JPH0526120A - Evaporated fuel controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To surely improve starting characteristic at the time of restarting of an evaporated fuel controller of an internal combustion engine for processing a fuel that remains while the engine stops. CONSTITUTION:An evaporated fuel channel 8 by which an air intake tube 2 and a canister 9 are communicated together is provided in the evaporated fuel controller of an internal combustion engine provided on an engine 14 that injects fuel from a fuel injector 5 into an air suction tube 2. A valve device (VSV) 10 for opening/closing the evaporated fuel channel 8, which is arranged in the evaporation fuel channel 8, and an evaporated fuel controller (microcomputer) 11 for opening and driving the VSV 10 for a fixed period of time after the engine 14 stops, are also provided.

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 which processes residual fuel when the engine is stopped.

[0002]

2. Description of the Related Art When an internal combustion engine (engine) is stopped, if fuel remains in the intake pipe due to fuel leakage from a fuel injector or adhesion of fuel to the wall surface of the intake pipe, excess fuel remaining when restarting after the engine is stopped. It is known that components are sucked in and become overrich, resulting in poor startability. The deterioration of startability due to this residual fuel is
Especially, it occurs remarkably when the engine is restarted in a hot state such as in the summer or immediately after the engine is stopped.

Conventionally, as a means for improving the deterioration of the startability due to the residual fuel, a power source holding means for continuing the power supply to the ignition system for a predetermined time even after the engine is stopped is provided, and during this period, the power remains in the intake system. There is a fuel which burns up the fuel to an amount less than the combustible range, thereby improving the starting characteristic at the time of restarting (Japanese Patent Laid-Open No. 60-88832).

[0004]

However, in the device having the above-mentioned structure, since the starting characteristic is improved by burning the residual fuel, when the residual fuel amount is an appropriate amount that can be burned. Is effective, but when the amount of residual fuel is large, combustion may not occur due to lack of oxygen or the like even if ignition is performed. Therefore, the conventional device has a problem that the starting characteristic at the time of restart cannot be surely improved.

Further, in the conventional device, since the residual fuel is burned when the engine is stopped, the exhaust gas generated by the combustion remains in the engine. Therefore, at the time of restarting, it is conceivable that the residual exhaust gas rather deteriorates the starting characteristics.

The present invention has been made in view of the above points, and by introducing the residual fuel into the evaporated fuel storage means when the engine is stopped, the evaporation of the internal combustion engine that can surely improve the starting characteristics at the time of restarting It is an object to provide a fuel control device.

[0007]

In order to solve the above-mentioned problems, according to the present invention, in a fuel vapor control system for an internal combustion engine provided in an internal combustion engine for injecting fuel from an injector into an intake pipe, a throttle valve for the intake pipe is provided. The vaporized fuel passage that connects the downstream side and the vaporized fuel storage means, the valve device that is disposed in the vaporized fuel passage and that opens and closes the vaporized fuel passage, and the valve device that is opened for a predetermined time after the internal combustion engine is stopped. Evaporative fuel control means for opening the valve is provided.

[0008]

With the above structure of the evaporated fuel control device for the internal combustion engine, fuel leaks from the fuel injectors and fuel that adheres to the wall surface of the intake pipe and remains in the intake pipe passes through the evaporated fuel passage when the engine is stopped. It will be introduced into the storage means. Therefore, even if the amount of remaining fuel is large, the residual fuel is smoothly introduced and adsorbed in the evaporated fuel storage means, so that overrich at the time of restart can be prevented and the starting characteristics can be improved.

[0009]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a configuration diagram of essential parts of an evaporated fuel control device 1 according to an embodiment of the present invention, and FIG. 2 is a plan view showing an engine 14 in which the evaporated fuel control device 1 is arranged. In FIG. 2, 6
It shows a state in which the evaporated fuel control device 1 is provided in a cylinder independent injection type engine.

In the figure, reference numeral 2 is an intake pipe, and a throttle valve 3 for controlling the amount of air supplied to the engine 14 from its upstream side, a surge tank 4 for preventing an intake artery, and fuel injection to an intake port 6. A fuel injector 5, an intake valve 7 for introducing the injected fuel into the cylinder during an intake stroke, and the like are provided.

Reference numeral 8 denotes an evaporated fuel passage, which is an essential part of the present invention, and one end of the fuel injector 5 is located between the position where the surge tank 4 of the intake pipe 2 is arranged and the position where the fuel injector 5 is arranged. It is connected to the vicinity and forms an opening 16, and the other end is connected to the canister 9. A switching valve (hereinafter referred to as VSV) 10 is arranged in the middle of the vaporized fuel passage 8.

The canister 9 contains activated carbon as an adsorbent therein, and contains evaporated fuel introduced from a fuel tank (not shown) and residual fuel introduced through an evaporated fuel passage 8 as described later. It is held by adsorbing. The fuel held in the canister 9 is configured to be purged into the intake pipe 2 through the purge pipe 15.

The VSV 10 is, for example, an electromagnetic valve, which opens and closes the vaporized fuel passage 8 by operating the opening / closing valve. The intake pipe 2 and the canister 9 are communicated with each other by opening the VSV 10. The VSV 10 is connected to the evaporative fuel control microcomputer 11, and the VSV 10 operates to open and close based on a signal supplied from the microcomputer 11.

The microcomputer 11 is composed of a central processing circuit (not shown), a memory circuit, etc., and from the ignition key 12 the engine 14 is turned on / off.
Signal, and a water temperature signal is supplied from a water temperature sensor 13 attached to the water jacket of the engine 14,
Opening / closing control of the VSV 10 is performed based on each signal.

Next, the control operation of the VSV 10 performed by the microcomputer 11 will be described with reference to FIG.
The processing program shown in FIG.
This is a routine process which is stored in the read-only memory (ROM) in the No. 1 and is executed, for example, every 64 ms.

When the program shown in the figure is started, first, the microcomputer 11 executes step 100 (hereinafter,
In step S), it is determined whether the engine water temperature is equal to or higher than a predetermined temperature (for example, 80 ° C.) based on the water temperature signal supplied from the water temperature sensor 13. In S100, when the engine water temperature is equal to or lower than the predetermined temperature, the process ends without performing the process of introducing the evaporated fuel into the canister 9 described in S110 to S140 described below. On the other hand, when the engine water temperature is equal to or higher than the predetermined temperature, S11
The process of introducing the evaporated fuel into the canister 9 shown in 0 to S140 is executed.

The fuel leaking from the fuel injector 5 and the fuel adhering to the wall surface of the intake pipe 2 deteriorates the startability when the engine is restarted after the engine is stopped. This is the case when it is started. When the engine temperature is high as described above, the amount of evaporated fuel generated increases and the restartability deteriorates. Therefore, the fuel vapor is introduced into the canister 9 when the engine water temperature is higher than the predetermined temperature.

When it is determined in S100 that the engine water temperature is equal to or higher than the predetermined temperature, the process proceeds to S110, and ON / O supplied from the ignition key (IG key) 12 is turned on.
Based on the FF signal, it is determined whether the engine 14 has been stopped. Since it is not necessary to process the evaporated fuel while the engine 14 is operating, the process ends. On the other hand, if it is determined that the engine 14 is stopped, the process proceeds to S120.
Then, the microcomputer 11 turns on the VSV10.
And As a result, the evaporated fuel passage 8 is opened and the intake pipe 2 and the canister 9 are communicated with each other by the evaporated fuel passage 8.

As described above, the VSV 10 is opened and the evaporated fuel passage 8 is opened when the engine 14 is stopped in a state where the engine temperature is high and the evaporated fuel is likely to be generated in the intake pipe 2, so that the intake pipe 2 is opened. Evaporative fuel generated in the canister 9
Will be introduced to. At this time, since the canister 9 is originally configured to adsorb the evaporated fuel generated in the fuel tank, its adsorption capacity is relatively large, so that a large amount of residual fuel exists in the intake pipe 2 and a large amount of evaporated fuel is generated. Even in this case, the canister 9 can sufficiently adsorb the evaporated fuel generated in the intake pipe 2.

When the VSV 10 is opened by the processing of S120, the microcomputer 11 is opened in S130.
Uses a built-in clock to count the time during which the VSV 10 is opened, and determines whether the VSV 10 has been opened for a predetermined time (for example, 5 to 30 seconds). The valve open state of the VSV 10 is maintained until this predetermined time elapses, and the evaporated fuel generated in the intake pipe 2 is continuously introduced into the canister 9. This predetermined time is for the engine 1
The maximum amount of residual fuel that can remain in the intake pipe 2 is set to a time that can be introduced into the canister 9, although this depends on the size of the fuel cell 4 and the like. Therefore, even if a large amount of evaporated fuel is generated in the intake pipe 2, this evaporated fuel is surely adsorbed to the canister 9.

When it is determined in S130 that the predetermined time has elapsed, the process proceeds to S140, the microcomputer 11 closes the VSV 10, and the evaporated fuel passage 8 is restarted.
Is closed and the process ends. Above S100-S1
In the state in which the process of step 40 is completed, almost all of the generated evaporated fuel is adsorbed by the canister 9 and does not exist in the intake pipe 2, so the air-fuel ratio at restart does not become overrich, and at restart. The starting characteristic can be improved.

FIG. 4 is a diagram for explaining the effect of the present invention. The same graph shows the relationship between the air-fuel ratio and the elapsed time after starting and the relationship between the engine speed and the elapsed time after starting in the same graph. Further, in the figure, the solid line shows the characteristic of the engine 14 to which the evaporated fuel control device 1 according to the present invention is applied, and the broken line shows the characteristic of the engine of the conventional configuration.

First, paying attention to the air-fuel ratio, in the conventional engine, the air-fuel ratio is in a rich state for a while after starting. As described above, this is due to the fuel remaining in the intake pipe after the engine is stopped. Therefore, looking at the engine speed, it can be seen that in the conventional engine, the increase in engine speed after starting is slow and the starting characteristics are deteriorated.

On the other hand, in the engine 14 to which the evaporated fuel control device 1 according to the present invention is applied, the fuel remaining in the intake pipe 2 is introduced into the canister 9 when the engine is stopped,
Since the fuel is not present in the intake pipe 2 at the time of restart, the air-fuel ratio changes to the lean side (ideal air-fuel ratio side) in a short time after the start has elapsed. In this way, since the air-fuel ratio at restart is in the proper air-fuel ratio state, the engine speed rises in a short time as shown in the figure, and the starting characteristics are improved compared to the conventional one. I understand.

In the above embodiment, the engine temperature is judged based on the temperature signal supplied from the water temperature sensor 13, but the means for judging the engine temperature is not limited to this. The engine temperature may be determined by measuring

In the above embodiment, the vaporized fuel generated in the intake pipe 2 is introduced into the canister 9, but
Instead of this, as shown in FIG. 6, the fuel vapor generated in the intake pipe 2 may be introduced between the intake pipe 2 upstream of the throttle valve 3 and the air cleaner 17.

Further, in the above embodiment, the VSV 10 is opened for a predetermined time, but the amount of fuel vapor generated is related to the engine temperature, and the engine temperature is high. The more it is generated. Therefore,
A configuration in which a valve temperature of the VSV 10 is determined based on the water temperature may be stored in advance in the microcomputer 11 by previously storing a map of the water temperature (which may be the fuel temperature) and the valve opening time. With this configuration, the VSV 10 is not closed before all the evaporated fuel is adsorbed by the canister 9, and the controllability of the evaporated fuel can be further improved.

[0028]

As described above, according to the present invention, the fuel leaked from the fuel injector and the fuel adhering to the wall surface of the intake pipe and remaining in the intake pipe are introduced into the evaporated fuel storage means through the evaporated fuel passage when the engine is stopped. Therefore, even if the amount of residual fuel is large, the residual fuel is smoothly introduced and adsorbed in the evaporated fuel storage means, so overrich at the time of restart can be prevented and the starting characteristics can be improved. With the features of.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an evaporated fuel control device that is an embodiment of the present invention.

FIG. 2 is a plan view showing an engine provided with an evaporated fuel control device according to an embodiment of the present invention.

FIG. 3 is a flowchart showing an evaporated fuel control operation executed by a microcomputer.

FIG. 4 is a diagram for explaining the effect of the present invention.

FIG. 5 is a diagram showing an example of a map stored in a microcomputer.

FIG. 6 is a main part configuration diagram of an evaporated fuel control device according to another embodiment of the present invention.

[Explanation of symbols]

 1 Evaporative Fuel Control Device 2 Intake Pipe 3 Throttle Valve 4 Surge Tank 5 Fuel Injector 6 Intake Port 7 Intake Valve 8 Evaporative Fuel Passage 9 Canister 10 VSV (Switching Valve) 11 Microcomputer 12 Ignition Key (IG Key) 13 Water Temperature Sensor 14 Engine 15 Purge pipe 16 Evaporative fuel passage opening 17 Air cleaner

Claims (1)

Claim: What is claimed is: 1. An evaporated fuel control device for an internal combustion engine, which is provided in an internal combustion engine for injecting fuel from an injector into an intake pipe, wherein a downstream side of a throttle valve of the intake pipe communicates with evaporated fuel storage means. An evaporated fuel passage, a valve device provided in the evaporated fuel passage for opening and closing the evaporated fuel passage, and an evaporated fuel control means for opening the valve device for a predetermined time after the internal combustion engine is stopped. An evaporative fuel control device for an internal combustion engine, comprising: