JP2930831B2 - Evaporative fuel processing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporative fuel processing control apparatus for controlling the processing of evaporative fuel in a fuel tank for an internal combustion engine mounted on a vehicle, and more particularly, to supercharging fuel to the fuel tank during fuel supply. The present invention relates to an evaporative fuel processing control device for preventing the above.

[0002]

2. Description of the Related Art If the pressure in a fuel tank is high when fuel is supplied, the fuel vapor in the tank is released into the atmosphere when the filler cap is opened. Various evaporative fuel treatment devices for vehicles that control the inside of a fuel tank to an appropriate internal pressure have been proposed.

For example, in Japanese Utility Model Application No. 3-38883, a solenoid valve provided in a vent passage during running is opened to reduce the pressure in a fuel tank to about an atmospheric pressure via a canister, and then stopped to refuel. Is performed, the pressure in the fuel tank is reduced to prevent the fuel vapor from being released from the fuel filler.

Japanese Patent Application Laid-Open No. 3-222855 discloses an example in which an opening / closing means for opening / closing a vent passage is opened for a predetermined time after the engine is stopped to reduce the tank internal pressure.

[0005]

However, in the case of the prior art, if refueling is performed while the engine is operating, or if refueling is performed early even after the engine is stopped, the on-off valve of the vent passage opens. Since the fuel tank and the canister are in communication with each other, if the fuel tank is full during refueling, the upper space in the fuel tank is normally closed and refueling cannot be performed when the fuel tank is full. Is not secured, and the fuel in the filler neck gradually enters the fuel tank even after the automatic tank full stop is detected, so that the fuel can be further supplied.

[0006] Therefore, depending on the user, the refueling operation may be repeated, so that a so-called supercharging state occurs, and the fuel in the fuel tank blows out from the refueling port due to the fluctuation of the oil level due to the expansion of fuel, vibration or turning during running. ,
Inflow into the vent passage and into the canister may cause problems such as deterioration of the activated carbon and fuel leakage from the canister.

[0007] The present invention has been made in view of the above points, and its object is to refuel even when the internal combustion engine is in an operating state, or at an early point in time when the internal combustion engine is stopped. Therefore, the present invention provides an evaporative fuel processing control device for an internal combustion engine, which prevents the discharge of evaporative fuel and has no risk of supercharging.

[0008]

In order to achieve the above object, the invention according to claim 1 is a fuel tank.
Is higher than the atmospheric pressure.
Pressure state and set valve opening lower than atmospheric pressure Pressure lower than negative pressure
The two-way valve that opens in the state of
In the vent passage that connects the space and the canister,
The evaporative fuel treatment system equipped with a solenoid valve in parallel with the two-way valve
In the fuel tank provided in series with the solenoid valve
The second setting valve is lower than the first setting valve positive pressure.
A one-way valve that opens at a pressure equal to or higher than the positive pressure, and the fuel
A fuel level detecting means for detecting a fuel level in the tank;
In a predetermined operating state of the fuel engine, the solenoid valve is opened,
The fuel level is detected by the fuel level detecting means so that the fuel level exceeds a predetermined level.
Electromagnetic that closes the solenoid valve when a certain state is detected
And a valve control means.
Was placed.

[0009]

[0010]

[0011]

The upper space of the fuel tank and the canister are connected.
A two-way valve is interposed in the vent passage through which the two-way valve
Has solenoid valve controlled in parallel based on fuel level
Therefore, usually, the fuel vapor is controlled by a two-way valve to operate the internal combustion engine.
Even if refueled during rotation, the release of fuel vapor and the refueling are prevented.
And a one-way valve in series with the solenoid valve.
Direction valve is the first setting of the two-way valve.
Since the valve is opened at the valve opening positive pressure or higher, when the internal combustion engine is in a predetermined operation state and the pressure in the upper space of the fuel tank is equal to or less than the second set valve opening positive pressure of the one-way valve, The one-way valve is shut off, preventing excessive adsorption of the fuel vapor in the fuel tank to the canister, and the load on the canister is reduced.

Further, when the internal combustion engine is in a predetermined operating state,
Even if the pressure in the upper space of the fuel tank is equal to or less than the first set positive pressure for opening the two-way valve, if the pressure is equal to or more than the second set positive pressure for opening the one-way valve, the one-way The valve is opened, and the pressure in the fuel tank is maintained between the first set positive pressure of the two-way valve and the second set positive pressure of the one-way valve and applied to the fuel tank. The pressure is reduced,
The durability of the fuel tank is improved.

[0014]

According to a second aspect of the present invention, there is provided an evaporative fuel treatment apparatus provided with a valve for opening and closing the vent passage in a vent passage communicating the upper space of the fuel tank and the canister. Operating / stop detecting means for detecting the state of the internal combustion engine when the valve is in an open state when the operating / stop detecting means detects a transition from an operating state to a stopped state; Evaporative fuel processing of an internal combustion engine having valve control means for closing the valve when the operation is restarted within a predetermined time immediately after the shift to the stop state or when the operation is not restarted within the predetermined time. Control device.

Although the pressure in the fuel tank increases immediately after the stop of the internal combustion engine depending on running conditions, environmental conditions, and the like, the internal combustion engine has shifted from operation to stop with the valve provided in the vent passage open. At this time, since the valve keeps the open state, the internal pressure of the fuel tank is prevented from rising, and even if the filler cap is removed for refueling immediately after the stop of the internal combustion engine, the release of fuel vapor can be prevented. And a predetermined time has passed
Then the valve closes, closing the upper space of the fuel tank
As a state, supercharging can be prevented. Also at a prescribed time
The operation of the internal combustion engine has resumed even before the
The moxibustion valve can be closed to return to normal evaporative fuel control.
You.

According to a third aspect of the present invention, an upper portion of a fuel tank is provided.
The vent passage communicates with the space and the canister.
In an evaporative fuel treatment system equipped with a valve to open and close the
Run / stop detection that detects whether the fuel engine is running or stopped
Output means and fuel for detecting a fuel level in the fuel tank
Whether the liquid level detection means and the operation / stop detection means are in the operating state
The valve is opened when it detects a transition from
In some cases, keep the valve open and stop the internal combustion engine
Within a predetermined time immediately after the shift to
When it is detected that the fuel level is higher than the predetermined level
Or the fuel level does not reach the predetermined height within the predetermined time
Valve control means for closing the valve when the predetermined time has elapsed
This is an evaporative fuel processing control device for an internal combustion engine provided with: Ben
The internal combustion engine operates with the valve provided in the
The valve is configured to remain open when transitioning from stop to stop
This is the same as the second aspect of the present invention,
Immediately after stopping the engine, remove the filler cap to refuel.
However, the release of fuel vapor can be prevented. And the predetermined time has passed
Or even before the specified time has elapsed, the fuel tank
The valve closes when the liquid level exceeds a predetermined level.
The upper space is closed, and when the tank is full during refueling, refueling is disabled and overcharging can be prevented.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention shown in FIGS. 1 to 4 will be described below. The internal combustion engine E mounted on the automobile absorbs a mixture of fuel and air from the intake pipe 1 and obtains power by combustion, and the exhaust gas after combustion is discharged from the exhaust pipe 2. A throttle body 3 is formed in the pipe 1, and a throttle valve 4 is disposed therein. A fuel injection valve 5 is provided downstream of the throttle valve 4 and upstream of an intake valve (not shown) of the internal combustion engine E. The fuel injection 5 is provided and connected to a fuel tank T via a fuel pump 6.

Each load detecting means for detecting the operating state of the internal combustion engine E is provided as follows. An intake pipe absolute pressure sensor 10 for detecting an absolute pressure PbA in the intake pipe 1 is provided in a branch pipe 7 on the downstream side of the throttle valve 4, and an engine rotation around a camshaft or a crankshaft (not shown) of the internal combustion engine E is provided. An engine speed sensor 11 for detecting the engine speed Ne is provided. The engine speed sensor 11 detects the TDC at a predetermined crank angle position every 180 degree rotation of the crankshaft of the internal combustion engine E.
It emits a signal pulse.

Further, an engine water temperature sensor 12 for detecting an engine water temperature Tw is attached to the main body of the internal combustion engine E, and an O ₂ sensor 13 for detecting the oxygen concentration in the exhaust gas is provided in the exhaust pipe 2 of the internal combustion engine E. The throttle valve 4 is also provided with a throttle valve opening sensor 14 for detecting the throttle valve opening.

The detection signals from the sensors are all input to the electronic control unit ECU, and the electronic control unit ECU performs arithmetic processing based on the information, and outputs various control signals to the respective driving devices to perform optimal control. It is supposed to do.

For example, an electronic control unit ECU
Is the O ₂ sensor based on signals from various sensors.
13 to control various engine operation states such as a feedback control operation area and an open loop control operation area according to the oxygen concentration in the exhaust gas, and according to the engine operation state, synchronize the fuel injection valve 5 with the TDC signal pulse. the fuel injection time calculates the T _OUT, which is the required fuel supply amount of the fuel injection valve 5 based on the fuel injection time T _OUT by duty control so as to supply to the internal combustion engine E.

In the internal combustion engine E provided with such an electronically controlled fuel injection device, an evaporative fuel processing mechanism for processing the evaporative fuel in the fuel tank T so as not to leak to the outside world is provided.

A vent passage 20 communicating with an upper space in a fuel tank T mounted on a vehicle extends from an upper wall of the fuel tank T to an inlet pipe C ₁ protruding from an upper wall of the canister C.
The vent passage 20 is provided with a two-way valve 21 in which a pair of one-way valves in opposite directions are connected in parallel, and the two-way valve 21 is connected to the pressure in the fuel tank T. There a high pressure state than the first set opening positive pressure P ₁ higher than atmospheric pressure,
It is adapted to open at a lower pressure condition than the low set valve opening negative pressure P ₃ than atmospheric pressure.

A vent solenoid valve 23 and a one-way valve 24 are disposed in series in a bypass passage 22 bypassing the two-way valve 21. becomes a two lower than the first set opening positive pressure P ₁ in the direction valve 21 and the second set opening positive pressure P ₂ (a slightly higher pressure value than the atmospheric pressure) or higher, so as to open.

Further, inside the container of the canister C, the space sandwiched by the upper and lower filters C ₂ is filled with activated carbon C ₃ , and the outlet chamber C ₄ of the upper space is connected to the throttle chamber in the intake pipe 1 through the purge passage 25. communicates the valve 4 on the downstream side, purged solenoid valve 26 is interposed in the purge passage 25, the air chamber C ₅ below the space communicates with the atmosphere via a vent pipe 27.

Further, the purge solenoid valve 26 is provided with a purge detecting means 15 and a float is provided in the fuel tank T.
A fuel level detecting means 17 for detecting a fixed level by the fuel level detecting means 16 is provided.
It is transmitted to the CU.

The ignition system 8 attached to the internal combustion engine E
Thus, a start / stop sensor 18 for detecting whether or not the internal combustion engine E is operating is provided, and a vehicle speed sensor 19 is provided. These detection signals are transmitted to the electronic control unit ECU. ing.

Further, the electronic control unit ECU operates according to a flowchart as shown in FIG.

That is, in step S1, it is determined whether or not the internal combustion engine E has started operation based on the output of the operation / stop sensor 18. If the operation has not started, step S1 is executed.
2. Proceeding to S3, the vent solenoid valve 23 is closed, and the solenoid valve flag is set to "0" (FP / L).
VLV = 0).

[0031] If the start of the operation at step S1, the process proceeds to step S4, the vehicle speed Vp is determined whether a predetermined vehicle speed V _PSTP above, when the vehicle speed Vp is less than a predetermined vehicle speed V _PSTP,
In step S5, it is determined whether or not a predetermined time tmstp has elapsed. If it has elapsed, the process proceeds to step 6, and if not, the process proceeds to step S8, and the timer TMFLCHK is reset.

In step S4, the vehicle speed Vp is changed to the predetermined vehicle speed V
If it is equal to or greater than _PSTP , the process proceeds to step 7 where the timer TMST
P is reset, and then in step S8, the timer TMFL
Reset CHK.

When the routine proceeds to the full tank determination subroutine of step S6, as shown in FIG.
It is determined whether or not the vent solenoid valve 23 is currently open. If the vent solenoid valve 23 is open, the process proceeds to step S10, where the fuel level detection sensor 17 outputs the high level Hi or higher. Is determined, and if not higher than the high liquid level Hi, the process proceeds to step S11, where the timer TMFLCH
Reset KHi.

Further, when the fuel level detection sensor 17 detects the high liquid level Hi in step S10, it is determined in step S12 whether or not the timer TMFLCHKHi has passed a predetermined time tmflchkhi. To set the flag F-FLLO to "0".

However, in step S11, the timer TM
After resetting FLCHKHi, or step S12
If the timer TMFLCHKHi has not passed the predetermined time tmflchkhi in step S17, the flow advances to step S17 to set the flag F-FLL.
O is set to "1".

If the vent solenoid valve 23 is closed in step S9, the process proceeds to step S14, in which it is determined whether or not the output of the fuel level detection sensor 17 detects an output of the low level Lo or lower. , If the low liquid level Lo or less is not detected,
The process proceeds to test S15, resets the timer TMFLCHKLo, and proceeds to step S13.

In step S14, if the output of the fuel level detection reset 17 has been detected to be lower than the low level Lo,
Proceeding to step S16, it is determined whether the timer TMFLCHKLo has passed a predetermined time tmflchklo. If it has not passed, the process proceeds to step S13. If the predetermined time tmflchklo has passed, the process proceeds to step S17.

After the subroutine of step S6 (shown in FIG. 4) has elapsed, step S18 in FIG.
To determine if the tank is full or not, ie, the flag F-FLLO
Is not full or not, and the battery is not full (F-FLLO
= 1), the process proceeds to step S19, in which the internal combustion engine E is operated at a rotational speed equal to or higher than the idle rotational speed and the water temperature T
w is equal to or higher than a predetermined temperature, and O _2
(2) It is determined whether or not the purge start condition of the canister such as after the start of the fuel supply control by the feedback control is satisfied. If the purge start condition is satisfied, the vent solenoid valve 23 is opened in step S20 and the step In step S21, the flag FP / LVLV is set to "1" and "1".

However, in step S18, the tank is full (FF).
If LLO = O), and if the purge start condition is not satisfied in step S19, the process proceeds to steps S2 and S3,
Opening the vent solenoid valve 23 and flap FP / LV
LV is set to “0”.

Since the embodiment shown in FIGS. 1 to 4 is configured as described above, in a state where the internal combustion engine E is operating, is not full, and satisfies the purge start condition, FIG. , Steps S1, S4, S5,
Via S6 or steps S1, S4, S7, S8
, And further through steps S18 and S19, the process proceeds to steps S20 and S21, the baint solenoid valve 23 is opened,
Also to open the filler cap T ₁ of the fuel tank, fuel vapor in the fuel tank bypass path 22, the canister C,
Intake pipe 1 via purge solenoid valve 26 and purge passage 25
, Flows into the internal combustion engine E, burns, and prevents the fuel vapor in the fuel tank T from being released into the atmosphere.

If the internal combustion engine E has not started operation, or if the internal combustion engine has been operated but is full, or if the internal combustion engine E has been operating and is not full, If the purge start condition is not satisfied, the routine proceeds to steps S2 and S3, where the vent solenoid valve 23 is closed, so that the bypass passage 22 is shut off and the fuel tank T
The internal pressure is controlled by a two-way valve 21.

Further, in this embodiment, the state in which the refueling operation is to be performed is not detected by a detecting means such as a lid switch or a cap open detecting switch, and the vehicle train Vp is not more than a predetermined _VPSTP. If the predetermined time tmstp has elapsed, it is estimated that refueling will be performed, and the process proceeds to the full tank determination subroutine of step 6, where the state in which the liquid level in the fuel tank T is equal to or higher than the full tank liquid level Hi is the predetermined time tmfl.
Since the solenoid valve is closed when it is detected that the tank is full after the passage of chklo, the supercharging can be reliably prevented without the need for a lid switch or a cap open detection switch. Therefore, since there is no need for a lid switch or a cap open detection switch that has a short life and a large number of times of opening and closing operations and is easy to fail, the durability and reliability of the full tank detection system can be improved.

In the embodiment shown in FIGS. 1 to 4, a two-way valve 21 is provided in the vent passage 20, and a vent solenoid valve 23 and a one-way valve 24 are provided in a bypass passage 22 which bypasses the two directions 21. Although interposed in series, as shown in FIG.
The internal pressure of the fuel tank T is set by the negative pressure setting unit 29 instead of interposing the two-way valve 21 that opens and closes when the internal pressure of the fuel tank T is higher than the atmospheric pressure by a predetermined pressure, in the vent passage 20. A two-way valve 28 that opens and closes when a predetermined pressure is higher than the pressure may be interposed in the vent passage 20.

That is, the two-way valve 28 is composed of a pair of two-way valves 28a and 28b which are opposite to each other. The one-way valve 28a which opens when the internal pressure of the fuel tank T is higher than the set pressure of the negative pressure setting unit 29 is , A valve chamber 28e and a negative pressure chamber inside the valve case 28c.
A negative pressure chamber 28f is connected to a downstream side of the throttle valve 4 in the intake pipe 1 through a negative pressure pipe 30, and a valve seat sleeve 28g is connected to a one-way valve 28b close to the canister C. It is connected to the.

The one-way valve 28a is provided with a valve spring 28h.
The one-way valve 28b which is pressed against the upper surface of the valve seat sleeve 28g by the spring force of the valve seat 28g and is opened when the internal pressure of the fuel tank T is lower than the internal pressure of the canister c, the lower surface of the valve seat sleeve 28g by the spring force of the valve spring 28i. Is pressed.

Further, a negative pressure setting unit 29 is provided in the negative pressure pipe 30.
And a solenoid valve 31 for controlling the set pressure of the negative pressure setting unit 29 are interposed in series, and a valve case 29a of the negative pressure setting unit 29 is provided.
Is divided by a diaphragm 29b into a negative pressure chamber 29c and an atmospheric pressure chamber 29d, and a load valve 29c is attached to the lower surface of the diaphragm 29b. A restrictor 29i is provided on a branch pipe 29b which is further separated from the negative pressure pipe 30b near the two-way valve 28, and the branch pipe 29h is open to the atmosphere.

When the solenoid valve 31 is opened and Pb negative pressure is introduced into the negative pressure chamber 29c of the negative pressure setting unit 29, the negative pressure is applied to the spring force of the valve spring 29f and the diaphragm.
When dropped on the setting below the negative pressure P _N, which is defined by the 29b, the diaphragm 29b and the negative pressure valve 29e I押勝the spring force of the valve spring 29f is lowered and the negative pressure valve 29e valve seat
When a predetermined time has passed since the negative pressure chamber 29c was closed by contact with the negative pressure chamber 29g and the negative pressure chamber 29c was closed by the air in the atmosphere flowing into the negative pressure chamber 29c from the throttle 29i in the branch pipe 29h.
The pressure in 29c rises above the set negative pressure _PN , and the negative pressure valve 29e is opened again. With such repetition, in the open state of the solenoid valve 31, the pressure in the negative pressure chambers 29c, 28f becomes , Is maintained at the set negative pressure P _N.

When the solenoid valve 31 is closed, the negative pressure in the intake pipe 1 is not introduced into the negative pressure chamber 29c of the negative pressure setting unit 29, and the pressure in the negative pressure chamber 29c is reduced by the branch pipe 29h. Since the atmospheric pressure is maintained by the air in the atmosphere flowing from the throttle 29i, the negative pressure chamber 28f of the two-way valve 28 is also maintained at the atmospheric pressure.

In the embodiment shown in FIG. 5, similarly to the embodiment shown in FIGS. 1 to 4, when the pressure in the fuel tank is equal to or higher than the atmospheric pressure while the solenoid valve 31 is opened or closed. Since the set pressure at which the fuel tank T and the canister c can communicate with each other can be set in two stages, FIG.
Control similar to that shown in the flowchart of FIG. 4 can be performed.

In the above embodiment, the emission of fuel vapor and the supercharging are mainly prevented when refueling is performed when the internal combustion engine is operating, but the internal combustion engine is stopped. An embodiment in which the above-mentioned problem in refueling later is solved will be described below.

The present embodiment also uses the evaporative fuel processing control device shown in FIG. 1 and controls according to the flowchart of FIG. When entering this routine, first, step S
At 31, it is determined whether or not the internal combustion engine E is in operation this time based on the output of the operation / stop sensor 18, and if it is in operation, the process proceeds to step S32, where it is determined whether or not it was in the previous operation. If so, the process proceeds to step S33 to determine whether or not a predetermined operating condition is satisfied (see FIG.
Steps S4, S5, S6, S7, S8, S18, S19
If it is satisfied, the process proceeds to step S34 to open the vent solenoid valve 23, then sets the flag FP / LVLV to "1" (step S35) and proceeds to step S38 to set the down timer TM to a predetermined value. Reset to time.

When it is determined in step S32 that the internal combustion engine is not operating last time, and when it is determined in step S33 that the predetermined operating conditions are not satisfied, the process jumps to step S36 to close the vent solenoid valve 23. Then, the flag FP / LVLV is set to "0" (step S37),
Proceeding to step S38, the timer TM is reset.

That is, when the internal combustion engine E was previously stopped and brought into the current operation state, the operation proceeds from step S32 to step S36.
And the vent solenoid valve 23 is closed and the flag FP / LVLV is closed.
To “0” to reset the timer TM. From the next time, since the internal combustion engine is still in operation, the process proceeds from step S32 to step S33 to determine whether or not the predetermined operating conditions are satisfied.
And the vent solenoid valve 23 is kept closed.

When the predetermined operating conditions are satisfied, step S33 is executed.
The process then proceeds to step S34, where the solenoid valve 23 is opened to reduce the pressure in the fuel tank during normal running. If the predetermined operating conditions are not satisfied during the operation of the internal combustion engine as described above, the solenoid valve 23 is opened. The control is performed to close the solenoid valve 23 and open the solenoid valve 23 when satisfied.

When the internal combustion engine stops, step S
From step 31, the flow jumps to step S39 to determine the state of the jump flag FP / LVLV. The flag FP / LVLV is a flag for storing the state of the solenoid valve 23 immediately before the stop of the internal combustion engine. If the solenoid valve 23 is closed and FP / LVLV = 0, the process jumps from step S39 to step S43. Solenoid valve 23
Is closed, while the solenoid valve 23 is open and the FP / LVL
If V = 1, the process proceeds from step S39 to step S40.

In step S40, it is determined whether or not the down timer TM reset in step S38 has counted a predetermined time and has become 0, and proceeds to step S41 until the predetermined time has elapsed. Is Step S
Fly to 43 and close solenoid valve 23. Step S within a predetermined time
When the routine proceeds to 41, it is determined from the flag F-FLLO whether or not the fuel tank is full.

This step S41 is the same as step S19 in FIG. 3 in the above embodiment, and the determination of the full state is made by the subroutine in FIG. 4, and the flag F-FLLO is determined. When the tank is not full (F-FLLO = 1)
Proceeding to step S42, the vent solenoid valve 23 is kept open, but when it is full (F-FLLO = 0) step S43.
Then, the solenoid valve 23 is closed.

That is, when the internal combustion engine is stopped with the vent solenoid valve 23 opened, step S is performed until a predetermined time has elapsed.
If it is not full, proceeding to step S42, the vent solenoid valve 23 is kept open, and when a predetermined time has elapsed, the process proceeds from step S40 to step S43 to close the vent solenoid valve 23.

If the fuel tank is full before the predetermined time elapses, the process proceeds from step S41 to step S43 to close the vent solenoid valve 23. Further, if the operation of the internal combustion engine is restarted before the predetermined time has elapsed, the process proceeds from step S31 to step S32 and further to step S36, where the vent solenoid valve is operated.
Close 23.

As described above, when the internal combustion engine is stopped while the vent solenoid valve 23 is open, the solenoid valve 23 is kept open for a predetermined time, so that an increase in the tank internal pressure after the stop is prevented. Even if the filler cap is removed for refueling, the evaporated fuel is not released from the refueling port, and when refueling is performed and the tank is full within a predetermined time, the solenoid valve 23 closes (step 43). The upper space is closed, and the pressure in the fuel tank rises to prevent the subsequent refueling, thereby preventing overcharging, thereby avoiding problems such as fuel leakage from the filler port and the canister or deterioration of the activated carbon of the canister.

[0061]

As described above, according to the present invention, even if refueling is performed when the internal combustion engine is in the operating state, or even if refueling is performed early after shifting from the operating state to the stopped state, the filler When the cap is removed, the vent solenoid valve opens and the pressure inside the fuel tank is reduced, preventing the release of fuel vapor.When refueling is continued and the tank is full, the vent solenoid valve closes to prevent over-fuelling. Is done.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram illustrating an embodiment of an evaporative fuel processing control apparatus for an internal combustion engine according to the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a control flowchart of the electronic control unit of the embodiment.

FIG. 4 is a flowchart of a full tank determination subroutine in the flowchart of FIG. 3;

FIG. 5 is an enlarged sectional view of a main part of another embodiment.

FIG. 6 is a control flowchart in yet another embodiment.

[Explanation of symbols]

1. Intake pipe, 2. Exhaust pipe, 3. Throttle body 4.
Throttle valve, 5 ... fuel injection valve, 6 ... fuel pump, 7 ...
Branch pipe, 8: ignition system, 10: intake pipe internal pressure absolute pressure sensor, 11 ...
Engine speed sensor, 12 ... engine coolant temperature sensor, 13 ... O ₂ sensor, 14 ... throttle valve opening sensor, 15 ... purge detection unit, 16 ... float 17 ... fuel level sensor, 18 ... operation and stop sensors, 19… Vehicle speed sensor, 20… Vent passage, 21…
Two-way valve, 22 ... bypass passage, 23 ... vent solenoid valve, 24 ...
One-way valve, 25 ... Purge passage, 26 ... Purge solenoid valve, 27 ... Vent pipe, 28 ... Two-way valve, 29 ... Negative pressure setting unit, 30 ... Negative pressure pipe, 31 ... Solenoid valve, C: Canister, E: Internal combustion Institutions, EC
O: electronic control unit, T: fuel tank.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shigeki Baba 1-4-1 Chuo, Wako-shi, Saitama Stock Company Honda Research Institute (72) Inventor Kenichi Sawada 1-4-1 Chuo, Wako-shi, Saitama Stock Inside the Honda R & D Co., Ltd. (72) Inventor Shoji Shimaai 1-4-1 Chuo, Wako-shi, Saitama Prefecture Incorporated Honda R & D Co., Ltd. (72) Hideki Kaseyama 1-4-1 Chuo Wako-shi, Saitama Co., Ltd. Inside the Technical Research Institute (72) Inventor Hiroshi Kitagawa 1-4-1 Chuo, Wako-shi, Saitama Pref. Inside the Honda R & D Co., Ltd. (72) Kazumi Yamazaki 1-4-1 Chuo, Wako-shi, Saitama Pref. In-house (56) References JP-A-6-17712 (JP, A) JP-A-2-130254 (JP, A) JP-A-3-222855 (JP, A) 64-4849 (JP, U) Japanese Utility Model 4-24650 (JP, U) Japanese Utility Model 4-119351 (JP, U) Japanese Utility Model 54-45822 (JP, U) Japanese Utility Model Utility Model 55-106357 (JP) , U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02M 25/08 F02M 37/00 301

Claims (3)

(57) [Claims] 1. A two-way valve that opens in a state where the pressure in a fuel tank is equal to or higher than a first set valve opening positive pressure higher than the atmospheric pressure and a state where the pressure in the fuel tank is equal to or lower than a set valve opening negative pressure lower than the atmospheric pressure. A valve is interposed in a vent passage communicating an upper space of the fuel tank with a canister, and an evaporative fuel treatment device having an electromagnetic valve provided in parallel with the two-way valve, wherein the fuel is provided in series with the electromagnetic valve. The pressure in the tank
The second set valve opening positive pressure lower than the first set valve opening positive pressure
A one-way valve that opens in the above pressure state, fuel level detection means for detecting a fuel level in the fuel tank, and in a predetermined operating state of the internal combustion engine, opens the solenoid valve,
An electromagnetic valve control unit that closes the electromagnetic valve when the fuel level is detected by the fuel level detection unit to be higher than a predetermined level. Control device. 2. An evaporative fuel treatment apparatus comprising a vent passage communicating with an upper space of a fuel tank and a canister and a valve for opening and closing the vent passage. When the valve is in the open state when the operation / stop detection means detects the transition from the operation state to the stop state, the open / close state of the valve is maintained, and the transition to the stop state of the internal combustion engine is performed. And evaporative fuel processing control of the internal combustion engine, comprising: valve control means for closing the valve when the operation is restarted within a predetermined time immediately after the operation or when the operation is not restarted within the predetermined time. apparatus. 3. An evaporative fuel treatment apparatus provided with a valve for opening and closing a vent passage in a vent passage connecting an upper space of a fuel tank and a canister, wherein the operation / stop detects whether the internal combustion engine is operating or stopped. Detecting means; fuel level detecting means for detecting a fuel level in the fuel tank; and the valve being in an open state when the operation / stop detection means detects a transition from an operation state to a stop state. Maintaining the open state of the valve, and when the fuel level detecting means detects that the fuel level is equal to or higher than a predetermined height within a predetermined time immediately after the shift of the internal combustion engine to a stop state, or when the predetermined time has elapsed. An evaporative fuel processing control device for an internal combustion engine, comprising: valve control means for closing the valve when the predetermined time has elapsed when the fuel level does not reach a predetermined height.