JPH0539754A - Evaporation system - Google Patents

Abstract

PURPOSE:To allow airtightness to be easily judged and emission of evaporated fuel to an intake passage to be judged by closing a purge control valve and a new air control valve and monitoring the detected pressure value of a pressure sensor when the inside of an evaporation system is air-tight. CONSTITUTION:An evaporation system 18 has a canister 22 in a ventilation passage between a fuel tank 16 and a surge tank 10 on the downstream side of an intake throttle valve 14 and a purge control valve 24 provided in the ventilation passage 20 further downstream from the canister 22. In addition, a new air control valve 32 is provided in the middle of a new air passage 30 which introduces new air into the canister 22. To judge the airtightness of the evaporation system, the purge control valve is closed using a control section and the new air valve 32 is closed via an operation control valve 44. When the ventilation passage 20 and the new air passage 30 are closed as stated above, if a pressure sensor 52 provided in a connecting passage 50 detects positive pressure, it is judged that the evaporation system 18 has no leak and is air-tight.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative system, and more particularly to an evaporative system which can easily determine the airtightness of an evaporative system and the release of evaporated fuel, and has a simple structure and can be implemented at low cost. ..

[0002]

2. Description of the Related Art Evaporative fuel leaking into the atmosphere from a fuel tank, a float chamber of a carburetor, etc., contains a large amount of hydrocarbons (HC) and is one of the causes of air pollution. Because of the connection, various techniques for preventing this are known. As a typical example, when the internal combustion engine is stopped, the canister containing an adsorbent such as activated carbon adsorbs the evaporated fuel in the fuel tank, and when the internal combustion engine is operating, the evaporated fuel adsorbed in the canister is released and released to the intake passage. There is an evaporative system that does.

As such an evaporation system, for example, Japanese Utility Model Laid-Open No. 56-20055 and Japanese Utility Model Laid-Open No. 58-111.
No. 348 and Japanese Utility Model Laid-Open No. 57-193955. In the one disclosed in Japanese Utility Model Laid-Open No. 56-20055, the fresh air passage of the canister communicates with the intake passage between the air flow meter and the throttle valve and the atmosphere through a control valve, and the fresh air passage of the canister is opened when the engine is stopped. The control valve is controlled so as to communicate with the intake passage between the air flow meter and the throttle valve and to communicate the fresh air passage of the canister with the atmosphere when the engine is driven. 58-1
The one disclosed in Japanese Patent No. 11348 is to energize a heater provided in a fresh air passage of a canister when a throttle valve is in a closed position. Actual exploitation 57-19395
The device disclosed in Japanese Patent No. 5 is such that an opening / closing valve is provided in the fresh air passage of the canister, and this opening / closing valve is closed when the engine is stopped and during idling operation to cut off communication with the atmosphere.

[0004]

By the way, in such an evaporative system, regulation of exhaust harmful components has become stricter in recent years, and therefore it is required to judge the function of the evaporative system. For example, as a function of the evaporative system, it is required to be able to quickly determine that the evaporative system is leak-free and airtight, and that the evaporated fuel is released.

However, conventionally, there is no evaporative system having a function capable of determining both airtightness and release of evaporated fuel, and it has been desired to realize an evaporative system having such a function.

[0006]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention provides a canister in the middle of an air passage extending from a fuel tank to an intake passage of an internal combustion engine, and a canister is provided downstream of the canister. A purge control valve is provided in the ventilation passage, a fresh air control valve is provided in the fresh air passage for introducing fresh air into the canister, and a pressure guiding passage communicating one end side with the ventilation passage upstream of the purge control valve is provided. The pressure guiding passage is provided with the other end of the pressure guiding passage in communication with the pressure sensor, and the ventilation passage and the fresh air passage downstream of the communicating portion at one end of the pressure guiding passage are closed and the pressure guiding is performed. In order to judge the function of the evaporative system based on the pressure value detected by the pressure sensor, respectively, in the state where the ventilation passage downstream of the communicating portion on one end side of the passage and the fresh air passage are opened, the purge control valve and the new Characterized in that a control means for controlling opening and closing of the control valve.

[0007]

According to the structure of the present invention, the control means controls the opening and closing of the purge control valve and the fresh air control valve, and closes the ventilation passage and the fresh air passage on the downstream side of the communicating portion on one end side of the pressure guiding passage. The function of the evaporation system is determined by the pressure value detected by the pressure sensor in each of the above state and the state in which the ventilation passage and the fresh air passage downstream of the communicating portion on one end side of the pressure guiding passage are opened. That is, the airtightness can be determined whether or not there is a leak by monitoring the pressure value detected by the pressure sensor in the state where the inside of the evaporation system is airtight by controlling the closing of the purge control valve and the fresh air control valve. .. Further, by checking the opening of the purge control valve and the fresh air control valve to monitor the pressure value detected by the pressure sensor in the state where the canister is in communication with the intake passage, it is possible to check whether or not the evaporated fuel is released into the intake passage. Can be determined.

[0008]

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

FIG. 1 shows a first embodiment of the present invention. In FIG. 1, 2 is an internal combustion engine, and 4 is an intake passage. The intake passage 4 is formed by an air cleaner 6, a throttle body 8, a surge tank 10, and an intake manifold 12. An intake throttle valve 14 is provided in the intake passage 4 in the throttle body 8. Further, the internal combustion engine 2 is provided with a fuel tank 16 that stores fuel.

The internal combustion engine 2 includes an evaporation system 18
Is provided. The evaporation system 18 is provided with an air passage 20 that extends from the fuel tank 16 to the surge tank 10, which is the intake passage 4 on the downstream side of the intake throttle valve 14 of the internal combustion engine 2. A canister 22 is provided in the middle of the air passage 20. Ventilation path 20 downstream of this canister 22
A purge control valve 24 is provided in the. Purge control valve 2
Reference numeral 4 includes a solenoid 26 and a valve body 28 that is driven by the solenoid 26 to open and close the ventilation path 20.

Further, the canister 22 is provided with a fresh air passage 30 for introducing fresh air. A fresh air control valve 32 is provided in the fresh air passage 30. The fresh air control valve 32 is
The fresh air passage 30 is provided in the diaphragm 36 that partitions the pressure chamber 34.
A valve element 38 for opening and closing the valve is provided, and a spring 40 for urging the fresh air passage 30 in the direction of opening is provided.

The pressure chamber 34 of the fresh air control valve 32 is connected to the surge tank 10 which is the intake passage 4 on the downstream side of the intake throttle valve 14 by the negative pressure passage 42. An operation control valve 44 is provided in the negative pressure passage 42. The operation control valve 44 is
It is composed of a solenoid 46 and a valve element 48 that is driven by the solenoid 46 to open and close the negative pressure passage 42, and controls the operation of the fresh air control valve 32 by supplying and blocking intake negative pressure to the pressure chamber 34.

One end of a pressure guiding passage 50 is provided in communication with the ventilation passage 20 upstream of the purge control valve 24 and downstream of the canister 22. The other end of the pressure guiding passage 50 is provided so as to communicate with the pressure sensor 52. The purge control valve 24, the operation control valve 44, and the pressure sensor 52 are connected to a control unit 54 which is a control means.

The control section 54 includes a ventilation passage 20 and a fresh air passage 30 on the downstream side of a communicating portion on one end side of the pressure guiding passage 50.
In the closed state and in a state in which the ventilation passage 20 and the fresh air passage 30 on the downstream side of the communicating portion on the one end side of the pressure guiding passage 50 are opened, the evaporation system 18 is controlled by the pressure values detected by the pressure sensor 52. In order to determine the function of, the purge control valve 24 is controlled to be opened / closed and the fresh air control valve 32 is controlled to be opened / closed via the operation control valve 44.

The operation of the first embodiment will be described.

The purge control valve 24 is controlled by the controller 54 to determine whether the evaporative system 18 is leak-free and airtight.
Is closed and the fresh air control valve 32 is closed via the operation control valve 44 to close the ventilation passage 20 and the fresh air passage 30 on the downstream side of the communicating portion on one end side of the pressure guiding passage 50. It will be in the state where it did. In this way, the pressure value detected by the pressure sensor 52 is monitored with the ventilation passage 20 and the fresh air passage 30 closed.

The pressure sensor 52 closes the ventilation passage 20 and the fresh air passage 30, so that the evaporation system 18 is closed.
When there is no leakage inside and the inside is airtight, the positive pressure P1 is detected by the evaporated fuel generated in the fuel tank 14. As a result, the pressure value detected by the pressure sensor 52 is the positive pressure P in a state where the ventilation passage 20 and the fresh air passage 30 on the downstream side of the communicating portion on one end side of the pressure guiding passage 50 are closed.
If it is 1, it can be determined that the inside of the evaporation system 18 is airtight.

Therefore, the purge control valve 24 and the fresh air control valve 32 are controlled to be closed to monitor the pressure value detected by the pressure sensor 52 in a state where the inside of the evaporation system 18 is made airtight, thereby checking whether or not there is a leak. Airtightness can be determined.

The controller 54 determines whether the evaporated fuel is being discharged to the intake passage 4 by the evaporation system 18.
Thus, the purge control valve 24 is controlled to be opened, and the fresh air control valve 32 is controlled to be opened via the operation control valve 44 to bring the canister 22 into communication with the intake passage 4. In this way, the pressure value detected by the pressure sensor 52 is monitored under normal operating conditions in which the canister 22 is in communication with the intake passage 4.

The pressure sensor 52, when the evaporated fuel is discharged to the intake passage 4 by the evaporation system 18,
The negative pressure P2 acting from the intake passage 4 is detected. As a result, when the canister 22 is in communication with the intake passage 4 and the pressure value detected by the pressure sensor 52 is the negative pressure P2, it is determined that the evaporated fuel is released from the canister 22 to the intake passage 4. You can

Therefore, the purge control valve 24 and the fresh air control valve 32 are controlled to open to monitor the pressure value detected by the pressure sensor 52 in a state where the canister 22 is in communication with the intake passage 4, and thereby the intake passage 4 is opened. It can be determined whether the evaporated fuel is being released.

In this way, the airtightness of the evaporation system 18 and the release of the evaporated fuel are judged by controlling the opening and closing of the purge control valve 24 and the fresh air control valve 32 to monitor the pressure value detected by the pressure sensor 52. This can be done easily. Also,
Since the configuration is simple and the control software is relatively simple, it can be implemented at low cost. Moreover, it is practically advantageous that the existing control means, for example, a control unit for fuel control can be used in the internal combustion engine 2. In the first embodiment, the operation of the fresh air control valve 32 provided in the fresh air passage 30 is controlled by the operation control valve 44. However, the fresh air control valve 32 is controlled without the operation control valve 44.
It is also possible to directly control the operation by means of 4.

Next, a second embodiment of the present invention will be described.

2 to 4 show a second embodiment of the present invention. In FIG. 2, 102 is an internal combustion engine, 10
Reference numeral 4 is an intake passage. The intake passage 104 includes an air cleaner 106, a throttle body 108, and a surge tank 110.
And the intake manifold 112. An intake throttle valve 114 is provided in the intake passage 104 in the throttle body 108. Further, the internal combustion engine 102 is provided with a fuel tank 116 that stores fuel.

The internal combustion engine 102 is provided with an evaporation system 118. The evaporative system 118 operates from the fuel tank 116 to the intake throttle valve 114 of the internal combustion engine 102.
An air passage 120 is provided to reach the surge tank 110, which is the intake passage 104 on the downstream side. A canister 122 is provided in the air passage 120. A purge control valve 124 is provided in the air passage 120 on the downstream side of the canister 122. The purge control valve 124 includes a solenoid 126 and a valve body 128 that is driven by the solenoid 126 to open and close the ventilation path 120.

Further, the canister 122 is provided with a fresh air passage 130 for introducing fresh air. This fresh air passage 1
A fresh air control valve 132 is provided at 30. The fresh air control valve 132 is a diaphragm 136 that partitions the pressure chamber 134.
A valve body 138 for opening and closing the fresh air passage 130, and a spring 140 for urging the fresh air passage 130 in the opening direction.
Is provided.

The pressure chamber 134 of the fresh air control valve 132 is connected to the surge tank 110, which is the intake passage 104 on the downstream side of the intake throttle valve 114, by the negative pressure passage 142. An operation control valve 144 is provided in the negative pressure passage 142. The operation control valve 144 includes a solenoid 146 and a valve element 148 that is driven by the solenoid 146 to open and close the negative pressure passage 142, and supplies intake negative pressure to the pressure chamber 134.
By shutting off, the operation of the fresh air control valve 132 is controlled.

One end of the first pressure guiding passage 150 is connected to the ventilation passage 120 upstream of the purge control valve 124 and downstream of the canister 122. Further, in the air passage 120 on the upstream side of the canister 124,
One end side of the second pressure guiding passage 152 is provided so as to communicate with each other. The other end sides of the first and second pressure guiding passages 150, 152 collectively communicate with one end side of the third pressure guiding passage 154, and the other end side of the third pressure guiding passage 154 is connected to the pressure sensor 156. To communicate with.

The first and second pressure guiding passages 150 and 152 are provided at the locations where the first to third pressure guiding passages 150 to 154 gather.
Control valve 15 for switching and communicating with the third pressure guiding passage 154
8 is provided. As shown in FIGS. 3 and 4, the switching control valve 158 includes a solenoid 160 and a valve element 162 that is driven by the solenoid 160 to relatively open and close the first pressure passage 150 and the second pressure passage 152. Therefore, the first pressure guiding passage 150 and the second pressure guiding passage 1 are provided with respect to the third pressure guiding passage 154.
52 for switching communication.

The purge control valve 124 and the operation control valve 14
4, the pressure sensor 156, and the switching control valve 158 are connected to the control unit 164 serving as control means. Control unit 164
Closes the ventilation passage 120 and the fresh air passage 130 on the downstream side of the communicating portion on one end side of the first pressure guiding passage 150 and closes the first pressure guiding passage 150 to close the second pressure guiding passage 152 and the second pressure guiding passage 152. The third pressure guiding passage 154 is in communication with the first pressure guiding passage 1
Ventilation path 12 on the downstream side of the communicating portion on one end side of 50
0 and the fresh air passage 130 are opened and the first pressure guiding passage 150 is opened.
To close the second pressure guiding passage 152 and the third pressure guiding passage 154.
And the ventilation passage 120 and the fresh air passage 13 on the downstream side of the communicating portion on the one end side of the first pressure guiding passage 150.
0 is opened and the second pressure guiding passage 152 is closed to connect the first pressure guiding passage 150 and the third pressure guiding passage 154,
In order to judge the function of the evaporation system 118 by the pressure value detected by the pressure sensor 156 respectively, the purge control valve 124 and the fresh air control valve 144 are opened / closed and the switching control valve 158 is switched.

The operation of the second embodiment will be described.

To determine that the evaporative system 118 is leak-free and airtight, the control section 164 controls the purge control valve 124 to close, and the operation control valve 144 to control the fresh air control valve 132 to close. , The ventilation passage 120 and the fresh air passage 130 on the downstream side of the communicating portion on the one end side of the first pressure guiding passage 150 are closed, and the switching control valve 158 is switched to control the first pressure guiding passage 150. The second pressure guiding passage 152 and the third pressure guiding passage 154 are brought into communication with each other by closing.
As described above, the pressure value detected by the pressure sensor 156 is monitored in a state where the ventilation passage 20 and the fresh air passage 30 are closed and the second pressure guiding passage 152 and the third pressure guiding passage 154 are communicated with each other.

Since the pressure sensor 156 closes the ventilation passage 20 and the fresh air passage 30, the evaporation system 1
If there is no leak in 18 and it is airtight, the fuel tank 1
The positive pressure P1 is detected by the fuel vapor generated in the fuel cell 14.

The control unit 164 controls the purge control valve 1
24 and the closing control of the fresh air control valve 132 are released. That is, the control unit 164 controls the opening of the purge control valve 124, and controls the opening of the fresh air control valve 132 via the operation control valve 144 so that the first pressure guiding passage 150 is downstream of the communicating portion on the one end side. The air passage 120 and the fresh air passage 130 on the side are opened, the first pressure passage 150 is closed, and the second pressure passage 152 and the third pressure passage 154 are communicated. In this way, the ventilation passage 20 and the fresh air passage 30 are opened, and the second pressure guiding passage 152 and the third pressure guiding passage 154 are opened.
The pressure value detected by the pressure sensor 156 is monitored in the state of communicating with the.

The pressure sensor 156 opens the air passage 120 and the fresh air passage 130 and discharges the evaporated fuel to the intake passage 4, so that the pressure in the fuel tank 114 lowers and the pressure is higher than the positive pressure P1. A weak positive pressure P1 'will be detected.

As a result, the ventilation passage 120 and the fresh air passage 130 on the downstream side of the communicating portion on the one end side of the first pressure guiding passage 150 are closed, and the second pressure guiding passage 152 and the third pressure guiding passage 152 are closed.
When the evaporative system 118 is airtight with no leakage in the state where the pressure guiding passage 154 is in communication, the pressure value detected by the pressure sensor 156 becomes the positive pressure P1, and the first pressure
The air passage 120 and the fresh air passage 130 on the downstream side of the communicating portion on one end side of the pressure guide passage 150 are opened, and the second passage
In a state where the pressure guiding passage 152 and the third pressure guiding passage 154 are communicated with each other, when the evaporated fuel is released to the intake passage 4, the pressure value detected by the pressure sensor 156 is a positive pressure weaker than the positive pressure P1. By becoming P1 ', the evaporative system 1
The airtightness in 18 can be determined accurately.

Moreover, since the first pressure guiding passage 150 is closed and the second pressure guiding passage 152 and the third pressure guiding passage 154 are communicated with each other, the pressure in the fuel tank 114 is quickly introduced into the pressure sensor 156. Therefore, the detection accuracy can be improved, which can contribute to the improvement of the determination accuracy.

Further, it is judged whether or not the evaporated fuel is released to the intake passage 104 by the evaporation system 118, the control unit 164 controls the opening of the purge control valve 124, and the operation control valve 144 controls the fresh air control valve 132. To control the opening of the canister 122 to communicate with the intake passage 104,
In addition, the switching control valve 158 is switched and controlled to close the second pressure guiding passage 152 and close the first pressure guiding passage 150 and the third pressure guiding passage 1.
54 is communicated. In this way, the air passage 120
And the fresh air passage 130 is closed, and the first pressure guiding passage 15
The pressure value detected by the pressure sensor 164 is monitored under normal operating conditions in which 0 and the third pressure guiding passage 154 are communicated.

The pressure sensor 164 is the evaporation system 11
When the vaporized fuel is discharged to the intake passage 104 by 8, the negative pressure P2 acting from the intake passage 104 via the first pressure guiding passage 150 and the third pressure guiding passage 154 is detected. Thus, if the pressure value detected by the pressure sensor 164 is the negative pressure P2 in the state where the canister 122 communicates with the intake passage 104, the intake passage 104
It can be determined that the evaporated fuel is being released from the canister 122.

Therefore, the purge control valve 124 and the fresh air control valve 132 are controlled to open so that the canister 122 communicates with the intake passage 104, and the first pressure guide passage 150 and the third pressure passage 150 are connected.
Pressure sensor 16 in a state in which pressure guiding passage 154 is in communication
By monitoring the pressure value detected by No. 4, the intake passage 1
It is possible to determine whether or not the vaporized fuel is released in 04.

Moreover, since the second pressure guiding passage 152 is closed and the first pressure guiding passage 150 and the third pressure guiding passage 154 are communicated with each other, the intake negative pressure in the intake passage 104 is promptly applied to the pressure sensor 156. It is possible to improve the detection accuracy and contribute to the improvement of the determination accuracy.

In this way, the purge control valve 124 and the fresh air control valve 132 are controlled to open and close, and the switching control valve 1 is used to judge the airtightness of the evaporation system 118 and the release of the evaporated fuel.
By controlling the switching of the pressure sensor 58 and monitoring the pressure value detected by the pressure sensor 52, the pressure value can be easily achieved, and the pressure can be quickly introduced into the pressure sensor 156 to improve the detection accuracy. It can contribute to the improvement of accuracy. Further, the configuration is simple and the control software is relatively simple, so that it can be implemented at low cost. Moreover, it is practically advantageous that the existing control means, such as a control unit for fuel control, can be used in the internal combustion engine 102.
In the second embodiment, the operation of the fresh air control valve 132 provided in the fresh air passage 130 is controlled by the operation control valve 144, but the fresh air control valve 132 is controlled without the operation control valve 144. It is also possible to directly control the operation.

[0043]

As is apparent from the above detailed description, according to the present invention, the pressure value detected by the pressure sensor in the state in which the purge control valve and the fresh air control valve are closed and the evaporative system is hermetically sealed. Airtightness can be determined for leaks by monitoring the. Further, by checking the opening of the purge control valve and the fresh air control valve to monitor the pressure value detected by the pressure sensor in the state where the canister is in communication with the intake passage, it is possible to check whether or not the evaporated fuel is released into the intake passage. Can be determined.

Therefore, the determination of the airtightness of the evaporative system and the release of the evaporated fuel can be easily made by controlling the opening / closing of various control valves and monitoring the pressure value detected by the pressure sensor. Is simple and the control software is relatively simple, so it can be implemented at low cost.
Moreover, the existing control means can be used for the internal combustion engine, which is practically advantageous.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an evaporation system showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an evaporation system showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view of the switching control valve in a state where the third pressure guiding passage is switched and communicated with the second pressure guiding passage.

FIG. 4 is a cross-sectional view of the switching control valve in a state where the first pressure guiding passage is switched and communicated with the second pressure guiding passage.

[Explanation of symbols]

 2 Internal combustion engine 4 Intake passage 6 Air cleaner 8 Throttle body 10 Surge tank 12 Intake manifold 14 Intake throttle valve 16 Fuel tank 18 Evaporation system 20 Ventilation passage 22 Canister 24 Purge control valve 30 Fresh air passage 32 Fresh air control valve 42 Negative pressure passage 44 Operation control valve 50 Pressure passage 52 Pressure sensor 54 Control unit

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[Procedure amendment]

[Submission date] September 20, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

Claims (1)

[Claims] 1. A fresh air for introducing fresh air into the canister by providing a canister in the middle of the air passage from the fuel tank to the intake passage of the internal combustion engine, and providing a purge control valve in the air passage downstream of the canister. A fresh air control valve is provided in the passage, a pressure guiding passage communicating one end side with the ventilation passage upstream of the purge control valve is provided, and the other end side of the pressure guiding passage is provided communicating with the pressure sensor, The closed state of the air passage and the fresh air passage downstream of the communicating portion on one end side of the pressure guiding passage, and the ventilation passage and the fresh air downstream of the communicating portion on the one end side of the pressure guiding passage. The evaporation system is provided with a control means for controlling the opening and closing of the purge control valve and the fresh air control valve in order to judge the function of the evaporation system based on the pressure value detected by the pressure sensor when the passage is opened. Mu.