JPH03502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel vapor adsorption device for an engine that draws vaporized fuel adsorbed into a canister into an intake passage of the engine.

(Prior art) In engines, especially automobile engines,
To prevent evaporative fuel pollution, it is common practice to adsorb and capture evaporative fuel generated from fuel tanks, vaporizers, etc. using a canister. A vaporized fuel adsorption device is known that sucks vaporized fuel into the intake passage of an engine.

That is, by utilizing the intake negative pressure during engine operation, the evaporated fuel adsorbed in the canister is separated from the canister, guided into the intake passage of the engine, and combusted.

By the way, in this type of device, it is prohibited to introduce the evaporated fuel captured by the canister during deceleration into the intake passage, as this will result in an increase in harmful components in the exhaust gas.

(Problem to be solved by the invention) For this reason, the suction force due to the engine's intake negative pressure is weak, and the vaporized fuel adsorbed by the canister is not sufficiently released, resulting in a decrease in the adsorption capacity of the canister over time. I had the problem of doing so.

Conventionally known solutions to this problem include increasing the number of canisters, or
As seen in Japanese Patent No. 54-9252, a device equipped with a separate suction pump is known.

The conventional problem of the present invention is to use the high intake negative pressure generated in the intake system during deceleration to encourage the separation of evaporated fuel adsorbed by the canister, without providing a separate suction pump as in the past. An object of the present invention is to provide an evaporative fuel adsorption device for an engine that activates the adsorption function of a canister.

(Means and effects for solving the problems) The present invention provides that by placing the canister in a high negative pressure state, the evaporated fuel adsorbed on the canister becomes detached, and thereby the canister is sufficiently adsorbed. This was done with a focus on the ability to activate abilities.

That is, the present invention is based on an engine fuel vapor adsorption device that adsorbs vaporized fuel generated in a vaporized fuel generation source with a canister, and sucks the vaporized fuel adsorbed into the canister into the intake passage of the engine, and houses the canister. a negative pressure introduction passage that communicates the housing with the intake passage; a negative pressure opening/closing valve that opens the negative pressure introduction passage during deceleration; and an atmospheric opening/closing valve that closes the atmosphere release port of the housing during deceleration; The vehicle is configured to include an evaporated fuel opening/closing valve that closes an evaporated fuel introduction passage that guides the evaporated fuel to the housing during deceleration.

With this configuration, the inside of the housing in which the canister is housed is reduced in pressure due to the high intake negative pressure during deceleration, and the evaporated fuel adsorbed by the canister is forced to leave. From this,
The working capacity (adsorption capacity) of the canister is restored every time the speed is decelerated, and the adsorption function for the evaporated fuel from the evaporated fuel generation source can be activated.

(Example) Hereinafter, one example of the present invention will be described based on the accompanying drawings.

In FIG. 1, 1 is a combustion chamber of an engine, an intake port 2 and an exhaust port 4 are opened in the combustion chamber 1, the intake port 2 is connected to an intake passage 6, and the exhaust port 4 is connected to an exhaust passage 8. By opening and closing the intake valve 10 and the exhaust valve 12 at predetermined timing, the air-fuel mixture is sucked into the combustion chamber 1 and the combustion gas is discharged into the exhaust passage 8. The amount of air taken into the combustion chamber 1 is controlled by opening and closing a throttle valve 14 provided in the intake passage 6.

In the same figure, reference numeral 20 denotes a fuel vapor adsorption device according to the embodiment. It is designed to be attracted to.

That is, one end of the fuel vapor introduction pipe 26 enters the housing 24 in which the canister 22 is accommodated, and the other end of the fuel vapor introduction pipe 26 is connected to the fuel vapor generation source through a gas-liquid separator (not shown). as connected to the fuel tank or carburetor. Further, one end of the evaporated fuel outlet pipe 28 is opened in the housing 24, and the other end of the evaporated fuel outlet pipe 28 is opened.
It is connected to the downstream side of the throttle valve 14 in the intake passage 6. An on-off valve 30 and a diaphragm 32 as an actuator for the on-off valve 30 are provided in the middle of this evaporated fuel outlet pipe 28 , and a negative pressure chamber 34 of the diaphragm 32 is connected to the evaporated fuel conduit 28 .
An atmospheric chamber 35 is connected to the intake passage 6 immediately upstream of the throttle valve 14 via a pressure guiding pipe 36, and the diaphragm 32 is biased by a spring 38 in a direction to close the on-off valve 30. .

With such a configuration, evaporated fuel from a fuel tank or the like is guided into the housing 24 through the evaporated fuel introduction pipe 26, is adsorbed and captured by the canister 22, and the evaporated fuel captured by the canister 22 is When the on-off valve 30 is opened, air is sucked into the air intake passage 6 through the outlet pipe 28 by negative air intake pressure. At this time, the pressure within the housing 24 is compensated using an atmosphere release port 40 provided in the housing 24.

Here, a spring 38 that biases the diaphragm 32 is installed.
The biasing force is adjusted so that the on-off valve 30 is closed when the deceleration is fully closed, and therefore, the evaporative fuel captured by the canister 22 is transferred to the intake air by using the intake negative pressure at times other than when the deceleration is fully closed. It will be sucked into the passage 6. That is, during fully closed deceleration, the amount of intake air into the combustion chamber 1 is small, and introducing evaporated fuel into the intake passage 6 in this operating state increases harmful components in the exhaust gas. This is prevented by prohibiting this during fully closed deceleration.

In addition to this basic configuration, the evaporative fuel adsorption device 20 is provided with a negative pressure introduction pipe 42 that bypasses the outlet pipe on-off valve 30. That is, the negative pressure introduction pipe 42 has one end connected to the evaporated fuel outlet pipe 28 and the intake passage 6 from the on-off valve 30.
The negative pressure introduction pipe 42 has a solenoid valve (negative pressure opening/closing valve) 44 that opens and closes the negative pressure introduction pipe 42 .
is interposed. On the other hand, the above-described fuel vapor introduction pipe 26 is provided with a solenoid valve (fuel vapor opening/closing valve) 46 that opens and closes the fuel vapor introduction pipe 26.
Further, the above-mentioned atmosphere release port 40 is provided with an atmosphere opening/closing valve 48 for opening and closing the atmosphere release port.

The opening/closing operations of the negative pressure on/off valve 44, evaporative fuel on/off valve 46, and atmosphere on/off valve 48 are performed based on output signals from a control unit (not shown).

The relationship between valve opening/closing operations and operating conditions is as shown in FIG. That is, during fully closed deceleration, the negative pressure on/off valve 44 is opened, and both the evaporated fuel on/off valve 46 and the atmospheric air on/off valve 48 are closed.

In such a configuration, during fully closed deceleration, both the evaporative fuel introduction pipe 26 and the atmosphere release port 40 are shut off, while the housing 24 is connected to the negative pressure introduction pipe 4.
The air intake passage 6 is communicated with the air intake passage 6 through the air intake passage 2.

Therefore, the high intake negative pressure in the intake passage 6 causes the pressure inside the housing 24 to be reduced, and the closing of the atmosphere release port 40 prohibits the evaporated fuel from flowing into the intake passage. Therefore, the vaporized fuel adsorbed on the canister 22 is forced to leave.

And vaporized fuel fuel introduction pipe 26, atmosphere release port 4
0, when the canister 22 returns to an operating state other than fully closed deceleration, in which the evaporated fuel outlet pipe 28 is opened.
The vaporized fuel released is drawn into the intake passage 6 through the vaporized fuel outlet pipe 28, whereby the canister 22 recovers its adsorption function and its adsorption and capture capabilities are activated.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, the suction capacity of the canister can be recovered using the negative intake pressure during fully closed deceleration without providing a separate suction pump. Therefore, in addition to being advantageous in terms of cost, high adsorption capacity can be maintained for a long period of time without increasing the amount of canister.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of the embodiment, Fig. 2 is a timing relationship diagram showing the relationship between the opening/closing operation of the negative pressure on-off valve, the atmosphere on-off valve, and the evaporative fuel on-off valve and the operating state. It is a figure showing the relationship between adsorption capacity and pressure when it is placed in a reduced pressure state. 6... Intake passage, 20... Evaporated fuel adsorption device,
22...Canister, 24...Housing, 26
...Evaporative fuel introduction pipe, 40...Atmospheric release port, 42
... Negative pressure introduction pipe, 44 ... Negative pressure on/off valve, 46 ...
Evaporated fuel on/off valve, 48... Atmosphere on/off valve.

Claims (1)

[Scope of Claims] 1. An evaporator for an engine in which evaporative fuel generated at an evaporative fuel generation source is adsorbed by a canister, and the evaporative fuel adsorbed by the canister is sucked into an intake passage of the engine.A housing for accommodating the canister. a negative pressure introduction passage that communicates with the intake passage; a negative pressure opening/closing valve that opens the negative pressure introduction passage during deceleration; an atmospheric opening/closing valve that closes the atmosphere release port of the housing during deceleration; and the evaporator. An evaporative fuel adsorption device for an engine, comprising: an evaporative fuel opening/closing valve that closes an evaporative fuel introduction passage that guides fuel to the housing during deceleration.