JPS6113735Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel vapor emission prevention device for an internal combustion engine having an air flow meter.

Many internal combustion engines are equipped with a fuel vapor emission prevention device that guides the fuel vapor filling the fuel tank to an activated carbon canister and adsorbs it there, so that the fuel vapor that fills the fuel tank is not discharged into the atmosphere.
The fuel vapor adsorbed on the activated carbon canister is separated from the activated carbon by applying the engine's intake pipe negative pressure to the activated carbon canister and sucking the atmosphere through the atmosphere opening of the activated carbon canister, and is sent into the combustion chamber of the engine. .

However, in an internal combustion engine that detects the intake air amount with an air flow meter and controls the fuel supply amount based on the detected output, for example, a fuel injection controlled internal combustion engine that uses an air flow meter, the above-mentioned fuel vapor discharge occurs. The following problems arise when using a prevention device. In other words, since the fuel vapor separation air sucked into the activated carbon canister is sent directly to the combustion chamber without going through an air flow meter, the amount of fuel supplied is controlled without taking into account the amount of air for separation, and the engine control is affected accordingly. becomes inaccurate. For this reason, in the prior art, the amount of air for separation is minimized so as not to affect engine performance too much. However, according to such a method, there is a risk that the adsorption performance of the activated carbon canister is reduced, and the ability to prevent fuel vapor from being discharged is inevitably reduced.

In addition, in conventional fuel vapor emission prevention devices, one end of the activated carbon canister is partially open to the atmosphere, which inevitably causes fuel vapor to pass through without being adsorbed by the activated carbon and be emitted into the atmosphere. Ta.

The present invention is intended to solve the above-mentioned problems of the prior art, and the purpose of the present invention is to provide a fuel vapor emission prevention device that can improve the ability to prevent fuel vapor emission without affecting engine performance. Our goal is to provide the following.

A feature of the present invention that achieves the above-mentioned object is that it includes an air flow meter that detects the amount of air passing through the intake passage, and a fuel control system that controls the amount of fuel supplied to the engine according to the detected output of the air flow meter. This is a fuel vapor emission prevention device for an internal combustion engine, which includes an activated carbon canister connected to the fuel tank so as to adsorb fuel vapor in the fuel tank, and an activated carbon canister connected to the fuel tank on the upstream side when the throttle valve is in a fully closed state. a first port that opens into the intake passage at a downstream position when the throttle valve is opened to a predetermined opening degree or more, and is configured to send fuel vapor released from the activated carbon canister into the intake passage;
a second port for introducing air for fuel vapor separation into the activated carbon canister;
A port is communicated with an intake passage downstream of the air flow meter, and air in the intake passage is introduced into the activated carbon canister.

The present invention will be explained in detail below using the drawings.

FIG. 1 is a schematic diagram of a fuel injection type internal combustion engine which is an embodiment of the present invention. In the figure, 10 is an air flow meter provided upstream of the intake passage 12 of the engine, 14 is a throttle valve provided in the intake passage 12 downstream of the air flow meter 10, and 1
Reference numeral 6 indicates a fuel injection valve provided in an intake manifold portion further downstream from the throttle valve 14. The fuel injection amount is calculated from the intake air flow rate detected by the air flow meter 10 and the engine rotational speed obtained from the output of a crank angle sensor (not shown), and the fuel injection valve 16 is driven according to the calculated value. As a result, fuel injection control is performed.

In FIG. 1, 18 is a fuel tank, 2
0 indicates an activated carbon canister. Fuel vapor generated in the fuel tank 18 is guided to the activated carbon canister 20 via a passage 22 and adsorbed therein. A passage 24 is connected to the communicating side of the passage 22 of the activated carbon canister 20, and the other end of this passage 24 communicates with a purge port 26. The purge port 26 is located upstream of the throttle valve 14 when the throttle valve 14 is in a fully closed state or a state close to it, and is located upstream of the throttle valve 14 when the throttle valve 14 is opened at a predetermined angle, for example, 12 to 13 degrees Celsius or more. It opens into the intake passage 12 at a position downstream from the intake passage 14. Passage 24 of activated carbon canister 20
A purge air intake port 30 communicates with the side opposite to the communicating side via a passage 28. This purge air intake port 30 is connected to the air flow meter 1.
It opens into the intake passage 12 downstream from the throttle valve 14 and upstream from the throttle valve 14.

When the engine enters a normal operating state different from an idle state, the throttle valve 14 opens and intake pipe negative pressure is applied to the activated carbon canister via the purge port 26, so purge air is taken in from the purge air intake port 30 and the activated carbon Fuel vapor adsorbed in the canister is separated and sent into the combustion chamber 32 via the passage 24 and purge port 26.
In this case, the amount of purge air can also be measured using the air flow meter 10.
There is no need to reduce this amount, and the adsorbed fuel vapor can be removed with a sufficient amount of purge air.
There is no possibility that the adsorption performance of 0 will deteriorate. Also,
Since the purge air intake port 30 opens into the intake passage between the air flow meter 10 and the throttle valve 14, there is a risk that fuel vapor that passes through without being adsorbed by the activated carbon canister 20 during adsorption may be discharged into the atmosphere. Not at all.

FIG. 2 shows a modification of the present invention, 1
0' is the air flow meter, 12' is the intake passage, 3
0' indicates the purge air intake port, respectively. The configuration of other parts not shown in the figure is exactly the same as the embodiment shown in FIG. That is, in the example shown in FIG. 2, the opening direction of the purge air intake port 30' is the upstream direction of the intake passage 12'. With this configuration, dynamic pressure is applied to the activated carbon canister 20, and the amount of purge air is increased in proportion to the amount of intake air. It is clear from the above explanation that the amount of purge air decreases when the intake pipe negative pressure decreases, that is, when the engine is under high load, but by configuring as shown in Figure 2, this amount of purge air can be reduced. This makes it possible to compensate for

As explained above, according to the device of the present invention,
Since the amount of purge air can be increased without affecting the performance of the engine, it is possible to prevent the adsorption performance of the activated carbon canister from deteriorating, and to that extent, the ability to prevent fuel vapor from being discharged can be prevented from deteriorating. Furthermore, since no fuel vapor is released into the atmosphere without being adsorbed by the activated carbon, the ability to prevent fuel vapor emissions is increased accordingly.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of one embodiment of the present invention, and FIG. 2 is a diagram showing a part of another embodiment of the present invention. 10,10'...Air flow meter, 12,1
2'...Intake passage, 14...Throttle valve, 18
... Fuel tank, 20 ... Activated carbon canister, 2
6...Purge port, 30, 30'...Purge air intake port.

Claims (1)

[Scope of utility model registration request] A fuel vapor emission prevention device for an internal combustion engine, comprising an air flow meter that detects the flow rate of air passing through an intake passage, and a fuel control system that controls the amount of fuel supplied to the engine according to the detected output of the air flow meter. The activated carbon canister is connected to the fuel tank so as to adsorb fuel vapor in the fuel tank, and when the throttle valve is in a fully closed state, it is on the upstream side, and when the throttle valve is opened to a predetermined opening degree or more. a first port that opens into the intake passage at a position on the downstream side of the activated carbon canister, and for feeding the fuel vapor separated from the activated carbon canister into the intake passage; and a first port for introducing air for separating the fuel vapor into the activated carbon canister. a second port;
A fuel vapor emission prevention device for an internal combustion engine, wherein the second port communicates with an intake passage downstream of the air flow meter, and introduces air in the intake passage into the activated carbon canister.