JP2962167B2 - Fuel evaporation prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel evaporation prevention device, and more particularly to a fuel evaporation prevention device capable of preventing the emission of fuel evaporation gas during refueling.

[0002]

2. Description of the Related Art Generally, harmful substances such as carbon monoxide, nitrogen oxides and hydrocarbons are emitted from automobiles. For example, unburned HC gas contained in blow-by gas or exhaust gas is discharged to the atmosphere as hydrocarbons (HC),
Also, raw gasoline (fuel evaporative gas) evaporated in the fuel tank or the like is emitted to the atmosphere as HC. Therefore, vehicles are equipped with devices for suppressing emission of harmful substances, such as exhaust gas purification devices and fuel evaporation prevention devices.

[0003] The fuel evaporation prevention device prevents the evaporation of fuel evaporation gas to the atmosphere, and typically includes a canister having activated carbon for adsorbing HC. The canister is provided with an introduction port communicating with the fuel tank, a discharge port communicating with the intake pipe of the engine, and a vent port opened to the atmosphere. In this type of canister storage type fuel evaporation prevention device, when the engine is stopped, fuel evaporative gas (HC) in a fuel tank is introduced into a canister and adsorbed on activated carbon in the canister. In addition, this system uses the intake negative pressure generated in the intake pipe during the operation of the engine to act on the exhaust port, introduces purge air from the vent port, and separates the HC adsorbed on the activated carbon from the activated carbon by the purge air. Then, the separated HC is discharged to the intake pipe together with the purge air. HC discharged to the intake pipe
The (fuel evaporative gas) is burned in the cylinder of the engine together with the air-fuel mixture, thereby preventing discharge of the fuel evaporative gas to the atmosphere.

[0004]

However, when the engine is stopped, the fuel evaporative gas adsorbed on the canister cannot be burned in the engine. Therefore, if the engine is stopped for a long period of time for parking or the like, especially when the engine is stopped, If the temperature is high or the vehicle is exposed to direct sunlight, the amount of fuel vapor generated in the fuel tank may exceed the capacity limit of the canister. In this case, the fuel evaporative gas is released into the atmosphere to promote air pollution.
When the fuel supply port of the fuel tank is opened for refueling, the fuel evaporative gas in the fuel tank is diffused into the atmosphere.

Accordingly, an object of the present invention is to provide a fuel evaporation prevention device which can prevent unnecessary emission of fuel evaporative gas from a fuel supply port of a fuel tank at the time of refueling.

[0006]

According to the present invention, there is provided a fuel evaporation prevention apparatus comprising: a reservoir communicated with a fuel tank via a reserve passage; and a compressor interposed in the reserve passage for guiding gas in the fuel tank to the reservoir side. A compressor operating means for operating the compressor in response to the command signal, a pressure sensor for detecting the internal pressure of the reservoir, a return passage connecting the reservoir to the engine intake passage, and an on-off valve interposed in the return passage. And valve control means for opening the on-off valve when the reservoir internal pressure exceeds a set pressure based on the detection result of the pressure sensor.

[0007]

When a command signal is transmitted prior to refueling, the compressor is operated by the compressor operating means. By this compressor operation, the gas containing the fuel evaporative gas in the fuel tank is guided to the reservoir side through the reserve passage. For this reason, even if the fuel tank internal pressure decreases and the fuel supply port of the fuel tank is opened, fuel evaporative gas does not blow out from the fuel tank.

When the internal pressure of the reservoir detected by the pressure sensor exceeds the set pressure, the reservoir is interposed in a return passage connecting the reservoir and the engine intake passage under the control of valve control means responsive to the detection result. The on-off valve is opened, whereby the fuel evaporative gas in the reservoir flows into the engine and the internal pressure of the reservoir decreases. As a result, during the next refueling, the pressure in the reservoir is reduced, and the gas in the fuel tank can be smoothly introduced into the reservoir.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fuel evaporation prevention device according to a first embodiment of the present invention will be described. Referring to FIG. 1, a branch end of an intake manifold 2 is connected to each cylinder of the engine 1, and an air cleaner 4 is provided at an outer end of an intake pipe 3 connected to a collecting end of the intake manifold 2. I have. Further, a fuel injection valve (not shown) is provided in the intake manifold 2 near the intake port of each cylinder.

[0010] The fuel tank 10 includes a filler duct 10a.
And a vent pipe 10b, and a filler duct 10a
A filler cap 10c is attached to the filler port, and the filler port side of the duct is surrounded by a filler lid 12 that is opened and closed by a filler lid opening and closing drive unit 11. When the filler cap 10c is removed and the filler lid 12 is opened, a refueling gun (not shown) for refueling the fuel tank 10 can be inserted into the filler duct 10a. Reference numeral 13
Indicates a refueling end detection switch that responds to attachment / detachment of the filler cap 10c to / from the filler port.

A fuel pump 14 is provided in the fuel tank 10, and a fuel filter 15 is provided on the suction side of the pump 14. A part of the fuel discharged from the fuel pump 14 is supplied to each fuel injection valve via a fuel pipe 16 and a delivery pipe 17, and the remainder of the fuel is supplied to the fuel regulator 1 connected to the delivery pipe 17.
The fuel tank 10 is returned to the fuel tank 10 via the return pipe 8 and the return pipe 19.

The fuel evaporation prevention device is attached to the fuel system having the above-described structure to prevent the emission of fuel evaporative gas from the fuel tank 10, and is an electronic control unit (ECU) for controlling the operation of each part of the device. 21. Further, the fuel evaporation prevention device is provided in the upper space 1 of the fuel in the fuel tank 10.
First pipe 3 for communicating 0d with intake manifold 2
1 and a second pipe 32 branched from the pipe 31. The second pipe 32 extends to the reservoir 22 for storing the fuel evaporative gas, and cooperates with the first pipe 31 to form the reservoir 22. Is formed in a reserve passage which communicates with the fuel tank 10.

In the middle of the first pipe 31, a fuel evaporative gas (more generally, a gas containing a fuel evaporative gas from the tank space 10 d (hereinafter, referred to as “gas”) passes through the first pipe 31.
Similarly, a first solenoid on-off valve 41 is provided for selectively allowing or preventing the inflow into the intake manifold 2). In the middle of the second pipe 32, a second solenoid valve 42 for allowing or preventing the flow of the fuel evaporative gas through the pipe 32, a compressor 23 for feeding the fuel evaporative gas to the reservoir 22, A canister 24 for adsorbing the fuel evaporative gas is provided.

Further, one end of a third pipe 33 is connected to the second pipe 32 on the upstream side of the compressor 23, and the other end of the pipe 33 is connected to the intake pipe 3.
Then, a part of the air introduced into the intake pipe 3 via the air cleaner 4 is sent as purge air to the canister 24 through the third pipe 33 as purge air by the compressor 23, whereby the fuel evaporative gas adsorbed on the canister 24 is removed. From the canister 24 (purge). In the middle of the third pipe 33, there is provided a third pipe 33 for allowing or preventing the inflow of purge air through the pipe 33.
An electromagnetic valve 43 is provided.

A fourth pipe 34 extending from the reservoir 22
Is connected to the first pipe 31 on the intake manifold 2 side with respect to the first solenoid valve 41, and discharges the fuel evaporative gas in the reservoir 22 to the intake manifold 2 through the fourth pipe 34 by the intake negative pressure. I have. That is, the fourth
The pipe 34 cooperates with the first pipe 31 to form the reservoir 2.
A return passage connecting the intake manifold 2 and an intake manifold 2 as an engine intake passage is formed. In the middle of the fourth pipe 34, a fourth solenoid valve 44 for permitting or preventing the flow of the fuel evaporative gas into the intake manifold 2 via the pipe 34 is provided. Note that the first to first
The fourth solenoid valves 41 to 44 are, for example, normally open solenoid valves.

The fuel tank 10 has a tank space 1.
A first pressure sensor 51 for detecting a pressure within 0d, that is, a fuel tank internal pressure is provided, and a second pressure sensor 52 for detecting a reservoir internal pressure is provided for the reservoir 22. The electronic control unit 21 includes a central processing unit for executing a program for controlling fuel evaporation to be described later, a memory storing the control program and the like, an input / output circuit (all not shown), and the like. ~ 4th
Solenoid valves 41 to 44, first and second pressure sensors 51 and 52,
It is connected to the compressor 23, the filler lid opening / closing drive unit 11, the refueling switch 53, the lamp drive unit 55, and the like. If necessary, a drive unit (not shown) is provided between the electronic control unit 21 and each of the solenoid valves 41 to 44 and the compressor 23.

The refueling switch 53 is provided, for example, on an instrument panel (not shown) together with a display lamp 54. When a driver turns on the refueling switch 53 prior to refueling, an electronic device which responds to a refueling switch output as a command signal. Under the control of the control unit 21, a fuel evaporation prevention control process at the time of refueling is executed, as described later. When the process is completed, a refueling enable display is performed by the display lamp 54.

As will be apparent from the following description of operation, the electronic control unit 21 functions as compressor operating means and valve control means. Hereinafter, the operation of the fuel evaporation prevention device having the above-described configuration will be described with reference to FIGS. The electronic control unit 21 of the fuel evaporation prevention device is configured such that the ignition key (not shown) is in the ON position, and at least a predetermined period (a time sufficiently longer than the maximum refueling time) has elapsed since the ignition key was turned off. The main routine (FIG. 2) of the fuel evaporation prevention control program is executed at predetermined intervals until the operation is completed.

In the main routine, the electronic control unit 21 determines whether or not the operation of the engine 1 is stopped by determining, for example, whether the ignition key is at an ON position or an OFF position (step S1). S1) If the result of this determination is negative, a subroutine for control during engine operation (FIG. 3) is executed (step S2).

On the other hand, when it is determined in step S1 that the operation of the engine 1 is stopped, the electronic control unit 2
1 determines whether or not the refueling switch 53 has been turned on and a refueling command signal has been sent based on the output from the switch 53 (step S3). A subroutine for control (FIG. 4) is executed (step S4). Step S3
When the electronic control unit 21 determines that the refueling command signal has been transmitted, the electronic control unit 21 executes a subroutine (FIG. 5) for control during refueling (step S5).

More specifically, during the operation of the engine, in the subroutine of FIG. 3, the electronic control unit 21 sends, for example, an L-level control output to the first
1 (step S201), and then the compressor 2
Then, it is determined whether or not the compressor 23 is operating with reference to the control output level to the control output 3 (step S202).
If the determination result is negative, it is further determined whether or not the internal pressure of the reservoir 22 is equal to or higher than a predetermined pressure based on the output from the second pressure sensor 52 (step S20).
3). Usually, the reservoir internal pressure is less than a predetermined pressure,
The result of the determination in step S203 is negative. In this case, the process returns to the main routine of FIG. 2, and if it is determined in step S1 that the operation of the engine 1 has not been stopped,
The process returns to the subroutine of FIG. 3, and the first solenoid valve 41 is maintained in the open state. As a result, the fuel evaporative gas in the fuel tank 10 flows into the intake manifold 2 via the first pipe 31 by the negative pressure of the intake air and burns in the cylinder of the engine 1, whereby the fuel evaporative gas during engine operation is generated. From the fuel tank 10 to the atmosphere is prevented.

Thereafter, when it is determined in step S203 of the subroutine of FIG. 3 that the internal pressure of the reservoir has become equal to or higher than the predetermined pressure during the continuation of the engine operation, the electronic control unit 21 causes the fourth solenoid valve 44 to output, for example, an L level signal. Is sent to open the solenoid valve 44 (step S20).
4) Next, the third solenoid valve 43 is opened in the same manner (step S205), and the compressor 23 is operated (step S206), and the process returns to the main routine. in this case,
When it is determined in step S1 of the main routine that the engine is not in the stopped state and the process returns to the subroutine of FIG. 3, it is determined that the compressor 23 is operating in step S202 of the subroutine, and then, in step S207, the internal pressure of the reservoir is reduced. It is determined that the pressure is equal to or higher than the predetermined pressure. Therefore, the third
The open state of the fourth solenoid valves 43 and 44 is maintained, and the operation of the compressor 23 is continued.

As a result, a part of the air introduced into the intake pipe 3 via the air cleaner 4 is introduced into the third pipe 33, and further, is supplied to the canister 24 by the compressor 23.
Is supplied as purge air. As a result, the fuel evaporative gas adsorbed by the canister 24 is removed.
And is sent into the reservoir 22 together with the purge air, and further sucked into the intake manifold 2 through the fourth pipe 34 together with the fuel evaporative gas in the reservoir 22 by the negative pressure of the intake air generated in the intake manifold 2. Combustion in the engine 1.

As described above, the fuel evaporative gas in the reservoir 22 is sent to the engine 1 side, and the internal pressure of the reservoir decreases. When the reservoir internal pressure becomes lower than the predetermined pressure, the result of the determination in step S207 is negative. In this case, the electronic control unit 21 sends, for example, an H level to the fourth electromagnetic valve 44 to close the electromagnetic valve 44 (Step S).
208), and similarly closes the third solenoid valve 43 (step S2).
09), the compressor 23 is stopped (step S2).
10) Return to the main routine.

At the time of engine operation, as described above, the first
The solenoid valve 41 is opened to allow the fuel evaporative gas in the fuel tank 10 to always flow to the intake manifold 2, and the third and fourth solenoid valves 43 and 44 are opened and closed as necessary, and the compressor 23 is operated. By deactivating, the internal pressure of the reservoir is maintained below the predetermined pressure, thereby making it possible to smoothly feed the fuel evaporative gas from the fuel tank 10 to the reservoir 22 (described later) at the time of the next refueling.

When the engine is stopped, a subroutine of FIG. 4 corresponding to step S4 of the main routine (FIG. 2) is executed. In this subroutine, the electronic control unit 21 sends, for example, an H-level control output to the first electromagnetic valve 41 to close the electromagnetic valve 41 (step S401).
Next, the second to fourth solenoid valves 42 to 44 are sequentially closed (steps S402 to S404). As a result, the fuel tank 10 is closed, and even when the engine is stopped, the evaporation of the fuel evaporative gas from the fuel tank 10 to the atmosphere is prevented.

At the time of refueling, step S in the main routine
5 corresponding to FIG. 5 is executed. In this subroutine, the electronic control unit 21 sends an L level control output to the second electromagnetic valve 42 to
Is opened (step S501), and then the compressor 23
Is activated (step S502). As a result, the fuel evaporation gas in the fuel tank 10 flows from the first pipe 31 to the second
After flowing into the pipe 32, the second solenoid valve 42 in the open state
Through the compressor 23. Further, the fuel evaporative gas is sent into the reservoir 22 by the compressor 23 via the canister 24. Thereby, the fuel tank internal pressure gradually decreases. Meanwhile, the electronic control unit 2
1 repeatedly determines whether or not the fuel tank internal pressure has become equal to or lower than a set pressure, for example, the atmospheric pressure, based on the output indicating the fuel tank internal pressure from the first pressure sensor 51 (step S503).

If it is determined in step S503 that the internal pressure of the fuel tank has become equal to or less than the atmospheric pressure, the electronic control unit 2
The control unit 1 sends, for example, a control output of H level to the lamp driving unit 55, thereby turning on the display lamp 54 via the driving unit 55 (step S504). Next, the electronic control unit 21 closes the second solenoid valve 42 and stops the operation of the compressor 23 (step S5).
05 and S506), a control output of, for example, H level is sent to the filler lid opening / closing drive section 11, thereby opening the filler lid 12 via the drive section 11 (step S507).

As described above, when the internal pressure of the fuel tank becomes equal to or lower than the atmospheric pressure, this is notified to a driver or the like by lighting a lamp, and the filler lid 12 is opened later. Therefore, the refueling worker puts the filler cap 10c on the filler duct 10a.
And remove the fuel filler. At this time, since the fuel tank internal pressure is equal to or lower than the atmospheric pressure, even when the fuel supply port is opened, the fuel evaporative gas does not blow out from the fuel tank 10. Next, the refueling worker inserts the refueling gun into the filler port of the filler duct 10a to start refueling the fuel tank 10.

The electronic control unit 21 repeatedly determines whether or not refueling has been completed based on the output signal from the refueling end detection switch 13 (step S508). After that, refueling is finished and the refueling gun is pulled out from the refueling port,
Further, when the filler cap 10c is attached to the filler port, the switch 13 sends an output signal indicating the completion of the filler operation. When the refueling end signal is input, the electronic control unit 21 closes the filler lid 12 via the filler lid opening / closing drive unit 11 (step S509), and then turns off the display lamp 54 via the lamp drive unit 55. (Step S510). Thereby, the subroutine of FIG. 5 ends, and the process returns to the main routine.

As described above, according to the present embodiment, the emission of the fuel evaporative gas from the fuel tank 10 is prevented both at the time of refueling and at the time other than the refueling (when the engine is stopped and the engine is operating). Hereinafter, a fuel evaporation prevention device according to a second embodiment of the present invention will be described with reference to FIG.

As compared with the apparatus of the first embodiment (FIG. 1),
The present embodiment differs mainly in that the canister 24 shown in FIG. 1 is not provided, and in connection with this difference, elements corresponding to the third pipe 33 and the third solenoid valve 43 shown in FIG. Not equipped. Further, in this embodiment, the fourth pipe 3 shown in FIG.
The point that the third pipe 33a corresponding to No. 4 communicates with the first pipe 31 on the fuel tank 10 side with respect to the first solenoid valve 41, and the point that the display lamp 54 and the lamp driving unit 55 are not provided are the following. Different from the first embodiment. In the following description, the solenoid valve 43a corresponding to the fourth solenoid valve 44 in FIG. 1 is referred to as a third solenoid valve. The other configuration is the same as that of the first embodiment, and the description is omitted.

The operation of the apparatus shown in FIG. 6 will be briefly described below. The electronic control unit 21 of this device executes the same main routine (not shown) for fuel evaporation prevention control as shown in FIG. 2 at a predetermined cycle. And the control unit 2
As in the case of the first embodiment, when it is determined that the engine operation is not stopped, the subroutine 1 executes a subroutine for control during engine operation (FIG. 7), determines that the engine is stopped, and sends a refueling command signal. If it is determined that the engine has not been stopped, a subroutine (not shown) similar to that shown in FIG. 4 is executed for control when the engine is stopped. 8).

When the engine is operating, in the subroutine of FIG. 7, the electronic control unit 21 opens the first solenoid valve 41 (step S201a), and then, based on the output of the second pressure sensor 52, the internal pressure of the reservoir becomes equal to or higher than a predetermined pressure. Is determined (step S202a). If the reservoir internal pressure is lower than the predetermined pressure, the third electromagnetic valve 43a is closed (step S203a), while if the reservoir internal pressure is higher than the predetermined pressure, the third electromagnetic valve 43a is opened (step S204).
a). Therefore, during the operation of the engine, the third solenoid valve 43a is controlled to open and close so that the internal pressure of the reservoir is kept below the predetermined pressure while the first solenoid valve 41 is kept open. This prevents the fuel evaporative gas from dissipating during the operation of the engine.
So that it can be smoothly fed into the building.

When the engine is stopped, the first to third solenoid valves 4
The fuel tank 10, 1, 42 and 43a is kept closed and the fuel tank 10 is kept in a closed state, whereby the emission of the fuel evaporative gas is prevented. At the time of refueling, in the subroutine of FIG. 8, the electronic control unit 21 opens the second solenoid valve 42 and operates the compressor 23 (step S5).
01a), the fuel evaporative gas in the fuel tank 10 is sent into the reservoir 22 by the compressor 23, whereby the fuel tank internal pressure is gradually reduced. When it is determined in step S502a that the fuel tank internal pressure has become equal to or lower than the atmospheric pressure based on the output of the first pressure sensor 51, the electronic control unit 21 closes the second solenoid valve 42 and stops the operation of the compressor 23. Then, the filler lid 12 is opened via the filler lid opening / closing drive unit 11 (step S503a).

Thereafter, refueling is performed as in the case of the first embodiment. When the refueling end is determined in step S504a based on the output of the refueling end detection switch 13,
The electronic control unit 21 opens the third solenoid valve 43a (Step S505a). As a result, the fuel evaporative gas in the reservoir 22 flows into the fuel tank 10 through the third pipe 33a, so that the internal pressure of the reservoir gradually decreases while the internal pressure of the fuel tank gradually increases. Meanwhile, the electronic control unit 2
1 repeatedly determines whether or not the difference between the fuel tank internal pressure and the reservoir internal pressure (differential pressure between the tank and the reservoir) has become equal to or less than a predetermined pressure based on the outputs of the first and second pressure sensors 51 and 52 (step). S506a).

If the differential pressure has become equal to or less than the predetermined pressure, and accordingly the internal pressure of the fuel tank and the internal pressure of the reservoir have been balanced, step S
When the determination is made in 506a, the electromagnetic control unit 21
The solenoid valve 43a is closed. This suppresses the generation of fuel evaporative gas in the fuel tank 10 by pre-pressurizing the inside of the fuel tank 10 and provides a margin for the reservoir internal pressure at the time of refueling. Next, the control unit closes the filler lid 12 (step S508a), and ends the subroutine of FIG.

Referring now to FIG. 9, a description will be given of a fuel evaporation prevention apparatus according to a third embodiment of the present invention. Compared to the device of the second embodiment (FIG. 6), the device of the present embodiment has a third pipe 33b corresponding to the third pipe 33a of FIG. The difference is that it communicates with one pipe 31. The other configuration is the same as that of the second embodiment, and the description is omitted.

Hereinafter, the operation of the apparatus shown in FIG. 9 will be briefly described. The electronic control unit 21 executes the same main routine (not shown) for fuel evaporation prevention control as shown in FIG. 2 at a predetermined cycle. Then, the control unit 21
As in the case of the second embodiment, when it is determined that the engine operation is not stopped, the control for the engine operation is performed.
The same subroutine (not shown) as the subroutine shown in FIG. 7 is executed, and if it is determined that the engine is stopped and the refueling command signal is not transmitted, a subroutine similar to that of FIG. 10) (corresponding to FIG. 8) for control at the time of refueling when it is determined that the engine is stopped and the refueling command signal is transmitted.
Execute the subroutine.

When the engine is running, the electronic control unit 21
After the first solenoid valve 41 is opened, the third solenoid valve 43b is closed if the internal pressure of the reservoir is less than the predetermined pressure, while the third electromagnetic valve 43a is opened if the internal pressure of the reservoir is equal to or higher than the predetermined pressure. The first solenoid valve 4 is used to prevent the evaporative gas from diffusing.
The third solenoid valve 43a is controlled to open and close so that the reservoir internal pressure is kept below a predetermined pressure while maintaining 1 in the open state.

When the engine is stopped, the first to third solenoid valves 4
The fuel tank 10, 1, 42 and 43b is kept closed and the fuel tank 10 is closed, thereby preventing the fuel evaporative gas from diffusing. At the time of refueling, in the subroutine of FIG. 10, the electronic control unit 21 opens the second solenoid valve 42 and operates the compressor 23 (step S50).
1b) When the fuel vapor in the fuel tank 10 is sent into the reservoir 22 by the compressor 23 and it is determined in step S502b that the fuel tank internal pressure has become equal to or less than the atmospheric pressure, the electronic control unit 21 Is closed, the operation of the compressor 23 is stopped, and the filler lid 12 is opened via the filler lid opening / closing drive unit 11 (step S503b).

Thereafter, refueling is performed in the same manner as in the first and second embodiments. Then, the refueling end is determined in step S50.
When the determination is made in 4b, the electronic control unit 21 closes the filler lid 12 (step S505b), and ends the subroutine of FIG. The present invention relates to the above first to third embodiments.
The present invention is not limited to the embodiment and the modified example according to the first embodiment, and can be variously modified.

For example, in each of the above embodiments, the case where the fuel evaporation type apparatus is provided with the fuel evaporation prevention apparatus has been described. However, the apparatus of the present invention can be applied to an engine with a carburetor. In the first to third embodiments, an automatic opening / closing type filler lid is used. However, it is not essential to use this kind of filler lid and to control the opening / closing of the filler lid in the present invention. In the first to third embodiments, the fuel tank 10 is closed when the engine is stopped to prevent the evaporation of the fuel evaporative gas except during refueling. However, this is an essential item in the present invention. Absent. Further, in the first embodiment, the display lamp 54 is provided so as to display the refueling possibility when the pressure in the fuel tank 10 is reduced to a pressure equal to or lower than the set value. However, this is not essential.

Further, in the first to third embodiments, when the filler lid is opened after the fuel tank internal pressure has been reduced to a set pressure, for example, the atmospheric pressure or less, refueling is performed immediately. Later, it may be determined again whether or not the fuel tank internal pressure is equal to or lower than the set pressure. In this case, if the determination result is affirmative, the start of refueling work is permitted, while if the determination result is negative, the second
The pressure in the fuel tank is reduced again by opening the solenoid valve and operating the compressor.

The refueling switch 53, the refueling end detection switch 13 and the like can be variously modified.

[0046]

As described above, the fuel evaporation prevention device according to the present invention has a reservoir that communicates with the fuel tank via the reserve passage, and guides gas in the fuel tank to the reservoir by being interposed in the reserve passage. A compressor, compressor operating means for operating the compressor in response to the command signal, a pressure sensor for detecting an internal pressure of the reservoir, a return passage connecting the reservoir to the engine intake passage, and an on-off valve interposed in the return passage And valve control means for opening the on-off valve when the reservoir internal pressure exceeds the set pressure based on the detection result of the pressure sensor, so that unnecessary release of fuel evaporative gas from the fuel supply port of the fuel tank during refueling is prevented. It can be prevented reliably, and the internal pressure of the reservoir can always be kept below the set pressure. Therefore, the gas in the fuel tank at the time of refueling can enter the reservoir. Smoothly carried out the introduction.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a fuel evaporation prevention device according to a first embodiment of the present invention together with peripheral elements.

FIG. 2 is a flowchart showing a main routine of a fuel evaporation prevention control program executed by an electronic control unit shown in FIG. 1;

FIG. 3 is a flowchart showing in detail a subroutine for control during engine operation shown in FIG. 2;

FIG. 4 is a flowchart showing in detail a subroutine for control when the engine is stopped shown in FIG. 2;

FIG. 5 is a flowchart showing in detail a subroutine for control during refueling shown in FIG. 2;

FIG. 6 is a schematic view of a fuel evaporation prevention device according to a second embodiment of the present invention.

FIG. 7 is a flowchart of a subroutine for control during engine operation in a second embodiment.

FIG. 8 is a flowchart of a subroutine for control during refueling in a second embodiment.

FIG. 9 is a schematic view of a fuel evaporation prevention device according to a third embodiment of the present invention.

FIG. 10 is a flowchart of a subroutine for control at the time of refueling in a third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Intake manifold 4,60 Air cleaner 10 Fuel tank 10c Filler cap 11 Filler lid opening / closing drive unit 12 Filler lid 13 Refueling end detection switch 21 Electronic control unit 22 Reservoir 23 Compressor 24 Canister 31,32,33,34 Pipe 41,42 , 43, 43a, 43b, 43c, 44, 4
4c Solenoid on-off valve 51, 52 Pressure sensor 53 Lubrication switch

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 33/00 B60K 15/02 L

Claims (1)

(57) [Claims] 1. A reservoir which communicates with a fuel tank via a reserve passage, a compressor which is interposed in the reserve passage and guides gas in the fuel tank to the reservoir side, and operates the compressor in response to a command signal Compressor operating means, a pressure sensor for detecting a reservoir internal pressure, a return passage connecting the reservoir and an engine intake passage, an on-off valve interposed in the return passage, and a reservoir based on a detection result of the pressure sensor. And a valve control means for opening the on-off valve when the internal pressure exceeds a set pressure.