JPH08232777A - Vaporizing fuel control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To prevent discharge of vaporizing fuel in a tank to the atmosphere by a method wherein during the stop of an engine and the feed of oil, vaporizing fuel is fed to a canister through a pressure control valve and a check valve and a tank internal pressure is reduced and during operation of the engine, a solenoid valve is opened and the tank internal pressure is reduced. CONSTITUTION: When, during the stop of an internal combustion engine 2 and the feed of oil, a tank internal pressure exceeds a set value for a pressure control valve 36, a pressure control valve 36 is released against the force of a spring. Through the check valve function of the pressure control valve 36, vaporizing fuel in a fuel tank 16 is guided to a canister 30 through first and second passages 58 and 60 having a large passage diameter and collected, and the tank pressure is reduced to a value lower than a set pressure. Meanwhile, during operation of the engine 2, a second solenoid 68 is released and the vaporizing fuel is fed to the canister 30 through a third communication passage 62 and a bypass passage 66, and the tank internal pressure is reduced to a value lower than a set pressure set by a pressure sensor 54.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel vapor control system for an internal combustion engine, and more particularly to a third communication passage having a passage sectional area smaller than that of a passage provided with a pressure control valve.
A check valve and a new solenoid valve are arranged in parallel in the middle of the communication passage to open the pressure control valve during refueling and open the new solenoid valve during operation of the internal combustion engine to set the tank internal pressure to a predetermined value. The present invention relates to an evaporative fuel control device for an internal combustion engine that sets the level.

[0002]

2. Description of the Related Art Evaporative fuel that leaks into the atmosphere from a fuel tank, a float chamber of a vaporizer, etc., contains a large amount of hydrocarbons (HC) and is one of the causes of air pollution, and also causes fuel loss. Because of the connection, various techniques for preventing this are known. As a typical example, the canister containing an adsorbent such as activated carbon once adsorbs and holds the evaporated fuel in the fuel tank, and the evaporated fuel adsorbed and held in this canister is separated (purge) during operation of the internal combustion engine.
There is an evaporated fuel control device that supplies the internal combustion engine with the fuel.

As an evaporative fuel control system for the internal combustion engine, there is one disclosed in Japanese Patent Laid-Open No. 6-17712. The engine evaporated fuel control device disclosed in this publication forms a passage by a first passage that connects a fuel tank and a canister and a second passage that connects a canister and an intake passage, and a pressure is provided in the middle of the first passage. A control valve is provided, a first solenoid valve is provided in the middle of the second passage, a communication passage for connecting the intake passage and the pressure control valve is provided, and a second solenoid valve is provided in the middle of the communication passage to reduce the amount of fuel in the fuel tank. A fuel level gauge for detection is provided to control the intake valve negative pressure by the second solenoid valve to open the pressure control valve when the engine is operating, and the fuel is supplied when the fuel in the fuel tank exceeds a predetermined amount. When the engine is in operation, a control unit is provided to operate the second solenoid valve according to the detection signal from the level gauge to control the pressure control valve to act on the atmosphere. The second solenoid valve causes the negative pressure in the intake pipe to act on the pressure control valve to control the pressure control valve to open so that the tank internal pressure becomes substantially equal to the atmospheric pressure, and the fuel in the fuel tank has a predetermined amount. When the above occurs, the second solenoid valve is operated by the detection signal from the fuel level gauge, the pressure control valve is controlled to act on the atmosphere, the fuel tank and the canister are shut off, and fuel is supplied during refueling. To prevent overfilling.

Further, there is one disclosed in Japanese Patent Laid-Open No. 6-17713. The engine evaporated fuel control device disclosed in this publication is provided with a ventilation passage communicating one end side with an intake passage of the engine, and the other end side of the ventilation passage is formed into a first branch ventilation passage and a second branch ventilation passage. The first branch air passage is provided by branching to communicate with the fuel tank, a canister for adsorbing and holding evaporated fuel in the air passage, and an on-off valve in the air passage between the canister and the intake passage. A check valve that is opened when the pressure in the fuel tank becomes equal to or higher than the set pressure is provided in the middle of the, and a control valve that is opened during the operation of the engine is provided in the middle of the second branch ventilation path, and the first branch ventilation is also provided. A float valve that closes when the fuel is full is provided at the opening in the fuel tank of the passage, and during operation of the engine, the control valve is opened and communicates with the second branch air passage, so that the pressure in the fuel tank is reduced. About atmospheric pressure It is possible to, when the oil supply to the fuel tank, since it is immediately after the engine is stopped, the pressure in the fuel tank is substantially become atmospheric pressure. In addition, when the fuel in the fuel tank becomes full due to refueling, the float valve closes, the fuel tank becomes full with the upper space left, refueling is blocked, and the pressure in the fuel tank becomes a check valve. Is controlled by the set pressure. Further, since the pressure in the fuel tank is substantially atmospheric pressure, fuel can be supplied even when the engine is operating.

[0005]

By the way, in the conventional evaporated fuel control apparatus for an internal combustion engine, a canister for adsorbing and holding the evaporated fuel is provided in the middle of a passage connecting the intake passage of the internal combustion engine and the fuel tank. Evaporative fuel (HC) generated in the tank is adsorbed and held by the canister.

When fuel is supplied to the fuel tank, the tank internal pressure, which is the pressure inside the fuel tank, rises.

As a result, the vaporized fuel generated in the fuel tank is released to the atmosphere through the breather pipe connecting the fuel tank and the fuel hose, and the vaporized fuel may cause air pollution. However, there is an inconvenience that it is disadvantageous in practical use.

Further, in the evaporative regulation which is planned to be adopted from the US 95MY (model year), the tank internal pressure during engine operation is at a predetermined level, for example, 10 inches mm.
It is regulated below Ag, and development of an engine fuel vapor control device that can cope with this evaporative regulation is earnestly desired.

[0009]

Therefore, in order to eliminate the above-mentioned inconvenience, the present invention adsorbs and holds evaporative fuel generated in the fuel tank in the middle of a passage communicating the inside of the fuel tank with the intake passage of the internal combustion engine. In addition, a canister is provided for separating the absorbed and retained evaporated fuel and supplying it to the intake passage, and a purge solenoid valve is provided in the middle of the passage between the canister and the intake passage, and in the middle of the passage between the fuel tank and the canister. In a fuel vapor control apparatus for an internal combustion engine, which is provided with a pressure control valve having a check valve function, and which is provided with control means for controlling opening / closing of the solenoid valve, a fuel level gauge for detecting a fuel level in the fuel tank is provided, and a fuel tank is provided. A pressure sensor for detecting the internal pressure of the tank is installed to connect the fuel tank with the canister. The first passage and the second passage that connects the canister and the intake passage to each other to form the passage, and to form a large passage cross-sectional area of the first passage and to connect the first passage to the fuel tank and the pressure control valve. Is formed by a first communication passage communicating with the canister, and a second communication passage communicating with the pressure control valve and the canister. The fuel tank is communicated with the second communication passage and the cross-sectional area of the first passage is larger than that of the first passage. A third communication passage having a smaller passage cross-sectional area is provided, a check valve is provided in the middle of the third communication passage, bypasses the check valve, and has a passage cross-sectional area smaller than the passage cross-sectional area of the first passage. A passage is provided and at the middle of the bypass passage, the tank internal pressure is set at a predetermined level during operation by the control means for inputting output signals from at least a fuel level gauge and a pressure sensor. Characterized in that a new solenoid valve which is opened and closed controlled to the Le.

[0010]

With the invention as described above, when the internal combustion engine is stopped, refueling, or when refueling is completed, the pressure control valve having a check valve function and the check valve feed the evaporated fuel to the canister to lower the tank internal pressure. Then, during operation of the internal combustion engine, the solenoid valve newly provided is opened by the control means, and the evaporated fuel is supplied to the canister to reduce the tank internal pressure.

[0011]

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

1 to 6 show an embodiment of the present invention. 2, 2 is an internal combustion engine, 4 is an air cleaner, 6 is a throttle valve, 8 is a surge tank, 10 is an intake passage, 12 is a combustion chamber, 14 is an exhaust passage, and 16 is a fuel tank. The internal combustion engine 2 is provided with a fuel injection valve 18 in the intake passage 10 in the direction of the combustion chamber 12.
The fuel injection valve 18 is connected to the fuel tank 16 through the fuel passage 20.
Is communicated to.

The fuel passage 20 includes a fuel supply passage 22 for supplying fuel from the fuel tank 16 to the fuel injection valve 18,
The fuel return passage 24 returns a predetermined amount of fuel or more into the fuel tank 16.

The fuel in the fuel tank 16 is supplied by the fuel pump 26.
Is sent to the fuel injection valve 18 via the fuel supply passage 22, and is supplied to the combustion chamber 12 together with air for combustion. The exhaust gas generated by the combustion is exhausted through the exhaust passage 14.

An intake passage 10 of the internal combustion engine 2, for example, a passage 28 that connects the surge tank 8 and the fuel tank 16 on the downstream side of the throttle valve 6 is provided, and a canister 30 that adsorbs and holds evaporated fuel is provided in the passage 28. .

The passage 28 is formed by a first passage 32 that connects the fuel tank 16 and the canister 30 and a second passage 34 that connects the canister 30 and the intake passage 10.

Further, a pressure control valve (TPCV) 36 is provided in the middle of the first passage 32, and the pressure control valve 36 causes the tank internal pressure which is the pressure in the fuel tank 16 and the canister 3 to be controlled.
The pressure in 0 is set to a predetermined pressure to suppress the amount of evaporated fuel (HC) generated in the fuel tank 16.

A two-way type first solenoid valve 38 for purging is provided in the middle of the second passage 34, and a fuel level gauge 42 for detecting the amount of fuel is provided in the fuel tank 16. The fuel level gauge 42 corresponds to the fuel tank 16
To detect the fuel level inside.

A control means 44 is provided for controlling the first solenoid valve 38 for purging and the second solenoid valve 68 described later when the internal combustion engine 2 is in operation.

The pressure control valve 36 is arranged so that the diaphragm 48 defining the pressure chamber 46 is pressed by the urging force of the spring 50 to close the pressure control valve 36. Then, the biasing force of the spring 50 is adjusted so as to open the tank when the tank internal pressure becomes equal to or higher than the TPCV set pressure for the pressure control valve 36, which is a preset set value, and a check valve function is added to the pressure control valve 36. Set up.

Further, the control means 44 has a fuel injection valve 18, a fuel pump 26, and a first solenoid valve 38.
And the fuel level gauge 42 are connected to each other.

Reference numeral 52 is a fuel hose through which fuel passes when supplying fuel to the fuel tank 16, and 54 is connected to the fuel tank 16 via a pressure passage 56 to detect the tank internal pressure of the fuel tank 16. It is a pressure sensor.

The passage cross-sectional area of the first passage 32 is large, that is, it is formed large when compared with the passage cross-sectional area of the third communication passage 62 described later, and the first passage 32 is formed.
Is formed by a first communication passage 58 that connects the fuel tank 16 and the pressure control valve 36, and a second communication passage 60 that connects the pressure control valve 36 and the canister 30.

Further, there is provided a third communication passage 62 which connects the fuel tank 16 and the second communication passage 60 and has a passage sectional area smaller than the passage sectional area of the first passage 32.
A check valve 64 is provided in the middle of the third communication passage 62.

Then, the positive pressure side valve setting pressure of the check valve 64 is set to be larger than the TPCV setting pressure for the pressure control valve 36.

Further, a bypass passage 66 bypassing the check valve 64 and having a passage sectional area smaller than the passage sectional area of the first passage 32 is provided, and at least a fuel level gauge 42 and a fuel level gauge 42 are provided in the bypass passage 66. A second solenoid valve 68, which is a new solenoid valve whose opening / closing is controlled so that the tank internal pressure is set to a predetermined set level during operation by the control means 44 which receives the output signal from the pressure sensor 54, is provided.

More specifically, in order to recover a large amount of fuel vapor generated during refueling, the first and second passages of the first passage 32 are collected.
The cross-sectional area of the communication passages 58 and 60 is set to the third communication passage 62.
And the bypass passage 66 is formed to have a larger cross-sectional area. That is, the passage diameters of the first and second communication passages 58 and 60 are about 15 ㎓, the third communication passage 62 and the bypass passage 66.
The diameter of the passage is set to about 4-6〓, and the first and second connecting passages 5
The passage diameters of 8 and 60 are about several times the passage diameters of the third communication passage 62 and the bypass passage 66.

A second solenoid valve 68, which is controlled to be opened / closed by the control means 44, is arranged near the fuel tank 16, for example.

As shown in FIG. 6 (c), the control means 44 closes the second solenoid valve 68 when the engine is stopped, that is, when the internal combustion engine 2 is stopped, refueling is completed, and when refueling is completed. During operation of the engine 2, the duty is controlled so as to open the second solenoid valve 68.

The pressure control valve 36 is shown in FIG. 6 (b).
As shown in, when the internal combustion engine 2 is stopped and the internal capacity of the fuel tank 16 is not in the full tank state, the opening / closing operation is alternately performed according to the tank internal pressure, and the open state is set at the time of refueling, and the refueling ends It will be closed when the tank is full.

Further, the check valve 64 is shown in FIG.
As shown in (a) and (d), when the tank internal pressure becomes equal to or higher than the check valve set pressure, it is turned on, that is, opened, and when the tank internal pressure falls below the check valve set pressure, O
FF, that is, it closes.

Reference numeral 70 is an air cut valve that communicates with the canister 30 and is controlled to be opened / closed by the control means 44, 72 is a fuel filler port of the fuel hose 52 of the fuel tank 16, and 74 is a fuel filler port 72. Is a fuel refueling nozzle, and 78 is a float valve for the passage 28 arranged in the fuel tank 16.

Next, the operation will be described.

As shown in FIG. 4, when the internal combustion engine 2 is stopped and the amount of fuel in the fuel tank 16 is not full, the fuel level gauge 42 does not turn on.

Then, when the internal combustion engine 2 is stopped, the T for the pressure control valve 36, which is a preset value of the tank internal pressure, is set.
When the pressure exceeds the PCV set pressure, as shown in FIG. 6A, the pressure control valve 36 is opened against the biasing force of the spring 50, and the fuel tank 16 is opened by the check valve function of the pressure control valve 36. The evaporated fuel in the canister 3 passes through the first and second communication passages 58 and 60 having large passage cross-sectional areas.
It is adsorbed and held at 0, and the tank internal pressure is reduced to less than the TPCV set pressure. At this time, when the tank internal pressure rises above the check valve set pressure, the check valve 64 is also opened.

Further, when the internal combustion engine 2 is stopped and refueling, as shown in FIGS. 1 and 6 (b), the tank internal pressure rises to become equal to or higher than the TPCV set pressure for the pressure control valve 36, and the pressure control valve 36 is turned on. The pressure control valve 36 is opened by the check valve function, and the evaporated fuel is supplied to the canister 30 through the first and second communication passages 58 and 60 having large passage cross-sectional areas.

Then, when refueling progresses and a so-called full tank state in which the internal capacity of the fuel tank 16 is sufficiently filled, that is, when refueling ends, a detection signal from the fuel level gauge 42 is input to the control means 44. To be done. Further, when the tank is full, the float valve 78 is pushed up and the first passage 32
Shut off. At this time, if the tank internal pressure has risen to the check valve set pressure or higher, as shown in FIG.
As shown in (d), the check valve 64 is opened, and the evaporated fuel is sent to the canister 30 via the third communication passage 62.

Furthermore, during operation of the internal combustion engine 2 during idling, the second solenoid valve 68 is opened by the duty control of the control means 44, as shown in FIGS. 5 and 6 (a), (c). The evaporated fuel is sent to the canister 30 via the third communication passage 62 and the bypass passage 66, and the tank internal pressure is reduced to a pressure less than the pressure set by the pressure sensor 54.

As a result, the fuel level in the fuel tank 16 can be reliably grasped by the fuel level gauge 42.

Further, by providing the pressure sensor 54, the tank internal pressure of the fuel tank 16 can be accurately detected,
This can contribute to the improvement of control reliability.

Further, the first and second communication passages 58, 60
The passage cross-sectional area of the first passage 32 consisting of
Since it is formed larger than the passage cross-sectional area of 2, the large amount of evaporated fuel generated in the fuel tank 16 at the time of refueling can be surely adsorbed and held in the canister 30 without being discharged to the atmosphere. It is possible to prevent air pollution.

Furthermore, by disposing the second solenoid valve 68, which is controlled to be opened and closed by the control means 44, in the vicinity of the fuel tank 16, it is not necessary to use a valve mechanism operated by the intake pipe pressure. The position of the second solenoid valve 68, the pressure control valve 36, the check valve 64, and the like can be moved from the engine room to the vicinity of the fuel tank 16 arranged at the rear of the vehicle, and the system can be made compact. It is practically advantageous.

Further, while the internal combustion engine 2 is operating, the second solenoid valve 68 can be controlled to be opened / closed by the control means 44, so that the tank internal pressure can be set to a predetermined set level.

Furthermore, by reliably controlling the internal pressure of the fuel tank 16 to a predetermined level, it is
It can sufficiently cope with the evaporative regulations that will be adopted from 5MY (model year).

[0045]

As described in detail above, according to the present invention, the evaporated fuel generated in the fuel tank is adsorbed and held in the middle of the passage communicating the inside of the fuel tank with the intake passage of the internal combustion engine, and the evaporated fuel is adsorbed and held. A canister for releasing the fuel to the intake passage, a purge solenoid valve in the passage between the canister and the intake passage, and a pressure control valve having a check valve function in the passage between the fuel tank and the canister. A control means for controlling the opening and closing of the solenoid valve is provided, and a fuel level gauge for detecting the fuel level in the fuel tank is provided.
A pressure sensor that detects the tank internal pressure in the fuel tank is provided, and a passage is formed by the first passage that connects the fuel tank and the canister, and the second passage that connects the canister and the intake passage. While forming a large area, the first passage is formed by a first communication passage that connects the fuel tank and the pressure control valve, and a second communication passage that connects the pressure control valve and the canister. A third communication passage communicating with the second communication passage and having a passage cross-sectional area smaller than the passage cross-sectional area of the first passage is provided, a check valve is provided in the middle of the third communication passage, the check valve is bypassed, and A bypass passage having a passage cross-sectional area smaller than the passage cross-sectional area of the passage is provided, and at least an output signal from the fuel level gauge and the pressure sensor is input in the middle of the bypass passage. Since a new solenoid valve that is controlled to open and close so as to bring the tank internal pressure to a predetermined set level by the means is provided by the means, a large passage cross-sectional area of the first passage including the first and second communication passages is formed. As a result, a large amount of evaporated fuel generated in the fuel tank during refueling can be reliably adsorbed and held in the canister without being discharged to the atmosphere, and atmospheric pollution due to evaporated fuel can be prevented. Further, if a new solenoid valve whose opening and closing is controlled by the control means is arranged in the vicinity of the fuel tank, it is not necessary to use a valve mechanism that is operated by the intake pipe pressure, and the inside of the engine room can be moved to the rear part of the vehicle. The arrangement position can be moved to the vicinity of the arranged fuel tank, and the system can be made compact, which is practically advantageous. Further, while the internal combustion engine is in operation, a new solenoid valve can be controlled to be opened / closed by the control means, so that the tank internal pressure can be set to a predetermined set level.

[Brief description of drawings]

FIG. 1 is a schematic enlarged view of an operating state of a pressure control valve and a second solenoid valve during refueling showing an embodiment of the present invention.

FIG. 2 is a schematic enlarged view showing operating states of a pressure control valve and a second solenoid valve at the end of refueling.

FIG. 3 is a schematic configuration diagram of an evaporated fuel control device for an internal combustion engine.

FIG. 4 is a schematic enlarged view showing operating states of a pressure control valve and a second solenoid valve when the internal combustion engine is stopped.

FIG. 5 is a schematic enlarged view showing operating states of the pressure control valve and the second solenoid valve during operation of the internal combustion engine.

6A and 6B are time charts corresponding to respective operations of an evaporated fuel control device for an internal combustion engine, FIG. 6A is a time chart showing a tank internal pressure, and FIG. 6B is a time chart showing an opening / closing state of a pressure control valve (TRCV). , (C) is a time chart showing the open / closed state of the second solenoid valve, (d) is a time chart showing the ON / OFF operation state of the check valve,
(E) is a time chart showing the rising (closed) and falling (open) states of the float in the fuel tank.

[Explanation of symbols]

 2 Internal Combustion Engine 6 Throttle Valve 10 Intake Passage 14 Exhaust Passage 16 Fuel Tank 18 Fuel Injection Valve 20 Fuel Passage 28 Passage 30 Canister 32 First Passage 34 Second Passage 36 Pressure Control Valve (TPCV) 38 First Solenoid Valve for Purging 44 Control Means 54 Pressure Sensor 58 First Communication Passage 60 Second Communication Passage 62 Third Communication Passage 64 Check Valve 66 Bypass Passage 68 Second Solenoid Valve 70 Air Cut Valve 78 Float Valve

Claims (1)

[Claims] 1. A canister that adsorbs and holds the vaporized fuel generated in the fuel tank in the middle of a passage that connects the interior of the fuel tank and an intake passage of the internal combustion engine and releases the adsorbed and retained vaporized fuel to supply it to the intake passage. A purge solenoid valve is provided in the passage between the canister and the intake passage, and a pressure control valve having a check valve function is provided in the passage between the fuel tank and the canister to control the opening / closing of the solenoid valve. In an evaporative fuel control device for an internal combustion engine provided with a control means,
A fuel level gauge for detecting a fuel level in the fuel tank and a pressure sensor for detecting a tank internal pressure in the fuel tank are provided, and a first passage connecting the fuel tank and the canister, a canister and an intake passage are connected. And a second passage for forming the passage, forming a large passage cross-sectional area of the first passage and connecting the first passage to the fuel tank and the pressure control valve, and the pressure control valve. And a canister, and a second communication passage that connects the fuel tank and the canister, and a third communication passage that connects the fuel tank and the second communication passage and has a passage cross-sectional area smaller than the passage cross-sectional area of the first passage. A bypass valve is provided in the middle of the third communication passage, bypasses the check valve, and has a passage cross-sectional area smaller than the passage cross-sectional area of the first passage. A new solenoid valve is provided in the middle of the bypass passage, the opening / closing of which is controlled to bring the tank internal pressure to a predetermined set level during operation by the control means for inputting output signals from at least the fuel level gauge and the pressure sensor. An evaporated fuel control device for an internal combustion engine, comprising: