JP3266058B2 - Abnormality detection device for fuel gas emission suppression device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel gas emission suppressing device for preventing fuel gas (evaporated fuel) generated in a fuel tank from being discharged into the atmosphere, and to an abnormality detection for the device. It concerns the device.

[0002]

2. Description of the Related Art Conventionally, in a vehicle or the like, it is required to install a fuel gas emission suppression device in order to prevent a fuel gas generated in a fuel tank from being discharged into the atmosphere. The fuel gas emission suppression device is configured to adsorb fuel gas to a canister provided in the middle of a purge passage communicating the fuel tank and the intake pipe of the engine as needed, and to open and close the purge control valve according to the operation state of the internal combustion engine. By
The adsorbed fuel gas is appropriately released into the intake pipe. Then, the fuel gas discharged into the intake pipe is mixed into the fuel-air mixture to prevent the fuel from being discharged to the outside.

[0003] In such a fuel gas emission suppression device, usually,
A purge passage is formed by connecting a rubber hose between the canister and the intake pipe. If the rubber hose is damaged or falls off, fuel gas is discharged to the outside (in the atmosphere).
Will leak out. Therefore, as an apparatus for monitoring such leakage (leakage) of fuel gas, for example, Japanese Patent Laid-Open No.
In the "abnormality detection device for a fuel evaporation prevention device" disclosed in -125997, a pressure sensor is attached to a fuel tank, and a fuel gas leak abnormality is determined according to the sensor detection value. More specifically, the space from the fuel tank to the intake pipe of the engine is sealed, and the pressure in the sealed section is adjusted to near atmospheric pressure or a predetermined negative pressure level. Then, an abnormality such as fuel leakage or passage blockage was detected from a pressure change state accompanying the generation of fuel gas in the sealed section at that time.

[0004]

However, when an automobile is traveling on an unpaved rough road, turning, or suddenly stopping, for example, the fuel in the fuel tank shakes, As a result, the pressure change state fluctuates carelessly. For this reason, the occurrence of an abnormality in the fuel gas emission suppression device may be erroneously detected, and there has been a demand for a technique capable of avoiding erroneous detection even in the case of such a fuel swing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an abnormality for a fuel gas emission suppression device capable of accurately detecting an abnormality such as leakage of fuel gas. It is to provide a detection device.

[0006]

In order to achieve the above object, the present invention presupposes that fuel gas generated in a fuel tank is stored in a canister, and the fuel gas stored in the canister is purged together with air through a purge pipe. Pressure control device that is applied to a fuel gas emission suppression device that discharges the fuel gas into the intake passage of the engine through the fuel tank. Means, and abnormality detecting means for detecting abnormality of the fuel gas emission suppression device from a pressure change to a predetermined pressure by the pressure adjusting means.

According to the first aspect of the present invention, when the pressure is adjusted by the pressure adjusting means, the fuel sway in the fuel tank is detected based on an amount of change in pressure in the sealed section per time. The fuel cell system includes a detection unit and an abnormality detection invalidation unit that invalidates the abnormality detection of the fuel gas emission suppression device by the abnormality detection unit when the fuel fluctuation is detected. According to the above configuration, even if the vehicle is running on a rough road, is turning, or suddenly stops, and the pressure change state is inadvertently changed, it is due to fuel swing. Can be recognized. In other words, by invalidating the abnormality detection result at the time of fuel swing, erroneous detection of abnormality can be prevented, and abnormality such as leakage of fuel gas can be accurately detected.

Further, the fuel fluctuation detecting means detects the fuel fluctuation when the pressure in the closed section is a negative pressure. In other words, the degree of generation of fuel gas due to fuel fluctuation increases on the negative pressure side. Therefore, if the fuel sway is detected at the time of the negative pressure, the reliability of the sway detection is improved.

Here, in order to easily detect the presence / absence of a leak and the cause of the leak, it is preferable to configure as in claim 2 . In other words, according to the second aspect of the present invention, when the fuel tank is closed from the fuel tank to the intake passage of the engine, the first predetermined pressure and the second predetermined pressure are switched to adjust to the first predetermined pressure. Comparing the first pressure change state after being performed with the second pressure change state after being adjusted to the second predetermined pressure,
An abnormality of the fuel gas emission suppression device is detected from the comparison result.

According to a third aspect of the present invention, there is provided an opening / closing control valve for adjusting a fuel purge amount from the canister to the engine intake system, and the pressure adjusting means closes the opening / closing control valve so as to close the closed section. The fuel gas emission suppression device according to the first aspect of the invention includes an abnormality detection suspension unit that suspends the abnormality detection of the fuel gas emission suppression device by the abnormality detection unit when the fuel fluctuation continues for a predetermined time or more. In the above configuration, for example, when the vehicle is traveling on a bad road over a long distance, the abnormality detection process is suspended. In this case, the opening / closing operation of the opening / closing control valve is prevented from being repeated more than necessary to set the closed section, and the durability of the control valve is improved.

By the way, when fuel fluctuation occurs in the closed section, the pressure does not change smoothly as when there is no fuel fluctuation. That is, irregular pressure changes occur. Therefore,
According to the fourth aspect of the present invention, the fuel sway detection means
Fluctuation of the fuel in the fuel tank is detected based on the amount of change per unit time of the pressure in the closed section. As a result, the presence / absence of the occurrence of fuel fluctuation can be detected more accurately.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention embodied in a fuel injection control system will be described below with reference to the drawings. In the present embodiment, a fuel gas emission suppression device is mounted on a gasoline engine (internal combustion engine) mounted on a vehicle, and a fuel gas generated in a fuel tank is temporarily adsorbed on a canister of the fuel gas emission suppression device. The adsorbed fuel is discharged to the engine intake system via a purge passage or the like. In addition, the control system is provided with an electronic control unit (hereinafter, referred to as an ECU) that performs fuel injection control, fuel gas purge control, and the like.

FIG. 1 is a configuration diagram showing an outline of a fuel injection control system according to the present embodiment. As shown in FIG. 1, an intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. An air cleaner 4 for filtering air is disposed upstream of the intake pipe 2, and air is sucked into the intake pipe 2 via the air cleaner 4. A throttle valve 5 that opens and closes in conjunction with an accelerator pedal 6 is provided in the intake pipe 2. The sucked air is supplied to the combustion chamber 8 above the piston 10 via the throttle valve 5 and the intake valve 7. Then, the exhaust gas burned in the combustion chamber 8 is discharged to the exhaust pipe 3 via the exhaust valve 9.

On the other hand, a fuel pump 13 is connected to a fuel tank 12 containing liquid fuel (gasoline).
The fuel stored in the fuel tank 12 is supplied to the fuel injection valve 14 while being pressurized by the fuel pump 13, and injected into the intake pipe 2 with the opening operation of the fuel injection valve 14. Supplied. That is, the injected fuel is mixed with the intake air in the combustion chamber 8 and burned.

The fuel tank 12 is connected to a canister 16 through a communication pipe 15. The components described below, including the fuel tank 12 and the communication pipe 15, constitute a fuel gas emission suppression device of the engine. That is, in the fuel gas emission suppression device, an adsorbent 18 made of, for example, activated carbon for adsorbing the fuel gas generated in the fuel tank 12 is accommodated in the canister body 17. With such a configuration as the device, the fuel gas generated in the fuel tank 12 is taken into the canister body 17 through the communication pipe 15 and is adsorbed by the adsorbent 18 in the canister body 17. .

The canister body 17 has an air hole 19 which is open to the atmosphere. Air can pass between the inside of the canister body 17 and the outside through the air hole 19. I have. An electromagnetically driven canister closing valve 20 is provided in the atmosphere hole 19 and can be closed as required. That is, the canister closing valve 20 keeps the air hole 19 open when the coil (not shown) is not energized (off), and closes the air hole 19 when the coil is energized (on). Whether or not the voltage is applied to the canister closing valve 20 is controlled through an ECU 40 described later.

Further, a hose connecting portion 21 is formed in the canister body 17. One end of a purge pipe 22 is attached to the hose connection 21, and the purge pipe 22
The other end is connected to an electromagnetically driven purge control valve 23. The purge control valve 23 is further connected to the intake pipe 2 downstream of the throttle valve 5 via a purge pipe 24.

According to such a structure of the fuel gas emission suppressing device, when the purge control valve 23 is opened, the intake pipe 2 and the canister 16 communicate with each other, and conversely, the control valve 23 is closed. These intake pipes 2
And the canister 16 are closed. Canister 16
And the fuel gas adsorbed by the adsorbent 18 is
In the communication state based on the opening of the purge control valve 23, the air is introduced into the intake pipe 2 based on the negative pressure generated in the intake pipe 2.

In the purge control valve 23, when a coil (not shown) is energized, the opening degree, that is, the purge flow rate is determined according to the energized amount. The power supply to the purge control valve 23 is performed by a pulse signal that is duty-controlled, and the purge flow rate is also determined based on the duty ratio of the pulse signal, for example, as shown in FIG.
In the manner shown in FIG. Such a purge flow duty control is also executed through the ECU 40 described later.

In the fuel gas emission suppressing device, the purge pipes 22 and 24 connected to the purge control valve 23 are formed of a flexible material such as a rubber hose or a nylon hose. The communication pipe 15 connecting the fuel tank 12 and the canister 16 is also partially formed by a rubber hose or the like.

On the other hand, the fuel tank 12 has a relief valve 1 for releasing the pressure in the tank 12 when the pressure exceeds, for example, -40 to 150 hPa.
2a is provided. Therefore, even when a pressure fluctuation occurs in a section from the fuel tank 12 to the canister 16, the fluctuation is always suppressed to be equal to or less than the relief pressure range.

The fuel tank 12 is further provided with a pressure sensor 25 for detecting the pressure in the tank 12. The output of the pressure sensor 25 is used as a monitor signal when adjusting the pressure in the fuel gas emission suppression device. It is sufficient that the pressure sensor 25 has a structure capable of withstanding the above-described relief pressure range. In the apparatus of the embodiment, a differential pressure sensor that detects a differential pressure (relative pressure) between the tank internal pressure and the atmospheric pressure is used as the pressure sensor 25.

In addition, in the same system, as shown in FIG. 1, a throttle sensor 26 for detecting the opening degree of the throttle valve 5, a rotation speed sensor 27 for detecting the rotation speed of the engine 1, and the intake air An intake pipe pressure sensor 28 for detecting the pressure in the pipe 2 is provided. The output of each of these sensors is taken into the ECU 40.

The ECU 40 includes a well-known CPU 41, a ROM 42 in which calculation programs for control and the like and data are stored in advance, and a RAM in which control data and the like are temporarily stored.
An input / output circuit 43 connected to the various sensors and actuators is connected to each other via a common bus 45. In the ECU 40, the fuel injection valve 14 is driven based on the detection signals from the various sensors, and the purge control valve 23 and the canister closing valve 20 are driven to integrally control the fuel injection control, canister purge control, and the like. Execute.

Here, an outline of the present control system by the ECU 40 will be briefly described. That is, the ECU 40 calculates the basic fuel injection amount to the engine 1 based on the output of the rotation speed sensor 27 (rotation speed NE) and the output of the intake pipe pressure sensor 28 (intake pressure PM), and calculates the basic fuel injection amount. Then, various corrections such as air-fuel ratio correction are performed on the fuel injection amount to calculate a final fuel injection amount. Then, the fuel injection valve 14 is driven for a time indicated by the final fuel injection amount in synchronization with the intake stroke of the engine 1.

The ECU 40 also determines the fuel gas concentration (evaporation concentration) in the fuel gas emission suppression device based on, for example, a feedback correction coefficient FAF based on the air-fuel ratio deviation amount.
And the opening degree information of the purge control valve 23 corresponding to the detected fuel gas concentration, that is, the purge flow rate is set. In executing the purge control, the opening degree of the purge control valve 23 is determined with reference to the opening degree information, and the opening degree of the purge control valve 23 is duty-controlled to match the determined opening degree. Further, the opening and closing of the canister closing valve 20 is adjusted in order to control the pressure in the fuel gas emission suppression device (the pressure in the canister 16 and the fuel tank 12) to a predetermined value.

Further, the ECU 40 carries out abnormality detection processing of the fuel gas emission suppression device described in detail below, and in the same processing, the occurrence of abnormality such as fuel gas leakage (leak) in the fuel gas emission suppression device. If is detected,
The abnormality warning lamp 29 is turned on to warn the passenger of the vehicle or the like of the occurrence of the abnormality so as to be notified.

Next, among the various arithmetic processes performed by the CPU 41 in the ECU 40, the abnormality detection process of the fuel gas emission suppression device will be described with reference to the flowcharts of FIGS. 3 to 6 and the time chart of FIG. . FIG.
When the IG key switch (not shown) is turned on, the process of FIG. 4 is repeatedly executed at predetermined time intervals (for example, every 64 milliseconds) together with the fuel injection control process. FIG.
The period shown from time t1 to time t5 in the time chart corresponds to a period for detecting an abnormality such as leakage of the fuel gas of the fuel gas emission suppression device (hereinafter referred to as a leak check period for convenience). However, the tank internal pressure PT shown in FIG. 7 indicates a pressure difference from the atmospheric pressure.

When the process is started, the CPU 41 first determines in step 101 in FIG. 3 whether or not the condition for performing abnormality detection is satisfied. Here, in the present embodiment, it is determined whether or not an abnormality detection suspension flag Fn operated in the processing (leak determination processing) of FIG. 6 described later is “0”. The abnormality detection suspension flag Fn indicates whether to suspend or permit abnormality detection after step 102. Fn = 1 indicates that abnormality detection is suspended, and Fn = 0 indicates that abnormality detection is permitted. . Other conditions for performing the abnormality detection include that the engine water temperature is equal to or higher than a predetermined temperature (for example, 70 ° C.), that the outside air temperature is equal to or higher than a predetermined temperature (for example, −10 ° C.), and that the vehicle is traveling at a constant speed. Conditions such as things may be added.

If a negative determination is made in step 101 (if Fn = 1), the CPU 41 ends this routine. That is, the abnormality detection after step 102 is not performed.

If the determination in step 101 is affirmative (if Fn = 0), the CPU 41 determines in step 10
Proceed to 2. Then, in steps 102 to 104,
It is determined which process has progressed during the leak check period (the period from time t1 to t5 in FIG. 7), and the process branches to each step according to the determination result. In this leak check period, the first flag F1, the second flag F2, and the third flag F
3 is configured so that the processing stage can be determined from each operation state. If all the flags F1 to F3 have been cleared to “0”, that is, if all of steps 102 to 104 are negatively determined, the CPU 41 proceeds to step 105.

When proceeding to step 105, the CPU 41
After the purge control valve 23 is fully closed, the following step 106
To fully close the canister closing valve 20 to seal the section from the fuel tank 12 to the intake pipe 2. In FIG. 7, at time t
By controlling the purge control valve 23 to be fully closed at 1, the section from the fuel tank 12 to the purge control valve 23 is adjusted to the same state as the atmospheric pressure via the atmosphere hole 19. At a slightly later time t2, the canister closing valve 23 is controlled to be fully closed, thereby forming a closed section adjusted to the atmospheric pressure.

Subsequently, the CPU 41 fetches the input signal from the pressure sensor 25 in step 107 and stores the tank internal pressure “P1 ′” immediately after the sealing, and the ECU 40
The built-in timer T is reset and started. Also, CPU
In step 108, it is determined whether or not a predetermined time (10 seconds in the present embodiment) has elapsed after the start of the timer T in step 107.

If 10 seconds have not elapsed, the CPU 41 sets "1" to the first flag F1 in step 109, and once ends the routine. In FIG. 7, the first flag F1 is set at the time t2, and thereafter, the step 102 is performed.
Is determined to be affirmative, and steps 101 → 102 → 108 → 1
The processing is performed in the order of 09. During this time, the pressure sensor 25
The detected value of “0 hP” depends on the amount of fuel gas generated in the fuel tank 12 as shown at times t2 to t3 in FIG.
a ”gradually increases.

When 10 seconds have elapsed from time t2, the CPU
41 affirmatively determines in step 108 and proceeds to step 110 in FIG. 4 to fetch the input signal from the pressure sensor 25 and store the tank internal pressure “P1” at this time,
In the following step 111, the pressure change amount ΔP1 for 10 seconds after sealing (hereinafter, referred to as atmospheric pressure change amount) ΔP1 is calculated as ΔP1 = P1 ″ −P1 ′.
Clears the first flag F1 to "0" (at time t in FIG. 7).
3).

Thereafter, the CPU 41 switches the purge control valve 23 from the fully closed state to the fully open state in step 113 and resets and starts the timer T. Purge control valve 2
At this time t3 when 3 is switched to the fully open state, the intake pipe negative pressure is introduced into the closed section under the previous positive pressure state. Therefore, if there is no abnormality due to blockage in the purge passage portion, the detection value (tank pressure PT) of the pressure sensor 25 starts to decrease.

Further, the CPU 41 determines in step 114 the tank internal pressure P based on the input signal from the pressure sensor 25.
T is a predetermined negative pressure level (−20 hP in the present embodiment).
a) It is determined whether or not the following has occurred. PT> -20hP
a (a period from time t3 to t4 in FIG. 7)
The CPU 41 makes a negative determination in step 114 and proceeds to step 115. Then, the CPU 41 determines in step 115
After the start of the timer T in the step 113,
That is, it is determined whether or not a predetermined time (two seconds in the present embodiment) has elapsed after time t3 in FIG.

If two seconds have not elapsed, the CPU 41 sets "1" to the second flag F2 in step 116. Thus, this time, the step 102 of FIG. 3 is determined to be negative, and the step 103 is determined to be positive.
The processing is repeatedly executed in the order of steps 101 to 103 → 114 → 115.

If two seconds or more have passed since time t3 while the state in which step 114 is negatively determined (PT> −20 hPa) continues, the CPU 41 proceeds to step 117 with an affirmative determination. . CP
U41 sets "1" to the purge system closing flag Fclose, which means that there is a blockage somewhere in the purge system from the fuel tank 12 to the intake pipe 2 in step 117, and turns on the abnormality warning lamp 29. .

That is, if no abnormality such as blockage of the purge system has occurred, the tank internal pressure PT is reduced to a predetermined negative pressure level (−20 hPa) before the elapse of 2 seconds within the period from time t3 to t4.
However, if an abnormality such as blockage of the purge system has occurred, the tank internal pressure PT does not decrease to the predetermined negative pressure level even after the elapse of 2 seconds, and the occurrence of a purge system blockage abnormality is detected. Will be.

On the other hand, if the determination in step 114 is affirmative, the CPU 41 determines in step 118 that the second flag F2
Is reset to "0", and in step 119, the purge control valve 23 is controlled to be fully closed again. Further, the CPU 41
Takes in the input signal from the pressure sensor 25 in step 120, stores the tank internal pressure “P2 ′” immediately after the closed section is set to the negative pressure sealed state, and resets and starts the timer T built in the ECU 40. This timing is shown in FIG.
At time t4.

In short, at time t4 in FIG. 7, the closed section is adjusted to a negative pressure of -20 hPa, and thereafter, at time t4.
During the period from 4 to t5, the tank internal pressure PT is
It gradually increases from -20 hPa in accordance with the amount of fuel gas generated in the furnace.

Next, in step 121, after the timer T is started in step 120 in step 121, that is, after time t4 in FIG. 7, a predetermined time (in this embodiment,
(10 seconds) has elapsed. If 10 seconds have not elapsed, the CPU 41 determines in step 122 that the third flag F
3 is set to "1", and in the following step 200, a fuel swing detection process is performed. The details of the fuel fluctuation detection process performed during the period from time t4 to time t5 will be described later with reference to the flowchart of FIG. Thus, this time, Steps 102 and 103 in FIG. 3 are negatively determined and Step 104 is affirmatively determined.
The processing is repeatedly executed in the order of 104 → 121 → 122 → 200.

When 10 seconds have passed since time t4, the CPU
41 is affirmatively determined in step 121 and step 123
Proceed to. The CPU 41 determines in step 123 that the pressure sensor 2
5 and stores the tank internal pressure “P2” ”at time t5, and in a subsequent step 124, a pressure change amount (hereinafter, referred to as“ the pressure change amount ”) for 10 seconds after sealing under negative pressure.
ΔP2) is calculated as ΔP2 = P2 ″ −P2 ′.

The CPU 41 performs a leak determination process in step 300, and thereafter terminates this routine once. The details of the leak determination process performed at time t5 in FIG. 7 will be described later with reference to the flowchart in FIG.

Next, the subroutine of the fuel swing detection process executed in step 200 of FIG. 4 will be described with reference to FIG.
This will be described with reference to the flowchart of FIG. As described above, this fuel fluctuation detection processing is performed during the period from time t4 to time t5 in FIG. 7, that is, during the period when both the purge control valve 23 and the canister closing valve 20 are fully closed and the tank internal pressure PT is under the negative pressure state. Is repeatedly executed.

When the processing of FIG. 5 is started, the CPU 41
First, in step 201, the tank internal pressure PT corresponding to the input signal from the pressure sensor 25 is read. The read tank internal pressure PT may be an average value. next,
The CPU 41 determines in step 202 that the tank internal pressure change amount dP
Calculate T. In this process, the tank internal pressure change amount dPT is calculated as dPT = PT (i) -PT (i-1). Here, i indicates the number of times of sampling.

Thereafter, in step 203, the CPU 41 calculates the amount of change in the tank internal pressure change amount dPT (hereinafter referred to as twice change amount d∧2PT for convenience). In this process, the amount of change d∧2PT is calculated twice as d∧2PT = dPT (i) −dPT (i−1).

Further, in step 204, the CPU 41 stores the maximum value of the two-time change d ス テ ッ プ 2PT up to that time as a “sway estimation value”. In short, time t4 to t5 in FIG.
In the period, the change amount of the tank pressure PT twice d∧2
PT is sequentially obtained, and the maximum value is updated each time as a swing estimation value. At this time, the twice change amount d∧2PT of the tank internal pressure PT is calculated and stored as data reflecting the degree of fuel sway in the fuel tank 12.

Next, the subroutine of the leak determination process performed in step 300 of FIG. 4 will be described with reference to the flowchart of FIG. This leak determination processing is executed at time t5 in FIG. 7 as described above.

When the processing of FIG. 6 is started, the CPU 41
First, in step 301, it is determined whether or not there is a leak based on a predetermined leak determination condition. Specifically, when ΔP2> α · ΔP1 + β holds, it is determined that “leakage has occurred”. Here, α is a coefficient for correcting a difference in fuel evaporation amount due to a difference between atmospheric pressure and negative pressure, and β is a coefficient for correcting pressure sensor accuracy, leakage of the canister closing valve 20, and the like.

That is, if there is a leak cause in the closed section from the fuel tank 12 to the purge control valve 23, the outflow from the closed section to the atmosphere occurs under the positive pressure state, while the leak occurs from the atmosphere under the negative pressure state. A spill to a closed section occurs. Therefore, the “negative pressure change amount ΔP2” is larger than the “atmospheric pressure change amount ΔP1”. Here, the amount of change in atmospheric pressure ΔP1 corresponds to “the amount of fuel gas generated in the fuel tank 12−the amount of outflow from the closed section to the atmosphere”. The amount of change in negative pressure ΔP2 corresponds to “the fuel tank 12 Of the fuel gas + the amount of fuel gas flowing into the closed section. From this, the inequality leak determination condition is derived.

If the inequality leak determination condition is not satisfied, that is, if the determination in step 301 is negative, C
The PU 41 proceeds to step 302, forcibly clears the first to third flags F1 to F3, and then returns to the original abnormality detection processing (the processing in FIGS. 3 and 4).

On the other hand, if the above inequality leak determination condition is satisfied, that is, if step 301 is affirmatively determined, the CPU 41 proceeds to step 303, where the "estimated swing value" of the fuel in the tank obtained in the processing of FIG. Is greater than or equal to a predetermined determination value Ks. Here, the estimated swing value <Ks means that the swing of the fuel in the fuel tank 12 is small and the result of the determination in step 301 is valid, and the estimated swing value ≧ Ks is This means that the swing is large and the result of the determination in step 301 is invalid.

Therefore, if a negative determination is made in step 303 (when the estimated swing value <Ks), the CPU 41 proceeds to step 304, in which a part of the purge system from the fuel tank 12 to the intake pipe 2 causes a leak. Is set to "1" for the purge system leak flag Fleak, which means that there is an alarm, and the abnormality warning lamp 29 is turned on.

If a negative determination is made in step 303 (when the estimated swing value ≧ Ks), the CPU 41 proceeds to step 3
Proceeding to step 05, the satisfaction of the leak determination condition in step 301 is considered to be due to fuel swing, and the result of the leak determination is canceled. Thereafter, the CPU 41 increments the counter CL by “1” in step 306. Then, on condition that the counter CL has reached the predetermined value KC (YES in step 307), the CPU 41 sets “1” in the abnormality detection suspension flag Fn in step 308, and thereafter, returns to the original abnormality detection processing (FIG. Return to (3, 4).

The reason why the abnormality detection suspension flag Fn is set based on the value of the counter CL is to prevent unnecessary leak check from being repeated when fuel fluctuations are prolonged. And the number of times of opening and closing operations of the purge control valve 23 is reduced.
23 has improved durability. However, the abnormality detection suspension flag Fn is reset to “0” after a lapse of a predetermined time (for example, about one hour) after being set, and the abnormality detection processing is restarted.

FIG. 8 is a time chart showing the generation of fuel gas and the state of fuel fluctuation when the closed section from the fuel tank 12 to the purge control valve 23 is under a negative pressure.
The time t4 to t5 in FIG.
This corresponds to t5 (a period during which the third flag F3 is set).

In FIG. 7, when there is no fuel fluctuation in the fuel tank 12, the tank internal pressure PT increases in a predetermined quadratic curve. At this time, if the fuel gas does not leak from the closed section, the tank internal pressure PT changes according to the amount of generated fuel gas and rises by ΔP2 as shown by the solid line, and the fuel gas leaks from the closed section. Then, as shown by the dashed line, the tank internal pressure PT increases by ΔP2 ′. Therefore, from the relationship of ΔP2 ′> ΔP2, it can be specified that the transition of the one-dot chain line is due to fuel gas leakage.

On the other hand, as shown by a two-dot chain line in the figure, when the fuel sway in the fuel tank 12 occurs, a large amount of fuel gas is temporarily generated, and the tank internal pressure PT
Rises with pulsation. When fuel gas is generated due to the fuel swing, the negative pressure change amount ΔP2 increases even if there is no leak, and it is not possible to determine the presence or absence of the leak only by the factor of ΔP2. Therefore, the twice change amount d∧2PT of the tank internal pressure PT
, The occurrence of fuel fluctuation is detected, and when the fuel fluctuation is detected, the leak determination result is invalidated.

According to the above-described processing, in the fuel gas emission suppressing device, the purge control valve 2
If a leak or blockage has occurred in the section up to 3, it can always be accurately detected. Further, this abnormality detection can be performed irrespective of the mounting position of the pressure sensor 25.

In the present embodiment, FIGS.
The opening / closing control of the purge control valve 23 and the canister closing valve 20 by the above corresponds to the pressure adjusting means described in the claims, and step 300 in FIG. 4 (the processing in FIG. 6) corresponds to the abnormality detecting means.
Step 200 in FIG. 4 (process in FIG. 5) corresponds to the fuel fluctuation detecting means, steps 303 and 305 in FIG. 6 correspond to the abnormality detection invalidating means, and steps 306 to 308 in FIG. I do.

According to the embodiment described above, the following specific effects can be obtained. (A) In this embodiment, the fuel tank 12 is connected to the intake pipe 2
At the time of sealing up to, the fluctuation of the fuel in the fuel tank 12 is detected from the amount of change per hour of the pressure in the sealed section,
When the fuel fluctuation is detected, the abnormality detection result of the fuel gas emission suppression device is invalidated. According to the above configuration,
Even if the vehicle is running on a rough road, turning, or suddenly stopping, and the pressure change state is inadvertently changed, it can be recognized that the change is due to fuel sway. In other words, by invalidating the abnormality detection result at the time of fuel swing, erroneous detection of abnormality can be prevented, and abnormality such as leakage of fuel gas can be accurately detected.

FIG. 9 is a diagram for confirming the effect of the present embodiment. In FIG. 9, the vertical axis indicates the fluctuation estimation value, and the horizontal axis indicates “ΔP2−ΔP1” corresponding to the pressure change state. ΔP2-ΔP1> about 6 hPa (area on the shaded side in the figure)
Is an abnormality determination area in which the presence of a leak should be detected. In the same figure, "・" indicates data when there is a leak of φ1 mm and there is no fuel fluctuation. "X" indicates data when there is a leak of φ1 mm and there is fuel fluctuation. Data: ・ The “△, ▲” marks show data when there is no leak and there is fuel fluctuation, respectively.

Therefore, when performing the above-described conventional abnormality detection that does not detect the fuel fluctuation, the data marked with “▲” is leaked in the same manner as the data marked with “○, ×” despite the data without leak. The presence is detected. On the other hand, in the apparatus according to the present embodiment, data in which the fluctuation estimated value exceeds the predetermined determination value Ks is invalidated, so that only the data marked with “○” is valid, and the data leaked with “▲” False detection can be prevented. However, the data marked with “x” is φ1 mm
Even if there is a leak, the abnormal data is temporarily invalidated due to the fuel swing, and it is determined that there is a leak after the fuel swing has subsided.

(B) In the present embodiment, the twice change amount d∧2PT of the tank internal pressure PT is used as the estimated value of the fuel fluctuation.
(Differential value twice) was used. Therefore, the detection of the fuel swing can be accurately performed.

(C) When the pressure in the sealed section from the fuel tank 12 to the intake pipe 2 is a negative pressure, that is, a fuel swing is detected from time t4 to t5 in FIG. Therefore, the fuel fluctuation can be detected in an area where fuel gas is likely to be generated due to the fuel fluctuation, and the reliability of the detection result is improved.

(D) At the time of sealing from the fuel tank 12 to the intake pipe 2, the atmospheric pressure (first predetermined pressure) and -20 hP
a (second predetermined pressure), and an abnormality such as a leak was detected from the comparison result of the pressure change state at each pressure. In such a case, if there is a cause of the leak, the leak speed changes according to the difference in the relative pressure difference from the atmospheric pressure when adjusting each pressure. Therefore, according to the difference between the two pressure change states, the presence or absence of a leak and the cause of the leak can be easily detected.

(E) When the fuel fluctuation continues for a predetermined time or more, the abnormality detection is temporarily stopped. In the above configuration, for example, when the vehicle is traveling on a bad road over a long distance, the abnormality detection process is suspended. In this case, the opening and closing operation of the purge control valve 23 and the canister closing valve 20 for setting the closed section is suppressed from being repeated more than necessary, and each of the valves 23 and 2 is suppressed.
0 durability is improved.

(F) It is possible to detect the fuel fluctuation in the fuel tank 12 by providing a fuel level meter and performing the measurement based on the measurement result. However, such a configuration leads to an increase in the cost of the system. Also, there is a problem that the detection accuracy of the fuel fluctuation is not sufficient. On the other hand, according to the configuration of the present embodiment, it is possible to accurately detect the fuel fluctuation without increasing the cost of the system.

(G) In the conventional device, for example, the abnormality detection of the fuel gas emission suppression device is performed only when the vehicle speed is "0" and during the idling operation, and when there is a possibility of fuel fluctuation, the abnormality is detected. Detection was not performed. However, the device according to the present embodiment sequentially detects the fuel swing,
Since the detection result can be reflected in the abnormality detection, abnormal traveling becomes possible even while the vehicle is traveling.

The embodiment of the present invention can be realized in the following modes other than the above. In the above-described embodiment, the maximum value of the twice change amount d∧2PT of the tank internal pressure PT is sequentially updated during the period from the time t4 to the time t5 in FIG. 7 upon detecting the fuel fluctuation (step 204 in FIG. 5). At time t5
Finally, at the timing of, it was determined whether there was fuel sway,
This configuration may be changed. Each time the twice change amount d∧2PT of the tank pressure PT is calculated, it is compared with a predetermined determination value, and d∧2
When the PT value exceeds the determination value, it is determined that the fuel has swayed, and an abnormality is detected in the closed section setting (leak check) at that time.
May not be performed.

In the above embodiment, the tank internal pressure PT
Although the fuel sway is detected based on the rotation change amount d∧2PT, this configuration may be changed. For example, tank pressure PT
Even if the fuel swing is detected based on the variation dPT (= PT (i) -PT (i-1)), the spirit of the present invention is not deviated.

In the above-described embodiment, when the pressure in the sealed section from the fuel tank 12 to the intake pipe 2 is negative, that is, during the time t4 to t5 in FIG. 7, the fuel swing is detected. May be changed. For example, at time t in FIG.
The fuel swing may be detected in the period of 2 to t3. In short, the fuel swing may be detected when the closed section is set.

In the above-described embodiment, the process of suspending the abnormality detection is performed (steps 306 to 308 in FIG. 6).
This processing may be deleted. In the above embodiment, FIG.
Also, in the abnormality detection process performed in the flowchart of FIG. 4, the pressure change state near the atmospheric pressure is measured, and then the pressure change state at the negative pressure is measured. However, the order may be reversed.

The time of pressure adjustment in the abnormality detection processing (time t2 to t3, t3 to t4, t4 to t5 in FIG. 7)
Is not limited to the above-mentioned time, but may be appropriately changed and embodied according to the engine specifications and the like.

In the above-described embodiment, the pressure sensor 25 as the pressure detecting means is provided in the fuel tank 12. However, for example, the pressure sensor 25 may be provided in a section between the canister 16 and the intake pipe 2. . Also in this case, it is possible to make a leak determination for the entire closed section based on the pressure change state after forming the closed section.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a fuel injection control system according to an embodiment of the invention.

FIG. 2 is a graph showing a duty driving mode of a purge control valve.

FIG. 3 is a flowchart illustrating an abnormality detection process.

FIG. 4 is a flowchart showing an abnormality detection process following FIG. 3;

FIG. 5 is a flowchart illustrating a fuel swing detection process.

FIG. 6 is a flowchart illustrating a leak determination process.

FIG. 7 is a time chart for explaining an execution process of the abnormality detection processing.

FIG. 8 is a time chart for explaining a pressure change state at the time of fuel swing.

FIG. 9 is a graph illustrating an effect of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 2 ... Intake pipe, 12 ... Fuel tank, 15 ... Communication pipe, 16 ... Canister, 20 ... Canister closing valve as open / close control valve, 22, 24 ... Purge piping, 23 ... Open / close control valve Purge control valve, 24 ... purge pipe, 25 ... pressure sensor, 40 ... ECU (electronic control unit), 41 ... pressure adjusting means, abnormality detection means, fuel fluctuation detection means, abnormality detection invalidating means, abnormality detection pausing means CPU that constitutes.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-61164 (JP, A) JP-A-5-125997 (JP, A) JP-A 8-296509 (JP, A) JP-A-6-296 235384 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02M 25/08 F02B 77/08

Claims (4)

(57) [Claims] 1. A fuel gas emission suppression device which stores fuel gas generated in a fuel tank in a canister and discharges the fuel gas stored in the canister together with air to an intake passage of an engine via a purge pipe. A pressure adjusting means for sealing the space from the fuel tank to the intake passage of the engine, and adjusting the pressure in the sealed section to a predetermined pressure; and An abnormality detection device comprising: an abnormality detection unit configured to detect an abnormality of the discharge suppression device.When sealing is performed by the pressure adjustment unit, the fuel in the fuel tank is determined based on an amount of change in pressure in the sealed section per unit time. Fuel sway detection means for detecting the sway of fuel; and an abnormality detection means for invalidating the abnormality detection of the fuel gas emission suppression device by the abnormality detection means when the fuel sway is detected. And a disabling means output, said fuel swing detection means, the pressure in the closed space is a negative pressure
Abnormality detection apparatus for a fuel gas emission control system characterized that you detect the fuel swing when going on to. 2. The engine according to claim 1, wherein said fuel tank is connected to an intake passage of an engine.
During sealing, the first predetermined pressure and the second predetermined pressure are cut off.
Alternatively, the first pressure after being adjusted to the first predetermined pressure
The change state and the second pressure after being adjusted to the second predetermined pressure.
Force change state, and based on the comparison result, the fuel gas
2. The fuel gauze according to claim 1, wherein an abnormality of the emission suppression device is detected.
Anomaly detection device for emission control device. 3. A fuel passage from said canister to an engine intake system.
An opening / closing control valve for adjusting the amount of charging,
Regulating means closes the on-off control valve to form the closed section
When the fuel sway continues for a predetermined time or more in the fuel gas emission suppression device, the abnormality is detected.
Stop the abnormality detection of the fuel gas emission suppression device by means
3. An abnormality detection suspending means according to claim 1 or 2.
Abnormality detection device for on-board fuel gas emission suppression device. 4. The apparatus according to claim 1, wherein the fuel sway detecting means is provided in the closed section.
Of the fuel based on the amount of change in the pressure
4. A fuel tank according to claim 1, wherein said fuel tank detects a fuel sway.
The fuel gas emission suppression device according to any one of
Anomaly detection device .