JPS58128438A - Air-fuel ratio controller - Google Patents

Abstract

PURPOSE:To always keep the ratio of fuel to air appropriate, by providing a control valve in an evaporator passage upstream to a canister and by opening the valve when the pressure upstream thereto is higher than a prescribed level and by increasing the ratio depending on the duration of the opening of the valve. CONSTITUTION:One end of an evaporator passage (evaporated fuel passage) 8 is connected to the top of a fuel tank 6 so that the passage communicates with the upper opening 6a in the tank. the other end of the passage 8 is connected to an intake passage 1 downstream to a throttle valve 3. A canister 9 is provided in the halfway part of the passage 8. An atmosphere introducing passage 10 is connected to the bottom of the canister 9. The intake passage 1 is provided with an air passage 12 detouring a venturi part 4 and the throttle valve 3. An air fuel ratio control valve 13 is installed in the halfway part of the air passage 12. A control valve 14 is provided in the evaporator passage 8 upstream to the canister 9. The valves 13, 14 are opened by a calculator circuit 16 when the output of a pressure sensor 15 which detects the pressure of the passage 8 has exceeded a prescribed level.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an air-fuel ratio system that prevents the air-fuel ratio of a mixture from being passively affected by the evaporated fuel in an engine in which evaporated fuel in a fuel tank is supplied to an intake system. It relates to an adjustment device.

Car fuel tanks are generally used to store fuel to be supplied to the engine, but the upper space of the fuel tank is filled with evaporated volatile fuel, and its pressure increases. If the temperature rises too high, the tank may explode, so it is necessary to release the evaporated fuel outside the tank. In this case, a method may be considered in which the evaporated fuel is directly released into the atmosphere, but this method has the drawbacks of causing fuel loss and air pollution.

Therefore, as one of the conventional fuel tanks, after temporarily accumulating the evaporated fuel in the tank in a canister installed outside the tank,
It is supplied to the engine's intake system through the engine's intake negative pressure through the evaporator passage, and the evaporated fuel is released outside the tank to prevent damage to the tank and to prevent fuel loss and air pollution. There is something that has been done (
(See Japanese Patent Publication No. 47-21842).

Incidentally, the amount of fuel released in the fuel tank of a car changes depending on the driving conditions of the car and the outside temperature. For example, while driving, the tank does not become very hot due to excessive wind hitting the fuel tank, and a large amount of fuel does not evaporate in the evening, but under the scorching sun in the summer. If the car is parked for a long time, the fuel tank becomes hot and a large amount of fuel evaporates. In the case of evaporation of high-voltage fuel, most of the evaporated fuel is accumulated in the canister in conventional f-fuel tanks, and when the engine is started in such a state, a large amount of evaporated fuel is supplied to the engine's intake system. It will be done. As a result, the air-fuel ratio of the mixture becomes small, that is, rich, causing a misfire and producing HC in the exhaust gas.

There was a problem that unburned gas such as GO was included in the electricity.

This invention was made in view of the above-mentioned conventional problems.When the content exceeds the evaporator value upstream of the canister, the content closing valve is opened, and the valve opening time, that is, the amount of evaporated fuel supplied to the intake system. By adjusting the air-fuel ratio to a larger value using the air-fuel ratio adjustment device, the air-fuel ratio is always maintained at an appropriate value and the content of unburned gas in the exhaust gas is reduced. The purpose of the present invention is to provide an air-fuel ratio control device that achieves the following.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an air-fuel ratio control device according to an embodiment of the present invention. In the figure, 1 is an intake passage of the engine, the upstream end of the intake passage 1 is connected to an air cleaner 2, and in the middle of the intake passage 1 is a throttle valve that opens in conjunction with an accelerator pedal (not shown). 3 is arranged, and a pentier part 4 is formed upstream thereof. This venturi part 4 is provided with one end of a fuel supply passage 5 open, and the other end of the passage 5 is connected to a float chamber of the carburetor (not shown), and a fuel tank 6 is provided in the float chamber. Fuel 7 is adapted to be supplied.

Further, one end of an evaporator passage (vaporized fuel passage) 8 is connected to the upper surface of the fuel tank 6 in communication with an upper space 6λ inside the tank, and the other end of the passage 8 is connected to a throttle valve 3 of the intake passage 1.
The evaporator passage 8 is connected to the downstream side, and the evaporator passage 8 guides the evaporated fuel in the fuel tank 6 to the intake passage 1. A canister (IFm member) 9 for temporarily storing evaporated fuel is interposed in the middle of the evaporator passage 8, and an atmosphere introduction passage 10 with one end open to the atmosphere is connected to the bottom of the cough canister 9.

The air passage 1 is connected to the intake passage 1 by a partition wall 11.
2 is formed by bypassing the bench area part 4 and the throttle valve 3, and an air-fuel ratio adjusting pulp (air-fuel ratio adjusting device) 13 is disposed in the middle of the core air passage 12 to open and close it. On the other hand, upstream of the canister 9 of the evaporator passage 8, a solenoid valve (opening/closing valve) 14 is provided to open and close the canister 9, and further upstream thereof, a pressure sensor 15 is provided to detect the internal pressure of the evaporator passage 8 upstream of the solenoid valve 14. The detection signal 2 of the pressure sensor 15 is applied to an arithmetic circuit 16. This arithmetic circuit 16 applies a valve opening signal to the solenoid valve 14 when the pressure upstream of the solenoid valve 14 exceeds a predetermined value, and also applies a signal d to the valve when the ignition switch or starter switch is turned on. A control signal C is applied to the fuel ratio adjusting pulp 13.

FIG. 2 shows a specific configuration of the pressure sensor 15 and the calculation circuit 16. In the pressure sensor 15, 17 is a diaphragm device, and the first chamber 17 of the device 17 is connected to the evaporator passage by a pressure introduction passage 18. The pressure on the upstream side of canister 9 of No. 8 is introduced. Diaphragm device 1
A spring member 17d that urges the diaphragm 17c upward in the figure is disposed in the second chamber 17b of the diaphragm 1.
A contact 17e is fixed to the surface of the second chamber 17b of 7C,
A battery 20 is connected by a lead wire 19 between the contact 17C and the ground. Also, the second room 1 above? b A contact 171 is fixed on the inner surface facing the contact 17e,
A lead wire 21. is connected to the contact point 17f. is connected.

Therefore, the diaphragm 17C is pushed downward by the pressure inside the evaporator passage 8 against the spring force of the spring member 17d, so that both the contacts 17e and 17f come into contact with each other, and the current from the battery 20 is transferred to the lead wire 19. Contact In, 17f i
The pressure sensor 15 outputs a detection signal a by flowing through the path of the lead #21.

Further, in the arithmetic circuit 16, 22 is an oscillator that oscillates at a constant frequency, 23 is a first AND circuit that uses the detection signal a of the pressure sensor 15 and the output of the oscillator 22, and 2
4 is a second AND circuit that uses the output of the oscillator 22 and the output of a drive circuit 27 to be described later, and 25 is the first AND circuit.
This is an up/down counter that counts up the output of the circuit 23 and counts down the output of the second AND circuit 24. Further, 26 is a relay operated by a signal d from an ignition switch or a starter switch, 261 is its relay coil, and 26b is its relay contact. When the up/down counter 25 receives the detection signal from the pressure sensor 15 via the relay contact 26b, it applies it to the solenoid valve 14 as a valve opening signal, and also outputs the output from the drive circuit 27 in the circuit 16. is applied to the air-fuel ratio adjusting pulp 13 as a control signal C.

Next, the operation will be explained.

When the engine is stopped, the fuel tank 6 is evaporated and filled with fuel due to the influence of outside air temperature, etc., and when the pressure exceeds a predetermined value, the pressure sensor 15 detects the diaphragm 1.
7C is pushed downward against the spring force of the spring member 17d, and its contacts 17e and 17f come into contact, so that the pressure sensor 15 generates a detection signal a. The arithmetic circuit 16 receives this detection signal and generates a valve opening signal, and the solenoid valve 14 opens while receiving the valve opening signal. The vaporized fuel in the fuel tank 6 is then led to the canister 9 via the evaporator passage 8 and accumulated there. At the same time, in the arithmetic circuit 16, the first AND circuit 23 directly outputs the output pulse of the development oscillator 22 to which the detection signal a of the pressure sensor 15 is added, and the counter 25 counts up the number of passes. The opening time of the solenoid valve 14 is measured. At this time, since the signal d is not applied to the relay 26, its relay contact 26b is open, the output of the counter 25 is not applied to the drive circuit 27, and the output of the second AND circuit 24 is steady. remains at “01”.

When the evaporated fuel is released to the outside of the fuel tank 6 and its pressure drops below a predetermined value, the diaphragm 17C in the pressure sensor 15 is deformed and moved upward by the spring force of the spring member 17d, and the contacts 17e and 17t
is separated, the pressure sensor 15 stops outputting the detection signal, and due to this, the arithmetic circuit 16 stops outputting the valve opening signal and the solenoid valve 14 closes. Since the output of the circuit 23 becomes m O+m, the counter 25 stops its counting operation.

In this way, when the engine is stopped E, whenever the pressure inside the fuel tank 6 exceeds a predetermined value, the solenoid valve 14 opens and the evaporated fuel is discharged from the tank 6 and accumulated in the canister 9, and the arithmetic circuit 16 measures the opening time of the solenoid valve 14.

If you start the engine in this condition, the intake passage 1
, air from the air cleaner 2 is sucked into the passage 1 in an amount corresponding to the opening degree of the throttle valve 3 by the action of the engine's intake negative pressure, and the cough intake air is drawn from the fuel supply passage 5 in the pentier part 4. fuel and is inhaled into the engine.

At that time, the large amount of evaporated fuel accumulated in the canister 9 is also drawn into the intake passage 1 by the effect of the intake negative pressure, so the air-fuel ratio of the mixture may be lower than the appropriate value, that is, it may become rich. There is.

However, in this case, in the arithmetic circuit 16 of the present device,
The relay 26 is actuated by the signal d from the ignition switch or starter switch, and the relay contact 26 is activated.
b is closed, the drive circuit 27 receives the output of the counter 25, generates a signal corresponding to the output value, and performs the second AND
Since the circuit 24 directly outputs the output pulse of the development oscillator 22 which has the output of the drive circuit 27, and the counter 25 counts down the number of pulses, the arithmetic circuit 16 continues to count the pulses until the output of the counter 25 reaches 10゛. A control signal C corresponding to the output of the counter 25 is output.Then, the air-fuel ratio adjustment valve 13 receives this control signal C and adjusts the opening degree according to the signal C to the downstream side of the throttle valve 3 in the intake passage 1. Since the air from the air cleaner 2 is sucked in through the air passage 12 by a flow rate corresponding to the opening time of the solenoid valve 14, that is, the amount of evaporated fuel accumulated in the canister 9, the air-fuel ratio of the mixture becomes small. The value is maintained at an appropriate value.

Furthermore, while the vehicle is running, the fuel tank 6 is hit by the wind, so the temperature of the tank 6 does not rise much, and evaporated fuel does not generate much electricity.

In this case, in this device, when the pressure in the fuel tank 6 changes from below a predetermined value to above a predetermined value, the control circuit 16 receives the detection signal & of the pressure sensor 15 in the same way as described above, and receives a valve opening signal. 4b, the solenoid valve 14 is opened, and the evaporated fuel is transferred to the evaporator passage 8 by the action of the negative pressure in the intake passage 1. At this time, in the calculation circuit 16, the first AND circuit 23 detects the detection signal 1. A pulse is output for a certain period of time, the counter 25 aggregates it, and the drive circuit 27 outputs a control signal C corresponding to the count value of the counter 25. On the other hand, the second AND circuit 24 Since a pulse is output while there is an output, and the counter 25 counts down, the count value of the counter 25 does not become a large value after all, and the output of the drive circuit 27 also does not reach a large value. No. The air-fuel ratio Pille valve 13 loses its color for a while in response to the small control signal C, and a small amount of air enters the air passage 12 in the intake passage 1.
The air-fuel ratio of the air-fuel mixture is maintained at an appropriate value. When the pressure in the fuel tank 6 drops below a predetermined value, the pressure sensor 15 stops outputting the signal &, the arithmetic circuit 16 closes the solenoid valve 14, and the arithmetic circuit 16 closes the solenoid valve 14. The output of the AND circuit 23 becomes '0'''', and the counter 25 also performs the second AND circuit:
The output of the passage 24 is immediately counted down and becomes "O", and as a result, the arithmetic circuit 16 immediately closes the air-fuel ratio adjustment band pulp 13.

In the device of this embodiment as described above, the opening time of the solenoid valve provided in the evaporator passage is measured, and the air-fuel ratio adjustment valve is operated according to this opening time to adjust the amount of air taken into the intake passage. a to make the air-fuel ratio of the mixture much hotter.
＃Because it is made to be luxurious, it is possible to prevent the air-fuel ratio from fluctuating due to evaporated fuel, and as a result, the occurrence of misfires is reduced.
The content of unburned gases such as HC and Co2 in the exhaust gas can be greatly reduced.

Furthermore, when detecting the flow rate of evaporated fuel, if the flow rate is directly detected using an air flow sensor, the evaporated fuel will adhere to the air flow sensor, reducing the detection level and durability of the sensor. While there are limitations regarding the durability and reliability of the device, this device measures the opening time of the solenoid valve and indirectly detects the electricity of the evaporated fuel. Its durability and reliability are very favorable.

In the above embodiment, an air-fuel ratio adjustment valve that adjusts the amount of intake air is used as an air-fuel ratio adjustment device, but this air-fuel ratio adjustment device is intended to increase or decrease the amount of fuel supplied to a portion of the pentier. Good too.

As described above, according to the air-fuel ratio control device according to the present invention,
An on-off valve is provided in the evaporator passage upstream of the canister, and when the pressure upstream of the on-off valve reaches a predetermined value or higher, the on-off valve is opened, and the opening time of the on-off valve is determined according to the amount of evaporated fuel supplied to the intake system. Therefore, the air-fuel ratio adjustment device is used to adjust the air-fuel ratio to a large extent, so that the air-fuel ratio is always maintained at an appropriate value and the electricity of unburned phosphorus gas in the exhaust gas is greatly reduced. It also has the effect of improving the durability and reliability of the device.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an air-fuel ratio control device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of a pressure sensor and an arithmetic circuit of the device. 1...Intake passage 6...Fuel tank 8...
Evaporator passage (evaporated fuel passage) 9... Canister 13... Air-fuel ratio adjustment valve (air-fuel ratio adjustment device) 14... Solenoid valve (on/off valve) 15...
・Pressure sensor 16...Arithmetic circuit patent applicant Toyo Kogyo Co., Ltd. agent Patent attorney Ken Hayase −

Claims (1)

[Claims] +1) A fuel vapor passage, which is provided with one end opening to the fuel tank and the other end opening to the intake passage of the engine, and which guides the evaporated fuel in the fuel tank to the intake passage; 111J! A storage member that temporarily stores fuel, an on-off valve that is provided in the vaporized fuel passage upstream of the cough accumulation member and opens and closes the passage, a pressure sensor that detects the pressure in the vaporized fuel passage upstream of the internuclear closing valve, and a pressure sensor that supplies the fuel to the engine. an air-fuel ratio adjusting device that adjusts the air-fuel ratio of the air-fuel mixture to be mixed; and an air-fuel ratio adjustment device that receives the output of the pressure sensor and opens the on-off valve and opens the on-off valve when the pressure in the vaporized fuel passage upstream of the on-off valve is higher than a predetermined pressure. An air-fuel ratio control device comprising: an arithmetic circuit that controls the air-fuel ratio adjustment device to increase the air-fuel ratio so that the air-fuel ratio is maintained at a proper value even when the air-fuel ratio is increased.