JPS6156416B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mixture heating device for an internal combustion engine that heats an engine mixture using recirculated exhaust gas and a heater.

When the engine is cold, the fuel in the intake passage does not vaporize well, and some of it adheres to the inner wall of the intake passage and condenses, creating a wall flow that flows along the inner wall of the intake passage, so the air-fuel mixture entering the cylinder is outside the flammable mixture ratio. This results in a lean mixture. In addition, the engine rotation does not increase smoothly due to increased viscosity of lubricating oil, so the incoming air flow rate is slow, and since there is a lot of heat dissipated from the cylinder wall, a type of vaporization that sucks fuel by the intake air flowing through the bench lily. In the fuel tank, only a small amount of the supplied fuel is vaporized, making it difficult to operate smoothly. Therefore, in order to produce a mixture that can be ignited in the cylinder when the engine is cold, the supplied mixture ratio must be made much richer than during normal operation.
For this reason, a choke valve is installed at the top of the bench lily to change the cross-sectional area of the air flow path, increasing the air flow velocity when the engine is cold and increasing the negative pressure in the bench lily, allowing a larger amount of fuel to flow than during normal operation (when the engine is warm). supplying.

However, in this case, fuel atomization and vaporization promotion are still insufficient, and the mixture ratio is much richer than when the engine is warm, resulting in poor mixture distribution and poor engine stability and combustion stability. Fuel efficiency was worsening, and emissions were also increasing.

Therefore, the heat of the recirculated exhaust gas is used to promote atomization and vaporization of the fuel, but in conventional exhaust gas recirculation systems, the recirculated exhaust gas is intensively discharged from one or two recirculated exhaust jets. Because an attempt was made to distribute fuel and recirculated exhaust gas at the same time within the jet intake manifold, control of fuel distribution and recirculated exhaust gas distribution was not successful, hindering engine stability, and further worsening combustion of the intake air-fuel mixture, resulting in increased fuel consumption. There was a growing problem. In this case, especially when the engine is cold, the temperature of the recirculated exhaust gas decreases due to heat dissipation in the engine, etc. before mixing, which has the disadvantage that the effect of promoting fuel atomization and vaporization is weakened.

The present invention was made in view of the above-mentioned circumstances, and includes a cylindrical heater installed in the intake passage downstream of the carburetor, and an annular exhaust passage provided around it, so that when the engine is cold, the heater warms the engine. After the mixture is heated, the mixture is heated by the recirculated exhaust gas, and the recirculated exhaust gas is uniformly jetted from the periphery of the mixture flow in a direction that intersects with the flow direction of the mixture, thereby controlling the distribution of the recirculated exhaust gas and fuel to each cylinder. To ensure uniformity and stability of combustion,
The aim is to improve both fuel efficiency and drivability.

Hereinafter, the present invention will be explained in detail based on the drawings.

In FIG. 1 showing the first embodiment, there is shown a dual carburetor 5 in which a primary barrel 1 and a secondary barrel 2 are provided with primary and secondary throttle valves 3 and 4, respectively, and a riser portion 6 is equipped with water. An intake manifold 8 heated by engine cooling water in a jacket 7 is connected via an insulator 9 in the same manner as in the conventional case.

At a position above the riser section 6 of the intake manifold 8, a cylindrical electric heater 10 is connected to the downstream side of the primary barrel 1 of the carburetor 5 and is attached to the insulator 9. For example, as shown in FIG. 2, this electric heater 10 includes a mesh heating element 1 based on a ceramic base material having a positive electric resistance characteristic with respect to temperature.
0a is laminated on a cylindrical heater body 10b which has the same inner diameter as the outlet of the primary barrel 1 and is attached to the insulator 9. still,
3 and 4 show another example of the shape of the electric heater.

A cylindrical wall 11 concentric with the heater body 10b is provided on the outside of the electric heater 10, and an annular exhaust passage 12 is formed between the heater body 10b and the cylindrical wall 11. Then, the recirculation exhaust gas introduction port 13 opened in the exhaust passage 12
A part of the exhaust gas taken out from the exhaust passage of the engine (not shown) is sent to the exhaust passage 1 via the exhaust gas recirculation passage 14.
Introduced within 2.

The upper end of the exhaust passage 12, that is, the upstream end of the air mixture flowing inside the heater body 10b, is sealed by the upper end of the cylindrical wall 11 and the heater body 10b, and the lower end, that is, the jetting part 15 of the introduced recirculated exhaust gas, is sealed by the heater body 10b.
It is formed into a slit shape following the lower end. The recirculated exhaust gas inlet 13 and the jetting part 15 are opened from the periphery of the air-fuel mixture flow in a direction that intersects with the flow direction thereof.

The electric heater 10 described above is energized according to the engine temperature and only needs to be operated when the engine is cold, and is wired as shown in FIG. 5, for example. That is, the electric heater 10 is connected to a detection device that detects the engine temperature via the lead wire 16, such as a water jacket 7.
A water temperature switch 17 that detects the engine cooling water temperature inside the engine, a normally open contact 18a of the relay 18, and a key switch 1.
It is connected in series to the battery 20 via 9. Excitation coil 18b of relay 18 is connected in series to alternator 21.

In such a configuration, turning on the key switch 19
When the engine is started, the air-fuel mixture formed by intake air and fuel in the carburetor 5 is guided from the primary barrel 1 through the primary throttle valve 3 and the electric heater 10 to the intake manifold 8. A portion of the fuel adheres to the peripheral wall of the primary barrel 1 and flows down into the electric heater 10 as a wall flow. At this time, that is, when the engine is cold, the exciting coil 18b is activated by the alternator 21.
is energized and the normally open contact 18a of the relay 18 is closed, and since the cooling water temperature has not risen and the water temperature switch 17 is also ON, the battery 2
0 to the electric heater 10. Therefore, the fuel flowing down into the electric heater 10 is heated by the electric heater 10 and atomization or vaporization is promoted, so that the air-fuel mixture distribution in each cylinder of the engine is greatly improved.

Further, by operating the electric heater 10 when the engine is cold, the amount of recirculated exhaust gas during the cold period can also be increased compared to the conventional case. That is, the exhaust gas recirculation passage 14
Conventionally, the recirculated exhaust gas that is introduced into the intake manifold 8 is cooled in the passage 14 and then introduced as it is, which causes deterioration of the air-fuel mixture distribution and exhaust gas recirculation. However, in the case of this embodiment, the recirculated exhaust gas is passed from the exhaust recirculation passage 14 to the recirculated exhaust gas inlet 13.
Once introduced into the exhaust passage 12 around the electric heater 10 through the exhaust passage 12, it is evenly warmed by the electric heater 10 as it passes through this exhaust passage 12, and then the recirculated exhaust gas is passed through a slit-shaped recirculation exhaust provided downstream of the electric heater 10. The air is uniformly ejected from the ejection portion 15 into the intake manifold 8. Therefore, the temperature of the air-fuel mixture does not decrease, and therefore, even if the amount of recirculated exhaust gas is increased compared to the conventional case when the engine is cold, there is no problem in engine operation, and NOx can be reduced by exhaust gas recirculation.

In addition, the direction in which the recirculated exhaust gas is ejected is perpendicular to the flow direction of the air-fuel mixture, and the recirculated exhaust air is ejected uniformly from around the air-fuel mixture flow, which promotes mixing with the air-fuel mixture and at the same time Mixing of air and fuel is also facilitated. As a result, fuel atomization and vaporization are further promoted, and at the same time, the air-fuel mixture distribution and the recirculated exhaust gas distribution are significantly improved compared to the prior art.

When the engine is sufficiently warmed up and the temperature of the cooling water in the water jacket 7 rises, the water temperature switch 17 is opened to cut off the power to the electric heater 10, and the operation of the electric heater 10 is stopped. However, after the engine has warmed up, the recirculated exhaust gas is introduced into the annular exhaust passage 12 without being cooled in the exhaust recirculation passage 14 and the heater main body 10b is heated. You can get the same effect as time.

Incidentally, the recirculated exhaust gas jetting part may be constructed by extending the heater main body 10b of the electric heater 10 downward, as shown in FIG. 6, and providing a large number of small holes 23 around the entire circumference of the extending part. In this case as well, the recirculated exhaust gas is jetted out substantially uniformly from the small holes 23 and mixed uniformly with the air-fuel mixture. Further, the cylindrical wall may be of the spacer type interposed between the insulator 9 and the intake manifold 8 as shown in FIG. 1, or may be formed integrally with the insulator 9 or the intake manifold 8. Furthermore, although the present embodiment has been described using a dual carburetor as an example, the present invention is not limited to this.

As described above, according to the present invention, the recirculated exhaust gas and the electric heater are provided together, and when the engine is cold, the electric heater forcibly vaporizes the fuel flowing as a wall flow, and the recirculated exhaust gas is also heated. Therefore, atomization and vaporization of the fuel are promoted and a good air-fuel mixture can be obtained regardless of the temperature conditions of the engine. In addition, since the recirculated exhaust gas crosses the flow direction of the air-fuel mixture and is ejected evenly from its surroundings, the mixture of fuel and intake air is improved evenly, and the distribution and temperature distribution of the recirculated exhaust air is also uniform. As a result, engine stability and combustion stability are improved, the air-fuel mixture can be made leaner, fuel consumption and emissions can be significantly improved, and drivability is improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention;
Figure 2 is a view of the electric heater in the direction of the arrow in Figure 1, Figures 3 and 4 are diagrams showing another embodiment of the electric heater, Figure 5 is a wiring diagram of the electric heater, and Figure 6 is a separate diagram. FIG. 3 shows a cross-sectional view of the main parts of the embodiment. 5... Carburetor, 8... Intake manifold, 10...
...Electric heater, 11...Cylinder wall, 12...Annular exhaust passage, 13...Recirculation exhaust inlet, 14...Exhaust recirculation passage, 15...Recirculation exhaust jetting part, 17...Water temperature switch.

Claims (1)

[Claims] 1. A cylindrical heater is installed in the intake passage downstream of the carburetor so that the air-fuel mixture flows in the cylinder, and an annular exhaust passage is provided around the outer periphery of the heater to guide a part of the exhaust gas,
The recirculation exhaust jetting part of the exhaust passage is opened from the periphery of the air-fuel mixture flow into the intake passage in a direction crossing the flow direction, and the heater is energized and heated by a detection device that detects the engine temperature when the engine is cold. A mixture heating device for an internal combustion engine, characterized in that it is configured to