JPH032697Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention adsorbs the evaporated fuel generated in the fuel tank and vaporizer, temporarily holds it, and then uses the negative pressure in the intake system to transfer the temporarily held evaporated fuel to the intake system during engine operation. This invention relates to an evaporated fuel adsorption device installed for the purpose of releasing the fuel and combusting it together with the air-fuel mixture.

This type of fuel vapor adsorption device is designed to have a first fuel vapor adsorption box (a) that communicates with the fuel tank and a second fuel vapor adsorption box (b) that communicates with the float chamber of the vaporizer, in order to improve restartability under high temperatures. The device installed in the
It is published in the issue (Figure 1). However, in this prior art, check valves c and d are arranged in each suction box a and b, so if the set values of the opening pressures of these check valves c and d are not the same, the intake system Only one check valve opens in response to negative pressure, and the evaporated fuel is released from only one adsorption box to the intake system, while the evaporated fuel temporarily retained in the other adsorption box is not released to the intake system.
This causes problems such as leakage into the atmosphere and a decrease in adsorption power of evaporated fuel, which impairs restartability. Since it is not easy to accurately set the opening pressures of the check valves c and d, the above problem has to be solved as a real problem.

The present invention aims to solve the problems of the above-mentioned prior art and to simplify the structure.
1 at the confluence of the purge passage of the first evaporated fuel adsorption box and the purge passage of the second evaporated fuel adsorption box.
A fuel vapor adsorption device is constructed by disposing two check valves and a throttle at an intermediate position between the float chamber and the check valve in the purge passage of the second vapor fuel adsorption box. do.

In the embodiment of the present invention shown in FIG. 2, 1 is a first vaporized fuel adsorption box (hereinafter referred to as the first adsorption box) communicating with a fuel tank 2, and 3 is a vaporizer 4.
a second vaporized fuel adsorption box (hereinafter referred to as the second adsorption box) communicating with the float chamber 5;
It is preferable that these are constructed of a carbon canister having activated carbon layers 6 and 7 therein for adsorbing evaporated fuel.

Both the first suction box 1 and the second suction box 3 are vertically divided into three parts, and have upper spaces 8, 9, activated carbon layers 6, 7, and lower spaces 10, 11. Each of the lower spaces 10 and 11 communicates with the atmosphere through atmosphere opening pipes 12 and 13.

The activated carbon layer 6 of the first adsorption box 1 and the fuel tank 2 are communicated through an evaporated fuel supply pipe 14, and the evaporated fuel generated in the fuel tank 2 flows into the activated carbon layer 6 through the supply pipe 14. , is adsorbed here. Also, the first suction box 1 is located in the upper space 8.
A purge chamber 16 defined by partition walls 15 is provided therein. This purge chamber 16 is connected to the upper space 8 via a discharge port 17 and to the second space via a communication pipe 18.
They communicate with the upper space 9 of the adsorption box 3, and also communicate with the vaporized fuel discharge pipe 20 via the check valve 19.
is connected to.

The activated carbon layer 7 of the second adsorption box 3 and the float chamber 5 are communicated with each other through an outer vent 21, and the evaporated fuel generated in the float chamber 5 passes through the outer vent 21 to the activated carbon layer 5.
, where it is adsorbed.

The vaporized fuel discharge pipe 20 is connected to a purge port 22 provided in the vaporizer 4. Thus, when negative pressure is generated in the intake system during engine operation, the check valve 19 opens, and the evaporated fuel adsorbed on the activated carbon layer 6 of the first adsorption box 1 is transferred to the atmosphere opening pipe 12.
The evaporated fuel is discharged from the purge port 22 into the intake system through the upper space 8, the discharge port 17, the purge chamber 16, the check valve 19, and the evaporated fuel discharge pipe 20 together with the outside air taken in from the evaporated fuel. At the same time, the vaporized fuel adsorbed on the activated carbon layer 7 of the second adsorption box 1
Together with the outside air taken in from the upper space 9, the discharge port 23 of the second adsorption box 3, the communication pipe 18, the purge chamber 16, the check valve 19, the evaporated fuel discharge pipe 20, and the purge port 22 to the intake system. is released.

Since the evaporated fuel generated in the float chamber 5 is smaller than the evaporated fuel generated in the fuel tank 2, a throttle 24 is provided in the communication pipe 18 to
A difference is provided between the negative pressures acting on the suction box 1 and the second suction box 3.

In addition, in Fig. 2, 25 is a ventilly, 26
is the throttle valve. Further, the purge chamber 16 and check valve 19 may be provided outside the first suction box 1.

As shown in the above embodiment, the present invention has a purge passage A of the first adsorption box 1 (in the above embodiment, the discharge port 17, the purge chamber 16, and the evaporated fuel discharge pipe 20 correspond to this) and the second adsorption box 1. One check valve 19 is arranged at the confluence C of the box 3 with the purge passage B (in the above embodiment, this corresponds to the discharge port 23, the communication pipe 18, the purge chamber 16, and the evaporated fuel discharge pipe 20). However, it goes without saying that the embodiments are not limited to those shown in the above embodiments.

For example, as shown in FIG.
The check valve 19 is installed at the junction of the second pipe 28 connected to the discharge port 23 of the second suction box 3.
The fuel vapor discharge pipe 20 may be connected to the check valve 19. In this case, the purge passage A of the first adsorption box 1 is composed of the discharge port 17, the first pipe 27, and the evaporated fuel discharge pipe 20, and the purge passage A of the first adsorption box 1
The purge passage B includes the discharge port 23 and the second pipe 2.
8. It goes without saying that the evaporated fuel discharge pipe 20 corresponds to the junction part C. The arrangement of the throttle 24 in the second pipe 28 is the same as in the embodiment shown in FIG.

Since the present invention has the above configuration, it can produce the following effects.

Since the two evaporated fuel adsorption boxes have a common check valve, when the check valve opens due to the negative pressure in the intake system, the evaporated fuel adsorbed in each evaporated fuel adsorption box is removed. Fuel is reliably discharged into the intake system through the respective purge passages. Therefore, it is possible to solve the problem seen in the prior art, that is, one check valve may not open and the evaporated fuel adsorbed in one evaporated fuel adsorption box may not be released into the intake system.

While the prior art required two check valves, the present invention requires only one check valve, simplifying the structure and reducing costs.

According to the present invention, a throttle is disposed in the purge passage on the carburetor side to make the negative pressure acting on the adsorption box on the carburetor side smaller than the negative pressure acting on the adsorption box on the fuel tank side. This corresponds to the fact that the amount of evaporated fuel generated on the fuel tank side is smaller than that on the fuel tank side. If the same negative pressure acts on both adsorption boxes, the adsorption box on the carburetor side, which generates less evaporated fuel, will be purged faster, which will have a negative effect on the subsequent purge of evaporated fuel in the adsorption box on the fuel tank side. However, according to the present invention, such problems can be solved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the main part of the prior art, FIG. 2 is a sectional view showing an embodiment of the present invention, and FIG. 3 is a sectional view showing the main part of another embodiment of the invention. DESCRIPTION OF SYMBOLS 1...First vaporized fuel adsorption box, 2...Fuel tank, 3...Second vaporized fuel adsorption box, 4...
... Carburizer, 5... Float chamber, 19... Check valve, 24... Throttle, A... Purge passage of first vaporized fuel adsorption box, B... Purge passage of second vaporized fuel adsorption box, C... Confluence.

Claims (1)

[Scope of utility model registration request] In a fuel vapor adsorption device in which a first fuel vapor adsorption box communicating with a fuel tank and a second fuel vapor adsorption box communicating with a float chamber of a vaporizer are separately provided, a purge passage of the first fuel vapor adsorption box and a second vapor adsorption box communicating with a float chamber of a vaporizer are provided. One check valve is disposed at the confluence of the second evaporated fuel adsorption box with the purge passage, and the second
A fuel vapor adsorption device characterized in that a throttle is disposed in a purge passage of a fuel vapor adsorption box at an intermediate position between the float chamber and the check valve.