JPH10299583A - Evaporative fuel discharge preventing device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress dry-up of fuel in a fuel tank to the minimum by arranging a control means for controlling an opening of a control valve for opening/closing an evaporation fuel passage so as to set inner pressure in the fuel tank to a target pressure value. SOLUTION: A fuel tank 9 is connected to a downstream side of a throttle valve 3 of an intake pipe 2 through an evaporation fuel passage 20. A tank pressure control valve 30 for opening/closing the evaporation fuel passage 20 is arranged on the way of the evaporation fuel passage 25. By the CPU of an electronic control unit ECU 5, an opening of the control valve 30 is decided according to an output signal of a tank inner pressure sensor 15, a fuel temperature sensor 16, and the like. The opening of the control valve 30 is controlled, and thereby, negative pressure in the intake pipe 2 is acted in the fuel tank 9 so as to hold tank inner pressure Pt in the fuel tank 9 to a prescribed target pressure value. As a result, the inside of the fuel tank 9 is held to negative pressure during operation of the engine 1 as well as after stop. It is thus possible to suppress dry-up of fuel in the fuel tank to the minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for preventing evaporative fuel from being released from an internal combustion engine, and more particularly to an apparatus for preventing evaporative fuel from being released from the fuel tank to the outside air when a filler cap of the fuel tank is opened during refueling. The present invention relates to an evaporative emission control device.

[0002]

2. Description of the Related Art Conventionally, a fuel tank is connected to an intake pipe of an internal combustion engine via a canister to prevent the fuel vapor in a fuel tank mounted on a vehicle from being released to the outside air. 2. Description of the Related Art There is known a technique in which fuel vapor is combusted by an internal combustion engine when the internal combustion engine is operating.

Further, there has been proposed a technique in which a fuel tank is connected to an intake pipe of an internal combustion engine via an evaporative fuel passage, and the fuel in the fuel tank is fueled by the internal combustion engine when the internal combustion engine is operating. According to this technique, the internal pressure of the fuel tank is excessively reduced during operation of the internal combustion engine, and the internal pressure of the fuel tank is maintained at a negative pressure even after the internal combustion engine is stopped as well as during operation of the internal combustion engine. Even if the filler cap is opened, the fuel vapor in the fuel tank is prevented from being released to the outside air.

In this device, a temperature sensor for detecting the temperature of the fuel in the fuel tank and a tank internal pressure sensor for detecting the internal pressure of the fuel tank are provided, and the fuel tank is predicted according to the temperature of the fuel in the fuel tank. A pressure value (target pressure value) that excessively reduces the pressure in the fuel tank is determined in consideration of an increase in the tank internal pressure. Then, using the negative pressure of the intake pipe during operation of the internal combustion engine, the opening degree of the control valve is adjusted by feeding back the detected value of the tank pressure sensor so that the internal pressure of the fuel tank becomes the target pressure value. Control.
As a result, the internal pressure of the fuel tank can normally be maintained at a negative pressure.

[0005]

However, in the above-mentioned prior art, since the fuel tank is always set at a negative pressure, the fuel in the fuel tank loses easily volatile components with the lapse of time, and the fuel is removed. However, there is a problem that a state in which the characteristic cannot be maintained (so-called withered state) is likely to occur.

[0006] Further, since the fuel does not evaporate so much as it becomes withered, the internal pressure of the fuel tank does not need to be largely reduced to a negative pressure. Since the target pressure value is set, there is a problem that the negative pressure is excessively increased in some cases. Such unnecessary negative pressure rather promotes fuel withering.

SUMMARY OF THE INVENTION It is an object of the present invention to control the negative pressure of a fuel tank in consideration of the dead of the fuel, and to minimize the dead of the fuel in the fuel tank when the inside of the fuel tank is maintained at a negative pressure. It is an object of the present invention to provide a fuel vapor emission prevention device for an internal combustion engine that can suppress the fuel vapor emission.

[0008]

According to a first aspect of the present invention, there is provided an evaporative fuel release preventing apparatus for an internal combustion engine, comprising: an evaporative fuel passage connecting a fuel tank to an intake system of the internal combustion engine; An evaporative fuel release prevention device for an internal combustion engine, which is provided in the middle of the evaporative fuel passage and includes a control valve that opens and closes the evaporative fuel passage. A rise amount calculation means for calculating a rise amount of the internal pressure, and a target pressure value of the internal pressure of the fuel tank is determined according to the rise amount calculated by the rise amount calculation means, and the internal pressure of the fuel tank is determined. Control means for controlling the opening of the control valve so as to attain the target pressure value.

According to the above configuration, the target pressure value of the internal pressure of the fuel tank is determined in accordance with the amount of increase in the internal pressure of the fuel tank after the transition from the open state to the closed state of the control valve. Since the opening of the control valve is controlled so as to be the target pressure value determined above, the amount of increase in the internal pressure of the fuel tank calculated by the increase amount calculating means, which indicates the dead state of the fuel in the fuel tank. Based on the amount, it is possible to perform negative pressure control of the fuel tank in consideration of the dead state of the fuel.

According to a second aspect of the present invention, there is provided the evaporative fuel release preventing apparatus for an internal combustion engine according to the first aspect, wherein the temperature detecting means for detecting the temperature of the fuel in the fuel tank is provided. The control means determines the target pressure value in accordance with the rise amount calculated by the rise amount calculation means and the temperature of the fuel detected by the temperature detection means.

With this configuration, the target pressure value of the internal pressure of the fuel tank is determined according to the amount of increase in the internal pressure of the fuel tank and the temperature of the fuel, so that the target pressure value of the internal pressure of the fuel tank is determined. In this case, the amount of heat retained in the fuel tank at that temperature is considered, and the target pressure value can be set to a more appropriate value.

According to a third aspect of the present invention, there is provided the evaporative fuel release preventing device for an internal combustion engine according to the first or second aspect, wherein the control means is calculated by the increase amount calculating means. The target pressure value is set higher as the amount of increase is smaller.

With this configuration, the target pressure value of the internal pressure of the fuel tank is set higher (toward the atmospheric pressure) as the calculated increase amount is smaller, that is, as the fuel is dead. Therefore, when the fuel in the fuel tank is in a dead state, it is possible to prevent the pressure in the fuel tank from being reduced more than necessary and to further suppress the withdrawal of the fuel.

[0014]

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

FIG. 1 is an overall configuration diagram showing a configuration of an evaporative fuel emission prevention device for an internal combustion engine according to the present embodiment. In FIG. 1, reference numeral 1 denotes an internal combustion engine having, for example, four cylinders (hereinafter simply referred to as “engine”), and a throttle valve 3 is arranged in the middle of an intake pipe 2 of the engine 1. A throttle valve opening (θTH) sensor 4 is connected to the throttle valve 3, and outputs an electric signal corresponding to the opening of the throttle valve 3 to output an electronic control unit (hereinafter referred to as “ECU”) 5. To supply.

The fuel injection valve 6 is provided for each cylinder in the intake pipe 2 and slightly upstream of an intake valve (not shown) between the engine 1 and the throttle valve 3. Each fuel injection valve 6 is connected to a fuel tank 9 via a fuel supply pipe 7, and a fuel pump 8 is provided in the fuel supply pipe 7. The fuel tank 9 has a filler port 10 for refueling.
And a filler cap 11 is attached to the filler port 10.

The fuel injection valve 6 is electrically connected to the ECU 5, and a signal from the ECU 5 controls the valve opening timing of the fuel injection.

An intake pipe absolute pressure (P) for detecting an intake pipe absolute pressure PBA is provided downstream of the throttle valve 3 of the intake pipe 2.
A BA) sensor 13 and an intake air temperature (TA) sensor 14 for detecting an intake air temperature TA as an outside air temperature are mounted. The fuel tank 9 has a tank internal pressure (Pt) sensor 15 for detecting a tank internal pressure (absolute pressure) Pt of the fuel tank 9.
And a fuel temperature (Tg) sensor 16 as temperature detecting means for detecting the temperature Tg of the fuel in the fuel tank 9. The detection signals of these sensors 13 to 16 are supplied to the ECU 5.

Next, an evaporative fuel emission suppression system 31 composed of the fuel tank 9, the evaporative fuel passage 20, and the like will be described.

The fuel tank 9 is connected to the intake pipe 2 downstream of the throttle valve 3 via an evaporative fuel passage 20.
A tank pressure control valve 30 for opening and closing the evaporative fuel passage 20 is provided in the middle of the evaporative fuel passage 20. Control valve 30
Is an electromagnetic valve configured to control the flow rate of the evaporative fuel generated in the fuel tank 9 by changing the on-off duty ratio of the control signal. The operation of the control valve 30 is controlled by the ECU 5. You. The control valve 30 may use an electromagnetic valve whose opening degree can be changed linearly.

A cut-off valve 21 is provided at a connection between the fuel vapor passage 20 and the fuel tank 9. The cutoff valve 21 is a float valve that closes when the fuel tank 9 is full or when the inclination of the fuel tank 9 increases.

The ECU 5 shapes input signal waveforms from various sensors and the like, corrects a voltage level to a predetermined level, and converts an analog signal value into a digital signal value. A storage means for storing a calculation program executed by the CPU, a calculation result, and the like, an output circuit for supplying a drive signal to the fuel injection valve 6 and the control valve 30, and the like.

The CPU of the ECU 5 includes a θTH sensor 3, P
The control of the amount of fuel supplied to the engine 1 is performed in accordance with the output signals of various sensors such as the BA sensor 13. Since the fuel amount control is not the subject of the present invention, the description is omitted.

The CPU of the ECU 5 includes the Tg sensor 1 described above.
6, the control valve 30 according to the output signal of the Pt sensor 15, etc.
Is determined. That is, in the present embodiment, EC
The CPU of U5 constitutes the control means.

FIG. 2 is a flowchart showing a control procedure for evaporative fuel emission prevention in the evaporative fuel emission prevention device according to the embodiment of the present invention. Note that a program for executing this flowchart is a program stored in R
Stored in storage means (not shown) such as an AM
It is executed by the CPU of the ECU 5.

First, in step S1, it is determined whether or not the engine 1 is operating, for example, by detecting cranking of the engine 1, and if the engine 1 is operating, the process proceeds to step S2, where the Tg sensor 16 To detect the temperature Tg of the fuel in the fuel tank 9 and further proceed to step S3.
The Pt sensor 15 detects the tank internal pressure Pt of the fuel tank 9.

Then, a target pressure value Po of the tank internal pressure of the fuel tank 9 is calculated by a method of setting a target pressure value (absolute pressure) Po (mmHg) in the fuel tank 9 described later (step S4). At this time, the target pressure value Po is set in the fuel tank 9 in consideration of a predicted increase in the tank internal pressure in the fuel tank 9 so that the negative pressure in the fuel tank 9 can be maintained even after the engine 1 is stopped. It is set to a value that causes excessive negative pressure.

The cause of the increase in the tank internal pressure is that the component contained in the fuel, which evaporates at a temperature lower than the fuel temperature, evaporates due to the amount of heat retained in the fuel in the fuel tank 9 at that temperature; As described above, a portion of the fuel evaporates due to a rise in the temperature of the fuel in the fuel tank 9 due to the rise in the temperature.

Next, the difference ΔP between the tank internal pressure Pt of the fuel tank 9 and the target pressure value Po is calculated (step S).
5) The opening of the control valve 30 is controlled so that the calculated difference ΔP becomes 0 (step S6), and this processing ends.

When the engine 1 is stopped in step S1, the CPU of the ECU 5 closes the control valve 30 to maintain the negative pressure in the fuel tank 9 controlled to the target pressure value Po (step S1). S7), this process ends.

With the above configuration, during operation of the engine 1, by controlling the opening of the control valve 30, the negative pressure in the intake pipe 2 is applied to the fuel tank 9, and the tank internal pressure Pt of the fuel tank 9 is adjusted. At the predetermined target pressure value Po. As a result, the inside of the fuel tank 9 is maintained at a negative pressure even after the engine 1 is stopped as well as during operation.

Here, a method of setting the target pressure value Po in the fuel tank 9 in step S4 of FIG. 2 will be described with reference to FIGS.

FIG. 3 is an explanatory diagram showing a change in the tank internal pressure Pt in the fuel tank 9 after the negative pressure of the normal (not withered) fuel and the withered fuel. In the figure, the change in the tank internal pressure Pt of the normal fuel after the negative pressure is indicated by a solid line A, and the change of the tank internal pressure Pt of the dead fuel after the negative pressure is indicated by a broken line A. .

As described above, even when the pressure inside the fuel tank 9 is reduced to a negative pressure, the tank internal pressure Pt remains
The same as above due to the fact that the components contained in the fuel that evaporate at a temperature lower than the fuel temperature evaporate due to the retained heat amount of the fuel in the fuel at that temperature, and the temperature of the fuel in the fuel tank 9 increases due to an increase in the outside air temperature. It rises due to factors such as evaporation of part of the fuel.

However, the fuel in the fuel tank 9 is
When the inside of the fuel tank 9 is always under negative pressure, components that easily volatilize escape, and the so-called dead state tends to occur. Further, the evaporation component contained in the fuel in the fuel tank 9 decreases as the fuel dies. Therefore, as is clear from FIG. 3, the tank internal pressure Pt (broken line a) in the fuel tank 9 having the dead fuel is the tank internal pressure in the fuel tank 9 having the normal fuel. It does not rise as much as Pt (solid line a). That is, it is not necessary to reduce the pressure of the dead fuel to the same degree as that of the normal fuel.

FIG. 4 is a graph showing a fuel temperature-tank pressure rise amount curve according to the "dead amount" indicating the degree of the dead state of the fuel. The vertical axis indicates the negative pressure after stopping the negative pressure. The tank internal pressure rise amount ΔPup (mmHg) is shown, and the horizontal axis shows the temperature Tg (° C.) of the fuel in the fuel tank. Here, the withered amount of fuel is represented by the ratio of the weight of evaporated fuel per unit weight of fuel. As is clear from the figure, as the withering amount of the fuel increases, the increase amount ΔPup of the tank internal pressure Pt after the negative pressure with respect to the fuel temperature Tg decreases. Further, as the fuel temperature Tg increases, the amount of increase ΔPup of the tank internal pressure Pt of the fuel tank 9 increases.

As described above, it is known that the larger the wither amount of fuel, the smaller the increase amount ΔPup of the tank internal pressure Pt after the negative pressure becomes. Therefore, in the present embodiment, the increase amount ΔPup of the tank internal pressure Pt is By performing the calculation, the amount of fuel withering is estimated, and a process of shifting the target pressure value Po to the atmospheric pressure side according to the estimated amount of fuel withering is performed.

FIG. 5 is a flow chart for explaining a procedure for setting the target pressure value Po, and FIG. 6 is an explanatory view for explaining a technique for estimating the wither amount of fuel in the fuel tank 9.

A program for executing the flowchart shown in FIG. 5 is stored in a storage means (not shown) such as a RAM in the ECU 5,
Performed by U. That is, the CPU of the ECU 5
Constitutes a rise amount calculating means for calculating a rise amount ΔPup of the fuel tank internal pressure Pt.

First, a target pressure value Po in the fuel tank 9 is calculated by a method for setting a target pressure value Po in the fuel tank 9 shown in FIG. 7 described later (step S10). Next, the control valve 30 is opened to start reducing the tank internal pressure Pt in the fuel tank 9 to a negative pressure (step S11), and the tank internal pressure Pt is slightly lower than the target pressure value Po as shown in FIG. It is determined whether or not P1 or less has been reached (step S12). By this determination, the tank internal pressure Pt becomes the pressure value P1.
If not, the procedure of step S12 is repeated.

In step S12, the tank internal pressure Pt
When the pressure becomes equal to or lower than the pressure value P1, the control valve 30 is closed to stop the negative pressure (step S13), and after a predetermined time t has elapsed since the control valve 30 was closed, the tank internal pressure value P2
(Step S14), and the tank internal pressure values P1 and P1
Based on the difference between the two, the increase amount ΔPup of the tank internal pressure in the fuel tank 9 is calculated (step S15).

The rising amount ΔPu calculated in step S15
Since there is a relationship as shown in FIG. 4 between p and the fuel withering amount, the fuel withering amount is estimated based on the calculated rise amount ΔPup and the fuel temperature Tg obtained from the Tg sensor. Then, based on a setting method of a target pressure value Po in the fuel tank 9 of FIG. 8 described later, a target pressure value Po corresponding to the withering amount is set (step S17), (step S17).
This processing ends.

In the above-described method for estimating the withering amount of fuel, the amount of increase ΔPup of the tank internal pressure in the fuel tank 9 is calculated only once, and the withering amount is directly estimated from the calculated value. As shown in FIG. 6, the negative pressure in the fuel tank 9 and the calculation of the rising amount at the predetermined time t are performed a plurality of times, and the average value of the plurality of calculated values is calculated as the rising amount ΔPup.
May be used to estimate the withering amount.

FIG. 7 is a graph showing a fuel temperature-tank internal pressure curve for a normal fuel for explaining the standard for setting the target pressure value Po in step S10 of FIG. The vertical axis indicates the tank internal pressure Pt (mmHg) of the fuel tank 9.
Is shown. Further, the tank internal pressure Pt on the vertical axis is indicated by the absolute pressure as described above, and the lower the graph, the lower the pressure.

The set range value of the target pressure value Po in the fuel tank 9 shown in FIG. 7 is stored in a storage means (not shown) of the ECU 5 in the form of a map.

In FIG. 5, the curve A indicates that the fuel tank 9 is stopped even when the engine 1 is stopped and the fuel tank 9 is turned to a negative pressure.
Is the upper limit value of the target pressure value Po of the tank internal pressure Pt for excessively reducing the pressure in the fuel tank 9 during running of the vehicle so that the internal pressure of the engine 1 is maintained at the negative pressure. Immediately thereafter, the amount of increase in the tank internal pressure Pt of the fuel tank 9 due to the evaporation of the component that evaporates at a temperature lower than the fuel temperature among the components contained in the fuel is determined by the amount of heat retained in the fuel tank 9 at the temperature Tg. The upper limit value of the target pressure value Po of the tank internal pressure Pt considered is shown. As shown in the curve A, as the fuel temperature Tg increases, the tank internal pressure P
The target pressure value Po of t is decreased.

Curve B indicates that the fuel tank 9 is maintained at a negative pressure while the vehicle is running so that the internal pressure of the fuel tank 9 is maintained at a negative pressure even when the engine 1 is stopped and the fuel tank 9 is turned into a negative pressure. Target pressure value Po of tank internal pressure Pt for making the pressure excessively negative
Is the upper limit of the tank internal pressure P of the fuel tank 9 when the outside air temperature rises to a predetermined assumed maximum outside air temperature of 45 ° C. while the vehicle is stopped or parked, and the fuel temperature Tg also rises to 45 ° C.
target pressure value Po of the tank internal pressure Pt in consideration of the increase in t
Shows the upper limit of The predetermined assumed maximum outside air temperature of 45 ° C. is a maximum value of the outside air temperature assumed when designing the vehicle. Curve B
As shown in (2), as the fuel temperature Tg increases, the target pressure value Po of the tank internal pressure Pt increases.

The curve A + B is a curve that satisfies the conditions of the curves A and B at the same time. When 45 ° C. is selected as the assumed maximum outside air temperature, the control valve 30 sets the fuel temperature T
g, the tank internal pressure Pt of the fuel tank 9 is equal to the curve A +
The opening is controlled so as to be B or less.

A curve C represents the lower limit of the suction pressure of the fuel pump 8 for transferring the fuel from the fuel tank 9 to the engine 1, that is, the lower limit of the target pressure value Po of the fuel tank 9. Fuel tank 9
If the tank internal pressure Pt is equal to or lower than the curve C, the fuel pump 8 cannot suck the fuel from the fuel tank 9, so the tank internal pressure Pt in the fuel tank 9 needs to be equal to or higher than the curve C. As shown by the curve C, the tank internal pressure Pt increases as the fuel temperature Tg increases. Further, the lower limit of the target pressure Po of the tank internal pressure Pt according to the curve C is smaller than the upper limit of the target pressure Po of the tank internal pressure Pt according to the curve A + B.

Therefore, when the fuel in the fuel tank 9 is a normal fuel that is not in a dead state, even if the engine 1 is stopped and the negative pressure of the fuel tank 9 is stopped, the tank internal pressure Pt of the fuel tank 9 is stopped. To maintain a negative pressure, the target pressure value Po
FIG. 7 shows a value that satisfies all the conditions according to the curves A, B, A + B, and C, that is, the value of the tank internal pressure Pt in the fuel tank 9.
Must be set according to the fuel temperature Tg.

FIG. 8 is a graph showing a fuel temperature-tank internal pressure curve for the dead fuel, for explaining the setting criteria of the target pressure value Po according to the dead amount in step S17 in FIG. Represents the temperature Tg (° C.) of the fuel in the fuel tank 9, and the vertical axis represents the tank internal pressure P of the fuel tank 9.
t (mmHg). Further, the tank internal pressure Pt on the vertical axis is shown as an absolute pressure, and the lower the graph, the lower the pressure.

As described above, when the fuel is dead, it is necessary to set the target pressure value to the atmospheric pressure side from the target pressure value set for the fuel in the normal state. Therefore, when the fuel is in a dead state, the target pressure value Po is obtained by shifting the curves A and B shown in FIG. 7 and the curves A ′ and B ′ obtained by shifting the curves A ′ and B ′ described above.
And the curve A '+ B' obtained from the curves A 'and B' must be set to a value that satisfies all the conditions, that is, the tank internal pressure in the fuel tank 9 must be set to a value within the shaded area shown in FIG. There is.

Therefore, in step S17 described above, the target pressure value Po is set using a target pressure value map that satisfies the condition of FIG.

The shift amounts of the curves A ′, B ′, A ′ + B ′ from the curves A, B, A + B are set based on the experimental value of the increase ΔPup.

The set value of the target pressure Po is determined by the ECU.
5, the amount of increase ΔPup in the tank internal pressure Pt varies depending on the amount of fuel withering in the fuel tank 9 as shown in FIG. It is desirable to store the pressure value map in the storage means.

As described above, according to the present embodiment, the amount of increase ΔPup of the tank internal pressure Pt is calculated, and the fuel is calculated according to the withered amount of fuel obtained from the calculated amount of increase ΔPup and the fuel temperature Tg. Since the target pressure value Po of the tank is set, it is possible to perform negative pressure control of the fuel tank in consideration of the dead of the fuel when the internal combustion engine is operating and when it is stopped. Further, since the target pressure value Po is determined in accordance with the withering state of the fuel, it is possible to prevent the pressure inside the fuel tank 9 from being reduced more than necessary when maintaining a negative pressure, thereby minimizing the withering of the fuel. Can be minimized.

[0057]

As described above, according to the first aspect of the present invention, it is possible to control the negative pressure of the fuel tank in consideration of the dead state of the fuel. When the inside of the fuel tank is maintained at a negative pressure in order to prevent the evaporative fuel from being released to the outside air, it is possible to minimize the withering of the fuel in the fuel tank.

According to the second aspect of the present invention, when determining the target pressure value of the internal pressure of the fuel tank, the amount of heat retained in the fuel in the fuel tank at that temperature is considered. The inside of the fuel tank can be reliably maintained at a negative pressure.

According to the third aspect of the present invention, when the fuel in the fuel tank is dead, the pressure in the fuel tank can be prevented from being reduced more than necessary when the fuel in the fuel tank is dead. Withering can be suppressed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing a configuration of an evaporative fuel release prevention device for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control processing procedure of evaporative fuel emission prevention in the evaporative fuel emission prevention device according to the embodiment.

FIG. 3 is an explanatory diagram showing a change in the tank internal pressure Pt in the fuel tank 9 after the negative pressure of a normal (not withered) fuel and a withered fuel.

FIG. 4 is an explanatory diagram showing a fuel temperature-tank pressure rise amount curve according to a “withering amount” indicating a degree of a withering state of fuel.

FIG. 5 is a flowchart illustrating a procedure for setting a target pressure value in a fuel tank.

FIG. 6 is an explanatory diagram for explaining a method of measuring a withering amount of fuel in a fuel tank.

FIG. 7 is a graph showing a fuel temperature-tank internal pressure curve for explaining a reference for setting a target pressure value in a fuel tank.

FIG. 8 is a graph showing a fuel temperature-tank internal pressure curve for explaining a standard for setting a target pressure value in a fuel tank.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 5 Electronic control unit 9 Fuel tank 15 Tank internal pressure sensor 16 Fuel temperature sensor 20 Evaporated fuel passage 30 Tank pressure control valve 31 Evaporated fuel release suppression system

Claims (3)

[Claims] 1. An evaporative fuel discharge system for an internal combustion engine, comprising: an evaporative fuel passage connecting a fuel tank to an intake system of the internal combustion engine; and a control valve provided in the middle of the evaporative fuel passage to open and close the evaporative fuel passage. In the prevention device, in accordance with the rise amount calculated by the rise amount calculation means, the rise amount calculating means for calculating the rise amount of the internal pressure of the fuel tank after the transition from the open state to the closed state of the control valve. A control means for determining a target pressure value of the internal pressure of the fuel tank, and controlling an opening of the control valve so that the internal pressure of the fuel tank becomes the determined target pressure value. Evaporative fuel release prevention device. 2. A fuel cell system comprising: a temperature detecting means for detecting a temperature of the fuel in the fuel tank; wherein the control means comprises a controller for detecting the amount of increase calculated by the increase amount calculator and the fuel detected by the temperature detector. 2. The apparatus according to claim 1, wherein the target pressure value is determined in accordance with a temperature of the engine. 3. The evaporation of the internal combustion engine according to claim 1, wherein the control unit sets the target pressure value higher as the increase amount calculated by the increase amount calculation unit is smaller. Fuel emission prevention device.