JP2741699B2 - Evaporative fuel processor for internal combustion engines - 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 apparatus for an internal combustion engine, and more particularly to an evaporative fuel processing apparatus for an internal combustion engine for detecting an abnormality of valves provided in an evaporative fuel emission control system.

[0002]

2. Description of the Related Art Conventionally, a canister provided with a fuel tank and an intake port, a first control valve interposed in a fuel vapor flow passage connecting the canister and the fuel tank, 2. Description of the Related Art An evaporative fuel processing apparatus for an internal combustion engine including an evaporative fuel discharge suppression system including a second control valve disposed in a purge passage connecting the intake system of the internal combustion engine and the purge passage is widely known.

In this type of apparatus, the evaporated fuel is temporarily stored in a canister, and the stored evaporated fuel is discharged (purged) into an intake system of an engine.

Further, as a method for determining an abnormality of the fuel vapor treatment apparatus, the fuel vapor suppression system is forcibly set to a predetermined negative pressure state, and the tank internal pressure changes with time from the setting of the negative pressure state. A method for determining whether or not there is an abnormality by measuring a target change has already been proposed by the present applicant (Japanese Patent Application No. 3-262857).

In this prior application, a third control valve for controlling the opening and closing of the intake port is provided near the intake port of the canister, and the third control valve is closed while the engine is operating. The first and second control valves are opened to forcibly reduce the evaporative fuel emission suppression system to a predetermined negative pressure state, and then the second control valve is closed to place the fuel tank in a proper position. The pressure fluctuation of the fuel tank is measured by a tank pressure sensor provided in the fuel tank, and it is determined whether or not the fuel vapor leaks from the fuel vapor emission suppression system based on the pressure fluctuation of the fuel tank pressure (leakdown check). An abnormality in the fuel processor is determined.

[0006]

However, in order to more accurately diagnose the abnormality of the fuel vapor processing apparatus, the fuel vapor evaporator is required.
Before depressurizing the discharge suppression system, it is desirable to measure the amount of change in the tank internal pressure from the time when the fuel tank was opened to the atmosphere, and to determine an abnormality based on the amount of change in the tank internal pressure and the amount of change in the tank internal pressure at the time of leak-down check. That is, when "perforation" or the like occurs in the fuel tank, the evaporative fuel emission suppression system cannot be sufficiently reduced in pressure. Therefore, even if a leak-down check is performed in such a state, an accurate abnormality diagnosis is performed. Can not do. Further, when a large amount of fuel vapor is generated in the fuel tank, the pressure fluctuation at the time of the leak down check becomes large. That is, since a large amount of fuel vapor is generated in the fuel tank, the pressure fluctuation at the time of the leak-down check becomes large, and there is a possibility that the apparatus is determined to be in an abnormal state, and accurate abnormality diagnosis cannot be performed. Therefore, as described above, it is preferable to determine the abnormality based on the amount of fluctuation in the tank internal pressure from the time of opening to the atmosphere and the amount of fluctuation in the tank internal pressure during the leak-down check.

However, in the above-described abnormality determination method, since the first control valve is closed and the amount of change in the tank internal pressure is detected, if the first control valve is out of order, the correctness is obtained. However, there is a problem that it is not possible to perform an abnormal diagnosis.

In other words, if the first control valve is in a malfunctioning state in the closed state, the amount of fluctuation in the tank internal pressure of the fuel tank during the leak down check cannot be detected. There is a possibility that it will be in a state.

If the first control valve is open and malfunctions, the amount of fluctuation in the tank internal pressure from the time of opening to the atmosphere cannot be detected, and accurate abnormality diagnosis cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and detects an abnormality in valves provided in an evaporative fuel discharge suppression system quickly to prevent over-negative pressure in the evaporative fuel discharge control system. It is another object of the present invention to provide an evaporative fuel processing apparatus for an internal combustion engine that can minimize erroneous determination of abnormality diagnosis of the evaporative fuel emission suppression system.

[0011]

In order to achieve the above object, the present invention provides a fuel tank, a canister provided with an intake port, and a fuel vapor flow passage connecting the canister and the fuel tank. Fuel processing for an internal combustion engine provided with a first control valve provided and a second control valve interposed in a purge passage connecting the canister and an intake system of the internal combustion engine. An operating state detecting means for detecting an operating state of the engine; a third control valve for opening and closing the intake port of the canister; a tank internal pressure detecting means for detecting an internal pressure of the fuel tank; And controlling the third control valve to control the evaporation fuel
Decompression processing means for setting the discharge suppression system to a predetermined negative pressure state; and controlling the first to third control valves to control the evaporation fuel discharge.
An abnormality diagnosis processing system comprising a stop system as a closed system and pressure fluctuation detection means for detecting pressure fluctuation from the predetermined negative pressure state, wherein the operation state of the engine is detected by the operation state detection means. And abnormality determining means for determining whether or not the first control valve is abnormal based on the tank internal pressure detected by the tank internal pressure detecting means when the second control valve is set to the open state. It is characterized by having.

Further, the present invention is characterized in that the abnormality judging means is configured to detect the tank internal pressure when the third control valve is set to a closed state and a valve closing signal is issued to the first control valve. And an abnormality detecting means for detecting an abnormality of the first control valve when the tank internal pressure detected by the controller becomes equal to or less than a predetermined value. If the tank internal pressure detected by the tank internal pressure detecting means becomes greater than or equal to a predetermined value when the valve is set to the open state and a valve open signal is issued to the first control valve, the first Is provided with abnormality detecting means for detecting abnormality of the control valve.

Further, the present invention is characterized in that it has a prohibiting means for prohibiting the execution of the abnormality diagnosis processing by the abnormality diagnosis processing system when the abnormality of the first control valve is detected.

[0014]

According to the above construction, whether the first control valve is abnormal is determined based on the detected value of the tank internal pressure when the operating state of the engine is detected and the second control valve is set to the open state. Is determined.

More specifically, if the tank internal pressure falls below a predetermined value when the third control valve is set to the closed state and a valve closing signal is issued to the first control valve, Alternatively, the third control valve is set to the open state and the first control valve is opened.
When the tank internal pressure detected by the tank internal pressure detecting means becomes equal to or higher than a predetermined value while a valve opening signal is issued to the control valve, an abnormality of the first control valve is detected.

Further, when an abnormality of the first control valve is detected, execution of the abnormality diagnosis processing by the abnormality diagnosis processing system is prohibited.

[0017]

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

FIG. 1 is an overall configuration diagram showing an embodiment of a fuel vapor processing apparatus for an internal combustion engine according to the present invention.

In FIG. 1, reference numeral 1 denotes an internal combustion engine having, for example, four cylinders (hereinafter simply referred to as "engine"). A throttle body 3 is provided in the middle of an intake pipe 2 of the engine 1. A throttle valve 3 'is provided. The throttle valve 3 'has a throttle valve opening (θ
A TH) sensor 4 is connected, and outputs an electric signal corresponding to the opening of the throttle valve 3 ′ and supplies it to an electronic control unit (hereinafter referred to as “ECU”) 5.

The fuel injection valve 6 is provided for each cylinder in the middle of 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 pump 8 via a fuel supply pipe 7 and electrically connected to the ECU 5.
5 controls the valve opening timing of the fuel injection.

Downstream of the throttle valve 3 'of the intake pipe 2, a negative pressure communication path 9 and a purge pipe 10 are provided in a branched manner, respectively. The negative pressure communication path 9 and the purge pipe 10 are connected to an evaporative fuel discharge suppression system 11 described later. It is connected to the.

Further, a branch pipe 12 is provided on the downstream side of the purge pipe 10 from the intake pipe 2, and an absolute pressure (PBA) sensor 13 is provided at a tip of the branch pipe 12. Also,
The PBA sensor 13 is electrically connected to the ECU 5,
Absolute pressure PB in intake pipe 2 detected by A sensor 13
A is converted into an electric signal and supplied to the ECU 5.

An intake air temperature (TA) sensor 14 is mounted on the intake pipe 2 downstream of the branch pipe 12.
The intake air temperature TA detected by the ECU 4 is converted into an electric signal and supplied to the ECU 5.

An engine coolant temperature (TW) sensor 15 composed of a thermistor or the like is inserted into the cylinder peripheral wall of the cylinder block of the engine 1 filled with coolant, and the engine coolant temperature TW detected by the TW sensor 15 is converted into an electric signal. The converted data is supplied to the ECU 5.

An engine speed (NE) sensor 16 is provided around a camshaft or a crankshaft (not shown) of the engine 1.
Is attached.

The NE sensor 16 outputs a signal pulse (hereinafter referred to as a “TDC signal pulse”) at a predetermined crank angle position every time the crankshaft of the engine 1 rotates by 180 degrees, and the TDC signal pulse is supplied to the ECU 5. .

An ignition switch (IGSW) sensor 17 is an IG indicating that the engine 1 is operating.
The ON state of the SW is detected and the electric signal is supplied to the ECU 5.

Thus, the evaporative fuel emission suppression system (hereinafter referred to as
The “emission control system” 11 includes a fuel tank 19 having a filler cap 18 that is opened at the time of fuel supply, an activated carbon 20 as an adsorbent, and an intake port (outside air intake) 21 at the top. A canister 22 provided;
A fuel vapor flow passage 23 connecting the canister 22 to the fuel tank 19; a first control valve 24 interposed in the fuel vapor flow passage 23; and a purge pipe 10 connected to the canister 22 Purge control valve 25 interposed in the road
(Second control valve).

The fuel tank 19 is connected to the fuel injection valve 6 via the fuel pump 8 and the fuel supply pipe 7, and a tank internal pressure (PT) sensor 26 is provided above the fuel tank. Further, the PT sensor 26 is electrically connected to the ECU 5, and the PT sensor 26 detects the tank internal pressure (PT) of the fuel tank 19 and supplies an electric signal to the ECU 5.

The first control valve 24 includes a positive pressure valve 27
And a two-way valve 29 composed of a negative pressure valve 28 and a first solenoid valve 30 integrally provided with the two-way valve 29. That is, the tip of the rod 30a of the first solenoid valve 30 is abutted against the diaphragm 27a of the positive pressure valve 27, and the first control valve 24 is formed by integrating the two-way valve 29 and the first solenoid valve 30. Be done. Further, the first electromagnetic valve 30 is electrically connected to the ECU 5, and the operation state of the first electromagnetic valve 30 is controlled by a signal from the ECU 5. Then, when the first solenoid valve 30 is excited (turned on), the positive pressure valve 27 of the two-way valve 29 is forcibly pushed open and the first control valve 24 is opened, while the first solenoid valve is opened. When 30 is demagnetized (off), the first control valve 24 is a two-way valve 2
9 controls the opening / closing operation.

The solenoid of the purge control valve 25 is E
The purge control valve 25 is connected to the CU 5 and is controlled according to a signal from the ECU 5 to linearly change the valve opening amount. That is, the ECU 5 outputs a desired control amount to control the opening amount of the purge control valve 25.

A drain shut valve 31 is interposed in the negative pressure communication passage 9 connected to the intake port 21 of the canister 22, and a second solenoid valve 32 is interposed downstream of the drain shut valve 31. The drain control valve 31 and the second solenoid valve 32 constitute a third control valve 33.

The drain shut valve 31 is defined through a diaphragm 34 into an atmosphere chamber 35 and a negative pressure chamber 36. Further, the atmosphere chamber 35 includes a first chamber 37 having a valve body 37a therein and a second chamber 3 having an atmosphere inlet 38a.
8 and a constricted portion 39 connecting the second chamber 38 and the first chamber 37. The valve body 37 a is connected to the diaphragm 34 via a rod 40. The negative pressure chamber 36
Is seated with a spring 41 which is communicated with the second solenoid valve 32 and resiliently urges in the direction of arrow A.

When the solenoid of the second solenoid valve 32 is demagnetized (turned off), air can be introduced into the negative pressure chamber 36 through the air supply port 42, and the solenoid is excited (turned on). Sometimes, it is possible to communicate with the intake pipe 2 through the negative pressure communication passage 9. Reference numeral 43 denotes a check valve.

Thus, the ECU 5 has an input circuit having a function of shaping the input signal waveforms from the various sensors described above, correcting the voltage level to a predetermined level, converting an analog signal value to a digital signal value, and the like. A central processing unit (hereinafter referred to as a “CPU”), storage means for storing an operation program executed by the CPU, operation results, and the like; the fuel injection valve 6, the first and second solenoid valves 30 and 32, and a purge And an output circuit that supplies a drive signal to the control valve 25.

Further, the ECU 5 (CPU) controls the first to third control valves 24, 25, and 33 to control the emission suppression system 1
Pressure reducing means for setting the pressure control valve 1 to a predetermined negative pressure state, and controlling the first to third control valves 24, 25, 33 to control the discharge control system 11
And a pressure fluctuation detecting means for detecting a pressure fluctuation from the predetermined negative pressure state. The pressure reducing processing means, the pressure fluctuation detecting means, the PT sensor 26, and I
The GSW sensor 17, the third control valve 33, and the like constitute an abnormality diagnosis processing system.

FIG. 2 shows the valves, ie, the first and second solenoid valves 30 and 32, the drain shut valve 31, and the purge control valve 25 when the abnormality diagnosis processing system diagnoses the abnormality of the emission suppression system 11. FIG. 7 is a diagram showing an operation pattern of FIG. 7 and a change state of the tank internal pressure PT at that time, and this operation pattern is executed by a signal from the ECU 5 (CPU).

First, during normal operation (normal purge mode) (shown in FIG. 2), the first solenoid valve 30 is turned on, the second solenoid valve 32 is turned off, and the IGSW Is turned on and the operation of the engine is detected by the IGSW sensor 17, the purge control valve 25 is turned on and opened. Then, the evaporated fuel generated in the fuel tank 19 flows into the canister 22 through the fuel vapor flow passage 23, and is temporarily absorbed and stored by the adsorbent 20 of the canister 22. As described above, during the normal operation, the second solenoid valve 32 is off, so that the drain shut valve 31 is opened, and the outside air is supplied to the canister 22 from the air inlet 38a, and the fuel vapor flowing into the canister 22 Is purged into the purge pipe 10 via the second control valve 25 together with the outside air. When the fuel tank 19 is cooled by the influence of the outside air and the negative pressure in the fuel tank 19 increases,
The negative pressure valve 28 of the two-way valve 24 opens, and the canister 2
2 is returned to the fuel tank 19.

When the engine 1 satisfies the predetermined abnormality diagnosis permission condition, the first and second solenoid valves 3
0, 32 and the purge control valve 25 operate as follows to diagnose the abnormality of the emission suppression system 11.

First, the tank internal pressure PT is released to the atmosphere (shown in FIG. 2). That is, the first solenoid valve 30 is maintained in the on state to bring the fuel tank 19 into communication with the canister 22, and the second solenoid valve 32 is maintained in the off state to maintain the open state of the drain shut valve 31. Is maintained, and the purge control valve 25 is maintained in the open state (on state) to release the tank internal pressure PT to the atmosphere.

Next, the fluctuation amount of the tank internal pressure is measured (shown in FIG. 2).

That is, the second solenoid valve 32 is kept off, the drain shut valve 31 is kept open, and the purge control valve 25 is kept open, while the first solenoid valve 30 is kept open. Is turned off, the amount of change in the tank internal pressure from the time of opening to the atmosphere is measured, and the amount of steam generated in the fuel tank 19 is checked.

Next, the pressure of the discharge suppression system 11 is reduced (FIG. 2,
). That is, while the first solenoid valve 32 is switched on and the purge control valve 25 is kept open,
The second solenoid valve 32 is turned on, the drain shut valve 31 is closed, and the exhaust suppression system 11 is brought into a predetermined negative pressure state by the suction force from the intake pipe 2 generated through the purge pipe 10.

Next, a leak down check is performed (shown in FIG. 2).

That is, when the discharge suppression system 11 is brought into a predetermined negative pressure state, the purge control valve 25 is closed and the PT sensor 26
To check the change state of the tank internal pressure PT. When there is no leak from the discharge suppression system 11, the change in the tank internal pressure PT hardly occurs and the discharge suppression system 1
1 is determined to be normal. On the other hand, when fuel vapor is leaking from the emission suppression system 11, the tank internal pressure approaches the atmospheric pressure as shown by the solid line. In such a case, in consideration of the fluctuation amount of the tank internal pressure measured above, it is determined whether fuel vapor is leaking from the emission suppression system 11, that is, whether abnormality is occurring in the emission suppression system 11. judge.

After the end of the abnormality determination, the routine shifts to the normal purge (shown in FIG. 2).

That is, while the first solenoid valve 35 is maintained in the on state, the second solenoid valve 39 is turned off, and the purge control valve 36 is switched to the open state to perform normal purging.
At this time, the tank internal pressure PT is open to the atmosphere, and is substantially equal to the atmospheric pressure.

Thus, the ECU 5 (CPU) of this embodiment
Is provided with abnormality detecting means for detecting abnormality of each valve such as the drain shut valve 31 (second electromagnetic valve 32), the purge control valve 25, and the first electromagnetic valve 30.

FIGS. 3 to 5 are flowcharts of an abnormality detection routine for detecting an abnormality of each of the valves, and this program is executed in the background.

In FIG. 3, in step S1, it is determined whether or not the PT sensor 26 is abnormal. The abnormality determination of the PT sensor 26 is determined based on the output fluctuation amount between the previous value and the current value of the PT sensor 26, and specifically, is determined based on a PT sensor abnormality determination routine (not shown). If the answer is affirmative (YES), that is, if the PT sensor 26 is determined to be abnormal, the first solenoid valve 30 is turned off, the purge control valve 25 is closed, and the second
The electromagnetic valve 32 is turned off to open the drain shut valve 31 (step S2), and then the flag FMON is set to "0" to stop the abnormality diagnosis of the emission suppression system 11 (step S3). finish. That is, since the abnormality diagnosis of the emission suppression system 11 is determined based on the output value of the PT sensor 26, the abnormality diagnosis of the emission suppression system 11 is stopped when the PT sensor 26 is abnormal.

On the other hand, when the answer to step S1 is negative (NO), it is determined whether or not the flag FMON is "1", and it is determined whether or not the emission suppression system 11 is under abnormality diagnosis. Here, the abnormality diagnosis is performed based on the intake pipe absolute pressure (PBA), the intake air temperature (T
A), is executed when various engine parameters such as the engine cooling water temperature TW and the engine speed NE satisfy predetermined conditions. In other words, when an abnormality diagnosis permission routine (not shown) is executed and the various engine parameters satisfy predetermined conditions, the flag FMON is set to “1”,
An abnormality diagnosis of the emission suppression system 11 is performed. When the answer to step S4 is negative (NO), that is, when the abnormality diagnosis is not being performed, the process proceeds to step S5, and the flag FFS is set to "1".
To determine whether or not the valve is in an abnormality determination mode.

If the answer is negative (NO), the first solenoid valve 30 is turned on, the purge control valve 25 and the drain shut valve 31 are opened, and the valves are set to the normal purge mode. (Step S6) The flag FFS is set to "1" to set the valve abnormality determination mode.
Is reset to "0" (step S8), and this program ends.

Next, in the next loop, since the flag FFS has already been set to "1" in step S7, the answer in step S5 is affirmative (YES), and in step S9, the tank internal pressure PT (by the PT sensor 26). (Detected) is equal to or less than a predetermined value PT1. here,
As the predetermined value PT1, for example, a value on the further negative pressure side (for example,
-40 mmHg). If the answer is negative (NO), the program is terminated, while if the answer is affirmative (YES), it is determined whether the first timer tmDSV has passed a predetermined time T1 (for example, 5 seconds). (Step S10). And the answer is negative (N
If the answer is affirmative (YES), it is detected that the drain shut valve 31 is closed and malfunctioning. That is, if the tank internal pressure PT falls to the pressure reducing side to a predetermined value or more in this loop even though the drain shut valve 31 is set to the open state in the previous loop, the electric system of the second solenoid valve 32 Is short-circuited, it is determined that a malfunction has occurred in the drain shut valve 31 in the closed state, and the third control valve 33
To detect abnormalities.

Thus, as described above, the drain shut valve 3
If it is determined that an operation failure has occurred in the valve 1 in the valve closed state, the process proceeds to step S12 (FIG. 4), the flag FMON is set to "0" to stop the execution of the abnormality diagnosis processing in the next loop, and the purge control is performed. A purge signal is issued to the solenoid of the valve 25 to close the purge control valve 25. That is, when the drain shut valve 31 is in a closed state and an operation failure occurs, the purge control valve 25 is closed to prevent the discharge suppression system 11 from being over-negative.

Next, in step S14, it is determined whether or not the tank internal pressure PT has decreased to a reduced pressure side by a predetermined value (for example, 10 mmHg). When the answer is negative (NO), the second timer tmP is set to "0". "(Step S1
5) While ending this program, if the answer to step S14 is affirmative (YES) in the subsequent loop, the process proceeds to step S16, where the second timer tmP sets the predetermined time T2.
(For example, 5 seconds) is determined. If the answer is negative (NO), the program is terminated. On the other hand, if the answer is affirmative (YES), the solenoid of the purge control valve 25 is issued a valve closing signal (step S13). ), Since the canister 22 and the intake pipe 2 of the engine 1 are not shut off, it is determined that the exhaust suppression system 11 has been depressurized, the solenoid of the purge control valve 25 is short-circuited, and the purge control valve 25 operates in the open state. Detect that a defect has occurred.

On the other hand, if the answer to step S4 (FIG. 3) is affirmative (YES), the flag FFS is set to "0" to stop the abnormality determination of the valves (step S18), and the leak down check is being performed (step S18). 2) is determined (step S19). If the answer is negative (NO), the program is terminated as it is, while if the answer is affirmative (YES), the process proceeds to step S20, where the tank internal pressure PT is reduced to a predetermined value (for example, 10 mmHg) or more. It is determined whether or not it has fallen. And the answer is negative (N
When the answer is affirmative (YES), step S16 (FIG. 4).
Proceeds to the second timer tmP for a predetermined time T2 (for example,
5 sec), it is determined whether or not it has elapsed, and the answer is affirmative (Y
In the case of ES), similarly to the above, it is detected that the purge control valve 25 is in an open state and malfunctions.

When the abnormality of the purge control valve 25 is detected as described above, the process proceeds to step S21.
It is determined whether or not the flag FMON is "1". If the answer is negative (NO), that is, S4 → S5 → S9 ... →
When the abnormality of the purge control valve 25 is detected through the flow from S14 to S16, the process proceeds to step S24, in which the first solenoid valve 30 is turned off, and the control of the first control valve 24 is performed by 2 steps.
It is left to the directional valve 29 to prevent the fuel tank 19 from becoming over-negative.

On the other hand, if the answer in step S21 is affirmative (YE
S), that is, S4 → S18 → S19 → S20 → S16
When an abnormality of the purge control valve 25 is detected after passing through the flow, the "ON command" signal to the purge control valve 25 is cut off, and the second solenoid valve 32 is turned on to close the drain shut valve 31. After the valve is opened (step S22), the flag FM
When ON is set to "0", the abnormality diagnosis of the emission suppression system 11 is stopped (step S23), and then an off signal is issued to the first solenoid valve 30 in order to prevent excessive negative pressure in the fuel tank 19 (step S24). And after this, it progresses to step S25,
It is determined whether or not the tank internal pressure PT has decreased to a reduced pressure side by a predetermined value (for example, 10 mmHg) or more.
In the case of O), the third timer tmWY1 is reset to "0" (step S25) and the program is terminated. On the other hand, when the answer is affirmative (YES), the third timer tmWY1 is reset for a predetermined time. T3 (for example, 5 seconds)
It is determined whether or not the time has elapsed (step S27). When the answer is negative (NO), the program is terminated, while when the answer is affirmative (YES), it is detected that the first control valve 24 is open and malfunctions (step S1). S28) This program ends.

That is, the answer to step S27 is affirmative (Y
ES) occurs when the tank internal pressure PT fluctuates to the reduced pressure side even though the first solenoid valve 30 has issued an off signal. That is, when the first solenoid valve 30 is off, the control of the first control valve 24 is entrusted to the two-way valve 29. Usually, the first control valve 24 is opened. Therefore, the tank internal pressure does not fluctuate to the reduced pressure side. Accordingly, in such a case, when the tank internal pressure falls to the pressure reducing side, the electric system of the first solenoid valve 30 is short-circuited and the first solenoid valve 30 is in the ON state, so that the first control valve 24 is in the open state. And the first control valve 24
To detect abnormalities.

By executing the above-described abnormality detection routine, the third control valve 33 (the drain shut valve 3
1, the second solenoid valve 32), the purge control valve 25, and the first control valve 24 (the first solenoid valve 30) can be sequentially detected for abnormality, and when the discharge suppression system 11 is in an over-negative pressure state. Can be avoided.

In the abnormality detection routine,
An example in which the same software is used to detect the abnormality of the valves has been described. After setting the drain shut valve 31 to the closed state and setting the purge control valve 25 to the open state, the first solenoid valve 30 is turned off. To detect an abnormality of the first control valve 24. In this case, when the abnormality of the first control valve 24 is detected, the drain shut valve 31 is opened to prohibit the abnormality diagnosis processing, so that the over-negative pressure of the canister 22 and the fuel tank 19 can be prevented. .

FIG. 6 is a flowchart of an abnormality detection routine when the first control valve 24 is closed and has a failure, and this program is executed in the background. That is, the drain shut valve 31 and the purge control valve 25 are opened, and an ON command is issued to the first solenoid valve (step S31).
It is determined whether it is greater than 1 (step S32). Here, the predetermined value P1 is the positive pressure valve 2 of the two-way valve 29.
7 is set to a value lower than the set pressure, for example, +5 mmHg. If the answer is negative (NO), the fourth timer tmWY2 is reset to "0" (step S).
33) While ending this program, if the answer to step S32 is affirmative (YES) in a subsequent loop, it is determined whether or not the fourth timer has elapsed a predetermined time T4 (for example, 5 seconds). If the answer is affirmative (YES), it is determined that the first control valve 24 is in a closed state and has failed due to the disconnection of the electric system of the first solenoid valve 30, and the flag FM
By setting ON to "0", the abnormality diagnosis processing of the evaporative fuel emission suppression system 11 is prohibited (step S35), and this program ends.

As described above, according to the present embodiment, even if the first control valve 24 fails in either the open state or the closed state, the abnormality is quickly detected to prevent the discharge suppression system from being damaged. In addition, erroneous determination can be prevented in the abnormality diagnosis.

[0064]

As described above in detail, the present invention relates to a fuel tank, a canister provided with an intake port, and a first fuel vapor flow passage interposed between the canister and the fuel tank. An evaporative fuel processing apparatus for an internal combustion engine, comprising: a control valve; and a second control valve interposed in a purge passage connecting the canister and an intake system of the internal combustion engine. Operating state detecting means for detecting an operating state; a third control valve for opening and closing the intake port of the canister; tank internal pressure detecting means for detecting an internal pressure of the fuel tank; and the first to third controls A pressure reducing means for controlling a valve to bring the evaporative fuel discharge suppression system into a predetermined negative pressure state; controlling the first to third control valves to make the evaporative fuel discharge suppression system a closed system; Negative pressure condition It has an abnormality diagnosis processing system comprising a pressure fluctuation detecting means for detecting a pressure fluctuation of al, the operating state of the engine by the operation state detection means is detected and the second
When the control valve is set to the open state, the first control valve includes abnormality determination means for determining whether or not the first control valve is abnormal based on the tank internal pressure detected by the tank internal pressure detection means. The operating condition of the engine is detected and the second
It is determined whether the first control valve is abnormal based on the detected value of the tank internal pressure when the control valve is set to the open state.

More specifically, when the third control valve is set to the closed state and the first control valve is issued a valve closing signal, the abnormality determining means determines that the tank internal pressure has been detected. When the tank internal pressure detected by the above becomes lower than a predetermined value, the abnormality detecting means for detecting the abnormality of the first control valve is provided. Even at this time, the abnormality of the first control valve can be quickly detected, and the abnormality determining means sets the third control valve to the open state and opens the first control valve. When the tank internal pressure detected by the tank internal pressure detecting means is greater than or equal to a predetermined value while the valve signal is being issued, the abnormality detecting means for detecting an abnormality of the first control valve is provided. Even when the first control valve is closed and malfunctions It can be departing quickly detect the first control valve abnormalities.

Further, when an abnormality of the first control valve is detected, there is provided a prohibition means for prohibiting execution of the abnormality diagnosis processing by the abnormality diagnosis processing system. In this case, too much negative pressure of the canister can be avoided, and erroneous determination of abnormality diagnosis of the evaporative fuel emission suppression system can be prevented.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing operation patterns of first and second solenoid valves, a drain shut valve, and a purge control valve.

FIG. 3 is a flowchart (1/3) showing an embodiment of the abnormality detecting means of the present invention.

FIG. 4 is a flowchart (2/3) showing an embodiment of the abnormality detecting means of the present invention.

FIG. 5 is a flowchart (3/3) showing an embodiment of the abnormality detecting means of the present invention.

FIG. 6 is a flowchart showing a second embodiment of the abnormality detecting means of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Intake pipe 5 ECU (pressure reduction processing means, pressure fluctuation detection means, abnormality detection means, prohibition means) 10 Purge pipe 11 Evaporation fuel emission suppression system 19 Fuel tank 21 Intake port 22 Canister 23 Fuel vapor flow passage 24 First Control valve 25 purge control valve (second control valve) 26 PT sensor (tank pressure detecting means) 33 third control valve

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masayoshi Yamanaka 1-4-1 Chuo, Wako-shi, Saitama Pref. Honda Technical Research Institute Co., Ltd. (56) References JP-A-1-142258 (JP, A) JP-A Hei 3-26862 (JP, A) JP-A-2-130255 (JP, A)

Claims (4)

(57) [Claims] 1. A fuel tank, a canister provided with an intake port, a first control valve interposed in a fuel vapor flow passage connecting the canister and the fuel tank, and a canister and an internal combustion engine. Operating state detecting means for detecting an operating state of an engine in an evaporative fuel processing apparatus for an internal combustion engine having an evaporative fuel discharge suppression system including a second control valve interposed in a purge passage connecting to an intake system; A third control valve for opening and closing the intake port of the canister;
Tank internal pressure detecting means for detecting the internal pressure of the fuel tank; and controlling the first to third control valves to control the fuel vapor pressure.
Decompression processing means for setting the discharge suppression system to a predetermined negative pressure state; and controlling the first to third control valves to control the evaporation fuel discharge.
An abnormality diagnosis processing system including a stop system that is a closed system and pressure fluctuation detection means for detecting pressure fluctuation from the predetermined negative pressure state, wherein the operation state of the engine is detected by the operation state detection means; And an abnormality determining means for determining whether or not the first control valve is abnormal based on the tank internal pressure detected by the tank internal pressure detecting means when the second control valve is set to the open state. An evaporative fuel treatment device for an internal combustion engine, comprising: 2. The abnormality judging means is detected by the tank internal pressure detecting means when a third control valve is set to a closed state and a valve closing signal is issued to the first control valve. 2. An apparatus according to claim 1, further comprising abnormality detecting means for detecting an abnormality of said first control valve when the internal pressure of said tank becomes equal to or lower than a predetermined value. 3. The abnormality determination means is detected by the tank internal pressure detection means when a third control valve is set to an open state and an open signal is issued to the first control valve. 2. An evaporative fuel processing apparatus for an internal combustion engine according to claim 1, further comprising an abnormality detecting means for detecting an abnormality of said first control valve when the tank internal pressure exceeds a predetermined value. 4. The apparatus according to claim 1, further comprising a prohibition unit for prohibiting execution of the abnormality diagnosis processing by the abnormality diagnosis processing system when an abnormality of the first control valve is detected.
An evaporative fuel processing apparatus for an internal combustion engine according to any one of claims 1 to 3.