JP2591309B2 - Fuel vapor emission suppression device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor emission suppression device that suppresses fuel vapor discharged from the internal combustion engine to the atmosphere after shutdown.

2. Description of the Related Art Conventionally, when an engine is stopped, a part of fuel may remain unburned in a surge tank, an intake manifold, or a fuel chamber of an intake system. Then, these unburned residual fuels eventually become steam, which hinders proper combustion at the time of restart, or is gradually released to the atmosphere over a long period of time, which has been a problem.

Therefore, in order to deal with such a problem, for example, in Japanese Patent Application Laid-Open Nos. 60-53638 and 60-88832, the ignition device is operated for a predetermined period of time even after the ignition switch is turned off. A technique has been disclosed in which the residual fuel is burned.

[Problems to be Solved by the Invention] However, in each of the above-described conventional examples, the remaining fuel is ignited and burned to maintain the engine rotation after the ignition switch is turned off. That is, even after the ignition switch is turned off, the ignition is maintained only while the engine continues to rotate by inertia. Therefore, when the amount of the residual fuel becomes less than the flammable range corresponding to the capacity of the engine, the rotation of the engine stops, and there is a problem that the residual fuel cannot be completely removed from the intake system or the like. Therefore, there is a possibility that the remaining fuel that cannot be completely burned becomes steam after the engine stops and leaks to the atmosphere.

The present invention has been made in view of the above-described circumstances, and has as its object to provide a fuel vapor emission suppression device capable of reliably removing residual fuel generated in an intake system, a combustion chamber, and the like of an internal combustion engine at the time of stoppage. To provide.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, the first
As shown in the figure, a fuel supply means M2 for supplying fuel to the internal combustion engine M1, an ignition switch M3 operated to instruct start / stop of the internal combustion engine M1, and a drive connection to a crankshaft of the internal combustion engine M1. A cranking means M4 for performing cranking, and a fuel stop control means M5 for stopping the operation of the fuel supply means M2 to stop the fuel supply when the stop of the internal combustion engine M1 is instructed by the ignition switch M3.
And a cranking control means M6 for operating the cranking means M4 for a predetermined time in order to eliminate fuel remaining in the internal combustion engine M1 after the stop of the internal combustion engine M1 is instructed by the ignition switch M3.

[Operation] According to the above configuration, as shown in FIG.
When the ignition switch M3 is turned off when M1 is stopped, the fuel stop control means M5 is turned on by the fuel supply means.
Deactivate M2 to stop fuel supply. Further, the cranking control means M6 operates the cranking means M4 for a predetermined time after the stop of the internal combustion engine M1 is instructed by the ignition switch M3. As a result, the fuel remaining in the internal combustion engine M1 is eliminated until the stop of the internal combustion engine M1 is completed.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram showing a gasoline engine system to which the fuel vapor emission suppression device according to the present invention is applied. An engine 1 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 an inlet of the intake passage 2. A surge tank 5 is provided in the middle of the intake passage 2. Downstream 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 (in this case, four cylinders) of the engine 1. On the other hand, on the outlet side of the exhaust passage 3, a catalytic converter 7 having a built-in three-way catalyst is provided.

Then, the engine 1 takes in outside air from the air cleaner 4 through the intake passage 2. At the same time as taking in the outside air, the engine 1 takes in the fuel injected from each of the injectors 6A to 6D. Further, the engine 1 explodes and burns a mixture of the taken fuel and the outside air in each combustion chamber to obtain a driving force, and then discharges the exhaust gas from the exhaust passage 3 to the outside via the catalytic converter 7. I do.

On the upstream side of the surge tank 5, a throttle valve 8 that opens and closes in response to operation of an accelerator pedal (not shown) is provided. And this throttle valve 8
Is opened and closed, the intake flow rate in the intake passage 2 is adjusted.

In the vicinity of the throttle valve 8, a throttle opening sensor 21 for detecting the opening is provided. A well-known movable vane type air flow meter 22 for measuring the flow rate of intake air passing through the intake passage 2 is provided downstream of the air cleaner 4. Further, an oxygen sensor 23 for detecting the oxygen concentration in the exhaust gas, that is, for detecting the exhaust air-fuel ratio in the exhaust gas passage 3 is provided in the exhaust passage 3. Further, the engine 1 is provided with a water temperature sensor 24 for detecting the temperature of the cooling water (cooling water temperature).

Spark plugs 9A and 9B provided for each cylinder of the engine 1
The ignition signals distributed by the disk distributor 10 are applied to 9C and 9D. The distributor 10 distributes the high voltage output from the igniter 11 to the ignition plugs 9A to 9D in synchronization with the crank angle of the engine 1. The ignition timing of each of the ignition plugs 9A to 9D is
It is determined by the high voltage output timing from the igniter 11.

The distributor 10 has a built-in rotor (not shown) that rotates in conjunction with the rotation of the engine 1. The distributor 10 is provided with a rotation speed sensor 25 for detecting the rotation speed (engine rotation speed) NE of the engine 1 from the rotation of the rotor. Similarly, a cylinder discriminating sensor 26 that detects a change in the crank angle of the engine 1 at a predetermined rate according to the rotation of the rotor is attached to the distributor 10, respectively. In this embodiment, assuming that the engine 1 makes two revolutions per stroke, the cylinder discrimination sensor 26 detects the crank angle at a rate of 360 ° CA.

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

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

Each of the injectors 6A to 6D, the igniter 11 and the starter 12 is an electronic control unit (hereinafter simply referred to as “ECU”) 30 that constitutes a fuel stop control unit and a cranking control unit.
The drive timing of the ECU 30 is controlled by the operation of the ECU 30. The ECU 30 stores a central processing unit (CPU), a read-only memory (ROM) in which a predetermined control program and the like are stored in advance, a random access memory (RAM) in which CPU operation results and the like are temporarily stored, and data stored in advance. It is configured as a logical operation circuit in which a backup RAM and the like, these units, an external input circuit, an external output circuit, and the like are connected by a bus.

The ECU 30 has an air flow meter 22, sensors 21 and 23,
Read the output signal from 27 as input value. Also, ECU30
Preferably controls the injectors 6A to 6D, the igniter 11, and the starter 12 based on these input values.

An ignition switch (IGSW) 13 operated to instruct start / stop of the engine 1 is connected between the starter 12 and the battery (+ B). And
When the IGSW 13 is turned on and off when the engine 1 is started and stopped, the start and stop of the injectors 6A to 6D, the igniter 11, and the starter 12 are instructed.

Next, processing for suppressing fuel vapor emission executed by the ECU 30 will be described with reference to the flowchart of FIG.

The process for suppressing fuel vapor emission in this embodiment is performed when the engine 1 is stopped. Therefore, the ECU 30 first determines in step 101 whether the IGSW 13 has been turned off. That is, to stop engine 1 IG
It is determined whether SW13 has been turned off.

If the IGSW 13 is not switched off, it is assumed that the operation of the engine 1 is to be continued and the subsequent processing is terminated. If the IGSW 13 is switched off, the engine 1
Are stopped, and the processing of steps 102 to 109 is executed.

That is, in step 102, first, the fuel injection is stopped. That is, when the engine 1 is stopped, the injectors 6A to 6D are deactivated to stop the 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 or not “a seconds” as a predetermined time has elapsed. This determination is made in order to confirm whether or not a sufficient time has elapsed for the engine 1 to temporarily stop after the fuel injection is stopped.
Therefore, while “a second” has not elapsed, in step 105, the ignition maintenance is executed. That is, each spark plug 9A ~
Maintain the ignition operation in 9D.

On the other hand, if “a second” has elapsed in step 104, the starter 12 is turned on in step 106. That is, the starter 12 is operated to crank the engine 1.

Then, in step 107, it is determined whether or not “b seconds” as a predetermined time has elapsed. This determination is made to confirm whether or not a sufficient time has elapsed after the starter 12 has been turned on to completely burn or discharge the residual fuel in the intake passage 2 and each cylinder combustion chamber. In this embodiment, “b seconds” is set with reference to “20 seconds” as a time since the timer was set in step 103.

Therefore, while “b seconds” has not elapsed, step 105
Is performed to maintain the ignition.

On the other hand, if "b seconds" have elapsed in step 107, the starter 12 is turned off in step 108 assuming that the residual fuel has been completely burned or discharged. That is, the cranking of the engine 1 is stopped.

Thereafter, in step 109, each of the spark plugs 9A to 9D
Is stopped, and the subsequent processing ends.

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

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

Thereafter, when “a seconds” have elapsed from the time t1 and the engine speed NE becomes “0”, the starter 12 is turned on and the engine 1 is cranked. Then, with the cranking, the engine speed NE started to rise again,
Engine speed only from t1 until "b seconds" elapse
NE is maintained at a moderate level. That is, during this time, the fuel remaining in the intake passage 2 and the combustion chamber of each cylinder evaporates due to the heat of the engine 1, and is burned in the combustion chamber with the maintenance of cranking and ignition. The rotation of the engine 1 at this time is not due to inertia, but is a result of being actively performed by cranking and combustion of residual fuel.

Then, when "b seconds" elapse from time t1, the starter 12 is turned off, ignition is stopped, and the stop of the engine 1 is completed. Even if the residual fuel amount falls below the flammable range during this time, the fuel vapor is sent to the catalytic converter 7 where it is purified. That is, each cylinder of the engine 1 functions as a pump that sends out residual fuel in the intake system to the catalytic converter 7.

As described above, according to the fuel vapor emission suppression device of this embodiment, after stopping the fuel injection when the engine 1 is stopped, the ignition is maintained while performing the cranking by the starter 12 for a sufficient time. Further, since the engine is forcibly rotated by cranking, the fuel remaining in the intake passage 2 or the like and becoming steam is burned together with the fuel remaining in the combustion chamber of each cylinder. The unburned residual fuel and the post-combustion exhaust gas are supplied to the exhaust passage 3.
Is discharged outside through the catalytic converter 7. Therefore, the engine 1 can be stopped while the remaining fuel is reliably and cleanly removed without leaving any in the intake passage 2 or the combustion chamber.

As a result, evaporative emission can be effectively reduced. Therefore, even after the engine 1 is stopped,
It is possible to prevent fuel vapor from leaking into the atmosphere from the intake passage 2 or each combustion chamber. Further, at the time of restart, combustion is not hindered by the fuel vapor, and starting can be reliably performed by proper combustion.

The present invention is not limited to the above-described embodiment, and may be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention.

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

In the case of only cranking, the fuel remaining in the intake passage, the combustion chamber, etc., which has been turned into steam by the heat of the engine,
The air is sent to the catalytic converter 7 through the exhaust passage 3 along with the cranking, is purified by the catalytic converter 7, and is discharged to the outside. Further, since the engine is forcibly rotated by cranking, residual fuel in the intake system can be reliably removed. Therefore, also in this case, it is possible to prevent the fuel vapor from leaking to the atmosphere.

(2) In the above embodiment, the starter 12 as the cranking means is provided, and the starter 12 is operated for cranking while the engine 1 is started and stopped. May be provided.

(3) In the above-described embodiment, the fuel vapor emission suppression device is embodied in the engine 1 of the type in which the fuel is injected and supplied by the injectors 6A to 6D. . However, in this case, it is needless to say that the fuel must be cut so that the fuel is not sucked out from the slow fuel passage of the carburetor.

[Effects of the Invention] As described above in detail, according to the present invention, the supply of fuel is stopped when the stop of the internal combustion engine is instructed by the ignition switch, and the internal combustion engine is cranked for a predetermined time. In addition, an excellent effect that residual fuel generated in the intake system, the combustion chamber, and the like of the internal combustion engine at the time of stoppage can be reliably removed is exhibited.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention, and FIGS.
FIG. 1 is a drawing according to one embodiment of the present invention, 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 executed by the fuel vapor emission suppression device. FIG. 4 is a time chart for explaining 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, M3 is an ignition switch, M4 is a cranking means, M5 is a fuel stop control means, M6 is a cranking control means, 1 is an engine as an internal combustion engine, 6A to 6D Is an injector as fuel supply means, 12 is a starter as cranking means, 13 is an ignition switch (IGSW), and 30 is an ECU which constitutes fuel stop control means and cranking control means.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Reference number in the agency FI Technical display location F02P 9/00 303 F02P 9/00 303B

Claims (1)

(57) [Claims] A fuel supply means for supplying fuel to an internal combustion engine; an ignition switch operated to instruct start / stop of the internal combustion engine; Cranking means for performing, fuel stop control means for stopping operation of the fuel supply means to stop fuel supply when stop of the internal combustion engine is instructed by the ignition switch, and the internal combustion engine by the ignition switch And a cranking control means for operating the cranking means for a predetermined time in order to eliminate fuel remaining in the internal combustion engine after an instruction to stop the fuel vapor is issued.