JPH04153558A - Fuel vapor discharge suppressing device - Google Patents

Abstract

PURPOSE:To surely discharge the fuel left in an intake system, combustion chamber, etc., by suspending the feed of fuel when the stop of an internal combustion engine is instructed by an ignition switch and cranking-operating the internal combustion engine for a prescribed time. CONSTITUTION:A fuel stop control means M5 which suspends the operation of a fuel feeding means M2 in order to stop fuel feed when the stop of an internal combustion engine M1 is instructed by an ignition switch M3 is installed, and a cranking control means M6 which operates a cranking means M4 for a prescribed time in order to discharge the fuel left in the internal combustion engine M1 after the stop of the internal combustion engine M1 is instructed by the ignition switch M3 is installed. Since the cranking control means M6 operates the cranking means M4 for a prescribed time after the stop of the internal combustion engine M1 is instructed by the ignition switch M3, the fuel left in the internal combustion engine M1 is discharged up to the completion of the stop of the internal combustion engine M1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a fuel vapor emission suppression device that suppresses fuel vapor discharged into the atmosphere from an internal combustion engine after it has been stopped.

1. Prior Art] Conventionally, when an engine is stopped, a portion of the fuel may remain unburned in the surge tank, intake manifold, or combustion chamber of the intake system. These unburned residual fuels eventually turn into steam, which can interfere with proper combustion when the engine is restarted, or can be released little by little into the atmosphere over a long period of time, creating problems.

Therefore, in order to deal with such problems, for example, Japanese Patent Laid-Open No. 60-53638 and Japanese Patent Laid-Open No. 60-ss832 have been proposed.
The publication discloses a technique in which the ignition device continues to operate for a predetermined period of time even after the ignition switch is turned off to burn residual fuel.

[Problems to be Solved by the Invention] However, in each of the conventional examples described above, the engine rotation is maintained after the ignition switch is turned off by igniting and burning the residual fuel. In other words, even after the ignition switch was turned off, the ignition was maintained only as long as the engine or inertia continued to rotate. Therefore, when the amount of residual fuel falls below the flammable range corresponding to the capacity of the engine, the engine stops rotating and there is a problem in that the residual fuel cannot be completely removed from the intake system and the like.

Therefore, the remaining fuel that has not been completely combusted may turn into steam and leak into the atmosphere after the engine is stopped.

This invention was made in view of the above-mentioned circumstances, and its purpose is to provide a fuel vapor emission suppression device that can reliably eliminate residual fuel generated in the intake system, combustion chamber, etc. of an internal combustion engine when it is stopped. It is about providing.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, as shown in FIG. - When the ignition switch M3 is operated to instruct stop, the cranking means M4 is drivingly connected to the crankshaft of the internal combustion engine M1 and performs cranking, and the ignition switch M3 instructs to stop the internal combustion engine M1. , a fuel stop control means M5 that stops the operation of the fuel supply means M2 to stop the fuel supply, and an ignition switch M
3, cranking control means M operates cranking means M4 for a predetermined period of time in order to remove fuel remaining in internal combustion engine M1 after the internal combustion engine M1 is instructed to stop.
6.

[Operation] According to the above configuration, as shown in FIG.
When the ignition switch M3 is turned off when the engine 1 is stopped, the fuel stop control means M5 deactivates the fuel supply means M2 to stop the fuel supply.

Further, the cranking control means M6 operates the cranking means M4 for a predetermined period of time after the ignition switch M3 instructs the internal combustion engine M1 to stop. As a result, the fuel remaining in the internal combustion engine M1 is removed from the internal combustion engine M1.
will be removed until the stop is complete.

[Example] Hereinafter, an example embodying the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a gasoline engine stem to which the fuel vapor emission control device of the present invention is applied. An engine l as an internal combustion engine mounted on a vehicle includes an intake passage 2 and an exhaust passage 3. An air cleaner 4 is provided at the entrance of the intake passage 2. Further, a surge tank 5 is provided in the middle of the intake passage 2. On the downstream side of the surge tank 5, injectors 6A, 6B, 6C, and 6D are provided as fuel supply means for injecting and supplying fuel to each cylinder (four cylinders in this case) of the engine 1, respectively. On the other hand, a catalytic converter 7 having a built-in three-way catalyst is provided on the exit side of the exhaust passage 3.

The engine l takes in outside air from the air cleaner 4 through the intake passage 2. Further, at the same time as taking in the outside air, the engine 1 takes in fuel injected from each injector 6A to 6D. In addition, the engine 1 explodes and burns the mixture of the taken in fuel and outside air in each combustion chamber to obtain driving force, and then exhausts the exhaust residue from the exhaust passage 3 to the outside via the catalytic converter 7. do.

Further, on the upstream side of the surge tank 5, there is a throttle valve 8 that opens and closes in conjunction with the operation of an accelerator pedal (not shown).
Or is provided. By opening and closing this throttle valve 8, the intake air flow rate in the intake passage 2 is adjusted.

A throttle opening sensor 21 is provided near the throttle valve 8 to detect its opening. Further, on the downstream side of the air cleaner 4, a well-known movable vane air flow meter 22 for measuring the flow rate of intake air passing through the intake passage 2 is provided. Furthermore, an oxygen sensor 23 is provided in the middle of the exhaust passage 3 to detect the oxygen concentration in the exhaust gas, that is, to detect the exhaust air-fuel ratio in the exhaust passage 3. or,
The engine l is provided with a water temperature sensor 24 that detects the temperature of its cooling water (cooling water temperature).

Spark plugs 9A, 9 provided for each cylinder of the engine 1
An ignition signal distributed by the distributor 10 is applied to B, 9C, and 9D. distributor 10
is for distributing the high voltage output from the equniter 11 to each of the spark plugs 9A to 9D in synchronization with the crank angle of the engine 1. And each spark plug 9A to 9D
The ignition timing of is determined by the high voltage output timing from igniter II.

The distributor IO has a built-in rotor (not shown) that rotates in conjunction with the rotation of the engine 1. The distributor IO is provided with a rotation speed sensor 25 that detects the rotation speed NE of the engine 1 (engine rotation speed) from the rotation of the rotor. Similarly, cylinder discrimination sensors 26 are attached to each distributor 1° to detect changes in the crank angle of the engine 1 at a predetermined rate in accordance with the rotation of the rotor. In this example,
Assuming that the engine 1 rotates twice per stroke, the cylinder discrimination sensor 26 detects the crank angle at a rate of 360'CA.

Further, a transmission (not shown) that is drivingly connected to the engine 1 is provided with a vehicle speed sensor 27 for detecting vehicle speed.

Further, the engine 1 is provided with a starter 12 as a cranking means, which is drivingly connected to a crankshaft (not shown) for cranking. In this embodiment, the starter 12 is driven when the engine 1 is started, and is also driven for a predetermined period of time when the engine 1 is stopped.

Each of the injectors 6A to 6D, the equniter 11, and the starter 12 are electrically connected to an electronic control unit (hereinafter simply referred to as rEcU) 30 that constitutes fuel stop control means and cranking control means, and are controlled by the operation of the ECU 30. drive timing is controlled. This EC
U3O is a central processing unit (CPU), a read-only memory (ROM) that stores predetermined control programs, etc.
Random access memory (RAM) that temporarily stores PU calculation results, etc., backup RAM that stores pre-stored data, etc., and a logic operation circuit that connects these parts with external input circuits, external output circuits, etc. via a bus. It is configured as.

The ECU 30 includes an air flow meter 22 and each sensor 2.
The output signals from 1, 23 to 27 are read as input values. Furthermore, the ECU 30 suitably controls the injectors 6A to 6D, the igniter 11, and the starter 12 based on these input values.

Further, an ignition switch (IGSW) 13 is connected between the starter 12 and the battery (1,000 B), which is operated to instruct starting and stopping of the engine 1. When the engine 1 starts and stops, the IGSW 13 is turned on and off, so that each injector 6A
~6D, starting and stopping of the equniter 11 and starter 12 are instructed.

Next, the process for suppressing fuel vapor emission executed by the ECU 30 described above will be explained according to the flowchart of FIG. 3.

In this embodiment, the process for suppressing fuel vapor emission is performed when the engine 1 is stopped. Therefore, ECU3O
First, in step 101, it is determined whether or not the IGSW 13 has been turned off.

That is, it is determined whether or not the IGSW 13 has been turned off to stop the engine 1.

If rGsW13 is not switched off, the engine 1 continues to operate and the subsequent processing is terminated. Also, if IGSW13 is switched off,
Step 102 to +0 to stop engine 1
Execute the process in step 9.

That is, in step +02, fuel injection is first stopped. That is, when the engine 1 is stopped, each injector 6A to 6D is stopped to stop fuel injection.

Next, in step 103, a timer is set to count the time since the IGSW 13 was turned off.

Then, in step 104, it is determined whether "3 seconds" as a predetermined time has elapsed. This determination is made to confirm whether sufficient time has elapsed for the engine 1 to temporarily stop after the fuel injection is stopped.

Therefore, while "a seconds" have not elapsed, step 105
At this point, ignition maintenance is performed. That is, each spark plug 9
The ignition operation in A to 9D is continued.

On the other hand, if "a seconds" have elapsed in step 104, the starter 12 is turned on in step 106. That is, the starter 12 is activated to crank the engine 1.

Then, in step 107, it is determined whether "b seconds" as a predetermined time has elapsed. This determination is made to confirm whether sufficient time has elapsed after the starter 12 is turned on to completely burn or exhaust the residual fuel in the intake passage 2 and the combustion chambers of each cylinder. In this embodiment, the time after the timer is set in step 103 is "b seconds" with "20 seconds" as a guide.
is set.

Therefore, while "b seconds" have not elapsed, step 105
Perform ignition maintenance at

On the other hand, if "b seconds" have elapsed in step 107, it is assumed that the residual fuel has been completely burned or exhausted, and the starter 12 is turned off in step 108.

In other words, cranking of engine l is stopped.

After that, in step 109, each spark plug 9A~
The ignition operation at 9D is stopped, and the subsequent processing is completed.

Here, the action of the processing performed based on the above flowchart is shown in the time chart of FIG.

As is clear from this time chart, when the IGSW 13 is switched off at time t1, fuel injection is stopped, and the engine speed NE begins to decrease accordingly.

Thereafter, when the engine speed NE reaches "0" after "a seconds" have elapsed from the time t1, the starter 12 is turned on and cranking of the engine 1 is performed. Then, along with the cranking, the engine speed NE begins to rise again, and the engine speed NE is maintained at a moderate level only until 5 seconds 2 have passed from time tl.In other words, during this period, the intake air The fuel remaining in the passage 2 or the combustion chamber of each cylinder is evaporated by the heat of the engine 1, and is combusted in the combustion chamber as cranking and ignition are maintained.

The rotation of the engine 1 at this point is not due to inertia, but is the result of active rotation by cranking and combustion of residual fuel.

Then, when "b seconds" have elapsed from the time t1, the starter 12 is turned off and ignition is stopped, completing the stopping of the engine I. Also, even if the amount of residual fuel falls below the flammable range during this period, the fuel vapor will not reach the catalytic converter.
＜-It will be sent at 7pm and purified there. That is, each cylinder of the engine 1 functions as a pump that sends residual fuel in the intake system to the catalytic converter 7.

As described above, according to the fuel vapor emission control device of this embodiment, after the fuel injection is stopped when the engine 1 is stopped, the starter 12 performs refranking after a sufficient period of time to maintain ignition.

Further, since the engine is forcibly rotated by cranking, the fuel remaining in the intake passage 2 and the like and becoming vapor is combusted together with the fuel remaining in the combustion chambers of each cylinder and the like. The unburned residual fuel and the exhaust gas after combustion are discharged from the exhaust passage 3 to the outside via the catalytic converter 7. Therefore, the ennon 1 can be stopped after removing residual fuel reliably and cleanly without leaving any residue in the intake passage 2, the combustion chamber, or the like.

As a result, it is possible to effectively reduce the amount of energy. Therefore, even after the engine 1 is stopped, fuel vapor can be prevented from leaking into the atmosphere from the intake passage 2, each combustion chamber, etc. Furthermore, when restarting, combustion is not inhibited by fuel vapor, and proper combustion ensures a reliable start.

Note that this invention is not limited to the above embodiments,
The present invention can be implemented as follows by changing a part of the structure as appropriate without departing from the spirit of the invention.

(1) In the above embodiment, when the engine 1 is stopped, cranking is performed and the spark plugs 9A to 9D are ignited to burn the residual fuel.
The ignition operation by D may be omitted and only cranking may be performed.

In the case of only cranking, the fuel remains in the intake passage or combustion chamber and becomes vapor due to the heat of the engine, or the fuel passes through the exhaust passage 3 during cranking to the catalytic converter 7.
After being purified by the catalytic converter 7,
It is discharged to the outside.

Furthermore, since the engine is forcibly rotated by cranking, residual fuel in the intake system can be reliably removed. Therefore, in this case as well, fuel vapor can be prevented from leaking into the atmosphere.

(2) In the above embodiment, the starter 12 is provided as a cranking means, and the starter 12 is operated for cranking both when starting and stopping the engine 1, or when the engine is stopped, cranking is performed. A special drive source may be provided to perform this.

(3) In the above embodiment, the fuel vapor emission suppressing device is embodied in the engine 1 of the type in which the fuel is injected and supplied by the injectors 6A to 6D, but it may be embodied in the engine 1 of the type in which the fuel is vaporized and supplied by the carburetor. . however,
In this case, of course, it is necessary to cut fuel so that fuel is not sucked out from the slow fuel passage of the carburetor.

[Effects of the Invention] As detailed above, according to the present invention, when the ignition switch instructs to stop the internal combustion engine, the fuel supply is stopped and the internal combustion engine is cranked for a predetermined period of time. This provides an excellent effect in that residual fuel generated in the intake system, combustion chamber, etc. of the internal combustion engine can be reliably removed when the engine is stopped.

[Brief explanation of drawings]

Figure 1 is a diagram showing the basic configuration of this invention, Figures 2 to 4
The figures are drawings relating to an embodiment embodying the present invention, in which Fig. 2 is a schematic configuration diagram of a gasoline engine system to which a fuel vapor emission suppression device is applied, and Fig. 3 is a diagram showing an example of the fuel vapor emission suppression device executed by the fuel vapor emission suppression device. FIG. 4 is a flowchart illustrating the processing performed, and FIG. 4 is a time chart illustrating the operation of the processing performed based on the flowchart. In the figure, M1 is an internal combustion engine, M2 is a fuel supply means, ~1
3 is an engine as an internal combustion engine, M4 is a cranking means, N=I 5 is a fuel stop control means, M6 is a cranking control means, ■ is an engine as an internal combustion engine, 6A~
6D is an injector as a fuel supply means, 12 is a starter as a cranking means, 13 is an engine start switch (IGSW), and 30 is an ECU that constitutes a fuel stop control means and a cranking control means.

Claims (1)

[Scope of Claims] 1. A fuel supply means for supplying fuel to an internal combustion engine; an ignition switch operated to instruct starting and stopping of the internal combustion engine; cranking means for performing ranking; fuel stop control means for stopping the operation of the fuel supply means to stop the fuel supply when the ignition switch instructs to stop the internal combustion engine; and cranking control means for operating the cranking means for a predetermined period of time to remove fuel remaining in the internal combustion engine after the internal combustion engine is instructed to stop. .