JPS6314050Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overflow device for a carburetor float chamber that controls the liquid level of fuel replenished from a fuel tank.

An engine carburetor is provided with a float chamber that serves as a fuel reservoir connected to the nozzle and maintains a constant liquid level. That is, as shown in FIG. 1, a float chamber 1 is supplied with fuel from a fuel tank via an on-off valve 2, and this on-off valve 2 is controlled by the vertical displacement of a float 3 provided within the chamber. float 3
When the float 3 rises, the on-off valve 2 is closed and refueling is stopped, so that the liquid level at which the float 3 is located at the closed position is maintained. This stabilizes the control of the fuel supplied from the nozzle 4. In the figure, 5 indicates an air supply passage, 6 indicates a throttle valve, and 7 indicates a variable bench lily.

However, in motorcycles and other vehicles, when the float 3 jumps due to its impulsive vertical movement and opens the on-off valve 2 unnecessarily, the liquid level may rise abnormally, causing the intake air-fuel mixture to become rich. This will cause engine trouble. Therefore, an overflow device is provided to deal with such an abnormal rise in the liquid level. The simplest method is to pass an overflow pipe 8 whose lower end is open to the atmosphere from the bottom 9 of the chamber and position the overflow port 10 at the upper end at a desired height above the liquid level, as shown in the figure. It is used. Further, in order to maintain the internal pressure of the float chamber 1 at atmospheric pressure, an out vent pipe 11 whose upper end is open to the atmosphere is provided with the lower end thereof opened in the upper part of the chamber.

By the way, the fuel evaporated in the float chamber 1 is
It is released from the out vent pipe 11 and overflow pipe 8 which are open to the atmosphere. The amount of evaporated fuel discharged from the out vent pipe 11 is extremely small and not a problem due to its cross-sectional area. However, the amount released from the overflow pipe 8 reaches the majority of the amount of evaporation in the float chamber 1, even though the cross-sectional area is not much different, resulting in pollution problems.
It is so large that it becomes a problem in terms of energy saving. This is because when the fuel vapor that has entered the pipe condenses and liquefies, it flows back into the float chamber 1 through the outvent pipe 11, but flows down through the overflow pipe 8. This is thought to be the result of active suction.

In view of the above problems, the present invention provides an overflow device for a carburetor float chamber that can suppress the emission of evaporated fuel to an extremely small amount without impairing the overflow function.

In other words, the overflow device for the carburetor float chamber according to the present invention has a small chamber that is sealed above the liquid level to the float chamber and is open below the liquid level, and the overflow port at the upper end of the overflow pipe is connected to the liquid in this small chamber. It is characterized by communicating above the surface, and the overflow function remains the same, and only the fuel that evaporates from the small area inside the chamber is dissipated into the atmosphere from the overflow pipe, so the amount of fuel is reduced compared to conventional ones. It can be drastically reduced.

Some embodiments of the device of the present invention will be illustrated and explained below.

In FIGS. 2 and 3, a separate vertically long chamber 13 is formed across the side wall 12 of the float chamber, and both chambers 1 and 13 are communicated through a through hole 14 provided in the side chamber 12 below the liquid level. 15 is an out vent hole provided at the top of the separate chamber 13 and open to the atmosphere. The overflow pipe 8 is inserted into this separate chamber 13. The liquid level in the separate chamber 13 is maintained at the same level as the float chamber 1, and the overflow port 10 is located above it.

With the above configuration, the separate chamber 13 acts as a part of the float chamber 1 below the liquid level, and performs the overflow function without any problem when the liquid level rises. However, since the separate chamber 13 above the liquid level exists independently,
Only the fuel evaporated on the liquid level in the separate chamber 13 is released from the overflow pipe 8. Since the area of the separate chamber 13 is small, the amount of fuel that evaporates is small, and therefore the amount that is dissipated is also small. The evaporated fuel in the float chamber 1 is released from the out vent pipe 11, but as described above, the amount is extremely small, and the amount released from the out vent hole 15 is also small. Therefore, the release of evaporated fuel, ie, hydrocarbon (HC) components from the carburetor float chamber can be suppressed to an acceptable level. Note that the out vent hole 15 can be omitted by using the overflow pipe 8 that is open to the atmosphere, but the resistance may become large depending on how the end of the overflow pipe 8 is treated. In order to improve the response of lifting and lowering, installing the out vent hole 15 is effective.

FIG. 4 shows another embodiment. In this embodiment, an upward blind hole 17 is provided at a position submerged below the liquid level on the lower surface of the float 3, and the upper end of the overflow pipe 8 is placed in the blind hole 17. Let it happen.

In this case as well, the liquid level communicated by the overflow pipe 8 is limited to a small area range, and the evaporated fuel released from this area is also limited to a small amount.

The overflow device for a carburetor float chamber of the present invention has a small chamber that is sealed above the liquid level to the float chamber and is open below the liquid level, and the upper end of the overflow pipe overflows above the liquid level in this small chamber. Since the opening is connected, the liquid area that can supply evaporated fuel to the overflow pipe is reduced, and the absolute amount of evaporated fuel that radiates from the overflow pipe is suppressed to a small value, which is a special phenomenon of overflow pipes. This is a unique device that has no problem with the overflow function and has a simple structure that can solve the problems of pollution and energy saving that tend to occur in this type of carburetor float chamber.

[Brief explanation of the drawing]

Fig. 1 is a vertical side view illustrating a conventional carburetor, Fig. 2 is a longitudinal side view illustrating an embodiment of the device of the present invention, Fig. 3 is a cross-sectional plan view of Fig. 2, and Fig. 4 is the device of the present invention. FIG. 6 is a vertical cross-sectional side view of a float chamber showing another embodiment of the present invention. 1... Float chamber, 2... On-off valve, 3... Float, 8... Overflow pipe, 10... Overflow port, 11... Out vent pipe, 12... Side wall, 13... Separate room, 14... Through hole, 15...out vent hole, 17...blind hole.

Claims (1)

[Claims for Utility Model Registration] 1. A small chamber provided in a float chamber, which is sealed from the float chamber above the liquid level and opens into the float chamber below the liquid surface, and a small chamber disposed within the small chamber. , with the bottom end open to the atmosphere,
An overflow device for a carburetor float chamber, characterized in that an overflow port at an upper end has an overflow pipe communicating with the liquid level in the small chamber. 2. The overflow device for a carburetor float chamber according to claim 1, which is characterized in that a vertically elongated small chamber is formed along the outer surface of the float chamber. 3. An overflow device for a carburetor float chamber according to claim 1, wherein the small chamber is formed by a blind hole provided in a surface submerged below the liquid level at the bottom of the float member. 4. The overflow device for a carburetor float chamber according to claim 1, which is characterized in that an out vent hole for opening to the atmosphere is provided in the upper part of the small chamber.