JPS6033316Y2 - Fuel vapor purge device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fuel vapor purge device used in vehicles such as automobiles.

In vehicles such as cars, in order to prevent air pollution,
The fuel vapor generated in the fuel tank is not released into the atmosphere, but is guided to a fuel vapor adsorption device such as a charcoal canister, and the fuel vapor adsorption device adsorbs and holds the fuel vapor.
That is, it has been conventional practice to store fuel vapor and purge the fuel vapor into the engine intake system during engine operation.

However, when the fuel vapor is purged, the air-fuel ratio of the air-fuel mixture supplied to the engine changes due to the fuel vapor, which may deteriorate engine drivability and exhaust emissions.

In view of the above-mentioned problems, the main object of the present invention is to provide a fuel vapor purge device capable of purging fuel vapor without disturbing the air-fuel ratio of the air-fuel mixture supplied to the engine.

By the way, in engines that have a three-way catalytic converter in the exhaust system, in order to effectively operate the three-way catalytic converter, a signal generated by an exhaust gas sensor such as the 02 sensor that detects the concentration of exhaust components in the exhaust gas is used. Some engines are equipped with an air-fuel ratio control device that feedback-controls the air-fuel ratio of the air-fuel mixture supplied to the engine and maintains the air-fuel ratio at an air-fuel ratio near the stoichiometric air-fuel ratio.

A detailed object of the present invention is to provide a fuel vapor purge system that effectively utilizes the air-fuel ratio control system as described above to achieve the above-mentioned main objectives.

According to the present invention, these purposes include a fuel vapor purge device that guides stored fuel vapor to the engine intake system, a valve device provided in the middle of the fuel vapor purge passage, and an air-fuel ratio control device that operates. This is achieved by a fuel vapor purge device characterized in that it has a control device that opens the valve device only when the fuel vapor purge device is opened.

According to this configuration, the fuel vapor is purged while the air-fuel ratio of the air-fuel mixture supplied to the engine is feedback-controlled by the air-fuel ratio control device, so that fluctuations in the air-fuel ratio due to the purged fuel vapor are prevented. is compensated by the feedback control, and the air-fuel ratio of the air-fuel mixture supplied to the engine is maintained approximately at the target air-fuel ratio regardless of changes in the purge amount of fuel vapor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram showing one embodiment of an engine equipped with a fuel vapor purge device according to the present invention.

In the figure, reference numeral 1 indicates an engine, and the engine sucks a mixture of air and fuel into a fuel chamber 6 through an intake system 5 that includes an air cleaner 2, a carburetor 3, and an intake manifold 4. The exhaust gas produced by the combustion of gas is discharged into the atmosphere through an exhaust manifold 7, an exhaust pipe 8, and a three-way catalytic converter 9 provided in the middle.

A throttle valve 10 is provided midway through the intake system 5 to control the flow rate of the air-fuel mixture supplied to the engine 1.

The carburetor 3 is adjusted to generate an air-fuel mixture having an air-fuel ratio smaller than the stoichiometric air-fuel ratio.

The intake manifold 4 is provided with an additional air supply port 11, and the additional air supply port 11 is provided with a carburetor 3.
Air is supplied through the air conduit 12 and an air control valve 13 provided in the middle thereof.

The air control valve 13 includes a valve element 14 that controls the flow rate of additional air supplied to the intake manifold 4 from the additional air supply port 11, and the valve element 14 is connected to a solenoid 15.
The valve is opened when the solenoid 15 is energized.

16 indicates a control device.

The control device 16 receives the signal generated by the 02 sensor 17 installed in the exhaust manifold 7, and after the 02 sensor 17 is loosened, the control device 16 receives the signal generated by the 02 sensor 17 installed in the exhaust manifold 7. Based on the signal generated by the 02 sensor 17, a pulse signal (feedback control signal) is generated to operate the air control valve 13 so that the air-fuel ratio of the air-fuel mixture supplied to the engine becomes near the stoichiometric air-fuel ratio, and the pulse signal A signal is output to the solenoid 15.

Reference numeral 1B indicates a fuel tank storing liquid fuel, and the liquid fuel stored in the fuel tank is supplied to the carburetor 3 via a fuel passage not shown in the figure.

The upper space of the fuel tank 18 is connected via a conduit 19 to a fuel vapor adsorption device 20 such as a charcoal canister, and the fuel vapor generated within the fuel tank 18 is led to the fuel vapor adsorption device 20 via the conduit 19, where the fuel vapor is It is designed to be adsorbed and held in a vapor adsorption device.

Further, the fuel vapor adsorption device 20 is connected to a purge port 22 provided in the intake manifold 4 via a fuel vapor purge conduit 21.
It is connected to the.

A solenoid valve 23 is provided in the middle of the fuel vapor purge passage 21 to selectively open and close the conduit.

The operation of the solenoid valve 23 is controlled by the control device 16,
The valve is opened only when the control device 16 outputs a feedback control signal to the solenoid 15, in other words, only when the air-fuel ratio of the air-fuel mixture supplied to the engine 1 is under feedback control.

FIG. 2 shows one embodiment of an electrical circuit for controlling a solenoid valve that is incorporated within the control device 16. As shown in FIG.

The feedback control signal is input to the terminal a of this electric circuit, and the terminal A is connected to the cathode of a power supply circuit (not shown), and the terminal C is connected to the anode of the power supply circuit.

A feedback control signal input to terminal a is applied to a capacitor 30, a diode 31, a resistive element 32, and a base terminal of a light transistor 33.

The output terminal of the diode 31 is connected to a terminal via a capacitor 34 and a resistive element 35 which are connected in parallel with each other.

Further, the terminal A is connected to the terminal a via the diode 36 and the capacitor 30.

The collector terminal of the transistor 33 is connected to the terminal C through the resistor element 37 and the ignition key switch 38, and the emitter terminal is connected to the other transistor 40 through the resistor 39.
are connected to the base terminals of each.

The collector terminal of the transistor 40 is connected to the terminal C via the parallel circuit of the solenoid 41 and the diode 42 of the electromagnetic valve 23 and the ignition key switch 38, and the emitter terminal is connected to the terminal C.

The solenoid 41 is energized when a voltage higher than a predetermined value is applied to the base terminal of the transistor 40 and its collector terminal and emitter terminal are brought into conduction, and when the ignition key switch 38 is closed. It has become.

The feedback signal that the control device 16 outputs to the solenoid 15 is generally a pulse signal, and this pulse signal is applied to the terminal a.

When the pulse signal is on, a voltage necessary for operating the transistor 33 is applied to the base terminal of the transistor 33, and the transistor enters an on state in which the collector terminal and the emitter terminal are connected.

Therefore, if the ignition key switch 38 is closed at this time, the voltage necessary to operate the transistor is applied to the base terminal of the transistor 40.
The transistor also turns on.

Also, at this time, the capacitor 34 is charged.

When the pulse signal is off, the capacitor 34 discharges through the resistive element 35, but under normal feedback control, the capacitor 34 is not completely discharged during the off period of the pulse signal, and the transistor 33 is always discharged. capacitor 3 so that it has the necessary charge to operate the
The capacitance of the transistor 4 and the resistance value of the resistive element 35 are predetermined, so that the transistor 33 remains on under normal feedback control.

Therefore, under normal feedback control, the solenoid 44 is connected and energized, and the solenoid valve 23 is opened.

When the feedback control is stopped, a pulse signal is no longer applied to terminal a, and an off signal is continuously applied, so that the charge necessary to operate the transistor is no longer applied to the base terminal of the transistor 33. The transistor is turned off.

Therefore, at this time, the solenoid 41 is not energized and the solenoid valve 23 is closed.

As is clear from the above description, according to the present invention, only when the air-fuel ratio of the air-fuel mixture supplied to the engine is under feedback control, the fuel vapor purge passage is in communication and the fuel vapor is adsorbed by the fuel vapor adsorption device. Since the fuel vapor is purged, the air-fuel ratio of the air-fuel mixture supplied to the engine is not disturbed by the purged fuel vapor.

Although the present invention has been described in detail with respect to specific embodiments above, it will be appreciated by those skilled in the art that the present invention is not limited to this and that various embodiments are possible within the scope of the present invention. It should be obvious.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of an engine equipped with a fuel vapor purge device according to the present invention, and FIG. 2 is an electric circuit diagram showing an electric circuit for controlling a solenoid valve. 1... Engine, 2... Air cleaner, 3... Carburetor, 4... Intake manifold, 5... Intake system, 6... ... combustion chamber,
7... Exhaust manifold, 8... Exhaust pipe, 9... Three-way catalytic converter, 10...
...Throttle valve, 11...Additional air supply port, 12...Air conduit, 13...
Air control valve, 14... Valve element, 15...
・Solenoid, 16...Control device, 17...
...-02 sensor, 18...fuel tank, 19
... Conduit, 20 ... Fuel vapor adsorption device, 21 ... Fuel vapor purge conduit, 22 ...
...Purge port, 23...Solenoid valve, 30...
... Capacitor, 31 ... Diode, 3
2... Resistance element, 33... Transistor, 34... Capacitor, 35... Resistance element, 36... Diode, 37... ...
- Resistance element, 38... Ignition key switch, 39... Resistance element, 40... Transistor, 41... Solenoid, 42...
···diode.

Claims (1)

[Scope of utility model registration request] A fuel vapor purge device for an engine equipped with an air-fuel ratio control device that feedback-controls the air-fuel ratio of a mixture supplied to the engine based on a signal generated by an exhaust gas sensor that detects the concentration of exhaust components in exhaust gas, A fuel vapor purge passage that guides stored fuel vapor to the engine intake system, a valve device provided in the middle of the fuel vapor purge passage, and the valve device opens only when the air-fuel ratio control device is operating. 1. A fuel vapor purge device comprising: a control device for controlling