JP3321943B2 - Abnormality detection device for fuel evaporation prevention mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality detecting device for a fuel evaporation prevention mechanism for detecting an abnormality such as leakage of fuel gas in a fuel evaporation prevention mechanism for preventing the evaporation of fuel gas generated in a fuel tank. is there.

[0002]

2. Description of the Related Art Conventionally, in vehicles and the like, it is required to provide a fuel evaporation prevention mechanism in order to prevent a fuel gas generated in a fuel tank from being released into the atmosphere. This fuel evaporation prevention mechanism adsorbs the fuel gas as needed by an adsorbent of a canister disposed in the middle of a purge passage communicating the fuel tank and the intake pipe, and operates a purge control valve according to the operation state of the internal combustion engine. By opening and closing,
This is a mechanism for preventing the evaporation of the fuel by appropriately introducing the adsorbed fuel gas into the intake pipe and mixing it into the fuel mixture.

In such a fuel evaporation prevention mechanism, a purge passage is usually formed by connecting the canister and the intake pipe with a rubber hose. If the rubber hose is bent and crushed, the fuel gas is not introduced into the intake pipe, exceeds the fuel gas adsorption capacity of the adsorbent in the canister, and the fuel gas is released from the air holes.
Further, the rubber hose may be damaged due to corrosion or the like because it is in contact with the alcohol component, and if the air hole of the canister is clogged with dust or the like, the rubber hose may come off due to an increase in pressure. Also in this case, the fuel gas is released to the atmosphere.

A prior art document related to an abnormality detection device for a fuel evaporation prevention mechanism for detecting the occurrence of such a situation is disclosed in Japanese Patent Laid-Open No. 5-125997.

In this apparatus, when a negative pressure is introduced from the intake pipe to adjust the pressure, the purge control valve is fully opened, and a standby is performed until a predetermined pressure is reached. Discloses a technique for performing abnormality detection of a fuel evaporation prevention mechanism by closing a purge control valve and adjusting the pressure in a closed section.

[0006]

Since the space volume in the fuel tank changes depending on the amount of fuel in the fuel tank, the space volume including the space in the fuel tank changes from the purge control valve. When the amount of fuel in the fuel tank is large, the space volume is small, and the pressure of the space volume further decreases even if the purge control valve is closed because the introduction speed of the negative pressure through the purge control valve is high and the purge control valve is closed. As a result, the amount of pressure drop is large, and as a result, the negative pressure in the closed section becomes too large, which may lead to damage to the fuel evaporation prevention mechanism.

Further, the pressure change in the sealed section immediately after the sealing, that is, since the pressure change in the sealed section is detected for a predetermined time from when the negative pressure is introduced to the sealed section to reach the predetermined pressure and the purge control valve is closed, the pressure change is reduced. The variation in the amount results in a detection error of the amount of change in the pressure, and as a result, there is a possibility that the malfunction of the abnormality detection of the fuel evaporation prevention mechanism is caused.

Further, when the amount of fuel in the fuel tank is small, the volume of the space becomes large and the time until the predetermined pressure is reached after the introduction of the negative pressure becomes long. Further, even when a leak occurs when the fuel amount in the fuel tank is large and the space volume is small, the time required for the pressure in the sealed section to reach the predetermined pressure after the introduction of the negative pressure becomes long. That is, there is no leak (normal state) when the fuel amount in the fuel tank is small and the space volume is large (normal state), and the length of time until the predetermined pressure is reached after the introduction of the negative pressure, and the fuel volume in the fuel tank is large and the space volume is small. It is difficult to determine the normal / abnormal condition based on the length of time until the predetermined pressure is reached after the introduction of the negative pressure due to the occurrence of a leak (abnormal condition), which may eventually lead to a malfunction of the abnormality detection of the fuel evaporation prevention mechanism. was there.

Accordingly, the present invention has been made to solve such a problem, and provides an abnormality detection device for a fuel evaporation prevention mechanism which improves pressure adjustment accuracy in a closed section and prevents erroneous detection at the time of abnormality detection. Is an issue.

[0010]

According to a first aspect of the present invention, there is provided an abnormality detecting apparatus for a fuel evaporation prevention mechanism, as shown in FIG. 9, in a purge passage communicating a fuel tank with an intake pipe of an internal combustion engine. By adsorbing the fuel gas generated in the fuel tank at any time by an adsorbent of a canister provided in the canister, and opening and closing a purge control valve according to the operation state of the internal combustion engine, the adsorbed fuel gas is sucked into the intake air. A fuel evaporation prevention mechanism which is appropriately introduced into the pipe to prevent fuel evaporation, a pressure detection means G11 for detecting a pressure state in the fuel evaporation prevention mechanism, and an air hole closing means for closing an air hole provided in the canister G12 and the sealing means G, which closes both the purge control valve and the air hole closing means G12 to make the whole fuel evaporation prevention mechanism one closed section.
13, an intake pipe pressure detecting means G14 for detecting a pressure state in the intake pipe, a fuel amount detecting means G15 for detecting a fuel amount in the fuel tank, and the intake air detected by the intake pipe pressure detecting means G14. The opening degree of the purge control valve is controlled in accordance with the pressure state in the pipe and the amount of fuel in the fuel tank detected by the fuel amount detection means G15 to change the speed of introducing the negative pressure from the intake pipe to thereby close the closed pipe. Sealed section pressure adjusting means G1 for adjusting the section pressure to a predetermined pressure
6, and a pressure change for measuring a predetermined pressure change state based on the pressure state in the fuel evaporation prevention mechanism detected by the pressure detection means G11 at the time of pressure adjustment by the closed section pressure adjustment means G16 or after the pressure adjustment. It comprises a state measuring means G17 and an abnormality detecting means G18 for detecting an abnormality of the fuel evaporation prevention mechanism from the predetermined pressure change state measured by the pressure change state measuring means G17.

According to a second aspect of the present invention, there is provided an abnormality detecting device for a fuel evaporation preventing mechanism,
The closed section pressure adjusting means introduces a negative pressure into the closed section to adjust the pressure in the closed section to a predetermined pressure, and thereafter the purge control valve and the air hole closing means are closed. The pressure is adjusted to a predetermined pressure.

According to a third aspect of the present invention, there is provided an abnormality detecting device for a fuel evaporation preventing mechanism,
The space volume of the closed section is calculated based on the fuel amount in the fuel tank detected by the fuel amount detecting means.

According to a fourth aspect of the present invention, there is provided an abnormality detecting device for a fuel evaporation preventing mechanism,
The abnormality detecting means is executed in an operating state in which the amount of change in the fuel amount in the fuel tank detected by the fuel amount detecting means is small.

[0014]

According to the present invention, the closed section pressure adjusting means controls the opening of the purge control valve in accordance with the pressure state in the intake pipe and the amount of fuel in the fuel tank to reduce the negative pressure introduction speed from the intake pipe. Since the pressure is changed and the pressure in the closed section is adjusted, the pressure is switched to a target, for example, a first predetermined pressure and a second predetermined pressure, and the pressure is adjusted very accurately. Then, the first pressure change state after being adjusted to the first predetermined pressure and the second pressure change state after being adjusted to the second predetermined pressure are measured by the pressure change state measurement means. You. The first pressure change state and the second pressure change state are compared by abnormality detection means, and abnormality of the fuel evaporation prevention mechanism is detected.

According to a second aspect of the present invention, in the closed section pressure adjusting means of the abnormality detection device for a fuel evaporation prevention mechanism, in addition to the function of the first aspect, the order of adjusting the predetermined pressure in the closed section is first executed by introducing the negative pressure. It is set as follows.

According to a third aspect of the present invention, in addition to the operation of the first aspect, the abnormality detection device for a fuel evaporation prevention mechanism is configured to calculate a space volume of a closed section based on an amount of fuel in a fuel tank.

According to the fourth aspect of the present invention, the abnormality detecting means of the abnormality detecting device for a fuel evaporation preventing mechanism is executed in an operation state in which the amount of change in the amount of fuel in the fuel tank is small in addition to the function of the first aspect.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments.

FIG. 1 is a schematic configuration diagram showing an abnormality detection device for a fuel evaporation prevention mechanism according to an embodiment of the present invention.

In FIG. 1, air sucked through an air cleaner 1 for filtering air is supplied to an intake pipe 2 connected to the air cleaner 1. A throttle valve 8 that opens and closes in conjunction with an accelerator pedal 6 is provided in the intake pipe 2. The intake pipe 2 is connected to a piston 12 and a cylinder head 14 of the internal combustion engine 3 through an intake valve 10.
And a combustion chamber 16 formed by Further, the combustion chamber 16 is connected to an exhaust pipe 20 via an exhaust valve 18.

On the other hand, a fuel pump 24 which pressurizes and supplies the liquid fuel stored in the fuel tank 22 and an injector (fuel injection valve) 26 provided in the intake pipe 2 are connected.
The opening and closing of the injector 26 is controlled to inject fuel. The communication pipe 28 connected to the fuel tank 22 is connected to the canister 30. Activated carbon, for example, is accommodated in the canister body 32 as an adsorbent 34 for adsorbing fuel gas. Thereby, the canister 30 can adsorb the fuel gas generated in the fuel tank 22 through the communication pipe 28. The canister main body 32 is formed with an atmospheric hole 36 that is open to the atmosphere, so that air can be sucked into the inside. The air hole 36 is provided with a canister closing valve 37 for closing the opening if necessary.

As shown in FIG. 2, the canister closing valve 37 applies a predetermined voltage (for example, 8 V or more) to the coil 3.
When the voltage is applied to the coil 37a, the coil 37a is excited to move the valve body 37b against the urging force of the spring 37c to open the conduit 37d. When a predetermined voltage is not applied to the coil 37a, the valve body 37b is opened. 37b is spring 3
An electromagnetic on-off valve which is urged by 7c and closes a conduit 37d communicating with the air hole 36 of the canister body 32.

Further, one end of the supply pipe 38 is inserted into the hose connection portion 32a of the canister body 32 and connected to the canister 30, and the other end of the supply pipe 38 is connected to the purge control valve 40. One end of a supply pipe 42 is connected to the purge control valve 40, and the other end of the supply pipe 42 is connected to the intake pipe 2. Supply pipe 3 used here
Numerals 8 and 42 have flexibility, such as rubber hoses and nylon hoses, and are formed entirely. Also, the fuel tank 2
The communication pipe 28 connecting the canister 2 and the canister 30 is also partially formed of a rubber hose or the like.

The fuel supply tank 22 is connected to both the supply pipes 38 and 42 and the communication pipe 28 connected to the purge control valve 40.
A purge passage from the intake pipe 2 to the intake pipe 2 is formed. The purge control valve 40 is interposed between the two supply pipes 38 and 42 for switching the intake pipe 2 and the canister 30 to be in communication or non-communication. The purge control valve 40 is provided in accordance with an input signal. 42 is configured to be connected and disconnected.

As shown in FIG. 3, the purge control valve 40 includes a canister-side port 40a to which the supply pipe 38 is connected.
An intake pipe side port 40b to which the supply pipe 42 is connected;
A valve 40d for opening and closing the passage 40c between the ports 40a and 40b in the middle, a spring 40e for urging the valve 40d in the valve closing direction, and opening the valve 40d against the urging force of the spring 40e. The solenoid valve includes a coil 40f that moves in the valve direction to perform purging. The coil 4
A voltage is applied to 0f by a pulse signal. By continuously changing the ratio (duty ratio) of the pulse width to the cycle of the pulse signal, the ratio of the time in which the valve body 40d is in the open position to the opening / closing cycle of the valve body 40d is changed. The purge flow rate of the fuel gas into the fuel cell can be controlled. Here, the purge flow rate is affected by the pressure of the front and rear ports 40a and 40b of the purge control valve 40, and the pressure of one of the canister-side ports 40a can use the atmospheric pressure. , And the output signal is input to the electronic control circuit 50. Also, the other intake pipe side port 40b
Is detected by an intake pipe pressure sensor (not shown), and its output signal is input to the electronic control circuit 50.

FIG. 4 shows the relationship between the purge control valve drive duty ratio (%) and the purge flow rate when the differential pressure (atmospheric pressure-intake pipe pressure) between the front and rear ports 40a and 40b of the purge control valve 40 is constant (450 mmHg). FIG. 4 is a characteristic diagram illustrating a relationship. FIG. 5 is a characteristic diagram showing the relationship between the purge control valve front and rear port differential pressure (mmHg) and the purge flow rate when the purge control valve drive duty ratio is constant (100%).

The fuel tank 22 is provided with a pressure sensor 44 for detecting the tank internal pressure PT and a well-known float type fuel gauge 23 for detecting the amount of fuel in the tank.
Further, the fuel tank 22 is provided with a relief valve 22a for releasing the pressure when the internal pressure exceeds -40 mmHg to 150 mmHg. Therefore, the fuel tank 2
The section from 2 to the canister 30 is always suppressed to a pressure fluctuation within this relief pressure range. Therefore, it is sufficient to adopt a pressure sensor having a structure that can withstand the relief pressure range.

The injector 26, the canister closing valve 37, the purge control valve 40 and the pressure sensor 4
4 are connected to the electronic control circuit 50, respectively. The electronic control circuit 50 includes a well-known CPU 52, a ROM 54 for storing a control program, a map, and the like in advance, a RAM 56 for storing various data, and an input / output circuit 58, which are connected to one another via a common bus 60. The input / output circuit 58 is also connected to various operating state detecting means such as a pressure sensor 62 for detecting the pressure in the intake pipe, a rotational speed sensor 64 for detecting the rotational speed of the internal combustion engine 3, and a vehicle speed sensor 66. The CPU 52 controls the signals input from the operating state detecting means via the input / output circuit 58 and the ROM 54, RA
Based on the control programs and various data stored in the M56, the injector 26, the canister closing valve 3
7. A drive signal is output to the purge control valve 40 and the like via the input / output circuit 58. In this way, the electronic control circuit 50 executes the fuel injection control, the canister purge control, the abnormality detection control for the fuel evaporation prevention mechanism, and the like.

Next, the processing procedure of the CPU 52 of the electronic control circuit 50 used in the abnormality detection device for the fuel evaporation prevention mechanism according to one embodiment of the present invention will be described with reference to the flowcharts of FIGS. This will be described with reference to a timing chart.

The abnormality detection control routine for the fuel evaporation prevention mechanism shown in FIGS. 6 and 7 is repeatedly executed every predetermined time (for example, 256 ms) together with the fuel injection control processing after the ignition switch (not shown) is turned on. .

First, in step S101, it is determined whether or not the accumulated purge execution time after the start has passed a predetermined time. When the determination in step S101 does not hold,
It is determined that the purging of the adsorbent 34 for adsorbing the fuel gas in the canister 30 is insufficient, and this program is ended without doing anything. That is, in the determination process of step S101, if the abnormality detection control is executed when the purge is insufficient, the fuel becomes excessive when the fuel gas is supplied to the internal combustion engine 3 through the purge control valve 40 in a large amount, and the exhaust gas is exhausted. Not only does the gas deteriorate, but the internal combustion engine 3 may malfunction and stop, so that the abnormality detection control waits until the purge is sufficiently executed.

On the other hand, when the determination in step S101 is satisfied, the process proceeds to step S102, and it is determined whether the normal / abnormal determination in this abnormality detection routine has been completed. Here, the abnormality detection control for preventing fuel evaporation requires a predetermined time, and during that time, the purge of the canister 30 cannot be performed. Therefore, once the normal / abnormal judgment has been completed once the ignition switch is turned on,
Until the internal combustion engine 3 stops, the abnormality detection control is not executed again. That is, when the determination in step S102 is established, the program is terminated without doing anything.

If the normal / abnormal judgment is not completed in step S102, the process proceeds to step S103, in which the amount of change in fuel in the fuel tank 22 is calculated based on the output signal of the fuel gauge 23, and the amount of change is determined to be a predetermined value. It is determined whether or not: Here, during running on a rough road, sudden turning, rapid acceleration / deceleration, or the like, the fuel pressure in the fuel tank 22 may fluctuate or fluctuate, causing the tank internal pressure PT to fluctuate greatly, making it impossible to make a correct determination in the following steps. Such fuel fluctuations and deviations are detected as changes in the amount of fuel by the float fuel gauge 23. When the fuel change amount exceeds the predetermined value and the determination in step S103 is not established, the process proceeds to step S131 described later.

If the determination in step S103 is satisfied, that is, if the operation state is such that the purging of the canister 30 is sufficient and the normal / abnormal determination has not been completed, and the change amount of the fuel amount in the tank is determined to be small, , To which stage the process has progressed is determined in steps S104 to S10.
The process branches to various steps while making the determination at step 8.

There are four processes, a first stage to a fourth stage.
As shown in the timing chart of FIG. 8, in the first stage, the canister closing valve 37 is closed and the purge control valve 40 is closed.
These are the times T1 to T3 from when the negative pressure is introduced from the intake pipe 2 to the closed section until the pressure becomes constant. The second stage is a time T3 to T4 when the purge control valve 40 is closed and the sealed section is closed to detect a change state of the tank internal pressure. The third stage is a time T4 to T5 when the canister closing valve 37 is opened to introduce the atmosphere into the closed section and bring the pressure in the closed section into equilibrium with the atmosphere. In the fourth stage, the canister closing valve 37 is closed again to close the sealed section, and the change state of the tank internal pressure due to the generation of fuel gas is detected at times T5 to T6.
It is.

It is configured to be able to determine which of the above-described first to fourth steps is in accordance with the setting states of the flags F1 to F5. The first stage is when all the flags F1 to F5 are set to "0", and the process proceeds to step S109. In the first stage, first, the canister closing valve 37 is fully closed, and the drive of the purge control valve 40 is set in advance based on the fuel amount in the tank and the differential pressure across the purge control valve 40 (atmospheric pressure-intake pipe pressure). The drive of the purge control valve 40 is started at the duty ratio, and the timer T built in the electronic control circuit 50 is reset (T = 0) and started.
The flag F1 is set (F1 ← 1). That is, here, the canister closing valve 37 is fully closed, the purge control valve 40 is driven, and the introduction of negative pressure into the closed section is started (FIG. 8).
At time T1).

Subsequently, the flow shifts to step S110, where it is determined whether or not the tank internal pressure PT is less than a predetermined value KPT1. If the determination in step S110 is not satisfied, the process proceeds to step S111, and the timer T
It is determined whether seconds have elapsed. If the determination in step S111 is satisfied, that is, if the tank internal pressure PT does not reach the predetermined negative pressure even if 60 seconds have elapsed since the start of the introduction of the negative pressure into the closed section, the process proceeds to step S112, and the flow from the fuel tank 22 to the intake pipe 2 Means that there is a leak or blockage somewhere in the purge system up to this point, and the abnormality notification of the fuel evaporation prevention mechanism is established, so that an abnormality notification lamp or the like is turned on to notify the abnormality. When the determination in step S111 is not satisfied, the present program ends.

Then, this program is executed at predetermined time intervals, during which the tank internal pressure PT decreases, and step S1 is executed.
When the determination at Step 10 is satisfied, the process proceeds to Step S113. In step S113, the purge control valve 40
To close the sealed section from the fuel tank 22 to the purge control valve 40 and reset the timer T (T =
0) Start, reset the flag F1 (F1 ← 0) and set the flag F2 (F2 ← 1), and step S114
Move to In step S114, it is determined whether the timer T has elapsed for 5 seconds. The elapsed time of 5 seconds is a standby time until the tank pressure PT becomes stable after the purge control valve 40 is closed. When the determination in step S114 is satisfied, the process proceeds to step S115, where the tank internal pressure PT is stored as P1, the timer T is reset (T = 0), the flag F2 is reset (F2 ← F).
0) and the flag F3 are set (F3 ← 1). With the processing up to this point, the first stage ends.

Next, as a second stage, step S116
It is determined whether the timer T has elapsed for 10 seconds. The elapsed time of 10 seconds is a time for detecting a change state of the tank internal pressure PT. When the determination in step S116 is satisfied, the process proceeds to step S117, where the tank internal pressure PT is stored as P2, and a change amount ΔP1 (= P2−P1) of the tank internal pressure PT for 10 seconds is calculated, and then the process proceeds to step S118. . In step S118, it is determined whether the change amount ΔP1 of the tank internal pressure PT calculated in step S117 is equal to or greater than a predetermined value K1. If the determination in step S118 is not satisfied, the process proceeds to step S119. In this case, the fuel evaporation prevention mechanism is assumed to be normal without any leak, and the process proceeds to step S1 described later.
Move to 31. With the processing so far, the second stage ends.

Next, as a third stage, step S118
Is satisfied, the process proceeds to step S120, the canister closing valve 37 is opened, the timer T is reset (T = 0), the flag F3 is reset (F3 ← 0), and the flag F4 is set (F4 ← 1). )
Then, control goes to a step S121. In step S121, it is determined whether the tank internal pressure PT is equal to or higher than a predetermined value KPT2. If the determination in step S121 is not satisfied, the process proceeds to step S122, and it is determined whether the timer T has elapsed for 90 seconds. The elapsed time of 90 seconds is a time for equilibrating the pressure in the closed section and the atmospheric pressure. Here, the pressure value based on the output signal from the pressure sensor 44 that detects the tank internal pressure PT does not always become 0 mmHg even when it is opened to the atmosphere and becomes in an equilibrium state due to manufacturing tolerance, temperature characteristic tolerance, piping resistance, and the like. .
In the experiment of the inventors, the result that the predetermined value KPT2 was the best -2 mmHg was obtained. The process waits until the determination in step S122 is established, and proceeds to step S123. On the other hand, when the determination in step S121 is established,
Proceeding to step S123, the canister closing valve 37
Is closed again, the tank internal pressure PT is stored as P3, the timer T is reset (T = 0), the flag F4
Is reset (F4 ← 0) and the flag F5 is set (F5
← 1), and then proceeds to step S124. With the processing so far, the third stage ends.

Next, as a fourth stage, step S124
It is determined whether the timer T has elapsed for 10 seconds. The elapsed time of 10 seconds is a time for detecting a change state of the tank internal pressure PT. When the determination in step S124 is established, the process proceeds to step S125, in which the tank internal pressure PT is stored as P4, and a change amount ΔP2 (= P4−P3) of the tank internal pressure PT for 10 seconds is calculated, and then the process proceeds to step S126. . In step S126, it is determined whether or not the change amount ΔP2 of the tank internal pressure PT is less than a predetermined value K2. Step S126
Does not hold, it indicates that fuel gas is being actively generated during the detection of the abnormality of the fuel evaporation prevention mechanism. When the fuel gas is actively generated, there is a possibility that a correct determination cannot be made.
Move to 31. When the determination in step S126 is established, the process proceeds to step S127, in which the change amount ΔP1 of the tank internal pressure PT calculated in the second stage in the closed section from the fuel tank 22 to the purge control valve 40 for 10 seconds has elapsed.
(= P2−P1) and the difference ΔP2 (= P4−P3) of the tank internal pressure PT during the elapse of 10 seconds after the closed section calculated in the fourth stage is equilibrated with the atmospheric pressure and then closed. ΔP3 (= ΔP1−ΔP2 × α) is calculated. That is, the change amount ΔP1 of the tank internal pressure PT under the negative pressure has the meaning represented by the following equation.

ΔP1 = (amount of evaporative gas generated in the fuel tank 22) + (amount flowing into the closed section from the atmosphere) Further, a change amount ΔP2 of the tank internal pressure PT under the atmospheric pressure has the following meaning. Become.

ΔP2 = (amount of evaporative gas generated in the fuel tank 22) + (amount of air flowing out of the closed section) where α is a correction for correcting the difference between the amount of evaporative gas generated under negative pressure and atmospheric pressure. It is a coefficient.

Therefore, when there is no leak in the closed section, ΔP1 becomes small (normal judgment is established in the above-described step S119).

When there is a leak in the closed section,
ΔP1 is large and ΔP2 is small, so that ΔP3
Becomes larger.

When the amount of generated evaporative gas is large, Δ
P1 is large, ΔP2 is large, and as a result, ΔP3 is small.

That is, when ΔP1 is large, an abnormality can be detected by ΔP3.

Therefore, the process proceeds to step S128,
It is determined whether ΔP3 is less than a predetermined value K3. If the determination in step S128 does not hold, the process proceeds to step S129, meaning that there is a leak or blockage somewhere in the purge system from the fuel tank 22 to the intake pipe 2, and the abnormality determination of the fuel evaporation prevention mechanism is established. Therefore, an abnormality notification lamp or the like is turned on to notify the abnormality. On the other hand, when the determination in step S128 is satisfied, the process proceeds to step S130. In this case, the fuel evaporation prevention mechanism is normal without any leak, and the process proceeds to step S131.
The canister closing valve 37 is opened and the timer T
Is reset (T = 0), all the flags for the detection state determination are reset (F1 to F5 ← 0), and the program ends.

As described above, the abnormality detecting device for the fuel evaporation prevention mechanism according to the present embodiment includes a purge passage formed by the communication pipe 28 and the supply pipes 38 and 42 for connecting the fuel tank 22 and the intake pipe 2 of the internal combustion engine 3. The adsorbent 34 of the canister 30 provided on the way adsorbs the fuel gas generated in the fuel tank 22 as needed, and opens and closes the purge control valve 40 in accordance with the operation state of the internal combustion engine 3, thereby obtaining the adsorbed fuel. A fuel evaporation prevention mechanism for appropriately introducing gas into the intake pipe 2 to prevent fuel evaporation, pressure detection means achieved by a pressure sensor 44 for detecting a pressure state in the fuel evaporation prevention mechanism, and a canister 30 The air hole closing means achieved by the provided canister closing valve 37 for closing the air hole, the purge control valve 40 and the air hole closing means are both closed to close the fuel vapor. A sealing means achieved by an electronic control circuit 50 having the entire prevention mechanism as one closed section, an intake pipe pressure detecting means achieved by a pressure sensor 62 for detecting a pressure state in the intake pipe 2, A fuel amount detecting means achieved by a fuel gauge 23 for detecting a fuel amount in the tank 22, a pressure state in the intake pipe 2 detected by the intake pipe pressure detecting means, and a fuel state detected by the fuel amount detecting means. An electronic control circuit 50 controls the opening of the purge control valve 40 in accordance with the amount of fuel in the fuel tank 22 to change the speed of introducing the negative pressure from the intake pipe 2 to adjust the pressure in the closed section to a predetermined pressure. Based on the pressure state in the fuel evaporation prevention mechanism detected by the pressure detecting means during or after pressure adjustment by the closed section pressure adjusting means to be achieved. A pressure change state measuring means achieved by an electronic control circuit 50 for measuring a predetermined pressure change state, and an abnormality of the fuel evaporation prevention mechanism is determined from the predetermined pressure change state measured by the pressure change state measurement means. An abnormality detecting means achieved by an electronic control circuit (50) for detecting the abnormality.
Of the present invention.

Therefore, when the pressure in the closed section is adjusted to the predetermined pressure by the closed section pressure adjusting means, the size of the space volume in the closed section is taken into consideration, and there is no difference in the negative pressure introduction speed. The pressure is precisely adjusted to a predetermined pressure without overshooting. Further, a predetermined pressure change state based on the pressure state in the fuel evaporation prevention mechanism detected by the pressure detection means at the time of pressure adjustment by the pressure change state measurement means or after the pressure adjustment is measured. When the amount of fuel is large and the space volume is large, there is no leakage (normal), and conversely, when the amount of fuel is large and the space volume is small, leakage (abnormal) occurs after the introduction of the negative pressure to a predetermined pressure. It is possible to determine the time to reach.

Therefore, the variation of the tank internal pressure in the fuel tank with respect to the predetermined pressure is reduced, and it is possible to prevent erroneous detection when detecting an abnormality in the fuel evaporation prevention mechanism.

Incidentally, the pressure detecting means of the above embodiment is
Although the present invention has been described as being achieved by the pressure sensor 44, the present invention is not limited to this, but may be any as long as it detects the pressure state in the fuel evaporation prevention mechanism.

Although the air hole closing means in the above embodiment is achieved by the canister closing valve 37, the present invention is not limited to this, and is provided in the canister 30. Any material can be used as long as it blocks the air holes.

Although the sealing means in the above embodiment is achieved by the electronic control circuit 50, the present invention is not limited to this. It suffices if the air hole closing means is closed together so that the entire fuel evaporation prevention mechanism is a closed section.

The pressure detecting means in the above-described embodiment is realized by the pressure sensor 62. However, the present invention is not limited to this.
What is necessary is just to detect the pressure state in the intake pipe 2.

Further, the fuel amount detecting means of the above embodiment is described as being realized by the fuel gauge 23. However, the present invention is not limited to this. What is necessary is just to detect the fuel amount.

Further, although the closed section pressure adjusting means of the above embodiment is described as being achieved by the electronic control circuit 50, the present invention is not limited to this. The degree of opening of the purge control valve 40 is controlled in accordance with the pressure state in the intake pipe 2 detected by the pipe pressure detecting means and the fuel amount in the fuel tank 22 detected by the fuel amount detecting means. The negative pressure introduction speed may be changed to adjust the pressure in the closed section to a predetermined pressure.

In addition, the pressure change state measuring means in the above embodiment is realized by the electronic control circuit 50. However, the present invention is not limited to this, and the present invention is not limited thereto. What is necessary is just to measure a predetermined pressure change state based on the pressure state in the fuel evaporation prevention mechanism detected by the pressure detection means at the time of pressure adjustment by the section pressure adjustment means or after the pressure adjustment.

Although the abnormality detecting means in the above embodiment is achieved by the electronic control circuit 50, the present invention is not limited to this. What is necessary is just to detect an abnormality of the fuel evaporation prevention mechanism from the predetermined pressure change state measured by the means.

Further, the closed section pressure adjusting means of the abnormality detection apparatus for a fuel evaporation prevention mechanism of the present embodiment adjusts the pressure in the closed section to a predetermined pressure by introducing a negative pressure into the closed section. An air hole closing means achieved by a purge control valve 40 and a canister closing valve 37 adjusts the pressure of the closed section, both of which are closed, to a predetermined pressure. it can.

Therefore, the introduction of the negative pressure is performed first as the order of adjusting the pressure in the closed section of the fuel evaporation prevention mechanism in the closed section pressure adjusting means.

Therefore, the generation times of the two tank internal pressures used for the determination in the closed section can be temporally approached, so that the detection accuracy in the abnormality detection is improved.

Further, the space volume of the closed section of the abnormality detecting device for a fuel evaporation prevention mechanism of the present embodiment is calculated based on the fuel amount in the fuel tank 22 detected by the fuel amount detecting means. This can be the embodiment of claim 3.

Therefore, the calculation of the space volume in the closed section only requires reading the output signal from the fuel gauge 23 for calculating the fuel amount in the fuel tank 22.

Therefore, the space volume of the closed section can be easily calculated by an existing detector or the like, and there is no new increase in cost.

Further, the abnormality detecting means of the abnormality detecting apparatus for a fuel evaporation prevention mechanism of the present embodiment is executed in an operating state in which the amount of change in the fuel amount in the fuel tank 22 detected by the fuel amount detecting means is small. This can be regarded as the embodiment of claim 4. Therefore, during an operating state in which the fuel amount in the fuel tank 22 detected by the fuel amount detecting means changes greatly, the abnormality detecting means is not executed.

Therefore, the fuel amount when the operating condition is stabilized by the fuel amount detecting means, that is, the space volume of the closed section is accurately detected, and the abnormality detecting means makes the abnormality judgment more accurate.

[0068]

As described above, according to the abnormality detecting device for a fuel evaporation prevention mechanism of the first aspect, when adjusting the pressure of the closed section by the closed section pressure adjusting means, the intake of the fuel evaporation prevention mechanism to the closed section is performed. Since the negative pressure introduction speed from the pipe is not affected by the magnitude of the intake pipe pressure or the amount of fuel in the fuel tank, the abnormality detection of the fuel evaporation prevention mechanism based on the measured pressure change state becomes accurate, It is possible to accurately detect occurrence of a leak or blockage in a section from the fuel tank to the purge control valve.

According to the second aspect of the present invention, in addition to the effect of the first aspect, in addition to the effect of the first aspect, the closed section pressure adjusting means precedes the closed section of the fuel evaporation prevention mechanism with the intake pipe. Since it is adjusted to a predetermined pressure by introducing a negative pressure from
The predetermined pressure detection time at the time of introducing the negative pressure and the subsequent predetermined pressure detection time of the closed section can be temporally close to each other, and the effect of improving the pressure detection accuracy can be expected.

According to the third aspect of the present invention, in addition to the effect of the first aspect, in addition to the effect of the first aspect, the calculation of the space volume of the closed section is performed by the fuel amount detection means in the fuel tank. The amount of fuel is used, and the speed at which negative pressure is introduced in the section from the fuel tank to the purge control valve is changed in accordance with the volume of the space to stabilize the pressure change state in the closed section. Detection accuracy can be significantly improved.

According to the fourth aspect of the present invention, in addition to the effect of the first aspect, the amount of change in the amount of fuel in the fuel tank detected by the fuel amount detecting means is small. Abnormality detection processing is performed in the operating state, preventing erroneous detection due to pressure changes due to fuel level fluctuations in the fuel tank during rough roads, sudden acceleration / deceleration, and sudden turning, and the timing of abnormality detection is stopped. It is possible during driving without being limited to the idle operation of the vehicle.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an abnormality detection device for a fuel evaporation prevention mechanism according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration of a canister closing valve used in the abnormality detection device for a fuel evaporation prevention mechanism according to one embodiment of the present invention.

FIG. 3 is a sectional view showing a schematic configuration of a purge control valve used in the abnormality detection device for a fuel evaporation prevention mechanism according to one embodiment of the present invention.

FIG. 4 is a purge control valve drive duty ratio when the pressure difference between the front and rear ports is constant (450 mmHg) in the purge control valve used in the abnormality detection device for the fuel evaporation prevention mechanism according to one embodiment of the present invention. FIG. 4 is a characteristic diagram illustrating a relationship between (%) and a purge flow rate.

FIG. 5 is a diagram illustrating a purge control valve driving duty ratio of a purge control valve used in the abnormality detection device for a fuel evaporation prevention mechanism according to one embodiment of the present invention;
FIG. 9 is a characteristic diagram showing a relationship between a purge control valve front-rear port differential pressure (mmHg) and a purge flow rate when the pressure is 00%).

FIG. 6 is an electronic control circuit C used in the abnormality detection device for the fuel evaporation prevention mechanism according to one embodiment of the present invention.
It is a flowchart which shows the processing procedure of PU.

FIG. 7 is an electronic control circuit C used in the abnormality detection device for the fuel evaporation prevention mechanism according to one embodiment of the present invention.
7 is a flowchart showing the processing procedure of the PU, following FIG. 6.

FIG. 8 is a timing chart showing a state during execution of an abnormality detection process of the abnormality detection device for a fuel evaporation prevention mechanism according to one embodiment of the present invention.

FIG. 9 is a block diagram showing the concept of the present invention.

[Explanation of symbols]

 2 intake pipe 3 internal combustion engine 8 throttle valve 22 fuel tank 23 fuel gauge 28 communication pipe 30 canister 34 adsorbent 36 atmosphere hole 37 canister closing valve 38 supply pipe 40 purge control valve 42 supply pipe 44 pressure sensor 50 electronic control circuit 52 CPU 62 Pressure sensor 64 Speed sensor 66 Vehicle speed sensor

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02M 25/08 F02M 25/08 301

Claims (5)

(57) [Claims] 1. An operating state of the internal combustion engine, wherein a fuel gas generated in the fuel tank is adsorbed as needed by an adsorbent of a canister provided in a purge passage communicating the fuel tank with an intake pipe of the internal combustion engine. Opening and closing a purge control valve according to the above, appropriately introducing the adsorbed fuel gas into the intake pipe to prevent fuel evaporation, and detecting a pressure state in the fuel evaporation prevention mechanism. Pressure detection means, air hole closing means for closing the air holes provided in the canister, and sealing in which the purge control valve and the air hole closing means are closed together to make the whole fuel evaporation prevention mechanism one closed section. An intake pipe pressure detecting means for detecting a pressure state in the intake pipe; a fuel amount detecting means for detecting a fuel amount in the fuel tank; The opening degree of the purge control valve is controlled in accordance with the pressure state in the intake pipe detected by the force detecting means and the fuel amount in the fuel tank detected by the fuel amount detecting means, and the negative pressure from the intake pipe is controlled. A closed section pressure adjusting means for changing the pressure introduction speed to adjust the pressure of the closed section to a predetermined pressure, and the pressure detected by the pressure detecting means during or after pressure adjustment by the closed section pressure adjusting means. A pressure change state measuring means for measuring a predetermined pressure change state based on a pressure state in the fuel evaporation prevention mechanism; and an abnormality of the fuel evaporation prevention mechanism from the predetermined pressure change state measured by the pressure change state measurement means. An abnormality detection device for a fuel evaporation prevention mechanism, comprising: an abnormality detection means for detecting. 2. The closed section pressure adjusting means adjusts the pressure in the closed section to a predetermined pressure by introducing a negative pressure into the closed section, after which both the purge control valve and the air hole closing means are closed. The abnormality detection device for a fuel evaporation prevention mechanism according to claim 1, wherein the pressure in the closed section is adjusted to a predetermined pressure. 3. The abnormality for a fuel evaporation prevention mechanism according to claim 1, wherein the space volume of the closed section is calculated based on a fuel amount in the fuel tank detected by the fuel amount detecting means. Detection device. 4. The fuel transpiration according to claim 1, wherein the abnormality detecting means is executed in an operation state in which the amount of change in the fuel amount in the fuel tank detected by the fuel amount detecting means is small. Abnormality detection device for prevention mechanism. (5) Communication between fuel tank and intake pipe of internal combustion engine
With a canister adsorbent provided in the middle of the purge passage
The fuel gas generated in the fuel tank is adsorbed as needed, and
Open and close the purge control valve according to the operating state of the internal combustion engine
By doing so, the adsorbed fuel gas is
Anti-transpiration machine that is appropriately introduced into the inside to prevent fuel transpiration
And Pressure for detecting a pressure state in the fuel evaporation prevention mechanism
Detecting means; Atmospheric hole closing for closing the atmospheric hole provided in the canister
Closing means, Both the purge control valve and the air hole closing means are closed.
The entire fuel evaporation prevention mechanism is one closed section
Sealing means; Intake pipe pressure detection means for detecting the pressure state in the intake pipe
Steps and In the intake pipe detected by the intake pipe pressure detection means,
The opening degree of the purge control valve is controlled according to the pressure state.
To change the negative pressure introduction speed from the intake pipe to
Closed section pressure adjusting means for adjusting the pressure between them to a predetermined pressure
When, At the time of pressure adjustment by the closed section pressure adjusting means or pressure
The fuel vapor detected by the pressure detecting means after the force adjustment.
Predetermined pressure change based on pressure state in anti-scattering mechanism
Pressure change state measuring means for measuring the state, The predetermined pressure measured by the pressure change state measuring means
Detecting abnormality of the fuel evaporation prevention mechanism from the force change state
Abnormality detection means Fuel transpiration prevention characterized by comprising:
Abnormality detection device for stop mechanism.