JPH0328587B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to an evaporative fuel suppression device for an engine.

(Prior Art) Conventionally, it is undesirable from the viewpoint of air pollution prevention to directly discharge evaporated fuel generated in a fuel tank into the atmosphere. Therefore, by communicating the upper space of the fuel tank with the canister, vaporized fuel is held in the canister, and when the throttle valve opens more than a certain degree during engine operation,
2. Description of the Related Art A fuel vapor processing device for an engine is known in which fuel vapor is supplied to an intake passage and combusted (see, for example, Japanese Utility Model Application Publication No. 119354/1983).

(Problem to be Solved by the Invention) By the way, when an external load is applied to the engine during idling operation (for example, when an air conditioner is activated), the engine is equipped with an idle-up means that opens the throttle valve slightly. There is an engine. When the above evaporative fuel processing device is applied to such an engine, for example, when the air conditioner switch is closed, the throttle valve opens to a predetermined opening by the idle up means, even though the engine is idling. However, there is a problem in that a large amount of evaporated fuel flows into the intake passage at one time, making the air-fuel ratio A/F rich (see the solid line in FIG. 3), resulting in large fluctuations in engine rotation. Therefore, even though the driver is not pressing the accelerator pedal, engine rotational fluctuations occur, which causes the driver to feel uncomfortable.

In view of these points, the present invention supplies evaporated fuel to the intake system according to the opening degree of the throttle valve, while suppressing engine rotational fluctuations during idle up in an engine equipped with idle up means. The purpose of the present invention is to provide an evaporative fuel suppression device.

(Means for Solving the Problem) In order to achieve the above object, the solving means of the present invention provides an engine in which vaporized fuel is supplied to the intake system according to the opening degree of the throttle valve.
When an external load is applied during idling,
idle up means for opening the throttle valve to a predetermined opening; and control means for limiting the amount of vaporized fuel supplied by the idle up means to be less than the amount corresponding to the opening of the throttle valve at the time of idle up. It shall be equipped with the following.

(Function) As a result, in the present invention, at idle up,
Since the amount of evaporated fuel supplied to the intake system is limited to be less than the amount corresponding to the throttle valve opening at that time, a large amount of evaporated fuel may be supplied at one time depending on the throttle valve opening at that time. By preventing fuel from being supplied, fluctuations in engine rotation during idle up can be suppressed.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

As shown in FIG. 1, an evaporative fuel supply passage 5 from an upper space 4a of a fuel tank 4 is connected via a canister 6 to a carburetor 3 of an intake passage 2 connected to an intake port 1a of an engine 1. ing. A first throttle valve 8 is disposed upstream of the opening 7 of the vaporized fuel supply passage 5 in the vaporizer 3.
When an external load is applied to the engine 1, the first throttle valve 8
Further, an idle up means 9 is linked to control the opening and closing of the opening to a predetermined opening degree. Further, the engine 1 includes a supply passage opening/closing means 16 for cutting off communication of the evaporated fuel supply passage 5 when the engine 1 is cold, that is, when the cooling water temperature is below a set temperature, and Control means 10 are provided for restricting the flow of evaporated fuel.

The engine 1 is provided with an exhaust port 1b symmetrically with respect to an intake port 1a, and a water jacket 1c for cooling the engine 1 is formed. An air cleaner 11 is connected to the intake passage 2 on the upstream side of the carburetor 3. The carburetor 3 is provided with a second throttle valve 12 in parallel with the first throttle valve 8, which opens when the load is high. A cooling water passage 13 communicates with the iota jacket 1c of the engine 1.

The fuel tank 4 is provided with a fuel inlet 4b. The evaporated fuel supply passage 5 includes an upstream supply passage 5a between the fuel tank 4 and the canister 6, and a downstream supply passage 5b connected to the outlet side of the canister 6.
It consists of Further, the downstream supply passage 5b is branched into two, and each branch passage 5c is provided with a first orifice 14 and a second orifice 15, respectively.

The idle up means 9 is equipped with a servo diaphragm mechanism (not shown) and operates when negative pressure is supplied to rotate the first throttle valve 8 by a predetermined angle in the opening direction.

The supply passage opening/closing means 16 includes a purge control valve 18 which opens an opening/closing valve 17 which opens and closes communication of the downstream supply passage 5b connected to the canister 6 when negative pressure is supplied, and a purge control valve 18 which opens and closes communication of the downstream supply passage 5b connected to the canister 6.
A first negative pressure supply passage 20 connecting the first intake negative pressure outlet hole 19 opened immediately upstream of the throttle valve 8 and the purge control valve 18
and a three-port, two-position thermovalve 21 interposed in the middle of the first negative pressure supply passage 20. The thermovalve 21 is provided with its temperature sensing part 21a facing the cooling water passage 13, and when the water temperature in the cooling water passage 13 exceeds the set temperature, the thermovalve 21 is switched to the upper side in FIG. and communicates with the first negative pressure supply passage 20.

In the control means 10, the branch passage 5c on the side where the first orifice 14 is provided is connected to the side surface, and the branch passage 5c on the side where the second orifice 15 is provided is connected to the end face in the direction in FIG. The left end face of the control valve 28 in FIG. a second negative pressure supply passage 23;
A first solenoid valve 24 with three ports and two positions is interposed in the middle of the second negative pressure supply passage 23, and an air conditioner switch 25 and a battery 2 are connected in series to the solenoid of the first solenoid valve 24.
It consists of 6 and 2. 27 is an air conditioner. When the first solenoid valve 24 is energized, it is switched upward in FIG. 1 and passes through the second negative pressure supply passage 23. In FIG. 1, the control valve 28 has a negative pressure chamber 28b formed on the left side by a diaphragm 28a, and a valve body 28c is provided integrally with the diaphragm 28a, and a valve seat is integrally provided inside the control valve 28. 28d is provided. Second negative pressure supply passage 2
3 decreases, the diaphragm 28a moves to the left in FIG.
The branch passage 5c on the first orifice 14 side, which is seated at d and connected to the control valve 28, is closed. Note that the second negative pressure supply passage 23 connected to the control valve 28 is branched and connected to the idle up means 9.

Therefore, first, during idling operation, when the cooling water temperature of the engine 1 is below the set temperature, the thermovalve 21 is closed as shown in the figure, so the air conditioner 27 is activated by closing the air conditioner switch 25. Even if the engine 1 idles up, no negative pressure is supplied to the purge control valve 18, and the open/close valve 17 remains closed as shown by the solid line, causing the evaporated fuel in the upper space 4a of the fuel tank 4 to evaporate. It is not supplied to vessel 3.

When the cooling water temperature exceeds the established temperature, the thermovalve 21 is switched to the upper position in FIG.
Therefore, the negative pressure of the first intake negative pressure outlet hole 19 is supplied to the purge control valve 18, and the purge control valve 18 is operated to operate the opening/closing valve 17.
is opened as shown by the chain line.

On the other hand, when the air conditioner switch 25 is open, the first solenoid valve 24 does not operate and remains in the closed position, so the second intake negative pressure outlet hole 22
The negative pressure is not supplied to the control valve 28, and the state shown in FIG. 1 remains.

Therefore, the vaporized fuel held in the canister 6 is caused by a flow from the downstream supply passage 5b passing through the first orifice 14 and the control valve 28 in the branch passage 5c and a flow passing through the second orifice 15 merging. The fuel is then supplied into the carburetor 3 through the opening 7 and combusted inside the engine 1.

At this time, when the air conditioner switch 25 is closed, the first solenoid valve 24 is activated and switched to the upper position in FIG. The operation of the idle up means 9 causes the first throttle valve 8 to rotate slightly in the direction of opening. On the other hand, the negative pressure of the second intake negative pressure outlet hole 22 is also supplied to the negative pressure chamber 28b of the control valve 28, and this negative pressure chamber 28b is also supplied to the negative pressure chamber 28b of the control valve 28.
The introduction of negative pressure to diaphragm 8b causes diaphragm 28a to be biased to the left in FIG. Along with that,
Since the valve body 28c seats on the valve seat 28d and closes,
Among the evaporated fuel flowing through the branch passage 5c, the evaporated fuel stops flowing through the first orifice 14, and the evaporated fuel stops flowing through the first orifice 14.
The evaporated fuel reaches the opening 7 only through the orifice 14, and the supply of evaporated fuel during idle up is restricted. Therefore, the fluctuation in the air-fuel ratio A/F becomes smaller than before (see the broken line in Figure 3), and the engine 1
The rotational fluctuations are also small, and the driver does not feel any discomfort.

Next, a modification of the above embodiment will be explained with reference to FIG. 2. Note that the same elements as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted. The downstream supply passage 5b is directly connected to the opening 7 of the supply passage 2. A third intake negative pressure outlet hole 31 is opened further upstream of the first intake negative pressure outlet hole 19 of the carburetor 3 . Further, a second solenoid valve 32 with two positions and three supports is provided as a control means. The third negative pressure supply passage 33 connected to the third intake negative pressure outlet hole 31 is connected to one of the two inflow ports of the second solenoid valve 32, and is also connected to the other inflow port of the second solenoid valve 32. is connected to the upstream side of the first negative pressure supply passage 20 connected to the first intake negative pressure extraction hole 19, and the downstream side of the first negative pressure supply passage 20 connected to the thermovalve 21 is connected to the outflow side port. ing. Further, the solenoid of the second solenoid valve 32 is connected in parallel with the solenoid of the first solenoid valve 24.

With this configuration, when the engine 1 is idling when the cooling water temperature is below the set temperature (the state shown in the figure), the vaporized fuel in the canister 6 can be supplied to the carburetor 3 by closing the on-off valve 17. There isn't.

When the set temperature is exceeded and the thermo valve 21 is switched, and the negative pressure in the first intake negative pressure outlet 19 reaches the purge control valve 18 via the second solenoid valve 32 and the thermo valve 21, this is activated. Open the on-off valve 17. Thereby, the vaporized fuel reaches the opening from the downstream supply passage 5b and is supplied to the vaporizer 3.

However, the air conditioner switch 25 is closed,
When the idle is up, the second solenoid valve 32 is switched to the right position in FIG. 21 and acts on the purge control valve 18. Since the third intake negative pressure outlet hole 31 opens on the upstream side of the first intake negative pressure outlet hole 19, the negative pressure in the third intake negative pressure outlet hole 31 is equal to the negative pressure in the first intake negative pressure outlet hole 19. Because it is closer to atmospheric pressure than negative pressure,
In this case, the negative pressure acting on the purge control valve 18 is also close to atmospheric pressure, and the on-off valve 17 is in a half-open state, and the downstream supply passage 5b
The amount of evaporated fuel flowing into the engine 1 is limited, and the rotational fluctuations of the engine 1 are reduced as in the embodiment shown in FIG.

(Effects of the Invention) According to the present invention, the amount of evaporated fuel supplied is limited to a small amount even though the throttle valve is opened due to the idle up, so engine rotation fluctuations at the idle up are reduced. is smaller, and the driver does not feel any discomfort.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram showing an evaporative fuel suppression device for an engine according to the present invention, FIG. 2 is an overall configuration diagram showing a modified example, and FIG. 3 is an operation explanatory diagram showing changes in air-fuel ratio. 1...engine, 2...intake passage, 8...first
Throttle valve, 5...Evaporative fuel supply pipe, 9...
...Idle up means, 10...Control means, 27
...Air conditioner.

Claims (1)

[Scope of Claims] 1. In an engine in which vaporized fuel is supplied to the intake system according to the opening degree of a throttle valve, when an external load is applied during idling operation, the throttle valve is opened to a predetermined opening degree during idling. An engine characterized by comprising: a boosting means; and a control means for limiting the amount of evaporative fuel supplied when the idle boosting means increases the idle so that it is less than the amount corresponding to the opening degree of the throttle valve at that time. evaporative fuel suppression device.