JPH06167253A - Evaporative fuel control device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Regarding an evaporated fuel control device for an internal combustion engine, the evaporated fuel can be discharged to an exhaust passage without adversely affecting air-fuel ratio control and deterioration determination of a sensor and a catalyst body, Realize a device that is advantageous in purification performance. A control unit for providing a first catalyst body 14 and a second catalyst body 16 in an exhaust passage 12, a first exhaust gas sensor 22 and a second exhaust gas sensor 24, and controlling an air-fuel ratio by detection signals of these exhaust gas sensors. 26, an intake-side discharge passage 38 is provided between the canister 34 and the intake passage 6, and an intake-side discharge control valve 40 that is controlled to be opened and closed by a control unit is provided in the discharge passage.
An exhaust side discharge passage 42 is provided between the canister and the exhaust passage on the downstream side of the second exhaust sensor and on the upstream side of the second catalyst body, and an open / close valve 44 is provided in the middle of this discharge passage, and this open / close valve is controlled by intake negative pressure. A pressure guiding passage 56 is provided between the intake passage and the opening / closing valve to perform the opening operation, and an exhaust side discharge control valve 58 that is controlled to be opened / closed by the control unit is provided in the middle of the pressure guiding passage.

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, and more particularly to an evaporative fuel control system capable of discharging evaporative fuel to an exhaust passage without adversely affecting air-fuel ratio control and deterioration determination of a first exhaust sensor and a first catalyst body. And an evaporative fuel control device that is advantageous in terms of exhaust gas purification performance.

[0002]

2. Description of the Related Art In a vehicle, an evaporative fuel control device is provided to prevent evaporative fuel generated in a fuel tank of an internal combustion engine or a float chamber of a carburetor from leaking to the atmosphere. There is. An example of the evaporated fuel control device is shown in FIG. In FIG. 3, 102 is an internal combustion engine, 104 is an air cleaner, 106 is an intake passage, 108
Is a throttle valve, 110 is a combustion chamber, 112 is an exhaust passage, and 114 is an evaporated fuel control device.

The evaporated fuel control device 114 is used for the fuel tank 1.
Canister 12 communicated with 16 by introduction passage 118
0 is provided, and the canister 120 is provided with an air introduction port 122. The evaporated fuel control device 114 is used for the canister 1
20 is connected to one end side and the throttle valve 10
6. A discharge passage 124 communicating with the other end side is provided to the intake passage 108 on the downstream side, a discharge control valve 126 is provided in the middle of the discharge passage 124, and a control unit 128 as a control means for controlling the opening and closing of the discharge control valve 126 is provided. It is provided.

The evaporative fuel control device 114 is used for the internal combustion engine 10.
When the internal combustion engine 102 is in operation, the evaporative fuel in the fuel tank 116 is adsorbed and held by the canister 120, and the control unit 128 controls the release control valve 126 to open and close. As a result, the vaporized fuel adsorbed and held by the canister 120 is released and released by the fresh air introduced from the atmosphere introduction port 122, and is released to the intake passage 106 by the release passage 122 and burned.

In this way, the intake passage 1 of the internal combustion engine 102
In the case of releasing the vaporized fuel in 06, there is a regulation that requires a larger amount of the vaporized fuel to be released than in the past. If a large amount of evaporated fuel is discharged to the intake passage in order to satisfy such regulations, there is a problem that the air-fuel ratio is changed, which adversely affects drivability and exhaust gas purification performance.

Therefore, as disclosed in Japanese Utility Model Application Laid-Open No. 57-31553, an exhaust side discharge passage for guiding the evaporated fuel collected in the canister to the exhaust passage is provided, and a valve is provided in the middle of the exhaust side discharge passage. A device is provided, and when the internal combustion engine is warmed by the valve device until secondary combustion is performed in the exhaust passage, the exhaust side discharge passage is opened to allow the evaporated and trapped fuel to flow in one direction from the canister toward the exhaust passage. There is something that leads to.

[0007]

By the way, as disclosed in the above publication, in the evaporative fuel control device for releasing the evaporative fuel to the exhaust passage, the evaporative fuel is provided in the exhaust passage upstream of the catalyst provided in the exhaust passage. Is released. In the evaporative fuel control device that releases evaporative fuel to the exhaust passage in this way, when the first catalyst body and the second catalyst body are sequentially provided from the upstream side of the exhaust passage, the upstream side of the first catalyst body Evaporative fuel is discharged to the exhaust passage of the.

However, when the air-fuel ratio is controlled by the exhaust sensor provided in the exhaust passage on the upstream side of the first catalyst,
If the evaporated fuel is discharged to the exhaust passage on the upstream side of the first catalyst body, it will affect the detection signal of the first exhaust sensor, which will adversely affect the control of the air-fuel ratio.

A first exhaust sensor and a second exhaust sensor are provided in the exhaust passage upstream of the first catalyst body and the exhaust passage downstream of the first catalyst body and upstream of the second catalyst body, respectively. When the air-fuel ratio is controlled by the detection signals of the first exhaust sensor and the second exhaust sensor and the deterioration determination of the first exhaust sensor and the first catalyst body is performed, the evaporated fuel is provided in the exhaust passage on the upstream side of the first catalyst body. When released, the first
This affects the detection signal of the exhaust sensor, which adversely affects the control of the air-fuel ratio and also adversely affects the deterioration determination of the first exhaust sensor and the first catalyst body.

[0010]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention provides a first catalyst body and a second catalyst body in the exhaust passage of an internal combustion engine sequentially from the upstream side, and the first catalyst body is provided. A first exhaust sensor and a second exhaust sensor are provided in the exhaust passage on the upstream side of the medium and the exhaust passage on the downstream side of the first catalyst body and on the upstream side of the second catalyst body, respectively. Control means for controlling the air-fuel ratio by each detection signal of the sensor is provided, and one end side is communicated with a canister that adsorbs and holds evaporated fuel of the internal combustion engine, and the other intake side discharge is communicated with the intake passage of the internal combustion engine. A passage is provided, and an intake side discharge control valve whose opening and closing is controlled by the control means is provided in the middle of the intake side discharge passage, one end side of which is connected to the canister, and the downstream side of the second exhaust sensor and the second catalyst. An exhaust side discharge passage communicating with the other end side is provided in the upstream side exhaust passage, an opening / closing valve is provided in the middle of the exhaust side discharge passage, and the opening / closing valve is opened at one end in the intake passage to be opened by negative intake pressure. A pressure guiding passage that communicates the other side with the on-off valve is provided, and an exhaust side discharge control valve whose opening and closing is controlled by the control means is provided in the pressure guiding passage in the middle of the pressure guiding passage.

[0011]

According to the structure of the present invention, the evaporated fuel control device can discharge the evaporated fuel not only to the intake passage but also to the exhaust passage by the intake side discharge passage and the exhaust side discharge passage. Further, the evaporated fuel control device may influence the detection signal of the exhaust sensor by communicating the exhaust side discharge passage with the exhaust passage on the downstream side of the second exhaust sensor and on the upstream side of the second catalyst body. Absent.

[0012]

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

FIG. 1 shows an embodiment of the present invention. In FIG. 1, 2 is an internal combustion engine mounted on a vehicle (not shown), 4 is an air cleaner, 6 is an intake passage, 8 is a throttle valve, 10 is a combustion chamber, and 12 is an exhaust passage.
The internal combustion engine 2 is provided with a first catalyst body 14 and a second catalyst body 16 in the exhaust passage 12 sequentially from the upstream side. The first catalyst body 14 and the second catalyst body 16 are held by the first catalyst body case 18 and the second catalyst body case 20, which are formed independently of each other, and are provided in the exhaust passage 12 while being separated from each other.

Exhaust passage 1 upstream of the first catalyst body 14
2 and the downstream side of the first catalyst body 14 and the second catalyst body 16
A first O2 sensor 22, which is a first exhaust sensor, and a second O2 sensor 24, which is a second exhaust sensor, are provided in the exhaust passage 12 on the upstream side. The first O2 sensor 22 and the second O2 sensor 24 are connected to a control unit 26 which is a control means. The control unit 26 inputs the detection signals of the first O2 sensor 22 and the second O2 sensor 24, adjusts the fuel amount of the fuel system and / or the air amount of the intake system (not shown), and controls the air-fuel ratio.

The internal combustion engine 2 includes an evaporated fuel control device 28.
Is equipped with. The evaporated fuel control device 28 is used for the fuel tank 3
A canister 34 communicating with the introduction passage 32 is provided at 0, and an atmosphere introduction port 36 is provided at the canister 34. The evaporated fuel control device 28 is provided with an intake-side discharge passage 38 that communicates one end side with the canister 34 and communicates the other end side with the intake passage 6 on the downstream side of the throttle valve 8. A side release control valve 40 is provided. The intake side release control valve 40 is provided in the control unit 26.
It is provided by connecting to.

The evaporative fuel control device 28 has one end connected to the canister 34 and the second O 2 sensor 24.
An exhaust side discharge passage 42 communicating with the other end side of the exhaust passage 12 on the downstream side and on the upstream side of the second catalyst body 16 is provided. In the illustrated example, the canister 34 and the intake side discharge control valve 4
In the intake side discharge passage 38 between 0 and 0, the exhaust side discharge passage 42
One end side of the is connected and provided. This exhaust side discharge passage 4
An on-off valve 44 is provided in the middle of 2.

This on-off valve 44 is provided in the main body 46 by partitioning a pressure chamber 50 with a diaphragm 48, a valve body 52 for opening and closing the exhaust side discharge passage 42 is attached to the diaphragm 48, and the pressure chamber 50 is provided with an exhaust side. The diaphragm 48 pushes the valve body 52 in the direction of closing the discharge passage 42.
A spring 54 for urging is provided.

The opening / closing valve 44 is provided with a pressure guiding passage 56 communicating one end side with the intake passage 6 and the other end side with the pressure chamber 50 for opening operation by the intake negative pressure. An exhaust side discharge control valve 58 is provided in the middle of the pressure guiding passage 56. The exhaust side discharge control valve 58 is provided so as to be connected to the control unit 26.

A pump 60 is provided between the canister 34 and the opening / closing valve 44, and a one-way valve 62, which is a reed valve, is provided between the opening / closing valve 44 and the exhaust passage 12, in the exhaust side discharge passage 42. ing. Therefore, in the exhaust side discharge passage 42, from the canister 34 to the exhaust passage 12
A pump 60, an on-off valve 44, and a one-way valve 62 are sequentially provided toward the. The one-way valve 62 is provided in the exhaust passage 1
It is opened and closed by the pressure difference of the exhaust pulsation generated in 2.

Next, the operation will be described.

When the internal combustion engine 2 is stopped, the evaporated fuel control device 28 controls the control unit 26 to close the intake side discharge control valve 40 and the exhaust side discharge control valve 58, and the intake side discharge passage 38.
And the exhaust side discharge passage 42 is closed. As a result, the evaporated fuel generated in the fuel tank 30 is introduced into the canister 34 through the introduction passage 32, and is adsorbed and held.

When the operating state of the internal combustion engine 2 satisfies a predetermined condition during the operation of the internal combustion engine 2, the evaporative fuel control device 28 causes the control unit 26 to control the intake side release control valve 38 and the exhaust side release according to the operating state. The control valve 58 is controlled to open and close.

As a result, the evaporated fuel adsorbed and held in the canister 34 is released and released by the fresh air introduced from the air inlet 36, and is opened and closed by the intake side release control valve 40 to pass through the intake side release passage 38. It is discharged to the intake passage 6 and burned.

Further, the evaporated fuel control device 28 causes the negative pressure of the intake air to act on the pressure chamber 50 of the opening / closing valve 44 through the pressure guiding passage 56 by the opening / closing control of the exhaust side discharge control valve 58, and the opening / closing valve 4
Open and close 4 As a result, the evaporated fuel released from the canister 34 is discharged to the exhaust passage 12 on the downstream side of the second O2 sensor 24 and the upstream side of the second catalyst body 16 via the exhaust side discharge passage 42, and is burned.

At this time, the vaporized fuel discharged into the exhaust passage 12 is pumped by the pump 60 and is prevented from flowing backward from the exhaust passage 12 side through the one-way valve 62 which is opened and closed by the exhaust pulsation. 12 will be released.

As a result, the evaporated fuel control device 28
Not only transfers the evaporated fuel to the intake passage 6 but also the exhaust passage 12
Can also be released. For this reason, even if the load on the intake passage 6 is reduced, a large amount of evaporated fuel can be discharged to the intake passage 6 and the exhaust passage 12 as a whole, so that the regulations that have become strict in recent years can be sufficiently satisfied. Therefore, it is possible to meet the regulation that requires the release of a larger amount of evaporated fuel than before, and it is possible to reduce the adverse effect on the atmosphere, which is practically advantageous.

Further, the load on the intake passage 6 can be reduced,
The influence on the internal combustion engine 2 can be made small, the influence on the control of the air-fuel ratio can be made small, the exhaust gas purification performance can be made advantageous, and when the evaporated fuel is supplied, the intake passage 6
By being able to control simultaneously or independently so as to release the amount that makes use of the respective characteristics of the exhaust passage 12 and
It is extremely effective in purification of exhaust gas and control of evaporated fuel.

Further, the evaporative fuel control system 28 communicates the exhaust-side discharge passage 42 with the exhaust passage 12 on the downstream side of the second O 2 sensor 24 and on the upstream side of the second catalyst body 16, so that It does not affect the detection signals of the second O2 sensors 22 and 24. Therefore, the evaporated fuel can be discharged to the exhaust passage 12 without adversely affecting the control of the air-fuel ratio and the deterioration determination of the first O2 sensor 22 and the first catalyst body 14, and the exhaust purification performance is also advantageous.

Further, since the pump 60 and the one-way valve 62 are provided in the exhaust side discharge passage 42, the evaporated fuel can be forcibly supplied by the pump 60, and the evaporated fuel to the exhaust passage 12 can be supplied. The exhaust gas can be reliably discharged, and the one-way valve 62 can prevent the exhaust gas from flowing backward from the exhaust passage 12, and the on-off valve 44 and the pump 60 can be protected from the high heat of the exhaust gas.

The present invention is not limited to the above-mentioned embodiment, but various application modifications are possible. For example,
In the above-described embodiment, the first catalyst body 14 and the second catalyst body 16 are independently provided in the exhaust passage 12 sequentially from the upstream side, but as shown in FIG. 2, the catalyst body case 6 integrally formed.
4, the first catalyst body 14 and the second catalyst body 16 are held apart from each other, and the exhaust passage 12 outside the catalyst body case 64 on the upstream side of the first catalyst body 14 and the downstream side of the first catalyst body 14 and The first O2 sensor 22 and the second O2 sensor 24 are respectively provided in the exhaust passage 12 in the catalyst case 64 on the upstream side of the two catalysts 16.
And an exhaust side discharge passage 42 communicating one end side with the canister 34 and communicating the other end side with the exhaust passage 12 in the catalyst case 64 on the downstream side of the second O2 sensor 24 and the upstream side of the second catalyst body 16. Can be provided.

[0031]

As described above, according to the present invention, the evaporated fuel control device can discharge the evaporated fuel not only to the intake passage but also to the exhaust passage. Therefore, it is possible to satisfy the regulation that requires the release of a larger amount of evaporated fuel than in the past. Further, the evaporative fuel control device includes a second exhaust passage on the exhaust side.
By communicating with the exhaust passage on the downstream side of the exhaust sensor and on the upstream side of the second catalyst, the detection signals of the first and second exhaust sensors are not affected. Therefore, the evaporated fuel can be discharged to the exhaust passage without adversely affecting the control of the air-fuel ratio and the deterioration determination of the first exhaust sensor and the first catalyst body, which is also advantageous in the exhaust purification performance.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an evaporated fuel control device showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an evaporated fuel control device showing another embodiment.

FIG. 3 is a schematic configuration diagram of an evaporated fuel control device showing a conventional example.

[Explanation of symbols]

 2 Internal combustion engine 6 Intake passage 10 Combustion chamber 12 Exhaust passage 14 First catalyst body 16 Second catalyst body 22 First O2 sensor 24 Second O2 sensor 26 Control unit 28 Evaporative fuel control device 30 Fuel tank 32 Introduction passage 34 Canister 36 Atmosphere introduction port 38 Intake-side discharge passage 40 Intake-side discharge control valve 42 Exhaust-side discharge passage 44 Open / close valve 56 Pressure passage 58 Exhaust-side discharge control valve 60 Pump 62 One-way valve

Claims (1)

[Claims] 1. A first catalyst body and a second catalyst body are sequentially provided from an upstream side in an exhaust passage of an internal combustion engine, and an exhaust passage upstream of the first catalyst body and a downstream side of the first catalyst body are provided. The first exhaust sensor and the second exhaust sensor are provided in the exhaust passages on the upstream side of the two catalysts, respectively.
An exhaust gas sensor is provided, and control means for controlling the air-fuel ratio based on the detection signals of the first exhaust gas sensor and the second exhaust gas sensor is provided, one end side of which communicates with a canister for adsorbing and holding evaporated fuel of the internal combustion engine, and the internal combustion engine. An intake side discharge passage communicating with the other end side is provided in the intake passage of the engine, an intake side discharge control valve whose opening and closing is controlled by the control means is provided in the intake side discharge passage, and one end side is communicated with the canister. Together with the second exhaust sensor downstream of the second exhaust sensor
An exhaust side discharge passage communicating with the other end side of the exhaust passage on the upstream side of the catalyst body is provided, an opening / closing valve is provided in the middle of the exhaust side discharge passage, and the opening / closing valve is opened by negative intake pressure. A pressure guide passage communicating one end side with the other end side of the on-off valve, and an exhaust side discharge control valve controlled to be opened and closed by the control means in the middle of the pressure guide passage. Evaporative fuel control device.