JPS60175757A - Vapored fuel controller for internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent an air-fuel ratio from being thickened so much, by closing a purge control valve or cutting off a vapored fuel feed passage at a driving range where a suction air quantity is little under broiling weather, and thereby stopping a purge to a suction system of vapored fuel at a canister. CONSTITUTION:A device bearing the above caption connects a storage chamber 10 of a canister 9 to a suction passage 5 at the downstream side of a throttle valve 3 through a vapored fuel feed passage 13 and installs a diaphragm type purge control valve 14 to be opened in time of partial load driving when suction pressure comes strong. In this case, a solenoid valve 25 is installed alongside in the point midway in a pressure signal passage 16 connecting a throttle chamber 4 of a pressure chamber 15 to a position proximate to the throttle valve 3. And, this solenoid valve 25 is controlled by a control unit 22 so as to be opened in time of engine starting when suction air temperature is above the setting value and suction flow is below the setting one, according to each signal out of a temperature sensor 23 and an air flow meter 2 being inputted in advance for driving a fuel injection valve 21.

Description

[Detailed description of the invention] (Technical field) -1- The present invention relates to an evaporated fuel control device for an internal combustion engine.

(Background and prior art) In general, in internal combustion engines for automobiles, as part of exhaust gas countermeasures, the above-mentioned It is equipped with an evaporative fuel control device that returns evaporative gas to the engine for combustion processing.

Conventionally, as this type of evaporative fuel control device, there is a device as shown in FIG. 1, for example, for an engine equipped with an electronically controlled fuel injection device (see Japanese Patent Laid-Open No. 143155/1983).

Air taken in from the air cleaner 1 first passes through an air flow meter 2, the flow rate is measured, and then passes through a throttle chamber 4 equipped with a throttle valve 3, and then from an intake manifold 5 to each combustion chamber of the engine body 6. Supplied.

The air chamber 8 of the fuel tank 7, which is the fuel evaporation source of the engine, and the storage chamber 10 filled with an adsorbent such as activated carbon of the canister 9 are connected to a passage 12 having a separator 11 in the middle thereof. The evaporated fuel generated in the fuel tank 7 after engine operation is stopped is sent to the canister 9, where it is temporarily adsorbed and stored.

Further, the storage chamber 10 of the canister 9 and the intake passage (intake manifold) 5 downstream of the throttle valve 3 are connected by an evaporated fuel supply passage 13, and the supply passage 13 is connected to the throttle valve 3.
The conduction is controlled by a diaphragm type purge control valve 14 that operates during partial load operation when the negative pressure in the downstream intake passage 5 becomes strong.

In other words, the purge control valve 14 responds to the negative pressure (VC negative pressure) in the vicinity of the throttle valve 3 introduced into the pressure chamber 15 via the pressure signal passage 16, and the pressure chamber 15 is When the negative pressure inside increases, the diaphragm 17 moves upward in the figure, and as a result, the valve body 18 integrated with the diaphragm 17 opens one valve port of the vaporized fuel supply passage 13 located above.

-3- Therefore, when the throttle valve 3 is controlled to close in the low and medium load range of the engine and the pressure near the throttle valve 3 in the intake passage 5 becomes high negative pressure, the purge control valve 14 is closed as described above. When the valve is opened, the vaporized fuel supply passage 13 is conducted.

As a result, suction negative pressure downstream of the throttle valve 3 acts on the storage chamber 10 of the canister 9 through the supply passage 13, and this suction negative pressure causes the adsorbed fuel in the storage chamber 10 to be transferred to the canister 9.
The air is introduced into the intake passage 5 through the supply passage 13 together with the atmospheric air that has passed through the filter medium 20, and is thereby supplied to each combustion chamber of the engine body 6 where it is combusted.

In this way, the combustion of the evaporated fuel is started appropriately depending on the operating state of the engine, so that problems such as air pollution caused by the evaporated fuel being released into the atmosphere do not occur.

In the figure, reference numeral 21 denotes an electromagnetic fuel injection valve that is driven and controlled by a control circuit 22, which will be described later, to inject the fuel required by the engine.

In other words, the control circuit 22 controls the air flow meter 4.
- Temperature sensor 23 that calculates the basic fuel injection amount (pulse width) based on the intake air amount signal input from the controller 2 and the engine rotation speed signal input from the ignition coil (not shown), and further detects the intake air temperature based on the basic fuel injection amount (pulse width) After correcting the position of the throttle valve 3 according to the engine operating condition based on the signal from the throttle valve switch 24 etc. that detects the position of the throttle valve 3, a pulse signal (drive signal) is sent to the fuel injection valve 21 in synchronization with the engine rotation. Output. As a result, the amount of fuel required by the engine is injected from the fuel injection valve 21, and a mixture having a predetermined air-fuel ratio is supplied to the engine body 6.

However, in such a conventional evaporated fuel control device, in the uni purge control valve 14, the VC negative pressure in the throttle chamber 3 causes the canister 9 to
Since the system controls the purge (M removal) of the evaporated fuel in the engine and introduces the evaporated fuel from the canister 9 into the intake manifold 5 in the low and medium load range of the engine, a large amount of evaporated fuel enters the canister 9 due to flame heating. If the throttle valve 3 is suddenly operated under conditions where the
= 5 - A large amount of evaporated fuel is instantaneously supplied to the engine body 6, which causes the air-fuel ratio to become overrich, causing the engine to stall.

(Objective of the Invention) This invention has been made by paying attention to such conventional problems, and aims to effectively avoid engine stalling caused by evaporated fuel under flaming heat.

(Structure and operation of the invention) In order to achieve the above object, the present invention provides an evaporative fuel control device as described above, which includes a solenoid valve that controls the opening/closing of the pressure signal passage or the evaporative fuel supply passage of the purge control valve, and A temperature sensor that detects the intake air flow rate and a flow rate sensor that detects the intake flow rate are provided, and when the intake air temperature is above the set value and the intake flow rate is below the set value based on the signals from the above two sensors, the solenoid valve is closed. A control circuit that outputs a signal is provided, and the purge control valve is forcibly closed or the evaporated fuel supply passage is cut off in an operating region where the amount of intake air is small under flaming heat.

(Embodiment) Next, an embodiment of the present invention will be described using FIG. 2, in which the same members as in FIG. 1 are given the same reference numerals and detailed explanations will be omitted.

In this embodiment, first, a solenoid valve 25 that controls the opening and closing of the passage 16 is installed in the middle of the pressure signal passage 16 that connects the pressure chamber 15 of the purge control valve 14 and the vicinity of the throttle valve 3 of the throttle valve 4. Can be set up.

The electromagnetic valve 25, like the fuel injection valve 21, is driven and controlled by a signal from the control circuit 22.

In other words, the control circuit 22 detects the engine operating state in which the intake air humidity is above the set value and the intake air flow is below the set value, based on signals from the temperature sensor 23 and the air flow meter 2 that have been input in advance to drive the fuel injection valve 21. When detected, the electromagnetic valve 25 is energized to avoid closing it.

Because of this configuration, under flaming heat (for example, the intake air temperature is 33℃)
℃ or higher), the solenoid valve 25 is closed by the signal from the control circuit 22 as described above, so the pressure saw signal passage 16 is closed.
is blocked.

This causes the purge control valve 14 to supply VC to its pressure chamber 15.
Since no negative pressure is applied, the valve is closed and the evaporative fuel I supply passage 13 is cut off.

As a result, vaporized fuel is not purged from the canister 9 into the operating range, preventing the air-fuel ratio from becoming overrich due to purging into the operating range, thereby preventing engine stalling.

On the other hand, when the intake air amount increases from the above state and exceeds the set value, or when the intake air temperature decreases and falls below the set value, the solenoid valve 25 is closed with a certain time delay, Pressure signal path 16 is made conductive.

As a result, the purge control valve 14 opens and closes according to the VC negative pressure, and opens in the low to medium load range where the VC negative pressure increases as before, and purges the evaporated fuel from the canister 9 into the intake manifold 5. The combustion process is carried out in the engine body 6. Of course, the same effect occurs even if the conditions described above are initially met.

In this embodiment, the pressure signal passage 16 is opened and closed by the solenoid valve 25 described above, but the evaporated fuel supply passage 1
It goes without saying that opening/closing control may be performed on the opening/closing of the opening/closing section 3. Further, according to this embodiment, since the control circuit 22 described in the outline can be used in its entirety, there is an advantage that the cost can be reduced.

(Effects of the Invention) As explained above, according to the present invention, in an operating region where the amount of intake air is small under flaming heat, the purge control valve is forcibly closed or the vaporized fuel supply passage is cut off, and the canister is Since the purge of evaporated fuel to the intake system is stopped in the above-mentioned operation range, over-rich air-fuel ratio can be prevented and engine stall can be effectively avoided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a conventional example, and FIG. 2 is a schematic diagram of an embodiment of the present invention. -9- 7... Fuel tank, 9... Canister, 3... Throttle valve, 5... Intake manifold, 13... Evaporated fuel supply passage, 14... Purge control valve, 16...・Pressure signal passage, 25... Solenoid valve, 23... Temperature sensor, 2
...Air flow meter, 22...Control circuit. Patent applicant Nissan Motor Co., Ltd. -10-

Claims (1)

[Claims] A canister that stores evaporated fuel generated in a fuel tank, etc., an evaporated fuel supply passage that connects this canister and the intake passage downstream of the throttle valve, and a evaporated fuel supply passage that responds to the angular pressure inside the intake passage near the throttle valve. An evaporated fuel control device for an internal combustion engine comprising a purge control valve that controls the opening and closing of the purge control valve, an NI & valve that controls the opening and closing of the pressure signal passage or the evaporated fuel supply passage of the purge control valve, and a temperature sensor that detects intake air temperature. and a flow rate sensor that detects the intake flow rate, and a control circuit that outputs a close signal to the solenoid valve when the intake air temperature is above a set value and the intake flow rate is below the set value based on signals from both of the above sensors. An evaporated fuel control device for an internal combustion engine, characterized in that it is provided with: