JPS5910375Y2 - Evaporated fuel treatment device in the fuel tank - Google Patents

Description

[Detailed description of the invention] This invention mainly stores the evaporative fuel generated in the fuel tank in the evaporative fuel storage device when the internal combustion engine is stopped, and consumes it as fuel when the engine is running, thereby reducing air pollution caused by the evaporative fuel. The present invention relates to an evaporative fuel processing device that is designed to prevent fuel consumption and to save fuel.

Conventional Karuru devices reduce the internal pressure of the fuel tank by installing a check valve in the passage connecting the upper space of the sealed fuel tank and the evaporated fuel storage device, which opens when the internal pressure of the fuel tank exceeds a certain value. This is to suppress fuel evaporation as much as possible and reduce the burden on the evaporative fuel storage device. It is not possible to lead all the evaporated fuel that has already been generated to the engine and consume it, so a large amount of evaporated fuel always remains in the fuel tank, so if fuel evaporates in the fuel tank after the engine has stopped, The reality is that when the check valve opens, the evaporated fuel must be stored in the evaporative fuel storage device, and a large-capacity evaporative fuel storage device is forced to be used.

In addition, even while the engine is running, the internal pressure of the fuel tank is increased by the evaporation pressure of the fuel, so the fuel supply pressure from the fuel tank to the carburetor increases, and the oil level in the float chamber of the carburetor rises to some extent, causing the fuel to be produced in the carburetor. Another drawback is that the air-fuel ratio of the air-fuel mixture to be controlled becomes richer than necessary, increasing the concentration of unburned gas in the exhaust gas of the engine.

SUMMARY OF THE INVENTION An object of the present invention is to provide an evaporative fuel treatment device in a fuel tank that eliminates the above-mentioned drawbacks.

An embodiment of the present invention will be described below with reference to the drawings.

? Starting with the first embodiment shown in FIG. 1, reference numeral 1 indicates a fuel tank of a vehicle, for example, a motorcycle, and the fuel stored in it passes through a fuel passage (not shown) to a carburetor 2 of an internal combustion engine.
is guided to the float chamber 3.

A cap 4 is attached to the fuel filler port at the top of the fuel tank 1, and the upper space 1a inside the tank is sealed. Since the valve is built-in, there is no problem in supplying fuel from the fuel tank 1 to the carburetor 2.

The evaporated fuel passage 5 extending from the upper space 1a of the fuel tank 1 has a first branch passage 5 and a second branch passage 5 along the way.

The evaporated fuel storage device 6 is branched into two branches, and either converges into a single line or reaches the evaporated fuel storage device 6 without converging.

The vaporized fuel storage device 6 has an inlet port 7 and a discharge port 8 on the upper side.
This is a conventionally known device in which an activated carbon evaporated fuel adsorbent 11 is loaded into a container body 10 having an atmosphere opening 9 on the lower side.
The first and second branch passages 51 and 52 are connected to the inlet 7, and the outlet 8 is connected to the evaporated fuel passage 12 which is connected to the intake passage 2a of the carburetor 2, and the intake negative pressure of the engine is connected to the outlet 8. A check valve 13 that opens under the action of is interposed.

A check valve 14 that opens to allow fluid to flow from the fuel tank 1 side to the evaporated fuel storage device 6 side is interposed in the first branch passage 5, and the valve pressure is set sufficiently high during this time. In addition, an electromagnetic on-off valve 15 and an orifice 16 are installed in series in the second branch passage 52, and the solenoid 15a of the electromagnetic on-off valve 15 is connected to a control switch 17 that opens and closes in conjunction with the ignition switch of the engine. and a normally closed emergency switch 18 that opens automatically in the event of a vehicle collision and is connected to a power source 19.

With this structure, when the engine is stopped, that is, when the engine ignition switch is opened, the control switch 17 is also opened in conjunction with this, so the electromagnetic on-off valve 15 is connected to the power supply 19.
As shown in the figure, the power supply from the second branch path 5 is cut off.

will be closed. Therefore, when fuel evaporates within the fuel tank 1, the evaporated fuel remains within the fuel tank 1 until the internal pressure of the fuel tank 1 reaches the opening pressure of the check valve 14 of the first branch path 5. Therefore, since the inside of the fuel tank 1 is maintained at a high pressure, evaporation of the fuel is suppressed.

However, due to heat absorption in the fuel tank 1, its internal pressure becomes higher than the above-mentioned valve opening pressure? When the engine rises and the check valve 14 is opened, the fuel tank 1
A part of the evaporated fuel passes through the first branch passage 5 and is introduced into the evaporated fuel storage device 6 from the inlet 7, and is adsorbed by the evaporated fuel adsorbent 11, thereby reducing the excess internal pressure of the fuel tank 1. is released to the outside from the atmosphere opening 9.

Next, close the engine ignition switch and start the engine.
Since the control switch 17 is also closed, the solenoid 15a of the electromagnetic on-off valve 15 is energized by the power source 19, and the second branch path 5 is opened.

Therefore, the evaporated fuel retained in the fuel tank 1 is once introduced into the evaporated fuel storage device 6 via the second branched path 5 without being blocked by the check valve 14 of the first branched path 51.

Since the check valve 13 in the passage 12 is opened by the negative intake pressure of the engine, the evaporated fuel introduced into the evaporated fuel storage device 6 immediately moves to the passage 12 and passes through there into the intake passage 2a of the carburetor 2. The air is sucked into the air, mixes with the air-fuel mixture produced in the intake passage 2a, and is supplied to the cylinders of the engine.

During this time, the flow rate of the evaporated fuel flowing through the second branch passage 52 is appropriately controlled by the restricting resistance of the orifice 16, so that a large amount of evaporated fuel does not flow into the intake passage 2a at once, and mixture due to mixture of evaporated fuel The change in the air-fuel ratio is practically negligible.

On the other hand, outside air flowing in from the atmosphere opening port 9 passes through the inside of the evaporated fuel storage device 6 due to the action of the engine's intake negative pressure, and the adsorbed evaporated fuel is released from the adsorbent 11, so that fuel also flows through the passage 12. The air is then sucked into the intake passage 2a.

In this way, the internal pressure of the fuel tank 1 is returned to approximately atmospheric pressure immediately after the engine is started, and the fuel supply pressure from the fuel tank 1 to the carburetor 2 is maintained at a normal level, so that the fuel oil level in the float chamber 3 is Almost no fluctuation occurs.

Furthermore, the fact that the internal pressure of the fuel tank 1 is returned to atmospheric pressure while the engine is running means that when the engine is stopped, the fuel tank 1
The evaporated fuel can be kept inside until the internal pressure of the first branch passage 5 reaches the opening pressure of the check valve 14 of the first branch passage 5 from the atmospheric pressure.
The amount of evaporated fuel released into the fuel tank can be reduced.

If the vehicle encounters a collision while the engine is running, the emergency switch 18 will sense the impact and open automatically, so it will not work even if the control switch 17 is closed. Even if it is, the electromagnetic on-off valve 15 immediately switches to the second branch path 5.

Close. However, even if the vehicle falls over, the fuel in the fuel tank 1 is prevented from passing through the evaporative fuel passage 5 by the check valve 14 with a high opening pressure and the electromagnetic shut-off valve 15, and the fuel in the evaporative fuel storage device is The leakage to the 6th side is prevented.

FIG. 2 shows a second embodiment of the present invention, in which the second branch 52 of the evaporated fuel passage 5 is a check valve whose opening pressure is set lower than that of the check valve 14 of the first branch 5. 20 to the inside of the crankcase 21 of the engine E, and the inside of the crankcase 21 was also connected to the air cleaner 23 attached to the carburetor 2 through the blow-by gas recirculation path 22 as is well known. The structure is the same as that of the previous embodiment, and in FIG. 2, the same reference numerals are given to the parts corresponding to those of the previous embodiment.

In the above structure, while the engine E is operating, the pulsating pressure generated in the crankcase 21 acts on the check valve 20 of the second branch passage 5 to open and close it, and accordingly, the fuel tank 1
The evaporated fuel inside is gradually introduced into the crankcase 21 through the second branch passage 5, and is then sucked into the air cleaner 23 through the blow-by gas recirculation passage 22 together with the internal blow-by gas. Similarly vaporizer 2
The mixture is mixed with the air-fuel mixture produced in the air-fuel mixture and is supplied into the cylinders of the engine E.

Therefore, the evaporated fuel released from the fuel tank 1 to the engine E during engine operation does not pass through the evaporated fuel storage device 6, and the frequency of use of the adsorbent 11 in the storage device 6 is reduced accordingly compared to the previous embodiment. , Sucking? The life of the agent 11 can be significantly extended.

Other functions are similar to those of the previous embodiment.

As described above, according to the present invention, the evaporated fuel in the sealed fuel tank is consumed during engine operation to bring the internal pressure to approximately atmospheric pressure, and when the engine is stopped, the internal pressure of the fuel tank is reduced to a certain value. As a result, even though evaporated fuel is generated in the fuel tank when the engine is stopped, the amount of evaporated fuel released from there to the evaporated fuel storage device can be kept to a low level, and as a result, a small volume of evaporated fuel can be stored. It is possible to use a storage device, which not only reduces the cost, but also has the advantage of being easy to install even in a narrow space when mounted on a vehicle.

Additionally, since the internal pressure of the fuel tank is returned to approximately atmospheric pressure during engine operation, the fuel supply pressure from the fuel tank to the engine's carburetor is always maintained at an appropriate level, and as a result, the air-fuel mixture produced in the carburetor is There is no large fluctuation in the fuel ratio, combustion is carried out properly, and the concentration of waste gas in the exhaust gas is reduced, which is extremely useful for preventing air pollution.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a main part of a first embodiment of the device of the present invention in longitudinal section, and FIG. 2 is a similar schematic diagram of a second embodiment. E...Engine, 1...Fuel tank, 1a...Upper space, 2a...Intake passage, 5...Evaporative fuel passage, 5...
・First branch path, 52... Second branch path, 6... Evaporated fuel storage device, 14... Check valve, 15... Open/close valve, 16
... Orifice, 21 ... Crank case, 22.
...Blowby gas return path.

Claims (3)

[Scope of utility model registration request] (1) An evaporative fuel passage extending from a sealed upper space in the fuel tank is branched into a first branch and a second branch, and the first branch is opened when the internal pressure of the fuel tank exceeds a certain value. connected to the evaporation storage via a stop valve, and the second
An evaporative fuel processing device in a fuel tank in which a branch passage is connected to an engine intake system via an on-off valve that is opened when the engine is running and closed when the engine is stopped. (2) Utility Model Registration In the evaporative fuel processing device in a fuel tank according to claim (1), the second branch path is connected to the intake system of the engine via the evaporative fuel storage device. An evaporated fuel processing device in the fuel tank, in which an orifice for controlling the flow rate of evaporated fuel is provided in series with the on-off valve in the two branch paths. (3) Utility Model Registration In the evaporated fuel processing device in a fuel tank according to claim (1), the second branch path is connected to the inside of the engine crankcase and via a blow-by gas recirculation path extending from the engine crankcase. An evaporative fuel processing device in the fuel tank, which communicates with the intake system of the engine and has a second branch line provided with a check valve that opens and closes under the action of pulsating pressure in the crankcase.