JPH05263638A - Transpiration gas purifying device for internal combustion engine - Google Patents

Abstract

PURPOSE:To improve drivability, reduce an exhaust gas and efficiently purify a transpiration gas by obtaining stable combustion without the discharge of a great amount of HC to an intake pipe to eliminate a bad influence on an air-fuel ratio. CONSTITUTION:This is a purifying device of a transpiration gas (HC) generated from fuel stored in a fuel tank 28 for an engine 10 and stored into a canister 35 temporarily. Here, a switching valve 53 and a supply pipe 52 as a transpiration gas supply means for supplying the transpiration gas in a canister 35 to an exhaust pipe 29 and a switching valve 57 and an intake pipe 59 as an air supply means for supplying a secondary air to the exhaust pipe 29 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for purifying evaporated gas generated from fuel stored in a fuel tank of an internal combustion engine.

[0002]

2. Description of the Related Art A required amount of fuel such as gasoline is stored in a fuel tank of an automobile, and this fuel is evaporated due to a temperature difference such as warm air of the engine or outside air. This transpiration gas contains harmful substances such as hydrocarbons (hereinafter referred to as HC). Therefore, the transpiration gas cannot be released to the outside as it is, and it is temporarily stored in the canister and the engine is used. When the engine is started, it is inhaled into this engine for processing.

FIG. 4 schematically shows a conventional engine transpiration gas purification device.

As shown in FIG. 4, the engine 10 is provided with an intake port 11 and an exhaust port 12, which can be opened and closed by an intake valve 13 and an exhaust valve 14. A piston 17 is connected to the crankshaft 15 via a connecting rod 16 and is supported in the cylinder so as to be vertically movable. A combustion chamber 18 is formed above the piston 17, and a spark plug 19 is attached to the combustion chamber 18.

The air cleaner 20 is for removing floating dust in the intake air, and is connected to the surge tank 22 and the intake port 11 of the engine 10 by an intake pipe 21. An air flow sensor 23 is provided on the air cleaner 20 side of the intake pipe 21, and a throttle valve 24 and a throttle position sensor 25 are provided on the surge tank 22 side of the intake pipe 21. The air flow sensor 23 and the throttle position sensor 25 are connected to an engine control unit (hereinafter referred to as ECU) 26 so that the detection result can be output. An injector 27 is attached to the intake port 11 of the engine 10 so that the gasoline stored in a fuel tank 28
A predetermined amount of fuel can be injected based on a command from the CU 26.

An exhaust pipe 29 is connected to the exhaust port 12 of the engine 10, and a catalytic converter (three-way catalyst) is provided in the middle thereof.
30 and a silencer 31 are attached. An O ₂ sensor 32 is attached to the exhaust pipe 29. In addition,
A water temperature sensor 33 for engine cooling water is provided in the engine 10, and a crank angle position sensor 34 is provided in a distributor (not shown) of the engine 10.

A canister 35 is connected to the fuel tank 28 described above. The canister 35 temporarily stores the evaporated harmful substances such as HC, and the engine 1
The fuel tank 28 is connected to a canister 35 via a discharge pipe 37 having a check valve 36. The canister 35 has a supply pipe 3 having a purge amount control valve 38.
It is connected to the intake pipe 21 via 9.

The air sucked from the air cleaner 20 is sent to the surge tank 22 via the intake pipe 21,
Then, it is supplied to the intake port 11 of the engine 10.
At this time, the throttle valve 24 controls the intake air amount. On the other hand, the ECU 26 uses the air flow sensor 23.
The fuel injection amount is determined from the intake air amount detected by and the throttle opening detected by the throttle position sensor 25, and the injector 27 injects a predetermined amount of gasoline in the fuel tank 28 based on a command from the ECU 26. Therefore, the mixture of air and gasoline becomes the combustion chamber 18
Will be supplied inside.

The air-fuel mixture is supplied from the intake port 11 into the combustion chamber 18, the piston 17 moves up and down by the drive of the crankshaft 15, the air-fuel mixture inside the combustion chamber 18 is compressed, and the spark plug 19 produces a spark. As a result, the compressed air-fuel mixture explodes and expands to operate the engine.

Further, while the engine 10 is stopped, the gasoline in the fuel tank 27 evaporates due to the temperature difference between the engine warm air and the outside air. When the vaporized gas has a gas pressure higher than a predetermined value, the check valve 35 opens and is sent to the canister 34 through the discharge pipe 36, where it is adsorbed and stored. Then, when the purge amount of the canister 34 becomes full, the purge amount control valve 37 opens,
It is discharged to the intake pipe 21 via the supply pipe 38. Therefore,
The evaporated gas discharged to the intake pipe 21 is sent to the combustion chamber 18 of the engine 10 together with the intake air and burned.

[0011]

In the conventional vaporized gas purifying apparatus for an engine described above, the vaporized gas generated from the gasoline in the fuel tank 27 is stored in the canister 34. In this case, for example, if the frequency of use of the vehicle is low in an area where the temperature difference between day and night is large, or if the traveling time is short even if used, the amount of transpiration gas generated increases and exceeds the adsorption capacity of the canister 34. There was a problem that the HC would overflow and be discharged outside the vehicle.

Conventionally, as a countermeasure, the capacity of the canister 34 is increased in order to increase the adsorption capacity of the canister 34, and a large amount of HC is discharged from the canister 34 into the intake pipe 21 while the engine 10 is operating. Combustion chamber 18
It is considered to burn with. By the way, in order to stabilize the combustion in the combustion chamber 18 of the engine 10,
In general, the ECU 26 controls the weight ratio of intake air and injected fuel, that is, the air-fuel ratio (A / F). As described above, the intake air is calculated from the detection results of the air flow sensor 23 and the throttle position sensor 25, and the ECU 26 determines the fuel injection amount corresponding to this. However, when a large amount of HC is discharged from the canister 34 to the intake pipe 21, there is a problem in that the air-fuel ratio is deviated and the drivability is deteriorated.

Therefore, the timing of discharging HC from the canister 34 to the intake pipe 21 is controlled so that HC is discharged only when the engine 10 is operating stably, for example, during low load operation or low rotation. Although it is possible to do so, a large number of valves for performing detailed detection of the operating state of the engine 10 and discharge of HC are required, and the device becomes complicated and large.

The present invention is intended to solve such problems, and an object of the present invention is to provide a vaporized gas purifying apparatus for an internal combustion engine which efficiently purifies vaporized gas.

[0015]

A vaporized gas purification apparatus for an internal combustion engine according to the present invention for achieving the above object is a purification apparatus for vaporized gas generated from fuel stored in a fuel tank of an internal combustion engine. A vaporized gas supply means for supplying the generated vaporized gas to the exhaust passage and an air supply means for supplying air to the exhaust passage are provided.

[0016]

The vaporized gas generated from the fuel tank is supplied to the exhaust passage by the vaporized gas supply means, while the air is supplied to the exhaust passage together with the vaporized gas by the air supply means, so that the oxidation reaction occurs and the hydrocarbons are generated. Hazardous substances such as are removed.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a vaporized gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is a flowchart thereof. The members having the same functions as the conventional ones are designated by the same reference numerals, and the duplicated description will be omitted.

In the vaporized gas purifying apparatus of this embodiment,
Evaporated gas supply means for supplying evaporated gas to the exhaust passage and air supply means for supplying air to the exhaust passage are provided.

That is, as shown in FIG. 1, the air cleaner 2
0 is connected to the intake port 11 of the engine 10 via the surge tank 22 by the intake pipe 21.
An air flow sensor 23, a throttle valve 24, and a throttle position sensor 25 are provided in the middle part. An injector 27 is attached to the intake port 11 of the engine 10 and is connected to a fuel tank 28. On the other hand, an exhaust pipe 29 is connected to the exhaust port 12 of the engine 10, and catalytic converters 30 (three-way catalyst), 51 (oxidation catalyst), and a silencer 31 are mounted midway.

A canister 35 is connected to the fuel tank 28 via a discharge pipe 37 having a check valve 36. The canister 35 temporarily stores the evaporated harmful substances such as HC and sucks the harmful substances when the engine 10 is started. The canister 35 is connected to the intake pipe 21 and the exhaust pipe 29 via the two supply pipes 39 and 52. It is connected. That is, the canister 35 is connected to the intake pipe 21 via the supply pipe 39 having the purge amount control valve 38, and is connected to the exhaust pipe 29 via the supply pipe 52 having the switching valve 53, the flame arrester 54, and the reed valve 55. It is connected.

The switching valve 53 is ON / OFF controlled by the ECU 26 and is opened under a predetermined condition so that the vaporized gas can be supplied to the exhaust pipe 29. The flame arrestor 54 is a mesh wire mesh for preventing backflow of combustion flame, and the reed valve 55 is opened by negative pressure on the exhaust pipe 29 side.

On the other hand, in addition to the above-mentioned air cleaner 20 which takes in the primary air and introduces it into the combustion chamber 18 of the engine 10 through the intake pipe 21, an air cleaner 56 which takes in the secondary air is provided. The air cleaner 56 is connected to the exhaust pipe 29 via an intake pipe 59 having a switching valve 57 and a reed valve 58. The switching valve 57 is ON / OFF controlled by the ECU 26 and is opened under a predetermined condition to supply secondary air to the exhaust pipe 29, and the reed valve 59 is opened by a negative pressure on the exhaust pipe 29 side. ..

The air sucked from the air cleaner 20 is supplied to the intake port 11 of the engine 10 via the intake pipe 21 and the surge tank 22, while the injector 27 injects a predetermined amount of gasoline in the fuel tank 28. Then
The mixture of air and gasoline is supplied to the combustion chamber 18. Then, the air-fuel mixture is compressed in the combustion chamber 18 by the vertical movement of the piston 17, and the spark plug 19 generates a spark, which explodes and expands to operate the engine.

While the engine 10 is stopped, the gasoline in the fuel tank 27 is evaporated due to the temperature difference between the engine warm air and the outside air. When the vapor pressure (HC) reaches a predetermined or higher gas pressure, the check valve 35 opens and is sent to the canister 34 through the discharge pipe 37, where it is adsorbed and stored. Then, the evaporated gas is discharged from the canister 34 to the intake pipe 21 via the supply pipe 39, and is sent to the combustion chamber 18 of the engine 10 together with the intake air for combustion.

At this time, if the frequency of use of the vehicle is low in an area where the temperature difference between day and night is large, or if the running time is short even if used, the amount of transpiration gas generated increases and exceeds the adsorption capacity of the canister 34. It may happen. In this case, while the evaporated gas of the canister 34 is supplied to the exhaust pipe 29 by the supply pipe 52, the secondary air sucked from the air cleaner 56 is supplied to the exhaust pipe 29 together with the evaporated gas,
The oxidation catalyst 51 causes the reaction.

That is, the ECU 26 constantly detects the cooling water temperature from the water temperature sensor 33 and constantly detects the engine speed from the crank angle position sensor 34. Therefore, as shown in FIG. 2, in step S1, it is determined whether the water temperature is equal to or higher than a certain temperature and the oxidation catalyst 51 is warmed up, and if so, the process proceeds to step S2.
If the water temperature is not lower than the predetermined temperature, the process proceeds to step S4 and the switching valves 53 and 57 are turned off.
In step S2, it is determined whether the engine 10 has a low load / low rotation, and if so, the process proceeds to step S3 and the switching valves 53 and 57 are turned on.

Then, the switching valve 53 is opened and the vaporized gas of the canister 34 is supplied to the exhaust pipe 29 by the supply pipe 52, while the switching valve 57 is opened and the secondary air from the air cleaner 56 is supplied to the exhaust pipe 29. , The air and the evaporated gas are mixed to form a mixture, which is reacted by the oxidation catalyst 51, and HC is removed. Also,
In step S2, if the engine 10 is not under low load and low rotation, the process proceeds to step S4 and the switching valves 53 and 57 are turned off.

The vaporized gas (HC) thus adsorbed in the canister 34 is supplied to the exhaust pipe 29 through the supply pipe 52, while the secondary air sucked from the air cleaner 56 is supplied to the exhaust pipe 29 together with the vaporized gas for oxidation. Since the reaction is carried out by the catalyst 51, the evaporated gas is passed through the canister 3
4 to the intake pipe 21 via the supply pipe 39 can be made low in cost and simple, or can be eliminated, and the canister 34
There is no need to upsize. Then, a large amount of HC is not discharged from the canister 34 to the intake pipe 21, the adverse effect on the air-fuel ratio of the engine 10 is eliminated, a stable combustion state is obtained, exhaust gas can be reduced, and deterioration of drivability is prevented. To be done.

FIG. 3 schematically shows a vaporized gas purifying apparatus for an internal combustion engine according to another embodiment of the present invention. The members having the same functions as those in the above-described embodiment are designated by the same reference numerals, and the duplicated description will be omitted.

In the transpiration gas purification apparatus of this embodiment,
Evaporated gas supply means for supplying evaporated gas to the exhaust passage and air supply means for supplying air to the exhaust passage are provided, and an air pump is used as the evaporated gas supply means. That is, the fuel tank 28 is connected to the canister 35 via the discharge pipe 37, and the canister 35 is connected to the two supply pipes 3.
The intake pipe 21 and the exhaust pipe 29 are respectively connected via 9, 61. The air pump 6 is attached to the supply pipe 61.
2 is installed.

The evaporated gas generated from the fuel tank 28 is stored in the canister 34, and the evaporated gas of the canister 34 is supplied to the exhaust pipe 29 by the supply pipe 61, while the secondary air sucked from the air cleaner 56 is evaporated. It is supplied to the exhaust pipe 29 together with the gas and is reacted by the oxidation catalyst 51. That is, as described above, when the water temperature is equal to or higher than a certain temperature and the engine 10 has a low load and a low rotation speed, the switching valve 57 is turned on and the air pump 6 is operated.
Activate 2. Therefore, the air-fuel mixture in the exhaust pipe 29 reacts with the oxidation catalyst 51 to remove HC.

In each of the above-described embodiments, an air cleaner 56 is provided separately from the air cleaner 20 for sucking the primary air in order to suck the secondary air for forming the air-fuel mixture with the evaporated gas. Although provided, the air cleaner 20 may be shared. For example, if the intake pipe 21 from the air cleaner 20 is branched in the middle and one is connected to the surge tank 22 and the other is connected to the exhaust pipe 29 to supply the primary air and the secondary air, the same as above. It is possible to achieve the action and effect.

[0034]

As described above in detail with reference to the embodiments, according to the evaporative gas purifying apparatus for an internal combustion engine of the present invention, the evaporative gas supply means for supplying the generated evaporative gas to the exhaust passage and the air are exhausted. Since the air supply means for supplying to the passage is provided, the vaporized gas generated from the fuel tank is supplied to the exhaust passage together with the air, and the oxidative reaction removes harmful substances such as hydrocarbons and the canister. It is not necessary to increase the size, and a large amount of HC is not discharged to the intake pipe, so that there is no adverse effect on the air-fuel ratio and a stable combustion state can be obtained, and exhaust gas is reduced and the evaporated gas is efficiently purified. It is possible to improve the drivability.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a vaporized gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation.

FIG. 3 is a schematic diagram showing a vaporized gas purifying apparatus for an internal combustion engine according to another embodiment of the present invention.

FIG. 4 is a schematic diagram showing a conventional evaporated gas purification device for an internal combustion engine.

[Explanation of symbols]

 10 engine 18 combustion chamber 20,56 air cleaner 21,59 intake pipe 26 engine control unit (ECU) 28 injection 29 exhaust pipe 30 catalytic converter (three-way catalyst) 35 canister 37 exhaust pipe 51 catalytic converter (oxidation catalyst) 52, 61 supply Pipe 53,57 Switching valve 62 Air pump

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[Procedure amendment]

[Submission date] November 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Detailed explanation of the invention

[Correction method] Change

[Correction content]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for purifying evaporated gas generated from fuel stored in a fuel tank of an internal combustion engine.

[0002]

2. Description of the Related Art A required amount of fuel such as gasoline is stored in a fuel tank of an automobile, and this fuel is evaporated due to a temperature difference such as warm air of the engine or outside air. This transpiration gas contains harmful substances such as hydrocarbons (hereinafter referred to as HC). Therefore, the transpiration gas cannot be released to the outside as it is, and it is temporarily stored in the canister and the engine is used. When the engine is started, it is inhaled into this engine for processing.

FIG. 4 schematically shows a conventional engine transpiration gas purification device.

As shown in FIG. 4, the engine 10 is provided with an intake port 11 and an exhaust port 12, which can be opened and closed by an intake valve 13 and an exhaust valve 14. A piston 17 is connected to the crankshaft 15 via a connecting rod 16 and is supported in the cylinder so as to be vertically movable. A combustion chamber 18 is formed above the piston 17, and a spark plug 19 is attached to the combustion chamber 18.

The air cleaner 20 is for removing floating dust in the intake air, and is connected to the surge tank 22 and the intake port 11 of the engine 10 by an intake pipe 21. An air flow sensor 23 is provided on the air cleaner 20 side of the intake pipe 21, and a throttle valve 25 and a throttle position sensor 24 are provided on the surge tank 22 side of the intake pipe 21. The air flow sensor 23 and the throttle position sensor 24 are connected to an engine control unit (hereinafter referred to as ECU) 26 so that the detection result can be output. An injector 27 is attached to the intake port 11 of the engine 10 so that the gasoline stored in a fuel tank 28
A predetermined amount of fuel can be injected based on a command from the CU 26.

An exhaust pipe 29 is connected to the exhaust port 12 of the engine 10, and a catalytic converter (three-way catalyst) is provided in the middle thereof.
30 and a silencer 31 are attached. An O ₂ sensor 32 is attached to the exhaust pipe 29. In addition,
A water temperature sensor 33 for engine cooling water is provided in the engine 10, and a crank angle position sensor 34 is provided in a distributor (not shown) of the engine 10.

A canister 35 is connected to the fuel tank 28 described above. The canister 35 temporarily stores the evaporated harmful substances such as HC, and the engine 1
The fuel tank 28 is connected to a canister 35 via a discharge pipe 37 having a check valve 36. The canister 35 is connected to the intake pipe 21 via a supply pipe 39 having a purge amount control valve 38 controlled by the ECU 26.

The air sucked from the air cleaner 20 is sent to the surge tank 22 via the intake pipe 21,
Then, it is supplied to the intake port 11 of the engine 10.
At this time, the throttle valve 25 controls the intake air amount. On the other hand, the ECU 26 uses the air flow sensor 23.
The fuel injection amount is determined from the intake air amount detected by and the throttle opening detected by the throttle position sensor 24, and the injector 27 injects a predetermined amount of gasoline in the fuel tank 28 based on a command from the ECU 26. Therefore, the mixture of air and gasoline becomes the combustion chamber 18
Will be supplied inside.

The air-fuel mixture is supplied from the intake port 11 into the combustion chamber 18, the piston 17 moves up and down by the drive of the crankshaft 15, the air-fuel mixture inside the combustion chamber 18 is compressed, and the spark plug 19 produces a spark. As a result, the compressed air-fuel mixture explodes and expands to operate the engine.

Further, while the engine 10 is stopped, the gasoline in the fuel tank 28 is evaporated due to the temperature difference between the engine warm air and the outside air. When the vapor pressure reaches a predetermined level or higher, the check valve 36 opens and is sent to the canister 35 via the discharge pipe 37, where it is adsorbed and stored. Then, the evaporated gas stored in the canister 35 is discharged to the intake pipe 21 via the supply pipe 39 by opening the purge amount control valve 38. Therefore, the vaporized gas discharged to the intake pipe 21 is sent to the combustion chamber 18 of the engine 10 and burned together with the intake air.

[0011]

In the conventional vaporized gas purification apparatus for an engine described above, the vaporized gas generated from gasoline in the fuel tank 28 is stored in the canister 35. In this case, for example, if the frequency of use of the vehicle is low in an area where the temperature difference between day and night is large, or if the traveling time is short even if used, the amount of vaporized gas generated increases and exceeds the adsorption capacity of the canister 35. There was a problem that the HC would overflow and be discharged outside the vehicle.

Conventionally, as a countermeasure against this, the capacity of the canister 35 is increased in order to increase the adsorption capacity of the canister 35, and a large amount of HC is discharged from the canister 35 to the intake pipe 21 while the engine 10 is operating. Combustion chamber 18
It is considered to burn with. By the way, in order to stabilize the combustion in the combustion chamber 18 of the engine 10,
In general, the ECU 26 controls the weight ratio of intake air and injected fuel, that is, the air-fuel ratio (A / F). As described above, the intake air is calculated from the detection results of the air flow sensor 23 and the throttle position sensor 24, and the ECU 26 determines the fuel injection amount corresponding to this. However, when a large amount of HC is discharged from the canister 35 to the intake pipe 21, there is a problem that the air-fuel ratio is deviated and the drivability is deteriorated.

Therefore, the timing of discharging HC from the canister 35 to the intake pipe 21 is controlled so that HC is discharged only when the engine 10 is operating stably, for example, during low load operation or low rotation. Although it is possible to do so, a large number of valves for performing detailed detection of the operating state of the engine 10 and discharge of HC are required, and the device becomes complicated and large.

The present invention is intended to solve such problems, and an object of the present invention is to provide a vaporized gas purifying apparatus for an internal combustion engine which efficiently purifies vaporized gas.

[0015]

A vaporized gas purification apparatus for an internal combustion engine according to the present invention for achieving the above object is a purification apparatus for vaporized gas generated from fuel stored in a fuel tank of an internal combustion engine. A vaporized gas supply means for supplying the generated vaporized gas to the exhaust passage and an air supply means for supplying air to the exhaust passage are provided.

[0016]

The vaporized gas generated from the fuel tank is supplied to the exhaust passage by the vaporized gas supply means, while the air is supplied to the exhaust passage together with the vaporized gas by the air supply means, so that the oxidation reaction occurs and the hydrocarbons are generated. Hazardous substances such as are removed.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram of a vaporized gas purifying apparatus for an internal combustion engine according to an embodiment of the present invention, and FIG. 2 is a flowchart thereof. The members having the same functions as the conventional ones are designated by the same reference numerals, and the duplicated description will be omitted.

In the vaporized gas purifying apparatus of this embodiment,
Evaporated gas supply means for supplying evaporated gas to the exhaust passage and air supply means for supplying air to the exhaust passage are provided.

That is, as shown in FIG. 1, the air cleaner 2
0 is connected to the intake port 11 of the engine 10 via the surge tank 22 by the intake pipe 21.
An air flow sensor 23, a throttle valve 25, and a throttle position sensor 24 are provided in the middle part. An injector 27 is attached to the intake port 11 of the engine 10 and is connected to a fuel tank 28. On the other hand, an exhaust pipe 29 is connected to the exhaust port 12 of the engine 10, and catalytic converters 30 (three-way catalyst), 51 (oxidation catalyst), and a silencer 31 are mounted midway.

A canister 35 is connected to the fuel tank 28 via a discharge pipe 37 having a check valve 36. The canister 35 temporarily stores the evaporated harmful substances such as HC and sucks the harmful substances when the engine 10 is started. The canister 35 is connected to the intake pipe 21 and the exhaust pipe 29 via the two supply pipes 39 and 52. It is connected. That is, the canister 35 is connected to the intake pipe 21 via the supply pipe 39 having the purge amount control valve 38, and is connected to the exhaust pipe 29 via the supply pipe 52 having the switching valve 53, the flame arrester 54, and the reed valve 55. It is connected.

The switching valve 53 is ON / OFF controlled by the ECU 26 and is opened under a predetermined condition so that the vaporized gas can be supplied to the exhaust pipe 29. The flame arrestor 54 is a mesh wire mesh for preventing backflow of combustion flame, and the reed valve 55 is opened by negative pressure on the exhaust pipe 29 side.

On the other hand, in addition to the above-mentioned air cleaner 20 which takes in the primary air and introduces it into the combustion chamber 18 of the engine 10 through the intake pipe 21, an air cleaner 56 which takes in the secondary air is provided. The air cleaner 56 is connected to the exhaust pipe 29 via an intake pipe 59 having a switching valve 57 and a reed valve 58. The switching valve 57 is ON / OFF controlled by the ECU 26 and is opened under a predetermined condition to supply secondary air to the exhaust pipe 29, and the reed valve 59 is opened by a negative pressure on the exhaust pipe 29 side. ..

The air sucked from the air cleaner 20 is supplied to the intake port 11 of the engine 10 via the intake pipe 21 and the surge tank 22, while the injector 27 injects a predetermined amount of gasoline in the fuel tank 28. Then
The mixture of air and gasoline is supplied to the combustion chamber 18. Then, the air-fuel mixture is compressed in the combustion chamber 18 by the vertical movement of the piston 17, and the spark plug 19 generates a spark, which explodes and expands to operate the engine.

While the engine 10 is stopped, the gasoline in the fuel tank 28 is evaporated due to the temperature difference between the engine warm air and the outside air. When the vapor pressure (HC) reaches a predetermined or higher gas pressure, the check valve 36 opens and is sent to the canister 35 via the discharge pipe 37, where it is adsorbed and stored. Then, the vaporized gas is discharged from the canister 35 to the intake pipe 21 via the supply pipe 39, is sent to the combustion chamber 18 of the engine 10 together with the intake air, and is burned.

At this time, if the frequency of use of the vehicle is low in an area where the temperature difference between day and night is large, or if the running time is short even if used, the amount of transpiration gas generated increases and exceeds the adsorption capacity of the canister 35. It may happen. In this case, while the evaporated gas of the canister 35 is supplied to the exhaust pipe 29 by the supply pipe 52, the secondary air sucked from the air cleaner 56 is supplied to the exhaust pipe 29 together with the evaporated gas.
The oxidation catalyst 51 causes the reaction.

That is, the ECU 26 constantly detects the cooling water temperature from the water temperature sensor 33 and constantly detects the engine speed from the crank angle position sensor 34. Therefore, as shown in FIG. 2, in step S1, it is determined whether the water temperature is equal to or higher than a certain temperature and the oxidation catalyst 51 is warmed up, and if so, the process proceeds to step S2.
If the water temperature is not lower than the predetermined temperature, the process proceeds to step S4 and the switching valves 53 and 57 are turned off.
In step S2, it is determined whether the engine 10 has a low load / low rotation, and if so, the process proceeds to step S3 and the switching valves 53 and 57 are turned on.

Then, the switching valve 53 is opened and the vaporized gas of the canister 35 is supplied to the exhaust pipe 29 by the supply pipe 52, while the switching valve 57 is opened and the secondary air from the air cleaner 56 is supplied to the exhaust pipe 29. , The air and the evaporated gas are mixed to form a mixture, which is reacted by the oxidation catalyst 51, and HC is removed. Also,
In step S2, if the engine 10 is not under low load and low rotation, the process proceeds to step S4 and the switching valves 53 and 57 are turned off.

The vaporized gas (HC) thus adsorbed in the canister 35 is supplied to the exhaust pipe 29 through the supply pipe 52, while the secondary air sucked from the air cleaner 56 is supplied to the exhaust pipe 29 together with the vaporized gas for oxidation. Since the reaction is carried out by the catalyst 51, the evaporated gas is passed through the canister 3
It is possible to make the path for discharging from 5 to the intake pipe 21 via the supply pipe 39 simple at low cost, or it is possible to eliminate it, and the canister 35
There is no need to upsize. Then, a large amount of HC is not discharged from the canister 35 to the intake pipe 21, the air-fuel ratio of the engine 10 is not adversely affected, a stable combustion state is obtained, exhaust gas is reduced, and deterioration of drivability is prevented. To be done.

FIG. 3 schematically shows a vaporized gas purifying apparatus for an internal combustion engine according to another embodiment of the present invention. The members having the same functions as those in the above-described embodiment are designated by the same reference numerals, and the duplicated description will be omitted.

In the transpiration gas purification apparatus of this embodiment,
Evaporated gas supply means for supplying evaporated gas to the exhaust passage and air supply means for supplying air to the exhaust passage are provided, and an air pump is used as the evaporated gas supply means. That is, the fuel tank 28 is connected to the canister 35 via the discharge pipe 37, and the canister 35 is connected to the two supply pipes 3.
The intake pipe 21 and the exhaust pipe 29 are respectively connected via 9, 61. The air pump 6 is attached to the supply pipe 61.
2 is installed.

The evaporated gas generated from the fuel tank 28 is stored in the canister 35, and the evaporated gas of the canister 35 is supplied to the exhaust pipe 29 by the supply pipe 61, while the secondary air sucked from the air cleaner 56 is evaporated. It is supplied to the exhaust pipe 29 together with the gas and is reacted by the oxidation catalyst 51. That is, as described above, when the water temperature is equal to or higher than a certain temperature and the engine 10 has a low load and a low rotation speed, the switching valve 57 is turned on and the air pump 6 is operated.
Activate 2. Therefore, the air-fuel mixture in the exhaust pipe 29 reacts with the oxidation catalyst 51 to remove HC.

In each of the above-described embodiments, an air cleaner 56 is provided separately from the air cleaner 20 for sucking the primary air in order to suck the secondary air for forming the air-fuel mixture with the evaporated gas. Although provided, the air cleaner 20 may be shared. For example, if the intake pipe 21 from the air cleaner 20 is branched in the middle and one is connected to the surge tank 22 and the other is connected to the exhaust pipe 29 to supply the primary air and the secondary air, the same as above. It is possible to achieve the action and effect.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Claims (1)

[Claims] 1. A purifying device for a vaporized gas generated from fuel stored in a fuel tank of an internal combustion engine, wherein vaporized gas is supplied to an exhaust passage, and vapor is supplied to the exhaust passage. An apparatus for purifying evaporated gas of an internal combustion engine, comprising: