquid fuel is injected at high pressure. Is formed. Liquid fuel in the supercritical state becomes a subcritical state in which the temperature or pressure is lower than the critical value in the process of being injected from the nozzle, and part of it becomes ordinary gas that diffuses into the combustion chamber and part of it from the gas phase. The liquid phase is changed to form fine fuel droplets in the combustion chamber. In this case, the particle size of the droplets formed by the phase change (condensation) from the gas phase to the liquid phase becomes extremely small, compared with the case where ordinary liquid fuel is injected at high pressure and atomized by mechanical impact. Moreover, since the liquid fuel in the supercritical state, which has the property as a gas, instantly diffuses into the combustion chamber, the formation of droplets due to the change from the gas phase to the liquid phase occurs in the entire combustion chamber. Therefore, by injecting the liquid fuel in the supercritical state into the combustion chamber, it is possible to uniformly form extremely fine fuel particles in the entire combustion chamber.

Further, as will be described later, for example, for light oil, the critical pressure is relatively low at about several MPa (tens of atmospheric pressure). Therefore, by injecting the liquid fuel in a supercritical state, the pressure is one tenth or less than that when high pressure injection is performed by increasing the fuel injection pressure to about 50 MPa (500 atm). Much finer fuel particles can be uniformly generated in the entire combustion chamber.

Further, the fuel fine particles produced by the injection in the supercritical state have a large energy due to the latent heat released by the change from the gas phase to the liquid phase, and are in a highly reactive state. Further, as described above, the fuel injected from the supercritical state becomes extremely fine particles and is uniformly mixed with the air in the combustion chamber. Therefore, the fuel fine particles generated in the combustion chamber by the injection in the supercritical state have a high energy and a sufficient amount of oxygen is supplied, so that the ignition and combustion state becomes extremely good. Since the combustion state of the fuel injected in this way becomes good and it burns completely,
The amount of unburned fuel discharged together with the exhaust gas is reduced, and the same output can be obtained with a smaller amount of fuel than in the past.

FIG. 4 is a diagram for explaining pressure-temperature conditions required for producing a supercritical state in the case of using light oil as an example. Generally, light oil has a linear saturated hydrocarbon (n-paraffin) component having about 11 to 20 carbon atoms and 10 to 20 carbon atoms.
It is a mixture with some aromatic (alkylbenzene) components. Generally, the critical pressure and the critical temperature are different for each substance, and each component in light oil also has a different critical pressure and temperature.

FIG. 4 is a diagram showing changes in the critical pressure and the critical temperature depending on the number of carbon atoms in n-paraffin and alkylbenzene. The vertical axis of FIG. 4 represents the critical pressure of each component,
The horizontal axis indicates the critical temperature. As shown in FIG. 4, in general, the critical temperature tends to increase as the number of carbon components increases, and the critical pressure tends to decrease as the number of carbon components increases. In general, the critical pressure and critical temperature of the n-paraffin component tend to be lower than the critical pressure and critical temperature of the alkylbenzene component having the same carbon number, respectively.

Regions A and B shown by hatching in FIG. 4 represent ranges of carbon numbers of the n-paraffin component and the alkylbenzene component contained in the light oil, respectively. As can be seen from FIG. 4, in order for all components of light oil to be completely in a supercritical state, the temperature and pressure conditions are in the region shown by SC1 in FIG. 4 (pressure is 3 to 6 MPa or more, temperature is 400 to 500 ° C.). Above). However, in reality, in order to obtain the above-mentioned effect of atomizing the injected fuel, not all the components of light oil are necessarily in the supercritical state, only some components are in the supercritical state. However, it is known that the effect of atomizing the injected fuel can be sufficiently obtained. Therefore, in reality, even under a temperature / pressure condition (for example, a pressure of 1 MPa or higher, or a temperature of 300 ° C. or higher) such that only a part of the n-paraffin component or the alkylbenzene component in the light oil becomes a supercritical state, the injection fuel is miniaturized The effect of can be obtained. As can be seen from FIG. 4, as the carbon number of the component increases, the critical temperature increases, and conversely, the critical pressure decreases as the carbon number of the component increases, so that only a part of the component is put into a supercritical state. In this case, generally, the higher the temperature, the lower the pressure can be.

As described above, by injecting light oil into the combustion chamber in a supercritical state, a pressure of about 1 (a part of the light oil component) is sufficient as compared with the conventional high pressure fuel injection (for example, about 50 MPa). In the case where only the fuel is injected into the supercritical state, the injected fuel is made finer (at a lower pressure), and the combustion state can be further improved as compared with the case of the high pressure fuel injection. Therefore, by injecting the liquid fuel in the supercritical state, the discharge pressure of the fuel injection pump can be set significantly lower than in the case of high pressure injection, reducing the cost of the fuel injection pump and improving the durability of the fuel system equipment. It is possible to improve.

It has been described above that the fuel particles can be atomized to improve the combustion state by injecting the liquid fuel in the supercritical state. However, by holding the liquid fuel in the supercritical state for a certain period of time, It is known that the effect of reforming the fuel can be obtained by converting the heavy component of the fuel into the light component. FIG. 5 is a diagram illustrating a fuel reforming effect in a supercritical state. The horizontal axis of FIG. 5 shows the concentration change of the n-paraffin component at each carbon number in the light oil when the light oil is kept in the supercritical state for a certain period of time. The example of FIG. 5 shows the concentration change of each component when the light oil is kept at a temperature of 400 to 500 ° C. for 4 to 5 MPa (40 to 50 atm) for about 20 minutes, and the vertical axis of FIG. The increase and decrease, the horizontal axis represents the carbon number of the component. In the example of FIG. 5, the concentration of heavy n-paraffin components (components having 13 or more carbon atoms) decreases as a result of holding the light oil in a supercritical state for a certain time, and instead, the light n-paraffin component components (carbon numbers) are replaced. It can be seen that the concentration of (12 or less components) increases. Also, this n
-It has been found that the effect of modifying the paraffin component is more remarkable as the temperature and pressure for holding in the supercritical state are higher and the holding time is longer.

Experiments have shown that it is preferable to maintain the pressure at 1.5 MPa or more in order to obtain the effect of modifying the heavy n-paraffin component. Figure 7
Shows the results of treating light oil under a pressure of 5 MPa while changing the temperature and the holding time. In the table shown in FIG. 7, the letter C
Indicates the processing conditions in which the heavy n-paraffin component amount of the light oil did not change by the treatment, the letter B indicates the treatment conditions in which the heavy n-paraffin component amount slightly decreased, and the letter A indicates the heavy n-paraffin component amount. The processing conditions are shown with reduced amount. As can be seen from FIG. 7, when the gas oil is reformed under a pressure of 5 MPa, the reforming effect is obtained when the temperature is 400 ° C. or higher (that is, the heavy n-paraffin component in the gas oil is reduced).

Further, as shown in FIG. 7, if the pressure is constant, the processing time required for reforming becomes shorter as the processing temperature becomes higher. For example, in FIG. 7, when the temperature is 400 ° C., a processing time of 120 minutes or more is required to reduce heavy components, but when the temperature is 475 ° C. or more, the processing time is 1 minute or less. Heavy components can be reduced.

On the other hand, on the other hand, when the treatment temperature and pressure are increased during the supercritical reforming treatment of light oil, the heavy n
-It has been confirmed that the alkylbenzene component is generated by the paraffin component and the amount of the alkylbenzene component is increased. FIG. 6 shows the same light oil as in FIG.
It is a figure which shows the density | concentration change of the alkylbenzene component of each carbon number in light oil when it hold | maintains at 5 MPa for about 20 minutes. As shown in FIG. 6, it can be seen that when the temperature and pressure are high, the alkylbenzene component is increased, and the heavy n-paraffin component is converted into the alkylbenzene component.

Generally, when the heavy n-paraffin component or alkylbenzene component in light oil increases, the amount of particulates in the exhaust increases. In particular, heavy alkylbenzene (for example, alkylbenzene having two or more benzene rings) increases the amount of particulates in the exhaust gas. Therefore, it is not preferable that the alkylbenzene component in the light oil increases due to the supercritical reforming treatment.

FIG. 8 shows the results of supercritical processing of light oil at a pressure of 5 MPa while changing the temperature and pressure.
In the table of FIG. 8, the letter C indicates the treatment condition in which the alkylbenzene component in the light oil increased due to the treatment, the letter B indicates the treatment condition in which the alkylbenzene content in the light oil slightly increased, and the letter A indicates that the alkylbenzene content in the light oil increased. The processing conditions not performed are shown respectively.

As shown in FIG. 8, when the pressure during supercritical processing is maintained at 5 MPa and the processing temperature is 550 ° C. or higher, the alkylbenzene component increases even when the processing time is 1 minute. However, as the treatment temperature becomes lower, the alkylbenzene component does not increase even if the treatment time is increased. Considering the results of FIGS. 7 and 8, during the supercritical treatment, for example, the pressure is 1.5 MPa or more and the temperature is 400 MPa.
It can be seen that when the temperature is set to 550 ° C. or higher and the temperature is 550 ° C. or lower, there are processing time conditions capable of reducing the heavy n-paraffin component, that is, reforming the light oil and suppressing the increase of the alkylbenzene component.

Further, in addition to keeping the temperature and pressure conditions during the supercritical treatment at the conditions where the alkylbenzene component does not easily increase as described above, in order to suppress the increase of the alkylbenzene component, water or methanol is previously added to the light oil. It is effective to add oxygen-containing substances such as (substances containing oxygen and hydroxyl components). By performing supercritical reforming treatment by adding water or methanol in a ratio of several percent to ten and several percent to light oil, it is possible to suppress the conversion of the decomposed heavy n-paraffin component into an alkylbenzene component. . It is known that the n-paraffin component in light oil also produces a small amount of an alkylbenzene component during combustion. However, by adding the above oxygen-containing component to light oil in advance, the alkylbenzene component is produced during combustion. Can be suppressed and the amount of particulates in the exhaust can be effectively reduced.

Next, changes in other physical properties of light oil when the above-mentioned supercritical reforming is carried out will be explained. FIG. 9 shows the physical properties of unreformed light oil (JIS JTD-5) and the properties of the reformed oil obtained by subjecting this light oil to a supercritical reforming treatment at a pressure of 5 MPa and a temperature of 400 to 550 ° C. As you can see from Figure 9,
The kinematic viscosity and the flash point are greatly reduced although the cetane number of the diesel fuel has hardly changed due to the reforming treatment. This means that when the light oil after reforming is injected into the engine combustion chamber, since the injected light oil has a low kinematic viscosity, it forms finer droplets than the unreformed light oil, and the flash point decreases. This means that ignition will be easier.

Further, as shown in FIG. 9, the reformed oil maintains a cetane number equivalent to that of the unreformed oil, but has a much lower initial boiling point and flash point than the unreformed oil. . This means
It means that the reformed oil has a cetane number equivalent to that of the unreformed oil, but is more highly volatile than the unreformed oil. Therefore, by adding the light oil reformed by the supercritical reforming treatment to the normal (unreformed) light oil, it is possible to promote the initial combustion of the light oil in the combustion chamber. That is, the gas oil after reforming can be used as a combustion aid added to ordinary gas oil. According to the experiment, if the modified oil is added to normal light oil so that the weight ratio after mixing is about 1% or more, preferably 5% or more, the effect as a combustion aid is sufficiently obtained. It turns out that you can get.

Next, a specific structure of a fuel injection device for injecting liquid fuel into a combustion chamber of an internal combustion engine in a supercritical state will be described. FIG. 1 is a schematic diagram showing the configuration of an embodiment of a fuel injection device of the present invention. In FIG.
Reference numeral 1 is a diesel engine, 2 is a fuel injection valve for injecting light oil in a supercritical state into each combustion chamber of the diesel engine, and 11 is a fuel tank for storing fuel (light oil) of the engine 1. Also,
In FIG. 1, reference numeral 13 denotes a fuel supply pump that pumps the fuel in the fuel tank 11 to the fuel tank 15 for injection. Further, 17 in FIG. 1 is a critical pressure pump for boosting the fuel in the injection fuel tank 15 to a predetermined pressure equal to or higher than the critical pressure and supplying it to the supercritical pressure fuel injection pump 19, and 18 is from the supercritical pressure fuel injection pump 19. This is a supercritical state generation device having a heater 18b such as an electric heater for heating the fuel supplied to the fuel injection valve 2 to a temperature equal to or higher than the critical temperature.

The liquid fuel is boosted from the injection fuel tank 15 by the critical pressure pump 17 to a critical pressure of, for example, about 3 to 6 MPa, and as will be described later, a passage in the valve body 19a in the supercritical pressure fuel injection pump 19. 19h to flow into the heating chamber 18a in the supercritical state generator 18,
Depending on b, a temperature above the critical temperature (for example, 400 to 550 ° C.)
It becomes a supercritical state by being heated to a certain degree). Further, at the fuel injection timing, the fuel in the heating chamber 18a is further increased in pressure by the plunger 19b in the supercritical pressure fuel injection pump 19. As a result, when the fuel pressure exceeds the opening pressure of the fuel injection valve 2, the fuel in the supercritical state in the heating chamber 18a is injected from the fuel injection valve 2, and extremely fine fuel particles are uniformly formed in the engine combustion chamber. It

FIG. 2 shows the supercritical pressure fuel injection pump 1 of FIG.
It is a figure which shows schematic structure of 9. In FIG. 19, 19d
Is a cylindrical cylinder, 19a is a spool driven by a solenoid actuator 19c to slide in the cylinder 19d, 19b is a plunger driven by a cam shaft (not shown) of the engine 1 to reciprocate in the cylinder 19d, and 19e is a spool 19a. And a plunger 19b is a pressurizing chamber defined in the cylinder. The stroke of the plunger 19b is adjusted according to the load of the engine 1 by a governor (not shown).

During lowering of the plunger 19b, the spool 19
2a is moved to the lowered position shown in FIG. 2 by the solenoid 19c, and the fuel pumped from the critical pressure pump 17 through the pipe 21 passes through the port 21a and the passage 19h in the spool 19a, and from the port 24a through the pipe 24. And is directly supplied to the heating chamber 18a of the supercritical state generator 18. In addition, a part of the fuel from the critical pressure pump 17 is connected to the pipe 2
2, is supplied from the port 22a into the pressurizing chamber 19e. Further, when the plunger 19b descends to a predetermined position, the port 23a opens, and the surplus fuel supplied to 19e is returned to the fuel tank 11 through the return pipe 23. FIG.
Reference numeral 23b denotes a cooling water jacket for cooling the fuel flowing back through the return pipe 23.

Next, the plunger 19b starts to rise,
When the ports 23a and 22a are closed by the plunger 19b, the pressure of the fuel in the pressurizing chamber 19e increases the plunger 19b.
Increases with the rise of. In this state, when the fuel injection timing from the fuel injection valve 2 comes, the spool 19a is moved to the raised position by the solenoid 19c, the above-mentioned passage 19h is closed, and instead, another passage 19j in the spool 19a is provided.
Communicate with the port 24a. In this state, the fuel in the pressurizing chamber 19e, whose pressure is increased by the plunger 19b, passes through the passage 1
9j, it flows into the heating chamber 18a through the port 24, and the pressure of the fuel in the heating chamber 18a further rises. A check valve 19k is provided in the passage 19j of the plunger 19b to prevent the fuel in the heating chamber 18a from flowing backward from the passage 19j to the pressurizing chamber 19e.

As the plunger 19b rises, the heating chamber 1
When the fuel pressure in 8a becomes higher than the valve opening pressure of the fuel injection valve 2, the fuel in the heating chamber 18 is injected from the fuel injection valve 2 as described above. Then, when the plunger 19b starts to descend, the pressure in the heating chamber 18a decreases, and when the pressure becomes lower than the valve opening pressure of the fuel injection valve 2, the fuel injection valve 2 closes and the fuel injection ends. Further, at this time, the check valve 19k is closed, so that the fuel pressure in the heating chamber 18a is maintained above the critical pressure, and the fuel in the heating chamber 18a is maintained in the supercritical state. Then, the spool 19a is moved to the lowered position of FIG. 2, and the above-mentioned fuel injection cycle is started again. It should be noted that by appropriately selecting the volume of the heating chamber 18a, the residence time of the fuel in the heating chamber 18a can be arbitrarily set, and the heater 18b secures a time for sufficiently raising the fuel temperature to the critical temperature. can do.

The apparatus of FIG. 1 makes it possible to inject liquid fuel in the supercritical state into the combustion chamber of the engine 1. The opening pressure of the fuel injection valve 2 and the temperature in the heating chamber 18a are the pressure and temperature at which all the components of the liquid fuel are completely in a supercritical state (for example, in the case of light oil, the pressure is 3 to 6 MPa or more, and the temperature is 400 MPa). It is preferable to set the temperature to 500 ° C. or higher), but as described above, the effect of refining the fuel can be sufficiently obtained even when the pressure and temperature are set so that only a part of the components becomes a supercritical state. . Further, it is also possible to previously add an oxygen-containing substance such as water or methanol to the light oil in the fuel tank 11 so as to suppress the generation of alkylbenzene by combustion.

Next, referring to FIG. 3, an example of a concrete apparatus configuration for reforming a liquid fuel in a supercritical state will be described. FIG.
Shows a schematic configuration of an apparatus for reforming the liquid fuel supplied to the fuel tank 11 in a supercritical state and injecting it into the combustion chamber of the engine 1. 3, the same reference numerals as those in FIG. 1 indicate the same elements as those in FIG. In the embodiment shown in FIG. 3, the second fuel is supplied from the fuel tank 1 to the supercritical reformer 31.
1 is that the critical pressure pump 33 of FIG. 1 is provided, and that the reformed fuel tank 35 that stores the reformed fuel is provided instead of the injection fuel tank 15 of FIG. Is different from In this embodiment, the second critical pressure pump 33 supplies the fuel to the supercritical reformer 31 at a pressure of about 3 to 6 MPa. The supercritical reformer 31 includes a heater 31.
a and a fuel heating passage 31b for heating the fuel by the heater 31a. The fuel is heated by the heater 31a while flowing through the heating passage 31b in the reformer 31, exceeds the critical temperature, and becomes a supercritical state. The flow velocity (residence time) of the fuel in the passage 31b is adjusted by the flow rate control valve 37. In this embodiment, the fuel is 400 to 60
Passage 3 of reformer 31 at a temperature of about 0 ° C. for about 20 minutes
1b so that the flow control valve 37 and the heater 31
The capacity of a is set. As a result, the fuel is reformer 3
When the fuel passes through the passage 31b in the fuel cell 1, the reformed fuel is stored in the reforming tank 35.

Further, in the present embodiment, the fuel in the reforming tank 35 is the critical pressure pump 17, as in the embodiment of FIG.
Supercritical pressure fuel injection pump 19, supercritical state generation device 18
Then, the fuel is injected into the supercritical state again by the fuel injection valve 2 and injected into the combustion chamber of the engine. However, the configuration and operation of these devices are the same as those in FIG. According to this embodiment, the reformer 31 is arranged in the fuel supply path from the fuel tank 11 to the fuel injection valve 2. Therefore, for example, in a vehicle internal combustion engine, fuel reforming can be performed on the vehicle. . For this reason, there is no need to supply a special reformed fuel to the vehicle, and there is an advantage that a special refueling facility for refueling becomes unnecessary.

In this embodiment, the reformed fuel is injected in the supercritical state again. However, the reformed fuel is injected as a liquid by using a normal fuel injection pump. However, it goes without saying that a combustion improving effect can be obtained by reforming the fuel. Further, instead of the flow rate control valve 37 of the supercritical reformer 31 of FIG. 3, a shutoff valve opened and closed by a timer may be provided to reform the fuel in the reformer 31 by batch processing. is there. Further, also in the present embodiment, by adding an oxygen-containing substance such as water or ethanol to the fuel in the fuel tank 11 in advance, the alkylbenzene in the reformer 31 and at the time of combustion of the fuel after the reforming is increased. It is possible to suppress the production of components and further improve the combustion state.

[0047]

According to the invention described in each of the claims, by making the liquid fuel into a supercritical state, the combustion state of the engine is significantly improved, and cleaning of exhaust gas and reduction of fuel consumption are achieved at the same time. A common effect that enables That is,
According to the invention of claim 1, by supplying the fuel into the combustion chamber in a supercritical state, it is possible to form extremely fine fuel fine particles in the combustion chamber without using a high-pressure injection pump. The engine combustion condition is greatly improved.

According to the second aspect of the present invention, the combustion state of the engine is greatly improved by supplying the reformed fuel in the supercritical state to the engine. Further, claim 3
According to the invention described in claim 2, since the fuel reformed in claim 2 is supplied to the combustion chamber in a further supercritical state, it is possible to further improve the combustion state in addition to the effect of claim 2. The effect is obtained.

Further, in the invention described in claim 4, by applying any one of claims 1 to 3 to the diesel engine, it is possible to achieve the cleaning of the exhaust gas of the diesel engine and the reduction of the fuel consumption at the same time. And the effect is obtained. Further, according to the invention of claim 5, by adding the oxygen-containing substance to the liquid fuel in advance in claim 4, in addition to the effect of claim 4, generation of particulates during combustion can be effectively suppressed. An excellent effect can be obtained. Further, according to the inventions of claims 6 and 7, when the inventions of claims 1 to 4 are applied to an engine for a vehicle, it becomes possible to generate a supercritical state of fuel on the vehicle, The effects of each of the above claims can be achieved.

Further, according to the inventions of claims 8 and 9, appropriate conditions are set when reforming the light oil in the supercritical state, and the effect of improving the combustion state of the engine can be obtained. Claim 1
According to the inventions of 0 and 11, by using the light oil reformed in the supercritical state as the combustion aid of the unreformed light oil, the combustion state of the engine can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of the supercritical pressure fuel injection pump of FIG.

FIG. 3 is a schematic view showing a configuration of an embodiment different from FIG. 1 of the present invention.

FIG. 4 is a diagram showing the critical pressure and critical temperature of each component contained in light oil.

FIG. 5 is a diagram illustrating a result of reforming light oil in a supercritical state.

FIG. 6 is a diagram illustrating a result of reforming light oil in a supercritical state.

FIG. 7 is a diagram illustrating a result of reforming light oil in a supercritical state.

FIG. 8 is a diagram illustrating a result of reforming light oil in a supercritical state.

FIG. 9 is a diagram illustrating a result of reforming light oil in a supercritical state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 17 ... Critical pressure pump 18 ... Supercritical state generation device 19 ... Supercritical pressure fuel injection pump 31 ... Supercritical reformer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor ▲ Taka ▼ Nobuaki Sawa 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Yasushi Takahashi 1, Toyota Town, Aichi Prefecture Toyota Motor Corporation Stock In-house (72) Inventor Atsushi Hiei, 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd.

Claims (11)

[Claims] 1. A fuel supply method for an internal combustion engine, wherein a liquid fuel is brought into a supercritical state and the fuel in the supercritical state is supplied into a combustion chamber of the internal combustion engine. 2. A fuel injection method for an internal combustion engine for a vehicle, comprising performing reforming in a liquid fuel supercritical state on a vehicle and supplying the reformed fuel to a combustion chamber of the internal combustion engine. Fuel supply method. 3. The fuel supply method according to claim 2, further comprising supplying the reformed fuel into a combustion chamber of the internal combustion engine in a supercritical state. 4. The internal combustion engine is a diesel engine,
The fuel supply method according to claim 1, wherein the liquid fuel is light oil. 5. The fuel supply method according to claim 4, wherein an oxygen-containing substance is added to the liquid fuel in advance. 6. A fuel tank for storing liquid fuel, a fuel injection valve for injecting fuel supplied from the fuel tank into a combustion chamber of an internal combustion engine, and a fuel supply path between the fuel tank and the fuel injection valve. A fuel supply device for an internal combustion engine, comprising: a supercritical state generating means provided therein for bringing the liquid fuel into a supercritical state. 7. The method according to claim 6, wherein the supercritical state generating means includes a pressurizing means for pressurizing the liquid fuel to a predetermined pressure and a heating means for heating the liquid fuel to a predetermined temperature. The fuel supply device described. 8. A method for supplying light oil to an internal combustion engine, the light oil being reformed while maintaining the temperature at 400 ° C. or higher and the pressure at 1.5 MPa or higher, and then the reformed light oil is supplied to the internal combustion engine. Fuel supply method. 9. A method for supplying light oil to an internal combustion engine, the light oil being supplied at a temperature of 400 ° C. to 550 ° C. and a pressure of 1.5M.
A fuel supply method in which the fuel gas is maintained at Pa or higher and reformed, and then the reformed light oil is supplied to the internal combustion engine. 10. A method for supplying light oil to an internal combustion engine, the light oil being reformed while maintaining a temperature of 400 ° C. or higher and a pressure of 1.5 MPa or higher, and then the reformed light oil is an unreformed light oil. And a mixture of the reformed gas oil and unreformed gas oil, and supplying the mixture to the engine. 11. A method for supplying light oil to an internal combustion engine, the light oil being supplied at a temperature of 400 ° C. to 550 ° C. and a pressure of 1.5M.
A fuel supply method of holding at or above Pa for reforming, then mixing reformed gas oil with unmodified gas oil, and supplying a mixture of the modified gas oil and unmodified gas oil to the engine.