JPH07293346A - Fuel supply device for engine - Google Patents

Abstract

PURPOSE:To attain reduction of retarding of ignition, and smoke even when assistant fuel being the same in kind as main fuel is used in a fuel supply device which supplies the assistant fuel to the intake pipe of an engine independently on the main fuel. CONSTITUTION:Low boiling point component of fuel which is vaporized by a fuel fractionation device 11 is stored in a fuel storage tank 15 having a cooler as low boiling point fuel. High boiling point fuel including high boiling point component is supplied to an engine l through an injection pump 3 and an injection nozzle 4. The low boiling point fuel is injected from the storing tank 15 through an injector 17 to a fuel vaporizing device 19. The low boiling point fuel vaporized by the fuel vaporizing device 19 is supplied into an intake pipe 5 as assistant fuel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for an engine, and more particularly to a fuel supply system for supplying auxiliary fuel to a diesel engine in addition to main fuel.

[0002]

2. Description of the Related Art It is known to supply atomized auxiliary fuel into the intake pipe of an engine in addition to the main fuel supplied into the cylinder of the engine. According to such a fuel supply device, the auxiliary fuel having a high self-igniting property forms an atmosphere in the cylinder that is easily ignited, the ignition of the main fuel is promoted, and the ignition delay period is shortened. Further, the mixing of fuel and air is promoted, the air utilization rate is improved, and the smoke emission amount from the engine can be reduced.

[0003]

From the viewpoint of further reducing smoke, it is desirable to use gasoline as an auxiliary fuel when diesel oil is used as the main fuel in a diesel engine. The use of different auxiliary fuels may be impractical. Therefore, in the above fuel supply device, generally, the same type of fuel as the main fuel is used as the auxiliary fuel. However, when the same type of auxiliary fuel as the main fuel is used, the ignition delay period shortening effect and the smoke reducing effect due to the auxiliary fuel supply are relatively small compared to the case of using the main fuel and a different type of auxiliary fuel.

Therefore, an object of the present invention is to provide an engine fuel supply system capable of increasing the ignition delay period shortening effect, smoke reducing effect and the like even when an auxiliary fuel of the same type as the main fuel is used.

[0005]

The fuel supply system of the present invention comprises a main fuel supply means for supplying a first fuel as a main fuel to a combustion chamber of an engine, and a low boiling point component and a high boiling point component of the second fuel. The fuel cell system is characterized by comprising fuel separation means for separating the boiling point component to obtain a low boiling point fuel, and auxiliary fuel supply means for supplying the low boiling point fuel as an auxiliary fuel into the intake pipe of the engine.

Preferably, the second fuel is the same fuel as the first fuel. Preferably, the auxiliary fuel supply means has a fuel atomization means for atomizing the low boiling point fuel. More preferably, the fuel atomizing means has an ultrasonic vibrator for vibrating the low boiling point fuel to atomize it. Preferably, the main fuel supply means uses the high boiling point fuel obtained by separating the low boiling point component and the high boiling point component of the second fuel by the fuel separating means as the first fuel, or uses the high boiling point fuel as the first fuel.
It is supplied to the combustion chamber as the main fuel together with the above fuel.

Preferably, the fuel separating means utilizes the exhaust heat of the engine for separating the low boiling point component and the high boiling point component of the second fuel. Preferably the engine is a diesel engine and the first and second fuels are light oils. Preferably, the auxiliary fuel supply means controls the auxiliary fuel supply amount according to the operating state of the engine. More preferably, the auxiliary fuel supply means stores the low boiling point fuel, and supplies the stored low boiling point fuel into the intake pipe when the engine is operating in a predetermined operating range. The predetermined operating range includes an engine starting operating range, an acceleration operating range, and a low speed fully open operating range.

[0008]

The first fuel is supplied to the combustion chamber of the engine as the main fuel by the main fuel supply means. Further, the low boiling point component and the high boiling point component of the second fuel are separated by the fuel separating means to obtain the low boiling point fuel. This low boiling point fuel is supplied as auxiliary fuel into the intake pipe of the engine by the auxiliary fuel supply means. Since the low boiling point fuel is rich in self-ignitability, the ignition of the main fuel is promoted and the ignition delay is shortened. Also,
The sudden increase in the engine combustion chamber pressure is suppressed, and the operating noise is reduced.

In a preferred embodiment of the present invention, a second fuel of the same type as the first fuel is used. Also in this case, since the auxiliary fuel is a low boiling point fuel having excellent ignitability, the ignition delay shortening effect is achieved. In another aspect, the low-boiling-point fuel is atomized by, for example, vibrating, for example, by a fuel atomizing means having an ultrasonic oscillator, and then used as an auxiliary fuel. In this case, the ignitability of the auxiliary fuel is further improved and the ignition delay is shortened. In addition, mixing of the auxiliary fuel and air is promoted, the air utilization rate is improved, and smoke is reduced.

In another aspect, the high boiling point fuel is used as the first fuel or is supplied as the main fuel together with the first fuel. In this case, the high boiling point fuel is effectively used without lowering the ignitability. In another aspect, the exhaust heat of the engine is used to separate the low-boiling point component and the high-boiling point component, and a special heat source for separating the components is unnecessary.

In another embodiment, diesel oil is supplied to the diesel engine as the main fuel and the low boiling point component of the diesel oil is supplied as the auxiliary fuel to improve the combustion state of the diesel engine. In still another aspect, the auxiliary fuel supply amount is controlled by the auxiliary fuel supply means according to the engine operating state. For example, when the engine is operating in a predetermined operating range including a starting operating range, an accelerating operating range and a low speed fully open operating range, the stored low boiling point fuel is supplied to the engine. In this case, the load on the fuel separation means and the auxiliary fuel supply means is reduced compared to the case where the components are separated and the auxiliary fuel is supplied in the entire engine operating range, and the assist when the engine is operating in the predetermined operating range is reduced. Fuel is reliably supplied, and smoke reduction in a predetermined operating range is achieved.

[0012]

In FIG. 1, an engine 1 equipped with a fuel supply system according to an embodiment of the present invention is, for example, a four-cylinder diesel engine that uses light oil fuel, and operates under the control of a controller 2, for example. A distribution type injection pump 3 and an injection nozzle 4 for injecting high-pressure fuel from the injection pump 3 into a cylinder (not shown) of the engine 1.
And an intake pipe 5 communicating with the cylinder of the engine 1.

The fuel supply system supplies the main fuel into the cylinder of the engine 1 through the injection pump 3 and the injection nozzle 4 and the auxiliary fuel into the intake pipe 5 of the engine 1. Then, the high boiling point component of light oil is supplied as the main fuel, and the low boiling point component is supplied as the auxiliary fuel. Therefore, the fuel supply device includes a fuel fractionation device 11 for separating the low boiling point component and the high boiling point component of the light oil, and the light oil fuel is supplied to the fuel distilling device 11 via the fuel pipe 12. It is supposed to be done.

Although not shown, the fuel fractionating device 11 is
A vaporization chamber communicating with the fuel pipe 12 is provided, and a heating pipe is arranged around the vaporization chamber. One end of the heating pipe communicates with the first intermediate portion of the exhaust pipe of the engine 1, and the other end of the heating pipe communicates with the exhaust pipe downstream of the first intermediate portion. Therefore, a part of the exhaust gas flowing in the exhaust pipe flows into the heating pipe, then flows in the heating pipe and is discharged to the exhaust pipe. Then, the vaporization chamber is heated by the high temperature exhaust gas flowing in the heating pipe, and therefore,
The light oil introduced into the vaporization chamber through the fuel pipe 12 is heated and the low boiling point components of the light oil are vaporized to become fuel gas,
On the other hand, the high-boiling point component of light oil accumulates in the bottom of the vaporization chamber as a liquid high-boiling point fuel.

The high boiling point fuel accumulated at the bottom of the vaporization chamber is supplied to the injection pump 3 through the high boiling point fuel pipe 13, and further supplied as the main fuel to the cylinder of the engine 1 through the injection pump 3 and the injection nozzle 4. Will be done. On the other hand, the low boiling point component vaporized in the vaporization chamber is introduced into the fuel storage tank 15 with a cooling device through the fuel gas pipe 14, and is cooled and liquefied by the cooling device (not shown) of the storage tank 15, It becomes a low boiling point fuel with a high cetane number and rich in self-ignitability. This low boiling point fuel is supplied to the injector 17 via the low boiling point fuel pipe 16. Then, the injector 17 driven and controlled by the controller 2 injects the low boiling point fuel into the fuel atomization device 19. The fuel atomization device 19 supplies the auxiliary fuel obtained by atomizing the low boiling point fuel to the chamber 18.

The chamber 18 communicates with the intake pipe 5 of the engine 1 via the auxiliary fuel passage 20. And
An opening / closing valve 21 for adjusting the auxiliary fuel supply amount is arranged in the auxiliary fuel passage 20, and the opening degree of the opening / closing valve 21 is adjusted by an actuator driven and controlled by the controller 2, for example, a stepper motor 22. Has become.

As shown in FIG. 2, the fuel atomizer 19 of this embodiment is provided with a vibrating horn 191. The vibrating horn 191 has a substantially disk-shaped horn body 191a having an injector mounting hole formed therein, and a hollow cylindrical portion 191b integral with the horn body 191a, and the injector 17 is fitted in the injector mounting hole. Then, in the axially intermediate portion of the hollow cylindrical portion 191b, on the peripheral wall of the hollow cylindrical portion 191b,
A protrusion 191c protruding inward in the radial direction of the hollow cylindrical portion
Is integrally formed with the hollow cylindrical portion 191b, and a fuel reservoir plate 191d is integrally formed with the peripheral wall of the hollow cylindrical portion 191b so as to close a corresponding portion of the tip opening.

On the other hand, an annular electrostrictive element 192 as an ultrasonic transducer is arranged on the top surface of the vibrating horn body 191a opposite to the hollow cylindrical portion 191b.
Are clamped between the vibrating horn body 191 a and the support plate 193 by tightening bolts 194. The fuel atomization device 19 further includes an oscillating device 195 that is driven and controlled by the controller 2. Although detailed illustration is omitted,
This oscillator 195 has an ultrasonic frequency of, for example, 40 KH.
z first excitation signal and predetermined frequency, for example 320 Hz
The first and second oscillating units for respectively generating the second excitation signal and the modulating unit for modulating the first exciting signal with the second exciting signal, and the output side of the modulating unit includes the electrostrictive element 192. It is connected to the. When the modulator output is applied, the electrostrictive element 19
2 is excited by the first excitation signal of 40 KHz, for example, and is excited by the second excitation signal of 320 Hz, for example.

The operation of the fuel supply system having the above construction will be described below. During the operation of the diesel engine 1, the controller 2 causes the engine 1 to perform a predetermined operation range in which a large amount of smoke is generated, based on output signals from various sensors (not shown).
For example, it is determined whether or not the vehicle is operating in the starting operation range, the acceleration operation range, or the low speed fully open operation range.

When the engine 1 is operating in an operating range other than the predetermined operating range, the injector 17 is deactivated under the control of the controller 2 and the oscillating device 195 of the fuel atomizing device 19 moves to the electrostrictive element 192. The application of the first and second excitation signals is prohibited, and the stepper motor 22 is drive-controlled so that the opening / closing valve 21 is closed. As a result, the injection of the low boiling point fuel from the injector 17 to the fuel atomizing device 19 is stopped, the atomization of the low boiling point fuel by the fuel atomizing device 19 is stopped, and the chamber 18 and the intake pipe 5 of the engine 1 are connected to each other. Communication is cut off. Therefore, the engine 1
Supply of auxiliary fuel to the combustion chamber of the engine is blocked.

On the other hand, a high boiling point fuel consisting of a high boiling point component of light oil fuel is supplied as a main fuel from the fuel fractionating device 11 to the injection pump 3 via the high boiling point fuel pipe 13. Then, the high-pressure main fuel from the injection pump 3 that is drive-controlled by the controller 2 is supplied to the respective injection nozzles 4 at suitable timing, and is injected from the injection nozzles 4 into the combustion chamber of the engine 1.

Unlike the above case, if the engine 1 is operating in a predetermined operating range, under the control of the controller 2,
The injector 17 is driven to open the valve, and the fuel atomizer 19
The first and second excitation signals are applied from the oscillating device 195 to the electrostrictive element 192, and the stepper motor 22 is driven so that the on-off valve opens. As a result, the low boiling point fuel stored in the fuel storage tank 15 is supplied to the guide protrusion 191c of the vibration horn 191 of the fuel atomization device 19. At this time, the electrostrictive element 192 is vibrated by being excited by the first and second excitation signals from the oscillator 195. Then, the guide protrusion 1 is generated by the vibration of the electrostrictive element 192.
The low boiling point fuel of 91c moves onto the fuel collecting plate 191d, is uniformly atomized, and is discharged into the air to form a spray. Moreover, since the electrostrictive element 192 is vibrated by the first and second excitation signals having different frequencies, the entire low boiling point fuel is finely atomized as compared with the case where the excitation signal of a single frequency is vibrated. To be done.

Then, the uniform fine particles of the low boiling point fuel are scattered in the air in the chamber 18 and become atomized auxiliary fuel. At this time, since the on-off valve 21 is opened, the auxiliary fuel flows into the intake pipe 5 of the engine 1 through the auxiliary fuel passage 20 and is sucked into the combustion chamber of the engine 1 together with the air flowing in the intake pipe 5. To be done. As described above, when the engine 1 is operated in the predetermined operation range, the auxiliary fuel is used as the engine 1
Is supplied to the combustion chamber of. On the other hand, as in the case where the engine 1 is operated in an operating range other than the predetermined operating range, the high boiling point fuel is supplied to the combustion chamber of the engine 1 as the main fuel. In this way, when an auxiliary fuel composed of a low boiling point fuel having a high cetane number and good self-ignitability is supplied, an atmosphere that easily ignites is formed in the combustion chamber, and therefore, the ignitability of the main fuel is improved, The ignition delay period is shortened. Further, since the auxiliary fuel is atomized, mixing of the fuel and air is promoted, and the air utilization rate is improved, which reduces the amount of smoke generated.

It should be noted that even when the auxiliary fuel is the same kind of fuel as the main fuel as in the present embodiment, remarkable ignitability improvement and smoke reduction effects are exhibited. Also,
When the auxiliary fuel supply is performed only in the predetermined engine operating range, the processing performance required for the fuel fractionation device 11 and the fuel atomization device 19 is moderately compared with the case where the auxiliary fuel supply is performed in the entire engine operating range. It can be suppressed, so that both devices 1
It is possible to reduce the cost and size of the devices 1 and 19.

During the engine operation, part of the exhaust gas flowing through the exhaust pipe of the engine 1 flows through the heating pipe of the fuel fractionating device 11. For this reason, the light oil fuel in the vaporization chamber arranged near the heating pipe is heated by the exhaust heat, and the low boiling point component of the light oil fuel is vaporized. On the other hand, the high boiling point component of the light oil fuel accumulates in the vaporization chamber as a liquid high boiling point fuel, and is supplied to the injection pump 3 via the high boiling point fuel pipe 13 as described above. That is, the low boiling point component and the high boiling point component can be separated without using a special heat source.

The low boiling point component vaporized in the vaporization chamber is introduced into the fuel storage tank 15 through the fuel gas pipe 14, cooled by the cooling device of the tank and liquefied to become a low boiling point fuel. This low boiling point fuel serves as an auxiliary fuel as described above. Even if the separation of the low boiling point component and the high boiling point component of the light oil fuel in the fuel fractionating device 11 is delayed with respect to the fuel consumption, the light oil fuel containing both components is only supplied to the injection pump 3. No, there is no problem. Also, such a situation will be resolved within a certain amount of time,
Auxiliary fuel supply can be restarted if necessary.

The present invention is not limited to the above embodiment, but can be variously modified. In the embodiment, the case where it is applied to a diesel engine using light oil fuel has been described.
The fuel supply device of the present invention can be installed in, for example, a direct injection type gasoline engine as well as a diesel engine. Also, in the example,
Although the auxiliary fuel composed of the same fuel as the main fuel is used, an auxiliary fuel different from the main fuel may be used.

Further, in the embodiment, the high boiling point component of the fuel is mainly used as the main fuel, but the fuel which is not separated into the low boiling point component and the high boiling point component may be used as the main fuel. Alternatively, both the fuel that has not been separated into components and the high boiling point component of the fuel may be used as the main fuel. Further, in the embodiment, the exhaust heat is used as the heat source of the fuel fractionation device, but instead of this, other heat sources, for example, an electric heater may be used, or the exhaust heat and other heat sources may be used. Both may be used. FIG. 3 shows a fuel distilling device using an electric heater as a heat source.
Reference numeral 2 denotes an electric heater and a vaporization chamber, respectively.

Furthermore, it is not essential to equip the fuel supply device of the present invention with a fuel atomizer. Further, although the fuel atomizer including the electrostrictive element is used in the embodiment, other fuel atomizers may be used.

[0030]

As described above, the fuel supply system of the present invention comprises the main fuel supply means for supplying the first fuel to the combustion chamber of the engine as the main fuel, and the low boiling point component of the second fuel. Since the fuel separation means for separating the high boiling point component to obtain the low boiling point fuel and the auxiliary fuel supply means for supplying the low boiling point fuel as the auxiliary fuel into the intake pipe of the engine are provided, the cetane number is high and The low boiling point component of the fuel, which has excellent ignitability, can be supplied as an auxiliary fuel. Therefore, ignition of the main fuel can be promoted, ignition delay can be shortened, and sudden increase in fuel chamber pressure can be suppressed to reduce operating noise. .

Further, according to the preferred embodiment of the present invention in which the second fuel, which is the same fuel as the first fuel, is used, even when the main fuel and the auxiliary fuel are of the same type, a considerable ignition delay reduction effect can be obtained. Can be achieved. Further, in a preferred mode including the fuel atomizing means having an ultrasonic oscillator or the like, the low boiling point fuel is atomized and used as the auxiliary fuel, so that the ignitability of the auxiliary fuel is further improved and the ignition delay can be shortened. Further, it is possible to promote mixing of the auxiliary fuel and air, improve the air utilization rate, and reduce smoke.

According to a preferable mode in which the high boiling point fuel is used as the first fuel or is supplied together with the first fuel as the main fuel, the high boiling point fuel can be effectively utilized without lowering the ignitability. According to the preferable mode in which the low boiling point component and the high boiling point component are separated by utilizing the exhaust heat of the engine, a special heat source for separating the components is not required.

Further, according to the preferable mode in which the light oil is supplied to the diesel engine as the main fuel and the low boiling point component of the light oil is supplied as the auxiliary fuel, the combustion state in the diesel engine can be improved. Further, in a preferred mode in which the auxiliary fuel supply amount is controlled by the auxiliary fuel supply means according to the engine operating state, for example, the engine is operated in a predetermined operating region including a starting operating region, an accelerating operating region and a low speed fully open operating region. Since the stored low boiling point fuel is supplied to the engine during operation, the burden on the fuel separation means and auxiliary fuel supply means is reduced compared to the case where component separation and auxiliary fuel supply are performed in the entire engine operating range. At the same time, it is possible to reliably supply the auxiliary fuel when the engine is operating in the predetermined operating range, and thereby it is possible to achieve smoke reduction in the predetermined operating range.

[Brief description of drawings]

FIG. 1 is a schematic view showing a fuel supply device according to an embodiment of the present invention together with peripheral elements.

FIG. 2 is a schematic sectional view showing a part of the fuel atomization device shown in FIG. 1 as a block.

FIG. 3 is a schematic perspective view showing a modified example of the fuel fractionating device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Controller 3 Injection pump 4 Injection nozzle 5 Intake pipe 11 Fuel diversion device 15 Fuel storage tank with cooling device 17 Injector 18 Chamber 19 Fuel atomizer 21 Open / close valve 191 Vibration horn 192 Electrostrictive element 195 Oscillator

Claims (11)

[Claims] 1. A low-boiling fuel is obtained by separating a main-fuel supplying means for supplying a first fuel into a combustion chamber of an engine as a main fuel and a low-boiling component and a high-boiling component of the second fuel. And a sub-fuel supply unit for supplying a low boiling point fuel as an auxiliary fuel into the intake pipe of the engine. 2. The fuel supply system for an engine according to claim 1, wherein the second fuel is the same fuel as the first fuel. 3. The fuel supply device for an engine according to claim 1, wherein the auxiliary fuel supply unit has a fuel atomization unit for atomizing the low boiling point fuel. 4. The fuel supply system for an engine according to claim 3, wherein the fuel atomization means has an ultrasonic vibrator for vibrating the low boiling point fuel to atomize it. 5. The high-boiling fuel obtained by separating the low-boiling point component and the high-boiling point component of the second fuel by the fuel separating means is used as the first fuel by the main fuel supply means. The fuel supply system for an engine according to claim 1, wherein: 6. The main fuel supply means includes a high boiling point fuel obtained by separating the low boiling point component and the high boiling point component of the second fuel by the fuel separating means together with the first fuel from the main fuel. The fuel supply device for an engine according to claim 1, wherein the fuel is supplied to the combustion chamber as fuel. 7. The engine according to claim 1, wherein the fuel separation means uses exhaust heat of the engine to separate the low boiling point component and the high boiling point component of the second fuel. Fuel supply system. 8. The fuel supply system for an engine according to claim 2, wherein the engine is a diesel engine, and the first and second fuels are light oils. 9. The fuel supply device for an engine according to claim 1, wherein the auxiliary fuel supply means controls the auxiliary fuel supply amount according to the operating state of the engine. 10. The auxiliary fuel supply means stores the low boiling point fuel, and stores the stored low boiling point fuel in the intake pipe when the engine is operating in a predetermined operating range. The fuel supply device for an engine according to claim 9, wherein the fuel is supplied. 11. The fuel supply system for an engine according to claim 10, wherein the predetermined operating range includes a starting operating range, an accelerating operating range and a low speed fully open operating range of the engine.