JP2006161722A - Fuel supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel supply device improving low temperature startability of an internal combustion engine. <P>SOLUTION: This invented fuel supply device supplies fuel to the internal combustion engine and is provided with a fuel component separation means 14 distilling and separating low ignition point component or low boiling point component in fuel, and a fuel change over means 16 selectively changing fuel supplied to the internal combustion engine. Fuel of low ignition point component or low boiling point component is supplied at a time of low temperature start of the internal combustion engine. The fuel component separation means 14 is installed in an exhaust gas route of the internal combustion engine and is provided with a fuel vaporizer 42. And the fuel vaporizer consists of a fin part erectly provided on an outer circumference surface of an exhaust pipe 44 in the exhaust route and a shell body storing the fin part and formed concentrically with the exhaust pipe. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel supply device that supplies fuel to an internal combustion engine such as a gasoline engine or a diesel engine.

  Fuels of internal combustion engines such as gasoline and light oil are composed of many hydrocarbon components having different carbon numbers and bonding states, and these components each have inherent distillation characteristics. For this reason, problems such as deterioration of exhaust gas in gasoline engines and ignition delay in diesel engines may occur, especially in cold start in winter in cold regions.

  For example, normal butane containing about 4% or isopentane containing about 13% in gasoline is a fuel component suitable for starting at a low temperature because it has a low boiling point compared to toluene, which has a high content of 20%. However, since it also contains a high-boiling component such as toluene as described above, the fuel supply amount is increased during start-up at low temperatures to ensure operability. For this reason, a large amount of hydrocarbons are mixed in the exhaust gas, which may cause a reduction in fuel consumption and environmental degradation. In light oil used in diesel engines, paraffinic normal decane, which is a straight-chain component, has an ignition point lower than 200 ° C compared to aroma-based ethylbenzene having a benzene nucleus, and ignition at low temperature start-up. Good properties. However, in light oil fuels containing a low ignition point component and a high ignition point component, ignition delay becomes a problem because the high ignition point component does not contribute effectively, particularly at the start in winter.

  By the way, the ignition delay of a diesel engine becomes shorter as the fuel with a higher cetane number (low ignition point component fuel) is used. There is known a fuel supply device that supplies fuel to an engine at low speed and low load (see Patent Document 1). In this fuel supply device, the linear component in the fuel component is adsorbed on the zeolite in the separation column, and then purge air is supplied to the separation column to extract only the high cetane number component, A cetane number component is selected as fuel. For example, a high cetane number fuel is supplied to the engine during idling, low speed and low load operation, and a low cetane number fuel is supplied during medium and high load operation which is not easily affected by cetane number. It is said that the noise level at low speed and low load including idling can be reduced without deteriorating drivability, fuel consumption, noise, etc. during medium and high load operation. In addition, the engine startability and the operability during warm-up can be improved by supplying fuel with a high cetane number to the engine during engine start-up and warm-up.

However, when starting at low temperatures, fuel vaporization is important, but it is an indicator of cetane number ignition delay and cannot be directly separated into effective components.
JP-A-56-143323

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel supply device that can improve the low-temperature startability of an internal combustion engine.

  The inventor has paid attention to the fact that a fuel having a low ignition point component or a low boiling point component as a main component can be easily obtained by distilling and separating the fuel component using the exhaust heat of the internal combustion engine.

The fuel supply device of the present invention is a fuel supply device for supplying fuel to an internal combustion engine,
A fuel component separating means for distilling and separating a low ignition point component or a low boiling point component in the fuel; and a fuel switching means for selectively switching the fuel supplied to the internal combustion engine. A low boiling point component is supplied as a fuel.

  Since the fuel supply device of the present invention is provided with the fuel component separation means, a low ignition point component or a low boiling point component that is particularly effective at the time of low temperature start-up can be distilled off from the used fuel to obtain a start fuel. Further, the fuel switching means can supply a fuel containing a high-concentration low-ignition point component or low-boiling point component instead of the normal fuel used at low temperature start. Therefore, the low temperature startability of the engine can be improved without causing problems such as a decrease in fuel consumption at the time of low temperature start, an increase in hydrocarbons in the exhaust, or an ignition delay.

  In the fuel supply apparatus of the present invention, the fuel component separation means includes a fuel carburetor interposed in the exhaust path of the internal combustion engine, and the fuel carburetor is a fin portion erected on the outer peripheral surface of the exhaust pipe of the exhaust path. And a shell that is coaxial with the exhaust pipe and accommodates the fin portion, and preferably separates the fuel into a gas component and a liquid component by exhaust heat.

  Since the fuel can be distilled and separated by a fuel vaporizer interposed in the exhaust path of the internal combustion engine, the separation means is compact and easy to control.

  The internal combustion engine may be a diesel engine, and the low ignition point component in this case is mainly normal decane in the fuel.

  The internal combustion engine may be a gasoline engine, and may be a direct injection gasoline engine that sprays fuel directly into a cylinder. In such a gasoline engine, the low boiling point component is mainly normal butane and / or isopentane in the fuel.

  By using the low ignition point component or the low boiling point component as described above as the low temperature starting fuel for the internal combustion engine, the low temperature startability of the internal combustion engine can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a system configuration of a fuel supply device in a direct injection gasoline engine which is a preferred embodiment of the present invention. The fuel supply device 10 includes a fuel component separation unit 14 that distills and separates a low ignition point component in the fuel, and a fuel switching unit 16 that selectively switches the fuel supplied to the engine A. The fuel selected by the fuel switching means 16 is injected from the injector 20 into the engine cylinder 22 via the fuel pump 18. The fuel switching means 16 is stored in the fuel tank 11 by driving an electromagnetic valve or the like according to a command from the ECU 28 based on ON information of the vehicle key switch 24 and temperature information from the engine coolant temperature gauge 26. The normal fuel F and the fuel f mainly composed of a low ignition point component stored in the starting fuel tank 12 are switched. In the figure, 30 is a spark plug, 32 is an exhaust valve, and 34 is a piston.

  FIG. 2 is a schematic diagram showing the configuration of the fuel component separation means 14 in the gasoline engine. The fuel component separation means 14 includes a fuel carburetor 42 interposed in the exhaust path of the internal combustion engine A. As shown in FIG. 4, the fuel carburetor 42 has a fin portion 46 erected on the outer peripheral surface of the exhaust pipe 44 in the exhaust path, and a shell body that is accommodated in the exhaust pipe 44 and accommodates the fin portion 46. 48, the fuel F can be separated into the gas component f and the liquid component F ′ by the heat of the exhaust E flowing in the exhaust pipe 44.

  In the fuel component separation means 14 having the fuel vaporizer 42 as described above, the used fuel (gasoline) F stored in the fuel tank 11 is supplied from the inlet 42a via the fuel valve 50 and is vaporized by exhaust heat. The gaseous component (for example, normal butane and / or isopentane) f flows through the flow path 52 from the outlet 42c, is liquefied by the cooling means 54, and is stored in the starting fuel tank 12. Further, the liquid component (for example, toluene) F ′ remaining without being vaporized is circulated to the fuel tank 11 through the flow path 56 connected to the outflow port 42 b and stored as the used fuel F. The ECU 28 is connected to the temperature measuring device 56 and the fuel valve 50, and instructs the fuel valve 50 to open / close based on the temperature information of the exhaust E detected by the temperature assumption device 58.

  FIG. 3 shows a schematic configuration of the fuel component separation means 14 in the diesel engine. In the diesel engine using light oil as a fuel, the same fuel vaporizer as shown in FIG. 4 can be used. However, in the case of diesel oil, the boiling point of normal decane, which is a high cetane number component effective at low temperature starting, is 174 ° C. (ignition point: 210 ° C.), whereas the boiling point of ethylbenzene having a low cetane number is 136 ° C. (ignition point). : 432 ° C.). For this reason, when fractionating with a fuel vaporizer, ethylbenzene having a low boiling point but a high ignition point is vaporized at a low temperature. Therefore, as shown in FIG. 3, the gas component (ethylbenzene) f is cooled and circulated to the fuel tank 11, and the liquid component (normal decane) F ′ is supplied to the starting fuel tank 12 and stored.

  FIG. 5 shows a flowchart of the operation of vaporizing and separating the used fuel by the fuel vaporizer 42.

  First, in step S11, the driver rotates the key 24 to turn on the switch. The ECU 28 measures the temperature of the exhaust gas in the exhaust pipe (step S12), and determines whether or not the used fuel F is supplied to the fuel carburetor 42 based on the temperature information (step S13). For example, in a gasoline engine, when the exhaust gas temperature is 50 ° C. or lower, the used fuel F is supplied to the fuel vaporizer 42 (step S14), and when it exceeds 50 ° C., the fuel is not supplied (step S18). Define it. That is, when the exhaust gas temperature is 50 ° C. or lower, the fuel valve 50 is “open”, and when it exceeds 50 ° C., the fuel valve 50 is “closed”.

  If the ECU 28 determines that the exhaust gas temperature is less than 50 ° C. (YES in step S13), the ECU 28 instructs the fuel valve 50 including an electromagnetic valve to open, and supplies the fuel F to the fuel carburetor 42 (step S14). Since the fuel vaporizer 42 is heated by the exhaust heat, the low boiling point component is vaporized and the other components remain in a liquid state (step S15).

  Since the vaporized component f flows out from the outlet 42c of the fuel vaporizer 42 in a gaseous state, it is cooled and liquefied by the cooling means 54 interposed in the flow path 52 (step S16). The cooling means 54 may be selected depending on the distillation characteristics of the vaporized component, and may be either air cooling or water cooling. The liquefied vaporized component f is supplied and stored in the fuel tank 11 or the starting fuel tank 12 by an appropriate method such as gravity or a pump (step S17).

  As described above, in the fuel component separation means of the present invention, the used fuel is supplied to the fuel carburetor only when the exhaust gas temperature is equal to or lower than the fractionation temperature at which the effective component and the other components are separated when starting at a low temperature. The separated effective components at the time of low temperature starting are stored in the starting fuel tank as starting fuel, so that they can be used immediately as necessary.

  In the case of a diesel engine, if the judgment temperature in step S13 is set to 150 ° C. or lower, for example, a fuel mainly composed of normal decane that does not contain ethylbenzene can be used as the starting fuel.

  Next, the operation of the fuel supply device 10 in the above-described embodiment will be described along the flowchart of FIG.

  First, in step S21, the driver rotates the key 24 to turn on the switch. The ECU 28 measures the coolant temperature (step S22), and determines whether the engine is cold starting or normal starting based on the temperature information (step S23). For example, when the water temperature is lower than 10 ° C., it is defined as a low temperature start and when it is 10 ° C. or higher, it is defined as a normal start. When the ECU 28 determines that the water temperature is less than 10 ° C. (YES in step S23), the ECU 28 instructs the fuel switching means 16 having an electromagnetic valve or the like to select the start fuel tank 12 side as the start fuel (step S24). When the ECU 28 selects the fuel supply to the start fuel tank 12 side, the pump 18 sucks up the vaporized component f (liquid component F ′ in the diesel engine) stored in the start fuel tank 12 (step S25). (Step S26).

  Since the vaporized component f (or F ') is injected from the injector 20 as the starting fuel, the engine A starts normally in step S27. In step S28, the ECU 28 determines whether or not the engine A has started normally. Whether the engine has started normally can be determined from the engine speed. If it is determined that the engine has started normally (YES in step 28), the ECU 28 proceeds to step S29, where the fuel switching means 16 selects the fuel tank 11 side and the normal fuel F is injected through the fuel pump 18 into the injector. (Step S30).

  If it is determined in step 23 that the temperature of the cooling water is 10 ° C. or higher, the ECU 28 selects the fuel tank 11 side of the fuel switching means 16 and sends the normal fuel F to the injector 20 via the fuel pump 18. Supply (step S30).

  As described above, according to the fuel supply apparatus of the present invention, normal butane and / or isopentane, which are low-boiling components, are mainly used in gasoline engines, and normal decane, which is mainly low ignition point components, are used as starting fuels in diesel engines. Can be used as Accordingly, various troubles occurring in the engine at the time of starting the internal combustion engine, particularly at a low temperature start can be solved.

  In addition, the fuel supply apparatus of the present invention performs distillation separation using exhaust heat with a fuel vaporizer interposed in an exhaust system, so that the component separation efficiency is high and energy saving.

  The fuel supply device of the present invention is not limited to the above-described embodiment, and may be changed without departing from the gist of the present invention.

  For example, in the above embodiment, the gasoline engine has been described as a direct injection type. However, in a conventional gasoline engine or a supercharged gasoline engine, the fuel after passing through the switching means fuel 16 may be supplied to the intake port.

  Further, the fuel vaporizer is not limited to the shape shown in FIG. 4, and any fuel vaporizer may be used as long as the fuel can be distilled and separated using the exhaust heat. For example, the fin portion 46 may be provided in a spiral shape on the outer periphery of the exhaust pipe, or each fin may be provided with irregularities to increase the surface area.

  The present invention is suitable as a fuel supply device for a gasoline engine or a diesel engine of a vehicle. This is particularly effective when starting a winter engine in a cold region. By using the fuel supply device of the present invention, high-concentration hydrocarbons are discharged from a gasoline engine at the low-temperature start, fuel consumption is reduced, ignition delay of a diesel engine, etc. The problem can be solved.

It is explanatory drawing explaining the system outline | summary of embodiment, and shows the case of a direct injection type gasoline engine. It is a schematic diagram which shows the structure of the component separation means in a gasoline engine. It is a schematic diagram which shows the structure of the component separation means in a diesel engine. It is a schematic diagram explaining an example of a fuel vaporizer. (A) is an axial direction cross section, (b) shows the X-X 'cross section of (a). It is a flowchart explaining the operation | movement which vaporizes and separates a use fuel with a fuel vaporizer. It is a flowchart explaining the action | operation of the fuel supply apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11: Fuel tank 12: Fuel tank for starting 14: Fuel component separation means 16: Fuel switching means 18: Fuel pump 20: Injector 28: ECU 42: Fuel vaporizer 44: Exhaust pipe 46: Fin part 48: Shell 50: Fuel valve 54: Cooling means 58: Temperature measuring device A: Engine E: Exhaust gas F: Fuel used F ': Liquid component (high ignition point component or high boiling point component) f: Vaporization component (low ignition point component or low boiling point component) )

Claims (8)

A fuel supply device for supplying fuel to an internal combustion engine,
Fuel component separation means for distilling and separating low ignition point components or low boiling point components in the fuel, and fuel switching means for selectively switching the fuel supplied to the internal combustion engine,
A fuel supply apparatus that supplies the low ignition point component or the low boiling point component as fuel when the internal combustion engine is started at a low temperature.   The fuel supply apparatus according to claim 1, wherein the fuel component separation unit includes a fuel carburetor interposed in an exhaust path of the internal combustion engine.   The fuel carburetor includes a fin portion standing on an outer peripheral surface of an exhaust pipe of the exhaust path, and a shell body that accommodates the fin portion and is formed coaxially with the exhaust pipe, and exhausts the fuel. The fuel supply device according to claim 1, wherein the fuel supply device is separated into a gas component and a liquid component by heat.   The fuel supply device according to claim 1, wherein the internal combustion engine is a diesel engine.   The fuel supply apparatus according to claim 7, wherein the low ignition point component is normal decane in light oil.   The fuel supply device according to claim 1, wherein the internal combustion engine is a gasoline engine.   The fuel supply apparatus according to claim 6, wherein the internal combustion engine is a direct injection gasoline engine that sprays the fuel directly into a cylinder.   The fuel supply apparatus according to claim 6 or 7, wherein the low boiling point component is mainly normal butane and / or isopentane in gasoline.

Images