JPH08232779A - Vaporizing fuel control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To reliably prevent pollution of the atmosphere due to vaporizing fuel by a method wherein during the feed of oil, a canister and a fuel tank are intercommunicated through opening/closing of a control valve and discharge vaporizing fuel generated in the fuel tank to the atmosphere is blocked. CONSTITUTION: During the stop of an internal combustion engine, a pressure control valve located in a first passage 32 to intercommunicate a fuel tank 16 and a canister and drive by an engine intake air negative pressure serving as a drive source is closed, and a passage between the fuel tank 16 and the canister is cutoff. When, with this state, a tank internal pressure is increased to a value higher than a set value, a pressure control valve is opened against the force of a spring and the tank internal pressure is reduced to a value lower than the set value. Meanwhile, since during the feed of oil, in a control valve 62, an atmospheric pressure P is exerted on first and second chambers 66 and 68, an on-off valve 78 is opened through the force of a spring 76, a tank internal pressure P4 increased through the feed of oil is exerted on a third chamber 70 and vaporizing fuel is fed to the canister.

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 for an internal combustion engine, and more particularly, a control valve having three chambers is formed so that a canister and a fuel tank are communicated with each other at the time of refueling to release the evaporative fuel to the atmosphere. The present invention relates to an evaporative fuel control device for an internal combustion engine that prevents the air pollution by evaporative fuel.

[0002]

2. Description of the Related Art In vehicles, evaporated 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. In addition, various techniques for preventing this are known because they also lead to fuel loss. As a typical example, the canister containing an adsorbent such as activated carbon once adsorbs and holds the vaporized fuel in the fuel tank, and the vaporized fuel adsorbed and held in the canister is released (purged) during operation of the internal combustion engine. There is a fuel vapor control device that supplies the engine.

As an evaporative fuel control system for the internal combustion engine, there is one disclosed in Japanese Patent Application Laid-Open No. 60-199727. The vehicle fuel tank disclosed in this publication has an opening / closing control valve that is connected to an opening / closing lid that covers a cap and opens when the opening / closing lid is opened in an evaporated fuel passage that connects the inside of the fuel tank and the canister. The fuel vapor is prevented from flowing out of the fuel injection port into the outside air when the fuel is injected into the fuel tank.

[0004]

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. A pressure control valve is provided in the middle of the first passage that connects the tank and the canister, and the pressure in the fuel tank and the pressure in the canister are set to a predetermined pressure by this pressure control valve, and the evaporated fuel (HC) in the fuel tank is set. There is one that suppresses the generation amount of.

During operation of the internal combustion engine, the control means controls the second solenoid valve disposed in the middle of the pressure control passage, and the second solenoid valve causes the pressure control valve to act on the intake pipe pressure. Is open.

Further, when the amount of fuel in the fuel tank exceeds a predetermined amount at the time of refueling, the second solenoid valve is operated by the detection signal from the fuel level gauge to act the atmosphere on the pressure control valve.

The pressure control valve has a check valve function of reducing the pressure in the fuel tank to less than a set value.

Therefore, when evaporated fuel is generated in the fuel tank at the time of stopping and refueling, and the tank internal pressure rises above a set value, the tank internal pressure resists the urging force of the spring to open the pressure control valve, and the canister is opened. The evaporated fuel is adsorbed and held on the.

However, not all evaporative fuel generated by the tank internal pressure is adsorbed and held in the canister, and it is not necessary to release the fuel by pressure and the fuel refueling port communicating with the outside air, that is, from a location where it easily flows. Since the evaporated fuel is released to the outside air, the evaporated fuel may cause air pollution, which is disadvantageous in practical use.

[0010]

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, a purge first solenoid valve is provided in the middle of the passage between the canister and the intake passage, and a passage between the fuel tank and the canister is provided. A control for providing a pressure control valve on the way, providing a pressure control passage connecting the pressure control valve and the intake passage, and providing a second solenoid valve on the way of the pressure control passage to control opening / closing of the first and second solenoid valves. In the evaporative fuel control device for an internal combustion engine provided with means, a control passage for connecting the canister and the fuel tank is newly provided. , A control valve is provided in the middle of the control passage, and when the control valve is divided into two chambers by a partition wall, one chamber is partitioned by a diaphragm to form first and second chambers and the other chamber is divided into two chambers. 3 chambers are formed, and the first chamber is first on the fuel tank side.
The second chamber is provided in communication with the intake system of the internal combustion engine by the second communication passage, the third chamber is provided in the middle of the control passage, and the pressure in the first and second chambers is provided. An opening / closing valve is provided in the third chamber, which is connected to the diaphragm that operates according to fluctuations and is urged in an opening direction by a spring to communicate the canister and the fuel tank during refueling.

[0011]

By the invention as described above, during refueling,
The canister and the fuel tank are communicated with each other by the opening / closing valve of the control valve to prevent the evaporative fuel generated in the fuel tank from being released into the atmosphere and prevent the air pollution due to the evaporative fuel.

[0012]

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

1 to 7 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 36 is provided in the middle of the first passage 32, and the fuel tank 16 is
The internal pressure and the internal pressure of the canister 30 are set to predetermined pressures 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 (see FIG. 5), and a pressure control passage 40 for connecting the intake passage 10 and the pressure control valve 36 is provided. A 3-way second solenoid valve 42 is provided in the middle of the pressure control passage 40 (see FIG. 7).
), A fuel level gauge 44 for detecting the amount of fuel is provided in the fuel tank 16.

During operation of the internal combustion engine 2, the second solenoid valve 42 controls the intake pipe pressure to open the pressure control valve 36, and the fuel tank 1 is controlled.
When the amount of fuel in 6 exceeds a predetermined amount, the detection signal from the fuel level gauge 44 causes the second solenoid valve 4
A control means 46 is provided for controlling the pressure control valve 36 so that the pressure control valve 36 is operated by the atmosphere.

Further, the pressure control passage 40 is arranged so as to be opened at a portion upstream of the opening portion of the second passage 34 to the intake passage 10, and as shown in FIG. It is connected to the pressure chamber 48.

The pressure control valve 36 includes a diaphragm 50.
Is pressed by the urging force of the spring 52, and the pressure control valve 3
Arrange 6 to be closed. Then, the urging force of the spring 52 is adjusted so as to perform the opening operation when the tank internal pressure becomes equal to or higher than a preset value, and the pressure control valve 36 is provided with a check valve function.

When the internal combustion engine 2 is in operation, the control means 46 causes the intake pipe pressure to act on the pressure chamber 48 of the pressure control valve 36 by the second solenoid valve 42, and resists the biasing force of the spring 52 to prevent the pressure control valve 36. Control to open.

The control means 46 controls the fuel level gauge when the amount of fuel in the fuel tank 16 is equal to or more than a predetermined amount by refueling, that is, when the fuel tank 16 is fully filled with the internal capacity. The second solenoid valve 42 is operated by the detection signal from 44 so that the pressure control valve 36 is controlled to act on the atmosphere.

Further, the control means 46 has a fuel injection valve 18, a fuel pump 26, and a first solenoid valve 38.
, The second solenoid valve 42, and the fuel level gauge 4
4 and 4 are connected to each other.

Reference numeral 54 is a fuel hose through which the fuel passes when the fuel is supplied to the fuel tank 16, and 56 is a pressure passage 58 between the fuel tank 16 and the pressure control valve 36 of the first passage 32. It is a pressure sensor that communicates.

Then, a control passage 60 for connecting the canister 30 and the fuel tank 16 is newly provided,
In the middle of this control passage 60, the control valve 6
2 is provided.

The control valve 62 is formed as follows. That is, the control valve 62 has a partition wall 62W.
When divided into two chambers, one of the chambers is diaphragm 64
To form the first and second chambers 66 and 68, and the other chamber to form the third chamber 70.
6 is connected to the fuel tank 16 side by a first communication passage 72, and the second chamber 68 is formed by a second communication passage 74 in the intake passage 10 downstream of the throttle valve 6 which is the intake system of the internal combustion engine 2. The third chamber 70 is provided in communication with the control passage 60.

The on-off valve 78 provided in the third chamber 70 communicates with the diaphragm 64 which operates in response to the pressure fluctuations in the first and second chambers 66 and 68, and the second chamber 68. The canister 30 and the fuel tank 16 are communicated with each other at the time of refueling by being urged in the opening direction by a spring 76 that is contracted inside.

At this time, the control valve 62
1 is directly connected to the fuel tank 16 through a connecting pipe 80 as shown in FIG.

When connecting the first communication passage 72 to the fuel tank 16 side, the fuel hose 5 of the fuel tank 16 is connected.
4 is provided so as to communicate with the vicinity of the fuel filler port 82.

The on-off valve 78 comprises a connecting pipe 80 and a valve body 84 which opens and closes the upper end portion of the connecting pipe 80 and connects to the diaphragm 64.

Reference numeral 86 is an air cut valve which communicates with the canister 30 and whose opening and closing is controlled by the control means 46, 88 is a cap for opening and closing the fuel filling port 82 of the fuel hose 54 of the fuel tank 16, and 90 is fuel. A fueling nozzle, 92 is a first float valve for the passage 28,
Reference numeral 94 is a second float valve for the control passage 60.

Next, the operation will be described.

As shown in FIG. 3, 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 44 does not turn on and the second solenoid valve 42 does not operate. The intake pipe pressure acting on the pressure chamber 48 of the pressure control valve 36 is not generated, and the fuel tank 16 and the canister 30 are shut off from each other.

When the internal pressure of the tank exceeds a preset value when the internal combustion engine 2 is stopped, the pressure control valve 36 is opened against the biasing force of the spring 52, and the pressure control valve 36 is opened. The check valve function of 36 reduces the tank internal pressure below the set value.

At this time, the control valve 62
As shown in FIG. 3, the tank internal pressure P ₁ acts on the first chamber 66, and the atmospheric pressure P ₂ from the intake passage 10 acts on the second chamber 68. Generally, P ₁ > P _Since it is ₂ , the on-off valve 78 is closed against the biasing force of the spring 76. When P ₁ = P ₂ , the diaphragm 64 is pushed up by the urging force of the spring 76, and the on-off valve 78 is opened.

During operation of the internal combustion engine 2 during idling, the intake pipe pressure acts on the pressure chamber 48 of the pressure control valve 36 via the second solenoid valve 42, as shown in FIG. The pressure control valve 36 is opened against the urging force of the fuel tank 16 to establish communication between the fuel tank 16 and the canister 30.

At this time, as shown in FIG. 4, the control valve 62 has a tank internal pressure P _{1 in} the first chamber 66.
And the intake pipe pressure P ₃ from the intake passage 10 acts on the second chamber 68, and the canister 3 enters the third chamber 70.
Since the atmospheric pressure P ₂ from 0 acts and P ₁ > P ₂ > P ₃ , the opening / closing valve 78 is closed against the biasing force of the spring 76.

Further, when the internal combustion engine 2 is stopped and refueling, as shown in FIG. 1, the atmospheric pressure P ₂ acts on the first and second chambers 66 and 68, and the opening / closing valve 78 is opened by the urging force of the spring 76. Then, the tank internal pressure P ₄ at the time of refueling, which is increased by refueling, acts on the third chamber 70, and the evaporated fuel is fed to the canister 30.

When refueling progresses and a so-called full state in which the internal capacity of the fuel tank 16 is sufficiently filled, a detection signal from the fuel level gauge 44 is sent to the control means 4.
6 is input. When the tank is full, the first float valve 92 is pushed up to shut off the first passage 32, and the second float valve 94 is pushed up to shut off the control passage 60, so that the fuel tank 16 and the canister 30 are separated from each other. It is shut off.

As a result, the on-off valve 78 is opened by the urging force of the spring 76 when the internal combustion engine 2 is stopped and fuel is supplied, and the fuel tank 1 is opened by the control valve 62.
The evaporated fuel generated in 6 can be adsorbed and held in the canister 30 without being discharged to the atmosphere from the fuel filler port 82, and the atmospheric pollution due to the evaporated fuel can be reliably prevented.

Further, since the evaporated fuel generated in the fuel tank 16 is not released from the fuel refueling port 82 to the atmosphere when the internal combustion engine 2 is stopped and refueled, it is possible to realize a device that meets various evaporation regulations. It is practically advantageous.

Further, during operation of the internal combustion engine 2 during idling or the like, the opening / closing valve 78 of the control valve 62 is closed against the biasing force of the spring 76, so that fuel vapor from the fuel tank 16 to the canister 30 and There is no fear of liquid leakage.

Furthermore, the control valve 62
Is directly connected to the fuel tank 16 via the connection pipe 80, the control valve 62 can be firmly attached to the fuel tank 16, which is practically advantageous.

Further, when the first communication passage 72 is connected to the fuel tank 16 side, the fuel hose 5 of the fuel tank 16 is connected.
Since it is provided in the vicinity of the fuel filling port 82 of No. 4, the atmospheric pressure can be applied to the first chamber 64 of the control valve 62 when the internal combustion engine 2 is stopped and the fuel is filled, and the on-off valve 78 can be reliably operated. Therefore, the reliability of the operation can be improved.

[0047]

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 that separates and supplies the intake air to the intake passage, a first solenoid valve for purging provided in the passage between the canister and the intake passage, and a pressure control valve in the passage between the fuel tank and the canister. And an intake passage, a pressure control passage is provided, a second solenoid valve is provided in the middle of the pressure control passage, and a control means for controlling opening / closing of the first and second solenoid valves is provided.
A control passage that connects the canister and the fuel tank is newly provided, and a control valve is provided in the middle of the control passage. When the inside of the control valve is divided into two chambers by a partition wall, one of the chambers is partitioned by a diaphragm. Two chambers are formed and a third chamber is formed in the other chamber, the first chamber is provided on the fuel tank side in communication with the first communication passage, and the second chamber is provided in the intake system of the internal combustion engine with the second communication passage. The third chamber is provided in the middle of the control passage, and the third chamber is connected to the diaphragm that operates according to pressure fluctuations in the first and second chambers and is urged in the opening direction by the spring to connect the canister and the fuel tank during refueling. Since the on-off valve that communicates with each other is provided in the third chamber, the on-off valve is opened by the biasing force of the spring when the internal combustion engine is refueled, and the control valve The evaporative fuel generated in the fuel tank can be adsorbed and held in the canister without being released to the atmosphere, and air pollution due to the evaporative fuel can be reliably prevented, and a device that meets various evaporation regulations can be realized. It is practically advantageous. Further, if the control valve is directly connected to the fuel tank, the control valve can be firmly attached to the fuel tank. Further, when the first communication passage is connected to the fuel tank side, if it is provided so as to communicate with the vicinity of the fuel filler port of the fuel hose of the fuel tank, the first valve passage is connected to the first chamber of the control valve when the internal combustion engine is refueled. The atmospheric pressure can be applied, the on-off valve can be reliably opened, and the operation reliability can be improved.

[Brief description of drawings]

FIG. 1 is a schematic enlarged view of a control valve during refueling showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an evaporated fuel control device for an internal combustion engine.

FIG. 3 is a schematic enlarged view of a control valve when the internal combustion engine is stopped.

FIG. 4 is a schematic enlarged view of a control valve when the internal combustion engine is operating.

FIG. 5 is a schematic enlarged view of a 2-way type first solenoid valve for purging.

FIG. 6 is a schematic enlarged view of a pressure control valve.

FIG. 7 is a schematic enlarged view of a 3-way second solenoid valve.

[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 38 Two-way First Solenoid Valve for Purging 40 Pressure control passage 42 3 way type second solenoid valve 44 Fuel level gauge 46 Control means 54 Fuel hose 56 Pressure sensor 60 Control passage 62 Control valve 62W Partition wall 64 Diaphragm 66 First chamber 68 Second chamber 70 Third chamber 72 First Communication passage 74 Second communication passage 76 Spring 78 Open / close valve 80 Connection pipe 82 Fuel filler port 84 Valve body

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 first solenoid valve for purging is provided in the passage between the canister and the intake passage, and a pressure control valve is provided in the passage between the fuel tank and the canister, and the pressure control valve and the intake passage are connected to each other. A pressure control passage for communication is provided, and a second solenoid valve is provided in the middle of the pressure control passage.
In an evaporative fuel control system for an internal combustion engine, which is provided with control means for controlling opening and closing of first and second solenoid valves, a control passage for connecting the canister and the fuel tank is newly provided, and a control valve is provided in the middle of the control passage. When the inside of the control valve is divided into two chambers by a partition wall, one chamber is partitioned by a diaphragm to form first and second chambers, and the other chamber forms a third chamber. Is connected to the fuel tank side by a first communication passage, and the second chamber is connected to the intake system of the internal combustion engine as a second
The third chamber is provided in communication with the communication passage, the third chamber is provided in the middle of the control passage, and the third chamber is connected to the diaphragm that operates in response to pressure fluctuations in the first and second chambers, and is urged in the opening direction by a spring to refuel. An evaporative fuel control system for an internal combustion engine, characterized in that an opening / closing valve for communicating the canister and the fuel tank is provided in the third chamber.