JPH05125997A - Abnormality detection device for fuel evaporation prevention device - Google Patents

Abstract

PURPOSE:To surely detect any abnormality that could cause leakage, such as breakage somewhere in the whole fuel evaporation preventive device from a fuel tank to a suction pipe. CONSTITUTION:A canister blocking valve 37 for blocking an atmospheric hole 36 is mounted in a canister 30 and a pressure sensor 44 is mounted in a fuel tank 22. While a vehicle is stopped and in an idle operating condition, a purge control valve 40 and the canister blocking valve 37 are closed up to keep the area from the fuel tank 22 to a suction pipe 2 in a sealed state under atmospheric pressure (time T1, T2), and the amount DELTA1 of pressure changes in the sealed state under atmospheric pressure is measured (time T2-T3). Next, the purge control valve 40 is closed up and then switched to a full open state and suction pipe negative pressure is introduced into the sealed area (time T3) and the amount DELTA2 of pressure changes in the sealed state under negative pressure is measured (time T4-T5). When DELTAP2 is greater than /DELTAP1, the result of detection that a cause of leakage exists somewhere in the sealed area is notified.

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 preventing device for detecting an abnormality such as leakage of fuel gas in a fuel evaporation preventing device for preventing evaporation of fuel gas generated in a fuel tank.

[0002]

2. Description of the Related Art Conventionally, in automobiles and the like, it has been obliged to equip a fuel evaporation preventing device in order to prevent the fuel gas generated in a fuel tank from being released into the atmosphere. The fuel transpiration prevention device adsorbs fuel gas at any time by an adsorbent of a canister provided in the middle of a purge passage that connects the fuel tank and the intake pipe, and opens and closes the purge control valve according to the operating state of the internal combustion engine. With this, the adsorbed fuel gas is appropriately introduced into the intake pipe and mixed into the fuel mixture to prevent fuel evaporation.

In such a fuel evaporation preventing apparatus, a purge passage is usually formed by connecting a canister and an intake pipe with a rubber hose. When this 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, since the rubber hose is in contact with the alcohol component, it may be damaged due to corrosion or the like, and if the atmospheric hole of the canister is clogged with dust or the like, it may be removed due to a pressure increase. In this case as well, the fuel gas is released to the atmosphere.

Therefore, in order to detect the occurrence of such a situation, a pressure sensor is arranged in the purge passage between the canister and the intake pipe (hereinafter referred to as the intake pipe side purge passage), and the detection result of this pressure sensor is normal. There is proposed a device in which the fuel evaporation prevention device has an abnormality when the maximum pressure exceeds the maximum pressure and when a predetermined pressure difference cannot be detected before and after switching the opening / closing state of the purge control valve (for example, Japanese Patent Laid-Open No. HEI-2).
No. 130255). According to the device described in this publication, it is possible to accurately detect the blockage of the atmospheric hole of the canister, the inability to open the purge control valve, and the breakage or drop of the intake pipe side purge passage.

[0005]

However, in the fuel transpiration prevention device, the rubber hose is used in the connecting portion of the purge passage (hereinafter referred to as the tank side purge passage) in the portion connecting the fuel tank and the canister. There is a risk that the fuel gas may be released into the atmosphere even if this side is damaged or falls off. On the other hand, in the conventional apparatus, even if the tank side purge passage is damaged or dropped, it cannot be detected as abnormal.

From the prior art, it seems that if a pressure sensor is also provided in this tank side purge passage, it is possible to detect damage and dropout there as well, but there are the following problems, and it will be simpler. I didn't.

The fuel gas pressure from the fuel tank is constantly applied to the tank side purge passage. Therefore, the detection value of the pressure sensor attached here is greatly influenced by the evaporation amount of the fuel gas in the fuel tank. The fuel gas evaporation amount in the fuel tank is not constant, but changes depending on the remaining fuel amount, the outside air temperature, the fuel consumption state, and the like. Therefore, simply adding a pressure sensor to the tank side purge passage cannot detect damage to the tank side purge passage due to the influence of the evaporation amount of the fuel gas.

Further, in the conventional apparatus, since the pressure sensor is attached to the intake pipe side purge passage, the structure must be able to withstand a wide range of pressure changes from the intake pipe negative pressure to the atmospheric pressure. Therefore, the pressure detection sensitivity is low, and accordingly, the abnormality detection accuracy is also low.

Therefore, in the present invention, as a first object, when there is an abnormality such as breakage anywhere in the entire fuel transpiration prevention device from the fuel tank to the intake pipe, it can be reliably detected. It was decided to provide the basic configuration of the abnormality detection device for the fuel evaporation prevention device.

As a second object, in particular, when there is an abnormality that causes a leak such as breakage anywhere in the entire fuel transpiration prevention device from the fuel tank to the intake pipe, this can be reliably detected. It is decided to provide an abnormality detection device for a fuel evaporation prevention device that can be performed.

Further, as a third object, if not only the cause of the leakage but also a clogging abnormality such as a hose collapse in the entire fuel evaporation preventing device from the fuel tank to the intake pipe, this can be surely prevented. It is decided to provide an abnormality detection device for a fuel evaporation prevention device that can detect the abnormality.

In addition, a fourth object is to provide an abnormality detecting device for a fuel transpiration preventing device which can use a sensor having high pressure detecting sensitivity and which has high abnormality detecting accuracy.

[0013]

The abnormality detecting device for a fuel evaporation preventing device of the present invention completed to achieve the first object has a fuel tank and an intake pipe as illustrated in FIG. The adsorbent of the canister provided in the middle of the communicating purge passage adsorbs the fuel gas generated in the fuel tank at any time, and the purge control valve is opened / closed according to the operating state of the internal combustion engine to adsorb the adsorbed fuel. A fuel transpiration prevention device for appropriately introducing gas into the intake pipe to prevent fuel transpiration, pressure detection means for detecting a pressure state in the fuel transpiration prevention device, and fuel transpiration prevention based on the detection result of the pressure detection means An abnormality detecting device for a fuel evaporation prevention device, comprising: an abnormality detecting device for detecting an abnormality of the device; an atmospheric hole closing device for closing an atmospheric hole provided in the canister; and the purge control valve. And the air hole blocking means are closed together to make the whole fuel evaporation prevention device a closed section, a closed section pressure adjusting means for adjusting the pressure of the closed section to a predetermined pressure, and a closed section pressure adjustment. Pressure change state measuring means for measuring a predetermined pressure change state during or after pressure adjustment by means, and the abnormality detecting means detects an abnormality of the fuel evaporation prevention device from the pressure change state. It is characterized by

In this basic configuration, for example, the closed section pressure adjusting means adjusts the pressure in the closed section by switching it between a first predetermined pressure and a second predetermined pressure, and the pressure change state measuring means 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 respectively measured, and the abnormality detecting means, The fuel transpiration prevention device according to claim 2, which is particularly suitable for achieving the second object, if the abnormality of the fuel transpiration prevention device is detected by comparing the first and second pressure change states. It can be developed into an abnormality detection device.

According to the abnormality detecting device for a fuel transpiration preventing device of the second aspect, the section from the fuel tank to the intake pipe is made into one closed section by including the atmospheric hole closing means and the sealing means. be able to. If there is a cause of leakage due to damage or dropping of the rubber hose in any of the closed sections, gas leaks from the closed section to the atmosphere or vice versa based on the difference between the internal pressure and the atmospheric pressure of the closed section. .. The gas leak rate changes depending on the pressure difference. If the cause of the leak exists, the difference in relative pressure difference from the atmospheric pressure when the first predetermined pressure is adjusted by the closed section pressure adjusting means and when the second predetermined pressure is adjusted. The leak rate changes based on. Therefore, "when there is a predetermined difference between the first and second pressure change states measured by the pressure change state measuring means, there is a leak cause somewhere in the closed section, and such a difference is not found. If not, the cause of leak does not exist "can be easily detected.

Further, in order to achieve the third object, in the abnormality detecting device for a fuel transpiration preventing device according to claim 1,
The closed section pressure adjusting means introduces a negative pressure from the vicinity of the end portion on the intake pipe side, the pressure change state measuring means measures a pressure change state at the time of introducing the negative pressure, and the abnormality detecting means The abnormality detection device for a fuel evaporation prevention device according to claim 3, wherein an abnormality of the fuel evaporation prevention device is detected based on a pressure change state when the negative pressure is introduced.

According to the third aspect of the present invention, if there is a closed state somewhere in the purge passage, the pressure detected by the pressure detecting means is planned when the negative pressure is introduced from the intake pipe side into the closed section. It takes time to reach the negative pressure state of, or such negative pressure state is not reached. Therefore, it is possible to easily determine the presence / absence of abnormality related to the blockage by observing the pressure change situation when the negative pressure is introduced.

In order to achieve the fourth object, in the abnormality detecting device for a fuel evaporation preventing device according to any one of claims 1 to 3, the pressure detecting means is provided in a section from the fuel tank to the canister. An abnormality detection device for a fuel evaporation prevention device, which is characterized in that it is provided, is also completed.

With this structure, the pressure detecting means can be structured to withstand pressure fluctuations within the relief pressure range of the fuel tank, and the sensitivity can be increased accordingly. Therefore, even a subtle pressure change state can be accurately detected, and the abnormality determination accuracy can be improved.

As the pressure detecting means for realizing the present invention, for example, a semiconductor type pressure sensor for detecting the pressure by utilizing the piezo effect accompanying the deformation of the diaphragm can be used. This semiconductor type pressure sensor has a very thin diaphragm and can detect pressure with high sensitivity. However, since water vapor is also generated in the fuel tank, water may adhere to the diaphragm. If water adheres, the deformation of the diaphragm becomes uneven and an error occurs. It is also possible that the diaphragm may break due to freezing. In addition, gum and dust in gasoline may adhere to the diaphragm to cause an error in the amount of strain, which makes it impossible to detect the accurate pressure.

Therefore, as a fifth object, in realizing the above-mentioned inventions, there is no possibility of causing an error during use, and an abnormality detecting device for a fuel evaporation preventing apparatus capable of always performing highly reliable abnormality detection. Decided to provide.

In order to achieve this fifth object, claim 1
5. The abnormality detection device for a fuel evaporation prevention device according to claim 4, wherein the pressure detecting means is a displacement member that is displaced according to the pressure, a magnetic member attached to the displacement member, and a magnetic member. We have also completed an abnormality detection device for a fuel transpiration prevention device, characterized in that it comprises a Hall element that changes its output based on displacement.

As a result, even in a fuel tank containing water, gum, or dust, pressure can be detected without causing an error, and reliable abnormality detection can always be performed.

[0024]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 2 is a schematic configuration diagram of an abnormality detection device for a fuel transpiration prevention device according to an embodiment of the present invention. The air sucked through the air cleaner 1 that filters air is supplied to an intake pipe 2 connected to the air cleaner 1. Inside the intake pipe 2, a throttle valve 8 that opens and closes in conjunction with an accelerator pedal 6 is provided. The intake pipe 2 is connected to a combustion chamber 16 formed by a piston 12 and an internal combustion engine body 14 via an intake valve 10. Further, the combustion chamber 16 is connected to an exhaust pipe 20 via an exhaust valve 18.

On the other hand, a fuel tank 22 containing a liquid fuel
A fuel pump 24 for pressurizing and supplying the fuel inside, and an intake pipe 2
Is connected to the fuel injection valve 26 provided in the vehicle, and is configured to control the opening and closing of the fuel injection valve 26 to inject fuel. Further, the communication pipe 28 connected to the fuel tank 22.
Is connected to the canister 30. An adsorbent 34 that adsorbs fuel gas, such as activated carbon, is housed in the canister body 32. This allows the canister 30
Can adsorb the fuel gas generated in the fuel tank 22 through the communication pipe 28. Also, the canister body 3
At 2 is formed an atmosphere hole 36 open to the atmosphere, so that air can be sucked into the inside. This hole 36
A canister shutoff valve 37 for shutting off the canister is attached to the valve.

As shown in FIG. 3, the canister shutoff valve 37 has a valve body 37b which is a spring 37 when a predetermined voltage (for example, 6V or more) is not applied to the coil 37a.
The conduit 37d that is urged by c to communicate with the atmosphere hole 36 of the canister body 32 is opened, and when a predetermined voltage is applied, the coil 37a is excited to move the valve body 37b against the urging force of the spring 37c. This is an electromagnetic on-off valve that closes the conduit 37d.

Further, one end of the supply pipe 38 is inserted into the hose connecting portion 32a of the canister body 32 so that the canister 30 is
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. The supply pipes 38 and 42 used here are made of a flexible material such as a rubber hose or a nylon hose and are entirely formed. Further, the communication pipe 28 connecting the fuel tank 22 and the canister 30 is also partially formed by a rubber hose or the like.

The fuel tank 22 is connected by the supply pipes 38, 42 and the communication pipe 28 attached to the purge control valve 40.
To the intake pipe 2 constitutes a purge passage. The purge control valve 40 is provided between the two supply pipes 38 and 42 to switch the intake pipe 2 and the canister 30 between communication and non-communication, and both supply pipes are provided according to an input signal. 38 and 42 are connected and disconnected. The details are shown in FIG.

As shown in the figure, the purge control valve 40 has a canister side port 40a to which the supply pipe 38 is attached, an intake pipe side port 40b to which the supply pipe 42 is attached, and a passage 40c between these ports 40a and 40b. A valve body 40d that opens and closes on the way, a spring 40e that urges the valve body 40d in the valve closing direction, and a coil 40f that moves the valve body 40d in the valve opening direction against the urging force of the spring 40e to perform purging. Is an electromagnetic on-off valve equipped with and. A voltage is applied to the coil 40f 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 the valve open position of the valve body 40d to the opening / closing cycle of the valve body 40d is changed, and the canister 30 moves to the intake pipe 2. The purge flow rate of the fuel gas can be controlled. The relationship between the purge control valve drive duty and the purge flow rate is shown in FIG.

A pressure sensor 44 is arranged in the fuel tank 22. Also, the fuel tank 22 has a -40 mm
A relief valve 22a is provided to release the pressure when the internal pressure exceeds Hg to 150 mmHg. Therefore, the section from the fuel tank 22 to the canister 30 is always suppressed to be equal to or less than the pressure fluctuation within this relief pressure range. Therefore, it suffices to employ a pressure sensor 44 having a structure capable of withstanding this relief pressure range.

The fuel injection valve 26, the canister closing valve 37, the purge control valve 40 and the pressure sensor 44 are connected to an electronic control circuit 50. The electronic control circuit 50 includes a well-known CPU 52, a ROM 54 that stores a control program and data in advance, and a readable / writable RAM 5
6 and the input / output circuit 58 are connected to each other via a common bus 60. Further, the input / output circuit 58 is also connected to various operating state detecting means such as a throttle sensor 62, an idle switch 64, a vehicle speed sensor 66 and the like. The CPU 52 receives signals from the operating state detecting means via the input / output circuit 58 and the ROM 54,
Based on the program and data in the RAM 56, the fuel injection valve 26, the canister closing valve 37, the purge control valve 40
And the like through 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 of the fuel evaporation preventing device, and the like.

Next, of the processes performed by the electronic control circuit 50 described above, the abnormality detection control of the fuel evaporation prevention device will be described with reference to the flowcharts of FIGS. 6 and 7 and the timing chart of FIG.

When a key switch (not shown) is turned on, the abnormality detection control of the fuel evaporation prevention apparatus is repeatedly executed at predetermined time intervals (for example, every 256 msec) together with the fuel injection control processing and the like.

When the processing is started, first, the vehicle speed sensor 6
Based on the input signal from 6, it is determined whether or not the vehicle speed SP = 0 (S100). When it is determined to be "YES", it is determined based on the input signal from the idle switch 64 whether or not the idle operation is being performed (S110). In addition, S
When it is determined to be "NO" in either 100 or S110, the processing is ended as it is. That is, the abnormality detection is executed only when the vehicle is stopped and in the idle operation state. This is because the internal pressure of the fuel tank may fluctuate during traveling on a rough road or while turning, and correct determination may not be possible in the following steps. Further, even when the vehicle is stopped, the engine speed is not stable in the racing state and the internal pressure of the fuel tank becomes unstable, which may also make it impossible to make a correct determination.

If the vehicle is stopped and the vehicle is idling, the process branches to various steps while determining whether the process is in progress (S120 to S140). There are four treatments from the first to the fourth stage, and the first
The processing stage can be determined from the setting states of the third flags F1 to F3. When all flags F1 to F3 are set to “0”, that is, S120 to S140.
When all are "NO", it is the first stage, and the process proceeds to S150.

In the first stage, first, the purge control valve 40 is fully closed, and then the canister closing valve 37 is fully closed to seal the section from the fuel tank 22 to the intake pipe 2 (S1).
50, S160).

That is, as shown in FIG. 8, first, by controlling the purge control valve 40 to be fully closed, the section from the fuel tank 22 to the purge control valve 40 is adjusted to the same state as the atmospheric pressure via the atmosphere hole 36. Then (time T1), the canister closing valve 37 is fully closed with a slight delay to form a closed section adjusted to atmospheric pressure (time T2).

Then, the input signal from the pressure sensor 44 is immediately taken in to store the tank internal pressure P1 'immediately after sealing and reset the timer T built in the electronic control circuit 50 (S170). In the next step, S
It is determined whether or not 10 seconds have elapsed after the execution of step 170 (S180). Before the elapse of 10 seconds, the first flag F1 is set to "1" (S190). This is the second stage. In the second stage, the determination of “YES” comes to be made in the step of S120, and “S100-
The processing is repeated in the order of “S120” → “S180” → “...”.
During this time, the detection value of the pressure sensor 44 rises from 0 mmHg according to the amount of the fuel gas generated in the fuel tank 22, as in the time T2 to the time T3 in FIG.

Immediately after the lapse of 10 seconds, the input signal from the pressure sensor 44 is taken in to store the tank internal pressure P1 "at this time (S200), and after sealing 10
A pressure change amount (hereinafter, referred to as an atmospheric pressure change amount) ΔP1 during sec is calculated (S210), and the first flag F1 is reset (S220). This completes the second stage and moves to the third stage.

In the third stage, first, the purge control valve 40 is switched from the fully closed state to the fully opened state and the timer T is reset and started (S230). When the purge control valve 40 is fully opened, the intake pipe negative pressure starts to be introduced into the closed section under the positive pressure up to the point (time T3). Therefore, if there is no abnormality due to blockage in the purge passage portion, the detection value of the pressure sensor 44 begins to fall.

In the next step, the tank internal pressure PT is -20 mmH based on the input signal from the pressure sensor 44.
It is determined whether or not it has become g or less (S240). "N
If it is determined to be "O", 2 steps after step S230 is executed
It is determined whether or not c has passed (S250). 2 sec
Before the elapse, the second flag F2 is set to "1" (S26).
0). Thus, in step S120, "N
The determination of “YES” comes to be made in the steps of “O” and S130, and “S100 to S130” → “S25”.
The process is repeated from "0" to "..." to enter the standby state. This standby state ends when S240 or S250 becomes “YES”. If "YES" is obtained in S250, the purge system, that is, the flag Fclose, which means that the purge system from the fuel tank 22 to the intake pipe 2 has a closed portion somewhere, is set to "1". (S270), and the abnormality notification lamp is turned on (S280).

On the other hand, if "YES" is obtained in S240, the second flag F2 is reset (S29).
0), and then the purge control valve 40 is fully closed again (S30
0), the input signal from the pressure sensor 44 is taken in, the tank internal pressure P2 ′ immediately after the closed section is brought into the negative pressure sealed state is stored, and the timer T built in the electronic control circuit 50 is reset and started (S310). It has moved from the third stage to the fourth stage.

As can be seen from the detection value of the pressure sensor 44 in FIG. 8, by executing the steps S290 to S310, the closed section is adjusted to a negative pressure state of -20 mmHg. (Time T4). Therefore,
This time, the detected value of the pressure sensor 44 increases from -20 mmHg according to the amount of fuel gas generated in the fuel tank 22, as in the period from time T4 to time T5 in FIG.

In the next step, it is determined whether or not 10 seconds have elapsed after the execution of step S310 (S32).
0). Before the elapse of 10 seconds, the third flag F3 is set to "1" (S330). Thus this time S120, S1
In step S30, "NO" is determined, and in step S140, "YES" is determined.
The process is repeated from 0 to S140 "→" S330 "→" ... "

Immediately after the lapse of 10 seconds, the input signal from the pressure sensor 44 is taken in to store the tank internal pressure P2 "at time T6 (S340), and after the sealing, 1
A pressure change amount for 0 sec (hereinafter referred to as a negative pressure change amount) ΔP2 is calculated (S350). Then, it is determined whether or not there is a leak based on the leak determination condition shown in Expression 1 (S360).

[0046]

[Formula 1] If ΔP2> α · ΔP1 + β, “Leakage” α: Coefficient for correcting the difference in fuel evaporation amount due to the difference between atmospheric pressure and negative pressure β: Pressure sensor accuracy, canister blockage valve leakage correction, etc. That is, if there is a leak cause in the closed section from the fuel tank 22 to the purge control valve 40, the outflow from the closed section to the atmosphere occurs under positive pressure, while the inflow from the atmosphere to the closed section under negative pressure. Occur. Therefore, “(amount of change in negative pressure ΔP1) = (amount of vaporized gas generated in the fuel tank 22) − (amount of outflow from the sealed section into the atmosphere)” is “(amount of change in negative pressure ΔP2) = ( The generated amount of evaporative gas in the fuel tank 22) + (inflow amount from the atmosphere into the sealed section) ”becomes larger. From this, the judgment condition of Formula 1 was derived.

When the determination condition of the equation 1 is satisfied, that is, when "YES" is determined in S360, there is a portion of the purge system from the fuel tank 22 to the intake pipe 2 which causes a leak. The purge leak flag Fleak which means that there is is set to "1" (S370), and the abnormality notification lamp is turned on (S280). On the other hand, if it is determined to be "NO", the flags F1 to F3 are forcibly reset and the process ends (S380).

According to the present embodiment described above, in the fuel evaporation preventing device, the purge control valve 4 is removed from the fuel tank 22.
If a leak or blockage has occurred in the section up to 0, it can always be detected accurately regardless of the mounting position of the pressure sensor.

Further, by adopting the structure for executing the abnormality detection processing while the vehicle is stopped and idle, it is possible to avoid erroneous determination. Further, the pressure sensor 44
Has only to withstand the pressure within the operating range of the relief valve of the fuel tank 22, and therefore does not have to have a structure capable of withstanding large pressure fluctuations such as when mounted between the canister 30 and the intake pipe 2. Good. As a result, a sensor with high sensitivity can be used and the abnormality detection accuracy can be improved.

The various abnormalities that can be detected in this embodiment are as follows. Case: Damage or loss of the communication pipe 28 or the supply pipe 38 Under negative pressure, there is damage or inflow of air from the dropout portion, but under positive pressure, there is outflow into the atmosphere, so the result in S360 is "YES". , It is possible to report an abnormality.

Case: Bending, crushing, etc. in the communication pipe 28 or the supply pipe 38. Even if a negative pressure is introduced, the pressure does not decrease, or it takes time for the pressure to decrease, so "NO" in S240, S2
At 50, the result is "YES", and the abnormality can be reported.

Case: The purge control valve 40 cannot be opened. Negative pressure cannot be introduced.
If "40" is "NO", and if S250 is "YES", an abnormality can be reported. In this unopenable state, the fuel gas adsorbed by the adsorbent in the canister cannot be introduced into the intake pipe 2, and thereafter, the fuel gas adsorbing ability of the adsorbent is exceeded, and the fuel gas is released from the atmospheric holes. Case: Drop of supply pipe 42 Negative pressure from the intake pipe 2 cannot be introduced, and as in the case, "NO" in S240 and "Y" in S250.
It becomes "ES", and the abnormality can be notified. It should be noted that the case is not a blockage but a dropout, which is a mistake as the type of abnormality, but the object of the present invention can be achieved if the abnormality can be accurately determined, which is sufficient.

Case: Bending, crushing, etc. in the supply pipe 42 This is exactly the same as the case, and "NO" in S240 and "YES" in S250 based on the negative pressure introduction situation.
Then, the abnormality can be reported. As in the case, the state of this case is also an abnormality that needs to be detected, because fuel gas may be released from the air holes.

Case: Blocking the air hole 36 of the canister 30 This abnormality does not immediately cause a large pressure increase such as crushing or bending of the rubber hose. When the supply pipes 38, 42 are crushed, the fuel gas cannot be purged even if the purge control valve 40 is opened, but the purge control valve 40 is opened even if the atmosphere hole 36 of the canister 30 is blocked. This is because the fuel gas is sometimes purged as such. Therefore, an abnormality in which the atmospheric hole 36 of the canister 30 remains blocked is not configured to be immediately known from the abnormality detection routine described above, but there is no serious problem. If necessary, the tank internal pressure P can be determined by the processing in S340 of the above-described abnormality detection routine.
As soon as 2 "is detected, the canister closing valve 37 is opened, and if the pressure does not quickly return to the vicinity of the atmospheric pressure, it may be determined that there is an abnormal closing of the atmosphere hole 36.

Case: state in which the purge control valve 40 cannot be closed When this abnormality occurs, the fuel gas is always introduced into the supply pipe 2, but the secondary state as in the case where it cannot be opened is generated. From the viewpoint of preventing the evaporation of the fuel gas, it does not have to be abnormal because the fuel gas is not released from the air holes. Therefore, in the above-described embodiment, no particular method for detecting this abnormality is provided. If necessary, S2
When ΔP1 calculated in 10 becomes equal to or lower than the predetermined negative pressure, it may be determined that the purge control valve 40 cannot be closed.

Case: Damaged state such as cracks in the supply pipe 42. Since the supply pipe 42 is a portion through which the fuel gas passes only when the purge control valve 40 is opened, even if there are cracks or holes. However, this only acts in the same manner as the atmospheric hole 36 of the canister 30, and it is needless to say that it is not abnormal from the viewpoint of preventing fuel gas evaporation. Therefore, although this cannot be detected in the above embodiment, there is no problem.

It can be said that the cases 1 to 3 are common in that the abnormality can be judged based on the pressure change state after or when the pressure in the closed section is adjusted to a predetermined pressure.

Next, a second embodiment will be described. The second embodiment has the same configuration and processing as those of the above-described embodiments, but is characterized in that a pressure sensor 100 of the type shown in FIG. 9 is adopted.

The main body of this pressure sensor 100 is the cup 1
01 and the cap 103 are fitted to each other. The pressure introducing pipe 10 that opens into the fuel tank 22 is provided in the cup 101.
5 is provided, and one of the caps 103 is provided with an electric wire guide tube 107 for connecting a measuring electric wire. The inside of the cup 101 and the cap 103 is divided into two parts by a diaphragm 109 fitted and fixed between them.
A cup 101 and a cap 103 are provided in the divided space.
Stoppers 111 and 11 protruding from the inner walls of the respective
3 and the moving range of the diaphragm 109 is restricted.

The diaphragm 109 is made of fluororubber (FK
M) having a thickness of 150 μ to 250 μ reinforced with a base fabric. Pressure receiving plates 115 and 117 are fixed to both surfaces of the diaphragm 109. And stopper 1
The pressure receiving plates 115 and 117 are in contact with 11 and 113. Further, springs 119 and 121 are in contact with the pressure receiving plates 115 and 117 from above and below. Due to the balance between these springs 119 and 121 and the pressure introduced from the pressure introducing pipe 105, the diaphragm 109
Between the stoppers 111 and 113 is the fuel tank 22.
It stops at a position proportional to the internal pressure of.

Pressure receiving plate 115 on the side of the wire guide tube 107
A rare earth magnet 123 is fixed to the center of the. A hybrid IC 127 including a Hall element 125 is arranged at a position facing the rare earth magnet 123, and the displacement of the diaphragm 109, that is, the pressure in the fuel tank 22 is detected by the output of the Hall element 125.

In this pressure sensor 100, the fuel tank 2
When the pressure in 2 changes, the diaphragm 109 moves up and down in proportion to this. Therefore, the distance between the Hall element 125 and the rare earth magnet 123 changes, and the magnetic flux entering the Hall element 125 changes. As a result, from the Hall element 125,
A change in the output voltage occurs corresponding to a change in the magnetic flux, that is, a change in the distance from the rare earth magnet 123.

FIG. 10 shows the relationship between the Hall element output voltage and the magnet displacement amount. Although the Hall element 125 itself has a linearity of 2%, the Hall element output voltage and the magnet displacement amount are not linear as shown.
Further, the output voltage of the Hall element 125 itself is about 100 mV, but since the distance from the fuel tank 22 to the electronic control circuit 50 is considerable, if the output is not amplified, it will be output on the electronic control circuit 50 side due to noise or the like. It may not be possible to determine.

For this reason, in this embodiment, the hybrid IC 127 incorporates the amplifier circuit and the linear approximation circuit shown in FIG. The amplification circuit is Hall element 1
The temperature correction circuit 131 is connected to the battery input terminal of 25, and the amplifier 133 is connected to the output of the Hall element 125. Further, the linear approximation circuit is configured such that a plurality of comparators 137 receiving the output signal of the amplifier 133 at one input terminal and receiving the reference voltages E1, E2, ... At the other input terminal are connected in parallel.
Each comparator 137 inputs a signal to the output unit 139. The terminal 141 of the output unit 139 and the electronic control circuit 50 are connected by a measuring wire, and the output voltage from the hall element 125 is amplified and linearly approximated and input to the electronic control circuit 50.

As shown in FIG. 12, the pressure sensor 100 shares the battery line + B and the ground line GND with the fuel pump 24, and is attached to the upper plate 221 of the fuel tank 22 via the gasket 223 and the pump flange 225. It is fixed so as to penetrate through. The fuel pump 24 is suspended via the pump bracket 231 so as to be located in the sub tank 229 fixed to the lower plate 227 of the fuel tank 22, and the fuel sucked from the fuel filter 233 is discharged from the discharge pipe 235. It is a thing. Next to the discharge pipe 235 is a return pipe 237.

The fuel tank 22 of the pressure sensor 100
The mounting position to is not limited to this, as shown in FIG.
Sender flange 2 to which the remaining amount warning lamp 251 and the fuel sender 255 of the float 253 type are attached
It may be attached through 57, or may be attached to a passage portion between the fuel tank 22 and the canister 30.

Although the pressure sensor 100 of this embodiment is mounted at a position where it is exposed to moisture, gum, etc. from the fuel tank 22, as described above, the displacement amount of the rare earth magnet 123 is changed to a hole. Since the rubber diaphragm having a thickness of 150 μm to 250 μm measured by the element 125 is used, the operation of the diaphragm 109 due to the adhesion of moisture or the like is not much affected as compared with the semiconductor pressure sensor. Further, since it is not necessary to use an extremely thin diaphragm like a semiconductor pressure sensor, there is no risk of damage due to freezing.

As a result, highly reliable pressure detection can be performed for a long period of time, and abnormality detection in the fuel transpiration prevention device can be accurately performed. Although a rare earth magnet is used as the magnet in this embodiment, it may be a ferrite magnet.

The present invention is not limited to the embodiments as described above, and can be carried out in various modes without departing from the scope of the present invention. For example, canister 3
The pressure sensor 44 may be attached to a section between 0 and the intake pipe 2. In this case as well, it is possible to detect the presence or absence of the cause of leakage in the entire closed section based on the pressure change state after the closed section is configured.

When adjusting the measurement start pressure after sealing, the negative pressure may be introduced by a completely different means, instead of opening and closing the purge control valve 40 to introduce the negative pressure. In addition, the atmospheric pressure change amount ΔP1 and the negative pressure change amount ΔP
Instead of comparing with 2, it is also possible to compare ΔP1 and ΔP2 with each other as the pressure change amount from the positive pressure above atmospheric pressure, or conversely with each other as the pressure change amount from the negative pressure. You may. If the pressure value at the start of measurement is different, the leak rate from the damaged part will be different.Therefore, the pressure adjustment condition in the sealed section may be the pressure equal to or higher than the atmospheric pressure or the negative pressure. This is because it is possible to detect the presence or absence of a leak cause in the closed section by paying attention to the difference.

Next, a third embodiment will be described. S3 in FIG.
At 60, regardless of the amount of fuel in the fuel tank 22,
Although the criterion for determining the leak is determined, as shown by the solid line in FIG. 14, even if the leak diameter in the closed section from the fuel tank 22 to the purge control valve 40 is constant, the fuel tank 22
The amount of change in the internal pressure of the fuel tank 22 largely changes depending on the internal space volume, that is, the fuel amount. Therefore, the supply abnormality is detected with reference to the time when the space volume of the fuel tank 22 where the pressure change is smallest is large (when the fuel amount is small).
Then, when the space volume of the fuel tank 22 is small (when the amount of fuel is large), the abnormality is excessively detected even when the pressure changes in the case where the leak diameter is small and is not considered abnormal.

Therefore, as shown by the broken line in FIG. 14, the criterion for determining the leak is changed according to the amount of fuel.
It is possible to accurately determine the leak diameter. In order to perform such control, FIG. 15 is provided between S350 and S360 of FIG.
Add step. That is, in S351, the fuel amount Fu in the fuel tank 22 is read by the output of the fuel sensor 255, and in the next S352, the fuel tank 2 stored in advance according to the read fuel amount Fu.
The correction coefficient γ corresponding to the space volume of 2 is obtained. And
In the next S360,

[0073]

[Formula 2] If ΔP2> a · ΔP1 + β + γ, it is determined that there is a leak. Here, the correction coefficient γ is set to increase as the space volume decreases so that the determination reference changes as indicated by the broken line in FIG. 14 in response to changes in the space volume of the fuel tank 22. Of course.

Next, as a fourth embodiment, an abnormality detection control during vehicle running will be described. This embodiment is shown in FIG.
5 is the same as that of the third embodiment of the present invention, but it is possible to detect an abnormality by sensing the fuel sender internal pressure fluctuations that occur during running or turning on a rough road by the fuel sender 255. It is characterized by judging whether it should be done.

An example of the abnormality detection possible judgment by the fuel sender 255 will be described below. Fuel sender 255
Is output to the CPU, and the fuel sender 255 is supplied every predetermined time (for example, every 256 msec) from the start of the abnormality detection or only during the calculation of ΔP1 or ΔP2.
It is determined whether the output of is within a predetermined range. When the output of the fuel sender 255 is out of the predetermined range, the detection is stopped even during the abnormality detection. Further, the above-mentioned predetermined range is based on the output of the fuel sender 255 at the start of abnormality detection, and is on the + side and − with respect to the reference value Fu _B.
It is assumed that the sides have the same width ω.

As another example of the above-mentioned method of setting the predetermined range, the fuel sender 2 during the calculation of ΔP1 or ΔP2
The smoothed value of the output of 55 can be used as the reference value. However, in this case, the abnormality detection possible determination is ΔP1 or ΔP2.
Only under calculation.

Next, the flow chart of the fourth embodiment will be described with reference to FIG. In S101, the fuel amount Fu in the fuel tank 22 is read by the output of the fuel sender 255, and then the process proceeds to S102 where the fuel amount Fu is the reference value F.
The comparison within the range of u _B ± ω is performed to determine whether or not the abnormality detection is possible.

If it is determined to be "YES" here, the flow proceeds to S120, and the processing is continued in the same manner as in the above-described embodiment. When it is determined to be "NO", the processing is ended as it is. In the above-described flow, the output of the fuel sender 255 is judged from the start to the end of the abnormality detection. However, if the judgment is made only during the calculation of ΔP1 or ΔP2, the same as in S101 before reading the pressure. Processing may be performed.

FIG. 17 shows the structure of the canister portion in the fifth embodiment of the present invention, which is used in place of the canister 30 and the canister shutoff valve 37 in FIG. In FIG. 17, the first check valve 302 is provided between the introduction port 15 of the canister 30 and the introduction pipe 301 that connects the adsorption body 34.
The first check valve 302 is arranged such that the pressure in the fuel tank is a predetermined value from the atmospheric pressure, for example, 15 mmHg.
When the temperature becomes higher than the above, it is opened to introduce the fuel gas in the fuel tank into the canister 30. Further, second and third check valves 303 and 304 in opposite directions are arranged in parallel between the introduction port 15 of the canister 30 and the hose connecting portion 32a forming the derivation port, and the hose of the canister 30 is further arranged. A canister shutoff valve 37 is arranged between the connecting portion 32a and the suction port 37a in the canister 30.

According to the embodiment shown in FIG. 17, the canister closing valve 37 is opened during the normal running of the vehicle so that the intake pipe negative pressure (100 mmHg) higher than that of the internal combustion engine is generated.
Above) is the canister shutoff valve 37 and the hose connection portion 32a
The second check valve 303 is closed because it is introduced into the canister 30 via the. Fuel gas is generated in the fuel tank as the fuel temperature rises, and when the pressure exceeds the opening pressure of the first check valve 302, the first check valve 302 is opened and the fuel gas in the fuel tank is absorbed by the adsorbent of the canister 30. Adsorbed by 34. Here, the third check valve 304 is opened when the pressure in the fuel tank becomes lower than the atmospheric pressure by a predetermined value (for example, 12 mmHg) or more, and the atmosphere is introduced into the fuel tank through the kinaster 30 from the atmosphere port 36, This is to prevent deformation of the fuel tank.

When the canister closing valve 37 is closed to detect the abnormality of the evaporative purge system, the second check valve 303 has a larger intake pipe negative pressure (10) than that of the internal combustion engine.
0mmHg or more), this second check valve 3
0 is in an open state, and this intake pipe negative pressure is supplied to the fuel tank via the second check valve 303. At this time, since the fuel tank side has a negative pressure, the first check valve 302 is closed, so that the adsorbent 34 of the canister 30 can be bypassed and the evaporation purge system can be sealed.

FIG. 18 shows the structure of the canister portion in the sixth embodiment of the present invention, which is used in place of the canister 30 and the canister shutoff valve 37 in FIG. In FIG. 18, the canister 30 is divided into two chambers by partition walls 30b and 30c, the adsorbents 34A and 34B are housed in the respective chambers, and substantially has two canister portions. .. Then, the filter 15 is arranged on the upper surface of the adsorbent 34B facing the atmosphere port 36. Also, each partition 3
The rooms partitioned by 0b and 30c are connected via a switching valve 32.

[0083]

As described in detail above, according to the abnormality detecting device for a fuel evaporation preventing device of the present invention, it is possible to accurately detect an abnormality in the entire fuel evaporation preventing device from the fuel tank to the intake pipe.

In particular, according to the abnormality detecting device for a fuel evaporation prevention device of the second aspect, when there is an abnormality causing a leak such as damage anywhere in the entire fuel evaporation prevention device from the fuel tank to the intake pipe. This can be reliably detected.

Further, according to the third aspect of the present invention, if there is a blockage abnormality such as a hose crushed anywhere in the entire fuel evaporation prevention device from the fuel tank to the intake pipe, this can be reliably detected. be able to.

In addition, according to the apparatus of claim 4, it is possible to use a sensor having a high pressure detection sensitivity, and it is possible to improve the accuracy of abnormality detection. Further, according to the apparatus of claim 5, in realizing each of the inventions of claims 1 to 4, the pressure sensor does not cause an error during use, and always performs highly reliable abnormality detection. be able to.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram illustrating a basic configuration of the present invention.

FIG. 2 is a schematic configuration diagram of an abnormality detection device for a fuel evaporation prevention device according to an embodiment.

FIG. 3 is a cross-sectional view showing a schematic configuration of a canister blocking valve.

FIG. 4 is a cross-sectional view showing a schematic configuration of a purge control valve.

FIG. 5 is a graph showing characteristics of duty control in the purge control valve.

FIG. 6 is a flowchart of abnormality detection processing.

FIG. 7 is a flowchart of abnormality detection processing.

FIG. 8 is a timing chart exemplifying a state during execution of abnormality detection processing.

FIG. 9 is a cross-sectional view showing a schematic configuration of a pressure sensor adopted in the second embodiment.

FIG. 10 is a graph showing the relationship between the output voltage of the Hall element used in the pressure sensor of the second embodiment and the amount of magnet displacement.

FIG. 11 is a circuit configuration diagram in the hybrid IC in the pressure sensor of the second embodiment.

FIG. 12 is a sectional view illustrating the mounting relationship of the pressure sensor of the second embodiment.

FIG. 13 is a cross-sectional view illustrating another mounting relationship of the pressure sensor of the second embodiment.

FIG. 14 is a graph showing the characteristics of the fuel tank spatial volume and tank internal pressure change in the third embodiment.

FIG. 15 is a flowchart of a main part of abnormality detection processing according to the third embodiment.

FIG. 16 is a flowchart of an abnormality detection process in the fourth embodiment.

FIG. 17 is a diagram showing a structure of a canister portion in a fifth embodiment.

FIG. 18 is a diagram showing a structure of a canister portion in a sixth embodiment.

[Explanation of symbols]

 2 intake pipe 6 accelerator pedal 8 throttle valve 22 fuel tank 22a relief valve 28 communication pipe 30 canister 34 adsorbent 36 atmosphere hole 37 canister blocking valve 38 supply pipe 40 purge control valve 42 supply pipe 44 pressure sensor 50 electronic control circuit 62 throttle sensor 64 Idle switch 66 Vehicle speed sensor 100 Pressure sensor 109 Diaphragm 115, 117 Pressure receiving plate 123 Rare earth magnet 125 Hall element 127 Hybrid IC

Claims (9)

[Claims] 1. A fuel gas generated in a fuel tank is adsorbed at any time by an adsorbent of a canister provided in the middle of a purge passage that connects a fuel tank and an intake pipe, and purge control is performed according to an operating state of an internal combustion engine. A fuel vaporization prevention device for appropriately introducing the adsorbed fuel gas into the intake pipe to prevent vaporization of fuel by opening and closing a valve; pressure detection means for detecting a pressure state in the fuel vaporization prevention device; An abnormality detecting device for a fuel evaporation prevention device, comprising: an abnormality detecting device for detecting an abnormality of a fuel evaporation preventing device based on a detection result of a pressure detecting device; A sealing means for closing the purge control valve and the air hole closing means together to form the entire fuel evaporation prevention device as one closed section; and adjusting the pressure in the closed section to a predetermined pressure. And a pressure change state measuring means for measuring a predetermined pressure change state during or after pressure adjustment by the closed zone pressure adjusting means, wherein the abnormality detecting means is An abnormality detection device for a fuel transpiration prevention device, which detects an abnormality of the fuel transpiration prevention device from a changed state. 2. The abnormality detection device for a fuel transpiration prevention device according to claim 1, wherein the closed section pressure adjusting means adjusts the pressure in the closed section by switching between a first predetermined pressure and a second predetermined pressure. The pressure change state measuring means respectively measures a first pressure change state after being adjusted to the first predetermined pressure and a second pressure change state after being adjusted to a second predetermined pressure. The abnormality detecting device for a fuel evaporation preventing apparatus is characterized in that the abnormality detecting means detects an abnormality of the fuel evaporation preventing apparatus by comparing the first and second pressure change states. 3. The fuel vaporization prevention device abnormality detection device according to claim 1, wherein the closed section pressure adjusting means introduces a negative pressure from the vicinity of the end portion on the intake pipe side, and the pressure change state measuring means includes: Measuring the pressure change state at the time of introducing the negative pressure, the abnormality detecting means detects the abnormality of the fuel evaporation prevention device based on the pressure change state at the time of introducing the negative pressure, fuel evaporation prevention Device abnormality detection device. 4. The abnormality detection device for a fuel evaporation prevention device according to claim 1, wherein the pressure detection means is arranged in a section from the fuel tank to the canister. Abnormality detection device for fuel evaporation prevention device. 5. The fuel vaporization prevention device abnormality detection device according to claim 1, wherein the pressure detection means is attached to the displacement member that is displaced according to the pressure. An abnormality detection device for a fuel transpiration prevention device comprising a magnetic member and a Hall element that changes an output based on a displacement of the magnetic member. 6. The fuel evaporation prevention apparatus abnormality detection device according to claim 1, wherein the fuel amount detection means detects the fuel amount in the fuel tank, and the fuel detected by the fuel amount detection means. An abnormality detecting device for a fuel transpiration prevention device, comprising: an abnormality determining reference changing means for changing a determination reference for detecting an abnormality of the abnormality detecting means according to an amount thereof. 7. The fuel vaporization prevention device abnormality detection device according to claim 1, wherein the fuel amount detection means detects the fuel amount in the fuel tank, and the fuel detected by the fuel amount detection means. A fuel fluctuation detecting means for judging whether or not the fuel quantity is fluctuating, and when the fuel quantity is fluctuating, for substantially canceling the abnormality detection by the abnormality detecting means. Abnormality detection device for prevention device. 8. The abnormality detection device for a fuel evaporation preventer according to claim 1, wherein the canister substantially has two canister parts, and the two canister parts are the air holes. It is connected through the closing means. 9. The abnormality detection device for a fuel transpiration prevention device according to claim 1, wherein the atmospheric hole closing means is arranged in the canister, and when the atmospheric hole closing means is closed. An abnormality detection device for a fuel transpiration prevention device, comprising a check valve means for bypassing the adsorbent and communicating between the introduction port and the derivation port of the canister.