JPS60147561A - Fuel vapor removing device for internal-combustion engine - Google Patents

Abstract

PURPOSE:To effect the scavenging of the inside of a suction path surely and improve the restarting property of the engine by a method wherein a vaporized fuel path, interposed with a pump and a non-return valve, is connected to the suction air path of the internal-combustion engine while the pump is controlled so as to be driven for a predetermined period of time after stopping the engine. CONSTITUTION:When a key switch 21 is opened to stop the engine under operating condition, an engine temperature is high and a temperature switch 17 is being closed, therefore, both inputs of the NOR gate 22 of a control circuit unit 15 become low potential, the potential of an output point A is increased and a timer circuit 24 is operated through a trigger circuit 23. Then, the potential of the output point B of an AND gate 25 becomes high for a predetermined period of time, a transistor 26 is put ON and the pump 11 is driven. Accordingly, the vaporized fuel in the suction air path 3 is sent by the pump 11 into a canister 10 through the non-return valve 12 together with air, only the fuel constituent thereof is adsorbed to the canister 10 and the air is released into atmosphere through an atmosphere opening port 14.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application This invention relates to a fuel vapor removal device for improving restartability of an internal combustion engine at high temperatures.

BACKGROUND OF THE INVENTION Conventional internal combustion engines operate normally by being supplied with an air-fuel mixture having an appropriate air-fuel ratio according to the engine's operating conditions from an intake passage.

Considering the state after the engine is stopped, the engine remains in a high temperature state for a while after stopping due to residual heat from the exhaust pipe, catalyst, etc. Therefore, the evaporation of the fuel remaining in the float chamber, fuel passage, etc. of the carburetor is promoted, and a portion of it flows from the float chamber through the air vent or flows out from the main nozzle, acceleration nozzle, etc. into the intake passage. As a result, the air-fuel mixture in the intake passage has an excess fuel component. If the engine is restarted at this point, an extreme air-fuel mixture will be sucked into the combustion chamber, resulting in poor restartability.

In order to solve this problem, a device disclosed in Japanese Utility Model Application Publication No. 57-126558 has been proposed. This system communicates the intake passage with the canister (evaporated fuel collection device) when the engine is stopped, allowing excess fuel components in the intake passage to be adsorbed into the canister, making the air-fuel mixture appropriate and improving restartability. There is.

In this prior art, in order to adsorb excess evaporated fuel onto the canister, the evaporated fuel is moved toward the canister due to its diffusion and the difference in specific gravity with air. Therefore, it was necessary to promote the movement of evaporated fuel by lowering the mounting position of the canister.

C.6 Problems to be Solved by the Invention The above-mentioned conventional technology has the disadvantage that the canister must be installed at a low position, and there is no flexibility in the arrangement of equipment in the engine compartment of the automobile. . Furthermore, in recent years, the number of front-wheel drive cars, cab-over cars, turbo cars, etc. has been increasing, but because the temperature in the engine room of these cars is much higher, the amount of fuel that flows into the intake passage after the engine stops has increased significantly. are doing. In order to respond to such recent trends in automobiles, the conventional techniques described above lack the ability to discharge evaporated fuel and cannot meet the emission capacity required by these automobiles.

The purpose of this invention is to propose a fuel vapor removal device that can solve these problems.

21 Structure of the Invention The fuel vapor removal device of the present invention comprises a vaporized fuel passage whose one end opens into the intake passage of an internal combustion engine, a pump and a check valve provided in the vaporized fuel passage, and A control circuit for driving the pump.

E1 Function When the engine stops, the control circuit drives the pump for a certain period of time to forcibly discharge the evaporated fuel in the intake passage. The check valve prevents excess air from being drawn into the intake passage from the evaporated fuel passage during engine operation.

Embodiment In FIG. 1, (1) is an engine, (2) is a carburetor attached to the engine via an intake passage (3), and (4) is an engine.
) is an air cleaner. (5) is a float chamber, (6
) is an air vent, (7) is a main nozzle, and (8) is a throttle valve. (9) is an evaporated fuel passage whose one end (left end) opens to the intake passage (2), the other end communicates with the canister 00), and the pump (11) and check valve (1) in the middle.
2) is provided in series. (13) is a purge pipe whose one end communicates with the canister 00) and the other end communicates with the intake passage near the throttle valve, and (14) an atmospheric opening connected with the canister 00). (15) is an electric wire (16)
a control circuit section (17) connected to the pump (11);
) detects the temperature in the engine compartment using a temperature switch and closes only when the temperature is high.

The control circuit section (15) is composed of the electric circuit shown in FIG. (18) is a battery, (19) and (20) are resistors, (21) is a key switch, (22) is a NOR gate, (23) is a trigger circuit, (24) is a timer circuit,
(25) is an AND gate, and (26) is a transistor, which are connected as shown to form a control circuit. Note that the point indicated by the arrow V in the figure is connected to a constant positive voltage. This positive voltage is obtained from the positive terminal of the battery (18) or from a stabilized power supply circuit (not shown).

The operation of the above embodiment will be explained with reference to FIGS. 1 to 3.

Since the key switch (21) is closed during engine operation, the output point A of the NOR gate (22) is at a low potential. Also, if the engine temperature is high at this time, the temperature switch (17
) is closed. When the key switch (21) is opened to stop the engine in this state, the re-input to the NOR gate becomes a low potential, so the voltage at the output point A rises by a moment, and the trigger circuit (23) The rise is detected and a trigger signal is applied to the timer circuit (24). Timer circuit (
Reference numeral 24) is a circuit such as a small stable multi-by-break, for example, and upon application of the trigger signal, output is output for a certain period of time. Therefore, the voltage at the output point B of the AND gate (25) is at a high potential for the predetermined period of time, making the transistor (26) conductive and driving the pump (11). Therefore, the mixture of vaporized fuel and air in the intake passage (3) is sent to the canister 00) by the pump (11), only the fuel component is adsorbed to the canister, and only the air is passed through the atmospheric opening (14) into the atmosphere. released into the body. The timer circuit (24) serves to prevent battery (18) consumption.

In winter, when the temperature is low, the temperature in the engine room does not rise to high temperatures, so the fuel in the carburetor does not reach high temperatures and there is little vaporization. Therefore, there is no need to operate the pump (11). Since the temperature switch (17) detects the salinity and opens in such a case, the output A of the NOR gate (22)
The point becomes low potential and the pump (11) is not driven.

Next, when the engine is restarted, the air-fuel mixture in the intake passage (3) is sucked into the engine (1), but due to the action of the pump (11) after the engine has stopped, the air-fuel mixture in the intake passage becomes too rich. Since there is no such thing, a complete explosion occurs quickly and a smooth restart occurs. In this way, when the engine is restarted, the intake passage (3) becomes negative pressure, and this negative pressure acts on the evaporated fuel passage (9) and the purging pipe (13). non-return valve(
12) is closed by this negative pressure, closing the vaporized fuel passage.

Since the negative pressure acting on the purging pipe (13) is transmitted to the canister 00), outside air is sucked in from the atmospheric opening (14), passes through the canister 00) and the purging pipe (13), and flows into the intake passage (3). Due to this air flow, the excess fuel adsorbed in the canister θ0) is desorbed, and the canister θ0) returns to its state before adsorption.

FIG. 4 shows another embodiment, which differs from the embodiment shown in FIG. 1 in that it does not have a canister 00), a purging pipe (13), and an atmospheric opening (14) in the canister. . The right end of the vaporized fuel passage (9) is directly open to the atmosphere. This embodiment is a device that can be used for vehicles that do not use a canister and are intended for areas where there are no exhaust regulations. In this case, when the pump (11) operates, the evaporated fuel in the intake passage (3) is discharged into the atmosphere from the right end of the evaporated fuel passage (9). As the control circuit section used in this embodiment, the circuit shown in FIG. 2 can be used.

FIG. 5 shows another embodiment of the control circuit section (15).

(27) is a buffer amplifier, and (28) and (29) are resistors. (30) is a thermoelectric generating element that is attached to an exhaust pipe, catalyst, muffler, etc. Note that other elements having the same symbols as in FIG. 2 are the same elements.

Each element is connected as shown.

In the control circuit shown in this figure, a timer circuit that operates the pump (11) for a certain period of time after the engine stops is not provided, and the function for determining the certain period of time is performed by the thermoelectric generating element (30).
) is fulfilled.

When the key switch (21) is closed and the engine is running and the temperature in the engine room is high, the temperature switch (17) is closed and the voltage at the output point A of the NOR gate (22) is at a low potential. If you open the key switch (21) to stop the engine, the NOR game will start as shown in Figure 6.
22) becomes a high potential, the transistor (26) (shown in FIG. 5) becomes conductive, and the -pump (11) is driven. The evaporated fuel in the intake passage is then discharged. At this time, the power to drive the pump (11) is provided by the thermoelectric generator (30). In this way, the pump (11
), which is advantageous because it eliminates the need to consume battery power. Further, after the engine is stopped, the exhaust pipe, catalyst, muffler, etc. cool down, the electromotive force of the thermoelectric generator stops, and the operation of discharging evaporated fuel from the intake passage automatically stops.
- Effects of the Invention Figure 7 shows temporal changes in intake pipe negative pressure during restart.
During cranking, the engine speed is low, so the negative pressure in the intake pipe is small, about 1'50m) (g). When the engine fully explodes and starting is completed, the engine speed advances to the idle speed, so Intake pipe negative pressure is -500mmHg
rises to a certain extent. In this invention, this -500mmT
(The time it takes for the intake pipe negative pressure to reach around g can be reduced by over 3 seconds compared to the conventional device.

As described above, according to the present invention, since the air in the intake passage is automatically and forcibly scavenged for a certain period of time after the engine is stopped, it can be used even in vehicles where the engine room is particularly hot, such as recent front-wheel drive vehicles. This has the effect of reliably improving restartability.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram explaining an embodiment of this invention, Fig. 2 is an electric circuit diagram used in Fig. 1, Fig. 3 is a diagram explaining the operation of the circuit in Fig. 2, and Fig. 4 is another embodiment. A schematic diagram of an example, FIG. 5 is another electric circuit, and FIG. 6 is a diagram explaining the operation of the electric circuit of FIG. FIG. 7 is a diagram showing the intake pipe negative pressure when the engine is restarted. (11... Engine (2)... Carb reflex (3)... Intake passage (9)... Evaporated fuel passage 00)... Canister (11)... Pump (12)... Check valve (15) Control circuit section (17) Temperature switch Patent applicant Aisan Kogyo Co., Ltd. 252 261ZI A odor voltage Salmon Naoharukuni (Of course

Claims (1)

[Claims] a steam fuel passageway having one end open to an intake passageway of the internal combustion engine;
A fuel vapor removal device for an internal combustion engine, which includes a pump and a check valve provided in the evaporated fuel passage, and a control circuit section that drives the pump for a certain period of time after the engine is stopped.