JPH05302555A - Air assist fuel supply device - Google Patents

Abstract

PURPOSE:To atomize fuel without lowering down the temperature. CONSTITUTION:A heater is supported with heat insulation on a bypass path 5 through a supporting member, to heat air in the bypass path 5, mix the air of high temperature with fuel, atomize the fuel without decreasing its temperature, promote vaporization of the fuel and to reduce a fuel amount adhering to a wall surface of an intake passage 1. A heater 21 is not provided in the intake passage 1 to eliminate increase of passage resistance of intake air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-assisted fuel supply device which promotes atomization of fuel by air assist.

[0002]

2. Description of the Related Art A fuel is mixed with air and the mixture is injected into an intake system of an internal combustion engine to promote atomization of the fuel. When mixing air with fuel, the air assist fuel supply device shown in FIG. 3 is used.

FIG. 3 shows a schematic structure of a conventional air-assisted fuel supply device.

An injector 2 is provided in the intake passage 1, and fuel is sent to the injector 2 from a fuel tank 3. The bypass passage 5 connects the upstream side of the throttle valve 4 and the ejection port 11 of the injector 2, and the fuel from the injector 2 and the air from the bypass passage 5 are mixed with each other to supply the air-fuel mixture from the intake passage 1 to the combustion chamber 6. To be done. 7 in the figure
Is an intake valve.

FIG. 4 shows the detailed structure of the tip of the injector 2. The bypass passage 5 communicates with a portion of the injection port 11 of the injector 2, and the fuel and air are mixed in the mixing passage 12 and supplied from the intake passage 1 to the combustion chamber 6.

In the air-assisted fuel supply device described above,
The fuel ejected from the ejection port 11 of the injector 2 is mixed with the air from the bypass passage 5, and this air-fuel mixture is mixed with the intake passage 1
The fuel is atomized (30
μm). The atomization of the fuel promotes the evaporation of the fuel to reduce the amount of the fuel adhering to the wall surface of the intake passage 1, thereby improving the fuel efficiency and the exhaust gas performance.

[0007]

In the conventional air-assisted fuel supply device, air is mixed with fuel to atomize the fuel. However, while atomizing the fuel to facilitate heat transfer,
Since the temperature of the air itself is low, the evaporation is not sufficient and the fuel adheres to the inner wall of the intake passage 1.

Further, it is considered that a heating device for heating air, fuel or air-fuel mixture is provided in the intake system to promote evaporation of fuel. However, in this case, since the heating device is installed in the intake passage, the passage resistance increases and the full-open performance deteriorates. Further, the particle size of the fuel injected from the injector was about 200 μm, the heat transfer was slow even when heated, and the amount of heat could not be effectively used for the evaporation of the fuel.

[0009]

The structure of the present invention for solving the above-mentioned problems includes a fuel injection device for injecting fuel toward a combustion chamber, and an intake air downstream of a fuel injection outlet of the fuel injection device. In the air-assisted fuel supply device including a bypass passage for feeding a portion, a heating device for heating air is provided in the bypass passage.

[0010]

Function: The air in the bypass passage is heated and the high temperature air is mixed with the fuel to atomize the fuel without lowering the temperature of the fuel. Since there is no heating device in the main intake passage, there is no influence on the intake passage resistance.

[0011]

1 shows a schematic structure of an air-assisted fuel supply system according to an embodiment of the present invention, and FIG. 2 shows a cross section of a bypass passage representing a heating system. The same members as those shown in FIG. 3 are designated by the same reference numerals, and duplicate description will be omitted.

As shown in FIG. 1, the bypass passage 5 near the jet port 11 of the injector 2 is provided with a heating device 21 for heating the air sent from the bypass passage 5.

As shown in FIG. 2, the heating device 21 comprises a heater 22 made of ceramics, and a support member 23 that supports the heater 22 on the inner wall of the bypass passage 5 and insulates the heater 22 and the bypass passage 5. ing.

The air sent from the bypass passage 5 to the vicinity of the jet port 11 of the injector 2 is heated by the heater 22,
It is mixed with fuel injected from the injector 2. The fuel of the air-fuel mixture is atomized (about 30 μm) and the air around the fuel becomes hot. Since the fuel is atomized, the fuel evaporation rate is increased and the particle size is immediately reduced, and the fuel floats in the air and is unlikely to adhere to the inner wall surface of the intake passage 1. Further, since the heating device 21 is not provided in the intake passage 1, the intake passage resistance does not increase.

In the air-assisted fuel supply device described above, the air in the bypass 5 is heated by the heater 22 and the high temperature air is mixed with the fuel, so that the fuel can be atomized without lowering the temperature of the fuel. it can. Therefore, the heat transfer of the fuel is accelerated, the evaporation rate of the fuel is increased, and the amount of fuel adhering to the inner wall surface of the intake passage 1 is reduced. Further, since the heater 22 is adiabatically supported by the bypass passage 5 by the support member 23, the heat of the heater 22 and the bypass passage 5 are not insulated and the heat of the heater 22 is not taken to the bypass passage 5,
The air can be heated efficiently. In addition, the intake passage 1
Since the heater 22 does not exist in the valve, the intake passage resistance does not increase, and the full-open performance is not impaired.

[0016]

The air-assisted fuel supply device of the present invention is provided with a heating device in the bypass passage, heats the air in the bypass passage, mixes high temperature air with the fuel, and atomizes the fuel without lowering the temperature of the fuel. Can be converted. As a result,
The evaporation of fuel is promoted, the amount of fuel adhering to the wall surface of the intake passage is reduced, the controllability of the A / F during the transition is improved, and the drivability and the exhaust gas performance are improved. In addition, the amount of corrected fuel during the transition is small, and the fuel consumption can be improved. Further, since less fuel adheres to the wall surface of the intake passage, the exhaust gas performance during deceleration is also improved. Furthermore, since the heating device is not provided in the intake passage, the intake passage resistance does not increase and the full-open performance is not impaired.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an air-assisted fuel supply device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a bypass path representing a heating device.

FIG. 3 is a schematic configuration diagram of a conventional air-assisted fuel supply device.

FIG. 4 is a detailed structural diagram of a tip portion of an injector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Intake passage 2 Injector 5 Bypass passage 21 Heating device 22 Heater 23 Support member

Claims (2)

[Claims] 1. An air-assisted fuel supply device comprising: a fuel injection device for injecting fuel toward a combustion chamber; and a bypass passage for sending a part of intake air to a downstream side of a fuel injection outlet of the fuel injection device, An air-assisted fuel supply device, characterized in that a heating device for heating air is provided in the bypass passage. 2. The air-assisted fuel supply device according to claim 1, wherein the heating device thermally supports the heater between the inner wall of the bypass passage and the heater.