JPS636436Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a fuel evaporation control and bubble generation prevention device for preventing fuel evaporation and bubble generation in a carburetor.

Conventionally, in order to prevent the fuel evaporative gas generated in the float chamber of the carburetor from being directly released into the atmosphere, and to remove the bubbles generated in the float chamber when the engine becomes hot, a fuel evaporation control system as shown in Figure 1 was used. Bubble prevention devices have been put into practical use.

A device P installed in the upper part of the float chamber A prevents fuel evaporative gas from being directly released into the atmosphere, and is connected to a flow path leading to the float chamber A by an electromagnetic valve 2 consisting of a valve body 2a and a solenoid 2b. 3 and 4
When the engine is stopped, the valve body 2a (solid line) closes the flow path 4, so the fuel vapor gas passes through the flow path 3 and is adsorbed by the activated carbon 6 of the canister 5 shown in FIG. 2, and is filtered. The released air is now being released into the atmosphere. Furthermore, when the engine is rotating, the valve body 2a (broken line) closes the flow path 3, so
The fuel evaporative gas is led to the engine from the downstream side of an air cleaner (not shown) through the flow path 4 and is combusted. Further, a device Q for removing air bubbles generated in the float chamber A when the engine becomes high temperature is located in another location, and operates a negative pressure valve 7 consisting of a valve body 7c protruding from a diaphragm 7b pressed by a spring 7a. It's decorated. This device Q connects the negative pressure of the intake manifold (not shown) to the flow path 8.
When the engine becomes hot due to the negative pressure valve 7
The canister 5 and the float chamber A are communicated with the valve body 7c at the position shown by the solid line, and air bubbles are removed by taking atmospheric air into the float chamber A from the canister 5 and ventilating it.

However, since the fuel evaporation control and bubble generation prevention device uses the electromagnetic valve 2, it is expensive, and since the negative pressure valve 7 is independent, there is a drawback that the piping between each device is complicated.

By the way, neither the "carburetor with fuel evaporation prevention device" disclosed in Japanese Utility Model Publication No. 47-42721 nor the "carburetor starting aid device" disclosed in Japanese Patent Application Laid-open No. 51-12027 has a bubble generation prevention function. It is.

Therefore, the object of the present invention is to improve the above-mentioned conventional drawbacks, and to provide a device for controlling fuel evaporation and preventing bubble generation from the float chamber, which has simple piping and is low in cost. By integrating a device that prevents fuel evaporative gas from being released into the atmosphere and a device that removes air bubbles that occur in the float chamber at high temperatures, we eliminate the need for complicated piping, and we also eliminate the need for solenoid valves to improve the intake manifold. This is achieved by using two sets of negative pressure valves that utilize the negative pressure of the device, and each having the same function as the conventional device.

The present invention will be explained below using the drawings.

FIG. 3 shows an embodiment of the present invention, and this figure shows the state of the device of the present invention when the engine is stopped.

A small room B is connected to the upper part of the float room A.
and C are provided next to each other, and the small rooms B and C are communicated through a hole 17 provided in a partition wall 15. The small chamber B is provided with an air passage 9 communicating with the downstream side of an air cleaner (not shown), and this passage 9 is connected to a valve body protruding from a diaphragm 10b pressed by a relatively weak spring 10a. It is closed at 10c. On the other hand, an air passage 11 communicating with the canister 5 is arranged in the small chamber C, and a valve body 12c is provided inside the chamber C, and a valve body 12c is protruded from a diaphragm 12b pressed by a spring 12a stronger than the spring 10a.
A valve seat 13 having a communication hole 18 that can be closed by the valve body 12c is provided between the valve body 12c and the diaphragm 12b. A diaphragm chamber D surrounded by diaphragms 10b and 12b communicates with an intake manifold (not shown) through a flow path 14.

When the engine is stopped and in the state shown in Figure 3, the fuel evaporates in the float chamber A.
HC is connected to the activated carbon part 6 of the canister 5 from the flow path 11.
Since the filtered air is absorbed by the air, only filtered air is exhausted to the outside.

Next, Fig. 4 shows the state when the engine rotates and the rotation is not very high.At this time, because the opening degree of the throttle valve 16 is small, the negative pressure downstream of it becomes high, and The negative pressure at D also increases, and the diaphragms 10b and 12b are strongly attracted to the inside, and as a result, the valve body 10c communicates the flow path 9 with the float chamber A, and the valve body 12c closely contacts the valve seat 13 to close the flow path. 11 is closed. In this state, the fuel vapor evaporated in the float chamber A flows through the flow path 9.
The air is taken into the engine from the downstream side of the air cleaner 1 through the air cleaner 1.

FIG. 5 is a diagram showing the state of the device of the present invention when the engine speed is high. In this state, the amount of air taken into the air cleaner 1 is large, but since the throttle valve 16 is open, the negative pressure downstream thereof is low, and therefore the negative pressure in the diaphragm chamber D is also low.
In the device of the present invention, the spring 10a is a weak spring that contracts even when the negative pressure is low, and the spring 12a is a strong spring that does not contract unless the negative pressure becomes high. The valve element 12c is pulled by the diaphragm 12b, but does not close the flow path 11, and communicates the flow path 9 with the float chamber A. As a result, the canister 5 and the downstream side of the air cleaner 1 communicate with each other, and atmospheric air is taken in from the canister 5 by the negative pressure on the downstream side of the air cleaner 1, ventilating the float chamber A and generating bubbles from the fuel in the float chamber A. At the same time, when the engine is stopped, the fuel evaporates from the float chamber A and has been adsorbed on the activated carbon 6 of the canister 5, and is separated from the activated carbon 6 by the atmosphere and guided to the engine where it is burned.

As explained above, the present invention provides two chambers above the float chamber of a carburetor that communicate with the float chamber and are separated by a partition wall with a communication hole, and springs on both sides of the partition wall. energized,
A diaphragm is provided to form a chamber communicating with the intake manifold, one diaphragm is provided with a valve that opens and closes a flow path communicating with the downstream side of the air cleaner, and the other diaphragm is installed in the chamber communicating with the canister. This device is equipped with a valve to open and close the communication hole, which prevents the fuel evaporative gas generated in the float chamber, which was previously separated, from being released directly into the atmosphere, and the air bubbles that occur in the float chamber when the engine becomes hot. By integrating the device with the device for removing the water and forming it in the upper part of the float chamber, it is possible to eliminate the complicated piping between each device, which has the advantage of reducing the man-hours required for piping and reducing costs. Since the solenoid valve can be eliminated and replaced with a negative pressure valve that performs the same function, the cost is further reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional fuel evaporation control and bubble generation prevention device. Figure 2 is a sectional view of the canister, Figure 3 is a sectional view of the fuel evaporation control and bubble generation prevention device of the present invention when the engine is stopped, and Figure 4 is a sectional view of the device of the present invention when the engine speed is low. FIG. 5 is a schematic sectional view showing the operation of each part of the device of the present invention when the engine speed is high. 1... Air cleaner, 2... Solenoid valve, 5... Canister, 7... Negative pressure valve, 10a... Spring, 10b... Diaphragm, 10c... Valve body,
12a... Spring, 12b... Diaphragm, 12c... Valve body, 13... Valve seat, 15... Partition wall, A... Float chamber, D... Diaphragm chamber.

Claims (1)

[Scope of utility model registration request] Two chambers are provided above the float chamber of the carburetor, communicating with the float chamber and separated by a partition wall having a communication hole, biased by springs on both sides of the partition wall, and communicating with the intake manifold. One diaphragm is provided with a valve that opens and closes a flow path communicating with the downstream side of the air cleaner, and the other diaphragm is provided with a valve that opens and closes a flow path communicating with the downstream side of the air cleaner.
A valve is installed to open and close the communication hole installed in the room communicating with the canister, and when the engine is stopped or operating under low to medium load, one of the valves is opened to vent gas from the float chamber, and during high load operation, both valves are opened. A fuel evaporation control and bubble generation prevention device that opens the valve to prevent bubbles from forming inside the float chamber.