JPS6257823B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solenoid valve for controlling the air-fuel ratio of an electronically controlled carburetor used in a gasoline engine, and particularly to an integrated solenoid valve that controls fuel and air simultaneously.

The air-fuel ratio control solenoid valve of an electronically controlled carburetor is installed in the float chamber to cool the coil, but the structure of the solenoid valve is therefore subject to various restrictions and is inevitably elongated. Therefore, when the plunger moves up and down inside the bobbin repeatedly,
The fuel existing in the gap is gradually pushed upwards, and the oil level rises due to capillary action, causing the fuel to rise to the intake air amount control section directly below the slow air bleed, allowing the original air-fuel ratio control function to function. It had the disadvantage of confusing the

FIG. 1 is a sectional view of a main part of a carburetor equipped with a conventional air-fuel ratio control solenoid valve. slow air bleed 1
The body 9, which houses the plunger 2 by attaching it to the upper end thereof, is vertically attached to the lid of the float chamber of the carburetor, and communicates with an air passage 15 through a hole 13 formed in the side surface of the body 9. The lower part of the plunger 2 is inserted into the flange portion of the bobbin 4, and a rod 5 to which a valve 6 is fixed is connected to its lower end.
Further, the core 11 surrounding the lower part of the plunger 2 and the rod 5 is surrounded by the coil 3.
is housed in a yoke 10 that is integrated with the body 9. Further, this yoke 10 is vertically installed in the float chamber with a core 11 that forms a fuel inlet fixed to the lower part thereof, and a member facing the valve 6 and forming the main jet 8 is fixed to the lower part of the core 11. A coiled spring 7 is interposed between the main jet 8 and the valve 6, and the chamber housing the spring 7 opens below the oil level 14 of the float chamber.

The operation of the air-fuel ratio control solenoid valve configured as described above will be described next. When current flows through the coil 3, the plunger 2 moves down a distance of _l1 , closes the main jet 8 with the valve 6, and opens the slow air bleed 1, and when no current flows through the coil 3, the plunger 2 moves down the distance l 1 and closes the main jet 8 with the valve 6. The valve 6 is pushed up to open the main jet 8 and close the slow air bleed 1. Therefore, if a current is periodically applied to the coil 3 and the current application time ratio is changed, the amount of air supplied to the air passage 15 where the internal combustion engine's suction negative pressure is acting, and the amount of air supplied from the main jet 8 to the internal combustion engine. The amount of fuel supplied will be adjusted.

In the above operation, plunger 2 and rod 5
Guide 12 and bobbin 4 through a gap of 0.1~0.2mm
When the core 11 reciprocates while being guided by the inner diameter surface of the core 11, the fuel existing in the gap between them is gradually pushed upward, and the oil level rises due to capillary action, causing the fuel to flow directly under the slow air bleed 1. It starts to accumulate. When this happens, fuel is mixed with the air taken in from the slow air bleed 1 and sent into the intake passage through the hole 13 and the air passage 15, thereby enriching the low-speed air-fuel mixture. Therefore, there have been disadvantages in that the rotation of the internal combustion engine becomes unsmooth, the exhaust gas composition deteriorates, and fuel is wasted.

An object of the present invention is to provide a solenoid valve for controlling the air-fuel ratio of an electronically controlled carburetor, which can suppress the enrichment of the air-fuel mixture supplied to an internal combustion engine, which is a drawback of the prior art, with a relatively simple structural change. The main feature is that the ratio of the energization time to the energization time for the coil wound around the outer circumference of the bobbin that movably stores the plunger is changed, and the opening time of the main jet is adjusted at the bottom of the plunger. , the upper part is a solenoid valve for controlling the air-fuel ratio of an electronically controlled carburetor that simultaneously controls the amount of fuel and air supplied to the internal combustion engine by adjusting the opening time of the air bleed, and the lower end of the bobbin is connected to the float chamber. in which the plunger is immersed in the fuel and the upper part thereof communicates with the air passage downstream of the air bleed, and an annular cavity is provided on the outer periphery of the plunger that moves within the bobbin to block movement of fuel due to capillary action. It's about becoming.

FIG. 2 is a sectional view of a main part of an air-fuel ratio control solenoid valve according to an embodiment of the present invention. The difference from FIG. 1 is that a narrow diameter portion 16 is formed in the middle portion of the plunger 2. In this way, even if the capillary phenomenon is added to the rise of fuel due to the reciprocating motion of the plunger 2 and the oil level of the fuel rises to the narrow diameter portion 16 of the plunger 2,
The guide 12 stays within the narrow diameter portion 16 and moves beyond it.
It does not reach that part. Therefore, an amount of air proportional to the duty-controlled operation of the plunger 2 can be supplied to the air passage 15 to perform suitable operation. Note that the narrow diameter portion 16 is formed above the oil level 14 in FIG.

FIG. 3 is a cross-sectional view of a main part of an air-fuel ratio control solenoid valve which is a modification of FIG. 2, in which a large diameter hole 17 is provided in the flange of the bobbin 4. Therefore,
Even if the fuel rises through the gap between the bobbin 4 and the plunger 2, it remains at the large diameter hole 17 and does not rise beyond it, producing exactly the same effect as in the case of Fig. 2. Demonstrate. Note that the large diameter hole 17 is the second
It is formed above the oil level 14 in the figure.

Figure 4 is a diagram comparing the characteristics of solenoid valves for air-fuel ratio control. Time is shown, and the vertical axis is CO in exhaust gas.
The content is shown in %. The conventional first method shown by the broken line
In the case of the electronically controlled carburetor shown in the figure, the amount of CO in the exhaust gas rises to about 5% about 10 minutes after startup. This means that by repeating the up and down movement of the plunger 2, the oil level in the bobbin 4 will rise to the hole 13.
This indicates that the fuel is mixed into the bleed air supplied from the low-speed fuel system, enriching the air-fuel mixture introduced into the internal combustion engine and deteriorating its exhaust gas composition.

However, in the case of FIGS. 2 and 3, the mixture does not become enriched due to the presence of the small diameter part 16 of the plunger 2 and the large diameter hole 17 of the bobbin 4, so even if the operation is continued for a long time, the solid line remains unchanged. As shown in , CO in the exhaust gas
It remains at the optimum level of 2.5%. This indicates that the small diameter portion 16 or the large diameter hole 17 is working effectively to suppress the rise in the oil level.

The air-fuel ratio control solenoid valve of this embodiment has an annular space formed in the plunger accommodating portion above the oil level in the float chamber, so that the oil inside the solenoid valve is controlled by the upper and lower parts of the plunger and by capillary action. This has the effect of preventing an increase in air pressure and constantly supplying a suitable air-fuel mixture to the internal combustion engine.

FIG. 5 is a cross-sectional view of a main part of an air-fuel ratio control solenoid valve that is a modification of FIG. , 18b, 18c are provided, and the upper holes 18a, 18b are provided above the oil level 14 of the float chamber. Further, a narrow diameter portion 16 is provided in the middle portion of the plunger 2. In this way, the fuel that has risen above and below the rod 5 and due to capillary action enters the bobbin 4 through the holes 18a and 18b, flows down inside the coil 3 due to gravity, and enters the rod 5.
and flows out into the gap between the core 11. This has the advantage of reducing the amount of fuel rising to the narrow diameter portion 16 and completely preventing enrichment of the air-fuel mixture, as well as cooling the coil 3 using the rising fuel.

The air-fuel ratio control solenoid valve of this embodiment has holes in the core surrounding the rod and above and below the bobbin, so that the rising fuel touches the coil and flows down, and is used for cooling the coil. The effect is that the amount of fuel increase can be reduced.

In the above embodiment, if the flange portion of the bobbin 4 is provided with a large diameter hole 17 as shown in FIG. 3, and the plunger 2 is also provided with a small diameter portion 16 as shown in FIG. can be more completely prevented.

The solenoid valve for controlling the air-fuel ratio of an electronically controlled carburetor of the present invention always keeps the air-fuel ratio of the air-fuel mixture supplied to the internal combustion engine in a suitable state through simple improvements, achieving smooth operation and purification of the exhaust gas composition. It has the effect of being

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a carburetor equipped with a conventional solenoid valve for controlling an air-fuel ratio, and FIGS. 2 and 3 are sectional views of a main part of a solenoid valve for controlling an air-fuel ratio according to an embodiment of the present invention. FIG. 4 is a diagram comparing and showing the characteristics of the air-fuel ratio control solenoid valve, and FIG. 5 is a sectional view of the main part of the air-fuel ratio control solenoid valve which is a modification of FIG. 2. 1... Slow air bleed, 2... Plunger, 3... Coil, 4... Bobbin, 5... Rod, 6... Valve, 7... Spring, 8... Main jet, 9... Body, 10... Yoke, 11... Core, 12... Guide, 13, 18... Hole, 14...
...Oil level in the float chamber, 15...Air passage, 16...
...Small diameter part, 17...Large diameter hole.

Claims (1)

[Scope of Claims] 1. The ratio of the energization time and the energization time to the coil wound around the outer periphery of the bobbin that movably stores the plunger is changed, and the opening time of the main jet is adjusted in the lower part of the plunger, and the opening time of the main jet is adjusted in the upper part. This is a solenoid valve for controlling the air-fuel ratio of an electronically controlled carburetor that simultaneously controls the amount of fuel and air supplied to the internal combustion engine by adjusting the opening time of the air bleed. An annular cavity is provided on the outer periphery of the plunger that moves within the bobbin to block the movement of fuel due to capillary action. A solenoid valve for controlling an air-fuel ratio of an electronically controlled carburetor. 2. The solenoid valve for air-fuel ratio control of an electronically controlled carburetor according to claim 1, wherein the annular space is an annular groove provided on the plunger side. 3. The air-fuel ratio control solenoid valve for an electronically controlled carburetor according to claim 1, wherein the annular space is an annular groove provided on the bobbin side facing the plunger.