JPH08291733A - Evaporating fuel control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To prevent the rapid change in an air-fuel ratio by providing a control means to control operation of a means to feed fuel to an internal combustion engine so that the air-fuel ratio of an internal combustion engine is smoothly changed when the internal combustion engine is brought into idle operation. CONSTITUTION: A control means 42 inputs signals from intake air temperature and water temperature sensors 44 and 46, an idle switch 50, and a car speed sensor 52. When a car speed satisfies a condition of V <= a car speed constant, a condition wherein the idle switch 50 is switched from OFF to ON, and a condition of a cooling water temperature THW >= a water temperature constant, the purge valve of an evaporating fuel feed device being one of means to feed fuel to an internal combustion engine is not switched OFF but the purge valve is steppedly gradually closed to steppedly decrease a purge amount. This constitution smoothly changes an air-fuel ratio, prevents the generation of a shock, and prevents a driver from feeling displeasure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel control system for an internal combustion engine, and more particularly to an evaporative fuel control system for an internal combustion engine capable of preventing a rapid change in air-fuel ratio when the internal combustion engine is in an idle operation.

[0002]

2. Description of the Related Art In a vehicle, a fuel supply device including a fuel injection valve, a fuel supply passage and the like is provided as one means for supplying fuel from a fuel tank to an internal combustion engine, and evaporation generated in the fuel tank is also provided. There is an evaporative fuel control device (evaporation system) as another means for supplying the fuel to the internal combustion engine by separating (purging) the fuel during operation of the internal combustion engine.

In this evaporative fuel control system, as shown in FIG. 8, the evaporation passage 2 communicating with the inside of the fuel tank 202 is used.
04 and a purge passage 212 communicating with an intake passage 210 on the downstream side of the throttle valve 208 in the intake system of the internal combustion engine 206, which is generated in the fuel tank 202 while the internal combustion engine 206 is stopped and is guided to the evaporation passage 204. A canister 216 is provided which adsorbs and holds the evaporated fuel that has been adsorbed and holds the evaporated fuel that has been adsorbed and held by the atmosphere introduced from the atmosphere communication passage 214 and supplies it to the intake passage 210 from the purge passage 212 during operation of the internal combustion engine 206. There is. Purge passage 21
A purge valve (2-way solenoid valve) 218 that controls the amount of evaporated fuel (purge amount) to the intake passage 210 according to the operating state of the internal combustion engine 206 is provided in the middle of 2. The purge valve 218 has a control means (ECU) 22.
The duty is controlled so that the purge passage 212 is opened and closed by 0.

The control means 220 includes an internal combustion engine 206.
Idle switch 22 that turns on when the vehicle becomes idle
2, a vehicle speed sensor 224 for detecting the vehicle speed, and the throttle valve 20.
A throttle position sensor 226 for detecting the throttle opening, which is the opening of No. 8, is connected.

The control means 220 receives signals from various sensors and turns on / off the purge valve 218 while the evaporated fuel adsorbed by the canister 216 is not impaired while the vehicle is running ( (Between a and b in FIG. 9), the purge amount of the evaporated fuel to the intake passage 210 side is controlled and supplied to the internal combustion engine 206.

Further, the control means 220 uses the internal combustion engine 206.
When the throttle is fully closed (indicated by time b in FIG. 9) during the idle operation of the vehicle or while the vehicle is traveling, the purge valve 218 is turned off and the purge control is stopped.

As such an evaporated fuel control device, for example, JP-A-6-280690 and JP-A-1-19 are available.
It is disclosed in Japanese Patent No. 5961. JP-A-6-2806
No. 90 publication discloses that when the range of the automatic transmission is the D range and the idle switch is turned on,
If the vehicle speed of the vehicle exceeds the set vehicle speed, the introduction of evaporated fuel into the intake passage is prohibited, so that the air-fuel ratio of the air-fuel mixture in the combustion chamber of the engine is maintained at an appropriate air-fuel ratio according to the operating state of the engine. Therefore, in the creep running state where the vehicle speed of the vehicle exceeds a predetermined vehicle speed, even if a brake operation is performed to stop the vehicle, for example, the engine can be operated stably without causing an engine stall. It is what makes me. Japanese Patent Laid-Open No. 1-1959
The one disclosed in Japanese Patent No. 61 discloses a control in a steady operation of an engine, which increases the passage area of an evaporated fuel supply passage to the throttle valve downstream side of an intake passage in accordance with an increase in intake air amount, during acceleration operation. Then, by gradually increasing the passage area of the evaporated fuel supply passage after the increase of the intake air amount, the intake negative pressure downstream of the throttle valve increases with respect to the increase of the intake air amount during the acceleration operation of the engine. It is intended to improve the drivability of the engine by suppressing the excessive supply of the evaporated fuel due to the delay.

[0008]

By the way, in the conventional fuel vapor control apparatus, there is no problem because the purge control is stopped during the idling operation of the internal combustion engine, that is, when the idle switch is turned on. When the temperature is high,
Further, when the throttle is fully closed while the vehicle is traveling at a low speed and a low throttle opening, that is, when the idle switch is turned off as shown in FIG. 9, the purge valve is instantly turned off and the purge amount is rapidly increased. Since it decreases (indicated by C1 in FIG. 9), the air-fuel ratio changes abruptly (indicated by C2 in FIG. 9), which causes a shock and gives an inconvenience to the driver. .

[0009]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention is provided between an evaporation passage communicating with the inside of a fuel tank and a purge passage communicating with an intake passage of an intake system of an internal combustion engine. The evaporated fuel that is generated in the fuel tank when the internal combustion engine is stopped and is guided to the evaporation passage is adsorbed and held, and the evaporated fuel that is adsorbed and held by the atmosphere introduced from the atmosphere communication passage while the internal combustion engine is operating. And a purge valve for controlling the amount of evaporated fuel to the intake passage in accordance with the operating state of the internal combustion engine. In an evaporated fuel control device for an engine, fuel is supplied to the internal combustion engine so that the air-fuel ratio of the internal combustion engine changes smoothly when the internal combustion engine is in idle operation. Characterized in that a control means for operation control means.

[0010]

According to the structure of the present invention, the control means operates the means for supplying fuel to the internal combustion engine to smoothly change the air-fuel ratio when the internal combustion engine is in the idle operation. As a result, it is possible to prevent the air-fuel ratio from changing rapidly and to avoid the occurrence of shock.

[0011]

Embodiments of the present invention will be described in detail and specifically with reference to the drawings. 1 to 5 show a first embodiment of the present invention. In FIG. 5, 2 is an internal combustion engine mounted on a vehicle, 4 is an intake manifold, 6 is an intake passage,
8 is a surge tank, 10 is a throttle valve, 12 is an air cleaner, and 14 is a fuel tank. A fuel pump 16 is provided in the fuel tank 14. One end of a fuel supply passage 18 is provided in communication with the fuel pump 16. The other end of the fuel supply passage 18 is provided so as to communicate with a fuel injection valve 20 installed in the intake manifold 4 so as to inject fuel into the internal combustion engine 2. The fuel pump 16, the fuel supply passage 18, and the fuel injection valve 20 constitute a fuel supply device 22 which is one of means for supplying fuel to the internal combustion engine 2.

Between the fuel tank 14 and the intake system of the internal combustion engine 2, an evaporated fuel control device (evaporation system) 24 which is another means for supplying fuel to the internal combustion engine 2 is provided.

In the evaporated fuel control device 24, as shown in FIG. 5, the purge passage 26 having one end side communicating with the inside of the fuel tank 14 and the other end side and one end side communicating with the surge tank 8 constituting the intake passage 6 are purged. A canister 30 is provided between the other end of the passage 28. One end side of the evaporation passage 26 is provided so as to communicate with the inside of the fuel tank 14. The other end side of the evaporation passage 26 and the other end side of the purge passage 28 are arranged side by side in the upper portion of the canister 30 and open. Further, the canister 30 has an atmosphere communication passage 3
One end side of 2 is provided in communication. An air cut valve (2-way solenoid valve) 34 for opening and closing the atmosphere communication passage 32 is provided on the other end side of the atmosphere communication passage 32.

The canister 30 adsorbs and holds the vaporized fuel generated in the fuel tank 14 while the internal combustion engine 2 is stopped and guided to the evaporation passage 26, and also from the atmosphere communication passage 32 during operation of the internal combustion engine 2. The evaporated fuel adsorbed and held by the introduced atmosphere is separated and supplied from the purge passage 34 to the intake passage 6.

In the middle of the purge passage 28, a purge valve (2-way solenoid valve) for controlling the purge amount, which is the amount of evaporated fuel to the intake passage 6, according to the operating state of the internal combustion engine 2.
36 are provided. The purge valve 36 is duty-controlled by the control means 42 described later.

An upper end portion of the fuel tank 14 is provided with one end of a detection pressure passage 38 in communication therewith. A pressure sensor 40 that detects the tank internal pressure of the fuel tank 14 is provided on the other end side of the detection pressure passage 38.

The fuel injection valve 20, the air cut valve 34, the purge valve 36, and the pressure sensor 40 constitute a control means (ECU) 4
I have contacted 2.

As shown in FIG. 4, the control means 42 includes
On the input side, an intake air temperature sensor 44 for detecting the intake air temperature, a water temperature sensor 46 for detecting the cooling water temperature of the internal combustion engine 2, an air flow meter 48 for detecting the intake air flow rate, and are turned on when the internal combustion engine 2 is in idle operation. Idle switch 50
And a vehicle speed sensor 52 for detecting the vehicle speed, and a throttle position sensor 54 for detecting the throttle opening, which is the opening state of the throttle valve 10, are provided in communication with each other, and a fuel injection valve (injector) is provided on the output side. ) 20 and the purge valve 36 are provided in communication with each other.

The control means 42 inputs signals from various sensors and supplies fuel to the internal combustion engine 2 so that the air-fuel ratio of the internal combustion engine 2 changes smoothly when the internal combustion engine 2 is in idle operation. The means for controlling the operation is controlled.

More specifically, in this first embodiment,
As shown in FIG. 2, the control means 42 includes an intake air temperature sensor 44, a water temperature sensor 46, an idle switch 50, and a vehicle speed sensor 5.
2 and each signal is input, and the vehicle speed (V) is V ≦ vehicle speed constant (V ₁ : 20 〓 / h) and the idle switch 50 is switched from OFF to ON (OFF →
ON), the cooling water temperature (THW) is THW ≧ water temperature constant (THW ₁ : for example, 80 ° C.), and the intake air temperature (THA) is THA ≧ intake temperature constant (THA ₁ : for example, 40 ° C.). An evaporative fuel supply device 24 which is one of means for supplying fuel to the internal combustion engine 2 when a certain condition is satisfied.
The purge valve 36 is closed stepwise so that the air-fuel ratio of the internal combustion engine 2 changes smoothly, and the purge amount to the intake passage 6 side is gradually reduced.

Next, the operation of the first embodiment will be described based on the flowchart of FIG.

When the program of the control means 42 is started (step 102), first, the cooling water temperature (THW) ≧
It is determined whether or not the water temperature constant (THW ₁ ) and the intake air temperature (THA) ≧ the intake air temperature constant (THA ₁ ) (step 10).
4).

If YES at step 104,
It is determined whether or not vehicle speed (V) ≦ vehicle speed constant (V ₁ ) (step 106).

If YES at step 106,
It is determined whether the idle switch 50 is switched from off to on (step 108).

If YES at step 108,
The latest purge control amount (Pi) is set to the purge amount (P) when the idle switch 50 is switched from off to on, that is, Pi = P (step 110).

Then, it is judged whether or not a predetermined time (Δtsec) has elapsed after sampling the latest value of the purge control amount (Pi) (step 112). This step 11
If NO in 2, return to step 110.

If YES at step 112,
The latest purge control amount (Pi) is Pi = P (i _-1 )
(Previous purge amount) -D (constant) (step 11
4).

The purge control amount (Pi) is Pi =
It is determined whether it is 0 (step 116).

If NO at step 116, the process returns to step 112.

If YES at step 116,
The program is returned (step 118).

The steps 104, 106 and 10
If NO in 8 respectively, the program is immediately returned (step 118).

As a result, as shown in FIG. 3, the purge valve 36
Is activated (indicated by a in FIG. 3), purge control is performed,
Then, when the idle switch 50 is switched from off to on (shown by b in FIG. 3) and the internal combustion engine 2 is in the idle operation, the purge valve 36 is immediately turned off at the moment when the idle switch 50 is turned off. Instead, the purge valve 36 is gradually closed to gradually decrease the purge amount (shown between A1 and b to c in FIG. 3), thereby smoothly changing the air-fuel ratio ( As shown by A2 in FIG. 3), it is possible to prevent a shock from occurring and avoid causing the driver to feel uncomfortable.

Further, in the first embodiment, the air-fuel ratio can be changed smoothly only by changing the program of the control means 42, no additional device is required, and the structure can be simplified. Can be cheaper.

6 and 7 show a second embodiment of the present invention.

In the second embodiment, the parts having the same functions as those in the first embodiment will be described with the same reference numerals.

The features of the second embodiment are as follows. That is, in this second embodiment, as shown in FIG.
As shown in, the control means 42 inputs respective signals from the intake air temperature sensor 44, the water temperature sensor 46, the idle switch 50, the vehicle speed sensor 52, and the throttle position sensor 54, and the vehicle speed (V) is V ≦ vehicle speed constant ( V ₁ : For example, 20〓
/ H), the condition that the idle switch 50 is switched from off to on, and the cooling water temperature (THW) is TH
The condition that W ≧ water temperature constant (THW ₁ : 80 ° C.) and the intake air temperature (THA) are THA ≧ intake air temperature constant (TH
A ₁ : For example, 40 ° C.) and one of the means for supplying fuel to the internal combustion engine 2 when the throttle opening (θ) satisfies, for example, θ ≦ 2 ^o The fuel injection valve 20 of the fuel supply device 22 is set to slightly increase the injection amount of fuel so that the air-fuel ratio changes smoothly when the internal combustion engine 2 is in the idle operation. The amount is increased a little.

According to the configuration of the second embodiment. As shown in FIG. 7, the purge valve 36 is operated (indicated by a in FIG. 7),
At the time when the purge control is performed and the throttle is about to be fully closed, before the idle switch 50 is turned on,
Vehicle speed (V), intake air temperature (THA), cooling water temperature (TH)
W) and other conditions, the idle operation of the internal combustion engine 2 is estimated (shown by B1 and b in FIG. 7), and when the idle switch 50 is turned on, the fuel injection amount is slightly increased so that the air-fuel ratio becomes smooth. However, the shock can be prevented from occurring.

As a result, in the second embodiment, the same effect as that of the first embodiment is obtained, and the idle operation of the internal combustion engine 2 is estimated before the idle switch 50 is turned off. It is possible to further smooth the change in the fuel ratio and effectively prevent the occurrence of shock.

[0039]

As is apparent from the above detailed description, according to the present invention, means for supplying fuel to the internal combustion engine so that the air-fuel ratio of the internal combustion engine changes smoothly when the internal combustion engine is in idle operation. By providing the control means for controlling the operation, it is possible to prevent the air-fuel ratio from abruptly changing and avoid the occurrence of shock.

Further, according to the present invention, the program of the control means may be slightly changed, no additional device is required, the construction can be simplified, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a flowchart of an evaporated fuel control device.

FIG. 2 is a block diagram of control means and each sensor in the first embodiment.

FIG. 3 is a time chart of evaporated fuel control in the first embodiment.

FIG. 4 is a block diagram of a control unit and each sensor.

FIG. 5 is a configuration diagram of an evaporated fuel control device.

FIG. 6 is a block diagram of control means and each sensor in the second embodiment.

FIG. 7 is a time chart of fuel vapor control in the second embodiment.

FIG. 8 is a configuration diagram of a conventional evaporated fuel control device.

FIG. 9 is a time chart of conventional evaporated fuel control.

[Explanation of symbols]

 2 Internal Combustion Engine 14 Fuel Tank 20 Fuel Injection Valve 22 Fuel Supply Device 24 Evaporative Fuel Control Device 26 Evaporative Passage 28 Purge Passage 30 Canister 42 Control Means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display area F02M 25/08 301 F02M 25/08 301H 301M

Claims (1)

[Claims] 1. An evaporation passage, which is generated in the fuel tank during the stop of the internal combustion engine, between the evaporation passage communicating with the inside of the fuel tank and the purge passage communicating with the intake passage of the intake system of the internal combustion engine, A canister is provided which adsorbs and holds the introduced vaporized fuel and releases the vaporized fuel that is adsorbed and held by the atmosphere introduced from the atmosphere communication passage and supplies it to the intake passage from the purge passage while the internal combustion engine is operating. In the evaporated fuel control device for an internal combustion engine, which is provided with a purge valve for controlling the amount of evaporated fuel to the intake passage in accordance with the operating state of the internal combustion engine, when the internal combustion engine is in idle operation Evaporation of an internal combustion engine, characterized in that control means is provided for controlling the operation of the means for supplying fuel to the internal combustion engine so that the air-fuel ratio of the internal combustion engine changes smoothly Fuel control device.