JPH11182370A - Evaporated fuel treatment device of internal combustion engine with supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform canister purge even in a supercharging region. SOLUTION: A supercharged pressure introduction passage 20 which is branched from an intake passage 23 between a throttle valve 3 and a compressor 2 and is communicated with a canister 12 is provided, and a supercharged pressure cut valve 21 is provided in the supercharged pressure introduction passage 20. Furthermore, an atmospheric air cut valve 19 is provided at an atmospheric air introduction port 18 of the canister 12. The atmospheric air cut valve 19 is closed and the supercharged pressure cut valve 21 is opened in a supercharging region to scavenge the canister 12 by supercharged air so that a flow rate of purge air is adjusted by a purge control valve 17 and purge air is supplied to an intake collector part 22 on the downstream side of the throttle valve 3 through a purge passage 14. On the other hand, the atmospheric air cut valve 19 is opened and the supercharged pressure cut valve 21 is closed in a non-supercharging region to perform canister purge by utilizing a negative pressure of suctioned air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel processing apparatus for a supercharged internal combustion engine, and more particularly, to a technique for performing a purge operation in a state where supercharging is performed by a supercharger.

[0002]

2. Description of the Related Art Conventionally, evaporated fuel generated in a fuel tank is temporarily adsorbed on a canister, and the evaporated fuel adsorbed on the canister is utilized by utilizing a differential pressure between atmospheric pressure and suction negative pressure. 2. Description of the Related Art There is known an evaporative fuel processing apparatus having a configuration in which fresh air is purged while being taken in through an air inlet provided in a canister, and the purged air is sucked into an engine and burned (see Japanese Utility Model Laid-Open No. 1-58760). ).

[0003]

In an internal combustion engine equipped with a supercharger, the intake pressure becomes higher than the atmospheric pressure when the supercharger performs supercharging. Therefore, there is a problem in that the purge air cannot be supplied using the differential pressure, and the conditions for performing the purge are limited to a narrow region on the low load side where the suction negative pressure can be generated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an evaporative fuel processing apparatus for a supercharged internal combustion engine capable of supplying purge air even in a supercharged state.

[0005]

Therefore, according to the first aspect of the present invention, the evaporated fuel generated from the fuel tank is adsorbed and collected in the canister, and the evaporated fuel adsorbed and collected in the canister is supplied to the engine of the engine through the purge passage. An evaporative fuel processing apparatus for a supercharged internal combustion engine configured to be supplied into an intake passage and burned, wherein the canister is scavenged by intake air supercharged by a supercharger, and the scavenged exhaust gas is discharged through the purge passage. Evaporated fuel is supplied into the intake passage of the engine.

According to this configuration, the supercharged intake air having a pressure higher than the atmospheric pressure is sent into the canister and scavenged, thereby purging the evaporated fuel. Even in the supercharged state, the purge air is purged. Can be made possible. According to the second aspect of the present invention, the evaporated fuel generated from the fuel tank is adsorbed and collected in the canister, and the evaporated fuel adsorbed and collected in the canister is supplied into the intake passage of the engine via the purge passage for combustion. An evaporative fuel processing apparatus for a supercharged internal combustion engine, comprising a supercharger upstream of a throttle valve and connecting the purge passage to an intake passage downstream of the throttle valve. A supercharging pressure introducing passage for guiding a part of the intake air from the intake passage downstream of the feeder and upstream of the throttle valve to the canister; and a supercharging pressure cut valve interposed in the supercharging pressure introducing passage. And wherein the supercharging pressure cut valve is opened when the intake pressure downstream of the throttle valve is equal to or higher than a predetermined value.

[0007] According to this configuration, a supercharging pressure introduction passage is provided for guiding the intake air supercharged from the upstream side of the throttle to the canister. When the intake pressure on the downstream side of the throttle valve is equal to or higher than a predetermined value, that is, when the pressure on the downstream side of the throttle valve becomes positive due to supercharging and the suction of the purge air cannot be performed due to the pressure difference from the atmospheric pressure, the excess The supercharged intake air is introduced into the canister by opening the supercharging pressure cut valve interposed in the supply pressure introducing passage, and the canister is scavenged with the supercharged intake air to supply purge air to the engine. .

According to the third aspect of the present invention, a check valve is provided at the fresh air inlet to prevent a backflow from the fresh air inlet of the canister. According to this configuration, when introducing the supercharged intake air to the canister, only the flow from the atmosphere side into the canister is prevented so that the purge air does not flow back into the atmosphere via the fresh air inlet of the canister. An allowable check valve (one-way valve) is provided at the fresh air inlet, and when the purge air is normally sucked into the intake passage by the suction negative pressure, the fresh air is introduced into the canister through the check valve. On the other hand, when the supercharged intake air is introduced into the canister and the pressure in the canister increases,
The purge air in the canister is prevented from being discharged into the atmosphere through the fresh air inlet.

In the invention according to claim 4, when the boost pressure cut valve is opened, the atmosphere cut valve interposed at the fresh air inlet of the canister is closed. According to such a configuration, in a supercharging state in which the intake pressure downstream of the throttle valve is equal to or higher than a predetermined value, and when the canister is scavenged with the supercharged intake air by opening the supercharging pressure cut valve, fresh air is introduced into the canister. The air cut valve provided in the mouth is closed to prevent the purge air from flowing back into the atmosphere through the fresh air inlet.

[0010]

According to the first aspect of the present invention, the canister is scavenged by the intake air supercharged by the supercharger, so that the pressure on the canister side is increased even in the supercharged state to purge the engine with purge air. There is an effect that it becomes possible to supply the air to the intake passage. According to the second aspect of the invention, in a supercharging state in which the intake pressure on the downstream side of the throttle valve is higher than the atmospheric pressure and the canister purging using the differential pressure between the atmospheric pressure and the intake pressure cannot be performed, the intake pressure from the upstream side of the throttle valve is increased. There is an effect that purging can be performed by guiding the supercharged intake air to the canister.

According to the third or fourth aspect of the present invention, even if supercharged intake air is introduced into the canister, it is possible to prevent the purge air from being released into the atmosphere from the air inlet of the canister.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is a system diagram of a supercharged internal combustion engine provided with the evaporated fuel processing apparatus according to the present invention. In FIG. 1, an internal combustion engine 1 is provided with an exhaust turbocharger as a supercharger, and the intake air supercharged by a compressor 2 of the exhaust turbocharger is adjusted in flow rate by a throttle valve 3. It is sucked into the engine 1.

A fuel injection valve 4 is provided at each intake port of each cylinder, and the fuel injected from the fuel injection valve 4 and the intake air are mixed to form an air-fuel mixture. . The mixture is ignited and burned by spark ignition by an ignition plug 5 provided for each cylinder. A control unit 6 for controlling fuel injection by the fuel injection valve 4 and ignition by the ignition plug 5 includes a microcomputer, and calculates the fuel injection amount and the ignition timing based on detection signals from various sensors. Then, an injection pulse signal is output to the fuel injection valve 4, and an ignition signal is output to the ignition plug 5 (specifically, an ignition coil unit with a built-in power tiger attached to the ignition plug 5).

The various sensors include a throttle sensor 7 for detecting the opening of the throttle valve 3, an air flow meter 8 for detecting the intake air flow rate of the engine 1, and a crank angle sensor 9 for detecting a crank angle. I have.
The engine speed NE is calculated based on the detection signal from the crank angle sensor 9. On the other hand, the engine 1
Is provided with an evaporative fuel processing device 11. The evaporative fuel treatment device 11 causes an adsorbent such as activated carbon filled in the canister 12 to adsorb and collect the evaporative fuel generated in the fuel tank 13 and purge the fuel adsorbed by the adsorbent,
The purge air is supplied to the intake passage of the engine 1 through the purge passage 14. The purge passage 14 is communicated with an intake collector 22 of the intake passage downstream of the throttle valve 3.

The canister 12 has an evaporative fuel passage 16 provided with a check valve (check valve) 15 which opens when the pressure in the fuel tank 13 exceeds a predetermined pressure. Fuel is introduced, and the purge passage 14 is provided with an electromagnetic purge control valve 17. An electromagnetic air cut valve 19 is interposed in a fresh air inlet 18 for introducing fresh air into the canister 12.

Further, a supercharging pressure introducing passage which is branched from an intake passage 23 downstream of the compressor 2 and upstream of the throttle valve 3 and extends to the canister 12 to guide a part of intake air to the canister 12. An electromagnetic boost pressure cut valve 21 is interposed in the boost pressure introducing passage 20. Here, as shown in the flowchart of FIG. 2, the control unit 6 controls the purge control valve 17,
The purge valve 19 is controlled by controlling the atmosphere cut valve 19 and the supercharging pressure cut valve 21.

In step S1, a required purge flow rate is determined according to operating conditions such as an intake air amount of the engine and an engine speed.
In S2, the intake pressure on the downstream side of the throttle valve 3 is estimated from operating conditions such as the intake air amount, the engine speed, the throttle opening, or detected directly by the intake pressure sensor.

At S3, it is determined whether the detected intake pressure is equal to or higher than a predetermined value. Here, when the intake pressure is in a supercharging region where the intake pressure is equal to or higher than a predetermined value, S
Proceeding to 4, the supercharging pressure cut valve 21 is opened, and in the next S5, the atmospheric cut valve 19 is closed. As a result, the supercharged intake air is guided to the canister 12, and the canister 12 is scavenged by the supercharged intake air.
A state in which the air is purged to the intake collector section 22 via the port 14 is obtained.

In step S6, the required purge flow rate is converted into a control duty of the purge control valve 17 in response to the state in which the canister 12 is scavenged by the supercharged intake air, and a drive signal of the duty is transmitted to the purge control valve 17. Output to 17. According to the above configuration, even if the intake pressure on the downstream side of the throttle valve 3 increases due to supercharging, it is possible to purge the canister 12 by purging the canister 12 with the intake air having a higher pressure.

On the other hand, if it is determined in step S3 that the intake pressure downstream of the throttle valve 3 is lower than the predetermined value, it is determined that the atmospheric pressure and the intake pressure (negative pressure) downstream of the throttle valve 3 are in the non-supercharged region. The purging can be performed by utilizing the pressure difference between the supercharged pressure cut valve 21 and the supercharged pressure cut valve 21 is closed. In the next S8, the atmospheric cut valve 19 is opened to release the atmospheric pressure from the canister. It is in a state that can be introduced into 12.

In step S9, the required purge flow rate is converted into a control duty of the purge control valve 17 in accordance with a state where the canister purge is performed using the intake negative pressure on the downstream side of the throttle valve 3. Is output to the purge control valve 17. With the above configuration, in the non-supercharging region (low load region), the supercharging pressure introduction passage 20 and the purge passage
By this, the intake air can be prevented from flowing by bypassing the throttle valve 3, and the canister purge can be performed while the function of adjusting the air amount by the throttle valve 3 is secured.

In the above description, the exhaust turbocharger is provided as a supercharger. However, a mechanically driven supercharger may be provided. In addition, the atmosphere cut valve 19
Instead, a mechanical check valve that allows only the flow from the atmosphere side to the canister 12 side may be provided. In such a configuration, the control of S5 and S8 in the flowchart of FIG. 2 can be omitted.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an internal combustion engine according to an embodiment.

FIG. 2 is a flowchart illustrating an embodiment of purge control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Compressor 3 Throttle valve 4 Fuel injection valve 5 Spark plug 6 Control unit 7 Throttle sensor 8 Air flow meter 9 Crank angle sensor 11 Evaporation fuel processing device 12 Canister 13 Fuel tank 14 Purge passage 15 Check valve 16 Evaporation fuel passage 17 Purging Control valve 18 Atmospheric inlet 19 Atmospheric cut valve 20 Supercharging pressure introduction passage 21 Supercharging pressure cut valve

Claims (4)

[Claims] An evaporative fuel generated from a fuel tank is adsorbed and collected in a canister, and the evaporative fuel adsorbed and collected in the canister is supplied to an intake passage of the engine via a purge passage for combustion. An evaporative fuel processor for an internal combustion engine with a supercharger, wherein the canister is scavenged by intake air supercharged by a supercharger, and the evaporative fuel is supplied into an intake passage of the engine via the purge passage. An evaporative fuel processing apparatus for a supercharged internal combustion engine, comprising: 2. The fuel tank according to claim 1, wherein the evaporative fuel generated from the fuel tank is adsorbed and collected in a canister, and the evaporative fuel adsorbed and collected in the canister is supplied into an intake passage of the engine via a purge passage for combustion. An evaporative fuel processor for an internal combustion engine with a supercharger, comprising a supercharger upstream of a throttle valve and connecting the purge passage to an intake passage downstream of the throttle valve. A supercharging pressure introducing passage for guiding a part of the intake air from the intake passage on the downstream side and upstream of the throttle valve to the canister, and a supercharging pressure cut valve interposed in the supercharging pressure introducing passage. An evaporative fuel processor for a supercharged internal combustion engine, wherein the boost pressure cut valve is opened when an intake pressure downstream of the throttle valve is equal to or higher than a predetermined value. 3. The evaporation of the internal combustion engine with a supercharger according to claim 2, wherein a check valve is interposed in the fresh air inlet to prevent a back flow from the fresh air inlet of the canister. Fuel processor. 4. The internal combustion engine with a supercharger according to claim 2, wherein when the supercharging pressure cut valve is opened, an air cut valve interposed in a fresh air inlet of the canister is closed. Evaporative fuel processing equipment.